WorldWideScience

Sample records for sinking particulate organic

  1. Molecular distribution and degradation status of combined aldoses in sinking particulate organic matter

    Science.gov (United States)

    Panagiotopoulos, C.; Sempéré, R.

    2003-04-01

    Particulate samples were collected by using floating sediment traps (50--300 m) and in situ pumps (30 and 200 m) in the Southern Indian Ocean (Polar Front Zone (PFZ) and Sub-Tropical Zone (STZ)), Mediterranean Sea (Ligurian and Ionian Seas) and Atlantic Ocean (Upwelling (UPW) of Agadir-Morocco). They were studied for monosaccharide composition after acid hydrolysis (HCl 0.09 M, 20 h, 100^oC) by using High Performance Anion Exchange Chromatography followed by Pulsed Amperometric Detection (HPAEC-PAD). Our results indicated that higher PCHO yields (calculated as PCHO-C/POC ratios) were associated to higher C:N ratios (Med. Sea sample, PCHO yields = 12.7 ± 7.7%; C:N ratios = 8.3 ± 1.6; n = 12) whether the opposite trend was found for Southern Ocean samples (PCHO yields = 3.3 ± 0.75%; C:N ratios = 5.7 ± 0.59, n = 5) indicating significant variability in the sugar content of particles which might be due to the degradation degree of the particles as well as to the initial chemical composition of plankton. Alternatively, other processes such as high production of extracellular polysaccharides (type transparent exopolymer polysaccharides (TEP)) due to phosphorus limitation of some phytoplanktonic species may increase the sugar content in Mediterranean particles and the C/N ratio. In any case, glucose appeared to be the most abundant monosaccharide in Mediterranean Sea or UPW samples (range 23--59 wt% of the total aldoses) whereas ribose (17--39 wt%) and galactose (range 10--28 wt%) were the predominant aldoses in Southern Indian Ocean. These sugars (glucose + ribose) exhibited a strong negative relationship with C:N (r = -0.53, p >0.01; n = 30) in sediment traps (data from this study) and sediment (data from literature) particulate material which further indicates that these two monosaccharides are selectively extracted from the carbohydrate pool in sediment. In vitro biodegradation experiments performed with large particles (>60 μm) sampled using in situ pumps in

  2. Impacts of the Changjiang diluted water on sinking processes of particulate organic matters in the East China Sea

    Science.gov (United States)

    Sukigara, Chiho; Mino, Yoshihisa; Tripathy, Sarat Chandra; Ishizaka, Joji; Matsuno, Takeshi

    2017-12-01

    Intensive surveys with repeated CTD and microstructure turbulent observations, water and sediments sampling as well as onboard incubation and sediment trap experiments were conducted to reveal the nitrogen budget in the center of the East China Sea (ECS) during July 2010 and 2011. Low salinity water (Changjiang Diluted Water, CDW) covered the study area in 2010, but not in 2011. Higher chlorophyll a (chl. a) concentration, primary productivity, and downward particle flux in the upper layer were observed in 2010 than those in 2011. Existence of the CDW resulted in a steep pycnocline and an associated subsurface chl. a maximum (SCM) layer directly beneath the CDW. From chemical analyses of particulate carbon and nitrogen contents and isotope ratios, it became apparent that the particles sunk out the euphotic zone in 2010 was primarily originated in the CDW layer and secondly in the SCM layer. Whereas, in 2011, sinking particles were originated in the surface layer but a part of them were decomposed in the bottom of pycnocline. Our findings indicate that the CDW would supply particles into the deep layer and contribute to the downward transport of materials and the efficiency of biological pump in the ECS.

  3. Satellite observation of particulate organic carbon dynamics in ...

    Science.gov (United States)

    Particulate organic carbon (POC) plays an important role in coastal carbon cycling and the formation of hypoxia. Yet, coastal POC dynamics are often poorly understood due to a lack of long-term POC observations and the complexity of coastal hydrodynamic and biogeochemical processes that influence POC sources and sinks. Using field observations and satellite ocean color products, we developed a nw multiple regression algorithm to estimate POC on the Louisiana Continental Shelf (LCS) from satellite observations. The algorithm had reliable performance with mean relative error (MRE) of ?40% and root mean square error (RMSE) of ?50% for MODIS and SeaWiFS images for POC ranging between ?80 and ?1200 mg m23, and showed similar performance for a large estuary (Mobile Bay). Substantial spatiotemporal variability in the satellite-derived POC was observed on the LCS, with high POC found on the inner shelf (satellite data with carefully developed algorithms can greatly increase

  4. Regulation of assimilate import into sink organs: Update on molecular drivers of sink strength

    Directory of Open Access Journals (Sweden)

    Saadia eBihmidine

    2013-06-01

    Full Text Available Recent developments have altered our view of molecular mechanisms that determine sink strength, defined here as the capacity of non-photosynthetic structures to compete for import of photoassimilates. We review new findings from diverse systems, including stems, seeds, flowers, and fruits. An important advance has been the identification of new transporters and facilitators with major roles in the accumulation and equilibration of sugars at a cellular level. Exactly where each exerts its effect varies among systems. Sugarcane and sweet sorghum stems, for example, both accumulate high levels of sucrose, but may do so via different paths. The distinction is central to strategies for targeted manipulation of sink strength using transporter genes, and shows the importance of system-specific analyses. Another major advance has been the identification of deep hypoxia as a feature of normal grain development. This means that molecular drivers of sink strength in endosperm operate in very low oxygen levels, and under metabolic conditions quite different than previously assumed. Successful enhancement of sink strength has nonetheless been achieved in grains by up-regulating genes for starch biosynthesis. Additionally, our understanding of sink strength is enhanced by awareness of the dual roles played by invertases (INV, not only in sucrose metabolism, but also in production of the hexose sugar signals that regulate cell-cycle and cell-division programs. These contributions of INV to cell expansion and division prove to be vital for establishment of young sinks ranging from flowers to fruit. Since INV genes are themselves sugar-responsive feast genes, they can mediate a feed-forward enhancement of sink strength when assimilates are abundant. Greater overall productivity and yield have thus been attained in key instances, indicating that even broader enhancements may be achievable as we discover the detailed molecular mechanisms that drive sink strength

  5. Lability of Secondary Organic Particulate Matter

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Pengfei; Li, Yong Jie; Wang, Yan; Giles, Mary K.; Zaveri, Rahul A.; Bertram, Allan K.; Martin, Scot T.

    2016-10-24

    Accurate simulations of the consenctrations of atmospheric organic particulate matter (PM) are needed for predicting energy flow in the Earth’s climate system. In the past, simulations of organic PM widely assume equilibrium partitioning of semivolatile organic compounds (SVOCs) between the PM and surrounding vapor. Herein, we test this assumption by measuring evaporation rates and associated vapor mass concentration of organic films representative of atmospheric PM. For films representing anthropogenic PM, evaporation rates and vapor mass concentrations increased above a threshold relative humidity (RH), indicating equilibrium partitioning above a transition RH but not below. In contrast for films representing biogenic PM, no threshold was observed, indicating equilibrium partitioning at all RHs. The results suggest that the mass lability of atmospheric organic PM can differ in consequential ways among Earth’s natural biomes, polluted regions, and regions of land-use change, and these differences need to be considered when simulating atmospheric organic PM.

  6. Erosion of organic carbon in the Arctic as a geological carbon dioxide sink.

    Science.gov (United States)

    Hilton, Robert G; Galy, Valier; Gaillardet, Jérôme; Dellinger, Mathieu; Bryant, Charlotte; O'Regan, Matt; Gröcke, Darren R; Coxall, Helen; Bouchez, Julien; Calmels, Damien

    2015-08-06

    Soils of the northern high latitudes store carbon over millennial timescales (thousands of years) and contain approximately double the carbon stock of the atmosphere. Warming and associated permafrost thaw can expose soil organic carbon and result in mineralization and carbon dioxide (CO2) release. However, some of this soil organic carbon may be eroded and transferred to rivers. If it escapes degradation during river transport and is buried in marine sediments, then it can contribute to a longer-term (more than ten thousand years), geological CO2 sink. Despite this recognition, the erosional flux and fate of particulate organic carbon (POC) in large rivers at high latitudes remains poorly constrained. Here, we quantify the source of POC in the Mackenzie River, the main sediment supplier to the Arctic Ocean, and assess its flux and fate. We combine measurements of radiocarbon, stable carbon isotopes and element ratios to correct for rock-derived POC. Our samples reveal that the eroded biospheric POC has resided in the basin for millennia, with a mean radiocarbon age of 5,800 ± 800 years, much older than the POC in large tropical rivers. From the measured biospheric POC content and variability in annual sediment yield, we calculate a biospheric POC flux of 2.2(+1.3)(-0.9) teragrams of carbon per year from the Mackenzie River, which is three times the CO2 drawdown by silicate weathering in this basin. Offshore, we find evidence for efficient terrestrial organic carbon burial over the Holocene period, suggesting that erosion of organic carbon-rich, high-latitude soils may result in an important geological CO2 sink.

  7. Forest vegetation as a sink for atmospheric particulates: Quantitative studies in rain and dry deposition

    International Nuclear Information System (INIS)

    Russel, I.J.; Choquette, C.E.; Fang, S.; Dundulis, W.P.; Pao, A.A.; Pszenny, A.A.P.

    1981-01-01

    Radionuclides in the atmosphere are associated with nonradioactive air particulates and hence serve to trace the fluxes of air particulates to various surfaces. Natural and artificial radioactivities found in the atmosphere have been measured in vegetation for 10 years to elucidate some of the mechanisms of acquirement by forest trees of atmospheric particulates. Whole tree analysis, in conjunction with soil assay, have served to establish the fraction of the flux of radionuclides retained by above-ground tissues of a forest stand. Interpretation is facilitated because most radionuclides in the atmosphere are superficially acquired. Typically 5--20% of the total open field flux is retained by the forest canopy in a moderately rainy climate (120 cm/year). Short-lived daughters of radon give a dry deposition velocity of particulates in the Aitken size range of 0.03--0.05 cm/s, thus permitting an estimate of transient removal by forest canopies by dry deposition of this size fraction

  8. Temporal and spatial variations in particulate matter, particulate organic carbon and attenuation coefficient in Cochin Backwaters

    Digital Repository Service at National Institute of Oceanography (India)

    Devi, K.S.

    Nine stations over a stretch of 21 km of Periyar river estuary were sampled during January to December 1981. Particulate matter varied from 3-253 mg.1 super(1) at the surface and 24.8-257mg.1 super(1) at the bottom. Particulate organic carbon ranged...

  9. Observations on particulate organic nitrates and unidentified components of NOy

    DEFF Research Database (Denmark)

    Nielsen, T.; Egeløv, A.H.; Granby, K.

    1995-01-01

    A method to determine the total content of particulate organic nitrates (PON) has been developed and ambient air measurements of PON, NO, NO2, HNO3, peroxyacetyl nitrate (PAN), peroxypropionyl nitrate (PPN), gas NOy and particulate inorganic nitrate have been performed in the spring and early...... summer al an agricultural site in Denmark and compared with measurements of ozone, H2O2, SO2, formic acid, acetic acid and methane sulphonic acid. The gas NOy detector determines the sum NO + NO2 + HNO2 + HNO3 + PAN + PPN + gas phase organic nitrates + 2 x N2O5 + NO3. The content of residual gas NOy...... = gas NOy + particulate inorganic nitrate). Residual gas NOy was much higher than the particulate fraction of organic nitrates (PON). PON was only 0.25 +/- 0.11% of concentrations of photochemical oxidants in connection with high-pressure systems suggesting atmospheric processes being the major source...

  10. Semivolatile Particulate Organic Material Southern Africa during SAFARI 2000

    Science.gov (United States)

    Eatough, D. J.; Eatough, N. L.; Pang, Y.; Sizemore, S.; Kirchstetter, T. W.; Novakov, T.

    2005-01-01

    During August and September 2000, the University of Washington's Cloud and Aerosol Research Group (CARG) with its Convair-580 research aircraft participated in the Southern African Fire-Atmosphere Research Initiative (SAFARI) 2000 field study in southern Africa. Aboard this aircraft was a Particle Concentrator-Brigham Young University Organic Sampling System (PC-BOSS), which was used to determine semivolatile particulate material with a diffusion denuder sampler. Denuded quartz filters and sorbent beds in series were used to measure nonvolatile and semivolatile materials, respectively. Results obtained with the PC-BOSS are compared to those obtained with conventional quartz-quartz and Teflon-quartz filter pack samplers. Various 10-120 min integrated samples were collected during flights through the h e troposphere, in the atmospheric boundary layer, and in plumes from savanna fires. Significant fine particulate semivolatile organic compounds (SVOC) were found in all samples. The SVOC was not collected by conventional filter pack samplers and therefore would not have been determined in previous studies that used only filter pack samplers. The SVOC averaged 24% of the fine particulate mass in emissions from the fires and 36% of the fine particulate mass in boundary layer samples heavily impacted by aged emissions from savanna fires. Concentrations of fine particulate material in the atmospheric mixed layer heavily impacted by aged savanna frre emissions averaged 130 micrograms per cubic meter. This aerosol was 85% carbonaceous mated.

  11. Particulate organic nitrates: Sampling and night/day variation

    DEFF Research Database (Denmark)

    Nielsen, T.; Platz, J.; Granby, K.

    1998-01-01

    Atmospheric day and night concentrations of particulate organic nitrates (PON) and several other air pollutants were measured in the summer 1995 over an open-land area in Denmark. The sampling of PON was evaluated comparing 24 h samples with two sets of 12 h samples. These results indicate...... that the observed low contribution of PON to NO, is real and not the result of an extensive loss during the sampling. Empirical relationships between the vapour pressure and chemical formula of organic compounds were established in order to evaluate the gas/particle distribution of organic nitrates. A positive...

  12. Aged riverine particulate organic carbon in four UK catchments

    International Nuclear Information System (INIS)

    Adams, Jessica L.; Tipping, Edward; Bryant, Charlotte L.; Helliwell, Rachel C.; Toberman, Hannah; Quinton, John

    2015-01-01

    The riverine transport of particulate organic matter (POM) is a significant flux in the carbon cycle, and affects macronutrients and contaminants. We used radiocarbon to characterise POM at 9 riverine sites of four UK catchments (Avon, Conwy, Dee, Ribble) over a one-year period. High-discharge samples were collected on three or four occasions at each site. Suspended particulate matter (SPM) was obtained by centrifugation, and the samples were analysed for carbon isotopes. Concentrations of SPM and SPM organic carbon (OC) contents were also determined, and were found to have a significant negative correlation. For the 7 rivers draining predominantly rural catchments, PO 14 C values, expressed as percent modern carbon absolute (pMC), varied little among samplings at each site, and there was no significant difference in the average values among the sites. The overall average PO 14 C value for the 7 sites of 91.2 pMC corresponded to an average age of 680 14 C years, but this value arises from the mixing of differently-aged components, and therefore significant amounts of organic matter older than the average value are present in the samples. Although topsoil erosion is probably the major source of the riverine POM, the average PO 14 C value is appreciably lower than topsoil values (which are typically 100 pMC). This is most likely explained by inputs of older subsoil OC from bank erosion, or the preferential loss of high- 14 C topsoil organic matter by mineralisation during riverine transport. The significantly lower average PO 14 C of samples from the River Calder (76.6 pMC), can be ascribed to components containing little or no radiocarbon, derived either from industrial sources or historical coal mining, and this effect is also seen in the River Ribble, downstream of its confluence with the Calder. At the global scale, the results significantly expand available information for PO 14 C in rivers draining catchments with low erosion rates. - Highlights:

  13. Aged riverine particulate organic carbon in four UK catchments

    Energy Technology Data Exchange (ETDEWEB)

    Adams, Jessica L., E-mail: jesams@ceh.ac.uk [Centre for Ecology and Hydrology, Lancaster Environment Centre, Lancaster, LA1 4AP (United Kingdom); Tipping, Edward, E-mail: et@ceh.ac.uk [Centre for Ecology and Hydrology, Lancaster Environment Centre, Lancaster, LA1 4AP (United Kingdom); Bryant, Charlotte L., E-mail: charlotte.bryant@glasgow.ac.uk [NERC Radiocarbon Facility, East Kilbride G75 0QF, Scotland (United Kingdom); Helliwell, Rachel C., E-mail: rachel.helliwell@hutton.ac.uk [The James Hutton Institute, Craigiebuckler, Aberdeen AB15 8QH Scotland (United Kingdom); Toberman, Hannah, E-mail: hannahtoberman@hotmail.com [Centre for Ecology and Hydrology, Lancaster Environment Centre, Lancaster, LA1 4AP (United Kingdom); School of Environmental Sciences, University of Liverpool, Liverpool L69 3GP (United Kingdom); Quinton, John, E-mail: j.quinton@lancaster.ac.uk [Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ (United Kingdom)

    2015-12-01

    The riverine transport of particulate organic matter (POM) is a significant flux in the carbon cycle, and affects macronutrients and contaminants. We used radiocarbon to characterise POM at 9 riverine sites of four UK catchments (Avon, Conwy, Dee, Ribble) over a one-year period. High-discharge samples were collected on three or four occasions at each site. Suspended particulate matter (SPM) was obtained by centrifugation, and the samples were analysed for carbon isotopes. Concentrations of SPM and SPM organic carbon (OC) contents were also determined, and were found to have a significant negative correlation. For the 7 rivers draining predominantly rural catchments, PO{sup 14}C values, expressed as percent modern carbon absolute (pMC), varied little among samplings at each site, and there was no significant difference in the average values among the sites. The overall average PO{sup 14}C value for the 7 sites of 91.2 pMC corresponded to an average age of 680 {sup 14}C years, but this value arises from the mixing of differently-aged components, and therefore significant amounts of organic matter older than the average value are present in the samples. Although topsoil erosion is probably the major source of the riverine POM, the average PO{sup 14}C value is appreciably lower than topsoil values (which are typically 100 pMC). This is most likely explained by inputs of older subsoil OC from bank erosion, or the preferential loss of high-{sup 14}C topsoil organic matter by mineralisation during riverine transport. The significantly lower average PO{sup 14}C of samples from the River Calder (76.6 pMC), can be ascribed to components containing little or no radiocarbon, derived either from industrial sources or historical coal mining, and this effect is also seen in the River Ribble, downstream of its confluence with the Calder. At the global scale, the results significantly expand available information for PO{sup 14}C in rivers draining catchments with low erosion rates

  14. Organic speciation of size-segregated atmospheric particulate matter

    Science.gov (United States)

    Tremblay, Raphael

    Particle size and composition are key factors controlling the impacts of particulate matter (PM) on human health and the environment. A comprehensive method to characterize size-segregated PM organic content was developed, and evaluated during two field campaigns. Size-segregated particles were collected using a cascade impactor (Micro-Orifice Uniform Deposit Impactor) and a PM2.5 large volume sampler. A series of alkanes and polycyclic aromatic hydrocarbons (PAHs) were solvent extracted and quantified using a gas chromatograph coupled with a mass spectrometer (GC/MS). Large volume injections were performed using a programmable temperature vaporization (PTV) inlet to lower detection limits. The developed analysis method was evaluated during the 2001 and 2002 Intercomparison Exercise Program on Organic Contaminants in PM2.5 Air Particulate Matter led by the US National Institute of Standards and Technology (NIST). Ambient samples were collected in May 2002 as part of the Tampa Bay Regional Atmospheric Chemistry Experiment (BRACE) in Florida, USA and in July and August 2004 as part of the New England Air Quality Study - Intercontinental Transport and Chemical Transformation (NEAQS - ITCT) in New Hampshire, USA. Morphology of the collected particles was studied using scanning electron microscopy (SEM). Smaller particles (one micrometer or less) appeared to consist of solid cores surrounded by a liquid layer which is consistent with combustion particles and also possibly with particles formed and/or coated by secondary material like sulfate, nitrate and secondary organic aerosols. Source apportionment studies demonstrated the importance of stationary sources on the organic particulate matter observed at these two rural sites. Coal burning and biomass burning were found to be responsible for a large part of the observed PAHs during the field campaigns. Most of the measured PAHs were concentrated in particles smaller than one micrometer and linked to combustion sources

  15. Composition of Sinking Particulates Collected under Fast Ice near Syowa Station, East Antarctica, in Early Spring and Early Summer, 1994

    Directory of Open Access Journals (Sweden)

    Ryoko Saito

    1998-11-01

    Full Text Available Sinking particles collected in several sediment trap experiments near Syowa Station in austral spring-summer in 1994 have been microscopically analyzed. From the features of the shape and morphology, collected particles were identified, enumerated and measured, and the flux of each identified species was estimated. The majority of the particles were composed of diatom cells and "fecal pellet"-like aggregates were recognized in the samples. In spring, the particle fluxes were rather low and higher fluxes were detected in summer. In particular, diatom cell flux increased by two order of magnitude. The composition of the sinking particles varied seasonally; a centric diatom, Corethron criophilum, and round-shape fecal pellets accounted for dominant diatom cell and fecal pellet fluxes in the spring. But pennate diatoms and collumn-shape pellets dominated in summer. The vertical flux varied, too. In spite of the significant difference of total bio-volume flux between spring and summer (>30 times higher in summer, the bio-volume ratio, such as total identified diatoms and fecal pellets, stayed rather constant.

  16. Sorption of polycyclic aromatic hydrocarbons on particulate organic matters

    International Nuclear Information System (INIS)

    Guo Xueyan; Luo Lei; Ma Yibing; Zhang Shuzhen

    2010-01-01

    Particulate organic matter (POM) is a key organic matter fraction which can influence soil fertility. Its interactions with hydrophobic organic pollutants (HOCs) have not been characterized and the mechanisms of retention of HOCs by POM remain unclear. In the present study, sorption behaviors of polycyclic aromatic hydrocarbons (PAHs) naphthalene (NAP), phenanthrene (PHE), and pyrene (PYR) by POMs separated from different soils were examined and the POMs were characterized by elemental analysis, solid state 13 C NMR, and Fourier transform infrared spectroscopy (FT-IR). The results indicated that POMs were mainly composed of aliphatic components with high polarity. The different original POMs showed similar chemical composition and configuration. Sorption behaviors of PAHs indicated that there was no significant difference in sorption capacity among the POMs. Sorption of NAP and PHE by POMs displayed a nonlinear isotherm, while sorption of PYR yielded a linear isotherm. No significant hysteresis and ionic strength effect were observed for PAH desorption from the POMs.

  17. Temperature dependence of photodegradation of dissolved organic matter to dissolved inorganic carbon and particulate organic carbon

    Czech Academy of Sciences Publication Activity Database

    Porcal, Petr; Dillon, P. J.; Molot, L. A.

    2015-01-01

    Roč. 10, č. 6 (2015), e0128884 E-ISSN 1932-6203 R&D Projects: GA ČR(CZ) GAP503/12/0781; GA ČR(CZ) GA15-09721S Institutional support: RVO:60077344 Keywords : dissolved organic carbon * particulate organic carbon * photodegradation * temperature Subject RIV: DA - Hydrology ; Limnology Impact factor: 3.057, year: 2015

  18. Coarse Particulate Organic Matter: Storage, Transport, and Retention

    Energy Technology Data Exchange (ETDEWEB)

    Tiegs, Scott [Oakland University, Rochester, MI; Lamberti, Gary A. [University of Notre Dame, IN; Entrekin, Sally A. [University of Central Arkansas; Griffiths, Natalie A. [ORNL

    2017-08-01

    Coarse particulate organic matter, or CPOM, is a basal energy and nutrient resource in many stream ecosystems and is provided by inputs from the riparian zone, incoming tributaries, and to a lesser extent from in-stream production. The ability of a stream to retain CPOM or slow its transport is critical to its consumption and assimilation by stream biota. In this chapter, we describe basic exercises to measure (1) the amount of CPOM in the streambed and (2) the retention of CPOM from standardized particle releases. We further describe advanced exercises that (1) experimentally enhance the retentiveness of a stream reach and (2) measure organic carbon transport and turnover (i.e., spiraling) in the channel.

  19. Coarse Particulate Organic Matter: Storage, Transport, and Retention

    Energy Technology Data Exchange (ETDEWEB)

    Tiegs, Scott [Oakland University, Rochester, MI; Lamberti, Gary A. [University of Notre Dame, IN; Entrekin, Sally A. [University of Central Arkansas; Griffiths, Natalie A. [ORNL

    2017-06-01

    Coarse particulate organic matter, or CPOM, is a basal energy and nutrient resource in many stream ecosystems and is provided by inputs from the riparian zone, incoming tributaries, and to a lesser extent from in-stream production. The ability of a stream to retain CPOM or slow its transport is critical to its consumption and assimilation by stream biota. In this chapter, we describe basic exercises to measure (1) the amount of CPOM in the streambed and (2) the retention of CPOM from standardized particle releases. We further describe advanced exercises that (1) experimentally enhance the retentiveness of a stream reach and (2) measure organic carbon transport and turnover (i.e., spiraling) in the channel.

  20. Changes in the sedimentation histories of lakes using Pb-210 as a tracer of sinking particulate matter

    International Nuclear Information System (INIS)

    Barnes, R.S.; Birch, P.B.; Spyridakis, D.E.; Schell, W.R.

    1978-01-01

    A detailed study of man's impact over the last 150 years on six lakes in Western Washington State has been made using Pb-210 dating methods and historical records. These lakes represent a gradient in watershed usage from pristine natural environments to heavily urbanized areas. Fine structures in the sediment profiles of Pb-210 measurements were found to correlate with changing watershed land use. Contemporary sedimentation rates varied from 50-679 g/m 2 x a (0.37-2.9 mm/a) and were generally higher than precultural rates. The highest average sedimentation rates (1230-1800 g/m 2 x a or 5.6-8.3 mm/a) were simultaneous with suburbanization. Construction of roads and houses appeared to be the major cause of increased erosion in the watersheds. The present day sediments of all lakes were enriched in lead compared to older background material. The stable lead profiles from all lakes except Lake Union were consistent with the local history of lead pollution based on the Pb-210 geochronologies. Water column residence times for Pb-210 and stable lead were almost identical and were consistent with algal settling rates and the sinking rates of fine silts and clays. (orig.) [de

  1. Fluxes of particulate organic carbon in the East China Sea in summer

    Directory of Open Access Journals (Sweden)

    C.-C. Hung

    2013-10-01

    Full Text Available To understand carbon cycling in marginal seas better, particulate organic carbon (POC concentrations, POC fluxes and primary production (PP were measured in the East China Sea (ECS in summer 2007. Higher concentrations of POC were observed in the inner shelf, and lower POC values were found in the outer shelf. Similar to POC concentrations, elevated uncorrected POC fluxes (720–7300 mg C m−2 d−1 were found in the inner shelf, and lower POC fluxes (80–150 mg C m−2 d−1 were in the outer shelf, respectively. PP values (~ 340–3380 mg C m−2 d−1 had analogous distribution patterns to POC fluxes, while some of PP values were significantly lower than POC fluxes, suggesting that contributions of resuspended particles to POC fluxes need to be appropriately corrected. A vertical mixing model was used to correct effects of bottom sediment resuspension, and the lowest and highest corrected POC fluxes were in the outer shelf (58 ± 33 mg C m−2 d−1 and the inner shelf (785 ± 438 mg C m−2 d−1, respectively. The corrected POC fluxes (486 to 785 mg C m−2 d−1 in the inner shelf could be the minimum value because we could not exactly distinguish the effect of POC flux from Changjiang influence with turbid waters. The results suggest that 27–93% of the POC flux in the ECS might be from the contribution of resuspension of bottom sediments rather than from the actual biogenic carbon sinking flux. While the vertical mixing model is not a perfect model to solve sediment resuspension because it ignores biological degradation of sinking particles, Changjiang plume (or terrestrial inputs and lateral transport, it makes significant progress in both correcting the resuspension problem and in assessing a reasonable quantitative estimate of POC flux in a marginal sea.

  2. How reservoirs alter drinking water quality: Organic matter sources, sinks, and transformations

    Science.gov (United States)

    Kraus, Tamara E.C.; Bergamaschi, Brian A.; Hernes, Peter J.; Doctor, Daniel H.; Kendall, Carol; Downing, Bryan D.; Losee, Richard F.

    2011-01-01

    Within reservoirs, production, transformation, and loss of dissolved organic matter (DOM) occur simultaneously. While the balance between production and loss determines whether a reservoir is a net sink or source of DOM, changes in chemical composition are also important because they affect DOM reactivity with respect to disinfection by-product (DBP) formation. The composition of the DOM pool also provides insight into DOM sources and processing, which can inform reservoir management. We examined the concentration and composition of DOM in San Luis Reservoir, a large off-stream impoundment of the California State Water Project. We used a wide array of DOM chemical tracers including dissolved organic carbon (DOC) concentration, trihalomethane and haloacetic acid formation potentials (THMFP and HAAFP, respectively), absorbance properties, isotopic composition, lignin phenol content, and structural groupings determined by 13C nuclear magnetic resonance (NMR). There were periods when the reservoir was a net source of DOC due to the predominance of algal production (summer), a net sink due to the predominance of degradation (fall–winter), and balanced between production and consumption (spring). Despite only moderate variation in bulk DOC concentration (3.0–3.6 mg C/L), changes in DOM composition indicated that terrestrial-derived material entering the reservoir was being degraded and replaced by aquatic-derived DOM produced within the reservoir. Substantial changes in the propensity of the DOM pool to form THMs and HAAs illustrate that the DBP precursor pool was not directly coupled to bulk DOC concentration and indicate that algal production is an important source of DBP precursors. Results suggest reservoirs have the potential to attenuate DOM amount and reactivity with respect to DBP precursors via degradative processes; however, these benefits can be decreased or even negated by the production of algal-derived DOM.

  3. Identifying the source, transport path and sinks of sewage derived organic matter

    International Nuclear Information System (INIS)

    Mudge, Stephen M.; Duce, Caroline E.

    2005-01-01

    Since sewage discharges can significantly contribute to the contaminant loadings in coastal areas, it is important to identify sources, pathways and environmental sinks. Sterol and fatty alcohol biomarkers were quantified in source materials, suspended sediments and settling matter from the Ria Formosa Lagoon. Simple ratios between key biomarkers including 5β-coprostanol, cholesterol and epi-coprostanol were able to identify the sewage sources and effected deposition sites. Multivariate methods (PCA) were used to identify co-varying sites. PLS analysis using the sewage discharge as the signature indicated ∼ 25% of the variance in the sites could be predicted by the sewage signature. A new source of sewage derived organic matter was found with a high sewage predictable signature. The suspended sediments had relatively low sewage signatures as the material was diluted with other organic matter from in situ production. From a management viewpoint, PLS provides a useful tool in identifying the pathways and accumulation sites for such contaminants. - Multivariate statistical analysis was used to identify pathways and accumulation sites for contaminants in coastal waters

  4. Atmospheric oxidative chemistry of organic particulate emissions from fuel combustion.

    Science.gov (United States)

    2011-03-25

    "Construction and characterization of the University of Vermont Environmental Chamber (UVMEC) : were completed in this last phase of the project. The primary function of the UVMEC is to enable : tropospheric particulate formation and aging studies to...

  5. Fine particulate matter (PM) and organic speciation of fireplace emissions

    International Nuclear Information System (INIS)

    Purvis, C.R.; McCrillis, R.C.; Kariher, P.H.

    2000-01-01

    This paper presents a summary of fireplace particle size and organic speciation data gathered to date in an ongoing project. Tests are being conducted in a residential wood combustion (RWC) laboratory on three factory-built fireplaces. RWC wood smoke particles <10 microm (PM10) consist primarily of a mixture of organic compounds that have condensed into droplets; therefore, the size distribution and total mass are influenced by temperature of the sample during its collection. During the series 1 tests (15 tests), the dilution tunnel used to cool and dilute the stack gases gave an average mixed gas temperature of 47.3 C and an average dilution ration of 4.3. Averages for the PM2.5 (particles <2.5 microm) and PM10 fractions were 74 and 84%, respectively. For the series 2 tests, the dilution tunnel was modified, reducing the average mixed gas temperatures to 33.8 C and increasing the average dilution ratio to 11.0 in tests completed to date. PM2.5 and PM10 fractions were 83 and 91%, respectively. Since typical winter-time mixed gas temperatures would usually be less than 10 C, these size fraction results probably represent the lower bound; the PM10 and PM2.5 size fraction results might be higher at typical winter temperatures. The particles collected on the first stage were light gray and appeared to include inorganic ash. Particles collected on the remainder of the stages were black and appeared to be condensed organics because there was noticeable lateral bleeding of the collected materials into the filter substrate. Total particulate emission rates ranged from 10.3 to 58.4 g/h; corresponding emission factors ranged from 3.3 to 14.9 g/kg of dry wood burned. A wide range of Environmental Protection Agency (EPA) Method 8270 semivolatile organic compounds were found in the emissions; of the 17 target compounds quantified, major constituents are phenol, 2-methylphenol, 4-methylphenol, 2,4-dimethylphenol, and naphthalene

  6. Long-term Trends in Particulate Organic Carbon from a Low-Gradient Autotrophic Watershed

    Science.gov (United States)

    Fox, J.; Ford, W. I., III

    2014-12-01

    Recent insights from low-gradient streams dominated by fine surficial sediments have shown fluvial organic matter dynamics are governed by coupled hydrologic and biotic controls at event to seasonal timescales. Notwithstanding the importance of shorter timescales, quantity and quality of carbon in stream ecosystems at annual and decadal scales is of increased interest in order to understand if stream ecosystems are net stores or sinks of carbon and how stream carbon behaves under dynamic climate conditions. As part of an ongoing study in a low-gradient, agricultural watershed in the Bluegrass Region of Central Kentucky, an eight year dataset of transported particulate organic carbon (POC) was analyzed for the present study. The objective was to investigate if POC dynamics at multi-year timescales are governed by biotic or hydrologic processes. A statistical analysis using Empirical Mode Decomposition was performed on an 8 year dataset of transported sediment carbon, temperature, and log-transformed flowrates at the watershed outlet. Simulations from a previously validated, process-based, organic carbon model were utilized as further verification of drivers. Results from the analysis suggest that a 4 degree Celsius mean annual temperature shift corresponds to a 63% increase in organic carbon content at the main-stem, third order outlet and a 33% increase in organic carbon content at the main-stem inlet. Model and stable isotope results for the 8 year study support that long-term increases in organic carbon concentration are governed by biotic growth and humification of algal biomass in which increasing annual temperatures promote increased organic carbon production, relative to ecosystem respiration. This result contradicts conventional wisdom, suggesting projected warming trends will shift autotrophic freshwater systems to net heterotrophic, which has significant implications for the role of benthic stream ecosystems under changing climate conditions. Future work

  7. Chlorophyll 'a' particulate organic carbon and suspended load from the mangrove areas of Cochin backwaters

    Digital Repository Service at National Institute of Oceanography (India)

    Sheeba, P.; Devi, K.S.; Balasubramanian, T.; Sankaranarayanan, V.N.

    Chlorophyll 'a' Particulate Organic Carbon and suspended load were estimated for one year from two distinct mangrove areas of Cochin backwaters, viz. Puthuvypeen and Nettoor. Environmental parameters like tau degrees C, S ppt and pH were also...

  8. SEASONAL ABUNDANCE OF ORGANIC MOLECULAR MARKERS IN URBAN PARTICULATE MATTER FROM PHILADELPHIA, PA

    Science.gov (United States)

    Organic molecular markers were measured in airborne particulate matter (PM10) from the City of Philadelphia North Broad Street air quality monitoring site to identify the seasonal abundances of key tracer compounds together with their dominant sources. Daily PM10...

  9. Distribution and sources of particulate organic matter in the Indian monsoonal estuaries during monsoon

    Digital Repository Service at National Institute of Oceanography (India)

    Sarma, V.V.S.S.; Krishna, M.S.; Prasad, V.R.; Kumar, B.S.K.; Naidu, S.A.; Rao, G.D.; Viswanadham, R.; Sridevi, T.; Kumar, P.P.; Reddy, N.P.C.

    The distribution and sources of particulate organic carbon (POC) and nitrogen (PN) in 27 Indian estuaries were examined during the monsoon using the content and isotopic composition of carbon and nitrogen. Higher phytoplankton biomass was noticed...

  10. Can particulate organic matter reveal emerging changes in soil organic carbon?

    DEFF Research Database (Denmark)

    Simonsson, Magnus; Kirchmann, Holger; Magid, Jakob

    2014-01-01

    different cropping systems, N fertilizer applications, and organic amendments, we found that C and N in the fine to medium sand fraction (0.063-0.600 mm, "Fraction B") showed considerably larger relative errors according to ANOVA (RMSE was 11-20% of the mean), slightly lower values of the F statistic......This study assessed whether particulate organic matter (POM) in sand fractions, isolated by wet sieving after treatment with Na hexametaphosphate, can be a sensitive indicator of incipient changes in the content and composition of soil organic matter. In five long-term field experiments including......, and slightly less contrast between treatments than total organic C and N (RMSE 3-9% of the mean). Imprecision in laboratory procedures only explained part of the increase in RMSE for C and N in Fraction B compared with total C and N; within-field spatial variability most likely had a greater influence...

  11. Natural dissolved organic matter dynamics in karstic aquifer: O'Leno Sink-Rise system, Florida, USA

    Science.gov (United States)

    Jin, J.; Zimmerman, A. R.

    2010-12-01

    Natural dissolved organic matter (NDOM) dynamics in karstic aquifer remain poorly understood due to the inaccessibility and heterogeneity of the subsurface. Because the Santa Fe River sinks into the Floridan Aquifer and emerges 6 km down gradient, the O'Leno Sink-Rise system in Northern Florida provides an ideal setting to study NDOM transformation in groundwater. Water samples were collected at both high and low temporal resolutions over 3 years from the River Sink, Rise, and a series of shallow and deep wells. Analyses of dissolved organic and inorganic carbon, stable isotopic, and spectrophotometry (excitation-emission matrix or EEM) show that reversals of hydrologic head gradient in the conduit and matrix are closely related to the delivery of NDOM to the aquifer. In addition, the relative influence of biotic and abiotic processes varies along spatiotemporal gradients; regions of the aquifer with greatest connectivity to surface water (new NDOM and terminal electron acceptor supply) see the most microbial transformation of NDOM, while those with least connectivity see relatively greater abiotic transformation of NDOM. A source water mixing model was established for the Sink-Rise system using Mg2+ and SO42- concentrations from three end-members identified as allogenic recharge, upwelling deep water, and shallow groundwater of the Upper Floridan Aquifer. Biogeochemical processes were quantified after accounting for changes that occurred due to source water mixing, according to the model. In addition to NDOM remineralization by subsurface microbes which occurred mostly during wet periods, adsorption of NDOM onto aquifer materials as well as release of NDOM from aquifer materials was also observed. During wet periods when DOC-rich conduit water entered the matrix, progressive NDOM remineralization was found along the preferential flow paths from the conduits into the matrices. Both biotic and abiotic NDOM transformation processes were found to control channel

  12. Particulate organic matter in shelf waters of Prinsesse Asrid Kyst, Antarctica

    Digital Repository Service at National Institute of Oceanography (India)

    Dhargalkar, V.K.; Bhosle, N.B.

    In the coastal and estuarine waters of Goa, particulate organic carbon (POC) varied from 0.52 to 2.51 mg l-1 and from 0.28 to 5.24 mg l-1 and particulate phosphorus (PP) varied from 0.71 to 5.18 mu g l-1 and from 0.78 to 20.34 mu g l-1, respectively...

  13. Processes and modeling of hydrolysis of particulate organic matter in aerobic wastewater tratment - A review

    DEFF Research Database (Denmark)

    Morgenroth, Eberhard Friedrich; Kommedal, Roald; Harremoës, Poul

    2002-01-01

    Carbon cycling and the availability of organic carbon for nutrient removal processes are in most wastewater treatment systems restricted by the rate of hydrolysis of slowly biodegradable (particulate) organic matter. To date, the mechanisms of hydrolysis are not well understood for complex...

  14. Hydrolysis and degradation of filtrated organic particulates in a biofilm reactor under anoxic and aerobic conditions

    DEFF Research Database (Denmark)

    Janning, K.F.; Mesterton, K.; Harremoës, P.

    1997-01-01

    Two experiments were performed in order to investigate the anoxic and the aerobic degradation of filtrated organic matter in a biofilter. In submerged lab: scale reactors with Biocarbone media as filter material, accumulated particulate organic matter from pre-settled wastewater served as the only...

  15. Sinking rates and ballast composition of particles in the Atlantic Ocean: implications for the organic carbon fluxes to the deep ocean

    Science.gov (United States)

    Fischer, G.; Karakaş, G.

    2009-01-01

    The flux of materials to the deep sea is dominated by larger, organic-rich particles with sinking rates varying between a few meters and several hundred meters per day. Mineral ballast may regulate the transfer of organic matter and other components by determining the sinking rates, e.g. via particle density. We calculated particle sinking rates from mass flux patterns and alkenone measurements applying the results of sediment trap experiments from the Atlantic Ocean. We have indication for higher particle sinking rates in carbonate-dominated production systems when considering both regional and seasonal data. During a summer coccolithophorid bloom in the Cape Blanc coastal upwelling off Mauritania, particle sinking rates reached almost 570 m per day, most probably due the fast sedimentation of densely packed zooplankton fecal pellets, which transport high amounts of organic carbon associated with coccoliths to the deep ocean despite rather low production. During the recurring winter-spring blooms off NW Africa and in opal-rich production systems of the Southern Ocean, sinking rates of larger particles, most probably diatom aggregates, showed a tendency to lower values. However, there is no straightforward relationship between carbonate content and particle sinking rates. This could be due to the unknown composition of carbonate and/or the influence of particle size and shape on sinking rates. It also remains noticeable that the highest sinking rates occurred in dust-rich ocean regions off NW Africa, but this issue deserves further detailed field and laboratory investigations. We obtained increasing sinking rates with depth. By using a seven-compartment biogeochemical model, it was shown that the deep ocean organic carbon flux at a mesotrophic sediment trap site off Cape Blanc can be captured fairly well using seasonal variable particle sinking rates. Our model provides a total organic carbon flux of 0.29 Tg per year down to 3000 m off the NW African upwelling

  16. Evidence of molybdenum association with particulate organic matter under sulfidic conditions

    DEFF Research Database (Denmark)

    Dahl, Tais Wittchen; Chappaz, A.; Hoek, Joost

    2017-01-01

    , consisting of mainly Mo(IV)-sulfide compounds with molecular structures similar to Mo enzymes and to those found in natural euxinic sediments. Therefore, we propose that Mo removal in natural sulfidic waters can proceed via a non-Fe-assisted pathway that requires particulate organic matter (dead or living......The geochemical behavior of molybdenum (Mo) in the oceans is closely linked to the presence of sulfide species in anoxic environments, where Fe availability may play a key role in the Mo scavenging. Here, we show that Mo(VI) is reduced in the presence of particulate organic matter (represented...

  17. Particulate organic matter predicts bacterial productivity in a river dominated estuary

    Science.gov (United States)

    Crump, B. C.

    2015-12-01

    Estuaries act as coastal filters for organic and inorganic fluvial materials in which microbial, biogeochemical, and ecological processes combine to transform organic matter and nutrients prior to export to the coastal ocean. The function of this estuarine 'bioreactor' is linked to the residence times of those materials and to rates of microbial heterotrophic activity. Our ability to forecast the impact of global change on estuarine bioreactor function requires an understanding of the basic controls on microbial community activity and diversity. In the Columbia River estuary, the microbial community undergoes a dramatic seasonal shift in species composition during which a spring bacterioplankton community, dominated by Flavobacteriaceae and Oceanospirillales, is replaced by a summer community, dominated by Rhodobacteraceae and several common marine taxa. This annual shift occurs in July, following the spring freshet, when river flow and river chlorophyll concentration decrease and when estuarine water residence time increases. Analysis of a large dataset from 17 research cruises (1990-2014) showed that the composition of particulate organic matter in the estuary changes after the freshet with decreasing organic carbon and nitrogen content, and increasing contribution of marine and autochthonous estuarine organic matter (based on PO13C and pigment ratios). Bacterial production rates (measured as leucine or thymidine incorporation rates) in the estuary respond to this change, and correlate strongly with labile particulate nitrogen concentration and temperature during individual sampling campaigns, and with the concentration of chlorophyll in the Columbia River across all seasons. Regression models suggest that the concentration of labile particulate nitrogen and the rate of bacterial production can be predicted from sensor measurements of turbidity, salinity, and temperature in the estuary and chlorophyll in the river. These results suggest that the quality of

  18. Chemical characterization of organic particulate matter from on-road traffic in Sao Paulo, Brazil

    NARCIS (Netherlands)

    Oyama, Beatriz Sayuri; Andrade, Maria de Fatima; Herckes, Pierre; Dusek, Ulrike; Rockmann, Thomas; Holzinger, Rupert

    2016-01-01

    This study reports emission of organic particulate matter by light-duty vehicles (LDVs) and heavy-duty vehicles (HDVs) in the city of Sao Paulo, Brazil, where vehicles run on three different fuel types: gasoline with 25% ethanol (called gasohol, E25), hydrated ethanol (E100), and diesel (with 5%

  19. Chemical characterization of organic particulate matter from on-road traffic in Sao Paulo, Brazil

    NARCIS (Netherlands)

    Oyama, Beatriz Sayuri; Andrade, Maria de Fatima; Herckes, Pierre; Dusek, Ulrike; Rockmann, Thomas; Holzinger, Rupert

    2016-01-01

    This study reports emission of organic particulate matter by light-duty vehicles (LDVs) and heavy-duty vehicles (HDVs) in the city of São Paulo, Brazil, where vehicles run on three different fuel types: gasoline with 25 % ethanol (called gasohol, E25), hydrated ethanol (E100), and diesel (with 5 %

  20. Chlorophyll a, Phaeopigments and particulate organic carbon in the northern and western Bay of Bengal

    Digital Repository Service at National Institute of Oceanography (India)

    Radhakrishna, K.; Bhattathiri, P.M.A.; Devassy, V.P.

    Distribution of chl a at surface closely corresponds to the surface flow patterns. Integral mean concentration (IMC) of chl a in inshore waters (depth 200 m) is double than that in the offshore waters (depth 200 m) while IMC of particulate organic...

  1. Satellite observation of particulate organic carbon dynamics on the Louisiana continental shelf

    Science.gov (United States)

    Particulate organic carbon (POC) plays an important role in coastal carbon cycling and the formation of hypoxia. Yet, coastal POC dynamics are often poorly understood due to a lack of long-term POC observations and the complexity of coastal hydrodynamic and biogeochemical process...

  2. Crude glycerol combustion: Particulate, acrolein, and other volatile organic emissions

    KAUST Repository

    Steinmetz, Scott; Herrington, Jason S.; Winterrowd, Chris K.; Roberts, William L.; Wendt, Jost O L; Linak, William P.

    2013-01-01

    to be formed from the low temperature thermal decomposition of glycerol. Currently, there is no known reliable method for measuring acrolein in sources. Acrolein and emissions of other volatile organic compounds were characterized through the use of a SUMMA

  3. The role of effective discharge in the ocean delivery of particulate organic carbon by small, mountainous river systems

    Science.gov (United States)

    Wheatcroft, R.A.; Goni, M.A.; Hatten, J.A.; Pasternack, G.B.; Warrick, J.A.

    2010-01-01

    Recent research has shown that small, mountainous river systems (SMRS) account for a significant fraction of the global flux of sediment and particulate organic carbon (POC) to the ocean. The enormous number of SMRS precludes intensive studies of the sort conducted on large systems, necessitating development of a conceptual framework that permits cross-system comparison and scaling up. Herein, we introduce the geomorphic concept of effective discharge to the problem of source-to-sink POC transport. This idea recognizes that transport effectiveness is the product of discharge frequency and magnitude, wherein the latter is quantified as a power-law relationship between discharge and load (the 'rating curve'). An analytical solution for effective discharge (Qe) identifies two key variables: the standard deviation of the natural logarithm of discharge (??q), and the rating exponent of constituent i (bi Data from selected SMRS are used to show that for a given river Qe-POC transport in SMRS should exploit the conceptual framework provided herein and seek to identify how constituent-specific effective discharges vary between rivers and respond to perturbations. ?? 2010, by the American Society of Limnology and Oceanography, Inc.

  4. Multispectral remote-sensing algorithms for particulate organic carbon (POC): The Gulf of Mexico

    OpenAIRE

    Son, Young Baek; Gardner, Wilford D.; Mishonov, Alexey V.; Richardson, Mary Jo

    2009-01-01

    To greatly increase the spatial and temporal resolution for studying carbon dynamics in the marine environment, we have developed remote-sensing algorithms for particulate organic carbon (POC) by matching in situ POC measurements in the Gulf of Mexico with matching SeaWiFS remote-sensing reflectance. Data on total particulate matter (PM) as well as POC collected during nine cruises in spring, summer and early winter from 1997-2000 as part of the Northeastern Gulf of Mexico (NEGOM) study were ...

  5. Vertical Distributions of Macromolecular Composition of Particulate Organic Matter in the Water Column of the Amundsen Sea Polynya During the Summer in 2014

    Science.gov (United States)

    Kim, Bo Kyung; Lee, SangHoon; Ha, Sun-Yong; Jung, Jinyoung; Kim, Tae Wan; Yang, Eun Jin; Jo, Naeun; Lim, Yu Jeong; Park, Jisoo; Lee, Sang Heon

    2018-02-01

    Macromolecular compositions (carbohydrates, proteins, and lipids) of particulate organic matter (POM) are crucial as a basic marine food quality. To date, however, one investigation has been carried out in the Amundsen Sea. Water samples for macromolecular compositions were obtained at selected seven stations in the Amundsen Sea Polynya (AP) during the austral summer in 2014 to investigate vertical characteristics of POM. We found that a high proportion of carbohydrates (45.9 ± 11.4%) in photic layer which are significantly different from the previous result (27.9 ± 6.9%) in the AP, 2012. The plausible reason could be the carbohydrate content strongly associated with biomass of the dominant species (Phaeocystis antarctica). The calorific content of food material (FM) in the photic layer obtained in this study is similar with that of the Ross Sea as one of the highest primary productivity regions in the Southern Ocean. Total concentrations, calorific values, and calorific contents of FM were higher in the photic layer than the aphotic layer, which implies that a significant fraction of organic matter underwent degradation. A decreasing proteins/carbohydrates (PRT/CHO) ratio with depth could be caused by preferential nitrogen loss during sinking period. Since the biochemical compositions of POM mostly fixed in photic layers could play an important role in transporting organic carbon into the deep sea, further detail studies on the variations in biochemical compositions and main controlling factors are needed to understand sinking mechanisms of POM.

  6. Differential responses of sugar, organic acids and anthocyanins to source-sink modulation in Cabernet Sauvignon and Sangiovese grapevines.

    Science.gov (United States)

    Bobeica, Natalia; Poni, Stefano; Hilbert, Ghislaine; Renaud, Christel; Gomès, Eric; Delrot, Serge; Dai, Zhanwu

    2015-01-01

    Grape berry composition mainly consists of primary and secondary metabolites. Both are sensitive to environment and viticultural management. As a consequence, climate change can affect berry composition and modify wine quality and typicity. Leaf removal techniques can impact berry composition by modulating the source-to-sink balance and, in turn, may mitigate some undesired effects due to climate change. The present study investigated the balance between technological maturity parameters such as sugars and organic acids, and phenolic maturity parameters such as anthocyanins in response to source-sink modulation. Sugar, organic acid, and anthocyanin profiles were compared under two contrasting carbon supply levels in berries of cv. Cabernet Sauvignon and Sangiovese collected at 9 and 14 developmental stages respectively. In addition, whole-canopy net carbon exchange rate was monitored for Sangiovese vines and a mathematic model was used to calculate the balance between carbon fixation and berry sugar accumulation. Carbon limitation affected neither berry size nor the concentration of organic acids at harvest. However, it significantly reduced the accumulation of sugars and total anthocyanins in both cultivars. Most interestingly, carbon limitation decreased total anthocyanin concentration by 84.3% as compared to the non source-limited control, whereas it decreased sugar concentration only by 27.1%. This suggests that carbon limitation led to a strong imbalance between sugars and anthocyanins. Moreover, carbon limitation affected anthocyanin profiles in a cultivar dependent manner. Mathematical analysis of carbon-balance indicated that berries used a higher proportion of fixed carbon for sugar accumulation under carbon limitation (76.9%) than under carbon sufficiency (48%). Thus, under carbon limitation, the grape berry can manage the metabolic fate of carbon in such a way that sugar accumulation is maintained at the expense of secondary metabolites.

  7. Differential responses of sugar, organic acids and anthocyanins to source-sink modulation in Cabernet Sauvignon and Sangiovese grapevines

    Directory of Open Access Journals (Sweden)

    Natalia eBobeica

    2015-05-01

    Full Text Available Grape berry composition mainly consists of primary and secondary metabolites. Both are sensitive to environment and viticultural management. As a consequence, climate change can affect berry composition and modify wine quality and typicity. Leaf removal techniques can impact berry composition by modulating the source-to-sink balance and, in turn, may mitigate some undesired effects due to climate change. The present study investigated the balance between technological maturity parameters such as sugars and organic acids, and phenolic maturity parameters such as anthocyanins in response to source-sink modulation. Sugar, organic acid, and anthocyanin profiles were compared under two contrasting carbon supply levels in berries of cv. Cabernet Sauvignon and Sangiovese collected at 9 and 14 developmental stages respectively. In addition, whole-canopy net carbon exchange rate was monitored for Sangiovese vines and a mathematic model was used to calculate the balance between carbon fixation and berry sugar accumulation. Carbon limitation affected neither berry size nor the concentration of organic acids at harvest. However, it significantly reduced the accumulation of sugars and total anthocyanins in both cultivars. Most interestingly, carbon limitation decreased total anthocyanin concentration by 84.3 % as compared to the non source-limited control, whereas it decreased sugar concentration only by 27.1 %. This suggests that carbon limitation led to a strong imbalance between sugars and anthocyanins. Moreover, carbon limitation affected anthocyanin profiles in a cultivar dependent manner. Mathematical analysis of carbon-balance indicated that berries used a higher proportion of fixed carbon for sugar accumulation under carbon limitation (76.9% than under carbon sufficiency (48%. Thus, under carbon limitation, the grape berry can manage the metabolic fate of carbon in such a way that sugar accumulation is maintained at the expense of secondary

  8. [Distribution and source of particulate organic carbon and particulate nitrogen in the Yangtze River Estuary in summer 2012].

    Science.gov (United States)

    Xing, Jian-Wei; Xian, Wei-Wei; Sheng, Xiu-Zhen

    2014-07-01

    Based on the data from the cruise carried out in August 2012 in the Yangtze River Estuary and its adjacent waters, spatial distributions of particulate organic carbon (POC), particulate nitrogen (PN) and their relationships with environmental factors were studied, and the source of POC and the contribution of phytoplankton to POC were analyzed combined with n (C)/n (N) ratio and chlorophyll a (Chl a) in the Yangtze River Estuary in summer 2012. The results showed that the concentrations of POC in the Yangtze River Estuary ranged from 0.68 mg x L(-1) to 34.80 mg x L(-1) in summer and the average content was 3.74 mg x L(-1), and PN contents varied between 0.03 mg x L(-1) and 9.13 mg x L(-1) with an average value of 0.57 mg x L(-1). Both of them presented that the concentrations in bottom layers were higher than those in the surface. POC and PN as well as total suspended matter (TSM) showed a extremel similar horizontal distribution trend that the highest values appeared in the near of the mouth and southwest of the survey waters, and decreased rapidly as toward the open seas, both of them showed higher contents in coastal zones and lower in outer sea. There was a fairly good positive linear relationship between POC and PN, which indicated that they had the same source. POC and PN expressed significantly positive correlations with TSM and chemical oxygen demand (COD), but showed relatively weak correlations with salinit and chlorophyll a, which demonstrated that terrestrial inputs had a strong influence on the distribution of POC and PN, and phytoplankton production was not the major source of organic matters in the Yangtze River Estuary. Both the n (C)/n (N) ratio and POC/Chl a analysis showed that the main source of POC was terrestrial inputs, and organic debris was the main existence form of POC. Quantitative analysis showed the biomass of phytoplankton only made an average of 2.54% contribution to POC in the Yangtze Rive Estuary in summer and non-living POC

  9. FINE PARTICULATE MATTER (PM) AND ORGANIC SPECIATION OF FIREPLACE EMISSIONS

    Science.gov (United States)

    This paper presents a summary of fireplace particle size and organic speciation data gathered to date in an on-going project. Tests are being conducted in a residential wood combustion (RWC) laboratory on three factory-built fireplaces. RWC wood smoke particles <10?m (PM10) con...

  10. Relating hygroscopicity and composition of organic aerosol particulate matter

    CERN Document Server

    Duplissy, J; Prevot, A S H; Barmpadimos, I; Jimenez, J L; Gysel, M; Worsnop, D R; Aiken, A C; Tritscher, T; Canagaratna, M R; Collins, D R; Alfarra, M R; Metzger, A; Tomlinson, J; DeCarlo, P F; Weingartner, E; Baltensperger, U

    2011-01-01

    A hygroscopicity tandem differential mobility analyzer (HTDMA) was used to measure the water uptake (hygroscopicity) of secondary organic aerosol (SOA) formed during the chemical and photochemical oxidation of several organic precursors in a smog chamber. Electron ionization mass spectra of the non-refractory submicron aerosol were simultaneously determined with an aerosol mass spectrometer (AMS), and correlations between the two different signals were investigated. SOA hygroscopicity was found to strongly correlate with the relative abundance of the ion signal m/z 44 expressed as a fraction of total organic signal (f(44)). m/z 44 is due mostly to the ion fragment CO(2)(+) for all types of SOA systems studied, and has been previously shown to strongly correlate with organic O/C for ambient and chamber OA. The analysis was also performed on ambient OA from two field experiments at the remote site Jungfrau-joch, and the megacity Mexico City, where similar results were found. A simple empirical linear relation b...

  11. Late summer particulate organic carbon export and twilight zone remineralisation in the Atlantic sector of the Southern Ocean

    Science.gov (United States)

    Planchon, F.; Cavagna, A.-J.; Cardinal, D.; André, L.; Dehairs, F.

    2013-02-01

    As part of the GEOTRACES Bonus-GoodHope (BGH) expedition (January-March 2008) in the Atlantic sector of the Southern Ocean, particulate organic carbon (POC) export was examined from the surface to the mesopelagic twilight zone using water column distributions of total 234Th and biogenic particulate Ba (Baxs). Surface POC export production was estimated from steady state and non steady state modelling of 234Th fluxes, which were converted into POC fluxes, using the POC/234Th ratio of large, potentially sinking particles (> 53 μm) collected via in situ pumps. Deficits in 234Th activities were observed at all stations from the surface to the bottom of the mixed layer, yielding 234Th export fluxes from the upper 100 m of 496 ± 214 dpm m-2 d-1 to 1195 ± 158 dpm m-2 d-1 for the steady state model and of 149 ±517 dpm m-2 d-1 to 1217 ± 231 dpm m-2 d-1 for the non steady state model. Using the POC/234Thp ratio of sinking particles (ratios varied from 1.7 ± 0.2 μmol dpm-1 to 4.8 ± 1.9 μmol dpm-1) POC export production at 100 m was calculated to range between 0.9 ± 0.4 and 5.1 ± 2.1 mmol C m-2 d-1,assuming steady state and between 0.3 ± 0.9 m-2 d-1 and 4.9 ± 3.3 mmol C m-2 d-1, assuming non steady state. From the comparison of both approaches, it appears that during late summer export decreased by 56 to 16% for the area between the sub-Antarctic zone and the southern Antarctic Circumpolar Current Front (SACCF), whereas it remained rather constant over time in the HNLC area south of the SACCF. POC export represented only 6 to 54% of new production, indicating that export efficiency was, in general, low, except in the vicinity of the SACCF, where export represented 56% of new production. Attenuation of the POC sinking flux in the upper mesopelagic waters (100-600 m depth interval) was evidenced both, from excess 234Th activities and from particulate biogenic Ba (Baxs) accumulation. Excess 234Th activities, reflected by 234Th/238U ratios as large as 1.21 ± 0

  12. Organic and inorganic carbon dynamics in a karst aquifer: Santa Fe River Sink-Rise system, north Florida, USA

    Science.gov (United States)

    Jin, Jin; Zimmerman, Andrew R.; Moore, Paul J.; Martin, Jonathan B.

    2014-03-01

    Spatiotemporal variations in dissolved organic carbon (DOC), dissolved inorganic carbon (DIC), major ions concentrations and other geochemical parameters including stable carbon isotopes of DIC (δ13CDIC), were measured in surface water and deep and shallow well water samples of the Santa Fe River Sink-Rise eogenetic karst system, north Florida, USA. Three end-member water sources were identified: one DOC-rich/DIC-poor/δ13CDIC-depleted, one DOC-poor/DIC-rich/δ13CDIC-enriched, and one enriched in major ions. Given their spatiotemporal distributions, they were presumed to represent soil water, upper aquifer groundwater, and deep aquifer water sources, respectively. Using assumed ratios of Na+, Cl, and SO42- for each end-member, a mixing model calculated the contribution of each water source to each sample. Then, chemical effects of biogeochemical reactions were calculated as the difference between those predicted by the mixing model and measured species concentrations. In general, carbonate mineral dissolution occurred throughout the Sink-Rise system, surface waters were net autotrophic and the subsurface was in metabolic balance, i.e., no net DOC or DIC production or consumption. However, there was evidence for chemolithoautotrophy, perhaps by hydrogen oxidizing microbes, at some deep aquifer sites. Mineralization of this autochthonous natural dissolved organic matter (NDOM) led to localized carbonate dissolution as did surface water-derived NDOM supplied to shallow well sites during the highest flow periods. This study demonstrates linkages between hydrology, abiotic and microbial processes and carbon dynamics and has important implications for groundwater quality, karst morphologic evolution, and hydrogeologic projects such as aquifer storage and recovery in karst systems.

  13. Hydrogenation of organic matter as a terminal electron sink sustains high CO 2 :CH 4 production ratios during anaerobic decomposition

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, Rachel M.; Tfaily, Malak M.; Rich, Virginia I.; Keller, Jason K.; Bridgham, Scott D.; Zalman, Cassandra Medvedeff; Meredith, Laura; Hanson, Paul J.; Hines, Mark; Pfeifer-Meister, Laurel; Saleska, Scott R.; Crill, Patrick; Cooper, William T.; Chanton, Jeff P.; Kostka, Joel E.

    2017-10-01

    Once inorganic electron acceptors are depleted, organic matter in anoxic environments decomposes by hydrolysis, fermentation, and methanogenesis, requiring syntrophic interactions between microorganisms to achieve energetic favorability. In this classic anaerobic food chain, methanogenesis represents the terminal electron accepting (TEA) process, ultimately producing equimolar CO2 and CH4 for each molecule of organic matter degraded. However, CO2:CH4 production in Sphagnum-derived, mineral-poor, cellulosic peat often substantially exceeds this 1:1 ratio, even in the absence of measureable inorganic TEAs. Since the oxidation state of C in both cellulose-derived organic matter and acetate is 0, and CO2 has an oxidation state of +4, if CH4 (oxidation state -4) is not produced in equal ratio, then some other compound(s) must balance CO2 production by receiving 4 electrons. Here we present evidence for ubiquitous hydrogenation of diverse unsaturated compounds that appear to serve as organic TEAs in peat, thereby providing the necessary electron balance to sustain CO2:CH4 >1. While organic electron acceptors have previously been proposed to drive microbial respiration of organic matter through the reversible reduction of quinone moieties, the hydrogenation mechanism that we propose, by contrast, reduces C-C double bonds in organic matter thereby serving as 1) a terminal electron sink, 2) a mechanism for degrading complex unsaturated organic molecules, 3) a potential mechanism to regenerate electron-accepting quinones, and, in some cases, 4) a means to alleviate the toxicity of unsaturated aromatic acids. This mechanism for CO2 generation without concomitant CH4 production has the potential to regulate the global warming potential of peatlands by elevating CO2:CH4 production ratios.

  14. Barium in Twilight Zone suspended matter as a potential proxy for particulate organic carbon remineralization: Results for the North Pacific

    Energy Technology Data Exchange (ETDEWEB)

    Dehairs, F.; Jacquet, S.; Savoye, N.; Van Mooy, B.A.S.; Buesseler, K.; Bishop, J.K.B.; Lamborg, C.H.; Elskens, M.; Baeyens, W.; Boyd, P.W.; Casciotti, K.L.; Monnin, C.

    2008-04-10

    This study focuses on the fate of exported organic carbon in the twilight zone at two contrasting environments in the North Pacific: the oligotrophic ALOHA site (22 degrees 45 minutes N 158 degrees W; Hawaii; studied during June-July 2004) and the mesotrophic Subarctic Pacific K2 site (47 degrees N, 161 degrees W; studied during July-August 2005). Earlier work has shown that non-lithogenic, excess particulate Ba (Ba{sub xs}) in the mesopelagic water column is a potential proxy of organic carbon remineralization. In general Ba{sub xs} contents were significantly larger at K2 than at ALOHA. At ALOHA the Ba{sub xs} profiles from repeated sampling (5 casts) showed remarkable consistency over a period of three weeks, suggesting that the system was close to being at steady state. In contrast, more variability was observed at K2 (6 casts sampled) reflecting the more dynamic physical and biological conditions prevailing in this environment. While for both sites Ba{sub xs} concentrations increased with depth, at K2 a clear maximum was present between the base of the mixed layer at around 50m and 500m, reflecting production and release of Ba{sub xs}. Larger mesopelagic Ba{sub xs} contents and larger bacterial production in the twilight zone at the K2 site indicate that more material was exported from the upper mixed layer for bacterial degradation deeper, compared to the ALOHA site. Furthermore, application of a published transfer function (Dehairs et al., 1997) relating oxygen consumption to the observed Ba{sub xs} data indicated that the latter were in good agreement with bacterial respiration, calculated from bacterial production. These results corroborate earlier findings highlighting the potential of Ba{sub xs} as a proxy for organic carbon remineralization. The range of POC remineralization rates calculated from twilight zone excess particulate Ba contents did also compare well with the depth dependent POC flux decrease as recorded by neutrally buoyant sediment traps

  15. Crude glycerol combustion: Particulate, acrolein, and other volatile organic emissions

    KAUST Repository

    Steinmetz, Scott

    2013-01-01

    Crude glycerol is an abundant by-product of biodiesel production. As volumes of this potential waste grow, there is increasing interest in developing new value added uses. One possible use, as a boiler fuel for process heating, offers added advantages of energy integration and fossil fuel substitution. However, challenges to the use of crude glycerol as a boiler fuel include its low energy density, high viscosity, and high autoignition temperature. We have previously shown that a refractory-lined, high swirl burner can overcome challenges related to flame ignition and stability. However, critical issues related to ash behavior and the possible formation of acrolein remained. The work presented here indicates that the presence of dissolved catalysts used during the esterification and transesterification processes results in extremely large amounts of inorganic species in the crude glycerol. For the fuels examined here, the result is a submicron fly ash comprised primarily of sodium carbonates, phosphates, and sulfates. These particles report to a well-developed accumulation mode (0.3-0.7 μm diameter), indicating extensive ash vaporization and particle formation via nucleation, condensation, and coagulation. Particle mass emissions were between 2 and 4 g/m3. These results indicate that glycerol containing soluble catalyst is not suitable as a boiler fuel. Fortunately, process improvements are currently addressing this issue. Additionally, acrolein is of concern due to its toxicity, and is known to be formed from the low temperature thermal decomposition of glycerol. Currently, there is no known reliable method for measuring acrolein in sources. Acrolein and emissions of other volatile organic compounds were characterized through the use of a SUMMA canister-based sampling method followed by GC-MS analysis designed for ambient measurements. Results indicate crude glycerol combustion produces relatively small amounts of acrolein (∼15 ppbv) and other volatile organic

  16. The Rusty Sink: Iron Promotes the Preservation of Organic Matter in Sediments

    Science.gov (United States)

    Lalonde, K. M.; Mucci, A.; Moritz, A.; Ouellet, A.; Gelinas, Y.

    2011-12-01

    The biogeochemical cycles of iron (Fe) and organic carbon (OC) are strongly interlinked. In oceanic waters, organic ligands have been shown to control the concentration of dissolved Fe [1], whereas in soils, solid Fe phases provide a sheltering and preservative effect for organic matter [2]. Until now however, the role of iron in the preservation of OC in sediments has not been clearly established. Here we show that 21.5 ± 8.6% of the OC in sediments is directly bound to reactive iron phases, which promote the preservation of OC in sediments. Iron-bound OC represents a global mass of 19 to 45 × 10^15 g of OC in surface marine sediments. This pool of OC is different from the rest of sedimentary OC, with 13C and nitrogen-enriched organic matter preferentially bound to Fe which suggests that biochemical fractionation occurs with OC-Fe binding. Preferential binding also affects the recovery of high molecular weight lipid biomarkers and acidic lignin oxidation products, changing the environmental message of proxies derived from these biomarkers. [1] Johnson, K. S., Gordon, R. M. & Coale, K. H. What controls dissolved iron in the world ocean? Marine Chemistry 57, 137-161 (1997). [2] Kaiser, K. & Guggenberger, G. The role of DOM sorption to mineral surfaces in the preservation of organic matter in soils. Organic Geochemistry 31, 711-725 (2000).

  17. Measurement of emissions of fine particulate organic matter from Chinese cooking

    Science.gov (United States)

    He, Ling-Yan; Hu, Min; Huang, Xiao-Feng; Yu, Ben-De; Zhang, Yuan-Hang; Liu, De-Quan

    Cooking emissions may contribute significantly to atmospheric organic particles in urban environment in China, and thus need to be examined first for its chemical compositions and characteristics. The particulate organic emissions of the two cooking styles of Chinese cuisine, that is, Hunan Cooking and Cantonese Cooking, were characterized in Shenzhen. More than half of the PM 2.5 mass is due to organic compounds, and over 90 species of organic compounds were identified and quantified, accounting for 26.1% of bulk organic particle mass and 20.7% of PM 2.5. Fatty acids, diacids and steroids were the major organic compounds emitted from both styles of cooking. Of the quantified organic mass, over 90% was fatty acids. The mass of organic species, and the molecular distribution of n-alkanes and PAHs indicated the dissimilarities between the two different cooking styles, but generally the major parts of the organic particulate emissions of the two restaurants were similar, showing less difference than between Chinese and American cooking.

  18. Analytical solutions for hydromagnetic natural convection flow of a particulate suspension through isoflux-isothermal channels in the presence of a heat source or sink

    International Nuclear Information System (INIS)

    Chamkha, Ali J.; Al-Rashidi, Seham S.

    2010-01-01

    This work considers the problem of steady natural convection hydromagnetic flow of a particulate suspension through an infinitely long channel in the presence of heat generation or absorption effects. The channel walls are maintained at isoflux-isothermal condition. That is, the thermal boundary conditions are such that one of the channel walls is maintained at constant heat flux while the other is maintained at a constant temperature. Various closed-form solutions of the governing equations for different special cases are obtained. A parametric study of the physical parameters involved in the problem is done to illustrate the influence of these parameters on the velocity and temperature profiles of both phases.

  19. Quality and Quantity of Particulate Organic Carbon in a Coral Reef at Tioman Island, Malaysia

    International Nuclear Information System (INIS)

    Nakajima, R.; Toda, T.; Shibata, A.

    2011-01-01

    The quality and quantity of particulate organic carbon (POC) were investigated in a fringing coral reef of Tioman Island, Malaysia to better understand the food sources for reef meso-zooplankton. Phytoplankton biomass in the water column was on average 0.22 (± 0.07) mg Chl-a m-3, of which pico phytoplankton was the most important (size <3 μm, 50-70 % of the total Chl-a). The proportion of C biomass by phytoplankton and other plankton to particulate organic carbon (POC) was low (6 % and 5 %, respectively) and the major portion of POC was occupied by detritus (89 %), suggesting that the diet of particle-feeding or suspension feeding meso-zooplankton would chiefly consist of detritus. (author)

  20. Input of particulate organic and dissolved inorganic carbon from the Amazon to the Atlantic Ocean

    OpenAIRE

    Druffel, E. R. M; Bauer, J. E; Griffin, S.

    2005-01-01

    We report concentrations and isotope measurements (radiocarbon and stable carbon) of dissolved inorganic carbon (DIC) and suspended particulate organic carbon (POC) in waters collected from the mouth of the Amazon River and the North Brazil Current. Samples were collected in November 1991, when the Amazon hydrograph was at its annual minimum and the North Brazil Current had retroflected into the equatorial North Atlantic. The DIC Δ14C results revealed postbomb carbon in river and ocean waters...

  1. Sink or Swim: Ions and Organics at the Ice-Air Interface.

    Science.gov (United States)

    Hudait, Arpa; Allen, Michael T; Molinero, Valeria

    2017-07-26

    The ice-air interface is an important locus of environmental chemical reactions. The structure and dynamics of the ice surface impact the uptake of trace gases and kinetics of reactions in the atmosphere and snowpack. At tropospheric temperatures, the ice surface is partially premelted. Experiments indicate that ions increase the liquidity of the ice surface but hydrophilic organics do not. However, it is not yet known the extent of the perturbation solutes induce at the ice surface and what is the role of the disordered liquid-like layer in modulating the interaction between solutes and their mobility and aggregation at the ice surface. Here we use large-scale molecular simulations to investigate the effect of ions and glyoxal, one of the most abundant oxygenated volatile organic compounds in the atmosphere, on the structure, dynamics, and solvation properties of the ice surface. We find that the premelted surface of ice has unique solvation properties, different from those of liquid water. The increase in surface liquidity resulting from the hydration of ions leads to a water-mediated attraction of ions at the ice surface. Glyoxal molecules, on the other hand, perturb only slightly the surface of ice and do not experience water-driven attraction. They nonetheless accumulate as dry agglomerates at the ice surface, driven by direct interactions between the organic molecules. The enhanced attraction and clustering of ions and organics at the ice surface may play a significant role in modulating the mechanism and rate of heterogeneous chemical reactions occurring at the surface of atmospheric ice particles.

  2. Malodorous volatile organic sulfur compounds: Sources, sinks and significance in inland waters.

    Science.gov (United States)

    Watson, Susan B; Jüttner, Friedrich

    2017-03-01

    Volatile Organic Sulfur Compounds (VOSCs) are instrumental in global S-cycling and greenhouse gas production. VOSCs occur across a diversity of inland waters, and with widespread eutrophication and climate change, are increasingly linked with malodours in organic-rich waterbodies and drinking-water supplies. Compared with marine systems, the role of VOSCs in biogeochemical processes is far less well characterized for inland waters, and often involves different physicochemical and biological processes. This review provides an updated synthesis of VOSCs in inland waters, focusing on compounds known to cause malodours. We examine the major limnological and biochemical processes involved in the formation and degradation of alkylthiols, dialkylsulfides, dialkylpolysulfides, and other organosulfur compounds under different oxygen, salinity and mixing regimes, and key phototropic and heterotrophic microbial producers and degraders (bacteria, cyanobacteria, and algae) in these environs. The data show VOSC levels which vary significantly, sometimes far exceeding human odor thresholds, generated by a diversity of biota, biochemical pathways, enzymes and precursors. We also draw attention to major issues in sampling and analytical artifacts which bias and preclude comparisons among studies, and highlight significant knowledge gaps that need addressing with careful, appropriate methods to provide a more robust understanding of the potential effects of continued global development.

  3. Exposure to carbon monoxide, respirable suspended particulates, and volatile organic compounds while commuting by bicycle

    International Nuclear Information System (INIS)

    Bevan, M.A.J.; Proctor, C.J.; Baker-Rogers, J.; Warren, N.D.

    1991-01-01

    A portable air sampling system has been used to assess exposures to various substances while commuting by bicycle in an urban area. The major source of pollutants in this situation is motor vehicle exhaust emissions. Carbon monoxide, measured by electrochemical detection, was found at peak concentrations in excess of 62 ppm, with mean values over 16 individual 35-mm journeys being 10.5 ppm. Respirable suspended particulates, averaged over each journey period, were found at higher concentrations (mean 130 μg m -3 ) than would be expected in indoor situations. Mean exposure to benzene (at 56 μg m -3 ) and other aromatic volatile organic compounds was also relatively high. The influence of wind conditions on exposure was found to be significant. Commuting exposures to carbon monoxide, respirable suspended particulates, and aromatic VOCs were found to be higher than exposures in a busy high street and on common parkland

  4. Modeling the Current and Future Roles of Particulate Organic Nitrates in the Southeastern United States.

    Science.gov (United States)

    Pye, Havala O T; Luecken, Deborah J; Xu, Lu; Boyd, Christopher M; Ng, Nga L; Baker, Kirk R; Ayres, Benjamin R; Bash, Jesse O; Baumann, Karsten; Carter, William P L; Edgerton, Eric; Fry, Juliane L; Hutzell, William T; Schwede, Donna B; Shepson, Paul B

    2015-12-15

    Organic nitrates are an important aerosol constituent in locations where biogenic hydrocarbon emissions mix with anthropogenic NOx sources. While regional and global chemical transport models may include a representation of organic aerosol from monoterpene reactions with nitrate radicals (the primary source of particle-phase organic nitrates in the Southeast United States), secondary organic aerosol (SOA) models can underestimate yields. Furthermore, SOA parametrizations do not explicitly take into account organic nitrate compounds produced in the gas phase. In this work, we developed a coupled gas and aerosol system to describe the formation and subsequent aerosol-phase partitioning of organic nitrates from isoprene and monoterpenes with a focus on the Southeast United States. The concentrations of organic aerosol and gas-phase organic nitrates were improved when particulate organic nitrates were assumed to undergo rapid (τ = 3 h) pseudohydrolysis resulting in nitric acid and nonvolatile secondary organic aerosol. In addition, up to 60% of less oxidized-oxygenated organic aerosol (LO-OOA) could be accounted for via organic nitrate mediated chemistry during the Southern Oxidants and Aerosol Study (SOAS). A 25% reduction in nitrogen oxide (NO + NO2) emissions was predicted to cause a 9% reduction in organic aerosol for June 2013 SOAS conditions at Centreville, Alabama.

  5. Bioavailability of sinking organic matter in the Blanes canyon and the adjacent open slope (NW Mediterranean Sea)

    Science.gov (United States)

    Lopez-Fernandez, P.; Bianchelli, S.; Pusceddu, A.; Calafat, A.; Sanchez-Vidal, A.; Danovaro, R.

    2013-05-01

    Submarine canyons are sites of intense energy and material exchange between the shelf and the deep adjacent basins. To test the hypothesis that active submarine canyons represent preferential conduits of available food for the deep-sea benthos, two mooring lines were deployed at 1200 m depth from November 2008 to November 2009 inside the Blanes canyon and on the adjacent open slope (Catalan Margin, NW Mediterranean Sea). We investigated the fluxes, biochemical composition and food quality of sinking organic carbon (OC). OC fluxes in the canyon and the open slope varied among sampling periods, though not consistently in the two sites. In particular, while in the open slope the highest OC fluxes were observed in August 2009, in the canyon the highest OC fluxes occurred in April-May 2009. For almost the entire study period, the OC fluxes in the canyon were significantly higher than those in the open slope, whereas OC contents of sinking particles collected in the open slope were consistently higher than those in the canyon. This result confirms that submarine canyons are effective conveyors of OC to the deep sea. Particles transferred to the deep sea floor through the canyons are predominantly of inorganic origin, significantly higher than that reaching the open slope at a similar water depth. Using multivariate statistical tests, two major clusters of sampling periods were identified: one in the canyon that grouped trap samples collected in December 2008, concurrently with the occurrence of a major storm at the sea surface, and associated with increased fluxes of nutritionally available particles from the upper shelf. Another cluster grouped samples from both the canyon and the open slope collected in March 2009, concurrently with the occurrence of the seasonal phytoplankton bloom at the sea surface, and associated with increased fluxes of total phytopigments. Our results confirm the key ecological role of submarine canyons for the functioning of deep-sea ecosystems

  6. Highly Viscous States Affect the Browning of Atmospheric Organic Particulate Matter.

    Science.gov (United States)

    Liu, Pengfei; Li, Yong Jie; Wang, Yan; Bateman, Adam P; Zhang, Yue; Gong, Zhaoheng; Bertram, Allan K; Martin, Scot T

    2018-02-28

    Initially transparent organic particulate matter (PM) can become shades of light-absorbing brown via atmospheric particle-phase chemical reactions. The production of nitrogen-containing compounds is one important pathway for browning. Semisolid or solid physical states of organic PM might, however, have sufficiently slow diffusion of reactant molecules to inhibit browning reactions. Herein, organic PM of secondary organic material (SOM) derived from toluene, a common SOM precursor in anthropogenically affected environments, was exposed to ammonia at different values of relative humidity (RH). The production of light-absorbing organonitrogen imines from ammonia exposure, detected by mass spectrometry and ultraviolet-visible spectrophotometry, was kinetically inhibited for RH atmospheric brown carbon production and associated influences on energy balance.

  7. Seasonal and spatial distribution of particulate organic matter in the Bay of Bengal

    Digital Repository Service at National Institute of Oceanography (India)

    Fernandes, L.; Bhosle, N.B.; Matondkar, S.G.P.; Bhushan, R.

    spatial differences were observed for the offshore stations in SPIM (Table 1). 3.4. POC and % POC In the Bay of Bengal, the surface POC concentrations ranged from 4.3 to 11.1 µMC, 3.1 to 10.9 µMC, and 4.3 to 9.0 µMC in the SWM, FIM, and SPIM.... This is NIO contribution no. 4435. 10 References Bale, A., Morris, A., 1998. Organic carbon in suspended particulate material in the North Sea: effect of mixing resuspended and background particles. Cont. Shelf Res. 18, 1333 –1345. Bates, N. R., Dennis, A...

  8. Methods of analysis for complex organic aerosol mixtures from urban emission sources of particulate carbon

    International Nuclear Information System (INIS)

    Mazurek, M.A.; Hildemann, L.M.; Simoneit, B.R.T.

    1990-10-01

    Organic aerosols comprise approximately 30% by mass of the total fine particulate matter present in urban atmospheres. The chemical composition of such aerosols is complex and reflects input from multiple sources of primary emissions to the atmosphere, as well as from secondary production of carbonaceous aerosol species via photochemical reactions. To identify discrete sources of fine carbonaceous particles in urban atmospheres, analytical methods must reconcile both bulk chemical and molecular properties of the total carbonaceous aerosol fraction. This paper presents an overview of the analytical protocol developed and used in a study of the major sources of fine carbon particles emitted to an urban atmosphere. 23 refs., 1 fig., 2 tabs

  9. A Prototype Sensor for In Situ Sensing of Fine Particulate Matter and Volatile Organic Compounds.

    Science.gov (United States)

    Ng, Chee-Loon; Kai, Fuu-Ming; Tee, Ming-Hui; Tan, Nicholas; Hemond, Harold F

    2018-01-18

    Air pollution exposure causes seven million deaths per year, according to the World Health Organization. Possessing knowledge of air quality and sources of air pollution is crucial for managing air pollution and providing early warning so that a swift counteractive response can be carried out. An optical prototype sensor (AtmOptic) capable of scattering and absorbance measurements has been developed to target in situ sensing of fine particulate matter (PM2.5) and volatile organic compounds (VOCs). For particulate matter testing, a test chamber was constructed and the emission of PM2.5 from incense burning inside the chamber was measured using the AtmOptic. The weight of PM2.5 particles was collected and measured with a filter to determine their concentration and the sensor signal-to-concentration correlation. The results of the AtmOptic were also compared and found to trend well with the Dylos DC 1100 Pro air quality monitor. The absorbance spectrum of VOCs emitted from various laboratory chemicals and household products as well as a two chemical mixtures were recorded. The quantification was demonstrated, using toluene as an example, by calibrating the AtmOptic with compressed gas standards containing VOCs at different concentrations. The results demonstrated the sensor capabilities in measuring PM2.5 and volatile organic compounds.

  10. A Prototype Sensor for In Situ Sensing of Fine Particulate Matter and Volatile Organic Compounds

    Directory of Open Access Journals (Sweden)

    Chee-Loon Ng

    2018-01-01

    Full Text Available Air pollution exposure causes seven million deaths per year, according to the World Health Organization. Possessing knowledge of air quality and sources of air pollution is crucial for managing air pollution and providing early warning so that a swift counteractive response can be carried out. An optical prototype sensor (AtmOptic capable of scattering and absorbance measurements has been developed to target in situ sensing of fine particulate matter (PM2.5 and volatile organic compounds (VOCs. For particulate matter testing, a test chamber was constructed and the emission of PM2.5 from incense burning inside the chamber was measured using the AtmOptic. The weight of PM2.5 particles was collected and measured with a filter to determine their concentration and the sensor signal-to-concentration correlation. The results of the AtmOptic were also compared and found to trend well with the Dylos DC 1100 Pro air quality monitor. The absorbance spectrum of VOCs emitted from various laboratory chemicals and household products as well as a two chemical mixtures were recorded. The quantification was demonstrated, using toluene as an example, by calibrating the AtmOptic with compressed gas standards containing VOCs at different concentrations. The results demonstrated the sensor capabilities in measuring PM2.5 and volatile organic compounds.

  11. Particulate organic matter in the coastal and estuarine waters of Goa and its relationship with phytoplankton production

    Digital Repository Service at National Institute of Oceanography (India)

    Verlecar, X.N.; Qasim, S.Z.

    In the coastal and estuarine waters of Goa, particulate organic carbon (POC) varied from 0.52 to 2.51 mg l-1 and from 0.28 to 5.24 mg l-1 and particulate phosphorus (PP) varied from 0.71 to 5.18 mu g l-1 and from 0.78 to 20.34 mu g l-1, respectively...

  12. Improved method for minimizing sulfur loss in analysis of particulate organic sulfur.

    Science.gov (United States)

    Park, Ki-Tae; Lee, Kitack; Shin, Kyoungsoon; Jeong, Hae Jin; Kim, Kwang Young

    2014-02-04

    The global sulfur cycle depends primarily on the metabolism of marine microorganisms, which release sulfur gas into the atmosphere and thus affect the redistribution of sulfur globally as well as the earth's climate system. To better quantify sulfur release from the ocean, analysis of the production and distribution of organic sulfur in the ocean is necessary. This report describes a wet-based method for accurate analysis of particulate organic sulfur (POS) in the marine environment. The proposed method overcomes the considerable loss of sulfur (up to 80%) that occurs during analysis using conventional methods involving drying. Use of the wet-based POS extraction procedure in conjunction with a sensitive sulfur analyzer enabled accurate measurements of cellular POS. Data obtained using this method will enable accurate assessment of how rapidly sulfur can transfer among pools. Such information will improve understanding of the role of POS in the oceanic sulfur cycle.

  13. Biogeochemical consequences of vertical and lateral transport of particulate organic matter in the southern North Sea: A multiproxy approach

    NARCIS (Netherlands)

    Le Guitton, M.; Soetaert, K.; Sinninghe Damsté, J.S.; Middelburg, J.J.

    2015-01-01

    Vertical and lateral transports are of importance in continental shelf systems such as the North Sea andplay a major role in the processing of organic matter. We investigated the biogeochemical consequencesof these transports on particulate organic matter at the molecular level in the southern North

  14. Biogeochemical consequences of vertical and lateral transport of particulate organic matter in the southern North Sea: A multiproxy approach

    NARCIS (Netherlands)

    le Guitton, M.; Soetaert, K.; Sinninghe Damsté, J.S.; Middelburg, J.J.

    2015-01-01

    Vertical and lateral transports are of importance in continental shelf systems such as the North Sea and play a major role in the processing of organic matter. We investigated the biogeochemical consequences of these transports on particulate organic matter at the molecular level in the southern

  15. Organic and inorganic speciation of particulate matter formed during different combustion phases in an improved cookstove.

    Science.gov (United States)

    Leavey, Anna; Patel, Sameer; Martinez, Raul; Mitroo, Dhruv; Fortenberry, Claire; Walker, Michael; Williams, Brent; Biswas, Pratim

    2017-10-01

    Residential solid fuel combustion in cookstoves has established health impacts including bladder and lung cancers, cataracts, low birth weight, and pneumonia. The chemical composition of particulate matter (PM) from 4 commonly-used solid fuels (coal, dung, ambient/dry applewood, and oakwood pellets), emitted from a gasifier cookstove, as well as propane, were examined. Temporal changes between the different cookstove burn-phases were also explored. Normalized concentrations of non-refractory PM 1 , total organics, chloride, ammonium, nitrate, sulfate, and 41 particle-phase polycyclic aromatic hydrocarbons (PAHs) were measured using a High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) and a Thermal desorption Aerosol Gas chromatograph (TAG), respectively. Coal demonstrated the highest fraction of organic matter in its particulate emission composition (98%), followed by dung (94%). Coal and dung also demonstrated the highest numbers and concentrations of PAHs. While dry applewood emitted ten times lower organic matter compared to ambient applewood, a higher fraction of these organics was composed of PAHs, especially the more toxic ones such as benzo(a)pyrene (9.63ng/L versus 0.04ng/L), and benzo(b)fluoranthene (31.32ng/L versus 0.19ng/L). Data from the AMS demonstrated no clear trends for any of the combustion fuels over the different combustion phases unlike the previously reported trends observed for the physical characteristics. Of the solid fuels, pellets demonstrated the lowest emissions. Emissions from propane were below the quantification limit of the instruments. This work highlights the benefits of incorporating additional metrics into the cookstove evaluation process, thus enriching the existing PM data inventory. Copyright © 2017. Published by Elsevier Inc.

  16. PAHs concentration and toxicity in organic solvent extracts of atmospheric particulate matter and sea sediments.

    Science.gov (United States)

    Ozaki, Noriatsu; Takeuchi, Shin-ya; Kojima, Keisuke; Kindaichi, Tomonori; Komatsu, Toshiko; Fukushima, Takehiko

    2012-01-01

    The concentration of polycyclic aromatic hydrocarbons (PAHs) and the toxicity to marine bacteria (Vibrio fischeri) were measured for the organic solvent extracts of sea sediments collected from an urban watershed area (Hiroshima Bay) of Japan and compared with the concentrations and toxicity of atmospheric particulate matter (PM). In atmospheric PM, the PAHs concentration was highest in fine particulate matter (FPM) collected during cold seasons. The concentrations of sea sediments were 0.01-0.001 times those of atmospheric PM. 1/EC50 was 1-10 L g(-1) PM for atmospheric PM and 0.1-1 L g(-1) dry solids for sea sediments. These results imply that toxic substances from atmospheric PM are diluted several tens or hundreds of times in sea sediments. The ratio of the 1/EC50 to PAHs concentration ((1/EC50)/16PAHs) was stable for all sea sediments (0.1-1 L μg(-1) 16PAHs) and was the same order of magnitude as that of FPM and coarse particulate matter (CPM). The ratio of sediments collected from the west was more similar to that of CPM while that from the east was more similar to FPM, possibly because of hydraulic differences among water bodies. The PAHs concentration pattern analyses (principal component analysis and isomer ratio analysis) were conducted and the results showed that the PAHs pattern in sea sediments was quite different to that of FPM and CPM. Comparison with previously conducted PAHs analyses suggested that biomass burning residues comprised a major portion of these other sources.

  17. [Sample preparation methods for chromatographic analysis of organic components in atmospheric particulate matter].

    Science.gov (United States)

    Hao, Liang; Wu, Dapeng; Guan, Yafeng

    2014-09-01

    The determination of organic composition in atmospheric particulate matter (PM) is of great importance in understanding how PM affects human health, environment, climate, and ecosystem. Organic components are also the scientific basis for emission source tracking, PM regulation and risk management. Therefore, the molecular characterization of the organic fraction of PM has become one of the priority research issues in the field of environmental analysis. Due to the extreme complexity of PM samples, chromatographic methods have been the chief selection. The common procedure for the analysis of organic components in PM includes several steps: sample collection on the fiber filters, sample preparation (transform the sample into a form suitable for chromatographic analysis), analysis by chromatographic methods. Among these steps, the sample preparation methods will largely determine the throughput and the data quality. Solvent extraction methods followed by sample pretreatment (e. g. pre-separation, derivatization, pre-concentration) have long been used for PM sample analysis, and thermal desorption methods have also mainly focused on the non-polar organic component analysis in PM. In this paper, the sample preparation methods prior to chromatographic analysis of organic components in PM are reviewed comprehensively, and the corresponding merits and limitations of each method are also briefly discussed.

  18. Autoxidation as a major player in the fate of terrestrial particulate organic matter in seawater

    Science.gov (United States)

    Galeron, Marie-Aimée.; Radakovitch, Olivier; Charrière, Bruno; Vaultier, Frédéric; Rontani, Jean-François

    2017-05-01

    The Rhône River plays a major role in the Mediterranean Sea, being both its main freshwater source and its major particulate matter provider. This survey of the fate of terrestrial particulate organic matter (POM) was conducted along the salinity gradient of the Rhône River plume, between 2012 and 2014. It revealed that autoxidation acts rapidly and intensely upon the POM's arrival at sea, with α-amyrin and β-amyrin autoxidation rates going from 12.9 ± 2.9% to 45.0 ± 6.4% and 10.7 ± 4.0% to 50.3 ± 4.4%, respectively, between fresh water (salinity 0) and seawater (salinity 38). These compounds, being unambiguous markers of the terrestrial origin of POM, allow us to unequivocally characterize the POM as terrestrial. While it was originally believed that a desorption of redox-active trace metal ions was the favoring factor that kick-started this intense autoxidation, this study evidences no trace metal desorption in the Rhône River mixing zone and hence no correlation between high autoxidation rates and the presence of trace metal ions. Autoxidation rates however were very well correlated with salinity levels within the river plume, with r2 reaching 0.801, 0.962, and 0.943 for sitosterol, α-amyrin, and β-amyrin, respectively, in November 2014.

  19. Variation pattern of particulate organic carbon and nitrogen in oceans and inland waters

    Science.gov (United States)

    Huang, Changchun; Jiang, Quanliang; Yao, Ling; Yang, Hao; Lin, Chen; Huang, Tao; Zhu, A.-Xing; Zhang, Yimin

    2018-03-01

    We examined the relationship between, and variations in, particulate organic carbon (POC) and particulate organic nitrogen (PON) based on previously acquired ocean and inland water data. The latitudinal dependency of POC / PON is significant between 20 and 90° N but weak in low-latitude areas and in the Southern Hemisphere. The mean values of POC / PON in the Southern Hemisphere and Northern Hemisphere were 7.40 ± 3.83 and 7.80 ± 3.92, respectively. High values of POC / PON appeared between 80-90 (12.2 ± 7.5) and 70-80° N (9.4 ± 6.4), while relatively low POC / PON was found from 20 (6.6 ± 2.8) to 40° N (6.7 ± 2.7). The latitudinal variation of POC / PON in the Northern Hemisphere is much stronger than in the Southern Hemisphere due to the influence of more terrestrial organic matter. Higher POC and PON could be expected in coastal waters. POC / PON growth ranged from 6.89 ± 2.38 to 7.59 ± 4.22 in the Northern Hemisphere, with an increasing rate of 0.0024 km from the coastal to open ocean. Variations of POC / PON in lake water also showed a similar latitude-variation tendency of POC / PON with ocean water but were significantly regulated by the lakes' morphology, trophic state and climate. Small lakes and high-latitude lakes prefer relatively high POC / PON, and large lakes and low-latitude lakes tend to prefer low POC / PON. The coupling relationship between POC and PON in oceans is much stronger than in inland waters. Variations in POC, PON and POC / PON in inland waters should receive more attention due to the implications of these values for the global carbon and nitrogen cycles and the indeterminacy of the relationship between POC and PON.

  20. Simulating the effects of light intensity and carbonate system composition on particulate organic and inorganic carbon production in Emiliania huxleyi.

    Science.gov (United States)

    Holtz, Lena-Maria; Wolf-Gladrow, Dieter; Thoms, Silke

    2015-05-07

    Coccolithophores play an important role in the marine carbon cycle. Variations in light intensity and external carbonate system composition alter intracellular carbon fluxes and therewith the production rates of particulate organic and inorganic carbon. Aiming to find a mechanistic explanation for the interrelation between dissolved inorganic carbon fluxes and particulate carbon production rates, we develop a numerical cell model for Emiliania huxleyi, one of the most abundant coccolithophore species. The model consists of four cellular compartments, for each of which the carbonate system is resolved dynamically. The compartments are connected to each other and to the external medium via substrate fluxes across the compartment-confining membranes. By means of the model we are able to explain several pattern observed in particulate organic and inorganic carbon production rates for different strains and under different acclimation conditions. Particulate organic and inorganic carbon production rates for instance decrease at very low external CO2 concentrations. Our model suggests that this effect is caused mainly by reduced HCO3(-) uptake rates, not by CO2 limitation. The often observed decrease in particulate inorganic carbon production rates under Ocean Acidification is explained by a downregulation of cellular HCO3(-) uptake. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

  1. Organic, elemental and inorganic carbon in particulate matter of six urban environments in Europe

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    M. Sillanpää

    2005-01-01

    Full Text Available A series of 7-week sampling campaigns were conducted in urban background sites of six European cities as follows: Duisburg (autumn, Prague (winter, Amsterdam (winter, Helsinki (spring, Barcelona (spring and Athens (summer. The campaigns were scheduled to include seasons of local public health concern due to high particulate concentrations or findings in previously conducted epidemiological studies. Aerosol samples were collected in parallel with two identical virtual impactors that divide air particles into fine (PM2.5 and coarse (PM2.5-10 size ranges. From the collected filter samples, elemental (EC and organic (OC carbon contents were analysed with a thermal-optical carbon analyser (TOA; total Ca, Ti, Fe, Si, Al and K by energy dispersive X-ray fluorescence (ED-XRF; As, Cu, Ni, V, and Zn by inductively coupled plasma mass spectrometry (ICP/MS; Ca2+, succinate, malonate and oxalate by ion chromatography (IC; and the sum of levoglucosan+galactosan+mannosan (∑MA by liquid chromatography mass spectrometry (LC/MS. The campaign means of PM2.5 and PM2.5-10 were 8.3-29.6 µg m-3 and 5.4-28.7 µg m-3, respectively. The contribution of particulate organic matter (POM to PM2.5 ranged from 21% in Barcelona to 54% in Prague, while that to PM2.5-10 ranged from 10% in Barcelona to 27% in Prague. The contribution of EC was higher to PM2.5 (5-9% than to PM2.5-10 (1-6% in all the six campaigns. Carbonate (C(CO3, that interferes with the TOA analysis, was detected in PM2.5-10 of Athens and Barcelona but not elsewhere. It was subtracted from the OC by a simple integration method that was validated. The CaCO3 accounted for 55% and 11% of PM2.5-10 in Athens and Barcelona, respectively. It was anticipated that combustion emissions from vehicle engines affected the POM content in PM2.5 of all the six sampling campaigns, but a comparison of mass concentration ratios of the selected inorganic and organic tracers of common sources of organic material to POM suggested

  2. Recycling and Resistance of Petrogenic Particulate Organic Carbon: Implications from A Chemical Oxidation Method

    Science.gov (United States)

    Zhang, T.; Li, G.; Ji, J.

    2013-12-01

    Petrogenic particulate organic carbon (OCpetro) represents a small fraction of photosynthetic carbon which escapes pedogenic-petrogenic degradation and gets trapped in the lithosphere. Exhumation and recycling of OCpetro are of significant importance in the global carbon cycle because OCpetro oxidation represents a substantial carbon source to the atmosphere while the re-burial of OCpetro in sediment deposits has no net effect. Though studies have investigated various behaviors of OCpetro in the surface environments (e.g., riverine mobilization, marine deposition, and microbial remineralization), less attention has been paid to the reaction kinetics and structural transformations during OCpetro oxidation. Here we assess the OCpetro-oxidation process based on a chemical oxidation method adopted from soil studies. The employed chemical oxidation method is considered an effective simulation of natural oxidation in highly oxidative environments, and has been widely used in soil studies to isolate the inert soil carbon pool. We applied this chemical method to the OCpetro-enriched black shale samples from the middle-lower Yangtze (Changjiang) basin, China, and performed comprehensive instrumental analyses (element analysis, Fourier transform infrared (FTIR) spectrum, and Raman spectrum). We also conducted step-oxidizing experiments following fixed time series and monitored the reaction process in rigorously controlled lab conditions. In this work, we present our experiment results and discuss the implications for the recycling and properties of OCpetro. Particulate organic carbon concentration of black shale samples before and after oxidation helps to quantify the oxidability of OCpetro and constrain the preservation efficiency of OCpetro during fluvial erosion over large river basin scales. FTIR and Raman analyses reveal clear structural variations on atomic and molecular levels. Results from the step-oxidizing experiments provide detailed information about the reaction

  3. Input of particulate organic and dissolved inorganic carbon from the Amazon to the Atlantic Ocean

    Science.gov (United States)

    Druffel, E. R. M.; Bauer, J. E.; Griffin, S.

    2005-03-01

    We report concentrations and isotope measurements (radiocarbon and stable carbon) of dissolved inorganic carbon (DIC) and suspended particulate organic carbon (POC) in waters collected from the mouth of the Amazon River and the North Brazil Current. Samples were collected in November 1991, when the Amazon hydrograph was at its annual minimum and the North Brazil Current had retroflected into the equatorial North Atlantic. The DIC Δ14C results revealed postbomb carbon in river and ocean waters, with slightly higher values at the river mouth. The low DIC δ13C signature of the river end-member (-11‰) demonstrates that about half of the DIC originated from the remineralization of terrestrially derived organic matter. A linear relationship between DIC and salinity indicates that DIC was mixed nearly conservatively in the transition zone from the river mouth to the open ocean, though there was a small amount (≤10%) of organic matter remineralization in the mesohaline region. The POC Δ14C values in the river mouth were markedly lower than those values from the western Amazon region (Hedges et al., 1986). We conclude that the dominant source of POC near the river mouth and in the inner Amazon plume during November 1991 was aged, resuspended material of significant terrestrial character derived from shelf sediments, while the outer plume contained mainly marine-derived POC.

  4. Particulate organic matter composition in a semi-enclosed Periantarctic system: the Straits of Magellan

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    M. Fabiano

    1999-12-01

    Full Text Available The elemental and biochemical composition of particulate organic matter (POM was investigated in the Straits of Magellan during February-March 1991. Twenty-two stations were selected in order to identify different areas of the Magellan ecosystem from a trophic point of view. The Strait of Magellan can be divided into three subsystems characterized by different hydrological and geomorphological conditions. Seston concentrations were mostly constrained by physical events, particularly the influence of oceanic and land run-off water inputs and the strong vertical mixing and resuspension events. POM composition displayed quali-quantitative differences between the three areas. In the first subsystem, influenced by Pacific waters, the low seston and POM concentrations and the high POC/Chl-a ratio values indicated the general predominance of the detrital and heterotrophic fractions. In the second subsystem, characterized by superficial stratification, higher seston and organic matter concentrations and lower values of POC/Chl-a ratio were found, indicating that this subsystem was influenced by an active autotrophic component. Shallow waters with intense tidal regime and strong vertical mixing characterized the third subsystem, connected to the Atlantic Ocean, which displayed an increasing importance of the inorganic fraction (values of the POC/TSM ratio lower than in the other systems. Moreover, the third subsystem showed higher values of the RNA/DNA ratio, possibly indicating that resuspension events may enhance the metabolic state of the organic particles mainly dominated by heterotrophic components.

  5. Seasonal changes in particulate and dissolved organic matter composition and quality in the Lena River Delta

    Science.gov (United States)

    Mollenhauer, G.; Winterfeld, M.; Hefter, J.; Bodenstab, L.; Morgenstern, A.; Eulenburg, A.; Heim, B.; Koch, B.; Schefuss, E.; Moerth, C. M.; Rethemeyer, J.

    2016-12-01

    Arctic rivers are known to export large quantities of carbon by discharge of dissolved and particulate organic carbon (DOC, POC), and in a warming and progressively moister Arctic, these exports may increase resulting in a reduction of arctic continental carbon stocks. These rivers have highly variable discharge rates with a pronounced maximum during the spring freshet associated with highest concentrations of DOC and POC. Most studies investigating the isotopic composition and quality of carbon exported by Arctic rivers rely on samples taken in summer during base flow, which is due to the logistical challenges associated with sampling in the remote Arctic permafrost regions. Here we present a record of δ13C and Δ14C of DOC and POC collected between late May during the freshet and late August 2014 in the Lena River Delta. POC Δ14C shows an initial trend towards older values in the spring samples, which is reversed in summer, associated with a shift towards more depleted δ13C values. We interpret this aging trend as reflecting progressive thawing throughout the ice-free season, resulting in mobilization of progressively older carbon from deeper thawed layers. The summer reversal indicates admixture of aquatic organic matter. DOC Δ14C, in contrast, remains at relatively modern levels with rather constant δ13C values throughout the sampling period. We furthermore analysed the biomarker composition of Lena Delta particulate OM collected in spring and summer. From spring to summer, we observe trends in abundance of individual leaf-wax derived biomarkers indicating higher abundance of algal biomass in the summer particles. Trends in soil microbial biomarkers and compound-specific δD of leaf-wax lipids suggest a shift in sources towards higher contributions from the southern catchment in summer. DOC composition investigated with FT-ICR-MS changes from spring with higher abundances of compounds with high H/C and low O/C ratios to late summer, when fewer compounds

  6. Temporal variations in C-13 and C-14 concentrations in particulate organic matter from the southern North Sea

    NARCIS (Netherlands)

    Megens, L.; Plicht, J. van der; Leeuw, J.W. de

    As a new approach for the characterization and determination of the origin of particulate organic matter (POM) in coastal waters, we measured the 14C activity and 13C/12C isotope ratios and applied molecular analysis by means of AMS, IRMS and pyrolysis-GCMS for both bulk samples and isolated

  7. Peatland use and transport of particulate organic matter in boreal headwater catchments

    Science.gov (United States)

    Marttila, Hannu; Karjalainen, Satu-Maaria; Nieminen, Mika; Kløve, Bjørn

    2014-05-01

    Peatland use can cause increased transport of particulate organic matter (POM) causing deteriorated water quality and especially siltation of stream beds. Even though topic has gained major attention among stakeholders it has received only minor efforts to solve the main sources and properties of transported particles. The development of effective management practices and evaluation of purification efficiency demands understanding of the sources of particulate matter in peat dominated catchments with various land uses and hydrological conditions. The objectives of this study were: (1) to determinate physical properties of POM in headwater brooks affected by different peatland uses, and; (2) to identity the sources of transported material by using sediment fingerprinting methods. For this purpose, two headwater catchments under peat extraction and peatland forestry land uses with 8 sampling points were monitored for 2 years using time integrated suspended sediment samplers. Data was completed by gap samples from 50 other headwater locations with different upstream land uses: pristine, peatland forestry and peat extraction. For the sources analysis, disturbed topsoil, stream bed sediment, banks of ditches and brooks, algae and various vegetation types were identified as the potential sediment sources. Stable isotopes (δ13C, δ15N) and C/N ratio were analyzed to discriminate between the possible sources. Results are further scaled against different land uses, landscape elements and seasonal hydrological conditions in headwaters. This paper presents the preliminary results from a two year study aiming to show various patterns in transport of POM in boreal headwater catchments. Due to strong land-water relationship in headwaters, further information on the properties of particles is needed to assess the downstream impacts of land use.

  8. Distribution of gaseous and particulate organic composition during dark α-pinene ozonolysis

    Directory of Open Access Journals (Sweden)

    A. R. Rickard

    2010-03-01

    Full Text Available Secondary Organic Aerosol (SOA affects atmospheric composition, air quality and radiative transfer, however major difficulties are encountered in the development of reliable models for SOA formation. Constraints on processes involved in SOA formation can be obtained by interpreting the speciation and evolution of organics in the gaseous and condensed phase simultaneously. In this study we investigate SOA formation from dark α-pinene ozonolysis with particular emphasis upon the mass distribution of gaseous and particulate organic species. A detailed model for SOA formation is compared with the results from experiments performed in the EUropean PHOtoREactor (EUPHORE simulation chamber, including on-line gas-phase composition obtained from Chemical-Ionization-Reaction Time-Of-Flight Mass-Spectrometry measurements, and off-line analysis of SOA samples performed by Ion Trap Mass Spectrometry and Liquid Chromatography. The temporal profile of SOA mass concentration is relatively well reproduced by the model. Sensitivity analysis highlights the importance of the choice of vapour pressure estimation method, and the potential influence of condensed phase chemistry. Comparisons of the simulated gaseous- and condensed-phase mass distributions with those observed show a generally good agreement. The simulated speciation has been used to (i propose a chemical structure for the principal gaseous semi-volatile organic compounds and condensed monomer organic species, (ii provide evidence for the occurrence of recently suggested radical isomerisation channels not included in the basic model, and (iii explore the possible contribution of a range of accretion reactions occurring in the condensed phase. We find that oligomer formation through esterification reactions gives the best agreement between the observed and simulated mass spectra.

  9. Origin and composition of particulate organic matter in a macrotidal turbid estuary: The Gironde Estuary, France

    Science.gov (United States)

    Savoye, Nicolas; David, Valérie; Morisseau, François; Etcheber, Henri; Abril, Gwenaël; Billy, Isabelle; Charlier, Karine; Oggian, Georges; Derriennic, Hervé; Sautour, Benoît

    2012-08-01

    At the interface between continent and ocean, estuaries receive particles, and especially particulate organic matter (POM) originating from these two reservoirs, but also produce POM, through autochthonous primary production. The origin and composition of surface POM in the Gironde Estuary (SW France) and the environmental forcing of its variability was investigated using the data set produced by the French Coastal Monitoring Network SOMLIT (Service d'Observation en Milieu LITtoral; monthly like sampling during years 2007-2009). This estuary is considered as a model of macrotidal turbid estuaries. Using elemental and isotopic composition of the POM, we estimated that, at the inner estuary space scale and inter-annual time scale, surface particulate organic carbon (POC) was composed of terrestrial POM originated from the turbidity maximum (96.4%; refractory POC) and flood events (1.6%; labile and refractory POC), and of riverine (0.1%), estuarine (0.8%) and marine (1.1%) phytoplankton, i.e. that POC was 98% and 2% of terrestrial and phytoplankton origin, respectively. However, there was a clear spatial gradient: the phytoplankton contribution increases from ca. 1% in the upper and middle estuary to 8.5% in the lower estuary, where light condition is more favourable to plankton growth. The low contribution of phytoplankton to the POC is a characteristic of the Gironde estuary and contrast with other large temperate estuaries. Statistical analysis indicates that salinity, river flow and SPM concentration, and thus associated hydro-dynamic and sedimentary processes, were the only environmental forcings to the composition of surface POC in this system, at intra- and inter-annual time scale. In contrast, temperature and nutrient concentrations, and thus associated processes, do not force this composition of POC. By combining POC fluxes entering the inner estuary (literature data), POC loss as dissolved organic carbon and CO2 and as sediment trapping within the inner

  10. Trimethylsilyl derivatives of organic compounds in source samples and in atmospheric fine particulate matter.

    Science.gov (United States)

    Nolte, Christopher G; Schauer, James J; Cass, Glen R; Simoneit, Bernd R T

    2002-10-15

    Source sample extracts of vegetative detritus, motor vehicle exhaust, tire dust paved road dust, and cigarette smoke have been silylated and analyzed by GC-MS to identify polar organic compounds that may serve as tracers for those specific emission sources of atmospheric fine particulate matter. Candidate molecular tracers were also identified in atmospheric fine particle samples collected in the San Joaquin Valley of California. A series of normal primary alkanols, dominated by even carbon-numbered homologues from C26 to C32, the secondary alcohol 10-nonacosanol, and some phytosterols are prominent polar compounds in the vegetative detritus source sample. No new polar organic compounds are found in the motor vehicle exhaust samples. Several hydrogenated resin acids are present in the tire dust sample, which might serve as useful tracers for those sources in areas that are heavily impacted by motor vehicle traffic. Finally, the alcohol and sterol emission profiles developed for all the source samples examined in this project are scaled according to the ambient fine particle mass concentrations attributed to those sources by a chemical mass balance receptor model that was previously applied to the San Joaquin Valley to compute the predicted atmospheric concentrations of individual alcohols and sterols. The resulting underprediction of alkanol concentrations at the urban sites suggests that alkanols may be more sensitive tracers for natural background from vegetative emissions (i.e., waxes) than the high molecular weight alkanes, which have been the best previously available tracers for that source.

  11. Bioavailable dissolved and particulate organic carbon flux from coastal temperate rainforest watersheds

    Science.gov (United States)

    Fellman, J.; Hood, E. W.; D'Amore, D. V.; Moll, A.

    2017-12-01

    Coastal temperate rainforest (CTR) watersheds of southeast Alaska have dense soil carbon stocks ( 300 Mg C ha-1) and high specific discharge (1.5-7 m yr-1) driven by frontal storms from the Gulf of Alaska. As a result, dissolved organic carbon (DOC) fluxes from Alaskan CTR watersheds are estimated to exceed 2 Tg yr-1; however, little is known about the export of particulate organic carbon (POC). The magnitude and bioavailability of this land-to-ocean flux of terrigenous organic matter ultimately determines how much metabolic energy is translocated to downstream and coastal marine ecosystems in this region. We sampled streamwater weekly from May through October from four watersheds of varying landcover (gradient of wetland to glacial coverage) to investigate changes in the concentration and flux of DOC and POC exported to the coastal ocean. We also used headspace analysis of CO2 following 14 day laboratory incubations to determine the flux of bioavailable DOC and POC exported from CTR watersheds. Across all sites, bioavailable DOC concentrations ranged from 0.2 to 1.9 mg L-1 but were on average 0.6 mg L-1. For POC, bioavailable concentrations ranged from below detection to 0.3 mg L-1 but were on average 0.1 mg L-1. The concentration, flux and bioavailability of DOC was higher than for POC highlighting the potential importance of DOC as a metabolic subsidy to downstream and coastal environments. Ratios of DOC to POC decreased during high flow events because the increase in POC concentrations with discharge exceeds that for DOC. Overall, our findings suggest that projected increases in precipitation and storm intensity will drive changes in the speciation, magnitude and bioavailability of the organic carbon flux from CTR watersheds.

  12. Seasonal and diurnal variations of particulate nitrate and organic matter at the IfT research station Melpitz

    Directory of Open Access Journals (Sweden)

    L. Poulain

    2011-12-01

    Full Text Available Ammonium nitrate and several organic compounds such as dicarboxylic acids (e.g. succinic acid, glutaric acid, some Polycyclic Aromatic Hydrocarbon (PAHs or some n-alkanes are semi-volatile. The transition of these compounds between the gas and particulate phase may significantly change the aerosol particles radiative properties, the heterogeneous chemical properties, and, naturally, the total particulate mass concentration. To better assess these time-dependent effects, three intensive field experiments were conducted in 2008–2009 at the Central European EMEP research station Melpitz (Germany using an Aerodyne Aerosol Mass Spectrometer (AMS. Data from all seasons highlight organic matter as being the most important particulate fraction of PM1 in summer (59% while in winter, the nitrate fraction was more prevalent (34.4%. The diurnal variation of nitrate always showed the lowest concentration during the day while its concentration increased during the night. This night increase of nitrate concentration was higher in winter (ΔNO3 = 3.6 μg m−3 than in summer (ΔNO3 = 0.7 μg m−3. The variation in particulate nitrate was inherently linked to the gas-to-particle-phase equilibrium of ammonium nitrate and the dynamics of the atmosphere during day. The results of this study suggest that during summer nights, the condensation of HNO3 and NH3 on pre-existing particles represents the most prevalent source of nitrate, whereas during winter, nighttime chemistry is the predominant source of nitrate. During the summer 2008's campaign, a clear diurnal evolution in the oxidation state of the organic matter became evident (Organic Mass to Organic Carbon ratio (OM/OC ranging from 1.65 during night to 1.80 during day and carbon oxidation state (OSc from −0.66 to −0.4, which could be correlated to hydroxyl radical (OH and ozone

  13. The effect of typhoon on particulate organic carbon flux in the southern East China Sea

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    C.-C. Hung

    2010-10-01

    Full Text Available Severe tropical storms play an important role in triggering phytoplankton blooms, but the extent to which such storms influence biogenic carbon flux from the euphotic zone is unclear. In 2008, typhoon Fengwong provided a unique opportunity to study the in situ biological responses including phytoplankton blooms and particulate organic carbon fluxes associated with a severe storm in the southern East China Sea (SECS. After passage of the typhoon, the sea surface temperature (SST in the SECS was markedly cooler (∼25 to 26 °C than before typhoon passage (∼28 to 29 °C. The POC flux 5 days after passage of the typhoon was 265 ± 14 mg C m−2 d−1, which was ∼1.7-fold that (140–180 mg C m−2 d−1 recorded during a period (June–August, 2007 when no typhoons occurred. A somewhat smaller but nevertheless significant increase in POC flux (224–225 mg C m−2 d−1 was detected following typhoon Sinlaku which occurred approximately 1 month after typhoon Fengwong, indicating that typhoon events can increase biogenic carbon flux efficiency in the SECS. Remarkably, phytoplankton uptake accounted for only about 5% of the nitrate injected into the euphotic zone by typhoon Fengwong. It is likely that phytoplankton population growth was constrained by a combination of light limitation and grazing pressure. Modeled estimates of new/export production were remarkably consistent with the average of new and export production following typhoon Fengwong. The same model suggested that during non-typhoon conditions approximately half of the export of organic carbon occurs via convective mixing of dissolved organic carbon, a conclusion consistent with earlier work at comparable latitudes in the open ocean.

  14. ANALYSIS OF PARTICULATE ORGANIC MATTER IN HOLOCENE SEDIMENTS OF COASTAL PLAIN FROM PERO BEACH, CABO FRIO, RIO DE JANEIRO, BRAZIL

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    Taísa Camila Silveira de Souza

    2016-06-01

    Full Text Available The study of palynofacies along a core drilled on the coastal plain of Cabo Frio, State of Rio de Janeiro, was carried out in order to contribute to the knowledge of the paleoenvironmental evolution of the Pero Beach region. The ages obtained from 14C datings allowed to verify that the studied core records the past 6761 ± 130 yrs cal BP. Thirty samples were prepared by standard methodology for palynofacies. About three hundred particles of the particulate organic material was classified and recorded for each sample. Statistical methods were employed for the associations of particulate organic matter (R-mode cluster analysis and levels (samples; Q-mode cluster analysis analyzed along the core. Furthermore, the ratio Phytoclast - Total Organic Carbon (Phy-TOC was used to verify the proximity of the source area. The three major groups of particulate organic matter found along the studied core are Phytoclasts, Amorphous Organic Matter (AOM and Palynomorphs. The samples showed in general, a predominance of phytoclasts (73.2%, followed by AOM (18.6% and Palynomorphs (8.2%. Supported by statistical analysis, it was possible to deduce that the study area evolved since the middle Holocene from a marine environment to a paleolagoon.

  15. Iron persistence in a distal hydrothermal plume supported by dissolved-particulate exchange

    Science.gov (United States)

    Fitzsimmons, Jessica N.; John, Seth G.; Marsay, Christopher M.; Hoffman, Colleen L.; Nicholas, Sarah L.; Toner, Brandy M.; German, Christopher R.; Sherrell, Robert M.

    2017-02-01

    Hydrothermally sourced dissolved metals have been recorded in all ocean basins. In the oceans' largest known hydrothermal plume, extending westwards across the Pacific from the Southern East Pacific Rise, dissolved iron and manganese were shown by the GEOTRACES program to be transported halfway across the Pacific. Here, we report that particulate iron and manganese in the same plume also exceed background concentrations, even 4,000 km from the vent source. Both dissolved and particulate iron deepen by more than 350 m relative to 3He--a non-reactive tracer of hydrothermal input--crossing isopycnals. Manganese shows no similar descent. Individual plume particle analyses indicate that particulate iron occurs within low-density organic matrices, consistent with its slow sinking rate of 5-10 m yr-1. Chemical speciation and isotopic composition analyses reveal that particulate iron consists of Fe(III) oxyhydroxides, whereas dissolved iron consists of nanoparticulate Fe(III) oxyhydroxides and an organically complexed iron phase. The descent of plume-dissolved iron is best explained by reversible exchange onto slowly sinking particles, probably mediated by organic compounds binding iron. We suggest that in ocean regimes with high particulate iron loadings, dissolved iron fluxes may depend on the balance between stabilization in the dissolved phase and the reversibility of exchange onto sinking particles.

  16. A Global Data Analysis for Representing Sediment and Particulate Organic Carbon Yield in Earth System Models

    Science.gov (United States)

    Tan, Zeli; Leung, L. Ruby; Li, Hongyi; Tesfa, Teklu; Vanmaercke, Matthias; Poesen, Jean; Zhang, Xuesong; Lu, Hui; Hartmann, Jens

    2017-12-01

    Although sediment yield (SY) from water erosion is ubiquitous and its environmental consequences are well recognized, its impacts on the global carbon cycle remain largely uncertain. This knowledge gap is partly due to the lack of soil erosion modeling in Earth System Models (ESMs), which are important tools used to understand the global carbon cycle and explore its changes. This study analyzed sediment and particulate organic carbon yield (CY) data from 1,081 and 38 small catchments (0.1-200 km2), respectively, in different environments across the globe. Using multiple statistical analysis techniques, we explored environmental factors and hydrological processes important for SY and CY modeling in ESMs. Our results show clear correlations of high SY with traditional agriculture, seismicity and heavy storms, as well as strong correlations between SY and annual peak runoff. These highlight the potential limitation of SY models that represent only interrill and rill erosion because shallow overland flow and rill flow have limited transport capacity due to their hydraulic geometry to produce high SY. Further, our results suggest that SY modeling in ESMs should be implemented at the event scale to produce the catastrophic mass transport during episodic events. Several environmental factors such as seismicity and land management that are often not considered in current catchment-scale SY models can be important in controlling global SY. Our analyses show that SY is likely the primary control on CY in small catchments and a statistically significant empirical relationship is established to calculate SY and CY jointly in ESMs.

  17. Variability of particulate organic carbon in inland waters observed from MODIS Aqua imagery

    International Nuclear Information System (INIS)

    Duan, Hongtao; Ma, Ronghua; Zhang, Yuchao; Feng, Lian; Arthur Loiselle, Steven

    2014-01-01

    Surface concentrations of particulate organic carbon (POC) in shallow inland lakes were estimated using MODIS Aqua data. A power regression model of the direct empirical relationship between POC and the atmospherically Rayleigh-corrected MODIS product (R rc,645 -R rc,1240 )/(R rc,859 -R rc,1240 ) was developed (R 2  = 0.72, RMSE = 35.86 μgL −1 , p < 0.0001, N = 47) and validated (RMSE = 44.46 μgL −1 , N = 16) with field data from 56 lakes in the Middle and Lower reaches of the Yangtze River, China. This algorithm was applied to an 11 year series of MODIS data to determine the spatial and temporal distribution of POC in a wide range of lakes with different trophic and optical properties. The results indicate that there is a general increase in minimum POC concentrations in lakes from middle to lower reaches of the Yangtze River. The temporal dynamics of springtime POC in smaller lakes were found to be influenced by local meteorological conditions, in particular precipitation and wind speed, while larger lakes were found to be more sensitive to air temperature. (letter)

  18. Validation and Intercomparison of Ocean Color Algorithms for Estimating Particulate Organic Carbon in the Oceans

    Directory of Open Access Journals (Sweden)

    Hayley Evers-King

    2017-08-01

    Full Text Available Particulate Organic Carbon (POC plays a vital role in the ocean carbon cycle. Though relatively small compared with other carbon pools, the POC pool is responsible for large fluxes and is linked to many important ocean biogeochemical processes. The satellite ocean-color signal is influenced by particle composition, size, and concentration and provides a way to observe variability in the POC pool at a range of temporal and spatial scales. To provide accurate estimates of POC concentration from satellite ocean color data requires algorithms that are well validated, with uncertainties characterized. Here, a number of algorithms to derive POC using different optical variables are applied to merged satellite ocean color data provided by the Ocean Color Climate Change Initiative (OC-CCI and validated against the largest database of in situ POC measurements currently available. The results of this validation exercise indicate satisfactory levels of performance from several algorithms (highest performance was observed from the algorithms of Loisel et al., 2002; Stramski et al., 2008 and uncertainties that are within the requirements of the user community. Estimates of the standing stock of the POC can be made by applying these algorithms, and yield an estimated mixed-layer integrated global stock of POC between 0.77 and 1.3 Pg C of carbon. Performance of the algorithms vary regionally, suggesting that blending of region-specific algorithms may provide the best way forward for generating global POC products.

  19. A Global Data Analysis for Representing Sediment and Particulate Organic Carbon Yield in Earth System Models

    Energy Technology Data Exchange (ETDEWEB)

    Tan, Zeli [Pacific Northwest National Laboratory, Richland WA USA; Leung, L. Ruby [Pacific Northwest National Laboratory, Richland WA USA; Li, Hongyi [Montana State University, Bozeman MT USA; Tesfa, Teklu [Pacific Northwest National Laboratory, Richland WA USA; Vanmaercke, Matthias [Département de Géographie, Université de Liège, Liege Belgium; Poesen, Jean [Department of Earth and Environmental Sciences, Division of Geography, KU Leuven, Leuven Belgium; Zhang, Xuesong [Pacific Northwest National Laboratory, Richland WA USA; Lu, Hui [Ministry of Education Key Laboratory for Earth System Modeling, Department of Earth System Science, Tsinghua University, Beijing China; Hartmann, Jens [Institute for Geology, Center for Earth System Research and Sustainability, Universität Hamburg, Hamburg Germany

    2017-12-01

    Although sediment yield (SY) from water erosion is ubiquitous and its environmental consequences are well recognized, its impacts on the global carbon cycle remain largely uncertain. This knowledge gap is partly due to the lack of soil erosion modeling in Earth System Models (ESMs), which are important tools used to understand the global carbon cycle and explore its changes. This study analyzed sediment and particulate organic carbon yield (CY) data from 1081 and 38 small catchments (0.1-200 km27 ), respectively, in different environments across the globe. Using multiple statistical analysis techniques, we explored environmental factors and hydrological processes important for SY and CY modeling in ESMs. Our results show clear correlations of high SY with traditional agriculture, seismicity and heavy storms, as well as strong correlations between SY and annual peak runoff. These highlight the potential limitation of SY models that represent only interrill and rill erosion because shallow overland flow and rill flow have limited transport capacity due to their hydraulic geometry to produce high SY. Further, our results suggest that SY modeling in ESMs should be implemented at the event scale to produce the catastrophic mass transport during episodic events. Several environmental factors such as seismicity and land management that are often not considered in current catchment-scale SY models can be important in controlling global SY. Our analyses show that SY is likely the primary control on CY in small catchments and a statistically significant empirical relationship is established to calculate SY and CY jointly in ESMs.

  20. Radiocarbon determination of particulate organic carbon in glacier ice from the Grenzgletscher (Monte Rosa)

    International Nuclear Information System (INIS)

    Steier, P.; Drosg, R.; Kutschera, W.; Wild, E.M.; Fedi, M.; Schock, M.; Wagenbach, D.

    2005-01-01

    Full text: Dating ice cores from cold glaciers via radiocarbon is still an unsolved problem. This work describes our approach towards extraction and AMS radiocarbon dating of the particulate organic carbon (POC) fraction in ice samples at VERA (Vienna Environmental Research Accelerator). First measurements were performed on 1 snow and 11 ice samples from Gorner Glacier and Colle Gnifetti in the Monte Rosa Mountain region (Swiss Alps). The sample masses used were between 0.3 kg and 1.4 kg ice yielding between 18 μg and 307 μg carbon as POC. The carbon contamination introduced during the sample processing varied between 9 μg and 33 μg C and originates mainly from the quartz filters and the rinsing liquids used. Minimum sample sizes for successful graphitization of carbon dioxide in our laboratory have been reduced to less than 10 μg carbon. The background in the graphitization process is approximately 0.5 μg carbon of 40 pMC. Scatter and outliers in the radiocarbon data suggest that presently a single radiocarbon date of glacial POC has limited significance. For the set of 11 ice samples, a calibrated age of 2100 BC to 900 AD (95% confidence level) is obtained. (author)

  1. Organic and Elemental Carbon Aerosol Particulates at the Southern Great Plains Site Field Campaign Report

    Energy Technology Data Exchange (ETDEWEB)

    Cary, Robert

    2016-04-01

    The purpose of this study was to measure the organic carbon (OC) and elemental carbon (EC) fractions of PM2.5 particulate matter at the U.S. Department of Energy (DOE)’s Atmospheric Radiation Measurement (ARM) Climate Research Facility Southern Great Plains (SGP) sampling site for a 6-month period during the summer of 2013. The site is in a rural location remote from any populated areas, so it would be expected to reflect carbon concentration over long-distance transport patterns. During the same period in 2012, a number of prairie fires in Oklahoma and Texas had produced large plumes of smoke particles, but OC and EC particles had not been quantified. In addition, during the summer months, other wild fires, such as forest fires in the Rocky Mountain states and other areas, can produce carbon aerosols that are transported over long distances. Both of these source types would be expected to contain mixtures of both OC and EC.

  2. Chemical characteristics and source apportionment of fine particulate organic carbon in Hong Kong during high particulate matter episodes in winter 2003

    Science.gov (United States)

    Li, Yun-Chun; Yu, Jian Zhen; Ho, Steven Sai Hang; Schauer, James J.; Yuan, Zibing; Lau, Alexis K. H.; Louie, Peter K. K.

    2013-02-01

    PM2.5 samples were collected at six general stations and one roadside station in Hong Kong in two periods of high particulate matter (PM) in 2003 (27 October-4 November and 30 November-13 December). The highest PM2.5 reached 216 μg m- 3 during the first high PM period and 113 μg m- 3 during the second high PM period. Analysis of synoptic weather conditions identified individual sampling days under dominant influence of one of three types of air masses, that is, local, regional and long-range transported (LRT) air masses. Roadside samples were discussed separately due to heavy influences from vehicular emissions. This research examines source apportionment of fine organic carbon (OC) and contribution of secondary organic aerosol on high PM days under different synoptic conditions. Six primary OC (POC) sources (vehicle exhaust, biomass burning, cooking, cigarette smoke, vegetative detritus, and coal combustion) were identified on the basis of characteristic organic tracers. Individual POC source contributions were estimated using chemical mass balance model. In the roadside and the local samples, OC was dominated by the primary sources, accounting for more than 74% of OC. In the samples influenced by regional and LRT air masses, secondary OC (SOC), which was approximated to be the difference between the total measured OC and the apportioned POC, contributed more than 54% of fine OC. SOC was highly correlated with water-soluble organic carbon and sulfate, consistent with its secondary nature.

  3. Photochemical Reactions of Particulate Organic Matter: Deciphering the Role of Direct and Indirect Processes

    Science.gov (United States)

    Carrasquillo, A. J.; Gelfond, C. E.; Kocar, B. D.

    2016-12-01

    Photochemical reactions of natural organic matter (NOM) represent potentially important pathways for biologically recalcitrant material to be chemically altered in aquatic systems. Irradiation can alter the physical state of organic matter by facilitating the cycling between the particulate (POM) and dissolved (DOM) pools, however, a molecular level understanding of this chemically dynamic system is currently lacking. Photochemical reactions of a target molecule proceed by the direct absorption of a photon, or through reaction with a second photolytically generated species (i.e. the hydroxyl radical, singlet oxygen, excited triplet state NOM, hydrogen peroxide, etc.). Here, we isolate the major direct and indirect photochemical reactions of a lignocellulose-rich POM material (Phragmites australis) to determine their relative importance in changing the the chemical structure of the parent POM, and in the production of DOM. We measured POM molecular structure using a combination of NMR and FTIR for bulk analyses and scanning transmission x-ray microscopy (STXM) for spatially resolved chemistry, while the chemical composition of photo-produced DOM was measured using ultra-high resolution mass spectrometry. Results are discussed in the context of the differences in chemical composition of both NOM pools resulting from the isolated photochemical pathways. All treatments result in an increase in DOM with reaction time, indicating that the larger POM matrix is likely fragmenting into smaller more soluble species. Spectroscopic measurements, on the other hand, point to functionalization reactions which increase the abundance of alcohol, acid, and carbonyl moieties in both carbon pools. This unique dataset provides new insight into how photochemical reactions alter the chemical composition of NOM while highlighting the relative importance of indirect pathways.

  4. Particulate Organic Matter Affects Soil Nitrogen Mineralization under Two Crop Rotation Systems.

    Directory of Open Access Journals (Sweden)

    Rongyan Bu

    Full Text Available Changes in the quantity and/or quality of soil labile organic matter between and after different types of cultivation system could play a dominant role in soil nitrogen (N mineralization. The quantity and quality of particulate organic matter (POM and potentially mineralizable-N (PMN contents were measured in soils from 16 paired rice-rapeseed (RR/cotton-rapeseed (CR rotations sites in Hubei province, central China. Then four paired soils encompassing low (10th percentile, intermediate (25th and 75th percentiles, and high (90th percentile levels of soil PMN were selected to further study the effects of POM on soil N mineralization by quantifying the net N mineralization in original soils and soils from which POM was removed. Both soil POM carbon (POM-C and N (POM-N contents were 45.8% and 55.8% higher under the RR rotation compared to the CR rotation, respectively. The PMN contents were highly correlated with the POM contents. The PMN and microbial biomass N (MBN contents concurrently and significantly decreased when POM was removed. The reduction rate of PMN was positively correlated with changes in MBN after the removal of POM. The reduction rates of PMN and MBN after POM removal are lower under RR rotations (38.0% and 16.3%, respectively than CR rotations (45.6% and 19.5%, respectively. Furthermore, infrared spectroscopy indicated that compounds with low-bioavailability accumulated (e.g., aromatic recalcitrant materials in the soil POM fraction under the RR rotation but not under the CR rotation. The results of the present study demonstrated that POM plays a vital role in soil N mineralization under different rotation systems. The discrepancy between POM content and composition resulting from different crop rotation systems caused differences in N mineralization in soils.

  5. Particulate organic constituents of surface waters of east coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Sreepada, R.A.; Bhat, K.L.; Parulekar, A.H.

    protein (PP) and particulate lipid (PL) fractions. High values of chlorophyll a (chl-a) characterized the coastal waters. In coastal waters, POC was dominatEd. by PCHO containing detrital matter, whereas actively growing phytoplankton significantly...

  6. Characteristics of organic compounds in aerosol particulate matter from Dhahran city, Saudi Arabia

    Directory of Open Access Journals (Sweden)

    Ahmed I. Rushdi

    2017-05-01

    Full Text Available Organic chemical pollutants in atmospheric particulate matter (PM have a potential toxicity hazard resulting in human responses that vary from no discernible effect to premature death. The formation and sources of PM also affect air quality of metropolitan areas as well as climate change. The new developments and industrial activities in the Middle East, especially Saudi Arabia, are expected to contribute to the natural, regional, and anthropogenic input sources of organic matter (OM. Here we report the occurrence, concentrations and sources of organic tracers, including n-alkanes, polycyclic aromatic hydrocarbons (PAHs, plasticizers, and petroleum biomarkers, in ambient atmospheric PM from the city of Dhahran, Saudi Arabia. The major compounds were unresolved complex mixtures (UCM of branched and cyclic hydrocarbons (489 ± 296 ng m−3, plasticizers (131 ± 119 ng m−3 for phenyl phosphates, 87 ± 42 ng m−3 for phthalates, n-alkanes (73 ± 53 ng m−3, hopane biomarkers (11 ± 8 ng m−3, n-alkanones (6.7 ± 6.3 ng m−3, PAHs (2.0 ± 2.1 ng m−3, n-alkanols (1.2 ± 1.2 ng m−3, sterane biomarkers (0.4 ± 0.3 ng m−3, and sterols (0.5 ± 0.4 ng m−3. Obviously, UCM and plasticizers were the major components (56 ± 9% and 26 ± 10% of the total extracts, respectively in the PM of Dhahran, which might have adverse public health effects. The major sources of this OM are emissions from industrial factories north of the city, plastics and biomass burning, and petroleum product combustion (traffic/refining.

  7. Thermal stability of inorganic and organic compounds in atmospheric particulate matter

    Science.gov (United States)

    Perrino, Cinzia; Marconi, Elisabetta; Tofful, Luca; Farao, Carmela; Materazzi, Stefano; Canepari, Silvia

    2012-07-01

    The thermal behaviour of atmospheric particulate matter (PM) has been investigated by using different analytical approaches to explore the added value offered by these technique in environmental studies. The thermogravimetric analysis (TGA), carried out on both certified material and real PM samples, has shown that several mass losses can be detected starting from 80 °C up to above 500 °C, when pyrolysis occur. Thermo-optical analysis of PM and ion chromatographic analysis of the residual have shown that the mass losses in the temperature range 80-180 °C are not justified by the release of either organic or inorganic compounds; it can be thus attributed to the release of weakly and strongly bound water. Release of water has also been evidenced in the temperature range 225-275 °C. The release of ammonium chloride and nitrate has been detected only above 80 °C. This indicates that the release of nitric acid, hydrochloric acid and ammonia, which is observed downstream of the filters during the sampling of atmospheric PM at ambient temperature, cannot be reproduced off-line, after the end of the sampling. We successfully explored one of the possible explanations, that is the desorption of HNO3, HCl and NH3 adsorbed on collected particles. NH4NO3 and NH4Cl, which can be thermally released by the filter, exhibit a different thermal behaviour from NaNO3 and NaCl, which are thermally stable up to 370 °C. This different behaviour can be used to discriminate between natural and secondary sources of atmospheric inorganic salts, as the interconversion that is observed when heating mixtures of pure salts resulted to be not relevant when heating real PM samples.

  8. The molecular distribution of fine particulate organic matter emitted from Western-style fast food cooking

    Science.gov (United States)

    Zhao, Yunliang; Hu, Min; Slanina, Sjaak; Zhang, Yuanhang

    The emissions from food cooking could be a significant contributor to atmospheric particulate organic matter (POM) and its chemical composition would vary with different cooking styles. In this study, the chemical composition of POM emitted from Western-style fast food cooking was investigated. A total of six PM 2.5 samples was collected from a commercial restaurant and determined by gas chromatography-mass spectrometry (GC-MS). It is found that the total amount of quantified compounds of per mg POM in Western-style fast food cooking is much higher than that in Chinese cooking. The predominant homologue is fatty acids, accounting for 78% of total quantified POM, with the predominant one being palmitic acid. Dicarboxylic acids display the second highest concentration in the quantified homologues with hexanedioic acid being predominant, followed by nonanedioic acid. Cmax of n-alkanes occurs at C25, but they still appear relative higher concentrations at C29 and C31. In addition, both levoglucosan and cholesterol are quantified. The relationship of concentrations of unsaturated fatty acids (C16 and C18) with a double bond at C9 position and C9 acids indicates the reduction of the unsaturated fatty acids in the emissions could form the C9 acids. Moreover, the nonlinear fit indicates that other C9 species or other compounds are also produced, except for the C9 acids. The potential candidates of tracers for the emissions from Western-fast food cooking could be: tetradecanoic acid, hexadecanoic acid, octadecanoic acid, 9-octadecenoic acid, nonanal, lactones, levoglucosan, hexanedioic acid and nonanedioic acid.

  9. Carbon Composition of Particulate Organic Carbon in the Gulf of Mexico

    Science.gov (United States)

    Rogers, K.; Montoya, J. P.; Weber, S.; Bosman, S.; Chanton, J.

    2016-02-01

    The Deepwater Horizon blowout released 5.0x1011 g C from gaseous hydrocarbons and up to 6.0x1011g C from oil into the water column. Another carbon source, adding daily to the water column, leaks from the natural hydrocarbon seeps that pepper the seafloor of the Gulf of Mexico. How much of this carbon from the DWH and natural seeps is assimilated into particulate organic carbon (POC) in the water column? We filtered seawater collected in 2010, 2012, and 2013 from seep and non-seep sites, collecting POC on 0.7µm glass microfiber filters and analyzing the POC for stable and radiocarbon isotopes. Mixing models based on carbon isotopic endmembers of methane, oil, and modern production were used to estimate the percentage of hydrocarbon incorporated into POC. Significant differences were seen between POC from shallow and deep waters and between POC collected from seep, non-seep, and blowout sites; however yearly differences were not as evident suggesting the GOM has a consistent supply of depleted carbon. Stable carbon isotopes signatures of POC in the Gulf averaged -23.7±2.5‰ for shallow samples and -26.65±2.9‰ for deep POC samples, while radiocarbon signatures averaged -100.4±146.1‰ for shallow and -394.6±197‰ for deep samples. POC in the northern Gulf are composed of 23-91% modern carbon, 2-21% methane, and 0-71% oil. Oil plays a major role in the POC composition of the GOM, especially at the natural seep GC600.

  10. Nutrient variations and isotopic evidences of particulate organic matter provenance in fringing reefs, South China

    International Nuclear Information System (INIS)

    Cao, Di; Cao, Wenzhi; Liang, Ying; Huang, Zheng

    2016-01-01

    Nutrient over-enrichment is considered to be one of the causes of coral decline. Increase in traditional fishing in the Xuwen National Coral Reefs Reserve tract (XW) and tourism around the Sanya National Coral Reefs Reserve tract (SY) are causing this coral decline. This study reviews the current state of knowledge of the nutrient status of coastal fringing reefs in South China and evaluates the primary sources of nutrients using stable isotope method. Surveys of seawater nutrients showed that the seawater remained clean in both the XW and SY coastal coral reef areas. Based on the isotopic differences between anthropogenic sewage and naturally occurring aquatic nutrients, the isotopic values of particulate organic matter (POM) and the C/N ratios were successfully used to identify the presence of anthropogenic nutrients in aquatic environments. The δ"1"3C, δ"1"5N and C/N compositions of POM from XW and SY (− 21.18 ± 2.11‰, 10.30 ± 5.54‰, and 5.35 ± 0.69 and − 20.80 ± 1.34‰, 7.06 ± 3.95‰, and 5.77 ± 2.15, respectively) showed statistically significant variations with the season. The δ"1"3C and δ"1"5N values of POM suggest marine and terrestrial-derived nutrient sources. Organic carbon is a mixture of marine phytoplankton, marine benthic algae and terrestrial-derived plants. The δ"1"5N values suggest terrestrial-derived sewage and upwelling-dominated nitrogen sources. In the presence of natural upwelling and coastal currents, coastal coral reef areas are more vulnerable to the increasing anthropogenic nutrient inputs. Anthropogenic activities might lead to large increases in the nutrient concentrations and could trigger the shift from coral- to macroalgae-dominated ecosystems, which would ultimately result in the degradation of the coastal coral reef ecosystem. These results provide some understanding of the declining coral reef ecosystem and the importance of conservation areas and coastal coral reef resource management. - Highlights: • The

  11. Nutrient variations and isotopic evidences of particulate organic matter provenance in fringing reefs, South China

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Di; Cao, Wenzhi, E-mail: wzcao@xmu.edu.cn; Liang, Ying; Huang, Zheng

    2016-10-01

    Nutrient over-enrichment is considered to be one of the causes of coral decline. Increase in traditional fishing in the Xuwen National Coral Reefs Reserve tract (XW) and tourism around the Sanya National Coral Reefs Reserve tract (SY) are causing this coral decline. This study reviews the current state of knowledge of the nutrient status of coastal fringing reefs in South China and evaluates the primary sources of nutrients using stable isotope method. Surveys of seawater nutrients showed that the seawater remained clean in both the XW and SY coastal coral reef areas. Based on the isotopic differences between anthropogenic sewage and naturally occurring aquatic nutrients, the isotopic values of particulate organic matter (POM) and the C/N ratios were successfully used to identify the presence of anthropogenic nutrients in aquatic environments. The δ{sup 13}C, δ{sup 15}N and C/N compositions of POM from XW and SY (− 21.18 ± 2.11‰, 10.30 ± 5.54‰, and 5.35 ± 0.69 and − 20.80 ± 1.34‰, 7.06 ± 3.95‰, and 5.77 ± 2.15, respectively) showed statistically significant variations with the season. The δ{sup 13}C and δ{sup 15}N values of POM suggest marine and terrestrial-derived nutrient sources. Organic carbon is a mixture of marine phytoplankton, marine benthic algae and terrestrial-derived plants. The δ{sup 15}N values suggest terrestrial-derived sewage and upwelling-dominated nitrogen sources. In the presence of natural upwelling and coastal currents, coastal coral reef areas are more vulnerable to the increasing anthropogenic nutrient inputs. Anthropogenic activities might lead to large increases in the nutrient concentrations and could trigger the shift from coral- to macroalgae-dominated ecosystems, which would ultimately result in the degradation of the coastal coral reef ecosystem. These results provide some understanding of the declining coral reef ecosystem and the importance of conservation areas and coastal coral reef resource management

  12. The dynamic of organic carbon in South Cameroon. Fluxes in a tropical river system and a lake system as a varying sink on a glacial-interglacial time scale

    Energy Technology Data Exchange (ETDEWEB)

    Giresse, P. [Laboratoire de Sedimentologie et Geochimie Marines, URA CNRS 715, Universite de Perpignan, 66860 Perpignan (France); Maley, J. [Paleoenvironnements et Palynologie, ISEM/CNRS, UMR 5554, ORSTOM, UR 12, Universite de Montpellier II, 34095 Montpellier (France)

    1998-05-01

    In the first attempt to estimate both (i) a bulk carbon flux in a tropical river system (mainly Sanaga River) and (ii) their palaeoenvironmental implications from the Last Glacial Maximum (LGM) to the present, this study presents a synthetic approach based on the combined use of modern evaluation of fluxes and estuarine biodegradation in the tropical river system Sanaga and nearby Douala Bay rivers, and of sedimentation rates of a well studied marine shelf and lake system (Barombi-Mbo). In the lake Barombi-Mbo, the Holocene transfer of particulate carbon (96.6x10{sup 3} t) is very close to the mass fixed presently in soil catchments (117x10{sup 3} t). A complete process of stored carbon consumption would require some 10{sup 4} years, namely the Holocene period. During the last 20,000 years, variations in the sediment organic matter can be explained by the change of the vegetation cover, particularly with the substitution of open environments by forests. The global sedimentation was slow between ca. 18,000 and 10,000 years BP and increased after 12,000 years. But the carbon sedimentation rate remains fairly constant as the carbon content is higher in the LGM deposits. Such LGM carbon concentrations are probably explained by the input of coarse debris by rough floods and by a less degraded organic matter as a result of the cooling of the climate. Today, the total transport of dissolved and particulate organic carbon of the Sanaga and Douala Bay rivers to the Guinea Gulf is estimated as 0.62 to 0.79x10{sup 6} t C yr{sup -1}. Based on 50% biodegradation at the estuarine interface, the loss of organic matter per unit of land is evaluated around 8.8 t C km{sup -2} yr{sup -1}. Marine oceanic records of the carbon sedimentation rate reflect with difficulty the major palaeoenvironmental changes according to interfering hydrodynamic factors. The greatest input of organic carbon during warm marine biozones would be balanced by higher concentrations during the LGM resulting in

  13. Increase of anaerobic degradation of particulate organic matter in full-scale biogas plants by mechanical maceration

    DEFF Research Database (Denmark)

    Hartmann, Hinrich; Angelidaki, Irini; Ahring, Birgitte Kiær

    2000-01-01

    of a macerator make it attractive to use this pretreatment method for a more complete degradation of particulate organic matter. investigation of the size distribution of the fibers showed that a change in biogas potential was not correlated to a smaller size of the fibers. Results from the macerators indicate......% by pretreatment of the whole feed in the macerator before the reactor was observed. implementation concepts with a treatment of the fibers alone after separation from the manure showed to be not efficient due to a low recovery of organic matter in the fibers by the separation unit. The low operational costs...

  14. Polycyclic aromatic hydrocarbons and organic matter associated to particulate matter emitted from atmospheric fluidized bed coal combustion

    International Nuclear Information System (INIS)

    Mastral, A.M.; Callen, M.S.; Garcia, T.

    1999-01-01

    The polycyclic aromatic hydrocarbons (PAH) and the organic matter (OM) content associated with particulate matter (PM) emissions from atmospheric fluidized bed coal combustion have been studied. The two main aims of the work have been (a) to study OM and PAH emissions as a function of the coal fluidized bed combustion (FBC) variables in solid phase and (b) to check if there is any correlation between OM and PAH contained in the PM. The combustion was carried out in a laboratory scale plant at different combustion conditions: temperature, percentage of oxygen excess, and total air flow. PAH associated on the particulate matter have been analyzed by fluorescence spectroscopy in the synchronous mode (FS) after PM extraction by sonication with dimethylformamide (DMF). It can be concluded that there is not a direct relationship between the OM content and the PAH supported in the PM emitted. In addition, neither PM or OM show dependence between themselves

  15. Particulate organic carbon mass distribution at the Bermuda Atlantic Time-series Study (BATS) site

    Science.gov (United States)

    Gundersen, Kjell; Orcutt, Karen M.; Purdie, Duncan A.; Michaels, Anthony F.; Knap, Anthony H.

    Errors in total particulate organic carbon (total POC) measurements caused by particles settling in Niskin water samplers, loss of bacterial cells during filtration and undersampling of rare particles such as the diazotrophic cyanobacterium Trichodesmium spp. were investigated at the Bermuda Atlantic Time-series Study (BATS) site. Regular core samples of temperature, primary production, bacterial abundance, chlorophyll- a (Chl- a) and POC were collected at monthly intervals from 1991 to 1996. During this period of time, shorter investigations of particles settling in water samples (1991-1992), bacterial cells lost during filtration (1992-1993), and Trichodesmium abundance (1995-1996) were performed at the BATS site. The BATS site shows striking seasonal patterns in hydrography and phytoplankton primary productivity, with a strong maximum immediately following the deep winter mixing of the water column. Following the peak in primary production, bacterial abundance showed only slightly elevated levels in spring. Maxima of Chl- a and POC also were associated with the primary production peaks, but these particle concentrations became less pronounced through summer and fall. An average of 26% of total POC collected in Niskin water bottles settled below the spigot before it could be sampled. An average of 47% of all bacterial cells passed the nominal pore size of a Whatman GF/F filter, and total POC measurements generated from GF/F filtered seawater samples had to be corrected for this loss. The average integrated stocks of total POC in the upper 65 m of the water column was 32% pigmented phytoplankton, 15% microheterotrophs, 54% other detrital matter (32 : 15 : 54). Phytoplankton C equaled bacterial C in the 65-135 m depth range (16 : 19 : 65), but phytoplankton C was virtually non-existent deeper than 135 m (2 : 14 : 74). Bacterial C biomass was higher than phytoplankton in surface waters outside the spring bloom period, but carbon not accounted for by phytoplankton

  16. Origin of particulate organic carbon in the marine atmosphere as indicated by it stable carbon isotopic composition

    International Nuclear Information System (INIS)

    Chesselet, R.; Fontugne, M.; Buat-Menard, P.; Ezat, U.; Lambert, C.E.

    1981-01-01

    Organic carbon concentration and isotopic composition were determined in samples of atmospheric particulate matter collected in 1979 at remote marine locations (Enewetak atoll, Sargasso Sea) during the SEAREX (Sea-Air Exchange) program field experiments. Atmospheric Particulate Organic Carbon (POC) concentrations were found to be in the range of 0.3 to 1.2 mg. m -3 , in agreement with previous literature data. The major mass of POC was found on the smallest particles (r 13 C/ 12 C of the small particles is close to the one expected (d 13 C = 26 +- 2 0 //sub infinity/) for atmospheric POC of continental origin. For all the samples analysed so far, it appears that more than 80% of atmospheric POC over remote marine areas is of continental origin. This can be explained either by long-range transport of small sized continental organic aserosols or by the production of POC in the marine atmosphere from a vapor phase organic carbon pool of continental origin. The POC in the large size fraction of marine aerosols ( 13 C = -21 +- 2 0 / 00 ) for POC associated with sea-salt droplets transported to the marine atmosphere

  17. [Impacts of Land Use Changes on Soil Light Fraction and Particulate Organic Carbon and Nitrogen in Jinyun Mountain].

    Science.gov (United States)

    Lei, Li-guo; Jiang, Chang-sheng; Hao, Qing-ju

    2015-07-01

    Four land types including the subtropical evergreen broad-leaved forest, sloping farmland, orchard and abandoned land were selected to collect soil samples from 0 to 60 cm depth at the same altitude of sunny slope in the Jinyun Mountain in this study. Soil light fraction organic carbon and nitrogen ( LFOC and LFON), and particulate organic carbon and nitrogen (POC and PON) were determined and the distribution ratios and C/N ratios were calculated. The results showed that the contents of LFOC and LFON decreased significantly by 71. 42% and 38. 46% after the forest was changed into sloping farmland (P 0. 05), while the contents of LFOC and LFON increased significantly by 3. 77 and 1. 38 times after the sloping farmland was changed into abandoned land (P organic carbon and nitrogen accumulation; on the contrary, sloping farmland was easy to lose soil labile carbon and nitrogen. The LFOC and LFON distribution ratios were significantly reduced by 31. 20% and 30. 08%, respectively after the forest was changed into the sloping farmland, and increased by 18. 74% and 20. 33% respectively after the forest was changed into the orchard. Nevertheless, the distribution ratios of LFOC and LFON were changed little by converting the forest into the sloping farmland and orchard. The distribution ratios of LFOC, LFON, POC and PON all increased significantly after the farmland was abandoned (P organic carbon and nitrogen was enhanced after forest reclamation, while reduced after the sloping farmland was abandoned. The ratios of carbon to nitrogen in soil organic matter, light fraction organic matter and particulate organic matter were in the order of abandoned land (12. 93) > forest (8. 53) > orchard (7. 52) > sloping farmland (4. 40), abandoned land (16. 32) > forest (14. 29) > orchard (11. 32) > sloping farmland (7. 60), abandoned land (23. 41) > sloping farmland (13. 85 ) > forest (10. 30) > orchard (9. 64), which indicated that the degree of organic nitrogen mineralization was

  18. Impacts of traffic emissions on atmospheric particulate nitrate and organics at a downwind site on the periphery of Guangzhou, China

    Science.gov (United States)

    Qin, Yi Ming; Tan, Hao Bo; Jie Li, Yong; Schurman, Misha I.; Li, Fei; Canonaco, Francesco; Prévôt, André S. H.; Chan, Chak K.

    2017-09-01

    Particulate matter (PM) pollution on the peripheries of Chinese megacities can be as serious as in cities themselves. Given the substantial vehicular emissions in inner-city areas, the direct transport of primary PM (e.g., black carbon and primary organics) and effective formation of secondary PM from precursors (e.g., NOx and volatile organic compounds) can contribute to PM pollution in buffer zones between cities. To investigate how traffic emissions in inner-city areas impact these adjacent buffer zones, a suite of real-time instruments were deployed in Panyu, downwind from central Guangzhou, from November to December 2014. Nitrate mass fraction was higher on high-PM days, with the average nitrate-to-sulfate ratio increasing from around 0.35 to 1.5 as the PM mass concentration increased from 10 to 160 µg m-3. Particulate nitrate was strongly correlated with excess ammonium (([NH4+] / [SO42-] - 1.5) × [SO42-]), with higher concentrations in December than in November due to lower temperatures. The organic mass fraction was the highest across all PM1 levels throughout the campaign. While organic aerosols (OA) were dominated by secondary organic aerosols (SOA = semi-volatile oxygenated organic aerosols + low-volatility oxygenated organic aerosols) as a campaign average, freshly emitted hydrocarbon-like organic aerosols (HOA) contributed up to 40 % of OA during high-OA periods, which typically occurred at nighttime and contributed 23.8 to 28.4 % on average. This was due to daytime traffic restrictions on heavy-duty vehicles in Guangzhou, and HOA almost increased linearly with total OA concentration. SOA increased as odd oxygen (Ox = O3 + NO2) increased during the day due to photochemistry. A combination of nighttime traffic emissions and daytime photochemistry contributed to the buildup of PM in Panyu. The mitigation of PM pollution in inner-city areas by reducing vehicular traffic can potentially improve air quality in peripheral areas.

  19. Visualization of soil particulate organic matter by means of X-ray CT?

    Science.gov (United States)

    Sleutel, Steven; Van Loo, Denis; Maenhout, Peter; Van Hoorebeke, Luc; Cnudde, Veerle; De Neve, Stefaan

    2014-05-01

    composition of the soil mineral matrix. Furthermore, techniques such as multiple-energy scanning and K-edge imaging, even in the future perhaps in combination with spectral resolving detectors or spectroscopic techniques can could further enhance the potential benefit from this study of X-ray CT staining agents. The high Z elements of the staining agents have unique and characteristic traits that can be detected or quantified with the abovementioned techniques and methods. We conclude that, given resolution limits and inherent presence of partial volume effects staining, X-ray CT-based localization of discrete SOM particles will be limited to a lower limit of 20-50 µm. Still, the improved 3D visualization of OM and soil pore space opens up possibilities for tailored lab experiments with measures of microbial activity, which could generate new insights in carbon cycling at small scales. In addition, we report on a lab incubation experiment in which CO2 respiration from soil cores was monitored (headspace GC analysis) and an X-ray CT approach yielded soil pore size distributions. We incubated a sandy loam soil (with application of ground grass or sawdust) in 18 small aluminium rings (Ø 1 cm, h 1 cm). Bulk density was adjusted to 1.1 or 1.3 Mg m-3 (compaction) and 6 rings were filled at a coarser Coarse Sand:Fine Sand:Silt+Clay ratio. While compaction induced a strong reduction in the cumulative C mineralization for both grass and sawdust substrates, artificial change to a coarser soil texture only reduced net C mineralization from the added sawdust. There thus appears to be a strong interaction effect between soil pore structure and substrate type on substrate decomposition. Correlation coefficients between the C mineralization rates and volumes of 7 pore size classes (from the X-ray CT data) also showed an increasing positive correlation with increasing pore size. Since any particulate organic matter initially present in the soil was removed prior to the experiment (sieving

  20. Toxicologically important trace elements and organic compounds investigated in size-fractionated urban particulate matter collected near the Prague highway

    International Nuclear Information System (INIS)

    Sysalová, Jiřina; Sýkorová, Ivana; Havelcová, Martina; Száková, Jiřina; Trejtnarová, Hana; Kotlík, Bohumil

    2012-01-01

    Urban particulate matter was collected in the most exposed area of Prague, near a busy highway, in order to provide petrographic and chemical characterization useful for health impact assessment in that locality or other applications. Samples were collected from filters of the air conditioning system in two years, 2009 and 2010, and sieved into four grain-size fractions: 0.507–0.119 mm, 0.119–0.063 mm, 3 extracted solutions. A composition of inorganic and carbonaceous particles of natural and anthropogenic origin and their morphology were studied by optical and electron microscopy. Organic solvent extracts of the samples were analyzed using gas chromatography to compare the organic compound distribution in fractions. Only slight differences between 2009 and 2010 years are visible. The relatively high extractable part of most investigated elements confirms mobility and potential availability to organisms. The changes can be recognized in the petrographic and organic composition in samples from both years, which were likely the result of various inputs of source materials. Specific organic marker compounds indicate contribution from fossil fuels, plant materials and bacteria. -- Highlights: ► Uncommon urban particulate matter collected near the highway in years 2009 and 2010 was deeply characterized. ► Harmful organic compounds and toxic analytes were tested in grain-size fractions and completed with electron microscopy studies. ► Very similar concentration levels were found in elemental composition in samples from two years. ► Petrographic and organic compositions were different in both samples. ► Relatively high mobility of selected analytes was found in 2M HNO 3 extracted solutions.

  1. Isotopic composition of nitrate and particulate organic matter in a pristine dam reservoir of western India: Implications for biogeochemical processes

    Digital Repository Service at National Institute of Oceanography (India)

    Bardhan, P.; Naqvi, S.W.A.; Karapurkar, S.G.; Shenoy, D.M.; Kurian, S.; Naik, H.

    , 767–779, 2017 www.biogeosciences.net/14/767/2017/ doi:10.5194/bg-14-767-2017 © Author(s) 2017. CC Attribution 3.0 License. Isotopic composition of nitrate and particulate organic matter in a pristine dam reservoir of western India: implications... basis. Samples for nitrate isotopic measurements were col- lected from 2011. The facility for nitrate isotope analysis was Biogeosciences, 14, 767–779, 2017 www.biogeosciences.net/14/767/2017/ P. Bardhan et al.: Isotopic composition of nitrate and POM...

  2. Carbon isotopic ratio of suspended organic matter of the Gironde estuary. Application to particulate Zn and Pb distribution

    International Nuclear Information System (INIS)

    Fontugne, Michel; Jouanneau, J.M.

    1981-01-01

    In the Gironde estuary, the isotopic ratio of particulate organic carbon (P.O.C.), and the ratio metal/P.O.C. indicate the occurrence of two zones. Up-river, the concentration decreases due to the consumption of the organo-metallic phase and by mixing in the ''mud plug'' with terrestrial particles impoverished in metal and P.O.C. Down-stream, the mixing of metal rich terrestrial P.O.C. with poorer marine particles determines the metal concentrations [fr

  3. Phage-Bacterial Dynamics with Spatial Structure: Self Organization around Phage Sinks Can Promote Increased Cell Densities.

    Science.gov (United States)

    Bull, James J; Christensen, Kelly A; Scott, Carly; Jack, Benjamin R; Crandall, Cameron J; Krone, Stephen M

    2018-01-29

    Bacteria growing on surfaces appear to be profoundly more resistant to control by lytic bacteriophages than do the same cells grown in liquid. Here, we use simulation models to investigate whether spatial structure per se can account for this increased cell density in the presence of phages. A measure is derived for comparing cell densities between growth in spatially structured environments versus well mixed environments (known as mass action). Maintenance of sensitive cells requires some form of phage death; we invoke death mechanisms that are spatially fixed, as if produced by cells. Spatially structured phage death provides cells with a means of protection that can boost cell densities an order of magnitude above that attained under mass action, although the effect is sometimes in the opposite direction. Phage and bacteria self organize into separate refuges, and spatial structure operates so that the phage progeny from a single burst do not have independent fates (as they do with mass action). Phage incur a high loss when invading protected areas that have high cell densities, resulting in greater protection for the cells. By the same metric, mass action dynamics either show no sustained bacterial elevation or oscillate between states of low and high cell densities and an elevated average. The elevated cell densities observed in models with spatial structure do not approach the empirically observed increased density of cells in structured environments with phages (which can be many orders of magnitude), so the empirical phenomenon likely requires additional mechanisms than those analyzed here.

  4. The FOODBANCS project: Introduction and sinking fluxes of organic carbon, chlorophyll- a and phytodetritus on the western Antarctic Peninsula continental shelf

    Science.gov (United States)

    Smith, Craig R.; Mincks, Sarah; DeMaster, David J.

    2008-11-01

    The impact of the highly seasonal Antarctic primary production cycle on shelf benthic ecosystems remains poorly evaluated. Here we describe a times-series research project on the West Antarctic Peninsula (WAP) shelf designed to evaluate the seafloor deposition, and subsequent ecological and biogeochemical impacts, of the summer phytoplankton bloom along a transect crossing the Antarctic shelf near Anvers Island. During this project, entitled Food for Benthos on the Antarctic Continental Shelf (FOODBANCS), we deployed replicate sediment traps 150-170 m above the seafloor (total water-column depth of 590 m) on the central shelf from December 1999 to March 2001, recovering trap samples every 3-4 months. In addition, we used a seafloor time-lapse camera system, as well as video surveys conducted at 3-4 months intervals, to monitor the presence and accumulation of phytodetritus at the sediment-water interface. The fluxes of particulate organic carbon and chlorophyll- a into sediment traps (binned over 3-4 month intervals) showed patterns consistent with seasonal variability, with average summer fluxes during the first year exceeding winter fluxes by a factor of ˜2-3. However, inter-annual variability in summer fluxes was even greater than seasonal variability, with 4-10-fold differences in the flux of organic carbon and chlorophyll- a between the summer seasons of 1999-2000 and 2000-2001. Phytodetrital accumulation at the shelf floor also exhibited intense inter-annual variability, with no visible phytodetritus from essentially December 1999 to November 2000, followed by pulsed accumulation of 1-2 cm of phytodetritus over a ˜30,000 km 2 shelf area by March 2001. Comparisons with other studies suggest that the levels of inter-annual variability we observed are typical of the Antarctic shelf over decadal time scales. We conclude that fluxes of particulate organic carbon, chlorophyll- a and phytodetritus to WAP-shelf sediments vary intensely on seasonal to inter

  5. What's Up with Sinking?

    Science.gov (United States)

    Blintz, William

    2005-01-01

    In Hamlet, Shakespeare invites readers to ponder a famous philosophical question: To be or not to be? That is the question. In this issue, two trade books invite students to explore the question: To sink or not to sink? That is the experiment. Though both books are targeted for younger children, teachers can use these books with elementary…

  6. Chemical composition of phytoplankton and Particulate Organic Matter in the Ría de Vigo (NW Spain

    Directory of Open Access Journals (Sweden)

    A. F. Ríos

    1998-09-01

    Full Text Available Elemental (C, H, O, N, Si, P and biochemical composition (proteins, carbohydrates, lipids, phosphorus compounds, chlorophyll and opal in particulate organic matter, diatoms, other autotrophs, heterotrophs and detritus from natural plankton were established simultaneously by measuring relatively few components. Using standard techniques in marine chemistry on board ship, it is possible to infer a great deal about the composition and condition of the plankton. In addition, the organic matter content in terms of cell volume was determined for each group of plankton. Variation of chemical composition with depth was also considered. The ratio carbohydrates/lipids (Cbh/Lip was used as an indicator of the chemical quality of the plankton.

  7. Seasonal Variation in the Quality of Dissolved and Particulate Organic Matter Exchanged Between a Salt Marsh and Its Adjacent Estuary

    Science.gov (United States)

    Osburn, C. L.; Mikan, M.; Etheridge, J. R.; Burchell, M. R.; Birgand, F.

    2015-12-01

    Salt marshes are transitional ecosystems between terrestrial and marine environments. Along with mangroves and other vegetated coastal habitats, salt marshes rank among the most productive ecosystems on Earth, with critical global importance for the planet's carbon cycle. Fluorescence was used to examine the quality of dissolved and particulate organic matter (DOM and POM) exchanging between a tidal creek in a created salt marsh and its adjacent estuary in eastern North Carolina, USA. Samples from the creek were collected hourly over four tidal cycles in May, July, August, and October of 2011. Absorbance and fluorescence of chromophoric DOM (CDOM) and of base-extracted POM (BEPOM) served as the tracers for organic matter quality while dissolved organic carbon (DOC) and base-extracted particulate organic carbon (BEPOC) were used to compute fluxes. Fluorescence was modeled using parallel factor analysis (PARAFAC) and principle components analysis (PCA) of the PARAFAC results. Of nine PARAFAC components modeled, we used multiple linear regression to identify tracers for recalcitrant DOM; labile soil-derived source DOM; detrital POM; and planktonic POM. Based on mass balance, recalcitrant DOC export was 86 g C m-2 yr-1 and labile DOC export was 49 g C m-2 yr-1. The marsh also exported 41 g C m-2 yr-1 of detrital terrestrial POC, which likely originated from lands adjacent to the North River estuary. Planktonic POC export from the marsh was 6 g C m-2 yr-1. Using the DOM and POM quality results obtained via fluorescence measurements and scaling up to global salt marsh area, we estimated that the potential release of CO2 from the respiration of salt marsh DOC and POC transported to estuaries could be 11 Tg C yr-1, roughly 4% of the recently estimated CO2 release for marshes and estuaries globally.

  8. Toxic potential of organic constituents of submicron particulate matter (PM1) in an urban road site (Barcelona).

    Science.gov (United States)

    Mesquita, Sofia R; van Drooge, Barend L; Dall'Osto, Manuel; Grimalt, Joan O; Barata, Carlos; Vieira, Natividade; Guimarães, Laura; Piña, Benjamin

    2017-06-01

    Atmospheric particulate matter (PM) is a recognized risk factor contributing to a number of diseases in human populations and wildlife globally. Organic matter is a major component of PM, but its contribution to overall toxicity of PM has not been thoroughly evaluated yet. In the present work, the biological activity of organic extracts from PM1 (particles with less than 1 μm of aerodynamic diameter) collected from an urban road site in the centre of Barcelona (NE Spain) was evaluated using a yeast-based assay (AhR-RYA) and different gene expression markers in zebrafish embryos. Dioxin-like activity of the extracts correlated to primary emissions from local traffic exhausts, reflecting weekday/weekend alternance. Expression levels of cyp1a and of gene markers for key cellular processes and development (ier2, fos) also correlated to vehicle emissions, whereas expression of gene markers related to antioxidant defence and endocrine effects (gstal, hao1, ttr) was strongly reduced in samples with strong contribution from regional air masses with aged secondary organic species or with strong influence of biomass burning emissions. Our data suggest that the toxic potential of PM1 organic chemical constituents strongly depends on the emission sources and on the process of ageing from primary to secondary organic aerosols.

  9. Toxicologically important trace elements and organic compounds investigated in size-fractionated urban particulate matter collected near the Prague highway.

    Science.gov (United States)

    Sysalová, Jiřina; Sýkorová, Ivana; Havelcová, Martina; Száková, Jiřina; Trejtnarová, Hana; Kotlík, Bohumil

    2012-10-15

    Urban particulate matter was collected in the most exposed area of Prague, near a busy highway, in order to provide petrographic and chemical characterization useful for health impact assessment in that locality or other applications. Samples were collected from filters of the air conditioning system in two years, 2009 and 2010, and sieved into four grain-size fractions: 0.507-0.119 mm, 0.119-0.063 mm, origin and their morphology were studied by optical and electron microscopy. Organic solvent extracts of the samples were analyzed using gas chromatography to compare the organic compound distribution in fractions. Only slight differences between 2009 and 2010 years are visible. The relatively high extractable part of most investigated elements confirms mobility and potential availability to organisms. The changes can be recognized in the petrographic and organic composition in samples from both years, which were likely the result of various inputs of source materials. Specific organic marker compounds indicate contribution from fossil fuels, plant materials and bacteria. Copyright © 2012 Elsevier B.V. All rights reserved.

  10. Some aspects of organic and inorganic particulate transport at Rocky Flats. Final report

    International Nuclear Information System (INIS)

    Nichols, H.

    Findings from the summer 1975 sampling program and the conclusions from the 1975-1976 winter sampling program are summarized. Large radionuclide particles were not found attached to pollen. Sampling the airborne pollen throughout the Rocky Flats area demonstrated that the Rocky Flats air samplers were deficient in their abilities to properly collect large lightweight pollen grains. This may not have serious consequences for the undetected transport of radionuclides by pollen, however, it has implications of sampling inefficiency in some particulate size ranges, and implies that if radionuclides are carried at times by larger particles, then the standard Rocky Flats air samplers are not sampling these materials efficiently. Some initial findings suggested that soil samples from downwind areas associated with winter snow accumulation had abnormally high fissile particle accumulations, and this suggested the need to sample these sites in winter. Areas of preferred particle accumulation such as snow banks had higher concentrations of radionuclide particles than surrounding areas which are more windswept. Any soil sampling program at Rocky Flats which seeks to monitor background radionuclide levels and movement of fissile particles across the site should take account of these topographically and wind-controlled accumulation areas, and not rely solely on a grid pattern of sampling. The snow samples contained radionuclide material in substantial quantities. In terms of fissile particulates smaller than 0.5 microns the snow banks three miles east of the plant site contained as much or more radionuclides than sites close to the Hot Spot contaminated area. The snow samples immediately east of the Hot Spot contained many more large particles (>0.5 m), as did soil samples from the upwind site next to the plant fence. The Hot Spot is clearly implicated again as the source of these materials

  11. Modeling the current and future role of particulate organic nitrates in the southeastern United States

    Science.gov (United States)

    Organic nitrates are an important aerosol constituent in locations where biogenic hydrocarbon emissions mix with anthropogenic NOx sources. While regional and global chemical transport models may include a representation of organic aerosol from monoterpene reactions with nitrate ...

  12. Carbon and nitrogen isotopic compositions of particulate organic matter and biogeochemical processes in the eutrophic Danshuei Estuary in northern Taiwan

    International Nuclear Information System (INIS)

    Liu, K.-K.; Kao, S.-J.; Wen, L.-S.; Chen, K.-L.

    2007-01-01

    The Danshuei Estuary is distinctive for the relatively short residence time (1-2 d) of its estuarine water and the very high concentration of ammonia, which is the dominant species of dissolved inorganic nitrogen in the estuary, except near the river mouth. These characteristics make the dynamics of nitrogen cycling distinctively different from previously studied estuaries and result in unusual isotopic compositions of particulate nitrogen (PN). The δ 15 N PN values ranging from - 16.4 per mille to 3.8 per mille lie in the lower end of nitrogen isotopic compositions (- 16.4 to + 18.7 per mille ) of suspended particulate matter observed in estuaries, while the δ 13 C values of particulate organic carbon (POC) and the C/N (organic carbon to nitrogen) ratios showed rather normal ranges from - 25.5 per mille to - 19.0 per mille and from 6.0 to 11.3, respectively. There were three major types of particulate organic matter (POM) in the estuary: natural terrigenous materials consisting mainly of soils and bedrock-derived sediments, anthropogenic wastes and autochthonous materials from the aquatic system. During the typhoon induced flood period in August 2000, the flux-weighted mean of δ 13 C POC values was - 24.4 per mille , that of δ 15 N PN values was + 2.3 per mille and that of C/N ratio was 9.3. During non-typhoon periods, the concentration-weighted mean was - 23.6 per mille for δ 13 C POC , - 2.6 per mille for δ 15 N PN and 8.0 for C/N ratio. From the distribution of δ 15 N PN values of highly polluted estuarine waters, we identified the waste-dominated samples and calculated their mean properties: δ 13 C POC value of - 23.6 ± 0.7 per mille , δ 15 N PN value of - 3.0 ± 0.1 per mille and C/N ratio of 8.0 ± 1.4. Using a three end-member mixing model based on δ 15 N PN values and C/N ratios, we calculated contributions of the three major allochthonous sources of POC, namely, wastes, soils and bedrock-derived sediments, to the estuary. Their contributions

  13. Origin, composition and quality of suspended particulate organic matter in relation to freshwater inflow in a South Texas estuary

    Science.gov (United States)

    Lebreton, Benoit; Beseres Pollack, Jennifer; Blomberg, Brittany; Palmer, Terence A.; Adams, Leslie; Guillou, Gaël; Montagna, Paul A.

    2016-03-01

    South Texas has a semi-arid climate with a large interannual variability of freshwater inflows. This study sought to define how changes in freshwater inflow affect the composition, quantity and quality of suspended particulate organic matter (SPOM) in a South Texas estuary: the Mission-Aransas estuary. The study was implemented 1.5 months after a large rain event in September 2010 and continued for 10 months of drought conditions. The composition of SPOM originating from rivers, the Gulf of Mexico and the estuary were determined using stable isotopes (δ13C, δ15N and δ34S). The quantity and quality of SPOM were assessed using organic carbon content, chlorophyll a concentrations and C/chl a ratios. Our results demonstrated that autochthonous phytoplankton was the dominant component of SPOM in the Mission-Aransas estuary during droughts. Benthic organic matter from local primary producers (i.e., seagrass, salt marsh plants, benthic microalgae) did not influence SPOM composition, either as fresh material or as detritus. A comparison with a positive estuary (i.e., Sabine-Neches estuary, TX) indicates that decreases in freshwater inflow may lead to decreases of terrestrial organic matter inputs and to increase the ratio of autochtonous phytoplanktonic material in SPOM.

  14. Diagenetic fractionation of carbon isotopes in particulate and dissolved organic matter in sediments from Skan Bay, Alaska

    International Nuclear Information System (INIS)

    Alperin, M.J.; Reeburgh, W.S.

    1991-01-01

    Isotope fractionation during organic matter diagenesis was investigated by measuring detailed depth distributions of stable carbon isotope ratios in sediment particulate organic carbon (POC) and dissolved organic carbon (DOC) reservoirs. The δ 13 C value of the POC shifted systematically from -19 per-thousand at the surface to -21 per-thousand at 10 cm. Significant trends were also apparent in the δ 13 C-DOC profile. Proceeding down-core, DOC became isotopically heavier between 0 and 5 cm and isotopically lighter at greater depths. Two mechanisms could account for the observed down-core shift in δ 13 C-POC: (a) temporal changes in the isotope ratios of deposited organic matter and (b) isotope fractionation associated with diagenesis. The δ 15 C-DOC depth distribution is sensitive to which mechanism controls the isotopic composition of the POC reservoir. A diagenetic model that couples POC and DOC reservoirs was used to discriminate between temporal changes and diagenetic alteration of the POC isotopic composition. The model indicated that observed trends in δ 13 C-POC and δ 13 C-DOC depth distributions are consistent with isotopic fractionation of POC during diagenesis

  15. Diffusive component of the vertical flux of particulate organic carbon in the north polar Atlantic

    Directory of Open Access Journals (Sweden)

    Małgorzata Stramska

    2006-12-01

    Full Text Available The diffusive component of the vertical flux of particulate organiccarbon (POC from the surface ocean layer has been estimatedusing a combination of the mixed layer model and ocean colordata from the SeaWiFS satellite. The calculations were carriedout for an example location in the north polar Atlantic centeredat 75°N and 0°E for the time period of 1998-2004.The satellite estimates of surface POC derived using a regional ocean coloralgorithm were applied as an input to the model driven by localsurface heat and momentum fluxes. For each year of the examinedperiod, the diffusive POC flux was estimated at 200-m depth fromApril through December. The highest flux is generally observedin the late fall as a result of increased heat loss and convectionalmixing of surface waters. A relatively high diffusive POC fluxis also observed in early spring, when surface waters are weaklystratified. In addition, the model results demonstrate significantinterannual variability. The highest diffusive POC flux occurredin 1999 (about 4500 mg m-2 over the 9-month period. In 1998 and 2002 the estimated flux was about two orders of magnitudelower. The interannual variability of the diffusive POC fluxis associated with mixed layer dynamics and underscores the importanceof atmospheric forcing for POC export from the surface layerto the ocean's interior.

  16. Particulate organic compounds in the atmosphere surrounding an industrialised area of Prato (Italy)

    Science.gov (United States)

    Cincinelli, Alessandra; Mandorlo, Stefano; Dickhut, Rebecca M.; Lepri, Luciano

    Atmospheric aerosols were collected during the period from May 2000 through January 2001 at 13 different sites in and around the Baciacavallo sewage treatment plant in Prato (Italy). The urban area surrounding the plant contains significant textile industrial activity and a main arterial road. Aerosol-associated n-alkane, polycyclic aromatic hydrocarbon (PAH), nonylphenol (NP) and nonylphenolethoxylate (NPnEO) ( n=1-3) concentrations were measured in order to evaluate contributions from the sewage treatment plant, naturally produced aerosols, transportation and industrial activities to the air quality in the vicinity of the sewage treatment plant. Aerosol-associated n-alkane concentrations ranged from 36.7 to 205 ng/m 3 and their possible origin was determined by the presence of typical petroleum characteristics such as the unresolved complex mixture and an odd/even carbon ratio (Carbon Preference Index). PAH concentrations ranged from 0.855 to 24.2 ng/m 3, in accordance with those generally found for urban aerosols in Europe. NP and NPnEO ( n=1-3), as well as fine aerosol particulate matter (PM 10) were significantly correlated with relative wind direction with increased levels observed in the ambient atmosphere when the relative wind direction was from the Baciacavallo sewage treatment plant. This study confirms the use of NP and NPnEO ( n=1-3) as markers of sewage treatment emissions and the importance of the contribution of aerosols produced by sewage treatment plant aeration tanks to the local atmospheric composition.

  17. Origin and fate of particulate and dissolved organic matter in a naturally iron-fertilized region of the Southern Ocean

    Science.gov (United States)

    Tremblay, L.; Caparros, J.; Leblanc, K.; Obernosterer, I.

    2015-01-01

    Natural iron fertilization of high-nutrient low-chlorophyll (HNLC) waters induces annually occurring spring phytoplankton blooms off the Kerguelen Islands (Southern Ocean). To examine the origin and fate of particulate and dissolved organic matter (POM and DOM), D- and L-amino acids (AA) were quantified at bloom and HNLC stations. Total hydrolyzable AA accounted for 21-25% of surface particulate organic carbon (%POCAA) at the bloom sites, but for 10% at the HNLC site. A marked decrease in %POCAA with depth was observed at the most productive stations leading to values between 3 and 5% below 300 m depth. AA contributed to only 0.9-4.4% of dissolved organic carbon (%DOCAA) at all stations. The only consistent vertical trend was observed at the most productive station (A3-2) where %DOCAA decreased from ~ 2% in the surface waters to 0.9% near 300 m. These AA yields revealed that POM and DOM were more rapidly altered or mineralized at the bloom sites compared to the HNLC site. Alteration state was also assessed by trends in C / N ratio, %D-AA and degradation index. Different molecular markers indicated that POM mostly originated from diatoms and bacteria. The estimated average proportion of POM from intact phytoplankton cells in surface waters was 45% at the bloom station A3-2, but 14% at the HNLC site. Estimates based on D-AA yields indicated that ~ 15% of POM and ~ 30% of DOM was of bacterial origin (cells and cell fragments) at all stations. Surprisingly, the DOM in HNLC waters appeared less altered than the DOM from the bloom, had slightly higher dissolved AA concentrations, and showed no sign of alteration within the water column. Unfavorable conditions for bacterial degradation in HNLC regions can explain these findings. In contrast, large inputs of labile organic molecules and iron likely stimulate the degradation of organic matter (priming effect) and the production of more recalcitrant DOM (microbial carbon pump) during iron-fertilized blooms.

  18. Extraction of semivolatile organic compounds from high-efficiency particulate air (HEPA) filters by supercritical carbon dioxide

    International Nuclear Information System (INIS)

    Schilling, J.B.

    1997-09-01

    Supercritical fluid extraction (SFE) using unmodified carbon dioxide has been explored as an alternative method for the extraction of semivolatile organic compounds from high-efficiency particulate air (HEPA) filters. HEPA filters provide the final stage of containment on many exhaust systems in US Department of Energy (DOE) facilities by preventing the escape of chemical and radioactive materials entrained in the exhausted air. The efficiency of the filters is tested by the manufacturer and DOE using dioctylphthalate (DOP), a substance regulated by the US Environmental Protection Agency under the Resource Conservation and Recovery Act. Therefore, the filters must be analyzed for semivolatile organics before disposal. Ninety-eight acid, base, and neutral semivolatile organics were spiked onto blank HEPA material and extracted using SFE, Soxhlet, automated Soxhlet, and sonication techniques. The SFE conditions were optimized using a Dionex SFE-703 instrument. Average recoveries for the 98 semivolatile compounds are 82.7% for Soxhlet, 74.0% for sonication, 70.2% for SFE, and 62.9% for Soxtec. Supercritical fluid extraction reduces the extraction solvent volume to 10--15 mL, a factor of 20--30 less than Soxhlet and more than 5 times less than Soxtec and sonication. Extraction times of 30--45 min are used compared to 16--18 h for Soxhlet extraction

  19. Chemical characterization of organic particulate matter from on-road traffic in São Paulo, Brazil

    Directory of Open Access Journals (Sweden)

    B. S. Oyama

    2016-11-01

    Full Text Available This study reports emission of organic particulate matter by light-duty vehicles (LDVs and heavy-duty vehicles (HDVs in the city of São Paulo, Brazil, where vehicles run on three different fuel types: gasoline with 25 % ethanol (called gasohol, E25, hydrated ethanol (E100, and diesel (with 5 % biodiesel. The experiments were performed at two tunnels: Jânio Quadros (TJQ, where 99 % of the vehicles are LDVs, and RodoAnel Mário Covas (TRA, where up to 30 % of the fleet are HDVs. Fine particulate matter (PM2.5 samples were collected on quartz filters in May and July 2011 at TJQ and TRA, respectively. The samples were analyzed by thermal-desorption proton-transfer-reaction mass spectrometry (TD-PTR-MS and by thermal–optical transmittance (TOT. Emission factors (EFs for organic aerosol (OA and organic carbon (OC were calculated for the HDV and the LDV fleet. We found that HDVs emitted more PM2.5 than LDVs, with OC EFs of 108 and 523 mg kg−1 burned fuel for LDVs and HDVs, respectively. More than 700 ions were identified by TD-PTR-MS and the EF profiles obtained from HDVs and LDVs exhibited distinct features. Unique organic tracers for gasoline, biodiesel, and tire wear have been tentatively identified. nitrogen-containing compounds contributed around 20 % to the EF values for both types of vehicles, possibly associated with incomplete fuel burning or fast secondary production. Additionally, 70 and 65 % of the emitted mass (i.e. the OA originates from oxygenated compounds from LDVs and HDVs, respectively. This may be a consequence of the high oxygen content of the fuel. On the other hand, additional oxygenation may occur during fuel combustion. The high fractions of nitrogen- and oxygen-containing compounds show that chemical processing close to the engine / tailpipe region is an important factor influencing primary OA emission. The thermal-desorption analysis showed that HDVs emitted compounds with higher volatility, and with

  20. Enhanced Input of Terrestrial Particulate Organic Matter Reduces the Resilience of the Clear-Water State of Shallow Lakes: A Model Study

    NARCIS (Netherlands)

    Lischke, B.; Hilt, S.; Janse, J.H.; Kuiper, J.J.; Mehner, T.; Mooij, W.M.; Gaedke, U.

    2014-01-01

    The amount of terrestrial particulate organic matter (t-POM) entering lakes is predicted to increase as a result of climate change. This may especially alter the structure and functioning of ecosystems in small, shallow lakes which can rapidly shift from a clear-water, macrophyte-dominated into a

  1. Source apportionment of airborne particulate matter using organic compounds as tracers

    Science.gov (United States)

    Schauer, James J.; Rogge, Wolfgang F.; Hildemann, Lynn M.; Mazurek, Monica A.; Cass, Glen R.; Simoneit, Bernd R. T.

    A chemical mass balance receptor model based on organic compounds has been developed that relates source contributions to airborne fine particle mass concentrations. Source contributions to the concentrations of specific organic compounds are revealed as well. The model is applied to four air quality monitoring sites in southern California using atmospheric organic compound concentration data and source test data collected specifically for the purpose of testing this model. The contributions of up to nine primary particle source types can be separately identified in ambient samples based on this method, and approximately 85% of the organic fine aerosol is assigned to primary sources on an annual average basis. The model provides information on source contributions to fine mass concentrations, fine organic aerosol concentrations and individual organic compound concentrations. The largest primary source contributors to fine particle mass concentrations in Los Angeles are found to include diesel engine exhaust, paved road dust, gasoline-powered vehicle exhaust, plus emissions from food cooking and wood smoke, with smaller contribution from tire dust, plant fragments, natural gas combustion aerosol, and cigarette smoke. Once these primary aerosol source contributions are added to the secondary sulfates, nitrates and organics present, virtually all of the annual average fine particle mass at Los Angeles area monitoring sites can be assigned to its source.

  2. Nighttime residential wood burning evidenced from an indirect method for estimating real-time concentration of particulate organic matter (POM)

    International Nuclear Information System (INIS)

    Sciare, J.; Sarda-Esteve, R.; Favez, O.; Cachier, H.; Aymoz, G.; Laj, P.

    2008-01-01

    Real-time analyzers of selected chemical components (sulfate, nitrate, Black Carbon) and integrative aerosol parameters (particulate matter and light scattering coefficient) were implemented for a 2-week campaign (November-December 2005) in a suburban area of Clermont-Ferrand (France) in order to document fast changes in the chemical composition of submicron aerosols. Measurements of particulate organic matter (POM) were not available in the field but were indirectly estimated from time-resolved (3-min) reconstruction of the light scattering coefficient. This methodology offered the opportunity to investigate almost real-time and artifact-free POM concentrations even at low concentrations (typically below 0.1 mu g m(-3)). The overall uncertainties associated with this POM calculation were of the order of 20%, which are comparable to those commonly referred in literature for POM calculation or measurements. A chemical mass balance (CMB) of PM1 was performed using the derived POM concentrations and showed a very good correlation (slope = 0.93; r(2) = 0.91, N = 663) with real-time PM1 measurements obtained from R and P TEOM-FDMS, demonstrating the consistency of our approach. Important diurnal variations were observed in POM concentrations, with a dominant contribution of POM from fossil fuel origin during daytime and a dominant contribution of POM from residential wood burning at night. POM was calculated to contribute as much as 70% of PM1 during our study, pointing out the major role of carbonaceous aerosols at this period of the year at our residential area. (authors)

  3. From Solute, Fluidic and Particulate Precursors to Complex Organizations of Matter.

    Science.gov (United States)

    Rao, Ashit; Cölfen, Helmut

    2018-03-24

    The organization of matter from its constitutive units recruits intermediate states with distinctive degrees of self-association and molecular order. Existing as clusters, droplets, gels as well as amorphous and crystalline nanoparticles, these precursor forms have fundamental contributions towards the composition and structure of inorganic and organic architectures. In this personal account, we show that the transitions from atoms, molecules or ionic species to superstructures of higher order are intertwined with the interfaces and interactions of precursor and intermediate states. Structural organizations distributed across different length scales are explained by the multistep nature of nucleation and crystallization, which can be guided towards functional hybrid materials by the strategic application of additives, templates and reaction environments. Thus, the non-classical pathways for material formation and growth offer conceptual frameworks for elucidating, inducing and directing fascinating material organizations of biogenic and synthetic origins. © 2018 The Chemical Society of Japan & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Investigating organic matter in Fanno Creek, Oregon, Part 2 of 3: sources, sinks, and transport of organic matter with fine sediment

    Science.gov (United States)

    Keith, Mackenzie K.; Sobieszczyk, Steven; Goldman, Jami H.; Rounds, Stewart A.

    2014-01-01

    Organic matter (OM) is abundant in Fanno Creek, Oregon, USA, and has been tied to a variety of water-quality concerns, including periods of low dissolved oxygen downstream in the Tualatin River, Oregon. The key sources of OM in Fanno Creek and other Tualatin River tributaries have not been fully identified, although isotopic analyses from previous studies indicated a predominantly terrestrial source. This study investigates the role of fine sediment erosion and deposition (mechanisms and spatial patterns) in relation to OM transport. Geomorphic mapping within the Fanno Creek floodplain shows that a large portion (approximately 70%) of the banks are eroding or subject to erosion, likely as a result of the imbalance caused by anthropogenic alteration. Field measurements of long- and short-term bank erosion average 4.2 cm/year and average measurements of deposition for the watershed are 4.8 cm/year. The balance between average annual erosion and deposition indicates an export of 3,250 metric tons (tonnes, t) of fine sediment to the Tualatin River—about twice the average annual export of 1,880 t of sediment at a location 2.4 km from the creek’s mouth calculated from suspended sediment load regressions from continuous turbidity data and suspended sediment samples. Carbon content from field samples of bank material, combined with fine sediment export rates, indicates that about 29–67 t of carbon, or about 49–116 t of OM, from bank sediment may be exported to the Tualatin River from Fanno Creek annually, an estimate that is a lower bound because it does not account for the mass wasting of organic-rich O and A soil horizons that enter the stream.

  5. Particulate metals and organic compounds from electronic and tobacco-containing cigarettes: comparison of emission rates and secondhand exposure.

    Science.gov (United States)

    Saffari, Arian; Daher, Nancy; Ruprecht, Ario; De Marco, Cinzia; Pozzi, Paolo; Boffi, Roberto; Hamad, Samera H; Shafer, Martin M; Schauer, James J; Westerdahl, Dane; Sioutas, Constantinos

    2014-01-01

    In recent years, electronic cigarettes have gained increasing popularity as alternatives to normal (tobacco-containing) cigarettes. In the present study, particles generated by e-cigarettes and normal cigarettes have been analyzed and the degree of exposure to different chemical agents and their emission rates were quantified. Despite the 10-fold decrease in the total exposure to particulate elements in e-cigarettes compared to normal cigarettes, specific metals (e.g. Ni and Ag) still displayed a higher emission rate from e-cigarettes. Further analysis indicated that the contribution of e-liquid to the emission of these metals is rather minimal, implying that they likely originate from other components of the e-cigarette device or other indoor sources. Organic species had lower emission rates during e-cigarette consumption compared to normal cigarettes. Of particular note was the non-detectable emission of polycyclic aromatic hydrocarbons (PAHs) from e-cigarettes, while substantial emission of these species was observed from normal cigarettes. Overall, with the exception of Ni, Zn, and Ag, the consumption of e-cigarettes resulted in a remarkable decrease in secondhand exposure to all metals and organic compounds. Implementing quality control protocols on the manufacture of e-cigarettes would further minimize the emission of metals from these devices and improve their safety and associated health effects.

  6. Identification and semi-quantification of biogenic organic nitrates in ambient particulate matters by UHPLC/ESI-MS

    Science.gov (United States)

    Li, Rui; Wang, Xinfeng; Gu, Rongrong; Lu, Chunying; Zhu, Fanping; Xue, Likun; Xie, Huijun; Du, Lin; Chen, Jianmin; Wang, Wenxing

    2018-03-01

    Particulate biogenic organic nitrates (PBONs) are important components of secondary organic aerosols and play an important role in the tropospheric atmosphere chemistry. However, the concentrations and the chemistry of PBONs remain poorly understood due to the lack of accurate measurement techniques on specific organic nitrates. In this study, ultra high performance liquid chromatography/electrospray mass spectrometry was applied in detection of individual PBONs in ambient atmosphere. Total five kinds of PBONs were identified in PM2.5 samples collected in urban Ji'nan in spring according to characteristic fragments of NO2, NO3, HNO3, CO2, and H2O, including monoterpene hydroxyl nitrate (MW = 215, MHN215), pinene keto nitrate (MW = 229, PKN229), limonene di-keto nitrate (MW = 247, LDKN247), oleic acid keto nitrate (MW = 359, OAKN359), and oleic acid hydroxyl nitrate (MW = 361, OAHN361). Among them, three kinds of PBONs originated from biogenic volatile organic compounds of pinene and limonene and two kinds of PBONs came from chemical conversion of oleic acid. The concentrations of these PBONs were roughly quantified with surrogate standards of (1R,2R,5R)-(+)-2-hydroxy-3-pinanone and ricinoleic acid. The average concentrations of MHN215, PKN229, LDKN247, OAKN359, and OAHN361 were 111.6 ± 23.0, 93.1 ± 49.6, 55.3 ± 7.4, 23.4 ± 14.5, 36.8 ± 18.3 ng m-3, respectively. The total concentration of these PBONs was 325.4 ± 116.7 ng m-3, contributing to 1.64 ± 0.34‰ of PM2.5.

  7. River Export of Dissolved and Particulate Organic Carbon from Permafrost and Peat Deposits across the Siberian Arctic

    Science.gov (United States)

    Wild, B.; Andersson, A.; Bröder, L.; Vonk, J.; Hugelius, G.; McClelland, J. W.; Raymond, P. A.; Gustafsson, O.

    2017-12-01

    Permafrost and peat deposits of northern high latitudes store more than 1300 Pg of organic carbon. This carbon has been preserved for thousands of years by cold and moist conditions, but is now increasingly mobilized as temperatures rise. While part will be degraded to CO2 and CH4 and amplify global warming, part will be exported by rivers to the Arctic Ocean where it can be degraded or re-buried by sedimentation. We here use the four large Siberian rivers Ob, Yenisey, Lena, and Kolyma as natural integrators of carbon mobilization in their catchments. We apply isotope based source apportionments and Markov Chain Monte Carlo Simulations to quantify contributions of organic carbon from permafrost and peat deposits to organic carbon exported by these rivers. More specifically, we compare the 14C signatures of dissolved and particulate organic carbon (DOC, POC) sampled close to the river mouths with those of five potential carbon sources; (1) recent aquatic and (2) terrestrial primary production, (3) the active layer of permafrost soils, (4) deep Holocene deposits (including thermokarst and peat deposits) and (5) Ice Complex Deposits. 14C signatures of these endmembers were constrained based on extensive literature review. We estimate that the four rivers together exported 2.4-4.5 Tg organic carbon from permafrost and peat deposits per year. While total organic carbon export was dominated by DOC (90%), the export of organic carbon from permafrost and peat deposits was more equally distributed between DOC (56%) and POC (44%). Recent models predict that ca. 200 Pg carbon will be lost as CO2 or CH4 by 2100 (RCP8.5) from the circumarctic permafrost area, of which roughly a quarter is drained by the Ob, Yenisey, Lena, and Kolyma rivers. Our comparatively low estimates of river carbon export thus suggest limited transfer of organic carbon from permafrost and peat deposits to high latitude rivers, or its rapid degradation within rivers. Our findings highlight the importance

  8. Development of the GC-MS organic aerosol monitor (GC-MS OAM) for in-field detection of particulate organic compounds

    Science.gov (United States)

    Cropper, Paul M.; Overson, Devon K.; Cary, Robert A.; Eatough, Delbert J.; Chow, Judith C.; Hansen, Jaron C.

    2017-11-01

    Particulate matter (PM) is among the most harmful air pollutants to human health, but due to its complex chemical composition is poorly characterized. A large fraction of PM is composed of organic compounds, but these compounds are not regularly monitored due to limitations in current sampling and analysis techniques. The Organic Aerosol Monitor (GC-MS OAM) combines a collection device with thermal desorption, gas chromatography and mass spectrometry to quantitatively measure the carbonaceous components of PM on an hourly averaged basis. The GC-MS OAM is fully automated and has been successfully deployed in the field. It uses a chemically deactivated filter for collection followed by thermal desorption and GC-MS analysis. Laboratory tests show that detection limits range from 0.2 to 3 ng for 16 atmospherically relevant compounds, with the possibility for hundreds more. The GC-MS OAM was deployed in the field for semi-continuous measurement of the organic markers, levoglucosan, dehydroabietic acid, and polycyclic aromatic hydrocarbons (PAHs) from January to March 2015. Results illustrate the significance of this monitoring technique to characterize the organic components of PM and identify sources of pollution.

  9. Factors influencing soil aggregation and particulate organic matter responses to bioenergy crops across a topographic gradient

    Science.gov (United States)

    Todd A. Ontl; Cynthia A. Cambardella; Lisa A. Schulte; Randall K. Kolka

    2015-01-01

    Bioenergy crops have the potential to enhance soil carbon (C) pools from increased aggregation and the physical protection of organic matter; however, our understanding of the variation in these processes over heterogeneous landscapes is limited. In particular, little is known about the relative importance of soil properties and root characteristics for the physical...

  10. Particulate organic carbon at reclaimed and unreclaimed post-mining soils and its microbial community composition

    Czech Academy of Sciences Publication Activity Database

    Bartuška, Martin; Pawlett, M.; Frouz, Jan

    2015-01-01

    Roč. 131, August (2015), s. 92-98 ISSN 0341-8162 Grant - others:GA ČR(CZ) GAP504/12/1288 Program:GA Institutional support: RVO:60077344 Keywords : soil organic matter * PLFA * chronosequence * succession * reclamation Subject RIV: DF - Soil Science Impact factor: 2.612, year: 2015

  11. Fluxes and burial of particulate organic carbon along the Adriatic mud-wedge (Mediterranean Sea)

    Science.gov (United States)

    Tesi, T.; Langone, L.; Giani, M.; Ravaioli, M.; Miserocchi, S.

    2012-04-01

    Clinoform-shaped deposits are ubiquitous sedimentological bodies of modern continental margins, including both carbonate and silicoclastic platforms. They formed after the attainment of the modern sea level high-stand (mid-late Holocene) when river outlets and shoreline migrated landward. As clinoform-shape deposits are essential building blocks of the infill of sedimentary basins, they are sites of intense organic carbon (OC) deposition and account for a significant fraction of OC burial in the ocean during interglacial periods. In this study, we focused on sigmoid clinoforms that are generally associated with low-energy environments. In particular, we characterized the modern accumulation and burial of OC along the late-Holocene sigmoid in the Western Adriatic Sea (Mediterranean Sea). This sedimentary body consists of a mud wedge recognizable on seismic profiles as a progradational unit lying on top the maximum flooding surface that marks the time of maximum landward shift of the shoreline attained around 5.5 kyr cal BP. In the last two decades, several projects have investigated sediment dynamics and organic geochemistry along the Adriatic mud wedge (e.g., PRISMA, EURODELTA, EuroSTRATAFORM, PASTA, CIPE, VECTOR). All these studies increased our understanding of strata formation and organic matter cycling in this epicontinental margin. The overarching goal of this study was to combine the results gained during these projects with newly acquired data to assess fluxes to seabed and burial efficiency of organic carbon along the uppermost strata of the Adriatic mud-wedge. Our study benefited of an extensive number of radionuclide-based (Pb-210, and Cs-137) sediment accumulation rates and numerous biogeochemical data of surface sediments and sediment cores (organic carbon, total nitrogen, radiocarbon measurements, carbon stable isotopes, and biomarkers). In addition, because the accumulation of river-borne sediment may or may not be linked to a specific source, another

  12. Rapid prediction of particulate, humus and resistant fractions of soil organic carbon in reforested lands using infrared spectroscopy.

    Science.gov (United States)

    Madhavan, Dinesh B; Baldock, Jeff A; Read, Zoe J; Murphy, Simon C; Cunningham, Shaun C; Perring, Michael P; Herrmann, Tim; Lewis, Tom; Cavagnaro, Timothy R; England, Jacqueline R; Paul, Keryn I; Weston, Christopher J; Baker, Thomas G

    2017-05-15

    Reforestation of agricultural lands with mixed-species environmental plantings can effectively sequester C. While accurate and efficient methods for predicting soil organic C content and composition have recently been developed for soils under agricultural land uses, such methods under forested land uses are currently lacking. This study aimed to develop a method using infrared spectroscopy for accurately predicting total organic C (TOC) and its fractions (particulate, POC; humus, HOC; and resistant, ROC organic C) in soils under environmental plantings. Soils were collected from 117 paired agricultural-reforestation sites across Australia. TOC fractions were determined in a subset of 38 reforested soils using physical fractionation by automated wet-sieving and 13 C nuclear magnetic resonance (NMR) spectroscopy. Mid- and near-infrared spectra (MNIRS, 6000-450 cm -1 ) were acquired from finely-ground soils from environmental plantings and agricultural land. Satisfactory prediction models based on MNIRS and partial least squares regression (PLSR) were developed for TOC and its fractions. Leave-one-out cross-validations of MNIRS-PLSR models indicated accurate predictions (R 2  > 0.90, negligible bias, ratio of performance to deviation > 3) and fraction-specific functional group contributions to beta coefficients in the models. TOC and its fractions were predicted using the cross-validated models and soil spectra for 3109 reforested and agricultural soils. The reliability of predictions determined using k-nearest neighbour score distance indicated that >80% of predictions were within the satisfactory inlier limit. The study demonstrated the utility of infrared spectroscopy (MNIRS-PLSR) to rapidly and economically determine TOC and its fractions and thereby accurately describe the effects of land use change such as reforestation on agricultural soils. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. Study of the removal difference in indoor particulate matter and volatile organic compounds through the application of plants

    Directory of Open Access Journals (Sweden)

    Seung-Han Hong

    2017-02-01

    Full Text Available This study was conducted to evaluate the ability of plants to purify indoor air by observing the effective reduction rate among pollutant types of particulate matter (PM and volatile organic compounds (VOCs. PM and four types of VOCs were measured in a new building that is less than three years old and under three different conditions: before applying the plant, after applying the plant, and a room without a plant. The removal rate of each pollutant type due to the plant was also compared and analyzed. In the case of indoor PM, the removal effect was negligible because of outdoor influence. However, 9% of benzene, 75% of ethylbenzene, 72% of xylene, 75% of styrene, 50% of formaldehyde, 36% of acetaldehyde, 35% of acrolein with acetone, and 85% of toluene were reduced. The purification of indoor air by natural ventilation is meaningless because the ambient PM concentration has recently been high. However, contamination by gaseous materials such as VOCs can effectively be removed through the application of plants.

  14. Export of fine particulate organic carbon from redwood-dominated catchments

    Science.gov (United States)

    Madej, Mary Ann

    2015-01-01

    Recently, researchers have recognized the significant role of small mountainous river systems in the transport of carbon from terrestrial environments to the ocean, and the scale of such studies have ranged from channel bed units to continents. In temperate zones, these mountain river systems commonly drain catchments that are largely forested. However, the magnitude of carbon export from rivers draining old-growth redwood forests has not been evaluated to date. Old-growth redwood stands support some of the largest quantities of biomass in the world, up to 350 000 Mg of stem biomass km-2 and soil organic carbon can reach 46 800 Mg km-2. In north coastal California, suspended sediment samples were collected at three gaging stations for two to four years on streams draining old-growth redwood forests. Carbon content, determined through loss-on-ignition tests, was strongly correlated with turbidity, and continuous turbidity records from the gaging stations were used to estimate annual carbon exports of 1 · 6 to 4 · 2 Mg km-2 yr-1. These values, representing 13 to 33% of the suspended sediment load, are some of the highest percentages reported in the global literature. The fraction of organic carbon as part of the suspended sediment load decreased with discharge, but reached an asymptote of 5 to 10% at flows 10 to 20 times the mean annual flows. Although larger rivers in this region exhibit high sediment yields (up to 3600 Mg km-2 yr-1), mainly attributed to high rates of uplift, mass movement, and timber harvest, the small pristine streams in this study have sediment yields of only 8 to 100 Mg km-2 yr-1. Because the current extent of old-growth redwood stands is less than 5% of its pre-European-settlement distribution, the present organic carbon signature in suspended sediment loads in this region is likely different from that in the early 20th century. Published 2015. This article is a U.S. Government work and is in the public

  15. Temporal variability in terrestrially-derived sources of particulate organic carbon in the lower Mississippi River and its upper tributaries

    Science.gov (United States)

    Bianchi, Thomas S.; Wysocki, Laura A.; Stewart, Mike; Filley, Timothy R.; McKee, Brent A.

    2007-09-01

    In this study, we examined the temporal changes of terrestrially-derived particulate organic carbon (POC) in the lower Mississippi River (MR) and in a very limited account, the upper tributaries (Upper MR, Ohio River, and Missouri River). We used for the first time a combination of lignin-phenols, bulk stable carbon isotopes, and compound-specific isotope analyses (CSIA) to examine POC in the lower MR and upper tributaries. A lack of correlation between POC and lignin phenol abundances ( Λ8) was likely due to dilution effects from autochthonous production in the river, which has been shown to be considerably higher than previously expected. The range of δ 13C values for p-hydroxycinnamic and ferulic acids in POC in the lower river do support that POM in the lower river does have a significant component of C 4 in addition to C 3 source materials. A strong correlation between δ 13C values of p-hydroxycinnamic, ferulic, and vanillyl phenols suggests a consistent input of C 3 and C 4 carbon to POC lignin while a lack of correlation between these same phenols and POC bulk δ 13C further indicates the considerable role of autochthonous carbon in the lower MR POC budget. Our estimates indicate an annual flux of POC of 9.3 × 10 8 kg y -1 to the Gulf of Mexico. Total lignin fluxes, based on Λ8 values of POC, were estimated to be 1.2 × 10 5 kg y -1. If we include the total dissolved organic carbon (DOC) flux (3.1 × 10 9 kg y -1) reported by [Bianchi T. S., Filley T., Dria K. and Hatcher, P. (2004) Temporal variability in sources of dissolved organic carbon in the lower Mississippi River. Geochim. Cosmochim. Acta68, 959-967.], we get a total organic carbon flux of 4.0 × 10 9 kg y -1. This represents 0.82% of the annual total organic carbon supplied to the oceans by rivers (4.9 × 10 11 kg).

  16. Particulate and dissolved organic carbon and chlorophyll A in the Zaire river, estuary and plume

    Science.gov (United States)

    Cadée, G. C.

    Data were collected on POC, DOC and phytoplankton in the Zaire river, estuary and plume. Mean river value for POC was 1.1 mg·l -1, 4.7% of the suspended matter. Average DOC content of the river water was 8.5 mg·l -1. These values are in accordance with the calculations of TOC input from rivers to the world's ocean. Within the estuary POC and chlorophyll decreased regularly up to a salinity of 20. Between salinities of 20 and 32 small phytoplankton bloom occurred resulting also in higher POC values. DOC mixed conservatively up to a salinity of 25; at salinities above 25, values indicate DOC production. This DOC production occurred partly in the bottom water of the canyon where low oxygen values indicated mineralization and conversion of the accumulated POC into DOC. Another area of DOC production observed inside and outside the surface waters of the plume, was partly related to autolysis and degradation of the phytoplankton bloom. This study shows that the influence of rivers on the organic carbon in the ocean will not be confined to the amount introduced directly, but that we have to add the amounts of POC and DOC resulting from enhanced phytoplankton primary production by nutrient input from rivers and by river induced upwelling.

  17. Biomarker and carbon isotope constraints (δ13C, Δ14C) on sources and cycling of particulate organic matter discharged by large Siberian rivers draining permafrost areas

    International Nuclear Information System (INIS)

    Winterfeld, Maria

    2014-08-01

    Circumpolar permafrost soils store about half of the global soil organic carbon pool. These huge amounts of organic matter (OM) could accumulate due to low temperatures and water saturated soil conditions over the course of millennia. Currently most of this OM remains frozen and therefore does not take part in the active carbon cycle, making permafrost soils a globally important carbon sink. Over the last decades mean annual air temperatures in the Arctic increased stronger than the global mean and this trend is projected to continue. As a result the permafrost carbon pool is under climate pressure possibly creating a positive climate feedback due to the thaw-induced release of greenhouse gases to the atmosphere. Arctic warming will lead to increased annual permafrost thaw depths and Arctic river runoff likely resulting in enhanced mobilization and export of old, previously frozen soil-derived OM. Consequently, the great arctic rivers play an important role in global biogeochemical cycles by connecting the large permafrost carbon pool of their hinterlands with the arctic shelf seas and the Arctic Ocean. The first part of this thesis deals with particulate organic matter (POM) from the Lena Delta and adjacent Buor Khaya Bay. The Lena River in central Siberia is one of the major pathways translocating terrestrial OM from its southernmost reaches near Lake Baikal to the coastal zone of the Laptev Sea. The permafrost soils from the Lena catchment area store huge amounts of pre-aged OM, which is expected to be remobilized due to climate warming. To characterize the composition and vegetation sources of OM discharged by the Lena River, the lignin phenol and carbon isotopic composition (δ 13 C and Δ 14 C) in total suspended matter (TSM) from surface waters, surface sediments from the Buor Khaya Bay along with soils from the Lena Delta's first (Holocene) and third terraces (Pleistocene ice complex) were analyzed. The lignin compositions of these samples are

  18. Modelling biogeochemical processes in sediments from the north-western Adriatic Sea: response to enhanced particulate organic carbon fluxes

    Science.gov (United States)

    Brigolin, Daniele; Rabouille, Christophe; Bombled, Bruno; Colla, Silvia; Vizzini, Salvatrice; Pastres, Roberto; Pranovi, Fabio

    2018-03-01

    This work presents the result of a study carried out in the north-western Adriatic Sea, by combining two different types of biogeochemical models with field sampling efforts. A longline mussel farm was taken as a local source of perturbation to the natural particulate organic carbon (POC) downward flux. This flux was first quantified by means of a pelagic model of POC deposition coupled to sediment trap data, and its effects on sediment bioirrigation capacity and organic matter (OM) degradation pathways were investigated constraining an early diagenesis model by using original data collected in sediment porewater. The measurements were performed at stations located inside and outside the area affected by mussel farm deposition. Model-predicted POC fluxes showed marked spatial and temporal variability, which was mostly associated with the dynamics of the farming cycle. Sediment trap data at the two sampled stations (inside and outside of the mussel farm) showed average POC background flux of 20.0-24.2 mmol C m-2 d-1. The difference of organic carbon (OC) fluxes between the two stations was in agreement with model results, ranging between 3.3 and 14.2 mmol C m-2 d-1, and was primarily associated with mussel physiological conditions. Although restricted, these changes in POC fluxes induced visible effects on sediment biogeochemistry. Observed oxygen microprofiles presented a 50 % decrease in oxygen penetration depth (from 2.3 to 1.4 mm), accompanied by an increase in the O2 influx at the station below the mussel farm (19-31 versus 10-12 mmol O2 m-2 d-1) characterised by higher POC flux. Dissolved inorganic carbon (DIC) and NH4+ concentrations showed similar behaviour, with a more evident effect of bioirrigation underneath the farm. This was confirmed through constraining the early diagenesis model, of which calibration leads to an estimation of enhanced and shallower bioirrigation underneath the farm: bioirrigation rates of 40 yr-1 and irrigation depth of 15 cm were

  19. Future export of particulate and dissolved organic carbon from land to coastal zones of the Baltic Sea

    Science.gov (United States)

    Strååt, Kim Dahlgren; Mörth, Carl-Magnus; Undeman, Emma

    2018-01-01

    The Baltic Sea is a semi-enclosed brackish sea in Northern Europe with a drainage basin four times larger than the sea itself. Riverine organic carbon (Particulate Organic Carbon, POC and Dissolved Organic Carbon, DOC) dominates carbon input to the Baltic Sea and influences both land-to-sea transport of nutrients and contaminants, and hence the functioning of the coastal ecosystem. The potential impact of future climate change on loads of POC and DOC in the Baltic Sea drainage basin (BSDB) was assessed using a hydrological-biogeochemical model (CSIM). The changes in annual and seasonal concentrations and loads of both POC and DOC by the end of this century were predicted using three climate change scenarios and compared to the current state. In all scenarios, overall increasing DOC loads, but unchanged POC loads, were projected in the north. In the southern part of the BSDB, predicted DOC loads were not significantly changing over time, although POC loads decreased in all scenarios. The magnitude and significance of the trends varied with scenario but the sign (+ or -) of the projected trends for the entire simulation period never conflicted. Results were discussed in detail for the "middle" CO2 emission scenario (business as usual, a1b). On an annual and entire drainage basin scale, the total POC load was projected to decrease by ca 7% under this scenario, mainly due to reduced riverine primary production in the southern parts of the BSDB. The average total DOC load was not predicted to change significantly between years 2010 and 2100 due to counteracting decreasing and increasing trends of DOC loads to the six major sub-basins in the Baltic Sea. However, predicted seasonal total loads of POC and DOC increased significantly by ca 46% and 30% in winter and decreased by 8% and 21% in summer over time, respectively. For POC the change in winter loads was a consequence of increasing soil erosion and a shift in duration of snowfall and onset of the spring flood

  20. Submicron particulate organic matter in the urban atmosphere: a new method for real-time measurement, molecular-level characterization and source apportionment

    Science.gov (United States)

    Müller, Markus; Eichler, Philipp; D'Anna, Barbara; Tan, Wen; Wisthaler, Armin

    2017-04-01

    We used a novel chemical analytical method for measuring submicron particulate organic matter in the atmosphere of three European cities (Innsbruck, Lyon, Valencia). Proton-Transfer-Reaction Time-of-Flight Mass Spectrometry (PTR-ToF-MS) was used in combination with the "chemical analysis of aerosol online" (CHARON) inlet for detecting particulate organic compounds on-line (i.e. without filter pre-collection), in real-time (1-min time resolution), at ng m-3 concentrations, with molecular-level resolution (i.e. obtaining molecular weight and elemental composition information). The CHARON-PTR-ToF-MS system monitored molecular tracers associated with different particle sources including levoglucosan from biomass combustion, PAHs from vehicular traffic, nicotine from cigarette smoking, and monoterpene oxidation products secondarily formed from biogenic emissions. The tracer information was used for interpreting positive matrix factorization (PMF) data which allowed us to apportion the sources of submicron particulate organic matter in the different urban environments. This work was funded through the PIMMS ITN, which was supported by the European Commission's 7th Framework Programme under grant agreement number 287382.

  1. New approach to measure soil particulate organic matter in intact samples using X-ray computed micro-tomography

    Science.gov (United States)

    Kravchenko, Alexandra; Negassa, Wakene; Guber, Andrey; Schmidt, Sonja

    2014-05-01

    Particulate soil organic matter (POM) is biologically and chemically active fraction of soil organic matter. It is a source of many agricultural and ecological benefits, among which are POM's contribution to C sequestration. Most of conventional research methods for studying organic matter dynamics involve measurements conducted on pre-processed i.e., ground and sieved soil samples. Unfortunately, grinding and sieving completely destroys soil structure, the component crucial for soil functioning and C protection. Importance of a better understanding of the role of soil structure and of the physical protection that it provides to soil C cannot be overstated; and analysis of quantities, characteristics, and decomposition rates of POM in soil samples with intact structure is among the key elements of gaining such understanding. However, a marked difficulty hindering the progress in such analyses is a lack of tools for identification and quantitative analysis of POM in intact soil samples. Recent advancement in applications of X-ray computed micro-tomography (μ-CT) to soil science has given an opportunity to conduct such analyses. The objective of the current study is to develop a procedure for identification and quantitative characterization of POM within intact soil samples using X-ray μ-CT images and to test performance of the proposed procedure on a set of multiple intact soil macro-aggregates. We used 16 4-6 mm soil aggregates collected at 0-15 cm depth from a Typic Hapludalf soil at multiple field sites with diverse agricultural management history. The aggregates have been scanned at SIMBIOS Centre, Dundee, Scotland at 10 micron resolution. POM was determined from the aggregate images using the developed procedure. The procedure was based on combining image pre-processing steps with discriminant analysis classification. The first component of the procedure consisted of image pre-processing steps based on the range of gray values (GV) along with shape and size

  2. Influence of urban pollution on the production of organic particulate matter from isoprene epoxydiols in central Amazonia

    Directory of Open Access Journals (Sweden)

    S. S. de Sá

    2017-06-01

    Full Text Available The atmospheric chemistry of isoprene contributes to the production of a substantial mass fraction of the particulate matter (PM over tropical forests. Isoprene epoxydiols (IEPOX produced in the gas phase by the oxidation of isoprene under HO2-dominant conditions are subsequently taken up by particles, thereby leading to production of secondary organic PM. The present study investigates possible perturbations to this pathway by urban pollution. The measurement site in central Amazonia was located 4 to 6 h downwind of Manaus, Brazil. Measurements took place from February through March 2014 of the wet season, as part of the GoAmazon2014/5 experiment. Mass spectra of organic PM collected with an Aerodyne Aerosol Mass Spectrometer were analyzed by positive-matrix factorization. One resolved statistical factor (IEPOX-SOA factor was associated with PM production by the IEPOX pathway. The IEPOX-SOA factor loadings correlated with independently measured mass concentrations of tracers of IEPOX-derived PM, namely C5-alkene triols and 2-methyltetrols (R = 0. 96 and 0.78, respectively. The factor loading, as well as the ratio f of the loading to organic PM mass concentration, decreased under polluted compared to background conditions. For an increase in NOy concentration from 0.5 to 2 ppb, the factor loading and f decreased by two to three fold. Overall, sulfate concentration explained 37 % of the variability in the factor loading. After segregation of factor loading into subsets based on NOy concentration, the sulfate concentration explained up to 75 % of the variability. Considering both factors, the data sets show that the suppressing effects of increased NO concentrations dominated over the enhancing effects of higher sulfate concentrations. The pollution from Manaus elevated NOy concentrations more significantly than sulfate concentrations relative to background conditions. In this light, increased emissions of nitrogen oxides, as

  3. Stable carbon isotope signals in particulate organic and inorganic carbon of coccolithophores - A numerical model study for Emiliania huxleyi.

    Science.gov (United States)

    Holtz, Lena-Maria; Wolf-Gladrow, Dieter; Thoms, Silke

    2017-05-07

    A recent numerical cell model, which explains observed light and carbonate system effects on particulate organic and inorganic carbon (POC and PIC) production rates under the assumption of internal pH homeostasis, is extended for stable carbon isotopes ( 12 C, 13 C). Aim of the present study is to mechanistically understand the stable carbon isotopic fractionation signal (ε) in POC and PIC and furthermore the vital effect(s) included in measured ε PIC values. The virtual cell is divided into four compartments, for each of which the 12 C as well as the 13 C carbonate system kinetics are implemented. The compartments are connected to each other via trans-membrane fluxes. In contrast to existing carbon fractionation models, the presented model calculates the disequilibrium state for both carbonate systems and for each compartment. It furthermore calculates POC and PIC production rates as well as ε POC and ε PIC as a function of given light conditions and the compositions of the external carbonate system. Measured POC and PIC production rates as well as ε PIC values are reproduced well by the model (comparison with literature data). The observed light effect on ε POC (increase of ε POC with increasing light intensities), however, is not reproduced by the basic model set-up, which is solely based on RubisCO fractionation. When extending the latter set-up by assuming that biological fractionation includes further carbon fractionation steps besides the one of RubisCO, the observed light effect on ε POC is also reproduced. By means of the extended model version, four different vital effects that superimpose each other in a real cell can be detected. Finally, we discuss potential limitations of the ε PIC proxy. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Organic and elemental carbon bound to particulate matter in the air of printing office and beauty salon

    Science.gov (United States)

    Rogula-Kopiec, Patrycja; Pastuszka, Józef S.; Rogula-Kozłowska, Wioletta; Mucha, Walter

    2017-11-01

    The aim of this study was to determine the role of internal sources of emissions on the concentrations of total suspended particulate matter (TSP) and its sub-fraction, so-called respirable PM (PM4; fraction of particles with particle size ≤ 4 µm) and to estimate to which extent those emissions participate in the formation of PM-bound elemental (EC) and organic (OC) carbon in two facilities - one beauty salon and one printing office located in Bytom (Upper Silesia, Poland). The average concentration of PM in the printing office and beauty salon during the 10-day measurement period was 10 and 4 (PM4) and 8 and 3 (TSP) times greater than the average concentration of PM fractions recorded in the same period in the atmospheric air; it was on average: 204 µg/m3 (PM4) and 319 µg/m3 (TSP) and 93 µg/m3 (PM4) and 136 µg/m3 (TSP), respectively. OC concentrations determined in the printing office were 38 µg/m3 (PM4) and 56 µg/m3 (TSP), and those referring to EC: 1.8 µg/m3 (PM4) and 3.5 µg/m3 (TSP). In the beauty salon the average concentration of OC for PM4 and TSP were 58 and 75 µg/m3, respectively and in case of EC - 3.1 and 4.7 µg/m3, respectively. The concentrations of OC and EC within the those facilities were approximately 1.7 (TSP-bound EC, beauty salon) to 4.7 (TSP-bound OC, printing office) times higher than the average atmospheric concentrations of those compounds measured in both PM fractions at the same time. In both facilities the main source of TSP-and PM4-bound OC in the indoor air were the chemicals - solvents, varnishes, paints, etc.

  5. Co-optimization of diesel fuel biodegradation and N2 fixation through the addition of particulate organic carbon

    International Nuclear Information System (INIS)

    Piehler, M.; Swistak, J.; Paerl, H.

    1995-01-01

    Petroleum hydrocarbon pollution in the marine environment is widespread and current bioremedial techniques are often not cost effective for small spills. The formulation of simple and inexpensive bioremedial methods could help reduce the impacts of frequent low volume spills in areas like marinas and ports. Particulate organic carbon (POC) was added to diesel fuel amended samples from inshore marine waters in the form of corn-slash (post-harvest leaves and stems), with and without inorganic nutrients (nitrate and phosphate). Biodegradation of diesel fuel ( 14 C hexadecane mineralization) and N 2 fixation were measured in response to the additions, The addition of POC was necessary for N 2 fixation and diesel fuel biodegradation to co-occur. The effects of diesel fuel and inorganic nutrient additions on N 2 fixation rates were not consistent, with both inhibitory and stimulatory responses to each addition observed. The highest observed diesel fuel biodegradation levels were in response to treatments that included inorganic nutrients. The addition of POC alone increased diesel fuel degradation levels above that observed in the control. In an attempt to determine the effect of the POC on the microbial community, the corn particles were observed microscopically using scanning electron microscopy and light microscopy with tetrazolium salt additions. The corn particles were found to have abundant attached bacterial communities and microscale oxygen concentration gradients occurring on individual particles. The formation of oxygen replete microzones may be essential for the co-occurrence of aerobic diesel fuel biodegradation and oxygen inhibited N2 fixation. Mesocosm experiments are currently underway to further examine the structure and function of this primarily heterotrophic system and to explore the potential contribution of N 2 fixation to the N requirements of diesel fuel biodegradation

  6. New method to determine the total carbonyl functional group content in extractable particulate organic matter by tandem mass spectrometry.

    Science.gov (United States)

    Dron, J; Zheng, W; Marchand, N; Wortham, H

    2008-08-01

    A functional group analysis method was developed to determine the quantitative content of carbonyl functional groups in atmospheric particulate organic matter (POM) using constant neutral loss scanning-tandem mass spectrometry (CNLS-MS/MS). The neutral loss method consists in monitoring the loss of a neutral fragment produced by the fragmentation of a precursor ion in a collision cell. The only ions detected are the daughter ions resulting from the loss of the neutral fragment under study. Then, scanning the loss of a neutral fragment characteristic of a functional group enables the selective detection of the compounds bearing the chemical function under study within a complex mixture. The selective detection of carbonyl functional groups was achieved after derivatization with pentafluorophenylhydrazine (PFPH) by monitoring the neutral loss of C(6)F(5)N (181 amu), which was characteristic of a large panel of derivatized carbonyl compounds. The method was tested on 25 reference mixtures of different composition, all containing 24 carbonyl compounds at randomly determined concentrations. The repeatability and calibration tests were satisfying as they resulted in a relative standard deviation below 5% and a linear range between 0.01 and 0.65 mM with a calculated detection limit of 0.0035 mM. Also, the relative deviation induced by changing the composition of the mixture while keeping the total concentration of carbonyl functional groups constant was less than 20%. These reliability experiments demonstrate the high robustness of the developed procedure for accurate carbonyl functional group measurement, which was applied to atmospheric POM samples. Copyright (c) 2008 John Wiley & Sons, Ltd.

  7. Concentrations of volatile organic compounds, carbon monoxide, carbon dioxide and particulate matter in buses on highways in Taiwan

    Science.gov (United States)

    Hsu, Der-Jen; Huang, Hsiao-Lin

    2009-12-01

    Although airborne pollutants in urban buses have been studied in many cities globally, long-distance buses running mainly on highways have not been addressed in this regard. This study investigates the levels of volatile organic compounds (VOCs), carbon monoxide (CO), carbon dioxide (CO 2) and particulate matter (PM) in the long-distance buses in Taiwan. Analytical results indicate that pollutants levels in long-distance buses are generally lower than those in urban buses. This finding is attributable to the driving speed and patterns of long-distance buses, as well as the meteorological and geographical features of the highway surroundings. The levels of benzene, toluene, ethylbenzene and xylene (BTEX) found in bus cabins exceed the proposed indoor VOC guidelines for aromatic compounds, and are likely attributable to the interior trim in the cabins. The overall average CO level is 2.3 ppm, with higher average level on local streets (2.9 ppm) than on highways (2.2 ppm). The average CO 2 level is 1493 ppm, which is higher than the guideline for non-industrial occupied settings. The average PM level in this study is lower than those in urban buses and IAQ guidelines set by Taiwan EPA. However, the average PM 10 and PM 2.5 is higher than the level set by WHO. Besides the probable causes mentioned above, fewer passenger movements and less particle re-suspension from bus floor might also cause the lower PM levels. Measurements of particle size distribution reveal that more than 75% of particles are in submicron and smaller sizes. These particles may come from the infiltration from the outdoor air. This study concludes that air exchange rates in long-distance buses should be increased in order to reduce CO 2 levels. Future research on long-distance buses should focus on the emission of VOCs from brand new buses, and the sources of submicron particles in bus cabins.

  8. Assessment of volatile organic compounds and particulate matter in a dental clinic and health risks to clinic personnel.

    Science.gov (United States)

    Hong, Yu-Jue; Huang, Yen-Ching; Lee, I-Long; Chiang, Che-Ming; Lin, Chitsan; Jeng, Hueiwang Anna

    2015-01-01

    This study was conducted to assess (1) levels of volatile organic compounds (VOCs) and particulate matter (PM) in a dental clinic in southern Taiwan and (2) dental care personnel's health risks associated with due to chronic exposure to VOCs. An automatic, continuous sampling system and a multi-gas monitor were employed to quantify the air pollutants, along with environmental comfort factors, including temperature, CO2, and relative humidity at six sampling sites in the clinic over eight days. Specific VOC compounds were identified and their concentrations were quantified. Both non-carcinogenic and carcinogenic VOC compounds were assessed based on the US Environmental Protection Agency's Principles of Health Risk Assessment in terms of whether those indoor air pollutants increased health risks for the full-time dental care professionals at the clinic. Increased levels of VOCs were recorded during business hours and exceeded limits recommended by the Taiwan Environmental Protection Agency. A total of 68 VOC compounds were identified in the study area. Methylene methacrylate (2.8 ppm) and acetone (0.176 ppm) were the only two non-carcinogenic compounds that posed increased risks for human health, yielding hazard indexes of 16.4 and 4.1, respectively. None of the carcinogenic compounds increased cancer risk. All detected PM10 levels ranged from 20 to 150 μg/m(3), which met the Taiwan EPA and international limits. The average PM10 level during business hours was significantly higher than that during non-business hours (P = 0.04). Improved ventilation capacity in the air conditioning system was recommended to reduce VOCs and PM levels.

  9. Energies and carbon sinks

    International Nuclear Information System (INIS)

    Riedacker, A.

    2002-01-01

    The Kyoto Protocol puts a lot of emphasis on carbon sinks. This emphasis almost obliterates the other potential contributions of biomass in the fight against climatic changes and toward sustainable development. Biomass represents an infinite supply of renewable energy sources which do not increase the levels of carbon in the atmosphere, contribute to energy savings resulting from the use of wood rather than other materials, the sustainable management of soils, the fight against drought, agroforestry from which the production of foods depends, the mitigating of certain extreme climatic occurrences and the protection of dams from increased silting. The industrial revolution contributed to the increase in greenhouse gas emissions. When discussing some of the finer points of the Kyoto Protocol, the focus was placed on carbon sinks. The author indicates that the biomass cycle had to be considered, both in situ and ex situ. Details to this effect are provided, and a section dealing with greenhouse gases other than carbon must be taken into account. The rural environment must be considered globally. The author indicates that in the future, the emissions resulting from the transportation of agricultural products will have to be considered. Within the realm of the policies on sustainable development, the fight against climatic change represents only one aspect. In arid and semi-arid regions, one must take into account meeting the energy needs of the populations, the fight against drought and the preservation of biodiversity. The planting of trees offers multiple advantages apart from being a carbon sink: roughage, wood for burning, protection of soils, etc. A few examples are provided. 8 refs., 3 figs

  10. Sinking a Granular Raft

    Science.gov (United States)

    Protière, Suzie; Josserand, Christophe; Aristoff, Jeffrey M.; Stone, Howard A.; Abkarian, Manouk

    2017-03-01

    We report experiments that yield new insights on the behavior of granular rafts at an oil-water interface. We show that these particle aggregates can float or sink depending on dimensionless parameters taking into account the particle densities and size and the densities of the two fluids. We characterize the raft shape and stability and propose a model to predict its shape and maximum length to remain afloat. Finally we find that wrinkles and folds appear along the raft due to compression by its own weight, which can trigger destabilization. These features are characteristics of an elastic instability, which we discuss, including the limitations of our model.

  11. Quantity and biochemical composition of particulate organic matter in a highly trawled area (Thermaikos Gulf, Eastern Mediterranean Sea

    Directory of Open Access Journals (Sweden)

    Antonio Pusceddu

    2015-11-01

    Full Text Available Bottom trawling represents nowadays one of the most severe anthropogenic disturbances at sea, and determines large impacts on benthic communities and processes. Bottom trawling determines also local sediment resuspension and the effects of the injection of large amounts of surface sediments into the water column have been repeatedly investigated. Few studies have assessed the consequences of sediment resuspension caused by bottom trawling on the quantity, biochemical composition and bioavailability of suspended organic particles and how these eventually rival those exerted by natural storms. To provide insights on this poorly addressed issue, we investigated concentrations and biochemical composition of total and enzymatically digestible pools of particulate organic matter (POM in the Thermaikos Gulf (Mediterranean Sea under calm sea conditions, during intensive trawling activities, and after a severe storm. We show here that sediment resuspension caused by trawling can cause large effects on POM quantity, biochemical composition and bioavailability. Both during trawling and after the storm, the relative importance of the carbohydrate pools increased (in the upper water column and the total lipid concentrations decreased (in the intermediate and bottom layers when compared to values measured during calm conditions. These results would suggest that bottom trawling could inject in the upper water column POM pools more refractory in nature (e.g., carbohydrates than those present in calm or after-storm conditions. By contrast, we show also that the bioavailable fraction of biopolymeric C increased significantly during trawling in the upper water column of the shallowest stations and in the bottom water column layer of the deepest ones. These results provide evidence that bottom trawling can influence the overall trophic status of coastal waters, exerting effects similar or stronger than those caused by natural storms, though of variable amplitude

  12. Influence of declining mean annual rainfall on the behavior and yield of sediment and particulate organic carbon from tropical watersheds

    Science.gov (United States)

    Strauch, Ayron M.; MacKenzie, Richard A.; Giardina, Christian P.; Bruland, Gregory L.

    2018-04-01

    The capacity to forecast climate and land-use driven changes to runoff, soil erosion and sediment transport in the tropics is hindered by a lack of long-term data sets and model study systems. To address these issues we utilized three watersheds characterized by similar shape, geology, soils, vegetation cover, and land use arranged across a 900 mm gradient in mean annual rainfall (MAR). Using this space-for-time design, we quantified suspended sediment (SS) and particulate organic carbon (POC) export over 18 months to examine how large-scale climate trends (MAR) affect sediment supply and delivery patterns (hysteresis) in tropical watersheds. Average daily SS yield ranged from 0.128 to 0.618 t km- 2 while average daily POC ranged from 0.002 to 0.018 t km- 2. For the largest storm events, we found that sediment delivery exhibited similar clockwise hysteresis patterns among the watersheds, with no significant differences in the similarity function between watershed pairs, indicating that: (1) in-stream and near-stream sediment sources drive sediment flux; and (2) the shape and timing of hysteresis is not affected by MAR. With declining MAR, the ratio of runoff to baseflow and inter-storm length between pulse events both increased. Despite increases in daily rainfall and the number of days with large rainfall events increasing with MAR, there was a decline in daily SS yield possibly due to the exhaustion of sediment supply by frequent runoff events in high MAR watersheds. By contrast, mean daily POC yield increased with increasing MAR, possibly as a result of increased soil organic matter decomposition, greater biomass, or increased carbon availability in higher MAR watersheds. We compared results to modeled values using the Load Estimator (LOADEST) FORTRAN model, confirming the negative relationship between MAR and sediment yield. However, because of its dependency on mean daily flow, LOADEST tended to under predict sediment yield, a result of its poor ability to

  13. Discharge modulates stream metabolism dependence on fine particulate organic carbon in a Mediterranean WWTP-influenced stream

    Science.gov (United States)

    Drummond, J. D.; Bernal, S.; Meredith, W.; Schumer, R.; Martí Roca, E.

    2017-12-01

    Waste water treatment plant (WWTP) effluents constitute point source inputs of fine sediment, nutrients, carbon, and microbes to stream ecosystems. A range of responses to these inputs may be observed in recipient streams, including increases in respiration rates, which augment CO2 emissions to the atmosphere. Yet, little is known about which fractions of organic carbon (OC) contribute the most to stream metabolism in WWTP-influenced streams. Fine particulate OC (POC) represents ca. 40% of the total mass of OC in river networks, and is generally more labile than dissolved OC. Therefore, POC inputs from WWTPs could contribute disproportionately to higher rates of heterotrophic metabolism by stream microbial communities. The aim of this study was to investigate the influence of POC inputs from a WWTP effluent on the metabolism of a Mediterranean stream over a wide range of hydrologic conditions. We hypothesized that POC inputs would have a positive effect on respiration rates, and that the response to POC availability would be larger during low flows when the dilution capacity of the recipient stream is negligible. We focused on the easily resuspended fine sediment near the sediment-water interface (top 3 cm), as this region is a known hot spot for biogeochemical processes. For one year, samples of resuspended sediment were collected bimonthly at 7 sites from 0 to 800 m downstream of the WWTP point source. We measured total POC, organic matter (OM) content (%), and the associated metabolic activity of the resuspended sediment using the resazurin-resorufin smart tracer system as a proxy for aerobic ecosystem respiration. Resuspended sediment showed no difference in total POC over the year, while the OM content increased with decreasing discharge. This result together with the decreasing trend of total POC observed downstream of the point source during autumn after a long dry period, suggests that the WWTP effluent was the main contributor to stream POC. Furthermore

  14. Fine scale distributions of porosity and particulate excess 210Pb, organic carbon and CaCO3 in surface sediments of the deep equatorial Pacific

    International Nuclear Information System (INIS)

    Jahnke, R.A.; Emerson, S.R.; Cochran, J.K.; Hirschberg, D.J.

    1986-01-01

    Sediment samples were recovered from the central equatorial Pacific Ocean, sectioned at 1-mm intervals, and analyzed for porosity, organic carbon, excess 210 Pb and CaCO 3 . Steep porosity gradients were measured in the upper 1 cm of the sediment column with extremely high values observed near the sediment surface. Similarly, particulate organic carbon contents are highest at the sediment surface, decrease sharply in the upper 1 cm, and are relatively constant between 1 and 5 cm. CaCO 3 values, on the other hand, are lowest at the sediment surface and increase to a constant value below 5-10 mm depth. At the carbonate ooze sites, excess 210 Pb is present throughout the upper 5 cm of the sediments suggesting relatively rapid particle mixing rates. However, extremely high excess 210 Pb activities (> 100 dpm/g) are observed at the sediment surface with sharp gradients present in the upper 1 cm which would suggest slow rates of mixing. This apparent contradiction along with the major features of the CaCO 3 and particulate organic carbon profiles can be explained by a particle-selective feeding mechanism in which organic carbon, excess 210 Pb-enriched particles are preferentially maintained at the sediment surface via ingestion and defecation by benthic organisms. (orig.)

  15. Modelling biogeochemical processes in sediments from the north-western Adriatic Sea: response to enhanced particulate organic carbon fluxes

    Directory of Open Access Journals (Sweden)

    D. Brigolin

    2018-03-01

    Full Text Available This work presents the result of a study carried out in the north-western Adriatic Sea, by combining two different types of biogeochemical models with field sampling efforts. A longline mussel farm was taken as a local source of perturbation to the natural particulate organic carbon (POC downward flux. This flux was first quantified by means of a pelagic model of POC deposition coupled to sediment trap data, and its effects on sediment bioirrigation capacity and organic matter (OM degradation pathways were investigated constraining an early diagenesis model by using original data collected in sediment porewater. The measurements were performed at stations located inside and outside the area affected by mussel farm deposition. Model-predicted POC fluxes showed marked spatial and temporal variability, which was mostly associated with the dynamics of the farming cycle. Sediment trap data at the two sampled stations (inside and outside of the mussel farm showed average POC background flux of 20.0–24.2 mmol C m−2 d−1. The difference of organic carbon (OC fluxes between the two stations was in agreement with model results, ranging between 3.3 and 14.2 mmol C m−2 d−1, and was primarily associated with mussel physiological conditions. Although restricted, these changes in POC fluxes induced visible effects on sediment biogeochemistry. Observed oxygen microprofiles presented a 50 % decrease in oxygen penetration depth (from 2.3 to 1.4 mm, accompanied by an increase in the O2 influx at the station below the mussel farm (19–31 versus 10–12 mmol O2 m−2 d−1 characterised by higher POC flux. Dissolved inorganic carbon (DIC and NH4+ concentrations showed similar behaviour, with a more evident effect of bioirrigation underneath the farm. This was confirmed through constraining the early diagenesis model, of which calibration leads to an estimation of enhanced and shallower bioirrigation underneath the farm

  16. Seasonal variation in particulate organic matter and its cnstituent fractions under the ice covered sea near the shelf, Antarctica

    Digital Repository Service at National Institute of Oceanography (India)

    Dhargalkar, V.K.

    discrete depths. Chl @ia@@ concentration at all the 3 depths varied from 0.026 to 0.253 mu g l@u-1@@ showing minimum values during August-September. POC values varied from 280 to 1058 mu g l@u-1@@ while its constituent fractions such as particulate...

  17. Toxicologically important trace elements and organic compounds investigated in size-fractionated urban particulate matter collected near the Prague highway

    Czech Academy of Sciences Publication Activity Database

    Sysalová, J.; Sýkorová, Ivana; Havelcová, Martina; Száková, J.; Trejtnarová, Hana; Kotlík, B.

    2012-01-01

    Roč. 437, October (2012), s. 127-136 ISSN 0048-9697 R&D Projects: GA ČR GA205/09/1162 Institutional support: RVO:67985891 Keywords : urban particulate matter * grain- size partitioning * grain- size partitioning Subject RIV: DI - Air Pollution ; Quality Impact factor: 3.258, year: 2012

  18. Volatile organic compounds and particulate matter in child care facilities in the District of Columbia: Results from a pilot study.

    Science.gov (United States)

    Quirós-Alcalá, L; Wilson, S; Witherspoon, N; Murray, R; Perodin, J; Trousdale, K; Raspanti, G; Sapkota, A

    2016-04-01

    Many young children in the U.S. spend a significant portion of their day in child care facilities where they may be exposed to contaminants linked to adverse health effects. Exposure data on volatile organic compounds (VOCs) and particulate matter (PM) in these settings is scarce. To guide the design of a larger exposure assessment study in urban child care facilities, we conducted a pilot study in which we characterized indoor concentrations of select VOCs and PM. We recruited 14 child care facilities in the District of Columbia (Washington, DC) and measured indoor concentrations of seven VOCs (n=35 total samples; 2-5 samples per facility): benzene, carbon tetrachloride, chloroform, ethylbenzene, o-xylene, p-xylene, and toluene in all facilities; and collected real-time PM measurements in seven facilities. We calculated descriptive statistics for contaminant concentrations and computed intraclass correlation coefficients (ICC) to evaluate the variability of VOC levels indoors. We also administered a survey to collect general health information on the children attending these facilities, and information on general housekeeping practices and proximity of facilities to potential sources of target contaminants. We detected six of the seven VOCs in the majority of child care facilities with detection frequencies ranging from 71% to 100%. Chloroform and toluene were detected in all samples. Median (range) concentrations for toluene, chloroform, benzene, o-xylene, ethylbenzene, and carbon tetrachloride were: 5.6µg/m(3) (0.6-16.5µg/m(3)), 2.8µg/m(3) (0.4-53.0µg/m(3)), 1.4µg/m(3) (below the limit of detection or air fresheners and/or scented candles were used in half of the facilities, and at least one child in each facility had physician-diagnosed asthma (median asthma prevalence rate=10.2%). We found quantifiable levels of VOCs and PM in the child care facilities sampled. Given that exposures to environmental contaminants during critical developmental stages may

  19. Badlands as a major source of petrogenic particulate Organic Carbon and sediments to the Gulf of Lion (NW Mediterranean Sea)

    Science.gov (United States)

    Copard, Y.; Eyrolle-Boyer, F.; Radakovitch, O.; Poirel, A.; Raimbault, P.; Gairoard, S.; Di-Giovanni, C.

    2017-12-01

    Rivers feed the marine environments both in term of sediments and nutrients and consequently, the characterization of their nature, sources and changes over a different spatial and time ranges is a critical for many scientific (e.g. biogeochemical cycles, contaminants transfer, geomorphology, ecology) and societal issues (e.g. food security, catastrophic floods). Specifically, continental sources showing some high erosion rates deserve to be studied since their fingerprint can be significant for the rivers fluxes. These included some sedimentary rocks (e.g. marls) forming badlands and containing a significant amount of petrogenic particulate organic carbon (pPOC) for which its contribution to the Rivers still remains evasive. Our study focuses on the Mediterranean area considered as very sensitive to the Global Change and particularly the Gulf of Lion mainly fed by the Rhône River, one of the major conveyors of sediments to this Sea. Based on radiocarbon data performed on a set of riverine samples and time series analyses from monitoring stations from French CZOs, we (i) update the POC flux of the Rhône River, (ii) determine the pPOC content and flux in suspended sediments and (iii) estimate the badlands contribution from the Durance catchment (a major tributary of the Rhône River) to the pPOC flux and to sediment discharge. Sediment discharge by the Rhône River to the Sea is 6.5 ± 4.3 Tg yr-1 (period 1990-2014) , its POC discharge reaches 0.145 ± 0.095 Tg yr-1 (period 2007-2014) while pPOC (0.44 wt. %) contributes to 30 % of this POC flux. Despite their insignificant surfaces (0.2 %) regarding the Rhône catchment area, badlands presently in erosion from the Durance catchment provide respectively, 16, 5 and 20 % of the pPOC, POC and sediment fluxes to the Rhône River. Consequently, badlands can be considered as a major source of sediments and pPOC for the NW Mediterranean Sea. We suggest that river-dominated ocean margins, such as the Rhône River, with

  20. Hyphenation of a carbon analyzer to photo-ionization mass spectrometry to unravel the organic composition of particulate matter on a molecular level.

    Science.gov (United States)

    Grabowsky, Jana; Streibel, Thorsten; Sklorz, Martin; Chow, Judith C; Watson, John G; Mamakos, Athanasios; Zimmermann, Ralf

    2011-12-01

    The carbonaceous fraction of airborne particulate matter (PM) is of increasing interest due to the adverse health effects they are linked to. Its analytical ascertainment on a molecular level is still challenging. Hence, analysis of carbonaceous fractions is often carried out by determining bulk parameters such as the overall content of organic compounds (OC) and elemental carbon (EC) as well as the total carbon content, TC (sum of OC and EC), however, no information about the individual substances or substance classes, of which the single fractions consist can be obtained. In this work, a carbon analyzer and a photo-ionization time-of-flight mass spectrometer (PI-TOF-MS) were hyphenated to investigate individual compounds especially from the OC fractions. The carbon analyzer enables the stepwise heating of particle samples and provides the bulk parameters. With the PI-TOF-MS, it is possible to detect the organic compounds released during the single-temperature steps due to soft ionization and fast detection of the molecular ions. The hyphenation was designed, built up, characterized by standard substances, and applied to several kinds of samples, such as ambient aerosol, gasoline, and diesel emission as well as wood combustion emission samples. The ambient filter sample showed a strong impact of wood combustion markers. This was revealed by comparison to the product pattern of the similar analysis of pure cellulose and lignin and the wood combustion PM. At higher temperatures (450 °C), a shift to smaller molecules occurred due to the thermal decomposition of larger structures of oligomeric or polymeric nature comparable to lignocelluloses and similar oxygenated humic-like substances. Finally, particulate matter from gasoline and diesel containing 10% biodiesel vehicle exhaust has been analyzed. Gasoline-derived PM exhibited large polycyclic aromatic hydrocarbons, whereas diesel PM showed a much higher total organic content. The detected pattern revealed a strong

  1. Effect of CO2 on the properties and sinking velocity of aggregates of the coccolithophore Emiliania huxleyi

    Directory of Open Access Journals (Sweden)

    A. Engel

    2010-03-01

    Full Text Available Coccolithophores play an important role in organic matter export due to their production of the mineral calcite that can act as ballast. Recent studies indicated that calcification in coccolithophores may be affected by changes in seawater carbonate chemistry. We investigated the influence of CO2 on the aggregation and sinking behaviour of the coccolithophore Emiliania huxleyi (PML B92/11 during a laboratory experiment. The coccolithophores were grown under low (~180 μatm, medium (~380 μatm, and high (~750 μatm CO2 conditions. Aggregation of the cells was promoted using roller tables. Size and settling velocity of aggregates were determined during the incubation using video image analysis. Our results indicate that aggregate properties are sensitive to changes in the degree of ballasting, as evoked by ocean acidification. Average sinking velocity was highest for low CO2 aggregates (~1292 m d−1 that also had the highest particulate inorganic to particulate organic carbon (PIC/POC ratio. Lowest PIC/POC ratios and lowest sinking velocity (~366 m d−1 at comparable sizes were observed for aggregates of the high CO2 treatment. Aggregates of the high CO2 treatment showed a 4-fold lower excess density (~4.2×10−4 g cm−3 when compared to aggregates from the medium and low CO2 treatments (~1.7 g×10−3 cm−3. We also observed that more aggregates formed in the high CO2 treatment, and that those aggregates contained more bacteria than aggregates in the medium and low CO2 treatment. If applicable to the future ocean, our findings suggest that a CO2 induced reduction of the calcite content of aggregates could weaken the deep export of organic matter in the ocean, particularly in areas dominated by coccolithophores.

  2. Analysis of Phytosterols and N-Alkanols in Atmospheric Organic Particulate Matter Collected in Vancouver During the Pacific 2001 Air Quality Study

    Science.gov (United States)

    Leithead, A.; Li, S.

    2002-12-01

    As part of Pacific 2001, HiVol samples were collected from 5 sites in the Vancouver area. The samples were extracted by accelerated solvent extraction (ACE), concentrated with nitrogen blow down, and separated into fractions by silica gel chromatography. For this portion of the study, an aliquot of one of the polar fraction was derivatized with BSTFA and analyzed by GC-FID and GC-MS. The results for n-alkanols and phytosterols will be reported and discussed. Previous studies have shown that the biogenic components of particulate matter are major constituents of the total organic material in atmospheric samples. Phytosterols are present in wood smoke, epicuticular waxes of many plants and microbial sources. In addition, cholesterol has been proposed as a potential tracer for emissions from cooking. The most abundant phytosterols are cholesterol, campesterol, stigmasterol and beta-sitosterol. It has been hypothesized that the phytosterol signature may be useful in identifying particulate matter from different source areas. The phytosterol signature for these samples will be reported and compared. The n-alkanol CPI and Cmax will also be reported. N-alkanols in atmospheric samples generally show a strong even to odd predominance indicating that their main source in particulate matter is biogenic. The n-alkanol signature for each sampling site will be compared.

  3. Sinking fluxes of minor and trace elements in the North Pacific Ocean measured during the VERTIGO program

    Science.gov (United States)

    Lamborg, C. H.; Buesseler, K. O.; Lam, P. J.

    2008-07-01

    As part of the Vertical Transport in the Global Ocean (VERTIGO) program, we collected and analyzed sinking particles using sediment traps at three depths in the oceanic mesopelagic zone and at two biogeochemically contrasting sites (N. Central Pacific at ALOHA; N. Pacific Western Subarctic Gyre at K2). In this paper, we present the results of minor and trace element determinations made on these samples. Minor and trace elements in the sinking material showed 2 trends in flux with depth: increasing and constant. The sinking particulate phase of some elements (Al, Fe, Mn) was dominated by material of lithogenic origin and exhibited flux that was constant with depth and consistent with eolian dust inputs (ALOHA), or increasing in flux with depth as a result of lateral inputs from a shelf (K2). This shelf-derived material also appears to have been confined to very small particles, whose inherent sinking rates are slow, and residence time within the mesopelagic "twilight zone" would be consequently long. Furthermore, the flux of this material did not change with substantial changes in the rain of biogenic material from the surface (K2), suggesting mechanistic decoupling from the flux of organic carbon and macronutrients. Micronutrient (Fe, Co, Zn and Cu) fluxes examined in a 1-D mass balance suggest widely differing sources and sinks in the water column as well as impacts from biological uptake and regeneration. For example, total Fe fluxes into and out of the euphotic zone appeared to be dominated by lithogenic material and far exceed biological requirements. The export flux of Fe, however, appeared to be balanced by the eolian input of soluble Fe. For Zn and Cu, the situation is reversed, with atmospheric inputs insufficient to support fluxes, and the cycling therefore dominated by the draw down of an internal pool. For Co, the situation lies in between, with important, but ultimately insufficient atmospheric inputs.

  4. Nature and sources of suspended particulate organic matter in a tropical estuary during the monsoon and pre-monsoon: Insights from stable isotopes (delta 13C POC, delta 15 N TPN) and carbohydrate signature compounds

    Digital Repository Service at National Institute of Oceanography (India)

    Khodse, V.B.; Bhosle, N.B.

    zooplankton, and then known aliquots (0.25 to 1.5 L) were filtered through pre-combusted (450 °C, 4h) 47 mm GF/F filter papers (0.7 µm, Whatman) for the measurements of suspended particulate matter (SPM), particulate organic carbon (POC), δ13CPOC, δ15NTPN... analysis. 2.3. Determination of bulk parameters and stable isotopes GF/F (0.7 µm, 47 mm) filter containing particulate matter was washed with UV-Milli-Q- water to remove salt and the filter was dried at 40 °C for 24 h. Filter was cooled and weighed...

  5. Satellite-Derived Distributions, Inventories and Fluxes of Dissolved and Particulate Organic Matter Along the Northeastern U.S. Continental Margin

    Science.gov (United States)

    Mannino, A.; Hooker, S. B.; Hyde, K.; Novak, M. G.; Pan, X.; Friedrichs, M.; Cahill, B.; Wilkin, J.

    2011-01-01

    Estuaries and the coastal ocean experience a high degree of variability in the composition and concentration of particulate and dissolved organic matter (DOM) as a consequence of riverine and estuarine fluxes of terrigenous DOM, sediments, detritus and nutrients into coastal waters and associated phytoplankton blooms. Our approach integrates biogeochemical measurements, optical properties and remote sensing to examine the distributions and inventories of organic carbon in the U.S. Middle Atlantic Bight and Gulf of Maine. Algorithms developed to retrieve colored DOM (CDOM), Dissolved (DOC) and Particulate Organic Carbon (POC) from NASA's MODIS-Aqua and SeaWiFS satellite sensors are applied to quantify the distributions and inventories of DOC and POC. Horizontal fluxes of DOC and POC from the continental margin to the open ocean are estimated from SeaWiFS and MODIS-Aqua distributions of DOC and POC and horizontal divergence fluxes obtained from the Northeastern North Atlantic ROMS model. SeaWiFS and MODIS imagery reveal the importance of estuarine outflow to the export of CDOM and DOC to the coastal ocean and a net community production of DOC on the shelf.

  6. Direct sampling of sub-µm atmospheric particulate organic matter in sub-ng m-3 mass concentrations by proton-transfer-reaction mass spectrometry

    Science.gov (United States)

    Armin, W.; Mueller, M.; Klinger, A.; Striednig, M.

    2017-12-01

    A quantitative characterization of the organic fraction of atmospheric particulate matter is still challenging. Herein we present the novel modular "Chemical Analysis of Aerosol Online" (CHARON) particle inlet system coupled to a new-generation proton-transfer-reaction time-of-flight mass spectrometer (PTR-TOF 6000 X2, Ionicon Analytik, Austria) that quantitatively detects organic analytes in real-time and sub-pptV levels by chemical ionization with hydronium reagent ions. CHARON consists of a gas-phase denuder for stripping off gas-phase analytes (efficiency > 99.999%), an aerodynamic lens for particle collimation combined with an inertial sampler for the particle-enriched flow and a thermodesorption unit for particle volatilization prior to chemical analysis. With typical particle enrichment factors of around 30 for particle diameters (DP) between 120 nm and 1000 nm (somewhat reduced enrichment for 60 nm 6000) and excellent mass accuracies (< 10 ppm) chemical compositions can be assigned and included in further analyses. In addition to a detailed characterization of the CHARON PTR-TOF 6000 X2 we will present first results on the chemical composition of sub-µm particulate organic matter in the urban atmosphere in Innsbruck (Austria).

  7. Metabarcoding-based fungal diversity on coarse and fine particulate organic matter in a first-order stream in Nova Scotia, Canada [version 2; referees: 2 approved

    Directory of Open Access Journals (Sweden)

    Christian Wurzbacher

    2016-02-01

    Full Text Available Most streams receive substantial inputs of allochthonous organic material in the form of leaves and twigs (CPOM, coarse particulate organic matter. Mechanical and biological processing converts this into fine particulate organic matter (FPOM. Other sources of particles include flocculated dissolved matter and soil particles. Fungi are known to play a role in the CPOM conversion process, but the taxonomic affiliations of these fungi remain poorly studied. The present study seeks to shed light on the composition of fungal communities on FPOM and CPOM as assessed in a natural stream in Nova Scotia, Canada. Maple leaves were exposed in a stream for four weeks and their fungal community evaluated through pyrosequencing. Over the same period, four FPOM size fractions were collected by filtration and assessed. Particles had much lower ergosterol contents than leaves, suggesting major differences in the extent of fungal colonization. Pyrosequencing documented a total of 821 fungal operational taxonomic units (OTU, of which 726 were exclusive to particles and 47 to leaf samples. Most fungal phyla were represented, including yeast lineages (e.g., Taphrinaceae and Saccharomycotina, Basidiomycota, Chytridiomycota and Cryptomycota, but several classes of Pezizomycontina (Ascomycota dominated. Cluster dendrograms clearly separated fungal communities from leaves and from particles. Characterizing fungal communities may shed some light on the processing pathways of fine particles in streams and broadens our view of the phylogenetic composition of fungi in freshwater ecosystems.

  8. Sinking towards destiny: High throughput measurement of phytoplankton sinking rates through time-resolved fluorescence plate spectroscopy.

    Science.gov (United States)

    Bannon, Catherine C; Campbell, Douglas A

    2017-01-01

    Diatoms are marine primary producers that sink in part due to the density of their silica frustules. Sinking of these phytoplankters is crucial for both the biological pump that sequesters carbon to the deep ocean and for the life strategy of the organism. Sinking rates have been previously measured through settling columns, or with fluorimeters or video microscopy arranged perpendicularly to the direction of sinking. These side-view techniques require large volumes of culture, specialized equipment and are difficult to scale up to multiple simultaneous measures for screening. We established a method for parallel, large scale analysis of multiple phytoplankton sinking rates through top-view monitoring of chlorophyll a fluorescence in microtitre well plates. We verified the method through experimental analysis of known factors that influence sinking rates, including exponential versus stationary growth phase in species of different cell sizes; Thalassiosira pseudonana CCMP1335, chain-forming Skeletonema marinoi RO5A and Coscinodiscus radiatus CCMP312. We fit decay curves to an algebraic transform of the decrease in fluorescence signal as cells sank away from the fluorometer detector, and then used minimal mechanistic assumptions to extract a sinking rate (m d-1) using an RStudio script, SinkWORX. We thereby detected significant differences in sinking rates as larger diatom cells sank faster than smaller cells, and cultures in stationary phase sank faster than those in exponential phase. Our sinking rate estimates accord well with literature values from previously established methods. This well plate-based method can operate as a high throughput integrative phenotypic screen for factors that influence sinking rates including macromolecular allocations, nutrient availability or uptake rates, chain-length or cell size, degree of silification and progression through growth stages. Alternately the approach can be used to phenomically screen libraries of mutants.

  9. Characterization of particulate amines

    International Nuclear Information System (INIS)

    Gundel, L.A.; Chang, S.G.; Clemenson, M.S.; Markowitz, S.S.; Novakov, T.

    1979-01-01

    The reduced nitrogen compounds associated with ambient particulate matter are chemically characterized by means of ESCA and proton activation analysis. Ambient particulate samples collected on silver filters in Berkeley, California were washed with water and organic solvents, and ESCA and proton activation analysis were performed in order to determine the composition of various nitrogen compounds and the total nitrogen content. It is found that 85% of the amines originally present in ambient particulate matter can be removed by water extraction, whereas the ammonium and nitrate are completely removed. An observed increase in ammonium ion in the extract, compared with its concentration in the original sample, coupled with the commensurate decrease in amine concentration, is attributed to the hydrolysis of amide groups, which may cause analytical methods based on extraction to yield erroneous results

  10. Radiotracers in the study of marine food chains. The use of compartmental analysis and analog modelling in measuring utilization rates of particulate organic matter by benthic invertebrates

    International Nuclear Information System (INIS)

    Gremare, A.; Amouroux, J.M.; Charles, F.

    1991-01-01

    The present study assesses the problem of recycling when using radiotracers to quantify ingestion and assimilation rates of particulate organic matter by benthic invertebrates. The rapid production of dissolved organic matter and its subsequent utilization by benthic invertebrates constitutes a major bias in this kind of study. However recycling processes may also concern POM through the production and reingestion of faeces. The present paper shows that compartmental analysis of the diffusion kinetics of the radiotracer between the different compartments of the system studied and the analog modelling of the exchanges of radioactivity between compartments may be used in order to determine ingestion and assimilation rates. This method is illustrated by the study of a system composed of the bacteria Lactobacillus sp. and the filter-feeding bivalve Venerupis decussata. The advantages and drawbacks of this approach relative to other existing methods are briefly discussed. (Author)

  11. Ice formation via deposition nucleation on mineral dust and organics: dependence of onset relative humidity on total particulate surface area

    International Nuclear Information System (INIS)

    Kanji, Zamin A; Florea, Octavian; Abbatt, Jonathan P D

    2008-01-01

    We present ice nucleation results for Arizona test dust, kaolinite, montmorillonite, silica, silica coated with a hydrophobic octyl chain, oxalic acid dihydrate, Gascoyne leonardite (a humic material), and Aldrich humic acid (sodium salt). The focus was on deposition mode nucleation below water saturation at 233 K. Particles were deposited onto a hydrophobic cold stage by atomization of a slurry/solution and exposed to a constant partial pressure of water vapor. By lowering the temperature of the stage, the relative humidity with respect to ice (RH i ) was gradually increased until ice nucleation was observed using digital photography. Different numbers of particles were deposited onto the cold stage by varying the atomization solution concentration and deposition time. For the same total particulate surface area, mineral dust particles nucleated ice at lower supersaturations than all other materials. The most hydrophobic materials, i.e. Gascoyne leonardite and octyl silica, were the least active. For our limit of detection of one ice crystal, the ice onset RH i values were dependent on the total surface area of the particulates, indicating that no unique threshold RH i for ice nucleation prevails

  12. Ice formation via deposition nucleation on mineral dust and organics: dependence of onset relative humidity on total particulate surface area

    Energy Technology Data Exchange (ETDEWEB)

    Kanji, Zamin A; Florea, Octavian; Abbatt, Jonathan P D [Department of Chemistry, University of Toronto, 80 St George Street, Toronto, ON, M5S 3H6 (Canada)], E-mail: zkanji@chem.utoronto.ca

    2008-04-15

    We present ice nucleation results for Arizona test dust, kaolinite, montmorillonite, silica, silica coated with a hydrophobic octyl chain, oxalic acid dihydrate, Gascoyne leonardite (a humic material), and Aldrich humic acid (sodium salt). The focus was on deposition mode nucleation below water saturation at 233 K. Particles were deposited onto a hydrophobic cold stage by atomization of a slurry/solution and exposed to a constant partial pressure of water vapor. By lowering the temperature of the stage, the relative humidity with respect to ice (RH{sub i}) was gradually increased until ice nucleation was observed using digital photography. Different numbers of particles were deposited onto the cold stage by varying the atomization solution concentration and deposition time. For the same total particulate surface area, mineral dust particles nucleated ice at lower supersaturations than all other materials. The most hydrophobic materials, i.e. Gascoyne leonardite and octyl silica, were the least active. For our limit of detection of one ice crystal, the ice onset RH{sub i} values were dependent on the total surface area of the particulates, indicating that no unique threshold RH{sub i} for ice nucleation prevails.

  13. Effects of Particulate Organic Matter Complexation and Photo-Irradiation on the Fate and Toxicity of Mercury(II) in Aqueous Systems

    Science.gov (United States)

    Gelfond, C. E.; Kocar, B. D.; Carrasquillo, A. J.

    2015-12-01

    This project investigates how interactions between mercury (Hg) and particulate organic matter (POM) affect the fate, transport, and toxicity of Hg in the environment. Previous studies have evaluated the coordination of dissolved organic matter (DOM) with Hg, but the coordination of POM with Hg has not been thoroughly addressed. Owing to a high density of reactive functional groups, POM will sorb appreciable quantities of Hg, resulting in a large pool of Hg susceptible to organic matter dependent transformations. Particulate organic carbon is also susceptible photolysis, hence chemical changes induced by irradiation by natural sunlight is also important. Further, photo-reduction of Hg(II) to elemental mercury in the presence of DOM has been observed, yet studies examining this process with Hg(II) complexed to POM are less exhaustive. Here, we illustrate that POM derived from fresh plant detritus is a powerful sorbent of Hg(II), and sorbent properties are altered during POM photolysis. Further, we examine redox transformations of Hg(II), and examine functional groups that contribute to mercury association with POM. Batch sorption isotherms of Hg to dark and irradiated POM from ground Phragmites australis ("common reed") were performed and data was collected using ICP-MS. Coordination of Hg to POM was lower in the irradiated samples, resulting from the decrease in Hg-associated (reduced) sulfur bearing functional groups as measured using X-ray adsorption near-edge spectroscopy (XANES) and extended x-ray adsorption fine structure (EXAFS). Further analysis of the dark and irradiated POM was performed using FT-IR microscopy and STXM to determine changes in distribution and alteration of functional groups responsible for Hg sorption to POM.

  14. The role of plantation sinks

    International Nuclear Information System (INIS)

    Read, Peter

    2001-01-01

    In this paper it is argued that in the long term biofuel should play a significant role in global climate policy. Recent technological developments, as well as sustainable development criteria, would favour growing biofuel in community- scale plantations in developing countries. It is also pointed out that the lead times involved in growing biofuels are so great that the inclusion of biofuel plantation sinks in the CDM for the first commitment period would be desirable. It is suggested that to meet opposition to the inclusion of plantation sinks in the first commitment period plantation, sinks should be linked to biofuels technology development and production, and a biofuels obligation for plantation sink projects in the CDM should be established. (Author)

  15. Spatial distribution of organic contaminants in three rivers of Southern England bound to suspended particulate material and dissolved in water.

    Science.gov (United States)

    Wilkinson, John L; Hooda, Peter S; Swinden, Julian; Barker, James; Barton, Stephen

    2017-09-01

    The spatial distribution of pharmaceuticals, personal care products (PPCPs) and other emerging contaminants (ECs) such as plasticisers, perflourinated compounds (PFCs) and illicit drug metabolites in water and bound to suspended particulate material (SPM) is not well-understood. Here, we quantify levels of thirteen selected contaminants in water (n=88) and their partition to suspended particulate material (SPM, n=16) in three previously-unstudied rivers of Greater London and Southern England during a key reproduction/spawning period. Analysis was conducted using an in-house validated method for Solid Phase Extraction followed by High-Performance Liquid Chromatography-Tandem Mass-Spectrometry. Analytes were extracted from SPM using an optimised method for ultrasonic-assisted solvent extraction. Detection frequencies of contaminants dissolved in water ranged from 3% (ethinylestradiol) to 100% (bisphenol-A). Overall mean concentrations in the aqueous-phase ranged from 14.7ng/L (benzoylecgonine) to 159ng/L (bisphenol-A). Sewage treatment works (STW) effluent was the predominant source of pharmaceuticals, while plasticisers/perfluorinated compounds may additionally enter rivers via other sources. In SPM, detection frequencies ranged from 44% (PFOA) to 94% (hydroxyacetophenone). Mean quantifiable levels of analytes bound to SPM ranged from 13.5ng/g dry SPM (0.33ng bound/L water) perfluorononanoic acid to 2830ng/g dry SPM (14.3ng bound/L water) perfluorooctanesulfonic acid. Long chain (>C7) amphipathic and acidic PFCs were found to more preferentially bind to SPM than short chain PFCs and other contaminants (Kd=34.1-75.5 vs contaminants entering rivers ranged from 0.157μg/person/day of benzoylecgonine (cocaine metabolite) to 58.6μg/person/day of bisphenol-A. The large sample size of this work (n=104) enabled ANOVA followed by Tukey HSD post-hoc tests to establish significant trends in PPCP/EC spatial distribution from headwaters through downstream stretches of studied

  16. Mutagenic and recombinagenic activity of airborne particulates, PM10 and TSP, organic extracts in the Drosophila wing-spot test

    International Nuclear Information System (INIS)

    Rodrigues Dihl, Rafael; Grazielli Azevedo da Silva, Carla; Souza do Amaral, Viviane; Reguly, Maria Luiza; Rodrigues de Andrade, Heloisa Helena

    2008-01-01

    The genotoxicity associated with air pollution in the city of Canoas, Rio Grande do Sul (Brazil), was assessed in November (spring) and January (summer). We applied the somatic mutation and recombination test (SMART) in Drosophila melanogaster in its standard version with normal bioactivation (ST) and in its variant with increased cytochrome P450-dependent biotransformation capacity (HB). The data indicated the genotoxicity of TSP and PM10 collected in November, in both ST and HB crosses. The genotoxic activity of the PM10 material in the spring sample was exclusively associated with the induction of mitotic recombination, whereas the TSP genetic toxicity was due to both recombinational as well as point and/or chromosomal mutation events. Considering PM10 collected in January, a positive response-100% (17.10 m 3 /ml) concentration-was observed in the HB cross, which was not detected in the ST cross. - Drosophila Wing-Spot Test can be used for detection of airborne particulates mutagenesis

  17. Solid-state 13C NMR experiments reveal effects of aggregate size on the chemical composition of particulate organic matter in grazed steppe soils

    Science.gov (United States)

    Steffens, M.; Kölbl, A.; Kögel-Knabner, I.

    2009-04-01

    Grazing is one of the most important factors that may reduce soil organic matter (SOM) stocks and subsequently deteriorate aggregate stability in grassland topsoils. Land use management and grazing reduction are assumed to increase the input of OM, improve the soil aggregation and change species composition of vegetation (changes depth of OM input). Many studies have evaluated the impact of grazing cessation on SOM quantity. But until today little is known about the impact of grazing cessation on the chemical quality of SOM in density fractions, aggregate size classes and different horizons. The central aim of this study was to analyse the quality of SOM fractions in differently sized aggregates and horizons as affected by increased inputs of organic matter due to grazing exclusion. We applied a combined aggregate size, density and particle size fractionation procedure to sandy steppe topsoils with different organic matter inputs due to different grazing intensities (continuously grazed = Cg, winter grazing = Wg, ungrazed since 1999 = Ug99, ungrazed since 1979 = Ug79). Three different particulate organic matter (POM; free POM, in aggregate occluded POM and small in aggregate occluded POM) and seven mineral-associated organic matter fractions were separated for each of three aggregate size classes (coarse = 2000-6300 m, medium = 630-2000 m and fine =

  18. Sources, Sinks and Chemistry of Volatile Organic Compounds: A Summary of Results from Multiple Airborne, Ship-Based and Surface Measurements

    Science.gov (United States)

    de Gouw, J. A.; Gilman, J. B.; Goldan, P. D.; Kuster, W. C.; Roberts, J. M.; Veres, P. R.; Warneke, C.; Welsh-Bon, D.

    2009-12-01

    Volatile Organic compounds (VOCs) are emitted from a wide variety of natural and man-made sources. In the atmosphere, VOCs are oxidized on a time scale ranging from minutes to months by reactions with OH, NO3 and ozone, and by photolysis. While the removal of hydrocarbons is well described by these removal processes, the chemical formation and direct emissions of oxygenated VOCs are poorly characterized and understood. VOC oxidation in the atmosphere contributes to the formation of ozone and secondary organic aerosol (SOA). Both species are important ingredients of polluted air and represent a significant radiative forcing to the climate system. We have measured VOCs during several different field studies using both mass spectrometric and gas chromatographic methods. Airborne measurements from the NOAA WP-3D aircraft were carried out along the U.S. West Coast in 2002, in the northeastern U.S. in 2004, in Texas in 2006 and in Alaska in 2008. Ship-based measurements were conducted in the Gulf of Maine in 2002 and 2004, in the Gulf of Mexico in 2006 and in the northern Atlantic in 2008. Surface measurements were made in Beijing in 2005, in Mexico City in 2006 and at Blodgett Forest in 2007. In this presentation we will first make a comparison of the averaged observations between these different field studies. Average altitude profiles, surface mixing ratios and the diurnal variations therein will be compared, which gives a unique and detailed insight into the atmospheric distribution of VOCs. We will next turn to several case studies describing our observations in urban, forest fire and industrial plumes with a special focus on oxygenated VOCs. Insights into the natural sources of oxygenated VOCs from forests and oceans are described. Finally, we will briefly discuss new instrument developments in our laboratory.

  19. Estimating sources, sinks and fluxes of reactive atmospheric compounds within a forest canopy

    Science.gov (United States)

    While few dispute the significance of within-canopy sources or sinks of reactive gaseous and particulate compounds, their estimation continues to be the subject of active research and debate. Reactive species undergo turbulent dispersion within an inhomogeneous flow field, and ma...

  20. Evolution of the Lunar Receiving Laboratory to the Astromaterial Sample Curation Facility: Technical Tensions Between Containment and Cleanliness, Between Particulate and Organic Cleanliness

    Science.gov (United States)

    Allton, J. H.; Zeigler, R. A.; Calaway, M. J.

    2016-01-01

    The Lunar Receiving Laboratory (LRL) was planned and constructed in the 1960s to support the Apollo program in the context of landing on the Moon and safely returning humans. The enduring science return from that effort is a result of careful curation of planetary materials. Technical decisions for the first facility included sample handling environment (vacuum vs inert gas), and instruments for making basic sample assessment, but the most difficult decision, and most visible, was stringent biosafety vs ultra-clean sample handling. Biosafety required handling of samples in negative pressure gloveboxes and rooms for containment and use of sterilizing protocols and animal/plant models for hazard assessment. Ultra-clean sample handling worked best in positive pressure nitrogen environment gloveboxes in positive pressure rooms, using cleanable tools of tightly controlled composition. The requirements for these two objectives were so different, that the solution was to design and build a new facility for specific purpose of preserving the scientific integrity of the samples. The resulting Lunar Curatorial Facility was designed and constructed, from 1972-1979, with advice and oversight by a very active committee comprised of lunar sample scientists. The high precision analyses required for planetary science are enabled by stringent contamination control of trace elements in the materials and protocols of construction (e.g., trace element screening for paint and flooring materials) and the equipment used in sample handling and storage. As other astromaterials, especially small particles and atoms, were added to the collections curated, the technical tension between particulate cleanliness and organic cleanliness was addressed in more detail. Techniques for minimizing particulate contamination in sample handling environments use high efficiency air filtering techniques typically requiring organic sealants which offgas. Protocols for reducing adventitious carbon on sample

  1. Dynamics of particulate and dissolved organic and inorganic phosphorus during the peak and declining phase of an iron-induced phytoplankton bloom in the eastern subarctic Pacific

    Science.gov (United States)

    Yoshimura, Takeshi; Nishioka, Jun; Ogawa, Hiroshi; Tsuda, Atsushi

    2018-01-01

    Phosphorus (P) is an essential element for all organisms and thus the P cycle plays a key role in determining the dynamics of lower trophic levels in marine ecosystems. P in seawater occurs conceptually in particulate and dissolved organic and inorganic (POP, PIP, DOP, and DIP, respectively) pools and clarification of the dynamics in these P pools is the basis to assess the biogeochemical cycle of P. Despite its importance, behaviors of each P pool with phytoplankton dynamics have not been fully examined. We measured the four operationally defined P pools (POPop, PIPop, DOPop, and SRP) during an iron-induced phytoplankton bloom (as part of the subarctic ecosystem response to iron enrichment study (SERIES)) in the eastern subarctic Pacific in summer 2002. During our observations of the iron-enriched patch from day 15 to day 26 after the iron infusion, chlorophyll-a concentration in the surface layer decreased from 6.3 to 1.2 μg L- 1, indicating the peak through decline phase of the phytoplankton bloom. At the bloom peak, P was partitioned into POPop, PIPop, and DOPop in proportions of 60, 27, and 13%, respectively. While chlorophyll-a and POPop showed similar temporal variations during the declining phase, PIPop showed a different peak timing with a 2 day delay compared to POPop, resulting in a rapid change in the relative proportion of PIPop to total particulate P (TPP = POPop + PIPop) at the peak (25%) and during the declining phase of the bloom (50%). A part of POPop was replaced by PIPop just after slowing down of phytoplankton growth. This process may have a significant role in the subsequent regeneration of P. We conclude that measurement of TPP alone is insufficient to show the interaction between P and phytoplankton dynamics and fractionation of TPP into POPop and PIPop provides useful insights to clarify the biogeochemical cycle of P.

  2. Variation of particulate organic carbon and its relationship with bio-optical properties during a phytoplankton bloom in the Pearl River estuary

    International Nuclear Information System (INIS)

    Wang Guifen; Zhou Wen; Cao Wenxi; Yin Jianping; Yang Yuezhong; Sun Zhaohua; Zhang Yuanzhi; Zhao Jun

    2011-01-01

    Highlights: → A study about relationship between POC and optical properties during a phytoplankton bloom. → Empirical algorithms for retrieving POC concentration from optical data were developed. → Phytoplankton carbon and it's ratio to Chl-a are estimated and discussed. → Demonstrates that marine optical buoy can be a new platform for monitoring biogeochemical cycle. - Abstract: In this study, variations in the particulate organic carbon (POC) were monitored during a phytoplankton bloom event, and the corresponding changes in bio-optical properties were tracked at one station (114.29 o E, 22.06 o N) located in the Pearl River estuary. A greater than 10-fold increase in POC (112.29-1173.36 mg m -3 ) was observed during the bloom, with the chlorophyll a concentration (Chl-a) varying from 0.984 to 25.941 mg m -3 . A power law function is used to describe the relationship between POC and Chl-a, and the POC:Chl-a ratio tends to change inversely with Chl-a. Phytoplankton carbon concentration is indirectly estimated using the conceptual model proposed by , and this carbon is found to contribute 47.21% (±10.65%) to total POC. The estimated carbon-to-chlorophyll ratio of phytoplankton in diatom-dominated waters is found to be comparable with results reported in the literature. Empirical algorithms for determining the concentrations of Chl-a and POC were developed based on the relationships of these variables with the blue-to-green reflectance ratio. With these bio-optical models, the levels of particulate organic carbon and Chl-a could be predicted from the radiometric data measured by a marine optical buoy, which showed much more detailed information about the variability in biogeochemical parameters during this bloom event.

  3. [Review of lime carbon sink.

    Science.gov (United States)

    Liu, Li Li; Ling, Jiang Hua; Tie, Li; Wang, Jiao Yue; Bing, Long Fei; Xi, Feng Ming

    2018-01-01

    Under the background of "missing carbon sink" mystery and carbon capture and storage (CCS) technology development, this paper summarized the lime material flow process carbon sink from the lime carbonation principles, impact factors, and lime utilization categories in chemical industry, metallurgy industry, construction industry, and lime kiln ash treatment. The results showed that the lime carbonation rate coefficients were mainly impacted by materials and ambient conditions; the lime carbon sink was mainly in chemical, metallurgy, and construction industries; and current researches focused on the mechanisms and impact factors for carbonation, but their carbon sequestration calculation methods had not been proposed. Therefore, future research should focus on following aspects: to establish a complete system of lime carbon sequestration accounting method in view of material flow; to calculate lime carbon sequestration in both China and the world and explain their offset proportion of CO 2 emission from lime industrial process; to analyze the contribution of lime carbon sequestration to missing carbon sink for clarifying part of missing carbon sinks; to promote the development of carbon capture and storage technology and provide some scientific bases for China's international negotiations on climate change.

  4. Characterisation of the organic composition of size segregated atmospheric particulate matter at traffic exposed and background sites in Madrid

    Science.gov (United States)

    Mirante, F.; Perez, R.; Alves, C.; Revuelta, M.; Pio, C.; Artiñano, B.; Nunes, T.

    2010-05-01

    The growing awareness of the impact of atmospheric particulate matter (PM) on climate, and the incompletely recognised but serious effects of anthropogenic aerosols on air quality and human health, have led to diverse studies involving almost exclusively the coarse or the fine PM fractions. However, these environmental effects, the PM formation processes and the source assignment depend greatly on the particle size distribution. The innovative character of this study consists in obtaining time series with a size-segregated detailed chemical composition of PM for differently polluted sites. In this perspective, a summer sampling campaign was carried out from 1 of June to 1 of July 2009. One of the sampling sites was located at a representative urban monitoring station (Escuelas Aguirre) belonging to the municipal network, located at a heavy traffic street intersection in downtown Madrid. Other sampling point was positioned within the CIEMAT area, located in the NW corner of the city, which can be considered an urban background or suburban site. Particulate matter was sampled with high volume cascade impactors at 4 size stages: 10-2.5, 2.5-0.95, 0.95-0.45 and sources (e.g. vehicular). Carbon preference indices (CPI) close to the unity and the presence of PAHs point out vehicle exhaust as the main emission source of the aliphatic and polycyclic aromatic fractions, especially for the roadside aerosols. Concentration ratios between PAHs were also used to assign emission sources. The abundance and the sources of these carcinogenic pollutants are discussed and compared taking into account the local/regional characteristics. Water-soluble ions in PM were also analysed by ionic chromatography. A portion of the same filters was subjected to metal speciation by Inductively Coupled Plasma Mass Spectrometry (ICP-MS) or Instrumental Neutron Activation Analysis (INAA). Receptor-oriented modelling for source apportionment was applied to the size-segregated PM chemical composition

  5. Mutagenic and recombinagenic activity of airborne particulates, PM10 and TSP, organic extracts in the Drosophila wing-spot test

    Energy Technology Data Exchange (ETDEWEB)

    Rodrigues Dihl, Rafael [Programa de Pos Graduacao em Genetica e Biologia Molecular (PPGBM), Universidade Federal do Rio Grande do Sul, Porto Alegre, RS (Brazil); Grazielli Azevedo da Silva, Carla [Instituto de Quimica, Departamento de Quimica Organica, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS (Brazil); Souza do Amaral, Viviane; Reguly, Maria Luiza [Laboratorio de Diagnostico da Toxicidade Genetica (TOXIGEN), Programa de Pos Graduacao em Genetica e Toxicologia Aplicada (PPGGTA), Universidade Luterana do Brasil - ULBRA, Avenida Farroupilha 8001, 92420280 Canoas, RS (Brazil); Rodrigues de Andrade, Heloisa Helena [Laboratorio de Diagnostico da Toxicidade Genetica (TOXIGEN), Programa de Pos Graduacao em Genetica e Toxicologia Aplicada (PPGGTA), Universidade Luterana do Brasil -ULBRA, Avenida Farroupilha 8001, 92420280 Canoas, RS (Brazil)], E-mail: heloisa@ulbra.br

    2008-01-15

    The genotoxicity associated with air pollution in the city of Canoas, Rio Grande do Sul (Brazil), was assessed in November (spring) and January (summer). We applied the somatic mutation and recombination test (SMART) in Drosophila melanogaster in its standard version with normal bioactivation (ST) and in its variant with increased cytochrome P450-dependent biotransformation capacity (HB). The data indicated the genotoxicity of TSP and PM10 collected in November, in both ST and HB crosses. The genotoxic activity of the PM10 material in the spring sample was exclusively associated with the induction of mitotic recombination, whereas the TSP genetic toxicity was due to both recombinational as well as point and/or chromosomal mutation events. Considering PM10 collected in January, a positive response-100% (17.10 m{sup 3}/ml) concentration-was observed in the HB cross, which was not detected in the ST cross. - Drosophila Wing-Spot Test can be used for detection of airborne particulates mutagenesis.

  6. Sinking bubbles in stout beers

    Science.gov (United States)

    Lee, W. T.; Kaar, S.; O'Brien, S. B. G.

    2018-04-01

    A surprising phenomenon witnessed by many is the sinking bubbles seen in a settling pint of stout beer. Bubbles are less dense than the surrounding fluid so how does this happen? Previous work has shown that the explanation lies in a circulation of fluid promoted by the tilted sides of the glass. However, this work has relied heavily on computational fluid dynamics (CFD) simulations. Here, we show that the phenomenon of sinking bubbles can be predicted using a simple analytic model. To make the model analytically tractable, we work in the limit of small bubbles and consider a simplified geometry. The model confirms both the existence of sinking bubbles and the previously proposed mechanism.

  7. Tetra- and hexavalent uranium forms bidentate-mononuclear complexes with particulate organic matter in a naturally uranium-enriched peatland

    DEFF Research Database (Denmark)

    Mikutta, Christian; Langner, Peggy; Bargar, John R.

    2016-01-01

    Peatlands frequently serve as efficient biogeochemical traps for U. Mechanisms of U immobilization in these organic matter-dominated environments may encompass the precipitation of U-bearing mineral(oid)s and the complexation of U by a vast range of (in)organic surfaces. The objective of this work...... of bidentate-mononuclear U(IV/VI) complexes with carboxyl groups. We neither found evidence for U shells at ∼3.9 Å, indicative of mineral-associated U or multinuclear U(IV) species, nor for a substantial P/Fe coordination of U. Our data indicates that U(IV/VI) complexation by natural organic matter prevents...... the precipitation of U minerals as well as U complexation by Fe/Mn phases at our field site, and suggests that organically complexed U(IV) is formed via reduction of organic matter-bound U(VI)....

  8. Determination of metallo-organic and particulate wear metals in lubricating oils associated with hybrid ceramic bearings by inductively coupled plasma mass spectrometry

    Science.gov (United States)

    Russell, Robin Ann

    It is possible to increase both the performance and operating environment of jet engines by using hybrid ceramic bearings. Our laboratory is concerned with investigating lubricating fluids for wear metals associated with silicon nitride ball bearings and steel raceways. Silicon nitride is characterized by low weight, low thermal expansion, high strength, and corrosion resistance. These attributes result in longer engine lifetimes than when metallic ball bearings are used. Before the routine use of ceramic ball bearings can be realized, the wear mechanisms of the materials should be thoroughly understood. One important variable in determining wear degradation is the concentration of metal present in the lubricating oils used with the bearings. A complete method for analyzing used lubricating oils for wear metal content must accurately determine all metal forms present. Oil samples pose problems for routine analysis due to complex organic matrices. Nebulizing these types of samples into an Inductively Coupled Plasma - Mass Spectrometer introduces many problems including clogging of the sample cone with carbon and increasing interferences. In addition, other techniques such as Atomic Absorption Spectrometry and Atomic Emission Spectrometry are particle size dependent. They are unable to analyze particles greater than 10 mum in size. This dissertation describes a method of analyzing lubricating oils for both metallo-organic and particulate species by ICP-MS. Microwave digestion of the oil samples eliminates the need for elaborate sample introduction schemes as well as the use of a modified carrier gas. Al, Cr, Fe, Mg, Mo, Ni, Ti, and Y have been determined in both aqueous and organic media. Metallo-organic solutions of these metals were successfully digested, nebulized into the ICP, and the singly charged ions measured by mass spectrometry. Metal particulates in oil matrices have also been quantitatively determined by the above method. Linear analytical curves were

  9. Long-term particulate matter modeling for health effect studies in California - Part 2: Concentrations and sources of ultrafine organic aerosols

    Science.gov (United States)

    Hu, Jianlin; Jathar, Shantanu; Zhang, Hongliang; Ying, Qi; Chen, Shu-Hua; Cappa, Christopher D.; Kleeman, Michael J.

    2017-04-01

    Organic aerosol (OA) is a major constituent of ultrafine particulate matter (PM0. 1). Recent epidemiological studies have identified associations between PM0. 1 OA and premature mortality and low birth weight. In this study, the source-oriented UCD/CIT model was used to simulate the concentrations and sources of primary organic aerosols (POA) and secondary organic aerosols (SOA) in PM0. 1 in California for a 9-year (2000-2008) modeling period with 4 km horizontal resolution to provide more insights about PM0. 1 OA for health effect studies. As a related quality control, predicted monthly average concentrations of fine particulate matter (PM2. 5) total organic carbon at six major urban sites had mean fractional bias of -0.31 to 0.19 and mean fractional errors of 0.4 to 0.59. The predicted ratio of PM2. 5 SOA / OA was lower than estimates derived from chemical mass balance (CMB) calculations by a factor of 2-3, which suggests the potential effects of processes such as POA volatility, additional SOA formation mechanism, and missing sources. OA in PM0. 1, the focus size fraction of this study, is dominated by POA. Wood smoke is found to be the single biggest source of PM0. 1 OA in winter in California, while meat cooking, mobile emissions (gasoline and diesel engines), and other anthropogenic sources (mainly solvent usage and waste disposal) are the most important sources in summer. Biogenic emissions are predicted to be the largest PM0. 1 SOA source, followed by mobile sources and other anthropogenic sources, but these rankings are sensitive to the SOA model used in the calculation. Air pollution control programs aiming to reduce the PM0. 1 OA concentrations should consider controlling solvent usage, waste disposal, and mobile emissions in California, but these findings should be revisited after the latest science is incorporated into the SOA exposure calculations. The spatial distributions of SOA associated with different sources are not sensitive to the choice of

  10. Source-sink relationships in radish plant

    Directory of Open Access Journals (Sweden)

    Z. Starck

    2015-01-01

    Full Text Available The problem of source-sink relationships in di- and tetraploidal radish plants grown in. hydroponic cultures was investigated in two stages of their development: with intensively growing swollen hypocotyl and in the period of actively accumulating nutrients in the storage organ. It was found, that the proportion, between the mass of organs, their RGR and NAR was very similar in di- and tetraploidal populations, probably owing to a similar rate of photosynthesis and pattern of assimilates distribution. The high variability of swollen hypocotyls size is slightly correlated with the size of the whole aerial part and is not correlated with the rate of photosynthesis in leaves. Partial defoliation of radish plants did not affect the rate of photosynthesis of the remaining leaves. Only in the cotyledones the oldest donors of 14C-assimilates, a slight compensation of photosynthesis was reported. It may suggest, that the rate of photosynthesis in radish plants is not under the control of sink activity. The size of the storage organ have determined in some extent its attractive force and influenced the amount of 14C-assimilates exported from their donors. Translocation of photosynthates from the young, still growing leaves was conditioned mainly by their retention power. Therefore, in young radish plants cotyledons were the main donor of 14C-assimilates.

  11. How Low Can You Sink?

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 2; Issue 2. How Low Can You Sink? In Search of Global Minima. Vivek S Borkar. General Article Volume 2 ... Author Affiliations. Vivek S Borkar1. Department of Computer Science and Automation, Indian Institute of Science, Bangalore 560 012, India ...

  12. Anthropogenic impacts on the optical characteristics and biodegradability of dissolved and particulate organic matter in the Han River watershed, South Korea

    Science.gov (United States)

    Shirina Begum, Most; Jin, Hyojin; Yoon, Tae Kyung; Park, Ji-Hyung

    2016-04-01

    To understand how anthropogenic perturbations such as dams and pollution modify the chemical characteristics and biological transformations of riverine organic matter during transit through urbanized watersheds, we compared the optical characteristics and biodegradability of dissolved organic matter (DOM) and particulate organic matter (POM) along different reaches and urban tributary streams of the Han River watershed during short-term incubations. Laboratory incubations were conducted for 5-7 days at 20-25 oC with filtered or unfiltered water samples collected from up-, mid-, and downstream reaches with different levels of anthropogenic perturbations and three urban streams along the downstream reach that receive effluents from waste water treatment facilities in the metropolitan Seoul. Optical parameters such as ultraviolet absorbance at 254 nm, absorption coefficients at 254 nm and 350 nm, fluorescence index, humic-like fluorescence, microbial humic-like fluorescence, and protein-like fluorescence, and spectral slope at 350-400 nm were significantly correlated with increasing concentration of biodegradable dissolved organic carbon (BDOC) in filtered and unfiltered sample along the Han River up-, mid-, down-, and urban streams. The concentrations of BDOC in the urban streams were 6-12 times higher than in the filtered and unfiltered main-stem river samples, with significantly higher values in presence of POM in the unfiltered samples than in the filtered samples. In a separate 5-day incubation experiment with the unfiltered water sample from a downstream location of the Han River and its urban tributary water in isolation or mixed , the rate of concurrent biodegradation of both DOM and POM, as measured by the cumulative rate of CO2 production, was higher in the mixture than the average rate of the separately incubated samples, indicating the priming effect of mixed organic materials on the biodegradation of allochthonous organic materials from the other site

  13. Bacterioplankton: a sink for carbon in a coastal marine plankton community

    International Nuclear Information System (INIS)

    Ducklow, H.W.; Purdie, D.A.; Williams, P.J.LeB.; Davis, J.M.

    1986-01-01

    Recent determinations of high production rates (up to 30% of primary production in surface waters) implicate free-living marine bacterioplankton as a link in a microbial loop that supplements phytoplankton as food for herbivores. An enclosed water column of 300 cubic meters was used to test the microbial loop hypothesis by following the fate of carbon-14-labeled bacterioplankton for over 50 days. Only 2% of the label initially fixed from carbon-14-labeled glucose by bacteria was present in larger organisms after 13 days, at which time about 20% of the total label added remained in the particulate fraction. Most of the label appeared to pass directly from particles smaller than 1 micrometer (heterotrophic bacterioplankton and some bacteriovores) to respired labeled carbon dioxide or to regenerated dissolved organic carbon-14. Secondary (and, by implication, primary) production by organisms smaller than 1 micrometer may not be an important food source in marine food chains. Bacterioplankton can be a sink for carbon in planktonic food webs and may serve principally as agents of nutrient regeneration rather than as food

  14. Aggregation controls the stability of lignin and lipids in clay-sized particulate and mineral associated organic matter

    Czech Academy of Sciences Publication Activity Database

    Angst, Gerrit; Mueller, K.E.; Kögel-Knabner, I.; Freeman, K.H.; Mueller, C.W.

    2017-01-01

    Roč. 132, č. 3 (2017), s. 307-324 ISSN 0168-2563 Institutional support: RVO:60077344 Keywords : incubation * physical fractionation * GC/MS * C-13 NMR * CuO * soil organic matter Subject RIV: DF - Soil Science OBOR OECD: Soil science Impact factor: 3.428, year: 2016

  15. Diurnally resolved particulate and VOC measurements at a rural site: indication of significant biogenic secondary organic aerosol formation

    Science.gov (United States)

    Sjostedt, S. J.; Slowik, J. G.; Brook, J. R.; Chang, R. Y.-W.; Mihele, C.; Stroud, C. A.; Vlasenko, A.; Abbatt, J. P. D.

    2011-06-01

    We report simultaneous measurements of volatile organic compound (VOC) mixing ratios including C6 to C8 aromatics, isoprene, monoterpenes, acetone and organic aerosol mass loadings at a rural location in southwestern Ontario, Canada by Proton-Transfer-Reaction Mass Spectrometry (PTR-MS) and Aerosol Mass Spectrometry (AMS), respectively. During the three-week-long Border Air Quality and Meteorology Study in June-July 2007, air was sampled from a range of sources, including aged air from the polluted US Midwest, direct outflow from Detroit 50 km away, and clean air with higher biogenic input. After normalization to the diurnal profile of CO, a long-lived tracer, diurnal analyses show clear photochemical loss of reactive aromatics and production of oxygenated VOCs and secondary organic aerosol (SOA) during the daytime. Biogenic VOC mixing ratios increase during the daytime in accord with their light- and temperature-dependent sources. Long-lived species, such as hydrocarbon-like organic aerosol and benzene show little to no photochemical reactivity on this timescale. From the normalized diurnal profiles of VOCs, an estimate of OH concentrations during the daytime, measured O3 concentrations, and laboratory SOA yields, we calculate integrated local organic aerosol production amounts associated with each measured SOA precursor. Under the assumption that biogenic precursors are uniformly distributed across the southwestern Ontario location, we conclude that such precursors contribute significantly to the total amount of SOA formation, even during the period of Detroit outflow. The importance of aromatic precursors is more difficult to assess given that their sources are likely to be localized and thus of variable impact at the sampling location.

  16. Tetra- and hexavalent uranium forms bidentate-mononuclear complexes with particulate organic matter in a naturally uranium-enriched peatland

    International Nuclear Information System (INIS)

    Mikutta, Christian; Langner, Peggy; Bargar, John R.; Kretzschmar, Ruben

    2016-01-01

    Peatlands frequently serve as efficient biogeochemical traps for U. Mechanisms of U immobilization in these organic matter-dominated environments may encompass the precipitation of U-bearing mineral(oid)s and the complexation of U by a vast range of (in)organic surfaces. The objective of this work was to investigate the spatial distribution and molecular binding mechanisms of U in soils of an alpine minerotrophic peatland (pH 4.7–6.6, E_h = –127 to 463 mV) using microfocused X-ray fluorescence spectrometry and bulk and microfocused U L_3-edge X-ray absorption spectroscopy. The soils contained 2.3–47.4 wt % organic C, 4.1–58.6 g/kg Fe, and up to 335 mg/kg geogenic U. Uranium was found to be heterogeneously distributed at the micrometer scale and enriched as both U(IV) and U(VI) on fibrous and woody plant debris (48 ± 10% U(IV), x̄ ± σ, n = 22). Bulk U X-ray absorption near edge structure (XANES) spectroscopy revealed that in all samples U(IV) comprised 35–68% of total U (x̄ = 50%, n = 15). Shell-fit analyses of bulk U L_3-edge extended X-ray absorption fine structure (EXAFS) spectra showed that U was coordinated to 1.3 ± 0.2 C atoms at a distance of 2.91 ± 0.01 Å (x̄ ± σ), which implies the formation of bidentate-mononuclear U(IV/VI) complexes with carboxyl groups. We neither found evidence for U shells at ~3.9 Å, indicative of mineral-associated U or multinuclear U(IV) species, nor for a substantial P/Fe coordination of U. As a result, our data indicates that U(IV/VI) complexation by natural organic matter prevents the precipitation of U minerals as well as U complexation by Fe/Mn phases at our field site, and suggests that organically complexed U(IV) is formed via reduction of organic matter-bound U(VI).

  17. Tetra- and Hexavalent Uranium Forms Bidentate-Mononuclear Complexes with Particulate Organic Matter in a Naturally Uranium-Enriched Peatland.

    Science.gov (United States)

    Mikutta, Christian; Langner, Peggy; Bargar, John R; Kretzschmar, Ruben

    2016-10-04

    Peatlands frequently serve as efficient biogeochemical traps for U. Mechanisms of U immobilization in these organic matter-dominated environments may encompass the precipitation of U-bearing mineral(oid)s and the complexation of U by a vast range of (in)organic surfaces. The objective of this work was to investigate the spatial distribution and molecular binding mechanisms of U in soils of an alpine minerotrophic peatland (pH 4.7-6.6, E h = -127 to 463 mV) using microfocused X-ray fluorescence spectrometry and bulk and microfocused U L 3 -edge X-ray absorption spectroscopy. The soils contained 2.3-47.4 wt % organic C, 4.1-58.6 g/kg Fe, and up to 335 mg/kg geogenic U. Uranium was found to be heterogeneously distributed at the micrometer scale and enriched as both U(IV) and U(VI) on fibrous and woody plant debris (48 ± 10% U(IV), x̅ ± σ, n = 22). Bulk U X-ray absorption near edge structure (XANES) spectroscopy revealed that in all samples U(IV) comprised 35-68% of total U (x̅ = 50%, n = 15). Shell-fit analyses of bulk U L 3 -edge extended X-ray absorption fine structure (EXAFS) spectra showed that U was coordinated to 1.3 ± 0.2 C atoms at a distance of 2.91 ± 0.01 Å (x̅ ± σ), which implies the formation of bidentate-mononuclear U(IV/VI) complexes with carboxyl groups. We neither found evidence for U shells at ∼3.9 Å, indicative of mineral-associated U or multinuclear U(IV) species, nor for a substantial P/Fe coordination of U. Our data indicates that U(IV/VI) complexation by natural organic matter prevents the precipitation of U minerals as well as U complexation by Fe/Mn phases at our field site, and suggests that organically complexed U(IV) is formed via reduction of organic matter-bound U(VI).

  18. Application of Natural Radioisotopes as Tracers of Particulate Organic Carbon Transport, Export and Burial Processes in Chukchi Sea, Arctic Ocean

    Energy Technology Data Exchange (ETDEWEB)

    Wen, Yu; Jianhua, He [Key Lab of Global Change and Marine-Atmosphere Chemistry, State Oceanic Administration, Xiamen (China)

    2013-07-15

    To evaluate the efficiency of the biological pump and carbon sequestration content on the Arctic shelf, estimations of POC export fluxes derived from 234Th/238U disequilibrium and organic carbon burial rate from 210Pbex chronology in sediment core were made during the 3rd Chinese National Arctic Research Expedition (CHINARE-3), Jul 12-Sep 22, 2008. Great deficits of {sup 234}Th to {sup 238}U were observed widely over the Chukchi shelf, with an average {sup 234}Th/{sup 238}U of 0.64{+-}0.28, resulting from intense particle scavenging. The average POC export fluxes in the entire study area, shelf and slope area were 24.9 {+-} 23.3, 29.5 {+-} 23.0 and 2.1 {+-} 0.5 mmol C/m{sup 2}d, respectively, i.e. 21% of the primary production on average was exported to the benthos. An organic carbon burial rate of 517 mmol C/m{sup 2}a were estimated, accounting for 6% of the average primary production. The efficient biological pump led to 11.6{+-}9.0 T g C exported to benthos and 3.4 T g C buried permanently in the sediment per year, accounting for 0.3% of total POC export amount and 2.1% of total organic carbon burial amount of the global ocean. (author)

  19. Mercury, trace elements and organic constituents in atmospheric fine particulate matter, Shenandoah National Park, Virginia, USA: A combined approach to sampling and analysis

    Science.gov (United States)

    Kolker, A.; Engle, M.A.; Orem, W.H.; Bunnell, J.E.; Lerch, H.E.; Krabbenhoft, D.P.; Olson, M.L.; McCord, J.D.

    2008-01-01

    Compliance with U.S. air quality regulatory standards for atmospheric fine particulate matter (PM2.5) is based on meeting average 24 hour (35 ?? m-3) and yearly (15 ??g m-3) mass-per-unit-volume limits, regardless of PM2.5 composition. Whereas this presents a workable regulatory framework, information on particle composition is needed to assess the fate and transport of PM2.5 and determine potential environmental/human health impacts. To address these important non-regulatory issues an integrated approach is generally used that includes (1) field sampling of atmospheric particulate matter on filter media, using a size-limiting cyclone, or with no particle-size limitation; and (2) chemical extraction of exposed filters and analysis of separate particulate-bound fractions for total mercury, trace elements and organic constituents, utilising different USGS laboratories optimised for quantitative analysis of these substances. This combination of sampling and analysis allowed for a more detailed interpretation of PM2.5 sources and potential effects, compared to measurements of PM2.5 abundance alone. Results obtained using this combined approach are presented for a 2006 air sampling campaign in Shenandoah National Park (Virginia, USA) to assess sources of atmospheric contaminants and their potential impact on air quality in the Park. PM2.5 was collected at two sampling sites (Big Meadows and Pinnacles) separated by 13.6 km. At both sites, element concentrations in PM2.5 were low, consistent with remote or rural locations. However, element/Zr crustal abundance enrichment factors greater than 10, indicating anthropogenic input, were found for Hg, Se, S, Sb, Cd, Pb, Mo, Zn and Cu, listed in decreasing order of enrichment. Principal component analysis showed that four element associations accounted for 84% of the PM 2.5 trace element variation; these associations are interpreted to represent: (1) crustal sources (Al, REE); (2) coal combustion (Se, Sb), (3) metal production

  20. Water column distribution and carbon isotopic signal of cholesterol, brassicasterol and particulate organic carbon in the Atlantic sector of the Southern Ocean

    Directory of Open Access Journals (Sweden)

    A.-J. Cavagna

    2013-04-01

    Full Text Available The combination of concentrations and δ13C signatures of Particulate Organic Carbon (POC and sterols provides a powerful approach to study ecological and environmental changes in both the modern and ancient ocean. We applied this tool to study the biogeochemical changes in the modern ocean water column during the BONUS-GoodHope survey (February–March 2008 from Cape Basin to the northern part of the Weddell Gyre. Cholesterol and brassicasterol were chosen as ideal biomarkers of the heterotrophic and autotrophic carbon pools, respectively, because of their ubiquitous and relatively refractory nature. We document depth distributions of concentrations (relative to bulk POC and δ13C signatures of cholesterol and brassicasterol combined with CO2 aq. surface concentration variation. While the relationship between CO2 aq. and δ13C of bulk POC and biomarkers have been reported by others for the surface water, our data show that this persists in mesopelagic and deep waters, suggesting that δ13C signatures of certain biomarkers in the water column could be applied as proxies for surface water CO2 aq. We observed a general increase in sterol δ13C signatures with depth, which is likely related to a combination of particle size effects, selective feeding on larger cells by zooplankton, and growth rate related effects. Our data suggest a key role of zooplankton fecal aggregates in carbon export for this part of the Southern Ocean (SO. Additionally, in the southern part of the transect south of the Polar Front (PF, the release of sea-ice algae during the ice demise in the Seasonal Ice Zone (SIZ is hypothesized to influence the isotopic signature of sterols in the open ocean. Overall, the combined use of δ13C values and concentrations measurements of both bulk organic C and specific sterols throughout the water column offers the promising potential to explore the recent history of plankton and the fate of organic matter in the SO.

  1. Tropical Wetlands as Carbon Sinks

    Science.gov (United States)

    Jones, M. B.; Saunders, M.

    2007-12-01

    This presentation focuses on the tropical wetlands of sub-Saharan Africa. These are an understudied ecosystem in which large emergent grasses and sedges normally dominate and which have the potential to sequester significant amounts of carbon. Measurements of Net Primary Production of these wetlands show that they are some of the highest values recorded for any ecosystem. We have used eddy covariance to measure Net Ecosystem Exchange of pristine and disturbed wetlands and show that pristine systems can have sink strengths as strong as tropical forests while disturbed systems that have been reclaimed for agricultural purposes have a very much reduced carbon sink activity and may be net carbon sources. The management issues surrounding the use of these wetlands illustrate a direct conflict between the production of food crops for the local population and the maintenance of carbon sequestration as an ecosystem service.

  2. Sinking offshore platform. Nedsenkbar fralandsplatform

    Energy Technology Data Exchange (ETDEWEB)

    Einstabland, T.B.; Olsen, O.

    1988-12-19

    The invention deals with a sinking offshore platform of the gravitational type designed for being installed on the sea bed on great depths. The platform consists of at least three inclining pillars placed on a foundation unit. The pillars are at the upper end connected to a tower structure by means of a rigid construction. The tower supports the platform deck. The rigid construction comprises a centre-positioned cylinder connected to the foundation. 11 figs.

  3. Land-use impacts on fatty acid profiles of suspended particulate organic matter along a larger tropical river

    DEFF Research Database (Denmark)

    Boëchat, Iola; Krüger, Angela; Chavez, R.C.

    2014-01-01

    (SPOM-FAs) as indicators of land-use change in tropical catchments, and at identifying major human impacts on the biochemical composition of SPOM, which represents an important basal energy and organic matter resource for aquatic consumers. River water SPOM and total FA concentrations ranged between 2......Land-use change, such as agricultural expansion and urbanization, can affect riverine biological diversity and ecosystem functioning. Identifying the major stressors associated with catchment land-use change is a prerequisite for devising successful river conservation and restoration strategies...

  4. A Comprehensive Study of Data Collection Schemes Using Mobile Sinks in Wireless Sensor Networks

    Science.gov (United States)

    Khan, Abdul Waheed; Abdullah, Abdul Hanan; Anisi, Mohammad Hossein; Bangash, Javed Iqbal

    2014-01-01

    Recently sink mobility has been exploited in numerous schemes to prolong the lifetime of wireless sensor networks (WSNs). Contrary to traditional WSNs where sensory data from sensor field is ultimately sent to a static sink, mobile sink-based approaches alleviate energy-holes issues thereby facilitating balanced energy consumption among nodes. In mobility scenarios, nodes need to keep track of the latest location of mobile sinks for data delivery. However, frequent propagation of sink topological updates undermines the energy conservation goal and therefore should be controlled. Furthermore, controlled propagation of sinks' topological updates affects the performance of routing strategies thereby increasing data delivery latency and reducing packet delivery ratios. This paper presents a taxonomy of various data collection/dissemination schemes that exploit sink mobility. Based on how sink mobility is exploited in the sensor field, we classify existing schemes into three classes, namely path constrained, path unconstrained, and controlled sink mobility-based schemes. We also organize existing schemes based on their primary goals and provide a comparative study to aid readers in selecting the appropriate scheme in accordance with their particular intended applications and network dynamics. Finally, we conclude our discussion with the identification of some unresolved issues in pursuit of data delivery to a mobile sink. PMID:24504107

  5. Polychlorinated biphenyls (PCBs) in industrial and municipal effluents: Concentrations, congener profiles, and partitioning onto particulates and organic carbon

    International Nuclear Information System (INIS)

    Balasubramani, Aparna; Howell, Nathan L.; Rifai, Hanadi S.

    2014-01-01

    Wastewater effluent samples were collected in the summer of 2009 from 16 different locations which included municipal and industrial wastewater treatment plants and petrochemical industrial outfalls in the Houston area. The effluent samples were analyzed for all 209 polychlorinated biphenyls (PCBs) congeners using high resolution gas chromatography/high resolution mass spectrometry (HRGC/HRMS) using the USEPA method 1668A. The total PCBs (∑ 209) concentration in the dissolved medium ranged from 1.01 to 8.12 ng/L and ranged from 2.03 to 31.2 ng/L in the suspended medium. Lighter PCB congeners exhibited highest concentrations in the dissolved phase whereas, in the suspended phase, heavier PCBs exhibited the highest concentrations. The PCB homolog concentrations were dominated by monochlorobiphenyls through hexachlorobiphenyls, with dichlorobiphenyls exhibiting the highest concentration amongst them at most of the effluent outfalls, in the suspended phase. Both total suspended solids (TSS) and various organic carbon fractions played an important role in the distribution of the suspended fractions of PCBs in the effluents. The log K oc values determined in the effluents suggest that effluent PCB loads might have more risk and impact than what standard partitioning models predict. - Highlights: • 209 PCB congeners were measured in 16 different municipal and industrial effluents. • PCB congener differences were elucidated for the various effluent types. • In addition to log K ow , organic carbon and TSS affect partitioning of PCBs. • High concentrations of homolog 2 maybe due to biotransformation of PCBs

  6. Semivolatile Organic Compounds (SOCs) in Fine Particulate Matter (PM2.5) during Clear, Fog, and Haze Episodes in Winter in Beijing, China.

    Science.gov (United States)

    Wang, Ting; Tian, Mi; Ding, Nan; Yan, Xiao; Chen, She-Jun; Mo, Yang-Zhi; Yang, Wei-Qiang; Bi, Xin-Hui; Wang, Xin-Ming; Mai, Bi-Xian

    2018-05-01

    Few efforts have been made to elucidate the influence of weather conditions on the fate of semivolatile organic compounds (SOCs). Here, daily fine particulate matter (PM 2.5 ) during clear, haze, and fog episodes collected in the winter in Beijing, China was analyzed for polycyclic aromatic hydrocarbons (PAHs), brominated flame retardants (BFRs), and organophosphate flame retardants (OPFRs). The total concentrations of PAHs, OPFRs, and BFRs had medians of 45.1 ng/m 3 and 1347 and 46.7 pg/m 3 , respectively. The temporal pattern for PAH concentrations was largely dependent on coal combustion for residential heating. OPFR compositions that change during colder period were related to enhanced indoor emissions due to heating. The mean concentrations of SOCs during haze and fog days were 2-10 times higher than those during clear days. We found that BFRs with lower octanol and air partition coefficients tended to increase during haze and fog episodes, be removed from PM 2.5 during clear episodes, or both. For PAHs and OPFRs, pollutants that are more recalcitrant to degradation were prone to accumulate during haze and fog days. The potential source contribution function (PSCF) model indicated that southern and eastern cities were major source regions of SOCs at this site.

  7. Polychlorinated biphenyls (PCBs) in industrial and municipal effluents: Concentrations, congener profiles, and partitioning onto particulates and organic carbon

    Energy Technology Data Exchange (ETDEWEB)

    Balasubramani, Aparna, E-mail: aparna.27889@gmail.com; Howell, Nathan L., E-mail: nlhowell@central.uh.edu; Rifai, Hanadi S., E-mail: rifai@uh.edu

    2014-03-01

    Wastewater effluent samples were collected in the summer of 2009 from 16 different locations which included municipal and industrial wastewater treatment plants and petrochemical industrial outfalls in the Houston area. The effluent samples were analyzed for all 209 polychlorinated biphenyls (PCBs) congeners using high resolution gas chromatography/high resolution mass spectrometry (HRGC/HRMS) using the USEPA method 1668A. The total PCBs (∑ 209) concentration in the dissolved medium ranged from 1.01 to 8.12 ng/L and ranged from 2.03 to 31.2 ng/L in the suspended medium. Lighter PCB congeners exhibited highest concentrations in the dissolved phase whereas, in the suspended phase, heavier PCBs exhibited the highest concentrations. The PCB homolog concentrations were dominated by monochlorobiphenyls through hexachlorobiphenyls, with dichlorobiphenyls exhibiting the highest concentration amongst them at most of the effluent outfalls, in the suspended phase. Both total suspended solids (TSS) and various organic carbon fractions played an important role in the distribution of the suspended fractions of PCBs in the effluents. The log K{sub oc} values determined in the effluents suggest that effluent PCB loads might have more risk and impact than what standard partitioning models predict. - Highlights: • 209 PCB congeners were measured in 16 different municipal and industrial effluents. • PCB congener differences were elucidated for the various effluent types. • In addition to log K{sub ow}, organic carbon and TSS affect partitioning of PCBs. • High concentrations of homolog 2 maybe due to biotransformation of PCBs.

  8. Chemical composition and speciation of particulate organic matter from modern residential small-scale wood combustion appliances.

    Science.gov (United States)

    Czech, Hendryk; Miersch, Toni; Orasche, Jürgen; Abbaszade, Gülcin; Sippula, Olli; Tissari, Jarkko; Michalke, Bernhard; Schnelle-Kreis, Jürgen; Streibel, Thorsten; Jokiniemi, Jorma; Zimmermann, Ralf

    2018-01-15

    Combustion technologies of small-scale wood combustion appliances are continuously developed decrease emissions of various pollutants and increase energy conversion. One strategy to reduce emissions is the implementation of air staging technology in secondary air supply, which became an established technique for modern wood combustion appliances. On that account, emissions from a modern masonry heater fuelled with three types of common logwood (beech, birch and spruce) and a modern pellet boiler fuelled with commercial softwood pellets were investigated, which refer to representative combustion appliances in northern Europe In particular, emphasis was put on the organic constituents of PM2.5, including polycyclic aromatic hydrocarbons (PAHs), oxygenated PAHs (OPAHs) and phenolic species, by targeted and non-targeted mass spectrometric analysis techniques. Compared to conventional wood stoves and pellet boilers, organic emissions from the modern appliances were reduced by at least one order of magnitude, but to a different extent for single species. Hence, characteristic ratios of emission constituents and emission profiles for wood combustion identification and speciation do not hold for this type of advanced combustion technology. Additionally, an overall substantial reduction of typical wood combustion markers, such as phenolic species and anhydrous sugars, were observed. Finally, it was found that slow ignition of log woods changes the distribution of characteristic resin acids and phytosterols as well as their thermal alteration products, which are used as markers for specific wood types. Our results should be considered for wood combustion identification in positive matrix factorisation or chemical mass balance in northern Europe. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Relationships between the surface concentration of particulate organic carbon and optical properties in the eastern South Pacific and eastern Atlantic Oceans

    Directory of Open Access Journals (Sweden)

    D. Stramski

    2008-02-01

    Full Text Available We have examined several approaches for estimating the surface concentration of particulate organic carbon, POC, from optical measurements of spectral remote-sensing reflectance, Rrs(λ, using field data collected in tropical and subtropical waters of the eastern South Pacific and eastern Atlantic Oceans. These approaches include a direct empirical relationship between POC and the blue-to-green band ratio of reflectance, RrsB/Rrs(555, and two-step algorithms that consist of relationships linking reflectance to an inherent optical property IOP (beam attenuation or backscattering coefficient and POC to the IOP. We considered two-step empirical algorithms that exclusively include pairs of empirical relationships and two-step hybrid algorithms that consist of semianalytical models and empirical relationships. The surface POC in our data set ranges from about 10 mg m−3 within the South Pacific Subtropical Gyre to 270 mg m−3 in the Chilean upwelling area, and ancillary data suggest a considerable variation in the characteristics of particulate assemblages in the investigated waters. The POC algorithm based on the direct relationship between POC and RrsB/Rrs(555 promises reasonably good performance in the vast areas of the open ocean covering different provinces from hyperoligotrophic and oligotrophic waters within subtropical gyres to eutrophic coastal upwelling regimes characteristic of eastern ocean boundaries. The best error statistics were found for power function fits to the data of POC vs. Rrs(443/Rrs(555 and POC vs. Rrs(490/Rrs(555. For our data set that includes over 50 data pairs, these relationships are characterized by the mean normalized bias of about 2% and the normalized root mean square error of about 20%. We

  10. Repeated applications of compost and manure mainly affect the size and chemical nature of particulate organic matter in a loamy soil after 8 years

    Science.gov (United States)

    Peltre, Clement; Dignac, Marie-France; Doublet, Jeremy; Plante, Alain; Houot, Sabine

    2013-04-01

    Land application of exogenous organic matter (EOM) of residual origin can help to maintain or increase soil organic carbon (SOC) stocks. However, it remains necessary to quantify and predict the soil C accumulation and to determine under which form the C accumulates. Changes to the chemical composition of soil organic matter (SOM) after repeated applications of composts and farmyard manure were investigated in a field experiment (Qualiagro experiment, Ile-de-France) after 8 years of applications of green waste and sludge compost (GWS), municipal solid waste compost (MSW), biowaste compost (BIOW) or farmyard manure (FYM). The soil was fractionated into particulate organic matter >50 µm (POM), a heavy fraction >50 µm and a 0-50 µm fraction demineralized with hydrofluoric acid (HF). Repeated EOM applications significantly increased total SOC stocks, the C amount in the POM fraction and to a less extent in the 0-50 µm fraction compared to the reference treatment. Compost applications accumulated C preferentially under the form of coarse organic matter of size >50 µm, whereas the FYM accumulated similar C proportions of size >50 µm and 0-50 µm, which was attributed to the presence in the FYM of a fraction of labile C stimulating microbial activity and producing humified by-products together with a fraction of stabilized C directly alimenting the humified fraction of SOC. Pyrolysis-GC/MS and DRIFT spectroscopy revealed enrichment in lignin in the POM fractions of amended soils with GWS, BIOW and FYM. In the soil receiving MSW compost, the pyrolysate of the POM fraction revealed the presence of plastics originating from the MSW compost. A lower C mineralization during laboratory incubation was found for the POM fractions of amended soils compared with the POM from reference soil. This feature was related to a lower ratio of (furfural+acetic acid) / pyrole pyrolysis products in POM of amended vs. reference plots, indicating a higher degree of recalcitrance.. The POM

  11. Verification of Carbon Sink Assessment. Can We Exclude Natural Sinks?

    International Nuclear Information System (INIS)

    Alexandrov, G.; Yamagata, Y

    2004-01-01

    Any human-induced terrestrial sink is susceptible to the effects of elevated atmospheric CO2 concentration, nitrogen deposition, climate variability and other natural or indirect human-induced factors. It has been suggested in climate negotiations that the effects of these factors should be excluded from estimates of carbon sequestration used to meet the emission reduction commitments under the Kyoto Protocol. This paper focuses on the methodologies for factoring out the effects of atmospheric and climate variability/change. We estimate the relative magnitude of the non-human induced effects by using two biosphere models and discuss possibilities for narrowing estimate uncertainty

  12. Assessment of Zn bioavailability: XAFS study on speciation of zinc-particulate organic matter associations in polluted soils

    Energy Technology Data Exchange (ETDEWEB)

    Harfouche, M; Borca, C; Grolimund, D [Swiss Light Source, Institut Paul Scherrer, Villigen (Switzerland); Labanowski, J [UMR CNRS 6008, Laboratoire de Chimie et Microbiologie de l' Eau, Universite de Poitiers (France); Farges, F [USM 201 and CNRS UMR 7202, Museum National d' Histoire Naturelle, Paris (France); Hullebusch, E van [Laboratoire Geomateriaux et Environnement, Universite de Paris-Est (France); Oort, F van, E-mail: messaoud.harfouche@psi.c, E-mail: vanoort@versailles.inra.f [UR INRA 251, Physico-chimie et Ecotoxicologie des Sols d Agrosystemes Contamines, Versailles (France)

    2009-11-15

    We present a study about the behavior of Zn in agricultural soils polluted 100-50 years ago by metallurgical fallout and used nowadays for corn production. Such type of soil concerns an area of several km{sup 2} around former metallurgical complex in Northern France. Despite the moderated metal amounts of these soils, the metals deposited over the agricultural area still indirectly expose nowadays populations through the food chain. In contrast to the most contaminated industrial site, these more distant agricultural areas have been less studied. The study was focused on Zn, a relative mobile metal element, since its predominant occurrence in the surface horizon of sandy textured soils, fifty years after cessation of metallurgical activity suggests its immobilization due to specific soil mechanisms. To evaluate how Zn is associated to POM, Zn K-edge XAFS spectra were collected at 293 K at the SLS on beamlines superXAS and microXAS, using Si(111) monochromators and solid state Ge detectors. Energetic resolution is ca. 2 eV at 9 KeV. Lateral resolution varied from ca. 1 mm{sup 2} to 15 micron{sup 2}. Spectra were normalized with the XAFS 3.0 software. We studied different POM size fractions isolated from soils. The largest POM particles correspond to recent leaves or roots fragments. The finest POM particles correspond to decomposition by-products. The results revealed a multiple and heterogeneous speciation of Zn with POM. We observed that little interactions from next-nearest neighbors around Zn. We concluded that most of the Zn tends to be located in the POM matrix as a Zn-organic speciation. We also collected macroscopic EXAFS data on selected intact POM particles probed at the micron scale. The results show that the remaining Zn-distribution related to inorganic (hot-spots), possibly franklinite-type, is minor compared to the Zn-organic speciation. Such observations will help to better understand the mechanisms that regulate the bioavailability and

  13. Mutagenicity and oxidative damage induced by an organic extract of the particulate emissions from a simulation of the deepwater horizon surface oil burns.

    Science.gov (United States)

    DeMarini, David M; Warren, Sarah H; Lavrich, Katelyn; Flen, Alexis; Aurell, Johanna; Mitchell, William; Greenwell, Dale; Preston, William; Schmid, Judith E; Linak, William P; Hays, Michael D; Samet, James M; Gullett, Brian K

    2017-04-01

    Emissions from oil fires associated with the "Deepwater Horizon" explosion and oil discharge that began on April 20, 2010 in the Gulf of Mexico were analyzed chemically to only a limited extent at the time but were shown to induce oxidative damage in vitro and in mice. To extend this work, we burned oil floating on sea water and performed extensive chemical analyses of the emissions (Gullett et al., Marine Pollut Bull, in press, ). Here, we examine the ability of a dichloromethane extract of the particulate material with an aerodynamic size ≤ 2.5 µm (PM 2.5 ) from those emissions to induce oxidative damage in human lung cells in vitro and mutagenicity in 6 strains of Salmonella. The extract had a percentage of extractable organic material (EOM) of 7.0% and increased expression of the heme oxygenase (HMOX1) gene in BEAS-2B cells after exposure for 4 hr at 20 µg of EOM/ml. However, the extract did not alter mitochondrial respiration rate as measured by extracellular flux analysis. The extract was most mutagenic in TA100 +S9, indicative of a role for polycyclic aromatic hydrocarbons (PAHs), reflective of the high concentrations of PAHs in the emissions (1 g/kg of oil consumed). The extract had a mutagenicity emission factor of 1.8 ± 0.1 × 10 5 revertants/megajoule thermal in TA98 +S9, which was greater than that of diesel exhaust and within an order of magnitude of open burning of wood and plastic. Thus, organics from PM 2.5 of burning oil can induce oxidative responses in human airway epithelial cells and are highly mutagenic. Environ. Mol. Mutagen. 58:162-171, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  14. POM Pulses: Characterizing the Physical and Chemical Properties of Particulate Organic Matter (POM) Mobilized by Large Storm Events and its Influence on Receiving Fluvial Systems

    Science.gov (United States)

    Johnson, E. R.; Rowland, R. D.; Protokowicz, J.; Inamdar, S. P.; Kan, J.; Vargas, R.

    2016-12-01

    Extreme storm events have tremendous erosive energy which is capable of mobilizing vast amounts of material from watershed sources into fluvial systems. This complex mixture of sediment and particulate organic matter (POM) is a nutrient source, and has the potential to impact downstream water quality. The impact of POM on receiving aquatic systems can vary not only by the total amount exported but also by the various sources involved and the particle sizes of POM. This study examines the composition of POM in potential sources and within-event POM by: (1) determining the amount and quality of dissolved organic matter (DOM) that can be leached from coarse, medium and fine particle classes; (2) assessing the C and N content and isotopic character of within-event POM; and (3) coupling physical and chemical properties to evaluate storm event POM influence on stream water. Storm event POM samples and source sediments were collected from a forested headwater catchment (second order stream) in the Piedmont region of Maryland. Samples were sieved into three particle classes - coarse (2mm-1mm), medium (1mm-250µm) and fine (solid state event and source material. Future work will include examination of microbial communities associated with POM particle size classes. Physical size class separation of within-event POM exhibited differences in C:N ratios, δ15N composition, and extracted DOM lability. Smaller size classes exhibited lower C:N ratios, more enriched δ15N and more recalcitrant properties in leached DOM. Source material had varying C:N ratios and contributions to leached DOM. These results indicate that both source and size class strongly influence the POM contribution to fluvial systems during large storm events.

  15. Investigation of internally finned LED heat sinks

    Science.gov (United States)

    Li, Bin; Xiong, Lun; Lai, Chuan; Tang, Yumei

    2018-03-01

    A novel heat sink is proposed, which is composed of a perforated cylinder and internally arranged fins. Numerical studies are performed on the natural convection heat transfer from internally finned heat sinks; experimental studies are carried out to validate the numerical results. To compare the thermal performances of internally finned heat sinks and externally finned heat sinks, the effects of the overall diameter, overall height, and installation direction on maximum temperature, air flow and heat transfer coefficient are investigated. The results demonstrate that internally finned heat sinks show better thermal performance than externally finned heat sinks; the maximum temperature of internally finned heat sinks decreases by up to 20% compared with the externally finned heat sinks. The existence of a perforated cylinder and the installation direction of the heat sink affect the thermal performance significantly; it is shown that the heat transfer coefficient of the heat sink with the perforated cylinder is improved greater than that with the imperforated cylinder by up to 34%, while reducing the mass of the heat sink by up to 13%. Project supported by the Scientific Research Fund of Sichuan Provincial Education Department (No. 18ZB0516) and the Sichuan University of Arts and Science (No. 2016KZ009Y).

  16. Biomarker and carbon isotope constraints (δ{sup 13}C, Δ{sup 14}C) on sources and cycling of particulate organic matter discharged by large Siberian rivers draining permafrost areas

    Energy Technology Data Exchange (ETDEWEB)

    Winterfeld, Maria

    2014-08-15

    Circumpolar permafrost soils store about half of the global soil organic carbon pool. These huge amounts of organic matter (OM) could accumulate due to low temperatures and water saturated soil conditions over the course of millennia. Currently most of this OM remains frozen and therefore does not take part in the active carbon cycle, making permafrost soils a globally important carbon sink. Over the last decades mean annual air temperatures in the Arctic increased stronger than the global mean and this trend is projected to continue. As a result the permafrost carbon pool is under climate pressure possibly creating a positive climate feedback due to the thaw-induced release of greenhouse gases to the atmosphere. Arctic warming will lead to increased annual permafrost thaw depths and Arctic river runoff likely resulting in enhanced mobilization and export of old, previously frozen soil-derived OM. Consequently, the great arctic rivers play an important role in global biogeochemical cycles by connecting the large permafrost carbon pool of their hinterlands with the arctic shelf seas and the Arctic Ocean. The first part of this thesis deals with particulate organic matter (POM) from the Lena Delta and adjacent Buor Khaya Bay. The Lena River in central Siberia is one of the major pathways translocating terrestrial OM from its southernmost reaches near Lake Baikal to the coastal zone of the Laptev Sea. The permafrost soils from the Lena catchment area store huge amounts of pre-aged OM, which is expected to be remobilized due to climate warming. To characterize the composition and vegetation sources of OM discharged by the Lena River, the lignin phenol and carbon isotopic composition (δ{sup 13}C and Δ{sup 14}C) in total suspended matter (TSM) from surface waters, surface sediments from the Buor Khaya Bay along with soils from the Lena Delta's first (Holocene) and third terraces (Pleistocene ice complex) were analyzed. The lignin compositions of these samples are

  17. Microbial association with the dynamics of particulate organic carbon in response to the amendment of elevated CO2-derived wheat residue into a Mollisol.

    Science.gov (United States)

    Wang, Yanhong; Yu, Zhenhua; Li, Yansheng; Wang, Guanghua; Liu, Junjie; Liu, Judong; Liu, Xiaobing; Jin, Jian

    2017-12-31

    As the chemical quality of crop residue is likely to be affected by elevated CO 2 (eCO 2 ), residue amendments may influence soil organic carbon (SOC) sequestration. However, in Mollisols, the dynamics of the SOC fractions in response to amendment with wheat residue produced under eCO 2 and the corresponding microbial community composition remain unknown. Such investigation is essential to residue management, which affects the soil quality and productivity of future farming systems. To narrow this knowledge gap, 13 C-labeled shoot and root residue derived from ambient CO 2 (aCO 2 ) or eCO 2 were amended into Mollisols and incubated for 200days. The soil was sampled during the incubation period to determine the residue-C retained in the three SOC fractions, i.e., coarse intra-aggregate particulate organic C (coarse iPOC), fine iPOC and mineral-associated organic C (MOC). The soil bacterial community was assessed using a MiSeq sequencing instrument. The results showed that the increase in SOC concentrations attributable to the application of the wheat residue primarily occurred in the coarse iPOC fraction. Compared with the aCO 2 -derived shoot residue, the amendment of eCO 2 -derived shoot residue resulted in greater SOC concentrations, whereas no significant differences (P>0.05) were observed between the aCO 2 - and eCO 2 -derived roots. Principal coordinates analysis (PCoA) showed that the residue amendment significantly (P≤0.05) altered the bacterial community composition compared with the non-residue amendment. Additionally, the bacterial community in the aCO 2 -derived shoot treatment differed from those in the other residue treatments until day 200 of the incubation period. The eCO 2 -derived shoot treatment significantly increased (P≤0.05) the relative abundances of the genera Acidobacteriaceae_(Subgroup_1)_uncultured, Bryobacter, Candidatus_Solibacter, Gemmatimonas and Nitrosomonadaceae_uncultured, whereas the opposite trend was observed in Nonomuraea

  18. Sources and transformation of dissolved and particulate organic nitrogen in the North Pacific Subtropical Gyre indicated by compound-specific δ15N analysis of amino acids

    Science.gov (United States)

    Yamaguchi, Yasuhiko T.; McCarthy, Matthew D.

    2018-01-01

    This study explores the use of compound-specific nitrogen isotopes of amino acids (δ15NAA) of coupled dissolved and particulate organic nitrogen (DON, PON) samples as a new approach to examine relative sources, transformation processes, and the potential coupling of these two major forms of N cycle in the ocean water column. We measured δ15NAA distributions in high-molecular-weight dissolved organic nitrogen (HMW DON) and suspended PON in the North Pacific Subtropical Gyre (NPSG) from surface to mesopelagic depths. A new analytical approach achieved far greater δ15NAA measurement precision for DON than earlier work, allowing us to resolve previously obscured differences in δ15NAA signatures, both with depth and between ON pools. We propose that δ15N values of total hydrolysable amino acids (THAA) represents a proxy for proteinaceous ON δ15N values in DON and PON. Together with bulk δ15N values, this allows δ15N values and changes in bulk, proteinaceous, and ;other-N; to be directly evaluated. These novel measurements suggest three main conclusions. First, the δ15NAA signatures of both surface and mesopelagic HMW DON suggest mainly heterotrophic bacterial sources, with mesopelagic HMW DON bearing signatures of far more degraded material compared to surface material. These results contrast with a previous proposal that HMW DON δ15NAA patterns are essentially ;pre-formed; by cyanobacteria in the surface ocean, undergo little change with depth. Second, different δ15NAA values and patterns of HMW DON vs. suspended PON in the surface NPSG suggest that sources and cycling of these two N reservoirs are surpisingly decoupled. Based on molecular δ15N signatures, we propose a new hypothesis that production of surface HMW DON is ultimately derived from subsurface nitrate, while PON in the mixed layer is strongly linked to N2 fixation and N recycling. In contrast, the comparative δ15NAA signatures of HMW DON vs. suspended PON in the mesopelagic also suggest a

  19. Concentration, composition, bioavailability, and N-nitrosodimethylamine formation potential of particulate and dissolved organic nitrogen in wastewater effluents: A comparative study

    International Nuclear Information System (INIS)

    Hu, Haidong; Ma, Haijun; Ding, Lili; Geng, Jinju; Xu, Ke; Huang, Hui; Zhang, Yingying; Ren, Hongqiang

    2016-01-01

    Wastewater-derived organic nitrogen (org-N) can act as both nutrients and carcinogenic nitrogenous disinfection byproduct precursors. In this study, the concentration, composition, bioavailability, and N-nitrosodimethylamine (NDMA) formation potential of particulate organic nitrogen (PON) from three different municipal wastewater treatment plants were characterized and compared with that of effluent dissolved organic nitrogen (DON). The average effluent PON and DON concentrations ranged from 0.09 to 0.55 mg N/L and from 0.91 to 1.88 mg N/L, respectively. According to principal component analysis, org-N composition and characterization differed in PON and DON samples (n = 20). Compared with DON, PON tended to be enriched in protein and nucleic acids, and showed a more proteinaceous character. Composition of org-N functional groups estimated from the X-ray photoelectron spectroscopy N 1s spectra indicate no significant differences in the molecular weight distribution of the protein-like materials between PON and DON. Moreover, PON exhibited a significantly higher bioavailability (61.0 ± 13.3%) compared to DON (38.5 ± 12.4%, p < 0.05, t-test) and a significantly higher NDMA yields (791.4 ± 404.0 ng/mg-N) compared to DON (374.8 ± 62.5 ng/mg-N, p < 0.05, t-test). Accordingly, PON contributed to approximately 12.3–41.7% of the total bioavailable org-N and 22.0–38.4% of the total NDMA precursors in wastewater effluents. Thus, the potential adverse effects of PON on wastewater discharge and reuse applications should not be overlooked, even though it only accounted for 7.4–26.8% of the total effluent org-N. - Highlights: • The concentration, composition, bioavailability, and NDMA FP of PON and DON in wastewater effluents are compared. • PON is enriched in protein and nucleic acids. • PON is more bioavailable and shows higher NDMA yields compared to DON. • PON contributes12–42% of total bioavailable org-N and 22–38% of total NDMA precursors.

  20. Concentration, composition, bioavailability, and N-nitrosodimethylamine formation potential of particulate and dissolved organic nitrogen in wastewater effluents: A comparative study

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Haidong; Ma, Haijun; Ding, Lili; Geng, Jinju; Xu, Ke; Huang, Hui; Zhang, Yingying; Ren, Hongqiang, E-mail: hqren@nju.edu.cn

    2016-11-01

    Wastewater-derived organic nitrogen (org-N) can act as both nutrients and carcinogenic nitrogenous disinfection byproduct precursors. In this study, the concentration, composition, bioavailability, and N-nitrosodimethylamine (NDMA) formation potential of particulate organic nitrogen (PON) from three different municipal wastewater treatment plants were characterized and compared with that of effluent dissolved organic nitrogen (DON). The average effluent PON and DON concentrations ranged from 0.09 to 0.55 mg N/L and from 0.91 to 1.88 mg N/L, respectively. According to principal component analysis, org-N composition and characterization differed in PON and DON samples (n = 20). Compared with DON, PON tended to be enriched in protein and nucleic acids, and showed a more proteinaceous character. Composition of org-N functional groups estimated from the X-ray photoelectron spectroscopy N 1s spectra indicate no significant differences in the molecular weight distribution of the protein-like materials between PON and DON. Moreover, PON exhibited a significantly higher bioavailability (61.0 ± 13.3%) compared to DON (38.5 ± 12.4%, p < 0.05, t-test) and a significantly higher NDMA yields (791.4 ± 404.0 ng/mg-N) compared to DON (374.8 ± 62.5 ng/mg-N, p < 0.05, t-test). Accordingly, PON contributed to approximately 12.3–41.7% of the total bioavailable org-N and 22.0–38.4% of the total NDMA precursors in wastewater effluents. Thus, the potential adverse effects of PON on wastewater discharge and reuse applications should not be overlooked, even though it only accounted for 7.4–26.8% of the total effluent org-N. - Highlights: • The concentration, composition, bioavailability, and NDMA FP of PON and DON in wastewater effluents are compared. • PON is enriched in protein and nucleic acids. • PON is more bioavailable and shows higher NDMA yields compared to DON. • PON contributes12–42% of total bioavailable org-N and 22–38% of total NDMA precursors.

  1. Sink-to-Sink Coordination Framework Using RPL: Routing Protocol for Low Power and Lossy Networks

    Directory of Open Access Journals (Sweden)

    Meer M. Khan

    2016-01-01

    Full Text Available RPL (Routing Protocol for low power and Lossy networks is recommended by Internet Engineering Task Force (IETF for IPv6-based LLNs (Low Power and Lossy Networks. RPL uses a proactive routing approach and each node always maintains an active path to the sink node. Sink-to-sink coordination defines syntax and semantics for the exchange of any network defined parameters among sink nodes like network size, traffic load, mobility of a sink, and so forth. The coordination allows sink to learn about the network condition of neighboring sinks. As a result, sinks can make coordinated decision to increase/decrease their network size for optimizing over all network performance in terms of load sharing, increasing network lifetime, and lowering end-to-end latency of communication. Currently, RPL does not provide any coordination framework that can define message exchange between different sink nodes for enhancing the network performance. In this paper, a sink-to-sink coordination framework is proposed which utilizes the periodic route maintenance messages issued by RPL to exchange network status observed at a sink with its neighboring sinks. The proposed framework distributes network load among sink nodes for achieving higher throughputs and longer network’s life time.

  2. Benthic response to the sedimentation of particulate organic matter at the BIOTRANS station, 47°N, 20°W

    Science.gov (United States)

    Pfannkuche, O.

    The benthic response to the sedimentation of particulate organic matter (POM) was investigated during 1985-1990 at 47°N, 20°W (BIOTRANS station). The first noticeable annual sedimentation of phytodetritus, as indicated by chlorophyll a concentrations in the sediment, occurred as early as late April-early May. Maximum amounts were found in June-July. Two different sedimentation pulses to the sea bed are described that demonstrate interannual variation: the occurrence of salp faecal pellets early in the year 1988 and the massive fall out of a plankton bloom in summer 1986, which deposited approximately 15 mmol C m -2. The benthic reaction to POM pulses was quite diverse. The mega-, macro- and meiobenthos showed no change in biomass, whereas bacterial biomass doubled between March and July. This corresponds to a seasonal maximum of total adenylate biomass. The relative abundance of Foraminifera among the meiobenthos increased during the summer. Benthic activity (ATP, ratio ATP/ETSA), as well as in situ sediment community oxygen consumption rates (SCOC), showed distinct seasonal maxima in July-August of 0.75 mmol C m -2 day -1. Based on SCOC and the carbon demand for growth, a benthic carbon consumption of 0.94 mmol C m -2 day -1 was estimated. This represents about 1.1% of spring bloom primary production and 9.6% of the export flux beneath the 150 m layer, measured during the North Atlantic Bloom Experiment. Bacteria and protozoans colonizing the epibenthic phytodetrital layer were responsible for 60-80% of the seasonal increase in SCOC. The strong reaction of the smaller benthic size groups (bacteria, protozoans) to POM pulses stresses their particular importance for sediment-water interface flux rates.

  3. The dynamic ocean biological pump: Insights from a global compilation of particulate organic carbon, CaCO3, and opal concentration profiles from the mesopelagic

    Science.gov (United States)

    Lam, Phoebe J.; Doney, Scott C.; Bishop, James K. B.

    2011-09-01

    We have compiled a global data set of 62 open ocean profiles of particulate organic carbon (POC), CaCO3, and opal concentrations collected by large volume in situ filtration in the upper 1000 m over the last 30 years. We define concentration-based metrics for the strength (POC concentration at depth) and efficiency (attenuation of POC with depth in the mesopelagic) of the biological pump. We show that the strength and efficiency of the biological pump are dynamic and are characterized by a regime of constant and high transfer efficiency at low to moderate surface POC and a bloom regime where the height of the bloom is characterized by a weak deep biological pump and low transfer efficiency. The variability in POC attenuation length scale manifests in a clear decoupling between the strength of the shallow biological pump (e.g., POC at the export depth) and the strength of the deep biological pump (POC at 500 m). We suggest that the paradigm of diatom-driven export production is driven by a too restrictive perspective on upper mesopelagic dynamics. Indeed, our full mesopelagic analysis suggests that large, blooming diatoms have low transfer efficiency and thus may not export substantially to depth; rather, our analysis suggests that ecosystems characterized by smaller cells and moderately high %CaCO3 have a high mesopelagic transfer efficiency and can have higher POC concentrations in the deep mesopelagic even with relatively low surface or near-surface POC. This has negative implications for the carbon sequestration prospects of deliberate iron fertilization.

  4. Nested atmospheric inversion for the terrestrial carbon sources and sinks in China

    Directory of Open Access Journals (Sweden)

    F. Jiang

    2013-08-01

    Full Text Available In this study, we establish a nested atmospheric inversion system with a focus on China using the Bayesian method. The global surface is separated into 43 regions based on the 22 TransCom large regions, with 13 small regions in China. Monthly CO2 concentrations from 130 GlobalView sites and 3 additional China sites are used in this system. The core component of this system is an atmospheric transport matrix, which is created using the TM5 model with a horizontal resolution of 3° × 2°. The net carbon fluxes over the 43 global land and ocean regions are inverted for the period from 2002 to 2008. The inverted global terrestrial carbon sinks mainly occur in boreal Asia, South and Southeast Asia, eastern America and southern South America. Most China areas appear to be carbon sinks, with strongest carbon sinks located in Northeast China. From 2002 to 2008, the global terrestrial carbon sink has an increasing trend, with the lowest carbon sink in 2002. The inter-annual variation (IAV of the land sinks shows remarkable correlation with the El Niño Southern Oscillation (ENSO. The terrestrial carbon sinks in China also show an increasing trend. However, the IAV in China is not the same as that of the globe. There is relatively stronger land sink in 2002, lowest sink in 2006, and strongest sink in 2007 in China. This IAV could be reasonably explained with the IAVs of temperature and precipitation in China. The mean global and China terrestrial carbon sinks over the period 2002–2008 are −3.20 ± 0.63 and −0.28 ± 0.18 PgC yr−1, respectively. Considering the carbon emissions in the form of reactive biogenic volatile organic compounds (BVOCs and from the import of wood and food, we further estimate that China's land sink is about −0.31 PgC yr−1.

  5. Transfer of organic carbon through marine water columns to sediments – insights from stable and radiocarbon isotopes of lipid biomarkers

    OpenAIRE

    S. G. Wakeham; A. P. McNichol

    2014-01-01

    Compound-specific 13C and 14C compositions of diverse lipid biomarkers (fatty acids, alkenones, hydrocarbons, sterols and fatty alcohols) were measured in sinking particulate matter collected in sediment traps and from underlying surface sediments in the Black Sea, the Arabian Sea and the Ross Sea. The goal was to develop a multiparameter approach to constrain relative inputs of organic carbon (OC) from marine biomass, terrigenous vascular-plant and relict-kerogen sources. U...

  6. Fracture as a material sink

    Science.gov (United States)

    Volokh, K. Y.

    2017-12-01

    Cracks are created by massive breakage of molecular or atomic bonds. The latter, in its turn, leads to the highly localized loss of material, which is the reason why even closed cracks are visible by a naked eye. Thus, fracture can be interpreted as the local material sink. Mass conservation is violated locally in the area of material failure. We consider a theoretical formulation of the coupled mass and momenta balance equations for a description of fracture. Our focus is on brittle fracture and we propose a finite strain hyperelastic thermodynamic framework for the coupled mass-flow-elastic boundary value problem. The attractiveness of the proposed framework as compared to the traditional continuum damage theories is that no internal parameters (like damage variables, phase fields, etc.) are used while the regularization of the failure localization is provided by the physically sound law of mass balance.

  7. In situ measurement of mesopelagic particle sinking rates and the control of carbon transfer to the ocean interior during the Vertical Flux in the Global Ocean (VERTIGO) voyages in the North Pacific

    Science.gov (United States)

    Trull, T. W.; Bray, S. G.; Buesseler, K. O.; Lamborg, C. H.; Manganini, S.; Moy, C.; Valdes, J.

    2008-07-01

    Among the parameters affecting carbon transfer to the ocean interior, particle sinking rates vary three orders of magnitude and thus more than primary production, f-ratios, or particle carbon contents [e.g., Boyd, P.W., Trull, T.W., 2006. Understanding the export of marine biogenic particles: is there consensus? Progress in Oceanography 4, 276-312, doi:10.1016/j.pocean.2006.10.007]. Very few data have been obtained from the mesopelagic zone where the majority of carbon remineralization occurs and the attenuation of the sinking flux is determined. Here, we report sinking rates from ˜300 m depth for the subtropical (station ALOHA, June 2004) and subarctic (station K2, July 2005) North Pacific Ocean, obtained from short (6.5 day) deployments of an indented rotating sphere (IRS) sediment trap operating as an in situ settling column [Peterson, M.L., Wakeham, S.G., Lee, C., Askea, M.A., Miquel, J.C., 2005. Novel techniques for collection of sinking particles in the ocean and determining their settling rates. Limnology and Oceanography Methods 3, 520-532] to separate the flux into 11 sinking-rate fractions ranging from >820 to >2 m d -1 that are collected by a carousel for further analysis. Functioning of the IRS trap was tested using a novel programming sequence to check that all particles have cleared the settling column prior to the next delivery of particles by the 6-hourly rotation cycle of the IRS. There was some evidence (from the flux distribution among the cups and photomicroscopy of the collected particles) that very slow-sinking particles may have been under-collected because they were unable to penetrate the brine-filled collection cups, but good evidence for appropriate collection of fast-settling fractions. Approximately 50% of the particulate organic carbon (POC) flux was sinking at greater than 100 m d -1 at both stations. At ALOHA, more than 15% of the POC flux sank at >820 m d -1, but low fluxes make this uncertain, and precluded resolution of particles

  8. Kuwaiti oil fires—Particulate monitoring

    Science.gov (United States)

    Husain, Tahir; Amin, Mohamed B.

    The total suspended particulate (TSP) matters using a high-volume sampler and inhalable particulate matters using PM-10 samplers were collected at various locations in the Eastern Province of Saudi Arabia during and after the Kuwaiti oil fires. The collected samples were analysed for toxic metals and oil hydrocarbon concentrations including some carcinogenic organic compounds in addition to gravimetric analysis. The concentration values of particulate matters were determined on a daily basis at Dhahran. Abqaiq, Rahima, Tanajib and Jubail locations. The analyses of the filters show a high concentration of the inhalable particulate at various locations, especially when north or northwest winds were blowing. It was found that the inhalable particulate concentration exceeded the Meteorology and Environmental Protection Administration (MEPA) permissible limit of 340 μg m- 3 at most of these locations during May-October 1991. A trend between the total suspended particulate and inhalable particulate measured concurrently at the same locations was observed and a regression equation was developed to correlate PM-10 data with the total suspended particulate data.

  9. Genotoxic effects and oxidative stress induced by organic extracts of particulate matter(PM 10)collected from a subway tunnel in Seoul, Korea.

    Science.gov (United States)

    Jung, Mi Hyun; Kim, Ha Ryong; Park, Yong Joo; Park, Duck Shin; Chung, Kyu Hyuck; Oh, Seung Min

    2012-12-12

    Particulate matter (PM) has become an important health risk factor in our society. PM can easily deposit in the bronchi and lungs, causing diverse diseases such as respiratory infections, lung cancers and cardiovascular diseases. In recent days, more and more toxicological studies have been dealing with air particles in distinctive areas including industrial areas, transportation sites, or indoors. Studies on subway PM in particular, have been recognizing PM as an important health risk factor because many people use subways as a major mode of public transportation (4 million people a day in Korea). The main aim of the present study was to evaluate the genotoxic effects of organic extract (OE) of subway PM10 and potential attribution of PAHs to these effects. Particles were collected in the subway tunnel at Kil-eum station(Line 4) for one month and then extracted with Dichloromethane (DCM). Chinese Hamster Ovary cells(CHO-K1) and human normal bronchial cells (BEAS-2B) were exposed to OE, and MN and Comet assays were conducted to analyze the genotoxicity. The results showed that OE increased DNA or chromosome damages in both cell lines. In the modified Comet assay and MN assay with free radical scavengers, we confirmed that the genotoxic effect of OE was partially due to the oxidative damage on DNA. DCFHD Aassay also indicated that OE induced ROS generation in BEAS-2B cells. PAHs [benzo(a)anthracene,benzo(k)fluoranthrene, etc.], the most well-known carcinogens in polluted air, were detected in Kil-eum PM10. In conclusion, our findings confirmed that OE of subway PM10 has genotoxic effects on normal human lung cells, and oxidative stress could be one of the major mechanisms of these genotoxic effects.In addition, some genotoxic and carcinogenic PAHs were detected in OE by GC/MS/MS, even though PAHs level was not enough to increase CYP1A1 gene. Therefore, we suggest that additive or synergistic effects by unidentified chemicals as well as PAHs contained in OE of subway

  10. Source to sink transport and regulation by environmental factors

    Directory of Open Access Journals (Sweden)

    Remi eLemoine

    2013-07-01

    Full Text Available Source-to-sink transport of sugar is one of the major determinants of plant growth and relies on the efficient and controlled distribution of sucrose (and some other sugars such as raffinose and polyols across plant organs through the phloem. However, sugar transport through the phloem can be affected by many environmental factors that alter source/sink relationships. In this paper, we summarize current knowledge about the phloem transport mechanisms and review the effects of several abiotic (water and salt stress, mineral deficiency, CO2, light, temperature, air and soil pollutants and biotic (mutualistic and pathogenic microbes, viruses, aphids and parasitic plants factors. Concerning abiotic constraints, alteration of the distribution of sugar among sinks is often reported, with some sinks as roots favoured in case of mineral deficiency. Many of these constraints impair the transport function of the phloem but the exact mechanisms are far from being completely known. Phloem integrity can be disrupted (e.g. by callose deposition and under certain conditions, phloem transport is affected, earlier than photosynthesis. Photosynthesis inhibition could result from the increase in sugar concentration due to phloem transport decrease. Biotic interactions (aphids, fungi, viruses… also affect crop plant productivity. Recent breakthroughs have identified some of the sugar transporters involved in these interactions on the host and pathogen sides. The different data are discussed in relation to the phloem transport pathways. When possible, the link with current knowledge on the pathways at the molecular level will be highlighted.

  11. Characterization of Hop-and-Sink Locomotion of Water Fleas

    Science.gov (United States)

    Skipper, A. N.; Murphy, D. W.; Webster, D. R.

    2017-11-01

    The freshwater crustacean Daphnia magna is a widely studied zooplankton in relation to food webs, predator-prey interactions, and other biological/ecological considerations; however, their locomotion is poorly quantified and understood. These water fleas utilize a hop-and-sink mechanism that consists of making quick, impulsive jumps by beating their antennae to propel themselves forward (roughly 1 body length). The animals then sink for a period, during which they stretch out their antennae to increase drag and thereby reduce their sinking velocity. Time-resolved three-dimensional flow fields surrounding the animals were quantified with a unique infrared tomographic particle image velocimetry (tomo-PIV) system. Three-dimensional kinematics data were also extracted from the image sequences. In the current work, we compared body kinematics and flow disturbance among organisms of size in the range of 1.3 to 2.8 mm. The stroke cycle averaged 150 +/- 20 ms, with each stroke cycle split nearly evenly between power and recovery strokes. The kinematics data collapsed onto a self-similar curve when properly nondimensionalized, and a general trend was shown to exist between the nondimensionalized peak body speed and body length. The fluid flow induced by each antennae consisted of a viscous vortex ring that demonstrated a slow decay in the wake. The viscous dissipation showed no clear dependence on body size, whereas the volume of fluid exceeding 5 mm/s (the speed near the sinking speed of the animal) decayed more slowly with increasing body size.

  12. Causes of sinks near Tucson, Arizona, USA

    Science.gov (United States)

    Hoffmann, J.P.; Pool, D.R.; Konieczki, A.D.; Carpenter, M.C.

    1998-01-01

    Land subsidence in the form of sinks has occurred on and near farmlands near Tucson, Pima County, Arizona, USA. The sinks occur in alluvial deposits along the flood plain of the Santa Cruz River, and have made farmlands dangerous and unsuitable for farming. More than 1700 sinks are confined to the flood plain of the Santa Cruz River and are grouped along two north-northwestward-trending bands that are approximately parallel to the river and other flood-plain drainages. An estimated 17,000 m3 of sediment have been removed in the formation of the sinks. Thirteen trenches were dug to depths of 4-6 m to characterize near-surface sediments in sink and nonsink areas. Sediments below about 2 m included a large percentage of dispersive clays in sink areas. Sediments in nonsink areas contain a large component of medium- to coarse-grained, moderately to well sorted sand that probably fills a paleochannel. Electromagnetic surveys support the association of silts and clays in sink areas that are highly electrically conductive relative to sand in nonsink areas. Sinks probably are caused by the near-surface process of subsurface erosion of dispersive sediments along pre-existing cracks in predominantly silt and clay sediments. The pre-existing cracks probably result from desiccation or tension that developed during periods of water-table decline and channel incision during the past 100 years or in earlier periods.

  13. Forest carbon sinks in the Northern Hemisphere

    Science.gov (United States)

    Christine L. Goodale; Michael J. Apps; Richard A. Birdsey; Christopher B. Field; Linda S. Heath; Richard A. Houghton; Jennifer C. Jenkins; Gundolf H. Kohlmaier; Werner Kurz; Shirong Liu; Gert-Jan Nabuurs; Sten Nilsson; Anatoly Z. Shvidenko

    2002-01-01

    There is general agreement that terrestrial systems in the Northern Hemisphere provide a significant sink for atmospheric CO2; however, estimates of the magnitude and distribution of this sink vary greatly. National forest inventories provide strong, measurement-based constraints on the magnitude of net forest carbon uptake. We brought together...

  14. Ocean Acidification-Induced Restructuring of the Plankton Food Web Can Influence the Degradation of Sinking Particles

    Directory of Open Access Journals (Sweden)

    Paul Stange

    2018-04-01

    Full Text Available Ocean acidification (OA is expected to alter plankton community structure in the future ocean. This, in turn, could change the composition of sinking organic matter and the efficiency of the biological carbon pump. So far, most OA experiments involving entire plankton communities have been conducted in meso- to eutrophic environments. However, recent studies suggest that OA effects may be more pronounced during prolonged periods of nutrient limitation. In this study, we investigated how OA-induced changes in low-nutrient adapted plankton communities of the subtropical North Atlantic Ocean may affect particulate organic matter (POM standing stocks, POM fluxes, and POM stoichiometry. More specifically, we compared the elemental composition of POM suspended in the water column to the corresponding sinking material collected in sediment traps. Three weeks into the experiment, we simulated a natural upwelling event by adding nutrient-rich deep-water to all mesocosms, which induced a diatom-dominated phytoplankton bloom. Our results show that POM was more efficiently retained in the water column in the highest CO2 treatment levels (>800 μatm pCO2 subsequent to this bloom. We further observed significantly lower C:N and C:P ratios in post-bloom sedimented POM in the highest CO2 treatments, suggesting that degradation processes were less pronounced. This trend is most likely explained by differences in micro- and mesozooplankton abundance during the bloom and post-bloom phase. Overall, this study shows that OA can indirectly alter POM fluxes and stoichiometry in subtropical environments through changes in plankton community structure.

  15. Carbon storage in soil: how different land uses affect particulate organic matter composition. A molecular approach using nuclear magnetic resonance spectroscopy.

    Science.gov (United States)

    Panettieri, Marco; Courtier-Murias, Denis; Rumpel, Cornelia; Dignac, Marie-France; Doumert, Bertrand; Chabbi, Abad

    2017-04-01

    The future soil carbon stocks in a climate change scenario is being closely monitored. However, the huge edaphoclimatic variability impedes to disclose the mechanisms which underlie the cycle of accumulation/mineralization of soil organic matter (SOM). Soil environment could be described as a complex three phases matrix in which gases, liquids, and solids are not uniformly mixed, and in which microbes, fungi, vegetal residues, and roots are continuously interacting with the soil matrix and with each other. Molecular analyses on soil samples are crucial to estimate how stable those pools are and to predict which practices may accumulate larger C stocks. However, the study of land use impact through molecular characterization of a complex mixture like SOM is a challenge that requires a multidisciplinary approach. The present study applied a combination of soil physical fractionation (separation by density of the particulate organic matter (POM) within water stable aggregate fractions) followed by nuclear magnetic resonance (NMR) spectroscopy as a way to overcome spatial variability and to quantify the changes in the composition of SOM induced by land-use changes. The objective of the study was to assess, at a molecular level, the impact of different land managements, i.e. the introduction of temporary (ley) grassland into cropping cycles, on the chemical composition of SOM. Soil samples were collected at the long-term experimental observatory in Lusignan (http://www.soere-acbb.com/), in which control plots under permanent grassland, permanent cropland, and bare fallow are part of the experiment. To improve the signal-to-noise ratio (especially in the aromatic-C region), samples were analyzed using a ramped cross polarization-single pulse/magic angle spinning (CPSP/MAS) experiment. Peak integrals of different spectral regions (indicating different compound classes) were compared between treatments and two different molecular mixing models, calibrated against standard

  16. Complexity analysis in particulate matter measurements

    Directory of Open Access Journals (Sweden)

    Luciano Telesca

    2011-09-01

    Full Text Available We investigated the complex temporal fluctuations of particulate matter data recorded in London area by using the Fisher-Shannon (FS information plane. In the FS plane the PM10 and PM2.5 data are aggregated in two different clusters, characterized by different degrees of order and organization. This results could be related to different sources of the particulate matter.

  17. Ocean carbon sinks and international climate policy

    International Nuclear Information System (INIS)

    Rehdanz, Katrin; Tol, Richard S.J.; Wetzel, Patrick

    2006-01-01

    Terrestrial vegetation sinks have entered the Kyoto Protocol as offsets for anthropogenic greenhouse gas emissions, but ocean sinks have escaped attention. Ocean sinks are as unexplored and uncertain as were the terrestrial sinks at the time of negotiation of the Kyoto Protocol. It is not unlikely that certain countries will advocate the inclusion of ocean carbon sinks to reduce their emission reduction obligations in post-2012 negotiations. We use a simple model of the international market for carbon dioxide emissions to evaluate who would gain or loose from allowing for ocean carbon sinks. Our analysis is restricted to information on anthropogenic carbon sequestration within the exclusive economic zone of a country. We use information on the actual carbon flux and derive the human-induced uptake for the period from 1990 onwards. Like the carbon sequestration of business as usual forest management activities, natural ocean carbon sequestration applies at zero costs. The total amount of anthropogenic ocean carbon sequestration is large, also in the exclusive economic zones. As a consequence, it substantially alters the costs of emission reduction for most countries. Countries such as Australia, Denmark, France, Iceland, New Zealand, Norway and Portugal would gain substantially, and a large number of countries would benefit too. Current net exporters of carbon permits, particularly Russia, would gain less and oppose the inclusion of ocean carbon sinks

  18. Anaerobic nitrogen turnover by sinking diatom aggregates at varying ambient oxygen levels

    DEFF Research Database (Denmark)

    Stief, Peter; Kamp, Anja; Thamdrup, Bo

    2016-01-01

    nitrate supply. Sinking diatom aggregates can contribute directly to fixed-nitrogen loss in low-oxygen environments in the ocean and vastly expand the ocean volume in which anaerobic nitrogen turnover is possible, despite relatively high ambient oxygen levels. Depending on the extent of intracellular......In the world’s oceans, even relatively low oxygen levels inhibit anaerobic nitrogen cycling by free-living microbes. Sinking organic aggregates, however, might provide oxygen-depleted microbial hotspots in otherwise oxygenated surface waters. Here, we show that sinking diatom aggregates can host...

  19. Global Particulate Matter Source Apportionment

    Science.gov (United States)

    Lamancusa, C.; Wagstrom, K.

    2017-12-01

    As our global society develops and grows it is necessary to better understand the impacts and nuances of atmospheric chemistry, in particular those associated with atmospheric particulate matter. We have developed a source apportionment scheme for the GEOS-Chem global atmospheric chemical transport model. While these approaches have existed for several years in regional chemical transport models, the Global Particulate Matter Source Apportionment Technology (GPSAT) represents the first incorporation into a global chemical transport model. GPSAT runs in parallel to a standard GEOS-Chem run. GPSAT uses the fact that all molecules of a given species have the same probability of undergoing any given process as a core principle. This allows GPSAT to track many different species using only the flux information provided by GEOS-Chem's many processes. GPSAT accounts for the change in source specific concentrations as a result of aqueous and gas-phase chemistry, horizontal and vertical transport, condensation and evaporation on particulate matter, emissions, and wet and dry deposition. By using fluxes, GPSAT minimizes computational cost by circumventing the computationally costly chemistry and transport solvers. GPSAT will allow researchers to address many pertinent research questions about global particulate matter including the global impact of emissions from different source regions and the climate impacts from different source types and regions. For this first application of GPSAT, we investigate the contribution of the twenty largest urban areas worldwide to global particulate matter concentrations. The species investigated include: ammonium, nitrates, sulfates, and the secondary organic aerosols formed by the oxidation of benzene, isoprene, and terpenes. While GPSAT is not yet publically available, we will incorporate it into a future standard release of GEOS-Chem so that all GEOS-Chem users will have access to this new tool.

  20. Impacts of a heavy storm of rain upon dissolved and particulate organic C, N and P in the main river of a vegetation-rich basin area in Japan.

    Science.gov (United States)

    Li, Fusheng; Yuasa, Akira; Muraki, Yuzo; Matsui, Yoshihiko

    2005-06-01

    The impacts of a heavy storm of rain upon the dissolved and particulate organic matter (OM), nitrogen (N) and phosphorus (P) in the main river of the vegetation-rich Nagara River basin were investigated using water samples collected along the river line during a critical typhoon-induced heavy rain storm event. Besides, based on a high performance size-exclusion chromatography (HPSEC) system, the variance of dissolved OM (DOM) in its molecular weight (MW) characteristics was also assessed. From the MW standpoint, DOM components merged into the river along the river line resembled those present in its headwater. The MW range changed only slightly from 1010 to 5900 at the upstream (US), to 1130-5900 and 1200-5900 Da at the midstream (MS) and downstream (DS), respectively, while the corresponding weight-averaged MW (M(w)) decreased from 3669 to 3330 and 2962 Da. The heavy storm of rain enhanced the content of DOM; however, apart from a small larger-MW fraction (about 5900-6800 Da), the newly emerged DOM constituents exhibited an MW range similar to those existed before the storm. Due also to the storm of rain, total P and N (TP and TN) changed markedly in the ranges of 6.6-11.9, 8.3-40.6 and 48.4-231.3 microg/l for TP, and 145.4-296.0, 502.2-1168.7 and 1342.7-1927.3 microg/l for TN at the US, MS and DS, respectively. The larger values of TP and TN generally appeared for samples at elevated river water levels. The enhanced presence of P was found largely attributed to its particulate form; while, for N, the contribution from its dissolved form was significant. The newly emerged suspended particles via the storm-water contained lower content of OM, N and P, and a general decreasing trend of the particulate OM, N and P along the river line was also confirmed. The C/N ratio in the dissolved form varied in 0.7-6.7 and decreased downstream, while, that in the particulate form 2.3-17.3. Suspended particles that emerged in the river water during the storm exhibited larger C

  1. Effect of type and concentration of ballasting particles on sinking rate of marine snow produced by the Appendicularian Oikopleura dioica

    DEFF Research Database (Denmark)

    Lombard, Fabien; Guidi, L.; Kiørboe, Thomas

    2013-01-01

    Ballast material (organic, opal, calcite, lithogenic) is suggested to affect sinking speed of aggregates in the ocean. Here, we tested this hypothesis by incubating appendicularians in suspensions of different algae or Saharan dust, and observing the sinking speed of the marine snow formed...... by their discarded houses. We show that calcite increases the sinking speeds of aggregates by ~100% and lithogenic material by ~150% while opal only has a minor effect. Furthermore the effect of ballast particle concentration was causing a 33 m d-1 increase in sinking speed for a 5×105 μm3 ml-1 increase in particle...

  2. Contributions of biomass/biofuel burning to organic aerosols and particulate matter in Tanzania, East Africa, based on analyses of ionic species, organic and elemental carbon, levoglucosan and mannosan

    Science.gov (United States)

    Mkoma, S. L.; Kawamura, K.; Fu, P. Q.

    2013-10-01

    Atmospheric aerosol samples of PM2.5 and PM10 were collected at a rural site in Tanzania, East Africa, in 2011 during wet and dry seasons and were analysed for carbonaceous components, levoglucosan, mannosan and water-soluble inorganic ions. The contributions of biomass/biofuel burning to the organic carbon (OC) and particulate matter (PM) mass were estimated to be 46-52% and 87-13%, respectively. The mean mass concentrations of PM2.5 and PM10 were 28 ± 6 μg m-3 and 47 ± 8 μg m-3 in wet season, and 39 ± 10 μg m-3 and 61 ± 19 μg m-3 in dry season, respectively. Total carbon (TC) accounted for 16-19% of the PM2.5 mass and 13-15% of the PM10 mass. On average, 86 to 89% of TC in PM2.5 and 87 to 90% of TC in PM10 was OC, of which 67-72% and 63% was found to be water-soluble organic carbon (WSOC) in PM2.5 and PM10, respectively. We found that concentrations of levoglucosan and mannosan (specific organic tracers of pyrolysis of cellulose) well correlated with non-sea-salt potassium (nss-K+) (r2 = 0.56-0.75), OC (r2 = 0.75-0.96) and WSOC (r2 = 0.52-0.78). The K+ / OC ratios varied from 0.06 to 0.36 in PM2.5 and from 0.03 to 0.36 in PM10 with slightly higher ratios in dry season. Mean percent ratios of levoglucosan and mannosan to OC were found to be 3-4% for PM2.5 and PM10 in both seasons. We found lower levoglucosan / K+ ratios and higher K+ / EC (elemental carbon) ratios in the biomass-burning aerosols from Tanzania than those reported from other regions. This feature is consistent with the high levels of potassium reported in the soils of Morogoro, Tanzania, suggesting an importance of direct emission of potassium by soil resuspension although K+ is present mostly in fine particles. It is also likely that biomass burning of vegetation of Tanzania emits high levels of potassium that may be enriched in plant tissues. The present study demonstrates that emissions from mixed biomass- and biofuel-burning activities largely influence the air quality in Tanzania.

  3. Contributions of biomass/biofuel burning to organic aerosols and particulate matter in Tanzania, East Africa, based on analyses of ionic species, organic and elemental carbon, levoglucosan and mannosan

    Directory of Open Access Journals (Sweden)

    S. L. Mkoma

    2013-10-01

    Full Text Available Atmospheric aerosol samples of PM2.5 and PM10 were collected at a rural site in Tanzania, East Africa, in 2011 during wet and dry seasons and were analysed for carbonaceous components, levoglucosan, mannosan and water-soluble inorganic ions. The contributions of biomass/biofuel burning to the organic carbon (OC and particulate matter (PM mass were estimated to be 46–52% and 87–13%, respectively. The mean mass concentrations of PM2.5 and PM10 were 28 ± 6 μg m−3 and 47 ± 8 μg m−3 in wet season, and 39 ± 10 μg m−3 and 61 ± 19 μg m−3 in dry season, respectively. Total carbon (TC accounted for 16–19% of the PM2.5 mass and 13–15% of the PM10 mass. On average, 86 to 89% of TC in PM2.5 and 87 to 90% of TC in PM10 was OC, of which 67–72% and 63% was found to be water-soluble organic carbon (WSOC in PM2.5 and PM10, respectively. We found that concentrations of levoglucosan and mannosan (specific organic tracers of pyrolysis of cellulose well correlated with non-sea-salt potassium (nss-K+ (r2 = 0.56–0.75, OC (r2 = 0.75–0.96 and WSOC (r2 = 0.52–0.78. The K+ / OC ratios varied from 0.06 to 0.36 in PM2.5 and from 0.03 to 0.36 in PM10 with slightly higher ratios in dry season. Mean percent ratios of levoglucosan and mannosan to OC were found to be 3–4% for PM2.5 and PM10 in both seasons. We found lower levoglucosan / K+ ratios and higher K+ / EC (elemental carbon ratios in the biomass-burning aerosols from Tanzania than those reported from other regions. This feature is consistent with the high levels of potassium reported in the soils of Morogoro, Tanzania, suggesting an importance of direct emission of potassium by soil resuspension although K+ is present mostly in fine particles. It is also likely that biomass burning of vegetation of Tanzania emits high levels of potassium that may be enriched in plant tissues. The present study demonstrates that emissions from mixed biomass- and biofuel-burning activities largely

  4. Organic particulate matter formation at varying relative humidity using surrogate secondary and primary organic compounds with activity corrections in the condensed phase obtained using a method based on the Wilson equation

    Science.gov (United States)

    Chang, E. I.; Pankow, J. F.

    2010-06-01

    Secondary organic aerosol (SOA) formation in the atmosphere is currently often modeled using a multiple lumped "two-product" (N·2p) approach. The N·2p approach neglects: 1) variation of activity coefficient (ζi) values and mean molecular weight solid #000; color: #000;">MW in the particulate matter (PM) phase; 2) water uptake into the PM; and 3) the possibility of phase separation in the PM. This study considers these effects by adopting an (N·2p)ζpsolid #000; color: #000;">MW,ζ approach (θ is a phase index). Specific chemical structures are assigned to 25 lumped SOA compounds and to 15 representative primary organic aerosol (POA) compounds to allow calculation of ζi and solid #000; color: #000;">MW values. The SOA structure assignments are based on chamber-derived 2p gas/particle partition coefficient values coupled with known effects of structure on vapor pressure pL,io (atm). To facilitate adoption of the (N·2p)ζpsolid #000; color: #000;">MW,θ approach in large-scale models, this study also develops CP-Wilson.1 (Chang-Pankow-Wilson.1), a group-contribution ζi-prediction method that is more computationally economical than the UNIFAC model of Fredenslund et al. (1975). Group parameter values required by CP-Wilson.1 are obtained by fitting ζi values to predictions from UNIFAC. The (N·2p)ζpsolid #000; color: #000;">MW,θ approach is applied (using CP-Wilson.1) to several real α-pinene/O3 chamber cases for high reacted hydrocarbon levels (ΔHC≈400 to 1000 μg m-3) when relative humidity (RH) ≍50%. Good agreement between the chamber and predicted results is obtained using both the (N·2p)ζpsolid #000; color: #000;">MW,θ and N·2p approaches, indicating relatively small water effects under these conditions. However, for a hypothetical α-pinene/O3 case at ΔHC=30 μg m-3 and RH=50%, the (N·2p)ζpsolid #000; color: #000;">MW,θ approach predicts that water uptake will lead to an organic PM level that is more double that predicted by the N·2p

  5. Topology Optimization of Thermal Heat Sinks

    DEFF Research Database (Denmark)

    Klaas Haertel, Jan Hendrik; Engelbrecht, Kurt; Lazarov, Boyan Stefanov

    2015-01-01

    In this paper, topology optimization is applied to optimize the cooling performance of thermal heat sinks. The coupled two-dimensional thermofluid model of a heat sink cooled with forced convection and a density-based topology optimization including density filtering and projection are implemented...... in COMSOL Multiphysics. The optimization objective is to minimize the heat sink’s temperature for a prescribed pressure drop and fixed heat generation. To conduct the optimization, COMSOL’s Optimization Module with GCMMA as the optimization method is used. The implementation of this topology optimization...... approach in COMSOL Multiphysics is described in this paper and results for optimized two-dimensional heat sinks are presented. Furthermore, parameter studies regarding the effect of the prescribed pressure drop of the system on Reynolds number and realized heat sink temperature are presented and discussed....

  6. A Possible Sink for Methane on Mars

    NARCIS (Netherlands)

    Nørnberg, P.; Jensen, S. J. K.; Skibsted, J.; Jakobsen, H. J.; ten Kate, I. L.; Gunnlaugsson, H. P.; Merrison, J. P.; Finster, K.; Bak, E.; Iversen, J. J.; Kondrup, J. C.

    2014-01-01

    Mechanical simulated wind activation of mineral surfaces act as a trap for Methane through formation of covalent Si-C bonds stable up to temperatures above 250 C. This mechanism is proposed as a Methane sink on Mars.

  7. Observations of total RONO2 over the boreal forest: NOx sinks and HNO3 sources

    Directory of Open Access Journals (Sweden)

    E. C. Browne

    2013-05-01

    Full Text Available In contrast with the textbook view of remote chemistry where HNO3 formation is the primary sink of nitrogen oxides, recent theoretical analyses show that formation of RONO2 (ΣANs from isoprene and other terpene precursors is the primary net chemical loss of nitrogen oxides over the remote continents where the concentration of nitrogen oxides is low. This then increases the prominence of questions concerning the chemical lifetime and ultimate fate of ΣANs. We present observations of nitrogen oxides and organic molecules collected over the Canadian boreal forest during the summer which show that ΣANs account for ~20% of total oxidized nitrogen and that their instantaneous production rate is larger than that of HNO3. This confirms the primary role of reactions producing ΣANs as a control over the lifetime of NOx (NOx = NO + NO2 in remote, continental environments. However, HNO3 is generally present in larger concentrations than ΣANs indicating that the atmospheric lifetime of ΣANs is shorter than the HNO3 lifetime. We investigate a range of proposed loss mechanisms that would explain the inferred lifetime of ΣANs finding that in combination with deposition, two processes are consistent with the observations: (1 rapid ozonolysis of isoprene nitrates where at least ~40% of the ozonolysis products release NOx from the carbon backbone and/or (2 hydrolysis of particulate organic nitrates with HNO3 as a product. Implications of these ideas for our understanding of NOx and NOy budget in remote and rural locations are discussed.

  8. Protective coatings for commercial particulates

    DEFF Research Database (Denmark)

    Kindl, B.; Teng, Y.H.; Liu, Y.L.

    1994-01-01

    SiC/Al composites are in large-scale production with Al-Si alloy matrices. The same composites with pure Al or low Si matrices need diffusion barriers on the SiC reinforcement to control the interfacial reaction. The present paper describes various approaches taken to obtain protective coatings...... of alumina and zirconia on SiC particulates by sol-gel techniques. Aqueous and organic precursors have been used. The extent of the reaction, i.e., the Si and Al4C3 content in the matrix, was determined by differential thermal analysis and X-ray diffraction. The reaction rates of some coated particulates...... in liquid Al are decreased by as much as one order of magnitude during the first 15 min of immersion. Pretreatments of the SiC surface, the composition and thickness of the coating interphase and heat treatments of the coated materials have been studied, and are discussed in relation to their effect...

  9. Decomposition of sinking proteinaceous material during fall in the oxygen minimum zone off northern Chile

    Science.gov (United States)

    Pantoja, Silvio; Sepúlveda, Julio; González, Humberto E.

    2004-01-01

    We investigated the fate of sinking proteinaceous material in the oxygen minimum zone off northern Chile by deploying sediment traps at 30 m (base of the oxygenated layer) and 300 m (bottom of the O 2-depleted layer) during a 3-day experiment. Most of photosynthetically produced protein (82%) degraded in the top 30 m; an additional 15% decayed between 30 and 300 m, within the suboxic zone; and ca. 1% reached surface sediments at 1200 m depth. Sinking protein remained diagenetically labile in the top 300-m of the water column, as indicated by degradation indices and degradation rate constants of trap material, both characteristic of fresh material. We conclude that particulate protein degradation is not affected by the occurrence of the suboxic layer between 30 and 300 m in the water column. This conclusion is consistent with a model of degradation of particulate protein controlled by extracellular enzymatic hydrolysis and not dependent on O 2 availability. Assuming that our fall results are representative for an annual cycle and the whole oxygen minimum zone, suboxic decay of sinking protein in the oxygen minimum zone could support a production of 2 Tg N 2 yr -1, consistent with independent estimates of denitrification rates in the area.

  10. Enhancement of photocurrents due to the oxidation of water and organic compounds at BiZn2VO6 particulate thin film electrodes by treatment with a TiCl4 solution

    International Nuclear Information System (INIS)

    Liu Haimei; Imanishi, Akihito; Yang Wensheng; Nakato, Yoshihiro

    2010-01-01

    Photocurrents due to water oxidation at BiZn 2 VO 6 (E g 2.4 eV) particulate thin film electrodes were largely enhanced by pre-treatment with an aqueous TiCl 4 solution. Photocurrents for BiZn 2 VO 6 electrodes with no TiCl 4 treatment were also enhanced by the addition of organic compounds such as methanol and trimethyl amine to the aqueous electrolyte. Interestingly, such enhanced photocurrents by organic compounds were further enhanced by the TiCl 4 pre-treatment. EDAX and SEM investigations showed the formation of a flock-like TiO 2 overlayer on BiZn 2 VO 6 particles after the TiCl 4 treatment. The photocurrent enhancement by the TiCl 4 pre-treatment is thus mainly attributed to the necking effect of the flock-like TiO 2 overlayer, which facilitates the transport of photogenerated electrons within the BiZn 2 VO 6 particulate thin film electrode.

  11. Flooding and sinking of nuclear merchant ships

    International Nuclear Information System (INIS)

    Lettnin, H.K.J.; Wehowsky, P.

    1978-01-01

    In contrast to land-based power plants for ship reactors the marine environment brings up the peril of sinking. But this peril is low for nuclear ships with its high safety standard. An evaluation of casualties from 1964 - 1974 for ships>8000 GRT allows to estimate a very low sink probability for nuclear ships in the range of 10 -7 to 10 -8 p.a. In spite of this low probability a sinking cannot be excluded absolutely. Therefore passive means must be provided for sinking in deep waters: to maintain the integrity of at least one enclosure as activity barrier; to supply seawater into the safety containment for decay heat removal. For sinking in shallow waters and flooding at least one of the redundant decay heat removal systems including power supply stays operable. A mathematical tool is available for the design of flood openings of sufficient cross sections to flood the containment and to reach a pressure balance in case of postulated sinking in deep waters of any depth

  12. Airborne particulate discriminator

    Science.gov (United States)

    Creek, Kathryn Louise [San Diego, CA; Castro, Alonso [Santa Fe, NM; Gray, Perry Clayton [Los Alamos, NM

    2009-08-11

    A method and apparatus for rapid and accurate detection and discrimination of biological, radiological, and chemical particles in air. A suspect aerosol of the target particulates is treated with a taggant aerosol of ultrafine particulates. Coagulation of the taggant and target particles causes a change in fluorescent properties of the cloud, providing an indication of the presence of the target.

  13. Resilience in Source to Sink Systems: A Millennial Record of Watershed Responses to Disturbance in Loon Lake, Umpqua River Basin, Oregon

    Science.gov (United States)

    Guerrero, F. J.; Richardson, K.; Hatten, J. A.

    2017-12-01

    Small mountainous watersheds are disproportionate sources of particulate organic matter (POM) to long-term sinks like lake bottoms and the ocean. Thus, alterations in sediment routing resulting from disturbances (e.g. earthquakes, fires, and timber harvesting) have profound consequences on watershed's (biogeochemical) resilience. The assessment of these biogeochemical impacts is complicated by the episodic signal propagation along these source-to-sink systems and therefore is seldom attempted. We report on a 1500-year record of historical changes in Loon Lake, a local sedimentary sink (1.2 km2) for a 230 km2 watershed in the Oregon Coast Range. Particle size distributions and POM elemental composition (C, N) were sampled at high temporal resolution ( 3 years). Stable isotopic composition and lignin biomarkers were sampled with varying temporal resolution depending on the period analyzed: 1939-2013 (3-year resolution); 515-1939 (15-year resolution). Disturbance history in Loon Lake catchment is recorded as a sequence of event beds deposited in sharp contrast within a matrix of background sedimentation. At least 8 out of 23 event beds were associated with >8.2 magnitude earthquakes (including the 9.0 megathrust earthquake in 1700). Forest fires in 1770 and 1890 were also recorded as event beds. After 1939, event beds record the impacts of landscape destabilization due to the interaction between intense storms and timber harvesting. At the onset of each event, %C, %N, and C:N ratios increased reflecting the input of coarse POM from surficial soil horizons. Top layers bracketing event beds are rich in clays and have low %C, suggesting a deep-soil sediment source. Isotopic signatures (i.e. δ13C, δ15N) confirm the allochthony of sediment inputs during events and lignin biomarkers suggest a replacement of riparian inputs by a strong gymnosperm signal, particularly after 1945. Thus, event beds record changes in the relative importance of different sediment sources within

  14. Colloids as a sink for certain pharmaceuticals in the aquatic environment.

    Science.gov (United States)

    Maskaoui, Khalid; Zhou, John L

    2010-05-01

    The occurrence and fate of pharmaceuticals in the aquatic environment is recognized as one of the emerging issues in environmental chemistry and as a matter of public concern. Existing data tend to focus on the concentrations of pharmaceuticals in the aqueous phase, with limited studies on their concentrations in particulate phase such as sediments. Furthermore, current water quality monitoring does not differentiate between soluble and colloidal phases in water samples, hindering our understanding of the bioavailability and bioaccumulation of pharmaceuticals in aquatic organisms. In this study, an investigation was conducted into the concentrations and phase association (soluble, colloidal, suspended particulate matter or SPM) of selected pharmaceuticals (propranolol, sulfamethoxazole, meberverine, thioridazine, carbamazepine, tamoxifen, indomethacine, diclofenac, and meclofenamic acid) in river water, effluents from sewage treatment works (STW), and groundwater in the UK. The occurrence and phase association of selected pharmaceuticals propranolol, sulfamethoxazole, meberverine, thioridazine, carbamazepine, tamoxifen, indomethacine, diclofenac, and meclofenamic acid in contrasting aquatic environments (river, sewage effluent, and groundwater) were studied. Colloids were isolated by cross-flow ultrafiltration (CFUF). Water samples were extracted by solid-phase extraction (SPE), while SPM was extracted by microwave. All sample extracts were analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) in the multiple reaction monitoring. Five compounds propranolol, sulfamethoxazole, carbamazepine, indomethacine, and diclofenac were detected in all samples, with carbamazepine showing the highest concentrations in all phases. The highest concentrations of these compounds were detected in STW effluents, confirming STW as a key source of these compounds in the aquatic environments. The calculation of partition coefficients of pharmaceuticals between SPM and

  15. Factors influencing particulate lipid production in the East Atlantic Ocean

    Science.gov (United States)

    Gašparović, B.; Frka, S.; Koch, B. P.; Zhu, Z. Y.; Bracher, A.; Lechtenfeld, O. J.; Neogi, S. B.; Lara, R. J.; Kattner, G.

    2014-07-01

    Extensive analyses of particulate lipids and lipid classes were conducted to gain insight into lipid production and related factors along the biogeochemical provinces of the Eastern Atlantic Ocean. Data are supported by particulate organic carbon (POC), chlorophyll a (Chl a), phaeopigments, Chl a concentrations and carbon content of eukaryotic micro-, nano- and picophytoplankton, including cell abundances for the latter two and for cyanobacteria and prokaryotic heterotrophs. We focused on the productive ocean surface (2 m depth and deep Chl a maximum (DCM). Samples from the deep ocean provided information about the relative reactivity and preservation potential of particular lipid classes. Surface and DCM particulate lipid concentrations (3.5-29.4 μg L-1) were higher than in samples from deep waters (3.2-9.3 μg L-1) where an increased contribution to the POC pool was observed. The highest lipid concentrations were measured in high latitude temperate waters and in the North Atlantic Tropical Gyral Province (13-25°N). Factors responsible for the enhanced lipid synthesis in the eastern Atlantic appeared to be phytoplankton size (micro, nano, pico) and the low nutrient status with microphytoplankton having the most expressed influence in the surface and eukaryotic nano- and picophytoplankton in the DCM layer. Higher lipid to Chl a ratios suggest enhanced lipid biosynthesis in the nutrient poorer regions. The various lipid classes pointed to possible mechanisms of phytoplankton adaptation to the nutritional conditions. Thus, it is likely that adaptation comprises the replacement of membrane phospholipids by non-phosphorus containing glycolipids under low phosphorus conditions. The qualitative and quantitative lipid compositions revealed that phospholipids were the most degradable lipids, and their occurrence decreased with increasing depth. In contrast, wax esters, possibly originating from zooplankton, survived downward transport probably due to the fast sinking

  16. Sink Potential of Canadian Agricultural Soils

    International Nuclear Information System (INIS)

    Boehm, M.; Junkins, B.; Desjardins, R.; Lindwall, W.; Kulshreshtha, S.

    2004-01-01

    Net greenhouse gas (GHG) emissions from Canadian crop and livestock production were estimated for 1990, 1996 and 2001 and projected to 2008. Net emissions were also estimated for three scenarios (low (L), medium (M) and high (H)) of adoption of sink enhancing practices above the projected 2008 level. Carbon sequestration estimates were based on four sink-enhancing activities: conversion from conventional to zero tillage (ZT), reduced frequency of summerfallow (SF), the conversion of cropland to permanent cover crops (PC), and improved grazing land management (GM). GHG emissions were estimated with the Canadian Economic and Emissions Model for Agriculture (CEEMA). CEEMA estimates levels of production activities within the Canadian agriculture sector and calculates the emissions and removals associated with those levels of activities. The estimates indicate a decline in net emissions from 54 Tg CO2-Eq yr-1 in 1990 to 52 Tg CO2-Eq yr-1 in 2008. Adoption of the sink-enhancing practices above the level projected for 2008 resulted in further declines in emissions to 48 Tg CO2-Eq yr-1 (L), 42 Tg CO2-Eq yr-1 (M) or 36 Tg CO2-Eq yr-1 (H). Among the sink-enhancing practices, the conversion from conventional tillage to ZT provided the largest C sequestration potential and net reduction in GHG emissions among the scenarios. Although rates of C sequestration were generally higher for conversion of cropland to PC and adoption of improved GM, those scenarios involved smaller areas of land and therefore less C sequestration. Also, increased areas of PC were associated with an increase in livestock numbers and CH4 and N2O emissions from enteric fermentation and manure, which partially offset the carbon sink. The CEEMA estimates indicate that soil C sinks are a viable option for achieving the UNFCCC objective of protecting and enhancing GHG sinks and reservoirs as a means of reducing GHG emissions (UNFCCC, 1992)

  17. Longevity of terrestrial Carbon sinks: effects of soil degradation on greenhouse gas emissions

    Science.gov (United States)

    Kuhn, Nikolaus J.; Berger, Samuel; Kuonen, Samuel

    2013-04-01

    Soil erosion by water is a key process of soil and land degradation. In addition, significant amounts of nutrients and organic Carbon are moved from eroding source areas to landscape sinks. As a consequence, areas affected by erosion suffer a loss of fertility, while sinks experience the development of a stockpile of the deposited sediment, including soil organic matter and nutrients. The deposited nutrients are largely unavailable for the plants growing in these landscape sediment sinks once the thickness of the deposited layer is greater than the rooting depth of the plants. In addition, the deposited organic matter is decomposed slowly through the pack of sediment. At sites of erosion, nutrients have to be replaced and organic matter content of the soil declines due to a destruction of the A horizon. Over time, the risk of a significant reduction in productivity, for example caused by a loss of top soil with a sufficient water storage capacity for maximum plant growth, leads to a decline in CO2 uptake by photosynthesis. Soil organic matter at eroding sites therefore declines and consequently the sediment that is moved to landscape sinks also has a smaller organic matter content than sediment generated from the non-degraded soil. The sediment sinks, on the other hand, emit an increasing amount of greenhouse gases as a consequence of the increasing amount of organic matter deposited while the upslope area is eroded. Over time, the perceived sink effect of soil erosion for greenhouse gases is therefore replaced with a neutral or positive emission balance of erosion in agricultural landscapes. Such a switch from none or a negative emission balance of agricultural landscapes to a positive balance carries the risk of accelerating climate change. In this study, we tried to estimate the risk associated with ongoing soil degradation and closing landscape soil organic matter sinks. Currently observed global erosion rates were linked to known limitations of soil

  18. Landfills as sinks for (hazardous) substances.

    Science.gov (United States)

    Scharff, Heijo

    2012-12-01

    The primary goal of waste regulations is to protect human health and the environment. This requires the removal from the material cycle of those materials that cannot be processed without harm. Policies to promote recycling hold a risk that pollutants are dispersed. Materials have an environmental impact during their entire life cycle from extraction through production, consumption and recycling to disposal. Essentially there are only two routes for pollutants that cannot be rendered harmless: storage in sinks or dispersion into the environment. Many sinks do not contain substances absolutely, but result in slow dispersion. Dispersion leads to exposure and impact to human health and the environment. It is therefore important to assess the impact of the release to the environment. Based on various sources this paper discusses important material flows and their potential impact. This is compared with the intentions and achievements of European environmental and resource policy. The polluter pays principle is being implemented in Europe, but lags behind implementation of waste management regulations. As long as producers are allowed to add hazardous substances to their products and don't take their products back, it is in society's best interest to carefully consider whether recycling or storage in a sink is the better solution. This requires further development of life-cycle assessment tools and harmonization of regulations. In many cases the sink is unavoidable. Landfills as sinks will be needed in the future. Fail-safe design and construction as well as sustainable management of landfills must be further developed.

  19. Experimental investigation of inserts configurations and PCM type on the thermal performance of PCM based heat sinks

    International Nuclear Information System (INIS)

    Mahmoud, Saad; Tang, Aaron; Toh, Chin; AL-Dadah, Raya; Soo, Sein Leung

    2013-01-01

    Highlights: • Inclusion of PCM can reduce heating rate and peak temperatures of the heat sinks. • Increasing the number of fins can enhance heat transfer to PCM. • Honeycomb inserts can replace machined fin structures in PCM based heat sinks. • PCMs with lower melting points produced lower heat sink operating temperatures. - Abstract: Efficient thermal management in portable electronic devices is necessary to ensure sufficiently low operating temperatures for reliability, increased installed functions, and user comfort. Using Phase Change Materials (PCMs) based heat sinks offers potential in these applications. However, PCMs generally suffer from low thermal conductivities; therefore it is important to enhance their thermal conductivity and improve cooling performance. This study presents experimental investigation of the effects of PCM material, heat sink designs and power levels on PCM based heat sinks performance for cooling electronic devices. Six PCMs were used including paraffin wax (as reference material), two materials based on mixture of inorganic hydrated salts, two materials based on mixture of organic substances and one material based on a mixture of both organic and inorganic materials. Also, six heat sink designs were tested: one with single cavity, two with parallel fin arrangement, two with cross fin arrangement, and one with honeycomb insert inside the single cavity. Heat sinks thermal performance was investigated using paraffin wax type PCM with power inputs ranging from 3 W to 5 W. Results showed that the inclusion of PCM can reduce heating rates and peak temperatures of heat sinks with increasing the number of fins can enhance heat distribution to PCM leading to lower heat sinks peak temperatures. Also, the use of honeycomb inserts to replace machined finned structures has shown comparable thermal performance. Regarding the PCM type, the material with the lowest melting temperature has shown the best performance in terms of lowest

  20. Organic particulate matter formation at varying relative humidity using surrogate secondary and primary organic compounds with activity corrections in the condensed phase obtained using a method based on the Wilson equation

    Directory of Open Access Journals (Sweden)

    E. I. Chang

    2010-06-01

    Full Text Available Secondary organic aerosol (SOA formation in the atmosphere is currently often modeled using a multiple lumped "two-product" (N·2p approach. The N·2p approach neglects: 1 variation of activity coefficient (ζi values and mean molecular weight MW in the particulate matter (PM phase; 2 water uptake into the PM; and 3 the possibility of phase separation in the PM. This study considers these effects by adopting an (N·2pζpMW,ζ approach (θ is a phase index. Specific chemical structures are assigned to 25 lumped SOA compounds and to 15 representative primary organic aerosol (POA compounds to allow calculation of ζi and MW values. The SOA structure assignments are based on chamber-derived 2p gas/particle partition coefficient values coupled with known effects of structure on vapor pressure pL,io (atm. To facilitate adoption of the (N·2pζpMW,θ approach in large-scale models, this study also develops CP-Wilson.1 (Chang-Pankow-Wilson.1, a group-contribution ζi-prediction method that is more computationally economical than the UNIFAC model of Fredenslund et al. (1975. Group parameter values required by CP-Wilson.1 are obtained by fitting ζi values to predictions from UNIFAC. The (N·2pζpMW,θ approach is applied (using CP-Wilson.1 to several real α-pinene/O3 chamber cases for high reacted hydrocarbon levels (ΔHC≈400 to 1000 μg m−3 when relative humidity (RH ≈50%. Good agreement between the chamber and predicted results is

  1. Particulate emissions from biodiesel fuelled CI engines

    International Nuclear Information System (INIS)

    Agarwal, Avinash Kumar; Gupta, Tarun; Shukla, Pravesh C.; Dhar, Atul

    2015-01-01

    Highlights: • Physical and chemical characterization of biodiesel particulates. • Toxicity of biodiesel particulate due to EC/OC, PAHs and BTEX. • Trace metals and unregulated emissions from biodiesel fuelled diesel engines. • Influence of aftertreatment devices and injection strategy on biodiesel particulates. • Characterization of biodiesel particulate size-number distribution. - Abstract: Compression ignition (CI) engines are the most popular prime-movers for transportation sector as well as for stationary applications. Petroleum reserves are rapidly and continuously depleting at an alarming pace and there is an urgent need to find alternative energy resources to control both, the global warming and the air pollution, which is primarily attributed to combustion of fossil fuels. In last couple of decades, biodiesel has emerged as the most important alternative fuel candidate to mineral diesel. Numerous experimental investigations have confirmed that biodiesel results in improved engine performance, lower emissions, particularly lower particulate mass emissions vis-à-vis mineral diesel and is therefore relatively more environment friendly fuel, being renewable in nature. Environmental and health effects of particulates are not simply dependent on the particulate mass emissions but these change depending upon varying physical and chemical characteristics of particulates. Particulate characteristics are dependent on largely unpredictable interactions between engine technology, after-treatment technology, engine operating conditions as well as fuel and lubricating oil properties. This review paper presents an exhaustive summary of literature on the effect of biodiesel and its blends on exhaust particulate’s physical characteristics (such as particulate mass, particle number-size distribution, particle surface area-size distribution, surface morphology) and chemical characteristics (such as elemental and organic carbon content, speciation of polyaromatic

  2. Influence of plankton community structure on the sinking velocity of marine aggregates

    Science.gov (United States)

    Bach, L. T.; Boxhammer, T.; Larsen, A.; Hildebrandt, N.; Schulz, K. G.; Riebesell, U.

    2016-08-01

    About 50 Gt of carbon is fixed photosynthetically by surface ocean phytoplankton communities every year. Part of this organic matter is reprocessed within the plankton community to form aggregates which eventually sink and export carbon into the deep ocean. The fraction of organic matter leaving the surface ocean is partly dependent on aggregate sinking velocity which accelerates with increasing aggregate size and density, where the latter is controlled by ballast load and aggregate porosity. In May 2011, we moored nine 25 m deep mesocosms in a Norwegian fjord to assess on a daily basis how plankton community structure affects material properties and sinking velocities of aggregates (Ø 80-400 µm) collected in the mesocosms' sediment traps. We noted that sinking velocity was not necessarily accelerated by opal ballast during diatom blooms, which could be due to relatively high porosity of these rather fresh aggregates. Furthermore, estimated aggregate porosity (Pestimated) decreased as the picoautotroph (0.2-2 µm) fraction of the phytoplankton biomass increased. Thus, picoautotroph-dominated communities may be indicative for food webs promoting a high degree of aggregate repackaging with potential for accelerated sinking. Blooms of the coccolithophore Emiliania huxleyi revealed that cell concentrations of 1500 cells/mL accelerate sinking by about 35-40%, which we estimate (by one-dimensional modeling) to elevate organic matter transfer efficiency through the mesopelagic from 14 to 24%. Our results indicate that sinking velocities are influenced by the complex interplay between the availability of ballast minerals and aggregate packaging; both of which are controlled by plankton community structure.

  3. Programming Saposin-Mediated Compensatory Metabolic Sinks for Enhanced Ubiquinone Production.

    Science.gov (United States)

    Xu, Wen; Yuan, Jifeng; Yang, Shuiyun; Ching, Chi-Bun; Liu, Jiankang

    2016-12-16

    Microbial synthesis of ubiquinone by fermentation processes has been emerging in recent years. However, as ubiquinone is a primary metabolite that is tightly regulated by the host central metabolism, tweaking the individual pathway components could only result in a marginal improvement on the ubiquinone production. Given that ubiquinone is stored in the lipid bilayer, we hypothesized that introducing additional metabolic sink for storing ubiquinone might improve the CoQ 10 production. As human lipid binding/transfer protein saposin B (hSapB) was reported to extract ubiquinone from the lipid bilayer and form the water-soluble complex, hSapB was chosen to build a compensatory metabolic sink for the ubiquinone storage. As a proof-of-concept, hSapB-mediated metabolic sink systems were devised and systematically investigated in the model organism of Escherichia coli. The hSapB-mediated periplasmic sink resulted in more than 200% improvement of CoQ 8 over the wild type strain. Further investigation revealed that hSapB-mediated sink systems could also improve the CoQ 10 production in a CoQ 10 -hyperproducing E. coli strain obtained by a modular pathway rewiring approach. As the design principles and the engineering strategies reported here are generalizable to other microbes, compensatory sink systems will be a method of significant interest to the synthetic biology community.

  4. Reconstructing source-sink dynamics in a population with a pelagic dispersal phase.

    Directory of Open Access Journals (Sweden)

    Kun Chen

    Full Text Available For many organisms, the reconstruction of source-sink dynamics is hampered by limited knowledge of the spatial assemblage of either the source or sink components or lack of information on the strength of the linkage for any source-sink pair. In the case of marine species with a pelagic dispersal phase, these problems may be mitigated through the use of particle drift simulations based on an ocean circulation model. However, when simulated particle trajectories do not intersect sampling sites, the corroboration of model drift simulations with field data is hampered. Here, we apply a new statistical approach for reconstructing source-sink dynamics that overcomes the aforementioned problems. Our research is motivated by the need for understanding observed changes in jellyfish distributions in the eastern Bering Sea since 1990. By contrasting the source-sink dynamics reconstructed with data from the pre-1990 period with that from the post-1990 period, it appears that changes in jellyfish distribution resulted from the combined effects of higher jellyfish productivity and longer dispersal of jellyfish resulting from a shift in the ocean circulation starting in 1991. A sensitivity analysis suggests that the source-sink reconstruction is robust to typical systematic and random errors in the ocean circulation model driving the particle drift simulations. The jellyfish analysis illustrates that new insights can be gained by studying structural changes in source-sink dynamics. The proposed approach is applicable for the spatial source-sink reconstruction of other species and even abiotic processes, such as sediment transport.

  5. Ballast minerals and the sinking carbon flux in the ocean: carbon-specific respiration rates and sinking velocity of marine snow aggregates

    Directory of Open Access Journals (Sweden)

    M. H. Iversen

    2010-09-01

    Full Text Available Recent observations have shown that fluxes of ballast minerals (calcium carbonate, opal, and lithogenic material and organic carbon fluxes are closely correlated in the bathypelagic zones of the ocean. Hence it has been hypothesized that incorporation of biogenic minerals within marine aggregates could either protect the organic matter from decomposition and/or increase the sinking velocity via ballasting of the aggregates. Here we present the first combined data on size, sinking velocity, carbon-specific respiration rate, and composition measured directly in three aggregate types; Emiliania huxleyi aggregates (carbonate ballasted, Skeletonema costatum aggregates (opal ballasted, and aggregates made from a mix of both E. huxleyi and S. costatum (carbonate and opal ballasted. Overall average carbon-specific respiration rate was ~0.13 d−1 and did not vary with aggregate type and size. Ballasting from carbonate resulted in 2- to 2.5-fold higher sinking velocities than those of aggregates ballasted by opal. We compiled literature data on carbon-specific respiration rate and sinking velocity measured in aggregates of different composition and sources. Compiled carbon-specific respiration rates (including this study vary between 0.08 d−1 and 0.20 d−1. Sinking velocity increases with increasing aggregate size within homogeneous sources of aggregates. When compared across different particle and aggregate sources, however, sinking velocity appeared to be independent of particle or aggregate size. The carbon-specific respiration rate per meter settled varied between 0.0002 m−1 and 0.0030 m−1, and decreased with increasing aggregate size. It was lower for calcite ballasted aggregates as compared to that of similar sized opal ballasted aggregates.

  6. Advanced Hybrid Particulate Collector Project Management Plan

    Energy Technology Data Exchange (ETDEWEB)

    Miller, S.J.

    1995-11-01

    As the consumption of energy increases, its impact on ambient air quality has become a significant concern. Recent studies indicate that fine particles from coal combustion cause health problems as well as atmospheric visibility impairment. These problems are further compounded by the concentration of hazardous trace elements such as mercury, cadmium, selenium, and arsenic in fine particles. Therefore, a current need exists to develop superior, but economical, methods to control emissions of fine particles. Since most of the toxic metals present in coal will be in particulate form, a high level of fine- particle collection appears to be the best method of overall air toxics control. However, over 50% of mercury and a portion of selenium emissions are in vapor form and cannot be collected in particulate control devices. Therefore, this project will focus on developing technology not only to provide ultrahigh collection efficiency of particulate air toxic emissions, but also to capture vapor- phase trace metals such as mercury and selenium. Currently, the primary state-of-the-art technologies for particulate control are fabric filters (baghouses) and electrostatic precipitators (ESPs). However, they both have limitations that prevent them from achieving ultrahigh collection of fine particulate matter and vapor-phase trace metals. The objective of this project is to develop a highly reliable advanced hybrid particulate collector (AHPC) that can provide > 99.99 % particulate collection efficiency for all particle sizes between 0.01 and 50 14m, is applicable for use with all U.S. coals, and is cost-0443competitive with existing technologies. Phase I of the project is organized into three tasks: Task I - Project Management, Reporting, and Subcontract Consulting Task 2 - Modeling, Design, and Construction of 200-acfm AHPC Model Task 3 - Experimental Testing and Subcontract Consulting

  7. Predator transitory spillover induces trophic cascades in ecological sinks

    DEFF Research Database (Denmark)

    Casini, Michele; Blenckner, Thorsten; Möllmann, Christian

    2012-01-01

    Understanding the effects of cross-system fluxes is fundamental in ecosystem ecology and biological conservation. Source-sink dynamics and spillover processes may link adjacent ecosystems by movement of organisms across system boundaries. However, effects of temporal variability in these cross-sy...... in structuring natural systems. The integration of regional and local processes is central to predict species and ecosystem responses to future climate changes and ongoing anthropogenic disturbances......Understanding the effects of cross-system fluxes is fundamental in ecosystem ecology and biological conservation. Source-sink dynamics and spillover processes may link adjacent ecosystems by movement of organisms across system boundaries. However, effects of temporal variability in these cross......-system fluxes on a whole marine ecosystem structure have not yet been presented. Here we show, using 35 y of multitrophic data series from the Baltic Sea, that transitory spillover of the top-predator cod from its main distribution area produces cascading effects in the whole food web of an adjacent and semi...

  8. Advanced Fine Particulate Characterization Methods

    Energy Technology Data Exchange (ETDEWEB)

    Steven Benson; Lingbu Kong; Alexander Azenkeng; Jason Laumb; Robert Jensen; Edwin Olson; Jill MacKenzie; A.M. Rokanuzzaman

    2007-01-31

    The characterization and control of emissions from combustion sources are of significant importance in improving local and regional air quality. Such emissions include fine particulate matter, organic carbon compounds, and NO{sub x} and SO{sub 2} gases, along with mercury and other toxic metals. This project involved four activities including Further Development of Analytical Techniques for PM{sub 10} and PM{sub 2.5} Characterization and Source Apportionment and Management, Organic Carbonaceous Particulate and Metal Speciation for Source Apportionment Studies, Quantum Modeling, and High-Potassium Carbon Production with Biomass-Coal Blending. The key accomplishments included the development of improved automated methods to characterize the inorganic and organic components particulate matter. The methods involved the use of scanning electron microscopy and x-ray microanalysis for the inorganic fraction and a combination of extractive methods combined with near-edge x-ray absorption fine structure to characterize the organic fraction. These methods have direction application for source apportionment studies of PM because they provide detailed inorganic analysis along with total organic and elemental carbon (OC/EC) quantification. Quantum modeling using density functional theory (DFT) calculations was used to further elucidate a recently developed mechanistic model for mercury speciation in coal combustion systems and interactions on activated carbon. Reaction energies, enthalpies, free energies and binding energies of Hg species to the prototype molecules were derived from the data obtained in these calculations. Bimolecular rate constants for the various elementary steps in the mechanism have been estimated using the hard-sphere collision theory approximation, and the results seem to indicate that extremely fast kinetics could be involved in these surface reactions. Activated carbon was produced from a blend of lignite coal from the Center Mine in North Dakota and

  9. Comparison of ASE and SFE with Soxhlet, Sonication, and Methanolic Saponification Extractions for the Determination of Organic Micropollutants in Marine Particulate Matter.

    Science.gov (United States)

    Heemken, O P; Theobald, N; Wenclawiak, B W

    1997-06-01

    The methods of accelerated solvent extraction (ASE) and supercritical fluid extraction (SFE) of polycyclic aromatic hydrocarbons (PAHs), aliphatic hydrocarbons, and chlorinated hydrocarbons from marine samples were investigated. The results of extractions of a certified sediment and four samples of suspended particulate matter (SPM) were compared to classical Soxhlet (SOX), ultrasonication (USE), and methanolic saponification extraction (MSE) methods. The recovery data, including precision and systematic deviations of each method, were evaluated statistically. It was found that recoveries and precision of ASE and SFE compared well with the other methods investigated. Using SFE, the average recoveries of PAHs in three different samples ranged from 96 to 105%, for ASE the recoveries were in the range of 97-108% compared to the reference methods. Compared to the certified values of sediment HS-6, the average recoveries of SFE and ASE were 87 and 88%, most compounds being within the limits of confidence. Also, for alkanes the average recoveries by SFE and ASE were equal to the results obtained by SOX, USE, and MSE. In the case of SFE, the recoveries were in the range 93-115%, and ASE achieved recoveries of 94-107% as compared to the other methods. For ASE and SFE, the influence of water on the extraction efficiency was examined. While the natural water content of the SPM sample (56 wt %) led to insufficient recoveries in ASE and SFE, quantitative extractions were achieved in SFE after addition of anhydrous sodium sulfate to the sample. Finally, ASE was applied to SPM-loaded filter candles whereby a mixture of n-hexane/acetone as extraction solvent allowed the simultaneous determination of PAHs, alkanes, and chlorinated hydrocarbons.

  10. Carbon source-sink relationship in Arabidopsis thaliana: the role of sucrose transporters.

    Science.gov (United States)

    Durand, Mickaël; Mainson, Dany; Porcheron, Benoît; Maurousset, Laurence; Lemoine, Rémi; Pourtau, Nathalie

    2018-03-01

    The regulation of source-to-sink sucrose transport is associated with AtSUC and AtSWEET sucrose transporters' gene expression changes in plants grown hydroponically under different physiological conditions. Source-to-sink transport of sucrose is one of the major determinants of plant growth. Whole-plant carbohydrates' partitioning requires the specific activity of membrane sugar transporters. In Arabidopsis thaliana plants, two families of transporters are involved in sucrose transport: AtSUCs and AtSWEETs. This study is focused on the comparison of sucrose transporter gene expression, soluble sugar and starch levels and long distance sucrose transport, in leaves and sink organs (mainly roots) in different physiological conditions (along the plant life cycle, during a diel cycle, and during an osmotic stress) in plants grown hydroponically. In leaves, the AtSUC2, AtSWEET11, and 12 genes known to be involved in phloem loading were highly expressed when sucrose export was high and reduced during osmotic stress. In roots, AtSUC1 was highly expressed and its expression profile in the different conditions tested suggests that it may play a role in sucrose unloading in roots and in root growth. The SWEET transporter genes AtSWEET12, 13, and 15 were found expressed in all organs at all stages studied, while differential expression was noticed for AtSWEET14 in roots, stems, and siliques and AtSWEET9, 10 expressions were only detected in stems and siliques. A role for these transporters in carbohydrate partitioning in different source-sink status is proposed, with a specific attention on carbon demand in roots. During development, despite trophic competition with others sinks, roots remained a significant sink, but during osmotic stress, the amount of translocated [U- 14 C]-sucrose decreased for rosettes and roots. Altogether, these results suggest that source-sink relationship may be linked with the regulation of sucrose transporter gene expression.

  11. Migration of particulates in permeable rock columns

    International Nuclear Information System (INIS)

    Cropper, R.L.

    1982-01-01

    The migration of radioactive material through soil and permeable rock formations have become a major topic of concern due to the interest in the licensing of new radioactive waste disposal sites. Previously, research has been conducted in relation to deep repositories; however, similar situations arise in the vadose zone, where there is a higher probability of naturally-occurring particulates of organic nature and for the incursion of water. Test data has provided information which suggests that particulates will travel through porous media subject to various delay mechnisms and must be included in any consideration of waste migration. Data concerning particulate migration must and should be considered in the future when radioactive waste disposal sites are licensed

  12. Short term variations in particulate matter in Mahi river estuary

    Digital Repository Service at National Institute of Oceanography (India)

    Bhosle, N.B.; Rokade, M.A.; Zingde, M.D.

    The particulate matter (PM) collected from Mahi River Estuary was analysed for organic carbon (POC), nitrogen (PON), and chlorophyll a (Chl a). The concentration of PM, POC, PON and Chl a showed short term variations. Average surface concentration...

  13. Microwave regenerated particulate trap

    Energy Technology Data Exchange (ETDEWEB)

    McDonald, A.C. Jr.; Yonushonis, T.M. [Cummins Engine Co., Inc., Columbus, IN (United States); Haberkamp, W.C.; Mako, F.; Len, L.K,; Silberglitt, R.; Ahmed, I. [FM Technologies, Inc., Fairfax, VA (United States)

    1997-12-31

    It has been demonstrated that a fibrous particulate filter can extract particulate matter from the diesel exhaust. However, additional engineering efforts remains to achieve the design target of 90%. It has also be shown that with minor modifications magnetrons produced for home ovens can endure a simulated diesel operating environment. Much work remains to develop a robust product ready to complete extensive engine testing and evaluation. These efforts include: (1) additional environmental testing of magnetrons; (2) vibration testing of the filter in the housing; (3) evaluating alternative methods/designs to seal the center bore; and (4) determining the optimum coating thickness that provides sufficient structural integrity while maintaining rapid heating rates.

  14. Minimization of sink mark defects in injection molding process ...

    African Journals Online (AJOL)

    user

    3Institute of Remote Sensing, Anna University, Chennai-600025, INDIA .... Most of the Taguchi based studies used sink mark index or sink index as the parameter. It is an .... Maintaining higher pack pressure requires additional power and cost.

  15. Activation of the aryl hydrocarbon receptor is the major toxic mode of action of an organic extract of a reference urban dust particulate matter mixture: The role of polycyclic aromatic hydrocarbons

    International Nuclear Information System (INIS)

    Andrysik, Zdenek; Vondracek, Jan; Marvanova, Sona; Ciganek, Miroslav; Neca, Jiri; Pencikova, Katerina; Mahadevan, Brinda; Topinka, Jan; Baird, William M.; Kozubik, Alois; Machala, Miroslav

    2011-01-01

    Highlights: → SRM1649a extract and its fractions are potent activators of AhR in a model of epithelial cells. → AhR-dependent effects include both induction of CYP1 enzymes and disruption of cell proliferation control. → Polycyclic aromatic hydrocarbons present in the neutral SRM1649a fraction are major contributors to the AhR-mediated toxic effects. → Activation of AhR and related nongenotoxic effects occur at significantly lower doses than the formation of DNA adducts and activation of DNA damage response. → More attention should be paid to the AhR-dependent nongenotoxic events elicited by urban particulate matter constituents. - Abstract: Many of the toxic and carcinogenic effects of urban air pollution have been linked to polycyclic aromatic hydrocarbons (PAHs) adsorbed to airborne particulate matter (PM). The carcinogenic properties of PAHs in complex organic mixtures derived from PM have been chiefly attributed to their mutagenicity. Nevertheless, PAHs are also potent activators of the aryl hydrocarbon receptor (AhR), which may contribute to their nongenotoxic effects, including tumor promotion. As the genotoxicity of carcinogenic PAHs in complex mixtures derived from urban PM is often inhibited by other mixture constituents, the AhR-mediated activity of urban PM extracts might significantly contribute to the carcinogenic activity of such mixtures. In the present study, we used an organic extract of the urban dust standard reference material, SRM1649a, as a model mixture to study a range of toxic effects related to DNA damage and AhR activation. Both the organic extract and its neutral aromatic fraction formed a low number of DNA adducts per nucleotide in the liver epithelial WB-F344 cells model, without inducing DNA damage response, such as tumor suppressor p53 activation and apoptosis. In contrast, we found that this extract, as well as its neutral and polar fractions, were potent inducers of a range of AhR-mediated responses, including induction

  16. Subchronic effects of inhaled ambient particulate matter on glucose homeostasis and target organ damage in a type 1 diabetic rat model

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Yuan-Horng [Institute of Occupational Medicine and Industrial Hygiene, College of Public Health, National Taiwan University, Taipei, Taiwan (China); Department of Medical Research, Ditmanson Medical Foundation Chia-Yi Christian Hospital, Chiayi, Taiwan (China); Charles, Chou C.-K. [Research Center for Environmental Changes, Academia Sinica, Taipei, Taiwan (China); Wang, Jyh-Seng [Department of Pathology and Laboratory Medicine, Kaohsiung Veterans General Hospital, Kaohsiung, Taiwan (China); Tung, Chun-Liang [Department of Pathology, Ditmanson Medical Foundation Chia-Yi Christian Hospital, Chiayi, Taiwan (China); Li, Ya-Ru; Lo, Kai [Institute of Occupational Medicine and Industrial Hygiene, College of Public Health, National Taiwan University, Taipei, Taiwan (China); Cheng, Tsun-Jen, E-mail: tcheng@ntu.edu.tw [Institute of Occupational Medicine and Industrial Hygiene, College of Public Health, National Taiwan University, Taipei, Taiwan (China); Department of Public Health, College of Public Health, National Taiwan University, Taipei, Taiwan (China)

    2014-12-01

    Epidemiological studies have reported associations between particulate matter (PM) and cardiovascular effects, and diabetes mellitus (DM) patients might be susceptible to these effects. The chief chronic injuries resulting from DM are small vascular injuries (micro-vascular complications) or large blood vessel injuries (macro-vascular complications). However, toxicological data regarding the effects of PM on DM-related cardiovascular complications is limited. Our objective was to investigate whether subchronic PM exposure alters glucose homeostasis and causes cardiovascular complications in a type 1 DM rat model. We constructed a real world PM{sub 2.5} exposure system, the Taipei Air Pollution Exposure System for Health Effects (TAPES), to continuously deliver non-concentrated PM for subchronic exposure. A type 1 DM rat model was induced using streptozotocin. Between December 22, 2009 and April 9, 2010, DM rats were exposed to PM or to filtered air (FA) using TAPES in Taipei, Taiwan, 24 h/day, 7 days/week, for a total of 16 weeks. The average concentrations (mean [SD]) of PM{sub 2.5} in the exposure and control chambers of the TAPES were 13.30 [8.65] and 0.13 [0.05] μg/m{sup 3}, respectively. Glycated hemoglobin A1c (HbA1c) was significantly elevated after exposure to PM compared with exposure to FA (mean [SD], 7.7% [3.1%] vs. 4.7% [1.0%], P < 0.05). Interleukin 6 and fibrinogen levels were significantly increased after PM exposure. PM caused focal myocarditis, aortic medial thickness, advanced glomerulosclerosis, and accentuation of tubular damage of the kidney (tubular damage index: 1.76 [0.77] vs. 1.15 [0.36], P < 0.001). PM exposure might induce the macro- and micro-vascular complications in DM through chronic hyperglycemia and systemic inflammation. - Highlights: • The study demonstrated cardiovascular and renal effects of PM in a rat model of DM. • TAPES is a continuous, real world, long-term PM exposure system. • HbA1c, a marker of glycemic

  17. Subchronic effects of inhaled ambient particulate matter on glucose homeostasis and target organ damage in a type 1 diabetic rat model

    International Nuclear Information System (INIS)

    Yan, Yuan-Horng; Charles, Chou C.-K.; Wang, Jyh-Seng; Tung, Chun-Liang; Li, Ya-Ru; Lo, Kai; Cheng, Tsun-Jen

    2014-01-01

    Epidemiological studies have reported associations between particulate matter (PM) and cardiovascular effects, and diabetes mellitus (DM) patients might be susceptible to these effects. The chief chronic injuries resulting from DM are small vascular injuries (micro-vascular complications) or large blood vessel injuries (macro-vascular complications). However, toxicological data regarding the effects of PM on DM-related cardiovascular complications is limited. Our objective was to investigate whether subchronic PM exposure alters glucose homeostasis and causes cardiovascular complications in a type 1 DM rat model. We constructed a real world PM 2.5 exposure system, the Taipei Air Pollution Exposure System for Health Effects (TAPES), to continuously deliver non-concentrated PM for subchronic exposure. A type 1 DM rat model was induced using streptozotocin. Between December 22, 2009 and April 9, 2010, DM rats were exposed to PM or to filtered air (FA) using TAPES in Taipei, Taiwan, 24 h/day, 7 days/week, for a total of 16 weeks. The average concentrations (mean [SD]) of PM 2.5 in the exposure and control chambers of the TAPES were 13.30 [8.65] and 0.13 [0.05] μg/m 3 , respectively. Glycated hemoglobin A1c (HbA1c) was significantly elevated after exposure to PM compared with exposure to FA (mean [SD], 7.7% [3.1%] vs. 4.7% [1.0%], P < 0.05). Interleukin 6 and fibrinogen levels were significantly increased after PM exposure. PM caused focal myocarditis, aortic medial thickness, advanced glomerulosclerosis, and accentuation of tubular damage of the kidney (tubular damage index: 1.76 [0.77] vs. 1.15 [0.36], P < 0.001). PM exposure might induce the macro- and micro-vascular complications in DM through chronic hyperglycemia and systemic inflammation. - Highlights: • The study demonstrated cardiovascular and renal effects of PM in a rat model of DM. • TAPES is a continuous, real world, long-term PM exposure system. • HbA1c, a marker of glycemic homeostasis, was

  18. Source and sink nodes in absence seizures.

    Science.gov (United States)

    Rodrigues, Abner C; Machado, Birajara S; Caboclo, Luis Otavio S F; Fujita, Andre; Baccala, Luiz A; Sameshima, Koichi

    2016-08-01

    As opposed to focal epilepsy, absence seizures do not exhibit a clear seizure onset zone or focus since its ictal activity rapidly engages both brain hemispheres. Yet recent graph theoretical analysis applied to absence seizures EEG suggests the cortical focal presence, an unexpected feature for this type of epilepsy. In this study, we explore the characteristics of absence seizure by classifying the nodes as to their source/sink natures via weighted directed graph analysis based on connectivity direction and strength estimation using information partial directed coherence (iPDC). By segmenting the EEG signals into relatively short 5-sec-long time windows we studied the evolution of coupling strengths from both sink and source nodes, and the network dynamics of absence seizures in eight patients.

  19. Novel Natural Convection Heat Sink Design Concepts From First Principles

    Science.gov (United States)

    2016-06-01

    CONVECTION HEAT SINK DESIGN CONCEPTS FROM FIRST PRINCIPLES by Derek E. Fletcher June 2016 Thesis Advisor: Garth Hobson Second Reader...COVERED Master’s Thesis 4. TITLE AND SUBTITLE NOVEL NATURAL CONVECTION HEAT SINK DESIGN CONCEPTS FROM FIRST PRINCIPLES 5. FUNDING NUMBERS 6...CONVECTION HEAT SINK DESIGN CONCEPTS FROM FIRST PRINCIPLES Derek E. Fletcher Lieutenant Commander, United States Navy B.S., Southwestern

  20. Short-term changes in particulate fluxes measured by drifting sediment traps during end summer oligotrophic regime in the NW Mediterranean Sea

    Directory of Open Access Journals (Sweden)

    J. C. Marty

    2009-05-01

    Full Text Available Short-term changes in the flux of particulate matter were determined in the central north western Mediterranean Sea (near DYFAMED site using drifting sediment traps at 200 m depth in the course of the DYNAPROC 2 cruise (14 September–17 October 2004. In this period of marked water column stratification, POC fluxes varied by an order of magnitude, in the range of 0.03–0.29 mgC m−2 h−1 over the month and showed very rapid and high variations. Particulate carbon export represented less than 5% of integrated primary production, suggesting that phytoplankton production was essentially sustained by internal recycling of organic matter and retained within the photic zone. While PON and POP fluxes paralleled one another, the elemental ratios POC/PON and POC/POP, varied widely over short-term periods. Values of these ratios generally higher than the conventional Redfield ratio, together with the very low chlorophyll a flux recorded in the traps (mean 0.017 μg m−2 h−1, and the high phaeopigment and acyl lipid hydrolysis metabolite concentrations of the settling material, indicated that the organic matter reaching 200 m depth was reworked (by grazing, fecal pellets production, degradation and that algal sinking, dominated by nano- and picoplankton, made a small contribution to the downward flux. Over time, the relative abundance of individual lipid classes in organic matter (OM changed from glycolipids-dominated to neutral (wax esters, triacylglycerols and phospholipids-dominated, suggesting ecosystem maturation as well as rapid and continual exchanges between dissolved, suspended and sinking pools. Our most striking result was documenting the rapid change in fluxes of the various measured parameters. In the situation encountered here, with dominant regenerated production, a decrease of fluxes was noticed during windy periods (possibly through reduction of grazing. But fluxes increased as soon as calm

  1. Source apportionment of organic compounds in Berlin using positive matrix factorization - assessing the impact of biogenic aerosol and biomass burning on urban particulate matter.

    Science.gov (United States)

    Wagener, Sandra; Langner, Marcel; Hansen, Ute; Moriske, Heinz-Jörn; Endlicher, Wilfried R

    2012-10-01

    Source apportionment of 13 organic compounds, elemental carbon and organic carbon of ambient PM(10) and PM(1) was performed with positive matrix factorization (PMF). Samples were collected at three sites characterized by different vegetation influences in Berlin, Germany in 2010. The aim was to determine organic, mainly biogenic sources and their impact on urban aerosol collected in a densely populated region. A 6-factor solution provided the best data fit for both PM-fractions, allowing the sources isoprene- and α-pinene-derived secondary organic aerosol (SOA), bio primary, primarily attributable to fungal spores, bio/urban primary including plant fragments in PM(10) and cooking and traffic emissions in PM(1), biomass burning and combustion fossil to be identified. With mean concentrations up to 2.6 μg Cm(-3), biomass burning dominated the organic fraction in cooler months. Concentrations for α-pinene-derived SOA exceeded isoprene-derived concentrations. Estimated secondary organic carbon contributions to total organic carbon (OC) were between 7% and 42% in PM(10) and between 11% and 60% in PM(1), which is slightly lower than observed for US- or Asian cities. Primary biogenic emissions reached up to 33% of OC in the PM(10)-fraction in the late summer and autumn months. Temperature-dependence was found for both SOA-factors, correlations with ozone and mix depth only for the α-pinene-derived SOA-factor. Latter indicated input of α-pinene from the borders, highlighting differences in the origin of the precursors of both factors. Most factors were regionally distributed. High regional distribution was found to be associated with stronger influence of ambient parameters and higher concentrations at the background station. A significant contribution of biogenic emissions and biomass burning to urban organic aerosol could be stated. This indicates a considerable impact on PM concentrations also in cities in a densely populated area, and should draw the attention

  2. Recent Changes to the Strength of the CO2 Sink in Boreal Land Regions (Invited)

    Science.gov (United States)

    Hayes, D. J.; McGuire, A. D.; Kicklighter, D. W.; Gurney, K. R.; Melillo, J. M.

    2009-12-01

    Studies suggest that high-latitude terrestrial ecosystems have had a significant influence on the global carbon budget by acting as a substantial sink of atmospheric CO2 over the latter part of the 20th Century. However, recent changes in the controlling factors of this sink, including surface air temperature warming and increases in the frequency and severity of disturbances, have the potential to alter the C balance of boreal land regions. Whether these ecosystems continue to sequester atmospheric CO2 in the face of these changes is a key question in global change science and policy, as any changes to the strength of this major terrestrial sink will have important implications for the global C budget and climate system. Here, we diagnose and attribute contemporary terrestrial CO2 sink strength in the boreal land regions using a biogeochemical process model within a simulation framework that incorporates the impacts of recent changes in atmospheric chemistry and climate variability, as well as fire, forest management and agricultural land use regimes. The simulations estimate that the boreal land regions acted as a net sink of 102 TgC yr-1 from 1960 to 1980 that declined in strength to 28 TgC yr-1 for the 1990s and switched to a source of 99 TgC yr-1 from years 2000 to 2006. The weakening sink strength in the 1990s was largely a result of C losses from Boreal North American tundra and forest ecosystems through increasing decomposition of soil organic matter in response to warmer temperatures. Compared to previous decades, a near doubling of fire emissions was the major factor causing the boreal land regions to switch to a net C source since 2000 when large burn years occurred across the region, particularly in forests of Boreal Asia. A steady sink averaging 23 TgC yr-1 was estimated for Boreal European ecosystems from 1960 to 2006, with the ‘fertilization’ effects of increasing atmospheric CO2 concentration and N deposition primarily responsible for the

  3. Airborne particulates. European directives and standardization; Matieres particulaires dans l`air ambiant directives europeennes et normalisation

    Energy Technology Data Exchange (ETDEWEB)

    Houdret, J.L. [Ecole Nationale Superieure des Mines, 59 - Douai (France)

    1996-12-31

    The development of future European directives concerning atmospheric dusts and particulates, organization of the in-charge committee, measurement requirements and limit value determination processes are presented. Various measuring methods and instruments used for particulate and aerosol measurements are reviewed

  4. Stable carbon isotope analyses of nanogram quantities of particulate organic carbon (pollen) with laser ablation nano combustion gas chromatography/isotope ratio mass spectrometry

    NARCIS (Netherlands)

    van Roij, Linda; Sluijs, Appy; Laks, Jelmer J.; Reichart, Gert-Jan

    2017-01-01

    Rationale: Analyses of stable carbon isotope ratios (δ13C values) of organic and inorganic matter remains have been instrumental for much of our understanding of present and past environmental and biological processes. Until recently, the analytical window of such analyses has been limited to

  5. Plant Fructokinases: Evolutionary, Developmental, and Metabolic Aspects in Sink Tissues

    Directory of Open Access Journals (Sweden)

    Ofer Stein

    2018-03-01

    Full Text Available Sucrose, a glucose–fructose disaccharide, is the main sugar transported in the phloem of most plants and is the origin of most of the organic matter. Upon arrival in sink tissues, the sucrose must be cleaved by invertase or sucrose synthase. Both sucrose-cleaving enzymes yield free fructose, which must be phosphorylated by either fructokinase (FRK or hexokinase (HXK. The affinity of FRK to fructose is much higher than that of HXK, making FRKs central for fructose metabolism. An FRK gene family seems to exist in most, if not all plants and usually consists of several cytosolic FRKs and a single plastidic FRK. These genes are expressed mainly in sink tissues such as roots, stems, flowers, fruits, and seeds, with lower levels of expression often seen in leaves. Plant FRK enzymes vary in their biochemical properties such as affinity for fructose, inhibition by their substrate (i.e., fructose, and expression level in different tissues. This review describes recently revealed roles of plant FRKs in plant development, including the combined roles of the plastidic and cytosolic FRKs in vascular tissues and seed development.

  6. Do Continental Shelves Act as an Atmospheric CO2 Sink?

    Science.gov (United States)

    Cai, W.

    2003-12-01

    Recent air-to-sea CO2 flux measurements at several major continental shelves (European Atlantic Shelves, East China Sea and U.S. Middle Atlantic Bight) suggest that shelves may act as a one-way pump and absorb atmospheric CO2 into the ocean. These observations also favor the argument that continental shelves are autotrophic (i.e., net production of organic carbon, OC). The U.S. South Atlantic Bight (SAB) contrasts these findings in that it acts as a strong source of CO2 to the atmosphere while simultaneously exporting dissolved inorganic carbon (DIC) to the open ocean. We report pCO2, DIC, and alkalinity data from the SAB collected in 8 cruises along a transect from the shore to the shelf break in the central SAB. The shelf-wide net heterotrophy and carbon exports in the SAB are subsidized by the export of OC from the abundant intertidal marshes, which are a sink for atmospheric CO2. It is proposed here that the SAB represents a marsh-dominated heterotrophic ocean margin as opposed to river-dominated autotrophic margins. To further investigate why margins may behave differently in term of CO2 sink/source, the physical and biological conditions of several western boundary current margins are compared. Based on this and other studies, DIC export flux from margins to the open ocean must be significant in the overall global ocean carbon budget.

  7. Hormonal and metabolic regulation of tomato fruit sink activity and yield under salinity

    DEFF Research Database (Denmark)

    Albacete, Alfonso; Cantero-Navarro, Elena; Balibrea, María E.

    2014-01-01

    Salinization of water and soil has a negative impact on tomato (Solanum lycopersicum L.) productivity by reducing growth of sink organs and by inducing senescence in source leaves. It has been hypothesized that yield stability implies the maintenance or increase of sink activity in the reproductive...... structures, thus contributing to the transport of assimilates from the source leaves through changes in sucrolytic enzymes and their regulation by phytohormones. In this study, classical and functional physiological approaches have been integrated to study the influence of metabolic and hormonal factors...... sucrolytic activities (mainly cwInv and sucrose synthase), sink strength, and fruit weight, whereas the ethylene-releasing compound ethephon had a negative effect in equivalent non-stressed fruits. Fruit yield was increased by both the constitutive expression of CIN1 in the fruits (up to 4-fold) or IPT...

  8. On the meaning of sink capture efficiency and sink strength for point defects

    International Nuclear Information System (INIS)

    Mansur, L.K.; Wolfer, W.G.

    1982-01-01

    The concepts of sink capture efficiency and sink strength for point defects are central to the theory of point defect reactions in materials undergoing irradiation. Two fundamentally different definitions of the capture efficiency are in current use. The essential difference can be stated simply. The conventional meaning denotes a measure of the loss rate of point defects to sinks per unit mean point defect concentration. A second definition of capture efficiency, introduced recently, gives a measure of the point defect loss rate without normalization to the mean point defect concentration. The relationship between the two capture efficiencies is here derived. By stating the relationship we hope to eliminate confusion caused by comparisons of the two types of capture efficiencies at face value and to provide a method of obtaining one from the other. Internally consistent usage of either of the capture efficiencies leads to the same results for the calculation of measuable quantities, as is required physically. (orig.)

  9. Stable carbon isotope analyses of nanogram quantities of particulate organic carbon (pollen) with laser ablation nano combustion gas chromatography/isotope ratio mass spectrometry

    Science.gov (United States)

    Sluijs, Appy; Laks, Jelmer J.; Reichart, Gert‐Jan

    2016-01-01

    Rationale Analyses of stable carbon isotope ratios (δ 13C values) of organic and inorganic matter remains have been instrumental for much of our understanding of present and past environmental and biological processes. Until recently, the analytical window of such analyses has been limited to samples containing at least several μg of carbon. Methods Here we present a setup combining laser ablation, nano combustion gas chromatography and isotope ratio mass spectrometry (LA/nC/GC/IRMS). A deep UV (193 nm) laser is used for optimal fragmentation of organic matter with minimum fractionation effects and an exceptionally small ablation chamber and combustion oven are used to reduce the minimum sample mass requirement compared with previous studies. Results Analyses of the international IAEA CH‐7 polyethylene standard show optimal accuracy, and precision better than 0.5‰, when measuring at least 42 ng C. Application to untreated modern Eucalyptus globulus (C3 plant) and Zea mays (C4 plant) pollen grains shows a ~ 16‰ offset between these species. Within each single Z. mays pollen grain, replicate analyses show almost identical δ 13C values. Conclusions Isotopic offsets between individual pollen grains exceed analytical uncertainties, therefore probably reflecting interspecimen variability of ~0.5–0.9‰. These promising results set the stage for investigating both δ 13C values and natural carbon isotopic variability between single specimens of a single population of all kinds of organic particles yielding tens of nanograms of carbon. © 2016 The Authors. Rapid Communications in Mass Spectrometry Published by John Wiley & Sons Ltd. PMID:27766694

  10. Air-quality measurements in mega-cities: Focus on gaseous organic and particulate pollutants and comparison between two contrasted cities, Paris and Beijing

    International Nuclear Information System (INIS)

    Gros, V.; Sciare, J.; Yu, T.

    2007-01-01

    The rapid and important development of large urban areas ('mega-cities'), especially in developing countries, causes and will cause serious air-quality problems. Pollutant measurements in these cities help to characterize the chemical nature and the quantity of these pollutants and to constrain air-quality models. This paper focuses on measurements of volatile organic compounds and aerosols that have an important impact on air quality. We present a brief review on existing measurements and experimental strategies in mega-cities and then we show results from recent measurement campaigns that took place in two contrasted mega-cities: Paris and Beijing. (authors)

  11. Seasonal pathways of organic matter within the Avilés submarine canyon: Food web implications

    Science.gov (United States)

    Romero-Romero, Sonia; Molina-Ramírez, Axayacatl; Höfer, Juan; Duineveld, Gerard; Rumín-Caparrós, Aitor; Sanchez-Vidal, Anna; Canals, Miquel; Acuña, José Luis

    2016-11-01

    The transport and fate of organic matter (OM) sources within the Avilés submarine canyon (Cantabrian Sea, Southern Bay of Biscay) were studied using carbon and nitrogen stable isotope ratios. The isotopic composition of settling particles and deep bottom sediments closely resembled that of surface particulate OM, and there were no marked differences in the isotopic composition of settling particles inside and outside of the AC. This indicates that the Avilés Canyon (AC) receives inputs of sinking OM mostly from the upper water column and less through advective near-bottom down-canyon transport. Sinking OM fluxes are of marine and terrestrial origin in proportions which vary seasonally. Analysis of δ13C in the canyon fauna indicates a dependence on OM mainly produced by marine phytoplankton. A tight coupling of isotopic signatures between pelagic organisms and benthic suspension feeders reflects an active biological vertical transport of OM from the surface to the deep-sea. The food web presented seasonal variations in the trophic niche width and the amplitude of the primary carbon sources, reflecting seasonality in the availability of fresh particulate OM. Those seasonal changes are larger for benthic organisms of lower trophic levels.

  12. Particulate matter and plankton dynamics in the Ross Sea Polynya of Terra Nova Bay during the Austral Summer 1997/98

    Science.gov (United States)

    Fonda Umani, S.; Accornero, A.; Budillon, G.; Capello, M.; Tucci, S.; Cabrini, M.; Del Negro, P.; Monti, M.; De Vittor, C.

    2002-07-01

    The structure and variability of the plankton community and the distribution and composition of suspended particulate matter, were investigated in the polynya of Terra Nova Bay (western Ross Sea) during the austral summer 1997/1998, with the ultimate objective of understanding the trophic control of carbon export from the upper water column. Sampling was conducted along a transect parallel to the shore, near the retreating ice edge at the beginning of December, closer to the coast at the beginning of February, and more offshore in late February. Hydrological casts and water sampling were performed at several depths to measure total particulate matter (TPM), particulate organic carbon (POC), biogenic silica (BSi), chlorophyll a (Chl a) and phaeopigment (Phaeo) concentrations. Subsamples were taken for counting autotrophic and heterotrophic pico- and nanoplankton and to assess the abundance and composition of microphyto- and microzooplankton. Statistical analysis identified two major groups of samples: the first included the most coastal surface samples of early December, characterized by the prevalence of autotrophic nanoplankton biomass; the second included all the remaining samples and was dominated by microphytoplankton. With regard to the relation of the plankton community composition to the biogenic suspended and sinking material, we identified the succession of three distinct periods. In early December Phaeocystis dominated the plankton assemblage in the well-mixed water column, while at the retreating ice-edge a bloom of small diatoms (ND) was developing in the lens of superficial diluted water. Concentrations of biogenic particulates were generally low and confined to the uppermost layer. The very low downward fluxes, the near absence of faecal pellets and the high Chl a/Phaeo ratios suggested that the herbivorous food web was not established yet or, at least, was not working efficiently. In early February the superficial pycnocline and the increased water

  13. Particulates and organic compounds from wood firing - new investigations of emissions and concentrations; Partikler og organiske forbindelser fra traefyring - nye undersoegelser af udslip og koncentrationer

    Energy Technology Data Exchange (ETDEWEB)

    Glasius, M.; Konggaard, P.; Stubkjaer, J.; Bossi, R.; Hertel, O.; Ketzel, M.; Waehlin, P.; Schleicher, O.; Palmgren, F.

    2007-03-15

    Recent Danish as well as international studies have shown that wood burning may lead to increased levels air pollution levels of particles and different types of organic compounds in the vicinity of the sources. The air pollution constitutes a health risk for the local population but this risk is poorly quantified. Furthermore, the number of available studies is relatively limited with regard to pollutant emissions and concentrations related to wood burning. This report summarizes a number of studies which have the aim of contributing to the current understanding of the air pollution problem related to the use of wood stoves and boilers. The investigations include studies of emissions and resulting outdoor pollutant levels in two villages. Furthermore investigations of indoor-outdoor levels have been performed in two single-family detached houses. (au)

  14. Carbon transport by the Lena River from its headwaters to the Arctic Ocean, with emphasis on fluvial input of terrestrial particulate organic carbon vs. carbon transport by coastal erosion

    Directory of Open Access Journals (Sweden)

    I. P. Semiletov

    2011-09-01

    Full Text Available The Lena River integrates biogeochemical signals from its vast drainage basin, and the integrated signal reaches far out over the Arctic Ocean. Transformation of riverine organic carbon (OC into mineral carbon, and mineral carbon into the organic form in the Lena River watershed, can be considered to be quasi-steady-state processes. An increase in Lena discharge exerts opposite effects on total organic (TOC and total inorganic (TCO2 carbon: TOC concentration increases, while TCO2 concentration decreases. Significant inter-annual variability in mean values of TCO2, TOC, and their sum (total carbon, TC has been found. This variability is determined by changes in land hydrology which cause differences in the Lena River discharge. There is a negative correlation in the Lena River between TC in September and its mean discharge in August; a time shift of about one month is required for water to travel from Yakutsk to the Laptev Sea. Total carbon entering the sea with the Lena discharge is estimated to be almost 10 Tg C yr−1. The annual Lena River discharge of particulate organic carbon (POC can be as high as 0.38 Tg (moderate to high estimate. If we instead accept Lisytsin's (1994 statement that 85–95 % of total particulate matter (PM (and POC precipitates on the marginal "filter", then only about 0.03–0.04 Tg of Lena River POC reaches the Laptev Sea. The Lena's POC export would then be two orders of magnitude less than the annual input of eroded terrestrial carbon onto the shelf of the Laptev and East Siberian seas, which is estimated to be about 4 Tg. Observations support the hypothesis of a dominant role for coastal erosion (Semiletov, 1999a, b in East Siberian Arctic Shelf (ESAS sedimentation and the dynamics of the carbon/carbonate system. The Lena River is characterized by relatively high concentrations of the primary greenhouse gases, dissolved carbon dioxide (CO2 and methane (CH

  15. Vertical transport of suspended particulate trace elements in the North Atlantic Ocean

    International Nuclear Information System (INIS)

    Kuss, J.; Kremling, K.; Scholten, J.

    1999-01-01

    Suspended marine particles play a key role in the exchange processes between rapidly sinking particles and seawater because of their large surface area and long residence times. They are involved in the transport processes of rapidly sinking particles (∼ 100 m/day) through aggregation and disaggregation. This mechanism results in a net downward transport of suspended particulate trace elements (TE). To provide more information to these processes TE in suspended particulate material (SPM) have been measured on three cruises from 1995 to 1997 along 20 deg. W using a large volume in situ filtration between 25 m and 4150 m depth in addition to particle flux measurements with sediment traps. These studies were performed under the framework of German JGOFS

  16. Causes of sinks near Tucson, Arizona, USA

    Science.gov (United States)

    Hoffmann, John P.; Pool, Donald R.; Konieczki, A. D.; Carpenter, Michael C.

    Land subsidence in the form of sinks has occurred on and near farmlands near Tucson, Pima County, Arizona, USA. The sinks occur in alluvial deposits along the flood plain of the Santa Cruz River, and have made farmlands dangerous and unsuitable for farming. More than 1700 sinks are confined to the flood plain of the Santa Cruz River and are grouped along two north-northwestward-trending bands that are approximately parallel to the river and other flood-plain drainages. An estimated 17,000m3 of sediment have been removed in the formation of the sinks. Thirteen trenches were dug to depths of 4-6m to characterize near-surface sediments in sink and nonsink areas. Sediments below about 2m included a large percentage of dispersive clays in sink areas. Sediments in nonsink areas contain a large component of medium- to coarse-grained, moderately to well sorted sand that probably fills a paleochannel. Electromagnetic surveys support the association of silts and clays in sink areas that are highly electrically conductive relative to sand in nonsink areas. Sinks probably are caused by the near-surface process of subsurface erosion of dispersive sediments along pre-existing cracks in predominantly silt and clay sediments. The pre-existing cracks probably result from desiccation or tension that developed during periods of water-table decline and channel incision during the past 100 years or in earlier periods. Résumé Des effondrements en forme d'entonnoir se sont produits sur et près d'exploitations agricoles de Pima (Arizona). Ces entonnoirs apparaissent dans les alluvions le long de la plaine d'inondation de la rivière Santa Cruz ; ils ont rendu ces terrains dangereux et inexploitables pour l'agriculture. Plus de 1700 entonnoirs existent dans la plaine d'inondation de la rivière Santa Cruz et sont groupés en deux bandes orientées nord-nord-ouest, approximativement parallèles à la rivière et aux autres chenaux de la plaine d'inondation. Un volume de sédiments estim

  17. Laminar nanofluid flow in microheat-sinks

    Energy Technology Data Exchange (ETDEWEB)

    Koo, J.; Kleinstreuer, C. [North Carolina State University, Raleigh, NC (United States). Dept. of Mechanical and Aerospace Engineering

    2005-06-01

    In response to the ever increasing demand for smaller and lighter high-performance cooling devices, steady laminar liquid nanofluid flow in microchannels is simulated and analyzed. Considering two types of nanofluids, i.e., copper-oxide nanospheres at low volume concentrations in water or ethylene glycol, the conjugated heat transfer problem for microheat-sinks has been numerically solved. Employing new models for the effective thermal conductivity and dynamic viscosity of nanofluids, the impact of nanoparticle concentrations in these two mixture flows on the microchannel pressure gradients, temperature profiles and Nusselt numbers are computed, in light of aspect ratio, viscous dissipation, and enhanced temperature effects. Based on these results, the following can be recommended for microheat-sink performance improvements: Use of large high-Prandtl number carrier fluids, nanoparticles at high volume concentrations of about 4% with elevated thermal conductivities and dielectric constants very close to that of the carrier fluid, microchannels with high aspect ratios, and treated channel walls to avoid nanoparticle accumulation. (Author)

  18. Assessing the Influence of Seasonal and Spatial Variations on the Estimation of Secondary Organic Carbon in Urban Particulate Matter by Applying the EC-Tracer Method

    Directory of Open Access Journals (Sweden)

    Sandra Wagener

    2014-04-01

    Full Text Available The elemental carbon (EC-tracer method was applied to PM10 and PM1 data of three sampling sites in the City of Berlin from February to October 2010. The sites were characterized by differing exposure to traffic and vegetation. The aim was to determine the secondary organic carbon (SOC concentration and to describe the parameters influencing the application of the EC-tracer method. The evaluation was based on comparisons with results obtained from positive matrix factorization (PMF applied to the same samples. To obtain site- and seasonal representative primary OC/EC-ratios ([OC/EC]p, the EC-tracer method was performed separately for each station, and additionally discrete for samples with high and low contribution of biomass burning. Estimated SOC-concentrations for all stations were between 11% and 33% of total OC. SOC-concentrations obtained with PMF exceeded EC-tracer results more than 100% at the park in the period with low biomass burning emissions in PM10. The deviations were besides others attributed to the high ratio of biogenic to combustion emissions and to direct exposure to vegetation. The occurrences of biomass burning emissions in contrast lead to increased SOC-concentrations compared to PMF in PM10. The obtained results distinguish that the EC-tracer-method provides well comparable results with PMF if sites are strongly influenced by one characteristic primary combustion source, but was found to be adversely influenced by direct and relatively high biogenic emissions.

  19. Analysis of airborne particulate matter

    International Nuclear Information System (INIS)

    Iwatsuki, Masaaki

    2002-01-01

    An airborne particulate matter (APM) consists of many kinds of solid and liquid particles in air. APM analysis methods and the application examples are explained on the basis of paper published after 1998. Books and general remarks, sampling and the measurement of concentration and particle distribution, elemental analysis methods and the present state of analysis of species are introduced. Tapered Element Oscillating Microbalance (TEOM) method can collect continuously the integrating mass, but indicates lower concentration. Cu, Ni, Zn, Co, Fe(2), Mn, Cd, Fe(3) and Pb, the water-soluble elements, are determined by ion-chromatography after ultrasonic extraction of the aqueous solution. The detection limit of them is from 10 to 15 ppb (30 ppb Cd and 60 ppb Pb). The elemental carbon (EC) and organic carbon (OC) are separated by the thermal mass measurement-differential scanning calorimeter by means of keeping at 430degC for 60 min. 11 research organizations compared the results of TC (Total Carbon) and EC by NIOSH method 5040 and the thermal method and obtained agreement of TC. ICP-MS has been developed in order to determine correctly and quickly the trace elements. The determination methods for distinction of chemical forms in the environment were developed. GC/MS, LC/MS and related technologies for determination of organic substances are advanced. Online real-time analysis of APN, an ideal method, is examined. (S.Y.)

  20. Particulate barium tracing of significant mesopelagic carbon remineralisation in the North Atlantic

    Science.gov (United States)

    Lemaitre, Nolwenn; Planquette, Hélène; Planchon, Frédéric; Sarthou, Géraldine; Jacquet, Stéphanie; García-Ibáñez, Maribel I.; Gourain, Arthur; Cheize, Marie; Monin, Laurence; André, Luc; Laha, Priya; Terryn, Herman; Dehairs, Frank

    2018-04-01

    The remineralisation of sinking particles by prokaryotic heterotrophic activity is important for controlling oceanic carbon sequestration. Here, we report mesopelagic particulate organic carbon (POC) remineralisation fluxes in the North Atlantic along the GEOTRACES-GA01 section (GEOVIDE cruise; May-June 2014) using the particulate biogenic barium (excess barium; Baxs) proxy. Important mesopelagic (100-1000 m) Baxs differences were observed along the transect depending on the intensity of past blooms, the phytoplankton community structure, and the physical forcing, including downwelling. The subpolar province was characterized by the highest mesopelagic Baxs content (up to 727 pmol L-1), which was attributed to an intense bloom averaging 6 mg chl a m-3 between January and June 2014 and by an intense 1500 m deep convection in the central Labrador Sea during the winter preceding the sampling. This downwelling could have promoted a deepening of the prokaryotic heterotrophic activity, increasing the Baxs content. In comparison, the temperate province, characterized by the lowest Baxs content (391 pmol L-1), was sampled during the bloom period and phytoplankton appear to be dominated by small and calcifying species, such as coccolithophorids. The Baxs content, related to oxygen consumption, was converted into a remineralisation flux using an updated relationship, proposed for the first time in the North Atlantic. The estimated fluxes were of the same order of magnitude as other fluxes obtained using independent methods (moored sediment traps, incubations) in the North Atlantic. Interestingly, in the subpolar and subtropical provinces, mesopelagic POC remineralisation fluxes (up to 13 and 4.6 mmol C m-2 d-1, respectively) were equalling and occasionally even exceeding upper-ocean POC export fluxes, deduced using the 234Th method. These results highlight the important impact of the mesopelagic remineralisation on the biological carbon pump of the studied area with a near

  1. Sink-oriented Dynamic Location Service Protocol for Mobile Sinks with an Energy Efficient Grid-Based Approach

    Directory of Open Access Journals (Sweden)

    Hyunseung Choo

    2009-03-01

    Full Text Available Sensor nodes transmit the sensed information to the sink through wireless sensor networks (WSNs. They have limited power, computational capacities and memory. Portable wireless devices are increasing in popularity. Mechanisms that allow information to be efficiently obtained through mobile WSNs are of significant interest. However, a mobile sink introduces many challenges to data dissemination in large WSNs. For example, it is important to efficiently identify the locations of mobile sinks and disseminate information from multi-source nodes to the multi-mobile sinks. In particular, a stationary dissemination path may no longer be effective in mobile sink applications, due to sink mobility. In this paper, we propose a Sink-oriented Dynamic Location Service (SDLS approach to handle sink mobility. In SDLS, we propose an Eight-Direction Anchor (EDA system that acts as a location service server. EDA prevents intensive energy consumption at the border sensor nodes and thus provides energy balancing to all the sensor nodes. Then we propose a Location-based Shortest Relay (LSR that efficiently forwards (or relays data from a source node to a sink with minimal delay path. Our results demonstrate that SDLS not only provides an efficient and scalable location service, but also reduces the average data communication overhead in scenarios with multiple and moving sinks and sources.

  2. Sink-oriented Dynamic Location Service Protocol for Mobile Sinks with an Energy Efficient Grid-Based Approach.

    Science.gov (United States)

    Jeon, Hyeonjae; Park, Kwangjin; Hwang, Dae-Joon; Choo, Hyunseung

    2009-01-01

    Sensor nodes transmit the sensed information to the sink through wireless sensor networks (WSNs). They have limited power, computational capacities and memory. Portable wireless devices are increasing in popularity. Mechanisms that allow information to be efficiently obtained through mobile WSNs are of significant interest. However, a mobile sink introduces many challenges to data dissemination in large WSNs. For example, it is important to efficiently identify the locations of mobile sinks and disseminate information from multi-source nodes to the multi-mobile sinks. In particular, a stationary dissemination path may no longer be effective in mobile sink applications, due to sink mobility. In this paper, we propose a Sink-oriented Dynamic Location Service (SDLS) approach to handle sink mobility. In SDLS, we propose an Eight-Direction Anchor (EDA) system that acts as a location service server. EDA prevents intensive energy consumption at the border sensor nodes and thus provides energy balancing to all the sensor nodes. Then we propose a Location-based Shortest Relay (LSR) that efficiently forwards (or relays) data from a source node to a sink with minimal delay path. Our results demonstrate that SDLS not only provides an efficient and scalable location service, but also reduces the average data communication overhead in scenarios with multiple and moving sinks and sources.

  3. Mangrove production and carbon sinks: A revision of global budget estimates

    Science.gov (United States)

    Bouillon, S.; Borges, A.V.; Castaneda-Moya, E.; Diele, K.; Dittmar, T.; Duke, N.C.; Kristensen, E.; Lee, S.-Y.; Marchand, C.; Middelburg, J.J.; Rivera-Monroy, V. H.; Smith, T. J.; Twilley, R.R.

    2008-01-01

    Mangrove forests are highly productive but globally threatened coastal ecosystems, whose role in the carbon budget of the coastal zone has long been debated. Here we provide a comprehensive synthesis of the available data on carbon fluxes in mangrove ecosystems. A reassessment of global mangrove primary production from the literature results in a conservative estimate of ???-218 ?? 72 Tg C a-1. When using the best available estimates of various carbon sinks (organic carbon export, sediment burial, and mineralization), it appears that >50% of the carbon fixed by mangrove vegetation is unaccounted for. This unaccounted carbon sink is conservatively estimated at ??? 112 ?? 85 Tg C a-1, equivalent in magnitude to ??? 30-40% of the global riverine organic carbon input to the coastal zone. Our analysis suggests that mineralization is severely underestimated, and that the majority of carbon export from mangroves to adjacent waters occurs as dissolved inorganic carbon (DIC). CO2 efflux from sediments and creek waters and tidal export of DIC appear to be the major sinks. These processes are quantitatively comparable in magnitude to the unaccounted carbon sink in current budgets, but are not yet adequately constrained with the limited published data available so far. Copyright 2008 by the American Geophysical Union.

  4. Particulate sulfur-containing lipids: Production and cycling from the epipelagic to the abyssopelagic zone

    Science.gov (United States)

    Gašparović, Blaženka; Penezić, Abra; Frka, Sanja; Kazazić, Saša; Lampitt, Richard S.; Holguin, F. Omar; Sudasinghe, Nilusha; Schaub, Tanner

    2018-04-01

    There are major gaps in our understanding of the distribution and role of lipids in the open ocean especially with regard to sulfur-containing lipids (S-lipids). Here, we employ a powerful analytical approach based on high resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) to elucidate depth-related S-lipid production and molecular transformations in suspended particulate matter from the Northeast Atlantic Ocean in this depth range. We show that within the open-ocean environment S-lipids contribute up to 4.2% of the particulate organic carbon, and that up to 95% of these compounds have elemental compositions that do not match those found in the Nature Lipidomics Gateway database (termed "novel"). Among the remaining 5% of lipids that match the database, we find that sulphoquinovosyldiacylglycerol (SQDG) are efficiently removed while sinking through the mesopelagic zone. The relative abundance of other assigned lipids (sulphoquinovosylmonoacylglycerol (SQMG), sulfite and sulfate lipids, Vitamin D2 and D3 derivatives, and sphingolipids) did not change substantially with depth. The novel S-lipids, represented by hundreds of distinct elemental compositions (160-300 molecules at any one depth), contribute increasingly to the lipid and particulate organic matter pools with increased depth. Depth-related transformations cause (i) incomplete degradation/transformation of unsaturated S-lipids which leads to the depth-related accumulation of the refractory saturated compounds with reduced molecular weight (average 455 Da) and (ii) formation of highly unsaturated S-lipids (average abyssopelagic molecular double bond equivalents, DBE=7.8) with lower molecular weight (average 567 Da) than surface S-lipids (average 592 Da). A depth-related increase in molecular oxygen content is observed for all novel S-lipids and indicates that oxidation has a significant role in their transformation while (bio)hydrogenation possibly impacts the formation of

  5. Characteristics of sources and sinks of momentum in a turbulent boundary layer

    Science.gov (United States)

    Fiscaletti, D.; Ganapathisubramani, B.

    2018-05-01

    In turbulent boundary layers, the wall-normal gradient of the Reynolds shear stress identifies momentum sources and sinks (T =∂ [-u v ]/∂ y ). These motions can be physically interpreted in two ways: (1) as contributors to the turbulence term balancing the mean momentum equation, and (2) as regions of strong local interaction between velocity and vorticity fluctuations. In this paper, the space-time evolution of momentum sources and sinks is investigated in a turbulent boundary layer at the Reynolds number (Reτ) = 2700, with time-resolved planar particle image velocimetry in a plane along the streamwise and wall-normal directions. Wave number-frequency power spectra of T fluctuations reveal that the wave velocities of momentum sources and sinks tend to match the local streamwise velocity in proximity to the wall. However, as the distance from the wall increases, the wave velocities of the T events are slightly lower than the local streamwise velocities of the flow, which is also confirmed from the tracking in time of the intense momentum sources and sinks. This evidences that momentum sources and sinks are preferentially located in low-momentum regions of the flow. The spectral content of the T fluctuations is maximum at the wall, but it decreases monotonically as the distance from the wall grows. The relative spectral contributions of the different wavelengths remains unaltered at varying wall-normal locations. From autocorrelation coefficient maps, the characteristic streamwise and wall-normal extents of the T motions are respectively 60 and 40 wall units, independent of the wall distance. Both statistics and instantaneous visualizations show that momentum sources and sinks have a preferential tendency to be organized in positive-negative pairs in the wall-normal direction.

  6. Chemistry of superoxide radical in seawater: CDOM associated sink of superoxide in coastal waters

    Energy Technology Data Exchange (ETDEWEB)

    Goldstone, J.V.; Voelker, B.M.

    2000-03-15

    Colored dissolved organic matter (CDOM) and humic substances contain a nonmetallic redox-cycling component capable of catalyzing superoxide (O{sub 2}{sup {minus}}) dismutation. First-order rate coefficients (k{sub pseudo}) measured for this O{sub 2}{sup {minus}} sink in a number of coastal and Chesapeake Bay water samples range up to 1.4s{sup {minus}1}, comparable in magnitude to catalyzed dismutation by Cu species. A significant (r{sup 2}=0.73) correlation is observed between k{sub pseudo} and the optical absorption and salinity of individual coastal water samples, suggesting an association with non-marine-derived CDOM. The activity of this sink is not changed by acidification or boiling of samples but is removed by photooxidation, indicating that it is an organic compound, but that it is neither enzymatic nor likely to consist of tightly bound metals. The stoichiometry of hydrogen peroxide formation from O{sub 2}{sup {minus}} decay indicates that this sink is capable of a redox cycle catalyzing the dismutation of O{sub 2}{sup {minus}}. This CDOM sink combined with the organic copper sink previously described will produce a steady-state superoxide concentration in coastal waters that is 100--1000-fold lower than that predicted from bimolecular dismutation alone. Catalyzed O{sub 2}{sup {minus}} decay was also observed in a variety of humic and fulvic acid samples, possibly occurring through quinone functionalities. Although the presence of quinone moieties in humic and fulvic acids has been demonstrated, there do not appear to be good correlations between several measures of quinone content and the O{sub 2}{sup {minus}} dismutation rates of these samples.

  7. Organic carbon deliveries and their flow related dynamics in the Fitzroy estuary

    International Nuclear Information System (INIS)

    Ford, Phillip; Tillman, Pei; Robson, Barbara; Webster, Ian T.

    2005-01-01

    The Fitzroy estuary (Queensland, Australia) receives large, but highly episodic, river flows from a catchment (144,000 km 2 ) which has undergone major land clearing. Large quantities of suspended sediments, and particulate and dissolved organic carbon are delivered. At peak flows, δ 13 C (-21.7 ± 0.8%o) and C/N (14.8 ± 1.3) of the suspended solids indicate that the particulate organic material entering the estuary is principally soil organic carbon. At the lower beginning flows the particulate organic matter comes from in-stream producers (δ 13 C = -26%o). The DOC load is about 10 times the POC load. Using the inverse method, budgets for POC and DOC were constructed for high and low flows. Under high flows, only a small portion of the POC and DOC load is lost in the estuary. Under dry season (low flow) conditions the estuary is a sink for DOC, but remains a source of POC to the coastal waters

  8. Origin and biochemical cycling of particulate nitrogen in the Mandovi estuary

    Digital Repository Service at National Institute of Oceanography (India)

    Fernandes, L

    for particulate organic carbon (POC) and particulate organic nitrogen (PON), delta sup(13) C sub(POC), total hydrolysable amino acid enantiomers (L- and D- amino acids) concentration and composition. Delta sup(13)C sub(POC) values were depleted (-32 to -25 ppt...

  9. Characterization of a catalyst-based conversion technique to measure total particulate nitrogen and organic carbon and comparison to a particle mass measurement instrument

    Science.gov (United States)

    Stockwell, Chelsea E.; Kupc, Agnieszka; Witkowski, Bartłomiej; Talukdar, Ranajit K.; Liu, Yong; Selimovic, Vanessa; Zarzana, Kyle J.; Sekimoto, Kanako; Warneke, Carsten; Washenfelder, Rebecca A.; Yokelson, Robert J.; Middlebrook, Ann M.; Roberts, James M.

    2018-05-01

    The chemical composition of aerosol particles is a key aspect in determining their impact on the environment. For example, nitrogen-containing particles impact atmospheric chemistry, air quality, and ecological N deposition. Instruments that measure total reactive nitrogen (Nr = all nitrogen compounds except for N2 and N2O) focus on gas-phase nitrogen and very few studies directly discuss the instrument capacity to measure the mass of Nr-containing particles. Here, we investigate the mass quantification of particle-bound nitrogen using a custom Nr system that involves total conversion to nitric oxide (NO) across platinum and molybdenum catalysts followed by NO-O3 chemiluminescence detection. We evaluate the particle conversion of the Nr instrument by comparing to mass-derived concentrations of size-selected and counted ammonium sulfate ((NH4)2SO4), ammonium nitrate (NH4NO3), ammonium chloride (NH4Cl), sodium nitrate (NaNO3), and ammonium oxalate ((NH4)2C2O4) particles determined using instruments that measure particle number and size. These measurements demonstrate Nr-particle conversion across the Nr catalysts that is independent of particle size with 98 ± 10 % efficiency for 100-600 nm particle diameters. We also show efficient conversion of particle-phase organic carbon species to CO2 across the instrument's platinum catalyst followed by a nondispersive infrared (NDIR) CO2 detector. However, the application of this method to the atmosphere presents a challenge due to the small signal above background at high ambient levels of common gas-phase carbon compounds (e.g., CO2). We show the Nr system is an accurate particle mass measurement method and demonstrate its ability to calibrate particle mass measurement instrumentation using single-component, laboratory-generated, Nr-containing particles below 2.5 µm in size. In addition we show agreement with mass measurements of an independently calibrated online particle-into-liquid sampler directly coupled to the

  10. Airborne Particulate Threat Assessment

    Energy Technology Data Exchange (ETDEWEB)

    Patrick Treado; Oksana Klueva; Jeffrey Beckstead

    2008-12-31

    Aerosol threat detection requires the ability to discern between threat agents and ambient background particulate matter (PM) encountered in the environment. To date, Raman imaging technology has been demonstrated as an effective strategy for the assessment of threat agents in the presence of specific, complex backgrounds. Expanding our understanding of the composition of ambient particulate matter background will improve the overall performance of Raman Chemical Imaging (RCI) detection strategies for the autonomous detection of airborne chemical and biological hazards. Improving RCI detection performance is strategic due to its potential to become a widely exploited detection approach by several U.S. government agencies. To improve the understanding of the ambient PM background with subsequent improvement in Raman threat detection capability, ChemImage undertook the Airborne Particulate Threat Assessment (APTA) Project in 2005-2008 through a collaborative effort with the National Energy Technology Laboratory (NETL), under cooperative agreement number DE-FC26-05NT42594. During Phase 1 of the program, a novel PM classification based on molecular composition was developed based on a comprehensive review of the scientific literature. In addition, testing protocols were developed for ambient PM characterization. A signature database was developed based on a variety of microanalytical techniques, including scanning electron microscopy, FT-IR microspectroscopy, optical microscopy, fluorescence and Raman chemical imaging techniques. An automated particle integrated collector and detector (APICD) prototype was developed for automated collection, deposition and detection of biothreat agents in background PM. During Phase 2 of the program, ChemImage continued to refine the understanding of ambient background composition. Additionally, ChemImage enhanced the APICD to provide improved autonomy, sensitivity and specificity. Deliverables included a Final Report detailing our

  11. Effects of biofouling on the sinking behavior of microplastics

    Science.gov (United States)

    Kaiser, David; Kowalski, Nicole; Waniek, Joanna J.

    2017-12-01

    Although plastic is ubiquitous in marine systems, our current knowledge of transport mechanisms is limited. Much of the plastic entering the ocean sinks; this is intuitively obvious for polymers such as polystyrene (PS), which have a greater density than seawater, but lower density polymers like polyethylene (PE) also occur in sediments. Biofouling can cause large plastic objects to sink, but this phenomenon has not been described for microplastics microplastic particles in estuarine and coastal waters to determine how biofouling changes their sinking behavior. Sinking velocities of PS increased by 16% in estuarine water (salinity 9.8) and 81% in marine water (salinity 36) after 6 weeks of incubation. Thereafter sinking velocities decreased due to lower water temperatures and reduced light availability. Biofouling did not cause PE to sink during the 14 weeks of incubation in estuarine water, but PE started to sink after six weeks in coastal water when sufficiently colonized by blue mussels Mytilus edulis, and its velocity continued to increase until the end of the incubation period. Sinking velocities of these PE pellets were similar irrespective of salinity (10 vs. 36). Biofilm composition differed between estuarine and coastal stations, presumably accounting for differences in sinking behavior. We demonstrate that biofouling enhances microplastic deposition to marine sediments, and our findings should improve microplastic transport models.

  12. The potential contribution of sinks to meeting Kyoto Protocol commitments

    DEFF Research Database (Denmark)

    Missfeldt, F.; Haites, E.

    2001-01-01

    scenario, at least some of the sinks have costs lower than the market price, so the larger the eligible sinks, the lower the compliance costs for industrialised countries. Greater use of sinks also reduces the net income received by the economies in transition and developing countries. Increased use......, a range of average costs is used with the lowest cost allowing maximum use of sinks. The effects considered are the impacts on compliance costs for OECD countries, economies in transition, and developing countries and the mix of actions used by industrialised countries to achieve compliance. In every...

  13. Investigation of Heat Sink Efficiency for Electronic Component Cooling Applications

    DEFF Research Database (Denmark)

    Staliulionis, Ž.; Zhang, Zhe; Pittini, Riccardo

    2014-01-01

    Research and optimisation of cooling of electronic components using heat sinks becomes increasingly important in modern industry. Numerical methods with experimental real-world verification are the main tools to evaluate efficiency of heat sinks or heat sink systems. Here the investigation...... of relatively simple heat sink application is performed using modeling based on finite element method, and also the potential of such analysis was demonstrated by real-world measurements and comparing obtained results. Thermal modeling was accomplished using finite element analysis software COMSOL and thermo...

  14. Sources and sinks of stratospheric water vapor

    International Nuclear Information System (INIS)

    Ellsaesser, H.W.

    1979-11-01

    A tutorial review of the understanding of stratospheric H 2 O and the processes controlling it is presented. Paradoxes posed by currently available observational data are cited and suggestions made as to how they might be resolved. Such resolution appears to require: that the bulk of our current data provides unrepresentative and misleading vertical and latitudinal H 2 O gradients immediately downstream from the tropical tropopause; and, that there exists within the troposphere a mechanism different from or in addition to the tropical tropopause cold trap for drying air to the mixing ratios found in the lower stratosphere. Satisfaction of these requirements will reconcile much heretofore puzzling observational data and will obviate the necessity for a stratospheric sink for H 2 O

  15. Omnivory in birds is a macroevolutionary sink.

    Science.gov (United States)

    Burin, Gustavo; Kissling, W Daniel; Guimarães, Paulo R; Şekercioğlu, Çağan H; Quental, Tiago B

    2016-04-07

    Diet is commonly assumed to affect the evolution of species, but few studies have directly tested its effect at macroevolutionary scales. Here we use Bayesian models of trait-dependent diversification and a comprehensive dietary database of all birds worldwide to assess speciation and extinction dynamics of avian dietary guilds (carnivores, frugivores, granivores, herbivores, insectivores, nectarivores, omnivores and piscivores). Our results suggest that omnivory is associated with higher extinction rates and lower speciation rates than other guilds, and that overall net diversification is negative. Trait-dependent models, dietary similarity and network analyses show that transitions into omnivory occur at higher rates than into any other guild. We suggest that omnivory acts as macroevolutionary sink, where its ephemeral nature is retrieved through transitions from other guilds rather than from omnivore speciation. We propose that these dynamics result from competition within and among dietary guilds, influenced by the deep-time availability and predictability of food resources.

  16. How phosphorus limitation can control climatic gas sources and sinks

    Science.gov (United States)

    Gypens, Nathalie; Borges, Alberto V.; Ghyoot, Caroline

    2017-04-01

    Since the 1950's, anthropogenic activities severely increased river nutrient loads in European coastal areas. Subsequent implementation of nutrient reduction policies have considerably reduced phosphorus (P) loads from mid-1980's, while nitrogen (N) loads were maintained, inducing a P limitation of phytoplankton growth in many eutrophied coastal areas such as the Southern Bight of the North Sea (SBNS). When dissolved inorganic phosphorous (DIP) is limiting, most phytoplankton organisms are able to indirectly acquire P from dissolved organic P (DOP). We investigate the impact of DOP use on the importance of phytoplankton production and atmospheric fluxes of CO2 and dimethylsulfide (DMS) in the SBNS from 1951 to 2007 using an extended version of the R-MIRO-BIOGAS model. This model includes a description of the ability of phytoplankton organisms to use DOP as a source of P. Results show that primary production can increase up to 70% due to DOP uptake in limiting DIP conditions. Consequently, simulated DMS emissions double while CO2 emissions to the atmosphere decrease, relative to the reference simulation without DOP uptake. At the end of the simulated period (late 2000's), the net direction of air-sea CO2 annual flux, changed from a source to a sink for atmospheric CO2 in response to use of DOP and increase of primary production.

  17. UHS, Ultimate Heat Sink Cooling Pond Analysis

    International Nuclear Information System (INIS)

    Codell, R.; Nuttle, W.K.

    1998-01-01

    1 - Description of program or function: Three programs model performance of an ultimate heat sink cooling pond. National Weather Service data is read and analyzed to predict periods of lowest cooling performance and highest evaporative loss. The data is compared to local site data for significant differences. Then the maximum pond temperature is predicted. Five programs model performance of an ultimate heat sink spray pond. The cooling performance, evaporative water loss, and drift water loss as a function of wind speed are estimated for a spray field. These estimates are used in conjunction with National Weather Service data to predict periods of lowest cooling performance and highest evaporative loss. This data is compared to local site data for significant differences. Then the maximum pond temperature is predicted. 2 - Method of solution: The transfer of heat and water vapor is modeled using an equilibrium temperature procedure for an UHS cooling pond. The UHS spray pond model considers heat, mass, and momentum transfer from a single water drop with the surrounding air, and modification of the surrounding air resulting from the heat, mass, and momentum transfer from many drops in different parts of a spray field. 3 - Restrictions on the complexity of the problem: The program SPRCO uses RANF, a uniform random number generator which is an intrinsic function on the CDC. All programs except COMET use the NAMELIST statement, which is non standard. Otherwise these programs conform to the ANSI Fortran 77 standard. The meteorological data scanning procedure requires tens of years of recorded data to be effective. The models and methods, provided as useful tool for UHS analyses of cooling ponds and spray ponds, are intended as guidelines only. Use of these methods does not automatically assure NRC approval, nor are they required procedures for nuclear-power-plant licensing

  18. Using plant growth modeling to analyse C source-sink relations under drought: inter and intra specific comparison

    Directory of Open Access Journals (Sweden)

    Benoit ePallas

    2013-11-01

    Full Text Available The ability to assimilate C and allocate NSC (non structural carbohydrates to the most appropriate organs is crucial to maximize plant ecological or agronomic performance. Such C source and sink activities are differentially affected by environmental constraints. Under drought, plant growth is generally more sink than source limited as organ expansion or appearance rate is earlier and stronger affected than C assimilation. This favors plant survival and recovery but not always agronomic performance as NSC are stored rather than used for growth due to a modified metabolism in source and sink leaves. Such interactions between plant C and water balance are complex and plant modeling can help analyzing their impact on plant phenotype. This paper addresses the impact of trade-offs between C sink and source activities and plant production under drought, combining experimental and modeling approaches. Two contrasted monocotyledonous species (rice, oil palm were studied. Experimentally, the sink limitation of plant growth under moderate drought was confirmed as well as the modifications in NSC metabolism in source and sink organs. Under severe stress, when C source became limiting, plant NSC concentration decreased. Two plant models dedicated to oil palm and rice morphogenesis were used to perform a sensitivity analysis and further explore how to optimize C sink and source drought sensitivity to maximize plant growth. Modeling results highlighted that optimal drought sensitivity depends both on drought type and species and that modeling is a great opportunity to analyse such complex processes. Further modeling needs and more generally the challenge of using models to support complex trait breeding are discussed.

  19. Effect of sink size on growth response to elevated atmospheric CO{sub 2} within the genus Brassica

    Energy Technology Data Exchange (ETDEWEB)

    Reekie, E G; Wong, I; MacDougall, G [Acadia Univ., Wolfsville, NS (Canada); Hicklenton, P R [Agriculture Canada, Research Station, Kentville, NS (Canada)

    1998-05-01

    This study examines the response to elevated CO{sub 2} of seven broccoli, cauliflower, mustard, and turnip species (sp. Brassica). These species are the end result of selection by plant breeders for different allocation patterns and differ markedly in both the size and location of their carbon sinks. Based on the assumption that the presence of carbon storage organs is indicative of a low source to sink ratio, the hypothesis that innate differences in source to sink ratio among plants influences their response to elevated CO{sub 2} was examined. The study also investigated the question of whether location of the sink in root, stem or reproductive structures has any influence on response to elevated CO{sub 2}. Neither biomass allocation to photosynthetic versus non-photosynthetic tissues, nor leaf area ratio could adequately reflect the differences in source to sink ratio within the genus Brassica. Although the evidence is not straightforward, it is clear that there are other factors than the presence of carbon sinks that influence the response to elevated CO{sub 2}. 24 refs., 3 figs.

  20. Determining Inorganic and Organic Carbon.

    Science.gov (United States)

    Koistinen, Jaana; Sjöblom, Mervi; Spilling, Kristian

    2017-11-21

    Carbon is the element which makes up the major fraction of lipids and carbohydrates, which could be used for making biofuel. It is therefore important to provide enough carbon and also follow the flow into particulate organic carbon and potential loss to dissolved organic forms of carbon. Here we present methods for determining dissolved inorganic carbon, dissolved organic carbon, and particulate organic carbon.

  1. Source-to-sink transport of sugar and regulation by environmental factors.

    Science.gov (United States)

    Lemoine, Remi; La Camera, Sylvain; Atanassova, Rossitza; Dédaldéchamp, Fabienne; Allario, Thierry; Pourtau, Nathalie; Bonnemain, Jean-Louis; Laloi, Maryse; Coutos-Thévenot, Pierre; Maurousset, Laurence; Faucher, Mireille; Girousse, Christine; Lemonnier, Pauline; Parrilla, Jonathan; Durand, Mickael

    2013-01-01

    Source-to-sink transport of sugar is one of the major determinants of plant growth and relies on the efficient and controlled distribution of sucrose (and some other sugars such as raffinose and polyols) across plant organs through the phloem. However, sugar transport through the phloem can be affected by many environmental factors that alter source/sink relationships. In this paper, we summarize current knowledge about the phloem transport mechanisms and review the effects of several abiotic (water and salt stress, mineral deficiency, CO2, light, temperature, air, and soil pollutants) and biotic (mutualistic and pathogenic microbes, viruses, aphids, and parasitic plants) factors. Concerning abiotic constraints, alteration of the distribution of sugar among sinks is often reported, with some sinks as roots favored in case of mineral deficiency. Many of these constraints impair the transport function of the phloem but the exact mechanisms are far from being completely known. Phloem integrity can be disrupted (e.g., by callose deposition) and under certain conditions, phloem transport is affected, earlier than photosynthesis. Photosynthesis inhibition could result from the increase in sugar concentration due to phloem transport decrease. Biotic interactions (aphids, fungi, viruses…) also affect crop plant productivity. Recent breakthroughs have identified some of the sugar transporters involved in these interactions on the host and pathogen sides. The different data are discussed in relation to the phloem transport pathways. When possible, the link with current knowledge on the pathways at the molecular level will be highlighted.

  2. Uncovering Offshore Financial Centers: Conduits and Sinks in the Global Corporate Ownership Network.

    Science.gov (United States)

    Garcia-Bernardo, Javier; Fichtner, Jan; Takes, Frank W; Heemskerk, Eelke M

    2017-07-24

    Multinational corporations use highly complex structures of parents and subsidiaries to organize their operations and ownership. Offshore Financial Centers (OFCs) facilitate these structures through low taxation and lenient regulation, but are increasingly under scrutiny, for instance for enabling tax avoidance. Therefore, the identification of OFC jurisdictions has become a politicized and contested issue. We introduce a novel data-driven approach for identifying OFCs based on the global corporate ownership network, in which over 98 million firms (nodes) are connected through 71 million ownership relations. This granular firm-level network data uniquely allows identifying both sink-OFCs and conduit-OFCs. Sink-OFCs attract and retain foreign capital while conduit-OFCs are attractive intermediate destinations in the routing of international investments and enable the transfer of capital without taxation. We identify 24 sink-OFCs. In addition, a small set of five countries - the Netherlands, the United Kingdom, Ireland, Singapore and Switzerland - canalize the majority of corporate offshore investment as conduit-OFCs. Each conduit jurisdiction is specialized in a geographical area and there is significant specialization based on industrial sectors. Against the idea of OFCs as exotic small islands that cannot be regulated, we show that many sink and conduit-OFCs are highly developed countries.

  3. Efficient Data Collection by Mobile Sink to Detect Phenomena in Internet of Things

    Directory of Open Access Journals (Sweden)

    Amany Abu Safia

    2017-10-01

    Full Text Available With the rapid development of Internet of Things (IoT, more and more static and mobile sensors are being deployed for sensing and tracking environmental phenomena, such as fire, oil spills and air pollution. As these sensors are usually battery-powered, energy-efficient algorithms are required to extend the sensors’ lifetime. Moreover, forwarding sensed data towards a static sink causes quick battery depletion of the sinks’ nearby sensors. Therefore, in this paper, we propose a distributed energy-efficient algorithm, called the Hilbert-order Collection Strategy (HCS, which uses a mobile sink (e.g., drone to collect data from a mobile wireless sensor network (mWSN and detect environmental phenomena. The mWSN consists of mobile sensors that sense environmental data. These mobile sensors self-organize themselves into groups. The sensors of each group elect a group head (GH, which collects data from the mobile sensors in its group. Periodically, a mobile sink passes by the locations of the GHs (data collection path to collect their data. The collected data are aggregated to discover a global phenomenon. To shorten the data collection path, which results in reducing the energy cost, the mobile sink establishes the path based on the order of Hilbert values of the GHs’ locations. Furthermore, the paper proposes two optimization techniques for data collection to further reduce the energy cost of mWSN and reduce the data loss.

  4. Transfer, sources and sinks for major and trace elements in urban and rural areas

    International Nuclear Information System (INIS)

    Schnetger, B.; Brumsack, H.J.; Heinrichs, H.

    1996-01-01

    Spider webs and air filter samples from 11 German cities were analyzed for major and trace elements to determine the composition of urban particulates. Model calculation was used for the estimation of the sources (fraction of components with decreasing importance): tire abrasion, diesel soot, tar, material from the earth crust and brick abrasion, concrete abrasion, sulfur, gasoline soot, cement production, hard coal ash, lignite fly ash, steel production, waste incineration, sea spray, oil combustion, brake abrasion. Heavy metals in city dust are mostly related to traffic and industrial high temperature processes. The most important sink for the metals and acids of polluted air masses was found to be the forested areas of mountains exposed to the main wind direction. High enrichment of heavy metals and low pH values in the top soils of such areas (Harz Mountain, Germany) were found. From previously (now damaged) forested areas an acid front moves downward. Metals from the top soils were dissolved by this process. In the investigated area precipitation of the released metals takes place in the lakes and a drinking water reservoir. These sinks again become a source when acidification increases. (author)

  5. Application of in situ observations, high frequency radars, and ocean color, to study suspended matter, particulate carbon, and dissolved organic carbon fluxes in coastal waters of the Barents Sea - the NORDFLUX project

    Science.gov (United States)

    Stramska, Malgorzata; Yngve Børsheim, Knut; Białogrodzka, Jagoda; Cieszyńska, Agata; Ficek, Dariusz; Wereszka, Marzena

    2016-04-01

    There is still a limited knowledge about suspended and dissolved matter fluxes transported from coastal regions into the open sea regions in the Arctic. The land/sea interface is environmentally important and sensitive to climate change. Important biogeochemical material entering the oceans (including carbon) passes through this interface, but too little is known about the efficiency of this transport. Our goal in the NORDFLUX program is to improve quantitative understanding of the environmental feedbacks involved in these processes through an interdisciplinary study with innovative in situ observations. Completed work includes two in situ experiments in the Norwegian fiord (Porsangerfjorden) in the summers of 2014 and 2015. Experiments used research boat for collection of water samples and in situ bio-optical data, an autonomous glider, mooring with T S sensors, and a high frequency radar system. We have used these data to derive spatial maps of water temperature, salinity, surface currents, chlorophyll fluorescence, dissolved organic matter (DOM) fluorescence, and inherent optical properties (IOPs) of the water. The interpretation of these data in terms of suspended matter concentration and composition is possible by in situ 'calibrations' using water samples from discrete hydrographic stations. Total suspended matter (TSM), particulate carbon (POC and PIC), and dissolved organic carbon (DOC) concentrations together with measured water currents will allow us to estimate reservoirs and fluxes. Concentrations and fluxes will be related to physical conditions and meteorological data. An important aspect of this project is the work on regional ocean color algorithms. Global ocean color (OC) algorithms currently used by NASA do not perform sufficiently well in coastal Case 2 waters. Our data sets will allow us to derive such local algorithms. We will then use these algorithms for interpretation of OC data in terms of TSM concentrations and composition and DOC. After

  6. Copepods use chemical trails to find sinking marine snow aggregates

    DEFF Research Database (Denmark)

    Lombard, Fabien; Koski, Marja; Kiørboe, Thomas

    2013-01-01

    Copepods are major consumers of sinking marine particles and hence reduce the efficiency of the biological carbon pump. Their high abundance on marine snow suggests that they can detect sinking particles remotely. By means of laboratory observations, we show that the copepod Temora longicornis ca...

  7. Characterizing source-sink dynamics with genetic parentage assignments

    NARCIS (Netherlands)

    Peery, M. Zachariah; Beissinger, Steven R.; House, Roger F.; Berube, Martine; Hall, Laurie A.; Sellas, Anna; Palsboll, Per J.

    2008-01-01

    Source-sink dynamics have been suggested to characterize the population structure of many species, but the prevalence of source-sink systems in nature is uncertain because of inherent challenges in estimating migration rates among populations. Migration rates are often difficult to estimate directly

  8. Sinks as integrative elements of the anthropogenic metabolism

    Science.gov (United States)

    Kral, Ulrich; Brunner, Paul H.

    2015-04-01

    The anthropogenic metabolism is an open system requiring exchange of materials and energy between the anthroposphere and the environment. Material and energy flows are taken from nature and become utilized by men. After utilization, the materials either remain in the anthroposphere as recycling products, or they leave the anthroposphere as waste and emission flows. To accommodate these materials without jeopardizing human and environmental health, limited natural sinks are available; thus, man-made sinks have to be provided where natural sinks are missing or overloaded. The oral presentation (1) suggests a coherent definition of the term "sink", encompassing natural and man-made processes, (2) presents a framework to analyse and evaluate anthropogenic material flows to sinks, based on the tool substance flow analysis and impact assessment methodology, and (3) applies the framework in a case study approach for selected substances such as Copper and Lead in Vienna and Perfluorooctane sulfonate in Switzerland. Finally, the numeric results are aggregated in terms of a new indicator that specifies on a regional scale which fractions of anthropogenic material flows to sinks are acceptable. The following results are obtained: In Vienna, 99% of Cu flows to natural and man-made sinks are in accordance with accepted standards. However, the 0.7% of Cu entering urban soils and the 0.3% entering receiving waters surpass the acceptable level. In the case of Pb, 92% of all flows into sinks prove to be acceptable, but 8% are disposed of in local landfills with limited capacity. For PFOS, 96% of all flows into sinks are acceptable. 4% cannot be evaluated due to a lack of normative criteria, despite posing a risk for human health and the environment. The case studies corroborate the need and constraints of sinks to accommodate inevitable anthropogenic material flows.

  9. Fire ants perpetually rebuild sinking towers

    Science.gov (United States)

    Phonekeo, Sulisay; Mlot, Nathan; Monaenkova, Daria; Hu, David L.; Tovey, Craig

    2017-07-01

    In the aftermath of a flood, fire ants, Solenopsis invicta, cluster into temporary encampments. The encampments can contain hundreds of thousands of ants and reach over 30 ants high. How do ants build such tall structures without being crushed? In this combined experimental and theoretical study, we investigate the shape and rate of construction of ant towers around a central support. The towers are bell shaped, consistent with towers of constant strength such as the Eiffel tower, where each element bears an equal load. However, unlike the Eiffel tower, the ant tower is built through a process of trial and error, whereby failed portions avalanche until the final shape emerges. High-speed and novel X-ray videography reveal that the tower constantly sinks and is rebuilt, reminiscent of large multicellular systems such as human skin. We combine the behavioural rules that produce rafts on water with measurements of adhesion and attachment strength to model the rate of growth of the tower. The model correctly predicts that the growth rate decreases as the support diameter increases. This work may inspire the design of synthetic swarms capable of building in vertical layers.

  10. Evidence for nitrite-dependent anaerobic methane oxidation as a previously overlooked microbial methane sink in wetlands

    Science.gov (United States)

    Hu, Bao-lan; Shen, Li-dong; Lian, Xu; Zhu, Qun; Liu, Shuai; Huang, Qian; He, Zhan-fei; Geng, Sha; Cheng, Dong-qing; Lou, Li-ping; Xu, Xiang-yang; Zheng, Ping; He, Yun-feng

    2014-01-01

    The process of nitrite-dependent anaerobic methane oxidation (n-damo) was recently discovered and shown to be mediated by “Candidatus Methylomirabilis oxyfera” (M. oxyfera). Here, evidence for n-damo in three different freshwater wetlands located in southeastern China was obtained using stable isotope measurements, quantitative PCR assays, and 16S rRNA and particulate methane monooxygenase gene clone library analyses. Stable isotope experiments confirmed the occurrence of n-damo in the examined wetlands, and the potential n-damo rates ranged from 0.31 to 5.43 nmol CO2 per gram of dry soil per day at different depths of soil cores. A combined analysis of 16S rRNA and particulate methane monooxygenase genes demonstrated that M. oxyfera-like bacteria were mainly present in the deep soil with a maximum abundance of 3.2 × 107 gene copies per gram of dry soil. It is estimated that ∼0.51 g of CH4 m−2 per year could be linked to the n-damo process in the examined wetlands based on the measured potential n-damo rates. This study presents previously unidentified confirmation that the n-damo process is a previously overlooked microbial methane sink in wetlands, and n-damo has the potential to be a globally important methane sink due to increasing nitrogen pollution. PMID:24616523

  11. Anaerobic Nitrogen Turnover by Sinking Diatom Aggregates at Varying Ambient Oxygen Levels

    Directory of Open Access Journals (Sweden)

    Peter eStief

    2016-02-01

    Full Text Available In the world’s oceans, even relatively low oxygen (O2 levels inhibit anaerobic nitrogen cycling by free-living microbes. Sinking organic aggregates, however, might provide oxygen-depleted microbial hotspots in otherwise oxygenated surface waters. Here we show that sinking diatom aggregates can host anaerobic nitrogen cycling at ambient O2 levels well above the hypoxic threshold. Aggregates were produced from the ubiquitous diatom Skeletonema marinoi and the natural microbial community of seawater. Microsensor profiling through the center of sinking aggregates revealed internal anoxia at ambient 40% air saturation (~100 µmol O2 L-1 and below. Accordingly, anaerobic nitrate turnover inside the aggregates was evident within this range of ambient O2 levels. In incubations with 15N-labeled nitrate, individual Skeletonema aggregates produced NO2- (up to 10.7 nmol N h-1 per aggregate, N2 (up to 7.1 nmol N h-1, NH4+ (up to 2.0 nmol N h-1, and N2O (up to 0.2 nmol N h-1. Intriguingly, nitrate stored inside the diatom cells served as an additional, internal nitrate source for N2 production, which may partially uncouple anaerobic nitrate turnover by diatom aggregates from direct ambient nitrate supply. Sinking diatom aggregates can contribute directly to fixed-nitrogen loss in low-oxygen environments in the ocean and vastly expand the ocean volume in which anaerobic nitrogen turnover is possible, despite relatively high ambient O2 levels. Depending on the extent of intracellular nitrate consumption during the sinking process, diatom aggregates may also be involved in the long-distance export of nitrate to the deep ocean.

  12. Exposure to the elemental carbon, organic carbon, nitrate and sulfate fractions of fine particulate matter and risk of preterm birth in New Jersey, Ohio, and Pennsylvania (2000-2005).

    Science.gov (United States)

    BACKGROUND: Particulate matter ≤2.5 µm in aerodynamic diameter (PM2.5) has been consistently associated with preterm birth (PTB) to varying degrees, but roles of PM2.5 species have been less studied.OBJECTIVE:We estimated risk differences (RD) of PTB (reported per 106 pregnancies...

  13. ADVANCED HYBRID PARTICULATE COLLECTOR

    Energy Technology Data Exchange (ETDEWEB)

    Ye Zhuang; Stanley J. Miller; Michelle R. Olderbak; Rich Gebert

    2001-12-01

    A new concept in particulate control, called an advanced hybrid particulate collector (AHPC), is being developed under funding from the U.S. Department of Energy. The AHPC combines the best features of electrostatic precipitators (ESPs) and baghouses in an entirely novel manner. The AHPC concept combines fabric filtration and electrostatic precipitation in the same housing, providing major synergism between the two methods, both in the particulate collection step and in transfer of dust to the hopper. The AHPC provides ultrahigh collection efficiency, overcoming the problem of excessive fine-particle emissions with conventional ESPs, and solves the problem of reentrainment and re-collection of dust in conventional baghouses. Phase I of the development effort consisted of design, construction, and testing of a 5.7-m{sup 3}/min (200-acfm) working AHPC model. Results from both 8-hr parametric tests and 100-hr proof-of-concept tests with two different coals demonstrated excellent operability and greater than 99.99% fine-particle collection efficiency. Since all of the developmental goals of Phase I were met, the approach was scaled up in Phase II to a size of 255 m{sup 3}/min (9000 acfm) (equivalent in size to 2.5 MW) and was installed on a slipstream at the Big Stone Power Plant. For Phase II, the AHPC at Big Stone Power Plant was operated continuously from late July 1999 until mid-December 1999. The Phase II results were highly successful in that ultrahigh particle collection efficiency was achieved, pressure drop was well controlled, and system operability was excellent. For Phase III, the AHPC was modified into a more compact configuration, and components were installed that were closer to what would be used in a full-scale commercial design. The modified AHPC was operated from April to July 2000. While operational results were acceptable during this time, inspection of bags in the summer of 2000 revealed some membrane damage to the fabric that appeared to be

  14. Emission factors of fine particulate matter, organic and elemental carbon, carbon monoxide, and carbon dioxide for four solid fuels commonly used in residential heating by the U.S. Navajo Nation.

    Science.gov (United States)

    Champion, Wyatt M; Connors, Lea; Montoya, Lupita D

    2017-09-01

    Most homes in the Navajo Nation use wood as their primary heating fuel, often in combination with locally mined coal. Previous studies observed health effects linked to this solid-fuel use in several Navajo communities. Emission factors (EFs) for common fuels used by the Navajo have not been reported using a relevant stove type. In this study, two softwoods (ponderosa pine and Utah juniper) and two high-volatile bituminous coals (Black Mesa and Fruitland) were tested with an in-use residential conventional wood stove (homestove) using a modified American Society for Testing and Materials/U.S. Environmental Protection Agency (ASTM/EPA) protocol. Filter sampling quantified PM 2.5 (particulate matter with an aerodynamic diameter ≤2.5 μm) and organic (OC) and elemental (EC) carbon in the emissions. Real-time monitoring quantified carbon monoxide (CO), carbon dioxide (CO 2 ), and total suspended particles (TSP). EFs for these air pollutants were developed and normalized to both fuel mass and energy consumed. In general, coal had significantly higher mass EFs than wood for all pollutants studied. In particular, coal emitted, on average, 10 times more PM 2.5 than wood on a mass basis, and 2.4 times more on an energy basis. The EFs developed here were based on fuel types, stove design, and operating protocols relevant to the Navajo Nation, but they could be useful to other Native Nations with similar practices, such as the nearby Hopi Nation. Indoor wood and coal combustion is an important contributor to public health burdens in the Navajo Nation. Currently, there exist no emission factors representative of Navajo homestoves, fuels, and practices. This study developed emission factors for PM 2.5 , OC, EC, CO, and CO 2 using a representative Navajo homestove. These emission factors may be utilized in regional-, national-, and global-scale health and environmental models. Additionally, the protocols developed and results presented here may inform on-going stove design of

  15. Impact of high soot-loaded and regenerated diesel particulate filters on the emissions of persistent organic pollutants from a diesel engine fueled with waste cooking oil-based biodiesel

    International Nuclear Information System (INIS)

    Chen, Chia-Yang; Lee, Wen-Jhy; Wang, Lin-Chi; Chang, Yu-Cheng; Yang, Hsi-Hsien; Young, Li-Hao; Lu, Jau-Huai; Tsai, Ying I.; Cheng, Man-Ting; Mwangi, John Kennedy

    2017-01-01

    Highlights: • WCO-based biodiesel blends cannot stimulate POPs formation in uncatalyzed DPF. • Formation mechanism of POPs in diesel engines is homogeneous gas-phase formation. • The gas-phase POPs are highly dominant in the raw exhausts of diesel engines. • The regeneration of the DPF can drastically reduce the formation potential of POPs in the DPFs. - Abstract: This study evaluated the impact on persistent organic pollutant (POP) emissions from a diesel engine when deploying a diesel oxidation catalyst (DOC) combined with an uncatalyzed diesel particulate filter (DPF), as well as fueling with conventional diesel (B2) and waste cooking oil-based (WCO-based) biodiesel blends (B10 and B20). When the engine was fueled with WCO-based biodiesel blends (B10 and B20) in combination with deploying DOC+A-DPF, their levels of the chlorine and potassium contents could not stimulate the formation of chlorinated POPs (PCDD/Fs and PCBs), although previous studies had warned that happened on diesel engines fueled with biodiesel and deployed with iron-catalyzed DPFs. In contrast, the WCO-based biodiesel with a lower aromatic content reduced the precursors for POP formation, and its higher oxygen content compared to diesel promoted more complete combustion, and thus using WCO-based biodiesel could reduce both PM_2_._5 and POP emissions from diesel engines. This study also evaluated the impact of DPF conditions on the POP emissions from a diesel engine; that is, the difference in POP emissions before and just after the regeneration of the DPF. In comparison to the high soot-loaded DPF scenario, the regeneration of the DPF can drastically reduce the formation potential of POPs in the DPFs. An approach was developed to correct the effects of sampling artifacts on the partitioning of gas- and particle-phase POPs in the exhaust. The gas-phase POPs are highly dominant (89.7–100%) in the raw exhausts of diesel engines, indicating that the formation mechanism of POPs in diesel

  16. Maximizing Lifetime of Wireless Sensor Networks with Mobile Sink Nodes

    Directory of Open Access Journals (Sweden)

    Yourong Chen

    2014-01-01

    Full Text Available In order to maximize network lifetime and balance energy consumption when sink nodes can move, maximizing lifetime of wireless sensor networks with mobile sink nodes (MLMS is researched. The movement path selection method of sink nodes is proposed. Modified subtractive clustering method, k-means method, and nearest neighbor interpolation method are used to obtain the movement paths. The lifetime optimization model is established under flow constraint, energy consumption constraint, link transmission constraint, and other constraints. The model is solved from the perspective of static and mobile data gathering of sink nodes. Subgradient method is used to solve the lifetime optimization model when one sink node stays at one anchor location. Geometric method is used to evaluate the amount of gathering data when sink nodes are moving. Finally, all sensor nodes transmit data according to the optimal data transmission scheme. Sink nodes gather the data along the shortest movement paths. Simulation results show that MLMS can prolong network lifetime, balance node energy consumption, and reduce data gathering latency under appropriate parameters. Under certain conditions, it outperforms Ratio_w, TPGF, RCC, and GRND.

  17. Method and apparatus for removing volatile hydrocarbons from particulate soils

    International Nuclear Information System (INIS)

    Mendenhall, R.L.

    1992-01-01

    This patent describes an apparatus for heating solid particulate mineral compositions. It comprises: a counterflow ratable drum having a first end and an opposite second end, a first portion of the drum extending from the first end for a first length and having a first diameter along the first length, and a second portion of the drum secured to and extending from the first portion to the second end for a second length and having a second diameter along the second length, the second diameter being less than the first diameter, a burner adjacent the first end for introducing and directing hot gases of combustion into the first portion of the drum toward the second end, means for introducing particulate composition into the drum at the second end, means for directing the particulate composition along the drum from the second end toward the first end, and means for recovering composition at the first end, means for removing a gaseous mixture of organic volatiles, gases of combustion and fine particles of the particulate composition adjacent the second drum end, means for separating fine particles of the particulate composition from the gaseous mixture, and means for returning the separated fine particulate composition particles to the first portion of the drum

  18. Coupling individual kernel-filling processes with source-sink interactions into GREENLAB-Maize.

    Science.gov (United States)

    Ma, Yuntao; Chen, Youjia; Zhu, Jinyu; Meng, Lei; Guo, Yan; Li, Baoguo; Hoogenboom, Gerrit

    2018-02-13

    Failure to account for the variation of kernel growth in a cereal crop simulation model may cause serious deviations in the estimates of crop yield. The goal of this research was to revise the GREENLAB-Maize model to incorporate source- and sink-limited allocation approaches to simulate the dry matter accumulation of individual kernels of an ear (GREENLAB-Maize-Kernel). The model used potential individual kernel growth rates to characterize the individual potential sink demand. The remobilization of non-structural carbohydrates from reserve organs to kernels was also incorporated. Two years of field experiments were conducted to determine the model parameter values and to evaluate the model using two maize hybrids with different plant densities and pollination treatments. Detailed observations were made on the dimensions and dry weights of individual kernels and other above-ground plant organs throughout the seasons. Three basic traits characterizing an individual kernel were compared on simulated and measured individual kernels: (1) final kernel size; (2) kernel growth rate; and (3) duration of kernel filling. Simulations of individual kernel growth closely corresponded to experimental data. The model was able to reproduce the observed dry weight of plant organs well. Then, the source-sink dynamics and the remobilization of carbohydrates for kernel growth were quantified to show that remobilization processes accompanied source-sink dynamics during the kernel-filling process. We conclude that the model may be used to explore options for optimizing plant kernel yield by matching maize management to the environment, taking into account responses at the level of individual kernels. © The Author(s) 2018. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  19. Temperature effects on sinking velocity of different Emiliania huxleyi strains.

    Science.gov (United States)

    Rosas-Navarro, Anaid; Langer, Gerald; Ziveri, Patrizia

    2018-01-01

    The sinking properties of three strains of Emiliania huxleyi in response to temperature changes were examined. We used a recently proposed approach to calculate sinking velocities from coccosphere architecture, which has the advantage to be applicable not only to culture samples, but also to field samples including fossil material. Our data show that temperature in the sub-optimal range impacts sinking velocity of E. huxleyi. This response is widespread among strains isolated in different locations and moreover comparatively predictable, as indicated by the similar slopes of the linear regressions. Sinking velocity was positively correlated to temperature as well as individual cell PIC/POC over the sub-optimum to optimum temperature range in all strains. In the context of climate change our data point to an important influence of global warming on sinking velocities. It has recently been shown that seawater acidification has no effect on sinking velocity of a Mediterranean E. huxleyi strain, while nutrient limitation seems to have a small negative effect on sinking velocity. Given that warming, acidification, and lowered nutrient availability will occur simultaneously under climate change scenarios, the question is what the net effect of different influential factors will be. For example, will the effects of warming and nutrient limitation cancel? This question cannot be answered conclusively but analyses of field samples in addition to laboratory culture studies will improve predictions because in field samples multi-factor influences and even evolutionary changes are not excluded. As mentioned above, the approach of determining sinking rate followed here is applicable to field samples. Future studies could use it to analyse not only seasonal and geographic patterns but also changes in sinking velocity over geological time scales.

  20. Biological control of the terrestrial carbon sink

    Science.gov (United States)

    Schulze, E.-D.

    2006-03-01

    different reasons depending on the region of the world: anthropogenic nitrogen deposition is the controlling factor in Europe, increasing global temperatures is the main factor in Siberia, and maybe rising CO2 the factor controlling the carbon fluxes in Amazonia. However, this has not lead to increases in net biome productivity, due to associated losses. Also important is the interaction between biodiversity and biogeochemical processes. It is shown that net primary productivity increases with plant species diversity (50% species loss equals 20% loss in productivity). However, in this extrapolation the action of soil biota is poorly understood although soils contribute the largest number of species and of taxonomic groups to an ecosystem. The global terrestrial carbon budget strongly depends on areas with pristine old growth forests which are carbon sinks. The management options are very limited, mostly short term, and usually associated with high uncertainty. Unmanaged grasslands appear to be a carbon sink of similar magnitude as forest, but generally these ecosystems lost their C with grazing and agricultural use. Extrapolation to the future of Earth climate shows that the biota will not be able to balance fossil fuel emissions, and that it will be essential to develop a carbon free energy system in order to maintain the living conditions on earth.

  1. Biological control of the terrestrial carbon sink

    Directory of Open Access Journals (Sweden)

    E.-D. Schulze

    2006-01-01

    plant growth has different reasons depending on the region of the world: anthropogenic nitrogen deposition is the controlling factor in Europe, increasing global temperatures is the main factor in Siberia, and maybe rising CO2 the factor controlling the carbon fluxes in Amazonia. However, this has not lead to increases in net biome productivity, due to associated losses. Also important is the interaction between biodiversity and biogeochemical processes. It is shown that net primary productivity increases with plant species diversity (50% species loss equals 20% loss in productivity. However, in this extrapolation the action of soil biota is poorly understood although soils contribute the largest number of species and of taxonomic groups to an ecosystem. The global terrestrial carbon budget strongly depends on areas with pristine old growth forests which are carbon sinks. The management options are very limited, mostly short term, and usually associated with high uncertainty. Unmanaged grasslands appear to be a carbon sink of similar magnitude as forest, but generally these ecosystems lost their C with grazing and agricultural use. Extrapolation to the future of Earth climate shows that the biota will not be able to balance fossil fuel emissions, and that it will be essential to develop a carbon free energy system in order to maintain the living conditions on earth.

  2. Mesoscale inversion of carbon sources and sinks

    International Nuclear Information System (INIS)

    Lauvaux, T.

    2008-01-01

    Inverse methods at large scales are used to infer the spatial variability of carbon sources and sinks over the continents but their uncertainties remain large. Atmospheric concentrations integrate the surface flux variability but atmospheric transport models at low resolution are not able to simulate properly the local atmospheric dynamics at the measurement sites. However, the inverse estimates are more representative of the large spatial heterogeneity of the ecosystems compared to direct flux measurements. Top-down and bottom-up methods that aim at quantifying the carbon exchanges between the surface and the atmosphere correspond to different scales and are not easily comparable. During this phD, a mesoscale inverse system was developed to correct carbon fluxes at 8 km resolution. The high resolution transport model MesoNH was used to simulate accurately the variability of the atmospheric concentrations, which allowed us to reduce the uncertainty of the retrieved fluxes. All the measurements used here were observed during the intensive regional campaign CERES of May and June 2005, during which several instrumented towers measured CO 2 concentrations and fluxes in the South West of France. Airborne measurements allowed us to observe concentrations at high altitude but also CO 2 surface fluxes over large parts of the domain. First, the capacity of the inverse system to correct the CO 2 fluxes was estimated using pseudo-data experiments. The largest fraction of the concentration variability was attributed to regional surface fluxes over an area of about 300 km around the site locations depending on the meteorological conditions. Second, an ensemble of simulations allowed us to define the spatial and temporal structures of the transport errors. Finally, the inverse fluxes at 8 km resolution were compared to direct flux measurements. The inverse system has been validated in space and time and showed an improvement of the first guess fluxes from a vegetation model

  3. Electrically heated particulate filter restart strategy

    Science.gov (United States)

    Gonze, Eugene V [Pinckney, MI; Ament, Frank [Troy, MI

    2011-07-12

    A control system that controls regeneration of a particulate filter is provided. The system generally includes a propagation module that estimates a propagation status of combustion of particulate matter in the particulate filter. A regeneration module controls current to the particulate filter to re-initiate regeneration based on the propagation status.

  4. Development of Problem Sets for K-12 and Engineering on Pharmaceutical Particulate Systems

    Science.gov (United States)

    Savelski, Mariano J.; Slater, C. Stewart; Del Vecchio, Christopher A.; Kosteleski, Adrian J.; Wilson, Sarah A.

    2010-01-01

    Educational problem sets have been developed on structured organic particulate systems (SOPS) used in pharmaceutical technology. The sets present topics such as particle properties and powder flow and can be integrated into K-12 and college-level curricula. The materials educate students in specific areas of pharmaceutical particulate processing,…

  5. Low Carbon sink capacity of Red Sea mangroves.

    Science.gov (United States)

    Almahasheer, Hanan; Serrano, Oscar; Duarte, Carlos M; Arias-Ortiz, Ariane; Masque, Pere; Irigoien, Xabier

    2017-08-29

    Mangroves forests of Avicennia marina occupy about 135 km 2 in the Red Sea and represent one of the most important vegetated communities in this otherwise arid and oligotrophic region. We assessed the soil organic carbon (C org ) stocks, soil accretion rates (SAR; mm y -1 ) and soil C org sequestration rates (g C org m -2 yr -1 ) in 10 mangrove sites within four locations along the Saudi coast of the Central Red Sea. Soil C org density and stock in Red Sea mangroves were among the lowest reported globally, with an average of 4 ± 0.3 mg C org cm -3 and 43 ± 5 Mg C org ha -1 (in 1 m-thick soils), respectively. Sequestration rates of C org , estimated at 3 ± 1 and 15 ± 1 g C org m -2 yr -1 for the long (millennia) and short (last century) temporal scales, respectively, were also relatively low compared to mangrove habitats from more humid bioregions. In contrast, the accretion rates of Central Red Sea mangroves soils were within the range reported for global mangrove forests. The relatively low C org sink capacity of Red Sea mangroves could be due to the extreme environmental conditions such as low rainfall, nutrient limitation and high temperature, reducing the growth rates of the mangroves and increasing soil respiration rates.

  6. Low Carbon sink capacity of Red Sea mangroves

    KAUST Repository

    Almahasheer, Hanan

    2017-08-22

    Mangroves forests of Avicennia marina occupy about 135 km2 in the Red Sea and represent one of the most important vegetated communities in this otherwise arid and oligotrophic region. We assessed the soil organic carbon (C-org) stocks, soil accretion rates (SAR; mm y(-1)) and soil C-org sequestration rates (g C-org m(-2) yr(-1)) in 10 mangrove sites within four locations along the Saudi coast of the Central Red Sea. Soil C-org density and stock in Red Sea mangroves were among the lowest reported globally, with an average of 4 +/- 0.3 mg Corg cm(-3) and 43 +/- 5 Mg C-org ha(-1) (in 1 m-thick soils), respectively. Sequestration rates of C-org, estimated at 3 +/- 1 and 15 +/- 1 g C-org m(-2) yr(-1) for the long (millennia) and short (last century) temporal scales, respectively, were also relatively low compared to mangrove habitats from more humid bioregions. In contrast, the accretion rates of Central Red Sea mangroves soils were within the range reported for global mangrove forests. The relatively low C-org sink capacity of Red Sea mangroves could be due to the extreme environmental conditions such as low rainfall, nutrient limitation and high temperature, reducing the growth rates of the mangroves and increasing soil respiration rates.

  7. Low Carbon sink capacity of Red Sea mangroves

    KAUST Repository

    Almahasheer, Hanan; Serrano, Oscar; Duarte, Carlos M.; Arias-Ortiz, Ariane; Masque, Pere; Irigoien, Xabier

    2017-01-01

    Mangroves forests of Avicennia marina occupy about 135 km2 in the Red Sea and represent one of the most important vegetated communities in this otherwise arid and oligotrophic region. We assessed the soil organic carbon (C-org) stocks, soil accretion rates (SAR; mm y(-1)) and soil C-org sequestration rates (g C-org m(-2) yr(-1)) in 10 mangrove sites within four locations along the Saudi coast of the Central Red Sea. Soil C-org density and stock in Red Sea mangroves were among the lowest reported globally, with an average of 4 +/- 0.3 mg Corg cm(-3) and 43 +/- 5 Mg C-org ha(-1) (in 1 m-thick soils), respectively. Sequestration rates of C-org, estimated at 3 +/- 1 and 15 +/- 1 g C-org m(-2) yr(-1) for the long (millennia) and short (last century) temporal scales, respectively, were also relatively low compared to mangrove habitats from more humid bioregions. In contrast, the accretion rates of Central Red Sea mangroves soils were within the range reported for global mangrove forests. The relatively low C-org sink capacity of Red Sea mangroves could be due to the extreme environmental conditions such as low rainfall, nutrient limitation and high temperature, reducing the growth rates of the mangroves and increasing soil respiration rates.

  8. Modeling the energy performance of event-driven wireless sensor network by using static sink and mobile sink.

    Science.gov (United States)

    Chen, Jiehui; Salim, Mariam B; Matsumoto, Mitsuji

    2010-01-01

    Wireless Sensor Networks (WSNs) designed for mission-critical applications suffer from limited sensing capacities, particularly fast energy depletion. Regarding this, mobile sinks can be used to balance the energy consumption in WSNs, but the frequent location updates of the mobile sinks can lead to data collisions and rapid energy consumption for some specific sensors. This paper explores an optimal barrier coverage based sensor deployment for event driven WSNs where a dual-sink model was designed to evaluate the energy performance of not only static sensors, but Static Sink (SS) and Mobile Sinks (MSs) simultaneously, based on parameters such as sensor transmission range r and the velocity of the mobile sink v, etc. Moreover, a MS mobility model was developed to enable SS and MSs to effectively collaborate, while achieving spatiotemporal energy performance efficiency by using the knowledge of the cumulative density function (cdf), Poisson process and M/G/1 queue. The simulation results verified that the improved energy performance of the whole network was demonstrated clearly and our eDSA algorithm is more efficient than the static-sink model, reducing energy consumption approximately in half. Moreover, we demonstrate that our results are robust to realistic sensing models and also validate the correctness of our results through extensive simulations.

  9. Modeling the Energy Performance of Event-Driven Wireless Sensor Network by Using Static Sink and Mobile Sink

    Science.gov (United States)

    Chen, Jiehui; Salim, Mariam B.; Matsumoto, Mitsuji

    2010-01-01

    Wireless Sensor Networks (WSNs) designed for mission-critical applications suffer from limited sensing capacities, particularly fast energy depletion. Regarding this, mobile sinks can be used to balance the energy consumption in WSNs, but the frequent location updates of the mobile sinks can lead to data collisions and rapid energy consumption for some specific sensors. This paper explores an optimal barrier coverage based sensor deployment for event driven WSNs where a dual-sink model was designed to evaluate the energy performance of not only static sensors, but Static Sink (SS) and Mobile Sinks (MSs) simultaneously, based on parameters such as sensor transmission range r and the velocity of the mobile sink v, etc. Moreover, a MS mobility model was developed to enable SS and MSs to effectively collaborate, while achieving spatiotemporal energy performance efficiency by using the knowledge of the cumulative density function (cdf), Poisson process and M/G/1 queue. The simulation results verified that the improved energy performance of the whole network was demonstrated clearly and our eDSA algorithm is more efficient than the static-sink model, reducing energy consumption approximately in half. Moreover, we demonstrate that our results are robust to realistic sensing models and also validate the correctness of our results through extensive simulations. PMID:22163503

  10. Electrical diesel particulate filter (DPF) regeneration

    Science.gov (United States)

    Gonze, Eugene V; Ament, Frank

    2013-12-31

    An exhaust system that processes exhaust generated by an engine includes a diesel particulate filter (DPF) that is disposed downstream of the engine and that filters particulates from the exhaust. An electrical heater is disposed upstream of the DPF and selectively heats the exhaust to initiate combustion of the particulates within the exhaust as it passes therethrough. Heat generated by combustion of the particulates induces combustion of particulates within the DPF.

  11. Genetic Algorithm Design of a 3D Printed Heat Sink

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Tong [ORNL; Ozpineci, Burak [ORNL; Ayers, Curtis William [ORNL

    2016-01-01

    In this paper, a genetic algorithm- (GA-) based approach is discussed for designing heat sinks based on total heat generation and dissipation for a pre-specified size andshape. This approach combines random iteration processesand genetic algorithms with finite element analysis (FEA) to design the optimized heat sink. With an approach that prefers survival of the fittest , a more powerful heat sink can bedesigned which can cool power electronics more efficiently. Some of the resulting designs can only be 3D printed due totheir complexity. In addition to describing the methodology, this paper also includes comparisons of different cases to evaluate the performance of the newly designed heat sinkcompared to commercially available heat sinks.

  12. Sources and sinks of carbon dioxide in the Arctic regions

    Energy Technology Data Exchange (ETDEWEB)

    Gosink, T. A.; Kelley, J. J.

    1982-01-01

    The data base required to adequately ascertain seasonal source and sink strengths in the arctic regions is difficult to obtain. However, there are now a reasonable quantity of data for this polar region to estimate sources and sinks within the Arctic which may contribute significantly to the annual tropospheric CO/sub 2/ concentration fluctuation. The sea-ice-air and the sea-air interfaces account for most of the contribution to the sources and sinks for carbon dioxide. Although the arctic and subarctic region is small in extent, it certainly is not impervious and ice sealed. Our estimate, based on historical data and current research, indicates that the Arctic, which is about 4% of the earth's surface, is an annual net sink for approx. 10/sup 15/ g CO/sub 2/ accounting for an equivalent of approx. 3% of the annual anthropogenic contribution of CO/sub 2/ to the troposphere.

  13. Efficient Information Dissemination in Wireless Sensor Networks using Mobile Sinks

    National Research Council Canada - National Science Library

    Vincze, Zoltan; Vidacs, Attila; Vida, Rolland

    2006-01-01

    ...; therefore, relaying information between sensors and a sink node, possibly over multiple wireless hops, in an energy-efficient manner is a challenging task that preoccupies the research community for some time now...

  14. Using Stable Isotopes to Link Nutrient Sources in the Everglades and Biological Sinks in Florida Bay: A Biogeochemical Approach to Evaluate Ecosystem Response to Changing Nutrient Regimes

    Science.gov (United States)

    Hoare, A. M.; Hollander, D. J.; Heil, C.; Glibert, P.; Murasko, S.; Revilla, M.; Alexander, J.

    2005-05-01

    Anthropogenic influences in South Florida have led to deterioration of its two major ecosystems, the Everglades wetlands and the Florida Bay estuary. Consequently, the Comprehensive Everglades Restoration Plan has been proposed to restore the Everglades ecosystem; however, restoration efforts will likely exert new ecological changes in the Everglades and ultimately Florida Bay. The success of the Florida Everglades restoration depends on our understanding and ability to predict how regional changes in the distribution and composition of dissolved organic and inorganic nutrients will direct the downstream biogeochemical dynamics of Florida Bay. While the transport of freshwater and nutrients to Florida Bay have been studied, much work remains to directly link nutrient dynamics in Florida Bay to nutrient sources in the Everglades. Our study uses stable C and N isotopic measurements of chemical and biological materials from the Everglades and Florida Bay as part of a multi-proxy approach to link nutrient sources in the Everglades to biological sinks in Florida Bay. Isotopic analyses of dissolved and particulate species of water, aquatic vegetation and sedimentary organic matter show that the watersheds within the Everglades are chemically distinct and that these signatures are also reflected in the bay. A large east-west gradient in both carbon and nitrogen (as much as 10‰ for δ15N POM) reflect differing nutrient sources for each region of Florida Bay and is strongly correlated with upstream sources in the Everglades. Isotopic signatures also reflect seasonal relationships associated with wet and dry periods. High C and N measurements of DOM and POM measurements suggest significant influence from waste water in Canal C-111 in eastern Florida Bay, particularly during the dry season. These observations show that nutrients from the Everglades watersheds enter Florida Bay and are important in controlling biogeochemical processes in the bay. This study proves that

  15. Heat sink management during CANDU low level operation

    International Nuclear Information System (INIS)

    Wang Liansheng

    2008-01-01

    This paper introduces the practice of low-level operation with opening on the main heat transport system during an outage for a Candu-6 nuclear power plant, analyses the risks of losing heat sink during this condition, and points out the safety measures and management requirement for controlling such risks. This paper can be used as a reference for improving and optimizing the heat sink management for the coming outages. (author)

  16. Sinking and fit of abutment of locking taper implant system

    Science.gov (United States)

    Moon, Seung-Jin; Kim, Hee-Jung; Son, Mee-Kyoung

    2009-01-01

    STATEMENT OF PROBLEM Unlike screw-retention type, fixture-abutment retention in Locking taper connection depends on frictional force so it has possibility of abutment to sink. PURPOSE In this study, Bicon® Implant System, one of the conical internal connection implant system, was used with applying loading force to the abutments connected to the fixture. Then the amount of sinking was measured. MATERIAL AND METHODS 10 Bicon® implant fixtures were used. First, the abutment was connected to the fixture with finger force. Then it was tapped with a mallet for 3 times and loads of 20 kg corresponding to masticatory force using loading application instrument were applied successively. The abutment state, slightly connected to the fixture without pressure was considered as a reference length, and every new abutment length was measured after each load's step was added. The amount of abutment sinking (mm) was gained by subtracting the length of abutment-fixture under each loading condition from reference length. RESULTS It was evident, that the amount of abutment sinking in Bicon® Implant System increased as loads were added. When loads of 20 kg were applied more than 5 - 7 times, sinking stopped at 0.45 ± 0.09 mm. CONCLUSION Even though locking taper connection type implant shows good adaption to occlusal force, it has potential for abutment sinking as loads are given. When locking taper connection type implant is used, satisfactory loads are recommended for precise abutment location. PMID:21165262

  17. Sink- or Source-driven Phanerozoic carbon cycle?

    Science.gov (United States)

    Godderis, Y.; Donnadieu, Y.; Maffre, P.; Carretier, S.

    2017-12-01

    The Phanerozoic evolution of the atmospheric CO2 level is controlled by the fluxes entering or leaving the exospheric system. Those fluxes (including continental weathering, magmatic degassing, organic carbon burial, oxidation of sedimentary organic carbon) are intertwined, and their relative importance in driving the global carbon cycle evolution may have fluctuated through time. Deciphering the causes of the Phanerozoic climate evolution thus requires a holistic and quantitative approach. Here we focus on the role played by the paleogeographic configuration on the efficiency of the CO2 sink by continental silicate weathering, and on the impact of the magmatic degassing of CO2. We use the spatially resolved numerical model GEOCLIM (geoclimmodel.worpress.com) to compute the response of the silicate weathering and atmospheric CO2 to continental drift for 22 time slices of the Phanerozoic. Regarding the CO2 released by the magmatic activity, we reconstruct several Phanerozoic histories of this flux, based on published indexes. We calculate the CO2 evolution for each degassing scenario, and accounting for the paleogeographic setting. We show that the paleogeographic setting is a main driver of the climate from 540 Ma to about the beginning of the Jurassic. Regarding the role of the magmatic degassing, the various reconstructions do not converge towards a single signal, and thus introduce large uncertainties in the calculated CO2 level over time. Nevertheless, the continental dispersion, which prevails since the Jurassic, promotes the CO2 consumption by weathering and forces atmospheric CO2 to stay low. Warm climates of the "middle" Cretaceous and early Cenozoic require enhanced CO2 degassing by magmatic activity. In summary, the Phanerozoic climate evolution can be hardly assigned to a single process, but is the result of complex and intertwined processes.

  18. Biological mechanisms and translocation kinetics of particulate plutonium

    International Nuclear Information System (INIS)

    Bruenger, F.W.; Stevens, W.; Atherton, D.R.; Roswell, R.L.; Smith, J.M.

    1981-01-01

    The dissolution and elimination of particulate 239 Pu from its initial sites of deposition in phagocytic organs (the liver, spleen, and lung), as well as its translocation and redeposition in soft tissue organs and skeleton have been investigated. Beagles were injected intravenously with particulate Pu and sacrificed sequentially at times ranging from 33 to 830 days after injection. Equations that describe the overall retention of Pu in liver, spleen, lung, and bone were calculated. Plutonium mobilized from these organs either re-entered the blood stream and redeposited in the skeleton and liver parenchyma or was excreted. The protracted translocation of Pu to bone surfaces potentially exposes all cells involved in osteogenesis to continuous α-radiation, a situation that could enhance the hazard of developing osteosarcoma. A kinetic model that describes the translocation of Pu from the phagocytic compartments to blood and its subsequent redistribution to bone, liver, and other organs was formulated

  19. Particulate carbon in the atmosphere

    International Nuclear Information System (INIS)

    Surakka, J.

    1992-01-01

    Carbonaceous aerosols are emitted to the atmosphere in combustion processes. Carbon particles are very small and have a long residence time in the air. Black Carbon, a type of carbon aerosol, is a good label when transport of combustion emissions in the atmosphere is studied. It is also useful tool in air quality studies. Carbon particles absorb light 6.5 to 8 times stronger than any other particulate matter in the air. Their effect on decreasing visibility is about 50 %. Weather disturbances are also caused by carbon emissions e.g. in Kuwait. Carbon particles have big absorption surface and capacity to catalyze different heterogenous reactions in air. Due to their special chemical and physical properties particulate carbon is a significant air pollution specie, especially in urban air. Average particulate carbon concentration of 5.7 μg/m 2 have been measured in winter months in Helsinki

  20. Characterization of the particulate air pollution in contrasted mega cities

    International Nuclear Information System (INIS)

    Favez, O.

    2008-02-01

    This work aims at characterizing the physics and the chemistry that govern particulate air pollution in two mega cities (Paris and Cairo) for which the size distribution and the chemical composition of airborne particles were poorly documented. Seasonal variations of the main aerosol sources and transformation processes are investigated in these two urban centres, with a particular attention to semi-volatile material and secondary organic aerosols. Short-term health effects of Paris size-segregated aerosols, as well as particulate pollution during the Cairo 'Black Cloud' season, are also emphasized here. Finally, the comparison of results obtained for the two mega cities and for another one (Beijing) allows investigating main factors responsible for particulate air pollution in urban centres with contrasted climatic conditions and development levels. Notably, this work also allows the build-up of an experimental dataset which is now available for the modelling of urban air quality and of environmental impacts of mega city air pollution. (author)

  1. Understanding particulate coating microstructure development

    Science.gov (United States)

    Roberts, Christine Cardinal

    How a dispersion of particulates suspended in a solvent dries into a solid coating often is more important to the final coating quality than even its composition. Essential properties like porosity, strength, gloss, particulate order, and concentration gradients are all determined by the way the particles come together as the coating dries. Cryogenic scanning electron microscopy (cryoSEM) is one of the most effective methods to directly visualize a drying coating during film formation. Using this method, the coating is frozen, arresting particulate motion and solidifying the sample so that it be imaged in an SEM. In this thesis, the microstructure development of particulate coatings was explored with several case studies. First, the effect of drying conditions was determined on the collapse of hollow latex particles, which are inexpensive whiteners for paint. Using cryoSEM, it was found that collapse occurs during the last stages of drying and is most likely to occur at high drying temperatures, humidity, and with low binder concentration. From these results, a theoretical model was proposed for the collapse of a hollow latex particle. CryoSEM was also used to verify a theoretical model for the particulate concentration gradients that may develop in a coating during drying for various evaporation, sedimentation and particulate diffusion rates. This work created a simple drying map that will allow others to predict the character of a drying coating based on easily calculable parameters. Finally, the effect of temperature on the coalescence and cracking of latex coatings was explored. A new drying regime for latex coatings was identified, where partial coalescence of particles does not prevent cracking. Silica was shown to be an environmentally friendly additive for preventing crack formation in this regime.

  2. Production of Dissolved Organic Matter During Doliolid Feeding

    Science.gov (United States)

    Castellane, N. J.; Paffenhofer, G. A.; Stubbins, A.

    2016-02-01

    The biological carbon pump (BCP) draws carbon dioxide out of the atmosphere and buries it at the seafloor. The efficiency of the BCP is determined in part by the sinking rates of particulate organic carbon (POC) from ocean surface waters. Zooplankton can package POC into fecal pellets with higher sinking rates than their food source (e.g. phytoplankton), increasing the efficiency of the BCP. However, dissolved organic carbon (DOC) is also produced as zooplankton ingest and egest food, reducing the efficiency of BCP. The pelagic tunicate Dolioletta gegenbauri (doliolid) is a gelatinous zooplankton found at high concentrations in shelf waters, including our study site: the South Atlantic Bight. Doliolids are efficient grazers capable of stripping large quantities of phytoplankton from the water column. To determine the balance between pellet formation and DOC production during feeding, doliolids (6-7 mm gonozooids) were placed in natural seawater amended with a live phytoplankton food source and incubated on a plankton wheel. Dissolved organic matter (DOM) released directly to the water as well as the water soluble fraction of pellet organic matter were quantified and optically characterized. Colored dissolved organic matter (CDOM) absorbance and fluorescence spectra revealed that doliolid feeding produces DOM with optical properties that are commonly indicative of newly produced, highly biolabile DOM of microbial origin. Based upon these optical characteristics, doliolid-produced DOM is expected to be highly bio-labile in the environment and therefore rapidly degraded by surface ocean microbes shunting phytoplankton-derived organic carbon out of the BCP and back to dissolved inorganic carbon.

  3. Acetone in the atmosphere: Distribution, sources, and sinks

    Science.gov (United States)

    Singh, H. B.; O'Hara, D.; Herlth, D.; Sachse, W.; Blake, D. R.; Bradshaw, J. D.; Kanakidou, M.; Crutzen, P. J.

    1994-01-01

    Acetone (CH3COCH3) was found to be the dominant nonmethane organic species present in the atmosphere sampled primarily over eastern Canada (0-6 km, 35 deg-65 deg N) during ABLE3B (July to August 1990). A concentration range of 357 to 2310 ppt (= 10(exp -12) v/v) with a mean value of 1140 +/- 413 ppt was measured. Under extremely clean conditions, generally involving Arctic flows, lowest (background) mixing ratios of 550 +/- 100 ppt were present in much of the troposphere studied. Correlations between atmospheric mixing ratios of acetone and select species such as C2H2, CO, C3H8, C2Cl4 and isoprene provided important clues to its possible sources and to the causes of its atmospheric variability. Biomass burning as a source of acetone has been identified for the first time. By using atmospheric data and three-dimensional photochemical models, a global acetone source of 40-60 Tg (= 10(exp 12) g)/yr is estimated to be present. Secondary formation from the atmospheric oxidation of precursor hydrocarbons (principally propane, isobutane, and isobutene) provides the single largest source (51%). The remainder is attributable to biomass burning (26%), direct biogenic emissions (21%), and primary anthropogenic emissions (3%). Atmospheric removal of acetone is estimated to be due to photolysis (64%), reaction with OH radicals (24%), and deposition (12%). Model calculations also suggest that acetone photolysis contributed significantly to PAN formation (100-200 ppt) in the middle and upper troposphere of the sampled region and may be important globally. While the source-sink equation appears to be roughly balanced, much more atmospheric and source data, especially from the southern hemisphere, are needed to reliably quantify the atmospheric budget of acetone.

  4. Long-term decline of the Amazon carbon sink.

    Science.gov (United States)

    Brienen, R J W; Phillips, O L; Feldpausch, T R; Gloor, E; Baker, T R; Lloyd, J; Lopez-Gonzalez, G; Monteagudo-Mendoza, A; Malhi, Y; Lewis, S L; Vásquez Martinez, R; Alexiades, M; Álvarez Dávila, E; Alvarez-Loayza, P; Andrade, A; Aragão, L E O C; Araujo-Murakami, A; Arets, E J M M; Arroyo, L; Aymard C, G A; Bánki, O S; Baraloto, C; Barroso, J; Bonal, D; Boot, R G A; Camargo, J L C; Castilho, C V; Chama, V; Chao, K J; Chave, J; Comiskey, J A; Cornejo Valverde, F; da Costa, L; de Oliveira, E A; Di Fiore, A; Erwin, T L; Fauset, S; Forsthofer, M; Galbraith, D R; Grahame, E S; Groot, N; Hérault, B; Higuchi, N; Honorio Coronado, E N; Keeling, H; Killeen, T J; Laurance, W F; Laurance, S; Licona, J; Magnussen, W E; Marimon, B S; Marimon-Junior, B H; Mendoza, C; Neill, D A; Nogueira, E M; Núñez, P; Pallqui Camacho, N C; Parada, A; Pardo-Molina, G; Peacock, J; Peña-Claros, M; Pickavance, G C; Pitman, N C A; Poorter, L; Prieto, A; Quesada, C A; Ramírez, F; Ramírez-Angulo, H; Restrepo, Z; Roopsind, A; Rudas, A; Salomão, R P; Schwarz, M; Silva, N; Silva-Espejo, J E; Silveira, M; Stropp, J; Talbot, J; ter Steege, H; Teran-Aguilar, J; Terborgh, J; Thomas-Caesar, R; Toledo, M; Torello-Raventos, M; Umetsu, R K; van der Heijden, G M F; van der Hout, P; Guimarães Vieira, I C; Vieira, S A; Vilanova, E; Vos, V A; Zagt, R J

    2015-03-19

    Atmospheric carbon dioxide records indicate that the land surface has acted as a strong global carbon sink over recent decades, with a substantial fraction of this sink probably located in the tropics, particularly in the Amazon. Nevertheless, it is unclear how the terrestrial carbon sink will evolve as climate and atmospheric composition continue to change. Here we analyse the historical evolution of the biomass dynamics of the Amazon rainforest over three decades using a distributed network of 321 plots. While this analysis confirms that Amazon forests have acted as a long-term net biomass sink, we find a long-term decreasing trend of carbon accumulation. Rates of net increase in above-ground biomass declined by one-third during the past decade compared to the 1990s. This is a consequence of growth rate increases levelling off recently, while biomass mortality persistently increased throughout, leading to a shortening of carbon residence times. Potential drivers for the mortality increase include greater climate variability, and feedbacks of faster growth on mortality, resulting in shortened tree longevity. The observed decline of the Amazon sink diverges markedly from the recent increase in terrestrial carbon uptake at the global scale, and is contrary to expectations based on models.

  5. Phase Change Material Heat Sink for an ISS Flight Experiment

    Science.gov (United States)

    Quinn, Gregory; Stieber, Jesse; Sheth, Rubik; Ahlstrom, Thomas

    2015-01-01

    A flight experiment is being constructed to utilize the persistent microgravity environment of the International Space Station (ISS) to prove out operation of a microgravity compatible phase change material (PCM) heat sink. A PCM heat sink can help to reduce the overall mass and volume of future exploration spacecraft thermal control systems (TCS). The program is characterizing a new PCM heat sink that incorporates a novel phase management approach to prevent high pressures and structural deformation that often occur with PCM heat sinks undergoing cyclic operation in microgravity. The PCM unit was made using brazed aluminum construction with paraffin wax as the fusible material. It is designed to be installed into a propylene glycol and water cooling loop, with scaling consistent with the conceptual designs for the Orion Multipurpose Crew Vehicle. This paper reports on the construction of the PCM heat sink and on initial ground test results conducted at UTC Aerospace Systems prior to delivery to NASA. The prototype will be tested later on the ground and in orbit via a self-contained experiment package developed by NASA Johnson Space Center to operate in an ISS EXPRESS rack.

  6. Source/process apportionment of major and trace elements in sinking particles in the Sargasso sea

    Science.gov (United States)

    Huang, S.; Conte, M. H.

    2009-01-01

    Elemental composition of the particle flux at the Oceanic Flux Program (OFP) time-series site off Bermuda was measured from January 2002 to March 2005. Eighteen elements (Mg, Al, Si, P, Ca, Sc, Ti, V, Mn, Fe, Co, Ni, Cu, Zn, Sr, Cd, Ba and Pb) in sediment trap material from 500, 1500 and 3200 m depths were quantified using fusion-HR-ICPMS. Positive Matrix Factorization (PMF) was used to elucidate sources, elemental associations and processes that affect geochemical behavior in the water column. Results provide evidence for intense elemental cycling between the sinking flux material and the dissolved and suspended pools within mesopelagic and bathypelagic waters. Biological processing and remineralization rapidly deplete the sinking flux material in organic matter and associated elements (N, P, Cd, Zn) between 500 and 1500 m depth. Suspended particle aggregation, authigenic mineral precipitation, and chemical scavenging enriches the flux material in lithogenic minerals, barite and redox sensitive elements (Mn, Co, V, Fe). A large increase in the flux of lithogenic elements is observed with depth and confirms that the northeast Sargasso is a significant sink for advected continental materials, likely supplied via Gulf Stream circulation. PMF resolved major sources that contribute to sinking flux at all depths (carbonate, high-Mg carbonate, opal, organic matter, lithogenic material, and barite) as well as additional depth-specific elemental associations that contribute about half of the compositional variability in the flux. PMF solutions indicate close geochemical associations of barite-opal, Cd-P, Zn-Co, Zn-Pb and redox sensitive elements in the sinking flux material at 500 m depth. Major reorganizations of element associations occur as labile carrier phases break down and elements redistribute among new carrier phases deeper in the water column. Factor scores show strong covariation and similar temporal phasing among the three trap depths and indicate a tight

  7. [Corruption as individual and organizational sinking].

    Science.gov (United States)

    Cecchinato, Fabio

    2015-04-01

    The article qualifies the nature of psychosociological perspective in analysing corruption in organizations. Corruption is analysed as a mental event and social conditions of corruption are investigated. In particular six social and organizational factors are identified as relevant in determining the diffusion of corruption: meaning, work wellbeing, consistency, social recognition, reflexivity, social relations. The main hypothesis explored in the article is that to take managerial care of the organisational factors above mentioned is a strong and active prevention of the risk of corruption.

  8. Phytoplankton Do Not Produce Carbon-Rich Organic Matter in High CO2 Oceans

    Science.gov (United States)

    Kim, Ja-Myung; Lee, Kitack; Suh, Young-Sang; Han, In-Seong

    2018-05-01

    The ocean is a substantial sink for atmospheric carbon dioxide (CO2) released as a result of human activities. Over the coming decades the dissolved inorganic C concentration in the surface ocean is predicted to increase, which is expected to have a direct influence on the efficiency of C utilization (consumption and production) by phytoplankton during photosynthesis. Here we evaluated the generality of C-rich organic matter production by examining the elemental C:N ratio of organic matter produced under conditions of varying pCO2. The data used in this analysis were obtained from a series of pelagic in situ pCO2 perturbation studies that were performed in the diverse ocean regions and involved natural phytoplankton assemblages. The C:N ratio of the resulting particulate and dissolved organic matter did not differ across the range of pCO2 conditions tested. In particular, the ratio for particulate organic C and N was found to be 6.58 ± 0.05, close to the theoretical value of 6.6.

  9. Allochthonous subsidies of organic matter across a lake-river-fjord landscape in the Chilean Patagonia: Implications for marine zooplankton in inner fjord areas

    Science.gov (United States)

    Vargas, Cristian A.; Martinez, Rodrigo A.; San Martin, Valeska; Aguayo, Mauricio; Silva, Nelson; Torres, Rodrigo

    2011-03-01

    Ecosystems can act as both sources and sinks of allochthonous nutrients and organic matter. In this sense, fjord ecosystems are a typical interface and buffer zone between freshwater systems, glaciated continents, and the coastal ocean. In order to evaluate the potential sources and composition of organic matter across fjord ecosystems, we characterized particulate organic matter along a lake-river-fjord corridor in the Chilean Patagonia using stable isotope (δ 13C) and lipid (fatty acid composition) biomarker analyses. Furthermore, estimates of zooplankton carbon ingestion rates and measurements of δ 13C and δ 15N in zooplankton (copepods) were used to evaluate the implications of allochthonous subsidies for copepods inhabiting inner fjord areas. Our results showed that riverine freshwater flows contributed an important amount of dissolved silicon but, scarce nitrate and phosphate to the brackish surface layer of the fjord ecosystem. Isotopic signatures of particulate organic matter from lakes and rivers were distinct from their counterparts in oceanic influenced stations. Terrestrial allochthonous sources could support around 68-86% of the particulate organic carbon in the river plume and glacier melting areas, whereas fatty acid concentrations were maximal in the surface waters of the Pascua and Baker river plumes. Estimates of carbon ingestion rates and δ 13C in copepods from the river plume areas indicated that terrestrial carbon could account for a significant percentage of the copepod body carbon (20-50%) during periods of food limitation. Particulate organic matter from the Pascua River showed a greater allochthonous contribution of terrigenous/vascular plant sources. Rivers may provide fjord ecosystems with allochthonous contributions from different sources because of the distinct vegetation coverage and land use along each river's watershed. These observations have significant implications for the management of local riverine areas in the context of

  10. CDC WONDER: Daily Fine Particulate Matter

    Data.gov (United States)

    U.S. Department of Health & Human Services — The Daily Fine Particulate Matter data available on CDC WONDER are geographically aggregated daily measures of fine particulate matter in the outdoor air, spanning...

  11. Mercury partition in the interface between a contaminated lagoon and the ocean: The role of particulate load and composition

    International Nuclear Information System (INIS)

    Pato, P.; Otero, M.; Valega, M.; Lopes, C.B.; Pereira, M.E.; Duarte, A.C.

    2010-01-01

    After having estimated the patterns of flow to the ocean and found some seasonal and tidal differences, mainly with regard to the relative importance of dissolved and particulate fractions, mercury partitioning at the interface between a contaminated lagoon and the Atlantic Ocean was investigated during four tidal cycles in contrasting season and tidal regimes. Mercury was found to be located predominantely in the particulate fraction throughout the year, contributing to its retention within the system. Seasonal conditions, variations in marine and fluvial signals and processes affecting bed sediment resuspension influenced the character and concentration of suspended particulate matter in the water column. Variation in the nature, levels and partitioning of organic carbon in the particulate fraction affected levels of particulate mercury as well as mercury partitioning. These results highlight the dominant role of suspended particulate matter in the distribution of anthropogenic mercury and reinforce the importance of competitive behavior related to organic carbon in mercury scavenging.

  12. Design consideration for a diversity of heat sink

    Energy Technology Data Exchange (ETDEWEB)

    Rueckbrodt, Karin; Meischak, Stefan [AREVA NP GmbH, Erlangen (Germany)

    2013-07-01

    The defense in depth approach requires in all cases to prevent and mitigate accidents that could release radioactive materials. To assure the physical design barriers (preserve fuel integrity, reactor coolant pressure boundary integrity, and containment integrity) the decay heat has to be removed. External and internal events have to be taken in consideration for the robustness of all the involved cooling systems. To ensure the cooling function in all conceivable and all unlikely events an analysis for the necessity of a diversified heat sink is essential. The diversified concepts analyses the type of the primary heat sink and use contrary sources for the heat sink, air instead of water, well instead of a river. A complete diversity is realized if also for the heat transfer diversified systems are implemented. The described solutions are mainly applied for BWR plants, but can be partly transferred analogously to PWR plants. (orig.)

  13. Optimization of triangular microchannel heat sinks using constructible theory

    International Nuclear Information System (INIS)

    Mardani, Moloud; Salimpour, Mohammad Reza

    2016-01-01

    The present paper examines the optimization of triangular microchannel heat sinks. The impact of volume fraction of solid material and pressure drop on the maximum temperature of the microchannel heat sinks are investigated and their optimum operating conditions are compared. From the results, it is seen that increasing the side angle of the triangular microchannel, improves its performance. Furthermore, there is an appropriate agreement between the analytical and numerical results. Finally, the effect of degrees of freedom on the performance of microchannels is investigated. To accomplish this end, the triangular microchannels with the side angle of 60 degree have been chosen as it has the best performance compared to other microchannels. It is observed that the minimized maximum temperatures of optimized microchannel heat sinks with three degrees of freedom are 10% lower than the ones with two degrees of freedom

  14. Development and testing of aluminum micro channel heat sink

    Science.gov (United States)

    Kumaraguruparan, G.; Sornakumar, T.

    2010-06-01

    Microchannel heat sinks constitute an innovative cooling technology for the removal of a large amount of heat from a small area and are suitable for electronics cooling. In the present work, Tool Steel D2 grade milling slitting saw type plain milling cutter is fabricated The microchannels are machined in aluminum work pieces to form the microchannel heat sink using the fabricated milling cutter in an horizontal milling machine. A new experimental set-up is fabricated to conduct the tests on the microchannel heat sink. The heat carried by the water increases with mass flow rate and heat input. The heat transfer coefficient and Nusselt number increases with mass flow rate and increased heat input. The pressure drop increases with Reynolds number and decreases with input heat. The friction factor decreases with Reynolds number and decreases with input heat. The thermal resistance decreases with pumping power and decreases with input heat.

  15. Review of tribological sinks in six major industries

    Energy Technology Data Exchange (ETDEWEB)

    Imhoff, C.H.; Brown, D.R.; Hane, G.J.; Hutchinson, R.A.; Erickson, R.; Merriman, T.; Gruber, T.; Barber, S.

    1985-09-01

    Friction and material wear occur throughout all industries and are involved in many processes within each industry. These conditions make assessing tribological activity overall in industry very complex and expensive. Therefore, a research strategy to obtain preliminary information on only the most significant industrial tribological sinks was defined. The industries examined were selected according to both the magnitude of overall energy consumption (particularly machine drive) and the known presence of significant tribological sinks. The six industries chosen are as follows: mining, agriculture, primary metals, chemicals/refining, food, and pulp and paper. They were reviewed to identify and characterize the major tribology sinks. It was concluded that wear losses are greater than friction losses, and that reducing wear rates would improve industrial productivity.

  16. Bounds on the dynamics of sink populations with noisy immigration.

    Science.gov (United States)

    Eager, Eric Alan; Guiver, Chris; Hodgson, Dave; Rebarber, Richard; Stott, Iain; Townley, Stuart

    2014-03-01

    Sink populations are doomed to decline to extinction in the absence of immigration. The dynamics of sink populations are not easily modelled using the standard framework of per capita rates of immigration, because numbers of immigrants are determined by extrinsic sources (for example, source populations, or population managers). Here we appeal to a systems and control framework to place upper and lower bounds on both the transient and future dynamics of sink populations that are subject to noisy immigration. Immigration has a number of interpretations and can fit a wide variety of models found in the literature. We apply the results to case studies derived from published models for Chinook salmon (Oncorhynchus tshawytscha) and blowout penstemon (Penstemon haydenii). Copyright © 2013 Elsevier Inc. All rights reserved.

  17. A model for bacterial colonization of sinking aggregates.

    Science.gov (United States)

    Bearon, R N

    2007-01-01

    Sinking aggregates provide important nutrient-rich environments for marine bacteria. Quantifying the rate at which motile bacteria colonize such aggregations is important in understanding the microbial loop in the pelagic food web. In this paper, a simple analytical model is presented to predict the rate at which bacteria undergoing a random walk encounter a sinking aggregate. The model incorporates the flow field generated by the sinking aggregate, the swimming behavior of the bacteria, and the interaction of the flow with the swimming behavior. An expression for the encounter rate is computed in the limit of large Péclet number when the random walk can be approximated by a diffusion process. Comparison with an individual-based numerical simulation is also given.

  18. Host country attractiveness for CDM non-sink projects

    International Nuclear Information System (INIS)

    Jung, Martina

    2006-01-01

    In the present study, CDM host countries are classified according to their attractiveness for CDM non-sink projects by using cluster analysis. The attractiveness of host countries for CDM non-sink projects is described by three indicators: mitigation potential, institutional CDM capacity and general investment climate. The results suggest that only a small proportion of potential host countries will attract most of the CDM investment. The CDM (non-sink) stars are China, India, Brazil, Argentina, Mexico, South Africa, Indonesia and Thailand. They are followed by attractive countries like Costa Rica, Trinidad and Tobago, Mongolia, Panama, and Chile. While most of the promising CDM host countries are located in Latin America and Asia, the general attractiveness of African host countries is relatively low (with the exception of South Africa). Policy implications of this rather inequitable geographical distribution of CDM project activities are discussed briefly

  19. Particulate Matter: a closer look

    NARCIS (Netherlands)

    Buijsman E; Beck JP; Bree L van; Cassee FR; Koelemeijer RBA; Matthijsen J; Thomas R; Wieringa K; LED; MGO

    2005-01-01

    The summary in booklet form 'Fijn stof nader bekeken' (Particulate Matter: a closer look) , published in Dutch by the Netherlands Environmental Assessment Agency (MNP) and the Environment and Safety Division of the National Institute for Public Health and the Environment (RIVM), has been designed to

  20. Transport phenomena in particulate systems

    CERN Document Server

    Freire, José Teixeira; Ferreira, Maria do Carmo

    2012-01-01

    This volume spans 10 chapters covering different aspects of transport phenomena including fixed and fluidized systems, spouted beds, electrochemical and wastewater treatment reactors. This e-book will be valuable for students, engineers and researchers aiming to keep updated on the latest developments on particulate systems.

  1. Two decades of ocean CO2 sink and variability

    International Nuclear Information System (INIS)

    Quere, C. Le; Bopp, L.; Heimann, M.; Prentice, I.C.; Aumont, O.; Bousquet, P.; Ciais, P.; Francey, R.; Rayner, P.J.; Keeling, C.D.; Keeling, R.F.; Piper, S.C.; Kheshgi, H.; Peyliln, P.

    2003-01-01

    Atmospheric CO 2 has increased at a nearly identical average rate of 3.3 and 3.2 Pg C/yr for the decades of the 1980s and the 1990s, in spite of a large increase in fossil fuel emissions from 5.4 to 6.3 Pg C/yr. Thus, the sum of the ocean and land CO 2 sinks was 1 Pg C/yr larger in the 1990s than in to the 1980s. Here we quantify the ocean and land sinks for these two decades using recent atmospheric inversions and ocean models. The ocean and land sinks are estimated to be, respectively, 0.3 (0.1 to 0.6) and 0.7 (0.4 to 0.9) Pg C/yr larger in the 1990s than in the 1980s. When variability less than 5 yr is removed, all estimates show a global oceanic sink more or less steadily increasing with time, and a large anomaly in the land sink during 1990-1994. For year-to-year variability, all estimates show 1/3 to 1/2 less variability in the ocean than on land, but the amplitude and phase of the oceanic variability remain poorly determined. A mean oceanic sink of 1.9 Pg C/yr for the 1990s based on O 2 observations corrected for ocean outgassing is supported by these estimates, but an uncertainty on the mean value of the order of ±0.7 Pg C/yr remains. The difference between the two decades appears to be more robust than the absolute value of either of the two decades

  2. Trends and regional distributions of land and ocean carbon sinks

    Directory of Open Access Journals (Sweden)

    J. L. Sarmiento

    2010-08-01

    Full Text Available We show here an updated estimate of the net land carbon sink (NLS as a function of time from 1960 to 2007 calculated from the difference between fossil fuel emissions, the observed atmospheric growth rate, and the ocean uptake obtained by recent ocean model simulations forced with reanalysis wind stress and heat and water fluxes. Except for interannual variability, the net land carbon sink appears to have been relatively constant at a mean value of −0.27 Pg C yr−1 between 1960 and 1988, at which time it increased abruptly by −0.88 (−0.77 to −1.04 Pg C yr−1 to a new relatively constant mean of −1.15 Pg C yr−1 between 1989 and 2003/7 (the sign convention is negative out of the atmosphere. This result is detectable at the 99% level using a t-test. The land use source (LU is relatively constant over this entire time interval. While the LU estimate is highly uncertain, this does imply that most of the change in the net land carbon sink must be due to an abrupt increase in the land sink, LS = NLS – LU, in response to some as yet unknown combination of biogeochemical and climate forcing. A regional synthesis and assessment of the land carbon sources and sinks over the post 1988/1989 period reveals broad agreement that the Northern Hemisphere land is a major sink of atmospheric CO2, but there remain major discrepancies with regard to the sign and magnitude of the net flux to and from tropical land.

  3. Particulate COD balance of particulate cod in eletrocuagulation/flotation reactor treating tannery effluent

    Directory of Open Access Journals (Sweden)

    Rodrigo Babora Borri

    2012-04-01

    Full Text Available Mass balance or particulate organic matter was studied in terms of COD, by means of electrocoagulation/flotation (ECF reactor treating tannery effluent. Reactor was operated in fill and draw (batch mode. Operating in hydraulic residence time of 65 minutes, ECF reactor reached 55 % COD removal. Although volatile solids were also removed from liquid phase (removal of 40%, fixed solids concentration, and hence total solids concentration, showed to be higher in withdrawn effluent than in ECF’s influent. This was assigned to NaCl added in order to enhance conductivity in wastewater.

  4. Inventory of primary particulates emissions; Inventaire des emissions de particules primaires

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2001-12-01

    CITEPA carried out a national inventory on particulate emissions. This report presents the results of this study for a great number of sectors and it covers a larger number of sources than the previous CITEPA inventories on particles and some other inventories carried out by International organisms (TNO, IIASA). In particular, at the present time, fugitive dust emissions for some sources are rarely taken into account in inventories because of poor knowledge and they are still the subject of researches in order to validate the emission results. (author)

  5. New Method of Sinking Caisson Tunnel in Soft Soil

    OpenAIRE

    Bame, Abda Berisso

    2013-01-01

    Sinking a caisson tunnel in soft soil is new idea and this new concept could be an alternative method of tunneling in soft soil. The aim of this study is to evaluate geotechnical feasibility of sinking the caisson tunnel to the desired depth at the selected soil profile along tunnel alignment. This caisson tunneling method is proposed to reduce the use of temporary works such as propping of sheet pile walls and increase the ease and speed of construction. Besides, it reduces the disturbance o...

  6. ECONOMIC EVALUATION OF CO2 STORAGE AND SINK ENHANCEMENT OPTIONS

    Energy Technology Data Exchange (ETDEWEB)

    Bert Bock; Richard Rhudy; Howard Herzog; Michael Klett; John Davison; Danial G. De La Torre Ugarte; Dale Simbeck

    2003-02-01

    This project developed life-cycle costs for the major technologies and practices under development for CO{sub 2} storage and sink enhancement. The technologies evaluated included options for storing captured CO{sub 2} in active oil reservoirs, depleted oil and gas reservoirs, deep aquifers, coal beds, and oceans, as well as the enhancement of carbon sequestration in forests and croplands. The capture costs for a nominal 500 MW{sub e} integrated gasification combined cycle plant from an earlier study were combined with the storage costs from this study to allow comparison among capture and storage approaches as well as sink enhancements.

  7. Thorium-particulate matter interaction. Thorium complexing capacity of oceanic particulate matter: Theory

    International Nuclear Information System (INIS)

    Hirose, Katsumi; Tanque, Eiichiro

    1994-01-01

    The interaction between thorium and oceanic particulate matter was examined experimentally by using chemical equilibrium techniques. Thorium reacts quantitatively with the organic binding site of Particulate Matter (PM) in 0.1 mol/L HCl solution by complexation, which is equilibrated within 34 h. According to mass balance analysis, thorium forms a 1:1 complex with the organic binding site in PM, whose conditional stability constant is 10 6.6 L/mol. The Th adsorption ability is present even in 6.9 mol/L HCl solution although the amount of Th adsorption decreases with increasing acidity in the solution. Interferences to Th adsorption by Fe(III) suggests that other metals cannot react with PM in more than 0.1 mol/L HCl solutions when concentrations of other metals are the same level of Th. The competitive reaction between Th and Fe(III) occurs in higher Fe concentrations, which means that the organic binding site is nonspecific for Th. A vertical profile of Th complexing capacity of PM in the western North Pacific is characterized; that is, the Th complexing capacity shows a surface maximum and decreases rapidly with depth

  8. Particulate carbon and nitrogen determinations in tracer studies: The neglected variables

    International Nuclear Information System (INIS)

    Collos, Yves; Jauzein, Cécile; Hatey, Elise

    2014-01-01

    We address two issues in the determination of particulate carbon and nitrogen in suspended matter of aquatic environments. One is the adsorption of dissolved organic matter on filters, leading to overestimate particulate matter. The second is the material loss during filtration due to fragile algal cells breaking up. Examples from both laboratory cultures and natural samples are presented. We recommend using stacked filters in order to estimate the first and filtering different volumes of water in order to evaluate the second. - Highlights: • Adsorption of dissolved organic matter on GF/F filters saturates below 1 ml. • Such adsorption can overestimate (up to 5 fold at low volumes) particulate matter. • Plankton breakage during filtration underestimates (up to 3 fold) particulate matter. • Different volumes should be filtered to detect biases in PC and PN concentrations. • Adsorbed organic carbon is higher in surface ocean than in mid-waters

  9. Organics.

    Science.gov (United States)

    Chian, Edward S. K.; DeWalle, Foppe B.

    1978-01-01

    Presents water analysis literature for 1978. This review is concerned with organics, and it covers: (1) detergents and surfactants; (2) aliphatic and aromatic hydrocarbons; (3) pesticides and chlorinated hydrocarbons; and (4) naturally occurring organics. A list of 208 references is also presented. (HM)

  10. Organizers.

    Science.gov (United States)

    Callison, Daniel

    2000-01-01

    Focuses on "organizers," tools or techniques that provide identification and classification along with possible relationships or connections among ideas, concepts, and issues. Discusses David Ausubel's research and ideas concerning advance organizers; the implications of Ausubel's theory to curriculum and teaching; "webbing," a…

  11. Global modelling of the total OH reactivity: investigations on the “missing” OH sink and its atmospheric implications

    Directory of Open Access Journals (Sweden)

    V. Ferracci

    2018-05-01

    Full Text Available The hydroxyl radical (OH plays a crucial role in the chemistry of the atmosphere as it initiates the removal of most trace gases. A number of field campaigns have observed the presence of a missing OH sink in a variety of regions across the planet. A comparison of direct measurements of the OH loss frequency, also known as total OH reactivity (kOH, with the sum of individual known OH sinks (obtained via the simultaneous detection of species such as volatile organic compounds and nitrogen oxides indicates that, in some cases, up to 80 % of kOH is unaccounted for. In this work, the UM-UKCA chemistry-climate model was used to investigate the wider implications of the missing reactivity on the oxidising capacity of the atmosphere. Simulations of the present-day atmosphere were performed and the model was evaluated against an array of field measurements to verify that the known OH sinks were reproduced well, with a resulting good agreement found for most species. Following this, an additional sink was introduced to simulate the missing OH reactivity as an emission of a hypothetical molecule, X, which undergoes rapid reaction with OH. The magnitude and spatial distribution of this sink were underpinned by observations of the missing reactivity. Model runs showed that the missing reactivity accounted for on average 6 % of the total OH loss flux at the surface and up to 50 % in regions where emissions of the additional sink were high. The lifetime of the hydroxyl radical was reduced by 3 % in the boundary layer, whilst tropospheric methane lifetime increased by 2 % when the additional OH sink was included. As no OH recycling was introduced following the initial oxidation of X, these results can be interpreted as an upper limit of the effects of the missing reactivity on the oxidising capacity of the troposphere. The UM-UKCA simulations also allowed us to establish the atmospheric implications of the newly characterised reactions of peroxy

  12. Latest acquisition will sink to new depths

    International Nuclear Information System (INIS)

    Anon.

    1998-01-01

    The introduction of a state-of-the-art remotely operated vehicle (ROV) for use at Hibernia was presented. The ROV is a small submarine that is equipped with cameras, sonars and remote-operated robot arms. It is used to perform visual inspections of various components of the underwater equipment at Hibernia. The remotely operated arms make it possible to perform maintenance and repairs if necessary. The ROV will be used to check the entire network of subsea pipelines and valves in the offshore loading system to ensure that there are no leaks or unnecessary stresses on the system. It can also produce a visual record of the external ice wall of the gravity base structure from the surface to the ocean floor. The system can be mobilized in case of an emergency within 24 hours. Other organizations can also subcontract the ROV. 1 fig

  13. Organic carbon budget for the eastern boundary of the North Atlantic subtropical gyre: major role of DOC in mesopelagic respiration.

    Science.gov (United States)

    Santana-Falcón, Yeray; Álvarez-Salgado, Xosé Antón; Pérez-Hernández, María Dolores; Hernández-Guerra, Alonso; Mason, Evan; Arístegui, Javier

    2017-08-31

    Transports of suspended particulate (POC susp ) and dissolved (DOC) organic carbon are inferred from a box-model covering the eastern boundary of the North Atlantic subtropical gyre. Corresponding net respiration rates (R) are obtained from a net organic carbon budget that is based on the transport estimates, and includes both vertical and lateral fluxes. The overall R in the mesopelagic layer (100-1500 m) is 1.6 ± 0.4 mmol C m -2 d -1 . DOC accounts for up to 53% of R as a result of drawdown of organic carbon within Eastern North Atlantic Central Water (ENACW) that is entrained into sinking Mediterranean Overflow Water (MOW) that leads to formation of Mediterranean water (MW) at intermediate depths (~900 m). DOC represents 90% of the respired non-sinking organic carbon. When converted into oxygen units, the computed net respiration rate represents less than half the oxygen utilization rates (OUR) reported for the mesopelagic waters of the subtropical North Atlantic. Mesoscale processes in the area, not quantified with our approach, could account in part for the OUR differences observed between our carbon budget and other published studies from the North Atlantic, although seasonal or interannual variability could also be responsible for the difference in the estimates.

  14. 210Pb dating of sediments from the central and the northern Adriatic Sea: The deposition and preservation of sedimentary organic carbon

    International Nuclear Information System (INIS)

    Hamilton, T.; Fowler, S.; Miquel, J.C.; La Rosa, J.

    1996-04-01

    A central goal of the ELNA project is to assess the carbon assimilation capacity of the Northern Adriatic Sea. This requires fundamental quantitative information on budgets and sinks of organic carbon. Any change in carbon production in the water column should be reflected in the underlying sediments. Moreover, the fraction of particulate organic carbon reaching the sea floor which is subsequently preserved in the sediment will be strongly coupled to sediment accumulation and mixing. In this study a series of box cores were collected in order to characterize a hypothetical eutrophication gradient extending from the Po River outflow region in the north down to the shallow meso-Adriatic depression (Jabuka Pit). The main tasks assigned to IAEA-MEL were to provide 210 Pb derived sedimentation and dry-mass accumulation rates and to examine the possible correlations between sedimentary processes, the deposition and preservation of sedimentary organic carbon and pelagic primary productivity

  15. Sink strength simulations using the Monte Carlo method: Applied to spherical traps

    Science.gov (United States)

    Ahlgren, T.; Bukonte, L.

    2017-12-01

    The sink strength is an important parameter for the mean-field rate equations to simulate temporal changes in the micro-structure of materials. However, there are noteworthy discrepancies between sink strengths obtained by the Monte Carlo and analytical methods. In this study, we show the reasons for these differences. We present the equations to estimate the statistical error for sink strength calculations and show the way to determine the sink strengths for multiple traps. We develop a novel, very fast Monte Carlo method to obtain sink strengths. The results show that, in addition to the well-known sink strength dependence of the trap concentration, trap radius and the total sink strength, the sink strength also depends on the defect diffusion jump length and the total trap volume fraction. Taking these factors into account, allows us to obtain a very accurate analytic expression for the sink strength of spherical traps.

  16. The use of segregated heat sink structures to achieve enhanced passive cooling for outdoor wireless devices

    International Nuclear Information System (INIS)

    O'Flaherty, K; Punch, J

    2014-01-01

    Environmental standards which govern outdoor wireless equipment can stipulate stringent conditions: high solar loads (up to 1 kW/m 2 ), ambient temperatures as high as 55°C and negligible wind speeds (0 m/s). These challenges result in restrictions on power dissipation within a given envelope, due to the limited heat transfer rates achievable with passive cooling. This paper addresses an outdoor wireless device which features two segregated heat sink structures arranged vertically within a shielded chimney structure: a primary sink to cool temperature-sensitive components; and a secondary sink for high power devices. Enhanced convective cooling of the primary sink is achieved due to the increased mass flow within the chimney generated by the secondary sink. An unshielded heat sink was examined numerically, theoretically and experimentally, to verify the applicability of the methods employed. Nusselt numbers were compared for three cases: an unshielded heat sink; a sink located at the inlet of a shield; and a primary heat sink in a segregated structure. The heat sink, when placed at the inlet of a shield three times the length of the sink, augmented the Nusselt number by an average of 64% compared to the unshielded case. The Nusselt number of the primary was found to increase proportionally with the temperature of the secondary sink, and the optimum vertical spacing between the primary and secondary sinks was found to be close to zero, provided that conductive transfer between the sinks was suppressed.

  17. Quantifying the impact of riverine particulate dissolution in seawater on ocean chemistry

    Science.gov (United States)

    Jones, Morgan T.; Gislason, Sigurður R.; Burton, Kevin W.; Pearce, Christopher R.; Mavromatis, Vasileios; Pogge von Strandmann, Philip A. E.; Oelkers, Eric H.

    2014-06-01

    The quantification of the sources and sinks of elements to the oceans forms the basis of our understanding of global geochemical cycles and the chemical evolution of the Earth's surface. There is, however, a large imbalance in the current best estimates of the global fluxes to the oceans for many elements. In the case of strontium (Sr), balancing the input from rivers would require a much greater mantle-derived component than is possible from hydrothermal water flux estimates at mid-ocean ridges. Current estimates of riverine fluxes are based entirely on measurements of dissolved metal concentrations, and neglect the impact of riverine particulate dissolution in seawater. Here we present 87Sr/86Sr isotope data from an Icelandic estuary, which demonstrate rapid Sr release from the riverine particulates. We calculate that this Sr release is 1.1-7.5 times greater than the corresponding dissolved riverine flux. If such behaviour is typical of volcanic particulates worldwide, this release could account for 6-45% of the perceived marine Sr budget imbalance, with continued element release over longer timescales further reducing the deficit. Similar release from particulate material will greatly affect the marine budgets of many other elements, changing our understanding of coastal productivity, and anthropogenic effects such as soil erosion and the damming of rivers.

  18. Pathway of phloem unloading in tobacco sink leaves

    International Nuclear Information System (INIS)

    Turgeon, R.

    1987-01-01

    Phloem unloading in transition sink leaves of tobacco (Nicotiana tabacum L.) was analyzed by quantitative autoradiography. Source leaves were labeled with 14 CO 2 and experimental treatments were begun approximately 1 h later when label had entered the sink leaves. Autoradiographs were prepared from rapidly frozen, lyophilized sink tissue at the beginning and end of the treatments and the amount of label in veins and in surrounding cells was determined by microdensitometry. Photoassimilate unloaded from third order and larger, but not smaller, veins. Long-distance import and unloading did not respond the same way to all experimental treatments. Import was completely inhibited by cold, anaerobiosis or steam girdling the sink leaf petiole. Unloading was inhibited by cold but continued in an anaerobic atmosphere and after steam girdling. Uptake of exogenous [ 14 C]sucrose was inhibited by anaerobiosis. Since an apoplastic pathway of phloem unloading would involve solute uptake from the apoplast the results are most consistent with passive symplastic unloading of photoassimilates from phloem to surrounding cells

  19. Development of an operations evaluation system for sinking EDM

    NARCIS (Netherlands)

    Lauwers, B.; Oosterling, J.A.J.; Vanderauwera, W.

    2010-01-01

    This paper describes the development and validation of an operations evaluation system for sinking EDM operations. Based on a given workpiece geometry (e.g. mould), regions to be EDM'ed are automatically indentified. For a given electrode configuration, consisting of one or more regions, EDM

  20. Emission and Sink of Greenhouse Gases in Soils of Moscow

    Science.gov (United States)

    Mozharova, N. V.; Kulachkova, S. A.; Lebed'-Sharlevich, Ya. I.

    2018-03-01

    The first inventory and zoning of the emission and sink of methane and carbon dioxide in the urban structure of greenhouse gases from soils and surface technogenic formations (STFs) (Technosols) on technogenic, recrementogenic, and natural sediments have been performed with consideration for the global warming potential under conditions of different formation rate of these gases, underflooding, and sealing. From gas geochemical criteria and anthropogenic pedogenesis features, the main sources of greenhouse gases, their intensity, and mass emission were revealed. The mass fractions of emissions from the sectors of waste and land use in the inventories of greenhouse gas emissions have been determined. New sources of gas emission have been revealed in the first sector, the emissions from which add tens of percent to the literature and state reports. In the second sector, emissions exceed the available data in 70 times. Estimation criteria based on the degree of manifestation and chemical composition of soil-geochemical anomalies and barrier capacities have been proposed. The sink of greenhouse gases from the atmosphere and the internal (latent) sink of methane in soils and STFs have been determined. Ecological functions of soils and STFs have been shown, and the share of latent methane sink has been calculated. The bacterial oxidation of methane in soils and STFs exceeds its emission to the atmosphere in almost hundred times.

  1. Million Trees Los Angeles: Carbon dioxide sink or source?

    Science.gov (United States)

    E.G. McPherson; A. Kendall; S. Albers

    2015-01-01

    This study seeks to answer the question, 'Will the Million Trees LA (MTLA) programme be a CO2 sink or source?' Using surveys, interviews, field sampling and computer simulation of tree growth and survival over a 40-year period, we developed the first process-based life cycle inventory of CO2 for a large tree...

  2. Enhanced heat sink with geometry induced wall-jet

    Energy Technology Data Exchange (ETDEWEB)

    Hossain, Md. Mahamudul, E-mail: sohel0991@gmail.com; Tikadar, Amitav; Bari, Fazlul; Morshed, A. K. M. M. [Department of Mechanical Engineering Bangladesh University of Engineering and Technology, Dhaka-1000. Bangladesh (Bangladesh)

    2016-07-12

    Mini-channels embedded in solid matrix have already proven to be a very efficient way of electronic cooling. Traditional mini-channel heat sinks consist of single layer of parallel channels. Although mini-channel heat sink can achieve very high heat flux, its pumping requirement for circulating liquid through the channel increase very sharply as the flow velocity increases. The pumping requirements of the heat sink can be reduced by increasing its performance. In this paper a novel approach to increase the thermal performance of the mini-channel heat sink is proposed through geometry induced wall jet which is a passive technique. Geometric irregularities along the channel length causes abrupt pressure change between the channels which causes cross flow through the interconnections thus one channel faces suction and other channel jet action. This suction and jet action disrupts boundary layer causing enhanced heat transfer performance. A CFD model has been developed using commercially available software package FLUENT to evaluate the technique. A parametric study of the velocities and the effect of the position of the wall-jets have been performed. Significant reduction in thermal resistance has been observed for wall-jets, it is also observed that this reduction in thermal resistance is dependent on the position and shape of the wall jet.

  3. Intrinsic and extrinsic drivers of source-sink dynamics

    Science.gov (United States)

    1. Many factors affect the presence and exchange of individuals among subpopulations and influence not only the emergence, but the strength of ensuing source-sink dynamics within metapopulations, yet their relative contributions remain largely unexplored. 2. To help identify the...

  4. Recent findings on sinks for sulfide in gravity sewer networks

    DEFF Research Database (Denmark)

    Nielsen, Asbjørn Haaning; Hvitved-Jacobsen, Thorkild; Vollertsen, Jes

    2006-01-01

    summarizes this newly obtained knowledge and emphasizes important implications of the findings. Model simulations of the in-sewer processes important for the sulfur cycle showed that sulfide oxidation in the wetted biofilm is typically the most important sink for dissolved sulfide in gravity sewers. However...

  5. Role of Sink Density in Nonequilibrium Chemical Redistribution in Alloys

    Science.gov (United States)

    Martínez, Enrique; Senninger, Oriane; Caro, Alfredo; Soisson, Frédéric; Nastar, Maylise; Uberuaga, Blas P.

    2018-03-01

    Nonequilibrium chemical redistribution in open systems submitted to external forces, such as particle irradiation, leads to changes in the structural properties of the material, potentially driving the system to failure. Such redistribution is controlled by the complex interplay between the production of point defects, atomic transport rates, and the sink character of the microstructure. In this work, we analyze this interplay by means of a kinetic Monte Carlo (KMC) framework with an underlying atomistic model for the Fe-Cr model alloy to study the effect of ideal defect sinks on Cr concentration profiles, with a particular focus on the role of interface density. We observe that the amount of segregation decreases linearly with decreasing interface spacing. Within the framework of the thermodynamics of irreversible processes, a general analytical model is derived and assessed against the KMC simulations to elucidate the structure-property relationship of this system. Interestingly, in the kinetic regime where elimination of point defects at sinks is dominant over bulk recombination, the solute segregation does not directly depend on the dose rate but only on the density of sinks. This model provides new insight into the design of microstructures that mitigate chemical redistribution and improve radiation tolerance.

  6. Analysis of ultimate-heat-sink spray ponds. Technical report

    International Nuclear Information System (INIS)

    Codell, R.

    1981-08-01

    This report develops models which can be utilized in the design of certain types of spray ponds used in ultimate heat sinks at nuclear power plants, and ways in which the models may be employed to determine the design basis required by U.S. Nuclear Regulatory Commission Regulatory Guide 1.27

  7. Quantifying greenhouse gas sources and sinks in managed wetland systems

    Science.gov (United States)

    Stephen M Ogle; Patrick Hunt; Carl Trettin

    2014-01-01

    This chapter provides methodologies and guidance for reporting greenhouse gas (GHG) emissions and sinks at the entity scale for managed wetland systems. More specifically, it focuses on methods for managed palustrine wetlands.1 Section 4.1 provides an overview of wetland systems and resulting GHG emissions, system boundaries and temporal scale, a summary of the...

  8. Organizations

    DEFF Research Database (Denmark)

    Hatch, Mary Jo

    and considers many more. Mary Jo Hatch introduces the concept of organizations by presenting definitions and ideas drawn from the a variety of subject areas including the physical sciences, economics, sociology, psychology, anthropology, literature, and the visual and performing arts. Drawing on examples from......Most of us recognize that organizations are everywhere. You meet them on every street corner in the form of families and shops, study in them, work for them, buy from them, pay taxes to them. But have you given much thought to where they came from, what they are today, and what they might become...... prehistory and everyday life, from the animal kingdom as well as from business, government, and other formal organizations, Hatch provides a lively and thought provoking introduction to the process of organization....

  9. Spatial distribution of carbon sources and sinks in Canada's forests

    International Nuclear Information System (INIS)

    Chen, Jing M.; Weimin, Ju; Liu, Jane; Cihlar, Josef; Chen, Wenjun

    2003-01-01

    Annual spatial distributions of carbon sources and sinks in Canada's forests at 1 km resolution are computed for the period from 1901 to 1998 using ecosystem models that integrate remote sensing images, gridded climate, soils and forest inventory data. GIS-based fire scar maps for most regions of Canada are used to develop a remote sensing algorithm for mapping and dating forest burned areas in the 25 yr prior to 1998. These mapped and dated burned areas are used in combination with inventory data to produce a complete image of forest stand age in 1998. Empirical NPP age relationships were used to simulate the annual variations of forest growth and carbon balance in 1 km pixels, each treated as a homogeneous forest stand. Annual CO 2 flux data from four sites were used for model validation. Averaged over the period 1990-1998, the carbon source and sink map for Canada's forests show the following features: (i) large spatial variations corresponding to the patchiness of recent fire scars and productive forests and (ii) a general south-to-north gradient of decreasing carbon sink strength and increasing source strength. This gradient results mostly from differential effects of temperature increase on growing season length, nutrient mineralization and heterotrophic respiration at different latitudes as well as from uneven nitrogen deposition. The results from the present study are compared with those of two previous studies. The comparison suggests that the overall positive effects of non-disturbance factors (climate, CO 2 and nitrogen) outweighed the effects of increased disturbances in the last two decades, making Canada's forests a carbon sink in the 1980s and 1990s. Comparisons of the modeled results with tower-based eddy covariance measurements of net ecosystem exchange at four forest stands indicate that the sink values from the present study may be underestimated

  10. Photosynthesis, respiration, and carbon turnover in sinking marine snow from surface waters of Southern California Bight: implications for the carbon cycle in the ocean

    DEFF Research Database (Denmark)

    Ploug, H.; Grossart, HP; Azam, F.

    1999-01-01

    aggregate in darkness, which yielded a turnover time of 8 to 9 d for the total organic carbon in aggregates. Thus, marine snow is not only a vehicle for vertical flux of organic matter; the aggregates are also hotspots of microbial respiration which cause a fast and efficient respiratory turnover...... of particulate organic carbon in the sea....

  11. Dispersal and sink pathways of suspended particulate matter from the orographically enhanced SWM regime of the SE Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Chauhan, O.S.; Kader, U.S.A.; Vaidya, P.; Rajawat, A.S.; Ajai; Ramakrishnan, R.

    during NE monsoon. Deep-Sea Research part II, 52(14-15), pp. 2018-2030. doi:10.1016/j.dsr2.2005.05.012 CHAUHAN, O. S., VOGELSANG, E., BASAVAIAH, N. and KADER, U. S. A., 2010, Reconstruction of the variability of the southwest monsoon during the past...

  12. Starch as a source, starch as a sink: the bifunctional role of starch in carbon allocation.

    Science.gov (United States)

    MacNeill, Gregory J; Mehrpouyan, Sahar; Minow, Mark A A; Patterson, Jenelle A; Tetlow, Ian J; Emes, Michael J

    2017-07-20

    Starch commands a central role in the carbon budget of the majority of plants on earth, and its biological role changes during development and in response to the environment. Throughout the life of a plant, starch plays a dual role in carbon allocation, acting as both a source, releasing carbon reserves in leaves for growth and development, and as a sink, either as a dedicated starch store in its own right (in seeds and tubers), or as a temporary reserve of carbon contributing to sink strength, in organs such as flowers, fruits, and developing non-starchy seeds. The presence of starch in tissues and organs thus has a profound impact on the physiology of the growing plant as its synthesis and degradation governs the availability of free sugars, which in turn control various growth and developmental processes. This review attempts to summarize the large body of information currently available on starch metabolism and its relationship to wider aspects of carbon metabolism and plant nutrition. It highlights gaps in our knowledge and points to research areas that show promise for bioengineering and manipulation of starch metabolism in order to achieve more desirable phenotypes such as increased yield or plant biomass. © The Author 2017. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  13. Monitoring diesel particulate matter and calculating diesel particulate densities using Grimm model 1.109 real-time aerosol monitors in underground mines.

    Science.gov (United States)

    Kimbal, Kyle C; Pahler, Leon; Larson, Rodney; VanDerslice, Jim

    2012-01-01

    Currently, there is no Mine Safety and Health Administration (MSHA)-approved sampling method that provides real-time results for ambient concentrations of diesel particulates. This study investigated whether a commercially available aerosol spectrometer, the Grimm Portable Aerosol Spectrometer Model 1.109, could be used during underground mine operations to provide accurate real-time diesel particulate data relative to MSHA-approved cassette-based sampling methods. A subset was to estimate size-specific diesel particle densities to potentially improve the diesel particulate concentration estimates using the aerosol monitor. Concurrent sampling was conducted during underground metal mine operations using six duplicate diesel particulate cassettes, according to the MSHA-approved method, and two identical Grimm Model 1.109 instruments. Linear regression was used to develop adjustment factors relating the Grimm results to the average of the cassette results. Statistical models using the Grimm data produced predicted diesel particulate concentrations that highly correlated with the time-weighted average cassette results (R(2) = 0.86, 0.88). Size-specific diesel particulate densities were not constant over the range of particle diameters observed. The variance of the calculated diesel particulate densities by particle diameter size supports the current understanding that diesel emissions are a mixture of particulate aerosols and a complex host of gases and vapors not limited to elemental and organic carbon. Finally, diesel particulate concentrations measured by the Grimm Model 1.109 can be adjusted to provide sufficiently accurate real-time air monitoring data for an underground mining environment.

  14. Relationship between indoor and outdoor carbonaceous particulates in roadside households

    Energy Technology Data Exchange (ETDEWEB)

    Funasaka, K.; Miyazaki, T.; Tsuruho, K. [Osaka City Institute of Public Health and Environmental Sciences (Japan); Tamura, K. [The National Institute for Minamata Disease, Kumamoto (Japan); Mizuno, T. [Mie University (Japan). Dept. of Chemistry for Materials; Kuroda, K. [Osaka City University Medical School (Japan). Dept. of Preventive Medicine and Environmental Health

    2000-07-01

    Concentrations of particulate matter (PM) and carbonaceous particulates in indoor and outdoor air at roadside private households were measured in Osaka, Japan. The particulate samples were collected on filters using a portable AND sampler capable of separating particles into three different size ranges: over 10 {mu}m, 2-10 {mu}m (coarse) and below 2 {mu}m (fine) in aerodynamic diameter. The filters were weighed and then analyzed for elemental carbon (EC) and organic carbon (OC) by thermal oxidation using a CHN CORDER. The results showed that indoor fine PM concentration is considerably affected by fine EC and the fine EC in indoor air is significantly correlated to that in outdoor air, r = 0.86 (n = 30, p < 0.001). A simple estimation from EC content ratio in diesel exhaust particles indicated that about 30% of indoor particulates of less than 10 {mu}m (PM10) were contributed from diesel exhaust. Additionally, the size characteristics of outdoor PM at roadside and background sites were examined using Andersen Cascade Impactors. (author)

  15. Source apportionment of PM10 mass and particulate carbon in the Kathmandu Valley, Nepal

    Science.gov (United States)

    Kim, Bong Mann; Park, Jin-Soo; Kim, Sang-Woo; Kim, Hyunjae; Jeon, Haeun; Cho, Chaeyoon; Kim, Ji-Hyoung; Hong, Seungkyu; Rupakheti, Maheswar; Panday, Arnico K.; Park, Rokjin J.; Hong, Jihyung; Yoon, Soon-Chang

    2015-12-01

    The Kathmandu Valley in Nepal is a bowl-shaped urban basin in the Himalayan foothills with a serious problem of fine particulate air pollution that impacts local health and impairs visibility. Particulate carbon concentrations have reached severe levels that threaten the health of 3.5 million local residents. Moreover, snow and ice on the Himalayan mountains are melting as a result of additional warming due to particulate carbon, especially high black carbon concentrations. To date, the sources of the Valley's particulate carbon and the impacts of different sources on particulate carbon concentrations are not well understood. Thus, before an effective control strategy can be developed, these particulate carbon sources must be identified and quantified. Our study has found that the four primary sources of particulate carbon in the Kathmandu Valley during winter are brick kilns, motor vehicles, fugitive soil dust, and biomass/garbage burning. Their source contributions are quantified using a recently developed new multivariate receptor model SMP. In contrast to other highly polluted areas such as China, secondary contribution is almost negligible in Kathmandu Valley. Brick kilns (40%), motor vehicles (37%) and biomass/garbage burning (22%) have been identified as the major sources of elemental carbon (black carbon) in the Kathmandu Valley during winter, while motor vehicles (47%), biomass/garbage burning (32%), and soil dust (13%) have been identified as the most important sources of organic carbon. Our research indicates that controlling emissions from motor vehicles, brick kilns, biomass/garbage burning, and soil dust is essential for the mitigation of the particulate carbon that threatens public health, impairs visibility, and influences climate warming within and downwind from the Kathmandu Valley. In addition, this paper suggests several useful particulate carbon mitigation methods that can be applied to Kathmandu Valley and other areas in South Asia with

  16. Connecting Source with Sink: The Role of Arabidopsis AAP8 in Phloem Loading of Amino Acids1[OPEN

    Science.gov (United States)

    Santiago, James P.; Tegeder, Mechthild

    2016-01-01

    Allocation of large amounts of nitrogen to developing organs occurs in the phloem and is essential for plant growth and seed development. In Arabidopsis (Arabidopsis thaliana) and many other plant species, amino acids represent the dominant nitrogen transport forms in the phloem, and they are mainly synthesized in photosynthetically active source leaves. Following their synthesis, a broad spectrum of the amino nitrogen is actively loaded into the phloem of leaf minor veins and transported within the phloem sap to sinks such as developing leaves, fruits, or seeds. Controlled regulation of the source-to-sink transport of amino acids has long been postulated; however, the molecular mechanism of amino acid phloem loading was still unknown. In this study, Arabidopsis AMINO ACID PERMEASE8 (AAP8) was shown to be expressed in the source leaf phloem and localized to the plasma membrane, suggesting its function in phloem loading. This was further supported by transport studies with aap8 mutants fed with radiolabeled amino acids and by leaf exudate analyses. In addition, biochemical and molecular analyses revealed alterations in leaf nitrogen pools and metabolism dependent on the developmental stage of the mutants. Decreased amino acid phloem loading and partitioning to sinks led to decreased silique and seed numbers, but seed protein levels were unchanged, demonstrating the importance of AAP8 function for sink development rather than seed quality. Overall, these results show that AAP8 plays an important role in source-to-sink partitioning of nitrogen and that its function affects source leaf physiology and seed yield. PMID:27016446

  17. Lifetime Optimization of a Multiple Sink Wireless Sensor Network through Energy Balancing

    Directory of Open Access Journals (Sweden)

    Tapan Kumar Jain

    2015-01-01

    Full Text Available The wireless sensor network consists of small limited energy sensors which are connected to one or more sinks. The maximum energy consumption takes place in communicating the data from the nodes to the sink. Multiple sink WSN has an edge over the single sink WSN where very less energy is utilized in sending the data to the sink, as the number of hops is reduced. If the energy consumed by a node is balanced between the other nodes, the lifetime of the network is considerably increased. The network lifetime optimization is achieved by restructuring the network by modifying the neighbor nodes of a sink. Only those nodes are connected to a sink which makes the total energy of the sink less than the threshold. This energy balancing through network restructuring optimizes the network lifetime. This paper depicts this fact through simulations done in MATLAB.

  18. Antimony sinks in the weathering crust of bullets from Swiss shooting ranges

    International Nuclear Information System (INIS)

    Ackermann, Sonia; Giere, Reto; Newville, Matthew; Majzlan, Juraj

    2009-01-01

    Shooting ranges represent sites heavily polluted by Pb, Sb, Cu, Ni, and Zn, which are released during the weathering of bullets. The pristine bullets are made of a Pb-Sb core, Fe mantle, and minor amounts of Cu, Ni, and Zn in an interlayer between the core and mantle. At two selected sampling sites (Losone and Lucerne, both in Switzerland), corroding bullets were collected to determine the sinks of Sb within the weathering crust of the bullets. Bulk Sb concentrations in the crust were found to be as high as 1.3 wt.%. The oxalate-extractable fraction of Fe showed that the amorphous Fe oxides (e.g., ferrihydrite) prevail over goethite and lepidocrocite, which were identified by bulk X-ray diffraction experiments. Crystalline Pb phases are litharge (only found by X-ray diffraction) and cerussite, which result from weathering of the Pb core. No distinct Sb minerals were identified by X-ray diffraction. Investigations with electron microprobe (EMP) showed that Sb is mostly accumulated in those regions in the weathering crust where there is also a high concentration of Fe. In the weathering crust from Losone, such Fe-rich regions with Sb are represented by material that cements or rims silicate mineral grains. The cement was identified as lepidocrocite by micro-Raman analysis. At Lucerne, Sb is found in Fe-oxide aggregates, in sawdust particles where it may be bound to organic matter, or in aggregates enriched in Pb and depleted in Fe. Bulk EXAFS experiments suggested that the Fe oxides are the most important sink for Sb. Our modelling of Sb next-nearest neighbours suggests two types of inner-sphere complexes on the surfaces of Fe oxides. These are edge- and corner-sharing adsorption complexes. Hence, the predominant sink of Sb in the weathering crust of the bullets at the selected shooting ranges is Fe oxides, amorphous or crystalline

  19. Acoustic monitoring of a ball sinking in vibrated granular sediments

    Science.gov (United States)

    van den Wildenberg, Siet; Léopoldès, Julien; Tourin, Arnaud; Jia, Xiaoping

    2017-06-01

    We develop an ultrasound probing to investigate the dynamics of a high density ball sinking in 3D opaque dense granular suspensions under horizontal weak vibrations. We show that the motion of the ball in these horizontally vibrated glass bead packings saturated by water is consistent with the frictional rheology. The extracted stress-strain relation evidences an evolution of flow behaviour from frictional creep to inertial regimes. Our main finding is that weak external vibration primarily affects the yield stress and controls the depth of sinking via vibration-induced sliding at the grain contact. Also, we observe that the extracted rheological parameters depend on the size of the probing ball, suggesting thus a non-local rheology.

  20. A novel high performance, ultra thin heat sink for electronics

    International Nuclear Information System (INIS)

    Escher, W.; Michel, B.; Poulikakos, D.

    2010-01-01

    We present an ultra thin heat sink for electronics, combining optimized impinging slot-jets, micro-channels and manifolds for efficient cooling. We first introduce a three-dimensional numerical model of the heat transfer structure, to investigate its hydrodynamic and thermal performance and its sensitivity to geometric parameters. In a second step we propose a three-dimensional hydrodynamic numerical model representing the complete system. Based on this model we design a novel manifold providing uniform fluid distribution. In order to save computational time a simpler semi-empirical model is proposed and validated. The semi-empirical model allows a robust optimization of the heat sink geometric parameters. The design is optimized for a 2 x 2 cm 2 chip and provides a total thermal resistance of 0.087 cm 2 K/W for flow rates 2 for a temperature difference between fluid inlet and chip of 65 K.

  1. Prediction of work piece geometry in electrochemical cavity sinking

    Energy Technology Data Exchange (ETDEWEB)

    Riggs, J B; Muller, R H; Tobias, C W

    1981-01-01

    A computer-implemented model for predicting ECM work piece geometry has been developed and experimentally verified with a commercial ECM machine for cavity sinking in copper and 302-stainless steel with 2N KNO/sub 3/ electrolyte. Constant tool piece feed rates of 7-10 x 10/sup -4/ cm/s, and applied voltages of 11-25 V were used. The model predicts the dependence of work piece geometry on operating conditions and on the electrochemical and physical properties of the metal-electrolyte pair. Comparison of eight equilibrium and six unsteady state experimental cavity profiles in copper showed satisfactory agreement with predictions, as did five equilibrium profiles for cavity sinking in 302-stainless steel.

  2. Gaseous and particulate emissions from prescribed burning in Georgia.

    Science.gov (United States)

    Lee, Sangil; Baumann, Karsten; Schauer, James J; Sheesley, Rebecca J; Naeher, Luke P; Meinardi, Simone; Blake, Donald R; Edgerton, Eric S; Russell, Armistead G; Clements, Mark

    2005-12-01

    Prescribed burning is a significant source of fine particulate matter (PM2.5) in the southeastern United States. However, limited data exist on the emission characteristics from this source. Various organic and inorganic compounds both in the gas and particle phase were measured in the emissions of prescribed burnings conducted at two pine-dominated forest areas in Georgia. The measurements of volatile organic compounds (VOCs) and PM2.5 allowed the determination of emission factors for the flaming and smoldering stages of prescribed burnings. The VOC emission factors from smoldering were distinctly higher than those from flaming except for ethene, ethyne, and organic nitrate compounds. VOC emission factors show that emissions of certain aromatic compounds and terpenes such as alpha and beta-pinenes, which are important precursors for secondary organic aerosol (SOA), are much higher from active prescribed burnings than from fireplace wood and laboratory open burning studies. Levoglucosan is the major particulate organic compound (POC) emitted for all these studies, though its emission relative to total organic carbon (mg/g OC) differs significantly. Furthermore, cholesterol, an important fingerprint for meat cooking, was observed only in our in situ study indicating a significant release from the soil and soil organisms during open burning. Source apportionment of ambient primary fine particulate OC measured at two urban receptor locations 20-25 km downwind yields 74 +/- 11% during and immediately after the burns using our new in situ profile. In comparison with the previous source profile from laboratory simulations, however, this OC contribution is on average 27 +/- 5% lower.

  3. Pin fin compliant heat sink with enhanced flexibility

    Science.gov (United States)

    Schultz, Mark D.

    2018-04-10

    Heat sinks and methods of using the same include a top and bottom plate, at least one of which has a plurality of pin contacts flexibly connected to one another, where the plurality of pin contacts have vertical and lateral flexibility with respect to one another; and pin slice layers, each having multiple pin slices, arranged vertically between the top and bottom plates such that the plurality of pin slices form substantially vertical pins connecting the top and bottom plates.

  4. Field Test of a Steam Condenser Heat Sink Concept

    Science.gov (United States)

    1974-01-01

    stored underground for a specified time. A functional and economical heat rejection system is an important design consideration for such...per- mits the use of tunnels for other than just heat sink purposes. If existing tunnels can be used, the concept becomes economically attractive...that the water meter readings aie a valid indication of the mpu ! and that condensate was lost bv seepage thionuli the lock and or ballast into the

  5. Analytical analysis and experimental verification of interleaved parallelogram heat sink

    International Nuclear Information System (INIS)

    Chen, Hong-Long; Wang, Chi-Chuan

    2017-01-01

    Highlights: • A novel air-cooled heat sink profile (IPFM) is proposed to compete with the typical design. • It features two different perimeters with odd fin being rectangular and the rest being parallelogram. • A new modified dimensionless parameter characterized the flow length in triangular region is proposed. • The analytical predictions are in line with the experiments for both conventional and IPFM design. • IPFM design shows a much lower pressure drop and a superior performance especially for dense fins. - Abstract: In this study, a novel air-cooled heat sink profile is proposed to compete with the conventional design. The new design is termed as IPFM (Interleaved Parallelogram Fin Module) which features two different geometrical perimeter shapes of fins. This new design not only gains the advantage of lower pressure drop for power saving; but also gains a material saving for less fin surface area. An assessment of flow impedance and performance between the conventional and IPFM heat sink is analytically investigated and experimentally verified. A new modified dimensionless friction factor for triangular region is proposed. The analytical predictions agree with experimental measurements for both conventional and IPFM design. In electronic cooling design, especially for cloud server air-cooled heat sink design, the flow pattern is usually laminar with Reynolds number being operated less than 2000. In this regime, the IPFM design shows 8–12% less of surface than conventional design when the flow rate is less than 10 CFM; yet the thermal performance is slightly inferior to the conventional design when the flowrate is raised towards 25 CFM. Yet in the test range of 5–25 CFM, a 10–15% lower flow impedance is observed. The smaller fin spacing, the more conspicuous reduction of flow impedance is observed. The optimization of cutting angle is around 35° for 10 CFM, and it is reduced to 15° at a larger flowrate of 20 CFM.

  6. Is The Bovine Pedal Bone Sinking Around Calving?

    DEFF Research Database (Denmark)

    Bach, Kurt; Nielsen, Søren Saxmose; Capion, Nynne

    weeks. The correlation between “days from calving” and “thickness of the soft tissue” was 0.31 (Pearson’s, p...Introduction Softening of connective tissue of the claw suspensory apparatus around calving as described by Tarlton, et al. (2002) may lead to sinking of the bovine pedal bone resulting in compression of the digital cushion. The objective of this study was to describe changes in the thickness...

  7. Sinking of armour layer around a vertical cylinder exposed to waves and current

    DEFF Research Database (Denmark)

    Nielsen, Anders Wedel; Probst, Thomas; Petersen, Thor Ugelvig

    2015-01-01

    The mechanisms of the sinking of a scour protection adjacent to a monopile are described in this paper, together with the determination of the equilibrium sinking depth in various wave and combined wave and current conditions based on physical model tests.Sinking of the rocks may ultimately lead ...

  8. Lignin phenols and BIT index distributions in the Amur River and the Sea of Okhotsk: Implications for the source and transport of particulate terrestrial organic matter to the ocean

    NARCIS (Netherlands)

    Seki, O.; Mikami, Y.; Nagao, S.; Bendle, J.A.; Nakatsuka, T.; Kim, V.I.; Shesterkin, V.P.; Makinov, A.N.; Fukushima, M.; Moossen, H.M.; Schouten, S.

    2014-01-01

    Delta and coastal regions play a key role in the global carbon cycle as the main repository of inputs of terrestrial organic matter, delivered by rivers to marine sediments. The Amur River system is one of the largest in Asia and supplies organic matter to the Sea of Okhotsk and the North Pacific

  9. Sink strengths of dislocations taking into account bulk recombination effects

    International Nuclear Information System (INIS)

    Steinbach, E.

    1988-01-01

    The applicability of the rate theory to describe radiation damage processes is closely associated with the calculation of the various sink strengths. In this connection the effect of bulk recombination is usually neglected, because of the complexity of the problem. For this reason we present in this paper, for the first time, by means of the rigorous elastic-field model of a dislocation embedded in a lossy continuum, analytic expressions for the diffusion flux of irradiation-induced point defects into a dislocation, taking into account the elastic interaction, additional sinks and higher order bulk recombination effects. The resulting self-consistent formulae for the dislocation sink strengths clearly demonstrate the importance of the bulk recombination for the micro-structures of irradiated materials. In conjunction with the Harwell computer code VS5 it became clear that this new dislocation bias also leads to a change in the macrostructural observables. The order of magnitude of this effect emphasizes that neglecting bulk recombination as a general principle is not justified

  10. The sinking of the Soviet Mike class nuclear powered submarine

    International Nuclear Information System (INIS)

    1989-01-01

    The purpose of this preliminary study is to assess the quantities of the longer-lived or persistent radioactive materials, or source terms, that have been lost at sea with the sinking of the Soviet MIKE class submarine off Bear Island on 7 April 1989. The report arrives at an assessment of the amount of radioactivity and compares this to the quantities of radioactive materials dumped by the UK from 1953 to 1982 at which time sea dumping of radioactive wastes was suspended by international resolve. This comparison can be used to assess the relative significance of the sinking of this submarine. The study does not extrapolate the estimated radioactive source terms to an environmental or radiological significance of the sinking, although it is concluded that unless the submarine is recovered intact from the ocean floor, the by far greater part of the radioactive materials on board will disperse to the marine environment at some future time, if they are not doing so already. (author)

  11. Trends in the sources and sinks of carbon dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Le Quere, Corrine [University of East Anglia, Norwich, United Kingdom; Raupach, Mike [GCP, Canberra, Australia; Canadell, J.G. [CSIRO Marine and Atmospheric Research; Marland, Gregg [ORNL; Bopp, Laurent [National Center for Scientific Research, Gif-sur-Yvette, France; Ciais, Philippe [Laboratoire des Sciences du Climat et de l' Environement, France; Friedlingstein, Pierre [National Center for Scientific Research, Gif-sur-Yvette, France; Viovy, Nicolas [National Center for Scientific Research, Gif-sur-Yvette, France; Conway, T.J. [NOAA, Boulder, CO; Doney, Scott C. [Woods Hole Oceanographic Institution; Feely, R. A. [NOAA Pacific Marine Environmental Laboratory; Foster, Pru [University of Bristol, UK; House, Joanna I [University of Bristol, UK; Prentice, Colin I. [University of Bristol, UK; Gurney, Kevin [Purdue University; Houghton, R.A. [Woods Hole Research Center, Woods Hole, MA; Huntingford, Chris [Center for Ecology and Hydrology, Oxon, England; Levy, Peter E. [Center for Ecology and Hydrology, Midlothian, Scotland; Lomas, M. R. [University of Sheffield; Woodward, F. I. [University of Sheffield; Majkut, Joseph [Princeton University; Sarmiento, Jorge L. [Princeton University; Metzl, Nicolas [University of Paris; Ometto, Jean P [ORNL; Randerson, James T. [University of California, Irvine; Peters, Glen P [Center for International Climate and Energy Research (CICERO), Oslo, Norway; Running, Steven [University of Montana, Missoula; Sitch, Stephen [University of Leeds, UK; Takahashi, Taro [Columbia University; Van der Werf, Guido [Universitate Amsterdam

    2009-12-01

    Efforts to control climate change require the stabilization of atmospheric CO2 concentrations. This can only be achieved through a drastic reduction of global CO2 emissions. Yet fossil fuel emissions increased by 29% between 2000 and 2008, in conjunction with increased contributions from emerging economies, from the production and international trade of goods and services, and from the use of coal as a fuel source. In contrast, emissions from land-use changes were nearly constant. Between 1959 and 2008, 43% of each year's CO2 emissions remained in the atmosphere on average; the rest was absorbed by carbon sinks on land and in the oceans. In the past 50 years, the fraction of CO2 emissions that remains in the atmosphere each year has likely increased, from about 40% to 45%, and models suggest that this trend was caused by a decrease in the uptake of CO2 by the carbon sinks in response to climate change and variability. Changes in the CO2 sinks are highly uncertain, but they could have a significant influence on future atmospheric CO2 levels. It is therefore crucial to reduce the uncertainties.

  12. Control of Delta Avulsion by Downstream Sediment Sinks

    Science.gov (United States)

    Salter, Gerard; Paola, Chris; Voller, Vaughan R.

    2018-01-01

    Understanding how fluxes are partitioned at delta bifurcations is critical for predicting patterns of land loss and gain in deltas worldwide. Although the dynamics of river deltas are influenced from both upstream and downstream, previous studies of bifurcations have focused on upstream controls. Using a quasi-1-D bifurcation model, we show that flow switching in bifurcations is strongly influenced by downstream sediment sinks. We find that coupling between upstream and downstream feedbacks can lead to oscillations in water and sediment flux partitioning. The frequency and initial rate of growth/decay of the oscillations depend on both upstream and downstream conditions, with dimensionless bifurcate length and bypass fraction emerging as key downstream parameters. With a strong offshore sink, causing bypass in the bifurcate branches, we find that bifurcation dynamics become "frozen"; that is, the bifurcation settles on a permanent discharge ratio. In contrast, under depositional conditions, we identify three dynamical regimes: symmetric; soft avulsion, where both branches remain open but the dominant branch switches; and full avulsion. Finally, we show that differential subsidence alters these regimes, with the difference in average sediment supply to each branch exactly compensating for the difference in accommodation generation. Additionally, the model predicts that bifurcations with shorter branches are less asymmetric than bifurcations with longer branches, all else equal, providing a possible explanation for the difference between backwater length distributaries, which tend to be avulsive, and relatively stable mouth-bar-scale networks. We conclude that bifurcations are sensitive both quantitatively and qualitatively to downstream sinks.

  13. PIXE analysis of vehicle exhaust particulate

    International Nuclear Information System (INIS)

    Shi Xianfeng; Yao Huiying; Liu Bo; Sun Minde; Xu Huawei; Mi Yong; Shen Hao

    2001-01-01

    PIXE technique on the analysis of vehicle exhaust particulate is introduced. The clement composition and concentration of particulate are obtained. Some elements which are related to environmental pollution such as sulfur lead, silicon and manganese, were analyzed and discussed in detail by PIXE technique Nowadays although unleaded gasoline is widely used, the lead concentration is still very high in exhaust particulate. The concentrations of silicon and manganese in exhaust particulate from different model vehicles are also quite high from measurements. It shows that an evidence for exhaust pollution control could be provided from this work

  14. Vulnerability of the peatland carbon sink to sea-level rise

    Science.gov (United States)

    Whittle, Alex; Gallego-Sala, Angela V.

    2016-06-01

    Freshwater peatlands are carbon accumulating ecosystems where primary production exceeds organic matter decomposition rates in the soil, and therefore perform an important sink function in global carbon cycling. Typical peatland plant and microbial communities are adapted to the waterlogged, often acidic and low nutrient conditions that characterise them. Peatlands in coastal locations receive inputs of oceanic base cations that shift conditions from the environmental optimum of these communities altering the carbon balance. Blanket bogs are one such type of peatlands occurring in hyperoceanic regions. Using a blanket bog to coastal marsh transect in Northwest Scotland we assess the impacts of salt intrusion on carbon accumulation rates. A threshold concentration of salt input, caused by inundation, exists corresponding to rapid acidophilic to halophilic plant community change and a carbon accumulation decline. For the first time, we map areas of blanket bog vulnerable to sea-level rise, estimating that this equates to ~7.4% of the total extent and a 0.22 Tg yr-1 carbon sink. Globally, tropical peatlands face the proportionally greatest risk with ~61,000 km2 (~16.6% of total) lying ≤5 m elevation. In total an estimated 20.2 ± 2.5 GtC is stored in peatlands ≤5 m above sea level, which are potentially vulnerable to inundation.

  15. Source-sink relationships in two soybean cultivars with indeterminate growth under water deficit

    Directory of Open Access Journals (Sweden)

    Alexandre José da Silva

    Full Text Available Abstract Water deficit is a major factor limiting crop yield in rainfed areas. We hypothesized that under water deficit the decrease of photosynthetic production stimulates: carbohydrate remobilization from leaves, stems and roots to reproductive organs; and decreasing flowering intensity and pod development. The present work aims to study the effect of water deficit during bloom and grain pod-filling stages in two indeterminate soybean cultivar, Vtop and Nidera. The following physiological parameters were evaluated by means of daily CO2 assimilation rate (Ai, dynamic of carbohydrates in tissues, plant growth, grain yield and yield components. The study was conducted in a greenhouse with plants sown in tanks of 0.5 m3. Regardless of the phenological phase, water deficit reduced Ai, plant growth and number of pods and seeds per plant. The fact that grain yield was less affected by water deficit at bloom than at grain pod-filling stage was attributed to larger seeds found at bloom. In both treatments, a sharp reduction on carbohydrate content was found in leaves, stem and roots at the beginning of pod formation. The high amounts of carbohydrates remobilized for seed growth, along with the high values of Ai observed in well-watered plants, indicate that grain yield of soybeans is source rather than sink limited. On the other hand, in water deficit treatments, a new stimulus for carbohydrate storage was found in the leaves and stem at the beginning of grain maturity, suggesting that grain yield was limited by sink capacity.

  16. Vulnerability of the peatland carbon sink to sea-level rise

    Science.gov (United States)

    Whittle, Alex; Gallego-Sala, Angela V.

    2016-01-01

    Freshwater peatlands are carbon accumulating ecosystems where primary production exceeds organic matter decomposition rates in the soil, and therefore perform an important sink function in global carbon cycling. Typical peatland plant and microbial communities are adapted to the waterlogged, often acidic and low nutrient conditions that characterise them. Peatlands in coastal locations receive inputs of oceanic base cations that shift conditions from the environmental optimum of these communities altering the carbon balance. Blanket bogs are one such type of peatlands occurring in hyperoceanic regions. Using a blanket bog to coastal marsh transect in Northwest Scotland we assess the impacts of salt intrusion on carbon accumulation rates. A threshold concentration of salt input, caused by inundation, exists corresponding to rapid acidophilic to halophilic plant community change and a carbon accumulation decline. For the first time, we map areas of blanket bog vulnerable to sea-level rise, estimating that this equates to ~7.4% of the total extent and a 0.22 Tg yr−1 carbon sink. Globally, tropical peatlands face the proportionally greatest risk with ~61,000 km2 (~16.6% of total) lying ≤5 m elevation. In total an estimated 20.2 ± 2.5 GtC is stored in peatlands ≤5 m above sea level, which are potentially vulnerable to inundation. PMID:27354088

  17. Are iron-phosphate minerals a sink for phosphorus in anoxic Black Sea sediments?

    Directory of Open Access Journals (Sweden)

    Nikki Dijkstra

    Full Text Available Phosphorus (P is a key nutrient for marine organisms. The only long-term removal pathway for P in the marine realm is burial in sediments. Iron (Fe bound P accounts for a significant proportion of this burial at the global scale. In sediments underlying anoxic bottom waters, burial of Fe-bound P is generally assumed to be negligible because of reductive dissolution of Fe(III (oxyhydroxides and release of the associated P. However, recent work suggests that Fe-bound P is an important burial phase in euxinic (i.e. anoxic and sulfidic basin sediments in the Baltic Sea. In this study, we investigate the role of Fe-bound P as a potential sink for P in Black Sea sediments overlain by oxic and euxinic bottom waters. Sequential P extractions performed on sediments from six multicores along two shelf-to-basin transects provide evidence for the burial of Fe-bound P at all sites, including those in the euxinic deep basin. In the latter sediments, Fe-bound P accounts for more than 20% of the total sedimentary P pool. We suggest that this P is present in the form of reduced Fe-P minerals. We hypothesize that these minerals may be formed as inclusions in sulfur-disproportionating Deltaproteobacteria. Further research is required to elucidate the exact mineral form and formation mechanism of this P burial phase, as well as its role as a sink for P in sulfide-rich marine sediments.

  18. Are iron-phosphate minerals a sink for phosphorus in anoxic Black Sea sediments?

    Science.gov (United States)

    Dijkstra, Nikki; Kraal, Peter; Kuypers, Marcel M M; Schnetger, Bernhard; Slomp, Caroline P

    2014-01-01

    Phosphorus (P) is a key nutrient for marine organisms. The only long-term removal pathway for P in the marine realm is burial in sediments. Iron (Fe) bound P accounts for a significant proportion of this burial at the global scale. In sediments underlying anoxic bottom waters, burial of Fe-bound P is generally assumed to be negligible because of reductive dissolution of Fe(III) (oxyhydr)oxides and release of the associated P. However, recent work suggests that Fe-bound P is an important burial phase in euxinic (i.e. anoxic and sulfidic) basin sediments in the Baltic Sea. In this study, we investigate the role of Fe-bound P as a potential sink for P in Black Sea sediments overlain by oxic and euxinic bottom waters. Sequential P extractions performed on sediments from six multicores along two shelf-to-basin transects provide evidence for the burial of Fe-bound P at all sites, including those in the euxinic deep basin. In the latter sediments, Fe-bound P accounts for more than 20% of the total sedimentary P pool. We suggest that this P is present in the form of reduced Fe-P minerals. We hypothesize that these minerals may be formed as inclusions in sulfur-disproportionating Deltaproteobacteria. Further research is required to elucidate the exact mineral form and formation mechanism of this P burial phase, as well as its role as a sink for P in sulfide-rich marine sediments.

  19. Airborne particulate matter in spacecraft

    Science.gov (United States)

    1988-01-01

    Acceptability limits and sampling and monitoring strategies for airborne particles in spacecraft were considered. Based on instances of eye and respiratory tract irritation reported by Shuttle flight crews, the following acceptability limits for airborne particles were recommended: for flights of 1 week or less duration (1 mg/cu m for particles less than 10 microns in aerodynamic diameter (AD) plus 1 mg/cu m for particles 10 to 100 microns in AD); and for flights greater than 1 week and up to 6 months in duration (0.2 mg/cu m for particles less than 10 microns in AD plus 0.2 mg/cu m for particles 10 to 100 microns in AD. These numerical limits were recommended to aid in spacecraft atmosphere design which should aim at particulate levels that are a low as reasonably achievable. Sampling of spacecraft atmospheres for particles should include size-fractionated samples of 0 to 10, 10 to 100, and greater than 100 micron particles for mass concentration measurement and elementary chemical analysis by nondestructive analysis techniques. Morphological and chemical analyses of single particles should also be made to aid in identifying airborne particulate sources. Air cleaning systems based on inertial collection principles and fine particle collection devices based on electrostatic precipitation and filtration should be considered for incorporation into spacecraft air circulation systems. It was also recommended that research be carried out in space in the areas of health effects and particle characterization.

  20. Dans le tourbillon des particules

    CERN Document Server

    Zito, Marco

    2015-01-01

    Accélérateurs géants, détecteurs complexes, particules énigmatiques... La physique subatomique peut sembler bien intimidante pour le novice. Et pourtant, qui n a jamais entendu parler du boson de Higgs et du CERN, le laboratoire européen où il a été découvert en 2012 ? Nul besoin d être un spécialiste pour comprendre de quoi il s agit. Aujourd hui, une théorie extraordinairement élégante, le Modèle Standard, décrit tous les résultats des expériences dans le domaine. Trente-sept particules élémentaires et quatre forces fondamentales : c est tout ce dont nous avons besoin pour expliquer la matière et l Univers ! Ce livre, destiné à un large public, raconte sans équations le long parcours qui a abouti au Modèle Standard. Ce parcours, parfois sinueux, a été entamé lorsque les Grecs anciens, et peut-être d autres avant eux, ont imaginé que la matière est composée de petites « billes ». Il faudra attendre plusieurs siècles pour qu on réalise que la matière, à l échelle micros...

  1. Occurrence and behaviour of dissolved, nano-particulate and micro-particulate iron in waste waters and treatment systems: new insights from electrochemical analysis.

    Science.gov (United States)

    Matthies, R; Aplin, A C; Horrocks, B R; Mudashiru, L K

    2012-04-01

    Cyclic-, Differential Pulse- and Steady-state Microdisc Voltammetry (CV, DPV, SMV) techniques have been used to quantify the occurrence and fate of dissolved Fe(ii)/Fe(iii), nano-particulate and micro-particulate iron over a 12 month period in a series of net-acidic and net-alkaline coal mine drainages and passive treatment systems. Total iron in the mine waters is typically 10-100 mg L(-1), with values up to 2100 mg L(-1). Between 30 and 80% of the total iron occurs as solid phase, of which 20 to 80% is nano-particulate. Nano-particulate iron comprises 20 to 70% of the nominally "dissolved" (i.e. sedimentation are the only processes required to remove solid phase iron, these data have important implications for the generation or consumption of acidity during water treatment. In most waters, the majority of truly dissolved iron occurs as Fe(ii) (average 64 ± 22%). Activities of Fe(ii) do not correlate with pH and geochemical modelling shows that no Fe(ii) mineral is supersaturated. Removal of Fe(ii) must proceed via oxidation and hydrolysis. Except in waters with pH waters are generally supersaturated with respect to ferrihydrite and schwertmannite, and are not at redox equilibrium, indicating the key role of oxidation and hydrolysis kinetics on water treatment. Typically 70-100% of iron is retained in the treatment systems. Oxidation, hydrolysis, precipitation, coagulation and sedimentation occur in all treatment systems and - independent of water chemistry and the type of treatment system - hydroxides and oxyhydroxysulfates are the main iron sinks. The electrochemical data thus reveal the rationale for incomplete iron retention in individual systems and can thus inform future design criteria. The successful application of this low cost and rapid electrochemical method demonstrates its significant potential for real-time, on-site monitoring of iron-enriched waters and may in future substitute traditional analytical methods.

  2. An overview of particulate emissions from residential biomass combustion

    Science.gov (United States)

    Vicente, E. D.; Alves, C. A.

    2018-01-01

    Residential biomass burning has been pointed out as one of the largest sources of fine particles in the global troposphere with serious impacts on air quality, climate and human health. Quantitative estimations of the contribution of this source to the atmospheric particulate matter levels are hard to obtain, because emission factors vary greatly with wood type, combustion equipment and operating conditions. Updated information should improve not only regional and global biomass burning emission inventories, but also the input for atmospheric models. In this work, an extensive tabulation of particulate matter emission factors obtained worldwide is presented and critically evaluated. Existing quantifications and the suitability of specific organic markers to assign the input of residential biomass combustion to the ambient carbonaceous aerosol are also discussed. Based on these organic markers or other tracers, estimates of the contribution of this sector to observed particulate levels by receptor models for different regions around the world are compiled. Key areas requiring future research are highlighted and briefly discussed.

  3. Bioengineering towards self-assembly of particulate vaccines.

    Science.gov (United States)

    Rehm, Bernd H A

    2017-12-01

    There is an unmet demand for safe and efficient vaccines for prevention of various infectious diseases. Subunit vaccines comprise selected pathogen specific antigens are a safe alternative to whole organism vaccines. However they often lack immunogenicity. Natural and synthetic self-assembling polymers and proteins will be reviewed in view their use to encapsulate and/or display antigens to serve as immunogenic antigen carriers for induction of protective immunity. Recent advances made in in vivo assembly of antigen-displaying polyester inclusions will be a focus. Particulate vaccines are inherently immunogenic due to enhanced uptake by antigen presenting cells which process antigens mediating adaptive immune responses. Bioengineering approaches enable the design of tailor-made particulate vaccines to fine tune immune responses towards protective immunity. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Influence of particulate matter on microfouling biomass in the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Bhosle, N.B.; Nandakumar, K.; Wagh, A.B.

    ~ E :; :; 00 " " 200 '\\00 6001&. I&. Olslonc. from rne St>cre tn. miles! Leg , 0----4L~2 L~3 Leo .; Log $ Fig.3 Suspended matter (A), and particulate organic carbon (B) of surface seawater. and microfouling biomass as dry weight (C) and organic carbon...

  5. Dissolved organic matter and lake metabolism: Biogeochemistry and controls of nutrient flux dynamics in lakes: Technical progress report, 1 July 1986-30 June 1987

    International Nuclear Information System (INIS)

    Wetzel, R.G.

    1987-01-01

    Most lakes are small and possess large littoral and wetland components in the interface region between the open water per se and the drainage basin. Not only does the photosynthetic productivity of the surrounding littoral-wetland complex vastly exceed that of the pelagic zone, but the littoral-wetland vegetation and its intensive synthesis and decompositional metabolism regulate loading of inorganic nutrients passing to the open water (functioning as pulsed sources and sinks), and regulate loading of dissolved organic matter and particulate organic matter to the recipient open water, which by numerous complex pathways and mechanisms enhance or suppress pelagic productivity. Research emphasis was placed on the sources, fates, and interactions of dissolved and particulate organic matter in relation to inorganic chemical cycling: allochthonous loading to the lake system; and the coupled nutrient physiology and metabolism of phytoplankton, bacterial populations, macrophytes and attendant sessile algal-bacterial communities. Regulatory mechanisms of growth and rates of carbon and nutrient cycling were evaluated among the inorganic-organic influxes of allochthonous sources as they are controlled by wetland-littoral communities, the littoral photosynthetic producer-decomposer complex, the microflora of the sediment-water interface, and the microflora of the pelagic zone. 28 refs., 13 figs., 2 tabs

  6. Air Quality Criteria for Particulate Matter.

    Science.gov (United States)

    National Air Pollution Control Administration (DHEW), Washington, DC.

    To assist states in developing air quality standards, this book offers a review of literature related to atmospheric particulates and the development of criteria for air quality. It not only summarizes the current scientific knowledge of particulate air pollution, but points up the major deficiencies in that knowledge and the need for further…

  7. Externality costs by emission. E. Particulates

    International Nuclear Information System (INIS)

    Anon.

    1991-01-01

    Fossil-fuel-fired electricity generating systems, particularly coal and oil-fired facilities, are significant emitters of particulate matter. The major components of particulate emissions from a power plant include ash, which is made up of heavy metals, radioactive isotopes and hydrocarbons, and sulfates (SO 4 ) and nitrates (NO 3 ), which are formed by reaction of sulfur dioxide (SO 2 ) and nitrogen oxides (NO x ) in the atmosphere. The smallest ash particulates (including sulfates and nitrates) cause human respiratory effects and impaire