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.

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.

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

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

Directory of Open Access Journals (Sweden)

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

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.)

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.

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.

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...

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

Deposition and benthic mineralization of organic carbon

DEFF Research Database (Denmark)

Nordi, Gunnvor A.; Glud, Ronnie N.; Simonsen, Knud

2018-01-01

Seasonal variations in sedimentation and benthic mineralization of organic carbon (OC) were investigated in a Faroese fjord. Deposited particulate organic carbon (POC) was mainly of marine origin, with terrestrial material only accounting for b1%. On an annual basis the POC export fromthe euphotic...

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)

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

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...

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...

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...

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

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

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

Mangrove litter production and organic carbon pools in the ...

African Journals Online (AJOL)

Mngazana Estuary is an important source of mangrove litter and POC for the adjacent marine environment, possibly sustaining nearshore food webs. Keywords: Dissolved organic carbon, harvesting, litter production, mangroves, particulate organic carbon, Rhizophora mucronata, South Africa African Journal of Aquatic ...

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.

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

Directory of Open Access Journals (Sweden)

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.

A linear solvation energy relationship model of organic chemical partitioning to dissolved organic carbon.

Science.gov (United States)

Kipka, Undine; Di Toro, Dominic M

2011-09-01

Predicting the association of contaminants with both particulate and dissolved organic matter is critical in determining the fate and bioavailability of chemicals in environmental risk assessment. To date, the association of a contaminant to particulate organic matter is considered in many multimedia transport models, but the effect of dissolved organic matter is typically ignored due to a lack of either reliable models or experimental data. The partition coefficient to dissolved organic carbon (K(DOC)) may be used to estimate the fraction of a contaminant that is associated with dissolved organic matter. Models relating K(DOC) to the octanol-water partition coefficient (K(OW)) have not been successful for many types of dissolved organic carbon in the environment. Instead, linear solvation energy relationships are proposed to model the association of chemicals with dissolved organic matter. However, more chemically diverse K(DOC) data are needed to produce a more robust model. For humic acid dissolved organic carbon, the linear solvation energy relationship predicts log K(DOC) with a root mean square error of 0.43. Copyright © 2011 SETAC.

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.

[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

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.

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

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).

[Distribution characteristics of soil organic carbon and its composition in Suaeda salsa wetland in the Yellow River delta].

Science.gov (United States)

Dong, Hong-Fang; Yu, Jun-Bao; Guan, Bo

2013-01-01

Applying the method of physical fractionation, distribution characteristics of soil organic carbon and its composition in Suaeda salsa wetland in the Yellow River delta were studied. The results showed that the heavy fraction organic carbon was the dominant component of soil organic carbon in the studied region. There was a significantly positive relationship between the content of heavy fraction organic carbon, particulate organic carbon and total soil organic carbon. The ranges of soil light fraction organic carbon ratio and content were 0.008% - 0.15% and 0.10-0.40 g x kg(-1), respectively, and the range of particulate organic carbon ratio was 8.83% - 30.58%, indicating that the non-protection component of soil organic carbon was low and the carbon pool was relatively stable in Suaeda salsa wetland of the Yellow River delta.

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.

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.

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.

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...

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

Radiocarbon in particulate matter from the eastern sub-arctic Pacific Ocean: evidence of source of terrestrial carbon to the deep sea

International Nuclear Information System (INIS)

Druffel, E.R.M.; Honjo, S.; Griffin, S.; Wong, C.S.

1986-01-01

Carbon isotope ratios were measured in organic and inorganic carbon of settling particulate matter collected with a sediment trap at Ocean Station P in the Gulf of Alaska from March to October, 1983. Dissolved inorganic carbon (DIC) in surface sea water collected during two different seasons in 1984 were analyzed using large gas proportional counters and revealed a minimum seasonal Δ 14 C variation of 14 per thousand. Results show that the Δ 14 C of calcium carbonate sedimenting to the deep sea is the same as that measured in surface water DIC. In contrast, particulate organic carbon (POC) had significantly higher Δ 14 C values (by 25-70 per thousand) than that in surface water DIC. Also, the Δ 13 C of the POC was markedly lower than previously reported values from other trap stations and marine particulate matter in general. Results from this study suggest that a significant amount of the POC settling to the deep sea at this pelagic station is of terrestrial origin, not strictly of marine origin as had previously been believed

[Effects of Chinese prickly ash orchard on soil organic carbon mineralization and labile organic carbon in karst rocky desertification region of Guizhou province].

Science.gov (United States)

Zhang, Wen-Juan; Liao, Hong-Kai; Long, Jian; Li, Juan; Liu, Ling-Fei

2015-03-01

Taking 5-year-old Chinese prickly ash orchard (PO-5), 17-year-old Chinese prickly ash orchard (PO- 17), 30-year-old Chinese prickly ash orchard (PO-30) and the forest land (FL, about 60 years) in typical demonstration area of desertification control test in southwestern Guizhou as our research objects, the aim of this study using a batch incubation experiment was to research the mineralization characteristics of soil organic carbon and changes of the labile soil organic carbon contents at different depths (0-15 cm, 15-30 cm, and 30-50 cm). The results showed that: the cumulative mineralization amounts of soil organic carbon were in the order of 30-year-old Chinese prickly ash orchard, the forest land, 5-year-old Chinese prickly ash orchard and 17-year-old Chinese prickly ash orchard at corresponding depth. Distribution ratios of CO2-C cumulative mineralization amount to SOC contents were higher in Chinese prickly ash orchards than in forest land at each depth. Cultivation of Chinese prickly ash in long-term enhanced the mineralization of soil organic carbon, and decreased the stability of soil organic carbon. Readily oxidized carbon and particulate organic carbon in forest land soils were significantly more than those in Chinese prickly ash orchards at each depth (P < 0.05). With the increasing times of cultivation of Chinese prickly ash, the contents of readily oxidized carbon and particulate organic carbon first increased and then declined at 0-15 cm and 15-30 cm depth, respectively, but an opposite trend was found at 30-50 cm depth. At 0-15 cm and 15-30 cm, cultivation of Chinese prickly ash could be good for improving the contents of labile soil organic carbon in short term, but it was not conducive in long-term. In this study, we found that cultivation of Chinese prickly ash was beneficial for the accumulation of labile organic carbon at the 30-50 cm depth.

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

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

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

Production of dissolved organic carbon in aquatic sediment suspensions

NARCIS (Netherlands)

Koelmans, A.A.; Prevo, L.

2003-01-01

In many water quality models production of dissolved organic carbon (DOC) is modelled as mineralisation from particulate organic matter (POM). In this paper it is argued that the DOC production from dessicated sediments by water turbulence may be of similar importance
In many water quality

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.

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)

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.

Mercury and Organic Carbon Relationships in Streams Draining Forested Upland/Peatland Watersheds

Science.gov (United States)

R. K. Kolka; D. F. Grigal; E. S. Verry; E. A. Nater

1999-01-01

We determined the fluxes of total mecury (HgT), total organic carbon (TOC), and dissolved organic carbon (DOC) from five upland/peatland watersheds at the watershed outlet. The difference between TOC and DOC was defined as particulate OC (POC). Concentrations of HgT showed moderate to strong relationships with POC (R2 = 0.77) when all watersheds...

Scavenging of particulate elemental carbon into stratus cloud

Energy Technology Data Exchange (ETDEWEB)

Kaneyasu, Naoki; Maeda, Takahisa [National Inst. for Resources and Environment, Tsukuba (Japan)

1995-12-31

The role of atmospheric aerosols on the alternation of cloud radiative properties has widely been recognized since 1977 when Tomey and his coworkers have numerically demonstrated the effect of increased cloud condensation nuclei (CCN). At the same time, cloud processes are one of the most important factor in controlling the residence time of atmospheric aerosols through the wet removal process. The redistribution of the size and the composition of pre-cloud aerosols is also the important role of cloud process on the nature of atmospheric aerosols. In order to study these cloud-aerosol interaction phenomena, the incorporation of aerosols into cloud droplets is the first mechanism to be investigated. Among the several mechanisms for the incorporation of aerosols into cloud droplets, nucleation scavenging, is the potentially important process in the view of cloud-aerosol interactions. This critical supersaturation for a given radius of a particle can be theoretically calculated only for pure species, e.g., NaCl. However, a significant portion of the atmospheric aerosols is in the form of internal mixture of multiple components, such as SO{sub 4}{sup 2-}, NO{sub 3}{sup -}, NH{sub 4}{sup +} and particulate elemental carbon. The knowledge acquired by field measurements is therefore essential on this subject. The present study focuses on the scavenging of major components of urban atmospheric aerosols, in particular the incorporation of particulate elemental carbon into stratus cloud. Particulate elemental carbon is the strongest light absorbing species in visible region, and has potential to change the optical property of cloud. On the basis of the measurements conducted at a mountain located in the suburb of Tokyo Metropolitan area, Japan, some insights on the scavenging of particulate elemental carbon into cloud droplet will be presented

Scavenging of particulate elemental carbon into stratus cloud

Energy Technology Data Exchange (ETDEWEB)

Kaneyasu, Naoki; Maeda, Takahisa [National Inst. for Resources and Environment, Tsukuba (Japan)

1996-12-31

The role of atmospheric aerosols on the alternation of cloud radiative properties has widely been recognized since 1977 when Tomey and his coworkers have numerically demonstrated the effect of increased cloud condensation nuclei (CCN). At the same time, cloud processes are one of the most important factor in controlling the residence time of atmospheric aerosols through the wet removal process. The redistribution of the size and the composition of pre-cloud aerosols is also the important role of cloud process on the nature of atmospheric aerosols. In order to study these cloud-aerosol interaction phenomena, the incorporation of aerosols into cloud droplets is the first mechanism to be investigated. Among the several mechanisms for the incorporation of aerosols into cloud droplets, nucleation scavenging, is the potentially important process in the view of cloud-aerosol interactions. This critical supersaturation for a given radius of a particle can be theoretically calculated only for pure species, e.g., NaCl. However, a significant portion of the atmospheric aerosols is in the form of internal mixture of multiple components, such as SO{sub 4}{sup 2-}, NO{sub 3}{sup -}, NH{sub 4}{sup +} and particulate elemental carbon. The knowledge acquired by field measurements is therefore essential on this subject. The present study focuses on the scavenging of major components of urban atmospheric aerosols, in particular the incorporation of particulate elemental carbon into stratus cloud. Particulate elemental carbon is the strongest light absorbing species in visible region, and has potential to change the optical property of cloud. On the basis of the measurements conducted at a mountain located in the suburb of Tokyo Metropolitan area, Japan, some insights on the scavenging of particulate elemental carbon into cloud droplet will be presented

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

Filtration of Carbon Particulate Emissions from a Plasma Pyrolysis Assembly

Science.gov (United States)

Agui, Juan H.; Green, Robert; Vijayakumar, R.; Berger, Gordon; Greenwood, Zach; Abney, Morgan; Peterson, Elspeth

2016-01-01

NASA is investigating plasma pyrolysis as a candidate technology that will enable the recovery of hydrogen from the methane produced by the ISS Sabatier Reactor. The Plasma Pyrolysis Assembly (PPA) is the current prototype of this technology which converts the methane product from the Carbon Dioxide Reduction Assembly (CRA) to acetylene and hydrogen with 90% or greater conversion efficiency. A small amount of solid carbon particulates are generated as a side product and must be filtered before the acetylene is removed and the hydrogen-rich gas stream is recycled back to the CRA. We discuss developmental work on several options for filtering out the carbon particulate emissions from the PPA exit gas stream. The filtration technologies and concepts investigated range from fibrous media to monolithic ceramic and sintered metal media. This paper describes the different developed filter prototypes and characterizes their performance from integrated testing at the Environmental Chamber (E-Chamber) at MSFC. In addition, characterization data on the generated carbon particulates, that help to define filter requirements, are also presented.

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

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

High rates of organic carbon processing in the hyporheic zone of intermittent streams.

Science.gov (United States)

Burrows, Ryan M; Rutlidge, Helen; Bond, Nick R; Eberhard, Stefan M; Auhl, Alexandra; Andersen, Martin S; Valdez, Dominic G; Kennard, Mark J

2017-10-16

Organic carbon cycling is a fundamental process that underpins energy transfer through the biosphere. However, little is known about the rates of particulate organic carbon processing in the hyporheic zone of intermittent streams, which is often the only wetted environment remaining when surface flows cease. We used leaf litter and cotton decomposition assays, as well as rates of microbial respiration, to quantify rates of organic carbon processing in surface and hyporheic environments of intermittent and perennial streams under a range of substrate saturation conditions. Leaf litter processing was 48% greater, and cotton processing 124% greater, in the hyporheic zone compared to surface environments when calculated over multiple substrate saturation conditions. Processing was also greater in more saturated surface environments (i.e. pools). Further, rates of microbial respiration on incubated substrates in the hyporheic zone were similar to, or greater than, rates in surface environments. Our results highlight that intermittent streams are important locations for particulate organic carbon processing and that the hyporheic zone sustains this fundamental process even without surface flow. Not accounting for carbon processing in the hyporheic zone of intermittent streams may lead to an underestimation of its local ecological significance and collective contribution to landscape carbon processes.

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...

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.

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.

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.

Storage and release of organic carbon from glaciers and ice sheets

Science.gov (United States)

Hood, Eran; Battin, Tom J.; Fellman, Jason; O'Neel, Shad; Spencer, Robert G. M.

2015-02-01

Polar ice sheets and mountain glaciers, which cover roughly 11% of the Earth's land surface, store organic carbon from local and distant sources and then release it to downstream environments. Climate-driven changes to glacier runoff are expected to be larger than climate impacts on other components of the hydrological cycle, and may represent an important flux of organic carbon. A compilation of published data on dissolved organic carbon from glaciers across five continents reveals that mountain and polar glaciers represent a quantitatively important store of organic carbon. The Antarctic Ice Sheet is the repository of most of the roughly 6 petagrams (Pg) of organic carbon stored in glacier ice, but the annual release of glacier organic carbon is dominated by mountain glaciers in the case of dissolved organic carbon and the Greenland Ice Sheet in the case of particulate organic carbon. Climate change contributes to these fluxes: approximately 13% of the annual flux of glacier dissolved organic carbon is a result of glacier mass loss. These losses are expected to accelerate, leading to a cumulative loss of roughly 15 teragrams (Tg) of glacial dissolved organic carbon by 2050 due to climate change -- equivalent to about half of the annual flux of dissolved organic carbon from the Amazon River. Thus, glaciers constitute a key link between terrestrial and aquatic carbon fluxes, and will be of increasing importance in land-to-ocean fluxes of organic carbon in glacierized regions.

Storage and release of organic carbon from glaciers and ice sheets

Science.gov (United States)

Hood, Eran; Battin, Tom J.; Fellman, Jason; O'Neel, Shad; Spencer, Robert G. M.

2015-01-01

Polar ice sheets and mountain glaciers, which cover roughly 11% of the Earth's land surface, store organic carbon from local and distant sources and then release it to downstream environments. Climate-driven changes to glacier runoff are expected to be larger than climate impacts on other components of the hydrological cycle, and may represent an important flux of organic carbon. A compilation of published data on dissolved organic carbon from glaciers across five continents reveals that mountain and polar glaciers represent a quantitatively important store of organic carbon. The Antarctic Ice Sheet is the repository of most of the roughly 6 petagrams (Pg) of organic carbon stored in glacier ice, but the annual release of glacier organic carbon is dominated by mountain glaciers in the case of dissolved organic carbon and the Greenland Ice Sheet in the case of particulate organic carbon. Climate change contributes to these fluxes: approximately 13% of the annual flux of glacier dissolved organic carbon is a result of glacier mass loss. These losses are expected to accelerate, leading to a cumulative loss of roughly 15 teragrams (Tg) of glacial dissolved organic carbon by 2050 due to climate change — equivalent to about half of the annual flux of dissolved organic carbon from the Amazon River. Thus, glaciers constitute a key link between terrestrial and aquatic carbon fluxes, and will be of increasing importance in land-to-ocean fluxes of organic carbon in glacierized regions.

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

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...

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

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.

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...

Effect of particulate matrix inhibitors on microstructure and properties of 2-D carbon-carbon composites

International Nuclear Information System (INIS)

Tlomak, P.; Takano, Shigeru; Wright, M.A.; Ju, Chien-Ping.

1991-01-01

Extended-life applications of structural carbon-carbon (C-C) composites involve multiple periods of operation in high-temperature oxidizing environments and as such require a reliable oxidation protection system (OPS). Advanced OPS's generally consist of an external ceramic coating combined with an in-depth matrix inhibitor. This work investigated the effects produced by particulate inhibitors doped on the matrix on the microstructure of 2D, PAN fiber-pitch matrix C-C's. Boron and zirconium-based particulate inhibitors were added to the matrix material prior to heat treatment. A process was developed to assure a uniform distribution of the inhibitors. Oxidation behavior of such matrix-inhibited composites was evaluated using isothermal oxidation tests. 5 refs

Global anthropogenic emissions of particulate matter including black carbon

Science.gov (United States)

Klimont, Zbigniew; Kupiainen, Kaarle; Heyes, Chris; Purohit, Pallav; Cofala, Janusz; Rafaj, Peter; Borken-Kleefeld, Jens; Schöpp, Wolfgang

2017-07-01

This paper presents a comprehensive assessment of historical (1990-2010) global anthropogenic particulate matter (PM) emissions including the consistent and harmonized calculation of mass-based size distribution (PM1, PM2. 5, PM10), as well as primary carbonaceous aerosols including black carbon (BC) and organic carbon (OC). The estimates were developed with the integrated assessment model GAINS, where source- and region-specific technology characteristics are explicitly included. This assessment includes a number of previously unaccounted or often misallocated emission sources, i.e. kerosene lamps, gas flaring, diesel generators, refuse burning; some of them were reported in the past for selected regions or in the context of a particular pollutant or sector but not included as part of a total estimate. Spatially, emissions were calculated for 172 source regions (as well as international shipping), presented for 25 global regions, and allocated to 0.5° × 0.5° longitude-latitude grids. No independent estimates of emissions from forest fires and savannah burning are provided and neither windblown dust nor unpaved roads emissions are included. We estimate that global emissions of PM have not changed significantly between 1990 and 2010, showing a strong decoupling from the global increase in energy consumption and, consequently, CO2 emissions, but there are significantly different regional trends, with a particularly strong increase in East Asia and Africa and a strong decline in Europe, North America, and the Pacific region. This in turn resulted in important changes in the spatial pattern of PM burden, e.g. European, North American, and Pacific contributions to global emissions dropped from nearly 30 % in 1990 to well below 15 % in 2010, while Asia's contribution grew from just over 50 % to nearly two-thirds of the global total in 2010. For all PM species considered, Asian sources represented over 60 % of the global anthropogenic total, and residential combustion

Global anthropogenic emissions of particulate matter including black carbon

Directory of Open Access Journals (Sweden)

Z. Klimont

2017-07-01

Full Text Available This paper presents a comprehensive assessment of historical (1990–2010 global anthropogenic particulate matter (PM emissions including the consistent and harmonized calculation of mass-based size distribution (PM1, PM2. 5, PM10, as well as primary carbonaceous aerosols including black carbon (BC and organic carbon (OC. The estimates were developed with the integrated assessment model GAINS, where source- and region-specific technology characteristics are explicitly included. This assessment includes a number of previously unaccounted or often misallocated emission sources, i.e. kerosene lamps, gas flaring, diesel generators, refuse burning; some of them were reported in the past for selected regions or in the context of a particular pollutant or sector but not included as part of a total estimate. Spatially, emissions were calculated for 172 source regions (as well as international shipping, presented for 25 global regions, and allocated to 0.5°  ×  0.5° longitude–latitude grids. No independent estimates of emissions from forest fires and savannah burning are provided and neither windblown dust nor unpaved roads emissions are included. We estimate that global emissions of PM have not changed significantly between 1990 and 2010, showing a strong decoupling from the global increase in energy consumption and, consequently, CO2 emissions, but there are significantly different regional trends, with a particularly strong increase in East Asia and Africa and a strong decline in Europe, North America, and the Pacific region. This in turn resulted in important changes in the spatial pattern of PM burden, e.g. European, North American, and Pacific contributions to global emissions dropped from nearly 30 % in 1990 to well below 15 % in 2010, while Asia's contribution grew from just over 50 % to nearly two-thirds of the global total in 2010. For all PM species considered, Asian sources represented over 60 % of the global

Fluvial organic carbon flux from an eroding peatland catchment, southern Pennines, UK

Directory of Open Access Journals (Sweden)

R. R. Pawson

2008-03-01

Full Text Available This study investigates for the first time the relative importance of dissolved organic carbon (DOC and particulate organic carbon (POC in the fluvial carbon flux from an actively eroding peatland catchment in the southern Pennines, UK. Event scale variability in DOC and POC was examined and the annual flux of fluvial organic carbon was estimated for the catchment. At the event scale, both DOC and POC were found to increase with discharge, with event based POC export accounting for 95% of flux in only 8% of the time. On an annual cycle, exports of 35.14 t organic carbon (OC are estimated from the catchment, which represents an areal value of 92.47 g C m⁻² a⁻¹. POC was the most significant form of organic carbon export, accounting for 80% of the estimated flux. This suggests that more research is required on both the fate of POC and the rates of POC export in eroding peatland catchments.

Radiocarbon and stable-isotope geochemistry of organic and inorganic carbon in Lake Superior

Science.gov (United States)

Zigah, Prosper K.; Minor, Elizabeth C.; Werne, Josef P.

2012-03-01

We present a lake-wide investigation of Lake Superior carbon and organic matter biogeochemistry using radiocarbon, stable isotope, and carbon concentrations. Dissolved inorganic carbon (DIC) abundance in the lake was 121-122 Tg C, with offshore concentration andδ13C values being laterally homogenous and tightly coupled to the physical and thermal regime and biochemical processes. Offshore Δ14C of DIC (50-65‰) exhibited lateral homogeneity and was more 14C enriched than co-occurring atmospheric CO2 (˜38‰); nearshore Δ14C of DIC (36-38‰) was similar to atmospheric CO2. Dissolved organic carbon (DOC) abundance was 14.2-16.4 Tg C. DOC's concentration and δ13C were homogenous in June (mixed lake), but varied laterally during August (stratification) possibly due to spatial differences in lake productivity. Throughout sampling, DOC had modern radiocarbon values (14-58‰) indicating a semilabile nature with a turnover time of ≤60 years. Lake particulate organic carbon (POC, 0.9-1.3 Tg C) was consistently 13C depleted relative to DOC. The δ15N of epilimnetic particulate organic nitrogen shifted to more negative values during stratification possibly indicating greater use of nitrate (rather than ammonium) by phytoplankton in August. POC's radiocarbon was spatially heterogeneous (Δ14C range: 58‰ to -303‰), and generally 14C depleted relative to DOC and DIC. POC 14C depletion could not be accounted for by black carbon in the lake but, because of its spatial and temporal distribution, is attributed to sediment resuspension. The presence of old POC within the epilimnion of the open lake indicates possible benthic-pelagic coupling in the lake's organic carbon cycle; the ultimate fate of this old POC bears further investigation.

Particulate Matter and Black Carbon Concentration Levels in Ashaiman, a Semi-Urban Area of Ghana, 2008

OpenAIRE

Sam-Quarcoo Dotse; Joshua Kwame Asane; F.G. Ofosu

2012-01-01

Particulate matter and black carbon concentration levels in Ashaiman, a semi-urban area of Ghana was assessed. Using IVL PM2.5 and PM10 particle samplers, airborne particulate matter was sampled on Teflon filters for a period of three months. In addition to determination of particulate mass in the two fractions by gravimetrical method, aerosol filters were analyzed to determine Black Carbon (BC) concentration levels using the black smoke method. BC fractions in fine and coarse, together with ...

Carbonaceous Aerosols in Fine Particulate Matter of Santiago Metropolitan Area, Chile

Science.gov (United States)

Toro Araya, Richard; Flocchini, Robert; Morales Segura, Rául G. E.; Leiva Guzmán, Manuel A.

2014-01-01

Measurements of carbonaceous aerosols in South American cities are limited, and most existing data are of short term and limited to only a few locations. For 6 years (2002–2007), concentrations of fine particulate matter and organic and elemental carbon were measured continuously in the capital of Chile. The contribution of carbonaceous aerosols to the primary and secondary fractions was estimated at three different sampling sites and in the warm and cool seasons. The results demonstrate that there are significant differences in the levels in both the cold (March to August) and warm (September to February) seasons at all sites studied. The percent contribution of total carbonaceous aerosol fine particulate matter was greater in the cool season (53 ± 41%) than in the warm season (44 ± 18%). On average, the secondary organic carbon in the city corresponded to 29% of the total organic carbon. In cold periods, this proportion may reach an average of 38%. A comparison of the results with the air quality standards for fine particulate matter indicates that the total carbonaceous fraction alone exceeds the World Health Organization standard (10 µg/m3) and the United States Environmental Protection Agency standard (15 µg/m3) for fine particulate matter. PMID:24587753

Carbonaceous Aerosols in Fine Particulate Matter of Santiago Metropolitan Area, Chile

Directory of Open Access Journals (Sweden)

Richard Toro Araya

2014-01-01

Full Text Available Measurements of carbonaceous aerosols in South American cities are limited, and most existing data are of short term and limited to only a few locations. For 6 years (2002–2007, concentrations of fine particulate matter and organic and elemental carbon were measured continuously in the capital of Chile. The contribution of carbonaceous aerosols to the primary and secondary fractions was estimated at three different sampling sites and in the warm and cool seasons. The results demonstrate that there are significant differences in the levels in both the cold (March to August and warm (September to February seasons at all sites studied. The percent contribution of total carbonaceous aerosol fine particulate matter was greater in the cool season (53 ± 41% than in the warm season (44 ± 18%. On average, the secondary organic carbon in the city corresponded to 29% of the total organic carbon. In cold periods, this proportion may reach an average of 38%. A comparison of the results with the air quality standards for fine particulate matter indicates that the total carbonaceous fraction alone exceeds the World Health Organization standard (10 µg/m3 and the United States Environmental Protection Agency standard (15 µg/m3 for fine particulate matter.

Carbonaceous aerosols in fine particulate matter of Santiago Metropolitan Area, Chile.

Science.gov (United States)

Toro Araya, Richard; Flocchini, Robert; Morales Segura, Rául G E; Leiva Guzmán, Manuel A

2014-01-01

Measurements of carbonaceous aerosols in South American cities are limited, and most existing data are of short term and limited to only a few locations. For 6 years (2002-2007), concentrations of fine particulate matter and organic and elemental carbon were measured continuously in the capital of Chile. The contribution of carbonaceous aerosols to the primary and secondary fractions was estimated at three different sampling sites and in the warm and cool seasons. The results demonstrate that there are significant differences in the levels in both the cold (March to August) and warm (September to February) seasons at all sites studied. The percent contribution of total carbonaceous aerosol fine particulate matter was greater in the cool season (53 ± 41%) than in the warm season (44 ± 18%). On average, the secondary organic carbon in the city corresponded to 29% of the total organic carbon. In cold periods, this proportion may reach an average of 38%. A comparison of the results with the air quality standards for fine particulate matter indicates that the total carbonaceous fraction alone exceeds the World Health Organization standard (10 µg/m(3)) and the United States Environmental Protection Agency standard (15 µg/m(3)) for fine particulate matter.

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.

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.

Particulate barium tracing of significant mesopelagic carbon remineralisation in the North Atlantic

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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

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...

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.

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

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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

Hydrothermal Fe cycling and deep ocean organic carbon scavenging: Model-based evidence for significant POC supply to seafloor sediments

Digital Repository Service at National Institute of Oceanography (India)

German, C.R.; Legendre, L.L.; Sander, S.G.;; Niquil, N.; Luther-III, G.W.; LokaBharathi, P.A.; Han, X.; LeBris, N.

by more than ~10% over background values, what the model does indicate is that scavenging of carbon in association with Fe-rich hydrothermal plume particles should play a significant role in the delivery of particulate organic carbon to deep ocean...

Examining organic carbon transport by the Orinoco River using SeaWiFS imagery

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López, Ramón; Del Castillo, Carlos E.; Miller, Richard L.; Salisbury, Joseph; Wisser, Dominik

2012-09-01

The Orinoco River is the fourth largest in the world in terms of water discharge and organic carbon export to the ocean. River export of organic carbon is a key component of the carbon cycle and the global carbon budget. Here, we examined the seasonal transport of organic carbon by the Orinoco River into the eastern Caribbean using the conservative relationship of colored dissolved organic matter (CDOM) and dissolved organic carbon (DOC) in low salinity coastal waters influenced by river plumes. In situ measurements of CDOM absorption, DOC, and salinity were used to develop an empirical model for DOC concentration at the Orinoco River Plume. Satellite remote sensing reflectances were used with empirical models to determine DOC and Particulate organic carbon (POC) river transport. Our estimates of CDOM and DOC significantly correlated with in situ measurements and were within the expected ranges for the river. Total organic carbon transport by the Orinoco River during the period of 1998 to 2010 was 7.10 ×1012 g C y-1, from 5.29 × 1012 g C y-1 of DOC and 1.81 × 1012 g C y-1 of POC, representing ˜6% increase to previous published estimates. The variability in organic carbon transport responded to the seasonality in river flow more than to changes in organic carbon concentration in the river. Our results corroborate that is possible to estimate organic carbon transport using ocean color data at global scales. This is needed to reduce the uncertainties of land-ocean carbon fluxes.

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...

Heterogeneous Oxidation of Atmospheric Organic Aerosol: Kinetics of Changes to the Amount and Oxidation State of Particle-Phase Organic Carbon.

Science.gov (United States)

Kroll, Jesse H; Lim, Christopher Y; Kessler, Sean H; Wilson, Kevin R

2015-11-05

Atmospheric oxidation reactions are known to affect the chemical composition of organic aerosol (OA) particles over timescales of several days, but the details of such oxidative aging reactions are poorly understood. In this study we examine the rates and products of a key class of aging reaction, the heterogeneous oxidation of particle-phase organic species by the gas-phase hydroxyl radical (OH). We compile and reanalyze a number of previous studies from our laboratories involving the oxidation of single-component organic particles. All kinetic and product data are described on a common basis, enabling a straightforward comparison among different chemical systems and experimental conditions. Oxidation chemistry is described in terms of changes to key ensemble properties of the OA, rather than to its detailed molecular composition, focusing on two quantities in particular, the amount and the oxidation state of the particle-phase carbon. Heterogeneous oxidation increases the oxidation state of particulate carbon, with the rate of increase determined by the detailed chemical mechanism. At the same time, the amount of particle-phase carbon decreases with oxidation, due to fragmentation (C-C scission) reactions that form small, volatile products that escape to the gas phase. In contrast to the oxidation state increase, the rate of carbon loss is nearly uniform among most systems studied. Extrapolation of these results to atmospheric conditions indicates that heterogeneous oxidation can have a substantial effect on the amount and composition of atmospheric OA over timescales of several days, a prediction that is broadly in line with available measurements of OA evolution over such long timescales. In particular, 3-13% of particle-phase carbon is lost to the gas phase after one week of heterogeneous oxidation. Our results indicate that oxidative aging represents an important sink for particulate organic carbon, and more generally that fragmentation reactions play a major

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.

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

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

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

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

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.

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

Long-term dynamics of dissolved organic carbon: implications for drinking water supply.

Science.gov (United States)

Ledesma, José L J; Köhler, Stephan J; Futter, Martyn N

2012-08-15

Surface waters are the main source of drinking water in many regions. Increasing organic carbon concentrations are a cause for concern in Nordic countries since both dissolved and particulate organic carbon can transport contaminants and adversely affect drinking water treatment processes. We present a long-term study of dynamics of total (particulate and dissolved) organic carbon (TOC) concentrations in the River Fyris. This river supplies drinking water to approximately 200000 people in Uppsala, Sweden. The River Fyris is a main tributary to Lake Mälaren, which supplies drinking water to approximately 2 million people in the greater Stockholm area. Utilities responsible for drinking water supply in both Uppsala and Stockholm have expressed concerns about possible increases in TOC. We evaluate organic carbon dynamics within the Fyris catchment by calculating areal mass exports using observed TOC concentrations and modeled flows and by modeling dissolved organic carbon (as a proxy for TOC) using the dynamic, process based INCA-C model. Exports of TOC from the catchment ranged from 0.8 to 5.8 g m(-2) year(-1) in the period 1995-2010. The variation in annual exports was related to climatic variability which influenced seasonality and amount of runoff. Exports and discharge uncoupled at the end of 2008. A dramatic increase in TOC concentrations was observed in 2009, which gradually declined in 2010-2011. INCA-C successfully reproduced the intra- and inter-annual variation in concentrations during 1996-2008 and 2010-2011 but failed to capture the anomalous increase in 2009. We evaluated a number of hypotheses to explain the anomaly in 2009 TOC values, ultimately none proved satisfactory. We draw two main conclusions: there is at least one unknown or unmeasured process controlling or influencing surface water TOC and INCA-C can be used as part of the decision-making process for current and future use of rivers for drinking water supply. Copyright © 2012 Elsevier B

Transformation of soil organic matter in a Japanese larch forest. Radiocarbon and stable carbon isotope compositions versus soil depth

International Nuclear Information System (INIS)

Liu Wei; Moriizumi, Jun; Yamazawa, Hiromi; Iida, Takao

2008-01-01

Soil organic matter at a depth of 0-55 cm, collected from a Japanese larch forest area, was separated into particulate organic matter (size >53 μm), particulate organic matter (size 14 C and δ 13 C values were determined. The Δ 14 C values of particulate matters decreased greatly from 128 per mille to -278 per mille, indicating a relative increase of resistant organic components in particulate matters. That of humic acid matter decreased from 183 per mille to -139 per mille. For these of organic matter fractions at the same depth, the Δ 14 C values of particulate matter (size >53μm) are smallest and those of humic acid matter are the largest. That indicates that a high contribution of young organic matter to the humic acid matter exists and transformation tendency of particulate matter may be from coarse to small in the particulate size. Positive Δ 14 C values appeared at a depth of 10 cm, 25 cm, and 35 cm for the particulate organic matter (size >53μm), particulate organic matter (size 14 C values of the humic acid matter also infects that the bomb carbon has reached the depth of 35 cm. Additionally, the Δ 14 C values of these three kinds of organic matters ranged from 50 per mille to 183 per mille at a depth of 0-7 cm, which were not smaller than that of litter in the forest area, indicating high proportion of modern, plants-derived soil organic matter in this depth ranges. The δ 13 C values increased from -28 per mille to -23 per mille with the increase depth of 0-55 cm. The δ 13 C values of humic acid matter are approximately less than that of particulate matters at the same depth, which may be explained as a high contribution of young organic matter to the humic acid matter. (author)

Content and carbon stocks in labile and recalcitrant organic matter of the soil under crop-livestock integration in Cerrado

Directory of Open Access Journals (Sweden)

Itaynara Batista

2013-12-01

Full Text Available The study of organic matter and its compartments and their relationship with management, aims to develop strategies for increasing their levels in soils and better understanding of its dynamics. This work aimed to evaluate the fractions of soil organic matter and their carbon stocks in different soil cover system in crop-livestock integration and native Cerrado vegetation. The study was conducted at the farm Cabeceira, Maracajú – MS, sample area have the following history: soybean/corn + brachiaria/cotton/oat + pasture/soybean/formation of pasture/grazing, sampling was carried out in two seasons, dry (May/2009 and rainy (March 2010, in the dry season, crops present were: pasture, corn and cotton + brachiaria and in the rainy season were corn, cotton and soybeans, so the areas in the two evaluation periods were: pasture / maize + brachiaria / cotton, cotton / soybean area and a native of Savanna. Was performed to determine the exchangeable cations, particle size analysis, bulk density, organic carbon, particle size fractionation of organic matter of the soil with the quantification of particulate organic carbon (POC and organic carbon associated with minerals (OCam. Was also quantified the carbon stock and size fractions. The area of pasture / maize showed higher carbon stock in the particulate fraction in the topsoil. The area of cotton / soy due to its lower clay, showed the greatest loss of carbon. Because of the areas have the same history, the stock of more recalcitrant fraction was not sensitive to variations in coverage. The POC fraction appears more sensitive to different soil covers and seasonality.

Secondary organic carbon quantification and source apportionment of PM10 in Kaifeng, China

Institute of Scientific and Technical Information of China (English)

WU Lin; FENG Yinchang; WU Jianhui; ZHU Tan; BI Xiaohui; HAN Bo; YANG Weihong; YANG Zhiqiang

2009-01-01

During 2005, the filter samples of ambient PM10 from five sites and the source samples of particulate matter were collected in Kaifeng, Henan province of China. Nineteen elements, water-soluble ions, total carbon (TC) and organic carbon (OC) contained in samples were analyzed. Seven contributive source types were identified and their contributions to ambient PM10 were estimated by chemical mass balance (CMB) receptor model. Weak associations between the concentrations of organic carbon and element carbon (EC) were observed during the sampling periods, indicating that there was secondary organic aerosol pollution in the urban atmosphere. An indirect method of "OC/EC minimum ratio" was applied to estimate the concentration of secondary organic carbon (SOC). The results showed that SOC contributed 26.2%, 32.4% and 18.0% of TC in spring, summer-fall and winter respectively, and the annual average SOC concentration was 7.07 μg/m3, accounting for 5.73% of the total mass in ambient PM10. The carbon species concentrations in ambient PM10 were recalculated by subtracting the SOC concentrations from measured concentrations of TC and OC to increase the compatibility of source and receptor measurements for CMB model.

Organic carbon in glacial fjords of Chilean Patagonia

Science.gov (United States)

Pantoja, Silvio; Gutiérrez, Marcelo; Tapia, Fabián; Abarzúa, Leslie; Daneri, Giovanni; Reid, Brian; Díez, Beatriz

2016-04-01

The Southern Ice Field in Chilean Patagonia is the largest (13,000 km2) temperate ice mass in the Southern hemisphere, yearly transporting ca. 40 km3 of freshwater to fjords. This volume of fresh and cold water likely affects adjacent marine ecosystems by changing circulation, productivity, food web dynamics, and the abundance and distribution of planktonic and benthic organisms. We hypothesize that freshwater-driven availability of inorganic nutrient and transport of organic and inorganic suspended matter, as well as microbes, become a controlling factor for productivity in the fjord associated with the Baker river and Jorge Montt glacier. Both appear to be sources of silicic acid, but not of nitrate and particulate organic carbon, especially during summer, when surface PAR and glacier thawing are maximal. In contrast to Baker River, the Jorge Montt glacier is also a source of dissolved organic carbon towards a proglacial fjord and the Baker Channel, indicating that a thorough chemical description of sources (tidewater glacier and glacial river) is needed. Nitrate in fiord waters reaches ca. 15 μM at 25 m depth with no evidence of mixing up during summer. Stable isotope composition of particulate organic nitrogen reaches values as low as 3 per mil in low-salinity waters near both glacier and river. Nitrogen fixation could be depleting δ15N in organic matter, as suggested by the detection at surface waters of nif H genes belonging to diazotrophs near the Montt glacier. As diazotrophs have also been detected in other cold marine waters (e.g. Baltic Sea, Arctic Ocean) as well as glaciers and polar terrestrial waters, there is certainly a potential for both marine and freshwater microbes to contribute and have a significant impact on the Patagonian N and C budgets. Assessing the impact of freshwater on C and N fluxes and the microbial community structure in Patagonian waters will allow understanding future scenarios of rapid glacier melting. This research was funded

Time-resolved analysis of particle emissions from residential biomass combustion - Emissions of refractory black carbon, PAHs and organic tracers

Science.gov (United States)

Nielsen, Ingeborg E.; Eriksson, Axel C.; Lindgren, Robert; Martinsson, Johan; Nyström, Robin; Nordin, Erik Z.; Sadiktsis, Ioannis; Boman, Christoffer; Nøjgaard, Jacob K.; Pagels, Joakim

2017-09-01

Time-resolved particle emissions from a conventional wood stove were investigated with aerosol mass spectrometry to provide links between combustion conditions, emission factors, mixing state of refractory black carbon and implications for organic tracer methods. The addition of a new batch of fuel results in low temperature pyrolysis as the fuel heats up, resulting in strong, short-lived, variable emission peaks of organic aerosol-containing markers of anhydrous sugars, such as levoglucosan (fragment at m/z 60). Flaming combustion results in emissions dominated by refractory black carbon co-emitted with minor fractions of organic aerosol and markers of anhydrous sugars. Full cycle emissions are an external mixture of larger organic aerosol-dominated and smaller thinly coated refractory black carbon particles. A very high burn rate results in increased full cycle mass emission factors of 66, 2.7, 2.8 and 1.3 for particulate polycyclic aromatic hydrocarbons, refractory black carbon, total organic aerosol and m/z 60, respectively, compared to nominal burn rate. Polycyclic aromatic hydrocarbons are primarily associated with refractory black carbon-containing particles. We hypothesize that at very high burn rates, the central parts of the combustion zone become air starved, leading to a locally reduced combustion temperature that reduces the conversion rates from polycyclic aromatic hydrocarbons to refractory black carbon. This facilitates a strong increase of polycyclic aromatic hydrocarbons emissions. At nominal burn rates, full cycle emissions based on m/z 60 correlate well with organic aerosol, refractory black carbon and particulate matter. However, at higher burn rates, m/z 60 does not correlate with increased emissions of polycyclic aromatic hydrocarbons, refractory black carbon and organic aerosol in the flaming phase. The new knowledge can be used to advance source apportionment studies, reduce emissions of genotoxic compounds and model the climate impacts of

[Dynamics of unprotected soil organic carbon with the restoration process of Pinus massoniana plantation in red soil erosion area].

Science.gov (United States)

Lü, Mao-Kui; Xie, Jin-Sheng; Zhou, Yan-Xiang; Zeng, Hong-Da; Jiang, Jun; Chen, Xi-Xiang; Xu, Chao; Chen, Tan; Fu, Lin-Chi

2014-01-01

By the method of spatiotemporal substitution and taking the bare land and secondary forest as the control, we measured light fraction and particulate organic carbon in the topsoil under the Pinus massoniana woodlands of different ages with similar management histories in a red soil erosion area, to determine their dynamics and evaluate the conversion processes from unprotected to protected organic carbon. The results showed that the content and storage of soil organic carbon increased significantly along with ages in the process of vegetation restoration (P organic carbon content and distribution proportion to the total soil organic carbon increased significantly (P organic carbon mostly accumulated in the form of unprotected soil organic carbon during the initial restoration period, and reached a stable level after long-term vegetation restoration. Positive correlations were found between restoration years and the rate constant for C transferring from the unprotected to the protected soil pool (k) in 0-10 cm and 10-20 cm soil layers, which demonstrated that the unprotected soil organic carbon gradually transferred to the protected soil organic carbon in the process of vegetation restoration.

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.

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.

Carbon amendment stimulates benthic nitrogen cycling during the bioremediation of particulate aquaculture waste

Science.gov (United States)

Robinson, Georgina; MacTavish, Thomas; Savage, Candida; Caldwell, Gary S.; Jones, Clifford L. W.; Probyn, Trevor; Eyre, Bradley D.; Stead, Selina M.

2018-03-01

The treatment of organic wastes remains one of the key sustainability challenges facing the growing global aquaculture industry. Bioremediation systems based on coupled bioturbation-microbial processing offer a promising route for waste management. We present, for the first time, a combined biogeochemical-molecular analysis of the short-term performance of one such system that is designed to receive nitrogen-rich particulate aquaculture wastes. Using sea cucumbers (Holothuria scabra) as a model bioturbator we provide evidence that adjusting the waste C : N from 5 : 1 to 20 : 1 promoted a shift in nitrogen cycling pathways towards the dissimilatory nitrate reduction to ammonium (DNRA), resulting in net NH4+ efflux from the sediment. The carbon amended treatment exhibited an overall net N2 uptake, whereas the control receiving only aquaculture waste exhibited net N2 production, suggesting that carbon supplementation enhanced nitrogen fixation. The higher NH4+ efflux and N2 uptake was further supported by meta-genome predictions that indicate that organic-carbon addition stimulated DNRA over denitrification. These findings indicate that carbon addition may potentially result in greater retention of nitrogen within the system; however, longer-term trials are necessary to determine whether this nitrogen retention is translated into improved sea cucumber biomass yields. Whether this truly constitutes a remediation process is open for debate as there remains the risk that any increased nitrogen retention may be temporary, with any subsequent release potentially raising the eutrophication risk. Longer and larger-scale trials are required before this approach may be validated with the complexities of the in-system nitrogen cycle being fully understood.

40 CFR 89.112 - Oxides of nitrogen, carbon monoxide, hydrocarbon, and particulate matter exhaust emission standards.

Science.gov (United States)

2010-07-01

....112 Oxides of nitrogen, carbon monoxide, hydrocarbon, and particulate matter exhaust emission... emissions of oxides of nitrogen, carbon monoxide, hydrocarbon, and nonmethane hydrocarbon are measured using... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Oxides of nitrogen, carbon monoxide...

Particulate inverse opal carbon electrodes for lithium-ion batteries.

Science.gov (United States)

Kang, Da-Young; Kim, Sang-Ok; Chae, Yu Jin; Lee, Joong Kee; Moon, Jun Hyuk

2013-01-29

Inverse opal carbon materials were used as anodes for lithium ion batteries. We applied particulate inverse opal structures and their dispersion in the formation of anode electrodes via solution casting. We prepared aminophenyl-grafted inverse opal carbons (a-IOC), inverse opal carbons with mesopores (mIOC), and bare inverse opal carbons (IOC) and investigated the electrochemical behavior of these samples as anode materials. Surface modification by aminophenyl groups was confirmed by XPS measurements. TEM images showed mesopores, and the specific area of mIOC was compared with that of IOC using BET analysis. A half-cell test was performed to compare a-IOC with IOC and mIOC with IOC. In the case of the a-IOC structure, the cell test revealed no improvement in the reversible specific capacity or the cycle performance. The mIOC cell showed a reversible specific capacity of 432 mAh/g, and the capacity was maintained at 88%-approximately 380 mAh/g-over 20 cycles.

Feasibility of plasma aftertreatment for simultaneous control of NOx and particulates

International Nuclear Information System (INIS)

Brusasco, R M; Merritt, B T; Penetrante, B; Pitz, W J; Vogtlin, G E

1999-01-01

Plasma reactors can be operated as a particulate trap or as a NOx converter. Particulate trapping in a plasma reactor can be accomplished by electrostatic precipitation. The soluble organic fraction of the trapped particulates can be utilized for the hydrocarbon-enhanced oxidation of NO to NO2 . The NO2 can then be used to non-thermally oxidize the carbon fraction of the particulates. The oxidation of the carbon fraction by NO2 can lead to reduction of NOx or backconversion of NO2 to NO. This paper examines the hydrocarbon and electrical energy density requirements in a plasma for maximum NOx conversion in both heavy-duty and light-duty diesel engine exhaust. The energy density required for complete oxidation of hydrocarbons is also examined and shown to be much greater than that required for maximum NOx conversion. The reaction of NO2 with carbon is shown to lead mainly to backconversion of NO2 to NO. These results suggest that the combination of the plasma with a catalyst will be required to reduce the NOx and oxidize the hydrocarbons. The plasma reactor can be operated occasionally in the arc mode to thermally oxidize the carbon fraction of the particulates

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...

[Effects of precipitation intensity on soil organic carbon fractions and their distribution under subtropical forests of South China].

Science.gov (United States)

Chen, Xiao-mei; Liu, Ju-xiu; Deng, Qi; Chu, Guo-wei; Zhou, Guo-yi; Zhang, De-qiang

2010-05-01

From December 2006 to June 2008, a field experiment was conducted to study the effects of natural precipitation, doubled precipitation, and no precipitation on the soil organic carbon fractions and their distribution under a successional series of monsoon evergreen broad-leaf forest, pine and broad-leaf mixed forest, and pine forest in Dinghushan Mountain of Southern China. Different precipitation treatments had no significant effects on the total organic carbon (TOC) concentration in the same soil layer under the same forest type (P > 0.05). In treatment no precipitation, particulate organic carbon (POC) and light fraction organic carbon (LFOC) were mainly accumulated in surface soil layer (0-10 cm); but in treatments natural precipitation and doubled precipitation, the two fractions were infiltrated to deeper soil layers. Under pine forest, soil readily oxidizable organic carbon (ROC) was significantly higher in treatment no precipitation than in treatments natural precipitation and doubled precipitation (P organic carbon storage. Precipitation intensity less affected TOC, but had greater effects on the labile components POC, ROC, and LFOC.

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.

Deforestation impacts on soil organic carbon stocks in the Semiarid Chaco Region, Argentina.

Science.gov (United States)

Villarino, Sebastián Horacio; Studdert, Guillermo Alberto; Baldassini, Pablo; Cendoya, María Gabriela; Ciuffoli, Lucía; Mastrángelo, Matias; Piñeiro, Gervasio

2017-01-01

Land use change affects soil organic carbon (SOC) and generates CO 2 emissions. Moreover, SOC depletion entails degradation of soil functions that support ecosystem services. Large areas covered by dry forests have been cleared in the Semiarid Chaco Region of Argentina for cropping expansion. However, deforestation impacts on the SOC stock and its distribution in the soil profile have been scarcely reported. We assessed these impacts based on the analysis of field data along a time-since-deforestation-for-cropping chronosequence, and remote sensing indices. Soil organic C was determined up to 100cm depth and physically fractionated into mineral associated organic carbon (MAOC) and particulate organic C (POC). Models describing vertical distribution of SOC were fitted. Total SOC, POC and MAOC stocks decreased markedly with increasing cropping age. Particulate organic C was the most sensitive fraction to cultivation. After 10yr of cropping SOC loss was around 30%, with greater POC loss (near 60%) and smaller MAOC loss (near 15%), at 0-30cm depth. Similar relative SOC losses were observed in deeper soil layers (30-60 and 60-100cm). Deforestation and subsequent cropping also modified SOC vertical distribution. Soil organic C loss was negatively associated with the proportion of maize in the rotation and total crop biomass inputs, but positively associated with the proportion of soybean in the rotation. Without effective land use polices, deforestation and agricultural expansion can lead to rapid soil degradation and reductions in the provision of important ecosystem services. Copyright © 2016 Elsevier B.V. All rights reserved.

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.

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

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.

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.

Carbonaceous material in fine particulate matter (PM10) of urban areas

International Nuclear Information System (INIS)

Brocco, Domenico; Leonardi, Vittorio; Maso; Marco; Prignani, Patrizia

2006-01-01

Total carbon (TC), elemental carbon (EC) and organic carbon (OC) in the fine particulate matter (PM10) were measured in the urban areas of Rome and Marino (Castelli Romani) by means a thermal method with a non-dispersive infrared detector (NDIR). The results showed that carbonaceous material constitutes 30-40% of the total aerosols in Rome and about 20% in Marino [it

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...

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

Fossil and nonfossil carbon in fine particulate matter: A study of five European cities

Science.gov (United States)

Glasius, Marianne; La Cour, Agnete; Lohse, Christian

2011-06-01

Fossil carbon in particulate matter comes from anthropogenic use and combustion of fossil fuels, while nonfossil carbon may originate from both biogenic (e.g., pollen, plant debris, fungal spores, and biogenic secondary organic aerosol (SOA)) and anthropogenic sources (e.g., cooking and residential wood combustion). We investigated the relative contributions of fossil and nonfossil sources to fine carbonaceous aerosols in five European cities by radiocarbon analysis of aerosol samples collected at four types of sites in 2002-2004. The average fraction of nonfossil carbon was 43 ± 11%, with the lowest fraction, 36 ± 7%, at urban curbside sites and the highest fraction, 54 ± 11%, at rural background sites, farthest away from the impact of man-made emissions. Generally, fossil carbon concentrations at urban curbside sites are elevated in comparison to background sites, which is expected because of their proximity to vehicular emissions. Contrary to what might be expected, the concentration of nonfossil carbon is also higher at curbside than at background sites. This may be attributable to differences between site categories in levels of primary biological aerosols, brake and tire wear in resuspended road dust, biofuels, emissions from cooking and residential wood combustion, or processes such as anthropogenic enhancement of biogenic SOA and increased partitioning of semivolatile compounds into the aerosol phase at urban sites. The exact causes should be investigated by future detailed source analyses.

Organic carbon production, mineralization and preservation on the Peruvian margin

Science.gov (United States)

Dale, A. W.; Sommer, S.; Lomnitz, U.; Montes, I.; Treude, T.; Gier, J.; Hensen, C.; Dengler, M.; Stolpovsky, K.; Bryant, L. D.; Wallmann, K.

2014-09-01

Carbon cycling in Peruvian margin sediments (11° S and 12° S) was examined at 16 stations from 74 m on the inner shelf down to 1024 m water depth by means of in situ flux measurements, sedimentary geochemistry and modeling. Bottom water oxygen was below detection limit down to ca. 400 m and increased to 53 μM at the deepest station. Sediment accumulation rates and benthic dissolved inorganic carbon fluxes decreased rapidly with water depth. Particulate organic carbon (POC) content was lowest on the inner shelf and at the deep oxygenated stations (< 5%) and highest between 200 and 400 m in the oxygen minimum zone (OMZ, 15-20%). The organic carbon burial efficiency (CBE) was unexpectedly low on the inner shelf (< 20%) when compared to a global database, for reasons which may be linked to the frequent ventilation of the shelf by oceanographic anomalies. CBE at the deeper oxygenated sites was much higher than expected (max. 81%). Elsewhere, CBEs were mostly above the range expected for sediments underlying normal oxic bottom waters, with an average of 51 and 58% for the 11° S and 12° S transects, respectively. Organic carbon rain rates calculated from the benthic fluxes alluded to a very efficient mineralization of organic matter in the water column, with a Martin curve exponent typical of normal oxic waters (0.88 ± 0.09). Yet, mean POC burial rates were 2-5 times higher than the global average for continental margins. The observations at the Peruvian margin suggest that a lack of oxygen does not affect the degradation of organic matter in the water column but promotes the preservation of organic matter in marine sediments.

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.

Organic carbon efflux from a deciduous forest catchment in Korea

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S. J. Kim

2010-04-01

Full Text Available Soil infiltration and surface discharge of precipitation are critical processes that affect the efflux of Dissolved Organic Carbon (DOC and Particulate Organic Carbon (POC in forested catchments. Concentrations of DOC and POC can be very high in the soil surface in most forest ecosystems and their efflux may not be negligible particularly under the monsoon climate. In East Asia, however, there are little data available to evaluate the role of such processes in forest carbon budget. In this paper, we address two basic questions: (1 how does stream discharge respond to storm events in a forest catchment? and (2 how much DOC and POC are exported from the catchment particularly during the summer monsoon period? To answer these questions, we collected hydrological data (e.g., precipitation, soil moisture, runoff discharge, groundwater level and conducted hydrochemical analyses (including DOC, POC, and six tracers in a deciduous forest catchment in Gwangneung National Arboretum in west-central Korea. Based on the end-member mixing analysis of the six storm events during the summer monsoon in 2005, the surface discharge was estimated as 30 to 80% of the total runoff discharge. The stream discharge responded to precipitation within 12 h during these storm events. The annual efflux of DOC and POC from the catchment was estimated as 0.04 and 0.05 t C ha⁻¹ yr⁻¹, respectively. Approximately 70% of the annual organic carbon efflux occurred during the summer monsoon period. Overall, the annual efflux of organic carbon was estimated to be about 10% of the Net Ecosystem carbon Exchange (NEE obtained by eddy covariance measurement at the same site. Considering the current trends of increasing intensity and amount of summer rainfall and the large interannual variability in NEE, ignoring the organic carbon efflux from forest catchments would result in an inaccurate estimation of the carbon sink strength of forest ecosystems in the monsoon

Input related microbial carbon dynamic of soil organic matter in particle size fractions

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Gude, A.; Kandeler, E.; Gleixner, G.

2012-04-01

This paper investigated the flow of carbon into different groups of soil microorganisms isolated from different particle size fractions. Two agricultural sites of contrasting organic matter input were compared. Both soils had been submitted to vegetation change from C3 (Rye/Wheat) to C4 (Maize) plants, 25 and 45 years ago. Soil carbon was separated into one fast-degrading particulate organic matter fraction (POM) and one slow-degrading organo-mineral fraction (OMF). The structure of the soil microbial community were investigated using phospholipid fatty acids (PLFA), and turnover of single PLFAs was calculated from the changes in their 13C content. Soil enzyme activities involved in the degradation of carbohydrates was determined using fluorogenic MUF (methyl-umbelliferryl phosphate) substrates. We found that fresh organic matter input drives soil organic matter dynamic. Higher annual input of fresh organic matter resulted in a higher amount of fungal biomass in the POM-fraction and shorter mean residence times. Fungal activity therefore seems essential for the decomposition and incorporation of organic matter input into the soil. As a consequence, limited litter input changed especially the fungal community favouring arbuscular mycorrhizal fungi. Altogether, supply and availability of fresh plant carbon changed the distribution of microbial biomass, the microbial community structure and enzyme activities and resulted in different priming of soil organic matter. Most interestingly we found that only at low input the OMF fraction had significantly higher calculated MRT for Gram-positive and Gram-negative bacteria suggesting high recycling of soil carbon or the use of other carbon sources. But on average all microbial groups had nearly similar carbon uptake rates in all fractions and both soils, which contrasted the turnover times of bulk carbon. Hereby the microbial carbon turnover was always faster than the soil organic carbon turnover and higher carbon input

Cycling of organic carbon in the ocean: use of naturally occuring radiocarbon as a long and short term tracer

International Nuclear Information System (INIS)

Williams, P.M.; Linick, T.W.

1975-01-01

The natural radiocarbon activities of surface, bathypelagic and benthic marine organisms have been measured for samples collected from the north central, north eastern and central equatorial Pacific Ocean and from the Ross Sea in Antarctica. These measurements show that 1961-1962 bomb-carbon-14 has been incorporated into the bathypelagic specimens in varying amounts. Thus, pollutants introduced into surface waters of the oceans may be removed more or less rapidly from the euphotic zone into the deep water depending upon particular food chain mechanisms. These results are discussed in relation to the cycling of disolved organic carbon, the flux of particulate organic carbon through the seawater column into the sediments, and to the oxidation rates of organic matter in the deep sea. (author)

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...

Emissions factors for gaseous and particulate pollutants from offshore diesel engine vessels in China

Science.gov (United States)

Zhang, F.; Chen, Y.; Tian, C.; Li, J.; Zhang, G.; Matthias, V.

2015-09-01

Shipping emissions have significant influence on atmospheric environment as well as human health, especially in coastal areas and the harbor districts. However, the contribution of shipping emissions on the environment in China still need to be clarified especially based on measurement data, with the large number ownership of vessels and the rapid developments of ports, international trade and shipbuilding industry. Pollutants in the gaseous phase (carbon monoxide, sulfur dioxide, nitrogen oxides, total volatile organic compounds) and particle phase (particulate matter, organic carbon, elemental carbon, sulfates, nitrate, ammonia, metals) in the exhaust from three different diesel engine power offshore vessels in China were measured in this study. Concentrations, fuel-based and power-based emissions factors for various operating modes as well as the impact of engine speed on emissions were determined. Observed concentrations and emissions factors for carbon monoxide, nitrogen oxides, total volatile organic compounds, and particulate matter were higher for the low engine power vessel than for the two higher engine power vessels. Fuel-based average emissions factors for all pollutants except sulfur dioxide in the low engine power engineering vessel were significantly higher than that of the previous studies, while for the two higher engine power vessels, the fuel-based average emissions factors for all pollutants were comparable to the results of the previous studies. The fuel-based average emissions factor for nitrogen oxides for the small engine power vessel was more than twice the International Maritime Organization standard, while those for the other two vessels were below the standard. Emissions factors for all three vessels were significantly different during different operating modes. Organic carbon and elemental carbon were the main components of particulate matter, while water-soluble ions and elements were present in trace amounts. Best-fit engine speeds

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

Importance of kelp-derived organic carbon to the scallop Chlamys farreri in an integrated multi-trophic aquaculture system

Science.gov (United States)

Xu, Qiang; Gao, Fei; Yang, Hongsheng

2016-03-01

Bivalves and seaweeds are important cleaners that are widely used in integrated multi-trophic aquaculture (IMTA) systems. A beneficial relationship between seaweed and bivalve in the seaweed-based IMTA system has been confirmed, but the trophic importance of seaweed-derived particulate organic materials to the co-cultured bivalve is still unclear. We evaluated the trophic importance of the kelp Saccharina japonica to the co-cultured scallop Chlamys farreri in a typical IMTA farm in Sungo Bay (Weihai, North China). The dynamics of detritus carbon in the water were monitored during the culturing period. The proportion of kelp-derived organic matter in the diet of the co-cultured scallop was assessed via the stable carbon isotope method. Results showed that the detritus carbon in the water ranged from 75.52 to 265.19 μg/L, which was 25.6% to 73.8% of total particulate organic carbon (TPOC) during the study period. The amount of detritus carbon and its proportion in the TPOC changed throughout the culture cycle of the kelp. Stable carbon isotope analysis showed that the cultured scallop obtained 14.1% to 42.8% of its tissue carbon from the kelp, and that the percentages were closely correlated with the proportion of detritus carbon in the water ( F =0.993, P= 0.003). Evaluation showed that for 17 000 tons (wet weight) of annual scallop production, the kelp contributed about 139.3 tons of carbon (535.8 tons of dry mass). This confirms that cultured kelp plays a similar trophic role in IMTA systems as it does in a natural kelp bed. It is a major contributor to the detritus pool and supplies a vital food source to filter-feeding scallops in the IMTA system, especially during winter and early spring when phytoplankton are scarce.

Organic carbon accumulation and reactivity in central Swedish lakes during the Holocene

Science.gov (United States)

Chmiel, H.; Kokic, J.; Niggemann, J.; Dittmar, T.; Sobek, S.

2012-04-01

Sedimentation and burial of particulate organic carbon (POC), received from terrestrial sources and from lake internal primary production, are responsible for the progressive accumulation and long-term storage of organic matter in lake basins. For lakes in the boreal zone of central Sweden it can be presumed, that the onset of POC accumulation occurred during the early Holocene (˜8000 BP.) after the retreat of the Scandinavian ice sheet. In this study we investigated carbon mass accumulation rates (CMARs), as well as sources and reactivity of deposited organic material, for seven lakes in central Sweden (60°N, 15°E), in order to obtain a detailed temporal resolution of carbon burial and preservation in boreal lakes. Sediment long-cores were sampled in March 2011 from the ice, and CMARs were calculated from water contents, dry bulk densities, carbon contents and radiocarbon (14C) ages of the depth profiles. To indicate the sources of the organic material and characterize its diagenetic state, we determined carbon-nitrogen ratios (C/N) as well as amounts and compositions of lignin phenols. The transitions from organic rich sediment layers to glacial till deposits were found to be in sediment depths of ˜3 m in each lake. POC contents were on average highest (25-34 wt. % C), in small lakes (≤ 0.07 km2) and lowest (10-18 wt. % C) in the larger lakes (≥ 165 km2). The CMARs over the Holocene showed significant variations and were on average lower in the early Holocene, compared to recent accumulation rates. C/N values and the composition of lignin phenols further provided indications of important changes in organic matter source and reactivity over the Holocene. In summary, our data suggest that boreal lake sediments were a significantly stronger sink for organic carbon during the last ~150 years than during earlier periods of the Holocene.

Cellulase activity and dissolved organic carbon release from lignocellulose macrophyte-derived in four trophic conditions

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Flávia Bottino

2016-06-01

Full Text Available Abstract Considering the importance of lignocellulose macrophyte-derived for the energy flux in aquatic ecosystems and the nutrient concentrations as a function of force which influences the decomposition process, this study aims to relate the enzymatic activity and lignocellulose hydrolysis in different trophic statuses. Water samples and two macrophyte species were collected from the littoral zone of a subtropical Brazilian Reservoir. A lignocellulosic matrix was obtained using aqueous extraction of dried plant material (≈40 °C. Incubations for decomposition of the lignocellulosic matrix were prepared using lignocelluloses, inoculums and filtered water simulating different trophic statuses with the same N:P ratio. The particulate organic carbon and dissolved organic carbon (POC and DOC, respectively were quantified, the cellulase enzymatic activity was measured by releasing reducing sugars and immobilized carbon was analyzed by filtration. During the cellulose degradation indicated by the cellulase activity, the dissolved organic carbon daily rate and enzyme activity increased. It was related to a fast hydrolysable fraction of cellulose that contributed to short-term carbon immobilization (ca. 10 days. After approximately 20 days, the dissolved organic carbon and enzyme activity were inversely correlated suggesting that the respiration of microorganisms was responsible for carbon mineralization. Cellulose was an important resource in low nutrient conditions (oligotrophic. However, the detritus quality played a major role in the lignocelluloses degradation (i.e., enzyme activity and carbon release.

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)

Stable isotopes of bulk organic matter to trace carbon and nitrogen dynamics in an estuarine ecosystem in Babitonga Bay (Santa Catarina, Brazil)

International Nuclear Information System (INIS)

Barros, Grace Virginia; Martinelli, Luiz Antonio; Oliveira Novais, Therezinha M.; Ometto, Jean Pierre H.B.; Zuppi, Gian Maria

2010-01-01

The biogeochemical processes affecting the transport and cycling of terrestrial organic carbon in coastal and transition areas are still not fully understood. One means of distinguishing between the sources of organic materials contributing to particulate organic matter (POM) in Babitonga Bay waters and sediments is by the direct measurement of δ 13 C of dissolved inorganic carbon (DIC) and δ 13 C and δ 15 N in the organic constituents. An isotopic survey was taken from samples collected in the Bay in late spring of 2004. The results indicate that the δ 13 C and δ 15 N compositions of OM varied from - 21.7 per mille to - 26.2 per mille and from + 9.2 per mille to - 0.1 per mille , respectively. δ 13 C from DIC ranges from + 0.04 per mille to - 12.7 per mille . The difference in the isotope compositions enables the determination of three distinct end-members: terrestrial, marine and urban. Moreover, the evaluation of source contribution to the particulate organic matter (POM) in the Bay, enables assessment of the anthropogenic impact. Comparing the depleted values of δ 13 C DIC and δ 13 C POC it is possible to further understand the carbon dynamic within Babitonga Bay.

Ancient low-molecular-weight organic acids in permafrost fuel rapid carbon dioxide production upon thaw.

Science.gov (United States)

Drake, Travis W; Wickland, Kimberly P; Spencer, Robert G M; McKnight, Diane M; Striegl, Robert G

2015-11-10

Northern permafrost soils store a vast reservoir of carbon, nearly twice that of the present atmosphere. Current and projected climate warming threatens widespread thaw of these frozen, organic carbon (OC)-rich soils. Upon thaw, mobilized permafrost OC in dissolved and particulate forms can enter streams and rivers, which are important processors of OC and conduits for carbon dioxide (CO2) to the atmosphere. Here, we demonstrate that ancient dissolved organic carbon (DOC) leached from 35,800 y B.P. permafrost soils is rapidly mineralized to CO2. During 200-h experiments in a novel high-temporal-resolution bioreactor, DOC concentration decreased by an average of 53%, fueling a more than sevenfold increase in dissolved inorganic carbon (DIC) concentration. Eighty-seven percent of the DOC loss to microbial uptake was derived from the low-molecular-weight (LMW) organic acids acetate and butyrate. To our knowledge, our study is the first to directly quantify high CO2 production rates from permafrost-derived LMW DOC mineralization. The observed DOC loss rates are among the highest reported for permafrost carbon and demonstrate the potential importance of LMW DOC in driving the rapid metabolism of Pleistocene-age permafrost carbon upon thaw and the outgassing of CO2 to the atmosphere by soils and nearby inland waters.

Ancient low–molecular-weight organic acids in permafrost fuel rapid carbon dioxide production upon thaw

Science.gov (United States)

Drake, Travis W.; Wickland, Kimberly P.; Spencer, Robert G. M.; McKnight, Diane M.; Striegl, Robert G.

2015-01-01

Northern permafrost soils store a vast reservoir of carbon, nearly twice that of the present atmosphere. Current and projected climate warming threatens widespread thaw of these frozen, organic carbon (OC)-rich soils. Upon thaw, mobilized permafrost OC in dissolved and particulate forms can enter streams and rivers, which are important processors of OC and conduits for carbon dioxide (CO2) to the atmosphere. Here, we demonstrate that ancient dissolved organic carbon (DOC) leached from 35,800 y B.P. permafrost soils is rapidly mineralized to CO2. During 200-h experiments in a novel high–temporal-resolution bioreactor, DOC concentration decreased by an average of 53%, fueling a more than sevenfold increase in dissolved inorganic carbon (DIC) concentration. Eighty-seven percent of the DOC loss to microbial uptake was derived from the low–molecular-weight (LMW) organic acids acetate and butyrate. To our knowledge, our study is the first to directly quantify high CO2 production rates from permafrost-derived LMW DOC mineralization. The observed DOC loss rates are among the highest reported for permafrost carbon and demonstrate the potential importance of LMW DOC in driving the rapid metabolism of Pleistocene-age permafrost carbon upon thaw and the outgassing of CO2 to the atmosphere by soils and nearby inland waters.

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

Cellulase activity and dissolved organic carbon release from lignocellulose macrophyte-derived in four trophic conditions.

Science.gov (United States)

Bottino, Flávia; Cunha-Santino, Marcela Bianchessi; Bianchini, Irineu

2016-01-01

Considering the importance of lignocellulose macrophyte-derived for the energy flux in aquatic ecosystems and the nutrient concentrations as a function of force which influences the decomposition process, this study aims to relate the enzymatic activity and lignocellulose hydrolysis in different trophic statuses. Water samples and two macrophyte species were collected from the littoral zone of a subtropical Brazilian Reservoir. A lignocellulosic matrix was obtained using aqueous extraction of dried plant material (≈40°C). Incubations for decomposition of the lignocellulosic matrix were prepared using lignocelluloses, inoculums and filtered water simulating different trophic statuses with the same N:P ratio. The particulate organic carbon and dissolved organic carbon (POC and DOC, respectively) were quantified, the cellulase enzymatic activity was measured by releasing reducing sugars and immobilized carbon was analyzed by filtration. During the cellulose degradation indicated by the cellulase activity, the dissolved organic carbon daily rate and enzyme activity increased. It was related to a fast hydrolysable fraction of cellulose that contributed to short-term carbon immobilization (ca. 10 days). After approximately 20 days, the dissolved organic carbon and enzyme activity were inversely correlated suggesting that the respiration of microorganisms was responsible for carbon mineralization. Cellulose was an important resource in low nutrient conditions (oligotrophic). However, the detritus quality played a major role in the lignocelluloses degradation (i.e., enzyme activity) and carbon release. Copyright © 2016 Sociedade Brasileira de Microbiologia. Published by Elsevier Editora Ltda. All rights reserved.

SOIL ORGANIC CARBON FRACTIONS AS INFLUENCED BY SOYBEAN CROPPING IN THE HUMID PAMPA OF ARGENTINA

Directory of Open Access Journals (Sweden)

Marta E. Conti

2014-07-01

Full Text Available The sustainability of continuous cropping systems depends heavily on the years of intensive agricultural production and the choice of crop sequence that alters the fractions of soil organic matter. The aim of this study was to evaluate the impact of continuous soybean cultivation on fractions of organic carbon in the vertic Argiudolls of the Argentinean Pampas. Total organic carbon (TOC, particulate organic carbon (POC , fulvic acids (FA, humic acids (HA, humin (H and carbon produced by microbial respiration (Cresp were assessed in plots with continuous production of soybean for over 15 years (SP and grassland plots that were considered the change control (GP. A significant reduction of TOC and POC variables in cultured soybean SP plots, relative to grassland GP, was observed. The POC / TOC and Cresp / TOC ratios were significantly lower in soybean plots than in grasslands used as controls. These ratios were interpreted as a preferential tendency to maintain high rates of mineralization of labile carbon forms and increased biological stability of humified forms in cultured soybean plots. The shapes of the humic fractions of less complexity, FA and HA, were significantly reduced in the latter plots compared with grasslands, while no significant changes occurred in the more stable and recalcitrant forms of carbon, such as humin, in either plot type.

PBDE and PCB accumulation in benthos near marine wastewater outfalls: The role of sediment organic carbon

International Nuclear Information System (INIS)

Dinn, Pamela M.; Johannessen, Sophia C.; Ross, Peter S.; Macdonald, Robie W.; Whiticar, Michael J.; Lowe, Christopher J.; Roodselaar, Albert van

2012-01-01

Polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs) were measured in sediments and benthic invertebrates near submarine municipal outfalls in Victoria and Vancouver, B.C., Canada, two areas with contrasting receiving environments. PBDE concentrations in wastewater exceeded those of the legacy PCBs by eight times at Vancouver and 35 times at Victoria. Total PBDE concentrations in benthic invertebrates were higher near Vancouver than Victoria, despite lower concentrations in sediments, and correlated with organic carbon-normalized concentrations in sediment. Principal Components Analysis indicated uptake of individual PBDE congeners was determined by sediment properties (organic carbon, grain size), while PCB congener uptake was governed by physico-chemical properties (octanol-water partitioning coefficient). Results suggest the utility of sediment quality guidelines for PBDEs and likely PCBs benefit if based on organic carbon-normalized concentrations. Also, where enhanced wastewater treatment increases the PBDEs to particulate organic carbon ratio in effluent, nearfield benthic invertebrates may face increased PBDE accumulation. - Highlights: ► Physical receiving environment affects PBDE bioaccumulation by benthic invertebrates. ► PBDE uptake is correlated with organic-carbon normalized sediment concentrations. ► PBDE and PCB congener uptake are governed by different properties. ► PBDE sediment quality guidelines may benefit by using organic carbon-normalized data. ► Enhanced wastewater treatment may mean increased benthic invertebrate PBDE bioaccumulation. - The physical receiving environment affects the accumulation of PBDEs by benthic invertebrates near submarine municipal outfalls, and uptake of PBDE congeners is governed by different properties than for PCB congeners.

Evidence for the assimilation of ancient glacier organic carbon in a proglacial stream food web

Science.gov (United States)

Fellman, Jason; Hood, Eran; Raymond, Peter A.; Hudson, J.H.; Bozeman, Maura; Arimitsu, Mayumi L.

2015-01-01

We used natural abundance δ13C, δ15N, and Δ14C to compare trophic linkages between potential carbon sources (leaf litter, epilithic biofilm, and particulate organic matter) and consumers (aquatic macroinvertebrates and fish) in a nonglacial stream and two reaches of the heavily glaciated Herbert River. We tested the hypothesis that proglacial stream food webs are sustained by organic carbon released from glacial ecosystems. Carbon sources and consumers in the nonglacial stream had carbon isotope values that ranged from -30‰ to -25‰ for δ13C and from -14‰ to 53‰ for Δ14C reflecting a food web sustained mainly on contemporary primary production. In contrast, biofilm in the two glacial stream sites was highly Δ14C-depleted (-215‰ to 175‰) relative to the nonglacial stream consistent with the assimilation of ancient glacier organic carbon. IsoSource modeling showed that in upper Herbert River, macroinvertebrates (Δ14C = -171‰ to 22‰) and juvenile salmonids (Δ14C = −102‰ to 17‰) reflected a feeding history of both biofilm (~ 56%) and leaf litter (~ 40%). We estimate that in upper Herbert River on average 36% of the carbon incorporated into consumer biomass is derived from the glacier ecosystem. Thus, 14C-depleted glacial organic carbon was likely transferred to higher trophic levels through a feeding history of bacterial uptake of dissolved organic carbon and subsequent consumption of 14C-depleted biofilm by invertebrates and ultimately fish. Our findings show that the metazoan food web is sustained in part by glacial organic carbon such that future changes in glacial runoff could influence the stability and trophic structure of proglacial aquatic ecosystems.

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

长江口外海域沉积物中有机物的来源及分布%Spatial distributions of organic carbon and nitrogen and their isotopic compositions in sediments of the Changjiang Estuary and its adjacent sea area

Institute of Scientific and Technical Information of China (English)

高建华; 汪亚平; 潘少明; 张瑞; 李军; 白风龙

2008-01-01

The spatial distribution patterns of total organic carbon and total nitrogen show significant correlations with currents of the East China Sea Shelf. Corresponding to distributions of these currents, the study area could be divided into four different parts. Total organic carbon, total nitrogen, and organic carbon and nitrogen stable isotopes in sediments show linear correlations with mean grain size, respectively, thus "grain size effect" is an important factor that influences their distributions. C/N ratios can reflect source information of organic matter to a certain degree. In contrast, nitrogen stable isotope shows different spatial distribution patterns with C/N and organic carbon stable isotope, according to their relationships and regional distributions. The highest contribution (up to 50%) of terrestrial organic carbon appears near the Changjiang Estuary with isolines projecting towards northeast, indicating the influence of the Changjiang dilution water. Terrestrial particulate organic matter suffers from effects of diagenesis, benthos and incessant inputting of dead organic matter of plankton,after depositing in seabed. Therefore, the contribution of terrestrial organic carbon to particulate organic matter is obviously greater than that to organic matter in sediments in the same place.

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...

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

Air pollution studies in terms of particulate matters, elements and black carbon in the aerosols collected at Andravoahangy-Antananarivo

International Nuclear Information System (INIS)

HARINOELY, M.

2012-01-01

This work was performed at the Institut National des Sciences et Techniques Nucleaires (Madagascar-INSTN) in the framework of RAF/4/019 project organized by the International Atomic Energy Agency. The main objective of this work is to study the level of air pollution in terms of particulate matters, elements and black carbon in the site of Andravoahangy-Antananarivo and to transmit the results obtained to the competent authorities so that they can make decisions to reduce the impacts of air pollution on the population. The total reflection X-ray fluorescence spectrometer is used for qualitative and quantitative analyses of the elements contained in the aerosols and the reflectometer M43D for the determination of the black carbon concentrations. The results showed that the average concentrations of the particulate matters PM 2,5-10 are higher than those of PM 2,5 . The average concentrations of PM 10 in the aerosols are exceeding the World Health Organisation (WHO) and European Union guidelines, set at 50 μg.m -3 and those of PM 2,5 are higher than the 2005 WHO (25 μg.m -3 ) and the United States Environmental Protection Agency (35 μg.m -3 ) guidelines. The identified elements in the aerosols are Ti, Cr, Mn, Fe, Ni, Cu, Zn, Br, Sr and Pb. The average concentrations of these elements are also higher in the coarse particles than in the fine particles. The concentrations of black carbon are higher in the fine particles, with a maximum value of 9.12 μg.m -3 . [fr

[Responses of accumulation-loss patterns for soil organic carbon and its fractions to tillage and water erosion in black soil area].

Science.gov (United States)

Zhao, Peng Zhi; Chen, Xiang Wei; Wang, En Heng

2017-11-01

Tillage and water erosion have been recognized as the main factors causing degradation in soil organic carbon (SOC) pools of black soil. To further explore the response of SOC and its fractions to different driving forces of erosion (tillage and water), geostatistical methods were used to analyze spatial patterns of SOC and its three fractions at a typical sloping farmland based on tillage and water erosion rates calculated by local models. The results showed that tillage erosion and deposition rates changed according to the slope positions, decreasing in the order: upper-slope > lower-slope > middle-slope > toe-slope and toe-slope > lower-slope > middle-slope > upper-slope, respectively; while the order of water erosion rates decreased in the order: lower-slope > toe-slope > middle-slope > upper-slope. Tillage and water erosion cooperatively triggered intense soil loss in the lower-slope areas with steep slope gradient. Tillage erosion could affect C cycling through the whole slope at different levels, although the rate of tillage erosion (0.02-7.02 t·hm -2 ·a -1 ) was far less than that of water erosion (5.96-101.17 t·hm -2 ·a -1 ) in black soil area. However, water erosion only played a major role in controlling C dynamics in the runoff-concentrated lower slope area. Affected by water erosion and tillage erosion-deposition disturbance, the concentrations of SOC, particulate organic carbon and dissolved organic carbon in depositional areas were higher than in erosional areas, however, microbial biomass carbon showed an opposite trend. Tillage erosion dominated SOC dynamic by depleting particulate organic carbon.

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

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.

Fluvial organic carbon losses from oil palm plantations on tropical peat, Sarawak, Southeast Asia

Science.gov (United States)

Cook, Sarah; Page, Susan; Evans, Chris; Whelan, Mick; Gauci, Vincent; Lip Khoon, Kho

2017-04-01

Tropical peatlands are valuable stores of carbon. However, tropical peat swamp forests (TPSFs) in Southeast Asia have increasingly been converted to other land-uses. For example, more than 25% of TPSFs are now under oil palm plantations. This conversion - requiring felling and burning of trees and drainage of the peat - can enhance carbon mineralization, dissolved organic carbon (DOC) losses and can contribute significantly to global anthropogenic greenhouse gas emissions, changing these natural carbon sinks into carbon sources. At present, relatively few scientifically sound studies provide dependable estimates of gaseous and fluvial carbon losses from oil palm plantations or from drained tropical peat in general. Here we present an annual (54 week) estimate of the export of dissolved and particulate organic carbon in water draining two oil palm estates and nearby stands of TPSF in Sarawak, Malaysia, subjected to varying degrees of past anthropogenic disturbance. Spectrophotometric techniques including SUVA254 (Specific Ultra-Violet Absorption) were used to gain insight into the aromaticity and subsequent bioavailability of the exported DOC. Water draining plantation and deforested land had a higher proportion of labile carbon compared to water draining forested areas. Preliminary data suggest a total fluvial DOC flux from plantations of ca. 190 g C m-2 year-1; nearly three times estimates from intact TPSFs (63 g C m-2 year-1). DOC accounted for between 86 % - 94 % of the total organic carbon lost (most of which was bioavailable). Wit et al. (2015) estimates that an average of 53 % of peat-derived DOC is decomposed and emitted as CO2, on a monthly basis. Based on these estimates our data suggests an additional 101 g CO2 m-2 may be emitted indirectly from fluvial organic carbon in degraded TPSFs per year. Overall, these findings emphasize the importance of including fluvial organic carbon fluxes when quantifying the impact of anthropogenic disturbance on the

Mapping soil organic carbon content and composition across Australia to assess vulnerability to climate change

Science.gov (United States)

Viscarra Rossel, R. A.

2015-12-01

We can effectively monitor soil condition—and develop sound policies to offset the emissions of greenhouse gases—only with accurate data from which to define baselines. Currently, estimates of soil organic C for countries or continents are either unavailable or largely uncertain because they are derived from sparse data, with large gaps over many areas of the Earth. Here, we derive spatially explicit estimates, and their uncertainty, of the distribution and stock of organic C content and composition in the soil of Australia. The composition of soil organic C may be characterized by chemical separation or physical fractionation based on either particle size or particle density (Skjemstad et al., 2004; Gregorich et al., 2006; Kelleher&Simpson, 2006; Zimmermann et al., 2007). In Australia, for example, Skjemstad et al. (2004) used physical separation of soil samples into 50-2000 and solid-state 13C nuclear magnetic resonance (NMR) spectroscopy, giving the three OC pools, particulate organic carbon (POC), humic organic carbon (HOC) and resistant organic carbon (ROC; charcoal or char-carbon). We assembled and harmonized data from several sources to produce the most comprehensive set of data on the current stock of organic C in soil of the continent. Using them, we have produced a fine spatial resolution baseline map of organic C, POC, HOC and ROC at the continental scale. In this presentation I will describe how we made the maps and how we use them to assess the vulnerability of soil organic C to for instance climate change.

Distinguishing Terrestrial Organic Carbon in Marginal Sediments of East China Sea and Northern South China Sea

Science.gov (United States)

Kandasamy, Selvaraj; Lin, Baozhi; Wang, Huawei; Liu, Qianqian; Liu, Zhifei; Lou, Jiann-Yuh; Chen, Chen-Tung Arthur; Mayer, Lawrence M.

2016-04-01

Knowledge about the sources, transport pathways and behavior of terrestrial organic carbon in continental margins adjoining to large rivers has improved in recent decades, but uncertainties and complications still exist with human-influenced coastal regions in densely populated wet tropics and subtropics. In these regions, the monsoon and other episodic weather events exert strong climatic control on mineral and particulate organic matter delivery to the marginal seas. Here we investigate elemental (TOC, TN and bromine-Br) and stable carbon isotopic (δ13C) compositions of organic matter (OM) in surface sediments and short cores collected from active (SW Taiwan) and passive margin (East China Sea) settings to understand the sources of OM that buried in these settings. We used sedimentary bromine to total organic carbon (Br/TOC) ratios to apportion terrigenous from marine organic matter, and find that Br/TOC may serve as an additional, reliable proxy for sedimentary provenance in both settings. Variations in Br/TOC are consistent with other provenance indicators in responding to short-lived terrigenous inputs. Because diagenetic alteration of Br is insignificant on shorter time scales, applying Br/TOC ratios as a proxy to identify organic matter source along with carbon isotope mixing models may provide additional constraints on the quantity and transformation of terrigenous organics in continental margins. We apply this combination of approaches to land-derived organic matter in different depositional environments of East Asian marginal seas.

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.

Elemental and organic carbon in aerosols over urbanized coastal region (southern Baltic Sea, Gdynia).

Science.gov (United States)

Lewandowska, Anita; Falkowska, Lucyna; Murawiec, Dominika; Pryputniewicz, Dorota; Burska, Dorota; Bełdowska, Magdalena

2010-09-15

Studies on PM 10, total particulate matter (TSP), elemental carbon (EC) and organic carbon (OC) concentrations were carried out in the Polish coastal zone of the Baltic Sea, in urbanized Gdynia. The interaction between the land, the air and the sea was clearly observed. The highest concentrations of PM 10, TSP and both carbon fractions were noted in the air masses moving from southern and western Poland and Europe. The EC was generally of primary origin and its contribution to TSP and PM 10 mass was on average 2.3% and 3.7% respectively. Under low wind speed conditions local sources (traffic and industry) influenced increases in elemental carbon and PM 10 concentrations in Gdynia. Elemental carbon demonstrated a pronounced weekly cycle, yielding minimum values at the weekend and maximum values on Thursdays. The role of harbors and ship yards in creating high EC concentrations was clearly observed. Concentration of organic carbon was ten times higher than that of elemental carbon, and the average OC contribution to PM 10 mass was very high (31.6%). An inverse situation was observed when air masses were transported from over the Atlantic Ocean, the North Sea and the Baltic Sea. These clean air masses were characterized by the lowest concentrations of all analysed compounds. Obtained results for organic and elemental carbon fluxes showed that atmospheric aerosols can be treated, along with water run-off, as a carbon source for the coastal waters of the Baltic Sea. The enrichment of surface water was more effective in the case of organic carbon (0.27+/-0.19 mmol m(-2) d(-1)). Elemental carbon fluxes were one order of magnitude smaller, on average 0.03+/-0.04 mmol m(-2) d(-1). We suggest that in some situations atmospheric carbon input can explain up to 18% of total carbon fluxes into the Baltic coastal waters. Copyright 2010 Elsevier B.V. All rights reserved.

Changes in physical properties and organic carbon of a Kandiudox fertilized with manure

Directory of Open Access Journals (Sweden)

Andréia Patricia Andrade

2016-05-01

Full Text Available ABSTRACT: Successive applications of pig slurry and poultry manure can improve the soil structure, according to the land use conditions and amounts applied. This study evaluated the effect of manure fertilization on the physical properties and organic carbon of a Rhodic Kandiudox. Treatments included land use and management and time of pig slurry and poultry litter application, namely: native forest (NF; yerba mate after 20 years of animal waste application (YM20; pasture after 15 years of application (P15; grassland after 20 years of manuring (PP20; grassland after 3 years of manuring (P3; pasture without application (P0, maize after 20 years of application (M20; and maize after 7 years of application (M7. Soil samples were collected in the 0-5, 5-10 and 10-20cm layers, in which density, porosity, aggregate stability, flocculation, penetration resistance, available water, and total clay content, total and particulate organic carbon, and C:N ratio were analyzed. The total organic carbon is sensitive to management and was not related to waste application, except in the 10-20cm layer of ryegrass pasture after three years of manuring. Reponses to waste application and land use and management systems were observed in the variables soil density and penetration resistance.

Iatroscan-measured particulate and dissolved lipids in the Almeria-Oran frontal system (Almofront-1, May 1991)

Science.gov (United States)

Gérin, C.; Goutx, M.

1994-08-01

The Chromarod-Iatroscan system was used to measure dissolved and particulate lipids at six sites representative of the main hydrological zones of the Almeria-Oran frontal system in May 1991. Concentrations ranged from 9 to 113 μg 1 -1 and from 3 to 84 μg 1 -1 respectively. Particulate carbon was estimated on a CHN Leco analyzer. Dissolved lipid concentrations were highly variable with depth and exhibited clear signatures of phytoplankton degradation throughout the profiles. In the 300-400 m layer, particulate wax esters denoted the presence of deep zooplankton which may be benefit from the downward fluxes of organic matter from the frontal zone. In surface water, high concentrations of dissolved lipids and particulate carbon marked the presence of the jet front. Particulate lipid classes in samples were related to the presence of zooplankton and to the physiological state of cells rather than to phytoplankton biomass. Particulate triglyceride concentrations (storage lipids in phytoplankton) increased from the left to the right border of the jet core and further southwards, culminating in the Atlantic anticyclonic gyre. The distribution of particulate lipids to carbon and chlorophyllatios and the increasing level of triglycerides from the jet and southwards suggested a rapid removal of the frontal production by physical transports. The ability of anticyclonic structures to enhance accumulations of energetically rich compounds and thus to play a role as fertilizers of the oligotrophic waters of the Mediterranean Sea is discussed.

Autonomous observations of the ocean biological carbon pump

Energy Technology Data Exchange (ETDEWEB)

Bishop, James K.B.

2009-03-01

Prediction of the substantial biologically mediated carbon flows in a rapidly changing and acidifying ocean requires model simulations informed by observations of key carbon cycle processes on the appropriate space and time scales. From 2000 to 2004, the National Oceanographic Partnership Program (NOPP) supported the development of the first low-cost fully-autonomous ocean profiling Carbon Explorers that demonstrated that year-round real-time observations of particulate organic carbon (POC) concentration and sedimentation could be achieved in the world's ocean. NOPP also initiated the development of a sensor for particulate inorganic carbon (PIC) suitable for operational deployment across all oceanographic platforms. As a result, PIC profile characterization that once required shipboard sample collection and shipboard or shore based laboratory analysis, is now possible to full ocean depth in real time using a 0.2W sensor operating at 24 Hz. NOPP developments further spawned US DOE support to develop the Carbon Flux Explorer, a free-vehicle capable of following hourly variations of particulate inorganic and organic carbon sedimentation from near surface to kilometer depths for seasons to years and capable of relaying contemporaneous observations via satellite. We have demonstrated the feasibility of real time - low cost carbon observations which are of fundamental value to carbon prediction and when further developed, will lead to a fully enhanced global carbon observatory capable of real time assessment of the ocean carbon sink, a needed constraint for assessment of carbon management policies on a global scale.

Soil organic carbon assessments in cropping systems using isotopic techniques

Science.gov (United States)

Martín De Dios Herrero, Juan; Cruz Colazo, Juan; Guzman, María Laura; Saenz, Claudio; Sager, Ricardo; Sakadevan, Karuppan

2016-04-01

Introduction of improved farming practices are important to address the challenges of agricultural production, food security, climate change and resource use efficiency. The integration of livestock with crops provides many benefits including: (1) resource conservation, (2) ecosystem services, (3) soil quality improvements, and (4) risk reduction through diversification of enterprises. Integrated crop livestock systems (ICLS) with the combination of no-tillage and pastures are useful practices to enhance soil organic carbon (SOC) compared with continuous cropping systems (CCS). In this study, the SOC and its fractions in two cropping systems namely (1) ICLS, and (2) CCS were evaluated in Southern Santa Fe Province in Argentina, and the use of delta carbon-13 technique and soil physical fractionation were evaluated to identify sources of SOC in these systems. Two farms inside the same soil cartographic unit and landscape position in the region were compared. The ICLS farm produces lucerne (Medicago sativa Merrill) and oat (Avena sativa L.) grazed by cattle alternatively with grain summer crops sequence of soybean (Glicine max L.) and corn (Zea mays L.), and the farm under continuous cropping system (CCS) produces soybean and corn in a continuous sequence. The soil in the area is predominantly a Typic Hapludoll. Soil samples from 0-5 and 0-20 cm depths (n=4) after the harvest of grain crops were collected in each system and analyzed for total organic carbon (SOC, 0-2000 μm), particulate organic carbon (POC, 50-100 μm) and mineral organic carbon (MOC, is probably due to the presence of deep roots under pastures in ICLS. Delta carbon-13 values for 0-5 cm were -22.9, -21.2 and -19.9 per mil for REF, ICLS and CCS, respectively (Pis explained by the presence of tree species with high lignin content in natural vegetation. Lignin has lower delta carbon-13 compared to cellulose (dominating in crops and pastures), which is present in greater proportion in plant residues of

Toward a quantitative and empirical dissolved organic carbon budget for the Gulf of Maine, a semienclosed shelf sea

Science.gov (United States)

Balch, William; Huntington, Thomas G.; Aiken, George R.; Drapeau, David; Bowler, Bruce; Lubelczyk, Laura; Butler, Kenna D.

2016-01-01

A time series of organic carbon export from Gulf of Maine (GoM) watersheds was compared to a time series of biological, chemical, bio-optical, and hydrographic properties, measured across the GoM between Yarmouth, NS, Canada, and Portland, ME, U.S. Optical proxies were used to quantify the dissolved organic carbon (DOC) and particulate organic carbon in the GoM. The Load Estimator regression model applied to river discharge data demonstrated that riverine DOC export (and its decadal variance) has increased over the last 80 years. Several extraordinarily wet years (2006–2010) resulted in a massive pulse of chromophoric dissolved organic matter (CDOM; proxy for DOC) into the western GoM along with unidentified optically scattering material (Time lags between DOC discharge and its appearance in the GoM increased with distance from the river mouths. Algae were also a significant source of DOC but not CDOM. Gulf-wide algal primary production has decreased. Increases in precipitation and DOC discharge to the GoM are predicted over the next century.

Substantial soil organic carbon retention along floodplains of mountain streams

Science.gov (United States)

Sutfin, Nicholas A.; Wohl, Ellen

2017-07-01

Small, snowmelt-dominated mountain streams have the potential to store substantial organic carbon in floodplain sediment because of high inputs of particulate organic matter, relatively lower temperatures compared with lowland regions, and potential for increased moisture conditions. This work (i) quantifies mean soil organic carbon (OC) content along 24 study reaches in the Colorado Rocky Mountains using 660 soil samples, (ii) identifies potential controls of OC content based on soil properties and spatial position with respect to the channel, and (iii) and examines soil properties and OC across various floodplain geomorphic features in the study area. Stepwise multiple linear regression (adjusted r2 = 0.48, p sample depth, percent sand, distance from the channel, and relative elevation from the channel are significant predictors of OC content in the study area. Principle component analysis indicates limited separation between geomorphic floodplain features based on predictors of OC content. A lack of significant differences among floodplain features suggests that the systematic random sampling employed in this study can capture the variability of OC across floodplains in the study area. Mean floodplain OC (6.3 ± 0.3%) is more variable but on average greater than values in uplands (1.5 ± 0.08% to 2.2 ± 0.14%) of the Colorado Front Range and higher than published values from floodplains in other regions, particularly those of larger rivers.

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

Organic matter in central California radiation fogs.

Science.gov (United States)

Herckes, Pierre; Lee, Taehyoung; Trenary, Laurie; Kang, Gongunn; Chang, Hui; Collett, Jeffrey L

2002-11-15

Organic matter was studied in radiation fogs in the San Joaquin Valley of California during the California Regional Particulate Air Quality Study (CRPAQS). Total organic carbon (TOC) concentrations ranged from 2 to 40 ppm of C. While most organic carbon was found in solution as dissolved organic carbon (DOC), 23% on average was not dissolved inside the fog drops. We observe a clear variation of organic matter concentration with droplet size. TOC concentrations in small fog drops (fogwater, consistent with the enrichment of the organic matter in smaller fog drops with lower terminal settling velocities.

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....

Seasonal distribution of organic matter in mangrove environment of Goa

Digital Repository Service at National Institute of Oceanography (India)

Jagtap, T.G.

Water and sediments were studied for the distribution of suspended matter, organic carbon and nitrogen Suspended matter ranged from 3-373 mg.l-1 while particulate organic carbon (POC) from 0.03-9.94 mg.l-1 POC value showed significant correlation...

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.

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.

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

Dynamics regulating major trends in Barents Sea temperatures and subsequent effect on remotely sensed particulate inorganic carbon

DEFF Research Database (Denmark)

Hovland, Erlend Kjeldsberg; Dierssen, Heidi M.; Ferreira, Ana Sofia

2013-01-01

A more comprehensive understanding of how ocean temperatures influence coccolithophorid production of particulate inorganic carbon (PIC) will make it easier to constrain the effect of ocean acidification in the future. We studied the effect of temperature on Emiliania huxleyi PIC production...

Ambient Air Pollution and Increases in Blood Pressure: Role for biological constituents of particulate matter

Science.gov (United States)

Particulate matter (PM) is a complex mixture of extremely small particles and liquid droplets made up of a number of components including elemental carbon, organic chemicals, metals, acids (such as nitrates and sulfates), and soil and dust particles. Epidemiological studies con...

Carbon dioxide, climate and the deep ocean circulation: Carbon chemistry model

International Nuclear Information System (INIS)

Menawat, A.S.

1992-01-01

The objective of this study was to investigate the role of oceanic carbon chemistry in modulating the atmospheric levels of CO 2 . It is well known that the oceans are the primary sink of the excess carbon pumped into the atmosphere since the beginning of the industrial period. The suspended particulate and the dissolved organic matters in the deep ocean play important roles as carriers of carbon and other elements critical to the fate of CO 2 . In addition, the suspended particulate matter provides sites for oxidation-reduction reactions and microbial activities. The problem is of an intricate system with complex chemical, physical and biological processes. This report describes a methodology to describe the interconversions of different forms of the organic and inorganic nutrients, that may be incorporated in the ocean circulation models. Our approach includes the driving force behind the transfers in addition to balancing the elements. Such thermodynamic considerations of describing the imbalance in the chemical potentials is a new and unique feature of our approach

Toward Distinguishing Woodsmoke and Diesel Exhaust in Ambient Particulate Matter

International Nuclear Information System (INIS)

Braun, A.; Huggins, F.; Kubatova, A.; Wirick, S.; Maricq, M.; Mun, B.; McDonald, J.; Kelly, K.; Shah, N.; Huffman, G.

2008-01-01

Particulate matter (PM) from biomass burning and diesel exhaust has distinct X-ray spectroscopic, carbon specific signatures, which can be employed for source apportionment. Characterization of the functional groups of a wide selection of PM samples (woodsmoke, diesel soot, urban air PM) was carried out using the soft X-ray spectroscopy capabilities at the synchrotron radiation sources in Berkeley (ALS) and Brookhaven (NSLS). The spectra reveal that diesel exhaust particulate (DEP) matter is made up from a semigraphitic solid core and soluble organic matter, predominantly with carboxylic functional groups. Woodsmoke PM has no or a less prevalent, graphitic signature, instead it contains carbon-hydroxyl groups. Using these features to apportion the carbonaceous PM in ambient samples we estimate that the relative contribution of DEP to ambient PM in an urban area such as Lexington, KY and St. Louis, MO is 7% and 13.5%, respectively. These values are comparable to dispersion modeling data from nonurban and urban areas in California, and with elemental carbon measurements in urban locations such as Boston, MA, Rochester, NY, and Washington, DC.

Spatially explicit modeling of particulate nutrient flux in Large global rivers

Science.gov (United States)

Cohen, S.; Kettner, A.; Mayorga, E.; Harrison, J. A.

2017-12-01

Water, sediment, nutrient and carbon fluxes along river networks have undergone considerable alterations in response to anthropogenic and climatic changes, with significant consequences to infrastructure, agriculture, water security, ecology and geomorphology worldwide. However, in a global setting, these changes in fluvial fluxes and their spatial and temporal characteristics are poorly constrained, due to the limited availability of continuous and long-term observations. We present results from a new global-scale particulate modeling framework (WBMsedNEWS) that combines the Global NEWS watershed nutrient export model with the spatially distributed WBMsed water and sediment model. We compare the model predictions against multiple observational datasets. The results indicate that the model is able to accurately predict particulate nutrient (Nitrogen, Phosphorus and Organic Carbon) fluxes on an annual time scale. Analysis of intra-basin nutrient dynamics and fluxes to global oceans is presented.

Influence of Beaver-Induced Complexity on Storage of Organic Carbon and Sediment in Colorado Mountain Streams

Science.gov (United States)

Laurel, D.; Wohl, E.

2016-12-01

Beaver meadows (complexes of multiple different aged beaver dams and ponds) influence the storage of water, sediment, and nutrients. Although beaver meadows compose only a small fraction of catchment area, they provide a potentially large role in retaining these fluxes in mountain watersheds. Multiple dams and ponds in beaver meadows increase overbank flows leading to an anastomosing stream channel planform, and deposition of fine sediment along with particulate organic carbon. An earlier study estimated a range of cumulative carbon stored in 27 beaver meadows east of the continental divide in Rocky Mountain National Park. Storage ranged from 735,800 to 2.8 x 106 Mg carbon, with the high value estimating storage if all the meadows had active beaver (historic conditions pre-European settlement) and the lower value estimating current conditions where many of the meadows are abandoned. We combined geomorphic surveys, soil depth probing by rebar, and soil cores analyzed for carbon content to investigate the influence of beaver activity, meadow size, and meadow placement within the drainage on catchment-scale fluxes of fine sediment and organic carbon. We found carbon storage in floodplain soils to be highly variable across both active and abandoned meadows; however, active beaver meadows store more carbon on average than abandoned meadows. In addition, active meadows with high levels of beaver activity (multiple colonies) stored greater volumes of fine sediment behind dams and in ponds. These results have implications for the restoration potential of abandoned beaver meadows in mountain environments to store greater volumes of sediment and more organic carbon if beaver are successfully reintroduced.

The large variation in organic carbon consumption in spring in the East China Sea

Directory of Open Access Journals (Sweden)

C.-C. Chen

2013-05-01

Full Text Available A tremendous amount of organic carbon respired by plankton communities has been found in summer in the East China Sea (ECS, and this rate has been significantly correlated with fluvial discharge from the Changjiang River. However, respiration data has rarely been collected in other seasons. To evaluate and reveal the potential controlling mechanism of organic carbon consumption in spring in the ECS, two cruises covering almost the entire ECS shelf were conducted in the spring of 2009 and 2010. These results showed that although the fluvial discharge rates were comparable to the high riverine flow in summer, the plankton community respiration (CR varied widely between the two springs. In 2009, the level of CR was double that of 2010, with mean (± SD values of 111.7 (±76.3 and 50.7 (±62.9 mg C m−3 d−1, respectively. The CR was positively correlated with concentrations of particulate organic carbon and/or chlorophyll a (Chl a in 2009 (all p 2 (fCO2 in the surface waters, even with a significant amount of inorganic carbon regenerated via CR. In 2010, even more riverine runoff nutrients were measured in the ECS than in 2009. Surprisingly, the growth of phytoplankton in 2010 was not stimulated by enriched nutrients, and its growth was likely limited by low water temperature and/or low light intensity. Low temperature might also suppress planktonic metabolism, which could explain why the CR was lower in 2010. During this period, lower surface water fCO2 may have been driven mainly by physical process(es. To conclude, these results indicate that high organic carbon consumption (i.e. CR in the spring of 2009 could be attributed to high planktonic biomasses, and the lower CR rate during the cold spring of 2010 might be likely limited by low temperature in the ECS. This further suggests that the high inter-annual variability of organic carbon consumption needs to be kept in mind when budgeting the annual carbon balance.

Carbon dioxide emissions from Indian monsoonal estuaries

Digital Repository Service at National Institute of Oceanography (India)

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

estuaries. The mean pCO sub(2) and particulate organic carbon (POC) showed positive relation with rate of discharge suggesting availability of high quantities of organic matter that led to enhanced microbial decomposition. The annual CO sub(2) fluxes from...

Stable carbon isotope biogeochemistry of lakes along a trophic gradient

NARCIS (Netherlands)

de Kluijver, A.; Schoon, P.L.; Downing, J.A.; Schouten, S.; Middelburg, J.J.

2014-01-01

The stable carbon (C) isotope variability of dissolved inorganic and organic C (DIC and DOC), particulate organic carbon (POC), glucose and polar-lipid derived fatty acids (PLFAs) was studied in a survey of 22 North American oligotrophic to eutrophic lakes. The d13C of different PLFAs were used as

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

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.)

[Effect of straw-returning on the storage and distribution of different active fractions of soil organic carbon].

Science.gov (United States)

Wang, Hul; Wang, Xu-dong; Tian, Xiao-hong

2014-12-01

The impacts of straw mulching and returning on the storage of soil dissolved organic carbon (DOC), particulate organic carbon (POC) and mineral associated organic carbon (MOC), and their proportions to the total organic carbon (TOC) were studied based on a field experiment. The results showed that compared to the treatment of wheat straw soil-returning (WR), the storage of TOC and MOC decreased by 4.1% and 9.7% respectively in 0-20 cm soil in the treatment with wheat straw mulching (WM), but the storage of DOC and POC increased by 207.7% and 11.9%, and TOC and POC increased significantly in 20-40 cm soil. Compared to the treatment with maize straw soil-returning (MR), the storage of TOC and MOC in the plough pan soil of the treatment with maize straw mulching (MM) increased by 13.6% and 14.6% , respectively. Compared to the WR-MR treatment, the storage of TOC and MOC in top soil (0-20 icm) significantly decreased by 8.5% and 10.3% respectively in WM-MM treatment. The storage of TOC, and POC in top soil was significantly higher in the treatments with maize straw soil-returning or mulching than that with wheat straw. Compared to the treatment without straw (CK), the storage of TOC in top soil increased by 5.2% to 18.0% in the treatments with straw returning or mulching in the six modes (WM, WR, MM, MR, WM-MM,WR-MR) (Porganic carbon fraction in soil, straw soil-returning had the potential to accumulate stable organic carbon fraction. Considering organic carbon sequestration in cropland in the region of Guanzhong plain, maize straw mulching or soil-returning was better than wheat straw, and wheat straw and maize straw soil-returning (WR-MR) were better than wheat and maize straw mulching (WM-MM).

Experimental Evidence that Hemlock Mortality Enhances Carbon Stabilization in Southern Appalachian Forest Soils

Science.gov (United States)

Fraterrigo, J.; Ream, K.; Knoepp, J.

2017-12-01

Forest insects and pathogens (FIPs) can cause uncertain changes in forest carbon balance, potentially influencing global atmospheric carbon dioxide (CO2) concentrations. We quantified the effects of hemlock (Tsuga canadensis L. Carr.) mortality on soil carbon fluxes and pools for a decade following either girdling or natural infestation by hemlock woolly adelgid (HWA; Adelges tsugae) to improve mechanistic understanding of soil carbon cycling response to FIPs. Although soil respiration (Rsoil) was similar among reference plots and plots with hemlock mortality, both girdled and HWA-infested plots had greater activities of β-glucosidase, a cellulose-hydrolyzing extracellular enzyme, and decreased O-horizon mass and fine root biomass from 2005 to 2013. During this period, total mineral soil carbon accumulated at a higher rate in disturbed plots than in reference plots in both the surface (0-10 cm) and subsurface (10-30 cm); increases were predominantly in the mineral-associated fraction of the soil organic matter. In contrast, particulate organic matter carbon accrued slowly in surface soils and declined in the subsurface of girdled plots. δ13C values of this fraction demonstrate that particulate organic matter carbon in the surface soil has become more microbially processed over time, suggesting enhanced decomposition of organic matter in this pool. Together, these findings indicate that hemlock mortality and subsequent forest regrowth has led to enhanced soil carbon stabilization in southern Appalachian forests through the translocation of carbon from detritus and particulate soil organic matter pools to the mineral-associated organic matter pool. These findings have implications for ecosystem management and modeling, demonstrating that forests may tolerate moderate disturbance without diminishing soil carbon storage when there is a compensatory growth response by non-host trees.

Badlands and the Carbon cycle: a significant source of petrogenic organic carbon in rivers and marine environments?

Science.gov (United States)

Copard, Yoann; Eyrolle-Boyer, Frederique; Radakovitch, Olivier; Poirel, Alain; Raimbault, Patrick; Lebouteiller, Caroline; Gairoard, Stéphanie; Di-Giovanni, Christian

2016-04-01

A key issue in the study of carbon biogeochemical cycle is to well constrain each carbon origin in term of fluxes between all C-reservoirs. From continental surfaces to oceans, rivers convey particulate organic carbon originate from the biomass (biospheric OC) and /or from the sedimentary rocks (petrogenic OC). Existence and importance of this petrogenic OC export to oceans was debated for several decades (see Copard et al., 2007 and ref.), but it is now assumed that 20% of the global carbon export to ocean has a geological origin (Galy et al., 2015). The main current challenge is to constrain the major contributors to this petrogenic OC flux. Amongst the expected sedimentary sources of petrogenic OC in rivers, sedimentary rocks forming badlands can be rightly considered as some viable candidates. Indeed these rocks show a strong erosion rate, may exceed 50 kt km-2 y-1 and in addition, shales, marls and argillaceous rocks, frequently forming badlands (see Nadal-Romero et al., 2011 for the Mediterranean area), contain a significant amount of petrogenic OC (frequently over 0.50 wt. %, Ronov and Yaroshevsky 1976). Our work illustrates the contribution of badlands, mainly distributed within the Durance catchment (a main tributary of the Rhône river), in the petrogenic OC export to the Mediterranean Sea. The approach is based on (i) the use of previous and new data on radiogenic carbon, (ii) bulk organic geochemistry (Rock-Eval pyrolysis), (iii) optical quantification of particulate OM (palynofacies), performed on suspended sediments from the Durance, the Rhône rivers and from small rivers draining the badlands. A mean erosion rate of badlands, previously calculated for instrumented catchments (SOERE Draix-Bléone, Graz et al., 2012) was also applied to the badlands disseminated within the Durance catchment. These different methodologies converge to a petrogenic contribution of the OC export to the Mediterranean Sea close to 30 %. Badlands from the Durance catchment

Dynamics of particulate phosphorus in a shallow eutrophic lake

Energy Technology Data Exchange (ETDEWEB)

Shinohara, Ryuichiro, E-mail: r-shino@nies.go.jp [National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305-8506 (Japan); Imai, Akio; Kohzu, Ayato; Tomioka, Noriko [National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305-8506 (Japan); Furusato, Eiichi [Graduate School of Science and Engineering, Saitama University, 255 Shimo-okubo, Sakura-ku, Saitama 338-8570 (Japan); Satou, Takayuki; Sano, Tomoharu; Komatsu, Kazuhiro; Miura, Shingo; Shimotori, Koichi [National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305-8506 (Japan)

2016-09-01

We tested the hypothesis that in shallow, eutrophic Lake Kasumigaura, the concentration of particulate phosphorus (PP) is controlled by biogenic P (P in living or dead phytoplankton and bacterial cells), rather than by resuspension of inorganic P in sediment. Increases in wind velocity and turbidity were associated with bottom shear stress exceeding the critical value for the lake (τ{sub c} = 0.15 N m{sup −2}); this increased turbidity was due to sediment resuspension. However, concentrations of PP; HCl-extractable, reactive P in PP (P-rP); and HCl-extractable, non-reactive P in PP (P-nrP) were not correlated with wind velocity (PP vs. wind velocity: r = 0.40, p > 0.05). Rather, the P-nrP concentration accounted for approximately 79% of PP, and the concentrations of PP, P-rP, and P-nrP were correlated with the particulate organic carbon (POC) concentration (POC vs. PP: r = 0.90, p < 0.01; POC vs. P-rP: r = 0.82, p < 0.01; POC vs. P-nrP: r = 0.86, p < 0.01). In our {sup 31}P nuclear magnetic resonance spectroscopy results, mononucleotides accounted for the largest proportion among the detected P compound classes. In addition, concentrations of mononucleotides, orthophosphate, and pyrophosphate were significantly higher in samples with high POC concentrations, whereas the DNA-P concentration was not. These results suggest that biogenic P affects PP concentrations more strongly than does sediment resuspension, and the production of biogenic P creates a pool of mononucleotides, a class of easily degradable P, even in shallow, eutrophic Lake Kasumigaura. - Highlights: • Biogenic P affected the PP concentration more than did sediment resuspension. • PP correlated with particulate organic carbon concentration but not wind velocity. • Mononucleotides accounted for the largest P compound class of organic P in PP.

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...

Alignment of policies to maximize the climate benefits of diesel vehicles through control of particulate matter and black carbon emissions

International Nuclear Information System (INIS)

Minjares, Ray; Blumberg, Kate; Posada Sanchez, Francisco

2013-01-01

Diesel vehicles offer greater fuel-efficiency and lower greenhouse gas emissions at a time when national governments seek to reduce the energy and climate impacts of the vehicle fleet. Policies that promote diesels like preferential fuel taxes, fuel economy standards and greenhouse gas emission standards can produce higher emissions of diesel particulate matter if diesel particulate filters or equivalent emission control technology is not in place. This can undermine the expected climate benefits of dieselization and increase impacts on public health. This paper takes a historical look at Europe to illustrate the degree to which dieselization and lax controls on particulate matter can undermine the potential benefits sought from diesel vehicles. We show that countries on the dieselization pathway can fully capture the value of diesels with the adoption of tailpipe emission standards equivalent to Euro 6 or Tier 2 for passenger cars, and fuel quality standards that limit the sulfur content of diesel fuel to no greater than 15 ppm. Adoption of these policies before or in parallel with adoption of fuel consumption and greenhouse gas standards can avert the negative impacts of dieselization. - Highlights: ► Preferential tax policies have increased the dieselization of some light-duty vehicle fleets. ► Dieselization paired with lax emission standards produces large black carbon emissions. ► Diesel black carbon undermines the perceived climate benefits of diesel vehicles. ► Stringent controls on diesel particulate emissions will also reduce black carbon. ► Euro 6/VI equivalent emission standards can preserve the climate benefits of diesel vehicles

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.

High-Latitude Wintertime Urban Pollution: Particulate Matter Composition and Temporal Trends in Fairbanks, Alaska

Science.gov (United States)

Simpson, W. R.; Nattinger, K.; Hooper, M.

2017-12-01

High latitude cities often experience severe pollution episodes during wintertime exacerbated by thermal inversion trapping of pollutant emissions. Fairbanks, Alaska is an extreme example of this problem, currently being classified by the US Environmental Protection Agency (EPA) as a "serious" non-attainment area for fine particulate matter (PM2.5). For this reason, we have studied the chemical composition of PM2.5 at multiple EPA monitoring sites in the non-attainment area from 2006 to the present. The chemical composition is dominated by organic carbon with lesser amounts of black carbon and inorganic ionic species such as ammonium, sulfate, and nitrate. We find large spatial differences in composition and amount of PM2.5 that indicate a different mix of sources in residential areas as compared to the city center. Specifically, the difference in composition is consistent with increased wood smoke source in the residential areas. The extent to which organic matter could be secondary (formed through conversion of emitted gases) is also an area needing study. Ammonium sulfate is responsible for about a fifth to a quarter of the particles mass during the darkest months, possibly indicating a non-photochemical source of sulfate, but the chemical mechanism for this possible transformation is unclear. Therefore, we quantified the relationship between particulate sulfate concentrations and gas-phase sulfur dioxide concentrations along with particulate metals and inferred particulate acidity with the hopes that these data can assist in elucidation of the mechanism of particulate sulfate formation. We also analyze temporal trends in PM2.5 composition in an attempt to understand how the problem is changing over time and find most trends are small despite regulatory changes. Improving mechanistic understanding of particulate formation under cold and dark conditions could assist in reducing air-quality-related health effects.

Global patterns of organic carbon export and sequestration in the ocean (Arne Richter Award for Outstanding Young Scientists)

Science.gov (United States)

Henson, S.; Sanders, R.; Madsen, E.; Le Moigne, F.; Quartly, G.

2012-04-01

A major term in the global carbon cycle is the ocean's biological carbon pump which is dominated by sinking of small organic particles from the surface ocean to its interior. Here we examine global patterns in particle export efficiency (PEeff), the proportion of primary production that is exported from the surface ocean, and transfer efficiency (Teff), the fraction of exported organic matter that reaches the deep ocean. This is achieved through extrapolating from in situ estimates of particulate organic carbon export to the global scale using satellite-derived data. Global scale estimates derived from satellite data show, in keeping with earlier studies, that PEeff is high at high latitudes and low at low latitudes, but that Teff is low at high latitudes and high at low latitudes. However, in contrast to the relationship observed for deep biomineral fluxes in previous studies, we find that Teff is strongly negatively correlated with opal export flux from the upper ocean, but uncorrelated with calcium carbonate export flux. We hypothesise that the underlying factor governing the spatial patterns observed in Teff is ecosystem function, specifically the degree of recycling occurring in the upper ocean, rather than the availability of calcium carbonate for ballasting. Finally, our estimate of global integrated carbon export is only 50% of previous estimates. The lack of consensus amongst different methodologies on the strength of the biological carbon pump emphasises that our knowledge of a major planetary carbon flux remains incomplete.

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

Strain-specific responses of Emiliania huxleyi to changing seawater carbonate chemistry

Directory of Open Access Journals (Sweden)

P. Ziveri

2009-11-01

Full Text Available Four strains of the coccolithophore E. huxleyi (RCC1212, RCC1216, RCC1238, RCC1256 were grown in dilute batch culture at four CO2 levels ranging from ~200 μatm to ~1200 μatm. Growth rate, particulate organic carbon content, and particulate inorganic carbon content were measured, and organic and inorganic carbon production calculated. The four strains did not show a uniform response to carbonate chemistry changes in any of the analysed parameters and none of the four strains displayed a response pattern previously described for this species. We conclude that the sensitivity of different strains of E. huxleyi to acidification differs substantially and that this likely has a genetic basis. We propose that this can explain apparently contradictory results reported in the literature.

Natural diet of coral-excavating sponges consists mainly of dissolved organic carbon (DOC).

Science.gov (United States)

Mueller, Benjamin; de Goeij, Jasper M; Vermeij, Mark J A; Mulders, Yannick; van der Ent, Esther; Ribes, Marta; van Duyl, Fleur C

2014-01-01

Coral-excavating sponges are the most important bioeroders on Caribbean reefs and increase in abundance throughout the region. This increase is commonly attributed to a concomitant increase in food availability due to eutrophication and pollution. We therefore investigated the uptake of organic matter by the two coral-excavating sponges Siphonodictyon sp. and Cliona delitrix and tested whether they are capable of consuming dissolved organic carbon (DOC) as part of their diet. A device for simultaneous sampling of water inhaled and exhaled by the sponges was used to directly measure the removal of DOC and bacteria in situ. During a single passage through their filtration system 14% and 13% respectively of the total organic carbon (TOC) in the inhaled water was removed by the sponges. 82% (Siphonodictyon sp.; mean ± SD; 13 ± 17 μmol L(-1)) and 76% (C. delitrix; 10 ± 12 μmol L(-1)) of the carbon removed was taken up in form of DOC, whereas the remainder was taken up in the form of particulate organic carbon (POC; bacteria and phytoplankton) despite high bacteria retention efficiency (72 ± 15% and 87 ± 10%). Siphonodictyon sp. and C. delitrix removed DOC at a rate of 461 ± 773 and 354 ± 562 μmol C h(-1) respectively. Bacteria removal was 1.8 ± 0.9 × 10(10) and 1.7 ± 0.6 × 10(10) cells h(-1), which equals a carbon uptake of 46.0 ± 21.2 and 42.5 ± 14.0 μmol C h(-1) respectively. Therefore, DOC represents 83 and 81% of the TOC taken up by Siphonodictyon sp. and C. delitrix per hour. These findings suggest that similar to various reef sponges coral-excavating sponges also mainly rely on DOC to meet their carbon demand. We hypothesize that excavating sponges may also benefit from an increasing production of more labile algal-derived DOC (as compared to coral-derived DOC) on reefs as a result of the ongoing coral-algal phase shift.

Natural diet of coral-excavating sponges consists mainly of dissolved organic carbon (DOC.

Directory of Open Access Journals (Sweden)

Benjamin Mueller

Full Text Available Coral-excavating sponges are the most important bioeroders on Caribbean reefs and increase in abundance throughout the region. This increase is commonly attributed to a concomitant increase in food availability due to eutrophication and pollution. We therefore investigated the uptake of organic matter by the two coral-excavating sponges Siphonodictyon sp. and Cliona delitrix and tested whether they are capable of consuming dissolved organic carbon (DOC as part of their diet. A device for simultaneous sampling of water inhaled and exhaled by the sponges was used to directly measure the removal of DOC and bacteria in situ. During a single passage through their filtration system 14% and 13% respectively of the total organic carbon (TOC in the inhaled water was removed by the sponges. 82% (Siphonodictyon sp.; mean ± SD; 13 ± 17 μmol L(-1 and 76% (C. delitrix; 10 ± 12 μmol L(-1 of the carbon removed was taken up in form of DOC, whereas the remainder was taken up in the form of particulate organic carbon (POC; bacteria and phytoplankton despite high bacteria retention efficiency (72 ± 15% and 87 ± 10%. Siphonodictyon sp. and C. delitrix removed DOC at a rate of 461 ± 773 and 354 ± 562 μmol C h(-1 respectively. Bacteria removal was 1.8 ± 0.9 × 10(10 and 1.7 ± 0.6 × 10(10 cells h(-1, which equals a carbon uptake of 46.0 ± 21.2 and 42.5 ± 14.0 μmol C h(-1 respectively. Therefore, DOC represents 83 and 81% of the TOC taken up by Siphonodictyon sp. and C. delitrix per hour. These findings suggest that similar to various reef sponges coral-excavating sponges also mainly rely on DOC to meet their carbon demand. We hypothesize that excavating sponges may also benefit from an increasing production of more labile algal-derived DOC (as compared to coral-derived DOC on reefs as a result of the ongoing coral-algal phase shift.

Source contributions and regional transport of primary particulate matter in China

International Nuclear Information System (INIS)

Hu, Jianlin; Wu, Li; Zheng, Bo; Zhang, Qiang; He, Kebin; Chang, Qing; Li, Xinghua; Yang, Fumo; Ying, Qi; Zhang, Hongliang

2015-01-01

A source-oriented CMAQ was applied to determine source sector/region contributions to primary particulate matter (PPM) in China. Four months were simulated with emissions grouped to eight regions and six sectors. Predicted elemental carbon (EC), primary organic carbon (POC), and PPM concentrations and source contributions agree with measurements and have significant spatiotemporal variations. Residential is a major contributor to spring/winter EC (50–80%), POC (60%–90%), and PPM (30–70%). For summer/fall, industrial contributes 30–50% for EC/POC and 40–60% for PPM. Transportation is more important for EC (20–30%) than POC/PPM ( 90% in Beijing. - Highlights: • A source-oriented CMAQ was established for primary particulate matter (PPM). • Source and region contributions to EC, POC and PPM in China were quantified. • Residential is major in spring/winter and industrial dominates in summer/fall. • Open burning is more important for southern while dust is in contrast. • Both local and Heibei emissions contribute to PPM in Beijing. - Source and region contributions to primary particulate matter in China were quantified for four months during 2012-2013. Residential and industrial are the major contributors.

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)

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

A cross-site comparison of factors controlling streamwater carbon flux in western North American catchments (Invited)

Science.gov (United States)

Brooks, P. D.; Biederman, J. A.; Condon, K.; Chorover, J.; McIntosh, J. C.; Meixner, T.; Perdrial, J. N.

2013-12-01

Increasing variability in climate is expected to alter the amount and form of terrestrial carbon in stream water both directly, through changes in the magnitude and timing of discharge, and indirectly through changes in land cover following disturbance (e.g. drought, fire, or insect driven mortality). Predicting how these changes will impact individual stream-catchment ecosystems however, is hampered by a lack of concurrent observations on both dissolved and particulate carbon flux across a range of spatial, temporal, and discharge scales. Because carbon is strongly coupled to most biogeochemical reactions within both aquatic and terrestrial ecosystems, this represents a critical unknown in predicting the response of catchment-ecosystems to concurrent changes in climate and land cover. This presentation will address this issue using a meta-analysis of dissolved organic, dissolved inorganic, and particulate organic carbon fluxes from multiple locations, including undisturbed sites along a climate gradient from desert rivers to seasonally snow-covered, forested mountain catchments, and sites disturbed by both fire and extensive, insect driven mortality. Initial analyses suggest that dissolved (organic and inorganic) and particulate fluxes respond differently to various types of disturbance and depend on interactions between changes in size of mobile carbon pools and changes in hydrologic routing of carbon to streamwater. Anomalously large fluxes of both dissolved and particulate organic matter are associated with episodic changes in hydrologic routing (e.g. storm floods; snowmelt) that connect normally hydrologically isolated carbon pools (e.g. surficial hillslope soils) with surface water. These events are often of short duration as the supply of mobile carbon is exhausted in short term flushing response. In contrast, disturbances that increase the size of the mobile carbon pool (e.g. widespread vegetation mortality) result smaller proportional increases in

The Role of Physical and Human Landscape Properties on Carbon Composition of Organic Matter in Tropical Rivers

Science.gov (United States)

Ballester, M. R.; Krusche, A. V.; Victoria, R. L.; Richey, J. E.; Deegan, L.; Neill, C.

2011-12-01

To evaluate physical and human controls organic matter carbon composition in tropical rivers, we applied an integrated analysis of landscape properties and riverine isotopic composition. Our goal was to establish the relationships between basin attributes and forms and composition of dissolved and particulate organic matter in rivers. A GIS template was developed as tool to support the understanding of the biogeochemistry of the surface waters of the Ji-Paraná (Western Amazonia) and the Piracicaba (southeastern of Brazil)rivers. Each basin was divided into drainage units, organized according to river network morphology and degree of land-use impact. The delineated drainage areas were individually characterized in terms of topography, soils and land use using data sets compiled as layers in ArcGis and ERDAS-IMAGINE software. DOM and POM carbon stable isotopic composition were determined at several sites along the main tributaries and small streams. The effects of these drivers on the fluvial carbon was quantified by a multiple linear regression analysis, relating basin characteristics and river isotopic composition. The results showed that relatively recent land cover changes have already had an impact on the composition of the riverine DOM and POM, indicating that, as in natural ecosystems, the vegetation plays a key role in the composition of the riverine organic matter in agricultural systems.

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.

Particulate matter and black carbon optical properties and emission factors from prescribed fires in the southeastern United States

Science.gov (United States)

The aerosol emissions from prescribed fires in the Southeastern United States were measured and compared to emissions from laboratory burns with fuels collected from the site. Fine particulate matter (PM2.5), black carbon, and aerosol light scattering and absorption were characte...

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.

Laboratory Validation of Four Black Carbon Measurement Methods for Determination of the Nonvolatile Particulate Matter (nvPM) Mass Emissions from Commercial Aircraft Engines

Science.gov (United States)

Four candidate black carbon (BC) measurement techniques have been identified by the SAE International E-31 Committee for possible use in determining nonvolatile particulate matter (nvPM) mass emissions during commercial aircraft engine certification. These techniques are carbon b...

Nepal Ambient Monitoring and Source Testing Experiment (NAMaSTE): Emissions of particulate matter from wood and dung cooking fires, brick kilns, generators, trash and crop residue burning

Science.gov (United States)

Stone, Elizabeth; Jayarathne, Thilina; Stockwell, Chelsea; Christian, Ted; Bhave, Prakash; Siva Praveen, Puppala; Panday, Arnico; Adhikari, Sagar; Maharjan, Rashmi; Goetz, Doug; DeCarlo, Peter; Saikawa, Eri; Yokelson, Robert

2016-04-01

The Nepal Ambient Monitoring and Source Testing Experiment (NAMASTE) field campaign targeted the in situ characterization of widespread and under-sampled combustion sources. In Kathmandu and the Terai, southern Nepal's flat plains, samples of fine particulate matter (PM2.5) were collected from wood and dung cooking fires (n = 22), generators (n = 2), groundwater pumps (n = 2), clamp kilns (n = 3), zig-zag kilns (n = 3), trash burning (n = 4), one heating fire, and one crop residue fire. Co-located measurements of carbon dioxide, carbon monoxide, and volatile organic compounds allowed for the application of the carbon mass balance approach to estimate emission factors for PM2.5, elemental carbon, organic carbon, and water-soluble inorganic ions. Organic matter was chemically speciated using gas chromatography - mass spectrometry for polycyclic aromatic hydrocarbons, sterols, n-alkanes, hopanes, steranes, and levoglucosan, which accounted for 2-8% of the measured organic carbon. These data were used to develop molecular-marker based profiles for use in source apportionment modeling. This study provides quantitative emission factors for particulate matter and its constituents for many important combustion sources in Nepal and South Asia.

[Effects of grazing disturbance on soil active organic carbon in mountain forest-arid valley ecotone in the upper reaches of Minjiang River].

Science.gov (United States)

Liu, Shan-Shan; Zhang, Xing-Hua; Gong, Yuan-Bo; Li, Yuan; Wang, Yan; Yin, Yan-Jie; Ma, Jin-Song; Guo, Ting

2014-02-01

Effects of grazing disturbance on the soil carbon contents and active components in the four vegetations, i.e., artificial Robinia pseudoacacia plantation, artificial poplar plantation, Berberis aggregate shrubland and grassland, were studied in the mountain forest-arid valley ecotone in the upper Minjiang River. Soil organic carbon and active component contents in 0-10 cm soil layer were greater than in 10-20 cm soil layer at each level of grazing disturbance. With increasing the grazing intensity, the total organic carbon (TOC), light fraction organic carbon (LFOC), particulate organic carbon (POC) and easily oxidized carbon (LOC) contents in 0-10 cm soil layer decreased gradually in the artificial R. pseudoacacia plantation. The LFOC content decreased, the POC content increased, and the TOC and LOC contents decreased initially and then increased with increasing the grazing intensity in the artificial poplar plantation. The POC content decreased, and the TOC, LFOC and LOC contents decreased initially and then increased with increasing the grazing intensity in the B. aggregate shrubland. The POC and TOC contents decreased, and the LFOC and LOC contents decreased initially and then increased with increasing the grazing intensity in the grassland. The decreasing ranges of LOC, LFOC and POC contents were 0.1-7.9 times more than that of TOC content. There were significant positive relationships between TOC and LOC, LFOC and POC, suggesting that the active organic carbon components could reflect the change of soil total carbon content.

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.

Assessment of Contribution of Contemporary Carbon Sources to Size-Fractionated Particulate Matter and Time-Resolved Bulk Particulate Matter Using the Measurement of Radiocarbon

Energy Technology Data Exchange (ETDEWEB)

Hwang, H M; Young, T M; Buchholz, B A

2009-04-16

This study was motivated by a desire to improve understanding of the sources contributing to the carbon that is an important component of airborne particulate matter (PM). The ultimate goal of this project was to lay a ground work for future tools that might be easily implemented with archived or routinely collected samples. A key feature of this study was application of radiocarbon measurement that can be interpreted to indicate the relative contributions from fossil and non-fossil carbon sources of atmospheric PM. Size-resolved PM and time-resolved PM{sub 10} collected from a site in Sacramento, CA in November 2007 (Phase I) and March 2008 (Phase II) were analyzed for radiocarbon and source markers such as levoglucosan, cholesterol, and elemental carbon. Radiocarbon data indicates that the contributions of non-fossil carbon sources were much greater than that from fossil carbon sources in all samples. Radiocarbon and source marker measurements confirm that a greater contribution of non-fossil carbon sources in Phase I samples was highly likely due to residential wood combustion. The present study proves that measurement of radiocarbon and source markers can be readily applied to archived or routinely collected samples for better characterization of PM sources. More accurate source apportionment will support ARB in developing more efficient control strategies.

Radiocarbon dating of fluvial organic matter reveals land-use impacts in boreal peatlands

DEFF Research Database (Denmark)

Hulatt, Chris J.; Kaartokallio, Hermanni; Oinonen, Markku

2014-01-01

This study measured the effects of land use on organic matter released to surface waters in a boreal peat catchment using radiocarbon dating of particulate and dissolved organic carbon (POC and DOC), DOC concentration, stable carbon and nitrogen isotope composition, and optical measurements. Undi...

The dynamics of CO2 fixation in the Southern Ocean as indicated by carboxylase activities and organic carbon isotopic ratios

International Nuclear Information System (INIS)

Fontugne, M.

1991-01-01

Recent studies have suggested a direct relationship between the dissolved CO 2 concentration and carbon isotopic composition of phytoplankton in surface ocean. Thus, measurement of δ 13 C of planktonic organic matter in deep-sea ocean cores can potentially yield a record of the past atmospheric CO 2 variations. However, results are presented from 3 cruises in Indian and Atlantic sectors of the Southern Ocean (between 40-66degS) in which biochemical and physiological factors associated with photosynthetic processes lead to carbon isotopic fractionation by phytoplankton which cannot be directly related to variations within the mineral carbon pool. Simultaneous measurements of the carboxylase activities in the 13 C/ 12 C ratio of particulate organic carbon show that there is a large variability in phytoplankton carbon metabolism, especially on a seasonal scale, in spite of a relative uniformity of the environmental conditions. Phytoplankton carbon metabolism is clearly a main factor governing variations in the stable isotopic composition of organic matter in the euphotic layer. Interrelationships between light, Rubiso activity and δ 13 C are clearly shown by the data. Heterotrophic processes may also influence the carbon isotope mass balance, especially during the break-up of the ice pack. In addition to the influence of photosynthetic metabolism, the effect of the meridoneal temperature gradient is also verified by the data set. (author). 24 refs.; 5 figs

Black carbon and particulate matter (PM2.5) concentrations in New York City's subway stations.

Science.gov (United States)

Vilcassim, M J Ruzmyn; Thurston, George D; Peltier, Richard E; Gordon, Terry

2014-12-16

The New York City (NYC) subway is the main mode of transport for over 5 million passengers on an average weekday. Therefore, airborne pollutants in the subway stations could have a significant impact on commuters and subway workers. This study looked at black carbon (BC) and particulate matter (PM2.5) concentrations in selected subway stations in Manhattan. BC and PM2.5 levels were measured in real time using a Micro-Aethalometer and a PDR-1500 DataRAM, respectively. Simultaneous samples were also collected on quartz filters for organic and elemental carbon (OC/EC) analysis and on Teflon filters for gravimetric and trace element analysis. In the underground subway stations, mean real time BC concentrations ranged from 5 to 23 μg/m(3), with 1 min average peaks >100 μg/m(3), while real time PM2.5 levels ranged from 35 to 200 μg/m(3). Mean EC levels ranged from 9 to 12.5 μg/m(3). At street level on the same days, the mean BC and PM2.5 concentrations were below 3 and 10 μg/m(3), respectively. This study shows that both BC soot and PM levels in NYC's subways are considerably higher than ambient urban street levels and that further monitoring and investigation of BC and PM subway exposures are warranted.

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...

How organic carbon derived from multiple sources contributes to carbon sequestration processes in a shallow coastal system?

Science.gov (United States)

Watanabe, Kenta; Kuwae, Tomohiro

2015-04-16

Carbon captured by marine organisms helps sequester atmospheric CO 2 , especially in shallow coastal ecosystems, where rates of primary production and burial of organic carbon (OC) from multiple sources are high. However, linkages between the dynamics of OC derived from multiple sources and carbon sequestration are poorly understood. We investigated the origin (terrestrial, phytobenthos derived, and phytoplankton derived) of particulate OC (POC) and dissolved OC (DOC) in the water column and sedimentary OC using elemental, isotopic, and optical signatures in Furen Lagoon, Japan. Based on these data analysis, we explored how OC from multiple sources contributes to sequestration via storage in sediments, water column sequestration, and air-sea CO 2 exchanges, and analyzed how the contributions vary with salinity in a shallow seagrass meadow as well. The relative contribution of terrestrial POC in the water column decreased with increasing salinity, whereas autochthonous POC increased in the salinity range 10-30. Phytoplankton-derived POC dominated the water column POC (65-95%) within this salinity range; however, it was minor in the sediments (3-29%). In contrast, terrestrial and phytobenthos-derived POC were relatively minor contributors in the water column but were major contributors in the sediments (49-78% and 19-36%, respectively), indicating that terrestrial and phytobenthos-derived POC were selectively stored in the sediments. Autochthonous DOC, part of which can contribute to long-term carbon sequestration in the water column, accounted for >25% of the total water column DOC pool in the salinity range 15-30. Autochthonous OC production decreased the concentration of dissolved inorganic carbon in the water column and thereby contributed to atmospheric CO 2 uptake, except in the low-salinity zone. Our results indicate that shallow coastal ecosystems function not only as transition zones between land and ocean but also as carbon sequestration filters. They

Organic carbon content of tropical zooplankton

Digital Repository Service at National Institute of Oceanography (India)

Nair, V.R.

In the Zuari and Mandovi estuaries variations in organic carbon of zooplankton are 26.4-38.8 and 24-39.9% of dry weight respectively. Maximum carbon content of estuarine zooplankton is observed in November. Organic carbon in nearshore and oceanic...

ORGANIC MATTER LABILE FRACTIONS AND CARBON STOCKS IN A TYPIC QUARTZIPSAMMENT CULTIVATED WITH SUGARCANE HARVESTED WITHOUT BURNING

Directory of Open Access Journals (Sweden)

JOSÉ DE SOUZA OLIVEIRA FILHO

2017-01-01

Full Text Available The permanence of sugarcane straw on the soil surface, in systems without the pre-harvest straw burning practice, directly affects the soil organic matter dynamics. The objective of this work was to evaluate the changes in total organic carbon (TOC, carbon in the light organic matter (CLOM and particulate organic carbon (POC, and their carbon stocks in a typic Quartzipsamment cultivated for nine years with sugarcane crops, which were conducted without the pre-harvest straw burning practice, in Paraipaba, State of Ceará, Brazil. Disturbed and undisturbed soil samples were collected at depths of 0.0-0.025, 0.025-0.05, 0.05-0.10, 0.10-0.20 and 0.20-0.30 m, in the sugarcane crop area and in an adjacent native forest area, in order to quantify the TOC, CLOM and POC, as well as the carbon stocks accumulated in the layer 0.0-0.30 m related to these fractions (TOCSt, CLOMSt and POCSt. TOC content changes after nine years of sugarcane crops, conducted without pre-harvest straw burning, were found only in the layers 0.10-0.20 and 0.20-0.30 m. The CLOM varied only in the layer 0.025-0.05 m. The POC content changes were more noticeable than the changes in TOC and CMOL. The CLOM of the sugarcane crop area presented high similarity with TOC, which may affect their quantification in studies related to the soil organic matter dynamics. The sugarcane crop increased the TOCSt, POCSt and CLOMSt in the layer 0.0-0.30 m, compared with the adjacent native forest area.

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

Method for determination of stable carbon isotope ratio of methylnitrophenols in atmospheric particulate matter

Directory of Open Access Journals (Sweden)

S. Moukhtar

2011-11-01

Full Text Available A technique for the measurement of the stable isotope ratio of methylnitrophenols in atmospheric particulate matter is presented. Atmospheric samples from rural and suburban areas were collected for evaluation of the procedure. Particulate matter was collected on quartz fibre filters using dichotomous high volume air samplers. Methylnitrophenols were extracted from the filters using acetonitrile. The sample was then purified using a combination of high-performance liquid chromatography and solid phase extraction. The final solution was then divided into two aliquots. To one aliquot, a derivatising agent, Bis(trimethylsilyltrifluoroacetamide, was added for Gas Chromatography-Mass Spectrometry analysis. The second half of the sample was stored in a refrigerator. For samples with concentrations exceeding 1 ng μl⁻¹, the second half of the sample was used for measurement of stable carbon isotope ratios by Gas Chromatography-Isotope Ratio Mass Spectrometry.

The procedure described in this paper provides a method for the analysis of methylnitrophenols in atmospheric particulate matter at concentrations as low as 0.3 pg m⁻³ and for stable isotope ratios with an accuracy of better than ±0.5‰ for concentrations exceeding 100 pg m⁻³.

In all atmospheric particulate matter samples analysed, 2-methyl-4-nitrophenol was found to be the most abundant methylnitrophenol, with concentrations ranging from the low pg m⁻³ range in rural areas to more than 200 pg m⁻³ in some samples from a suburban location.

Ambient organic carbon to elemental carbon ratios: Influence of the thermal–optical temperature protocol and implications

Energy Technology Data Exchange (ETDEWEB)

Cheng, Yuan, E-mail: ycheng@mail.tsinghua.edu.cn [State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing (China); He, Ke-bin, E-mail: hekb@tsinghua.edu.cn [State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing (China); State Environmental Protection Key Laboratory of Sources and Control of Air Pollution Complex, Beijing (China); Duan, Feng-kui; Du, Zhen-yu [State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing (China); Zheng, Mei [College of Environmental Sciences and Engineering, Peking University, Beijing (China); Ma, Yong-liang [State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing (China)

2014-01-01

Ambient organic carbon (OC) to elemental carbon (EC) ratios are strongly associated with not only the radiative forcing due to aerosols but also the extent of secondary organic aerosol (SOA) formation. An inter-comparison study was conducted based on fine particulate matter samples collected during summer in Beijing to investigate the influence of the thermal–optical temperature protocol on the OC to EC ratio. Five temperature protocols were used such that the NIOSH (National Institute for Occupational Safety and Health) and EUSAAR (European Supersites for Atmospheric Aerosol Research) protocols were run by the Sunset carbon analyzer while the IMPROVE (the Interagency Monitoring of Protected Visual Environments network)-A protocol and two alternative protocols designed based on NIOSH and EUSAAR were run by the DRI analyzer. The optical attenuation measured by the Sunset carbon analyzer was more easily biased by the shadowing effect, whereas total carbon agreed well between the Sunset and DRI analyzers. The EC{sub IMPROVE-A} (EC measured by the IMPROVE-A protocol; similar hereinafter) to EC{sub NIOSH} ratio and the EC{sub IMPROVE-A} to EC{sub EUSAAR} ratio averaged 1.36 ± 0.21 and 0.91 ± 0.10, respectively, both of which exhibited little dependence on the biomass burning contribution. Though the temperature protocol had substantial influence on the OC to EC ratio, the contributions of secondary organic carbon (SOC) to OC, which were predicted by the EC-tracer method, did not differ significantly among the five protocols. Moreover, the SOC contributions obtained in this study were comparable with previous results based on field observation (typically between 45 and 65%), but were substantially higher than the estimation provided by an air quality model (only 18%). The comparison of SOC and WSOC suggests that when using the transmittance charring correction, all of the three common protocols (i.e., IMPROVE-A, NIOSH and EUSAAR) could be reliable for the estimation

Ambient organic carbon to elemental carbon ratios: Influence of the thermal–optical temperature protocol and implications

International Nuclear Information System (INIS)

Cheng, Yuan; He, Ke-bin; Duan, Feng-kui; Du, Zhen-yu; Zheng, Mei; Ma, Yong-liang

2014-01-01

Ambient organic carbon (OC) to elemental carbon (EC) ratios are strongly associated with not only the radiative forcing due to aerosols but also the extent of secondary organic aerosol (SOA) formation. An inter-comparison study was conducted based on fine particulate matter samples collected during summer in Beijing to investigate the influence of the thermal–optical temperature protocol on the OC to EC ratio. Five temperature protocols were used such that the NIOSH (National Institute for Occupational Safety and Health) and EUSAAR (European Supersites for Atmospheric Aerosol Research) protocols were run by the Sunset carbon analyzer while the IMPROVE (the Interagency Monitoring of Protected Visual Environments network)-A protocol and two alternative protocols designed based on NIOSH and EUSAAR were run by the DRI analyzer. The optical attenuation measured by the Sunset carbon analyzer was more easily biased by the shadowing effect, whereas total carbon agreed well between the Sunset and DRI analyzers. The EC IMPROVE-A (EC measured by the IMPROVE-A protocol; similar hereinafter) to EC NIOSH ratio and the EC IMPROVE-A to EC EUSAAR ratio averaged 1.36 ± 0.21 and 0.91 ± 0.10, respectively, both of which exhibited little dependence on the biomass burning contribution. Though the temperature protocol had substantial influence on the OC to EC ratio, the contributions of secondary organic carbon (SOC) to OC, which were predicted by the EC-tracer method, did not differ significantly among the five protocols. Moreover, the SOC contributions obtained in this study were comparable with previous results based on field observation (typically between 45 and 65%), but were substantially higher than the estimation provided by an air quality model (only 18%). The comparison of SOC and WSOC suggests that when using the transmittance charring correction, all of the three common protocols (i.e., IMPROVE-A, NIOSH and EUSAAR) could be reliable for the estimation of SOC by the EC

Long-term rice cultivation stabilizes soil organic carbon and promotes soil microbial activity in a salt marsh derived soil chronosequence

Science.gov (United States)

Wang, Ping; Liu, Yalong; Li, Lianqing; Cheng, Kun; Zheng, Jufeng; Zhang, Xuhui; Zheng, Jinwei; Joseph, Stephen; Pan, Genxing

2015-01-01

Soil organic carbon (SOC) sequestration with enhanced stable carbon storage has been widely accepted as a very important ecosystem property. Yet, the link between carbon stability and bio-activity for ecosystem functioning with OC accumulation in field soils has not been characterized. We assessed the changes in microbial activity versus carbon stability along a paddy soil chronosequence shifting from salt marsh in East China. We used mean weight diameter, normalized enzyme activity (NEA) and carbon gain from straw amendment for addressing soil aggregation, microbial biochemical activity and potential C sequestration, respectively. In addition, a response ratio was employed to infer the changes in all analyzed parameters with prolonged rice cultivation. While stable carbon pools varied with total SOC accumulation, soil respiration and both bacterial and fungal diversity were relatively constant in the rice soils. Bacterial abundance and NEA were positively but highly correlated to total SOC accumulation, indicating an enhanced bio-activity with carbon stabilization. This could be linked to an enhancement of particulate organic carbon pool due to physical protection with enhanced soil aggregation in the rice soils under long-term rice cultivation. However, the mechanism underpinning these changes should be explored in future studies in rice soils where dynamic redox conditions exist. PMID:26503629

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...

Evaluating Simulated Primary Anthropogenic and Biomass Burning Organic Aerosols during MILAGRO: Implications for Assessing Treatments of Secondary Organic Aerosols

Energy Technology Data Exchange (ETDEWEB)

Fast, Jerome D.; Aiken, Allison; Allan, James D.; Alexander, M. L.; Campos, Teresa; Canagaratna, Manjula R.; Chapman, Elaine G.; DeCarlo, Peter; de Foy, B.; Gaffney, Jeffrey; de Gouw, Joost A.; Doran, J. C.; Emmons, L.; Hodzic, Alma; Herndon, Scott C.; Huey, L. G.; Jayne, John T.; Jimenez, Jose L.; Kleinman, Lawrence I.; Kuster, W. C.; Marley, Nancy A.; Russell, Lynn M.; Ochoa, Carlos; Onasch, Timothy B.; Pekour, Mikhail S.; Song, Chen; Ulbrich, Ingrid M.; Warneke, Carsten; Welsh-Bon, Daniel; Wiedinmyer, Christine; Worsnop, Douglas R.; Yu, Xiao-Ying; Zaveri, Rahul A.

2009-08-31

Simulated primary organic aerosols (POA), as well as other particulates and trace gases, in the vicinity of Mexico City are evaluated using measurements collected during the 2006 Megacity Initiative: Local and Global Research Observations (MILAGRO) field campaigns. Since the emission inventories and dilution will affect predictions of total organic matter and consequently total particulate matter, our objective is to assess the uncertainties in predicted POA before testing and evaluating the performance of secondary organic aerosol (SOA) treatments. Carbon monoxide (CO) is well simulated on most days both over the city and downwind, indicating that transport and mixing processes were usually consistent with the meteorological conditions observed during MILAGRO. Predicted and observed elemental carbon (EC) in the city was similar, but larger errors occurred at remote locations since the CO/EC emission ratios in the national emission inventory were lower than in the metropolitan emission inventory. Components of organic aerosols derived from Positive Matrix Factorization and data from several Aerodyne Aerosol Mass Spectrometer instruments deployed both at ground sites and on research aircraft are used to evaluate the model. Predicted POA was consistently lower than the measured organic matter at the ground sites, which is consistent with the expectation that SOA should be a large fraction of the total organic matter mass. A much better agreement was found when predicted POA was compared with the sum of "primary anthropogenic" and "primary biomass burning" components on days with relatively low biomass burning, suggesting that the overall magnitude of primary organic particulates released was reasonable. The predicted POA was greater than the total observed organic matter when the aircraft flew directly downwind of large fires, suggesting that biomass burning emission estimates from some large fires may be too high. Predicted total observed organic carbon (TOOC) was

Permanganate oxidizable carbon reflects a processed soil fraction that is sensitive to management

Science.gov (United States)

Permanganate oxidizable C (POXC; i.e., active C) is a relatively new method that can quantify labile soil C rapidly and inexpensively. Despite limited reports of positive correlations with particulate organic carbon (POC), microbial biomass carbon (MBC) and other soil carbon (C) fractions, little i...

Soil Organic Carbon and Its interaction with Minerals in Two Hillslopes with Different Climates and Erosion Processes

Science.gov (United States)

Wang, X.; Yoo, K.; Wackett, A. A.; Gutknecht, J.; Amundson, R.; Heimsath, A. M.

2017-12-01

Climate and topography have been widely recognized as important factors regulating soil organic carbon (SOC) dynamics but their interactive effects on SOC storage and its pools remain poorly constrained. Here we aimed to evaluate SOC storages and carbon-mineral interactions along two hillslope transects with moderately different climates (MAP: 549 mm vs. 816 mm) in Southeastern Australia. We sampled soil along the convex (eroding)-to-convergent (depositional) continuum at each hillslope transect and conducted size and density fractionation of these samples. In responses to the difference in climate factor, SOC inventories of eroding soils were twice as large at the wetter site compared with the drier site but showed little difference between two sites in depositional soils. These trends in SOC inventories were primarily controlled by SOC concentrations and secondarily by soil thicknesses. Similar patterns were observed for mineral associated organic carbon (MOC), and the abundances of MOC were controlled by the two independently operating processes affecting MOC concentration and fine-heavy fraction minerals. The contents and species of secondary clay and iron oxide minerals, abundances of particulate organic carbon, and bioturbation affected MOC concentrations. In contrast, the abundances of fine-heavy fraction minerals were impacted by erosion mechanisms that uniquely responded to regional- and micro- climate conditions. Consequently, topographic influences on SOC inventories and carbon-mineral interactions were more strongly pronounced in the drier climate where vegetation and erosion mechanisms were sensitive to microclimate. Our results highlight the significance of understanding topography and erosional processes in capturing climatic effects on soil carbon dynamics.

Palynofacies assemblages reflect sources of organic matter in New Zealand fjords

Science.gov (United States)

Prebble, Joseph G.; Hinojosa, Jessica L.; Moy, Christopher M.

2018-02-01

Understanding sources and transport pathways of organic carbon in fjord systems is important to quantify carbon cycling in coastal settings. Provenance of surficial sediment organic carbon in Fiordland National Park (southwestern New Zealand) has previously been estimated using a range of techniques, including mixing models derived from stable isotopes and lipid biomarker distributions. Here, we present the first application of palynofacies to explore the sources of particulate organic carbon to five fjords along the SW margin of New Zealand, to further discriminate the provenance of organic carbon in the fjords. We find good correlation between isotopic-and biomarker-derived proxies for organic carbon provenance and our new palynofacies observations. We observe strong down-fjord gradients of decreasing terrestrially derived organic carbon further from the river inflow at fjord heads. Fjords with small catchments and minor fresh water inflow exhibit reversed gradients, indicating that volume of freshwater entering at the fjord head is a primary mechanism to transport particulates down fjord rather than local transport from fjord sides. The palynofacies data also confirmed previously recorded latitudinal trends (i.e. between fjords), of less frequent and more weathered terrestrially derived organic carbon in the southern fjords, consistent with enhanced marine inflow and longer transport times in the southern catchments. Dinocyst assemblages also exhibit a strong latitudinal gradient, with assemblages dominated by heterotrophic forms in the north. In addition to providing support for previous studies, this approach allows finer discrimination of terrestrial organic carbon than previously, for example variation of leaf material. This study demonstrates that visual palynofacies analysis is a valuable tool to pinpoint origins of organic carbon in fjord systems, providing different but complementary information to other proxies.

The effects of biodiesels on semivolatile and nonvolatile particulate matter emissions from a light-duty diesel engine.

Science.gov (United States)

Cheng, Yuan; Li, Shao-Meng; Liggio, John; Hayden, Katherine; Han, Yuemei; Stroud, Craig; Chan, Tak; Poitras, Marie-Josée

2017-11-01

Semivolatile organic compounds (SVOCs) represent a dominant category of secondary organic aerosol precursors that are increasingly included in air quality models. In the present study, an experimental system was developed and applied to a light-duty diesel engine to determine the emission factors of particulate SVOCs (pSVOCs) and nonvolatile particulate matter (PM) components at dilution ratios representative of ambient conditions. The engine was tested under three steady-state operation modes, using ultra-low-sulfur diesel (ULSD), three types of pure biodiesels and their blends with ULSD. For ULSD, the contribution of pSVOCs to total particulate organic matter (POM) mass in the engine exhaust ranged between 21 and 85%. Evaporation of pSVOCs from the diesel particles during dilution led to decreases in the hydrogen to carbon ratio of POM and the PM number emission factor of the particles. Substituting biodiesels for ULSD could increase pSVOCs emissions but brought on large reductions in black carbon (BC) emissions. Among the biodiesels tested, tallow/used cooking oil (UCO) biodiesel showed advantages over soybean and canola biodiesels in terms of both pSVOCs and nonvolatile PM emissions. It is noteworthy that PM properties, such as particle size and BC mass fraction, differed substantially between emissions from conventional diesel and biodiesels. Copyright © 2017 Elsevier Ltd. All rights reserved.

Rivers of Carbon: Carbon Fluxes in a Watershed Context

Science.gov (United States)

Wohl, E.; Tom, B.; Hovius, N.

2017-12-01

Research within the past decade has identified the roles of diverse terrestrial processes in mobilizing terrestrial carbon from bedrock, soil, and vegetation and in redistributing this carbon among the atmosphere, biota, geosphere, and oceans. Rivers are central to carbon redistribution, serving as the primary initial receptor of mobilized terrestrial carbon, as well as governing the proportions of carbon sequestered within sediment, transported to oceans, or released to the atmosphere. We use a riverine carbon budget to examine how key questions regarding carbon dynamics can be addressed across diverse spatial and temporal scales from sub-meter areas over a few hours on a single gravel bar to thousands of square kilometers over millions of years across an entire large river network. The portion of the budget applying to the active channel(s) takes the form of ,in which Cs is organic carbon storage over time t. Inputs are surface and subsurface fluxes from uplands (CIupl) and the floodplain (CIfp), including fossil, soil, and biospheric organic carbon; surface and subsurface fluxes of carbon dioxide to the channel (CICO2); and net primary productivity in the channel (CINPP). Outputs occur via respiration within the channel and carbon dioxide emissions (COgas) and fluxes of dissolved and particulate organic carbon to the floodplain and downstream portions of the river network (COriver). The analogous budget for the floodplain portion of a river corridor is .

Latest Permian carbonate carbon isotope variability traces heterogeneous organic carbon accumulation and authigenic carbonate formation

Science.gov (United States)

Schobben, Martin; van de Velde, Sebastiaan; Gliwa, Jana; Leda, Lucyna; Korn, Dieter; Struck, Ulrich; Vinzenz Ullmann, Clemens; Hairapetian, Vachik; Ghaderi, Abbas; Korte, Christoph; Newton, Robert J.; Poulton, Simon W.; Wignall, Paul B.

2017-11-01

Bulk-carbonate carbon isotope ratios are a widely applied proxy for investigating the ancient biogeochemical carbon cycle. Temporal carbon isotope trends serve as a prime stratigraphic tool, with the inherent assumption that bulk micritic carbonate rock is a faithful geochemical recorder of the isotopic composition of seawater dissolved inorganic carbon. However, bulk-carbonate rock is also prone to incorporate diagenetic signals. The aim of the present study is to disentangle primary trends from diagenetic signals in carbon isotope records which traverse the Permian-Triassic boundary in the marine carbonate-bearing sequences of Iran and South China. By pooling newly produced and published carbon isotope data, we confirm that a global first-order trend towards depleted values exists. However, a large amount of scatter is superimposed on this geochemical record. In addition, we observe a temporal trend in the amplitude of this residual δ13C variability, which is reproducible for the two studied regions. We suggest that (sub-)sea-floor microbial communities and their control on calcite nucleation and ambient porewater dissolved inorganic carbon δ13C pose a viable mechanism to induce bulk-rock δ13C variability. Numerical model calculations highlight that early diagenetic carbonate rock stabilization and linked carbon isotope alteration can be controlled by organic matter supply and subsequent microbial remineralization. A major biotic decline among Late Permian bottom-dwelling organisms facilitated a spatial increase in heterogeneous organic carbon accumulation. Combined with low marine sulfate, this resulted in varying degrees of carbon isotope overprinting. A simulated time series suggests that a 50 % increase in the spatial scatter of organic carbon relative to the average, in addition to an imposed increase in the likelihood of sampling cements formed by microbial calcite nucleation to 1 out of 10 samples, is sufficient to induce the observed signal of carbon

Latest Permian carbonate carbon isotope variability traces heterogeneous organic carbon accumulation and authigenic carbonate formation

Directory of Open Access Journals (Sweden)

M. Schobben

2017-11-01

Full Text Available Bulk-carbonate carbon isotope ratios are a widely applied proxy for investigating the ancient biogeochemical carbon cycle. Temporal carbon isotope trends serve as a prime stratigraphic tool, with the inherent assumption that bulk micritic carbonate rock is a faithful geochemical recorder of the isotopic composition of seawater dissolved inorganic carbon. However, bulk-carbonate rock is also prone to incorporate diagenetic signals. The aim of the present study is to disentangle primary trends from diagenetic signals in carbon isotope records which traverse the Permian–Triassic boundary in the marine carbonate-bearing sequences of Iran and South China. By pooling newly produced and published carbon isotope data, we confirm that a global first-order trend towards depleted values exists. However, a large amount of scatter is superimposed on this geochemical record. In addition, we observe a temporal trend in the amplitude of this residual δ13C variability, which is reproducible for the two studied regions. We suggest that (sub-sea-floor microbial communities and their control on calcite nucleation and ambient porewater dissolved inorganic carbon δ13C pose a viable mechanism to induce bulk-rock δ13C variability. Numerical model calculations highlight that early diagenetic carbonate rock stabilization and linked carbon isotope alteration can be controlled by organic matter supply and subsequent microbial remineralization. A major biotic decline among Late Permian bottom-dwelling organisms facilitated a spatial increase in heterogeneous organic carbon accumulation. Combined with low marine sulfate, this resulted in varying degrees of carbon isotope overprinting. A simulated time series suggests that a 50 % increase in the spatial scatter of organic carbon relative to the average, in addition to an imposed increase in the likelihood of sampling cements formed by microbial calcite nucleation to 1 out of 10 samples, is sufficient to induce the

Physical and Human Controls on the Carbon Composition of Organic Matter in Tropical Rivers: An Integrated Analysis of Landscape Properties and River Isotopic Composition

Energy Technology Data Exchange (ETDEWEB)

Ballester, M. V.R.; Victoria, R. L.; Krusche, A. V. [Centro de Energia Nuclear na Agricultura, Universidade de Sao Paulo, Piracicaba (Brazil); Bernardes, M. [Universidade Federal Fluminense, Rio de Janeiro (Brazil); Neill, C.; Deegan, L. [Marine Biological Laboratory, Woods Hole, MA (United States); Richey, J. E. [University of Washington, Seatle, WA (United States)

2013-05-15

We applied an integrated analysis of landscape properties including soil properties, land cover and riverine isotopic composition. To evaluate physical and human controls on the carbon composition of organic matter in tropical rivers, we applied an integrated analysis of landscape properties including soil properties, land cover and riverine isotopic composition. Our main objective was to establish the relationship between basin attributes and forms, fluxes and composition of dissolved and particulate organic matter in river channels. A physical template was developed as a GIS-based comprehensive tool to support the understanding of the biogeochemistry of the surface waters of two tropical rivers: the Ji-Parana (Western Amazonia) and the Piracicaba (southeastern of Brazil). For each river we divided the basin into drainage units, organized according to river network morphology and degree of land use impact. Each sector corresponded to a sampling point where river isotopic composition was analysed. River sites and basin characteristics were calculated using datasets compiled as layers in ArcGis Geographical Information System and ERDAS-IMAGINE (Image Processing) software. Each delineated drainage area was individually characterized in terms of topography, soils, river network and land use. Carbon stable isotopic composition of dissolved organic matter (DOM) and particulate organic matter (POM) was determined at several sites along the main tributaries and small streams. The effects of land use on fluvial carbon composition were quantified by a linear regression analysis, relating basin cover and river isotopic composition. The results showed that relatively recent land cover changes have already had an impact on the composition of the riverine DOM and POM, indicating that, as in natural ecosystems, vegetation plays a key role in the composition of riverine organic matter in agricultural ecosystems. (author)

Extension of an assessment model of ship traffic exhaust emissions for particulate matter and carbon monoxide

Directory of Open Access Journals (Sweden)

J.-P. Jalkanen

2012-03-01

Full Text Available A method is presented for the evaluation of the exhaust emissions of marine traffic, based on the messages provided by the Automatic Identification System (AIS, which enable the positioning of ship emissions with a high spatial resolution (typically a few tens of metres. The model also takes into account the detailed technical data of each individual vessel. The previously developed model was applicable for evaluating the emissions of NO_x, SO_x and CO₂. This paper addresses a substantial extension of the modelling system, to allow also for the mass-based emissions of particulate matter (PM and carbon monoxide (CO. The presented Ship Traffic Emissions Assessment Model (STEAM2 allows for the influences of accurate travel routes and ship speed, engine load, fuel sulphur content, multiengine setups, abatement methods and waves. We address in particular the modeling of the influence on the emissions of both engine load and the sulphur content of the fuel. The presented methodology can be used to evaluate the total PM emissions, and those of organic carbon, elemental carbon, ash and hydrated sulphate. We have evaluated the performance of the extended model against available experimental data on engine power, fuel consumption and the composition-resolved emissions of PM. We have also compared the annually averaged emission values with those of the corresponding EMEP inventory, As example results, the geographical distributions of the emissions of PM and CO are presented for the marine regions of the Baltic Sea surrounding the Danish Straits.

Emission factors for CH{sub 4}, NO{sub x}, particulates and black carbon for domestic shipping in Norway, revision 1

Energy Technology Data Exchange (ETDEWEB)

Nielsen, Joergen Bremnes; Stenersen, Dag

2010-11-15

In this report new and updated emission factors for diesel, HFO and gas fuelled ships are presented and discussed as follows; NO{sub x} reduction factors from ships with NO{sub x} reduction measures; NO{sub x} emission factor from gas operated vessels; Methane emission factors for gas operated vessels; Updated emission factors for particulate emissions (PM) with a specific factor for the black carbon (BC) fraction of particulate emissions; A discussion on how low sulfur fuel will affect emissions of PM emissions and the BC fraction of PM is also included. (Author)

BILP-19-An Ultramicroporous Organic Network with Exceptional Carbon Dioxide Uptake.

Science.gov (United States)

Klumpen, Christoph; Radakovitsch, Florian; Jess, Andreas; Senker, Jürgen

2017-08-12

Porous benzimidazole-based polymers (BILPs) have proven to be promising for carbon dioxide capture and storage. The polarity of their chemical structure in combination with an inherent porosity allows for adsorbing large amounts of carbon dioxide in combination with high selectivities over unpolar guest molecules such as methane and nitrogen. For this reason, among purely organic polymers, BILPs contain some of the most effective networks to date. Nevertheless, they are still outperformed by competitive materials such as metal-organic frameworks (MOFs) or metal doped porous polymers. Here, we report the synthesis of BILP-19 and its exceptional carbon dioxide uptake of up to 6 mmol•g-1 at 273 K, making the network comparable to state-of-the-art materials. BILP-19 precipitates in a particulate structure with a strongly anisotropic growth into platelets, indicating a sheet-like structure for the network. It exhibits only a small microporous but a remarkable ultra-microporous surface area of 144 m2•g-1 and 1325 m2•g-1, respectively. We attribute the exceptional uptake of small guest molecules such as carbon dioxide and water to the distinct ultra-microporosity. Additionally, a pronounced hysteresis for both guests is observed, which in combination with the platelet character is probably caused by an expansion of the interparticle space, creating additional accessible ultra-microporous pore volume. For nitrogen and methane, this effect does not occur which explains their low affinity. In consequence, Henry selectivities of 123 for CO2/N2 at 298 K and 12 for CO2/CH4 at 273 K were determined. The network was carefully characterized with solid-state nuclear magnetic resonance (NMR) and infrared (IR) spectroscopy, thermal gravimetry (TG) and elemental analyses as well as physisorption experiments with Ar, N2, CO2, CH4 and water.

Variations in organic carbon fluxes from Long Island Sound to the Continental Shelf

Science.gov (United States)

Vlahos, P.; Whitney, M. M.

2017-12-01

Organic carbon balances for the Long Island Sound estuary over the years 2009-2012 are presented to assess the particulate and dissolved organic carbon contributions of the estuary to the adjacent shelf waters with respect to the Delaware and Chesapeake. Observations were coupled to a hydrodynamic model (ROMS) for both seasonal and annual estimates. During stratified summer periods, LIS was consistently a net exporter of OC to the continental shelf. LIS annual net carbon export however, varied with river flow. The heterotrophic or autotrophic nature of LIS also shifted seasonally and inter-annually. During the mass balance analysis period LIS ranged between net OC import from the continental shelf and heterotrophy in the lowest river flow year (2012) and net export of OC and autotrophy in the highest flow year (2011). Analysis suggests that LIS switches from net OC import to export when the annual river inputs exceed 19 km3 yr-1. Applying these thresholds to the annual river flow record suggests that net import occurred in 15% of the last 20 years and that LIS usually is a net exporter of OC (85%). Annually averaged LIS carbon export values based on river flow conditions over the last 20 yr are estimated at 56 ± 64 x 106 km3 yr-1. Analysis also suggests that LIS shifts from net heterotrophic to net autotrophic when annual river flow exceeds 26 km3 yr-1 (35% of the last 20 yr). Net heterotrophic conditions are most common, representing 65% of the last 20 yr.

Effect of biological activated carbon pre-treatment to control organic fouling in the microfiltration of biologically treated secondary effluent.

Science.gov (United States)

Pramanik, Biplob Kumar; Roddick, Felicity A; Fan, Linhua

2014-10-15

Biological activated carbon (BAC) filtration was investigated as a pre-treatment for reducing the organic fouling of a microfiltration membrane (0.1 μm polyvinylidene fluoride) in the treatment of a biologically treated secondary effluent (BTSE) from a municipal wastewater treatment plant. BAC treatment of the BTSE resulted in a marked improvement in permeate flux, which was attributed to the effective removal of organic foulants and particulates. Although the BAC removed significantly less dissolved organic carbon than the granular activated carbon (GAC) treatment which was used as a control for comparison, it led to a markedly greater flux. This was attributed to the effective removal of the very high molecular weight substances such as biopolymers by the BAC through biodegradation and adsorption of those molecules on the biofilm. Size exclusion chromatography showed the BAC treatment led to approximately 30% reduction in these substances, whereas the GAC did not greatly remove these molecules. The BAC treatment led to a greater reduction of loosely-attached and firmly-attached membrane surface foulant, and this was confirmed by attenuated total reflection-fourier transform infrared spectroscopy analysis. This study demonstrated the potential of BAC pre-treatment for reducing organic fouling and thus improving flux for the microfiltration of BTSE. Copyright © 2014 Elsevier Ltd. All rights reserved.

[Organic carbon and carbon mineralization characteristics in nature forestry soil].

Science.gov (United States)

Yang, Tian; Dai, Wei; An, Xiao-Juan; Pang, Huan; Zou, Jian-Mei; Zhang, Rui

2014-03-01

Through field investigation and indoor analysis, the organic carbon content and organic carbon mineralization characteristics of six kinds of natural forest soil were studied, including the pine forests, evergreen broad-leaved forest, deciduous broad-leaved forest, mixed needle leaf and Korean pine and Chinese pine forest. The results showed that the organic carbon content in the forest soil showed trends of gradual decrease with the increase of soil depth; Double exponential equation fitted well with the organic carbon mineralization process in natural forest soil, accurately reflecting the mineralization reaction characteristics of the natural forest soil. Natural forest soil in each layer had the same mineralization reaction trend, but different intensity. Among them, the reaction intensity in the 0-10 cm soil of the Korean pine forest was the highest, and the intensities of mineralization reaction in its lower layers were also significantly higher than those in the same layers of other natural forest soil; comparison of soil mineralization characteristics of the deciduous broad-leaved forest and coniferous and broad-leaved mixed forest found that the differences of litter species had a relatively strong impact on the active organic carbon content in soil, leading to different characteristics of mineralization reaction.

Organic electrochemistry and carbon electrodes

International Nuclear Information System (INIS)

Weinberg, N.

1983-01-01

Carbons are often used in organic electrosynthesis and are critical as anodes or cathodes to certain reactions. Too often the surface properties of carbons have been left uncharacterized in relation to the reaction; however, these physical and chemical properties of carbons are important to the nature of the products, and the selectivity. Examples presented include the Kolbe reaction, the oxidation of aromatics in presence of carboxylate salts, electrofluorination of organics, acetamidation of aromatics, the hydrodimerization of formaldehyde and the oxidation of carbon fibers. These reactions apparently involve special surface characteristics: structure, surface area, stabilized surface sites, and the presence or absence of significant ''oxide'' functionality

Black Carbon and Particulate Matter (PM2.5) Concentrations in New York City’s Subway Stations

Science.gov (United States)

2015-01-01

The New York City (NYC) subway is the main mode of transport for over 5 million passengers on an average weekday. Therefore, airborne pollutants in the subway stations could have a significant impact on commuters and subway workers. This study looked at black carbon (BC) and particulate matter (PM2.5) concentrations in selected subway stations in Manhattan. BC and PM2.5 levels were measured in real time using a Micro-Aethalometer and a PDR-1500 DataRAM, respectively. Simultaneous samples were also collected on quartz filters for organic and elemental carbon (OC/EC) analysis and on Teflon filters for gravimetric and trace element analysis. In the underground subway stations, mean real time BC concentrations ranged from 5 to 23 μg/m3, with 1 min average peaks >100 μg/m3, while real time PM2.5 levels ranged from 35 to 200 μg/m3. Mean EC levels ranged from 9 to 12.5 μg/m3. At street level on the same days, the mean BC and PM2.5 concentrations were below 3 and 10 μg/m3, respectively. This study shows that both BC soot and PM levels in NYC’s subways are considerably higher than ambient urban street levels and that further monitoring and investigation of BC and PM subway exposures are warranted. PMID:25409007

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%

Controlling exposure to DPM : diesel particulate filters vs. biodiesel

International Nuclear Information System (INIS)

Bugarski, A.D.; Shi, X.C.

2009-01-01

In order to comply with Mine Safety and Health Administration regulations, mining companies are required to reduce miners exposures to diesel particulate matter (DPM) to 160 μg/m 3 of total carbon. Diesel particulate filter (DPF) systems, disposable filter elements (DFEs), and diesel oxidation catalysts (DOCs) are among the most effective strategies and technologies for curtailing DPM at its source. Substituting diesel fuel with biodiesel blends is also considered to be a plausible solution by many underground mine operators. Studies were conducted at the National Institute for Occupational Safety and Health Diesel Laboratory at Lake Lynn Experimental Mine to evaluate various control technologies and strategies available to the underground mining industry to reduce exposure to DPM. The physical, chemical and toxicological properties of diesel aerosols (DPM) emitted by engines in an underground mine were also evaluated. The DPF and DFE systems were found to be highly effective in reducing total particulate and elemental carbon mass concentrations, total aerosol surface concentrations and, in most cases, concentrations of diesel aerosols in occupational settings such as underground mines. Soy methyl ester (SME) biodiesel fuels had the potential to reduce the mine air concentrations of total DPM, although the rate of reduction varied depending on engine operating conditions. The disadvantage of using biodiesel fuels was an increase in the fraction of particle-bound volatile organics and concentration of aerosols for light-load engine operating conditions.

Organic carbon organic matter and bulk density relationships in arid ...

African Journals Online (AJOL)

Soil organic matter (SOM) and soil organic carbon (SOC) constitute usually a small portion of soil, but they are one of the most important components of ecosystems. Bulk density (dB or BD) value is necessary to convert organic carbon (OC) content per unit area. Relationships between SOM, SOC and BD were established ...

Simply scan--optical methods for elemental carbon measurement in diesel exhaust particulate.

Science.gov (United States)

Forder, James A

2014-08-01

This article describes a performance assessment of three optical methods, a Magee Scientific OT21 Transmissometer, a Hach-Lange Microcolor II difference gloss meter, and a combination of an office scanner with Adobe Photoshop software. The optical methods measure filter staining as a proxy for elemental carbon in diesel exhaust particulate (DEP) exposure assessment and the suitability of each as a replacement for the existing Bosch meter optical method. Filters loaded with DEP were produced from air in a non-coal mine and the exhaust gases from a mobile crane. These were measured with each apparatus and then by combustion to obtain a reference elemental carbon value. The results from each apparatus were then plotted against both the Bosch number and reference elemental carbon values. The equations of the best fit lines for these plots were derived, and these gave functions for elemental carbon and Bosch number from the output of each new optical method. For each optical method, the range of DEP loadings which can be measured has been determined, and conversion equations for elemental carbon and Bosch number have been obtained. All three optical methods studied will effectively quantify blackness as a measure of elemental carbon. Of these the Magee Scientific OT21 transmissometer has the best performance. The Microcolor II and scanner/photoshop methods will in addition allow conversion to Bosch number which may be useful if historical Bosch data are available and functions for this are described. The scanner/photoshop method demonstrates a technique to obtain measurements of DEP exposure without the need to purchase specialized instrumentation. © The Author 2014. Published by Oxford University Press on behalf of the British Occupational Hygiene Society.

Barrow Black Carbon Source and Impact Study Final Campaign Report

Energy Technology Data Exchange (ETDEWEB)

Barrett, Tate [Baylor Univ., Waco, TX (United States)

2014-07-01

The goal of the Barrow Black Carbon Source and Impact (BBCSI) Study was to characterize the concentration and isotopic composition of carbonaceous atmospheric particulate matter (PM) at the Atmospheric Radiation Measurement site in Barrow, AK. The carbonaceous component was characterized via measurement of the organic and black carbon (OC and BC) components of the total PM. To facilitate complete characterization of the particulate matter, filter-based collections were used, including a medium volume PM2.5 sampler and a high volume PM10 sampler. Thirty-eight fine (PM2.5) and 49 coarse (PM10) particulate matter fractions were collected at weekly and bi-monthly intervals. The PM2.5 sampler operated with minimal maintenance during the 12 month campaign. The PM10 sampler used for the BBCSI used standard Tisch hi-vol motors which have a known lifetime of ~1 month under constant use; this necessitated monthly maintenance and it is suggested that the motors be upgraded to industrial blowers for future deployment in the Arctic. The BBCSI sampling campaign successfully collected and archived 87 ambient atmospheric particulate matter samples from Barrow, AK from July 2012 to June 2013. Preliminary analysis of the organic and black carbon concentrations has been completed. This campaign confirmed known trends of high BC lasting from the winter through to spring haze periods and low BC concentrations in the summer.

Metal/nonmetal diesel particulate matter rule

Energy Technology Data Exchange (ETDEWEB)

Tomko, D.M. [United States Dept. of Labor, Mine Safety and Health Administration, Pittsburgh, PA (United States). Safety and Health Technology Center; Stackpole, R.P. [United States Dept. of Labor, Mine Safety and Health Administration, Triadelphia, WV (United States). Approval and Certification Center; Findlay, C.D. [United States Dept. of Labor, Mine Safety and Health Administration, Arlington, VA (United States). Metal/Nonmetal Safety and Health; Pomroy, W.H. [United States Dept. of Labor, Mine Safety and Health Administration, Duluth, MN (United States). Metal/Nonmetal North Central District

2010-07-01

The American Mine Safety and Health Administration (MSHA) issued a health standard in January 2001 designed to reduce exposure to diesel particulate matter (DPM) in underground metal and nonmetal mines. The rule established an interim concentration limit for DPM of 400 {mu}g/m{sup 3} of total carbon, to be followed in 2004 by a final limit of 160 {mu}g/m{sup 3} of total carbon. The 2001 rule was challenged in federal court by various mining trade associations and mining companies. The rule was subsequently amended. This paper highlighted the major provisions of the 2006 final rule and summarized MSHAs current compliance sampling procedures. The concentration limit was changed to a permissible exposure limit and the sampling surrogate was changed from total carbon to elemental carbon. The MSHA published a new rule in 2006 which based the final limit on a miner's personal exposure rather than a concentration limit. The final limit was phased in using 3 steps over 2 years. This paper also discussed engineering controls and a recent MSHA report on organic carbon, elemental carbon and total carbon emissions from a diesel engine fueled with various blends of standard diesel and biodiesel. In May 2008, about two-thirds of all underground metal/nonmetal mines achieved and maintained compliance with the rule. 20 refs.

Next Generation Non-particulate Dry Nonwoven Pad for Chemical Warfare Agent Decontamination

Energy Technology Data Exchange (ETDEWEB)

Ramkumar, S S; Love, A; Sata, U R; Koester, C J; Smith, W J; Keating, G A; Hobbs, L; Cox, S B; Lagna, W M; Kendall, R J

2008-05-01

New, non-particulate decontamination materials promise to reduce both military and civilian casualties by enabling individuals to decontaminate themselves and their equipment within minutes of exposure to chemical warfare agents or other toxic materials. One of the most promising new materials has been developed using a needlepunching nonwoven process to construct a novel and non-particulate composite fabric of multiple layers, including an inner layer of activated carbon fabric, which is well-suited for the decontamination of both personnel and equipment. This paper describes the development of a composite nonwoven pad and compares efficacy test results for this pad with results from testing other decontamination systems. The efficacy of the dry nonwoven fabric pad was demonstrated specifically for decontamination of the chemical warfare blister agent bis(2-chloroethyl)sulfide (H or sulfur mustard). GC/MS results indicate that the composite fabric was capable of significantly reducing the vapor hazard from mustard liquid absorbed into the nonwoven dry fabric pad. The mustard adsorption efficiency of the nonwoven pad was significantly higher than particulate activated carbon (p=0.041) and was similar to the currently fielded US military M291 kit (p=0.952). The nonwoven pad has several advantages over other materials, especially its non-particulate, yet flexible, construction. This composite fabric was also shown to be chemically compatible with potential toxic and hazardous liquids, which span a range of hydrophilic and hydrophobic chemicals, including a concentrated acid, an organic solvent and a mild oxidant, bleach.

Long-Term Effect of Manure and Fertilizer on Soil Organic Carbon Pools in Dryland Farming in Northwest China

Science.gov (United States)

Liu, Enke; Yan, Changrong; Mei, Xurong; Zhang, Yanqing; Fan, Tinglu

2013-01-01

An understanding of the dynamics of soil organic carbon (SOC) as affected by farming practices is imperative for maintaining soil productivity and mitigating global warming. The objectives of this study were to investigate the effects of long-term fertilization on SOC and SOC fractions for the whole soil profile (0–100 cm) in northwest China. The study was initiated in 1979 in Gansu, China and included six treatments: unfertilized control (CK), nitrogen fertilizer (N), nitrogen and phosphorus (P) fertilizers (NP), straw plus N and P fertilizers (NP+S), farmyard manure (FYM), and farmyard manure plus N and P fertilizers (NP+FYM). Results showed that SOC concentration in the 0–20 cm soil layer increased with time except in the CK and N treatments. Long-term fertilization significantly influenced SOC concentrations and storage to 60 cm depth. Below 60 cm, SOC concentrations and storages were statistically not significant between all treatments. The concentration of SOC at different depths in 0–60 cm soil profile was higher under NP+FYM follow by under NP+S, compared to under CK. The SOC storage in 0–60 cm in NP+FYM, NP+S, FYM and NP treatments were increased by 41.3%, 32.9%, 28.1% and 17.9%, respectively, as compared to the CK treatment. Organic manure plus inorganic fertilizer application also increased labile soil organic carbon pools in 0–60 cm depth. The average concentration of particulate organic carbon (POC), dissolved organic carbon (DOC) and microbial biomass carbon (MBC) in organic manure plus inorganic fertilizer treatments (NP+S and NP+FYM) in 0–60 cm depth were increased by 64.9–91.9%, 42.5–56.9%, and 74.7–99.4%, respectively, over the CK treatment. The POC, MBC and DOC concentrations increased linearly with increasing SOC content. These results indicate that long-term additions of organic manure have the most beneficial effects in building carbon pools among the investigated types of fertilization. PMID:23437161

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.

Relationship between Organic Carbon Runoff to River and Land Cover

Science.gov (United States)

Kim, G. S.; Lee, S. G.; Lim, C. H.; Lee, W.; Yoo, S.; Kim, S. J.; Heo, S.; Lee, W. K.

2017-12-01

Carbon is an important unit in understanding the ecosystem and energy circulation. Each ecosystem, land, water, and atmosphere, is interconnected through the exchange of energy and organic carbon. In the rivers, primary producers utilize the organic carbon from the land. Understanding the organic carbon uptake into the river is important for understanding the mechanism of river ecosystems. The main organic carbon source of the river is land. However, it is difficult to observe the amount of organic carbon runoff to the river. Therefore, an indirect method should be used to estimate the amount of organic carbon runoff to the river. The organic carbon inflow is caused by the runoff of organic carbon dissolved in water or the inflow of organic carbon particles by soil loss. Therefore, the hydrological model was used to estimate organic carbon runoff through the flow of water. The land cover correlates with soil respiration, soil loss, and so on, and the organic carbon runoff coefficient will be estimated to the river by land cover. Using the organic carbon concentration from water quality data observed at each point in the river, we estimate the amount of organic carbon released from the land. The reason is that the runoff from the watershed converges into the rivers in the watershed, the watershed simulation is conducted based on the water quality data observation point. This defines a watershed that affects organic carbon observation sites. The flow rate of each watershed is calculated by the SWAT (Soil and Water Assessment Tool), and the total organic carbon runoff is calculated by using flow rate and organic carbon concentration. This is compared with the factors related to the amount of organic carbon such as land cover, soil loss, and soil organic carbon, and spatial analysis is carried out to estimate the organic carbon runoff coefficient per land cover.

Stable carbon isotope fractionation of organic cyst-forming dinoflagellates: Evaluating the potential for a CO2 proxy

Science.gov (United States)

Hoins, Mirja; Van de Waal, Dedmer B.; Eberlein, Tim; Reichart, Gert-Jan; Rost, Björn; Sluijs, Appy

2015-07-01

Over the past decades, significant progress has been made regarding the quantification and mechanistic understanding of stable carbon isotope fractionation (13C fractionation) in photosynthetic unicellular organisms in response to changes in the partial pressure of atmospheric CO2 (pCO2). However, hardly any data is available for organic cyst-forming dinoflagellates while this is an ecologically important group with a unique fossil record. We performed dilute batch experiments with four harmful dinoflagellate species known for their ability to form organic cysts: Alexandrium tamarense, Scrippsiella trochoidea, Gonyaulax spinifera and Protoceratium reticulatum. Cells were grown at a range of dissolved CO2 concentrations characterizing past, modern and projected future values (∼5-50 μmol L-1), representing atmospheric pCO2 of 180, 380, 800 and 1200 μatm. In all tested species, 13C fractionation depends on CO2 with a slope of up to 0.17‰ (μmol L)-1. Even more consistent correlations were found between 13C fractionation and the combined effects of particulate organic carbon quota (POC quota; pg C cell-1) and CO2. Carbon isotope fractionation as well as its response to CO2 is species-specific. These results may be interpreted as a first step towards a proxy for past pCO2 based on carbon isotope ratios of fossil organic dinoflagellate cysts. However, additional culture experiments focusing on environmental variables other than pCO2, physiological underpinning of the recorded response, testing for possible offsets in 13C values between cells and cysts, as well as field calibration studies are required to establish a reliable proxy.

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

Acidity controls on dissolved organic carbon mobility in organic soils

Czech Academy of Sciences Publication Activity Database

Evans, Ch. D.; Jones, T.; Burden, A.; Ostle, N.; Zielinski, P.; Cooper, M.; Peacock, M.; Clark, J.; Oulehle, Filip; Cooper, D.; Freeman, Ch.

2012-01-01

Roč. 18, č. 11 (2012), s. 3317-3331 ISSN 1354-1013 Institutional support: RVO:67179843 Keywords : acidity * dissolved organic carbon * organic soil * peat * podzol * soil carbon * sulphur Subject RIV: EH - Ecology, Behaviour Impact factor: 6.910, year: 2012

Characteristics of differently stabilised soil organic carbon fractions in relation to long-term fertilisation in Brown Earth of Northeast China.

Science.gov (United States)

Xu, Xiangru; Zhang, Wenju; Xu, Minggang; Li, Shuangyi; An, Tingting; Pei, Jiubo; Xiao, Jing; Xie, Hongtu; Wang, Jingkuan

2016-12-01

Long-term use of artificial fertiliser has a significant impact on soil organic carbon (SOC). We used physical-chemical fractionation methods to assess the impact of long-term (26years) fertilisation in a maize cropping system developed on Brown Earth in Northeast China. Plot treatments consisted of control (CK); nitrogen (N) fertiliser (N2); low-level organic manure combined with inorganic N and phosphorus (P) fertiliser (M1N1P1); medium-level organic manure combined with inorganic N fertiliser (M2N2); and high-level organic manure combined with inorganic N and P fertiliser (M4N2P1). Our objectives were to (1) determine the contents of and variations in the SOC fractions; (2) explore the relationship between total SOC and its fractions. In treatments involving organic manure (M1N1P1, M2N2, and M4N2P1), total SOC and physically protected microaggregate (μagg) and μagg occluded particulate organic carbon (iPOC) contents increased by 9.9-58.9%, 1.3-34.7%, 29.5-127.9% relative to control, respectively. But there no significant differences (P>0.05) were detected for the chemically, physically-chemically, and physically-biochemically protected fractions among the M1N1P1, M2N2, and M4N2P1 treatments. Regression analysis revealed that there was a linear positive correlation between SOC and the unprotected coarse particulate organic carbon (cPOC), physically protected μagg, and iPOC fractions (Pfractions responded negatively to SOC content. The highest rate of C accumulation among the SOC fractions occurred in the cPOC fraction, which accounted for as much as 32% of C accumulation as total SOC increased, suggesting that cPOC may be the most sensitive fraction to fertiliser application. We found that treatments had no effect on C levels in H-μsilt and NH-μsilt, indicating that the microaggregated silt C-fractions may have reached a steady state in terms of C saturation in the Brown Earth of Northeast China. Copyright © 2016 Elsevier B.V. All rights reserved.

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, R_rs(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, R_rs(λ_B/R_rs(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 R_rs(λ_B/R_rs(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. R_rs(443/R_rs(555 and POC vs. R_rs(490/R_rs(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

Organic carbon spiralling in stream ecosystems

Energy Technology Data Exchange (ETDEWEB)

Newbold, J D; Mulholland, P J; Elwood, J W; O' Neill, R V

1982-01-01

The term spiralling has been used to describe the combined processes of cycling and longitudinal transport in streams. As a measure or organic carbon spiralling, we introduced organic carbon turnover length, S, defined as the average or expected downstream distance travelled by a carbon atom between its entry or fixation in the stream and its oxidation. Using a simple model for organic carbon dynamics in a stream, we show that S is closely related to fisher and Likens' ecosystem efficiency. Unlike efficiency, however, S is independent of the length of the study reach, and values of S determined in streams of differing lengths can be compared. Using data from three different streams, we found the relationship between S and efficiency to agree closely with the model prediction. Hypotheses of stream functioning are discussed in the context of organic carbeon spiralling theory.

Fractionation and characterization of soil organic carbon during transition to organic farming

Science.gov (United States)

Abdelrahman, H.; Olk, D.; Cocozza, C.; Miano, T.

2012-04-01

The transition from conventional to organic farming is the most difficult period faced by organic growers as it could be characterized by unstable conditions, such as nutrient availability, production reductions, mineralization extents. As soil organic matter (SOM), specifically soil organic carbon (SOC), is known to play important roles in maintenance and improvement of many soil properties, it is important to define its changes during the transition period. Total SOC might not be the suitable tool to track the changes in organically based soil fertility within a 3- to 5-yr transition period. Labile fractions that are important for nutrient cycling and supply are likely to be controlled by management to a much greater extent than is total SOM. Two field experiments, in south of Italy, were established in 2009 to study the changes in SOC during transition to organic farming. Experiments included a cereal/leguminous rotation with triplicates treatments of permitted amendments (compost and fertilizers). Soils were sampled at the beginning of the project, and after each crop harvest in 2010 and 2011. A sequential fractionation procedure was used to separate different SOC-fractions: light fraction (LF), two size classes of particulate organic matter (POM), mobile humic acid (MHA) and Ca++ bound humic acid (CaHA). Isolated fractions were quantified and analyzed for their content of C, N, carbohydrates and amino compounds fingerprints. The obtained results showed that compost application contributed to significantly higher quantities of LF, POM and MHA than did fertilizers application. Carbohydrates content decreased in LF while increased noticeably in POM and slightly in MHA fractions, which indicates that decomposing materials are converted, within the time span of humification, from young fractions into more mature fractions. Amino compounds were found to provide up to 40% of total soil N with a major contribution of the humified fractions, MHA and CaHA. The utilized

Carbon isotope ratios of organic matter in Bering Sea settling particles. Extremely high remineralization of organic carbon derived from diatoms

International Nuclear Information System (INIS)

Yasuda, Saki; Akagi, Tasuku; Naraoka, Hiroshi; Kitajima, Fumio; Takahashi, Kozo

2016-01-01

The carbon isotope ratios of organic carbon in settling particles collected in the highly-diatom-productive Bering Sea were determined. Wet decomposition was employed to oxidize relatively fresh organic matter. The amount of unoxidised organic carbon in the residue following wet decomposition was negligible. The δ 13 C of organic carbon in the settling particles showed a clear relationship against SiO 2 /CaCO 3 ratio of settling particles: approximately -26‰ and -19‰ at lower and higher SiO 2 /CaCO 3 ratios, respectively. The δ 13 C values were largely interpreted in terms of mixing of two major plankton sources. Both δ 13 C and compositional data can be explained consistently only by assuming that more than 98% of diatomaceous organic matter decays and that organic matter derived from carbonate-shelled plankton may remain much less remineralized. A greater amount of diatom-derived organic matter is discovered to be trapped with the increase of SiO 2 /CaCO 3 ratio of the settling particles. The ratio of organic carbon to inorganic carbon, known as the rain ratio, therefore, tends to increase proportionally with the SiO 2 /CaCO 3 ratio under an extremely diatom-productive condition. (author)

INVESTIGATION OF VERTICAL DISTRIUBTION AND MORPHO- LOGY OF INDIGENOUS ORGANIC MATTER AT SLEEPING BEAR SITE, MICHIGAN

Science.gov (United States)

This study evaluates the nature and origin of particulate organic carbon and organic coatings on aquifer sands upgradient from a fuel spill site near the Sleeping Bear Dunes National Lakeshore in Michigan. The distribution of carbon was found to be highly complex due to the occur...

Mobility of organic carbon from incineration residues

International Nuclear Information System (INIS)

Ecke, Holger; Svensson, Malin

2008-01-01

Dissolved organic carbon (DOC) may affect the transport of pollutants from incineration residues when landfilled or used in geotechnical construction. The leaching of dissolved organic carbon (DOC) from municipal solid waste incineration (MSWI) bottom ash and air pollution control residue (APC) from the incineration of waste wood was investigated. Factors affecting the mobility of DOC were studied in a reduced 2 6-1 experimental design. Controlled factors were treatment with ultrasonic radiation, full carbonation (addition of CO 2 until the pH was stable for 2.5 h), liquid-to-solid (L/S) ratio, pH, leaching temperature and time. Full carbonation, pH and the L/S ratio were the main factors controlling the mobility of DOC in the bottom ash. Approximately 60 weight-% of the total organic carbon (TOC) in the bottom ash was available for leaching in aqueous solutions. The L/S ratio and pH mainly controlled the mobilization of DOC from the APC residue. About 93 weight-% of TOC in the APC residue was, however, not mobilized at all, which might be due to a high content of elemental carbon. Using the European standard EN 13 137 for determination of total organic carbon (TOC) in MSWI residues is inappropriate. The results might be biased due to elemental carbon. It is recommended to develop a TOC method distinguishing between organic and elemental carbon

State-Space Estimation of Soil Organic Carbon Stock

Science.gov (United States)

Ogunwole, Joshua O.; Timm, Luis C.; Obidike-Ugwu, Evelyn O.; Gabriels, Donald M.

2014-04-01

Understanding soil spatial variability and identifying soil parameters most determinant to soil organic carbon stock is pivotal to precision in ecological modelling, prediction, estimation and management of soil within a landscape. This study investigates and describes field soil variability and its structural pattern for agricultural management decisions. The main aim was to relate variation in soil organic carbon stock to soil properties and to estimate soil organic carbon stock from the soil properties. A transect sampling of 100 points at 3 m intervals was carried out. Soils were sampled and analyzed for soil organic carbon and other selected soil properties along with determination of dry aggregate and water-stable aggregate fractions. Principal component analysis, geostatistics, and state-space analysis were conducted on the analyzed soil properties. The first three principal components explained 53.2% of the total variation; Principal Component 1 was dominated by soil exchange complex and dry sieved macroaggregates clusters. Exponential semivariogram model described the structure of soil organic carbon stock with a strong dependence indicating that soil organic carbon values were correlated up to 10.8m.Neighbouring values of soil organic carbon stock, all waterstable aggregate fractions, and dithionite and pyrophosphate iron gave reliable estimate of soil organic carbon stock by state-space.

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

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 %

Deposition and benthic mineralization of organic carbon: A seasonal study from Faroe Islands

Science.gov (United States)

á Norði, Gunnvør; Glud, Ronnie N.; Simonsen, Knud; Gaard, Eilif

2018-01-01

Seasonal variations in sedimentation and benthic mineralization of organic carbon (OC) were investigated in a Faroese fjord. Deposited particulate organic carbon (POC) was mainly of marine origin, with terrestrial material only accounting for rates were associated to the spring bloom. The dynamics in the benthic solute exchange were governed by stratification that isolated the bottom water during summer and intensified sediment resuspension during winter. The POC export from the euphotic zone could not sustain the benthic mineralization rate (10.8 mol C m- 2 yr- 1) and the calculated burial rate (9.8 mol C m- 2 yr- 1) of organic material in the central basin. This indicated considerable focusing of material in the central part of the fjord. This was supported by the fact that the measured benthic mineralization rate - in contrast to most investigations - actually increased with increasing water depth. In August, when mineralization was at its maximum, the dissolved inorganic carbon (DIC) release from the sediment increased by 2.2 mmol m- 2 d- 1 for every m increase in water depth at 30-60 m depth. Due to sediment focusing, the OC burial in the deepest part of the fjord was 9.8 mol C m- 2 yr- 1. This was 2.4 times higher than the average OC burial in the fjord, estimated from the total sedimentation, and benthic mineralization accounting for the water depth related changes in activity. The study in Kaldbaksfjørður underscore that fjords are important sites for long time OC burial, but emphasize the need for accounting for spatial variations when extrapolating results from a single or few stations to the scale of the entire fjord.

Organic and Inorganic Matter in Louisiana Coastal Waters: Vermilion, Atchafalaya, Terrebonne, Barataria, and Mississippi Regions.

Science.gov (United States)

Chromophoric dissolved organic matter (CDOM) spectral absorption, dissolved organic carbon (DOC) concentration, and the particulate fraction of inorganic (PIM) and organic matter (POM) were measured in Louisiana coastal waters at Vermilion, Atchafalaya, Terrebonne, Barataria, and...

Trophic state changes can affect the importance of methane-derived carbon in aquatic food webs

NARCIS (Netherlands)

Schilder, Jos; Van Hardenbroek, M.; Bodelier, P.L.E.; Kirilova, Emiliya P.; Leuenberger, Markus; Lotter, A.F.; Heiri, O.

2017-01-01

Methane-derived carbon, incorporated by methane-oxidizing bacteria, has been identified as a significant source of carbon in food webs of many lakes. By measuring the stable carbon isotopic composition (δ13C values) of particulate organic matter, Chironomidae and Daphnia spp. and their resting eggs

Land Use and Climate Alter Carbon Dynamics in Watersheds of Chesapeake Bay

Science.gov (United States)

Kaushal, S.; Duan, S.; Grese, M.; Pennino, M. J.; Belt, K. T.; Findlay, S.; Groffman, P. M.; Mayer, P. M.; Murthy, S.; Blomquist, J.

2011-12-01

There have been long-term changes in the quantity of organic carbon in streams and rivers globally. Shifts in the quality of organic carbon due to environmental changes may also impact downstream ecosystem metabolism and fate and transport of contaminants. We investigated long-term impacts of land use and hydrologic variability on organic carbon transport in watersheds of the Baltimore Long-Term Ecological Research (LTER) site and large rivers of the Chesapeake Bay. In small and medium-sized watersheds of the Baltimore LTER site, urban land use increased organic carbon concentrations in streams several-fold compared to forest and agricultural watersheds. Enzymatic activities of stream microbes were significantly altered across watershed land use during a record wet year. During the wet year, short-term bioassays showed that bioavailable dissolved organic carbon varied seasonally, but comprised a substantial proportion of the dissolved organic carbon pool. Similarly, measurements of biochemical oxygen demand across hydrologic variability suggest that reactive organic carbon export from small and medium-sized urban watersheds during storms can be substantial. At a larger regional scale, major tributaries such as the Potomac, Susquehanna, Patuxent, and Choptank rivers also showed similar variability as smaller watersheds in quantity and quality of organic carbon based on land use and climate. There were distinct isotopic values of d13C of particulate organic matter and fluorescence excitation emission matrices for rivers influenced by different land uses. Stable isotopic values of d13C of particulate organic matter and fluorescence excitation emission matrices showed marked seasonal changes in organic matter quality during spring floods in the Potomac River at Washington D.C. Across watershed size, there appeared to be differences in seasonal cycles of organic carbon quality and this may have been based on the degree of hydrologic connectivity between watersheds and

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.

Isotopic evidence for the influence of typhoons and submarine canyons on the sourcing and transport behavior of biospheric organic carbon to the deep sea

Science.gov (United States)

Zheng, Li-Wei; Ding, Xiaodong; Liu, James T.; Li, Dawei; Lee, Tsung-Yu; Zheng, Xufeng; Zheng, Zhenzhen; Xu, Min Nina; Dai, Minhan; Kao, Shuh-Ji

2017-05-01

Export of biospheric organic carbon from land masses to the ocean plays an important role in regulating the global carbon cycle. High-relief islands in the western Pacific are hotspots for such land-to-ocean carbon transport due to frequent floods and active tectonics. Submarine canyon systems serve as a major conduit to convey terrestrial organics into the deep sea, particularly during episodic floods, though the nature of ephemeral sediment transportation through such canyons remains unclear. In this study, we deployed a sediment trap in southwestern Taiwan's Gaoping submarine canyon during summer 2008, during which Typhoon Kalmaegi impacted the study area. We investigated sources of particulate organic carbon and quantified the content of fossil organic carbon (OCf) and biospheric non-fossil carbon (OCnf) during typhoon and non-typhoon periods, based on relations between total organic carbon (TOC), isotopic composition (δ13 C, 14C), and nitrogen to carbon ratios (N/C) of newly and previously reported source materials. During typhoons, flooding connected terrestrial rivers to the submarine canyon. Fresh plant debris was not found in the trap except in the hyperpycnal layer, suggesting that only hyperpycnal flow is capable of entraining plant debris, while segregation had occurred during non-hyperpycnal periods. The OCnf components in typhoon flood and trapped samples were likely sourced from aged organics buried in ancient landslides. During non-typhoon periods, the canyon is more connected to the shelf, where waves and tides cause reworking, thus allowing abiotic and biotic processes to generate isotopically uniform and similarly aged OCnf for transport into the canyon. Therefore, extreme events coupled with the submarine canyon system created an efficient method for deep-sea burial of freshly produced organic-rich material. Our results shed light on the ephemeral transport of organics within a submarine canyon system on an active tectonic margin.

Amino sugars in suspended particulate matter from the Bay of Bengal during the summer monsoon of 2001

Digital Repository Service at National Institute of Oceanography (India)

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

and pseudopeptidoglycan (Brock et al 1994). AS are also important con- stituents of many biopolymers such as polysac- charides, glycoproteins and glycolipids (Sharon 1965). Moreover, chitin, a polymer of amino sugar, N-acetyl glucosamine (Muzzarelli 1977; Benner.../F glass fibre filters (0.7?m pore size) for the analysis of particu- late organic carbon (POC), particulate nitrogen (PN) and amino sugars (AS) concentration and composition. 2.3 Analysis of samples The SPM samples were de-carbonated overnight using fuming...

Physical factors controlling carbon cycling dynamics in blackwater river-dominated and particle dominated estuaries

Science.gov (United States)

Arellano, A. R.; Bianchi, T. S.; Osburn, C. L.; D'Sa, E. J.; Oviedo-Vargas, D.; Ward, N. D.; Joshi, I.

2017-12-01

While most blue carbon habitat (wetlands, seagrass beds and mangroves) research has focused on carbon burial/stocks and habitat fragmentation of these communities, few studies have examined physical factors that control exports and losses of blue carbon sources of organic matter (OM) to adjacent coastal waters. Here, we report on spatiotemporal changes in the composition and concentration of dissolved organic carbon (DOC), particulate organic carbon (POC), particulate nitrogen, pCO2, δ13C-DOC, δ13C-POC, δ13C-CO2, dissolved lignin-phenols (dΣ8), particulate lignin-phenols (pΣ8) and carbon normalized dissolved and particulate lignin phenol yields (dΛ8 and pΛ8) in surface waters of the Apalachicola and Barataria bays in the Gulf of Mexico. Discriminant analysis described spatial variability along canonical axis I (24.4%) while temporal variability was explained by canonical axis II (23.2%). Apalachicola Bay was low in POC concentration and characterized by high values for pCO2, DOC, C:N, dΣ8 and (Ad:Al)V. The latter three parameters indicated a clear terrestrial source of OM at Apalachicola Bay reflecting the importance of riverine DOM inputs in this system. In contrast, Barataria Bay was characterized by high values for POC, C:V, S:V, and δ13C-POC, indicating blue-carbon sources due to a lack of direct river inputs and high prevalence of wetlands, some recently submerged. Extreme weather, such as intense precipitation events in Apalachicola Bay and enhanced northerly winds in Barataria Bay were characterized by δ13C-CO2, dΛ8, C:V (Barataria), and C:N (Apalachicola). Results indicate that such physical factors can exert strong control on OM sources and sinks across the gradient of coastal wetlands and shelf waters and lead to enhanced transfer and degradation of wetland-derived blue carbon in coastal waters.

Inferring absorbing organic carbon content from AERONET data

Science.gov (United States)

Arola, A.; Schuster, G.; Myhre, G.; Kazadzis, S.; Dey, S.; Tripathi, S. N.

2011-01-01

Black carbon, light-absorbing organic carbon (often called "brown carbon") and mineral dust are the major light-absorbing aerosols. Currently the sources and formation of brown carbon aerosol in particular are not well understood. In this study we estimated the amount of light-absorbing organic carbon and black carbon from AERONET measurements. We find that the columnar absorbing organic carbon (brown carbon) levels in biomass burning regions of South America and Africa are relatively high (about 15-20 mg m-2 during biomass burning season), while the concentrations are significantly lower in urban areas in US and Europe. However, we estimated significant absorbing organic carbon amounts from the data of megacities of newly industrialized countries, particularly in India and China, showing also clear seasonality with peak values up to 30-35 mg m-2 during the coldest season, likely caused by the coal and biofuel burning used for heating. We also compared our retrievals with the modeled organic carbon by the global Oslo CTM for several sites. Model values are higher in biomass burning regions than AERONET-based retrievals, while the opposite is true in urban areas in India and China.

Influence of land use changes on soil carbon stock and soil carbon erosion in a Mediterranean catchment

Energy Technology Data Exchange (ETDEWEB)

Boix-Fayos, C.; Martinez-Mena, M.; Vente, J. de; Albaladejo, J.

2009-07-01

The effect of changing land uses on the organic soil carbon (C) stock and the soil C transported by water erosion and buried in depositions wedges behring check-dams was estimated in a Mediterranean catchment in SE Spin. the 57% decrease in agricultural areas and 1.5-fold increase of the total forest cover between 1956 and 1997 induced an accumulation rate of total organic carbon (TOC) in the soil of 10.73 g m{sup -}2 yr{sup -}1. The mineral-associated organic carbon (MOC) represented the 70% of the soil carbon pool, the particulate organic carbon (POC) represented a 30% of the soil carbon pool. The average sediments/soil enrichment ratio at the sub catchment scale (8-125 ha) was 0.59{+-}0.43 g kg{sup -}1. Eroded soil C accounted for between 2% to 78% of the soil c stock in the first 5 cm of the soil in the subcatchments. the C erosion rate varied between 0.008 and 0.2 t ha{sup -}1 yr{sup -}1. (Author) 20 refs.

Influence of land use changes on soil carbon stock and soil carbon erosion in a Mediterranean catchment

International Nuclear Information System (INIS)

Boix-Fayos, C.; Martinez-Mena, M.; Vente, J. de; Albaladejo, J.

2009-01-01

The effect of changing land uses on the organic soil carbon (C) stock and the soil C transported by water erosion and buried in depositions wedges behring check-dams was estimated in a Mediterranean catchment in SE Spin. the 57% decrease in agricultural areas and 1.5-fold increase of the total forest cover between 1956 and 1997 induced an accumulation rate of total organic carbon (TOC) in the soil of 10.73 g m - 2 yr - 1. The mineral-associated organic carbon (MOC) represented the 70% of the soil carbon pool, the particulate organic carbon (POC) represented a 30% of the soil carbon pool. The average sediments/soil enrichment ratio at the sub catchment scale (8-125 ha) was 0.59±0.43 g kg - 1. Eroded soil C accounted for between 2% to 78% of the soil c stock in the first 5 cm of the soil in the subcatchments. the C erosion rate varied between 0.008 and 0.2 t ha - 1 yr - 1. (Author) 20 refs.

Model predictions of long-lived storage of organic carbon in river deposits

Directory of Open Access Journals (Sweden)

M. A. Torres

2017-11-01

Full Text Available The mass of carbon stored as organic matter in terrestrial systems is sufficiently large to play an important role in the global biogeochemical cycling of CO2 and O2. Field measurements of radiocarbon-depleted particulate organic carbon (POC in rivers suggest that terrestrial organic matter persists in surface environments over millennial (or greater timescales, but the exact mechanisms behind these long storage times remain poorly understood. To address this knowledge gap, we developed a numerical model for the radiocarbon content of riverine POC that accounts for both the duration of sediment storage in river deposits and the effects of POC cycling. We specifically target rivers because sediment transport influences the maximum amount of time organic matter can persist in the terrestrial realm and river catchment areas are large relative to the spatial scale of variability in biogeochemical processes.Our results show that rivers preferentially erode young deposits, which, at steady state, requires that the oldest river deposits are stored for longer than expected for a well-mixed sedimentary reservoir. This geometric relationship can be described by an exponentially tempered power-law distribution of sediment storage durations, which allows for significant aging of biospheric POC. While OC cycling partially limits the effects of sediment storage, the consistency between our model predictions and a compilation of field data highlights the important role of storage in setting the radiocarbon content of riverine POC. The results of this study imply that the controls on the terrestrial OC cycle are not limited to the factors that affect rates of primary productivity and respiration but also include the dynamics of terrestrial sedimentary systems.

Citrus stand ages regulate the fraction alteration of soil organic carbon under a citrus/Stropharua rugodo-annulata intercropping system in the Three Gorges Reservoir area, China.

Science.gov (United States)

Zhang, Yang; Ni, Jiupai; Yang, John; Zhang, Tong; Xie, Deti

2017-08-01

Soil carbon fractionation is a valuable indicator in assessing stabilization of soil organic matter and soil quality. However, limited studies have addressed how different vegetation stand ages under intercropping agroforestry systems, could affect organic carbon (OC) accumulation in bulk soil and its physical fractions. A field study thus investigated the impact of citrus plantation age (15-, 25-, and 45-year citrus) on the bulk soil organic carbon (SOC) and SOC fractions and yields of Stropharia rugoso-annulata (SRA) in the Three Gorges Reservoir area, Chongqing, China. Results indicated that the intercropping practice of SRA with citrus significantly increased the SOC by 57.4-61.6% in topsoil (0-10 cm) and by 24.8-39.9% in subsoil (10-30 cm). With a significantly higher enhancement under the 25-year citrus stand than the other two stands, all these citrus stands of three ages also resulted in a significant increase of free particulate OC (fPOC, 60.1-62.4% in topsoil and 34.8-46.7% in subsoil), intra-micro aggregate particulate OC (iPOC, 167.6-206.0% in topsoil and 2.77-61.09% in subsoil), and mineral-associated OC (MOC, 43.6-46.5% in topsoil and 26.0-51.5% in subsoil). However, there were no significant differences in yields of SRA under three citrus stands. Our results demonstrated that citrus stand ages did play an important role in soil carbon sequestration and fractionation under a citrus/SRA intercropping system, which could therefore provide a sustainable agroforestry system to enhance concurrently the SOC accumulation while mitigating farmland CO 2 emission.

Predicting ambient aerosol Thermal Optical Reflectance (TOR) measurements from infrared spectra: organic carbon

Science.gov (United States)

Dillner, A. M.; Takahama, S.

2014-11-01

Organic carbon (OC) can constitute 50% or more of the mass of atmospheric particulate matter. Typically, the organic carbon concentration is measured using thermal methods such as Thermal-Optical Reflectance (TOR) from quartz fiber filters. Here, methods are presented whereby Fourier Transform Infrared (FT-IR) absorbance spectra from polytetrafluoroethylene (PTFE or Teflon) filters are used to accurately predict TOR OC. Transmittance FT-IR analysis is rapid, inexpensive, and non-destructive to the PTFE filters. To develop and test the method, FT-IR absorbance spectra are obtained from 794 samples from seven Interagency Monitoring of PROtected Visual Environment (IMPROVE) sites sampled during 2011. Partial least squares regression is used to calibrate sample FT-IR absorbance spectra to artifact-corrected TOR OC. The FTIR spectra are divided into calibration and test sets by sampling site and date which leads to precise and accurate OC predictions by FT-IR as indicated by high coefficient of determination (R2; 0.96), low bias (0.02 μg m-3, all μg m-3 values based on the nominal IMPROVE sample volume of 32.8 m-3), low error (0.08 μg m-3) and low normalized error (11%). These performance metrics can be achieved with various degrees of spectral pretreatment (e.g., including or excluding substrate contributions to the absorbances) and are comparable in precision and accuracy to collocated TOR measurements. FT-IR spectra are also divided into calibration and test sets by OC mass and by OM / OC which reflects the organic composition of the particulate matter and is obtained from organic functional group composition; this division also leads to precise and accurate OC predictions. Low OC concentrations have higher bias and normalized error due to TOR analytical errors and artifact correction errors, not due to the range of OC mass of the samples in the calibration set. However, samples with low OC mass can be used to predict samples with high OC mass indicating that the

Carbon fuel particles used in direct carbon conversion fuel cells

Science.gov (United States)

Cooper, John F.; Cherepy, Nerine

2012-10-09

A system for preparing particulate carbon fuel and using the particulate carbon fuel in a fuel cell. Carbon particles are finely divided. The finely dividing carbon particles are introduced into the fuel cell. A gas containing oxygen is introduced into the fuel cell. The finely divided carbon particles are exposed to carbonate salts, or to molten NaOH or KOH or LiOH or mixtures of NaOH or KOH or LiOH, or to mixed hydroxides, or to alkali and alkaline earth nitrates.

Carbon Fuel Particles Used in Direct Carbon Conversion Fuel Cells

Science.gov (United States)

Cooper, John F.; Cherepy, Nerine

2008-10-21

A system for preparing particulate carbon fuel and using the particulate carbon fuel in a fuel cell. Carbon particles are finely divided. The finely dividing carbon particles are introduced into the fuel cell. A gas containing oxygen is introduced into the fuel cell. The finely divided carbon particles are exposed to carbonate salts, or to molten NaOH or KOH or LiOH or mixtures of NaOH or KOH or LiOH, or to mixed hydroxides, or to alkali and alkaline earth nitrates.

A method for smoke marker measurements and its potential application for determining the contribution of biomass burning from wildfires and prescribed fires to ambient PM2.5 organic carbon

Science.gov (United States)

A. P. Sullivan; A. S. Holden; L. A. Patterson; G. R. McMeeking; S. M. Kreidenweis; W. C. Malm; W. M. Hao; C. E. Wold; J. L. Collett

2008-01-01

Biomass burning is an important source of particulate organic carbon (OC) in the atmosphere. Quantifying this contribution in time and space requires a means of routinely apportioning contributions of smoke from biomass burning to OC. Smoke marker (for example, levoglucosan) measurements provide the most common approach for making this determination. A lack of source...

Organic nitrogen and carbon in atmospheric dry and wet depositions in the southern East China Sea: its implication for new production in coastal region

Science.gov (United States)

Chen, H. Y.; Yeh, J. X.; Lin, C. T.

2016-02-01

We collected 11 sets of size-segregated particulate aerosol (include coarse and fine particles) and 53 rain samples from January to December 2014 at a coastal city (Keelung) on the southern East China Sea. Here we present measurements of water-soluble inorganic/organic nitrogen and carbon (WSIN/WSON and WSIC/WSOC, respectively) in aerosol samples and dissolved inorganic/organic nitrogen and carbon (DIN/DON and DIC/DOC, respectively) in rain samples. In addition, 4-d back trajectories of air masses arriving daily at the sampling site were calculated to determine the potential aerosol source regions. The concentrations of water-soluble species in particulate aerosols were relatively high in March (WSON: 223±48 nmol m-3; WSOC: 203±51 nmol m-3) and dissolved species in rain samples were high in December (DON: 157±69 μM; DOC: 294±168 μM), which occur frequently during the spring and winter. The monsoon system of East Asia play a key role on the atmospheric composition of nitrogen and carbon, with higher loadings in northerly (winter to spring) than southerly (summer to autumn) monsoon periods, owing to strong emissions from the East Asian continent. Our results indicate that biomass burning and dust events yielded the largest concentrations of ON and OC not only on particulate aerosols but also in precipitations. For aerosols, the amounts of WSON and WSOC accounted for 42±8% and 80±7% of the water-soluble total nitrogen (WSTN) and carbon (WSTC), respectively. Additionally, the concentrations of DON and DOC accounted for 40±5% and 75±3% of total dissolved nitrogen (TDN) and carbon (TDC), respectively, for precipitations. By using dry and wet deposition flux estimations, we estimated that the fluxes of WSTN/TDN and WSTC/TDC were 47.1±24.4 / 266±20 mmol m-2 yr-1 and 23±9 / 153±3 mmol m-2 yr-1, respectively. These results suggest that atmospheric deposition contributed approximately 25-34% of the annual biological new production in the southern East China Sea.

Source areas and chemical composition of fine particulate matter in the Pearl River Delta region of China

Science.gov (United States)

Hagler, G. S. W.; Bergin, M. H.; Salmon, L. G.; Yu, J. Z.; Wan, E. C. H.; Zheng, M.; Zeng, L. M.; Kiang, C. S.; Zhang, Y. H.; Lau, A. K. H.; Schauer, J. J.

Fine particulate matter (PM 2.5) was measured for 4 months during 2002-2003 at seven sites located in the rapidly developing Pearl River Delta region of China, an area encompassing the major cities of Hong Kong, Shenzhen and Guangzhou. The 4-month average fine particulate matter concentration ranged from 37 to 71 μg m -3 in Guangdong province and from 29 to 34 μg m -3 in Hong Kong. Main constituents of fine particulate mass were organic compounds (24-35% by mass) and sulfate (21-32%). With sampling sites strategically located to monitor the regional air shed patterns and urban areas, specific source-related fine particulate species (sulfate, organic mass, elemental carbon, potassium and lead) and daily surface winds were analyzed to estimate influential source locations. The impact of transport was investigated by categorizing 13 (of 20 total) sampling days by prevailing wind direction (southerly, northerly or low wind-speed mixed flow). The vicinity of Guangzhou is determined to be a major source area influencing regional concentrations of PM 2.5, with levels observed to increase by 18-34 μg m -3 (accounting for 46-56% of resulting particulate levels) at sites immediately downwind of Guangzhou. The area near Guangzhou is also observed to heavily impact downwind concentrations of lead. Potassium levels, related to biomass burning, appear to be controlled by sources in the northern part of the Pearl River Delta, near rural Conghua and urban Guangzhou. Guangzhou appears to contribute 5-6 μg m -3 of sulfate to downwind locations. Guangzhou also stands out as a significant regional source of organic mass (OM), adding 8.5-14.5 μg m -3 to downwind concentrations. Elemental carbon is observed to be strongly influenced by local sources, with highest levels found in urban regions. In addition, it appears that sources outside of the Pearl River Delta contribute a significant fraction of overall fine particulate matter in Hong Kong and Guangdong province. This is evident

Bacterial uptake of photosynthetic carbon from freshwater phytoplankton

International Nuclear Information System (INIS)

Coveney, M.F.

1982-01-01

Microheterotrophic uptake of algal extracellular products was studied in two eutrophic lakes in southern Sweden. Size fractionation was used in H 14 CO 3 uptake experiments to measure 14 C fixation in total particulate, small particulate and dissolved organic fractions. Carbon fixed in algal photosynthesis was recovered as dissolved and small particulate 14 C, representing excretion and bacterial uptake of algal products. Estimated gross extracellular release was low in these eutrophic systems, 1 to 7% of total 14 C uptake per m 2 lake surface. From 28 to 80 % of 14 C released was recovered in the small particulate fraction after ca. 4h incubation.This percentage was uniform within each depth profile, but varied directly with in situ water temperature. Laboratory time-series incubations indicated steady state for the pool of algal extracellular products on one occasion, while increasing pool size was indicated in the remaining two experiments. Uptake of photosynthetic carbon to small particles in situ was 32 to 95% of estimted heterotrophic bacterial production (as dark 14 CO 2 uptake) on four occasions. While excretion apparently was not an important loss of cabon for phytoplankton, it may have represented an important carbon source for planktonic bacteria. (author)

Inferring absorbing organic carbon content from AERONET data

Directory of Open Access Journals (Sweden)

A. Arola

2011-01-01

Full Text Available Black carbon, light-absorbing organic carbon (often called "brown carbon" and mineral dust are the major light-absorbing aerosols. Currently the sources and formation of brown carbon aerosol in particular are not well understood. In this study we estimated the amount of light–absorbing organic carbon and black carbon from AERONET measurements. We find that the columnar absorbing organic carbon (brown carbon levels in biomass burning regions of South America and Africa are relatively high (about 15–20 mg m⁻² during biomass burning season, while the concentrations are significantly lower in urban areas in US and Europe. However, we estimated significant absorbing organic carbon amounts from the data of megacities of newly industrialized countries, particularly in India and China, showing also clear seasonality with peak values up to 30–35 mg m⁻² during the coldest season, likely caused by the coal and biofuel burning used for heating. We also compared our retrievals with the modeled organic carbon by the global Oslo CTM for several sites. Model values are higher in biomass burning regions than AERONET-based retrievals, while the opposite is true in urban areas in India and China.

Inter-annual Variability in Global Suspended Particulate Inorganic Carbon Inventory Using Space-based Measurements

Science.gov (United States)

Hopkins, J.; Balch, W. M.; Henson, S.; Poulton, A. J.; Drapeau, D.; Bowler, B.; Lubelczyk, L.

2016-02-01

Coccolithophores, the single celled phytoplankton that produce an outer covering of calcium carbonate coccoliths, are considered to be the greatest contributors to the global oceanic particulate inorganic carbon (PIC) pool. The reflective coccoliths scatter light back out from the ocean surface, enabling PIC concentration to be quantitatively estimated from ocean color satellites. Here we use datasets of AQUA MODIS PIC concentration from 2003-2014 (using the recently-revised PIC algorithm), as well as statistics on coccolithophore vertical distribution derived from cruises throughout the world ocean, to estimate the average global (surface and integrated) PIC standing stock and its associated inter-annual variability. In addition, we divide the global ocean into Longhurst biogeochemical provinces, update the PIC biomass statistics and identify those regions that have the greatest inter-annual variability and thus may exert the greatest influence on global PIC standing stock and the alkalinity pump.

The Diesel Exhaust in Miners Study: III. Interrelations between respirable elemental carbon and gaseous and particulate components of diesel exhaust derived from area sampling in underground non-metal mining facilities.

Science.gov (United States)

Vermeulen, Roel; Coble, Joseph B; Yereb, Daniel; Lubin, Jay H; Blair, Aaron; Portengen, Lützen; Stewart, Patricia A; Attfield, Michael; Silverman, Debra T

2010-10-01

Diesel exhaust (DE) has been implicated as a potential lung carcinogen. However, the exact components of DE that might be involved have not been clearly identified. In the past, nitrogen oxides (NO(x)) and carbon oxides (CO(x)) were measured most frequently to estimate DE, but since the 1990s, the most commonly accepted surrogate for DE has been elemental carbon (EC). We developed quantitative estimates of historical exposure levels of respirable elemental carbon (REC) for an epidemiologic study of mortality, particularly lung cancer, among diesel-exposed miners by back-extrapolating 1998-2001 REC exposure levels using historical measurements of carbon monoxide (CO). The choice of CO was based on the availability of historical measurement data. Here, we evaluated the relationship of REC with CO and other current and historical components of DE from side-by-side area measurements taken in underground operations of seven non-metal mining facilities. The Pearson correlation coefficient of the natural log-transformed (Ln)REC measurements with the Ln(CO) measurements was 0.4. The correlation of REC with the other gaseous, organic carbon (OC), and particulate measurements ranged from 0.3 to 0.8. Factor analyses indicated that the gaseous components, including CO, together with REC, loaded most strongly on a presumed 'Diesel exhaust' factor, while the OC and particulate agents loaded predominantly on other factors. In addition, the relationship between Ln(REC) and Ln(CO) was approximately linear over a wide range of REC concentrations. The fact that CO correlated with REC, loaded on the same factor, and increased linearly in log-log space supported the use of CO in estimating historical exposure levels to DE.

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.

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.

Mercury, monomethyl mercury, and dissolved organic carbon concentrations in surface water entering and exiting constructed wetlands treated with metal-based coagulants, Twitchell Island, California

Science.gov (United States)

Stumpner, Elizabeth B.; Kraus, Tamara E.C.; Fleck, Jacob A.; Hansen, Angela M.; Bachand, Sandra M.; Horwath, William R.; DeWild, John F.; Krabbenhoft, David P.; Bachand, Philip A.M.

2015-09-02

Coagulation with metal-based salts is a practice commonly employed by drinking-water utilities to decrease particle and dissolved organic carbon concentrations in water. In addition to decreasing dissolved organic carbon concentrations, the effectiveness of iron- and aluminum-based coagulants for decreasing dissolved concentrations both of inorganic and monomethyl mercury in water was demonstrated in laboratory studies that used agricultural drainage water from the Sacramento–San Joaquin Delta of California. To test the effectiveness of this approach at the field scale, nine 15-by-40‑meter wetland cells were constructed on Twitchell Island that received untreated water from island drainage canals (control) or drainage water treated with polyaluminum chloride or ferric sulfate coagulants. Surface-water samples were collected approximately monthly during November 2012–September 2013 from the inlets and outlets of the wetland cells and then analyzed by the U.S. Geological Survey for total concentrations of mercury and monomethyl mercury in filtered (less than 0.3 micrometers) and suspended-particulate fractions and for concentrations of dissolved organic carbon.

Seasonal carbon cycling in a Greenlandic fjord

DEFF Research Database (Denmark)

Sørensen, Heidi L.; Meire, Lorenz; Juul-Pedersen, Thomas

2015-01-01

Climate change is expected to have a pronounced effect on biogeochemical cycling in Arctic fjords, but current insight on the biogeochemical functioning of these systems is limited. Here, we present seasonal data on primary production, export of particulate organic carbon (POC), and the coupling...... carbon amounted to 3.2 and 5.3 mol C m−2 yr−1, respectively. Sulfate reduction was the most prominent mineralization pathway, accounting for 69% of the benthic mineralization, while denitrification accounted for 2%. Overall, the carbon mineralization and burial in Kobbefjord were significantly higher...... in ice coverage in higher Arctic Greenlandic fjords will, as a first approximation, entail proportional increases in productivity, mineralization, and burial of organic carbon in the fjords, which will thus become similar to present-day southerly systems....

Isotopic and chemical composition (δ13C, Δ14C, δ15N, C:N, SUVA254nm, % HPOA) of aquatic carbon and field conditions (water temperature, pH, discharge) in the Upper Mississippi River Basin, October 2014 – February 2016

Data.gov (United States)

Department of the Interior — This dataset contains stable isotope (δ13C) and radioisotope (Δ14C) compositions of dissolved inorganic carbon, dissolved organic carbon, particulate organic carbon,...

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.

Carbon-14 measurements and characterization of dissolved organic carbon in ground water

International Nuclear Information System (INIS)

Murphy, E.M.

1987-01-01

Carbon-14 was measured in the dissolved organic carbon (DOC) in ground water and compared with 14 C analyses of dissolved inorganic carbon (DIC). Two field sites were used for this study; the Stripa mine in central Sweden, and the Milk River Aquifer in southern Alberta, Canada. The Stripa mine consists of a Precambrian granite dominated by fracture flow, while the Milk River Aquifer is a Cretaceous sandstone aquifer characterized by porous flow. At both field sites, 14 C analyses of the DOC provide additional information on the ground-water age. Carbon-14 was measured on both the hydrophobic and hydrophilic organic fractions of the DOC. The organic compounds in the hydrophobic and hydrophilic fractions were also characterized. The DOC may originate from kerogen in the aquifer matrix, from soil organic matter in the recharge zone, of from a combination of these two sources. Carbon-14 analyses, along with characterization of the organics, were used to determine this origin. Carbon-14 analyses of the hydrophobic fraction in the Milk River Aquifer suggest a soil origin, while 14 C analyses of the hydrophilic fraction suggest an origin within the Cretaceous sediments (kerogen) or from the shale in contact with the aquifer

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

Export from Seagrass Meadows Contributes to Marine Carbon Sequestration

KAUST Repository

Duarte, Carlos M.; Krause-Jensen, Dorte

2017-01-01

Seagrasses export a substantial portion of their primary production, both in particulate and dissolved organic form, but the fate of this export production remains unaccounted for in terms of seagrass carbon sequestration. Here we review available evidence on the fate of seagrass carbon export to conclude that this represents a significant contribution to carbon sequestration, both in sediments outside seagrass meadows and in the deep sea. The evidence presented implies that the contribution of seagrass meadows to carbon sequestration has been underestimated by only including carbon burial within seagrass sediments.

Export from Seagrass Meadows Contributes to Marine Carbon Sequestration

KAUST Repository

Duarte, Carlos M.

2017-01-17

Seagrasses export a substantial portion of their primary production, both in particulate and dissolved organic form, but the fate of this export production remains unaccounted for in terms of seagrass carbon sequestration. Here we review available evidence on the fate of seagrass carbon export to conclude that this represents a significant contribution to carbon sequestration, both in sediments outside seagrass meadows and in the deep sea. The evidence presented implies that the contribution of seagrass meadows to carbon sequestration has been underestimated by only including carbon burial within seagrass sediments.

Global chemical composition of ambient fine particulate matter for exposure assessment.

Science.gov (United States)

Philip, Sajeev; Martin, Randall V; van Donkelaar, Aaron; Lo, Jason Wai-Ho; Wang, Yuxuan; Chen, Dan; Zhang, Lin; Kasibhatla, Prasad S; Wang, Siwen; Zhang, Qiang; Lu, Zifeng; Streets, David G; Bittman, Shabtai; Macdonald, Douglas J

2014-11-18

Epidemiologic and health impact studies are inhibited by the paucity of global, long-term measurements of the chemical composition of fine particulate matter. We inferred PM2.5 chemical composition at 0.1° × 0.1° spatial resolution for 2004-2008 by combining aerosol optical depth retrieved from the MODIS and MISR satellite instruments, with coincident profile and composition information from the GEOS-Chem global chemical transport model. Evaluation of the satellite-model PM2.5 composition data set with North American in situ measurements indicated significant spatial agreement for secondary inorganic aerosol, particulate organic mass, black carbon, mineral dust, and sea salt. We found that global population-weighted PM2.5 concentrations were dominated by particulate organic mass (11.9 ± 7.3 μg/m(3)), secondary inorganic aerosol (11.1 ± 5.0 μg/m(3)), and mineral dust (11.1 ± 7.9 μg/m(3)). Secondary inorganic PM2.5 concentrations exceeded 30 μg/m(3) over East China. Sensitivity simulations suggested that population-weighted ambient PM2.5 from biofuel burning (11 μg/m(3)) could be almost as large as from fossil fuel combustion sources (17 μg/m(3)). These estimates offer information about global population exposure to the chemical components and sources of PM2.5.

The influence of temperature calibration on the OC–EC results from a dual-optics thermal carbon analyzer

Science.gov (United States)

The Sunset Laboratory Dual-Optical Carbonaceous Analyzer that simultaneously measures transmission and reflectance signals is widely used in thermal-optical analysis of particulate matter samples. Most often this instrument is used to measure total carbon (TC), organic carbon (O...

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

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

New views on "old" carbon in the Amazon River: Insight from the source of organic carbon eroded from the Peruvian Andes

Science.gov (United States)

Clark, K. E.; Hilton, R. G.; West, A. J.; Malhi, Y.; Gröcke, D. R.; Bryant, C. L.; Ascough, P. L.; Robles Caceres, A.; New, M.

2013-05-01

rivers play a key role in the delivery of particulate organic carbon (POC) to large river systems and the ocean. Due to the extent of its drainage area and runoff, the Amazon River is one of Earth's most important biogeochemical systems. However, the source of POC eroded from the humid region of the Eastern Andes and the input of fossil POC from sedimentary rocks (POCfossil) remains poorly constrained. Here we collected suspended sediments from the Kosñipata River during flood events to better characterize Andean POC, measuring the nitrogen to organic carbon ratio (N/C), stable carbon isotopes (δ13Corg) and radiocarbon (Δ14Corg). Δ14Corg values ranged from -711‰ to -15‰, and significant linear trends between Δ14Corg, N/C and δ13Corg suggested that this reflects the mixing of POCfossil with very young organic matter (Δ14Corg 50‰) from the terrestrial biosphere (POCnon-fossil). Using N/C and Δ14Corg in an end-member mixing analysis, we quantify the fraction of POCfossil (to within 0.1) and find that it contributes a constant proportion of the suspended sediment mass (0.37 ± 0.03%) and up to 80% of total POC. In contrast, the relative contribution of POCnon-fossil was variable, being most important during the rising limb and peak discharges of flood events. The new data shed light on published measurements of "old" POC (low Δ14Corg) in Andean-fed tributaries of the Amazon River, with their Δ14Corg and δ13Corg values consistent with variable addition of POCfossil. The findings suggest a greater persistence of Andean POC in the lowland Amazon than previously recognized.

Bacterial-viral interactions in the sea surface microlayer of a black carbon-dominated tropical coastal ecosystem (Halong Bay, Vietnam

Directory of Open Access Journals (Sweden)

A. S. Pradeep Ram

2018-02-01

Full Text Available Increasing human activity has raised concerns about the impact of deposition of anthropogenic combustion aerosols (i.e., black carbon; BC on marine processes. The sea surface microlayer (SML is a key gate for the introduction of atmospheric BC into the ocean; however, relatively little is known of the effects of BC on bacteria-virus interactions, which can strongly influence microbially mediated processes. To study the impact of BC on bacteria-virus interactions, field investigations involving collection from the SML and underlying water were carried out in Halong Bay (Vietnam. Most inorganic nutrient concentrations, as well as dissolved organic carbon, were modestly but significantly higher ('p' = 0.02–0.05 in the SML than in underlying water. The concentrations of particulate organic carbon (though not chlorophyll 'a' and of total particulate carbon, which was composed largely of particulate BC (mean = 1.7 ± 6.4 mmol L–1, were highly enriched in the SML, and showed high variability among stations. On average, microbial abundances (both bacteria and viruses and bacterial production were 2- and 5fold higher, respectively, in the SML than in underlying water. Significantly lower bacterial production ('p' 3 μm compared to the bulk sample, but our data overall suggest that bacterial production in the SML was stimulated by particulate BC. Higher bacterial production in the SML than in underlying water supported high viral lytic infection rates (from 5.3 to 30.1% which predominated over percent lysogeny (from undetected to 1.4%. The sorption of dissolved organic carbon by black carbon, accompanied by the high lytic infection rate in the black carbon-enriched SML, may modify microbially mediated processes and shift the net ecosystem metabolism (ratio of production and respiration to net heterotrophy and CO2 production in this critical layer between ocean and atmosphere.

Measurement and analysis of ambient atmospheric particulate matter in urban and remote environments

Science.gov (United States)

Hagler, Gayle S. W.

Atmospheric particulate matter pollution is a challenging environmental concern in both urban and remote locations worldwide. It is intrinsically difficult to control, given numerous anthropogenic and natural sources (e.g. fossil fuel combustion, biomass burning, dust, and seaspray) and atmospheric transport up to thousands of kilometers after production. In urban regions, fine particulate matter (particles with diameters under 2.5 mum) is of special concern for its ability to penetrate the human respiratory system and threaten cardiopulmonary health. A second major impact area is climate, with particulate matter altering Earth's radiative balance through scattering and absorbing solar radiation, modifying cloud properties, and reducing surface reflectivity after deposition in snow-covered regions. While atmospheric particulate matter has been generally well-characterized in populated areas of developed countries, particulate pollution in developing nations and remote regions is relatively unexplored. This thesis characterizes atmospheric particulate matter in locations that represent the extreme ends of the spectrum in terms of air pollution-the rapidly-developing and heavily populated Pearl River Delta Region of China, the pristine and climate-sensitive Greenland Ice Sheet, and a remote site in the Colorado Rocky Mountains. In China, fine particles were studied through a year-long field campaign at seven sites surrounding the Pearl River Delta. Fine particulate matter was analyzed for chemical composition, regional variation, and meteorological impacts. On the Greenland Ice Sheet and in the Colorado Rocky Mountains, the carbonaceous fraction (organic and elemental carbon) of particulate matter was studied in the atmosphere and snow pack. Analyses included quantifying particulate chemical and optical properties, assessing atmospheric transport, and evaluating post-depositional processing of carbonaceous species in snow.

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

An assessment, using stable isotopes, of the importance of allochthonous organic carbon sources to the pelagic food web in Loch Ness

Science.gov (United States)

Jones, R. I.; Grey, J.; Sleep, D.; Quarmby, C.

1998-01-01

The natural abundance of stable isotopes (δ13C and δ1315N) was determined for components of the pelagic food web in Loch Ness, a deep oligotrophic lake in northern Scotland, and compared with values from the inflow rivers and the catchment vegetation. Phytoplankton δ13C was low compared to values reported from other lakes, possibly reflecting a high use of 13C-depleted carbon dioxide from respired organic matter before further isotopic fractionation during photosynthesis. Phytoplankton δ13C was appreciably lower than that of dissolved and particulate organic matter (DOM and POM) in the loch. The DOM and POM were evidently overwhelmingly of allochthonous origin and ultimately derived from terrestrial plant detritus. The distinctive δ13C values for phytoplankton and detritus in the loch allowed the use of food sources by grazing crustacean zooplankton to be assessed, and the contributions of phytoplankton carbon and detrital carbon to zooplankton total body carbon appeared to be about equal. Comparison of δ13C and δ15N values for zooplankton and fish allowed assessment of trophic structure in the loch. The very high dependence of the pelagic food web in Loch Ness on allochthonous organic matter inputs from the catchment may be exceptional in a large lake, but has important implications for our understanding of lake ecosystem processes as well as for lake management.

Diesel emission control: Catalytic filters for particulate removal

Directory of Open Access Journals (Sweden)

Debora Fino

2007-01-01

Full Text Available The European diesel engine industry represents a vital sector across the Continent, with more than 2 million direct work positions and a turnover of over 400 billion Euro. Diesel engines provide large paybacks to society since they are extensively used to transport goods, services and people. In recent years increasing attention has been paid to the emissions from diesel engines which, like gasoline engine emissions, include carbon monoxide (CO, hydrocarbons (HC and oxides of nitrogen (NOx. Diesel engines also produce significant levels of particulate matter (PM, which consists mostly of carbonaceous soot and a soluble organic fraction (SOF of hydrocarbons that have condensed on the soot.

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.

Autochthonous and allochthonous contributions of organic carbon to microbial food webs in Svalbard fjords

KAUST Repository

Holding, Johnna M.; Duarte, Carlos M.; Delgado-Huertas, Antonio; Soetaert, Karline; Vonk, Jorien E.; Agusti, Susana; Wassmann, Paul; Middelburg, Jack J.

2017-01-01

Rising temperatures in the Arctic Ocean are causing sea ice and glaciers to melt at record breaking rates, which has consequences for carbon cycling in the Arctic Ocean that are yet to be fully understood. Microbial carbon cycling is driven by internal processing of in situ produced organic carbon (OC), however recent research suggests that melt water from sea ice and glaciers could introduce an allochthonous source of OC to the microbial food web with ramifications for the metabolic balance of plankton communities. In this study, we characterized autochthonous and allochthonous sources of OC to the Western Svalbard fjord system using stable isotopes of carbon. We quantified δ13C of eukaryotic and prokaryotic planktonic groups using polar lipid-derived fatty acids as biomarkers in addition to measuring δ13C of marine particulate OC and dissolved OC from glacial runoff. δ13C of bacteria (−22.5‰) was higher than that of glacial runoff OC (−28.5‰) and other phytoplankton groups (−24.7 to −29.1‰), which suggests that marine bacteria preferentially use a third source of OC. We present a Bayesian three-source δ13C mixing model whereby ∼ 60% of bacteria carbon is derived from OC in sea ice, and the remaining carbon is derived from autochthonous production and glacial-derived OC. These results suggest that subsidies of OC from melting glaciers will not likely influence microbial carbon cycling in Svalbard fjords in the future and that further research is needed to determine the effects of melting sea ice on microbial carbon cycling in fjord systems and elsewhere in the Arctic Ocean.

Autochthonous and allochthonous contributions of organic carbon to microbial food webs in Svalbard fjords

KAUST Repository

Holding, Johnna M.

2017-03-27

Rising temperatures in the Arctic Ocean are causing sea ice and glaciers to melt at record breaking rates, which has consequences for carbon cycling in the Arctic Ocean that are yet to be fully understood. Microbial carbon cycling is driven by internal processing of in situ produced organic carbon (OC), however recent research suggests that melt water from sea ice and glaciers could introduce an allochthonous source of OC to the microbial food web with ramifications for the metabolic balance of plankton communities. In this study, we characterized autochthonous and allochthonous sources of OC to the Western Svalbard fjord system using stable isotopes of carbon. We quantified δ13C of eukaryotic and prokaryotic planktonic groups using polar lipid-derived fatty acids as biomarkers in addition to measuring δ13C of marine particulate OC and dissolved OC from glacial runoff. δ13C of bacteria (−22.5‰) was higher than that of glacial runoff OC (−28.5‰) and other phytoplankton groups (−24.7 to −29.1‰), which suggests that marine bacteria preferentially use a third source of OC. We present a Bayesian three-source δ13C mixing model whereby ∼ 60% of bacteria carbon is derived from OC in sea ice, and the remaining carbon is derived from autochthonous production and glacial-derived OC. These results suggest that subsidies of OC from melting glaciers will not likely influence microbial carbon cycling in Svalbard fjords in the future and that further research is needed to determine the effects of melting sea ice on microbial carbon cycling in fjord systems and elsewhere in the Arctic Ocean.

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.

[Distribution and origin of polycyclic aromatic hydrocarbons in suspended particulate matters from the Yangtze estuarine and nearby coastal areas].

Science.gov (United States)

Ou, Dong-ni; Liu, Min; Xu, Shi-yuan; Cheng, Shu-bo; Hou, Li-jun; Gao, Lei

2008-09-01

Parent PAHs have been quantified in suspended particulate matters from the Yangtze Estuarine and Coastal Areas. The results show that the concentrations of total PAHs ranged from 2278.79-14293.98 ng/g, and were characterized by greatest content near sewage discharge point with trend to decrease by increasing distance. As for PAHs composition, 4-6 rings PAHs were dominant while 2-3 rings PAHs were relative low. Cluster analysis found that except urban sewage discharge, the hydrodynamic force was influencing PAHs distribution patterns. Moreover, the content of suspended particulate matters, organic carbon and soot carbon of suspended particulate matters also play the important roles in PAHs distribution from the Yangtze estuarine and nearby coastal areas. Principal component analysis and PAH ratios demonstrated that uncompleted combustion of fossil fuels was the main source of PAHs in coastal areas, as well as a few anthropogenic releases of oil and oil products. Ecological risk assessment indicated that most of PAH compounds exceeded the effects range ER-L values and ISQV-L values, which might certain potential damage to the Yangtze Estuary ecosystem.

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

Soil organic carbon redistribution by water erosion--the role of CO2 emissions for the carbon budget.

Science.gov (United States)

Wang, Xiang; Cammeraat, Erik L H; Romeijn, Paul; Kalbitz, Karsten

2014-01-01

A better process understanding of how water erosion influences the redistribution of soil organic carbon (SOC) is sorely needed to unravel the role of soil erosion for the carbon (C) budget from local to global scales. The main objective of this study was to determine SOC redistribution and the complete C budget of a loess soil affected by water erosion. We measured fluxes of SOC, dissolved organic C (DOC) and CO2 in a pseudo-replicated rainfall-simulation experiment. We characterized different C fractions in soils and redistributed sediments using density fractionation and determined C enrichment ratios (CER) in the transported sediments. Erosion, transport and subsequent deposition resulted in significantly higher CER of the sediments exported ranging between 1.3 and 4.0. In the exported sediments, C contents (mg per g soil) of particulate organic C (POC, C not bound to soil minerals) and mineral-associated organic C (MOC) were both significantly higher than those of non-eroded soils indicating that water erosion resulted in losses of C-enriched material both in forms of POC and MOC. The averaged SOC fluxes as particles (4.7 g C m(-2) yr(-1)) were 18 times larger than DOC fluxes. Cumulative emission of soil CO2 slightly decreased at the erosion zone while increased by 56% and 27% at the transport and depositional zone, respectively, in comparison to non-eroded soil. Overall, CO2 emission is the predominant form of C loss contributing to about 90.5% of total erosion-induced C losses in our 4-month experiment, which were equal to 18 g C m(-2). Nevertheless, only 1.5% of the total redistributed C was mineralized to CO2 indicating a large stabilization after deposition. Our study also underlines the importance of C losses by particles and as DOC for understanding the effects of water erosion on the C balance at the interface of terrestrial and aquatic ecosystems.

Accumulation of organic carbon in northwestern Arabian sea sediments

International Nuclear Information System (INIS)

Khan, A.A.

1999-01-01

In this study accumulation of organic carbon in marine sediments of northwestern Arabian sea has been discussed. This paper presents the geochemical analysis of Organic carbon content and accumulation, delta 13 stable carbon isotope and Ba/Al. The primary objective was to investigate the high resolution information about the variations in paleoproductivity and source of organic matter in sediments below an upwelling area. Undisturbed sediments (Piston core NIOP-486) of late Pleistocene time were collected during Netherlands Indian Ocean Program (NIOP-1992-93). The core NIOP-486 was raised from a depth of 2077 meters near the Owen Ridge. This core records deposition history of last 200,000 years and includes 4 warm and 3 cold periods. The distribution of organic carbon content in studied core shows a pronounced cyclicity during glacial and interglacial stages. Organic carbon accumulation trends show that high sedimentation rates in glacial stages results in rapid burial and hence increase organic carbon accumulation. Paleoproductivity indicator Ba/Al has been used to compare with the organic carbon content and is correlated with the warm and cold periods variations in monsoons upwelling intensity. Generally, low paleoproductivity is found in glacial stages. The organic carbon content and accumulation, in sediments however seems to differ from the paleoproductivity trends shown by Ba/Al in glacial sediments of stage 6. Delta 13 C.org isotope results of the core NIOP-486 confirm that organic matter in sediments is predominantly marine (-20 to -23% ). (author)

The distribution of radionuclides between the dissolved and particulate phases of a contaminated freshwater stream

International Nuclear Information System (INIS)

Murdock, R.N.; Johnson, M.S.; Hemingway, J.D.

1995-01-01

Streamwater concentrations of the radionuclides 137 Cs, 241 Am and 239,240 Pu from a contaminated freshwater stream showed significant relationships between total concentration and flow rate. When total concentrations were divided into their dissolved and particulate components 239,240 Pu was shown to exist mainly (>80%) in the solute phase ( 137 Cs and 241 Am were distributed equally between the two phases. 137 Cs was most likely present either as the dissolved ion or as the specifically adsorbed ion on particulate sediments. Particle-associated 241 Am and the small particulate component of 239,240 Pu, were believed to be bound to sediment surface coatings, such as organic or oxide/hydroxides, rather than the truly adsorbed ion. Solute phase 239,240 Pu was most likely associated with colloidal organic carbon species (such as humic or fulvic acids). This was also apparent, but to a lesser extent, for 241 Am. Distribution coefficients were determined for a number of discrete sites and environmental conditions. The response of the stream to removal of its source of radioactivity (via a re-routing scheme) was both significant and rapid. (author)

A study of the carbon dioxide system in the northern Indian Ocean during premonsoon

Digital Repository Service at National Institute of Oceanography (India)

George, M.D.; DileepKumar, M.; Naqvi, S.W.A.; Banerjee, S.; Narvekar, P.V.; De; Jayakumar, D.A.

is relatively small (17.5 ~kM). Significantly,, the contribution of the organic decomposition in this region is only 1/7 of the increase in TCO@d2@@. This, together with the earlier reports on large sinking fluxes of particulate organic carbon and pronounced...

Weathering, landscape equilibrium, and carbon in four watersheds in eastern Puerto Rico: Chapter H in Water quality and landscape processes of four watersheds in eastern Puerto Rico

Science.gov (United States)

Stallard, Robert F.; Murphy, Sheila F.; Stallard, Robert F.

2012-01-01

The U.S. Geological Survey's Water, Energy, and Biogeochemical Budgets (WEBB) program research in eastern Puerto Rico involves a double pair-wise comparison of four montane river basins, two on granitic bedrock and two on fine-grained volcaniclastic bedrock; for each rock type, one is forested and the other is developed. A confounding factor in this comparison is that the developed watersheds are substantially drier than the forested (runoff of 900–1,600 millimeters per year compared with 2,800–3,700 millimeters per year). To reduce the effects of contrasting runoff, the relation between annual runoff and annual constituent yield were used to estimate mean-annual yields at a common, intermediate mean-annual runoff of 1,860 millimeters per year. Upon projection to this intermediate runoff, the ranges of mean-annual yields among all watersheds became more compact or did not substantially change for dissolved bedrock, sodium, silica, chloride, dissolved organic carbon, and calcium. These constituents are the primary indicators of chemical weathering, biological activity on the landscape, and atmospheric inputs; the narrow ranges indicate little preferential influence by either geology or land cover. The projected yields of biologically active constituents (potassium, nitrate, ammonium ion, phosphate), and particulate constituents (suspended bedrock and particulate organic carbon) were considerably greater for developed landscapes compared with forested watersheds, consistent with the known effects of land clearing and human waste inputs. Equilibrium rates of combined chemical and physical weathering were estimated by using a method based on concentrations of silicon and sodium in bedrock, river-borne solids, and river-borne solutes. The observed rates of landscape denudation greatly exceed rates expected for a dynamic equilibrium, except possibly for the forested watershed on volcaniclastic rock. Deforestation and agriculture can explain the accelerated physical

Source apportionment of carbonaceous particulate matter during haze days in Shanghai based on the radiocarbon

International Nuclear Information System (INIS)

Nannan Wei; Jialiang Feng; Detao Xiao

2017-01-01

To estimate the sources of carbonaceous particulate matter, "1"4C and biomass-burning marker (levoglucosan) were measured in the form of organic carbon (OC) and elemental carbon (EC) in PM_2_._5 that was collected in five different functional districts of Shanghai during winter 2013. Spatial variations of the contemporary proportion among different districts were evident. The results of levoglucosan in Xujiahui (XH) and Chongming (CM) agreed well with those of "1"4C. The results indicate that environmental protection policies should vary for functional districts within the same city to account for their different sources of emissions. (author)

Flocculation of organic carbon from headwaters to estuary - the impact of soil erosion, water quality and land use on carbon transformation processes in eight streams draining Exmoor, UK

Science.gov (United States)

Snoalv, J.; Groeneveld, M.; Quine, T. A.; Tranvik, L.

2017-12-01

Flocculation of dissolved organic carbon (DOC) in streams and rivers is a process that contributes to the pool of particulate organic carbon (POC) in the aquatic system. In low-energy waters the increased sedimentation rates of this higher-density fraction of organic carbon (OC) makes POC important in allocating organic carbon into limnic storage, which subsequently influences emissions of greenhouse gases from the continental environment to the atmosphere. Allochthonous OC, derived from the terrestrial environment by soil erosion and litterfall, import both mineral aggregate-bound and free OC into freshwaters, which comprise carbon species of different quality and recalcitrance than autochthonous in-stream produced OC, such as from biofilms, aquatic plants and algae. Increased soil erosion due to land use change (e.g. agriculture, deforestation etc.) influences the input of allochthonous OC, which can lead to increased POC formation and sedimentation of terrestrial OC at flocculation boundaries in the landscape, i.e. where coagulation and flocculation processes are prone to occur in the water column. This study investigates the seasonal variation in POC content and flocculation capacity with respect to water quality (elemental composition) in eight river systems (four agricultural and four wooded streams) with headwaters in Exmoor, UK, that drain managed and non-managed land into Bristol Channel. Through flocculation experiments the samples were allowed to flocculate by treatments with added clay and salt standards that simulate the flocculation processes by 1) increased input of sediment into streams, and 2) saline mixing at the estuarine boundary, in order to quantify floc production and investigate POC quality by each process respectively. The results show how floc production, carbon quality and incorporation (e.g. complexation) of metals and rare earth elements (REE) in produced POC and remaining DOC in solution vary in water samples over the season and how

Cycles of selected trace elements in the South Atlantic: Vertical transport and interactions between particulates and solution; Zum Kreislauf ausgewaehlter Spurenmetalle im Suedatlantik: Vertikaltransport und Wechselwirkung zwischen Partikeln und Loesung

Energy Technology Data Exchange (ETDEWEB)

Dierssen, H

1999-07-01

Subjects: Concentrations, vertical and regional distributions of dissolved and suspended particulate trace elements; Trace element fluxes - vertical, regional, seasonal; The role of particulate organic carbon and atmospheric dust in vertical transport; Fractionation of trace elements in particulate material during transport. [German] Themen dieser Arbeit sind: Konzentrationen, vertikale und regionale Verteilungen von geloesten und suspendierten partikulaeren Spurenelementem (SE); SE-Fluesse vertikal, regional und saisonal; die Rolle des partikulaeren organischen Kohlenstoffs und des atmosphaerischen Staubeintrags beim Vertikaltransport; Fraktionierung von SE im partikulaeren Material beim Transport. (orig./SR)

A new look at ocean carbon remineralization for estimating deepwater sequestration

DEFF Research Database (Denmark)

Guidi, L.; Legendre, L.; Reygondeau, Gabriel

2015-01-01

provinces, where these estimates range between -50 and +100% of the commonly used globally uniform remineralization value. We apply the regionalized values to satellite-derived estimates of upper ocean POC export to calculate regionalized and ocean-wide deep carbon fluxes and sequestration. The resulting....... These results stress that variable remineralization and sequestration depth should be used to model ocean carbon sequestration and feedback on the atmosphere......The "biological carbon pump" causes carbon sequestration in deep waters by downward transfer of organic matter, mostly as particles. This mechanism depends to a great extent on the uptake of CO2 by marine plankton in surface waters and subsequent sinking of particulate organic carbon (POC) through...

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.

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

Chemistry of organic carbon in soil with relationship to the global carbon cycle

International Nuclear Information System (INIS)

Post, W.M. III.

1988-01-01

Various ecosystem disturbances alter the balances between production of organic matter and its decomposition and therefore change the amount of carbon in soil. The most severe perturbation is conversion of natural vegetation to cultivated crops. Conversion of natural vegetation to cultivated crops results in a lowered input of slowly decomposing material which causes a reduction in overall carbon levels. Disruption of soil matrix structure by cultivation leads to lowered physical protection of organic matter resulting in an increased net mineralization rate of soil carbon. Climate change is another perturbation that affects the amount and composition of plant production, litter inputs, and decomposition regimes but does not affect soil structure directly. Nevertheless, large changes in soil carbon storage are probable with anticipated CO 2 induced climate change, particularly in northern latitudes where anticipated climate change will be greatest (MacCracken and Luther 1985) and large amounts of soil organic matter are found. It is impossible, given the current state of knowledge of soil organic matter processes and transformations to develop detailed process models of soil carbon dynamics. Largely phenomenological models appear to be developing into predictive tools for understanding the role of soil organic matter in the global carbon cycle. In particular, these models will be useful in quantifying soil carbon changes due to human land-use and to anticipated global climate and vegetation changes. 47 refs., 7 figs., 2 tabs

Dynamics of dissolved organic matter in fjord ecosystems: Contributions of terrestrial dissolved organic matter in the deep layer

Science.gov (United States)

Yamashita, Youhei; McCallister, S. Leigh; Koch, Boris P.; Gonsior, Michael; Jaffé, Rudolf

2015-06-01

Annually, rivers and inland water systems deliver a significant amount of terrestrial organic matter (OM) to the adjacent coastal ocean in both particulate and dissolved forms; however, the metabolic and biogeochemical transformations of OM during its seaward transport remains one of the least understood components of the global carbon cycle. This transfer of terrestrial carbon to marine ecosystems is crucial in maintaining trophic dynamics in coastal areas and critical in global carbon cycling. Although coastal regions have been proposed as important sinks for exported terrestrial materials, most of the global carbon cycling data, have not included fjords in their budgets. Here we present distributional patterns on the quantity and quality of dissolved OM in Fiordland National Park, New Zealand. Specifically, we describe carbon dynamics under diverse environmental settings based on dissolved organic carbon (DOC) depth profiles, oxygen concentrations, optical properties (fluorescence) and stable carbon isotopes. We illustrate a distinct change in the character of DOC in deep waters compared to surface and mid-depth waters. Our results suggest that, both, microbial reworking of terrestrially derived plant detritus and subsequent desorption of DOC from its particulate counterpart (as verified in a desorption experiment) are the main sources of the humic-like enriched DOC in the deep basins of the studied fjords. While it has been suggested that short transit times and protection of OM by mineral sorption may ultimately result in significant terrestrial carbon burial and preservation in fjords, our data suggests the existence of an additional source of terrestrial OM in the form of DOC generated in deep, fjord water.

Toward a quantitative and empirical dissolved organic carbon budget for the Gulf of Maine, a semienclosed shelf sea

Science.gov (United States)

Balch, William; Huntington, Thomas; Aiken, George; Drapeau, David; Bowler, Bruce; Lubelczyk, Laura; Butler, Kenna

2016-02-01

A time series of organic carbon export from Gulf of Maine (GoM) watersheds was compared to a time series of biological, chemical, bio-optical, and hydrographic properties, measured across the GoM between Yarmouth, NS, Canada, and Portland, ME, U.S. Optical proxies were used to quantify the dissolved organic carbon (DOC) and particulate organic carbon in the GoM. The Load Estimator regression model applied to river discharge data demonstrated that riverine DOC export (and its decadal variance) has increased over the last 80 years. Several extraordinarily wet years (2006-2010) resulted in a massive pulse of chromophoric dissolved organic matter (CDOM; proxy for DOC) into the western GoM along with unidentified optically scattering material (DOC in the GoM and Scotian Shelf showed the strong influence of the Gulf of Saint Lawrence on the DOC that enters the GoM. A deep plume of CDOM-rich water was observed near the coast of Maine which decreased in concentration eastward. The Forel-Ule color scale was derived and compared to the same measurements made in 1912-1913 by Henry Bigelow. Results show that the GoM has yellowed in the last century, particularly in the region of the extension of the Eastern Maine Coastal Current. Time lags between DOC discharge and its appearance in the GoM increased with distance from the river mouths. Algae were also a significant source of DOC but not CDOM. Gulf-wide algal primary production has decreased. Increases in precipitation and DOC discharge to the GoM are predicted over the next century.

Exposure of miners to diesel exhaust particulates in underground nonmetal mines.

Science.gov (United States)

Cohen, H J; Borak, J; Hall, T; Sirianni, G; Chemerynski, S

2002-01-01

A study was initiated to examine worker exposures in seven underground nonmetal mines and to examine the precision of the National Institute for Occupational Safety and Health (NIOSH) 5040 sampling and analytical method for diesel exhaust that has recently been adopted for compliance monitoring by the Mine Safety and Health Administration (MSHA). Approximately 1000 air samples using cyclones were taken on workers and in areas throughout the mines. Results indicated that worker exposures were consistently above the MSHA final limit of 160 micrograms/m3 (time-weighted average; TWA) for total carbon as determined by the NIOSH 5040 method and greater than the proposed American Conference of Governmental Industrial Hygienists TLV limit of 20 micrograms/m3 (TWA) for elemental carbon. A number of difficulties were documented when sampling for diesel exhaust using organic carbon: high and variable blank values from filters, a high variability (+/- 20%) from duplicate punches from the same sampling filter, a consistent positive interference (+26%) when open-faced monitors were sampled side-by-side with cyclones, poor correlation (r 2 = 0.38) to elemental carbon levels, and an interference from limestone that could not be adequately corrected by acid-washing of filters. The sampling and analytical precision (relative standard deviation) was approximately 11% for elemental carbon, 17% for organic carbon, and 11% for total carbon. An hypothesis is presented and supported with data that gaseous organic carbon constituents of diesel exhaust adsorb onto not only the submicron elemental carbon particles found in diesel exhaust, but also mining ore dusts. Such mining dusts are mostly nonrespirable and should not be considered equivalent to submicron diesel particulates in their potential for adverse pulmonary effects. It is recommended that size-selective sampling be employed, rather than open-faced monitoring, when using the NIOSH 5040 method.

Elemental and organic carbon in flue gas particles of various wood combustion systems

Energy Technology Data Exchange (ETDEWEB)

Gaegauf, C.; Schmid, M.; Guentert, P.

2005-12-15

The airborne particulate matter (PM) in the environment is of ever increasing concern to authorities and the public. The major fractions of particles in wood combustion processes are in the size less than 1 micron, typically in the range of 30 to 300 nm. Of specific interest is the content of the elemental carbon (EC) and organic carbon (OC) in the particles since these substances are known for its particular potential as carcinogens. Various wood combustion systems have been analysed (wood chip boiler, pellet boiler, wood log boiler, wood stove and open fire). The sampling of the particles was done by mean of a multi-stage particle sizing sampler cascade impactor. The impactor classifies the particles collected according to their size. The 7 stages classify the particles between 0.4 and 9 microns aerodynamic diameter. The analytical method for determining the content of EC and OC in the particles is based on coulometry. The coulometer measures the conductivity of CO{sub 2} released by oxidation of EC in the samples at 650 {sup o}C. The OC content is determined by pyrolysis of the particle samples in helium atmosphere.

Comparing the NIOSH Method 5040 to a Diesel Particulate Matter Meter for Elemental Carbon

Science.gov (United States)

Ayers, David Matthew

Introduction: The sampling of elemental carbon has been associated with monitoring exposures in the trucking and mining industries. Recently, in the field of engineered nanomaterials, single wall and muti-wall carbon nanotubes (MWCNTs) are being produced in ever increasing quantities. The only approved atmospheric sampling for multi-wall carbon nanotubes in NIOSH Method 5040. These results are accurate but can take up to 30 days for sample results to be received. Objectives: Compare the results of elemental carbon sampling from the NIOSH Method 5040 to a Diesel Particulate Matter (DPM) Meter. Methods: MWCNTs were transferred and weighed between several trays placed on a scale. The NIOSH Method 5040 and DPM sampling train was hung 6 inches above the receiving tray. The transferring and weighing of the MWCNTs created an aerosol containing elemental carbon. Twenty-one total samples using both meters type were collected. Results: The assumptions for a Two-Way ANOVA were violated therefore, Mann-Whitney U Tests and a Kruskal-Wallis Test were performed. The hypotheses for both research questions were rejected. There was a significant difference in the EC concentrations obtained by the NIOSH Method 5040 and the DPM meter. There were also significant differences in elemental carbon level concentrations when sampled using a DPM meter versus a sampling pump based upon the three concentration levels (low, medium and high). Conclusions: The differences in the EC concentrations were statistically significant therefore, the two methods (NIOSH Method 5040 and DPM) are not the same. The NIOSH Method 5040 should continue to be the only authorized method of establishing an EC concentration for MWCNTs until a MWCNT specific method or an instantaneous meter is invented.

Water soluble organic aerosols in the Colorado Rocky Mountains, USA: composition, sources and optical properties

OpenAIRE

Xie, Mingjie; Mladenov, Natalie; Williams, Mark W.; Neff, Jason C.; Wasswa, Joseph; Hannigan, Michael P.

2016-01-01

Atmospheric aerosols have been shown to be an important input of organic carbon and nutrients to alpine watersheds and influence biogeochemical processes in these remote settings. For many remote, high elevation watersheds, direct evidence of the sources of water soluble organic aerosols and their chemical and optical characteristics is lacking. Here, we show that the concentration of water soluble organic carbon (WSOC) in the total suspended particulate (TSP) load at a high elevation site in...

Organic carbon isotope systematics of coastal marshes

NARCIS (Netherlands)

Middelburg, J.J.; Nieuwenhuize, J.; Lubberts, R.K.; Van de Plassche, O.

1997-01-01

Measurements of nitrogen, organic carbon and delta(13)C are presented for Spartina-dominated marsh sediments from a mineral marsh in SW Netherlands and from a peaty marsh in Massachusetts, U.S.A. delta(13)C Of organic carbon in the peaty marsh sediments is similar to that of Spartina material,

Formation of Particulate Matter from the Oxidation of Evaporated Wastewater from Hydraulic Fracturing Activity

Science.gov (United States)

Hildebrandt Ruiz, L.; Bean, J. K.; Bilotto, A.

2017-12-01

The use of hydraulic fracturing for production of petroleum and natural gas has increased dramatically in the last decade, but the environmental impacts of this technology remain unclear. Experiments were conducted to quantify airborne emissions from twelve samples of hydraulic fracturing flowback wastewater collected in the Permian Basin, as well as the photochemical processing of these emissions leading to the formation of particulate matter. The concentration of total volatile carbon (TVC, hydrocarbons evaporating at room temperature) averaged 29 milligrams of carbon per liter (mgC/L) and the TVC evaporation rate averaged 1357 mgC/L-m2-min. After photochemical oxidation under high NOx conditions the amount of organic particulate matter formed per milliliter of wastewater evaporated averaged 24 micrograms (µg); the amount of ammonium nitrate formed averaged 262 µg. In the state of Texas, the potential formation of PM from evaporated flowback wastewater is similar to the estimated PM emissions from diesel engines used in oil rigs, emphasizing the need to quantify wastewater evaporation and atmospheric processing of these emissions.

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

Fossil and non-fossil sources of organic carbon (OC and elemental carbon (EC in Göteborg, Sweden

Directory of Open Access Journals (Sweden)

S. Szidat

2009-03-01

Full Text Available Particulate matter was collected at an urban site in Göteborg (Sweden in February/March 2005 and in June/July 2006. Additional samples were collected at a rural site for the winter period. Total carbon (TC concentrations were 2.1–3.6 μg m⁻³, 1.8–1.9 μg m⁻³, and 2.2–3.0 μg m⁻³ for urban/winter, rural/winter, and urban/summer conditions, respectively. Elemental carbon (EC, organic carbon (OC, water-insoluble OC (WINSOC, and water-soluble OC (WSOC were analyzed for ¹⁴C in order to distinguish fossil from non-fossil emissions. As wood burning is the single major source of non-fossil EC, its contribution can be quantified directly. For non-fossil OC, the wood-burning fraction was determined independently by levoglucosan and ¹⁴C analysis and combined using Latin-hypercube sampling (LHS. For the winter period, the relative contribution of EC from wood burning to the total EC was >3 times higher at the rural site compared to the urban site, whereas the absolute concentrations of EC from wood burning were elevated only moderately at the rural compared to the urban site. Thus, the urban site is substantially more influenced by fossil EC emissions. For summer, biogenic emissions dominated OC concentrations most likely due to secondary organic aerosol (SOA formation. During both seasons, a more pronounced fossil signal was observed for Göteborg than has previously been reported for Zurich, Switzerland. Analysis of air mass origin using back trajectories suggests that the fossil impact was larger when local sources dominated, whereas long-range transport caused an enhanced non-fossil signal. In comparison to other European locations, concentrations of levoglucosan and other monosaccharide anhydrides were low for the urban and the rural site in the area of Göteborg during winter.

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.

Soil Organic Carbon Redistribution by Water Erosion – The Role of CO2 Emissions for the Carbon Budget

Science.gov (United States)

Wang, Xiang; Cammeraat, Erik L. H.; Romeijn, Paul; Kalbitz, Karsten

2014-01-01

A better process understanding of how water erosion influences the redistribution of soil organic carbon (SOC) is sorely needed to unravel the role of soil erosion for the carbon (C) budget from local to global scales. The main objective of this study was to determine SOC redistribution and the complete C budget of a loess soil affected by water erosion. We measured fluxes of SOC, dissolved organic C (DOC) and CO2 in a pseudo-replicated rainfall-simulation experiment. We characterized different C fractions in soils and redistributed sediments using density fractionation and determined C enrichment ratios (CER) in the transported sediments. Erosion, transport and subsequent deposition resulted in significantly higher CER of the sediments exported ranging between 1.3 and 4.0. In the exported sediments, C contents (mg per g soil) of particulate organic C (POC, C not bound to soil minerals) and mineral-associated organic C (MOC) were both significantly higher than those of non-eroded soils indicating that water erosion resulted in losses of C-enriched material both in forms of POC and MOC. The averaged SOC fluxes as particles (4.7 g C m−2 yr−1) were 18 times larger than DOC fluxes. Cumulative emission of soil CO2 slightly decreased at the erosion zone while increased by 56% and 27% at the transport and depositional zone, respectively, in comparison to non-eroded soil. Overall, CO2 emission is the predominant form of C loss contributing to about 90.5% of total erosion-induced C losses in our 4-month experiment, which were equal to 18 g C m−2. Nevertheless, only 1.5% of the total redistributed C was mineralized to CO2 indicating a large stabilization after deposition. Our study also underlines the importance of C losses by particles and as DOC for understanding the effects of water erosion on the C balance at the interface of terrestrial and aquatic ecosystems. PMID:24802350

Effect of nutrient enrichment on the source and composition of sediment organic carbon in tropical seagrass beds in the South China Sea.

Science.gov (United States)

Liu, Songlin; Jiang, Zhijian; Zhang, Jingping; Wu, Yunchao; Lian, Zhonglian; Huang, Xiaoping

2016-09-15

To assess the effect of nutrient enrichment on the source and composition of sediment organic carbon (SOC) beneath Thalassia hemprichii and Enhalus acoroides in tropical seagrass beds, Xincun Bay, South China Sea, intertidal sediment, primary producers, and seawater samples were collected. No significant differences on sediment δ(13)C, SOC, and microbial biomass carbon (MBC) were observed between T. hemprichii and E. acoroides. SOC was mainly of autochthonous origin, while the contribution of seagrass to SOC was less than that of suspended particulate organic matter, macroalgae and epiphytes. High nutrient concentrations contributed substantially to SOC of seagrass, macroalgae, and epiphytes. The SOC, MBC, and MBC/SOC ratio in the nearest transect to fish farming were the highest. This suggested a more labile composition of SOC and shorter turnover times in higher nutrient regions. Therefore, the research indicates that nutrient enrichment could enhance plant-derived contributions to SOC and microbial use efficiency. Copyright © 2016 Elsevier Ltd. All rights reserved.

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.

Volatile organic carbon/air separation test using gas membranes

International Nuclear Information System (INIS)

King, C.V.; Kaschemekat, J.

1993-08-01

An estimated 900 metric tons of carbon tetrachloride were discharged to soil columns during the Plutonium Finishing Plant Operations at the Hanford Site. The largest percentage of this volatile organic compound was found in the vadose region of the 200 West Area. Using a Vacuum Extraction System, the volatile organic compound was drawn from the soil in an air mixture at a concentration of about 1,000 parts per million. The volatile organic compounds were absorbed from the air stream using granulated activated carbon canisters. A gas membrane separation system, developed by Membrane Technology and Research, Inc., was tested at the Vacuum Extraction System site to determine if the volatile organic compound load on the granulated activated carbon could be reduced. The Vacuum Extraction System condensed most of the volatile organic compound into liquid carbon tetrachloride and vented the residual gas stream into the granulated activated carbon. This system reduced the cost of operation about $5/kilogram of volatile organic compound removed

Emission factors for gaseous and particulate pollutants from offshore diesel engine vessels in China

Science.gov (United States)

Zhang, Fan; Chen, Yingjun; Tian, Chongguo; Lou, Diming; Li, Jun; Zhang, Gan; Matthias, Volker

2016-05-01

Shipping emissions have significant influence on atmospheric environment as well as human health, especially in coastal areas and the harbour districts. However, the contribution of shipping emissions on the environment in China still need to be clarified especially based on measurement data, with the large number ownership of vessels and the rapid developments of ports, international trade and shipbuilding industry. Pollutants in the gaseous phase (carbon monoxide, sulfur dioxide, nitrogen oxides, total volatile organic compounds) and particle phase (particulate matter, organic carbon, elemental carbon, sulfates, nitrate, ammonia, metals) in the exhaust from three different diesel-engine-powered offshore vessels in China (350, 600 and 1600 kW) were measured in this study. Concentrations, fuel-based and power-based emission factors for various operating modes as well as the impact of engine speed on emissions were determined. Observed concentrations and emission factors for carbon monoxide, nitrogen oxides, total volatile organic compounds, and particulate matter were higher for the low-engine-power vessel (HH) than for the two higher-engine-power vessels (XYH and DFH); for instance, HH had NOx EF (emission factor) of 25.8 g kWh-1 compared to 7.14 and 6.97 g kWh-1 of DFH, and XYH, and PM EF of 2.09 g kWh-1 compared to 0.14 and 0.04 g kWh-1 of DFH, and XYH. Average emission factors for all pollutants except sulfur dioxide in the low-engine-power engineering vessel (HH) were significantly higher than that of the previous studies (such as 30.2 g kg-1 fuel of CO EF compared to 2.17 to 19.5 g kg-1 fuel in previous studies, 115 g kg-1 fuel of NOx EF compared to 22.3 to 87 g kg-1 fuel in previous studies and 9.40 g kg-1 fuel of PM EF compared to 1.2 to 7.6 g kg-1 fuel in previous studies), while for the two higher-engine-power vessels (DFH and XYH), most of the average emission factors for pollutants were comparable to the results of the previous studies, engine type was

Exposure to fine particulate, black carbon, and particle number concentration in transportation microenvironments

Science.gov (United States)

Morales Betancourt, R.; Galvis, B.; Balachandran, S.; Ramos-Bonilla, J. P.; Sarmiento, O. L.; Gallo-Murcia, S. M.; Contreras, Y.

2017-05-01

This research determined intake dose of fine particulate matter (PM2.5), equivalent black carbon (eBC), and number of sub-micron particles (Np) for commuters in Bogotá, Colombia. Doses were estimated through measurements of exposure concentration, a surrogate of physical activity, as well as travel times and speeds. Impacts of travel mode, traffic load, and street configuration on dose and exposure were explored. Three road segments were selected because of their different traffic loads and composition, and dissimilar street configuration. The transport modes considered include active modes (walking and cycling) and motorized modes (bus, car, taxi, and motorcycle). Measurements were performed simultaneously in the available modes at each road segment. High average eBC concentrations were observed throughout the campaign, ranging from 20 to 120 μgm-3 . Commuters in motorized modes experienced significantly higher exposure concentrations than pedestrians and bicyclists. The highest average concentrations of PM2.5, eBC , and Np were measured inside the city's Bus Rapid Transit (BRT) system vehicles. Pedestrians and bicycle users in an open street configuration were exposed to the lowest average concentrations of PM2.5 and eBC , six times lower than those experienced by commuters using the BRT in the same street segment. Pedestrians experienced the highest particulate matter intake dose in the road segments studied, despite being exposed to lower concentrations than commuters in motorized modes. Average potential dose of PM2.5 and eBC per unit length traveled were nearly three times higher for pedestrians in a street canyon configuration compared to commuters in public transport. Slower travel speed and elevated inhalation rates dominate PM dose for pedestrians. The presence of dedicated bike lanes on sidewalks has a significant impact on reducing the exposure concentration for bicyclists compared to those riding in mixed traffic lanes. This study proposes a simple

Predicting ambient aerosol thermal-optical reflectance (TOR) measurements from infrared spectra: organic carbon

Science.gov (United States)

Dillner, A. M.; Takahama, S.

2015-03-01

Organic carbon (OC) can constitute 50% or more of the mass of atmospheric particulate matter. Typically, organic carbon is measured from a quartz fiber filter that has been exposed to a volume of ambient air and analyzed using thermal methods such as thermal-optical reflectance (TOR). Here, methods are presented that show the feasibility of using Fourier transform infrared (FT-IR) absorbance spectra from polytetrafluoroethylene (PTFE or Teflon) filters to accurately predict TOR OC. This work marks an initial step in proposing a method that can reduce the operating costs of large air quality monitoring networks with an inexpensive, non-destructive analysis technique using routinely collected PTFE filter samples which, in addition to OC concentrations, can concurrently provide information regarding the composition of organic aerosol. This feasibility study suggests that the minimum detection limit and errors (or uncertainty) of FT-IR predictions are on par with TOR OC such that evaluation of long-term trends and epidemiological studies would not be significantly impacted. To develop and test the method, FT-IR absorbance spectra are obtained from 794 samples from seven Interagency Monitoring of PROtected Visual Environment (IMPROVE) sites collected during 2011. Partial least-squares regression is used to calibrate sample FT-IR absorbance spectra to TOR OC. The FTIR spectra are divided into calibration and test sets by sampling site and date. The calibration produces precise and accurate TOR OC predictions of the test set samples by FT-IR as indicated by high coefficient of variation (R2; 0.96), low bias (0.02 μg m-3, the nominal IMPROVE sample volume is 32.8 m3), low error (0.08 μg m-3) and low normalized error (11%). These performance metrics can be achieved with various degrees of spectral pretreatment (e.g., including or excluding substrate contributions to the absorbances) and are comparable in precision to collocated TOR measurements. FT-IR spectra are also

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

Organic carbon and nitrogen export from a tropical dam-impacted floodplain system

Science.gov (United States)

Zurbrügg, R.; Suter, S.; Lehmann, M. F.; Wehrli, B.; Senn, D. B.

2013-01-01

Tropical floodplains play an important role in organic matter transport, storage, and transformation between headwaters and oceans. However, the fluxes and quality of organic carbon (OC) and organic nitrogen (ON) in tropical river-floodplain systems are not well constrained. We explored the quantity and characteristics of dissolved and particulate organic matter (DOM and POM, respectively) in the Kafue River flowing through the Kafue Flats (Zambia), a tropical river-floodplain system in the Zambezi River basin. During the flooding season, > 80% of the Kafue River water passed through the floodplain, mobilizing large quantities of OC and ON, which resulted in a net export of 69-119 kg OC km-2 d-1 and 3.8-4.7 kg ON km-2 d-1, 80% of which was in the dissolved form. The elemental C : N ratio of ~ 20, the comparatively high δ13C values of -25‰ to -21‰, and its spectroscopic properties (excitation-emission matrices) showed that DOM in the river was mainly of terrestrial origin. Despite a threefold increase in OC loads due to inputs from the floodplain, the characteristics of the riverine DOM remained relatively constant along the sampled 410-km river reach. This suggests that floodplain DOM displayed properties similar to those of DOM leaving the upstream reservoir and implied that the DOM produced in the reservoir was relatively short-lived. In contrast, the particulate fraction was 13C-depleted (-29‰) and had a C : N ratio of ~ 8, which indicated that POM originated from phytoplankton production in the reservoir and in the floodplain, rather than from plant debris or resuspended sediments. While the upstream dam had little effect on the DOM pool, terrestrial particles were retained, and POM from algal and microbial sources was released to the river. A nitrogen mass balance over the 2200 km2 flooded area revealed an annual deficit of 15 500-22 100 t N in the Kafue Flats. The N isotope budget suggests that these N losses are balanced by intense N-fixation. Our

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

Organic carbon dynamics in mangrove ecosystems: a review

NARCIS (Netherlands)

Kristensen, E.; Bouillon, S.; Dittmar, T.; Marchand, C.

2008-01-01

Our current knowledge on production, composition, transport, pathways and transformations of organic carbon in tropical mangrove environments is reviewed and discussed. Organic carbon entering mangrove foodwebs is either produced autochthonously or imported by tides and/or rivers. Mangrove litter

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)

Size, Composition, and Sources of Health Relevant Particulate Matter in the San Joaquin Valley

Science.gov (United States)

Ham, Walter Allan

Particulate Matter (PM) is an environment contaminant that has been associated with adverse health effects in epidemiological and toxicological studies. Atmospheric PM is made up of a diverse array of chemical species that are emitted from multiple sources across a range of aerodynamic diameters spanning several orders of magnitude. The focus of the present work was the characterization of ambient PM with aerodynamic diameters below 1.8 mum (PM1.8) in 6 size sub-fractions including PM0.1. Chemical species measured included organic carbon, elemental carbon, water soluble ions, trace metals, and organic molecular markers in urban and rural environments in the San Joaquin Valley. These measurements were used to determine differences in relative diurnal size distributions during a severe winter stagnation event, seasonal changes in PM size and composition, and the source origin of carbonaceous PM. This size-resolved information was used to calculate lung deposition patterns of health relevant PM species to evaluate seasonal differences in PM dose. By accurately calculating PM dose, researchers are able to more directly link ambient PM characterization data with biological endpoints. All of these results are used to support ongoing toxicological health effects studies. These types of analyses are important as this type of information may assist regulators with developing control strategies to reduce health effects caused by particulate air pollution.

Exoenzyme activities as indicators of dissolved organic matter composition in the hyporheic zone of a floodplain river

Science.gov (United States)

Sandra M. Clinton; Rick T. Edwards; Stuart E.G. Findlay

2010-01-01

We measured the hyporheic microbial exoenzyme activities in a floodplain river to determine whether dissolved organic matter (DOM) bioavailability varied with overlying riparian vegetation patch structure or position along flowpaths. Particulate organic matter (POM), dissolved organic carbon (DOC), dissolved oxygen (DO), electrical conductivity and temperature were...

Implication of POC/234Th ratios in oceanic particulate matter. An approach to particle aggregation

International Nuclear Information System (INIS)

Hirose, Katumi

2003-01-01

234 Th has been widely applied as a tracer of particulate organic carbon (POC) fluxes in the upper ocean. Fundamental to this approach is the determination of 234 Th fluxes from water column measurements of the 234 Th- 238 U disequilibria, and the conversion of 234 Th flux to POC export, using the measured POC/ 234 Th ratio on particles. As such, POC/ 234 Th ratios are one of the most critical factors in quantifying the carbon export flux in ocean interior when using this approach. However, the POC/ 234 Th ratios show significant temporal and spatial variations, but cannot be predicted at this time. therefore, it is important to elucidate factors controlling the variations of the POC/ 234 Th ratios. To achieve this purpose, we should understand the chemical interactions between POC and 234 Th. In the open ocean, POC/ 234 Th ratios have been determined together with other oceanographic parameters. We examined here the relationship between POC/ 234 Th and primary production. The POC/ 234 Th ratios were linearly related to logarithmic values of primary production. Taken into account the complexation between surface ligand on particulate organic matter (POM) and 234 Th, a complexation model suggests that the size of particles adsorbing 234 Th is related to primary production; in the equatorial Pacific, the size of particles adsorbing 234 Th apparently decreases with increasing primary production, whereas opposite phenomenon occurs in the North Atlantic. Since the POC/ 234 Th ratios were determined in filtered particulate matter, this finding suggests that aggregation of small particles would be dominant in the equatorial Pacific, which can be explained by a chemical aggregation model. (author)

Response of Microbial Soil Carbon Mineralization Rates to Oxygen Limitations

Science.gov (United States)

Keiluweit, M.; Denney, A.; Nico, P. S.; Fendorf, S. E.

2014-12-01

The rate of soil organic matter (SOM) mineralization is known to be controlled by climatic factors as well as molecular structure, mineral-organic associations, and physical protection. What remains elusive is to what extent oxygen (O2) limitations impact overall rates of microbial SOM mineralization (oxidation) in soils. Even within upland soils that are aerobic in bulk, factors limiting O2 diffusion such as texture and soil moisture can result in an abundance of anaerobic microsites in the interior of soil aggregates. Variation in ensuing anaerobic respiration pathways can further impact SOM mineralization rates. Using a combination of (first) aggregate model systems and (second) manipulations of intact field samples, we show how limitations on diffusion and carbon bioavailability interact to impose anaerobic conditions and associated respiration constraints on SOM mineralization rates. In model aggregates, we examined how particle size (soil texture) and amount of dissolved organic carbon (bioavailable carbon) affect O2 availability and distribution. Monitoring electron acceptor profiles (O2, NO3-, Mn and Fe) and SOM transformations (dissolved, particulate, mineral-associated pools) across the resulting redox gradients, we then determined the distribution of operative microbial metabolisms and their cumulative impact on SOM mineralization rates. Our results show that anaerobic conditions decrease SOM mineralization rates overall, but those are partially offset by the concurrent increases in SOM bioavailability due to transformations of protective mineral phases. In intact soil aggregates collected from soils varying in texture and SOM content, we mapped the spatial distribution of anaerobic microsites. Optode imaging, microsensor profiling and 3D tomography revealed that soil texture regulates overall O2 availability in aggregate interiors, while particulate SOM in biopores appears to control the fine-scale distribution of anaerobic microsites. Collectively, our

Black carbon, organic carbon, and co-pollutant emissions and energy efficiency from artisanal brick production in Mexico

Science.gov (United States)

Zavala, Miguel; Molina, Luisa T.; Maiz, Pablo; Monsivais, Israel; Chow, Judith C.; Watson, John G.; Munguia, Jose Luis; Cardenas, Beatriz; Fortner, Edward C.; Herndon, Scott C.; Roscioli, Joseph R.; Kolb, Charles E.; Knighton, Walter B.

2018-04-01

In many parts of the developing world and economies in transition, small-scale traditional brick kilns are a notorious source of urban air pollution. Many are both energy inefficient and burn highly polluting fuels that emit significant levels of black carbon (BC), organic carbon (OC) and other atmospheric pollutants into local communities, resulting in severe health and environmental impacts. However, only a very limited number of studies are available on the emission characteristics of brick kilns; thus, there is a need to characterize their gaseous and particulate matter (PM) emission factors to better assess their overall contribution to emissions inventories and to quantify their ecological, human health, and climate impacts. In this study, the fuel-, energy-, and brick-based emissions factors and time-based emission ratios of BC, OC, inorganic PM components, CO, SO2, CH4, NOx, and selected volatile organic compounds (VOCs) from three artisanal brick kilns with different designs in Mexico were quantified using the tracer ratio sampling technique. Simultaneous measurements of PM components, CO, and CO2 were also obtained using a sampling probe technique. Additional measurements included the internal temperature of the brick kilns, mechanical resistance of bricks produced, and characteristics of fuels employed. Average fuel-based BC emission factors ranged from 0.15 to 0.58 g (kg fuel)-1, whereas BC/OC mass ratios ranged from 0.9 to 5.2, depending on the kiln type. The results show that both techniques capture similar temporal profiles of the brick kiln emissions and produce comparable emission factors. A more integrated inter-comparison of the brick kilns' performances was obtained by simultaneously assessing emissions factors, energy efficiency, fuel consumption, and the quality of the bricks produced.

[Effects of different cultivation patterns on soil aggregates and organic carbon fractions].

Science.gov (United States)

Qiu, Xiao-Lei; Zong, Liang-Gang; Liu, Yi-Fan; Du, Xia-Fei; Luo, Min; Wang, Run-Chi

2015-03-01

Combined with the research in an organic farm in the past 10 years, differences of soil aggregates composition, distribution and organic carbon fractions between organic and conventional cultivation were studied by simultaneous sampling analysis. The results showed that the percentages of aggregates (> 1 mm, 1-0.5 mm, 0.5-0.25 mm and organic cultivation were 9.73%, 18.41%, 24.46% and 43.90%, respectively. The percentage of organic cultivation than that in conventional cultivation. Organic cultivation increased soil organic carbon (average of 17.95 g x kg(-1)) and total nitrogen contents (average of 1.51 g x kg(-1)). Among the same aggregates in organic cultivation, the average content of heavy organic carbon fraction was significantly higher than that in conventional cultivation. This fraction accumulated in organic carbon. In organic cultivation, the content of labile organic carbon in > 1 mm macro-aggregates was significantly higher than that in conventional cultivation, while no significant difference was found among the other aggregates, indicating that the labile organic carbon was enriched in > 1 mm macro-aggregates. Organic cultivation increased the amounts of organic carbon and its fractions, reduced tillage damage to aggregates, and enhanced the stability of organic carbon. Organic cultivation was therefore beneficial for soil carbon sequestration. The findings of this research may provide theoretical basis for further acceleration of the organic agriculture development.

Insights in groundwater organic matter from Liquid Chromatography-Organic Carbon Detection

Science.gov (United States)

Rutlidge, H.; Oudone, P.; McDonough, L.; Andersen, M. S.; Baker, A.; Meredith, K.; O'Carroll, D. M.

2017-12-01

Understanding the processes that control the concentration and characteristics of organic matter in groundwater has important implications for the terrestrial global carbon budget. Liquid Chromatography - Organic Carbon Detection (LC-OCD) is a size-exclusion based chromatography technique that separates the organic carbon into molecular weight size fractions of biopolymers, humic substances, building blocks (degradation products of humic substances), low molecular weight acids and low molecular weight neutrals. Groundwater and surface water samples were collected from a range of locations in Australia representing different surface soil, land cover, recharge type and hydrological properties. At one site hyporheic zone samples were also collected from beneath a stream. The results showed a general decrease in the aromaticity and molecular weight indices going from surface water, hyporheic downwelling and groundwater samples. The aquifer substrate also affected the organic composition. For example, groundwater samples collected from a zone of fractured rock showed a relative decrease in the proportion of humic substances, suggestive of sorption or degradation of humic substances. This work demonstrates the potential for using LC-OCD in elucidating the processes that control the concentration and characteristics of organic matter in groundwater.

Ammonia, hydrogen sulfide, carbon dioxide and particulate matter emissions from California high-rise layer houses

Science.gov (United States)

Lin, X.-J.; Cortus, E. L.; Zhang, R.; Jiang, S.; Heber, A. J.

2012-01-01

Ammonia and hydrogen sulfide are hazardous substances that are regulated by the U.S. Environmental Protection Agency through community right-to-know legislation (EPCRA, EPA, 2011). The emissions of ammonia and hydrogen sulfide from large commercial layer facilities are of concern to legislators and nearby neighbors. Particulate matter (PM 10 and PM 2.5) released from layer houses are two of seven criteria pollutants for which EPA has set National Ambient Air Quality Standards as required by the Clean Air Act. Therefore, it is important to quantify the baseline emissions of these pollutants. The emissions of ammonia, hydrogen sulfide, carbon dioxide and PM from two California high-rise layer houses were monitored for two years from October 2007 to October 2009. Each house had 32,500 caged laying hens. The monitoring site was setup in compliance with a U.S. EPA-approved quality assurance project plan. The results showed the average daily mean emission rates of ammonia, hydrogen sulfide and carbon dioxide were 0.95 ± 0.67 (standard deviation) g d -1 bird -1, 1.27 ± 0.78 mg d -1 bird -1 and 91.4 ± 16.5 g d -1 bird -1, respectively. The average daily mean emission rates of PM 2.5, PM 10 and total suspended particulate (TSP) were 5.9 ± 12.6, 33.4 ± 27.4, and 78.0 ± 42.7 mg d -1 bird -1, respectively. It was observed that ammonia emission rates in summer were lower than in winter because the high airflow stabilized the manure by drying it. The reductions due to lower moisture content were greater than the increases due to higher temperature. However, PM 10 emission rates in summer were higher than in winter because the drier conditions coupled with higher internal air velocities increased PM 10 release from feathers, feed and manure.

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.

Field evaluation of diesel particulate matter using portable elemental carbon monitors

Energy Technology Data Exchange (ETDEWEB)

Janisko, S.; Noll, J.D. [National Inst. for Occupational Safety and Health, Pittsburgh, PA (United States)

2010-07-01

The permissible exposure limits of underground mine workers to diesel particulate matter (DPM) was lowered in 2008 by the United States Mine Safety and Health Administration. In order to comply with the new regulation, most mines must use one or several combined control strategies to lower DPM concentrations. Since DPMs are complex and unpredictable, there is a need for new tools to help mines develop an effective strategy to reduce their concentrations. This paper reported on newly developed portable elemental carbon (EC) monitoring device for use in underground mines. This compact instrument was developed by the National Institute for Occupational Safety and Health to monitor EC concentrations in real time. The device has proven to be useful in planning new DPM curtailment strategies and in measuring the effectiveness of existing DPM controls. The information is provided in charts of concentration changes over time. The data offers a new way of understanding the factors that influence DPM exposure and drive concentration transients in an underground environment. 14 refs., 6 figs.

Organic carbon in Hanford single-shell tank waste

International Nuclear Information System (INIS)

Toth, J.J.; Willingham, C.E.; Heasler, P.G.; Whitney, P.D.

1994-04-01

Safety of Hanford single-shell tanks (SSTs) containing organic carbon is a concern because the carbon in the presence of oxidizers (NO 3 or NO 2 ) is combustible when sufficiently concentrated and exposed to elevated temperatures. A propagating chemical reaction could potentially occur at high temperature (above 200 C). The rapid increase in temperature and pressure within a tank might result in the release of radioactive waste constituents to the environment. The purpose of this study is to gather available laboratory information about the organic carbon waste inventories stored in the Hanford SSTs. Specifically, the major objectives of this investigation are: Review laboratory analytical data and measurements for SST composite core and supernatant samples for available organic data; Assess the correlation of organic carbon estimated utilizing the TRAC computer code compared to laboratory measurements; and From the laboratory analytical data, estimate the TOC content with confidence levels for each of the 149 SSTs

Organic carbon fluxes in stemflow, throughfall and rainfall in an olive orchard

Science.gov (United States)

Lombardo, L.; Vanwalleghem, T.; Gomez, J. A.

2012-04-01

The importance of rainfall distribution under the vegetation canopy for nutrient cycling of forest ecosystems has been widely studied (e.g. Kolkai et al., 1999, Bath et al., 2011). It has been demonstrated how throughfall and stemflow reach the soil as chemically-enriched water, by incorporating soluble organic and inorganic particles deriving from plant exudates and from atmospheric depositions (dryfall and wetfall) present on the surfaces of the plant (leaves, bark, fruits). Dissolved (DOC) and particulate (POC) organic carbon inputs from stem- and canopy-derived hydrologic fluxes are small but important components of the natural carbon cycle. DOC has also the capability to form complexes that control the transport and solubility of heavy metals in surface and ground waters, being composed for the most part (75-90%) of fulvic, humic or tanninic compounds, and for the resting part of molecules like carbohydrates, hydrocarbons, waxes, fatty acids, amino and hydroxy acids. However, very little data is available for agricultural tree crops, especially olive trees. In this sense, the objective of this work is to investigate the concentration and fluxes of organic carbon in rainfall, throughfall, and stemflow in a mature olive orchard located in Cordoba, in Southern Spain and to relate them to rainfall characteristics and tree physiology. The measurements started in October 2011. Four high density polyethylene bottles with 18-cm-diameter polyethylene funnels for throughfall collection were placed beneath the canopy of each of the three selected olive trees; four more collectors were placed in open spaces in the same orchard for rainfall sampling. Stemflow was collected through PVC spiral tubes wrapped around the trunks and leading into collection bins. The throughflow sampling points were chosen randomly. Total and dissolved organic carbon concentrations in unfiltered (TOC) and filtered (0.45 µm membrane filter, DOC) collected waters were measured using a TOC analyzer