A Thermodynamically-consistent FBA-based Approach to Biogeochemical Reaction Modeling

Science.gov (United States)

Shapiro, B.; Jin, Q.

2015-12-01

Microbial rates are critical to understanding biogeochemical processes in natural environments. Recently, flux balance analysis (FBA) has been applied to predict microbial rates in aquifers and other settings. FBA is a genome-scale constraint-based modeling approach that computes metabolic rates and other phenotypes of microorganisms. This approach requires a prior knowledge of substrate uptake rates, which is not available for most natural microbes. Here we propose to constrain substrate uptake rates on the basis of microbial kinetics. Specifically, we calculate rates of respiration (and fermentation) using a revised Monod equation; this equation accounts for both the kinetics and thermodynamics of microbial catabolism. Substrate uptake rates are then computed from the rates of respiration, and applied to FBA to predict rates of microbial growth. We implemented this method by linking two software tools, PHREEQC and COBRA Toolbox. We applied this method to acetotrophic methanogenesis by Methanosarcina barkeri, and compared the simulation results to previous laboratory observations. The new method constrains acetate uptake by accounting for the kinetics and thermodynamics of methanogenesis, and predicted well the observations of previous experiments. In comparison, traditional methods of dynamic-FBA constrain acetate uptake on the basis of enzyme kinetics, and failed to reproduce the experimental results. These results show that microbial rate laws may provide a better constraint than enzyme kinetics for applying FBA to biogeochemical reaction modeling.

Solar System Chaos and its climatic and biogeochemical consequences

Science.gov (United States)

Ikeda, M.; Tada, R.; Ozaki, K.; Olsen, P. E.

2017-12-01

Insolation changes caused by changes in Earth's orbital parameters are the main driver of climatic variations, whose pace has been used for astronomically-calibrated geologic time scales of high accuracy to understand Earth system dynamics. However, the astrophysical models beyond several tens of million years ago have large uncertainty due to chaotic behavior of the Solar System, and its impact on amplitude modulation of multi-Myr-scale orbital variations and consequent climate changes has become the subject of debate. Here we show the geologic constraints on the past chaotic behavior of orbital cycles from early Mesozoic monsoon-related records; the 30-Myr-long lake level records of the lacustrine sequence in Newark-Hartford basins (North America) and 70-Myr-long biogenic silica (BSi) burial flux record of pelagic deep-sea chert sequence in Inuyama area (Japan). BSi burial flux of chert could be considered as proportional to the dissolved Si (DSi) input from chemical weathering on timescales longer than the residence time of DSi ( 100 kyr), because chert could represent a major sink for oceanic dissolved silica (Ikeda et al., 2017).These geologic records show multi-Myr cycles with similar frequency modulations of eccentricity solution of astronomical model La2010d (Laskar et al., 2011) compared with other astronomical solutions, but not exactly same. Our geologic records provide convincing evidence for the past chaotic dynamical behaviour of the Solar System and new and challenging additional constraints for astrophysical models. In addition, we find that ˜10 Myr cycle detected in monsoon proxies and their amplitude modulation of ˜2 Myr cycle may be related to the amplitude modulation of ˜2 Myr eccentricity cycle through non-linear process(es) of Earth system dynamics, suggesting possible impact of the chaotic behavior of Solar planets on climate change. Further impact of multi-Myr orbital cycles on global biogeochemical cycles will be discussed.

Understanding system disturbance and ecosystem services in restored saltmarshes: Integrating physical and biogeochemical processes

Science.gov (United States)

Spencer, K. L.; Harvey, G. L.

2012-06-01

Coastal saltmarsh ecosystems occupy only a small percentage of Earth's land surface, yet contribute a wide range of ecosystem services that have significant global economic and societal value. These environments currently face significant challenges associated with climate change, sea level rise, development and water quality deterioration and are consequently the focus of a range of management schemes. Increasingly, soft engineering techniques such as managed realignment (MR) are being employed to restore and recreate these environments, driven primarily by the need for habitat (re)creation and sustainable coastal flood defence. Such restoration schemes also have the potential to provide additional ecosystem services including climate regulation and waste processing. However, these sites have frequently been physically impacted by their previous land use and there is a lack of understanding of how this 'disturbance' impacts the delivery of ecosystem services or of the complex linkages between ecological, physical and biogeochemical processes in restored systems. Through the exploration of current data this paper determines that hydrological, geomorphological and hydrodynamic functioning of restored sites may be significantly impaired with respects to natural 'undisturbed' systems and that links between morphology, sediment structure, hydrology and solute transfer are poorly understood. This has consequences for the delivery of seeds, the provision of abiotic conditions suitable for plant growth, the development of microhabitats and the cycling of nutrients/contaminants and may impact the delivery of ecosystem services including biodiversity, climate regulation and waste processing. This calls for a change in our approach to research in these environments with a need for integrated, interdisciplinary studies over a range of spatial and temporal scales incorporating both intensive and extensive research design.

Hyporheic zone as a bioreactor: sediment heterogeneity influencing biogeochemical processes

Science.gov (United States)

Perujo, Nuria; Romani, Anna M.; Sanchez-Vila, Xavier

2017-04-01

Mediterranean fluvial systems are characterized by frequent periods of low flow or even drought. During low flow periods, water from wastewater treatment plants (WWTPs) is proportionally large in fluvial systems. River water might be vertically transported through the hyporheic zone, and then porous medium acts as a complementary treatment system since, as water infiltrates, a suite of biogeochemical processes occurs. Subsurface sediment heterogeneity plays an important role since it influences the interstitial fluxes of the medium and drives biomass growing, determining biogeochemical reactions. In this study, WWTP water was continuously infiltrated for 3 months through two porous medium tanks: one consisting of 40 cm of fine sediment (homogeneous); and another comprised of two layers of different grain size sediments (heterogeneous), 20 cm of coarse sediment in the upper part and 20 cm of fine one in the bottom. Several hydrological, physicochemical and biological parameters were measured periodically (weekly at the start of the experiment and biweekly at the end). Analysed parameters include dissolved nitrogen, phosphorus, organic carbon, and oxygen all measured at the surface, and at 5, 20 and 40 cm depth. Variations in hydraulic conductivity with time were evaluated. Sediment samples were also analysed at three depths (surface, 20 and 40 cm) to determine bacterial density, chlorophyll content, extracellular polymeric substances, and biofilm function (extracellular enzyme activities and carbon substrate utilization profiles). Preliminary results suggest hydraulic conductivity to be the main driver of the differences in the biogeochemical processes occurring in the subsurface. At the heterogeneous tank, a low nutrient reduction throughout the whole medium is measured. In this medium, high hydraulic conductivity allows for a large amount of infiltrating water, but with a small residence time. Since some biological processes are largely time-dependent, small water

Ecotoxicological, ecophysiological and biogeochemical fundamentals of risk assessment

International Nuclear Information System (INIS)

Bashkin, V.; Evstafjeva, E.

1995-01-01

A quantitative risk assessment (RA) for complex influence of different factors in heavy polluted regions is possible to carry out only on a basis of determination of various links of biogeochemical trophical chains and analysis of the whole biogeochemical structure of the region under study. As an integrative assessment, the human adaptability should be chosen because the majority of trophical chains are closed by man. The given integrative criteria includes biogeochemical, ecophysiological and ecotoxicological assessment of risk factors. Consequently, ecological-biogeochemical regionalization, ecophysiological and ecotoxicological monitoring of human population health are the important approaches to RA. These criteria should be conjugated with LCA of various industrial and agricultural products. At the ultimate degree, the given approaches are needed for areas where traditional pollutants (heavy metals, POPS, pesticides, fertilizers) are enforced sharply by radioactive pollution. Due to the complex influence of pollutants, it is impossible to use individual guidelines. For RA of these complex pollutants, the methods of human adaptability assessment to a polluted environment have to be carried out. These methods include biogeochemical, ecotoxicological and ecophysiological analysis of risk factors as well as quantitative uncertainty analysis. Furthermore, the modern statistical methods such as correlative graphs etc., have to be used for quantitative assessment of human adaptability to complex influence of pollutants. The results obtained in the Chernobyl region have shown the acceptability of suggested methods

Green Infrastructure Increases Biogeochemical Responsiveness, Vegetation Growth and Decreases Runoff in a Semi-Arid City, Tucson, AZ, USA

Science.gov (United States)

Meixner, T.; Papuga, S. A.; Luketich, A. M.; Rockhill, T.; Gallo, E. L.; Anderson, J.; Salgado, L.; Pope, K.; Gupta, N.; Korgaonkar, Y.; Guertin, D. P.

2017-12-01

Green Infrastructure (GI) is often viewed as a mechanism to minimize the effects of urbanization on hydrology, water quality, and other ecosystem services (including the urban heat island). Quantifying the effects of GI requires field measurements of the dimensions of biogeochemical, ecosystem, and hydrologic function that we expect GI to impact. Here we investigated the effect of GI features in Tucson, Arizona which has a low intensity winter precipitation regime and a high intensity summer regime. We focused on understanding the effect of GI on soil hydraulic and biogeochemical properties as well as the effect on vegetation and canopy temperature. Our results demonstrate profound changes in biogeochemical and hydrologic properties and vegetation growth between GI systems and nearby control sites. In terms of hydrologic properties GI soils had increased water holding capacity and hydraulic conductivity. GI soils also have higher total carbon, total nitrogen, and organic matter in general than control soils. Furthermore, we tested the sampled soils (control and GI) for differences in biogeochemical response upon wetting. GI soils had larger respiration responses indicating greater biogeochemical activity overall. Long-term Lidar surveys were used to investigate the differential canopy growth of GI systems versus control sites. The results of this analysis indicate that while a significant amount of time is needed to observe differences in canopy growth GI features due increase tree size and thus likely impact street scale ambient temperatures. Additionally monitoring of transpiration, soil moisture, and canopy temperature demonstrates that GI features increase vegetation growth and transpiration and reduce canopy temperatures. These biogeochemical and ecohydrologic results indicate that GI can increase the biogeochemical processing of soils and increase tree growth and thus reduce urban ambient temperatures.

Enhanced biogeochemical cycling and subsequent reduction of hydraulic conductivity associated with soil-layer interfaces in the vadose zone

Science.gov (United States)

Hansen, David J.; McGuire, Jennifer T.; Mohanty, Binayak P.

2013-01-01

Biogeochemical dynamics in the vadose zone are poorly understood due to the transient nature of chemical and hydrologic conditions, but are nonetheless critical to understanding chemical fate and transport. This study explored the effects of a soil layer on linked geochemical, hydrological, and microbiological processes. Three laboratory soil columns were constructed: a homogenized medium-grained sand, a homogenized organic-rich loam, and a sand-over-loam layered column. Upward and downward infiltration of water was evaluated during experiments to simulate rising water table and rainfall events respectively. In-situ collocated probes measured soil water content, matric potential, and Eh while water samples collected from the same locations were analyzed for Br−, Cl−, NO3−, SO42−, NH4+, Fe2+, and total sulfide. Compared to homogenous columns, the presence of a soil layer altered the biogeochemistry and water flow of the system considerably. Enhanced biogeochemical cycling was observed in the layered column over the texturally homogeneous soil columns. Enumerations of iron and sulfate reducing bacteria showed 1-2 orders of magnitude greater community numbers in the layered column. Mineral and soil aggregate composites were most abundant near the soil-layer interface; the presence of which, likely contributed to an observed order-of-magnitude decrease in hydraulic conductivity. These findings show that quantifying coupled hydrologic-biogeochemical processes occurring at small-scale soil interfaces is critical to accurately describing and predicting chemical changes at the larger system scale. Findings also provide justification for considering soil layering in contaminant fate and transport models because of its potential to increase biodegradation and/or slow the rate of transport of contaminants. PMID:22031578

Molecular biogeochemical provinces in the Atlantic Surface Ocean

Science.gov (United States)

Koch, B. P.; Flerus, R.; Schmitt-Kopplin, P.; Lechtenfeld, O. J.; Bracher, A.; Cooper, W.; Frka, S.; Gašparović, B.; Gonsior, M.; Hertkorn, N.; Jaffe, R.; Jenkins, A.; Kuss, J.; Lara, R. J.; Lucio, M.; McCallister, S. L.; Neogi, S. B.; Pohl, C.; Roettgers, R.; Rohardt, G.; Schmitt, B. B.; Stuart, A.; Theis, A.; Ying, W.; Witt, M.; Xie, Z.; Yamashita, Y.; Zhang, L.; Zhu, Z. Y.; Kattner, G.

2010-12-01

One of the most important aspects to understand marine organic carbon fluxes is to resolve the molecular mechanisms which convert fresh, labile biomolecules into semi-labile and refractory dissolved and particulate organic compounds in the ocean. In this interdisciplinary project, which was performed on a cruise with RV Polarstern, we carried out a detailed molecular characterisation of dissolved organic matter (DOM) on a North-South transect in the Atlantic surface ocean in order to relate the data to different biological, climatic, oceanographic, and meteorological regimes as well as to terrestrial input from riverine and atmospheric sources. Our goal was to achieve a high resolution data set for the biogeochemical characterisation of the sources and reactivity of DOM. We applied ultrahigh resolution Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR-MS), nutrient, trace element, amino acid, and lipid analyses and other biogeochemical measurements for 220 samples from the upper water column (0-200m) and eight deep profiles. Various spectroscopic techniques were applied continuously in a constant sample water flow supplied by a fish system and the moon pool. Radiocarbon dating enabled assessing DOC residence time. Bacterial abundance and production provided a metabolic context for the DOM characterization work and pCO2 concentrations. Combining molecular organic techniques and inductively coupled plasma mass spectrometry (ICP-MS) established an important link between organic and inorganic biogeochemical studies. Multivariate statistics, primarily based on FT-ICR-MS data for 220 samples, allowed identifying geographical clusters which matched ecological provinces proposed previously by Longhurst (2007). Our study demonstrated that marine DOM carries molecular information reflecting the “history” of ocean water masses. This information can be used to define molecular biogeochemical provinces and to improve our understanding of element fluxes in

Investigating the Role of Biogeochemical Processes in the Northern High Latitudes on Global Climate Feedbacks Using an Efficient Scalable Earth System Model

Energy Technology Data Exchange (ETDEWEB)

Jain, Atul K. [Univ. of Illinois, Urbana-Champaign, IL (United States)

2016-09-14

The overall objectives of this DOE funded project is to combine scientific and computational challenges in climate modeling by expanding our understanding of the biogeophysical-biogeochemical processes and their interactions in the northern high latitudes (NHLs) using an earth system modeling (ESM) approach, and by adopting an adaptive parallel runtime system in an ESM to achieve efficient and scalable climate simulations through improved load balancing algorithms.

Organochlorine compounds and the biogeochemical cycle of chlorine in soils: A review

Science.gov (United States)

Vodyanitskii, Yu. N.; Makarov, M. I.

2017-09-01

Chloride ions in soil may interact with soil organic matter and form organochlorine compounds in situ. The biotic chlorination of soil organic substances takes places under aerobic conditions with participation of H2O2 forming from peroxidases released by soil microorganisms (in particular, by microscopic fungi). The abiotic chlorination results also from the redox reactions with the participation of Fe3+/Fe2+ system, but it develops several times slower. Chlorination of soil organic substances is favored by Cl- coming to soil both from natural (salinized soil-forming rocks and groundwater, sea salt) and anthropogenic sources of chlorides, i.e., spills of saline water at oil production, road deicing chemicals, mineral fertilizers, etc. The study of the biogeochemical chlorine cycle should take into account the presence of organochlorine compounds in soils, in addition to transformation and migration of chloride ions.

The Seasonal Cycle of Carbon in the Southern Pacific Ocean Observed from Biogeochemical Profiling Floats

Science.gov (United States)

Sarmiento, J. L.; Gray, A. R.; Johnson, K. S.; Carter, B.; Riser, S.; Talley, L. D.; Williams, N. L.

2016-02-01

The Southern Ocean is thought to play an important role in the ocean-atmosphere exchange of carbon dioxide and the uptake of anthropogenic carbon dioxide. However, the total number of observations of the carbonate system in this region is small and heavily biased towards the summer. Here we present 1.5 years of biogeochemical measurements, including pH, oxygen, and nitrate, collected by 11 autonomous profiling floats deployed in the Pacific sector of the Southern Ocean in April 2014. These floats sampled a variety of oceanographic regimes ranging from the seasonally ice-covered zone to the subtropical gyre. Using an algorithm trained with bottle measurements, alkalinity is estimated from salinity, temperature, and oxygen and then used together with the measured pH to calculate total carbon dioxide and pCO2 in the upper 1500 dbar. The seasonal cycle in the biogeochemical quantities is examined, and the factors governing pCO2 in the surface waters are analyzed. The mechanisms driving the seasonal cycle of carbon are further investigated by computing budgets of heat, carbon, and nitrogen in the mixed layer. Comparing the different regimes sampled by the floats demonstrates the complex and variable nature of the carbon cycle in the Southern Ocean.

Biogeochemical stability and reactions of iron-organic carbon complexes

Science.gov (United States)

Yang, Y.; Adhikari, D.; Zhao, Q.; Dunham-Cheatham, S.; Das, K.; Mejia, J.; Huang, R.; Wang, X.; Poulson, S.; Tang, Y.; Obrist, D.; Roden, E. E.

2017-12-01

Our core hypothesis is that the degradation rate of soil organic carbon (OC) is governed by the amount of iron (Fe)-bound OC, and the ability of microbial communities to utilize OC as an energy source and electron shuttle for Fe reduction that in turn stimulates reductive release of Fe-bound labile dissolved OC. This hypothesis is being systematically evaluated using model Fe-OC complexes, natural soils, and microcosm system. We found that hematite-bound aliphatic C was more resistant to reduction release, although hematite preferred to sorb more aromatic C. Resistance to reductive release represents a new mechanism that aliphatic soil OC was stabilized by association with Fe oxide. In other studies, pyrogenic OC was found to facilitate the reduction of hematite, by enhancing extracellular electron transport and sorbing Fe(II). For ferrihydrite-OC co-precipitates, the reduction of Fe and release of OC was closely governed by the C/Fe ratio in the system. Based on the XPS, XANES and XAFS analysis, the transformation of Fe speciation was heterogeneous, depending on the conformation and composition of Fe-OC complexes. For natural soils, we investigated the quantity, characteristics, and reactivity of Fe-bound OC in soils collected from 14 forests in the United States. Fe-bound OC contributed up to 57.8% of total OC in the forest soils. Under the anaerobic conditions, the reduction of Fe was positively correlated to the electron accepting capacity of OC. Our findings highlight the closely coupled dynamics of Fe and OC, with broad implications on the turnover of OC and biogeochemical cycles of Fe.

Geophysical Monitoring of Hydrological and Biogeochemical Transformations associated with Cr(VI) Bioremediation

International Nuclear Information System (INIS)

Hubbard, Susan; Williams, Kenneth H.; Conrad, Mark E.; Faybishenko, Boris; Peterson, John; Chen, Jinsong; Long, Philip E.; Hazen, Terry C.

2008-01-01

Understanding how hydrological and biogeochemical properties change over space and time in response to remedial treatments is hindered by our ability to monitor these processes with sufficient resolution and over field relevant scales. Here, we explored the use of geophysical approaches for monitoring the spatiotemporal distribution of hydrological and biogeochemical transformations associated with a Cr(VI)bioremediation experiment performed at Hanford, WA. We first integrated hydrological wellbore and geophysical tomographic datasets to estimate hydrological zonation at the study site. Using results from laboratory biogeophysical experiments and constraints provided by field geochemical datasets, we then interpreted time-lapse seismic and radar tomographic datasets, collected during thirteen acquisition campaigns over a three year experimental period, in terms of hydrological and biogeochemical transformations. The geophysical monitoring datasets were used to infer: the spatial distribution of injected electron donor; the evolution of gas bubbles; variations in total dissolved solids (nitrate and sulfate) as a function of pumping activity; the formation of precipitates and dissolution of calcites; and concomitant changes in porosity. Although qualitative in nature, the integrated interpretation illustrates how geophysical techniques have the potential to provide a wealth of information about coupled hydrobiogeochemical responses to remedial treatments in high spatial resolution and in a minimally invasive manner. Particularly novel aspects of our study include the use of multiple lines of evidence to constrain the interpretation of a long-term, field-scale geophysical monitoring dataset and the interpretation of the transformations as a function of hydrological heterogeneity and pumping activity

Biogeochemical interactions between of coal mine water and gas well cement

Science.gov (United States)

Gulliver, D. M.; Gardiner, J. B.; Kutchko, B. G.; Hakala, A.; Spaulding, R.; Tkach, M. K.; Ross, D.

2017-12-01

Unconventional natural gas wells drilled in Northern Appalachia often pass through abandoned coal mines before reaching the Marcellus or Utica formations. Biogeochemical interactions between coal mine waters and gas well cements have the potential to alter the cement and compromise its sealing integrity. This study investigates the mineralogical, geochemical, and microbial changes of cement cores exposed to natural coal mine waters. Static reactors with Class H Portland cement cores and water samples from an abandoned bituminous Pittsburgh coal mine simulated the cement-fluid interactions at relevant temperature for time periods of 1, 2, 4, and 6 weeks. Fluids were analyzed for cation and anion concentrations and extracted DNA was analyzed by 16S rRNA gene sequencing and shotgun sequencing. Cement core material was evaluated via scanning electron microscope. Results suggest that the sampled coal mine water altered the permeability and matrix mineralogy of the cement cores. Scanning electron microscope images display an increase in mineral precipitates inside the cement matrix over the course of the experiment. Chemistry results from the reaction vessels' effluent waters display decreases in dissolved calcium, iron, silica, chloride, and sulfate. The microbial community decreased in diversity over the 6-week experiment, with Hydrogenophaga emerging as dominant. These results provide insight in the complex microbial-fluid-mineral interactions of these environments. This study begins to characterize the rarely documented biogeochemical impacts that coal waters may have on unconventional gas well integrity.

Biogeochemical and engineered barriers for preventing spread of contaminants.

Science.gov (United States)

Baltrėnaitė, Edita; Lietuvninkas, Arvydas; Baltrėnas, Pranas

2018-02-01

The intensive industrial development and urbanization, as well as the negligible return of hazardous components to the deeper layers of the Earth, increases the contamination load on the noosphere (i.e., the new status of the biosphere, the development of which is mainly controlled by the conscious activity of a human being). The need for reducing the spread and mobility of contaminants is growing. The insights into the role of the tree in the reduction of contaminant mobility through its life cycle are presented to show an important function performed by the living matter and its products in reducing contamination. For maintaining the sustainable development, natural materials are often used as the media in the environmental protection technologies. However, due to increasing contamination intensity, the capacity of natural materials is not sufficiently high. Therefore, the popularity of engineered materials, such as biochar which is the thermochemically modified lignocellulosic product, is growing. The new approaches, based on using the contaminant footprint, as well as natural (biogeochemical) and engineered barriers for reducing contaminant migration and their application, are described in the paper.

Characterization of mixing errors in a coupled physical biogeochemical model of the North Atlantic: implications for nonlinear estimation using Gaussian anamorphosis

Directory of Open Access Journals (Sweden)

D. Béal

2010-02-01

Full Text Available In biogeochemical models coupled to ocean circulation models, vertical mixing is an important physical process which governs the nutrient supply and the plankton residence in the euphotic layer. However, vertical mixing is often poorly represented in numerical simulations because of approximate parameterizations of sub-grid scale turbulence, wind forcing errors and other mis-represented processes such as restratification by mesoscale eddies. Getting a sufficient knowledge of the nature and structure of these errors is necessary to implement appropriate data assimilation methods and to evaluate if they can be controlled by a given observation system.

In this paper, Monte Carlo simulations are conducted to study mixing errors induced by approximate wind forcings in a three-dimensional coupled physical-biogeochemical model of the North Atlantic with a 1/4° horizontal resolution. An ensemble forecast involving 200 members is performed during the 1998 spring bloom, by prescribing perturbations of the wind forcing to generate mixing errors. The biogeochemical response is shown to be rather complex because of nonlinearities and threshold effects in the coupled model. The response of the surface phytoplankton depends on the region of interest and is particularly sensitive to the local stratification. In addition, the statistical relationships computed between the various physical and biogeochemical variables reflect the signature of the non-Gaussian behaviour of the system. It is shown that significant information on the ecosystem can be retrieved from observations of chlorophyll concentration or sea surface temperature if a simple nonlinear change of variables (anamorphosis is performed by mapping separately and locally the ensemble percentiles of the distributions of each state variable on the Gaussian percentiles. The results of idealized observational updates (performed with perfect observations and neglecting horizontal correlations

Biogeochemical provinces in the global ocean based on phytoplankton growth limitation

Science.gov (United States)

Hashioka, T.; Hirata, T.; Aita, M. N.; Chiba, S.

2016-02-01

The biogeochemical province is one of the useful concepts for the comprehensive understanding of regional differences of the marine ecosystem. Various biogeochemical provinces for lower-trophic level ecosystem have been proposed using a similarity-based classification of seasonal variations of chl-a concentration typified by Longhurst 1995 and 2006. Such categorizations well capture the regional differences of seasonality as "total phytoplankton". However, background biogeochemical mechanism to characterize the province boundary is not clear. Namely, the dominant phytoplankton group is different among regions and seasons, and their physiological characteristics are significantly different among groups. Recently some pieces of new biogeochemical information are available. One is an estimation of phytoplankton community structure from satellite observation, and it makes clear the key phytoplankton type in each region. Another is an estimation of limitation factors for phytoplankton growth (e.g., nutrients, temperature, light) in each region from modeling studies. In this study, we propose new biogeochemical provinces as a combination between the dominance of phytoplankton (i.e., diatoms, nano-, pico-phytoplankton or coexistence of two/three types) and their growth limitation factors (particularly we focused on nutrient limitation; N, P, Si or Fe). In this combination, we classified the global ocean into 23 biogeochemical provinces. The result suggests that even if the same type of phytoplankton dominates, the background mechanism could be different among regions. On the contrary, even if the regions geographically separate, the background mechanism could be similar among regions. This is important to understand that region/boundary does respond to environmental change. This biogeochemical province is useful for identification of key areas for future observation.

Cyclic biogeochemical processes and nitrogen fate beneath a subtropical stormwater infiltration basin.

Science.gov (United States)

O'Reilly, Andrew M; Chang, Ni-Bin; Wanielista, Martin P

2012-05-15

A stormwater infiltration basin in north-central Florida, USA, was monitored from 2007 through 2008 to identify subsurface biogeochemical processes, with emphasis on N cycling, under the highly variable hydrologic conditions common in humid, subtropical climates. Cyclic variations in biogeochemical processes generally coincided with wet and dry hydrologic conditions. Oxidizing conditions in the subsurface persisted for about one month or less at the beginning of wet periods with dissolved O(2) and NO(3)(-) showing similar temporal patterns. Reducing conditions in the subsurface evolved during prolonged flooding of the basin. At about the same time O(2) and NO(3)(-) reduction concluded, Mn, Fe and SO(4)(2-) reduction began, with the onset of methanogenesis one month later. Reducing conditions persisted up to six months, continuing into subsequent dry periods until the next major oxidizing infiltration event. Evidence of denitrification in shallow groundwater at the site is supported by median NO(3)(-)-N less than 0.016 mg L(-1), excess N(2) up to 3 mg L(-1) progressively enriched in δ(15)N during prolonged basin flooding, and isotopically heavy δ(15)N and δ(18)O of NO(3)(-) (up to 25‰ and 15‰, respectively). Isotopic enrichment of newly infiltrated stormwater suggests denitrification was partially completed within two days. Soil and water chemistry data suggest that a biogeochemically active zone exists in the upper 1.4m of soil, where organic carbon was the likely electron donor supplied by organic matter in soil solids or dissolved in infiltrating stormwater. The cyclic nature of reducing conditions effectively controlled the N cycle, switching N fate beneath the basin from NO(3)(-) leaching to reduction in the shallow saturated zone. Results can inform design of functionalized soil amendments that could replace the native soil in a stormwater infiltration basin and mitigate potential NO(3)(-) leaching to groundwater by replicating the biogeochemical

Cyclic biogeochemical processes and nitrogen fate beneath a subtropical stormwater infiltration basin

Science.gov (United States)

O'Reilly, Andrew M.; Chang, Ni-Bin; Wanielista, Martin P.

2012-01-01

A stormwater infiltration basin in north–central Florida, USA, was monitored from 2007 through 2008 to identify subsurface biogeochemical processes, with emphasis on N cycling, under the highly variable hydrologic conditions common in humid, subtropical climates. Cyclic variations in biogeochemical processes generally coincided with wet and dry hydrologic conditions. Oxidizing conditions in the subsurface persisted for about one month or less at the beginning of wet periods with dissolved O2 and NO3- showing similar temporal patterns. Reducing conditions in the subsurface evolved during prolonged flooding of the basin. At about the same time O2 and NO3- reduction concluded, Mn, Fe and SO42- reduction began, with the onset of methanogenesis one month later. Reducing conditions persisted up to six months, continuing into subsequent dry periods until the next major oxidizing infiltration event. Evidence of denitrification in shallow groundwater at the site is supported by median NO3-–N less than 0.016 mg L-1, excess N2 up to 3 mg L-1 progressively enriched in δ15N during prolonged basin flooding, and isotopically heavy δ15N and δ18O of NO3- (up to 25‰ and 15‰, respectively). Isotopic enrichment of newly infiltrated stormwater suggests denitrification was partially completed within two days. Soil and water chemistry data suggest that a biogeochemically active zone exists in the upper 1.4 m of soil, where organic carbon was the likely electron donor supplied by organic matter in soil solids or dissolved in infiltrating stormwater. The cyclic nature of reducing conditions effectively controlled the N cycle, switching N fate beneath the basin from NO3- leaching to reduction in the shallow saturated zone. Results can inform design of functionalized soil amendments that could replace the native soil in a stormwater infiltration basin and mitigate potential NO3- leaching to groundwater by replicating the biogeochemical conditions under the observed basin.

Mangrove forests: a potent nexus of coastal biogeochemical cycling

Science.gov (United States)

Barr, J. G.; Fuentes, J. D.; Shoemaker, B.; O'Halloran, T. L.; Lin, G., Sr.; Engel, V. C.

2014-12-01

Mangrove forests cover just 0.1% of the Earth's terrestrial surface, yet they provide a disproportionate source (~10 % globally) of terrestrially derived, refractory dissolved organic carbon to the oceans. Mangrove forests are biogeochemical reactors that convert biomass into dissolved organic and inorganic carbon at unusually high rates, and many studies recognize the value of mangrove ecosystems for the substantial amounts of soil carbon storage they produce. However, questions remain as to how mangrove forest ecosystem services should be valuated and quantified. Therefore, this study addresses several objectives. First, we demonstrate that seasonal and annual net ecosystem carbon exchange in three selected mangrove forests, derived from long-term eddy covariance measurements, represent key quantities in defining the magnitude of biogeochemical cycling and together with other information on carbon cycle parameters serves as a proxy to estimate ecosystem services. Second, we model ecosystem productivity across the mangrove forests of Everglades National Park and southern China by relating net ecosystem exchange values to remote sensing data. Finally, we develop a carbon budget for the mangrove forests in the Everglades National Park for the purposes of demonstrating that these forests and adjacent estuaries are sites of intense biogeochemical cycling. One conclusion from this study is that much of the carbon entering from the atmosphere as net ecosystem exchange (~1000 g C m-2 yr-1) is not retained in the net ecosystem carbon balance. Instead, a substantial fraction of the carbon entering the system as net ecosystem exchange is ultimately exported to the oceans or outgassed as reaction products within the adjacent estuary.

A framework to assess biogeochemical response to ecosystem disturbance using nutrient partitioning ratios

Science.gov (United States)

Kranabetter, J. Marty; McLauchlan, Kendra K.; Enders, Sara K.; Fraterrigo, Jennifer M.; Higuera, Philip E.; Morris, Jesse L.; Rastetter, Edward B.; Barnes, Rebecca; Buma, Brian; Gavin, Daniel G.; Gerhart, Laci M.; Gillson, Lindsey; Hietz, Peter; Mack, Michelle C.; McNeil, Brenden; Perakis, Steven

2016-01-01

Disturbances affect almost all terrestrial ecosystems, but it has been difficult to identify general principles regarding these influences. To improve our understanding of the long-term consequences of disturbance on terrestrial ecosystems, we present a conceptual framework that analyzes disturbances by their biogeochemical impacts. We posit that the ratio of soil and plant nutrient stocks in mature ecosystems represents a characteristic site property. Focusing on nitrogen (N), we hypothesize that this partitioning ratio (soil N: plant N) will undergo a predictable trajectory after disturbance. We investigate the nature of this partitioning ratio with three approaches: (1) nutrient stock data from forested ecosystems in North America, (2) a process-based ecosystem model, and (3) conceptual shifts in site nutrient availability with altered disturbance frequency. Partitioning ratios could be applied to a variety of ecosystems and successional states, allowing for improved temporal scaling of disturbance events. The generally short-term empirical evidence for recovery trajectories of nutrient stocks and partitioning ratios suggests two areas for future research. First, we need to recognize and quantify how disturbance effects can be accreting or depleting, depending on whether their net effect is to increase or decrease ecosystem nutrient stocks. Second, we need to test how altered disturbance frequencies from the present state may be constructive or destructive in their effects on biogeochemical cycling and nutrient availability. Long-term studies, with repeated sampling of soils and vegetation, will be essential in further developing this framework of biogeochemical response to disturbance.

Redox oscillation impact on natural and engineered biogeochemical systems: chemical resilience and implications for contaminant mobility

Energy Technology Data Exchange (ETDEWEB)

Charlet, Laurent [ISTerre, University of Grenoble, B.P. 53X, 38041 Grenoble (France); Institut Universitaire de France, Paris (France); Markelova, Ekaterina [ISTerre, University of Grenoble, B.P. 53X, 38041 Grenoble (France); Department of Earth and Environmental Sciences, University of Waterloo, Waterloo, ON N2L3G1 4 (Canada); Parsons, Chris; Couture, Raoul-Marie [Department of Earth and Environmental Sciences, University of Waterloo, Waterloo, ON N2L3G1 4 (Canada); Made, Benoit [Andra / DRD-TR, Direction Recherche et Developpement, 1-7 rue Jean Monnet, 92298 Chatenay-Malabry cedex (France)

2013-07-01

Many geochemical systems fluctuate regularly from oxic to anoxic conditions (flooded soils and nuclear waste surface repositories, for instance). In these conditions many inorganic contaminants including Sb, Se, Cr, As, and U are highly sensitive to changes in redox conditions. These oscillations may result in changes to their speciation, toxicity, and mobility. We demonstrate through the combination of redox-stat batch-reactor experiments that periodic and cumulative changes to matrix mineralogy, contaminant speciation, and mineral surface properties occur following periodic cycles of reduction and oxidation. These changes result in both short-term (intra-cycle) and long-term (inter-cycle) changes to K{sub d} values for a range of redox sensitive contaminants. These results demonstrate that naturally occurring redox oscillations may result in long-term immobilization of contaminants in the solid phase in addition to short-term variations in mobility. (authors)

Drought Conditions Maximize the Impact of High-Frequency Flow Variations on Thermal Regimes and Biogeochemical Function in the Hyporheic Zone.

Energy Technology Data Exchange (ETDEWEB)

None, None

2017-03-01

Anthropogenic activities, such as dam operations, often induce larger and more frequent stage fluctuations than those occurring in natural rivers. However, the long-term impact of such flow variations on thermal and biogeochemical dynamics of the associated hyporheic zone (HZ) is poorly understood. A heterogeneous, two-dimensional thermo-hydro-biogeochemical model revealed an important interaction between high-frequency flow variations and watershed-scale hydrology. High-frequency stage fluctuations had their strongest thermal and biogeochemical impacts when the mean river stage was low during fall and winter. An abnormally thin snowpack in 2015, however, created a low river stage during summer and early fall, whereby high frequency stage fluctuations caused the HZ to be warmer than usual. This study provided the scientific basis to assess the potential ecological consequences of the high-frequency flow variations in a regulated river, as well as guidance on how to maximize the potential benefits—or minimize the drawbacks—of river regulation to river ecosystems.

Greenland's glacial fjords and their role in regional biogeochemical dynamics.

Science.gov (United States)

Crosby, J.; Arndt, S.

2017-12-01

Greenland's coastal fjords serve as important pathways that connect the Greenland Ice Sheet (GrIS) and the surrounding oceans. They export seasonal glacial meltwater whilst being significant sites of primary production. These fjords are home to some of the most productive ecosystems in the world and possess high socio-economic value via fisheries. A growing number of studies have proposed the GrIS as an underappreciated yet significant source of nutrients to surrounding oceans. Acting as both transfer routes and sinks for glacial nutrient export, fjords have the potential to act as significant biogeochemical processors, yet remain underexplored. Critically, an understanding of the quantitative contribution of fjords to carbon and nutrient budgets is lacking, with large uncertainties associated with limited availability of field data and the lack of robust upscaling approaches. To close this knowledge gap we developed a coupled 2D physical-biogeochemical model of the Godthåbsfjord system, a sub-Arctic sill fjord in southwest Greenland, to quantitatively assess the impact of nutrients exported from the GrIS on fjord primary productivity and biogeochemical dynamics. Glacial meltwater is found to be a key driver of fjord-scale circulation patterns, whilst tracer simulations reveal the relative nutrient contributions from meltwater-driven upwelling and meltwater export from the GrIS. Hydrodynamic circulation patterns and freshwater transit times are explored to provide a first understanding of the glacier-fjord-ocean continuum, demonstrating the complex pattern of carbon and nutrient cycling at this critical land-ocean interface.

Biogeochemical cycling in the Taiwan Strait

Digital Repository Service at National Institute of Oceanography (India)

Naik, H.; Chen, C-T.A.

Based on repeat observations made during 2001-2003 along two transects in the Taiwan Strait this study aims at understanding factors controlling primary productivity with an emphasis on biogeochemical cycling of nitrogen, the major bio...

Preface to: Indian Ocean biogeochemical processes and ecological variability

Digital Repository Service at National Institute of Oceanography (India)

Hood, R.R.; Naqvi, S.W.A.; Wiggert, J.D.

monsoonal in fluence. The biogeochemical and ecological impacts of this complex physical forcing are not yet fully understood. The Indian Ocean is truly one of the last great frontiers of ocea- nographic research. In addition, it appears... to be particularly vulnerable to climate change and anthropogenic impacts, yet it has been more than a decade since the last coordinated international study of biogeochemical and ecological proc esses was undertaken in this region. To obtain a better un...

Application of portable in situ UV fluorescence sensors in natural and engineered aquatic systems.

Science.gov (United States)

Fox, Bethany; Rushworth, Cathy; Atrridge, John

2016-04-01

Natural organic matter (NOM) is ubiquitous throughout aquatic systems. This heterogeneous mixture of organic matter is central for aquatic ecosystems and, both local and global, biogeochemical cycling. Improvements in technology and data analysis has allowed for advances in the understanding and characterisation of aquatic organic matter. However, much of the technological expansions have focussed on benchtop instruments. In recent years, there has been interest in the continued development of portable in situ sensors for monitoring NOM characteristics within a wide range of applications, spanning both natural and engineered systems. The UviLux (Chelsea Technologies Group Ltd., UK) is an in situ portable UV fluorescence sensor that can be configured to monitor a range of NOM in aquatic systems, as well as anthropogenic inputs such as polycyclic aromatic hydrocarbons (PAH) and optical brighteners. Here we will focus on the use of the Tryptophan and CDOM UviLux sensors across a variety of applications in both natural systems, such as rivers and leachate into groundwater, and engineered systems, including drinking water and waste water treatment. Recent work has focused on standardising the fluorescence output across the UviLux range of sensors, reporting data in quinine sulphate units (QSU), which enables the output from two different fluorometers to be directly compared both to each other, and to bench-top data. A key advantage of deploying multiple sensors is the ability to fingerprint the fluorescence, by providing, for example, a Tryptophan/CDOM ratio. From the data collected, the ratio of the different fluorescence regions has been shown to provide more robust in situ data and help identify true temporal variations and patterns across multiple applications and sampling locations.

Geochemical and biogeochemical investigations in national parks [Badania geochemiczne i biogeochemiczne w parkach narodowych

Science.gov (United States)

Migaszewski, Z.M.; Lamothe, P.J.; Crock, J.G.

1998-01-01

National parks hold a key position among nature protection areas including a diversity of resources - natural, cultural, recreational and scenic. These "inviolable sanctuaries" are simultaneosuly ecologic knots and pristine nature refuges due to the presence of a number of unique plant and animal species. These species make up a natural gene bank. Classically, the level of biologic degradation in national parks is determined on the basis of qualitative and quantitative studies of plant bioindicators. Their scope encompasses phytosociologic survey the purpose of which is to identify floral assemblages with a detailed list of species to record future changes in their number. The best biomonitors of air quality are epiphytic lichens, ground mosses and conifers. Geochemical and biogeochemical investigations are widely performed in the U.S.A. to evaluate the degree of pollution in the nature protection areas including national parks (Gough et al., 1988a, b; Crock et al., 1992a, 1993; Jackson et al., 1995). Variability of element concentrations in soils and plants is assessed by using unbalanced, nested analysis-of-variance (ANOVA). It enables obtaining important statistical information with a minimum number of samples. In some cases a combined grid and barbell sampling design is applied (Jackson et al., 1995). In specific mountainous parks a method of 2-3 transects parallel to the extent of range (crest) is recommended. To determine the impact of a single pollution source on a given park, traverse sampling beginning near the emitter is used (Crock et al., 1992, 1993). The obtained results are a "snapshot" of chemical composition of soils and plant bioindicators that can be a reference for any future changes in the concentration level of chemical elements and organics. In addition, baseline element and organics composition of the media mentioned above can be compared with that obtained for geochemical atlases of polluted urban and industrial areas. Geochemical and

High frequency marine biogeochemical monitoring from a Japan-Korea ferry -1991 results

International Nuclear Information System (INIS)

Harashima, A.

1993-01-01

A ferry mounted monitoring system was developed and deployed to investigate the temporal and spatial variations of biogeochemical parameters (dissolved nutrients, phytoplankton biomass, temperature, salinity and pH) along the ship's regular route between Pusan, Korea and Kobe, Japan. Semi-continuous data recording (every 10 seconds, 4 transect cruises per week) and automated bottle sampling with filtration (24 cruises per year) were performed using the sea water taken continuously from the engine cooling system intake at 6m depth. These data are expected to clarify the natural variability in and anthropogenic changes to the coastal and marginal seas and the mechanism of algal blooming and to supply the ground truth data for the calibration-validation of algorithms to calculate pigment concentrations from ocean color remote sensing data. Since the start of monitoring (June, 1991), the data have revealed the contrast between the Seto Inland Sea and the outer continental shelf area and the spatial heterogeneities over smaller scales. Among the events apparent in this time series data are the termination of the spring bloom, the mid-summer decrease of phytoplankton biomass due to depletion of nutrients, and autumn blooms, which are characteristic of the periods following storms

Investigation of geochemical characteristics of some natural water systems by nondestructive radioactivation analysis

International Nuclear Information System (INIS)

Draskovic, R.

1977-01-01

In this thesis the new theoretical and systematized approaches to the investigation of continental water systems (rivers, lakes, swamps etc) with the aim of its biogeochemical characterization are given and discussed. By nondestructive radioactivation analysis some elements (Cr, Fe, Co, Sb, Sc, Na acro and trace elements level) in components of investigated water system are determined. These elements has been determined in materials dissolved in water, suspended and bed materials, soils and the living matter populating the rivers systems Danube, Sava, V.Morava, Tisa, Karas and some lakes also (plankton, algae, benthos, crustacea, benthos, shalls and fishes) in Yugoslavia. The results are presented and discussed on the basis of parameters ''content of elements'' (new theoretical approaches) for these systems (Csub(w)-water; Csub(s)-suspended and bed materials; Csub(t)-soils; Csub(vivo)-living matter: plankton - Csub(p); aglae - Csub(al); benthos - Csub(b); crustacea - Csub(c); fishes - Csub(f)) expressed in ppm. Distribution on parameters (Fsub(x,y)) for the pairs of components of water systems also are given. The ''contents of elements'' - parameters are biogeochemical standards characterizing investigated water systems and ecological and environmental important parameters, too

The acclimative biogeochemical model of the southern North Sea

Science.gov (United States)

Kerimoglu, Onur; Hofmeister, Richard; Maerz, Joeran; Riethmüller, Rolf; Wirtz, Kai W.

2017-10-01

Ecosystem models often rely on heuristic descriptions of autotrophic growth that fail to reproduce various stationary and dynamic states of phytoplankton cellular composition observed in laboratory experiments. Here, we present the integration of an advanced phytoplankton growth model within a coupled three-dimensional physical-biogeochemical model and the application of the model system to the southern North Sea (SNS) defined on a relatively high resolution (˜ 1.5-4.5 km) curvilinear grid. The autotrophic growth model, recently introduced by Wirtz and Kerimoglu (2016), is based on a set of novel concepts for the allocation of internal resources and operation of cellular metabolism. The coupled model system consists of the General Estuarine Transport Model (GETM) as the hydrodynamical driver, a lower-trophic-level model and a simple sediment diagenesis model. We force the model system with realistic atmospheric and riverine fluxes, background turbidity caused by suspended particulate matter (SPM) and open ocean boundary conditions. For a simulation for the period 2000-2010, we show that the model system satisfactorily reproduces the physical and biogeochemical states of the system within the German Bight characterized by steep salinity; nutrient and chlorophyll (Chl) gradients, as inferred from comparisons against observation data from long-term monitoring stations; sparse in situ measurements; continuous transects; and satellites. The model also displays skill in capturing the formation of thin chlorophyll layers at the pycnocline, which is frequently observed within the stratified regions during summer. A sensitivity analysis reveals that the vertical distributions of phytoplankton concentrations estimated by the model can be qualitatively sensitive to the description of the light climate and dependence of sinking rates on the internal nutrient reserves. A non-acclimative (fixed-physiology) version of the model predicted entirely different vertical profiles

How do persistent organic pollutants be coupled with biogeochemical cycles of carbon and nutrients in terrestrial ecosystems under global climate change?

Energy Technology Data Exchange (ETDEWEB)

Teng, Ying [Chinese Academy of Sciences, Nanjing (China). Key Lab. of Soil Environment and Pollution Remediation; Griffith Univ., Nathan, QLD (Australia). Environmetnal Futures Centre and School of Biomolecular and Physical Sciences; Xu, Zhihong; Reverchon, Frederique [Griffith Univ., Nathan, QLD (Australia). Environmetnal Futures Centre and School of Biomolecular and Physical Sciences; Luo, Yongming [Chinese Academy of Sciences, Nanjing (China). Key Lab. of Soil Environment and Pollution Remediation

2012-03-15

Global climate change (GCC), especially global warming, has affected the material cycling (e.g., carbon, nutrients, and organic chemicals) and the energy flows of terrestrial ecosystems. Persistent organic pollutants (POPs) were regarded as anthropogenic organic carbon (OC) source, and be coupled with the natural carbon (C) and nutrient biogeochemical cycling in ecosystems. The objective of this work was to review the current literature and explore potential coupling processes and mechanisms between POPs and biogeochemical cycles of C and nutrients in terrestrial ecosystems induced by global warming. Global warming has caused many physical, chemical, and biological changes in terrestrial ecosystems. POPs environmental fate in these ecosystems is controlled mainly by temperature and biogeochemical processes. Global warming may accelerate the re-emissions and redistribution of POPs among environmental compartments via soil-air exchange. Soil-air exchange is a key process controlling the fate and transportation of POPs and terrestrial ecosystem C at regional and global scales. Soil respiration is one of the largest terrestrial C flux induced by microbe and plant metabolism, which can affect POPs biotransformation in terrestrial ecosystems. Carbon flow through food web structure also may have important consequences for the biomagnification of POPs in the ecosystems and further lead to biodiversity loss induced by climate change and POPs pollution stress. Moreover, the integrated techniques and biological adaptation strategy help to fully explore the coupling mechanisms, functioning and trends of POPs and C and nutrient biogeochemical cycling processes in terrestrial ecosystems. There is increasing evidence that the environmental fate of POPs has been linked with biogeochemical cycles of C and nutrients in terrestrial ecosystems under GCC. However, the relationships between POPs and the biogeochemical cycles of C and nutrients are still not well understood. Further

Climate Regulation Services of Natural and Managed Ecosystems of the Americas

Science.gov (United States)

Anderson-Teixeira, K. J.; Snyder, P. K.; Twine, T. E.; Costa, M. H.; Cuadra, S.; DeLucia, E. H.

2011-12-01

Terrestrial ecosystems regulate climate through both biogeochemical mechanisms (greenhouse gas regulation) and biophysical mechanisms (regulation of water and energy). Land management therefore provides some of the most effective strategies for climate change mitigation. However, most policies aimed at climate protection through land management, including UNFCCC mechanisms and bioenergy sustainability standards, account only for biogeochemical climate services. By ignoring biophysical climate regulation services that in some cases offset the biogeochemical regulation services, these policies run the risk of failing to advance the best climate solutions. Quantifying the combined value of biogeochemical and biophysical climate regulation services remains an important challenge. Here, we use a combination of data synthesis and modeling to quantify how biogeochemical and biophysical effects combine to shape the climate regulation value (CRV) of 18 natural and managed ecosystem types across the Western Hemisphere. Natural ecosystems generally had higher CRVs than agroecosystems, largely driven by differences in biogeochemical services. Biophysical contributions ranged from minimal to dominant. They were highly variable in space and across ecosystem types, and their relative importance varied strongly with the spatio-temporal scale of analysis. Our findings pertain to current efforts to protect climate through land management. Specifically, they reinforce the importance of protecting tropical forests and recent findings that the climatic effects of bioenergy production may be somewhat more positive than previously estimated. Given that biophysical effects in some cases dominate, ensuring effective climate protection through land management requires consideration of combined biogeochemical and biophysical climate regulation services. While quantification of ecosystem climate services is necessarily complex, our CRV index serves as one potential approach to measure the

Biogeochemical research priorities for sustainable biofuel and bioenergy feedstock production in the Americas

Science.gov (United States)

Hero T. Gollany; Brian D. Titus; D. Andrew Scott; Heidi Asbjornsen; Sigrid C. Resh; Rodney A. Chimner; Donald J. Kaczmarek; Luiz F.C. Leite; Ana C.C. Ferreira; Kenton A. Rod; Jorge Hilbert; Marcelo V. Galdos; Michelle E. Cisz

2015-01-01

Rapid expansion in biomass production for biofuels and bioenergy in the Americas is increasing demand on the ecosystem resources required to sustain soil and site productivity. We review the current state of knowledge and highlight gaps in research on biogeochemical processes and ecosystem sustainability related to biomass production. Biomass production systems...

Modelling of transport and biogeochemical processes in pollution plumes: Vejen landfill, Denmark

DEFF Research Database (Denmark)

Brun, A.; Engesgaard, Peter Knudegaard; Christensen, Thomas Højlund

2002-01-01

A biogeochemical transport code is used to simulate leachate attenuation. biogeochemical processes. and development of redox zones in a pollution plume downstream of the Vejen landfill in Denmark. Calibration of the degradation parameters resulted in a good agreement with the observed distribution...

Long-term ERT monitoring of biogeochemical changes of an aged hydrocarbon contamination

Science.gov (United States)

Caterina, David; Flores Orozco, Adrian; Nguyen, Frédéric

2017-06-01

Adequate management of contaminated sites requires information with improved spatio-temporal resolution, in particular to assess bio-geochemical processes, such as the transformation and degradation of contaminants, precipitation of minerals or changes in groundwater geochemistry occurring during and after remediation procedures. Electrical Resistivity Tomography (ERT), a geophysical method sensitive to pore-fluid and pore-geometry properties, permits to gain quasi-continuous information about subsurface properties in real-time and has been consequently widely used for the characterization of hydrocarbon-impacted sediments. However, its application for the long-term monitoring of processes accompanying natural or engineered bioremediation is still difficult due to the poor understanding of the role that biogeochemical processes play in the electrical signatures. For in-situ studies, the task is further complicated by the variable signal-to-noise ratio and the variations of environmental parameters leading to resolution changes in the electrical images. In this work, we present ERT imaging results for data collected over a period of two years on a site affected by a diesel fuel contamination and undergoing bioremediation. We report low electrical resistivity anomalies in areas associated to the highest contaminant concentrations likely due transformations of the contaminant due to microbial activity and accompanying release of metabolic products. We also report large seasonal variations of the bulk electrical resistivity in the contaminated areas in correlation with temperature and groundwater level fluctuations. However, the amplitude of bulk electrical resistivity variations largely exceeds the amplitude expected given existing petrophysical models. Our results suggest that the variations in electrical properties are mainly controlled by microbial activity which in turn depends on soil temperature and hydrogeological conditions. Therefore, ERT can be suggested as

Radionuclide release from simulated waste material after biogeochemical leaching of uraniferous mineral samples

International Nuclear Information System (INIS)

Williamson, Aimee Lynn; Caron, François; Spiers, Graeme

2014-01-01

Biogeochemical mineral dissolution is a promising method for the released of metals in low-grade host mineralization that contain sulphidic minerals. The application of biogeochemical mineral dissolution to engineered leach heap piles in the Elliot Lake region may be considered as a promising passive technology for the economic recovery of low grade Uranium-bearing ores. In the current investigation, the decrease of radiological activity of uraniferous mineral material after biogeochemical mineral dissolution is quantified by gamma spectroscopy and compared to the results from digestion/ICP-MS analysis of the ore materials to determine if gamma spectroscopy is a simple, viable alternative quantification method for heavy nuclides. The potential release of Uranium (U) and Radium-226 ( 226 Ra) to the aqueous environment from samples that have been treated to represent various stages of leaching and passive closure processes are assessed. Dissolution of U from the solid phase has occurred during biogeochemical mineral dissolution in the presence of Acidithiobacillus ferrooxidans, with gamma spectroscopy indicating an 84% decrease in Uranium-235 ( 235 U) content, a value in accordance with the data obtained by dissolution chemistry. Gamma spectroscopy data indicate that only 30% of the 226 Ra was removed during the biogeochemical mineral dissolution. Chemical inhibition and passivation treatments of waste materials following the biogeochemical mineral dissolution offer greater protection against residual U and 226 Ra leaching. Pacified samples resist the release of 226 Ra contained in the mineral phase and may offer more protection to the aqueous environment for the long term, compared to untreated or inhibited residues, and should be taken into account for future decommissioning. - Highlights: • Gamma counting showed an 84% decrease in 235 U after biogeochemical mineral leaching. • Chemical digestion/ICP-MS analysis also showed an 84% decrease in total U. • Over

Error assessment of biogeochemical models by lower bound methods (NOMMA-1.0

Directory of Open Access Journals (Sweden)

V. Sauerland

2018-03-01

Full Text Available Biogeochemical models, capturing the major feedbacks of the pelagic ecosystem of the world ocean, are today often embedded into Earth system models which are increasingly used for decision making regarding climate policies. These models contain poorly constrained parameters (e.g., maximum phytoplankton growth rate, which are typically adjusted until the model shows reasonable behavior. Systematic approaches determine these parameters by minimizing the misfit between the model and observational data. In most common model approaches, however, the underlying functions mimicking the biogeochemical processes are nonlinear and non-convex. Thus, systematic optimization algorithms are likely to get trapped in local minima and might lead to non-optimal results. To judge the quality of an obtained parameter estimate, we propose determining a preferably large lower bound for the global optimum that is relatively easy to obtain and that will help to assess the quality of an optimum, generated by an optimization algorithm. Due to the unavoidable noise component in all observations, such a lower bound is typically larger than zero. We suggest deriving such lower bounds based on typical properties of biogeochemical models (e.g., a limited number of extremes and a bounded time derivative. We illustrate the applicability of the method with two real-world examples. The first example uses real-world observations of the Baltic Sea in a box model setup. The second example considers a three-dimensional coupled ocean circulation model in combination with satellite chlorophyll a.

Error assessment of biogeochemical models by lower bound methods (NOMMA-1.0)

Science.gov (United States)

Sauerland, Volkmar; Löptien, Ulrike; Leonhard, Claudine; Oschlies, Andreas; Srivastav, Anand

2018-03-01

Biogeochemical models, capturing the major feedbacks of the pelagic ecosystem of the world ocean, are today often embedded into Earth system models which are increasingly used for decision making regarding climate policies. These models contain poorly constrained parameters (e.g., maximum phytoplankton growth rate), which are typically adjusted until the model shows reasonable behavior. Systematic approaches determine these parameters by minimizing the misfit between the model and observational data. In most common model approaches, however, the underlying functions mimicking the biogeochemical processes are nonlinear and non-convex. Thus, systematic optimization algorithms are likely to get trapped in local minima and might lead to non-optimal results. To judge the quality of an obtained parameter estimate, we propose determining a preferably large lower bound for the global optimum that is relatively easy to obtain and that will help to assess the quality of an optimum, generated by an optimization algorithm. Due to the unavoidable noise component in all observations, such a lower bound is typically larger than zero. We suggest deriving such lower bounds based on typical properties of biogeochemical models (e.g., a limited number of extremes and a bounded time derivative). We illustrate the applicability of the method with two real-world examples. The first example uses real-world observations of the Baltic Sea in a box model setup. The second example considers a three-dimensional coupled ocean circulation model in combination with satellite chlorophyll a.

Biogeochemical cycles of Chernobyl-born radionuclides in the contaminated forest ecosystems: long-term dynamics of the migration processes

Science.gov (United States)

Shcheglov, Alexey; Tsvetnova, Ol'ga; Klyashtorin, Alexey

2013-04-01

Biogeochemical migration is a dominant factor of the radionuclide transport through the biosphere. In the early XX century, V.I. Vernadskii, a Russian scientist known, noted about a special role living things play in transport and accumulation of natural radionuclide in various environments. The role of biogeochemical processes in migration and redistribution of technogenic radionuclides is not less important. In Russia, V. M. Klechkovskii and N.V. Timofeev-Ressovskii showed some important biogeochemical aspects of radionuclide migration by the example of global fallout and Kyshtym accident. Their followers, R.M. Alexakhin, M.A. Naryshkin, N.V. Kulikov, F.A. Tikhomirov, E.B. Tyuryukanova, and others also contributed a lot to biogeochemistry of radionuclides. In the post-Chernobyl period, this area of knowledge received a lot of data that allowed building the radioactive element balance and flux estimation in various biogeochemical cycles [Shcheglov et al., 1999]. Regrettably, many of recent radioecological studies are only focused on specific radionuclide fluxes or pursue some applied tasks, missing the holistic approach. Most of the studies consider biogeochemical fluxes of radioactive isotopes in terms of either dose estimation or radionuclide migration rates in various food chains. However, to get a comprehensive picture and develop a reliable forecast of environmental, ecological, and social consequences of radioactive pollution in a vast contaminated area, it is necessary to investigate all the radionuclide fluxes associated with the biogeochemical cycles in affected ecosystems. We believe such an integrated approach would be useful to study long-term environmental consequences of the Fukushima accident as well. In our long-term research, we tried to characterize the flux dynamics of the Chernobyl-born radionuclides in the contaminated forest ecosystems and landscapes as a part of the integrated biogeochemical process. Our field studies were started in June of

High resolution modelling of the biogeochemical processes in the eutrophic Loire River (France)

Science.gov (United States)

Minaudo, Camille; Moatar, Florentina; Curie, Florence; Gassama, Nathalie; Billen, Gilles

2016-04-01

released by mineralization of the dead cells. The high resolution of the model allowed understanding some fine temporal scale events, especially during some minor flood events occurring in summer. Paradoxically such events played two opposite roles: first it was disturbing the phytoplankton by diluting the biomass and remobilizing suspended sediments; then, it indirectly re-supplied the system with more available phosphorus, mainly because the washed-out phytoplankton could not assimilate the P available upstream. The model also pointed out the significant role played by Corbicula invasive clams in the river biogeochemical functioning, substantially reducing the phytoplankton biomass, and thus impacting the nutrients, oxygen and carbon cycles. However, the temporal and spatial distribution of Corbicula was questioned, and highlighted the need for data collection on this topic.

Aqueous complexation reactions governing the rate and extent of biogeochemical U(VI) reduction

International Nuclear Information System (INIS)

Kemner, K.M.; Kelly, S.D.; Brooks, Scott C.; Dong, Wenming; Carroll, Sue; Fredrickson, James K.

2006-01-01

The proposed research will elucidate the principal biogeochemical reactions that govern the concentration, chemical speciation, and reactivity of the redox-sensitive contaminant uranium. The results will provide an improved understanding and predictive capability of the mechanisms that govern the biogeochemical reduction of uranium in subsurface environments

Biogeochemical speciation of Fe in ocean water

NARCIS (Netherlands)

Hiemstra, T.; Riemsdijk, van W.H.

2006-01-01

The biogeochemical speciation of Fe in seawater has been evaluated using the consistent Non-Ideal Competitive Adsorption model (NICA¿Donnan model). Two types of data sets were used, i.e. Fe-hydroxide solubility data and competitive ligand equilibration/cathodic stripping voltammetry (CLE/CSV) Fe

Modelling of transport and biogeochemical processes in pollution plumes: Literature review of model development

DEFF Research Database (Denmark)

Brun, A.; Engesgaard, Peter Knudegaard

2002-01-01

A literature survey shows how biogeochemical (coupled organic and inorganic reaction processes) transport models are based on considering the complete biodegradation process as either a single- or as a two-step process. It is demonstrated that some two-step process models rely on the Partial...... Equilibrium Approach (PEA). The PEA assumes the organic degradation step, and not the electron acceptor consumption step, is rate limiting. This distinction is not possible in one-step process models, where consumption of both the electron donor and acceptor are treated kinetically. A three-dimensional, two......-step PEA model is developed. The model allows for Monod kinetics and biomass growth, features usually included only in one-step process models. The biogeochemical part of the model is tested for a batch system with degradation of organic matter under the consumption of a sequence of electron acceptors...

Aqueous Complexation Reactions Governing the Rate and Extent of Biogeochemical U(VI) Reduction

International Nuclear Information System (INIS)

Scott C. Brooks; Wenming Dong; Sue Carroll; James K. Fredrickson; Kenneth M. Kemner; Shelly D. Kelly

2006-01-01

The proposed research will elucidate the principal biogeochemical reactions that govern the concentration, chemical speciation, and reactivity of the redox-sensitive contaminant uranium. The results will provide an improved understanding and predictive capability of the mechanisms that govern the biogeochemical reduction of uranium in subsurface environments. In addition, the work plan is designed to: (1) Generate fundamental scientific understanding on the relationship between U(VI) chemical speciation and its susceptibility to biogeochemical reduction reactions. (2) Elucidate the controls on the rate and extent of contaminant reactivity. (3) Provide new insights into the aqueous and solid speciation of U(VI)/U(IV) under representative groundwater conditions

Consequences of climate change for biogeochemical cycling in forests of northeastern North America

Science.gov (United States)

John L. Campbell; Lindsey E. Rustad; Elizabeth W. Boyer; Sheila F. Christopher; Charles T. Driscoll; Ivan .J. Fernandez; Peter M. Groffman; Daniel Houle; Jana Kiekbusch; Alison H. Magill; Myron J. Mitchell; Scott V. Ollinger

2009-01-01

A critical component of assessing the impacts of climate change on forest ecosystems involves understanding associated changes in biogeochemical cycling of elements. Evidence from research on northeastern North American forests shows that direct effects of climate change will evoke changes in biogeochemical cycling by altering plant physiology forest productivity, and...

Long-term ERT monitoring of biogeochemical changes of an aged hydrocarbon contamination.

Science.gov (United States)

Caterina, David; Flores Orozco, Adrian; Nguyen, Frédéric

2017-06-01

Adequate management of contaminated sites requires information with improved spatio-temporal resolution, in particular to assess bio-geochemical processes, such as the transformation and degradation of contaminants, precipitation of minerals or changes in groundwater geochemistry occurring during and after remediation procedures. Electrical Resistivity Tomography (ERT), a geophysical method sensitive to pore-fluid and pore-geometry properties, permits to gain quasi-continuous information about subsurface properties in real-time and has been consequently widely used for the characterization of hydrocarbon-impacted sediments. However, its application for the long-term monitoring of processes accompanying natural or engineered bioremediation is still difficult due to the poor understanding of the role that biogeochemical processes play in the electrical signatures. For in-situ studies, the task is further complicated by the variable signal-to-noise ratio and the variations of environmental parameters leading to resolution changes in the electrical images. In this work, we present ERT imaging results for data collected over a period of two years on a site affected by a diesel fuel contamination and undergoing bioremediation. We report low electrical resistivity anomalies in areas associated to the highest contaminant concentrations likely due transformations of the contaminant due to microbial activity and accompanying release of metabolic products. We also report large seasonal variations of the bulk electrical resistivity in the contaminated areas in correlation with temperature and groundwater level fluctuations. However, the amplitude of bulk electrical resistivity variations largely exceeds the amplitude expected given existing petrophysical models. Our results suggest that the variations in electrical properties are mainly controlled by microbial activity which in turn depends on soil temperature and hydrogeological conditions. Therefore, ERT can be suggested as

Optical Remote Sensing Algorithm Validation using High-Frequency Underway Biogeochemical Measurements in Three Large Global River Systems

Science.gov (United States)

Kuhn, C.; Richey, J. E.; Striegl, R. G.; Ward, N.; Sawakuchi, H. O.; Crawford, J.; Loken, L. C.; Stadler, P.; Dornblaser, M.; Butman, D. E.

2017-12-01

More than 93% of the world's river-water volume occurs in basins impacted by large dams and about 43% of river water discharge is impacted by flow regulation. Human land use also alters nutrient and carbon cycling and the emission of carbon dioxide from inland reservoirs. Increased water residence times and warmer temperatures in reservoirs fundamentally alter the physical settings for biogeochemical processing in large rivers, yet river biogeochemistry for many large systems remains undersampled. Satellite remote sensing holds promise as a methodology for responsive regional and global water resources management. Decades of ocean optics research has laid the foundation for the use of remote sensing reflectance in optical wavelengths (400 - 700 nm) to produce satellite-derived, near-surface estimates of phytoplankton chlorophyll concentration. Significant improvements between successive generations of ocean color sensors have enabled the scientific community to document changes in global ocean productivity (NPP) and estimate ocean biomass with increasing accuracy. Despite large advances in ocean optics, application of optical methods to inland waters has been limited to date due to their optical complexity and small spatial scale. To test this frontier, we present a study evaluating the accuracy and suitability of empirical inversion approaches for estimating chlorophyll-a, turbidity and temperature for the Amazon, Columbia and Mississippi rivers using satellite remote sensing. We demonstrate how riverine biogeochemical measurements collected at high frequencies from underway vessels can be used as in situ matchups to evaluate remotely-sensed, near-surface temperature, turbidity, chlorophyll-a derived from the Landsat 8 (NASA) and Sentinel 2 (ESA) satellites. We investigate the use of remote sensing water reflectance to infer trophic status as well as tributary influences on the optical characteristics of the Amazon, Mississippi and Columbia rivers.

Biogeochemical cycling of radionuclides in the environment

International Nuclear Information System (INIS)

Livens, F.R.

1990-01-01

The biogeochemical cycling of radionuclides with other components such as nutrients around ecosystems is discussed. In particular the behaviour of cesium in freshwater ecosystems since the Chernobyl accident and the behaviour of technetium in the form of pertechnetate anions, TcO 4 , in marine ecosystems is considered. (UK)

Electric currents couple spatially separated biogeochemical processes in marine sediment

DEFF Research Database (Denmark)

Nielsen, Lars Peter; Risgaard-Petersen, Nils; Fossing, Henrik

2010-01-01

Some bacteria are capable of extracellular electron transfer, thereby enabling them to use electron acceptors and donors without direct cell contact 1, 2, 3, 4 . Beyond the micrometre scale, however, no firm evidence has previously existed that spatially segregated biogeochemical processes can...... be coupled by electric currents in nature. Here we provide evidence that electric currents running through defaunated sediment couple oxygen consumption at the sediment surface to oxidation of hydrogen sulphide and organic carbon deep within the sediment. Altering the oxygen concentration in the sea water...... in the sediment was driven by electrons conducted from the anoxic zone. A distinct pH peak in the oxic zone could be explained by electrochemical oxygen reduction, but not by any conventional sets of aerobic sediment processes. We suggest that the electric current was conducted by bacterial nanowires combined...

Carbon sequestration by patch fertilization: A comprehensive assessment using coupled physical-ecological-biogeochemical models

Energy Technology Data Exchange (ETDEWEB)

Sarmiento, Jorge L. [Princeton Univ., NJ (United States); Gnanadesikan, Anand [Princeton Univ., NJ (United States); Gruber, Nicolas [Univ. of California, Los Angeles, CA (United States); Jin, Xin [Univ. of California, Los Angeles, CA (United States); Armstrong, Robert [State Univ. of New York (SUNY), Plattsburgh, NY (United States)

2007-06-21

This final report summarizes research undertaken collaboratively between Princeton University, the NOAA Geophysical Fluid Dynamics Laboratory on the Princeton University campus, the State University of New York at Stony Brook, and the University of California, Los Angeles between September 1, 2000, and November 30, 2006, to do fundamental research on ocean iron fertilization as a means to enhance the net oceanic uptake of CO2 from the atmosphere. The approach we proposed was to develop and apply a suite of coupled physical-ecological-biogeochemical models in order to (i) determine to what extent enhanced carbon fixation from iron fertilization will lead to an increase in the oceanic uptake of atmospheric CO2 and how long this carbon will remain sequestered (efficiency), and (ii) examine the changes in ocean ecology and natural biogeochemical cycles resulting from iron fertilization (consequences). The award was funded in two separate three-year installments: September 1, 2000 to November 30, 2003, for a project entitled “Ocean carbon sequestration by fertilization: An integrated biogeochemical assessment.” A final report was submitted for this at the end of 2003 and is included here as Appendix 1; and, December 1, 2003 to November 30, 2006, for a follow-on project under the same grant number entitled “Carbon sequestration by patch fertilization: A comprehensive assessment using coupled physical-ecological-biogeochemical models.” This report focuses primarily on the progress we made during the second period of funding subsequent to the work reported on in Appendix 1. When we began this project, we were thinking almost exclusively in terms of long-term fertilization over large regions of the ocean such as the Southern Ocean, with much of our focus being on how ocean circulation and biogeochemical cycling would interact to control the response to a given fertilization scenario. Our research on these types of scenarios, which was carried out largely during the

The Anthropogenic Effects of Hydrocarbon Inputs to Coastal Seas: Are There Potential Biogeochemical Impacts?

Science.gov (United States)

Anderson, M. R.; Rivkin, R. B.

2016-02-01

Petroleum hydrocarbon discharges related to fossil fuel exploitation have the potential to alter microbial processes in the upper ocean. While the ecotoxicological effects of such inputs are commonly evaluated, the potential for eutrophication from the constituent organic and inorganic nutrients has been largely ignored. Hydrocarbons from natural seeps and anthropogenic sources represent a measurable source of organic carbon for surface waters. The most recent (1989-1997) estimate of average world-wide input of hydrocarbons to the sea is 1.250 x 1012 g/yr ≈ 1.0 x 1012g C/year. Produced water from offshore platforms is the largest waste stream from oil and gas exploitation and contributes significant quantities of inorganic nutrients such as N, P and Fe. In coastal areas where such inputs are a significant source of these nutrients, model studies show the potential to shift production toward smaller cells and net heterotrophy. The consequences of these nutrient sources for coastal systems and semi enclosed seas are complex and difficult to predict, because (1) there is a lack of comprehensive data on inputs and in situ concentrations and (2) the is no conceptual or quantitative framework to consider their effects on ocean biogeochemical processes. Here we use examples from the North Sea (produced water discharges 1% total riverine input and NH4 3% of the annual riverine nitrogen load), the South China Sea (total petroleum hydrocarbons = 10-1750 μg/l in offshore waters), and the Gulf of Mexico (seeps = 76-106 x 109 gC/yr, Macondo blowout 545 x 109 gC) to demonstrate how hydrocarbon and produced water inputs can influence basin scale biogeochemical and ecosystem processes and to propose a framework to consider these effects on larger scales.

NERC's Biogeochemical Ocean Flux Study (North Atlantic Data Set) was collected aboard the RRS DISCOVERY and CHARLES DARWIN in the North Atlantic Ocean from 19890417 to 19910728 (NODC Accession 0000708)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The Biogeochemical Ocean Flux Study (BOFS) was a Community Research Project of the Marine and Atmospheric Sciences Directorate of the Natural Environment Research...

Natural Information Processing Systems

OpenAIRE

John Sweller; Susan Sweller

2006-01-01

Natural information processing systems such as biological evolution and human cognition organize information used to govern the activities of natural entities. When dealing with biologically secondary information, these systems can be specified by five common principles that we propose underlie natural information processing systems. The principles equate: (1) human long-term memory with a genome; (2) learning from other humans with biological reproduction; (3) problem solving through random ...

Multiscale Investigation on Biofilm Distribution and Its Impact on Macroscopic Biogeochemical Reaction Rates

Science.gov (United States)

Yan, Zhifeng; Liu, Chongxuan; Liu, Yuanyuan; Bailey, Vanessa L.

2017-11-01

Biofilms are critical locations for biogeochemical reactions in the subsurface environment. The occurrence and distribution of biofilms at microscale as well as their impacts on macroscopic biogeochemical reaction rates are still poorly understood. This paper investigated the formation and distributions of biofilms in heterogeneous sediments using multiscale models and evaluated the effects of biofilm heterogeneity on local and macroscopic biogeochemical reaction rates. Sediment pore structures derived from X-ray computed tomography were used to simulate the microscale flow dynamics and biofilm distribution in the sediment column. The response of biofilm formation and distribution to the variations in hydraulic and chemical properties was first examined. One representative biofilm distribution was then utilized to evaluate its effects on macroscopic reaction rates using nitrate reduction as an example. The results revealed that microorganisms primarily grew on the surfaces of grains and aggregates near preferential flow paths where both electron donor and acceptor were readily accessible, leading to the heterogeneous distribution of biofilms in the sediments. The heterogeneous biofilm distribution decreased the macroscopic rate of biogeochemical reactions as compared with those in homogeneous cases. Operationally considering the heterogeneous biofilm distribution in macroscopic reactive transport models such as using dual porosity domain concept can significantly improve the prediction of biogeochemical reaction rates. Overall, this study provided important insights into the biofilm formation and distribution in soils and sediments as well as their impacts on the macroscopic manifestation of reaction rates.

Biogeochemical protocols and diagnostics for the CMIP6 Ocean Model Intercomparison Project (OMIP

Directory of Open Access Journals (Sweden)

J. C. Orr

2017-06-01

Full Text Available The Ocean Model Intercomparison Project (OMIP focuses on the physics and biogeochemistry of the ocean component of Earth system models participating in the sixth phase of the Coupled Model Intercomparison Project (CMIP6. OMIP aims to provide standard protocols and diagnostics for ocean models, while offering a forum to promote their common assessment and improvement. It also offers to compare solutions of the same ocean models when forced with reanalysis data (OMIP simulations vs. when integrated within fully coupled Earth system models (CMIP6. Here we detail simulation protocols and diagnostics for OMIP's biogeochemical and inert chemical tracers. These passive-tracer simulations will be coupled to ocean circulation models, initialized with observational data or output from a model spin-up, and forced by repeating the 1948–2009 surface fluxes of heat, fresh water, and momentum. These so-called OMIP-BGC simulations include three inert chemical tracers (CFC-11, CFC-12, SF6 and biogeochemical tracers (e.g., dissolved inorganic carbon, carbon isotopes, alkalinity, nutrients, and oxygen. Modelers will use their preferred prognostic BGC model but should follow common guidelines for gas exchange and carbonate chemistry. Simulations include both natural and total carbon tracers. The required forced simulation (omip1 will be initialized with gridded observational climatologies. An optional forced simulation (omip1-spunup will be initialized instead with BGC fields from a long model spin-up, preferably for 2000 years or more, and forced by repeating the same 62-year meteorological forcing. That optional run will also include abiotic tracers of total dissolved inorganic carbon and radiocarbon, CTabio and 14CTabio, to assess deep-ocean ventilation and distinguish the role of physics vs. biology. These simulations will be forced by observed atmospheric histories of the three inert gases and CO2 as well as carbon isotope ratios of CO2. OMIP-BGC simulation

Biogeochemical Protocols and Diagnostics for the CMIP6 Ocean Model Intercomparison Project (OMIP)

Science.gov (United States)

Orr, James C.; Najjar, Raymond G.; Aumont, Olivier; Bopp, Laurent; Bullister, John L.; Danabasoglu, Gokhan; Doney, Scott C.; Dunne, John P.; Dutay, Jean-Claude; Graven, Heather;

Biogeochemical protocols and diagnostics for the CMIP6 Ocean Model Intercomparison Project (OMIP)

Science.gov (United States)

Orr, James C.; Najjar, Raymond G.; Aumont, Olivier; Bopp, Laurent; Bullister, John L.; Danabasoglu, Gokhan; Doney, Scott C.; Dunne, John P.; Dutay, Jean-Claude; Graven, Heather; Griffies, Stephen M.; John, Jasmin G.; Joos, Fortunat; Levin, Ingeborg; Lindsay, Keith; Matear, Richard J.; McKinley, Galen A.; Mouchet, Anne; Oschlies, Andreas; Romanou, Anastasia; Schlitzer, Reiner; Tagliabue, Alessandro; Tanhua, Toste; Yool, Andrew

2017-06-01

The Ocean Model Intercomparison Project (OMIP) focuses on the physics and biogeochemistry of the ocean component of Earth system models participating in the sixth phase of the Coupled Model Intercomparison Project (CMIP6). OMIP aims to provide standard protocols and diagnostics for ocean models, while offering a forum to promote their common assessment and improvement. It also offers to compare solutions of the same ocean models when forced with reanalysis data (OMIP simulations) vs. when integrated within fully coupled Earth system models (CMIP6). Here we detail simulation protocols and diagnostics for OMIP's biogeochemical and inert chemical tracers. These passive-tracer simulations will be coupled to ocean circulation models, initialized with observational data or output from a model spin-up, and forced by repeating the 1948-2009 surface fluxes of heat, fresh water, and momentum. These so-called OMIP-BGC simulations include three inert chemical tracers (CFC-11, CFC-12, SF6) and biogeochemical tracers (e.g., dissolved inorganic carbon, carbon isotopes, alkalinity, nutrients, and oxygen). Modelers will use their preferred prognostic BGC model but should follow common guidelines for gas exchange and carbonate chemistry. Simulations include both natural and total carbon tracers. The required forced simulation (omip1) will be initialized with gridded observational climatologies. An optional forced simulation (omip1-spunup) will be initialized instead with BGC fields from a long model spin-up, preferably for 2000 years or more, and forced by repeating the same 62-year meteorological forcing. That optional run will also include abiotic tracers of total dissolved inorganic carbon and radiocarbon, CTabio and 14CTabio, to assess deep-ocean ventilation and distinguish the role of physics vs. biology. These simulations will be forced by observed atmospheric histories of the three inert gases and CO2 as well as carbon isotope ratios of CO2. OMIP-BGC simulation protocols are

Biogeochemical cycles and biodiversity as key drivers of ecosystem services provided by soils

Science.gov (United States)

Smith, P.; Cotrufo, M. F.; Rumpel, C.; Paustian, K.; Kuikman, P. J.; Elliott, J. A.; McDowell, R.; Griffiths, R. I.; Asakawa, S.; Bustamante, M.; House, J. I.; Sobocká, J.; Harper, R.; Pan, G.; West, P. C.; Gerber, J. S.; Clark, J. M.; Adhya, T.; Scholes, R. J.; Scholes, M. C.

2015-06-01

Soils play a pivotal role in major global biogeochemical cycles (carbon, nutrient and water), while hosting the largest diversity of organisms on land. Because of this, soils deliver fundamental ecosystem services, and management to change a soil process in support of one ecosystem service can either provide co-benefits to other services or can result in trade-offs. In this critical review, we report the state-of-the-art understanding concerning the biogeochemical cycles and biodiversity in soil, and relate these to the provisioning, regulating, supporting and cultural ecosystem services which they underpin. We then outline key knowledge gaps and research challenges, before providing recommendations for management activities to support the continued delivery of ecosystem services from soils. We conclude that although there are knowledge gaps that require further research, enough is known to start improving soils globally. The main challenge is in finding ways to share knowledge with soil managers and policy-makers, so that best-practice management can be implemented. A key element of this knowledge sharing must be in raising awareness of the multiple ecosystem services underpinned by soils, and the natural capital they provide. The International Year of Soils in 2015 presents the perfect opportunity to begin a step-change in how we harness scientific knowledge to bring about more sustainable use of soils for a secure global society.

Biogeochemical impacts of wildfires over four millennia in a Rocky Mountain subalpine watershed.

Science.gov (United States)

Dunnette, Paul V; Higuera, Philip E; McLauchlan, Kendra K; Derr, Kelly M; Briles, Christy E; Keefe, Margaret H

2014-08-01

Wildfires can significantly alter forest carbon (C) storage and nitrogen (N) availability, but the long-term biogeochemical legacy of wildfires is poorly understood. We obtained a lake-sediment record of fire and biogeochemistry from a subalpine forest in Colorado, USA, to examine the nature, magnitude, and duration of decadal-scale, fire-induced ecosystem change over the past c. 4250 yr. The high-resolution record contained 34 fires, including 13 high-severity events within the watershed. High-severity fires were followed by increased sedimentary N stable isotope ratios (δ15N) and bulk density, and decreased C and N concentrations--reflecting forest floor destruction, terrestrial C and N losses, and erosion. Sustained low sediment C : N c. 20-50 yr post-fire indicates reduced terrestrial organic matter subsidies to the lake. Low sedimentary δ15N c. 50-70 yr post-fire, coincident with C and N recovery, suggests diminishing terrestrial N availability during stand development. The magnitude of post-fire changes generally scaled directly with inferred fire severity. Our results support modern studies of forest successional C and N accumulation and indicate pronounced, long-lasting biogeochemical impacts of wildfires in subalpine forests. However, even repeated high-severity fires over millennia probably did not deplete C or N stocks, because centuries between high-severity fires allowed for sufficient biomass recovery. © 2014 The Authors. New Phytologist © 2014 New Phytologist Trust.

Effects of Model Resolution and Ocean Mixing on Forced Ice-Ocean Physical and Biogeochemical Simulations Using Global and Regional System Models

Science.gov (United States)

Jin, Meibing; Deal, Clara; Maslowski, Wieslaw; Matrai, Patricia; Roberts, Andrew; Osinski, Robert; Lee, Younjoo J.; Frants, Marina; Elliott, Scott; Jeffery, Nicole; Hunke, Elizabeth; Wang, Shanlin

2018-01-01

The current coarse-resolution global Community Earth System Model (CESM) can reproduce major and large-scale patterns but is still missing some key biogeochemical features in the Arctic Ocean, e.g., low surface nutrients in the Canada Basin. We incorporated the CESM Version 1 ocean biogeochemical code into the Regional Arctic System Model (RASM) and coupled it with a sea-ice algal module to investigate model limitations. Four ice-ocean hindcast cases are compared with various observations: two in a global 1° (40˜60 km in the Arctic) grid: G1deg and G1deg-OLD with/without new sea-ice processes incorporated; two on RASM's 1/12° (˜9 km) grid R9km and R9km-NB with/without a subgrid scale brine rejection parameterization which improves ocean vertical mixing under sea ice. Higher-resolution and new sea-ice processes contributed to lower model errors in sea-ice extent, ice thickness, and ice algae. In the Bering Sea shelf, only higher resolution contributed to lower model errors in salinity, nitrate (NO3), and chlorophyll-a (Chl-a). In the Arctic Basin, model errors in mixed layer depth (MLD) were reduced 36% by brine rejection parameterization, 20% by new sea-ice processes, and 6% by higher resolution. The NO3 concentration biases were caused by both MLD bias and coarse resolution, because of excessive horizontal mixing of high NO3 from the Chukchi Sea into the Canada Basin in coarse resolution models. R9km showed improvements over G1deg on NO3, but not on Chl-a, likely due to light limitation under snow and ice cover in the Arctic Basin.

Biogeochemical Processes Regulating the Mobility of Uranium in Sediments

Energy Technology Data Exchange (ETDEWEB)

Belli, Keaton M.; Taillefert, Martial

2016-07-01

This book chapters reviews the latest knowledge on the biogeochemical processes regulating the mobility of uranium in sediments. It contains both data from the literature and new data from the authors.

The Good, the Bad and the Ugly - Interacting Physical, Biogeochemical and Biolological Controls of Nutrient Cycling at Ecohydrological Interfaces

Science.gov (United States)

Krause, S.; Baranov, V. A.; Lewandowski, J.; Blaen, P. J.; Romeijn, P.

2016-12-01

The interfaces between streams, lakes and their bed sediments have for a long time been in the research focus of ecohydrologists, aquatic ecologists and biogeochemists. While over the past decades, critical understanding has been gained of the spatial patterns and temporal dynamics in nutrient cycling at sediment-freshwater interfaces, important question remain as to the actual drivers (physical, biogeochemical and biological) of the often observed hot spots and hot moments of nutrient cycling at these highly reactive systems. This study reports on a combination of laboratory manipulation, artificial stream and field experiments from reach to river network scales to investigate the interplay of physical, biogeochemical and biological drivers of interface nutrient cycling under the impact of and resilience to global environmental change. Our results indicate that biogeochemical hotspots at sediment-freshwater interfaces were controlled not only by reactant mixing ratios and residence time distributions, but strongly affected by patterns in streambed physical properties and bioavailability of organic carbon. Lab incubation experiments revealed that geology, and in particular organic matter content strongly controlled the magnitude of enhanced streambed greenhouse gas production caused by increasing water temperatures. While these findings help to improve our understanding of physical and biogeochemical controls on nutrient cycling, we only start to understand to what degree biological factors can enhance these processes even further. We found that for instance chironomid or brittle star facilitated bioturbation in has the potential to substantially enhance freshwater or marine sediment pore-water flow and respiration. We revealed that ignorance of these important biologically controls on physical exchange fluxes can lead to critical underestimation of whole system respiration and its increase under global environmental change.

Groundwater Inputs to Rivers: Hydrological, Biogeochemical and Ecological Effects Inferred by Environmental Isotopes

Energy Technology Data Exchange (ETDEWEB)

Stellato, L. [Centre for Isotopic Research on Cultural and Environmental heritage (CIRCE), Seconda Universita degli Studi di Napoli, Caserta (Italy); Newman, B. D. [Isotope Hydrology Section, International Atomic Energy Agency, Vienna (Austria)

2013-05-15

In an effort to improve river management, numerous studies over the past two decades have supported the concept that river water and groundwater need to be considered together, as part of a hydrologic continuum. In particular, studies of the interface between surface water and groundwater (the hyporheic zone) have seen the tight collaboration of catchment hydrologists and stream ecologists in order to elucidate processes affecting stream functioning. Groundwater and surface waters interact at different spatial and temporal scales depending on system hydrology and geomorphology, which in turn influence nutrient cycling and in-stream ecology in relation to climatic, geologic, biotic and anthropogenic factors. In this paper, groundwater inputs to rivers are explored from two different and complementary perspectives: the hydrogeological, describing the generally acknowledged mechanisms of streamflow generation and the main factors controlling stream-aquifer interactions, and the ecologic, describing the processes occurring at the hyporheical and the riparian zones and their possible effects on stream functioning and on nutrient cycling, also taking into consideration the impact of human activities. Groundwater inflows to rivers can be important controls on hot moment/hot spot type biogeochemical behaviors. A description of the common methods used to assess these processes is provided emphasizing tracer methods (including physical, chemical and isotopic). In particular, naturally occurring isotopes are useful tools to identify stream discharge components, biogeochemical processes involved in nutrient cycling (such as N and P dynamics), nutrient sources and transport to rivers, and subsurface storage zones and residence times of hyporheic water. Several studies which have employed isotope techniques to clarify the processes occurring when groundwater enters the river,are reported in this chapter, with a view to highlighting both the advantages and limitations of these

A soil-landscape framework for understanding spatial and temporal variability in biogeochemical processes in catchments

Science.gov (United States)

McGuire, K. J.; Bailey, S. W.; Ross, D. S.

2017-12-01

Heterogeneity in biophysical properties within catchments challenges how we quantify and characterize biogeochemical processes and interpret catchment outputs. Interactions between the spatiotemporal variability of hydrological states and fluxes and soil development can spatially structure catchments, leading to a framework for understanding patterns in biogeochemical processes. In an upland, glaciated landscape at the Hubbard Brook Experimental Forest (HBEF) in New Hampshire, USA, we are embracing the structure and organization of soils to understand the spatial relations between runoff production zones, distinct soil-biogeochemical environments, and solute retention and release. This presentation will use observations from the HBEF to demonstrate that a soil-landscape framework is essential in understanding the spatial and temporal variability of biogeochemical processes in this catchment. Specific examples will include how laterally developed soils reveal the location of active runoff production zones and lead to gradients in primary mineral dissolution and the distribution of weathering products along hillslopes. Soil development patterns also highlight potential carbon and nitrogen cycling hotspots, differentiate acidic conditions, and affect the regulation of surface water quality. Overall, this work demonstrates the importance of understanding the landscape-level structural organization of soils in characterizing the variation and extent of biogeochemical processes that occur in catchments.

Determination of dominant biogeochemical processes in a contaminated aquifer-wetland system using multivariate statistical analysis

Science.gov (United States)

Baez-Cazull, S. E.; McGuire, J.T.; Cozzarelli, I.M.; Voytek, M.A.

2008-01-01

Determining the processes governing aqueous biogeochemistry in a wetland hydrologically linked to an underlying contaminated aquifer is challenging due to the complex exchange between the systems and their distinct responses to changes in precipitation, recharge, and biological activities. To evaluate temporal and spatial processes in the wetland-aquifer system, water samples were collected using cm-scale multichambered passive diffusion samplers (peepers) to span the wetland-aquifer interface over a period of 3 yr. Samples were analyzed for major cations and anions, methane, and a suite of organic acids resulting in a large dataset of over 8000 points, which was evaluated using multivariate statistics. Principal component analysis (PCA) was chosen with the purpose of exploring the sources of variation in the dataset to expose related variables and provide insight into the biogeochemical processes that control the water chemistry of the system. Factor scores computed from PCA were mapped by date and depth. Patterns observed suggest that (i) fermentation is the process controlling the greatest variability in the dataset and it peaks in May; (ii) iron and sulfate reduction were the dominant terminal electron-accepting processes in the system and were associated with fermentation but had more complex seasonal variability than fermentation; (iii) methanogenesis was also important and associated with bacterial utilization of minerals as a source of electron acceptors (e.g., barite BaSO4); and (iv) seasonal hydrological patterns (wet and dry periods) control the availability of electron acceptors through the reoxidation of reduced iron-sulfur species enhancing iron and sulfate reduction. Copyright ?? 2008 by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America. All rights reserved.

Surrogate-Based Optimization of Biogeochemical Transport Models

Science.gov (United States)

Prieß, Malte; Slawig, Thomas

2010-09-01

First approaches towards a surrogate-based optimization method for a one-dimensional marine biogeochemical model of NPZD type are presented. The model, developed by Oschlies and Garcon [1], simulates the distribution of nitrogen, phytoplankton, zooplankton and detritus in a water column and is driven by ocean circulation data. A key issue is to minimize the misfit between the model output and given observational data. Our aim is to reduce the overall optimization cost avoiding expensive function and derivative evaluations by using a surrogate model replacing the high-fidelity model in focus. This in particular becomes important for more complex three-dimensional models. We analyse a coarsening in the discretization of the model equations as one way to create such a surrogate. Here the numerical stability crucially depends upon the discrete stepsize in time and space and the biochemical terms. We show that for given model parameters the level of grid coarsening can be choosen accordingly yielding a stable and satisfactory surrogate. As one example of a surrogate-based optimization method we present results of the Aggressive Space Mapping technique (developed by John W. Bandler [2, 3]) applied to the optimization of this one-dimensional biogeochemical transport model.

Linking Chaotic Advection with Subsurface Biogeochemical Processes

Science.gov (United States)

Mays, D. C.; Freedman, V. L.; White, S. K.; Fang, Y.; Neupauer, R.

2017-12-01

This work investigates the extent to which groundwater flow kinematics drive subsurface biogeochemical processes. In terms of groundwater flow kinematics, we consider chaotic advection, whose essential ingredient is stretching and folding of plumes. Chaotic advection is appealing within the context of groundwater remediation because it has been shown to optimize plume spreading in the laminar flows characteristic of aquifers. In terms of subsurface biogeochemical processes, we consider an existing model for microbially-mediated reduction of relatively mobile uranium(VI) to relatively immobile uranium(IV) following injection of acetate into a floodplain aquifer beneath a former uranium mill in Rifle, Colorado. This model has been implemented in the reactive transport code eSTOMP, the massively parallel version of STOMP (Subsurface Transport Over Multiple Phases). This presentation will report preliminary numerical simulations in which the hydraulic boundary conditions in the eSTOMP model are manipulated to simulate chaotic advection resulting from engineered injection and extraction of water through a manifold of wells surrounding the plume of injected acetate. This approach provides an avenue to simulate the impact of chaotic advection within the existing framework of the eSTOMP code.

The effect of biogeochemical processes on pH

NARCIS (Netherlands)

Soetaert, K.E.R.; Hofmann, A.F.; Middelburg, J.J.; Meysman, F.J.R.; Greenwood, J.E.

2007-01-01

The impact of biogeochemical and physical processes on aquatic chemistry is usually expressed in terms of alkalinity. Here we show how to directly calculate the effect of single processes on pH. Under the assumptions of equilibrium and electroneutrality, the rate of change of pH can be calculated as

Global biogeochemical cycle of vanadium.

Science.gov (United States)

Schlesinger, William H; Klein, Emily M; Vengosh, Avner

2017-12-26

Synthesizing published data, we provide a quantitative summary of the global biogeochemical cycle of vanadium (V), including both human-derived and natural fluxes. Through mining of V ores (130 × 10 9 g V/y) and extraction and combustion of fossil fuels (600 × 10 9 g V/y), humans are the predominant force in the geochemical cycle of V at Earth's surface. Human emissions of V to the atmosphere are now likely to exceed background emissions by as much as a factor of 1.7, and, presumably, we have altered the deposition of V from the atmosphere by a similar amount. Excessive V in air and water has potential, but poorly documented, consequences for human health. Much of the atmospheric flux probably derives from emissions from the combustion of fossil fuels, but the magnitude of this flux depends on the type of fuel, with relatively low emissions from coal and higher contributions from heavy crude oils, tar sands bitumen, and petroleum coke. Increasing interest in petroleum derived from unconventional deposits is likely to lead to greater emissions of V to the atmosphere in the near future. Our analysis further suggests that the flux of V in rivers has been incremented by about 15% from human activities. Overall, the budget of dissolved V in the oceans is remarkably well balanced-with about 40 × 10 9 g V/y to 50 × 10 9 g V/y inputs and outputs, and a mean residence time for dissolved V in seawater of about 130,000 y with respect to inputs from rivers.

Biogeochemical cycle of boron in a forest ecosystem: the case study of Montiers beech-stand

International Nuclear Information System (INIS)

Roux, Philippe

2016-01-01

This thesis aims at establishing and understanding the biogeochemical cycle of boron and its isotopes within a forest ecosystem. In that context, many questions remain concerning the dynamics of boron within terrestrial ecosystems: - What are the major sources of boron? - What type of transfer occurs between the compartments of the environment? - What mechanisms are controlling those transfers? In order to establish this biogeochemical cycle, we quantified the different stocks (vegetation, humus and soil) and fluxes (atmospheric dust and dissolved deposition, throughfall, stem-flows, litterfall and drainage) of boron in the study site of Montiers. The use of boron isotopes will give us insight concerning the mechanisms controlling the dynamics of boron. This thesis is divided in 4 main parts: 1. The first part aims at establishing a new method of extraction, purification and measurement of boron and its isotopes within vegetation samples. 2. The second part focuses on the sources and mechanisms controlling boron within atmospheric dust and dissolved deposition on the study site of Montiers. 3. The third part aims at establishing the stocks and fluxes of boron on two distinct soils: a rendisoil (basic pH) and an alocrisoil (acid pH). The goal is to determine the influence of different soil properties on boron dynamics within its biogeochemical cycle. 4. The last part aims at establishing a model of boron and boron isotopes dynamics in the soil plant system. This model is mainly based of the measurement made in 2012. (author) [fr

Morphological, hydrological, biogeochemical and ecological changes and challenges in river restoration - the Thur River case study

Science.gov (United States)

Schirmer, M.; Luster, J.; Linde, N.; Perona, P.; Mitchell, E. A. D.; Barry, D. A.; Hollender, J.; Cirpka, O. A.; Schneider, P.; Vogt, T.; Radny, D.; Durisch-Kaiser, E.

2014-06-01

River restoration can enhance river dynamics, environmental heterogeneity and biodiversity, but the underlying processes governing the dynamic changes need to be understood to ensure that restoration projects meet their goals, and adverse effects are prevented. In particular, we need to comprehend how hydromorphological variability quantitatively relates to ecosystem functioning and services, biodiversity as well as ground- and surface water quality in restored river corridors. This involves (i) physical processes and structural properties, determining erosion and sedimentation, as well as solute and heat transport behavior in surface water and within the subsurface; (ii) biogeochemical processes and characteristics, including the turnover of nutrients and natural water constituents; and (iii) ecological processes and indicators related to biodiversity and ecological functioning. All these aspects are interlinked, requiring an interdisciplinary investigation approach. Here, we present an overview of the recently completed RECORD (REstored CORridor Dynamics) project in which we combined physical, chemical, and biological observations with modeling at a restored river corridor of the perialpine Thur River in Switzerland. Our results show that river restoration, beyond inducing morphologic changes that reshape the river bed and banks, triggered complex spatial patterns of bank infiltration, and affected habitat type, biotic communities and biogeochemical processes. We adopted an interdisciplinary approach of monitoring the continuing changes due to restoration measures to address the following questions: How stable is the morphological variability established by restoration? Does morphological variability guarantee an improvement in biodiversity? How does morphological variability affect biogeochemical transformations in the river corridor? What are some potential adverse effects of river restoration? How is river restoration influenced by catchment-scale hydraulics

[Ammonia-oxidizing archaea and their important roles in nitrogen biogeochemical cycling: a review].

Science.gov (United States)

Liu, Jing-Jing; Wu, Wei-Xiang; Ding, Ying; Shi, De-Zhi; Chen, Ying-Xu

2010-08-01

As the first step of nitrification, ammonia oxidation is the key process in global nitrogen biogeochemical cycling. So far, the autotrophic ammonia-oxidizing bacteria (AOB) in the beta- and gamma-subgroups of proteobacteria have been considered as the most important contributors to ammonia oxidation, but the recent researches indicated that ammonia-oxidizing archaea (AOA) are widely distributed in various kinds of ecosystems and quantitatively predominant, playing important roles in the global nitrogen biogeochemical cycling. This paper reviewed the morphological, physiological, and ecological characteristics and the molecular phylogenies of AOA, and compared and analyzed the differences and similarities of the ammonia monooxygenase (AMO) and its encoding genes between AOA and AOB. In addition, the potential significant roles of AOA in nitrogen biogeochemical cycling in aquatic and terrestrial ecosystems were summarized, and the future research directions of AOA in applied ecology and environmental protection were put forward.

Understanding Arsenic Dynamics in Agronomic Systems to Predict and Prevent Uptake by Crop Plants

Science.gov (United States)

This review is on arsenic in agronomic systems, and covers processes that influence the entry of arsenic into the human food supply. The scope is from sources of arsenic (natural and anthropogenic) in soils, biogeochemical and rhizosphere processes that control arsenic speciatio...

Biogeochemical gradients above a coal tar DNAPL

Energy Technology Data Exchange (ETDEWEB)

Scherr, Kerstin E., E-mail: kerstin.brandstaetter-scherr@boku.ac.at [University of Natural Resources and Life Sciences Vienna (BOKU), Department IFA-Tulln, Institute for Environmental Biotechnology, Konrad Lorenz Strasse 20, 3430 Tulln (Austria); Backes, Diana [University of Natural Resources and Life Sciences Vienna (BOKU), Department IFA-Tulln, Institute for Environmental Biotechnology, Konrad Lorenz Strasse 20, 3430 Tulln (Austria); Scarlett, Alan G. [University of Plymouth, Petroleum and Environmental Geochemistry Group, Biogeochemistry Research Centre, Drake Circus, Plymouth, Devon PL4 8AA (United Kingdom); Lantschbauer, Wolfgang [Government of Upper Austria, Directorate for Environment and Water Management, Division for Environmental Protection, Kärntner Strasse 10-12, 4021 Linz (Austria); Nahold, Manfred [GUT Gruppe Umwelt und Technik GmbH, Ingenieurbüro für Technischen Umweltschutz, Plesching 15, 4040 Linz (Austria)

2016-09-01

Naturally occurring distribution and attenuation processes can keep hydrocarbon emissions from dense non aqueous phase liquids (DNAPL) into the adjacent groundwater at a minimum. In a historically coal tar DNAPL-impacted site, the de facto absence of a plume sparked investigations regarding the character of natural attenuation and DNAPL resolubilization processes at the site. Steep vertical gradients of polycyclic aromatic hydrocarbons, microbial community composition, secondary water quality and redox-parameters were found to occur between the DNAPL-proximal and shallow waters. While methanogenic and mixed-electron acceptor conditions prevailed close to the DNAPL, aerobic conditions and very low dissolved contaminant concentrations were identified in three meters vertical distance from the phase. Comprehensive two-dimensional gas chromatography–mass spectrometry (GC × GC–MS) proved to be an efficient tool to characterize the behavior of the present complex contaminant mixture. Medium to low bioavailability of ferric iron and manganese oxides of aquifer samples was detected via incubation with Shewanella alga and evidence for iron and manganese reduction was collected. In contrast, 16S rDNA phylogenetic analysis revealed the absence of common iron reducing bacteria. Aerobic hydrocarbon degraders were abundant in shallow horizons, while nitrate reducers were dominating in deeper aquifer regions, in addition to a low relative abundance of methanogenic archaea. Partial Least Squares – Canonical Correspondence Analysis (PLS-CCA) suggested that nitrate and oxygen concentrations had the greatest impact on aquifer community structure in on- and offsite wells, which had a similarly high biodiversity (H’ and Chao1). Overall, slow hydrocarbon dissolution from the DNAPL appears to dominate natural attenuation processes. This site may serve as a model for developing legal and technical strategies for the treatment of DNAPL-impacted sites where contaminant plumes are

Natural light illumination system.

Science.gov (United States)

Whang, Allen Jong-Woei; Chen, Yi-Yung; Yang, Shu-Hua; Pan, Po-Hsuan; Chou, Kao-Hsu; Lee, Yu-Chi; Lee, Zong-Yi; Chen, Chi-An; Chen, Cheng-Nan

2010-12-10

In recent years, green energy has undergone a lot of development and has been the subject of many applications. Many research studies have focused on illumination with sunlight as a means of saving energy and creating healthy lighting. Natural light illumination systems have collecting, transmitting, and lighting elements. Today, most daylight collectors use dynamic concentrators; these include Sun tracking systems. However, this design is too expensive to be cost effective. To create a low-cost collector that can be easily installed on a large building, we have designed a static concentrator, which is prismatic and cascadable, to collect sunlight for indoor illumination. The transmission component uses a large number of optical fibers. Because optical fibers are expensive, this means that most of the cost for the system will be related to transmission. In this paper, we also use a prismatic structure to design an optical coupler for coupling n to 1. With the n-to-1 coupler, the number of optical fibers necessary can be greatly reduced. Although this new natural light illumination system can effectively guide collected sunlight and send it to the basement or to other indoor places for healthy lighting, previously there has been no way to manage the collected sunlight when lighting was not desired. To solve this problem, we have designed an optical switch and a beam splitter to control and separate the transmitted light. When replacing traditional sources, the lighting should have similar characteristics, such as intensity distribution and geometric parameters, to those of traditional artificial sources. We have designed, simulated, and optimized an illumination lightpipe with a dot pattern to redistribute the collected sunlight from the natural light illumination system such that it equals the qualities of a traditional lighting system. We also provide an active lighting module that provides lighting from the natural light illumination system or LED auxiliary

Transforming Ocean Observations of the Carbon Budget, Acidification, Hypoxia, Nutrients, and Biological Productivity: a Global Array of Biogeochemical Argo Floats

Science.gov (United States)

Talley, L. D.; Johnson, K. S.; Claustre, H.; Boss, E.; Emerson, S. R.; Westberry, T. K.; Sarmiento, J. L.; Mazloff, M. R.; Riser, S.; Russell, J. L.

2017-12-01

Our ability to detect changes in biogeochemical (BGC) processes in the ocean that may be driven by increasing atmospheric CO2, as well as by natural climate variability, is greatly hindered by undersampling in vast areas of the open ocean. Argo is a major international program that measures ocean heat content and salinity with about 4000 floats distributed throughout the ocean, profiling to 2000 m every 10 days. Extending this approach to a global BGC-Argo float array, using recent, proven sensor technology, and in close synergy with satellite systems, will drive a transformative shift in observing and predicting the effects of climate change on ocean metabolism, carbon uptake, acidification, deoxygenation, and living marine resource management. BGC-Argo will add sensors for pH, oxygen, nitrate, chlorophyll, suspended particles, and downwelling irradiance, with sufficient accuracy for climate studies. Observing System Simulation Experiments (OSSEs) using BGC models indicate that 1000 BGC floats would provide sufficient coverage, hence equipping 1/4 of the Argo array. BGC-Argo (http://biogeochemical-argo.org) will enhance current sustained observational programs such as Argo, GO-SHIP, and long-term ocean time series. BGC-Argo will benefit from deployments on GO-SHIP vessels, which provide sensor verification. Empirically derived algorithms that relate the observed BGC float parameters to the carbon system parameters will provide global information on seasonal ocean-atmosphere carbon exchange. BGC Argo measurements could be paired with other emerging technology, such as pCO2 measurements from ships of opportunity and wave gliders, to extend and validate exchange estimates. BGC-Argo prototype programs already show the potential of a global observing system that can measure seasonal to decadal variability. Various countries have developed regional BGC arrays: Southern Ocean (SOCCOM), North Atlantic Subpolar Gyre (remOcean), Mediterranean (NAOS), the Kuroshio (INBOX

Ecohydrological Interfaces as Dynamic Hotspots of Biogeochemical Cycling

Science.gov (United States)

Krause, Stefan; Lewandowski, Joerg; Hannah, David; McDonald, Karlie; Folegot, Silvia; Baranov, Victor

2016-04-01

Ecohydrological interfaces, represent the boundaries between water-dependent ecosystems that can alter substantially the fluxes of energy and matter. There is still a critical gap of understanding the organisational principles of the drivers and controls of spatially and temporally variable ecohydrological interface functions. This knowledge gap limits our capacity to efficiently quantify, predict and manage the services provided by complex ecosystems. Many ecohydrological interfaces are characterized by step changes in microbial metabolic activity, steep redox gradients and often even thermodynamic phase shifts, for instance at the interfaces between atmosphere and water or soil matrix and macro-pores interfaces. This paper integrates investigations from point scale laboratory microcosm experiments with reach and subcatchment scale tracer experiments and numerical modeling studies to elaborate similarities in the drivers and controls that constitute the enhanced biogeochemical activity of different types of ecohydrologica interfaces across a range of spatial and temporal scales. We therefore combine smart metabolic activity tracers to quantify the impact of bioturbating benthic fauna onto ecosystem respiration and oxygen consumption and investigate at larger scale, how microbial metabolic activity and carbon turnover at the water-sediment interface are controlled by sediment physical and chemical properties as well as water temperatures. Numerical modeling confirmed that experimentally identified hotspots of streambed biogeochemical cycling were controlled by patterns of physical properties such as hydraulic conductivities or bioavailability of organic matter, impacting on residence time distributions and hence reaction times. In contrast to previous research, our investigations thus confirmed that small-scale variability of physical and chemical interface properties had a major impact on biogeochemical processing at the investigated ecohydrological interfaces

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

HYDROBIOGEOCHEM: A coupled model of HYDROlogic transport and mixed BIOGEOCHEMical kinetic/equilibrium reactions in saturated-unsaturated media

Energy Technology Data Exchange (ETDEWEB)

Yeh, G.T.; Salvage, K.M. [Pennsylvania State Univ., University Park, PA (United States). Dept. of Civil and Environmental Engineering; Gwo, J.P. [Oak Ridge National Lab., TN (United States); Zachara, J.M.; Szecsody, J.E. [Pacific Northwest National Lab., Richland, WA (United States)

1998-07-01

The computer program HYDROBIOGEOCHEM is a coupled model of HYDROlogic transport and BIOGEOCHEMical kinetic and/or equilibrium reactions in saturated/unsaturated media. HYDROBIOGEOCHEM iteratively solves the two-dimensional transport equations and the ordinary differential and algebraic equations of mixed biogeochemical reactions. The transport equations are solved for all aqueous chemical components and kinetically controlled aqueous species. HYDROBIOGEOCHEM is designed for generic application to reactive transport problems affected by both microbiological and geochemical reactions in subsurface media. Input to the program includes the geometry of the system, the spatial distribution of finite elements and nodes, the properties of the media, the potential chemical and microbial reactions, and the initial and boundary conditions. Output includes the spatial distribution of chemical and microbial concentrations as a function of time and space, and the chemical speciation at user-specified nodes.

Biogeochemical response to widespread anoxia in the past ocean

NARCIS (Netherlands)

Ruvalcaba Baroni, I.

2015-01-01

Oxygen is a key element for life on earth. Oxygen concentrations in the ocean vary greatly in space and time. These changes are regulated by various physical and biogeochemical processes, such as primary productivity, sea surface temperatures and ocean circulation. In the geological past, several

Biogeochemical linkage between atmosphere and ocean in the eastern equatorial Pacific Ocean: Results from the EqPOS research cruise

Science.gov (United States)

Furutani, H.; Inai, Y.; Aoki, S.; Honda, H.; Omori, Y.; Tanimoto, H.; Iwata, T.; Ueda, S.; Miura, K.; Uematsu, M.

2012-12-01

Eastern equatorial Pacific Ocean is a unique oceanic region from several biogeochemical points of view. It is a remote open ocean with relatively high marine biological activity, which would result in limited influence of human activity but enhanced effect of marine natural processes on atmospheric composition. It is also characterized as high nutrient low chlorophyll (HNLC) ocean, in which availability of trace metals such as iron and zinc limits marine primary production and thus atmospheric deposition of these trace elements to the ocean surface is expected to play an important role in regulating marine primary production and defining unique microbial community. High sea surface temperature in the region generates strong vertical air convection which efficiently brings tropospheric atmospheric composition into stratosphere. In this unique eastern equatorial Pacific Ocean, EqPOS (Equatorial Pacific Ocean and Stratospheric/Tropospheric Atmospheric Study) research cruise was organized as a part of SOLAS Japan activity to understand biogeochemical ocean-atmospheric interaction in the region. Coordinated atmospheric, oceanic, and marine biological observations including sampling/characterization of thin air-sea interfacial layer (sea surface microlayer: SML) and launching large stratospheric air sampling balloons were carried out on-board R/V Hakuho Maru starting from 29 January for 39 days. Biogeochemically important trace/long-lived gases such as CO2, dimethyl sulfide (DMS), and some volatile organic carbons (VOCs) both in the atmosphere and seawater were continuously monitored and their air-sea fluxes were also observed using gradient and eddy-covariance techniques. Atmospheric gas measurement of CO2, CH4, N2O, SF6, CO, H2, Ar and isotopic composition of selected gases were further extended to stratospheric air by balloon-born sampling in addition to a vertical profiling of O3, CO2, and H2O with sounding sondes. Physical and chemical properties of marine

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

Deep-Sea Microbes: Linking Biogeochemical Rates to -Omics Approaches

Science.gov (United States)

Herndl, G. J.; Sintes, E.; Bayer, B.; Bergauer, K.; Amano, C.; Hansman, R.; Garcia, J.; Reinthaler, T.

2016-02-01

Over the past decade substantial progress has been made in determining deep ocean microbial activity and resolving some of the enigmas in understanding the deep ocean carbon flux. Also, metagenomics approaches have shed light onto the dark ocean's microbes but linking -omics approaches to biogeochemical rate measurements are generally rare in microbial oceanography and even more so for the deep ocean. In this presentation, we will show by combining metagenomics, -proteomics and biogeochemical rate measurements on the bulk and single-cell level that deep-sea microbes exhibit characteristics of generalists with a large genome repertoire, versatile in utilizing substrate as revealed by metaproteomics. This is in striking contrast with the apparently rather uniform dissolved organic matter pool in the deep ocean. Combining the different -omics approaches with metabolic rate measurements, we will highlight some major inconsistencies and enigmas in our understanding of the carbon cycling and microbial food web structure in the dark ocean.

IIASA's climate-vegetation-biogeochemical cycle module as a part of an integrated model for climate change

International Nuclear Information System (INIS)

Ganopolski, A.V.; Jonas, M.; Krabec, J.; Olendrzynski, K.; Petoukhov, V.K.; Venevsky, S.V.

1994-01-01

The main objective of this study is the development of a hierarchy of coupled climate biosphere models with a full description of the global biogeochemical cycles. These models are planned for use as the core of a set of integrated models of climate change and they will incorporate the main elements of the Earth system (atmosphere, hydrosphere, pedosphere and biosphere) linked with each other (and eventually with the antroposphere) through the fluxes of heat, momentum, water and through the global biogeochemical cycles of carbon and nitrogen. This set of integrated models can be considered to fill the gap between highly simplified integrated models of climate change and very sophisticated and computationally expensive coupled models, developed on the basis of general circulation models (GCMs). It is anticipated that this range of integrated models will be an effective tool for investigating the broad spectrum of problems connected with the coexistence of human society and biosphere

Biogeochemical Reactions Under Simulated Europa Ocean Conditions

Science.gov (United States)

Amashukeli, X.; Connon, S. A.; Gleeson, D. F.; Kowalczyk, R. S.; Pappalardo, R. T.

2007-12-01

Galileo data have demonstrated the probable presence of a liquid water ocean on Europa, and existence of salts and carbon dioxide in the satellite's surface ice (e.g., Carr et al., 1998; McCord et al., 1999, Pappalardo et al., 1999; Kivelson et al., 2000). Subsequently, the discovery of chemical signatures of extinct or extant life in Europa's ocean and on its surface became a distinct possibility. Moreover, understanding of Europa's potential habitability is now one of the major goals of the Europa Orbiter Flagship mission. It is likely, that in the early stages of Europa's ocean formation, moderately alkaline oceanic sulfate-carbonate species and a magnetite-silicate mantel could have participated in low-temperature biogeochemical sulfur, iron and carbon cycles facilitated by primitive organisms (Zolotov and Shock, 2004). If periodic supplies of fresh rock and sulfate-carbonate ions are available in Europa's ocean, then an exciting prospect exists that life may be present in Europa's ocean today. In our laboratory, we began the study of the plausible biogeochemical reactions under conditions appropriate to Europa's ocean using barophilic psychrophilic organisms that thrive under anaerobic conditions. In the near absence of abiotic synthetic pathways due to low Europa's temperatures, the biotic synthesis may present a viable opportunity for the formation of the organic and inorganic compounds under these extreme conditions. This work is independent of assumptions regarding hydrothermal vents at Europa's ocean floor or surface-derived oxidant sources. For our studies, we have fabricated a high-pressure (5,000 psi) reaction vessel that simulates aqueous conditions on Europa. We were also successful at reviving barophilic psychrophilic strains of Shewanella bacterium, which serve as test organisms in this investigation. Currently, facultative barophilic psychrophilic stains of Shewanella are grown in the presence of ferric food source; the strains exhibiting iron

Targeted quantification of functional enzyme dynamics in environmental samples for microbially mediated biogeochemical processes: Targeted quantification of functional enzyme dynamics

Energy Technology Data Exchange (ETDEWEB)

Li, Minjing [School of Environmental Studies, China University of Geosciences, Wuhan 430074 People' s Republic of China; Gao, Yuqian [Pacific Northwest National Laboratory, Richland, WA 99354 USA; Qian, Wei-Jun [Pacific Northwest National Laboratory, Richland, WA 99354 USA; Shi, Liang [Pacific Northwest National Laboratory, Richland, WA 99354 USA; Liu, Yuanyuan [Pacific Northwest National Laboratory, Richland, WA 99354 USA; Nelson, William C. [Pacific Northwest National Laboratory, Richland, WA 99354 USA; Nicora, Carrie D. [Pacific Northwest National Laboratory, Richland, WA 99354 USA; Resch, Charles T. [Pacific Northwest National Laboratory, Richland, WA 99354 USA; Thompson, Christopher [Pacific Northwest National Laboratory, Richland, WA 99354 USA; Yan, Sen [School of Environmental Studies, China University of Geosciences, Wuhan 430074 People' s Republic of China; Fredrickson, James K. [Pacific Northwest National Laboratory, Richland, WA 99354 USA; Zachara, John M. [Pacific Northwest National Laboratory, Richland, WA 99354 USA; Liu, Chongxuan [Pacific Northwest National Laboratory, Richland, WA 99354 USA; School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen 518055 People' s Republic of China

2017-07-13

Microbially mediated biogeochemical processes are catalyzed by enzymes that control the transformation of carbon, nitrogen, and other elements in environment. The dynamic linkage between enzymes and biogeochemical species transformation has, however, rarely been investigated because of the lack of analytical approaches to efficiently and reliably quantify enzymes and their dynamics in soils and sediments. Herein, we developed a signature peptide-based technique for sensitively quantifying dissimilatory and assimilatory enzymes using nitrate-reducing enzymes in a hyporheic zone sediment as an example. Moreover, the measured changes in enzyme concentration were found to correlate with the nitrate reduction rate in a way different from that inferred from biogeochemical models based on biomass or functional genes as surrogates for functional enzymes. This phenomenon has important implications for understanding and modeling the dynamics of microbial community functions and biogeochemical processes in environments. Our results also demonstrate the importance of enzyme quantification for the identification and interrogation of those biogeochemical processes with low metabolite concentrations as a result of faster enzyme-catalyzed consumption of metabolites than their production. The dynamic enzyme behaviors provide a basis for the development of enzyme-based models to describe the relationship between the microbial community and biogeochemical processes.

Biogeochemical Processes Controlling Microbial Reductive Precipitation of Radionuclides

International Nuclear Information System (INIS)

Fredrickson, James K.; Brooks, Scott C.

2004-01-01

This project is focused on elucidating the principal biogeochemical reactions that govern the concentrations, chemical speciation, and distribution of the redox sensitive contaminants uranium (U) and technetium (Tc) between the aqueous and solid phases. The research is designed to provide new insights into the under-explored areas of competing geochemical and microbiological oxidation-reduction reactions that govern the fate and transport of redox sensitive contaminants and to generate fundamental scientific understanding of the identity and stoichiometry of competing microbial reduction and geochemical oxidation reactions. These goals and objectives are met through a series of hypothesis-driven tasks that focus on (1) the use of well-characterized microorganisms and synthetic and natural mineral oxidants, (2) advanced spectroscopic and microscopic techniques to monitor redox transformations of U and Tc, and (3) the use of flow-through experiments to more closely approximate groundwater environments. The results are providing an improved understanding and predictive capability of the mechanisms that govern the redox dynamics of radionuclides in subsurface environments. For purposes of this poster, the results are divided into three sections: (1) influence of Ca on U(VI) bioreduction; (2) localization of biogenic UO 2 and TcO 2 ; and (3) reactivity of Mn(III/IV) oxides.

Dissolved nutrient exports from natural and human-impacted Neotropical catchments

DEFF Research Database (Denmark)

Gücker, Björn; Silva, Ricky C. S.; Graeber, Daniel

2016-01-01

Aim Neotropical biomes are highly threatened by land-use changes, but the catchment-wide biogeochemical effects are poorly understood. Here, we aim to compare exports of dissolved nitrogen (N) and phosphorus (P) from natural and human-impacted catchments in the Neotropics. Location Neotropics. Me...

Biogeochemical processes on tree islands in the greater everglades: Initiating a new paradigm

Science.gov (United States)

Wetzel, P.R.; Sklar, Fred H.; Coronado, C.A.; Troxler, T.G.; Krupa, S.L.; Sullivan, P.L.; Ewe, S.; Price, R.M.; Newman, S.; Orem, W.H.

2011-01-01

Scientists' understanding of the role of tree islands in the Everglades has evolved from a plant community of minor biogeochemical importance to a plant community recognized as the driving force for localized phosphorus accumulation within the landscape. Results from this review suggest that tree transpiration, nutrient infiltration from the soil surface, and groundwater flow create a soil zone of confluence where nutrients and salts accumulate under the head of a tree island during dry periods. Results also suggest accumulated salts and nutrients are flushed downstream by regional water flows during wet periods. That trees modulate their environment to create biogeochemical hot spots and strong nutrient gradients is a significant ecological paradigm shift in the understanding of the biogeochemical processes in the Everglades. In terms of island sustainability, this new paradigm suggests the need for distinct dry-wet cycles as well as a hydrologic regime that supports tree survival. Restoration of historic tree islands needs further investigation but the creation of functional tree islands is promising. Copyright ?? 2011 Taylor & Francis Group, LLC.

Biogeochemical reactive transport of carbon, nitrogen and iron in the hyporheic zone

Science.gov (United States)

Dwivedi, D.; Steefel, C. I.; Newcomer, M. E.; Arora, B.; Spycher, N.; Hammond, G. E.; Moulton, J. D.; Fox, P. M.; Nico, P. S.; Williams, K. H.; Dafflon, B.; Carroll, R. W. H.

2017-12-01

To understand how biogeochemical processes in the hyporheic zone influence carbon and nitrogen cycling as well as stream biogeochemistry, we developed a biotic and abiotic reaction network and integrated it into a reactive transport simulator - PFLOTRAN. Three-dimensional reactive flow and transport simulations were performed to describe the hyporheic exchange of fluxes from and within an intra-meander region encompassing two meanders of East River in the East Taylor watershed, Colorado. The objectives of this study were to quantify (1) the effect of transience on the export of carbon, nitrogen, and iron; and (2) the biogeochemical transformation of nitrogen and carbon species as a function of the residence time. The model was able to capture reasonably well the observed trends of nitrate and dissolved oxygen values that decreased as well as iron (Fe (II)) values that increased along the meander centerline away from the stream. Hyporheic flow paths create lateral redox zonation within intra-meander regions, which considerably impact nitrogen export into the stream system. Simulation results further demonstrated that low water conditions lead to higher levels of dissolved iron in groundwater, which (Fe (II)> 80%) is exported to the stream on the downstream side during high water conditions. An important conclusion from this study is that reactive transport models representing spatial and temporal heterogeneities are required to identify important factors that contribute to the redox gradients at riverine scales.

Diel biogeochemical processes in terrestrial waters

Science.gov (United States)

Nimick, David A.; Gammons, Christopher H.

2011-01-01

Many biogeochemical processes in rivers and lakes respond to the solar photocycle and produce persistent patterns of measureable phenomena that exhibit a day–night, or 24-h, cycle. Despite a large body of recent literature, the mechanisms responsible for these diel fluctuations are widely debated, with a growing consensus that combinations of physical, chemical, and biological processes are involved. These processes include streamflow variation, photosynthesis and respiration, plant assimilation, and reactions involving photochemistry, adsorption and desorption, and mineral precipitation and dissolution. Diel changes in streamflow and water properties such as temperature, pH, and dissolved oxygen concentration have been widely recognized, and recently, diel studies have focused more widely by considering other constituents such as dissolved and particulate trace metals, metalloids, rare earth elements, mercury, organic matter, dissolved inorganic carbon (DIC), and nutrients. The details of many diel processes are being studied using stable isotopes, which also can exhibit diel cycles in response to microbial metabolism, photosynthesis and respiration, or changes in phase, speciation, or redox state. In addition, secondary effects that diel cycles might have, for example, on biota or in the hyporheic zone are beginning to be considered.This special issue is composed primarily of papers presented at the topical session “Diurnal Biogeochemical Processes in Rivers, Lakes, and Shallow Groundwater” held at the annual meeting of the Geological Society of America in October 2009 in Portland, Oregon. This session was organized because many of the growing number of diel studies have addressed just a small part of the full range of diel cycling phenomena found in rivers and lakes. This limited focus is understandable because (1) fundamental aspects of many diel processes are poorly understood and require detailed study, (2) the interests and expertise of individual

Tidal Marsh Outwelling of Dissolved Organic Matter and Resulting Temporal Variability in Coastal Water Optical and Biogeochemical Properties

Science.gov (United States)

Tzortziou, Maria; Neale, Patrick J.; Megonigal, J. Patrick; Butterworth, Megan; Jaffe, Rudolf; Yamashita, Youhei

2010-01-01

Coastal wetlands are highly dynamic environments at the land-ocean interface where human activities, short-term physical forcings and intense episodic events result in high biological and chemical variability. Long being recognized as among the most productive ecosystems in the world, tidally-influenced coastal marshes are hot spots of biogeochemical transformation and exchange. High temporal resolution observations that we performed in several marsh-estuarine systems of the Chesapeake Bay revealed significant variability in water optical and biogeochemical characteristics at hourly time scales, associated with tidally-driven hydrology. Water in the tidal creek draining each marsh was sampled every hour during several semi-diurnal tidal cycles using ISCO automated samplers. Measurements showed that water leaving the marsh during ebbing tide was consistently enriched in dissolved organic carbon (DOC), frequently by more than a factor of two, compared to water entering the marsh during flooding tide. Estimates of DOC fluxes showed a net DOC export from the marsh to the estuary during seasons of both low and high biomass of marsh vegetation. Chlorophyll amounts were typically lower in the water draining the marsh, compared to that entering the marsh during flooding tide, suggesting that marshes act as transformers of particulate to dissolved organic matter. Moreover, detailed optical and compositional analyses demonstrated that marshes are important sources of optically and chemically distinctive, relatively complex, high molecular weight, aromatic-rich and highly colored dissolved organic compounds. Compared to adjacent estuarine waters, marsh-exported colored dissolved organic matter (CDOM) was characterized by considerably stronger absorption (more than a factor of three in some cases), larger DOC-specific absorption, lower exponential spectral slope, larger fluorescence signal, lower fluorescence per unit absorbance, and higher fluorescence at visible wavelengths

Natural radioactivity aspects of the marine environment

International Nuclear Information System (INIS)

Iyengar, M.A.R.

2005-01-01

A review of the natural radioactivity distributions and their movement in the oceans and their significance, is of considerable interest, while attempting to understand the impact of man-made radioactivity sources on the marine environment. In this context the interesting environmental behaviour of Radium isotopes ( 226 Ra and 228 Ra) and 210 Pb and 210 Po pair of radionuclides in the marine environment -occurring in 238 U and 232 Th natural radionuclides series have been the subject of considerable investigations as part of the marine biogeochemical studies, some aspects of which are discussed

Development of a 3D coupled physical-biogeochemical model for the Marseille coastal area (NW Mediterranean Sea): what complexity is required in the coastal zone?

Science.gov (United States)

Fraysse, Marion; Pinazo, Christel; Faure, Vincent Martin; Fuchs, Rosalie; Lazzari, Paolo; Raimbault, Patrick; Pairaud, Ivane

2013-01-01

Terrestrial inputs (natural and anthropogenic) from rivers, the atmosphere and physical processes strongly impact the functioning of coastal pelagic ecosystems. The objective of this study was to develop a tool for the examination of these impacts on the Marseille coastal area, which experiences inputs from the Rhone River and high rates of atmospheric deposition. Therefore, a new 3D coupled physical/biogeochemical model was developed. Two versions of the biogeochemical model were tested, one model considering only the carbon (C) and nitrogen (N) cycles and a second model that also considers the phosphorus (P) cycle. Realistic simulations were performed for a period of 5 years (2007-2011). The model accuracy assessment showed that both versions of the model were able of capturing the seasonal changes and spatial characteristics of the ecosystem. The model also reproduced upwelling events and the intrusion of Rhone River water into the Bay of Marseille well. Those processes appeared to greatly impact this coastal oligotrophic area because they induced strong increases in chlorophyll-a concentrations in the surface layer. The model with the C, N and P cycles better reproduced the chlorophyll-a concentrations at the surface than did the model without the P cycle, especially for the Rhone River water. Nevertheless, the chlorophyll-a concentrations at depth were better represented by the model without the P cycle. Therefore, the complexity of the biogeochemical model introduced errors into the model results, but it also improved model results during specific events. Finally, this study suggested that in coastal oligotrophic areas, improvements in the description and quantification of the hydrodynamics and the terrestrial inputs should be preferred over increasing the complexity of the biogeochemical model.

A state-space Bayesian framework for estimating biogeochemical transformations using time-lapse geophysical data

Energy Technology Data Exchange (ETDEWEB)

Chen, J.; Hubbard, S.; Williams, K.; Pride, S.; Li, L.; Steefel, C.; Slater, L.

2009-04-15

We develop a state-space Bayesian framework to combine time-lapse geophysical data with other types of information for quantitative estimation of biogeochemical parameters during bioremediation. We consider characteristics of end-products of biogeochemical transformations as state vectors, which evolve under constraints of local environments through evolution equations, and consider time-lapse geophysical data as available observations, which could be linked to the state vectors through petrophysical models. We estimate the state vectors and their associated unknown parameters over time using Markov chain Monte Carlo sampling methods. To demonstrate the use of the state-space approach, we apply it to complex resistivity data collected during laboratory column biostimulation experiments that were poised to precipitate iron and zinc sulfides during sulfate reduction. We develop a petrophysical model based on sphere-shaped cells to link the sulfide precipitate properties to the time-lapse geophysical attributes and estimate volume fraction of the sulfide precipitates, fraction of the dispersed, sulfide-encrusted cells, mean radius of the aggregated clusters, and permeability over the course of the experiments. Results of the case study suggest that the developed state-space approach permits the use of geophysical datasets for providing quantitative estimates of end-product characteristics and hydrological feedbacks associated with biogeochemical transformations. Although tested here on laboratory column experiment datasets, the developed framework provides the foundation needed for quantitative field-scale estimation of biogeochemical parameters over space and time using direct, but often sparse wellbore data with indirect, but more spatially extensive geophysical datasets.

Novel wireless sensors for in situ measurement of sub-ice hydrologic systems

OpenAIRE

Bagshaw, E; Lishman, B; Wadham, J; Bowden, J; Burrow, S; Clare, L; Chandler, D

2014-01-01

Wireless sensors have the potential to provide significant insight into in situ physical and biogeochemical processes in sub-ice hydrologic systems. However, the nature of the glacial environment means that sensor deployment and data return is challenging. We describe two bespoke sensor platforms, electronic tracers or ‘ETracers’, and ‘cryoegg’, for untethered, wireless data collection from glacial hydrologic systems, including subglacial channels. Both employ radio frequencies for data trans...

Biogeochemical anomaly above oil-containing structures in an arid zone. [Growth stimulation of plants by sodium naphthenate used for prospecting

Energy Technology Data Exchange (ETDEWEB)

Grishchenko, O.M.

1983-01-01

Visual biological anomalies above the oil-containing structures are characterized by bright green coloring of the vegetation cover, gigantism of the plants, extended vegetation period of the plants, deformity of the plants, etc. Biological anomalies are associated with geological features and are observed only above the zone of fault disorders of the earth's crust, above deep faults. A conclusion is drawn about the presence above the oil-bearing structures in the arid zone of a biogeochemical anomaly whose origin is explained by the biological activity of oil and its derivatives. The petroleum growth matter is the sodium salt of naphthene acid, a growth stimulator of plants and animals. The oils of the USSR contain 0.8-4.8% naphthene acids, which effuse through the faults into the root area levels of the soil. As a result of stimulation of growth and development by the petroleum growth matter, the vegetation period of the plants is prolonged. Under the influence of natural petroleum growth substances, the height and productivity of the anomalous plants increases 2-3-fold. Formation and manifestation of signs of biogeochemical anomalies above the oil-bearing structures in the arid zone predetermine the following conditions: presence of fault disorders of the earth's crust; salinity of the root area of the soil layer necessary for neutralization of the naphthene acids with subsequent formation of the biologically active naphthenates; aridity of the desert landscape; plain relief excluding color diversity in vegetation cover because of nonuniform wetting, etc. The established biogeochemical anomaly can be used in prospecting and exploration of oil, gas and bitumen, and also in determining the fault disorders of the earth's crust.

Effects of Climate and Ecosystem Disturbances on Biogeochemical Cycling in a Semi-Natural Terrestrial Ecosystem

International Nuclear Information System (INIS)

Beier, Claus; Schmidt, Inger Kappel; Kristensen, Hanne Lakkenborg

2004-01-01

The effects of increased temperature and potential ecosystem disturbances on biogeochemical cycling were investigated by manipulation of temperature in a mixed Calluna/grass heathland in Denmark. A reflective curtain covered the vegetation during the night to reduce the heat loss of IR radiation from the ecosystem to the atmosphere. This 'night time warming' was done for 3 years and warmed the air and soil by 1.1 deg. C. Warming was combined with ecosystem disturbances, including infestation by Calluna heather beetles (Lochmaea suturalis Thompson) causing complete defoliation of Calluna leaves during the summer 2000, and subsequent harvesting of all aboveground biomass during the autumn. Small increases in mineralisation rates were induced by warming and resulted in increased leaching of nitrogen from the organic soil layer. The increased nitrogen leaching from the organic soil layer was re-immobilised in the mineral soil layer as warming stimulated plant growth and thereby increased nitrogen immobilisation. Contradictory to the generally moderate effects of warming, the heather beetle infestation had very strong effects on mineralisation rates and the plant community. The grasses completely out-competed the Calluna plants which had not re-established two years after the infestation, probably due to combined effects of increased nutrient availability and the defoliation of Calluna. On the short term, ecosystem disturbances may have very strong effects on internal ecosystem processes and plant community structure compared to the more long-term effects of climate change

Application of a hybrid multiscale approach to simulate hydrologic and biogeochemical processes in the river-groundwater interaction zone.

Energy Technology Data Exchange (ETDEWEB)

Hammond, Glenn Edward; Yang, Xiaofan; Song, Xuehang; Song, Hyun-Seob; Hou, Zhangshuan; Chen, Xingyuan; Liu, Yuanyuan; Scheibe, Tim

2017-03-01

The groundwater-surface water interaction zone (GSIZ) plays an important role in riverine and watershed ecosystems as the exchange of waters of variable composition and temperature (hydrologic exchange flows) stimulate microbial activity and associated biogeochemical reactions. Variable temporal and spatial scales of hydrologic exchange flows, heterogeneity of the subsurface environment, and complexity of biogeochemical reaction networks in the GSIZ present challenges to incorporation of fundamental process representations and model parameterization across a range of spatial scales (e.g. from pore-scale to field scale). This paper presents a novel hybrid multiscale simulation approach that couples hydrologic-biogeochemical (HBGC) processes between two distinct length scales of interest.

What can high frequency data tell us about hydrological and biogeochemical processes in a permafrost-underlain watershed that we do not already know?

Science.gov (United States)

Carey, S. K.; Shatilla, N. J.; Tang, W.

2017-12-01

Permafrost and frozen ground play a key role in the delivery of water and solutes from the landscape to the stream, and in biogeochemical cycling by acting as a cold season or semi-permanent aquitard. Conceptual models of permafrost hydrology have been well defined for over 40 years, yet renewed interest in the face of global climate change and rapid degradation of frozen ground has provided an opportunity to revisit previous paradigms. At the same time, new instruments and techniques to understand coupled hydrological and biogeochemical processes have emerged, providing a more nuanced view of northern systems. High-frequency sub-hourly measures of flows, water quality and biogeochemical parameters such as salinity and chromophoric dissolved organic matter (CDOM), along with eddy covariance systems provide considerable data, yet using this data to reveal new process information remains challenging. In this presentation, multi-year high frequency data sets of water, solute and carbon fluxes from Granger Creek, an instrumented alpine watershed with discontinuous permafrost within the Wolf Creek Research Basin, Yukon Territory, Canada, will be shown. While several decades of hydrometric and geochemical data exist for Granger Creek, inter-annual variability is considerable and makes evaluating long-term trends difficult. Insights derived from high-frequency sub-hourly salinity, CDOM and flow over recent years reveal that hysteresis loops among variables can be used to assess changing connectivity and flow paths as both magnitude and direction of loops can be used to infer landscape-scale linkages. These patterns highlight spatial connections among landscape units not previously observed, and identify periods when hydrological and biogeochemical cycles are coupled. Evaluation of these patterns at the headwater scale provides alternate hypotheses for how permafrost landscapes will respond to a changing climate.

CMS: Simulated Physical-Biogeochemical Data, SABGOM Model, Gulf of Mexico, 2005-2010

Data.gov (United States)

National Aeronautics and Space Administration — This dataset contains monthly mean ocean surface physical and biogeochemical data for the Gulf of Mexico simulated by the South Atlantic Bight and Gulf of Mexico...

Restoration of biogeochemical function in mangrove forests

Science.gov (United States)

McKee, K.L.; Faulkner, P.L.

2000-01-01

Forest structure of mangrove restoration sites (6 and 14 years old) at two locations (Henderson Creek [HC] and Windstar [WS]) in southwest Florida differed from that of mixed-basin forests (>50 years old) with which they were once contiguous. However, the younger site (HC) was typical of natural, developing forests, whereas the older site (WS) was less well developed with low structural complexity. More stressful physicochemical conditions resulting from incomplete tidal flushing (elevated salinity) and variable topography (waterlogging) apparently affected plant survival and growth at the WS restoration site. Lower leaf fall and root production rates at the WS restoration site, compared with that at HC were partly attributable to differences in hydroedaphic conditions and structural development. However, leaf and root inputs at each restoration site were not significantly different from that in reference forests within the same physiographic setting. Macrofaunal consumption of tethered leaves also did not differ with site history, but was dramatically higher at HC compared with WS, reflecting local variation in leaf litter processing rates, primarily by snails (Melampus coffeus). Degradation of leaves and roots in mesh bags was slow overall at restoration sites, however, particularly at WS where aerobic decomposition may have been more limited. These findings indicate that local or regional factors such as salinity regime act together with site history to control primary production and turnover rates of organic matter in restoration sites. Species differences in senescent leaf nitrogen content and degradation rates further suggest that restoration sites dominated by Laguncularia racemosa and Rhizophora mangle should exhibit slower recycling of nutrients compared with natural basin forests where Avicennia germinans is more abundant. Structural development and biogeochemical functioning of restored mangrove forests thus depend on a number of factors, but site

Subsurface Biogeochemical Research FY11 Second Quarter Performance Measure

Energy Technology Data Exchange (ETDEWEB)

Scheibe, Timothy D.

2011-03-31

The Subsurface Biogeochemical Research (SBR) Long Term Measure for 2011 under the Performance Assessment Rating Tool (PART) measure is to "Refine subsurface transport models by developing computational methods to link important processes impacting contaminant transport at smaller scales to the field scale." The second quarter performance measure is to "Provide a report on computational methods linking genome-enabled understanding of microbial metabolism with reactive transport models to describe processes impacting contaminant transport in the subsurface." Microorganisms such as bacteria are by definition small (typically on the order of a micron in size), and their behavior is controlled by their local biogeochemical environment (typically within a single pore or a biofilm on a grain surface, on the order of tens of microns in size). However, their metabolic activity exerts strong influence on the transport and fate of groundwater contaminants of significant concern at DOE sites, in contaminant plumes with spatial extents of meters to kilometers. This report describes progress and key findings from research aimed at integrating models of microbial metabolism based on genomic information (small scale) with models of contaminant fate and transport in aquifers (field scale).

The significance of biogeochemical cycles of macro- and microelements in connection with man-made evolution of the living matter

International Nuclear Information System (INIS)

Ermakov, V.V.

2008-01-01

Biogeochemistry as an integrated science studying the elemental composition of the living matter and its role in migration, transformation, accumulation of chemical elements and their compounds in the biosphere, has again become the leading scientific branch highlighting the man-made evolution of the planet and the pathways of interaction between the man and environment. Nowadays the central problem of biogeochemistry as science about the biosphere is that of pollution of the different taxons of the biosphere. In the most case man-made factors effect on the different organisms and the flow of chemical elements changing their local, regional and global biogeochemical cycles. The concept of balance of O 2 , CO 2 and H 2 O as general condition of the sustained development of the biosphere is considered. The questions of biological rhythms, appearance of microelementhoses and modern systemic biogeochemical methodology of assessment of taxons of the biosphere are considered too

Development of a 3D coupled physical-biogeochemical model for the Marseille coastal area (NW Mediterranean Sea: what complexity is required in the coastal zone?

Directory of Open Access Journals (Sweden)

Marion Fraysse

Full Text Available Terrestrial inputs (natural and anthropogenic from rivers, the atmosphere and physical processes strongly impact the functioning of coastal pelagic ecosystems. The objective of this study was to develop a tool for the examination of these impacts on the Marseille coastal area, which experiences inputs from the Rhone River and high rates of atmospheric deposition. Therefore, a new 3D coupled physical/biogeochemical model was developed. Two versions of the biogeochemical model were tested, one model considering only the carbon (C and nitrogen (N cycles and a second model that also considers the phosphorus (P cycle. Realistic simulations were performed for a period of 5 years (2007-2011. The model accuracy assessment showed that both versions of the model were able of capturing the seasonal changes and spatial characteristics of the ecosystem. The model also reproduced upwelling events and the intrusion of Rhone River water into the Bay of Marseille well. Those processes appeared to greatly impact this coastal oligotrophic area because they induced strong increases in chlorophyll-a concentrations in the surface layer. The model with the C, N and P cycles better reproduced the chlorophyll-a concentrations at the surface than did the model without the P cycle, especially for the Rhone River water. Nevertheless, the chlorophyll-a concentrations at depth were better represented by the model without the P cycle. Therefore, the complexity of the biogeochemical model introduced errors into the model results, but it also improved model results during specific events. Finally, this study suggested that in coastal oligotrophic areas, improvements in the description and quantification of the hydrodynamics and the terrestrial inputs should be preferred over increasing the complexity of the biogeochemical model.

How does global biogeochemical cycle become complicated by terrestrial-aquatic interactions ?

Science.gov (United States)

Nakayama, Tadanobu; Maksyutov, Shamil

2015-04-01

Inland water such as river and lake are now known to be important and active components of global carbon cycle though its contribution has remained uncertain due to data scarcity (Battin et al., 2009; Aufdenkampe et al., 2011). The author has developed process-based National Integrated Catchment-based Eco-hydrology (NICE) model (Nakayama, 2008a-b, 2010, 2011a-b, 2012a-c, 2013; Nakayama and Fujita, 2010; Nakayama and Hashimoto, 2011; Nakayama and Shankman, 2013a-b; Nakayama and Watanabe, 2004, 2006, 2008a-b; Nakayama et al., 2006, 2007, 2010, 2012), which incorporates surface-groundwater interactions, includes up- and down-scaling processes between local-global scales, and can simulate iteratively nonlinear feedback between hydrologic, geomorphic, and ecological processes. In this study, NICE was coupled with various biogeochemical models to incorporate biogeochemical cycle including reaction between inorganic and organic carbons (DOC, POC, DIC, pCO2, etc.) in terrestrial and aquatic ecosystems including surface water and groundwater. The coupled model simulated CO2 evasion from inland water in global scale, was relatively in good agreement in that estimated by empirical regression model (Raymond et al., 2013). In particular, the simulated result implied importance of connectivity between terrestrial and aquatic ecosystems in addition to surface and groundwater, and hillslopes and stream channels, etc. The model further improved the accuracy of CH4 flux in wetland which is sensitive to fluctuations of shallow groundwater because the original NICE incorporates 3-D groundwater sub-model and simulates lateral subsurface flow more reasonably. This simulation system would play important role in integration of greenhouse gas budget of the biosphere, quantification of hot spots in boundless biogeochemical cycle, and bridging gap between top-down and bottom-up approaches (Cole et al., 2007; Frei et al., 2012; Kiel and Cardenas, 2014). References; Aufdenkampe, A.K., et al

Permafrost degradation and methane: low risk of biogeochemical climate-warming feedback

International Nuclear Information System (INIS)

Gao Xiang; Adam Schlosser, C; Sokolov, Andrei; Anthony, Katey Walter; Zhuang Qianlai; Kicklighter, David

2013-01-01

Climate change and permafrost thaw have been suggested to increase high latitude methane emissions that could potentially represent a strong feedback to the climate system. Using an integrated earth-system model framework, we examine the degradation of near-surface permafrost, temporal dynamics of inundation (lakes and wetlands) induced by hydro-climatic change, subsequent methane emission, and potential climate feedback. We find that increases in atmospheric CH 4 and its radiative forcing, which result from the thawed, inundated emission sources, are small, particularly when weighed against human emissions. The additional warming, across the range of climate policy and uncertainties in the climate-system response, would be no greater than 0.1 ° C by 2100. Further, for this temperature feedback to be doubled (to approximately 0.2 ° C) by 2100, at least a 25-fold increase in the methane emission that results from the estimated permafrost degradation would be required. Overall, this biogeochemical global climate-warming feedback is relatively small whether or not humans choose to constrain global emissions. (letter)

Patterns in natural systems

NARCIS (Netherlands)

Sewalt, L.

2016-01-01

In the thesis, `Patterns in natural systems’ the formation and evolution of patterns as solutions of several partial differential systems are studied. These mathematical systems model three different biological and ecological processes. First, the way that plankton concentrates in the water column,

Correlating phospholipid fatty acids (PLFA) in a landfill leachate polluted aquifer with biogeochemical factors by multivariate statistical methods

DEFF Research Database (Denmark)

Ludvigsen, Liselotte; Albrechtsen, Hans-Jørgen; Rootzén, Helle

1997-01-01

Different multivariate statistical analyses were applied to phospholipid fatty acids representing the biomass composition and to different biogeochemical parameters measured in 37 samples from a landfill contaminated aquifer at Grindsted Landfill (Denmark). Principal component analysis...... and correspondence analysis were used to identify groups of samples showing similar patterns with respect to biogeochemical variables and phospholipid fatty acid composition. The principal component analysis revealed that for the biogeochemical parameters the first principal component was linked to the pollution...... was used to allocate samples of phospholipid fatty acids into predefined classes. A large percentages of samples were classified correctly when discriminating samples into groups of dissolved organic carbon and specific conductivity, indicating that the biomass is highly influenced by the pollution...

Biogeochemical cycles and biodiversity as key drivers of ecosystem services provided by soils

Science.gov (United States)

Smith, P.; Cotrufo, M. F.; Rumpel, C.; Paustian, K.; Kuikman, P. J.; Elliott, J. A.; McDowell, R.; Griffiths, R. I.; Asakawa, S.; Bustamante, M.; House, J. I.; Sobocká, J.; Harper, R.; Pan, G.; West, P. C.; Gerber, J. S.; Clark, J. M.; Adhya, T.; Scholes, R. J.; Scholes, M. C.

2015-11-01

Soils play a pivotal role in major global biogeochemical cycles (carbon, nutrient, and water), while hosting the largest diversity of organisms on land. Because of this, soils deliver fundamental ecosystem services, and management to change a soil process in support of one ecosystem service can either provide co-benefits to other services or result in trade-offs. In this critical review, we report the state-of-the-art understanding concerning the biogeochemical cycles and biodiversity in soil, and relate these to the provisioning, regulating, supporting, and cultural ecosystem services which they underpin. We then outline key knowledge gaps and research challenges, before providing recommendations for management activities to support the continued delivery of ecosystem services from soils. We conclude that, although soils are complex, there are still knowledge gaps, and fundamental research is still needed to better understand the relationships between different facets of soils and the array of ecosystem services they underpin, enough is known to implement best practices now. There is a tendency among soil scientists to dwell on the complexity and knowledge gaps rather than to focus on what we do know and how this knowledge can be put to use to improve the delivery of ecosystem services. A significant challenge is to find effective ways to share knowledge with soil managers and policy makers so that best management can be implemented. A key element of this knowledge exchange must be to raise awareness of the ecosystems services underpinned by soils and thus the natural capital they provide. We know enough to start moving in the right direction while we conduct research to fill in our knowledge gaps. The lasting legacy of the International Year of Soils in 2015 should be for soil scientists to work together with policy makers and land managers to put soils at the centre of environmental policy making and land management decisions.

Contrasting seasonality in optical-biogeochemical properties of the Baltic Sea.

Science.gov (United States)

Simis, Stefan G H; Ylöstalo, Pasi; Kallio, Kari Y; Spilling, Kristian; Kutser, Tiit

2017-01-01

Optical-biogeochemical relationships of particulate and dissolved organic matter are presented in support of remote sensing of the Baltic Sea pelagic. This system exhibits strong seasonality in phytoplankton community composition and wide gradients of chromophoric dissolved organic matter (CDOM), properties which are poorly handled by existing remote sensing algorithms. Absorption and scattering properties of particulate matter reflected the seasonality in biological (phytoplankton succession) and physical (thermal stratification) processes. Inherent optical properties showed much wider variability when normalized to the chlorophyll-a concentration compared to normalization to either total suspended matter dry weight or particulate organic carbon. The particle population had the largest optical variability in summer and was dominated by organic matter in both seasons. The geographic variability of CDOM and relationships with dissolved organic carbon (DOC) are also presented. CDOM dominated light absorption at blue wavelengths, contributing 81% (median) of the absorption by all water constituents at 400 nm and 63% at 442 nm. Consequentially, 90% of water-leaving radiance at 412 nm originated from a layer (z90) no deeper than approximately 1.0 m. With water increasingly attenuating light at longer wavelengths, a green peak in light penetration and reflectance is always present in these waters, with z90 up to 3.0-3.5 m depth, whereas z90 only exceeds 5 m at biomass < 5 mg Chla m-3. High absorption combined with a weakly scattering particle population (despite median phytoplankton biomass of 14.1 and 4.3 mg Chla m-3 in spring and summer samples, respectively), characterize this sea as a dark water body for which dedicated or exceptionally robust remote sensing techniques are required. Seasonal and regional optical-biogeochemical models, data distributions, and an extensive set of simulated remote-sensing reflectance spectra for testing of remote sensing algorithms are

Contrasting seasonality in optical-biogeochemical properties of the Baltic Sea.

Directory of Open Access Journals (Sweden)

Stefan G H Simis

Full Text Available Optical-biogeochemical relationships of particulate and dissolved organic matter are presented in support of remote sensing of the Baltic Sea pelagic. This system exhibits strong seasonality in phytoplankton community composition and wide gradients of chromophoric dissolved organic matter (CDOM, properties which are poorly handled by existing remote sensing algorithms. Absorption and scattering properties of particulate matter reflected the seasonality in biological (phytoplankton succession and physical (thermal stratification processes. Inherent optical properties showed much wider variability when normalized to the chlorophyll-a concentration compared to normalization to either total suspended matter dry weight or particulate organic carbon. The particle population had the largest optical variability in summer and was dominated by organic matter in both seasons. The geographic variability of CDOM and relationships with dissolved organic carbon (DOC are also presented. CDOM dominated light absorption at blue wavelengths, contributing 81% (median of the absorption by all water constituents at 400 nm and 63% at 442 nm. Consequentially, 90% of water-leaving radiance at 412 nm originated from a layer (z90 no deeper than approximately 1.0 m. With water increasingly attenuating light at longer wavelengths, a green peak in light penetration and reflectance is always present in these waters, with z90 up to 3.0-3.5 m depth, whereas z90 only exceeds 5 m at biomass < 5 mg Chla m-3. High absorption combined with a weakly scattering particle population (despite median phytoplankton biomass of 14.1 and 4.3 mg Chla m-3 in spring and summer samples, respectively, characterize this sea as a dark water body for which dedicated or exceptionally robust remote sensing techniques are required. Seasonal and regional optical-biogeochemical models, data distributions, and an extensive set of simulated remote-sensing reflectance spectra for testing of remote sensing

Contrasting seasonality in optical-biogeochemical properties of the Baltic Sea

Science.gov (United States)

Ylöstalo, Pasi; Kallio, Kari Y.; Spilling, Kristian; Kutser, Tiit

2017-01-01

Optical-biogeochemical relationships of particulate and dissolved organic matter are presented in support of remote sensing of the Baltic Sea pelagic. This system exhibits strong seasonality in phytoplankton community composition and wide gradients of chromophoric dissolved organic matter (CDOM), properties which are poorly handled by existing remote sensing algorithms. Absorption and scattering properties of particulate matter reflected the seasonality in biological (phytoplankton succession) and physical (thermal stratification) processes. Inherent optical properties showed much wider variability when normalized to the chlorophyll-a concentration compared to normalization to either total suspended matter dry weight or particulate organic carbon. The particle population had the largest optical variability in summer and was dominated by organic matter in both seasons. The geographic variability of CDOM and relationships with dissolved organic carbon (DOC) are also presented. CDOM dominated light absorption at blue wavelengths, contributing 81% (median) of the absorption by all water constituents at 400 nm and 63% at 442 nm. Consequentially, 90% of water-leaving radiance at 412 nm originated from a layer (z90) no deeper than approximately 1.0 m. With water increasingly attenuating light at longer wavelengths, a green peak in light penetration and reflectance is always present in these waters, with z90 up to 3.0–3.5 m depth, whereas z90 only exceeds 5 m at biomass < 5 mg Chla m-3. High absorption combined with a weakly scattering particle population (despite median phytoplankton biomass of 14.1 and 4.3 mg Chla m-3 in spring and summer samples, respectively), characterize this sea as a dark water body for which dedicated or exceptionally robust remote sensing techniques are required. Seasonal and regional optical-biogeochemical models, data distributions, and an extensive set of simulated remote-sensing reflectance spectra for testing of remote sensing algorithms

Pre-treatments, characteristics, and biogeochemical dynamics of dissolved organic matter in sediments: A review.

Science.gov (United States)

Chen, Meilian; Hur, Jin

2015-08-01

Dissolved organic matter (DOM) in sediments, termed here sediment DOM, plays a variety of important roles in global biogeochemical cycling of carbon and nutrients as well as in the fate and transport of xenobiotics. Here we reviewed sediment DOM, including pore waters and water extractable organic matter from inland and coastal sediments, based on recent literature (from 1996 to 2014). Sampling, pre-treatment, and characterization methods for sediment DOM were summarized. The characteristics of sediment DOM have been compared along an inland to coastal ecosystems gradient and also with the overlying DOM in water column to distinguish the unique nature of it. Dissolved organic carbon (DOC) from inland sediment DOM was generally higher than coastal areas, while no notable differences were found for their aromaticity and apparent molecular weight. Fluorescence index (FI) revealed that mixed sources are dominant for inland sediment DOM, but marine end-member prevails for coastal sediment DOM. Many reports showed that sediments operate as a net source of DOC and chromophoric DOM (CDOM) to the water column. Sediment DOM has shown more enrichment of nitrogen- and sulfur-containing compounds in the elemental signature than the overlying DOM. Fluorescent fingerprint investigated by excitation-emission matrix coupled with parallel factor analysis (EEM-PARAFAC) further demonstrated the characteristics of sediment DOM lacking in the photo-oxidized and the intermediate components, which are typically present in the overlying surface water. In addition, the biogeochemical changes in sediment DOM and the subsequent environmental implications were discussed with the focus on the binding and the complexation properties with pollutants. Copyright © 2015 Elsevier Ltd. All rights reserved.

Multiscale Investigation on Biofilm Distribution and Its Impact on Macroscopic Biogeochemical Reaction Rates: BIOFILM DISTRIBUTION AND RATE SCALING

Energy Technology Data Exchange (ETDEWEB)

Yan, Zhifeng [Institute of Surface-Earth System Science, Tianjin University, Tianjin China; Pacific Northwest National Laboratory, Richland WA USA; Liu, Chongxuan [Pacific Northwest National Laboratory, Richland WA USA; School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen China; Liu, Yuanyuan [Pacific Northwest National Laboratory, Richland WA USA; School of Earth Science and Engineering, Nanjing University, Nanjing China; Bailey, Vanessa L. [Pacific Northwest National Laboratory, Richland WA USA

2017-11-01

Biofilms are critical locations for biogeochemical reactions in the subsurface environment. The occurrence and distribution of biofilms at microscale as well as their impacts on macroscopic biogeochemical reaction rates are still poorly understood. This paper investigated the formation and distributions of biofilms in heterogeneous sediments using multiscale models, and evaluated the effects of biofilm heterogeneity on local and macroscopic biogeochemical reaction rates. Sediment pore structures derived from X-ray computed tomography were used to simulate the microscale flow dynamics and biofilm distribution in the sediment column. The response of biofilm formation and distribution to the variations in hydraulic and chemical properties was first examined. One representative biofilm distribution was then utilized to evaluate its effects on macroscopic reaction rates using nitrate reduction as an example. The results revealed that microorganisms primarily grew on the surfaces of grains and aggregates near preferential flow paths where both electron donor and acceptor were readily accessible, leading to the heterogeneous distribution of biofilms in the sediments. The heterogeneous biofilm distribution decreased the macroscopic rate of biogeochemical reactions as compared with those in homogeneous cases. Operationally considering the heterogeneous biofilm distribution in macroscopic reactive transport models such as using dual porosity domain concept can significantly improve the prediction of biogeochemical reaction rates. Overall, this study provided important insights into the biofilm formation and distribution in soils and sediments as well as their impacts on the macroscopic manifestation of reaction rates.

Evaluating Southern Ocean Carbon Eddy-Pump From Biogeochemical-Argo Floats

Science.gov (United States)

Llort, Joan; Langlais, C.; Matear, R.; Moreau, S.; Lenton, A.; Strutton, Peter G.

2018-02-01

The vertical transport of surface water and carbon into ocean's interior, known as subduction, is one of the main mechanisms through which the ocean influences Earth's climate. New instrumental approaches have shown the occurrence of localized and intermittent subduction episodes associated with small-scale ocean circulation features. These studies also revealed the importance of such events for the export of organic matter, the so-called eddy-pump. However, the transient and localized nature of episodic subduction hindered its large-scale evaluation to date. In this work, we present an approach to detect subduction events at the scale of the Southern Ocean using measurements collected by biogeochemical autonomous floats (BGCArgo). We show how subduction events can be automatically identified as anomalies of spiciness and Apparent Oxygen Utilization (AOU) below the mixed layer. Using this methodology over more than 4,000 profiles, we detected 40 subduction events unevenly distributed across the Sothern Ocean. Events were more likely found in hot spots of eddy kinetic energy (EKE), downstream major bathymetric features. Moreover, the bio-optical measurements provided by BGCArgo allowed measuring the amount of Particulate Organic Carbon (POC) being subducted and assessing the contribution of these events to the total downward carbon flux at 100 m (EP100). We estimated that the eddy-pump represents less than 19% to the EP100 in the Southern Ocean, although we observed particularly strong events able to locally duplicate the EP100. This approach provides a novel perspective on where episodic subduction occurs that will be naturally improved as BGCArgo observations continue to increase.

Extracellular Electron Transport Coupling Biogeochemical Processes Centimeters

DEFF Research Database (Denmark)

Risgaard-Petersen, Nils; Fossing, Henrik; Christensen, Peter Bondo

2010-01-01

of the oxygen uptake in laboratory incubations of initially homogenized and stabilized sediment. Using microsensors and process rate measurements we further investigated the effect of the electric currents on sediment biogeochemistry. Dissolved sulfide readily donated electrons to the networks and could...... confirmed the depth range of the electric communication and indicated donation of electrons directly from organotrophic bacteria. The separation of oxidation and reduction processes created steep pH gradients eventually causing carbonate precipitation at the surface. The results indicate that electron...... exchanging organisms have major biogeochemical importance as they allow widely separated electron donors and acceptors to react with one another....

Reanalysis of biogeochemical properties in the Mediterranean Sea

Science.gov (United States)

Cossarini, Gianpiero; Teruzzi, Anna; Salon, Stefano; Solidoro, Cosimo

2014-05-01

In the 3D variational (3DVAR) assimilation approach the error covariance matrix can be decomposed in a series of operators. The decomposition makes the 3DVAR particularly suitable for marine biogeochemistry data assimilation, because of the reduced computational costs of the method and its modularity, which allows to define the covariance among the biogeochemical variables in a specific operator. In the present work, the results of 3DVAR assimilation of surface chlorophyll concentration in a multi-annual simulation of the Mediterranean Sea biogeochemistry are presented. The assimilated chlorophyll concentrations are obtained from satellite observations (Volpe et al. 2012). The multi-annual simulation is carried out using the OPATM-BFM model (Lazzari et al. 2012), which describes the low trophic web dynamics and is offline coupled with the MFS physical model (Oddo et al. 2009). In the OPATM-BFM four types of phytoplankton are simulated in terms of their content in carbon, nitrogen, phosphorous, silicon and chlorophyll. In the 3DVAR the error covariance matrix has been decomposed in three different operators, which account for the vertical, the horizontal and the biogeochemical covariance (Teruzzi et al. 2014). The biogeochemical operator propagates the result of the assimilation to the OPATM-BFM variables, providing innovation for the components of the four phytoplankton types. The biogeochemical covariance has been designed supposing that the assimilation preserves the physiological status and the relative abundances of phytoplankton types. Practically, the assimilation preserves the internal quotas of the components for each phytoplankton as long as the optimal growth rate condition are maintained. The quotas preservation is not applied when the phytoplankton is in severe declining growth phase, and the correction provided by the assimilation is set equal to zero. Moreover, the relative abundances among the phytoplankton functional types are preserved. The 3DVAR

A decade of physical and biogeochemical measurements in the Northern Indian Ocean.

Digital Repository Service at National Institute of Oceanography (India)

PrasannaKumar, S.; Sardesai, S.; Ramaiah, N.

at understanding the seasonal variability of physical and biogeochemical parameters. The results showed strongest seasonal cycle in the Arabian Sea with blooms during summer and winter. Upwelling, advection and wind-mixing drive the summer bloom, while the winter...

NATO Advanced Research Workshop on The Biogeochemical Cycling of Sulfur and Nitrogen in the Remote Atmosphere

CERN Document Server

Charlson, Robert; Andreae, Meinrat; Rodhe, Henning

1985-01-01

Viewed from space, the Earth appears as a globe without a beginning or an end. Encompassing the globe is the atmosphere with its three phases-­ gaseous, liquid, and solid--moving in directions influenced by sunlight, gravity, and rotation. The chemical compositions of these phases are determined by biogeochemical cycles. Over the past hundred years, the processes governing the rates and reactions in the atmospheric biogeochemical cycles have typically been studied in regions where scientists lived. Hence, as time has gone by, the advances in our knowledge of atmospheric chemical cycles in remote areas have lagged substantially behind those for more populated areas. Not only are the data less abundant, they are also scattered. Therefore, we felt a workshop would be an excellent mechanism to assess the state­ of-knowledge of the atmospheric cycles of sulfur and nitrogen in remote areas and to make recommendations for future research. Thus, a NATO Advanced Research Workshop '~he Biogeochemical Cycling of Sulfu...

Inferring Properties of Ancient Cyanobacteria from Biogeochemical Activity and Genomes of Siderophilic Cyanobacteria

Science.gov (United States)

McKay, David S.; Brown, I. I.; Tringe, S. G.; Thomas-Keprta, K. E.; Bryant, D. A.; Sarkisova, S. S.; Malley, K.; Sosa, O.; Klatt, C. G.; McKay, D. S.

2010-01-01

Interrelationships between life and the planetary system could have simultaneously left landmarks in genomes of microbes and physicochemical signatures in the lithosphere. Verifying the links between genomic features in living organisms and the mineralized signatures generated by these organisms will help to reveal traces of life on Earth and beyond. Among contemporary environments, iron-depositing hot springs (IDHS) may represent one of the most appropriate natural models [1] for insights into ancient life since organisms may have originated on Earth and probably Mars in association with hydrothermal activity [2,3]. IDHS also seem to be appropriate models for studying certain biogeochemical processes that could have taken place in the late Archean and,-or early Paleoproterozoic eras [4, 5]. It has been suggested that inorganic polyphosphate (PPi), in chains of tens to hundreds of phosphate residues linked by high-energy bonds, is environmentally ubiquitous and abundant [6]. Cyanobacteria (CB) react to increased heavy metal concentrations and UV by enhanced generation of PPi bodies (PPB) [7], which are believed to be signatures of life [8]. However, the role of PPi in oxygenic prokaryotes for the suppression of oxidative stress induced by high Fe is poorly studied. Here we present preliminary results of a new mechanism of Fe mineralization in oxygenic prokaryotes, the effect of Fe on the generation of PPi bodies in CB, as well as preliminary analysis of the diversity and phylogeny of proteins involved in the prevention of oxidative stress in phototrophs inhabiting IDHS.

Biogeochemical control points in a water-limited critical zone

Science.gov (United States)

Chorover, J.; Brooks, P. D.; Gallery, R. E.; McIntosh, J. C.; Olshansky, Y.; Rasmussen, C.

2017-12-01

The routing of water and carbon through complex terrain is postulated to control structure evolution in the sub-humid critical zone of the southwestern US. By combining measurements of land-atmosphere exchange, ecohydrologic partitioning, and subsurface biogeochemistry, we seek to quantify how a heterogeneous (in time and space) distribution of "reactants" impacts both short-term (sub-)catchment response (e.g., pore and surface water chemical dynamics) and long-term landscape evolution (e.g., soil geochemistry/morphology and regolith weathering depth) in watersheds underlain by rhyolite and schist. Instrumented pedons in convergent, planar, and divergent landscape positions show distinct depth-dependent responses to precipitation events. Wetting front propagation, dissolved carbon flux and associated biogeochemical responses (e.g., pulses of CO2 production, O2 depletion, solute release) vary with topography, revealing the influence of lateral subsidies of water and carbon. The impacts of these episodes on the evolution of porous media heterogeneity is being investigated by statistical analysis of pore water chemistry, chemical/spectroscopic studies of solid phase organo-mineral products, sensor-derived water characteristic curves, and quantification of co-located microbial community activity/composition. Our results highlight the interacting effects of critical zone structure and convergent hydrologic flows in the evolution of biogeochemical control points.

The system of nature

CERN Document Server

D'Holbac, Baron

1999-01-01

"The source of Man's unhappiness is his ignorance of Nature."D'Holbach believed that the misery he saw in mankind around him was caused by religion and its superstitious beliefs - that there was a God who controlled destiny and would reward or punish individuals. The System of Nature was written to replace these delusions with a schema of understanding based solely on the physical workings of nature. "Let Man study this nature, let him learn her laws, contemplate her energies." For d'Holbach the soul is only the physical body, understood from a certain point of view, which dies when the body dies. All the events and the nature of the world can be understood in terms of the motion and properties of matter; even the tiniest causes contribute to huge events - a simple change in the diet of an Emperor (or some other such insignificant cause), he suggests might have been capable of "saving kingdoms." For him, nature's laws are fixed and necessary, and if Man wants to find happiness it is best to accept this - if g...

Winter flooding in Dutch stream valley floodplains: biogeochemical effects and vegetation consequences

NARCIS (Netherlands)

Beumer, V.

2009-01-01

Winter flooding in Dutch stream valley floodplains: biogeochemical effects and vegetation consequences Victor Beumer Climatic change has great impacts on stream catchments and their ecology. Expectations are that more extreme climate events will result in undesired flooding in stream catchments. In

Wetland biogeochemical processes and simulation modeling

Science.gov (United States)

Bai, Junhong; Huang, Laibin; Gao, Haifeng; Jia, Jia; Wang, Xin

2018-02-01

As the important landscape with rich biodiversity and high productivity, wetlands can provide numerous ecological services including playing an important role in regulating global biogeochemical cycles, filteringpollutants from terrestrial runoff and atmospheric deposition, protecting and improving water quality, providing living habitats for plants and animals, controlling floodwaters, and retaining surface water flow during dry periods (Reddy and DeLaune, 2008; Qin and Mitsch, 2009; Zhao et al., 2016). However, more than 50% of the world's wetlands had been altered, degraded or lost through a wide range of human activities in the past 150 years, and only a small percentage of the original wetlands remained around the world after over two centuries of intensive development and urbanization (O'connell, 2003; Zhao et al., 2016).

The significance of GW-SW interactions for biogeochemical processes in sandy streambeds

Science.gov (United States)

Arnon, Shai; De Falco, Natalie; Fox, Aryeh; Laube, Gerrit; Schmidt, Christian; Fleckenstein, Jan; Boano, Fulvio

2015-04-01

Stream-groundwater interactions have a major impact on hyporheic exchange fluxes in sandy streambeds. However, the physical complexity of natural streams has limited our ability to study these types of interactions systematically, and to evaluate their importance to biogeochemical processes and nutrient cycling. In this work we were able to quantify the effect of losing and gaining fluxes on hyporheic exchange and nutrient cycling in homogeneous and heterogeneous streambeds by combining experiments in laboratory flumes and modeling. Tracer experiments for measuring hyporheic exchange were done using dyes and NaCl under various combinations of overlying water velocity and losing or gaining fluxes. Nutrient cycling experiments were conducted after growing a benthic biofilm by spiking with Sodium Benzoate (as a source of labile dissolved organic carbon, DOC) and measuring DOC and oxygen dynamics. The combination of experimental observations and modeling revealed that interfacial transport increases with the streambed hydraulic conductivity and proportional to the square of the overlying water velocity. Hyporheic exchange fluxes under losing and gaining flow conditions were similar, and became smaller when the losing or gaining flux increases. Increasing in streambed hydraulic conductivity led to higher hyporheic fluxes and reduction in the effects of losing and gaining flow conditions to constrain exchange. Despite the evident effect of flow conditions on hyporheic exchange, labile DOC uptake was positively linked to increasing overlying water velocity but was not affected by losing and gaining fluxes. This is because microbial aerobic activity was taking place at the upper few millimeters of the streambed as shown by local oxygen consumption rates, which was measured using microelectrodes. Based on modeling work, it is expected that GW-SW interaction will be more significant for less labile DOC and anaerobic processes. Our results enable us to study systematically

Evaluation of heavy metal pollution in bogs of Tomsk region on change in biogeochemical activity of ericaceous shrubs

Science.gov (United States)

Gaskova, L. P.

2018-01-01

The article discusses the change in biogeochemical activity of plant species in bogs under the influence of various types of human impact (roads, cities, drainage of mires, fire). It has been established that ericaceous shrubs, depending on the species, react with varying degrees of intensity to anthropogenic influences. The biogeochemical activity of species increased by 2.5 to 4.8 times in polluted sites.

Natural systems prediction of radionuclide migration

International Nuclear Information System (INIS)

Ewing, R.C.

1991-01-01

This paper reviews the application (and limitations) of data from natural systems to the verification of performance assessments, particularly as they apply to the evaluation of the long-term performance of waste forms, backfill, canister materials, and finally, the integrity of the repository itself. Two specific examples, the corrosion of borosilicate glass and the formation of alteration products of spent fuel, will be discussed. In both cases, inferences are of three types: 1) directly applicable data (i.e. radiation effects, stable phase assemblages): 2) inferences based on the analogous behaviour of the natural and repository systems (e.g. long-term corrosion rate); 3) specific identification of new phenomena that could not have been anticipated from the short term laboratory data (i.e. new mechanisms for the retention or release of radionuclides). The latter can only be derived from the observation of natural systems. Finally, specific attention will be paid to the limitations in the use of natural systems, particularly as the spatial and temporal scales expand, and to the inherent limitations of prediction and verification. (J.P.N.)

Biogeochemical and Ecomorphological Niche Segregation of Mediterranean Woody Species along a Local Gradient

Directory of Open Access Journals (Sweden)

Enrique G. de la Riva

2017-07-01

Full Text Available According with niche theory the species are specialized in different ecological niches, being able to coexist as result of a differential use of resources. In this context, the biogeochemical niche hypothesis proposes that species have an optimal elemental composition which results from the link between the chemical and morphological traits for the optimum plant functioning. Thus, and attending to the limiting similarity concept, different elemental composition and plant structure among co-occurring species may reduce competition, promoting different functional niches. Different functional habits associated with leaf life-span or growth forms are associated with different strategies for resource uptake, which could promote niche partitioning. In the present study, based on the biogeochemical niche concept and the use of resources in different proportions, we have focused on leaf traits (morphological and chemical associated with resource uptake, and explored the niche partitioning among functional habits: leaf life-span (deciduous, evergreen, and semideciduous and growth (tree, shrub, and arborescent-shrub. To this end, we have quantified the hypervolume of the leaf functional trait space (both structure and chemical composition in a sample of 45 Mediterranean woody species from Sierra Morena Mountains (Spain growing along a local soil resource gradient. Our results show consistent variation in functional space for woody communities distributed along the environmental gradient. Thus, communities dominated by deciduous trees with faster growth and a predominant acquisitive strategy were characteristic of bottom forests and showed highest leaf biogeochemical space. While semideciduous shrubs and evergreen (arborescent, trees species, characterized by a conservative strategy, dominated ridge forests and showed smaller functional space. In addition, within each topographical zone or environment type, the foliar biogeochemical niche partitioning

Biogeochemical and Ecomorphological Niche Segregation of Mediterranean Woody Species along a Local Gradient.

Science.gov (United States)

de la Riva, Enrique G; Marañón, Teodoro; Violle, Cyrille; Villar, Rafael; Pérez-Ramos, Ignacio M

2017-01-01

According with niche theory the species are specialized in different ecological niches, being able to coexist as result of a differential use of resources. In this context, the biogeochemical niche hypothesis proposes that species have an optimal elemental composition which results from the link between the chemical and morphological traits for the optimum plant functioning. Thus, and attending to the limiting similarity concept, different elemental composition and plant structure among co-occurring species may reduce competition, promoting different functional niches. Different functional habits associated with leaf life-span or growth forms are associated with different strategies for resource uptake, which could promote niche partitioning. In the present study, based on the biogeochemical niche concept and the use of resources in different proportions, we have focused on leaf traits (morphological and chemical) associated with resource uptake, and explored the niche partitioning among functional habits: leaf life-span (deciduous, evergreen, and semideciduous) and growth (tree, shrub, and arborescent-shrub). To this end, we have quantified the hypervolume of the leaf functional trait space (both structure and chemical composition) in a sample of 45 Mediterranean woody species from Sierra Morena Mountains (Spain) growing along a local soil resource gradient. Our results show consistent variation in functional space for woody communities distributed along the environmental gradient. Thus, communities dominated by deciduous trees with faster growth and a predominant acquisitive strategy were characteristic of bottom forests and showed highest leaf biogeochemical space. While semideciduous shrubs and evergreen (arborescent, trees) species, characterized by a conservative strategy, dominated ridge forests and showed smaller functional space. In addition, within each topographical zone or environment type, the foliar biogeochemical niche partitioning would underlie the

Understanding Arsenic Dynamics in Agronomic Systems to ...

Science.gov (United States)

This review is on arsenic in agronomic systems, and covers processes that influence the entry of arsenic into the human food supply. The scope is from sources of arsenic (natural and anthropogenic) in soils, biogeochemical and rhizosphere processes that control arsenic speciation and availability, through to mechanisms of uptake by crop plants and potential mitigation strategies. This review makes a case for taking steps to prevent or limit crop uptake of arsenic, wherever possible, and to work toward a long-term solution to the presence of arsenic in agronomic systems. The past two decades have seen important advances in our understanding of how biogeochemical and physiological processes influence human exposure to soil arsenic, and thus must now prompt an informed reconsideration and unification of regulations to protect the quality of agricultural and residential soils. Consumption of staple foods such as rice, beverages such as apple juice, or vegetables grown in historically arsenic-contaminated soils is now recognized as a tangible route of arsenic exposure that, in many cases, is more significant than exposure from drinking water. Understanding the sources of arsenic to crop plants and the factors that influence them is key to reducing exposure now and preventing exposure in future. In addition to the abundant natural sources of arsenic, there are a large number of industrial and agricultural sources of arsenic to the soil; from mining wastes, coal fly

Estimation of Net Groundwater Recharge Using Natural Drawdown Events in Subtropical Isolated Wetland Ecosystems

Science.gov (United States)

Perkins, D. B.; Min, J.; Jawitz, J. W.

2008-12-01

Restoration of ditched and drained wetlands in the Lake Okeechobee basin, Florida, USA is currently under study for possible amelioration of anthropogenic phosphorus enrichment of the lake. To date most research in this area has focused on the biogeochemical role of these wetlands. Here we focus on the dynamic hydrology of these systems and the resulting control on biogeochemical cycling. Four depressional wetlands in the basin were monitored for approximately three years to understand the interaction between wetland surface water and adjacent upland groundwater system. A coupled hydrologic-biogeochemical model was created to evaluate restoration scenarios. Determining wetland-scale hydraulic conductivity was an important aspect of the hydrologic model. Based on natural drawdown events observed at wetland-upland well pairs, hydraulic conductivities of top sandy soil layers surrounding the isolated wetlands were calculated using the Dupuit equation under a constrained water budget framework. The drawdown-based hydraulic conductivity estimates of 1.1 to 18.7 m/d (geometric mean of 4.8 m/d) were about three times greater than slug test- based values (1.5 ± 1.1 m/d), which is consistent with scale-dependent expectations. Model-based net groundwater recharge rate at each depressional wetland was predicted based on the estimated hydraulic conductivities, which corresponded to 50 to 72% of rainfall in the same period. These variances appeared to be due to the relative difference of ditch bottom elevation controlling the surface runoff as well as the spatial heterogeneity of the sandy aquifer. Results from this study have implications for nutrient loads to Lake Okeechobee via groundwater as well as water quality monitoring and management strategies aimed to reduce solute export (especially P) from the upstream catchment area to Lake Okeechobee.

Nitrous Oxide Emissions from Biofuel Crops and Parameterization in the EPIC Biogeochemical Model

Science.gov (United States)

This presentation describes year 1 field measurements of N2O fluxes and crop yields which are used to parameterize the EPIC biogeochemical model for the corresponding field site. Initial model simulations are also presented.

Intra- versus inter-site macroscale variation in biogeochemical properties along a paddy soil chronosequence

Directory of Open Access Journals (Sweden)

C. Mueller-Niggemann

2012-03-01

Full Text Available In order to assess the intrinsic heterogeneity of paddy soils, a set of biogeochemical soil parameters was investigated in five field replicates of seven paddy fields (50, 100, 300, 500, 700, 1000, and 2000 yr of wetland rice cultivation, one flooded paddy nursery, one tidal wetland (TW, and one freshwater site (FW from a coastal area at Hangzhou Bay, Zhejiang Province, China. All soils evolved from a marine tidal flat substrate due to land reclamation. The biogeochemical parameters based on their properties were differentiated into (i a group behaving conservatively (TC, TOC, TN, TS, magnetic susceptibility, soil lightness and colour parameters, δ¹³C, δ¹⁵N, lipids and n-alkanes and (ii one encompassing more labile properties or fast cycling components (N_mic, C_mic, nitrate, ammonium, DON and DOC. The macroscale heterogeneity in paddy soils was assessed by evaluating intra- versus inter-site spatial variability of biogeochemical properties using statistical data analysis (descriptive, explorative and non-parametric. Results show that the intrinsic heterogeneity of paddy soil organic and minerogenic components per field is smaller than between study sites. The coefficient of variation (CV values of conservative parameters varied in a low range (10% to 20%, decreasing from younger towards older paddy soils. This indicates a declining variability of soil biogeochemical properties in longer used cropping sites according to progress in soil evolution. A generally higher variation of CV values (>20–40% observed for labile parameters implies a need for substantially higher sampling frequency when investigating these as compared to more conservative parameters. Since the representativeness of the sampling strategy could be sufficiently demonstrated, an investigation of long-term carbon accumulation/sequestration trends in topsoils of the 2000 yr paddy chronosequence under wetland rice cultivation

Biogeochemical tracers of the marine cyanobacterium Trichodesmium

Science.gov (United States)

Carpenter, Edward J.; Harvey, H. Rodger; Fry, Brian; Capone, Douglas G.

1997-01-01

We examined the utility of several biogeochemical tracers for following the fate of the planktonic diazotrophic cyanobacterium Trichodesmium in the sea. The presence of a (CIO) fatty acid previously reported was observed in a culture of Trichodesmium but was not found in natural samples. This cyanobacterium had high concentrations of C 14 and C 16 acids, with lesser amounts of several saturated and unsaturated C 18 fatty acids. This composition was similar to that of other marine cyanobacteria. The major hydrocarbon identified was the C 17n-alkane, which was present in all samples from the five stations examined. Sterols common to algae and copepods were observed in many samples along with hopanoids representative of bacteria, suggesting a varied community structure in colonies collected from different stations. We found no unique taxonomic marker of Trichodesmium among the sterols. Measurements of the σ 15N and σ 13C in Trichodesmium samples from the SW Sargasso and NW Caribbean Seas averaged -0.4960 (range from -0.7 to -0.25960) and -12.9%0 (range from -15.2 to -11.9960), respectively, thus confirming previous observations that this cyanobacterial diazotroph has both the lowest σ 15N and highest σ 13C of any marine phytoplankter observed to date. A culture of Trichodesmium grown under diazotrophic conditions had a σ 15N between -1.3 and -3.6960. Our results support the supposition that the relatively low σ 15N and high σ 13C values observed in suspended and sediment-trapped material from some tropical and subtropical seas result from substantial input of C and N by Trichodesmium.

A positive and multi-element conserving time stepping scheme for biogeochemical processes in marine ecosystem models

Science.gov (United States)

Radtke, H.; Burchard, H.

2015-01-01

In this paper, an unconditionally positive and multi-element conserving time stepping scheme for systems of non-linearly coupled ODE's is presented. These systems of ODE's are used to describe biogeochemical transformation processes in marine ecosystem models. The numerical scheme is a positive-definite modification of the Runge-Kutta method, it can have arbitrarily high order of accuracy and does not require time step adaption. If the scheme is combined with a modified Patankar-Runge-Kutta method from Burchard et al. (2003), it also gets the ability to solve a certain class of stiff numerical problems, but the accuracy is restricted to second-order then. The performance of the new scheme on two test case problems is shown.

Thermodynamics at work - on the limits and potentials of biogeochemical processes

Science.gov (United States)

Peiffer, Stefan

2017-04-01

The preferential use of high potential electron acceptors by microorganisms has lead to the classical concept of a redox sequence with a sequential use of O2 nitrate, Fe(III), sulfate, and finally CO2 as electron acceptors for respiration (Stumm & Morgan, 1996). Christian Blodau has rigourously applied this concept to constrain the thermodynamical limits at which specific aquatic systems operate. In sediments from acidic mining lakes his analysis revealed that sulfate reducers are not competitive as long as low-crystallinity ferric oxides are available for organic matter decomposition (Blodau et al, 1998). This analysis opened up the possibility to generalize the linkage between the iron and sulphur cycle in such systems and to constrain the biogeochemical limits for remediation (e. g. Peine et al, 2000). In a similar approach, Beer & Blodau (2007) were able to demonstrate that constraints on the removal of products from acetoclastic methanogenesis in deeper peat layers are inhibiting organic matter decomposition and provide a thermodynamic argument for peat accumulation. In this contribution I will review such ideas and further refine the limits and potentials of biogeochemical reactions in terms of redox-active metastable phases (RAMPS) that are typically mixed-valent carbon-, iron-, and sulfur-containing compounds and which allow for the occurrence of a number of enigmatic reactions, e. g. limited greenhouse gas emission (CH4) under dynamic redox conditions. It is proposed that redox equivalents are generated, stored and recycled during oxidation and reduction cycles thus suppressing methanogenesis (Blodau, 2002). Such RAMPS will preferentially occur at dynamic interfaces being exposed to frequent redox cycles. The concept of RAMPS will be illustrated along the interaction between ferric (hydr)oxides and dissolved sulphide. Recent studies using modern analytical tools revealed the formation of a number of amorphous products within a short time scale (days) both

Possible impacts of global warming on tundra and boreal forest ecosystems - comparison of some biogeochemical models

Energy Technology Data Exchange (ETDEWEB)

Ploechl, M.; Cramer, W.

1995-06-01

Global warming affects the magnitude of carbon, water and nitrogen fluxes between biosphere and atmosphere as well as the distribution of vegetation types. Biogeochemical models, global as well as patch models, can be used to estimate the differences between the mean values of annual net primary production (NPP) for the present and for future climate scenarios. Both approaches rely on the prescribed pattern of vegetation types. Structural, rule based models can predict such patterns, provided that vegetation and climate are in equilibrium. The coupling of biogeochemical and structural models gives the opportunity to test the sensitivity of biogeochemical processes not only to climatic change but also to biome shifts. Whether the annual mean NPP of a vegetation type increses or decreases depends strongly on the assumptions about a CO{sub 2} fertilization effect and nitrogen cycling. Results from our coupled model show that, given that direct CO{sub 2} effects are uncertain, (i) average NPP of these northern biomes might decrease under global warming, but (ii) total NPP of the region would increase, due to the northward shift of the taiga biome. (orig.)

Monitoring strategies and scale appropriate hydrologic and biogeochemical modelling for natural resource management

DEFF Research Database (Denmark)

Bende-Michl, Ulrike; Volk, Martin; Harmel, Daren

2011-01-01

This short communication paper presents recommendations for developing scale-appropriate monitoring and modelling strategies to assist decision making in natural resource management (NRM). These ideas presented here were discussed in the session (S5) ‘Monitoring strategies and scale...... and communication between researcher and model developer on the one side, and natural resource managers and the model users on the other side to increase knowledge in: 1) the limitations and uncertainties of current monitoring and modelling strategies, 2) scale-dependent linkages between monitoring and modelling...

Quantifying the Variability of CH4 Emissions from Pan-Arctic Lakes with Lake Biogeochemical and Landscape Evolution Models

Science.gov (United States)

Tan, Z.; Zhuang, Q.

2014-12-01

Recent studies in the arctic and subarctic show that CH4 emissions from pan-arctic lakes are playing much more significant roles in the regional carbon cycling than previously estimated. Permafrost thawing due to pronounced warming at northern high latitudes affects lake morphology, changing its CH4 emissions. Thermokarst can enlarge the extent of artic lakes, exposing stable ancient carbon buried in the permafrost zone for degradation and changing a previously known carbon sink to a large carbon source. In some areas, the thawing of subarctic discontinuous and isolated permafrost can diminish thermokarst lakes. To date, few models have considered these important hydrological and biogeochemical processes to provide adequate estimation of CH4 emissions from these lakes. To fill this gap, we have developed a process-based climate-sensitive lake biogeochemical model and a landscape evolution model, which have been applied to quantify the state and variability of CH4 emissions from this freshwater system. Site-level experiments show the models are capable to capture the spatial and temporal variability of CH4 emissions from lakes across Siberia and Alaska. With the lake biogeochemical model solely, we estimate that the magnitude of CH4 emissions from lakes is 13.2 Tg yr-1 in the north of 60 ºN at present, which is on the same order of CH4 emissions from northern high-latitude wetlands. The maximum increment is 11.8 Tg CH4 yr-1 by the end of the 21st century when the worst warming scenario is assumed. We expect the landscape evolution model will improve the existing estimates.

Dynamic modeling of nitrogen losses in river networks unravels the coupled effects of hydrological and biogeochemical processes

Science.gov (United States)

Alexander, Richard B.; Böhlke, John Karl; Boyer, Elizabeth W.; David, Mark B.; Harvey, Judson W.; Mulholland, Patrick J.; Seitzinger, Sybil P.; Tobias, Craig R.; Tonitto, Christina; Wollheim, Wilfred M.

2009-01-01

The importance of lotic systems as sinks for nitrogen inputs is well recognized. A fraction of nitrogen in streamflow is removed to the atmosphere via denitrification with the remainder exported in streamflow as nitrogen loads. At the watershed scale, there is a keen interest in understanding the factors that control the fate of nitrogen throughout the stream channel network, with particular attention to the processes that deliver large nitrogen loads to sensitive coastal ecosystems. We use a dynamic stream transport model to assess biogeochemical (nitrate loadings, concentration, temperature) and hydrological (discharge, depth, velocity) effects on reach-scale denitrification and nitrate removal in the river networks of two watersheds having widely differing levels of nitrate enrichment but nearly identical discharges. Stream denitrification is estimated by regression as a nonlinear function of nitrate concentration, streamflow, and temperature, using more than 300 published measurements from a variety of US streams. These relations are used in the stream transport model to characterize nitrate dynamics related to denitrification at a monthly time scale in the stream reaches of the two watersheds. Results indicate that the nitrate removal efficiency of streams, as measured by the percentage of the stream nitrate flux removed via denitrification per unit length of channel, is appreciably reduced during months with high discharge and nitrate flux and increases during months of low-discharge and flux. Biogeochemical factors, including land use, nitrate inputs, and stream concentrations, are a major control on reach-scale denitrification, evidenced by the disproportionately lower nitrate removal efficiency in streams of the highly nitrate-enriched watershed as compared with that in similarly sized streams in the less nitrate-enriched watershed. Sensitivity analyses reveal that these important biogeochemical factors and physical hydrological factors contribute nearly

Relating hyporheic fluxes, residence times, and redox-sensitive biogeochemical processes upstream of beaver dams

Science.gov (United States)

Briggs, Martin A.; Lautz, Laura; Hare, Danielle K.

2013-01-01

Abstract. Small dams enhance the development of patchy microenvironments along stream corridors by trapping sediment and creating complex streambed morphologies. This patchiness drives intricate hyporheic flux patterns that govern the exchange of O2 and redox-sensitive solutes between the water column and the stream bed. We used multiple tracer techniques, naturally occurring and injected, to evaluate hyporheic flow dynamics and associated biogeochemical cycling and microbial reactivity around 2 beaver dams in Wyoming (USA). High-resolution fiber-optic distributed temperature sensing was used to collect temperature data over 9 vertical streambed profiles and to generate comprehensive vertical flux maps using 1-dimensional (1-D) heat-transport modeling. Coincident with these locations, vertical profiles of hyporheic water were collected every week and analyzed for dissolved O2, pH, dissolved organic C, and several conservative and redox-sensitive solutes. In addition, hyporheic and net stream aerobic microbial reactivity were analyzed with a constant-rate injection of the biologically sensitive resazurin (Raz) smart tracer. The combined results revealed a heterogeneous system with rates of downwelling hyporheic flow organized by morphologic unit and tightly coupled to the redox conditions of the subsurface. Principal component analysis was used to summarize the variability of all redox-sensitive species, and results indicated that hyporheic water varied from oxic-stream-like to anoxic-reduced in direct response to the hydrodynamic conditions and associated residence times. The anaerobic transition threshold predicted by the mean O2 Damko

Including natural systems into the system engineering process: benefits to spaceflight and beyond

Science.gov (United States)

Studor, George

2014-03-01

How did we get to the point where we don't have time to be inspired by the wonders of Nature? Our office walls, homes and city streets are so plain that even when we do escape to a retreat with nature all around us, we may be blind to its magnificence. Yet there are many who have applied what can be known of natural systems (NS) to create practical solutions, but often definite applications for them are lacking. Mimicry of natural systems is not only more possible than ever before, but the education and research programs in many major universities are churning out graduates with a real appreciation for Nature's complex integrated systems. What if these skills and perspectives were employed in the teams of systems engineers and the technology developers that support them to help the teams think "outside-the-box" of manmade inventions? If systems engineers (SE) and technology developers regularly asked the question, "what can we learn from Nature that will help us?" as a part of their processes, they would discover another set of potential solutions. Biomimicry and knowledge of natural systems is exploding. What does this mean for systems engineering and technology? Some disciplines such as robotics and medical devices must consider nature constantly. Perhaps it's time for all technology developers and systems engineers to perceive natural systems experts as potential providers of the technologies they need.

Investigation of Great Basin big sagebrush and black greasewood as biogeochemical indicators of uranium mineralization. Final report. National Uranium Resource Evaluation

International Nuclear Information System (INIS)

Diebold, F.E.; McGrath, S.

1982-11-01

The effects of varying phosphate concentrations in natural aqueous systems upon the uptake of uranium by big sagebrush (Artemesia tridentata subsp. tridentata) and black greasewood (Sarcobatus vermiculatus (Hook) Torr.) were investigated. Two separate growth experiments with five drip-flow hyroponic units were used and plant seedlings were grown for 60 days in solutions of varying phosphate and uranium concentrations. Successful growth experiments were obtained only for big sagebrush; black greasewood did not sustain sufficient growth. The phosphate concentration of the water did affect the uptake of uranium by the big sagebrush, and this effect is most pronounced in the region of higher concentrations of uranium in the water. The ratio of the concentration of uranium in the plant to that in the water was observed to decrease with increasing uranium concentration in solution. This is indicative of an absorption barrier in the plants. The field data shows that big sagebrush responds to uranium concentrations in the soil water and not the groundwater. The manifestation of these results is that the use of big sagebrush as a biogeochemical indicator of uranium is not recommended. Since the concentration of phosphate must also be knwon in the water supplying the uranium to the plant, one should analyze this natural aqueous phase as a hydrochemical indicator rather than the big sagebrush

Scaling view by the Virtual Nature Systems

Science.gov (United States)

Klenov, Valeriy

2010-05-01

The Actual Nature Systems (ANS) continually are under spatial-temporal governing external influences from other systems (Meteorology and Geophysics). This influences provide own spatial temporal patterns on the Earth Nature Systems, which reforms these influences by own manner and scales. These at last three systems belong to the Open Non Equilibrium Nature Systems (ONES). The Geophysics and Meteorology Systems are both governing for the ANS on the Earth. They provide as continual energetic pressure and impacts, and direct Extremes from the both systems to the ANS on Earth surface (earthquakes, storms, and others). The Geodynamics of the ANS is under mixing of influence for both systems, on their scales and on dynamics of their spatial-temporal structures, and by own ANS properties, as the ONES. To select influences of external systems on the Earth systems always is among major tasks of the Geomorphology. Mixing of the Systems scales and dynamics provide specific properties for the memory of Earth system. The memory of the ANS has practical value for their multi-purpose management. The knowledge of these properties is the key for research spatial-temporal GeoDynamics and Trends of Earth Nature Systems. Selection of the influences in time and space requires for special tool, requires elaboration and action of the Virtual Nature Systems (VNS), which are enliven computer doubles for analysis Geodynamics of the ANS. The Experience on the VNS enables to assess influence of each and both external factors on the ANS. It is source of knowledge for regional tectonic and climate oscillations, trends, and threats. Research by the VNS for spatial-temporal dynamics and structures of stochastic regimes of governing systems and processes results in stochastic GeoDynamics of environmental processes, in forming of false trends and blanks in natural records. This ‘wild dance' of 2D stochastic patterns and their interaction each other and generates acting structures of river nets

Soil biogeochemical and fungal patterns across a precipitation gradient in the lowland tropical rainforests of French Guiana

Science.gov (United States)

Soong, J.; Verbruggen, E.; Janssens, I.

2016-12-01

The Guyafor network contains over 12 pristine tropical rainforest long-term research sites throughout French Guiana, with a focus on vegetation and environmental monitoring at regular intervals. However, biogeochemical and belowground insights are needed to complete the picture of ecosystem functioning in these lowland tropical rainforests, which are critical to Earth's water and energy balance. Improving our biogeochemical understanding of these ecosystems is needed to improve Earth System Models, which poorly represent tropical systems. In July 2015 we sampled soils and litter from 12 of the Guyafor permanent plots in French Guiana spanning a mean annual precipitation gradient of over 2000 mm per year. We measured soil texture, pH, C, N and available P stocks in the top 30 cm, and fungal biodiversity using ITS DNA sequencing and characterized soil organic matter (SOM) C, N and P distribution among physically defined SOM fractions. We also measured litter layer standing stocks and CNP stoichiometry. We found significant stocks of SOM in the top 30 cm of the soil varying by a factor of 4 in the top 30 cm of soil with a negative correlation of arbuscular mycorrhizal fungi and soil C and N with available P. Available P was also a strong predictor of fungal community composition. Furthermore there is evidence for precipitation and mineralogical influences on leaf litter and SOM dynamics highlighting the importance of heterogeneity in tropical soil substrates and sub-climates in better understanding the biogeochemistry of tropical ecosystems.

Role of zooplankton dynamics for Southern Ocean phytoplankton biomass and global biogeochemical cycles

DEFF Research Database (Denmark)

Le Quéré, Corinne; Buitenhuis, Erik T.; Moriarty, Róisín

2016-01-01

zooplankton community, despite iron limitation of phytoplankton community growth rates. This result has implications for the representation of global biogeochemical cycles in models as zooplankton faecal pellets sink rapidly and partly control the carbon export to the intermediate and deep ocean....

A Biogeochemical Oceanographer at Sea: My Life with Nitrogen and a Nod to Silica

Science.gov (United States)

Dugdale, Richard C.

2018-01-01

My evolution from electrical engineering student to limnologist and then to oceanographer was a consequence of generous mentoring, which led to my use of the 15N tracer technique to measure nitrogen fixation in aquatic systems. The concept of new and regenerated production arose when I applied this method to measure nitrate and ammonium uptake in marine ecosystems. I then showed that enzyme kinetics could be applied to algal nitrogen uptake and used a silicate pump to explain silicate limitation of diatoms in coastal and equatorial upwelling systems. These concepts are now recognized as modern nutrient paradigms in biogeochemical oceanography. My interest in nutrients required field studies and led to my passion for the study of upwelling ecosystems and the establishment of two major international programs, with numerous advisors, collaborators, and students helping along the way.

Searching for biogeochemical hot spots in three dimensions: soil C and N cycling in hydropedologic settings in a northern hardwood forest

Science.gov (United States)

J.L. Morse; S.F. Werner; C.P. Gillin; C.L. Goodale; S.W. Bailey; K.J. McGuire; P.M. Groffman

2014-01-01

Understanding and predicting the extent, location, and function of biogeochemical hot spots at the watershed scale is a frontier in environmental science. We applied a hydropedologic approach to identify (1) biogeochemical differences among morphologically distinct hydropedologic settings and (2) hot spots of microbial carbon (C) and nitrogen (N) cycling activity in a...

Effects of ozone-vegetation coupling on surface ozone air quality via biogeochemical and meteorological feedbacks

Science.gov (United States)

Sadiq, Mehliyar; Tai, Amos P. K.; Lombardozzi, Danica; Martin, Maria Val

2017-02-01

Tropospheric ozone is one of the most hazardous air pollutants as it harms both human health and plant productivity. Foliage uptake of ozone via dry deposition damages photosynthesis and causes stomatal closure. These foliage changes could lead to a cascade of biogeochemical and biogeophysical effects that not only modulate the carbon cycle, regional hydrometeorology and climate, but also cause feedbacks onto surface ozone concentration itself. In this study, we implement a semi-empirical parameterization of ozone damage on vegetation in the Community Earth System Model to enable online ozone-vegetation coupling, so that for the first time ecosystem structure and ozone concentration can coevolve in fully coupled land-atmosphere simulations. With ozone-vegetation coupling, present-day surface ozone is simulated to be higher by up to 4-6 ppbv over Europe, North America and China. Reduced dry deposition velocity following ozone damage contributes to ˜ 40-100 % of those increases, constituting a significant positive biogeochemical feedback on ozone air quality. Enhanced biogenic isoprene emission is found to contribute to most of the remaining increases, and is driven mainly by higher vegetation temperature that results from lower transpiration rate. This isoprene-driven pathway represents an indirect, positive meteorological feedback. The reduction in both dry deposition and transpiration is mostly associated with reduced stomatal conductance following ozone damage, whereas the modification of photosynthesis and further changes in ecosystem productivity are found to play a smaller role in contributing to the ozone-vegetation feedbacks. Our results highlight the need to consider two-way ozone-vegetation coupling in Earth system models to derive a more complete understanding and yield more reliable future predictions of ozone air quality.

Growth and element flux at fine taxonomic resolution in natural microbial communities

Science.gov (United States)

Hungate, Bruce; Mau, Rebecca; Schwartz, Egbert; Caporaso, J. Gregory; Dijkstra, Paul; van Gestel, Natasja; Koch, Benjamin J.; Liu, Cindy M.; McHugh, Theresa; Marks, Jane C.; Morrissey, Ember; Price, Lance B.

2015-04-01

Microorganisms are the engines of global biogeochemical cycles, driving half of all photosynthesis and nearly all decomposition. Yet, quantifying the rates at which uncultured microbial taxa grow and transform elements in intact and highly diverse natural communities in the environment remains among the most pressing challenges in microbial ecology today. Here, we show how shifts in the density of DNA caused by stable isotope incorporation can be used to estimate the growth rates of individual bacterial taxa in intact soil communities. We found that the distribution of growth rates followed the familiar lognormal distribution observed for the abundances, biomasses, and traits of many organisms. Growth rates of most bacterial taxa increased in response to glucose amendment, though the increase in growth observed for many taxa was larger than could be explained by direct utilization of the added glucose for growth, illustrating that glucose addition indirectly stimulated the utilization of other substrates. Variation in growth rates and phylogenetic distances were quantitatively related, connecting evolutionary history and biogeochemical function in intact soil microbial communities. Our approach has the potential to identify biogeochemically significant taxa in the microbial community and quantify their contributions to element transformations and ecosystem processes.

Factors Influencing Divergent Patterns of Phosphorus Availability in NY and PA Biogeochemical `Hotspots'

Science.gov (United States)

Saia, S. M.; Hofmeister, K.; Regan, J. M.; Buda, A. R.; Carrick, H. J.; Walter, M. T.

2016-12-01

Anthropogenic alteration of the soil phosphorus (P) cycle leads to subsequent water quality issues in agricultural dominated watersheds. In the humid Northeastern United States (NE US), variably saturated areas can generate surface runoff that transports P and stimulates biogeochemical processes; these hydrologically dynamic locations are often called biogeochemical `hotspots'. Many studies have evaluated nitrogen and carbon cycling in biogeochemical hot spots but few have focused on P. We hypothesized seasonally wet parts of the landscape (i.e., hotspots) have smaller biologically available P pools because runoff events frequently carry away nutrients like P. To test this hypothesis, we generated soil wetness index (SWI) maps from soil (SURRGO) and elevation (LiDAR rescaled to 3 m) data and used these maps to direct seasonal soil sampling near Klingerstown, Pennsylvania (PA) and Ithaca, New York (NY). We collected 5cm deep soil samples in PA (bimonthly) and NY (monthly) along soil moisture gradients for a range of land cover types (forest, fallow, and cropped) from May through October. We measured soil moisture in the field and percent organic matter (OM), pH, and three increasingly strong soil P extractions (dilute-salt-extractable P, oxalate-extractable P, and total-extractable P) in the laboratory. Our results indicated a negative relationship between dilute-salt-extractable P concentrations and SWI in PA and no relationship between these same variables in NY. We also found positive relationships between each of the three P extractions in PA but only a positive relationship between oxalate-extractable P and total-extractable P in NY. Our findings in PA support our hypothesis; namely, less biologically available P (i.e. dilute-salt-extractable P) is found in wetter areas of the landscape. However, divergent P availability patterns in NY point to further complexities and confounding variables in our understanding in soil P processes. Further studies will look

Laser control of natural disperse systems

Science.gov (United States)

Vlasova, Olga L.; Bezrukova, Alexandra G.

2003-10-01

Different water disperse systems were studied by integral (spectroturbidemetry) and differential light scattering method with a laser as a source of light. The investigation done concerns the state of kaolin dispersions at storage and under dilution as an example of mineral dispersion systems such as natural water. The role of some light scattering parameters for an optical analysis of water dispersions, like the dispersion of erythrocytes and bacterial cells -Escherichia coli is discussed. The results obtained can help to elaborate the methods for on-line optical control fo natural disperse systems (water, air) with mineral and biological particles.

Sunscope natural light systems : tubular skylights

Energy Technology Data Exchange (ETDEWEB)

NONE

2010-07-01

This brochure described a tubular skylight designed by Sunscope Natural Light Systems. The Sunscope is a super-reflective light system in which daylight is reflected down a cylinder to a translucent ceiling fixture that diffuses natural light throughout the room in which it is placed. The Sunscope requires no structure changes, is installed in less than 3 hours, and requires no drywall repairs or repainting. The system eliminates the need for daytime electric lighting, and causes no winter heat losses or summer heat gains. Available in 3 sizes, the Sunscope has no moving parts and is fully maintenance-free. The system was designed for use in commercial and residential applications. 7 figs.

Sorption of organic chemicals at biogeochemical interfaces - calorimetric measurements

Science.gov (United States)

Krüger, J.; Lang, F.; Siemens, J.; Kaupenjohann, M.

2009-04-01

Biogeochemical interfaces in soil act as sorbents for organic chemicals, thereby controlling the degradation and mobility of these substances in terrestrial environments. Physicochemical properties of the organic chemicals and the sorbent determine sorptive interactions. We hypothesize that the sorption of hydrophobic organic chemicals ("R-determined" chemicals) is an entropy-driven partitioning process between the bulk aqueous phase and biogeochemical interface and that the attachment of more polar organic chemicals ("F-determined" chemicals) to mineral surfaces is due to electrostatic interactions and ligand exchange involving functional groups. In order to determine thermodynamic parameters of sorbate/sorbent interactions calorimetric titration experiments have been conducted at 20˚ C using a Nanocalorimeter (TAM III, Thermometric). Solutions of different organic substances ("R-determined" chemicals: phenanthrene, bisphenol A, "F-determined" chemicals: MCPA, bentazone) with concentrations of 100 mol l-1 were added to suspensions of pure minerals (goethite, muscovite, and kaolinite and to polygalacturonic acid (PGA) as model substance for biofilms in soil. Specific surface, porosity, N and C content, particle size and point of zero charge of the mineral were analyzed to characterize the sorbents. The obtained heat quantities for the initial injection of the organic chemicals to the goethite were 55 and 71 J for bisphenol A and phenanthrene ("R-determined representatives") and 92 and 105 J for MCPA and bentazone ("F-determined" representatives). Further experiments with muscovite, kaolinite and PGA are in progress to determine G and H of the adsorption process.

Biogeochemical cycles and biodiversity as key drivers of ecosystem services provided by soils

NARCIS (Netherlands)

Smith, Pete; Cotrufo, M.F.; Rumpel, C.; Paustian, K.; Kuikman, P.J.

2015-01-01

Soils play a pivotal role in major global biogeochemical cycles (carbon, nutrient, and water), while hosting the largest diversity of organisms on land. Because of this, soils deliver fundamental ecosystem services, and management to change a soil process in support of one ecosystem service can

The Southern Ocean biogeochemical divide.

Science.gov (United States)

Marinov, I; Gnanadesikan, A; Toggweiler, J R; Sarmiento, J L

2006-06-22

Modelling studies have demonstrated that the nutrient and carbon cycles in the Southern Ocean play a central role in setting the air-sea balance of CO(2) and global biological production. Box model studies first pointed out that an increase in nutrient utilization in the high latitudes results in a strong decrease in the atmospheric carbon dioxide partial pressure (pCO2). This early research led to two important ideas: high latitude regions are more important in determining atmospheric pCO2 than low latitudes, despite their much smaller area, and nutrient utilization and atmospheric pCO2 are tightly linked. Subsequent general circulation model simulations show that the Southern Ocean is the most important high latitude region in controlling pre-industrial atmospheric CO(2) because it serves as a lid to a larger volume of the deep ocean. Other studies point out the crucial role of the Southern Ocean in the uptake and storage of anthropogenic carbon dioxide and in controlling global biological production. Here we probe the system to determine whether certain regions of the Southern Ocean are more critical than others for air-sea CO(2) balance and the biological export production, by increasing surface nutrient drawdown in an ocean general circulation model. We demonstrate that atmospheric CO(2) and global biological export production are controlled by different regions of the Southern Ocean. The air-sea balance of carbon dioxide is controlled mainly by the biological pump and circulation in the Antarctic deep-water formation region, whereas global export production is controlled mainly by the biological pump and circulation in the Subantarctic intermediate and mode water formation region. The existence of this biogeochemical divide separating the Antarctic from the Subantarctic suggests that it may be possible for climate change or human intervention to modify one of these without greatly altering the other.

Scaling Hydrologic Exchange Flows and Biogeochemical Reactions from Bedforms to Basins

Science.gov (United States)

Harvey, J. W.; Gomez-Velez, J. D.

2015-12-01

River water moves in and out of the main channel along pathways that are perpendicular to the channel's main axis that flow across or beneath the ground surface. These hydrologic exchange flows (HEFs) are difficult to measure, yet no less important than a river's downstream flow, or exchanges with the atmosphere and deeper groundwater (Harvey and Gooseff, 2015, WRR). There are very few comprehensive investigations of exchange fluxes to understand patterns with river size and relative importance of specific types of exchanges. We used the physically based model NEXSS to simulate multiple scales of hyporheic flow and their cumulative effects on solute reaction in large basins (on the order of Chesapeake Bay basin or larger). Our goal was to explain where and when particular types of hyporheic flow are important in enhancing key biogeochemical reactions, such as organic carbon respiration and denitrification. Results demonstrate that hyporheic flux (expressed per unit area of streambed) varies surprisingly little across the continuum of first-order streams to eighth-order rivers, and vertical exchange beneath small bedforms dominates in comparison with lateral flow beneath gravel bars and meanders. Also, the river's entire volume is exchanged many times with hyporheic flow within a basin, and the turnover length (after one entire river volume is exchanged) is strongly influenced by hydrogeomorphic differences between physiographic regions as well as by river size. The cumulative effects on biogeochemical reactions were assessed using a the reaction significance factor, RSF, which computes the cumulative potential for hyporheic reactions using a dimensionless index that balances reaction progress in a single hyporheic flow path against overall processing efficiency of river turnover through hyporheic flow paths of that type. Reaction significance appears to be strongly dominated by hydrologic factors rather than biogeochemical factors, and seems to be dominated by

Concepts and implementations of natural language query systems

Science.gov (United States)

Dominick, Wayne D. (Editor); Liu, I-Hsiung

1984-01-01

The currently developed user language interfaces of information systems are generally intended for serious users. These interfaces commonly ignore potentially the largest user group, i.e., casual users. This project discusses the concepts and implementations of a natural query language system which satisfy the nature and information needs of casual users by allowing them to communicate with the system in the form of their native (natural) language. In addition, a framework for the development of such an interface is also introduced for the MADAM (Multics Approach to Data Access and Management) system at the University of Southwestern Louisiana.

Light-Dependent Transcriptional Regulation of Genes of Biogeochemical Interest in the Diploid and Haploid Life Cycle Stages of Emiliania huxleyi▿ †

Science.gov (United States)

Richier, Sophie; Kerros, Marie-Emmanuelle; de Vargas, Colomban; Haramaty, Liti; Falkowski, Paul G.; Gattuso, Jean-Pierre

2009-01-01

The expression of genes of biogeochemical interest in calcifying and noncalcifying life stages of the coccolithophore Emiliania huxleyi was investigated. Transcripts potentially involved in calcification were tested through a light-dark cycle. These transcripts were more abundant in calcifying cells and were upregulated in the light. Their application as potential candidates for in situ biogeochemical proxies is also suggested. PMID:19304825

Sensitivity of global ocean biogeochemical dynamics to ecosystem structure in a future climate

Science.gov (United States)

Manizza, Manfredi; Buitenhuis, Erik T.; Le Quéré, Corinne

2010-07-01

Terrestrial and oceanic ecosystem components of the Earth System models (ESMs) are key to predict the future behavior of the global carbon cycle. Ocean ecosystem models represent low complexity compared to terrestrial ecosystem models. In this study we use two ocean biogeochemical models based on the explicit representation of multiple planktonic functional types. We impose to the models the same future physical perturbation and compare the response of ecosystem dynamics, export production (EP) and ocean carbon uptake (OCU) to the same physical changes. Models comparison shows that: (1) EP changes directly translate into changes of OCU on decadal time scale, (2) the representation of ecosystem structure plays a pivotal role at linking OCU and EP, (3) OCU is highly sensitive to representation of ecosystem in the Equatorial Pacific and Southern Oceans.

Biogeochemical aspects of uranium mineralization, mining, milling, and remediation

Science.gov (United States)

Campbell, Kate M.; Gallegos, Tanya J.; Landa, Edward R.

2015-01-01

Natural uranium (U) occurs as a mixture of three radioactive isotopes: 238U, 235U, and 234U. Only 235U is fissionable and makes up about 0.7% of natural U, while 238U is overwhelmingly the most abundant at greater than 99% of the total mass of U. Prior to the 1940s, U was predominantly used as a coloring agent, and U-bearing ores were mined mainly for their radium (Ra) and/or vanadium (V) content; the bulk of the U was discarded with the tailings (Finch et al., 1972). Once nuclear fission was discovered, the economic importance of U increased greatly. The mining and milling of U-bearing ores is the first step in the nuclear fuel cycle, and the contact of residual waste with natural water is a potential source of contamination of U and associated elements to the environment. Uranium is mined by three basic methods: surface (open pit), underground, and solution mining (in situ leaching or in situ recovery), depending on the deposit grade, size, location, geology and economic considerations (Abdelouas, 2006). Solid wastes at U mill tailings (UMT) sites can include both standard tailings (i.e., leached ore rock residues) and solids generated on site by waste treatment processes. The latter can include sludge or “mud” from neutralization of acidic mine/mill effluents, containing Fe and a range of coprecipitated constituents, or barium sulfate precipitates that selectively remove Ra (e.g., Carvalho et al., 2007). In this chapter, we review the hydrometallurgical processes by which U is extracted from ore, the biogeochemical processes that can affect the fate and transport of U and associated elements in the environment, and possible remediation strategies for site closure and aquifer restoration.This paper represents the fourth in a series of review papers from the U.S. Geological Survey (USGS) on geochemical aspects of UMT management that span more than three decades. The first paper (Landa, 1980) in this series is a primer on the nature of tailings and radionuclide

Simulation of glacial ocean biogeochemical tracer and isotope distributions based on the PMIP3 suite of climate models

Science.gov (United States)

Khatiwala, Samar; Muglia, Juan; Kvale, Karin; Schmittner, Andreas

2016-04-01

In the present climate system, buoyancy forced convection at high-latitudes together with internal mixing results in a vigorous overturning circulation whose major component is North Atlantic Deep Water. One of the key questions of climate science is whether this "mode" of circulation persisted during glacial periods, and in particular at the Last Glacial Maximum (LGM; 21000 years before present). Resolving this question is both important for advancing our understanding of the climate system, as well as a critical test of numerical models' ability to reliably simulate different climates. The observational evidence, based on interpreting geochemical tracers archived in sediments, is conflicting, as are simulations carried out with state-of-the-art climate models (e.g., as part of the PMIP3 suite), which, due to the computational cost involved, do not by and large include biogeochemical and isotope tracers that can be directly compared with proxy data. Here, we apply geochemical observations to evaluate the ability of several realisations of an ocean model driven by atmospheric forcing from the PMIP3 suite of climate models to simulate global ocean circulation during the LGM. This results in a wide range of circulation states that are then used to simulate biogeochemical tracer and isotope (13C, 14C and Pa/Th) distributions using an efficient, "offline" computational scheme known as the transport matrix method (TMM). One of the key advantages of this approach is the use of a uniform set of biogeochemical and isotope parameterizations across all the different circulations based on the PMIP3 models. We compare these simulated distributions to both modern observations and data from LGM ocean sediments to identify similarities and discrepancies between model and data. We find, for example, that when the ocean model is forced with wind stress from the PMIP3 models the radiocarbon age of the deep ocean is systematically younger compared with reconstructions. Changes in

The Dialectic of the Nature-Society-System

Directory of Open Access Journals (Sweden)

Christian Fuchs

2008-07-01

Full Text Available There are four logical possibilities for conceiving the relationship of nature and society: the reduction of society to nature, the projection of nature into society, dualism, and a nature-society-dialectic. This differentiation results in four different approaches. Nature is a self-organizing system that produces an evolutionary hierarchy of interconnected systems with specific qualities. Society is a product of nature where humans produce and reproduce structures that enable and constrain human practices in dynamic processes. Parts of nature are observed and appropriated by humans from within society, these parts are socially constructed and form a subsystem of society. The self-organization cycle of nature and the self-organization cycle of the socio-sphere are mutually connected in a productive cycle of society where natural self-organization serves as the material foundation that enables and constrains social self-organization and human production processes transform natural structures and incorporate these very structures into society as means of production (technologies, raw materials. The economy is that part of the socio-sphere where the relationship between nature and the socio-sphere is established, the mediation is achieved by human labour processes. Nature enters the economic process as material input in the form of means of production (constant capital: machines, raw materials, auxiliary materials. Organized nature that is part of the production process in the form of technology increases the productivity of labour and hence reduces the costs of variable capital (total amount of wages and increases the speed of the production of surplus value. The production system of modern society is oriented on economic profit and productivity, ecological depletion and pollution are by-products of modernization. The Fordist production model that originated in the West and was copied by the Soviet Union is one of the major causes of the global

Studying Microbial Mat Functioning Amidst "Unexpected Diversity": Methodological Approaches and Initial Results from Metatranscriptomes of Mats Over Diel cycles, iTags from Long Term Manipulations, and Biogeochemical Cycling in Simplified Microbial Mats Constructed from Cultures

Science.gov (United States)

Bebout, B.; Bebout, L. E.; Detweiler, A. M.; Everroad, R. C.; Lee, J.; Pett-Ridge, J.; Weber, P. K.

2014-12-01

Microbial mats are famously amongst the most diverse microbial ecosystems on Earth, inhabiting some of the most inclement environments known, including hypersaline, dry, hot, cold, nutrient poor, and high UV environments. The high microbial diversity of microbial mats makes studies of microbial ecology notably difficult. To address this challenge, we have been using a combination of metagenomics, metatranscriptomics, iTags and culture-based simplified microbial mats to study biogeochemical cycling (H2 production, N2 fixation, and fermentation) in microbial mats collected from Elkhorn Slough, Monterey Bay, California. Metatranscriptomes of microbial mats incubated over a diel cycle have revealed that a number of gene systems activate only during the day in Cyanobacteria, while the remaining appear to be constitutive. The dominant cyanobacterium in the mat (Microcoleus chthonoplastes) expresses several pathways for nitrogen scavenging undocumented in cultured strains, as well as the expression of two starch storage and utilization cycles. Community composition shifts in response to long term manipulations of mats were assessed using iTags. Changes in community diversity were observed as hydrogen fluxes increased in response to a lowering of sulfate concentrations. To produce simplified microbial mats, we have isolated members of 13 of the 15 top taxa from our iTag libraries into culture. Simplified microbial mats and simple co-cultures and consortia constructed from these isolates reproduce many of the natural patterns of biogeochemical cycling in the parent natural microbial mats, but against a background of far lower overall diversity, simplifying studies of changes in gene expression (over the short term), interactions between community members, and community composition changes (over the longer term), in response to environmental forcing.

Historical storage budgets of organic carbon, nutrient and contaminant elements in saltmarsh sediments: Biogeochemical context for managed realignment, Humber Estuary, UK

International Nuclear Information System (INIS)

Andrews, J.E.; Samways, G.; Shimmield, G.B.

2008-01-01

Biogeochemical data from Welwick marsh (Humber Estuary, UK), an actively accreting saltmarsh, provides a decadal-centennial-scale natural analogue for likely future biogeochemical storage effects of managed realignment sites accreting either intertidal muds or saltmarsh. Marsh topographic profiles and progradation history from aerial photographs were combined with 137 Cs and niobium contamination history to establish and verify chronology and sediment mass accumulation. These data, combined with down-core measurements of particulate organic carbon (C org ), organic nitrogen (N org ), particle reactive phosphorus and selected contaminant metal (Zn, Pb, Cu, As and Nb) contents were then used to calculate sediment and chemical storage terms and to quantify changes in these over time. These data are used to help predict likely future biogeochemical storage changes at managed realignment sites in the estuary. The net effect of returning some 26 km 2 of reclaimed land to intertidal environments now (about 25% of the maximum possible realignment storage identified for the estuary) could result in the storage of some 40,000 tonnes a -1 of sediment which would also bury about 800 tonnes a -1 of C org and 40 tonnes a -1 of N org . Particulate contaminant P burial would be around 25 tonnes a -1 along with ∼ 6 tonnes a -1 contaminant Zn, 3 tonnes a -1 contaminant Pb, and ∼ 1 tonnes a -1 contaminant As and Cu. The study also shows that reclamation activities in the outer estuary since the mid-1700s has prevented, in total, the deposition of about 10 million tonnes of sediment, along with 320,000 tonnes of C org and 16,000 tonnes of N org . The study provides a mid-1990s baseline against which future measurements at the site can determine changes in burial fluxes and improvement or deterioration in contaminant metal contents of the sediments. The data are directly relevant for local managed realignment sites but also broadly indicative for sites generally on the European

Biotic and Biogeochemical Feedbacks to Climate Change

Science.gov (United States)

Torn, M. S.; Harte, J.

2002-12-01

Feedbacks to paleoclimate change are evident in ice core records showing correlations of temperature with carbon dioxide, nitrous oxide, and methane. Such feedbacks may be explained by plant and microbial responses to climate change, and are likely to occur under impending climate warming, as evidenced by results of ecosystem climate manipulation experiments and biometeorological observations along ecological and climate gradients. Ecosystems exert considerable influence on climate, by controlling the energy and water balance of the land surface as well as being sinks and sources of greenhouse gases. This presentation will focus on biotic and biogeochemical climate feedbacks on decadal to century time scales, emphasizing carbon storage and energy exchange. In addition to the direct effects of climate on decomposition rates and of climate and CO2 on plant productivity, climate change can alter species composition; because plant species differ in their surface properties, productivity, phenology, and chemistry, climate-induced changes in plant species composition can exert a large influence on the magnitude and sign of climate feedbacks. We discuss the effects of plant species on ecosystem carbon storage that result from characteristic differences in plant biomass and lifetime, allocation to roots vs. leaves, litter quality, microclimate for decomposition and the ultimate stabilization of soil organic matter. We compare the effect of species transitions on transpiration, albedo, and other surface properties, with the effect of elevated CO2 and warming on single species' surface exchange. Global change models and experiments that investigate the effect of climate only on existing vegetation may miss the biggest impacts of climate change on biogeochemical cycling and feedbacks. Quantification of feedbacks will require understanding how species composition and long-term soil processes will change under global warming. Although no single approach, be it experimental

Global biogeochemical provinces of the mesopelagic zone

DEFF Research Database (Denmark)

Reygondeau, Gabriel; Guidi, Lionel; Beaugrand, Gregory

2018-01-01

Aim: Following the biogeographical approach implemented by Longhurst for the epipelagic layer, we propose here to identify a biogeochemical 3-D partition for the mesopelagic layer. The resulting partition characterizes the main deep environmental biotopes and their vertical boundaries on a global...... scale, which can be used as a geographical and ecological framework for conservation biology, ecosystem-based management and for the design of oceanographic investigations. Location: The global ocean. Methods: Based on the most comprehensive environmental climatology available to date, which is both...... of the mesopelagic layer. Results: First, we show via numerical interpretation that the vertical division of the pelagic zone varies and, hence, is not constant throughout the global ocean. Indeed, a latitudinal gradient is found between the epipelagic-mesopelagic and mesopelagic-bathypelagic vertical limits. Second...

Natural interaction for unmanned systems

Science.gov (United States)

Taylor, Glenn; Purman, Ben; Schermerhorn, Paul; Garcia-Sampedro, Guillermo; Lanting, Matt; Quist, Michael; Kawatsu, Chris

2015-05-01

Military unmanned systems today are typically controlled by two methods: tele-operation or menu-based, search-andclick interfaces. Both approaches require the operator's constant vigilance: tele-operation requires constant input to drive the vehicle inch by inch; a menu-based interface requires eyes on the screen in order to search through alternatives and select the right menu item. In both cases, operators spend most of their time and attention driving and minding the unmanned systems rather than on being a warfighter. With these approaches, the platform and interface become more of a burden than a benefit. The availability of inexpensive sensor systems in products such as Microsoft Kinect™ or Nintendo Wii™ has resulted in new ways of interacting with computing systems, but new sensors alone are not enough. Developing useful and usable human-system interfaces requires understanding users and interaction in context: not just what new sensors afford in terms of interaction, but how users want to interact with these systems, for what purpose, and how sensors might enable those interactions. Additionally, the system needs to reliably make sense of the user's inputs in context, translate that interpretation into commands for the unmanned system, and give feedback to the user. In this paper, we describe an example natural interface for unmanned systems, called the Smart Interaction Device (SID), which enables natural two-way interaction with unmanned systems including the use of speech, sketch, and gestures. We present a few example applications SID to different types of unmanned systems and different kinds of interactions.

Effect of exopolymers on oxidative dissolution of natural rhodochrosite by Pseudomonas putida strain MnB1: An electrochemical study

International Nuclear Information System (INIS)

Wang, Huawei; Zhang, Daoyong; Song, Wenjuan; Pan, Xiangliang; Al-Misned, Fahad A.; Golam Mortuza, M.

2015-01-01

Highlights: • The biogeochemical behavior of natural rhodochrosite was investigated by electrochemical methods. • Bacterial exopolymers contributed to the increasing dissolution of natural rhodochrosite. • Oxidative dissolution of natural rhodochrosite was well explained by Tafel and EIS analysis. - Abstract: Oxidative dissolution of natural rhodochrosite by the Mn(II) oxidizing bacterium Pseudomonas putida strain MnB1 was investigated based on batch and electrochemical experiments using natural rhodochrosite as the working electrode. Tafel curves and batch experiments revealed that bacterial exopolymers (EPS) significantly increased dissolution of natural rhodochrosite. The corrosion current significantly increased with reaction time for EPS treatment. However, the corrosion process was blocked in the presence of cells plus extra EPS due to formation of the passivation layer. Moreover, the scanning electron microscopy and the energy dispersive spectroscopy (SEM–EDS) results showed that the surface of the natural rhodochrosite was notably changed in the presence of EPS alone or/and bacterial cells. This study is helpful for understanding the role of EPS in bacterially oxidation of Mn(II). It also indicates that the Mn(II) oxidizing bacteria may exert their effects on Mn(II) cycle and other biological and biogeochemical processes much beyond their local ambient environment because of the catalytically dissolution of solid Mn(II) by EPS and the possible long distance transport of the detached EPS

Defining Mediterranean and Black Sea biogeochemical subprovinces and synthetic ocean indicators using mesoscale oceanographic features

DEFF Research Database (Denmark)

Nieblas, Anne-Elise; Drushka, Kyla; Reygondeau, Gabriel

2014-01-01

variables to define integrative indices to monitor the environmental changes within each resultant subprovince at monthly resolutions. Using both the classical and mesoscale features, we find five biogeochemical subprovinces for the Mediterranean and Black Seas. Interestingly, the use of mesoscale variables......The Mediterranean and Black Seas are semi-enclosed basins characterized by high environmental variability and growing anthropogenic pressure. This has led to an increasing need for a bioregionalization of the oceanic environment at local and regional scales that can be used for managerial...... applications as a geographical reference. We aim to identify biogeochemical subprovinces within this domain, and develop synthetic indices of the key oceanographic dynamics of each subprovince to quantify baselines from which to assess variability and change. To do this, we compile a data set of 101 months...

Effects of Solar UV Radiation and Climate Change on Biogeochemical Cycling: Interactions and Feedbacks

Science.gov (United States)

Solar UV radiation, climate and other drivers of global change are undergoing significant changes and models forecast that these changes will continue for the remainder of this century. Here we assess the effects of solar UV radiation on biogeochemical cycles and the interactions...

Using coral Ba/Ca records to investigate seasonal to decadal scale biogeochemical cycling in the surface and intermediate ocean.

Science.gov (United States)

LaVigne, M.; Cobb, K. M.; DeLong, K. L.; Freiberger, M. M.; Grottoli, A. G.; Hill, T. M.; Miller, H. R.; Nurhati, I. S.; Richey, J. N.; Serrato Marks, G.; Sherrell, R. M.

2016-12-01

Dissolved barium (BaSW), a bio-intermediate element, is linked to several biogeochemical processes such as the cycling and export of nutrients, organic carbon (Corg), and barite in surface and intermediate oceans. Dynamic BaSW cycling has been demonstrated in the water column on short timescales (days-weeks) while sedimentary records have documented geologic-scale changes in barite preservation driven by export production. Our understanding of how seasonal-decadal scale climate variability impacts these biogeochemical processes currently lacks robust records. Ba/Ca calibrations in surface and deep sea corals suggest barium is incorporated via cationic substitution in both aragonite and calcite. Here we demonstrate the utility of Ba/Ca for reconstructing biogeochemical variability using examples of surface and deep sea coral records. Century-long deep sea coral records from the California Current System (bamboo corals: 900-1500m) record interannual variations in Ba/Ca, likely reflecting changes in barite formation via bacterial Corg respiration or barite saturation state. A surface Porites coral Ba/Ca record from Christmas Island (central equatorial Pacific: 1978-1995) shows maxima during low productivity El Niño warm periods, suggesting that variations in BaSW are driven by biological removal via direct cellular uptake or indirectly via barite precipitation with the decomposition of large phytoplankton blooms at this location. Similarly, a sixteen-year long Siderastera siderea surface coral record from Dry Tortugas, FL (Gulf of Mexico: 1991-2007) shows seasonal Ba/Ca cycles that align with annual chlorophyll and δ13C. Taken together, these records demonstrate the linkages among Corg, nutrient cycling and BaSW in the surface and intermediate ocean on seasonal to decadal timescales. Multi-proxy paleoceanographic reconstructions including Ba/Ca have the potential to elucidate the mechanisms linking past climate, productivity, nutrients, and BaSW cycling in the past.

Investigation of Artemisia tridentata as a biogeochemical uranium indicator

Energy Technology Data Exchange (ETDEWEB)

Diebold, F E; McGrath, S [Montana Coll. of Mineral Science and Technology, Butte (USA)

1985-01-01

Hydroponic experiments were conducted with seedlings of Artemisia tridentata subsp. tridentata (big sagebrush) to test the effect of the phosphate speciation of uranium in solution on its uptake by big sagebrush. No single complex could be identified as being preferentially taken up by the plant, but the varying aqueous phosphate concentrations did affect uranium uptake by the plants at the higher uranium concentrations in solution. The data also substantiate the tendency for uranium to behave as an essential element in this plant species. The implications for the use of Artemisia tridentata as a biogeochemical uranium indicator are discussed.

Short-term effects of salinity reduction and drainage on salt-marsh biogeochemical cycling and Spartina (Cordgrass) production

Science.gov (United States)

Portnoy, J.W.; Valiela, I.

1997-01-01

To assess the biogeochemical effects of tidal restrictions on salt-marsh sulfur cycling and plant growth, cores of short-form Spartina alterniflora peat were desalinated and kept either waterlogged or drained in greenhouse microcosms. Changes in net Spartina production, and porewater and solid phase chemistry of treated cores were compared to natural conditions in the field collection site over a 21-mo period. Net production among treatments increased significantly in drained and waterlogged peat compared to field conditions during the first growing season. Constantly high sulfide in waterlogged cores accompanied reduced plant growth. Aeration invigorated growth in drained cores but led to oxidization of sulfide minerals and to lowered pH. During the second growing season, growth declined in the drained treatment, probably because of acidification and decreased dissolved inorganic nitrogen. Results are pertinent to the success of current wetland protection and restoration activities in the coastal zone.

The roles of resuspension, diffusion and biogeochemical processes on oxygen dynamics offshore of the Rhône River, France: a numerical modeling study

Science.gov (United States)

Moriarty, Julia M.; Harris, Courtney K.; Fennel, Katja; Friedrichs, Marjorie A. M.; Xu, Kehui; Rabouille, Christophe

2017-04-01

Observations indicate that resuspension and associated fluxes of organic material and porewater between the seabed and overlying water can alter biogeochemical dynamics in some environments, but measuring the role of sediment processes on oxygen and nutrient dynamics is challenging. A modeling approach offers a means of quantifying these fluxes for a range of conditions, but models have typically relied on simplifying assumptions regarding seabed-water-column interactions. Thus, to evaluate the role of resuspension on biogeochemical dynamics, we developed a coupled hydrodynamic, sediment transport, and biogeochemical model (HydroBioSed) within the Regional Ocean Modeling System (ROMS). This coupled model accounts for processes including the storage of particulate organic matter (POM) and dissolved nutrients within the seabed; fluxes of this material between the seabed and the water column via erosion, deposition, and diffusion at the sediment-water interface; and biogeochemical reactions within the seabed. A one-dimensional version of HydroBioSed was then implemented for the Rhône subaqueous delta in France. To isolate the role of resuspension on biogeochemical dynamics, this model implementation was run for a 2-month period that included three resuspension events; also, the supply of organic matter, oxygen, and nutrients to the model was held constant in time. Consistent with time series observations from the Rhône Delta, model results showed that erosion increased the diffusive flux of oxygen into the seabed by increasing the vertical gradient of oxygen at the seabed-water interface. This enhanced supply of oxygen to the seabed, as well as resuspension-induced increases in ammonium availability in surficial sediments, allowed seabed oxygen consumption to increase via nitrification. This increase in nitrification compensated for the decrease in seabed oxygen consumption due to aerobic remineralization that occurred as organic matter was entrained into the water

Arabic Natural Language Processing System Code Library

Science.gov (United States)

2014-06-01

Adelphi, MD 20783-1197 This technical note provides a brief description of a Java library for Arabic natural language processing ( NLP ) containing code...for training and applying the Arabic NLP system described in the paper "A Cross-Task Flexible Transition Model for Arabic Tokenization, Affix...and also English) natural language processing ( NLP ), containing code for training and applying the Arabic NLP system described in Stephen Tratz’s

Biogeochemical behaviour of anionic radionuclides in soil: evidence for biotic interactions

International Nuclear Information System (INIS)

Fevrier, L.; Martin-Garin, A.

2004-01-01

Among studies on radionuclides, very few have been devoted to the behaviour of long-lived anionic radionuclides as 99 Tc and 79 Se in soils. Yet these two species are supposed to be highly mobile in soils, because of their anionic forms. The understanding of their biogeochemical behaviour in soils will improve both the ecological and health risk assessment. Very often the interactions between the radionuclides and the different components of soil are considered only from a physico-chemical point of view. However in surface horizons and more specially in the rhizosphere, the micro-organisms can not be ignored as they can affect either directly or indirectly the speciation of most of the chemical species, and particularly these of Se and Tc. This study demonstrates the role of the microbial compartment in the retention of Se and Tc in soil by comparing experiments with a sterilized soil (no microbial activity) to experiments with a soil more or less amended with organic carbon and / or nitrate, to stimulate its microbial activity. Kd coefficients for Se and Tc were determined in batch experiments, whereas transport of Se and Tc was investigated through column leaching experiments. Kd for Se was enhanced for the natural soil without amendment compared to the value obtained for the sterilized soil. The retention of Se was higher again in the natural soil amended with glucose and nitrate together. In addition, these amendments facilitated the development of a biofilm at the entrance of the column, which can directly retain Se. This effect was less obvious for Tc in batch experiments, but was revealed by leaching experiments where a high quantity of Tc was retained in the soil column when added with glucose and nitrate. These results give evidence that micro-organisms are responsible for a greater retention of Se and Tc in soil. (author)

Iron chemistry of Hawaiian rainforest soil solution: Biogeochemical implications of multiple Fe redox cycles

Science.gov (United States)

Thompson, A.; Chorover, J.; Chadwick, O.

2003-12-01

Iron (Fe)-oxides are important sorbents for nutrients, pollutants and natural organic matter (NOM). When flucutations in soil oxygen status exist, Fe can cycle through reduced and oxidized forms and thus greatly affect the aqueous conc. of nutrients and metals. We are examining the influence of oscillating oxic/anoxic conditions on Fe-oxide formation and biogeochemical processes (microbial community composition, and carbon, nutrient and trace metal availability). Our work makes use of a natural rainfall gradient ranging from 2.2 to 4.2 m mean annual precipitation (MAP) on the island of Maui, Hawaii, USA. All sites developed on a 400ky basaltic lava flow and comprise soils under similar vegetation. Solid phase Fe concentration and oxidation state vary systematically across this rainfall gradient with a sharp decrease in pedogenic Fe between 2.8 m and 3.5 m MAP that corresponds with an Eh of 330 mV (1-yr ave.). Fe isotopic composition and Fe-oxide associated rare earth elements (REE) also suggest a shift from ligand-promoted to redutive Fe dissolution with increasing rainfall. To examine the effects of multiple Fe oxidation/reduction cycles, we constructed a set of redox-stat reactors that maintain Eh values within a set range by small Eh-triggered additions of oxygen. Triplicate soil slurry reactors are subjected to redox (Eh) oscillations such that Fe is repeatedly cycled from oxidized to reduced forms. During our current experiment, we measure pH and Eh dynamics and monitor the distribution of Fe(II) and Fe(III), major ion and anion concentrations, a range of trace metals including the REE, and total organic carbon (TOC) in three Stokes-effective particle size fractions (DNA fingerprinting is used to track changes in the microbial community. Prior to implementing the rigorous sampling procedure above, we completed two preliminary reactor experiments focusing only on Fe distribution between aqueous, HCl, and oxalate extractions. These experiments illustrated (1) a

CO2 leakage alters biogeochemical and ecological functions of submarine sands

Science.gov (United States)

Molari, Massimiliano; Guilini, Katja; Lott, Christian; Weber, Miriam; de Beer, Dirk; Meyer, Stefanie; Ramette, Alban; Wegener, Gunter; Wenzhöfer, Frank; Martin, Daniel; Cibic, Tamara; De Vittor, Cinzia; Vanreusel, Ann; Boetius, Antje

2018-01-01

Subseabed CO2 storage is considered a future climate change mitigation technology. We investigated the ecological consequences of CO2 leakage for a marine benthic ecosystem. For the first time with a multidisciplinary integrated study, we tested hypotheses derived from a meta-analysis of previous experimental and in situ high-CO2 impact studies. For this, we compared ecological functions of naturally CO2-vented seafloor off the Mediterranean island Panarea (Tyrrhenian Sea, Italy) to those of nonvented sands, with a focus on biogeochemical processes and microbial and faunal community composition. High CO2 fluxes (up to 4 to 7 mol CO2 m−2 hour−1) dissolved all sedimentary carbonate, and comigration of silicate and iron led to local increases of microphytobenthos productivity (+450%) and standing stocks (+300%). Despite the higher food availability, faunal biomass (−80%) and trophic diversity were substantially lower compared to those at the reference site. Bacterial communities were also structurally and functionally affected, most notably in the composition of heterotrophs and microbial sulfate reduction rates (−90%). The observed ecological effects of CO2 leakage on submarine sands were reproduced with medium-term transplant experiments. This study assesses indicators of environmental impact by CO2 leakage and finds that community compositions and important ecological functions are permanently altered under high CO2. PMID:29441359

Connections between physical, optical and biogeochemical processes in the Pacific Ocean

Science.gov (United States)

Xiu, Peng; Chai, Fei

2014-03-01

A new biogeochemical model has been developed and coupled to a three-dimensional physical model in the Pacific Ocean. With the explicitly represented dissolved organic pools, this new model is able to link key biogeochemical processes with optical processes. Model validation against satellite and in situ data indicates the model is robust in reproducing general biogeochemical and optical features. Colored dissolved organic matter (CDOM) has been suggested to play an important role in regulating underwater light field. With the coupled model, physical and biological regulations of CDOM in the euphotic zone are analyzed. Model results indicate seasonal variability of CDOM is mostly determined by biological processes, while the importance of physical regulation manifests in the annual mean terms. Without CDOM attenuating light, modeled depth-integrated primary production is about 10% higher than the control run when averaged over the entire basin, while this discrepancy is highly variable in space with magnitudes reaching higher than 100% in some locations. With CDOM dynamics integrated in physical-biological interactions, a new mechanism by which physical processes affect biological processes is suggested, namely, physical transport of CDOM changes water optical properties, which can further modify underwater light field and subsequently affect the distribution of phytoplankton chlorophyll. This mechanism tends to occur in the entire Pacific basin but with strong spatial variability, implying the importance of including optical processes in the coupled physical-biogeochemical model. If ammonium uptake is sufficient to permit utilization of DOM, that is, UB∗⩾-U{U}/{U}-{(1-r_b)}/{RB}, then bacteria uptake of DOM has the form of FB=(1-r_b){U}/{RB}, bacteria respiration, SB=r_b×U, remineralization by bacteria, EB=UC{UN}/{UC}-{(1-r_b)}/{RB}. If EB > 0, then UB = 0; otherwise, UB = -EB. If there is insufficient ammonium, that is, UB∗CO2 is calculated using the

Searching for Biogeochemical Cycles on Mars

Science.gov (United States)

DesMarais, David J.

1997-01-01

The search for life on Mars clearly benefits from a rigorous, yet broad, definition of life that compels us to consider all possible lines of evidence for a martian biosphere. Recent studies in microbial ecology illustrate that the classic definition of life should be expanded beyond the traditional definition of a living cell. The traditional defining characteristics of life are threefold. First, life is capable of metabolism, that is, it performs chemical reactions that utilize energy and also synthesize its cellular constituents. Second, life is capable of self-replication. Third, life can evolve in order to adapt to environmental changes. An expanded, ecological definition of life also recognizes that life is a community of organisms that must interact with their nonliving environment through processes called biogeochemical cycles. This regenerative processing maintains, in an aqueous conditions, a dependable supply of nutrients and energy for growth. In turn, life can significantly affect those processes that control the exchange of materials between the atmosphere, ocean, and upper crust. Because metabolic processes interact directly with the environment, they can alter their surroundings and thus leave behind evidence of life. For example, organic matter is produced from single-carbon-atom precursors for the biosynthesis of cellular constituents. This leads to a reservoir of reduced carbon in sediments that, in turn, can affect the oxidation state of the atmosphere. The harvesting of chemical energy for metabolism often employs oxidation-reduction reactions that can alter the chemistry and oxidation state of the redox-sensitive elements carbon, sulfur, nitrogen, iron, and manganese. Have there ever been biogeochemical cycles on Mars? Certain key planetary processes can offer clues. Active volcanism provides reduced chemical species that biota can use for organic synthesis. Volcanic carbon dioxide and methane can serve as greenhouse gases. Thus the

Biogeochemical cycling in terrestrial ecosystems of the Caatinga Biome.

Science.gov (United States)

Menezes, R S C; Sampaio, E V S B; Giongo, V; Pérez-Marin, A M

2012-08-01

The biogeochemical cycles of C, N, P and water, the impacts of land use in the stocks and flows of these elements and how they can affect the structure and functioning of Caatinga were reviewed. About half of this biome is still covered by native secondary vegetation. Soils are deficient in nutrients, especially N and P. Average concentrations of total soil P and C in the top layer (0-20 cm) are 196 mg kg(-1) and 9.3 g kg(-1), corresponding to C stocks around 23 Mg ha(-1). Aboveground biomass of native vegetation varies from 30 to 50 Mg ha(-1), and average root biomass from 3 to 12 Mg ha(-1). Average annual productivities and biomass accumulation in different land use systems vary from 1 to 7 Mg ha(-1) year(-1). Biological atmospheric N2 fixation is estimated to vary from 3 to 11 kg N ha(-1) year-1 and 21 to 26 kg N ha(-1) year(-1) in mature and secondary Caatinga, respectively. The main processes responsible for nutrient and water losses are fire, soil erosion, runoff and harvest of crops and animal products. Projected climate changes in the future point to higher temperatures and rainfall decreases. In face of the high intrinsic variability, actions to increase sustainability should improve resilience and stability of the ecosystems. Land use systems based on perennial species, as opposed to annual species, may be more stable and resilient, thus more adequate to face future potential increases in climate variability. Long-term studies to investigate the potential of the native biodiversity or adapted exotic species to design sustainable land use systems should be encouraged.

Modelling benthic biophysical drivers of ecosystem structure and biogeochemical response

Science.gov (United States)

Stephens, Nicholas; Bruggeman, Jorn; Lessin, Gennadi; Allen, Icarus

2016-04-01

The fate of carbon deposited at the sea floor is ultimately decided by biophysical drivers that control the efficiency of remineralisation and timescale of carbon burial in sediments. Specifically, these drivers include bioturbation through ingestion and movement, burrow-flushing and sediment reworking, which enhance vertical particulate transport and solute diffusion. Unfortunately, these processes are rarely satisfactorily resolved in models. To address this, a benthic model that explicitly describes the vertical position of biology (e.g., habitats) and biogeochemical processes is presented that includes biological functionality and biogeochemical response capturing changes in ecosystem structure, benthic-pelagic fluxes and biodiversity on inter-annual timescales. This is demonstrated by the model's ability to reproduce temporal variability in benthic infauna, vertical pore water nutrients and pelagic-benthic solute fluxes compared to in-situ data. A key advance is the replacement of bulk parameterisation of bioturbation by explicit description of the bio-physical processes responsible. This permits direct comparison with observations and determination of key parameters in experiments. Crucially, the model resolves the two-way interaction between sediment biogeochemistry and ecology, allowing exploration of the benthic response to changing environmental conditions, the importance of infaunal functional traits in shaping benthic ecological structure and the feedback the resulting bio-physical processes exert on pore water nutrient profiles. The model is actively being used to understand shelf sea carbon cycling, the response of the benthos to climatic change, food provision and other societal benefits.

Using NEON Data to Test and Refine Conceptual and Numerical Models of Soil Biogeochemical and Microbial Dynamics

Science.gov (United States)

Weintraub, S. R.; Stanish, L.; Ayers, E.

2017-12-01

Recent conceptual and numerical models have proposed new mechanisms that underpin key biogeochemical phenomena, including soil organic matter storage and ecosystem response to nitrogen deposition. These models seek to explicitly capture the ecological links among biota, especially microbes, and their physical and chemical environment to represent belowground pools and fluxes and how they respond to perturbation. While these models put forth exciting new concepts, their broad predictive abilities are unclear as some have been developed and tested against only small or regional datasets. The National Ecological Observatory Network (NEON) presents new opportunities to test and validate these models with multi-site data that span wide climatic, edaphic, and ecological gradients. NEON is measuring surface soil biogeochemical pools and fluxes along with diversity, abundance, and functional potential of soil microbiota at 47 sites distributed across the United States. This includes co-located measurements of soil carbon and nitrogen concentrations and stable isotopes, net nitrogen mineralization and nitrification rates, soil moisture, pH, microbial biomass, and community composition via 16S and ITS rRNA sequencing and shotgun metagenomic analyses. Early NEON data demonstrates that these wide edaphic and climatic gradients are related to changes in microbial community structure and functional potential, as well as element pools and process rates. Going forward, NEON's suite of standardized soil data has the potential to advance our understanding of soil communities and processes by allowing us to test the predictions of new soil biogeochemical frameworks and models. Here, we highlight several recently developed models that are ripe for this kind of data validation, and discuss key insights that may result. Further, we explore synergies with other networks, such as (i)LTER and (i)CZO, which may increase our ability to advance the frontiers of soil biogeochemical modeling.

Investigation of In-situ Biogeochemical Reduction of Chlorinated Solvents in Groundwater by Reduced Iron Minerals

Science.gov (United States)

Biogeochemical transformation is a process in which chlorinated solvents are degraded abiotically by reactive minerals formed by, at least in part or indirectly from, anaerobic biological processes. Five mulch biowall and/or vegetable oil-based bioremediation applications for tr...

Design guidelines for natural ventilation systems in tertiary sector buildings

OpenAIRE

Van Moeseke, Geoffrey; Bruyère, Isabelle; De Herde, André; CISBAT 2005: Renewables in a changing climate

2005-01-01

Parameters determining efficiency of natural ventilation systems are numerous. The most important are architecture and system design. This article get onto both but focuses on system design. Through dynamic simulations it shows that natural ventilation management has a large impact on energy saving but most of all on thermal comfort. Natural ventilation techniques are also weighted against hybrid solutions and high efficiency mechanical cooling solutions. Natural ventilation techniques show t...

The transport system for natural gas

International Nuclear Information System (INIS)

Bjoerndalen, Joergen; Nese, Gjermund

2003-01-01

In 2002, the actors on the Norwegian shelf in cooperation with the authorities established a new regime for sale and transport of gas. This article deals with some issues of interest relating to this new regime. The transport system for natural gas shows clear signs of being a natural monopoly, which makes it difficult to use the system efficiently. Two main problems of the current way of organizing are pointed out: (1) lack of price and market signals in capacity allocation and (2) unclear incentive effects. The article indicates a possible solution based on the form of organization that is used in the power market

Hydrogeological and biogeochemical constrains of arsenic mobilization in shallow aquifers from the Hetao basin, Inner Mongolia

International Nuclear Information System (INIS)

Guo Huaming; Zhang Bo; Li Yuan; Berner, Zsolt; Tang Xiaohui; Norra, Stefan; Stueben, Doris

2011-01-01

Little is known about the importance of drainage/irrigation channels and biogeochemical processes in arsenic distribution of shallow groundwaters from the Hetao basin. This investigation shows that although As concentrations are primarily dependent on reducing conditions, evaporation increases As concentration in the centre of palaeo-lake sedimentation. Near drainage channels, groundwater As concentrations are the lowest in suboxic-weakly reducing conditions. Results demonstrate that both drainage and irrigation channels produce oxygen-rich water that recharges shallow groundwaters and therefore immobilize As. Groundwater As concentration increases with a progressive decrease in redox potential along the flow path in an alluvial fan. A negative correlation between SO 4 2- concentrations and δ 34 S values indicates that bacterial reduction of SO 4 2- occurs in reducing aquifers. Due to high concentrations of Fe (>0.5 mg L -1 ), reductive dissolution of Fe oxides is believed to cause As release from aquifer sediments. Target aquifers for safe drinking water resources are available in alluvial fans and near irrigation channels. - Research highlights: → Low As groundwaters occur in alluvial fans. → We find low As groundwaters near irrigation and drainage channels. → Both hydrogeologic conditions and biogeochemical processes control As distribution. - Both hydrogeologic conditions and biogeochemical processes control As distribution of shallow groundwaters, which results in the occurrence of low As groundwater in alluvial fans and near irrigation channels and drainage channels.

Task planning systems with natural language interface

International Nuclear Information System (INIS)

Kambayashi, Shaw; Uenaka, Junji

1989-12-01

In this report, a natural language analyzer and two different task planning systems are described. In 1988, we have introduced a Japanese language analyzer named CS-PARSER for the input interface of the task planning system in the Human Acts Simulation Program (HASP). For the purpose of a high speed analysis, we have modified a dictionary system of the CS-PARSER by using C language description. It is found that the new dictionary system is very useful for a high speed analysis and an efficient maintenance of the dictionary. For the study of the task planning problem, we have modified a story generating system named Micro TALE-SPIN to generate a story written in Japanese sentences. We have also constructed a planning system with natural language interface by using the CS-PARSER. Task planning processes and related knowledge bases of these systems are explained. A concept design for a new task planning system will be also discussed from evaluations of above mentioned systems. (author)

Dynamics of soil biogeochemical gas emissions shaped by remolded aggregate sizes and carbon configurations under hydration cycles.

Science.gov (United States)

Ebrahimi, Ali; Or, Dani

2018-01-01

Changes in soil hydration status affect microbial community dynamics and shape key biogeochemical processes. Evidence suggests that local anoxic conditions may persist and support anaerobic microbial activity in soil aggregates (or in similar hot spots) long after the bulk soil becomes aerated. To facilitate systematic studies of interactions among environmental factors with biogeochemical emissions of CO 2 , N 2 O and CH 4 from soil aggregates, we remolded silt soil aggregates to different sizes and incorporated carbon at different configurations (core, mixed, no addition). Assemblies of remolded soil aggregates of three sizes (18, 12, and 6 mm) and equal volumetric proportions were embedded in sand columns at four distinct layers. The water table level in each column varied periodically while obtaining measurements of soil GHG emissions for the different aggregate carbon configurations. Experimental results illustrate that methane production required prolonged inundation and highly anoxic conditions for inducing measurable fluxes. The onset of unsaturated conditions (lowering water table) resulted in a decrease in CH 4 emissions while temporarily increasing N 2 O fluxes. Interestingly, N 2 O fluxes were about 80% higher form aggregates with carbon placement in center (anoxic) core compared to mixed carbon within aggregates. The fluxes of CO 2 were comparable for both scenarios of carbon sources. These experimental results highlight the importance of hydration dynamics in activating different GHG production and affecting various transport mechanisms about 80% of total methane emissions during lowering water table level are attributed to physical storage (rather than production), whereas CO 2 emissions (~80%) are attributed to biological activity. A biophysical model for microbial activity within soil aggregates and profiles provides a means for results interpretation and prediction of trends within natural soils under a wide range of conditions. © 2017 John

Reactive transport modelling of biogeochemical processes and carbon isotope geochemistry inside a landfill leachate plume.

NARCIS (Netherlands)

van Breukelen, B.M.; Griffioen, J.; Roling, W.F.M.; van Verseveld, H.W.

2004-01-01

The biogeochemical processes governing leachate attenuation inside a landfill leachate plume (Banisveld, the Netherlands) were revealed and quantified using the 1D reactive transport model PHREEQC-2. Biodegradation of dissolved organic carbon (DOC) was simulated assuming first-order oxidation of two

Treatment of heavy metals by iron oxide coated and natural gravel media in Sustainable urban Drainage Systems.

Science.gov (United States)

Norris, M J; Pulford, I D; Haynes, H; Dorea, C C; Phoenix, V R

2013-01-01

Sustainable urban Drainage Systems (SuDS) filter drains are simple, low-cost systems utilized as a first defence to treat road runoff by employing biogeochemical processes to reduce pollutants. However, the mechanisms involved in pollution attenuation are poorly understood. This work aims to develop a better understanding of these mechanisms to facilitate improved SuDS design. Since heavy metals are a large fraction of pollution in road runoff, this study aimed to enhance heavy metal removal of filter drain gravel with an iron oxide mineral amendment to increase surface area for heavy metal scavenging. Experiments showed that amendment-coated and uncoated (control) gravel removed similar quantities of heavy metals. Moreover, when normalized to surface area, iron oxide coated gravels (IOCGs) showed poorer metal removal capacities than uncoated gravel. Inspection of the uncoated microgabbro gravel indicated that clay particulates on the surface (a natural product of weathering of this material) augmented heavy metal removal, generating metal sequestration capacities that were competitive compared with IOCGs. Furthermore, when the weathered surface was scrubbed and removed, metal removal capacities were reduced by 20%. When compared with other lithologies, adsorption of heavy metals by microgabbro was 10-70% higher, indicating that both the lithology of the gravel, and the presence of a weathered surface, considerably influence its ability to immobilize heavy metals. These results contradict previous assumptions which suggest that gravel lithology is not a significant factor in SuDS design. Based upon these results, weathered microgabbro is suggested to be an ideal lithology for use in SuDS.

Structural equation modeling and natural systems

Science.gov (United States)

Grace, James B.

2006-01-01

This book, first published in 2006, presents an introduction to the methodology of structural equation modeling, illustrates its use, and goes on to argue that it has revolutionary implications for the study of natural systems. A major theme of this book is that we have, up to this point, attempted to study systems primarily using methods (such as the univariate model) that were designed only for considering individual processes. Understanding systems requires the capacity to examine simultaneous influences and responses. Structural equation modeling (SEM) has such capabilities. It also possesses many other traits that add strength to its utility as a means of making scientific progress. In light of the capabilities of SEM, it can be argued that much of ecological theory is currently locked in an immature state that impairs its relevance. It is further argued that the principles of SEM are capable of leading to the development and evaluation of multivariate theories of the sort vitally needed for the conservation of natural systems.

A model integrating social-cultural concepts of nature into frameworks of interaction between social and natural systems

DEFF Research Database (Denmark)

Muhar, Andreas; Raymond, Christopher M.; van den Born, Riyan J.G.

2018-01-01

relationship at both individual and collective levels. We highlight the relevance of individual and collective understandings of the human-nature relationship as influencing factors for environmental behaviour, which may be reflected in natural resource management conflicts, and review the diversity......Existing frameworks for analysing interactions between social and natural systems (e.g. Social-Ecological Systems framework, Ecosystem Services concept) do not sufficiently consider and operationalize the dynamic interactions between people's values, attitudes and understandings of the human-nature....... Integrating this model into existing frameworks provides a tool for the exploration of how social-cultural concepts of nature interact with existing contexts to influence governance of social-ecological systems....

Natural and human-induced hypoxia and consequences for coastal areas: synthesis and future development

Science.gov (United States)

Zhang, J.; Gilbert, D.; Gooday, A.; Levin, L.; Naqvi, W.; Middelburg, J.; Scranton, M.; Ekau, W.; Pena, A.; Dewitte, B.; Oguz, T.; Monteiro, P. M. S.; Urban, E.; Rabalais, N.; Ittekkot, V.; Kemp, W. M.; Ulloa, O.; Elmgren, R.; Escobar-Briones, E.; van der Plas, A.

2009-11-01

Hypoxia has become a world-wide phenomenon in the global coastal ocean and causes deterioration of structure and function of ecosystems. Based on the collective contributions of members of SCOR Working Group #128, the present study provides an overview of the major aspects of coastal hypoxia in different biogeochemical provinces, including estuaries, upwelling areas, fjords and semi-enclosed basins, with various external forcings, ecosystem responses, feedbacks and potential impact on the sustainability of the fishery and economics. The obvious external forcings include fresh water runoff and other factors contributing to stratification, organic matter and nutrient loadings, as well as exchange between coastal and open ocean water masses; their different interactions set up mechanisms that drive the system towards hypoxia. However, whether the coastal environment becomes hypoxic or not, under the combination of external forcings, depends also on the nature of the ecosystem, e.g. physical and geographic settings. It is understood that coastal hypoxia has a profound impact on the sustainability of ecosystems, which can be seen, for example, by the change in the food-web structure and system function; other influences can be compression and loss of habitat, as well as change in life cycle and reproduction. In most cases, the ecosystem responds to the low dissolved oxygen in a non-linear way and has pronounced feedbacks to other compartments of the Earth System, hence affecting human society. Our knowledge and previous experiences illustrate that there is a need to develop new observational tools and models to support integrated research of biogeochemical dynamics and ecosystem behaviour that will improve confidence in remediation management strategies for coastal hypoxia.

Knowledge Systems and Natural Resources: Management, Policy ...

International Development Research Centre (IDRC) Digital Library (Canada)

2007-10-31

Oct 31, 2007 ... Knowledge Systems and Natural Resources is a unique collection of case studies from Nepal. ... and students of social and political sciences and natural resource management. ... Nepal and founding Editor of the Journal of Forest and Livelihood. ... Ideas from the global climate change hotspot research.

Assessing the Performance of Natural Resource Systems

Directory of Open Access Journals (Sweden)

Bruce Campbell

2002-01-01

Full Text Available Assessing the performance of management is central to natural resource management, in terms of improving the efficiency of interventions in an adaptive-learning cycle. This is not simple, given that such systems generally have multiple scales of interaction and response; high frequency of nonlinearity, uncertainty, and time lags; multiple stakeholders with contrasting objectives; and a high degree of context specificity. The importance of bounding the problem and preparing a conceptual model of the system is highlighted. We suggest that the capital assets approach to livelihoods may be an appropriate organizing principle for the selection of indicators of system performance. In this approach, five capital assets are recognized: physical, financial, social, natural, and human. A number of principles can be derived for each capital asset; indicators for assessing system performance should cover all of the principles. To cater for multiple stakeholders, participatory selection of indicators is appropriate, although when cross-site comparability is required, some generic indicators are suitable. Because of the high degree of context specificity of natural resource management systems, a typology of landscapes or resource management domains may be useful to allow extrapolation to broader systems. The problems of nonlinearities, uncertainty, and time lags in natural resource management systems suggest that systems modeling is crucial for performance assessment, in terms of deriving "what would have happened anyway" scenarios for comparison to the measured trajectory of systems. Given that a number of indicators are necessary for assessing performance, the question becomes whether these can be combined to give an integrative assessment. We explore five possible approaches: (1 simple additive index, as used for the Human Development Index; (2 derived variables (e.g., principal components as the indices of performance; (3 two-dimensional plots of

Numerical modeling of underground storage system for natural gas

Science.gov (United States)

Ding, J.; Wang, S.

2017-12-01

Natural gas is an important type of base-load energy, and its supply needs to be adjusted according to different demands in different seasons. For example, since natural gas is increasingly used to replace coal for winter heating, the demand for natural gas in winter is much higher than that in other seasons. As storage systems are the essential tools for balancing seasonal supply and demand, the design and simulation of natural gas storage systems form an important research direction. In this study, a large-scale underground storage system for natural gas is simulated based on theoretical analysis and finite element modeling.It is proven that the problem of axi-symmetric Darcy porous flow of ideal gas is governed by the Boussinesq equation. In terms of the exact solution to the Boussinesq equation, the basic operating characteristics of the underground storage system is analyzed, and it is demonstrated that the propagation distance of the pore pressure is proportional to the 1/4 power of the mass flow rate and to the 1/2 power of the propagation time. This quantitative relationship can be used to guide the overall design of natural gas underground storage systems.In order to fully capture the two-way coupling between pore pressure and elastic matrix deformation, a poro-elastic finite element model for natural gas storage is developed. Based on the numerical model, the dynamic processes of gas injection, storage and extraction are simulated, and the corresponding time-dependent surface deformations are obtained. The modeling results not only provide a theoretical basis for real-time monitoring for the operating status of the underground storage system through surface deformation measurements, but also demonstrate that a year-round balance can be achieved through periodic gas injection and extraction.This work is supported by the CAS "100 talents" Program and the National Natural Science Foundation of China (41371090).

Biogeochemical features technogenic pollution of soils under the influence chemical industry

Directory of Open Access Journals (Sweden)

Kuraeva I.V.

2015-09-01

Full Text Available The physico-chemical properties of soil (pH, organic matter content, cation exchange capacity. The regularities of the distribution of total and mobile forms of heavy metals in soil sediments in the territory of Shostka Sumy region under the influence of the chemical industry and in the background areas. Biogeochemical indicators obtained content of microscopic fungi and their species, the most characteristic of the study of soils, which can be used as an additional criterion for ecological and geochemical studies.

East Siberian Sea, an Arctic region of very high biogeochemical activity

Directory of Open Access Journals (Sweden)

L. G. Anderson

2011-06-01

Full Text Available Shelf seas are among the most active biogeochemical marine environments and the East Siberian Sea is a prime example. This sea is supplied by seawater from both the Atlantic and Pacific Oceans and has a substantial input of river runoff. All of these waters contribute chemical constituents, dissolved and particulate, but of different signatures. Sea ice formation during the winter season and melting in the summer has a major impact on physical as well as biogeochemical conditions. The internal circulation and water mass distribution is significantly influenced by the atmospheric pressure field. The western region is dominated by input of river runoff from the Laptev Sea and an extensive input of terrestrial organic matter. The microbial decay of this organic matter produces carbon dioxide (CO₂ that oversaturates all waters from the surface to bottom relative to atmospheric level, even when primary production, inferred from low surface water nutrients, has occurred. The eastern surface waters were under-saturated with respect to CO₂ illustrating the dominance of marine primary production. The drawdown of dissolved inorganic carbon equals a primary production of ~0.8 ± 2 mol C m⁻², which when multiplied by half the area of the East Siberian Sea, ~500 000 km², results in an annual primary production of 0.4 (± 1 × 10¹² mol C or ~4 (± 10 × 10¹² gC. Microbial decay occurs through much of the water column, but dominates at the sediment interface where the majority of organic matter ends up, thus more of the decay products are recycled to the bottom water. High nutrient concentrations and fugacity of CO₂ and low oxygen and pH were observed in the bottom waters. Another signature of organic matter decomposition, methane (CH₄, was observed in very high but variable concentrations. This is due to its seabed sources of glacial origin or modern production from

Temporal dynamics of biogeochemical processes at the Norman Landfill site

Science.gov (United States)

Arora, Bhavna; Mohanty, Binayak P.; McGuire, Jennifer T.; Cozzarelli, Isabelle M.

2013-01-01

The temporal variability observed in redox sensitive species in groundwater can be attributed to coupled hydrological, geochemical, and microbial processes. These controlling processes are typically nonstationary, and distributed across various time scales. Therefore, the purpose of this study is to investigate biogeochemical data sets from a municipal landfill site to identify the dominant modes of variation and determine the physical controls that become significant at different time scales. Data on hydraulic head, specific conductance, δ2H, chloride, sulfate, nitrate, and nonvolatile dissolved organic carbon were collected between 1998 and 2000 at three wells at the Norman Landfill site in Norman, OK. Wavelet analysis on this geochemical data set indicates that variations in concentrations of reactive and conservative solutes are strongly coupled to hydrologic variability (water table elevation and precipitation) at 8 month scales, and to individual eco-hydrogeologic framework (such as seasonality of vegetation, surface-groundwater dynamics) at 16 month scales. Apart from hydrologic variations, temporal variability in sulfate concentrations can be associated with different sources (FeS cycling, recharge events) and sinks (uptake by vegetation) depending on the well location and proximity to the leachate plume. Results suggest that nitrate concentrations show multiscale behavior across temporal scales for different well locations, and dominant variability in dissolved organic carbon for a closed municipal landfill can be larger than 2 years due to its decomposition and changing content. A conceptual framework that explains the variability in chemical concentrations at different time scales as a function of hydrologic processes, site-specific interactions, and/or coupled biogeochemical effects is also presented.

In Situ Biogeochemical Treatment Demonstration: Lessons Learned from ESTCP Project ER 201124

Science.gov (United States)

2015-12-09

native soil from the site amended with iron oxides at 3% concentration, electron donors, and sulfate (1,000 mg/L) to simulate an injection strategy...for biogeochemical transformation. Reactor # 2 (Abiotic Mulch) contained sand, mulch, vegetable oil (1%), iron oxides (3%), and sulfate (to simulate ...vegetable oil fermentation to volatile fatty acids (VFA) also likely reduced the pH and this change could have reduced the FeS reactivity. 2.3.5

The influence of tides on biogeochemical dynamics at the mouth of the Amazon River

Science.gov (United States)

Ward, N. D.; Sawakuchi, H. O.; Neu, V.; de Matos Valerio, A.; Less, D.; Guedes, V.; Wood, J.; Brito, D. C.; Cunha, A. C.; Kampel, M.; Richey, J. E.

2017-12-01

A major barrier to computing the flux of constituents from the world's largest rivers to the ocean is understanding the dynamic processes that occur along tidally-influenced river reaches. Here, we examine the response of a suite of biogeochemical parameters to tide-induced flow reversals at the mouth of the Amazon River. Continuous measurements of pCO2, pCH4, dissolved O2, pH, turbidity, and fluorescent dissolved organic matter (FDOM) were made throughout tidal cycles while held stationary in the center of the river and during hourly transects for ADCP discharge measurements. Samples were collected hourly from the surface and 50% depth during stationary samplings and from the surface during ADCP transects for analysis of suspended sediment concentrations along with other parameters such as nutrient and mercury concentrations. Suspended sediment and specific components of the suspended phase, such as particulate mercury, concentrations were positively correlated to mean river velocity during both high and low water periods with a more pronounced response at 50% depth than the surface. Tidal variations also influenced the concentration of O2 and CO2 by altering the dynamic balance between photosynthesis, respiration, and gas transfer. CO2 was positively correlated and O2 and pH were negatively correlated with river velocity. The concentration of methane generally increased during low tide (i.e. when river water level was lowest) both in the mainstem and in small side channels. In side channels concentrations increased by several orders of magnitude during low tide with visible bubbling from the sediment, presumably due to a release of hydrostatic pressure. These results suggest that biogeochemical processes are highly dynamic in tidal rivers, and these dynamic variations need to be quantified to better constrain global and regional scale budgets. Understanding these rapid processes may also provide insight into the long-term response of aquatic systems to change.

Neotropical peatland methane emissions along a vegetation and biogeochemical gradient.

Science.gov (United States)

Winton, R Scott; Flanagan, Neal; Richardson, Curtis J

2017-01-01

Tropical wetlands are thought to be the most important source of interannual variability in atmospheric methane (CH4) concentrations, yet sparse data prevents them from being incorporated into Earth system models. This problem is particularly pronounced in the neotropics where bottom-up models based on water table depth are incongruent with top-down inversion models suggesting unaccounted sinks or sources of CH4. The newly documented vast areas of peatlands in the Amazon basin may account for an important unrecognized CH4 source, but the hydrologic and biogeochemical controls of CH4 dynamics from these systems remain poorly understood. We studied three zones of a peatland in Madre de Dios, Peru, to test whether CH4 emissions and pore water concentrations varied with vegetation community, soil chemistry and proximity to groundwater sources. We found that the open-canopy herbaceous zone emitted roughly one-third as much CH4 as the Mauritia flexuosa palm-dominated areas (4.7 ± 0.9 and 14.0 ± 2.4 mg CH4 m-2 h-1, respectively). Emissions decreased with distance from groundwater discharge across the three sampling sites, and tracked changes in soil carbon chemistry, especially increased soil phenolics. Based on all available data, we calculate that neotropical peatlands contribute emissions of 43 ± 11.9 Tg CH4 y-1, however this estimate is subject to geographic bias and will need revision once additional studies are published.

Neotropical peatland methane emissions along a vegetation and biogeochemical gradient.

Directory of Open Access Journals (Sweden)

R Scott Winton

Full Text Available Tropical wetlands are thought to be the most important source of interannual variability in atmospheric methane (CH4 concentrations, yet sparse data prevents them from being incorporated into Earth system models. This problem is particularly pronounced in the neotropics where bottom-up models based on water table depth are incongruent with top-down inversion models suggesting unaccounted sinks or sources of CH4. The newly documented vast areas of peatlands in the Amazon basin may account for an important unrecognized CH4 source, but the hydrologic and biogeochemical controls of CH4 dynamics from these systems remain poorly understood. We studied three zones of a peatland in Madre de Dios, Peru, to test whether CH4 emissions and pore water concentrations varied with vegetation community, soil chemistry and proximity to groundwater sources. We found that the open-canopy herbaceous zone emitted roughly one-third as much CH4 as the Mauritia flexuosa palm-dominated areas (4.7 ± 0.9 and 14.0 ± 2.4 mg CH4 m-2 h-1, respectively. Emissions decreased with distance from groundwater discharge across the three sampling sites, and tracked changes in soil carbon chemistry, especially increased soil phenolics. Based on all available data, we calculate that neotropical peatlands contribute emissions of 43 ± 11.9 Tg CH4 y-1, however this estimate is subject to geographic bias and will need revision once additional studies are published.

Azolla-anabaena-bacteria system as a natural microcosm

Science.gov (United States)

Carrapico, Francisco J.

2002-02-01

Azolla is an aquatic fern that contains a permanent endosymbiotic prokaryotic community (cyanobacteria and bacteria) inside of the cavity in the leaf dorsal lobe of the pteridophyte. This is a unique situation and can be seen as a microcosm inside of an organism and also can be considered a good example of a living model for biological and environmental studies. These symbionts are specific of this symbiosis and lives immobilized in a mucilaginous fibrillar network, which fills part of the cavity. The symbionts works as immobilized organisms in a natural system that can be used as a model for biotechnological research and in biologically based life support systems. The nature and the complexity of this system is simultaneously a reference and a challenge for the research in the communication between the two levels of nature organization (microcosm and mesocosm), and can also be used as a reference for the design of new environmental engineered symbiotic systems that include man as a prelude to life in space.

Natural Characteristics of The Herringbone Gear Transmission System

Science.gov (United States)

Zhou, Jianxing; Sun, Wenlei; Cao, Li

2018-03-01

According to the structure characteristics of herringbone gear transmission, a more realistic dynamic model of the transmission system is built in consideration of the inner excitation, herringbone gears axial positioning and sliding bearing etc. The natural frequencies of the system are calculated, and the vibration mode is divided into symmetric vibration modes and asymmetric vibration modes. The time history of system dynamic force is obtained by solving the dynamic model. The effects of the connection stiffness of left and right sides of herringbone gears and axial support stiffness on natural characteristics are discussed.

Oceanographic and Biogeochemical Insights from Diatom Genomes

Science.gov (United States)

Bowler, Chris; Vardi, Assaf; Allen, Andrew E.

2010-01-01

Diatoms are the most successful group of eukaryotic phytoplankton in the modern ocean and have risen to dominance relatively quickly over the last 100 million years. Recently completed whole genome sequences from two species of diatom, Thalassiosira pseudonana and Phaeodactylum tricornutum, have revealed a wealth of information about the evolutionary origins and metabolic adaptations that have led to their ecological success. A major finding is that they have incorporated genes both from their endosymbiotic ancestors and by horizontal gene transfer from marine bacteria. This unique melting pot of genes encodes novel capacities for metabolic management, for example, allowing the integration of a urea cycle into a photosynthetic cell. In this review we show how genome-enabled approaches are being leveraged to explore major phenomena of oceanographic and biogeochemical relevance, such as nutrient assimilation and life histories in diatoms. We also discuss how diatoms may be affected by climate change-induced alterations in ocean processes.

Biogeochemical reactive-diffusive transport of heavy metals in Lake Coeur d'Alene sediments

International Nuclear Information System (INIS)

Sevinc Sengoer, S.; Spycher, Nicolas F.; Ginn, Timothy R.; Sani, Rajesh K.; Peyton, Brent

2007-01-01

Decades of runoff from precious-metal mining operations in the Lake Coeur d'Alene Basin, Idaho, have left the sediments in this lake heavily enriched with toxic metals, most notably Zn, Pb and Cu, together with As. The bioavailability, fate and transport of these metals in the sediments are governed by complex biogeochemical processes. In particular, indigenous microbes are capable of catalyzing reactions that detoxify their environments, and thus constitute an important driving component in the biogeochemical cycling of these metals. Here, the development of a quantitative model to evaluate the transport and fate of Zn, Pb and Cu in Lake Coeur d'Alene sediments is reported. The current focus is on the investigation and understanding of local-scale processes, rather than the larger-scale dynamics of sedimentation and diagenesis, with particular emphasis on metal transport through reductive dissolution of Fe hydroxides. The model includes 1-D inorganic diffusive transport coupled to a biotic reaction network including consortium biodegradation kinetics with multiple terminal electron acceptors and syntrophic consortium biotransformation dynamics of redox front. The model captures the mobilization of metals initially sorbed onto hydrous ferric oxides, through bacterial reduction of Fe(III) near the top of the sediment column, coupled with the precipitation of metal sulfides at depth due to biogenic sulfide production. Key chemical reactions involve the dissolution of ferrihydrite and precipitation of siderite and Fe sulfide. The relative rates of these reactions play an important role in the evolution of the sediment pore-water chemistry, notably pH, and directly depend on the relative activity of Fe and SO 4 reducers. The model captures fairly well the observed trends of increased alkalinity, sulfide, Fe and heavy metal concentrations below the sediment-water interface, together with decreasing terminal electron acceptor concentrations with depth, including the

Numerical modeling of watershed-scale radiocesium transport coupled with biogeochemical cycling in forests

Science.gov (United States)

Mori, K.; Tada, K.; Tawara, Y.; Tosaka, H.; Ohno, K.; Asami, M.; Kosaka, K.

2015-12-01

Since the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident, intensive monitoring and modeling works on radionuclide transfer in environment have been carried out. Although Cesium (Cs) concentration has been attenuating due to both physical and environmental half-life (i.e., wash-off by water and sediment), the attenuation rate depends clearly on the type of land use and land cover. In the Fukushima case, studying the migration in forest land use is important for predicting the long-term behavior of Cs because most of the contaminated region is covered by forests. Atmospheric fallout is characterized by complicated behavior in biogeochemical cycle in forests which can be described by biotic/abiotic interactions between many components. In developing conceptual and mathematical model on Cs transfer in forest ecosystem, defining the dominant components and their interactions are crucial issues (BIOMASS, 1997-2001). However, the modeling of fate and transport in geosphere after Cs exports from the forest ecosystem is often ignored. An integrated watershed modeling for simulating spatiotemporal redistribution of Cs that includes the entire region from source to mouth and surface to subsurface, has been recently developed. Since the deposited Cs can migrate due to water and sediment movement, the different species (i.e., dissolved and suspended) and their interactions are key issues in the modeling. However, the initial inventory as source-term was simplified to be homogeneous and time-independent, and biogeochemical cycle in forests was not explicitly considered. Consequently, it was difficult to evaluate the regionally-inherent characteristics which differ according to land uses, even if the model was well calibrated. In this study, we combine the different advantages in modeling of forest ecosystem and watershed. This enable to include more realistic Cs deposition and time series of inventory can be forced over the land surface. These processes are integrated

The Integrated Information System for Natural Disaster Mitigation

Directory of Open Access Journals (Sweden)

Junxiu Wu

2007-08-01

Full Text Available Supported by the World Bank, the Integrated Information System for Natural Disaster Mitigation (ISNDM, including the operational service system and network telecommunication system, has been in development for three years in the Center of Disaster Reduction, Chinese Academy of Sciences, based on the platform of the GIS software Arcview. It has five main modules: disaster background information, socio- economic information, disaster-induced factors database, disaster scenarios database, and disaster assessment. ISNDM has several significant functions, which include information collection, information processing, data storage, and information distribution. It is a simple but comprehensive demonstration system for our national center for natural disaster reduction.

Biogeochemical hotspots following a simulated tree mortality event of southern pine beetle

Science.gov (United States)

Siegert, C. M.; Renninger, H. J.; Karunarathna, S.; Hornslein, N.; Riggins, J. J.; Clay, N. A.; Tang, J. D.; Chaney, B.; Drotar, N.

2017-12-01

Disturbances in forest ecosystems can alter functions like productivity, respiration, and nutrient cycling through the creation of biogeochemical hotspots. These events occur sporadically across the landscape, leading to uncertainty in terrestrial biosphere carbon models, which have yet to capture the full complexity of biotic and abiotic factors driving ecological processes in the terrestrial environment. Given the widespread impact of southern pine beetle on forest ecosystems throughout the southeastern United States, it is critical to management and planning activities to understand the role of these disturbances. As such, we hypothesize that bark beetle killed trees create biogeochemical hotspots in the soils surrounding their trunk as they undergo mortality due to (1) increased soil moisture from reductions in plant water uptake and increased stemflow production, (2) enhanced canopy-derived inputs of carbon and nitrogen, and (3) increased microbial activity and root mortality. In 2015, a field experiment to mimic a southern pine beetle attack was established by girdling loblolly pine trees. Subsequent measurements of throughfall and stemflow for water quantity and quality, transpiration, stem respiration, soil respiration, and soil chemistry were used to quantify the extent of spatial and temporal impacts of tree mortality on carbon budgets. Compared to control trees, girdled trees exhibited reduced water uptake within the first 6 months of the study and succumbed to mortality within 18 months. Over two years, the girdled trees generated 33% more stemflow than control trees (7836 vs. 5882 L m-2). Preliminary analysis of carbon and nitrogen concentrations and dissolved organic matter quality are still pending. In the surrounding soils, C:N ratios were greater under control trees (12.8) than under girdled trees (12.1), which was driven by an increase in carbon around control trees (+0.13 mg C mg-1 soil) and not a decrease around girdled trees (-0.01 mg C mg-1

Host–virus dynamics and subcellular controls of cell fate in a natural coccolithophore population

Science.gov (United States)

Vardi, Assaf; Haramaty, Liti; Van Mooy, Benjamin A. S.; Fredricks, Helen F.; Kimmance, Susan A.; Larsen, Aud; Bidle, Kay D.

2012-01-01

Marine viruses are major evolutionary and biogeochemical drivers in marine microbial foodwebs. However, an in-depth understanding of the cellular mechanisms and the signal transduction pathways mediating host–virus interactions during natural bloom dynamics has remained elusive. We used field-based mesocosms to examine the “arms race” between natural populations of the coccolithophore Emiliania huxleyi and its double-stranded DNA-containing coccolithoviruses (EhVs). Specifically, we examined the dynamics of EhV infection and its regulation of cell fate over the course of bloom development and demise using a diverse suite of molecular tools and in situ fluorescent staining to target different levels of subcellular resolution. We demonstrate the concomitant induction of reactive oxygen species, caspase-specific activity, metacaspase expression, and programmed cell death in response to the accumulation of virus-derived glycosphingolipids upon infection of natural E. huxleyi populations. These subcellular responses to viral infection simultaneously resulted in the enhanced production of transparent exopolymer particles, which can facilitate aggregation and stimulate carbon flux. Our results not only corroborate the critical role for glycosphingolipids and programmed cell death in regulating E. huxleyi–EhV interactions, but also elucidate promising molecular biomarkers and lipid-based proxies for phytoplankton host–virus interactions in natural systems. PMID:23134731

Hydrological and associated biogeochemical consequences of rapid global warming during the Paleocene-Eocene Thermal Maximum

Science.gov (United States)

Carmichael, Matthew J.; Inglis, Gordon N.; Badger, Marcus P. S.; Naafs, B. David A.; Behrooz, Leila; Remmelzwaal, Serginio; Monteiro, Fanny M.; Rohrssen, Megan; Farnsworth, Alexander; Buss, Heather L.; Dickson, Alexander J.; Valdes, Paul J.; Lunt, Daniel J.; Pancost, Richard D.

2017-10-01

The Paleocene-Eocene Thermal Maximum (PETM) hyperthermal, 56 million years ago (Ma), is the most dramatic example of abrupt Cenozoic global warming. During the PETM surface temperatures increased between 5 and 9 °C and the onset likely took hydrological and associated biogeochemical feedbacks, and proxy data from the PETM can provide constraints on changes in warm climate hydrology simulated by general circulation models (GCMs). In this paper, we provide a critical review of biological and geochemical signatures interpreted as direct or indirect indicators of hydrological change at the PETM, explore the importance of adopting multi-proxy approaches, and present a preliminary model-data comparison. Hydrological records complement those of temperature and indicate that the climatic response at the PETM was complex, with significant regional and temporal variability. This is further illustrated by the biogeochemical consequences of inferred changes in hydrology and, in fact, changes in precipitation and the biogeochemical consequences are often conflated in geochemical signatures. There is also strong evidence in many regions for changes in the episodic and/or intra-annual distribution of precipitation that has not widely been considered when comparing proxy data to GCM output. Crucially, GCM simulations indicate that the response of the hydrological cycle to the PETM was heterogeneous - some regions are associated with increased precipitation - evaporation (P - E), whilst others are characterised by a decrease. Interestingly, the majority of proxy data come from the regions where GCMs predict an increase in PETM precipitation. We propose that comparison of hydrological proxies to GCM output can be an important test of model skill, but this will be enhanced by further data from regions of model-simulated aridity and simulation of extreme precipitation events.

Pre- and post-industrial environmental changes as revealed by the biogeochemical sedimentary record of Drammensfjord, Norway

NARCIS (Netherlands)

Smittenberg, R.H.; Baas, M.; Green, M.J.; Hopmans, E.C.; Schouten, S.; Sinninghe Damsté, J.S.

2005-01-01

The biogeochemical sedimentary record of the anoxic Drammensfjord, Norway, was investigated on a decadal to centennial time scale over the last millennium, in order to reconstruct the pre-industrial fjord environment and ecosystem and humaninduced environmental changes. The sediments were dated by

Pre- and post-industrial environmental changes as revealed by the biogeochemical sedimentary record of Drammensfjord, Norway

NARCIS (Netherlands)

Sinninghe Damsté, J.S.; Smittenberg, R.H.; Baas, M.; Green, M.J.; Hopmans, E.C.; Schouten, S.

2005-01-01

The biogeochemical sedimentary record of the anoxic Drammensfjord, Norway, was investigated on a decadal to centennial time scale over the last millennium, in order to reconstruct the pre-industrial fjord environment and ecosystem and human-induced environmental changes. The sediments were dated by

[The fate of nuclides in natural water systems

International Nuclear Information System (INIS)

Turekian, K.K.

1989-01-01

Our research at Yale on the fate of nuclides in natural water systems has three components to it: the study of the atmospheric precipitation of radionuclides and other chemical species; the study of the behavior of natural radionuclides in groundwater and hydrothermal systems; and understanding the controls on the distribution of radionuclides and stable nuclides in the marine realm. In this section a review of our progress in each of these areas is presented

Natural and accelerated bioremediation research program plan

International Nuclear Information System (INIS)

1995-09-01

This draft plan describes a ten-year program to develop the scientific understanding needed to harness and develop natural and enhanced biogeochemical processes to bioremediate contaminated soils, sediments and groundwater at DOE facilities. The Office of Health and Environmental Research (OHER) developed this program plan, with advice and assistance from DOE's Office of Environmental Management (EM). The program builds on OHER's tradition of sponsoring fundamental research in the life and environmental sciences and was motivated by OHER's and Office of Energy Research's (OER's) commitment to supporting DOE's environmental management mission and the belief that bioremediation is an important part of the solution to DOE's environmental problems

Towards better monitoring of technology critical elements in Europe: Coupling of natural and anthropogenic cycles.

Science.gov (United States)

Nuss, Philip; Blengini, Gian Andrea

2018-02-01

The characterization of elemental cycles has a rich history in biogeochemistry. Well known examples include the global carbon cycle, or the cycles of the 'grand nutrients' nitrogen, phosphorus, and sulfur. More recently, efforts have increased to better understand the natural cycling of technology critical elements (TCEs), i.e. elements with a high supply risk and economic importance in the EU. On the other hand, tools such as material-flow analysis (MFA) can help to understand how substances and goods are transported and accumulated in man-made technological systems ('anthroposphere'). However, to date both biogeochemical cycles and MFA studies suffer from narrow system boundaries, failing to fully illustrate relative anthropogenic and natural flow magnitude and the degree to which human activity has perturbed the natural cycling of elements. We discuss important interconnections between natural and anthropogenic cycles and relevant EU raw material dossiers. Increased integration of both cycles could help to better capture the transport and fate of elements in nature including their environmental/human health impacts, highlight potential future material stocks in the anthroposphere (in-use stocks) and in nature (e.g., in soils, tailings, or mining wastes), and estimate anticipated emissions of TCEs to nature in the future (based on dynamic stock modeling). A preliminary assessment of natural versus anthropogenic element fluxes indicates that anthropogenic fluxes induced by the EU-28 of palladium, platinum, and antimony (as a result of materials uses) might be greater than the respective global natural fluxes. Increased combination of MFA and natural cycle data at EU level could help to derive more complete material cycles and initiate a discussion between the research communities of biogeochemists and material flow analysts to more holistically address the issues of sustainable resource management. Copyright © 2017 The Authors. Published by Elsevier B.V. All

Nature-inspired design of hybrid intelligent systems

CERN Document Server

Castillo, Oscar; Kacprzyk, Janusz

2017-01-01

This book highlights recent advances in the design of hybrid intelligent systems based on nature-inspired optimization and their application in areas such as intelligent control and robotics, pattern recognition, time series prediction, and optimization of complex problems. The book is divided into seven main parts, the first of which addresses theoretical aspects of and new concepts and algorithms based on type-2 and intuitionistic fuzzy logic systems. The second part focuses on neural network theory, and explores the applications of neural networks in diverse areas, such as time series prediction and pattern recognition. The book’s third part presents enhancements to meta-heuristics based on fuzzy logic techniques and describes new nature-inspired optimization algorithms that employ fuzzy dynamic adaptation of parameters, while the fourth part presents diverse applications of nature-inspired optimization algorithms. In turn, the fifth part investigates applications of fuzzy logic in diverse areas, such as...

Environmental Systems Microbiology of Contaminated Environments

Energy Technology Data Exchange (ETDEWEB)

Sayler, Gary [University of Tennessee, Knoxville (UTK); Hazen, Terry C. [ORNL

2016-01-01

Environmental Systems Microbiology is well positioned to move forward in dynamic complex system analysis probing new questions and developing new insight into the function, robustness and resilience in response to anthropogenic perturbations. Recent studies have demonstrated that natural bacterial communities can be used as quantitative biosensors in both groundwater and deep ocean water, predicting oil concentration from the Gulf of Mexico Deep Water Horizon spill and from groundwater at nuclear production waste sites (16, 17, 25). Since the first demonstration of catabolic gene expression in soil remediation (34) it has been clear that extension beyond organismal abundance to process and function of microbial communities as a whole using the whole suite of omic tools available to the post genomic era. Metatranscriptomics have been highlighted as a prime vehicle for understanding responses to environmental drivers (35) in complex systems and with rapidly developing metabolomics, full functional understanding of complex community biogeochemical cycling is an achievable goal. Perhaps more exciting is the dynamic nature of these systems and their complex adaptive strategies that may lead to new control paradigms and emergence of new states and function in the course of a changing environment.

Andreae is New Editor of Global Biogeochemical Cycles

Science.gov (United States)

Andreae, Meinrat O.

2004-10-01

As the incoming editor of Global Biogeochemical Cycles, I would like to introduce myself and my ideas for the journal to Eos readers and to current and potential GBC authors. I've had a somewhat ``roaming'' scientific evolution, coming from ``straight'' chemistry through hard-rock geochemistry to chemical oceanography, the field in which I did my Ph.D. I taught marine chemistry at Florida State University for a number of years, and developed an interest in ocean/atmosphere interactions and atmospheric chemistry. In 1987 I took on my present job at the Max Planck Institute for Chemistry, in Mainz, Germany, and, after leaving the seacoast, my interests shifted to interactions between the terrestrial biosphere and atmosphere, including the role of vegetation fires. My present focus is on the role of biogenic aerosols and biomass smoke in regulating cloud properties and influencing climate.

MEDUSA-2.0: an intermediate complexity biogeochemical model of the marine carbon cycle for climate change and ocean acidification studies

Directory of Open Access Journals (Sweden)

A. Yool

2013-10-01

Full Text Available MEDUSA-1.0 (Model of Ecosystem Dynamics, nutrient Utilisation, Sequestration and Acidification was developed as an "intermediate complexity" plankton ecosystem model to study the biogeochemical response, and especially that of the so-called "biological pump", to anthropogenically driven change in the World Ocean (Yool et al., 2011. The base currency in this model was nitrogen from which fluxes of organic carbon, including export to the deep ocean, were calculated by invoking fixed C:N ratios in phytoplankton, zooplankton and detritus. However, due to anthropogenic activity, the atmospheric concentration of carbon dioxide (CO2 has significantly increased above its natural, inter-glacial background. As such, simulating and predicting the carbon cycle in the ocean in its entirety, including ventilation of CO2 with the atmosphere and the resulting impact of ocean acidification on marine ecosystems, requires that both organic and inorganic carbon be afforded a more complete representation in the model specification. Here, we introduce MEDUSA-2.0, an expanded successor model which includes additional state variables for dissolved inorganic carbon, alkalinity, dissolved oxygen and detritus carbon (permitting variable C:N in exported organic matter, as well as a simple benthic formulation and extended parameterizations of phytoplankton growth, calcification and detritus remineralisation. A full description of MEDUSA-2.0, including its additional functionality, is provided and a multi-decadal spin-up simulation (1860–2005 is performed. The biogeochemical performance of the model is evaluated using a diverse range of observational data, and MEDUSA-2.0 is assessed relative to comparable models using output from the Coupled Model Intercomparison Project (CMIP5.

The role of natural organics in radionuclide migration in natural aquifer systems

International Nuclear Information System (INIS)

Choppin, G.R.

1992-01-01

The wide variety of organic compounds present in natural waters is assessed for the role they may play in radionuclide and, especially, actinide migration. Some natural analog and environmental data are briefly reviewed for evaluation of the effect of organics in these systems. The binding constants and the kinetics of complexation of actinides by humics are discussed in terms of probable effects on actinide migration. The role of organics in redox, and in sorption, is also considered. (orig.)

Biogeochemical impact of a model western iron source in the Pacific Equatorial Undercurrent

OpenAIRE

Slemons, L.; Gorgues, T.; Aumont, Olivier; Menkès, Christophe; Murray, J. W.

2009-01-01

Trace element distributions in the source waters of the Pacific Equatorial Undercurrent (EUC) show the existence of elevated total acid-soluble iron concentrations. This region has been suggested to contribute enough bioavailable iron to regulate interannual and interglacial variability in biological productivity downstream in the high-nitrate low-chlorophyll upwelling zone of the eastern equatorial Pacific. We investigated the advection and first-order biogeochemical impact of an imposed, da...

Late winter biogeochemical conditions under sea ice in the Canadian High Arctic

Directory of Open Access Journals (Sweden)

Helen S. Findlay

2015-12-01

Full Text Available With the Arctic summer sea-ice extent in decline, questions are arising as to how changes in sea-ice dynamics might affect biogeochemical cycling and phenomena such as carbon dioxide (CO2 uptake and ocean acidification. Recent field research in these areas has concentrated on biogeochemical and CO2 measurements during spring, summer or autumn, but there are few data for the winter or winter–spring transition, particularly in the High Arctic. Here, we present carbon and nutrient data within and under sea ice measured during the Catlin Arctic Survey, over 40 days in March and April 2010, off Ellef Ringnes Island (78° 43.11′ N, 104° 47.44′ W in the Canadian High Arctic. Results show relatively low surface water (1–10 m nitrate (<1.3 µM and total inorganic carbon concentrations (mean±SD=2015±5.83 µmol kg−1, total alkalinity (mean±SD=2134±11.09 µmol kg−1 and under-ice pCO2sw (mean±SD=286±17 µatm. These surprisingly low wintertime carbon and nutrient conditions suggest that the outer Canadian Arctic Archipelago region is nitrate-limited on account of sluggish mixing among the multi-year ice regions of the High Arctic, which could temper the potential of widespread under-ice and open-water phytoplankton blooms later in the season.

Local Conceptualisation of Nature, Forest Knowledge Systems and ...

African Journals Online (AJOL)

Conventional forest and natural resource management tend to overshadow local forest management practices and ecological knowledge on which rural communities base their survival and livelihood strategies. This article examines how rural communities conceptualize nature, what forest knowledge systems they use and ...

Novel imaging techniques, integrated with mineralogical, geochemical and microbiological characterizations to determine the biogeochemical controls on technetium mobility in FRC sediments

Energy Technology Data Exchange (ETDEWEB)

Jonathan R. Lloyd

2009-02-03

-200 MBq; half life 6 hours) and its mobility was monitored using a {gamma}-camera. Incorporation of low concentrations of the long-lived 99Tc gave a tracer that can be followed by scintillation counting, should the metastable form of the radionuclide decay to below detection limits before the end of the experiment (complete immobilization or loss of the Tc from the column). After the Tc was reduced and immobilized, or passed through the system, the columns were dismantled carefully in an anaerobic cabinet and the pore water geochemistry and mineralogy of the columns profiled. Microbial community analysis was determined, again using molecular and culture-dependent techniques. Experimental results were also modeled using an established coupled speciation and transport code, to develop a predictive tool for the mobility of Tc in FRC sediments. From this multidisciplinary approach, we hoped to obtain detailed information on the microorganisms that control the biogeochemical cycling of key elements at the FRC, and we would also be able to determine the key factors that control the mobility of Tc at environmentally relevant concentrations at this site.

Sedimentary organic matter distributions, burrowing activity, and biogeochemical cycling: Natural patterns and experimental artifacts

Science.gov (United States)

Michaud, Emma; Aller, Robert, C.; Stora, Georges

2010-11-01

The coupling between biogenic reworking activity and reactive organic matter patterns within deposits is poorly understood and often ignored. In this study, we examined how common experimental treatments of sediment affect the burrowing behavior of the polychaete Nephtys incisa and how these effects may interact with reactive organic matter distributions to alter diagenetic transport - reaction balances. Sediment and animals were recovered from a subtidal site in central Long Island Sound, USA. The upper 15 cm of the sediment was sectioned into sub-intervals, and each interval separately sieved and homogenized. Three initial distributions of sediment and organic substrate reactivity were setup in a series of microcosms: (1) a reconstituted natural pattern with surface-derived sediment overlying sediment obtained from progressively deeper material to a depth of 15 cm (Natural); (2) a 15 cm thick sediment layer composed only of surface-derived sediment (Rich); and (3) a 15 cm thick layer composed of uniformally mixed sediment from the original 15 cm sediment profile (Averaged). The two last treatments are comparable to that used in microcosms in many previous studies of bioturbation and interspecific functional interaction experiments. Sediment grain size distributions were 97.5% silt-clay and showed no depth dependent patterns. Sediment porosity gradients were slightly altered by the treatments. Nepthys were reintroduced and aquariums were X-rayed regularly over 5 months to visualize and quantify spatial and temporal dynamics of burrows. The burrowing behaviour of adult populations having similar total biovolume, biomass, abundance, and individual sizes differed substantially as a function of treatment. Burrows in sediment with natural property gradients were much shallower and less dense than those in microcosms with altered gradients. The burrow volume/biovolume ratio was also lower in the substrate with natural organic reactivity gradients. Variation in food

Effects of hydrologic conditions on biogeochemical processes and organic pollutant degradation in salt marsh sediments

Science.gov (United States)

W. James Catallo

2000-01-01

This work addressed the influence of tidal vs. static hydrologic conditions on biogeochemical processes and the transformation of pollutant organic chemicals (eight representative N-, O-, and S-heterocycles (NOSHs) from coal chemicals, crude oils, and pyrogenic mixtures) in salt marsh sediments. The goals were to: (1) determine the effects of static (flooded, drained)...

Effects of Stratospheric Ozone Depletion, Solar UV Radiation, and Climate Change on Biogeochemical Cycling: Interactions and Feedbacks

Science.gov (United States)

Climate change modulates the effects of solar UV radiation on biogeochemical cycles in terrestrial and aquatic ecosystems, particularly for carbon cycling, resulting in UV-mediated positive or negative feedbacks on climate. Possible positive feedbacks discussed in this assessment...

Natural Language Generation for dialogue: system survey

NARCIS (Netherlands)

Theune, Mariet

Many natural language dialogue systems make use of `canned text' for output generation. This approach may be su±cient for dialogues in restricted domains where system utterances are short and simple and use fixed expressions (e.g., slot filling dialogues in the ticket reservation or travel

Assessment of the GHG Reduction Potential from Energy Crops Using a Combined LCA and Biogeochemical Process Models: A Review

Directory of Open Access Journals (Sweden)

Dong Jiang

2014-01-01

Full Text Available The main purpose for developing biofuel is to reduce GHG (greenhouse gas emissions, but the comprehensive environmental impact of such fuels is not clear. Life cycle analysis (LCA, as a complete comprehensive analysis method, has been widely used in bioenergy assessment studies. Great efforts have been directed toward establishing an efficient method for comprehensively estimating the greenhouse gas (GHG emission reduction potential from the large-scale cultivation of energy plants by combining LCA with ecosystem/biogeochemical process models. LCA presents a general framework for evaluating the energy consumption and GHG emission from energy crop planting, yield acquisition, production, product use, and postprocessing. Meanwhile, ecosystem/biogeochemical process models are adopted to simulate the fluxes and storage of energy, water, carbon, and nitrogen in the soil-plant (energy crops soil continuum. Although clear progress has been made in recent years, some problems still exist in current studies and should be addressed. This paper reviews the state-of-the-art method for estimating GHG emission reduction through developing energy crops and introduces in detail a new approach for assessing GHG emission reduction by combining LCA with biogeochemical process models. The main achievements of this study along with the problems in current studies are described and discussed.

Biogeochemical generation of dissolved inorganic carbon and nitrogen in the North Branch of inner Changjiang Estuary in a dry season

Science.gov (United States)

Zhai, Wei-Dong; Yan, Xiu-Li; Qi, Di

2017-10-01

We investigated the surface water carbonate system, nutrients, and relevant hydrochemical parameters in the inner Changjiang (Yangtze River) Estuary in early spring 2009 and 2010. The two surveys were carried out shortly after spring-tide days, and covered both the channel-like South Branch and the freshwater-blocked North Branch. In the North Branch, with a water residence time of approximately one month, we detected remarkable partial pressures of CO2 (pCO2) of 930-1518 μatm with a salinity range of 4.5-17.4, which were substantially higher than the South Branch pCO2 values of 700-1100 μatm at salinities of less than 0.88. The North Branch pCO2 distribution pattern is unique compared with many other estuaries where aquatic pCO2 normally declines with salinity increase. Furthermore, the biogeochemical additions of ammonium (7.4-65.7 μmol kg-1) and alkalinity (196-695 μmol kg-1) were identified in salinities between 4 and 16 in the North Branch. Based on field data analyses and simplified stoichiometric equations, we suggest that the relatively high North Branch pCO2 values and estuarine additions of dissolved inorganic nitrogen/carbon in the mid-salinity area were strongly associated with each other. These signals were primarily controlled by biogeochemical processes in the North Branch, combining biogenic organic matter decomposition (i.e. respiration), ammonia oxidation, CaCO3 dissolution, and CO2 degassing. In the upper reach of the South Branch, notable salinity values of 0.20-0.88 were detected, indicating saltwater spillover from the North Branch. These spillover waters had minor contributions (1.5-6.9%) to the springtime nutrient, dissolved inorganic carbon, and alkalinity export fluxes from Changjiang to the adjacent East China Sea. This is the first attempt to understand the biogeochemical controls of the unique pCO2 distributions in the North Branch, and to evaluate the effects of saltwater spillover from the North Branch on dry-season export fluxes

Can neap-spring tidal cycles modulate biogeochemical fluxes in the abyssal near-seafloor water column?

Science.gov (United States)

Turnewitsch, Robert; Dale, Andrew; Lahajnar, Niko; Lampitt, Richard S.; Sakamoto, Kei

2017-05-01

Before particulate matter that settles as 'primary flux' from the interior ocean is deposited into deep-sea sediments it has to traverse the benthic boundary layer (BBL) that is likely to cover almost all parts of the seafloor in the deep seas. Fluid dynamics in the BBL differ vastly from fluid dynamics in the overlying water column and, consequently, have the potential to lead to quantitative and compositional changes between primary and depositional fluxes. Despite this potential and the likely global relevance very little is known about mechanistic and quantitative aspects of the controlling processes. Here, results are presented for a sediment-trap time-series study that was conducted on the Porcupine Abyssal Plain in the abyssal Northeast Atlantic, with traps deployed at 2, 40 and 569 m above bottom (mab). The two bottommost traps were situated within the BBL-affected part of the water column. The time series captured 3 neap and 4 spring tides and the arrival of fresh settling material originating from a surface-ocean bloom. In the trap-collected material, total particulate matter (TPM), particulate inorganic carbon (PIC), biogenic silica (BSi), particulate organic carbon (POC), particulate nitrogen (PN), total hydrolysable amino acids (AA), hexosamines (HA) and lithogenic material (LM) were determined. The biogeochemical results are presented within the context of time series of measured currents (at 15 mab) and turbidity (at 1 mab). The main outcome is evidence for an effect of neap/spring tidal oscillations on particulate-matter dynamics in BBL-affected waters in the deep sea. Based on the frequency-decomposed current measurements and numerical modelling of BBL fluid dynamics, it is concluded that the neap/spring tidal oscillations of particulate-matter dynamics are less likely due to temporally varying total free-stream current speeds and more likely due to temporally and vertically varying turbulence intensities that result from the temporally varying

Politics of Natural Resource Management and Accountable Systems ...

African Journals Online (AJOL)

The political behaviour of public institutions exhibited in the management of critical natural ... natural resource management and the modes in which they impact on accountable systems in Uganda. ... the provision of critical resources such as water at the expense of consumers and citizens. ... AJOL African Journals Online.

Supercontinent tectonics and biogeochemical cycle: A matter of ‘life and death’

Directory of Open Access Journals (Sweden)

M. Santosh

2010-10-01

Full Text Available The formation and disruption of supercontinents have significantly impacted mantle dynamics, solid earth processes, surface environments and the biogeochemical cycle. In the early history of the Earth, the collision of parallel intra-oceanic arcs was an important process in building embryonic continents. Superdownwelling along Y-shaped triple junctions might have been one of the important processes that aided in the rapid assembly of continental fragments into closely packed supercontinents. Various models have been proposed for the fragmentation of supercontinents including thermal blanket and superplume hypotheses. The reassembly of supercontinents after breakup and the ocean closure occurs through “introversion”, “extroversion” or a combination of both, and is characterized by either Pacific-type or Atlantic-type ocean closure. The breakup of supercontinents and development of hydrothermal system in rifts with granitic basement create anomalous chemical environments enriched in nutrients, which serve as the primary building blocks of the skeleton and bone of early modern life forms. A typical example is the rifting of the Rodinia supercontinent, which opened up an N–S oriented sea way along which nutrient enriched upwelling brought about a habitable geochemical environment. The assembly of supercontinents also had significant impact on life evolution. The role played by the Cambrian Gondwana assembly has been emphasized in many models, including the formation of ‘Transgondwana Mountains’ that might have provided an effective source of rich nutrients to the equatorial waters, thus aiding the rapid increase in biodiversity. The planet has witnessed several mass extinction events during its history, mostly connected with major climatic fluctuations including global cooling and warming events, major glaciations, fluctuations in sea level, global anoxia, volcanic eruptions, asteroid impacts and gamma radiation. Some recent models

Experimental studies in a single-phase parallel channel natural circulation system. Preliminary results

International Nuclear Information System (INIS)

Bodkha, Kapil; Pilkhwal, D.S.; Jana, S.S.; Vijayan, P.K.

2016-01-01

Natural circulation systems find extensive applications in industrial engineering systems. One of the applications is in nuclear reactor where the decay heat is removed by natural circulation of the fluid under off-normal conditions. The upcoming reactor designs make use of natural circulation in order to remove the heat from core under normal operating conditions also. These reactors employ multiple vertical fuel channels with provision of on-power refueling/defueling. Natural circulation systems are relatively simple, safe and reliable when compared to forced circulation systems. However, natural circulation systems are prone to encounter flow instabilities which are highly undesirable for various reasons. Presence of parallel channels under natural circulation makes the system more complicated. To examine the behavior of parallel channel system, studies were carried out for single-phase natural circulation flow in a multiple vertical channel system. The objective of the present work is to study the flow behavior of the parallel heated channel system under natural circulation for different operating conditions. Steady state and transient studies have been carried out in a parallel channel natural circulation system with three heated channels. The paper brings out the details of the system considered, different cases analyzed and preliminary results of studies carried out on a single-phase parallel channel system.

Deliverability on the interstate natural gas pipeline system

Energy Technology Data Exchange (ETDEWEB)

NONE

1998-05-01

Deliverability on the Interstate Natural Gas Pipeline System examines the capability of the national pipeline grid to transport natural gas to various US markets. The report quantifies the capacity levels and utilization rates of major interstate pipeline companies in 1996 and the changes since 1990, as well as changes in markets and end-use consumption patterns. It also discusses the effects of proposed capacity expansions on capacity levels. The report consists of five chapters, several appendices, and a glossary. Chapter 1 discusses some of the operational and regulatory features of the US interstate pipeline system and how they affect overall system design, system utilization, and capacity expansions. Chapter 2 looks at how the exploration, development, and production of natural gas within North America is linked to the national pipeline grid. Chapter 3 examines the capability of the interstate natural gas pipeline network to link production areas to market areas, on the basis of capacity and usage levels along 10 corridors. The chapter also examines capacity expansions that have occurred since 1990 along each corridor and the potential impact of proposed new capacity. Chapter 4 discusses the last step in the transportation chain, that is, deliverability to the ultimate end user. Flow patterns into and out of each market region are discussed, as well as the movement of natural gas between States in each region. Chapter 5 examines how shippers reserve interstate pipeline capacity in the current transportation marketplace and how pipeline companies are handling the secondary market for short-term unused capacity. Four appendices provide supporting data and additional detail on the methodology used to estimate capacity. 32 figs., 15 tabs.

Implementation ambiguity: The fifth element long lost in uncertainty budgets for land biogeochemical modeling

Science.gov (United States)

Tang, J.; Riley, W. J.

2015-12-01

Previous studies have identified four major sources of predictive uncertainty in modeling land biogeochemical (BGC) processes: (1) imperfect initial conditions (e.g., assumption of preindustrial equilibrium); (2) imperfect boundary conditions (e.g., climate forcing data); (3) parameterization (type I equifinality); and (4) model structure (type II equifinality). As if that were not enough to cause substantial sleep loss in modelers, we propose here a fifth element of uncertainty that results from implementation ambiguity that occurs when the model's mathematical description is translated into computational code. We demonstrate the implementation ambiguity using the example of nitrogen down regulation, a necessary process in modeling carbon-climate feedbacks. We show that, depending on common land BGC model interpretations of the governing equations for mineral nitrogen, there are three different implementations of nitrogen down regulation. We coded these three implementations in the ACME land model (ALM), and explored how they lead to different preindustrial and contemporary land biogeochemical states and fluxes. We also show how this implementation ambiguity can lead to different carbon-climate feedback estimates across the RCP scenarios. We conclude by suggesting how to avoid such implementation ambiguity in ESM BGC models.

Novel food packaging systems with natural antimicrobial agents.

Science.gov (United States)

Irkin, Reyhan; Esmer, Ozlem Kizilirmak

2015-10-01

A new type of packaging that combines food packaging materials with antimicrobial substances to control microbial surface contamination of foods to enhance product microbial safety and to extend shelf-life is attracting interest in the packaging industry. Several antimicrobial compounds can be combined with different types of packaging materials. But in recent years, since consumer demand for natural food ingredients has increased because of safety and availability, these natural compounds are beginning to replace the chemical additives in foods and are perceived to be safer and claimed to alleviate safety concerns. Recent research studies are mainly focused on the application of natural antimicrobials in food packaging system. Biologically derived compounds like bacteriocins, phytochemicals, enzymes can be used in antimicrobial food packaging. The aim of this review is to give an overview of most important knowledge about application of natural antimicrobial packagings with model food systems and their antimicrobial effects on food products.

[Elaboration of Pseudo-natural Products Using Artificial In Vitro Biosynthesis Systems].

Science.gov (United States)

Goto, Yuki

2018-01-01

 Peptidic natural products often consist of not only proteinogenic building blocks but also unique non-proteinogenic structures such as macrocyclic scaffolds and N-methylated backbones. Since such non-proteinogenic structures are important structural motifs that contribute to diverse bioactivity, we have proposed that peptides with non-proteinogenic structures should be attractive candidates as artificial bioactive peptides mimicking natural products, or so-called pseudo-natural products. We previously devised an engineered translation system for pseudo-natural peptides, referred to as the flexible in vitro translation (FIT) system. This system enabled "one-pot" synthesis of highly diverse pseudo-natural peptide libraries, which can be rapidly screened by mRNA display technology for the discovery of pseudo-natural peptides with diverse bioactivities.

Biogeochemical and Ecomorphological Niche Segregation of Mediterranean Woody Species along a Local Gradient

OpenAIRE

Enrique G. de la Riva; Enrique G. de la Riva; Teodoro Marañón; Cyrille Violle; Rafael Villar; Ignacio M. Pérez-Ramos

2017-01-01

According with niche theory the species are specialized in different ecological niches, being able to coexist as result of a differential use of resources. In this context, the biogeochemical niche hypothesis proposes that species have an optimal elemental composition which results from the link between the chemical and morphological traits for the optimum plant functioning. Thus, and attending to the limiting similarity concept, different elemental composition and plant structure among co-oc...

Identifying biogeochemical processes beneath stormwater infiltration ponds in support of a new best management practice for groundwater protection

Science.gov (United States)

O'Reilly, Andrew M.; Chang, Ni-Bin; Wanielista, Martin P.; Xuan, Zhemin; Schirmer, Mario; Hoehn, Eduard; Vogt, Tobias

2011-01-01

 When applying a stormwater infiltration pond best management practice (BMP) for protecting the quality of underlying groundwater, a common constituent of concern is nitrate. Two stormwater infiltration ponds, the SO and HT ponds, in central Florida, USA, were monitored. A temporal succession of biogeochemical processes was identified beneath the SO pond, including oxygen reduction, denitrification, manganese and iron reduction, and methanogenesis. In contrast, aerobic conditions persisted beneath the HT pond, resulting in nitrate leaching into groundwater. Biogeochemical differences likely are related to soil textural and hydraulic properties that control surface/subsurface oxygen exchange. A new infiltration BMP was developed and a full-scale application was implemented for the HT pond. Preliminary results indicate reductions in nitrate concentration exceeding 50% in soil water and shallow groundwater beneath the HT pond.

Natural circulation in reactor coolant system

International Nuclear Information System (INIS)

Han, J.T.

1987-01-01

Reactor coolant system (RCS) natural circulation in a PWR is the buoyancy-driven coolant circulation between the core and the upper-plenum region (in-vessel circulation) with or without a countercurrent flow in the hot leg piping between the vessel and steam generators (ex-vessel circulation). This kind of multidimensional bouyancy-driven flow circulation serves as a means of transferring the heat from the core to the structures in the upper plenum, hot legs, and possibly steam generators. As a result, the RCS piping and other pressure boundaries may be heated to high temperatures at which the structural integrity is challenged. RCS natural circulation is likely to occur during the core uncovery period of the TMLB' accident in a PWR when the vessel upper plenum and hot leg are already drained and filled with steam and possibly other gaseous species. RCS natural circulation is being studied for the Surry plant during the TMLB' accident in which station blackout coincides with the loss of auxiliary feedwater and no operator actions. The effects of the multidimensional RCS natural circulation during the TMLB' accident are discussed

Natural and anthropogenic decadal pH decrease in the North Atlantic and Mediterranean Sea waters

Science.gov (United States)

Huertas, E.; Flecha, S.; Murata, A.; Garcia Lafuente, J.; Pérez, F. F.

2017-12-01

Seawater pH is undergoing a decreasing trend due to atmospheric CO2 absorption, a phenomenon known as Ocean Acidification (OA) that has been documented in different ocean regions. Certain marine basins are more vulnerable to OA, such as the Mediterranean Sea (MS), which is attributed to particular water circulation processes and biogeochemical features. Considering previous studies on OA in Mediterranean and Atlantic water masses, the main aim of this work was to identify for the first time the natural and anthropogenic contribution to decadal pH variations. Therefore, an archetypal analysis was applied to pH measurements and other biogeochemical variables collected in the Strait of Gibraltar during 10 years. Our results reveal that the biological component of the pH change in the Western Mediterranean Deep Water (WMDW) (ΔpHWMDW) represents around 56% of the total decadal pH decrease observed, highlighting the relevance of the remineralization occurring in the Alboran basin, where the WMDW resides before leaving the MS. On the other hand, neither natural nor anthropogenic forcing on the pH change in the Levantine Intermediate Water (ΔpHLIW) was detected, as pH variation was negligible. As for the North Atlantic Central Water (NACW), atmospheric CO2 uptake was responsible of 58% of the ΔpHNACW, likely related to permanent contact with the atmosphere. Additionally, estimations of the approximated ages of the NACW, LIW and WMDW in the SG of about 8, 34 and 32 years respectively have been obtained. Our results show that Mediterranean waters undergo changes in their biogeochemical characteristics during transit through the SG and gives insights on the main mechanisms affecting pH variations occurring from their formation sites to the SG.

Effects of increased solar ultraviolet radiation on biogeochemical cycles

International Nuclear Information System (INIS)

Zepp, R.G.; Callaghan, T.V.; Erickson, D.J.

1995-01-01

Increases in solar UV radiation could affect terrestrial and aquatic biogeochemical cycles thus altering both sources and sinks of greenhouse and chemically important trace gases (e.g., carbon dioxide (CO2), carbon monoxide (CO), carbonyl sulfide (COS). In terrestrial ecosystems, increased UV-B could modify both the production and decomposition of plant matter with concomitant changes in the uptake and release of atmospherically important trace gases. Decomposition processes can be accelerated when UV-B photodegrades surface litter, or retarded when the dominant effect involves changes in the chemical composition of living tissues that reduce the biodegradability of buried litter. These changes in decomposition can affect microbial production of CO2 and other trace gases and also may affect the availability of nutrients essential for plant growth. Primary production can be reduced by enhanced UV-B, but the effect is variable between species and even cultivars of some crops. Likewise, the effects of enhanced UV-B on photoproduction of CO from plant matter is species-dependent and occurs more efficiently from dead than from living matter. Aquatic ecosystems studies in several different locations have shown that reductions in current levels of solar UV-B result in enhanced primary production, and Antarctic experiments under the ozone hole demonstrated that primary production is inhibited by enhanced UV-B. In addition to its effects on primary production, solar UV radiation can reduce bacterioplankton growth in the upper ocean with potentially important effects on marine biogeochemical cycles. Decomposition processes can be retarded when bacterial activity is suppressed by enhanced UV-B radiation or stimulated when solar UV radiation photodegrades aquatic dissolved organic matter. Photodegradation of DOM results in loss of UV absorption and formation of dissolved inorganic carbon, CO, and organic substrates that are readily mineralized or taken up by aquatic

Combined effects of hydrologic alteration and cyprinid fish in mediating biogeochemical processes in a Mediterranean stream.

Science.gov (United States)

Rubio-Gracia, Francesc; Almeida, David; Bonet, Berta; Casals, Frederic; Espinosa, Carmen; Flecker, Alexander S; García-Berthou, Emili; Martí, Eugènia; Tuulaikhuu, Baigal-Amar; Vila-Gispert, Anna; Zamora, Lluis; Guasch, Helena

2017-12-01

Flow regimes are important drivers of both stream community and biogeochemical processes. However, the interplay between community and biogeochemical responses under different flow regimes in streams is less understood. In this study, we investigated the structural and functional responses of periphyton and macroinvertebrates to different densities of the Mediterranean barbel (Barbus meridionalis, Cyprinidae) in two stream reaches differing in flow regime. The study was conducted in Llémena Stream, a small calcareous Mediterranean stream with high nutrient levels. We selected a reach with permanent flow (permanent reach) and another subjected to flow regulation (regulated reach) with periods of flow intermittency. At each reach, we used in situ cages to generate 3 levels of fish density. Cages with 10 barbels were used to simulate high fish density (>7indm -2 ); cages with open sides were used as controls (i.e. exposed to actual fish densities of each stream reach) thus having low fish density; and those with no fish were used to simulate the disappearance of fish that occurs with stream drying. Differences in fish density did not cause significant changes in periphyton biomass and macroinvertebrate density. However, phosphate uptake by periphyton was enhanced in treatments lacking fish in the regulated reach with intermittent flow but not in the permanent reach, suggesting that hydrologic alteration hampers the ability of biotic communities to compensate for the absence of fish. This study indicates that fish density can mediate the effects of anthropogenic alterations such as flow intermittence derived from hydrologic regulation on stream benthic communities and associated biogeochemical processes, at least in eutrophic streams. Copyright © 2017. Published by Elsevier B.V.

Dynamic biogeochemical provinces in the global ocean

Science.gov (United States)

Reygondeau, Gabriel; Longhurst, Alan; Martinez, Elodie; Beaugrand, Gregory; Antoine, David; Maury, Olivier

2013-12-01

In recent decades, it has been found useful to partition the pelagic environment using the concept of biogeochemical provinces, or BGCPs, within each of which it is assumed that environmental conditions are distinguishable and unique at global scale. The boundaries between provinces respond to features of physical oceanography and, ideally, should follow seasonal and interannual changes in ocean dynamics. But this ideal has not been fulfilled except for small regions of the oceans. Moreover, BGCPs have been used only as static entities having boundaries that were originally established to compute global primary production. In the present study, a new statistical methodology based on non-parametric procedures is implemented to capture the environmental characteristics within 56 BGCPs. Four main environmental parameters (bathymetry, chlorophyll a concentration, surface temperature, and salinity) are used to infer the spatial distribution of each BGCP over 1997-2007. The resulting dynamic partition allows us to integrate changes in the distribution of BGCPs at seasonal and interannual timescales, and so introduces the possibility of detecting spatial shifts in environmental conditions.

Simulating temporal variations of nitrogen losses in river networks with a dynamic transport model unravels the coupled effects of hydrological and biogeochemical processes

Energy Technology Data Exchange (ETDEWEB)

Mulholland, Patrick J [ORNL; Alexander, Richard [U.S. Geological Survey; Bohlke, John [U.S. Geological Survey; Boyer, Elizabeth [Pennsylvania State University; Harvey, Judson [U.S. Geological Survey; Seitzinger, Sybil [Rutgers University; Tobias, Craig [University of North Carolina, Wilmington; Tonitto, Christina [Cornell University; Wollheim, Wilfred [University of New Hampshire

2009-01-01

The importance of lotic systems as sinks for nitrogen inputs is well recognized. A fraction of nitrogen in streamflow is removed to the atmosphere via denitrification with the remainder exported in streamflow as nitrogen loads. At the watershed scale, there is a keen interest in understanding the factors that control the fate of nitrogen throughout the stream channel network, with particular attention to the processes that deliver large nitrogen loads to sensitive coastal ecosystems. We use a dynamic stream transport model to assess biogeochemical (nitrate loadings, concentration, temperature) and hydrological (discharge, depth, velocity) effects on reach-scale denitrification and nitrate removal in the river networks of two watersheds having widely differing levels of nitrate enrichment but nearly identical discharges. Stream denitrification is estimated by regression as a nonlinear function of nitrate concentration, streamflow, and temperature, using more than 300 published measurements from a variety of US streams. These relations are used in the stream transport model to characterize nitrate dynamics related to denitrification at a monthly time scale in the stream reaches of the two watersheds. Results indicate that the nitrate removal efficiency of streams, as measured by the percentage of the stream nitrate flux removed via denitrification per unit length of channel, is appreciably reduced during months with high discharge and nitrate flux and increases during months of low-discharge and flux. Biogeochemical factors, including land use, nitrate inputs, and stream concentrations, are a major control on reach-scale denitrification, evidenced by the disproportionately lower nitrate removal efficiency in streams of the highly nitrate-enriched watershed as compared with that in similarly sized streams in the less nitrate-enriched watershed. Sensitivity analyses reveal that these important biogeochemical factors and physical hydrological factors contribute nearly

Computerized map-based information management system for natural resource management

Energy Technology Data Exchange (ETDEWEB)

Miller, K.

1995-12-01

Federal agencies, states and resource managers have control and stewardship responsibility over a significant inventory of natural resources. A number of federal regulations require the review, protection and preservation of natural resource protection. Examples of such actions include the reauthorization of the Clean Water Act and the modification of the National Contingency Plan to incorporate the requirements of the Oil Pollution Act of 1990. To successfully preserve conserve and restore natural resources on federal reservations, and state and private lands, and to comply with Federal regulations designed to protect natural resources located on their sites, and the type of information on these resources required by environmental regulations. This paper presents an approach using a computerized, graphical information management system to catalogue and track data for the management of natural resources under Federal and state regulations, and for promoting resource conservation, preservation and restoration. The system is designed for use by Federal facility resource managers both for the day-to-day management of resources under their control, and for the longer-term management of larger initiatives, including restoration of significant or endangered resources, participation in regional stewardship efforts, and general ecosystem management. The system will be valuable for conducting natural resource baseline inventories an implementing resource management plans on lands other than those controlled by the Federal government as well. The system can provide a method for coordinating the type of natural resource information required by major federal environmental regulations--thereby providing a cost-effective means for managing natural resource information.

Implications of a More Comprehensive Nitrogen Cycle in a Global Biogeochemical Ocean Model

Science.gov (United States)

Six, K. D.; Ilyina, T.

2016-02-01

Nitrogen plays a crucial role for nearly all living organisms in the Earth system. Changes in the marine nitrogen cycle not only alter the marine biota, but will also have an impact on the marine carbon cycle and, in turn, on climate due to the close coupling of the carbon-nitrogen cycle. The understanding of processes and controls of the marine nitrogen cycle is therefore a prerequisite to reduce uncertainties in the prediction of future climate. Nevertheless, most ocean biogeochemical components of modern Earth system models have a rather simplistic representation of marine N-cycle mainly focusing on nitrate. Here we present results of the HAMburg Ocean Carbon Cycle model (HAMOCC) as part of the MPI-ESM which was extended by a prognostic representation of ammonium and nitrite to resolve important processes of the marine N-cycle such as nitrification and anaerobic ammonium oxidation (anammox). Additionally, we updated the production of nitrous oxide, an important greenhouse gas, allowing for two sources from oxidation of ammonium (nitrification) and from reduction of nitrite (nitrifier-denitrification) at low oxygen concentrations. Besides an extended model data comparison we discuss the following aspects of the N-cycle by model means: (1) contribution of anammox to the loss of fixed nitrogen, and (2) production and emission of marine nitrous oxide.

Structure of peat soils and implications for biogeochemical processes and hydrological flow

Science.gov (United States)

Rezanezhad, F.; McCarter, C. P. R.; Gharedaghloo, B.; Kleimeier, C.; Milojevic, T.; Liu, H.; Weber, T. K. D.; Price, J. S.; Quinton, W. L.; Lenartz, B.; Van Cappellen, P.

2017-12-01

Permafrost peatlands contain globally important amounts of soil organic carbon and play major roles in global water, nutrient and biogeochemical cycles. The structure of peatland soils (i.e., peat) are highly complex with unique physical and hydraulic properties; where significant, and only partially reversible, shrinkage occurs during dewatering (including water table fluctuations), compression and/or decomposition. These distinct physical and hydraulic properties controls water flow, which in turn affect reactive and non-reactive solute transport (such as, sorption or degradation) and biogeochemical functions. Additionally, peat further attenuates solute migration through molecular diffusion into the inactive pores of Sphagnum dominated peat. These slow, diffusion-limited solute exchanges between the pore regions may give rise to pore-scale chemical gradients and heterogeneous distributions of microbial habitats and activity in peat soils. Permafrost peat plateaus have the same essential subsurface characteristics as other widely organic soil-covered peatlands, where the hydraulic conductivity is related to the degree of decomposition and soil compression. Increasing levels of decomposition correspond with a reduction of effective pore diameter and consequently restrict water and solute flow (by several orders of magnitude in hydraulic conductivity between the ground surface and a depth of 50 cm). In this presentation, we present the current knowledge of key physical and hydraulic properties related to the structure of globally available peat soils and discuss their implications for water storage, flow and the migration of solutes.

Natural and accelerated bioremediation research program plan

Energy Technology Data Exchange (ETDEWEB)

NONE

1995-09-01

This draft plan describes a ten-year program to develop the scientific understanding needed to harness and develop natural and enhanced biogeochemical processes to bioremediate contaminated soils, sediments and groundwater at DOE facilities. The Office of Health and Environmental Research (OHER) developed this program plan, with advice and assistance from DOE`s Office of Environmental Management (EM). The program builds on OHER`s tradition of sponsoring fundamental research in the life and environmental sciences and was motivated by OHER`s and Office of Energy Research`s (OER`s) commitment to supporting DOE`s environmental management mission and the belief that bioremediation is an important part of the solution to DOE`s environmental problems.

Development of a natural Gas Systems Analysis Model (GSAM)

International Nuclear Information System (INIS)

Godec, M.; Haas, M.; Pepper, W.; Rose, J.

1993-01-01

Recent dramatic changes in natural gas markets have significant implications for the scope and direction of DOE's upstream as well as downstream natural gas R ampersand D. Open access transportation changes the way gas is bought and sold. The end of the gas deliverability surplus requires increased reserve development above recent levels. Increased gas demand for power generation and other new uses changes the overall demand picture in terms of volumes, locations and seasonality. DOE's Natural Gas Strategic Plan requires that its R ampersand D activities be evaluated for their ability to provide adequate supplies of reasonably priced gas. Potential R ampersand D projects are to be evaluated using a full fuel cycle, benefit-cost approach to estimate likely market impact as well as technical success. To assure R ampersand D projects are evaluated on a comparable basis, METC has undertaken the development of a comprehensive natural gas technology evaluation framework. Existing energy systems models lack the level of detail required to estimate the impact of specific upstream natural gas technologies across the known range of geological settings and likely market conditions. Gas Systems Analysis Model (GSAM) research during FY 1993 developed and implemented this comprehensive, consistent natural gas system evaluation framework. Rather than a isolated research activity, however, GSAM represents the integration of many prior and ongoing natural gas research efforts. When complete, it will incorporate the most current resource base description, reservoir modeling, technology characterization and other geologic and engineering aspects developed through recent METC and industry gas R ampersand D programs

Natural Resources Information System for the State of Oklahoma

International Nuclear Information System (INIS)

Mankin, C.J.

1992-01-01

The objective of this research program was to continue developing, editing, maintaining, utilizing and making publicly available the Natural Resources Information System (NRIS) for the State of Oklahoma. The Oklahoma Geological Survey, working with Geological Information Systems at the University of Oklahoma's Sarkeys Energy Center, undertook to construct this information system in response to the need for a computerized, centrally located library containing accurate, detailed information on the state's natural resources. Particular emphasis during this phase of development was placed on computerizing information related to the energy needs of the nation, specifically oil and gas

Biogeochemical processes and buffering capacity concurrently affect acidification in a seasonally hypoxic coastal marine basin

Science.gov (United States)

Hagens, M.; Slomp, C. P.; Meysman, F. J. R.; Seitaj, D.; Harlay, J.; Borges, A. V.; Middelburg, J. J.

2015-03-01

Coastal areas are impacted by multiple natural and anthropogenic processes and experience stronger pH fluctuations than the open ocean. These variations can weaken or intensify the ocean acidification signal induced by increasing atmospheric pCO2. The development of eutrophication-induced hypoxia intensifies coastal acidification, since the CO2 produced during respiration decreases the buffering capacity in any hypoxic bottom water. To assess the combined ecosystem impacts of acidification and hypoxia, we quantified the seasonal variation in pH and oxygen dynamics in the water column of a seasonally stratified coastal basin (Lake Grevelingen, the Netherlands). Monthly water-column chemistry measurements were complemented with estimates of primary production and respiration using O2 light-dark incubations, in addition to sediment-water fluxes of dissolved inorganic carbon (DIC) and total alkalinity (TA). The resulting data set was used to set up a proton budget on a seasonal scale. Temperature-induced seasonal stratification combined with a high community respiration was responsible for the depletion of oxygen in the bottom water in summer. The surface water showed strong seasonal variation in process rates (primary production, CO2 air-sea exchange), but relatively small seasonal pH fluctuations (0.46 units on the total hydrogen ion scale). In contrast, the bottom water showed less seasonality in biogeochemical rates (respiration, sediment-water exchange), but stronger pH fluctuations (0.60 units). This marked difference in pH dynamics could be attributed to a substantial reduction in the acid-base buffering capacity of the hypoxic bottom water in the summer period. Our results highlight the importance of acid-base buffering in the pH dynamics of coastal systems and illustrate the increasing vulnerability of hypoxic, CO2-rich waters to any acidifying process.

Natural Resource Information System. Volume 2: System operating procedures and instructions

Science.gov (United States)

1972-01-01

A total computer software system description is provided for the prototype Natural Resource Information System designed to store, process, and display data of maximum usefulness to land management decision making. Program modules are described, as are the computer file design, file updating methods, digitizing process, and paper tape conversion to magnetic tape. Operating instructions for the system, data output, printed output, and graphic output are also discussed.

Designing Service-Oriented Chatbot Systems Using a Construction Grammar-Driven Natural Language Generation System

OpenAIRE

Jenkins, Marie-Claire

2011-01-01

Service oriented chatbot systems are used to inform users in a conversational manner about a particular service or product on a website. Our research shows that current systems are time consuming to build and not very accurate or satisfying to users. We find that natural language understanding and natural language generation methods are central to creating an e�fficient and useful system. In this thesis we investigate current and past methods in this research area and place particular emph...

Hyporheic flow and transport processes: mechanisms, models, and biogeochemical implications

Science.gov (United States)

Boano, Fulvio; Harvey, Judson W.; Marion, Andrea; Packman, Aaron I.; Revelli, Roberto; Ridolfi, Luca; Anders, Wörman

2014-01-01

Fifty years of hyporheic zone research have shown the important role played by the hyporheic zone as an interface between groundwater and surface waters. However, it is only in the last two decades that what began as an empirical science has become a mechanistic science devoted to modeling studies of the complex fluid dynamical and biogeochemical mechanisms occurring in the hyporheic zone. These efforts have led to the picture of surface-subsurface water interactions as regulators of the form and function of fluvial ecosystems. Rather than being isolated systems, surface water bodies continuously interact with the subsurface. Exploration of hyporheic zone processes has led to a new appreciation of their wide reaching consequences for water quality and stream ecology. Modern research aims toward a unified approach, in which processes occurring in the hyporheic zone are key elements for the appreciation, management, and restoration of the whole river environment. In this unifying context, this review summarizes results from modeling studies and field observations about flow and transport processes in the hyporheic zone and describes the theories proposed in hydrology and fluid dynamics developed to quantitatively model and predict the hyporheic transport of water, heat, and dissolved and suspended compounds from sediment grain scale up to the watershed scale. The implications of these processes for stream biogeochemistry and ecology are also discussed."

New pre-heating system for natural gas pressure regulating stations

International Nuclear Information System (INIS)

Zullo, G.; Vertuani, C.; Borghesani, O.; Vignoli, F.

1999-01-01

Costs for running natural gas pressure regulating stations are mainly due to operation and maintenance of a natural gas preheating system, usually equipment with a hot water boiler or an armour-plated electric resistance immersed in a fluid. The article describe a system, considering a natural circulation boiler which uses steam/condensate (at 100 degrees C and 0,5 bar) as a thermal conductor, in thermodynamic balance and in absence of un condensable. This new boiler, already operating with satisfactory results in heating system for industrial buildings, does not require testing, notifications, periodical inspections by the competent authorities, constant monitoring by trained or patented staff. Besides, it allows easier installations procedures and running cost savings. The system, to be considered as static because it has no moving parts, is a good alternative to conventional forced hot water circulation or electric heating system [it

Comparative study of potential transfer of natural and anthropogenic cadmium to plankton communities in the North-West African upwelling

Energy Technology Data Exchange (ETDEWEB)

Auger, P.A., E-mail: pierreamael.auger@gmail.com [Laboratoire de Physique des Océans (LPO), UMR-CNRS 6523/IFREMER/IRD/UBO, BP70, 29280 Plouzané (France); Machu, E.; Gorgues, T.; Grima, N. [Laboratoire de Physique des Océans (LPO), UMR-CNRS 6523/IFREMER/IRD/UBO, BP70, 29280 Plouzané (France); Waeles, M. [Université de Bretagne Occidentale (UBO), Laboratoire de l' Environnement Marin (LEMAR), UMR-CNRS 6539/IRD/UBO, place N. Copernic, 29280 Plouzané (France)

2015-02-01

A Lagrangian approach based on a physical–biogeochemical modeling was used to compare the potential transfer of cadmium (Cd) from natural and anthropogenic sources to plankton communities (Cd-uptake) in the North-West African upwelling. In this region, coastal upwelling was estimated to be the main natural source of Cd while the most significant anthropogenic source for marine ecosystem is provided by phosphate industry. In our model experiment, Cd-uptake (natural or anthropogenic) in the North-West African upwelling is the result of an interplay between the Cd dispersion (by advection processes) and the simulated biological productivity. In the Moroccan waters, advection processes limit the residence time of water masses resulting in a low natural Cd-uptake by plankton communities while anthropogenic Cd-uptake is high. As expected, the situation is reversed in the Senegalo-Mauritanian upwelling where natural Cd-uptake is higher than anthropogenic Cd-uptake. Based upon an estimate of Cd sources, our modeling study shows, unexpectedly, that the anthropogenic signal of potential Cd-bioaccumulation in the Moroccan upwelling is of the same order of magnitude as the natural signal mainly present in the Senegalo-Mauritanian upwelling region. A comparison with observed Cd levels in mollusk and fishes, which shows overall agreement with our simulations, is confirming our estimates. - Highlights: • We model the physical–biogeochemical dynamics in the North-West African upwelling. • We model the transport of cadmium from natural and anthropogenic sources. • We derive proxies of potential cadmium absorption and bioaccumulation in the plankton food chain. • The anthropogenic signal off Morocco at least equals the natural upwelling signal off Mauritania. • We compare our results with observed cadmium levels in mollusks and fishes.

Comparative study of potential transfer of natural and anthropogenic cadmium to plankton communities in the North-West African upwelling

International Nuclear Information System (INIS)

Auger, P.A.; Machu, E.; Gorgues, T.; Grima, N.; Waeles, M.

2015-01-01

A Lagrangian approach based on a physical–biogeochemical modeling was used to compare the potential transfer of cadmium (Cd) from natural and anthropogenic sources to plankton communities (Cd-uptake) in the North-West African upwelling. In this region, coastal upwelling was estimated to be the main natural source of Cd while the most significant anthropogenic source for marine ecosystem is provided by phosphate industry. In our model experiment, Cd-uptake (natural or anthropogenic) in the North-West African upwelling is the result of an interplay between the Cd dispersion (by advection processes) and the simulated biological productivity. In the Moroccan waters, advection processes limit the residence time of water masses resulting in a low natural Cd-uptake by plankton communities while anthropogenic Cd-uptake is high. As expected, the situation is reversed in the Senegalo-Mauritanian upwelling where natural Cd-uptake is higher than anthropogenic Cd-uptake. Based upon an estimate of Cd sources, our modeling study shows, unexpectedly, that the anthropogenic signal of potential Cd-bioaccumulation in the Moroccan upwelling is of the same order of magnitude as the natural signal mainly present in the Senegalo-Mauritanian upwelling region. A comparison with observed Cd levels in mollusk and fishes, which shows overall agreement with our simulations, is confirming our estimates. - Highlights: • We model the physical–biogeochemical dynamics in the North-West African upwelling. • We model the transport of cadmium from natural and anthropogenic sources. • We derive proxies of potential cadmium absorption and bioaccumulation in the plankton food chain. • The anthropogenic signal off Morocco at least equals the natural upwelling signal off Mauritania. • We compare our results with observed cadmium levels in mollusks and fishes

Soil Properties and Plant Biomass Production in Natural Rangeland Management Systems

Directory of Open Access Journals (Sweden)

Romeu de Souza Werner

Full Text Available ABSTRACT Improper management of rangelands can cause land degradation and reduce the economic efficiency of livestock activity. The aim of this study was to evaluate soil properties and quantify plant biomass production in four natural rangeland management systems in the Santa Catarina Plateau (Planalto Catarinense of Brazil. The treatments, which included mowed natural rangeland (NR, burned natural rangeland (BR, natural rangeland improved through the introduction of plant species after harrowing (IH, and natural rangeland improved through the introduction of plant species after chisel plowing (IC, were evaluated in a Nitossolo Bruno (Nitisol. In the improved treatments, soil acidity was corrected, phosphate fertilizer was applied, and intercropped annual ryegrass (Lolium multiflorum, velvet grass (Holcus lanatus, and white clover (Trifolium repens were sown. Management systems with harrowed or chisel plowed soil showed improved soil physical properties; however, the effect decreased over time and values approached those of burned and mowed natural rangelands. Natural rangeland systems in the establishment phase had little influence on soil organic C. The mowed natural rangeland and improved natural rangeland exhibited greater production of grazing material, while burning the field decreased production and increased the proportion of weeds. Improvement of the natural rangelands increased leguminous biomass for pasture.

Biogeochemical studies of wintering waterfowl in the Imperial and Sacramento Valleys

Energy Technology Data Exchange (ETDEWEB)

Koranda, J.J.; Stuart, M.; Thompson, S.; Conrado, C.

1979-10-01

Trace and major elemental composition were determined in the organs of wintering waterfowl in the Imperial and Sacramento Valleys of California, and in soils, sediments, and agricultural fertilizer that constitute the various sources of elements in the waterfowl. These data provide a biogeochemical baseline for waterfowl populations wintering in an area being developed for geothermal power. This baseline in the Imperial Valley is affected by soil and sediment composition, agricultural effluents in irrigation and stream water, and spent shot deposited by hunters in waterfowl habitats. The waterfowl acquire a set of trace elements from these sources and concentrations increase in their organs over the wintering period. Nickel, arsenic, selenium, bromine, and lead are the primary elements acquired from soil sources, agricultural effluents, and spent shot in the Imperial Valley. The assessment of effects from geothermal effluents on waterfowl populations in complex because there are large influxes of materials into the Imperial Valley ecosystem that contain trace elements, i.e., irrigation water, phosphatic fertilizers, pesticides, and lead shot. Multiple sources exist for many elements prominent in the expected geothermal effluents. The relationships between the two California valleys, the Imperial and Sacramento, are apparent in the trace element concentrations in the organs of waterfowl obtained in those two valleys. Arsenic is absent in the waterfowl organs obtained in the Sacramento Valley and relatively common in the Imperial Valley waterfowl. The effect of any release of geothermal effluent in the Imperial Valley waterfowl habitats will be difficult to describe because of the complexity of the biogeochemical baseline and the multiple sources of trace and major elements in the ecosystem.

System and method for producing substitute natural gas from coal

Science.gov (United States)

Hobbs, Raymond [Avondale, AZ

2012-08-07

The present invention provides a system and method for producing substitute natural gas and electricity, while mitigating production of any greenhouse gasses. The system includes a hydrogasification reactor, to form a gas stream including natural gas and a char stream, and an oxygen burner to combust the char material to form carbon oxides. The system also includes an algae farm to convert the carbon oxides to hydrocarbon material and oxygen.

Logistical management system for natural gas distribution; Sistema de gestao logistica para a distribuicao de gas natural

Energy Technology Data Exchange (ETDEWEB)

Arruda, Joao Bosco F; Nobre, Junior, Ernesto F; Praca, Eduardo R [Universidade Federal do Ceara (UFC), Fortaleza, CE (Brazil). Nucleo de Pesquisa em Logistica, Transportes e Desenvolvimento

2004-07-01

The Brazilian Federal Government has the very purpose of increasing the participation of the Natural Gas in the primary energy internal supply from 7,5% nowadays to about 12% till 2010. However, for that, it is necessary to eliminate the great impedance represented by the restricted accessibility to the product, due to the high distribution costs involved. So, there is an urgent need for availability of technologies to help natural gas distribution systems. This paper proposes an innovative logistics-based approach on the subject of the natural gas distribution, through a computational tool (GASLOG System) to be applied in the North and Northeastern urban and country areas of Brazil, with initial case study in the city of Fortaleza. In its conception, the GASLOG System focuses on the point-of-view of everyone of the actors involved with the natural gas distribution process trying to respond their particular necessities in the sector. (author)

Plutonium - its behavior in natural-water systems and assimilation by man

International Nuclear Information System (INIS)

Larsen, R.P.; Nelson, D.M.; Bhattacharyya, M.H.; Oldham, R.D.

1981-01-01

There are a number of factors which must be considered in establishing whether or not the inadvertent intrusion of a sizable amount of plutonium-bearing material into a natural-water system may have a significant impact on the health of those individuals who use that system as a drinking-water resource. These factors include the chemical form(s) and solubility of plutonium in natural waters, its behavior in relation to natural processes (geochemical and biological), its fate in water-treatment systems, and its uptake by man from drinking water. From the results obtained of the behavior in natural-water systems, it appears that (1) the chemical forms of plutonium dissolved in natural waters are Pu(IV) and Pu(V), (2) the soluble plutonium in many waters is bound to the organic constituents which probably enhance plutonium solubility, (3) the natural process responsible for the removal of plutonium from water is adsorption onto sediments, and (4) in water-treatment systems, soluble plutonium is oxidized to the VI state and this form is not removed. From investigations of gastrointestinal absorption, it appears that the value for f 1 , the fraction transferred from the gut to blood, is greater than 1 x 10 - 3 and may be as high as 2 x 10 - 1

Biogeochemical typing of paddy field by a data-driven approach revealing sub-systems within a complex environment--a pipeline to filtrate, organize and frame massive dataset from multi-omics analyses.

Directory of Open Access Journals (Sweden)

Diogo M O Ogawa

Full Text Available We propose the technique of biogeochemical typing (BGC typing as a novel methodology to set forth the sub-systems of organismal communities associated to the correlated chemical profiles working within a larger complex environment. Given the intricate characteristic of both organismal and chemical consortia inherent to the nature, many environmental studies employ the holistic approach of multi-omics analyses undermining as much information as possible. Due to the massive amount of data produced applying multi-omics analyses, the results are hard to visualize and to process. The BGC typing analysis is a pipeline built using integrative statistical analysis that can treat such huge datasets filtering, organizing and framing the information based on the strength of the various mutual trends of the organismal and chemical fluctuations occurring simultaneously in the environment. To test our technique of BGC typing, we choose a rich environment abounding in chemical nutrients and organismal diversity: the surficial freshwater from Japanese paddy fields and surrounding waters. To identify the community consortia profile we employed metagenomics as high throughput sequencing (HTS for the fragments amplified from Archaea rRNA, universal 16S rRNA and 18S rRNA; to assess the elemental content we employed ionomics by inductively coupled plasma optical emission spectroscopy (ICP-OES; and for the organic chemical profile, metabolomics employing both Fourier transformed infrared (FT-IR spectroscopy and proton nuclear magnetic resonance (1H-NMR all these analyses comprised our multi-omics dataset. The similar trends between the community consortia against the chemical profiles were connected through correlation. The result was then filtered, organized and framed according to correlation strengths and peculiarities. The output gave us four BGC types displaying uniqueness in community and chemical distribution, diversity and richness. We conclude therefore that

PRELIMINARY BIOGEOCHEMICAL DATA ON MICROBIAL CARBONATOGENESIS IN ANCIENT EXTREME ENVIRONMENTS (KESS-KESS MOUNDS, MOROCCO

Directory of Open Access Journals (Sweden)

ADRIANO GUIDO

2013-03-01

Full Text Available The Devonian Kess-Kess mounds, cropping out in the Hamar Laghdad Ridge (SE Morocco, provide a useful case-study for understanding the relationships between the microbial metabolic activities and micrite precipitation in an extreme environment. Very fine dark and white wrinkled laminae record microbial activity and the geochemistry of the organic matter allows the  characterization of the source organisms. The biogeochemical characterization of extracted organic matter was performed through the functional group analyses by FT-IR Spectroscopy. FT-IR parameters indicate a marine origin and low thermal evolution for the organic material. The organic matter is characterized by the presence of stretching ?C=C vibrations attributable to alkene and/or unsaturated carboxylic acids. Preliminary analysis with GC-MS provides evidence for an autochthonous (biogeochemical signatures of microbial carbonate precipitation in an ancient extreme environment may have implications in astrobiological research considering the recent discovery of carbonate deposits on Mars. 

The Biogeochemical Response to Inter-decadal Atmospheric Forcing Across Watershed Scales in Canada's Subarctic

Science.gov (United States)

Spence, C.

2016-12-01

Rapid landscape changes in the circumpolar north have been documented, including degradation of permafrost and alteration of vegetation communities. These are widely expected to have profound impacts on the freshwater fluxes of solutes, carbon and nitrogen across the Arctic domain. However, there have been few attempts to document trends across the diversity of landscapes in the circumpolar north, mostly due to a dearth of long term data. Some of the fastest rates of warming over the last thirty years have occurred in Canada's Northwest Territories, so this region should already exhibit changes in aquatic chemistry. Observations of chemical loads in streams draining the ice-poor discontinuous permafrost subarctic Canadian Shield region were analyzed with the goal of determining how basins across scales have responded to changes in atmospheric forcing. Smaller streams, with much closer linkages to terrestrial processes, experienced a synchrony among hydrological and biogeochemical processes that enhanced chemical flux above that in their larger counterparts. This demonstrates that there are differences in resiliency and resistance across scales to climate change. These results highlight the importance of biogeochemical process understanding to properly explain and predict how chemical loading scales from headwaters to river mouths. This is important information if society is to properly adapt policies for effluent discharge, nearshore marine management, among others.

Didymosphenia geminata invasion in South America: Ecosystem impacts and potential biogeochemical state change in Patagonian rivers

Science.gov (United States)

Reid, Brian; Torres, Rodrigo

2014-01-01

The diatom Didymosphenia geminata has emerged as a major global concern, as both an aggressive invader of rivers and streams in the southern hemisphere, and for its ability to form nuisance blooms in oligotrophic systems in its native range. South American D. geminata blooms were first documented in Chilean Patagonia in May 2010, and have spread to over five regions and three provinces, in Chile and Argentina respectively. The Patagonian invasion represents a distinct challenge compared to other regions; not only are affected systems poorly characterized, but also a general synthesis of the nature and magnitude of ecosystem impacts is still lacking. The latter is essential in evaluating impacts to ecosystem services, forms the basis for a management response that is proportional to the potentially valid threats, or aids in the determination of whether action is warranted or feasible. Based on a revision of the recent literature, some of the most significant impacts may be mediated through physical changes: substantially increased algal biomass, trapping of fine sediment, altered hydrodynamics, and consequent effects on biogeochemical states and processes such as redox condition, pH and nutrient cycling in the benthic zone. Surveys conducted during the early invasion in Chile show a strong correlation between benthic biomass and associated fine sediments, both of which were one-two orders of magnitude higher within D. geminata blooms. Experimental phosphorous amendments showed significant abiotic uptake, while interstitial water in D. geminata mats had nearly 10-20 fold higher soluble reactive phosphorous and a pronounced pH cycle compared to the water column. A dominant and aggressive stalk-forming diatom with this combination of characteristics is in sharp contrast to the colonial cyanobacteria and bare gravel substrate that characterize many Patagonian streams. The potential displacement of native benthic algal communities with contrasting functional groups

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

Science.gov (United States)

Jin, J.; Zimmerman, A. R.

2010-12-01

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

Biogeochemical Research Priorities for Sustainable Biofuel and Bioenergy Feedstock Production in the Americas.

Science.gov (United States)

Gollany, Hero T; Titus, Brian D; Scott, D Andrew; Asbjornsen, Heidi; Resh, Sigrid C; Chimner, Rodney A; Kaczmarek, Donald J; Leite, Luiz F C; Ferreira, Ana C C; Rod, Kenton A; Hilbert, Jorge; Galdos, Marcelo V; Cisz, Michelle E

2015-12-01

Rapid expansion in biomass production for biofuels and bioenergy in the Americas is increasing demand on the ecosystem resources required to sustain soil and site productivity. We review the current state of knowledge and highlight gaps in research on biogeochemical processes and ecosystem sustainability related to biomass production. Biomass production systems incrementally remove greater quantities of organic matter, which in turn affects soil organic matter and associated carbon and nutrient storage (and hence long-term soil productivity) and off-site impacts. While these consequences have been extensively studied for some crops and sites, the ongoing and impending impacts of biomass removal require management strategies for ensuring that soil properties and functions are sustained for all combinations of crops, soils, sites, climates, and management systems, and that impacts of biomass management (including off-site impacts) are environmentally acceptable. In a changing global environment, knowledge of cumulative impacts will also become increasingly important. Long-term experiments are essential for key crops, soils, and management systems because short-term results do not necessarily reflect long-term impacts, although improved modeling capability may help to predict these impacts. Identification and validation of soil sustainability indicators for both site prescriptions and spatial applications would better inform commercial and policy decisions. In an increasingly inter-related but constrained global context, researchers should engage across inter-disciplinary, inter-agency, and international lines to better ensure the long-term soil productivity across a range of scales, from site to landscape.

System reliability analysis with natural language and expert's subjectivity

International Nuclear Information System (INIS)

Onisawa, T.

1996-01-01

This paper introduces natural language expressions and expert's subjectivity to system reliability analysis. To this end, this paper defines a subjective measure of reliability and presents the method of the system reliability analysis using the measure. The subjective measure of reliability corresponds to natural language expressions of reliability estimation, which is represented by a fuzzy set defined on [0,1]. The presented method deals with the dependence among subsystems and employs parametrized operations of subjective measures of reliability which can reflect expert 's subjectivity towards the analyzed system. The analysis results are also expressed by linguistic terms. Finally this paper gives an example of the system reliability analysis by the presented method

Novel imaging techniques, integrated with mineralogical, geochemical and microbiological characterizations to determine the biogeochemical controls on technetium mobility in FRC sediments. Final report

International Nuclear Information System (INIS)

Lloyd, Jonathan R.

2009-01-01

mobility was monitored using a γ-camera. Incorporation of low concentrations of the long-lived 99Tc gave a tracer that can be followed by scintillation counting, should the metastable form of the radionuclide decay to below detection limits before the end of the experiment (complete immobilization or loss of the Tc from the column). After the Tc was reduced and immobilized, or passed through the system, the columns were dismantled carefully in an anaerobic cabinet and the pore water geochemistry and mineralogy of the columns profiled. Microbial community analysis was determined, again using molecular and culture-dependent techniques. Experimental results were also modeled using an established coupled speciation and transport code, to develop a predictive tool for the mobility of Tc in FRC sediments. From this multidisciplinary approach, we hoped to obtain detailed information on the microorganisms that control the biogeochemical cycling of key elements at the FRC, and we would also be able to determine the key factors that control the mobility of Tc at environmentally relevant concentrations at this site.

The Nature of Stability in Replicating Systems

Directory of Open Access Journals (Sweden)

Addy Pross

2011-02-01

Full Text Available We review the concept of dynamic kinetic stability, a type of stability associated specifically with replicating entities, and show how it differs from the well-known and established (static kinetic and thermodynamic stabilities associated with regular chemical systems. In the process we demonstrate how the concept can help bridge the conceptual chasm that continues to separate the physical and biological sciences by relating the nature of stability in the animate and inanimate worlds, and by providing additional insights into the physicochemical nature of abiogenesis.

Small Moves, NUI. Small Moves: Beginning to Investigate Biogeochemical Exchange From the Seafloor to the Exterior of an Ice-Covered Ocean

Science.gov (United States)

German, C. R.; Boetius, A.

2017-12-01

We present results from two recent cruises, using the new Nereid Under Ice (NUI) vehicle aboard the FS Polarstern, in which we investigated biogeochemical fluxes from the deep seafloor of the Gakkel Ridge, an ultraslow spreading ridge that spans the ice-covered Arctic Ocean, and the mechanisms by which biogeochemical signals might be transferred from within the underlying ocean to the overlying Arctic ice. The scientific advances for this work progress hand in hand with technological capability. During a first cruise in 2014, our NUI-based investigations focused on photosynthetically-driven biogeochemical cycling in the uppermost water column and how to study such processes using in situ sensing immediately at and beneath the rough topography of the overlying ice-cover. For that work we relied entirely upon human-in-the-loop control of the vehicle via a single optical fiber light tether than provided real-time monitoring and control of the vehicle as it ranged laterally out under the ice up to 1km distant from the ship, conducting physical, geochemical and biological surveys. Instrumentation used for that work included multibeam mapping and imaging (digital still photographs and HD video), in situ spectroscopy to study light transmission through the ice and biogeochemical mapping of the ocean water column using a combination of CTD sensing, fluorometry and an in situ nitrate analyzer. Returning to the Arctic in 2016 we extended our exploration modes with NUI further, investigating for seafloor fluid flow at a shallow setting on the flanks of the Gakkel Ridge where the seabed rises from >4000m to movement of the ship (horizontal displacements of 1km or more) at the ice-covered ocean surface. While the existing NUI vehicle does not map directly to model payloads for future SLS missions to Europa or Enceladus it does provide for important small moves in the right direction.

Influence of harvesting on biogeochemical exchange in sheetflow and soil processes in a eutrophic floodplain forest

Science.gov (United States)

B.G. Lockaby; R.G. Clawson; K. Flynn; Robert Rummer; S. Meadows; B Stokes; John A. Stanturf

1997-01-01

Floodplain forests contribute to the maintenance of water quality as a result of various biogeochemical transformations which occur within them. In particular, they can serve as sinks for nutrient run-off from adjacent uplands or as nutrient transformers as water moves downstream. However, little is known about the potential that land management activities may have for...

Tidal Pumping-Induced Nutrients Dynamics and Biogeochemical Implications in an Intertidal Aquifer

Science.gov (United States)

Liu, Yi; Jiao, Jiu Jimmy; Liang, Wenzhao; Luo, Xin

2017-12-01

Tidal pumping is a major driving force affecting water exchange between land and sea, biogeochemical reactions in the intertidal aquifer, and nutrient loading to the sea. At a sandy beach of Tolo Harbour, Hong Kong, the nutrient (NH4+, NO2-, NO3-, and PO43-) dynamic in coastal groundwater mixing zone (CGMZ) is found to be fluctuated with tidal oscillation. Nutrient dynamic is mainly controlled by tidal pumping-induced organic matter that serves as a reagent of remineralization in the aquifer. NH4+, NO2-, and PO43- are positively correlated with salinity. Both NH4+ and PO43- have negative correlations with oxidation/reduction potential. NH4+ is the major dissolved inorganic nitrogen species in CGMZ. The adsorption of PO43- onto iron oxides occurs at the deep transition zone with a salinity of 5-10 practical salinity unit (psu), and intensive N-loss occurs in near-surface area with a salinity of 10-25 psu. The biogeochemical reactions, producing PO43- and consuming NH4+, are synergistic effect of remineralization-nitrification-denitrification. In CGMZ, the annual NH4+ loss is estimated to be 4.32 × 105 mol, while the minimum annual PO43- production is estimated to be 2.55 × 104 mol. Applying these rates to the entire Tolo Harbour, the annual NH4+ input to the harbor through the remineralization of organic matters is estimated to be 1.02 × 107 mol. The annual NH4+ loss via nitrification is 1.32 × 107 mol, and the annual PO43- production is 7.76 × 105 mol.

75 FR 18607 - Mandatory Reporting of Greenhouse Gases: Petroleum and Natural Gas Systems

Science.gov (United States)

2010-04-12

...: Petroleum and Natural Gas Systems; Proposed Rule #0;#0;Federal Register / Vol. 75 , No. 69 / Monday, April... Natural Gas Systems AGENCY: Environmental Protection Agency (EPA). ACTION: Proposed rule. SUMMARY: EPA is... natural gas systems. Specifically, the proposed supplemental rulemaking would require emissions reporting...

American Indian Systems for Natural Resource Management.

Science.gov (United States)

Quintana, Jorge O.

1992-01-01

Outlines the philosophy and general principles of "primitive" indigenous production technologies and natural resource management systems in North and South America. Discusses indigenous practices that promote sustainable production in gathering, hunting and fishing, minerals extraction, and agriculture. (SV)

Natural frequency extraction of a beam-moving mass system with periodic passages using its pseudo-natural frequencies

Energy Technology Data Exchange (ETDEWEB)

Ghorbani, Esmaeil; Keshmiri, Mehdi [Isfahan University of Technology, Isfahan (Iran, Islamic Republic of)

2016-07-15

Wind turbines, helicopters, and turbo-machineries' rotary motion, along with a variety of nonlinear structures linearized with their periodic limit cycles, may all contain time-periodic terms in their equations of motion even if the equations remain linear. The purpose of this study is to model these systems into a beam-moving mass system. Natural frequencies of the beam are calculated using past work in which pseudo-natural frequencies of a beam-moving mass system were extracted, followed by the homotopy perturbation method. The findings of this study are valuable to the industry, and they decrease error margin in resonance range assessment. This approach indicates that for beam-moving mass systems, extraction of natural frequencies that ignore the moving mass effect can lead to inaccurate results, whereas only a limited amount of physical data are needed obtain accurate calculations. Furthermore, this study used homotopy perturbation for operational modal analysis purposes and not for solving nonlinear equations.

Natural computing for mechanical systems research: A tutorial overview

Science.gov (United States)

Worden, Keith; Staszewski, Wieslaw J.; Hensman, James J.

2011-01-01

A great many computational algorithms developed over the past half-century have been motivated or suggested by biological systems or processes, the most well-known being the artificial neural networks. These algorithms are commonly grouped together under the terms soft or natural computing. A property shared by most natural computing algorithms is that they allow exploration of, or learning from, data. This property has proved extremely valuable in the solution of many diverse problems in science and engineering. The current paper is intended as a tutorial overview of the basic theory of some of the most common methods of natural computing as they are applied in the context of mechanical systems research. The application of some of the main algorithms is illustrated using case studies. The paper also attempts to give some indication as to which of the algorithms emerging now from the machine learning community are likely to be important for mechanical systems research in the future.

Interdependence of the Electricity Generation System and the Natural Gas System and Implications for Energy Security

Science.gov (United States)

2013-05-15

installation of natural gas generation or cogeneration plants to increase their energy security from the typical three days using diesel supplies to weeks-to...better quantify the regional impact of natural gas for energy security. Modeling and simulation could identify those regions and DoD installations that...Interdependence of the Electricity Generation System and the Natural Gas System and Implications for Energy Security N. Judson 15 May 2013 Prepared for the

76 FR 22825 - Mandatory Reporting of Greenhouse Gases: Petroleum and Natural Gas Systems

Science.gov (United States)

2011-04-25

... Reporting of Greenhouse Gases: Petroleum and Natural Gas Systems AGENCY: Environmental Protection Agency... Subpart W: Petroleum and Natural Gas Systems of the Greenhouse Gas Reporting Rule. As part of the... greenhouse gas emissions for the petroleum and natural gas systems source category of the greenhouse gas...

75 FR 74457 - Mandatory Reporting of Greenhouse Gases: Petroleum and Natural Gas Systems

Science.gov (United States)

2010-11-30

...: Petroleum and Natural Gas Systems; Final Rule #0;#0;Federal Register / Vol. 75 , No. 229 / Tuesday, November... Natural Gas Systems AGENCY: Environmental Protection Agency (EPA). ACTION: Final rule. SUMMARY: EPA is... natural gas systems. This action adds this source category to the list of source categories already...

Biogeochemical sensor performance in the SOCCOM profiling float array

Science.gov (United States)

Johnson, Kenneth S.; Plant, Joshua N.; Coletti, Luke J.; Jannasch, Hans W.; Sakamoto, Carole M.; Riser, Stephen C.; Swift, Dana D.; Williams, Nancy L.; Boss, Emmanuel; Haëntjens, Nils; Talley, Lynne D.; Sarmiento, Jorge L.

2017-08-01

The Southern Ocean Carbon and Climate Observations and Modeling (SOCCOM) program has begun deploying a large array of biogeochemical sensors on profiling floats in the Southern Ocean. As of February 2016, 86 floats have been deployed. Here the focus is on 56 floats with quality-controlled and adjusted data that have been in the water at least 6 months. The floats carry oxygen, nitrate, pH, chlorophyll fluorescence, and optical backscatter sensors. The raw data generated by these sensors can suffer from inaccurate initial calibrations and from sensor drift over time. Procedures to correct the data are defined. The initial accuracy of the adjusted concentrations is assessed by comparing the corrected data to laboratory measurements made on samples collected by a hydrographic cast with a rosette sampler at the float deployment station. The long-term accuracy of the corrected data is compared to the GLODAPv2 data set whenever a float made a profile within 20 km of a GLODAPv2 station. Based on these assessments, the fleet average oxygen data are accurate to 1 ± 1%, nitrate to within 0.5 ± 0.5 µmol kg-1, and pH to 0.005 ± 0.007, where the error limit is 1 standard deviation of the fleet data. The bio-optical measurements of chlorophyll fluorescence and optical backscatter are used to estimate chlorophyll a and particulate organic carbon concentration. The particulate organic carbon concentrations inferred from optical backscatter appear accurate to with 35 mg C m-3 or 20%, whichever is larger. Factors affecting the accuracy of the estimated chlorophyll a concentrations are evaluated.Plain Language SummaryThe ocean science community must move toward greater use of autonomous platforms and sensors if we are to extend our knowledge of the effects of climate driven change within the ocean. Essential to this shift in observing strategies is an understanding of the performance that can be obtained from biogeochemical sensors on platforms deployed for years and the

Active geothermal systems as natural analogs of HLW repositories

International Nuclear Information System (INIS)

Elders, W.A.; Williams, A.E.; Cohen, L.H.

1988-01-01

Geologic analogs of long-lived processes in high-level waste (HLW) repositories have been much studied in recent years. However, most of these occurrences either involve natural processes going on today at 25 degree C, or, if they are concerned with behavior at temperatures similar to the peak temperatures anticipated near HLW canisters, have long since ended. This paper points out the usefulness of studying modern geothermal systems as natural analogs, and to illustrate the concept with a dramatic example, the Salton Sea geothermal system (SSGS)

Human Nature and its Implications for the Legal System | Obioha ...

African Journals Online (AJOL)

This paper examines the implications the various conceptions of human nature hold for the legal system. No doubt, there are various and conflicting theories of human nature such that the concept of human nature seems to have remained elusive and pervasive. Some conceive man as nothing but matter pure and simple; ...

Assessing the utility of frequency dependent nudging for reducing biases in biogeochemical models

Science.gov (United States)

Lagman, Karl B.; Fennel, Katja; Thompson, Keith R.; Bianucci, Laura

2014-09-01

Bias errors, resulting from inaccurate boundary and forcing conditions, incorrect model parameterization, etc. are a common problem in environmental models including biogeochemical ocean models. While it is important to correct bias errors wherever possible, it is unlikely that any environmental model will ever be entirely free of such errors. Hence, methods for bias reduction are necessary. A widely used technique for online bias reduction is nudging, where simulated fields are continuously forced toward observations or a climatology. Nudging is robust and easy to implement, but suppresses high-frequency variability and introduces artificial phase shifts. As a solution to this problem Thompson et al. (2006) introduced frequency dependent nudging where nudging occurs only in prescribed frequency bands, typically centered on the mean and the annual cycle. They showed this method to be effective for eddy resolving ocean circulation models. Here we add a stability term to the previous form of frequency dependent nudging which makes the method more robust for non-linear biological models. Then we assess the utility of frequency dependent nudging for biological models by first applying the method to a simple predator-prey model and then to a 1D ocean biogeochemical model. In both cases we only nudge in two frequency bands centered on the mean and the annual cycle, and then assess how well the variability in higher frequency bands is recovered. We evaluate the effectiveness of frequency dependent nudging in comparison to conventional nudging and find significant improvements with the former.

Effects of acid deposition on microbial processes in natural waters

International Nuclear Information System (INIS)

Gilmour, C.C.

1992-01-01

Biogeochemical processes mediated by microorganisms are not adversely affected by the acidification of natural waters to the same extent as are the life cycles of higher organisms. Basic processes, e.g., primary production and organic matter decomposition, are not slowed in moderately acidified systems and do not generally decline above a pH of 5. More specifically, the individual components of the carbon, nitrogen, and sulfur cycles are, with few exceptions, also acid resistant. The influence of acid deposition on microbial processes is more often stimulation of nitrogen and sulfur cycling, often leading to alkalinity production, which mitigates the effect of strong acid deposition. Bacterial sulfate reduction and denitrification in sediments are two of the major processes that can be stimulated by sulfate and nitrate deposition, respectively, and result in ANC (acid-neutralizing capacity) generation. One of the negative effects of acid deposition is increased mobilization and bioaccumulation of some metals. Bacteria appear to play an important role, especially in mercury cycling, with acidification leading to increased bacterial methylation of mercury and subsequent bioaccumulation in higher organisms

Biogeochemical studies of technetium in marine and estuarine ecosystems. Progress report, 1 July 1980-31 July 1981

International Nuclear Information System (INIS)

Beasley, T.M.

1981-01-01

This report summarizes progress from July 1980 through July 1981 on studies dealing with the biogeochemical behavior of technetium in marine and estuarine ecosystems. While the duration of the research has been slightly over two years, the results of our experiments have substantially extended our understanding of the environmental behavior of Tc

Nuclear processes in deuterium/natural hydrogen-metal systems

International Nuclear Information System (INIS)

Zelensky, V.F.

2013-01-01

The survey presents the analysis of the phenomena taking place in deuterium - metal and natural hydrogen - metal systems under cold fusion experimental conditions. The cold fusion experiments have shown that the generation of heat and helium in the deuterium-metal system without emission of energetic gamma-quanta is the result of occurrence of a chain of chemical, physical and nuclear processes observed in the system, culminating in both the fusion of deuterium nuclei and the formation of a virtual, electron-modified excited 4He nucleus. The excitation energy of the helium nucleus is transferred to the matrix through emission of conversion electrons, and that, under appropriate conditions, provides a persistent synthesis of deuterium. The processes occurring in the deuterium/natural hydrogen - metal systems have come to be known as chemonuclear DD- and HD-fusion. The mechanism of stimulation of weak interaction reactions under chemonuclear deuterium fusion conditions by means of strong interaction reactions has been proposed. The results of numerous experiments discussed in the survey bear witness to the validity of chemonuclear fusion. From the facts discussed it is concluded that the chemonuclear deuterium fusion scenario as presented in this paper may serve as a basis for expansion of deeper research and development of this ecologically clean energy source. It is shown that the natural hydrogen-based system, containing 0.015% of deuterium, also has good prospects as an energy source. The chemonuclear fusion processes do not require going beyond the scope of traditional physics for their explanation

Reconstructing disturbances and their biogeochemical consequences over multiple timescales

Science.gov (United States)

McLauchlan, Kendra K.; Higuera, Philip E.; Gavin, Daniel G.; Perakis, Steven S.; Mack, Michelle C.; Alexander, Heather; Battles, John; Biondi, Franco; Buma, Brian; Colombaroli, Daniele; Enders, Sara K.; Engstrom, Daniel R.; Hu, Feng Sheng; Marlon, Jennifer R.; Marshall, John; McGlone, Matt; Morris, Jesse L.; Nave, Lucas E.; Shuman, Bryan; Smithwick, Erica A.H.; Urrego, Dunia H.; Wardle, David A.; Williams, Christopher J.; Williams, Joseph J.

2014-01-01

Ongoing changes in disturbance regimes are predicted to cause acute changes in ecosystem structure and function in the coming decades, but many aspects of these predictions are uncertain. A key challenge is to improve the predictability of postdisturbance biogeochemical trajectories at the ecosystem level. Ecosystem ecologists and paleoecologists have generated complementary data sets about disturbance (type, severity, frequency) and ecosystem response (net primary productivity, nutrient cycling) spanning decadal to millennial timescales. Here, we take the first steps toward a full integration of these data sets by reviewing how disturbances are reconstructed using dendrochronological and sedimentary archives and by summarizing the conceptual frameworks for carbon, nitrogen, and hydrologic responses to disturbances. Key research priorities include further development of paleoecological techniques that reconstruct both disturbances and terrestrial ecosystem dynamics. In addition, mechanistic detail from disturbance experiments, long-term observations, and chronosequences can help increase the understanding of ecosystem resilience.

Introducing mixotrophy into a biogeochemical model describing an eutrophied coastal ecosystem: The Southern North Sea

Science.gov (United States)

Ghyoot, Caroline; Lancelot, Christiane; Flynn, Kevin J.; Mitra, Aditee; Gypens, Nathalie

2017-09-01

Most biogeochemical/ecological models divide planktonic protists between phototrophs (phytoplankton) and heterotrophs (zooplankton). However, a large number of planktonic protists are able to combine several mechanisms of carbon and nutrient acquisition. Not representing these multiple mechanisms in biogeochemical/ecological models describing eutrophied coastal ecosystems can potentially lead to different conclusions regarding ecosystem functioning, especially regarding the success of harmful algae, which are often reported as mixotrophic. This modelling study investigates the implications for trophic dynamics of including 3 contrasting forms of mixotrophy, namely osmotrophy (using alkaline phosphatase activity, APA), non-constitutive mixotrophy (acquired phototrophy by microzooplankton) and also constitutive mixotrophy. The application is in the Southern North Sea, an ecosystem that faced, between 1985 and 2005, a significant increase in the nutrient supply N:P ratio (from 31 to 81 mol N:P). The comparison with a traditional model shows that, when the winter N:P ratio in the Southern North Sea is above 22 molN molP-1 (as occurred from mid-1990s), APA allows a 3-32% increase of annual gross primary production (GPP). In result of the higher GPP, the annual sedimentation increases as well as the bacterial production. By contrast, APA does not affect the export of matter to higher trophic levels because the increased GPP is mainly due to Phaeocystis colonies, which are not grazed by copepods. Under high irradiance, non-constitutive mixotrophy appreciably increases annual GPP, transfer to higher trophic levels, sedimentation, and nutrient remineralisation. In this ecosystem, non-constitutive mixotrophy is also observed to have an indirect stimulating effect on diatoms. Constitutive mixotrophy in nanoflagellates appears to have little influence on this ecosystem functioning. An important conclusion from this work is that contrasting forms of mixotrophy have different

A comparative analysis to quantify the biogeochemical and biogeophysical cooling effects on climate of a white mustard cover crop

Science.gov (United States)

Ferlicoq, Morgan; Ceschia, Eric; Brut, Aurore; Tallec, Tiphaine; Carrer, Dominique; Pique, Gaetan; Ferroni, Nicole

2017-04-01

During the COP21, agriculture was recognised as a strategic sector and an opportunity to strengthen climate mitigation. In particular, the "4 per 1000" initiative relies upon solutions that refer to agro-ecology, conservation agriculture, … that could lead to increase carbon storage. Among those agro-ecology practices, including cover crops during fallow periods is considered as a fundamental agronomic lever for storing carbon. However, if biogeochemical benefits of cover-crops (CC) have already been addressed, their biogeophysical effects on climate have never been quantified and compared to biogeochemical effects. This comparative study (CC vs. bare soil), quantified and compared biogeochemical (including carbon storage) and biophysical effects (albedo and energy partitioning effect) of CC on climate. An experimental campaign was performed in 2013 in Southwest France, during the fallow period following a winter-wheat crop (and before a maize). The experimental plot was divided in two: the northern part was maintained in bare soil (BS) while white-mustard (WM) was grown during 3-months on the southern part. On each subplot, continuous measurements of CO2, latent and sensible fluxes (by eddy covariance) and solar radiation were acquired. Also, N2O emissions were measured by means of automatic chambers on each subplots. Moreover, by using a Life-Cycle-Analysis approach, each component of the greenhouse gas budget (GHGB) was quantified for each subplot, including emissions associated to field operations (FO). To quantify the albedo induced radiative forcing (RFα) caused by the white-mustard, the bare soil subplot was used as a reference state (IPCC, 2007). Finally, the net radiative forcing for each subplot was calculated as the sum of biogeochemical and biogeophysical (albedo effect) radiative forcing. The white-mustard allowed a net CO2 fixation of 63 g C-eq.m-2, corresponding to 20% of the net annual CO2 flux that year (-332 g C-eq.m-2). Through the WM seeds

Carbon sequestration by patch fertilization: A comprehensive assessment using coupled physical-ecological-biogeochemical models: FINAL REPORT of grant Grant No. DE-FG02-04ER63726

Energy Technology Data Exchange (ETDEWEB)

Sarmiento, Jorge L; Gnanadesikan, Anand; Gruber, Nicolas

2007-06-21

This final report summarizes research undertaken collaboratively between Princeton University, the NOAA Geophysical Fluid Dynamics Laboratory on the Princeton University campus, the State University of New York at Stony Brook, and the University of California, Los Angeles between September 1, 2000, and November 30, 2006, to do fundamental research on ocean iron fertilization as a means to enhance the net oceanic uptake of CO2 from the atmosphere. The approach we proposed was to develop and apply a suite of coupled physical-ecologicalbiogeochemical models in order to (i) determine to what extent enhanced carbon fixation from iron fertilization will lead to an increase in the oceanic uptake of atmospheric CO2 and how long this carbon will remain sequestered (efficiency), and (ii) examine the changes in ocean ecology and natural biogeochemical cycles resulting from iron fertilization (consequences). The award was funded in two separate three-year installments: • September 1, 2000 to November 30, 2003, for a project entitled “Ocean carbon sequestration by fertilization: An integrated biogeochemical assessment.” A final report was submitted for this at the end of 2003 and is included here as Appendix 1. • December 1, 2003 to November 30, 2006, for a follow-on project under the same grant number entitled “Carbon sequestration by patch fertilization: A comprehensive assessment using coupled physical-ecological-biogeochemical models.” This report focuses primarily on the progress we made during the second period of funding subsequent to the work reported on in Appendix 1. When we began this project, we were thinking almost exclusively in terms of long-term fertilization over large regions of the ocean such as the Southern Ocean, with much of our focus being on how ocean circulation and biogeochemical cycling would interact to control the response to a given fertilization scenario. Our research on these types of scenarios, which was carried out largely during

Design and performance of subgrade biogeochemical reactors.

Science.gov (United States)

Gamlin, Jeff; Downey, Doug; Shearer, Brad; Favara, Paul

2017-12-15

Subgrade biogeochemical reactors (SBGRs), also commonly referred to as in situ bioreactors, are a unique technology for treatment of contaminant source areas and groundwater plume hot spots. SBGRs have most commonly been configured for enhanced reductive dechlorination (ERD) applications for chlorinated solvent treatment. However, they have also been designed for other contaminant classes using alternative treatment media. The SBGR technology typically consists of removal of contaminated soil via excavation or large-diameter augers, and backfill of the soil void with gravel and treatment amendments tailored to the target contaminant(s). In most cases SBGRs include installation of infiltration piping and a low-flow pumping system (typically solar-powered) to recirculate contaminated groundwater through the SBGR for treatment. SBGRs have been constructed in multiple configurations, including designs capable of meeting limited access restrictions at heavily industrialized sites, and at sites with restrictions on surface disturbance due to sensitive species or habitat issues. Typical performance results for ERD applications include 85 to 90 percent total molar reduction of chlorinated volatile organic compounds (CVOCs) near the SBGR and rapid clean-up of adjacent dissolved contaminant source areas. Based on a review of the literature and CH2M's field-scale results from over a dozen SBGRs with a least one year of performance data, important site-specific design considerations include: 1) hydraulic residence time should be long enough for sufficient treatment but not too long to create depressed pH and stagnant conditions (e.g., typically between 10 and 60 days), 2) reactor material should balance appropriate organic mulch as optimal bacterial growth media along with other organic additives that provide bioavailable organic carbon, 3) a variety of native bacteria are important to the treatment process, and 4) biologically mediated generation of iron sulfides along with

Carbon and Nitrogen in the Lower Basin of the Paraíba do Sul River, Southeastern Brazil: Element fluxes and biogeochemical processes

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Luiz Antonio Martinelli

2011-08-01

Full Text Available The study was conducted in the lower basin of the Paraíba do Sul River (PSR, in which 57,000 km2 of the basin is located in the Brazilian states of São Paulo, Minas Gerais and Rio de Janeiro. We proposed to identify the main sources of C and N fluxes in the PSR waters, to evaluate biogeochemical processes in the watershed, and to estimate C and N riverine loads to the Atlantic Ocean in the context of the sugarcane plantation expansion for ethanol production. Riverine water samples were collected at seven stations along 12 months. Physicochemical and limnological parameters, as well as discharge, were measured together with organic and inorganic C and N species in the dissolved and suspended particulate material. C and N concentrations in bed fluvial sediments, and suspended particulate material were measured, and their elemental ([C:N]a and isotopic (δ13C compositions were compared with the [C:N]a and δ13C of the following sources: riparian soils, insular flooded soils, aquatic macrophytes, phytoplankton, pasture grass, sugarcane, sugarcane byproducts, and forest litterfall. Temporal patterns in the physicochemical and limnological environment were correlated to discharge. It also was observed that sugar cane production can increase riverine C and N fluxes. Riparian soils inputs were larger than insular soils, which was likely to act as a biogeochemical barrier. Effects of the macrophytes on riverine C and N were unclear, as well as urban sewage disposal effects. Although the PSR loads represented a very small percentage of the fluvial input to global biogeochemical cycles, we suggest that this and other medium sized watersheds in Eastern and Southeastern South America can be significant contributors to the continental biogeochemical riverine loads to the ocean, if their loads are considered together.

A System for Natural Language Sentence Generation.

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Levison, Michael; Lessard, Gregory

1992-01-01

Describes the natural language computer program, "Vinci." Explains that using an attribute grammar formalism, Vinci can simulate components of several current linguistic theories. Considers the design of the system and its applications in linguistic modelling and second language acquisition research. Notes Vinci's uses in linguistics…

Biogeochemical characteristics of Kuan-Tzu-Ling, Chung-Lun and Bao-Lai hot springs in southern Taiwan.

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Maity, Jyoti Prakash; Liu, Chia-Chuan; Nath, Bibhash; Bundschuh, Jochen; Kar, Sandeep; Jean, Jiin-Shuh; Bhattacharya, Prosun; Liu, Jiann-Hong; Atla, Shashi B; Chen, Chien-Yen

2011-01-01

Hot springs are the important natural sources of geothermally heated groundwater from the Earth's crust. Kuan-Tzu-Ling (KTL), Chung-Lun (CL) and Bao-Lai (BL) are well-known hot springs in southern Taiwan. Fluid and mud (sediments) samples were collected from the eruption points of three hot springs for detailed biogeochemical characterization. The fluid sample displays relatively high concentrations of Na(+) and Cl(-) compared with K(+), Mg(2+), Ca(2+), NO(2) (-), and SO(4) (2-), suggesting a possible marine origin. The concentrations of Fe, Cr, Mn, Ni, V and Zn were significantly higher in the mud sediments compared with fluids, whereas high concentrations of As, Ba, Cu, Se, Sr and Rb were observed in the fluids. This suggests that electronegative elements were released during sediment-water interactions. High As concentration in the fluids was observed to be associated with low redox (Eh) conditions. The FTIR spectra of the humic acid fractions of the sediments showed the presence of possible functional groups of secondary amines, ureas, urethanesm (amide), and silicon. The sulfate-reducing deltaproteobacterium 99% similar to Desulfovibrio psychrotolerans (GU329907) were rich in the CL hot spring while mesophilic, proteolytic, thiosulfate- and sulfur-reducing bacterium that 99% similar to Clostridium sulfidigenes (GU329908) were rich in the BL hot spring.

Linking human and natural systems in the planning process

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Susan I. Stewart; Miranda H. Mockrin; Roger B. Hammer

2012-01-01

Planning links human and natural systems in the urban-rural interface by engaging people in consideration of the future of natural resources. We review evolving ideas about what planning entails, who it involves, and what its outcomes should be. Sense of place, collaboration, emergent planning, and other new developments in planning are discussed. Smaller plans,...

Natural Interaction Based Online Military Boxing Learning System

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Yang, Chenglei; Wang, Lu; Sun, Bing; Yin, Xu; Wang, Xiaoting; Liu, Li; Lu, Lin

2013-01-01

Military boxing, a kind of Chinese martial arts, is widespread and health beneficial. In this paper, the authors introduce a military boxing learning system realized by 3D motion capture, Web3D and 3D interactive technologies. The interactions with the system are natural and intuitive. Users can observe and learn the details of each action of the…

Compensatory vapor loss and biogeochemical attenuation along flowpaths mute the water resources impacts of insect-induced forest mortality

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Biederman, J. A.; Brooks, P. D.; Harpold, A. A.; Gochis, D. J.; Ewers, B. E.; Reed, D. E.; Gutmann, E. D.

2013-12-01

Forested montane catchments are critical to the amount and quality of downstream water resources. In western North America more than 60 million people rely on mountain precipitation, and water managers face uncertain response to an unprecedented forest die-off from mountain pine beetle (MPB) infestation. Reduced snow interception and transpiration are expected to increase streamflow, while increased organic matter decay is expected to increase biogeochemical stream fluxes. Tree- to plot-scale observations have documented some of the expected changes, but there has been little significant change to streamflow or water quality at the larger scales relevant to water resources. A critical gap exists in our understanding of why tree-scale process changes have not led to the expected, large-scale increases in streamflow and biogeochemical fluxes. We address this knowledge gap with observations of water and biogeochemical fluxes at nested spatial scales including tree, hillslope, and catchments from 3 to 700 ha with more than 75% mortality. Catchment discharge showed reduced water yield consistent with co-located eddy covariance observations showing increased vapor losses following MPB. Stable water isotopes showed progressive kinetic fractionation (i.e. unsaturated transition layer above the evaporating surface) in snowpack, soil water and streams indicating greater abiotic evaporation from multiple water sources offsetting decreased interception and transpiration. In the 3rd to 5th years following MPB forest mortality, soil water DOC and DON were similar beneath killed and healthy trees, but concentrations were elevated 2-10 times in groundwater of MPB-impacted sites as compared to unimpacted. Stream water DOC and DON were about 3 times as large during snowmelt runoff in ephemeral zero-order channels of MPB-impacted sites compared to unimpacted. Processing in the headwater streams of MPB-impacted forests rapidly attenuated dissolved organic matter. From the MPB

DINAMICAL PROCESSES, ENTROPY AND INFORMATION IN NATURAL AND SOCIAL SYSTEMS

OpenAIRE

N. V. Katargin

2013-01-01

Possible to describe complicate as natural as social systems as objects consisted of nonlinearly dependent elements at the multi-dimension (phase) space contained as real as information components. The system movement is defined by natural growth of entropy and its decrease as a result of using of external energy sources and other resources. Examined the аssociation of entropy with the value of objects, as well as with humanitarian concepts: God's Providence, morality, and happiness.

Patterns of Transcript Abundance of Eukaryotic Biogeochemically-Relevant Genes in the Amazon River Plume.

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Brian L Zielinski

Full Text Available The Amazon River has the largest discharge of all rivers on Earth, and its complex plume system fuels a wide array of biogeochemical processes, across a large area of the western tropical North Atlantic. The plume thus stimulates microbial processes affecting carbon sequestration and nutrient cycles at a global scale. Chromosomal gene expression patterns of the 2.0 to 156 μm size-fraction eukaryotic microbial community were investigated in the Amazon River Plume, generating a robust dataset (more than 100 million mRNA sequences that depicts the metabolic capabilities and interactions among the eukaryotic microbes. Combining classical oceanographic field measurements with metatranscriptomics yielded characterization of the hydrographic conditions simultaneous with a quantification of transcriptional activity and identity of the community. We highlight the patterns of eukaryotic gene expression for 31 biogeochemically significant gene targets hypothesized to be valuable within forecasting models. An advantage to this targeted approach is that the database of reference sequences used to identify the target genes was selectively constructed and highly curated optimizing taxonomic coverage, throughput, and the accuracy of annotations. A coastal diatom bloom highly expressed nitrate transporters and carbonic anhydrase presumably to support high growth rates and enhance uptake of low levels of dissolved nitrate and CO2. Diatom-diazotroph association (DDA: diatoms with nitrogen fixing symbionts blooms were common when surface salinity was mesohaline and dissolved nitrate concentrations were below detection, and hence did not show evidence of nitrate utilization, suggesting they relied on ammonium transporters to aquire recently fixed nitrogen. These DDA blooms in the outer plume had rapid turnover of the photosystem D1 protein presumably caused by photodegradation under increased light penetration in clearer waters, and increased expression of silicon

Biogeochemical Cycling of Fe, S, C, N, and Mo in the 3.2 Ga ocean: Constraints from DXCL-DP Black Shales from Pilbara, Western Australia

Science.gov (United States)

Yamaguchi, K. E.; Naraoka, H.; Ikehara, M.; Ito, T.; Kiyokawa, S.

2014-12-01

Records of geochemical cycling of bio-essential, redox-sensitive elements have keys to decipher mysteries of the co-evolution of Earth and life. To obtain insight into biogeochemical cycling of those elements and early evolution of microbial biosphere from high-quality samples, we drilled through Mesoarchean strata in coastal Pilbara (Dixon Island-Cleaverville Drilling Project, see Yamaguchi et al., 2009; Kiyokawa et al., 2012), and obtained 3.2 Ga old drillcores (CL1, CL2, and DX) of sulfide-rich black shales in the Cleaverville Group, Pilbara Supergroup. We conducted a systematic geochemical study involving sequential extractions of Fe, S, C, and N for phase-dependent contents (e.g., pyrite-Fe, reactive-Fe, highly reactive-Fe, unreactive-Fe, pyrite-S, sulfate-S, organic-S, elemental-S, Corg, Ccarb, Norg, and Nclay) and their stable isotope compositions, micro FT-IR and laser Raman spectroscopy for extracted kerogen, in addition to major and trace (redox-sensitive; e.g., Mo) element analysis, for >100 samples. Here we integrate our recent multidisciplinary investigations into the redox state of ocean and nature of microbial biosphere in the ocean 3.2 Ga ago. All of the obtained data are very difficult to explain only by geochemical processes in strictly anoxic environments, where both atmosphere and oceans were completely anoxic, like an environment before the inferred "Great Oxidation Event" when pO2 was lower than 0.00001 PAL (e.g., Holland, 1994). Our extensive data set consistently suggests that oxygenic photosynthesis, bacterial sulfate reduction, and microbially mediated redox-cycling of nitrogen, possibly involving denitrification and N2-fixation, are very likely to have been operating, and may be used as a strong evidence for at least local and temporal existence of oxidized environment as far back as 3.2 Ga ago. Modern-style biogeochemical cycling of Fe, S, C, N, and Mo has been operating since then. The atmosphere-hydrosphere system 3.2 Ga ago would have

Deriving forest fire ignition risk with biogeochemical process modelling.

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Eastaugh, C S; Hasenauer, H

2014-05-01

Climate impacts the growth of trees and also affects disturbance regimes such as wildfire frequency. The European Alps have warmed considerably over the past half-century, but incomplete records make it difficult to definitively link alpine wildfire to climate change. Complicating this is the influence of forest composition and fuel loading on fire ignition risk, which is not considered by purely meteorological risk indices. Biogeochemical forest growth models track several variables that may be used as proxies for fire ignition risk. This study assesses the usefulness of the ecophysiological model BIOME-BGC's 'soil water' and 'labile litter carbon' variables in predicting fire ignition. A brief application case examines historic fire occurrence trends over pre-defined regions of Austria from 1960 to 2008. Results show that summer fire ignition risk is largely a function of low soil moisture, while winter fire ignitions are linked to the mass of volatile litter and atmospheric dryness.

Deriving forest fire ignition risk with biogeochemical process modelling☆

Science.gov (United States)

Eastaugh, C.S.; Hasenauer, H.

2014-01-01

Climate impacts the growth of trees and also affects disturbance regimes such as wildfire frequency. The European Alps have warmed considerably over the past half-century, but incomplete records make it difficult to definitively link alpine wildfire to climate change. Complicating this is the influence of forest composition and fuel loading on fire ignition risk, which is not considered by purely meteorological risk indices. Biogeochemical forest growth models track several variables that may be used as proxies for fire ignition risk. This study assesses the usefulness of the ecophysiological model BIOME-BGC's ‘soil water’ and ‘labile litter carbon’ variables in predicting fire ignition. A brief application case examines historic fire occurrence trends over pre-defined regions of Austria from 1960 to 2008. Results show that summer fire ignition risk is largely a function of low soil moisture, while winter fire ignitions are linked to the mass of volatile litter and atmospheric dryness. PMID:26109905

Environmental Assessment for Potential Impacts of Ocean CO2 Storage on Marine Biogeochemical Cycles

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Yamada, N.; Tsurushima, N.; Suzumura, M.; Shibamoto, Y.; Harada, K.

2008-12-01

Ocean CO2 storage that actively utilizes the ocean potential to dissolve extremely large amounts of CO2 is a useful option with the intent of diminishing atmospheric CO2 concentration. CO2 storage into sub-seabed geological formations is also considered as the option which has been already put to practical reconnaissance in some projects. Direct release of CO2 in the ocean storage and potential CO2 leakage from geological formations into the bottom water can alter carbonate system as well as pH of seawater. It is essential to examine to what direction and extent chemistry change of seawater induced by CO2 can affect the marine environments. Previous studies have shown direct and acute effects by increasing CO2 concentrations on physiology of marine organisms. It is also a serious concern that chemistry change can affect the rates of chemical, biochemical and microbial processes in seawater resulting in significant influences on marine biogeochemical cycles of the bioelements including carbon, nutrients and trace metals. We, AIST, have conducted a series of basic researches to assess the potential impacts of ocean CO2 storage on marine biogeochemical processes including CaCO3 dissolution, and bacterial and enzymatic decomposition of organic matter. By laboratory experiments using a special high pressure apparatus, the improved empirical equation was obtained for CaCO3 dissolution rate in the high CO2 concentrations. Based on the experimentally obtained kinetics with a numerical simulation for a practical scenario of oceanic CO2 sequestration where 50 Mton CO2 per year is continuously injected to 1,000-2,500 m depth within 100 x 333 km area for 30 years, we could illustrate precise 3-D maps for the predicted distributions of the saturation depth of CaCO3, in situ Ω value and CaCO3 dissolution rate in the western North Pacific. The result showed no significant change in the bathypelagic CaCO3 flux due to chemistry change induced by ocean CO2 sequestration. Both

Natural coordinates for a class of Benenti systems

International Nuclear Information System (INIS)

Blaszak, Maciej; Sergyeyev, Artur

2007-01-01

We present explicit formulas for the coordinates in which the Hamiltonians of the Benenti systems with flat metrics take natural form and the metrics in question are represented by constant diagonal matrices

Natural coordinates for a class of Benenti systems

Energy Technology Data Exchange (ETDEWEB)

Blaszak, Maciej [Institute of Physics, A. Mickiewicz University, Umultowska 85, 61-614 Poznan (Poland)]. E-mail: blaszakm@amu.edu.pl; Sergyeyev, Artur [Silesian University in Opava, Mathematical Institute, Na Rybnicku 1, 746 01 Opava (Czech Republic)]. E-mail: artur.sergyeyev@math.slu.cz

2007-05-21

We present explicit formulas for the coordinates in which the Hamiltonians of the Benenti systems with flat metrics take natural form and the metrics in question are represented by constant diagonal matrices.

Biogeochemical and Optical Analysis of Coastal DOM for Satellite Retrieval of Terrigenous DOM in the U.S. Middle Atlantic Bight

Science.gov (United States)

Mannino, A.; Dyda, R. Y.; Hernes, P. J.; Hooker, Stan; Hyde, Kim; Novak, Mike

2012-01-01

Estuaries and coastal ocean waters experience a high degree of variability in the composition and concentration of particulate and dissolved organic matter (DOM) as a consequence of riverine/estuarine fluxes of terrigenous DOM, sediments, detritus and nutrients into coastal waters and associated phytoplankton blooms. Our approach integrates biogeochemical measurements (elemental content, molecular analyses), optical properties (absorption) and remote sensing to examine terrestrial DOM contributions into the U.S. Middle Atlantic Bight (MAB). We measured lignin phenol composition, DOC and CDOM absorption within the Chesapeake and Delaware Bay mouths, plumes and adjacent coastal ocean waters to derive empirical relationships between CDOM and biogeochemical measurements for satellite remote sensing application. Lignin ranged from 0.03 to 6.6 ug/L between estuarine and outer shelf waters. Our results demonstrate that satellite-derived CDOM is useful as a tracer of terrigenous DOM in the coastal ocean

Past and present of sediment and carbon biogeochemical cycling models

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F. T. Mackenzie

2004-01-01

Full Text Available The global carbon cycle is part of the much more extensive sedimentary cycle that involves large masses of carbon in the Earth's inner and outer spheres. Studies of the carbon cycle generally followed a progression in knowledge of the natural biological, then chemical, and finally geological processes involved, culminating in a more or less integrated picture of the biogeochemical carbon cycle by the 1920s. However, knowledge of the ocean's carbon cycle behavior has only within the last few decades progressed to a stage where meaningful discussion of carbon processes on an annual to millennial time scale can take place. In geologically older and pre-industrial time, the ocean was generally a net source of CO2 emissions to the atmosphere owing to the mineralization of land-derived organic matter in addition to that produced in situ and to the process of CaCO3 precipitation. Due to rising atmospheric CO2 concentrations because of fossil fuel combustion and land use changes, the direction of the air-sea CO2 flux has reversed, leading to the ocean as a whole being a net sink of anthropogenic CO2. The present thickness of the surface ocean layer, where part of the anthropogenic CO2 emissions are stored, is estimated as of the order of a few hundred meters. The oceanic coastal zone net air-sea CO2 exchange flux has also probably changed during industrial time. Model projections indicate that in pre-industrial times, the coastal zone may have been net heterotrophic, releasing CO2 to the atmosphere from the imbalance between gross photosynthesis and total respiration. This, coupled with extensive CaCO3 precipitation in coastal zone environments, led to a net flux of CO2 out of the system. During industrial time the coastal zone ocean has tended to reverse its trophic status toward a non-steady state situation of net autotrophy, resulting in net uptake of anthropogenic CO2 and storage of carbon in the coastal ocean, despite the significant calcification

Examining fire-prone forest landscapes as coupled human and natural systems

Science.gov (United States)

Thomas A. Spies; Eric M. White; Jeffrey D. Kline; A. Paige Fisher; Alan Ager; John Bailey; John Bolte; Jennifer Koch; Emily Platt; Christine S. Olsen; Derric Jacobs; Bruce Shindler; Michelle M. Steen-Adams; Roger. Hammer

2014-01-01

Fire-prone landscapes are not well studied as coupled human and natural systems (CHANS) and present many challenges for understanding and promoting adaptive behaviors and institutions. Here, we explore how heterogeneity, feedbacks, and external drivers in this type of natural hazard system can lead to complexity and can limit the development of more adaptive approaches...

Consequences of ecological, evolutionary and biogeochemical uncertainty for coral reef responses to climatic stress.

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Mumby, Peter J; van Woesik, Robert

2014-05-19

Coral reefs are highly sensitive to the stress associated with greenhouse gas emissions, in particular ocean warming and acidification. While experiments show negative responses of most reef organisms to ocean warming, some autotrophs benefit from ocean acidification. Yet, we are uncertain of the response of coral reefs as systems. We begin by reviewing sources of uncertainty and complexity including the translation of physiological effects into demographic processes, indirect ecological interactions among species, the ability of coral reefs to modify their own chemistry, adaptation and trans-generational plasticity. We then incorporate these uncertainties into two simple qualitative models of a coral reef system under climate change. Some sources of uncertainty are far more problematic than others. Climate change is predicted to have an unambiguous negative effect on corals that is robust to several sources of uncertainty but sensitive to the degree of biogeochemical coupling between benthos and seawater. Macroalgal, zoanthid, and herbivorous fish populations are generally predicted to increase, but the ambiguity (confidence) of such predictions are sensitive to the source of uncertainty. For example, reversing the effect of climate-related stress on macroalgae from being positive to negative had no influence on system behaviour. By contrast, the system was highly sensitive to a change in the stress upon herbivorous fishes. Minor changes in competitive interactions had profound impacts on system behaviour, implying that the outcomes of mesocosm studies could be highly sensitive to the choice of taxa. We use our analysis to identify new hypotheses and suggest that the effects of climatic stress on coral reefs provide an exceptional opportunity to test emerging theories of ecological inheritance. Copyright © 2014 Elsevier Ltd. All rights reserved.

Neither nature nor environment: Systemic operationalism and ecologism

International Nuclear Information System (INIS)

Gomez E, Luis F

2009-01-01

Nature is a complex concept that some critics have found as one of the roots of the current crisis of orthodox modernity. Because of this, we think ecologism should develop a theory where it does not play a pivotal role. Here, we propose systemic operationalism as a theoretical basis for ecologism since it seems to meet this requirement without having to replace it with terms such as environment which appears to keep some of the problems critics see in the concept of nature.

Expert System for support of natural gas network management; Sistema especialista para gerenciamento de redes de gas natural: SEGRED

Energy Technology Data Exchange (ETDEWEB)

Silva, Jonny Carlos da [Universidade Federal de Santa Catarina (UFSC), Florianopolis, SC (Brazil); Hirano, Eduardo Wulff [Universidade Federal de Santa Catarina (UFSC), Florianopolis, SC (Brazil). Lab. de Hidraulica e Pneumatica (LASHIP); Moura, Newton Reis de [PETROBRAS, Rio de Janeiro, RJ (Brazil); Freire, Luiz Gustavo de Melo [PETROBRAS S.A., Pojuca, BA (Brazil). Unidade de Negocios de Gas Natural (UNGN)

2004-07-01

This work reports on the SEGRED project, which aims to develop an expert system for management of natural gas transportation networks. The system is currently being developed by LASHIP-UFSC in partnership with PETROBRAS/CENPES and TBG. The SEGRED system consists of an environment designed to support natural gas pipeline management by means of remote supervision of process parameters and analysis of the mutual interactions of those parameters by an expert system integrated to a dynamic simulator. The system is deployed through a process that contributes to making available for use the knowledge about functions such as line packing analysis and line break detection, thus enhancing the quality of execution of these tasks, which are related to the management of natural gas transportation network. The main benefits consist of promoting efforts to acquire and organize expert knowledge. This process contributes to the generation of a knowledge base with corporate technical memory, which can be made available in a permanent, expansible and useful way for decision-making. (author)

DINAMICAL PROCESSES, ENTROPY AND INFORMATION IN NATURAL AND SOCIAL SYSTEMS

Directory of Open Access Journals (Sweden)

N. V. Katargin

2013-01-01

Full Text Available Possible to describe complicate as natural as social systems as objects consisted of nonlinearly dependent elements at the multi-dimension (phase space contained as real as information components. The system movement is defined by natural growth of entropy and its decrease as a result of using of external energy sources and other resources. Examined the аssociation of entropy with the value of objects, as well as with humanitarian concepts: God's Providence, morality, and happiness.

Electron linear accelerator system for natural rubber vulcanization

Science.gov (United States)

Rimjaem, S.; Kongmon, E.; Rhodes, M. W.; Saisut, J.; Thongbai, C.

2017-09-01

Development of an electron accelerator system, beam diagnostic instruments, an irradiation apparatus and electron beam processing methodology for natural rubber vulcanization is underway at the Plasma and Beam Physics Research Facility, Chiang Mai University, Thailand. The project is carried out with the aims to improve the qualities of natural rubber products. The system consists of a DC thermionic electron gun, 5-cell standing-wave radio-frequency (RF) linear accelerator (linac) with side-coupling cavities and an electron beam irradiation apparatus. This system is used to produce electron beams with an adjustable energy between 0.5 and 4 MeV and a pulse current of 10-100 mA at a pulse repetition rate of 20-400 Hz. An average absorbed dose between 160 and 640 Gy is expected to be archived for 4 MeV electron beam when the accelerator is operated at 400 Hz. The research activities focus firstly on assembling of the accelerator system, study on accelerator properties and electron beam dynamic simulations. The resonant frequency of the RF linac in π/2 operating mode is 2996.82 MHz for the operating temperature of 35 °C. The beam dynamic simulations were conducted by using the code ASTRA. Simulation results suggest that electron beams with an average energy of 4.002 MeV can be obtained when the linac accelerating gradient is 41.7 MV/m. The rms transverse beam size and normalized rms transverse emittance at the linac exit are 0.91 mm and 10.48 π mm·mrad, respectively. This information can then be used as the input data for Monte Carlo simulations to estimate the electron beam penetration depth and dose distribution in the natural rubber latex. The study results from this research will be used to define optimal conditions for natural rubber vulcanization with different electron beam energies and doses. This is very useful for development of future practical industrial accelerator units.

Modeling the fate of nitrogen on the catchment scale using a spatially explicit hydro-biogeochemical simulation system

Science.gov (United States)

Klatt, S.; Butterbach-Bahl, K.; Kiese, R.; Haas, E.; Kraus, D.; Molina-Herrera, S. W.; Kraft, P.

2015-12-01

The continuous growth of the human population demands an equally growing supply for fresh water and food. As a result, available land for efficient agriculture is constantly diminishing which forces farmers to cultivate inferior croplands and intensify agricultural practices, e.g., increase the use of synthetic fertilizers. This intensification of marginal areas in particular will cause a dangerous rise in nitrate discharge into open waters or even drinking water resources. In order to reduce the amount of nitrate lost by surface runoff or lateral subsurface transport, bufferstrips have proved to be a valuable means. Current laws, however, promote rather static designs (i.e., width and usage) even though a multitude of factors, e.g., soil type, slope, vegetation and the nearby agricultural management, determines its effectiveness. We propose a spatially explicit modeling approach enabling to assess the effects of those factors on nitrate discharge from arable lands using the fully distributed hydrology model CMF coupled to the complex biogeochemical model LandscapeDNDC. Such a modeling scheme allows to observe the displacement of dissolved nutrients in both vertical and horizontal directions and serves to estimate both their uptake by the vegetated bufferstrip and loss to the environment. First results indicate a significant reduction of nitrate loss in the presence of a bufferstrip (2.5 m). We show effects induced by various buffer strip widths and plant cover on the nitrate retention.

Digital system to monitor the natural frequency of mechanical resonators

International Nuclear Information System (INIS)

Brengartner, Tobias; Siegel, Michael; Urban, Martin; Monse, Benjamin; Frühauf, Dietmar

2013-01-01

Mechanical resonators are often used in process or condition monitoring. They are used for liquid-level limit detection or for viscosity and density sensing. Therefore, the resonator is preferably actuated at its natural frequency. In industrial applications, this is achieved by analogue closed resonant circuits. These circuits have been established because of the low energy consumption and low component costs. Due to the future trend of microprocessors, digital systems are now an interesting alternative and can achieve better results compared to analogue realizations. In this context, this paper presents a novel digital system for monitoring the natural frequency of mechanical resonators. The system is realized with newly developed algorithms and is based on a simple signal processing procedure with minimum computational cost. This allows the use of a low-power microcontroller, thus making the system interesting for industrial use. It is shown that the natural frequency can be measured in respect of high industrial requirements on reliability, fastness and accuracy, combined with the possibility of reducing energy consumption. (paper)

PISCES-v2: an ocean biogeochemical model for carbon and ecosystem studies

Directory of Open Access Journals (Sweden)

O. Aumont

2015-08-01

of marine ecosystems (phytoplankton, microzooplankton and mesozooplankton and the biogeochemical cycles of carbon and of the main nutrients (P, N, Fe, and Si. The model is intended to be used for both regional and global configurations at high or low spatial resolutions as well as for short-term (seasonal, interannual and long-term (climate change, paleoceanography analyses. There are 24 prognostic variables (tracers including two phytoplankton compartments (diatoms and nanophytoplankton, two zooplankton size classes (microzooplankton and mesozooplankton and a description of the carbonate chemistry. Formulations in PISCES-v2 are based on a mixed Monod–quota formalism. On the one hand, stoichiometry of C / N / P is fixed and growth rate of phytoplankton is limited by the external availability in N, P and Si. On the other hand, the iron and silicon quotas are variable and the growth rate of phytoplankton is limited by the internal availability in Fe. Various parameterizations can be activated in PISCES-v2, setting, for instance, the complexity of iron chemistry or the description of particulate organic materials. So far, PISCES-v2 has been coupled to the Nucleus for European Modelling of the Ocean (NEMO and Regional Ocean Modeling System (ROMS systems. A full description of PISCES-v2 and of its optional functionalities is provided here. The results of a quasi-steady-state simulation are presented and evaluated against diverse observational and satellite-derived data. Finally, some of the new functionalities of PISCES-v2 are tested in a series of sensitivity experiments.

Study of the seasonal cycle of the biogeochemical processes in the Ligurian Sea using a 1D interdisciplinary model

NARCIS (Netherlands)

Raick, C.; Delhez, E.J.M.; Soetaert, K.E.R.; Grégoire, M.

2005-01-01

A one-dimensional coupled physical–biogeochemical model has been built to study the pelagic food web of the Ligurian Sea (NW Mediterranean Sea). The physical model is the turbulent closure model (version 1D) developed at the GeoHydrodynamics and Environmental Laboratory (GHER) of the University of

Biogeochemical Cycles for Combining Chemical Knowledge and ESD Issues in Greek Secondary Schools Part I: Designing the Didactic Materials

Science.gov (United States)

Koutalidi, Sophia; Scoullos, Michael

2016-01-01

Biogeochemical cycles support all anthropogenic activities and are affected by them, therefore they are intricately interlinked with global environmental and socioeconomic issues. Elements of these cycles that are already included in the science/chemical curriculum and textbooks intended for formal education in Greek secondary schools were…

Development of a natural Gas Systems Analysis Model (GSAM)

International Nuclear Information System (INIS)

1994-02-01

Lacking a detailed characterization of the resource base and a comprehensive borehole-to-burnertip evaluation model of the North American natural gas system, past R ampersand D, tax and regulatory policies have been formulated without a full understanding of their likely direct and indirect impacts on future gas supply and demand. The recent disappearance of the deliverability surplus, pipeline deregulation, and current policy debates about regulatory initiatives in taxation, environmental compliance and leasing make the need for a comprehensive gas evaluation system critical. Traditional econometric or highly aggregated energy models are increasingly regarded as unable to incorporate available geologic detail and explicit technology performance and costing algorithms necessary to evaluate resource-technology-economic interactions in a market context. The objective of this research is to create a comprehensive, non-proprietary, microcomputer model of the North American natural gas system. GSAM explicitly evaluates the key components of the natural gas system, including resource base, exploration and development, extraction technology performance and costs, transportation and storage and end use. The primary focus is the detailed characterization of the resource base at the reservoir and sub-reservoir level and the impact of alternative extraction technologies on well productivity and economics. GSAM evaluates the complex interactions of current and alternative future technology and policy initiatives in the context of the evolving gas markets. Scheduled for completion in 1995, a prototype is planned for early 1994. ICF Resources reviewed relevant natural gas upstream, downstream and market models to identify appropriate analytic capabilities to incorporate into GSAM. We have reviewed extraction technologies to better characterize performance and costs in terms of GSAM parameters

Studies of natural analogues and geological systems

International Nuclear Information System (INIS)

Brandberg, F.; Grundfelt, B.; Hoeglund, L.; Skagius K.; Karlsson, F.; Smellie, J.

1993-04-01

This review has involved studies of natural analogues and natural geological systems leading to the identification and quantification of processes and features of importance to the performance and safety of repositories for radioactive waste. The features and processes selected for the study comprise general geochemical issues related to the performance of the near- and far-field, the performance and durability of construction materials and the effects of glaciation. For each of these areas a number of potentially important processes for repository performance have been described, and evidence for their existence, as well as quantification of parameters of models describing the processes have been sought from major natural analogue studies and site investigations. The review has aimed at covering a relatively broad range of issues at the expense of in-depth analysis. The quantitative data presented are in most cases compilations of data from the literature; in a few cases results of evaluations made within the current project are included

Spatial distributions of biogeochemical reactions in freshwater-saltwater mixing zones of sandy beach aquifers

Science.gov (United States)

Kim, K. H.; Michael, H. A.; Ullman, W. J.; Cai, W. J.

2017-12-01

Beach aquifers host biogeochemically dynamic mixing zones between fresh and saline groundwaters of contrasting origins, histories, and compositions. Seawater, driven up the beachface by waves and tides, infiltrates into the sand and meets the seaward-discharging fresh groundwater, creating and maintaining a highly reactive intertidal circulation cell well-defined by salinity. Seawater supplies oxygen and reactive carbon to the circulation cell, supporting biogeochemical reactions within the cell that transform and attenuate dissolved nutrient fluxes from terrestrial sources. We investigated the spatial distribution of chemical reaction zones within the intertidal circulation cell at Cape Shores, Lewes, Delaware. Porewater samples were collected from multi-level wells along a beach-perpendicular transect. Samples were analyzed for particulate carbon and reactive solutes, and incubated to obtain rates of oxic respiration and denitrification. High rates of oxic respiration were observed higher on the beach, in the landward freshwater-saline water mixing zone, where dissolved oxygen availability was high. Denitrification was dominant in lower areas of the beach, below the intertidal discharge point. High respiration rates did not correlate with particulate carbon concentrations entrained within porewater, suggesting that dissolved organic carbon or immobile particulate carbon trapped within the sediment can contribute to and alter bulk reactivity. A better understanding of the sources and sinks of carbon within the beach will improve our ability to predict nutrient fluxes to estuaries and oceans, aiding the management of coastal environments and ecosystems.

Passive safety systems and natural circulation in water cooled nuclear power plants

International Nuclear Information System (INIS)

2009-11-01

Nuclear power produces 15% of the world's electricity. Many countries are planning to either introduce nuclear energy or expand their nuclear generating capacity. Design organizations are incorporating both proven means and new approaches for reducing the capital costs of their advanced designs. In the future most new nuclear plants will be of evolutionary design, often pursuing economies of scale. In the longer term, innovative designs could help to promote a new era of nuclear power. Since the mid-1980s it has been recognized that the application of passive safety systems (i.e. those whose operation takes advantage of natural forces such as convection and gravity), can contribute to simplification and potentially improve economics of new nuclear power plant designs. The IAEA Conference on The Safety of Nuclear Power: Strategy for the Future, which was convened in 1991, noted that for new plants 'the use of passive safety features is a desirable method of achieving simplification and increasing the reliability of the performance of essential safety functions, and should be used wherever appropriate'. Some new designs also utilize natural circulation as a means to remove core power during normal operation. The use of passive systems can eliminate the costs associated with the installation, maintenance, and operation of active systems that require multiple pumps with independent and redundant electric power supplies. However, considering the weak driving forces of passive systems based on natural circulation, careful design and analysis methods must be employed to ensure that the systems perform their intended functions. To support the development of advanced water cooled reactor designs with passive systems, investigations of natural circulation are conducted in several IAEA Member States with advanced reactor development programmes. To foster international collaboration on the enabling technology of passive systems that utilize natural circulation, the IAEA

Bio-optical profiling floats as new observational tools for biogeochemical and ecosystem studies: Potential synergies with ocean color remote sensing

Energy Technology Data Exchange (ETDEWEB)

Claustre, H.; Bishop, J.; Boss, E.; Bernard, S.; Berthon, J.-F.; Coatanoan, C.; Johnson, K.; Lotiker, A.; Ulloa, O.; Perry, M.J.; D' Ortenzio, F.; D' andon, O.H.F.; Uitz, J.

2009-10-01

Profiling floats now represent a mature technology. In parallel with their emergence, the field of miniature, low power bio-optical and biogeochemical sensors is rapidly evolving. Over recent years, the bio-geochemical and bio-optical community has begun to benefit from the increase in observational capacities by developing profiling floats that allow the measurement of key biooptical variables and subsequent products of biogeochemical and ecosystem relevance like Chlorophyll a (Chla), optical backscattering or attenuation coefficients which are proxies of Particulate Organic Carbon (POC), Colored Dissolved Organic Matter (CDOM). Thanks to recent algorithmic improvements, new bio-optical variables such as backscattering coefficient or absorption by CDOM, at present can also be extracted from space observations of ocean color. In the future, an intensification of in situ measurements by bio-optical profiling floats would permit the elaboration of unique 3D/4D bio-optical climatologies, linking surface (remotely detected) properties to their vertical distribution (measured by autonomous platforms), with which key questions in the role of the ocean in climate could be addressed. In this context, the objective of the IOCCG (International Ocean Color Coordinating Group) BIO-Argo working group is to elaborate recommendations in view of a future use of bio-optical profiling floats as part of a network that would include a global array that could be 'Argo-relevant', and specific arrays that would have more focused objectives or regional targets. The overall network, realizing true multi-scale sustained observations of global marine biogeochemistry and biooptics, should satisfy the requirements for validation of ocean color remote sensing as well as the needs of a wider community investigating the impact of global change on biogeochemical cycles and ecosystems. Regarding the global profiling float array, the recommendation is that Chla as well as POC should be the

Tracking Water, C, N, and P by Linking Local Scale Soil Hydrologic and Biogeochemical Features to Watershed Scale

Science.gov (United States)

Sedaghatdoost, A.; Mohanty, B.; Huang, Y.

2017-12-01

The biogeochemical cycles of carbon (C), nitrogen (N), and phosphorus (P) have many contemporary significance due to their critical roles in determining the structure and function of ecosystems. The objectives of our study is to find out temporal dynamics and spatial distribution of soil physical, chemical, and biological properties and their interaction with C, N, and P cycles in the soil for different land covers and weather conditions. The study is being conducted at three locations within Texas Water Observatory (TWO), including Riesel (USDA-ARS experimental watersheds), Texas A&M Agrilife Research Farm, and Danciger forest in Texas. Soil physical, hydraulic, chemical (total C, total N, total P, pH, EC, redox potential, N-NO3-, N-NH4+, PO42-, K, Ca, Mg, Na, Mn, and Alox and Feox), and microbiological (Microbial biomass C, N, and P, PLFA analysis, enzymatic activity) properties are being measured in the top 30 cm of the soil profile. Our preliminary data shows that biogeochemical processes would be more profound in the areas with higher temperature and precipitation as these factors stimulate microbial activity and thus influence C, N, and P cycles. Also concentrations of C and N are greater in woodlands relative to remnant grasslands as a consequence of the greater above- and below-ground productivity of woodlands relative to remnant grasslands. We hypothesize that finer soil textures have more organic matter, microbial population, and reactive surfaces for chemicals than coarse soils, as described in some recent literature. However, the microbial activity may not be active in fine textured soils as organic materials may be sorbed to clay surfaces or protected from decomposing organisms. We also expect reduced condition in saturated soils which will decrease carbon mineralization while increase denitrification and alkalinity in the soil. Spatio-temporal data with initial evaluation of biogeochemical factors/processes for different land covers will be presented.

Ecogenomics and potential biogeochemical impacts of globally abundant ocean viruses

KAUST Repository

Roux, Simon

2016-05-12

Ocean microbes drive biogeochemical cycling on a global scale. However, this cycling is constrained by viruses that affect community composition, metabolic activity, and evolutionary trajectories. Owing to challenges with the sampling and cultivation of viruses, genome-level viral diversity remains poorly described and grossly understudied, with less than 1% of observed surface-ocean viruses known. Here we assemble complete genomes and large genomic fragments from both surface-and deep-ocean viruses sampled during the Tara Oceans and Malaspina research expeditions, and analyse the resulting â global ocean virome\\' dataset to present a global map of abundant, double-stranded DNA viruses complete with genomic and ecological contexts. A total of 15,222 epipelagic and mesopelagic viral populations were identified, comprising 867 viral clusters (defined as approximately genus-level groups). This roughly triples the number of known ocean viral populations and doubles the number of candidate bacterial and archaeal virus genera, providing a near-complete sampling of epipelagic communities at both the population and viral-cluster level. We found that 38 of the 867 viral clusters were locally or globally abundant, together accounting for nearly half of the viral populations in any global ocean virome sample. While two-thirds of these clusters represent newly described viruses lacking any cultivated representative, most could be computationally linked to dominant, ecologically relevant microbial hosts. Moreover, we identified 243 viral-encoded auxiliary metabolic genes, of which only 95 were previously known. Deeper analyses of four of these auxiliary metabolic genes (dsrC, soxYZ, P-II (also known as glnB) and amoC) revealed that abundant viruses may directly manipulate sulfur and nitrogen cycling throughout the epipelagic ocean. This viral catalog and functional analyses provide a necessary foundation for the meaningful integration of viruses into ecosystem models where

Ecogenomics and potential biogeochemical impacts of globally abundant ocean viruses

KAUST Repository

Roux, Simon; Brum, Jennifer R; Dutilh, Bas E.; Sunagawa, Shinichi; Duhaime, Melissa B; Loy, Alexander; Poulos, Bonnie T; Solonenko, Natalie; Lara, Elena; Poulain, Julie; Pesant, Stephane; Kandels-Lewis, Stefanie; Dimier, Celine; Picheral, Marc; Searson, Sarah; Cruaud, Corinne; Alberti, Adriana; Duarte, Carlos M.; Gasol, Josep M M; Vaque, Dolors; Bork, Peer; Acinas, Silvia G; Wincker, Patrick; Sullivan, Matthew B

2016-01-01

Ocean microbes drive biogeochemical cycling on a global scale. However, this cycling is constrained by viruses that affect community composition, metabolic activity, and evolutionary trajectories. Owing to challenges with the sampling and cultivation of viruses, genome-level viral diversity remains poorly described and grossly understudied, with less than 1% of observed surface-ocean viruses known. Here we assemble complete genomes and large genomic fragments from both surface-and deep-ocean viruses sampled during the Tara Oceans and Malaspina research expeditions, and analyse the resulting â global ocean virome' dataset to present a global map of abundant, double-stranded DNA viruses complete with genomic and ecological contexts. A total of 15,222 epipelagic and mesopelagic viral populations were identified, comprising 867 viral clusters (defined as approximately genus-level groups). This roughly triples the number of known ocean viral populations and doubles the number of candidate bacterial and archaeal virus genera, providing a near-complete sampling of epipelagic communities at both the population and viral-cluster level. We found that 38 of the 867 viral clusters were locally or globally abundant, together accounting for nearly half of the viral populations in any global ocean virome sample. While two-thirds of these clusters represent newly described viruses lacking any cultivated representative, most could be computationally linked to dominant, ecologically relevant microbial hosts. Moreover, we identified 243 viral-encoded auxiliary metabolic genes, of which only 95 were previously known. Deeper analyses of four of these auxiliary metabolic genes (dsrC, soxYZ, P-II (also known as glnB) and amoC) revealed that abundant viruses may directly manipulate sulfur and nitrogen cycling throughout the epipelagic ocean. This viral catalog and functional analyses provide a necessary foundation for the meaningful integration of viruses into ecosystem models where they

A biogeochemical transport model to simulate the attenuation of chlorinated hydrocarbon contaminant fluxes across the groundwater-surface water interface

DEFF Research Database (Denmark)

Malaguerra, Flavio; Binning, Philip John; Albrechtsen, Hans-Jørgen

2009-01-01

and biogeochemical transformation model of the discharge of a TCE plume into a stream, and to determine which parameters most strongly affect pollutant discharge concentrations. Here biological kinetics and the interaction with the soil matrix are implemented in PHREEQC. The ability of PHREEQC to deal with a large...

Natural uranium-series radionuclide inventories in coastal and oceanic waters of the south-western Pacific - insights into trace metal flux and removal pathway analysis

International Nuclear Information System (INIS)

Szymczak, R.; Jeffree, R.A.; Peck, G.A.

2003-01-01

Participate scavenging of trace metals plays a major role in determining their ecosystem flux and incident dissolved concentrations. Differences in the half-lives and biogeochemical behaviour of natural uranium series radioisotope pairs (eg. 238 U/ 234 Th, 210 Pb/ 210 Po) allow their application as oceanic process tracers. Coincidental measurements of dissolved and particulate trace element concentrations and inventories of radionuclides in the Noumea coral lagoon and adjacent offshore waters were used to quantify water column flux rates and provide insights on removal pathway analysis. Understanding prevailing pathways and respective flux rates of pollutants in specific coastal and oceanic systems will assist to establish the fate and consequence of pollutants and allow sustainable management strategies to be developed. Both natural and pollutant chemical species introduced to the marine environment may either remain benign in solution or undergo physiological uptake by biota, but most often associate with colloids and fine particles, which subsequent undergo aggregation, sedimentation and removal to the sea floor

Towards the development of multifunctional molecular indicators combining soil biogeochemical and microbiological variables to predict the ecological integrity of silvicultural practices.

Science.gov (United States)

Peck, Vincent; Quiza, Liliana; Buffet, Jean-Philippe; Khdhiri, Mondher; Durand, Audrey-Anne; Paquette, Alain; Thiffault, Nelson; Messier, Christian; Beaulieu, Nadyre; Guertin, Claude; Constant, Philippe

2016-05-01

The impact of mechanical site preparation (MSP) on soil biogeochemical structure in young larch plantations was investigated. Soil samples were collected in replicated plots comprising simple trenching, double trenching, mounding and inverting site preparation. Unlogged natural mixed forest areas were used as a reference. Analysis of soil nutrients, abundance of bacteria and gas exchanges unveiled no significant difference among the plots. However, inverting site preparation resulted in higher variations of gas exchanges when compared with trenching, mounding and unlogged natural forest. A combination of the biological and physicochemical variables was used to define a multifunctional classification of the soil samples into four distinct groups categorized as a function of their deviation from baseline ecological conditions. According to this classification model, simple trenching was the approach that represented the lowest ecological risk potential at the microsite level. No relationship was observed between MSP method and soil bacterial community structure as assessed by high-throughput sequencing of bacterial 16S rRNA gene; however, indicator genotypes were identified for each multifunctional soil class. This is the first identification of multifunctional molecular indicators for baseline and disturbed ecological conditions in soil, demonstrating the potential of applied microbial ecology to guide silvicultural practices and ecological risk assessment. © 2016 The Authors. Microbial Biotechnology published by John Wiley & Sons Ltd and Society for Applied Microbiology.

Large- to submesoscale surface circulation and its implications on biogeochemical/biological horizontal distributions during the OUTPACE cruise (southwest Pacific)

Science.gov (United States)

Rousselet, Louise; de Verneil, Alain; Doglioli, Andrea M.; Petrenko, Anne A.; Duhamel, Solange; Maes, Christophe; Blanke, Bruno

2018-04-01

The patterns of the large-scale, meso- and submesoscale surface circulation on biogeochemical and biological distributions are examined in the western tropical South Pacific (WTSP) in the context of the OUTPACE cruise (February-April 2015). Multi-disciplinary original in situ observations were achieved along a zonal transect through the WTSP and their analysis was coupled with satellite data. The use of Lagrangian diagnostics allows for the identification of water mass pathways, mesoscale structures, and submesoscale features such as fronts. In particular, we confirmed the existence of a global wind-driven southward circulation of surface waters in the entire WTSP, using a new high-resolution altimetry-derived product, validated by in situ drifters, that includes cyclogeostrophy and Ekman components with geostrophy. The mesoscale activity is shown to be responsible for counter-intuitive water mass trajectories in two subregions: (i) the Coral Sea, with surface exchanges between the North Vanuatu Jet and the North Caledonian Jet, and (ii) around 170° W, with an eastward pathway, whereas a westward general direction dominates. Fronts and small-scale features, detected with finite-size Lyapunov exponents (FSLEs), are correlated with 25 % of surface tracer gradients, which reveals the significance of such structures in the generation of submesoscale surface gradients. Additionally, two high-frequency sampling transects of biogeochemical parameters and microorganism abundances demonstrate the influence of fronts in controlling the spatial distribution of bacteria and phytoplankton, and as a consequence the microbial community structure. All circulation scales play an important role that has to be taken into account not only when analysing the data from OUTPACE but also, more generally, for understanding the global distribution of biogeochemical components.

An introduction to high-frequency nutrient and biogeochemical monitoring for the Sacramento–San Joaquin Delta, northern California

Science.gov (United States)

Kraus, Tamara E.C.; Bergamaschi, Brian A.; Downing, Bryan D.

2017-07-11

Executive SummaryThis report is the first in a series of three reports that provide information about high-frequency (HF) nutrient and biogeochemical monitoring in the Sacramento–San Joaquin Delta of northern California (Delta). This first report provides an introduction to the reasons for and fundamental concepts behind collecting HF measurements, and describes the benefits associated with a real-time, continuous, HF, multi-parameter water quality monitoring station network that is co-located with flow stations. It then provides examples of how HF nutrient measurements have improved our understating of nutrient sources and cycling in aquatic systems worldwide, followed by specific examples from the Delta. These examples describe the ways in which HF instrumentation may be used for both fixed-station and spatial assessments. The overall intent of this document is to describe how HF measurements currently (2017) are being used in the Delta to examine the relationship between nutrient concentrations, nutrient cycling, and aquatic habitat conditions.The second report in the series (Downing and others, 2017) summarizes information about HF nutrient and associated biogeochemical monitoring in the northern Delta. The report synthesizes data available from the nutrient and water quality monitoring network currently operated by the U.S. Geological Survey in this ecologically important region of the Delta. In the report, we present and discuss the available data at various timescales—first, at the monthly, seasonal, and inter-annual timescales; and, second, for comparison, at the tidal and event (for example, storms, reservoir releases, phytoplankton blooms) timescales. As expected, we determined that there is substantial variability in nitrate concentrations at short timescales within hours, but also significant variability at longer timescales such as months or years. This multi-scale, high variability affects calculation of fluxes and loads, indicating that HF

Traceable components of terrestrial carbon storage capacity in biogeochemical models.

Science.gov (United States)

Xia, Jianyang; Luo, Yiqi; Wang, Ying-Ping; Hararuk, Oleksandra

2013-07-01

Biogeochemical models have been developed to account for more and more processes, making their complex structures difficult to be understood and evaluated. Here, we introduce a framework to decompose a complex land model into traceable components based on mutually independent properties of modeled biogeochemical processes. The framework traces modeled ecosystem carbon storage capacity (Xss ) to (i) a product of net primary productivity (NPP) and ecosystem residence time (τE ). The latter τE can be further traced to (ii) baseline carbon residence times (τ'E ), which are usually preset in a model according to vegetation characteristics and soil types, (iii) environmental scalars (ξ), including temperature and water scalars, and (iv) environmental forcings. We applied the framework to the Australian Community Atmosphere Biosphere Land Exchange (CABLE) model to help understand differences in modeled carbon processes among biomes and as influenced by nitrogen processes. With the climate forcings of 1990, modeled evergreen broadleaf forest had the highest NPP among the nine biomes and moderate residence times, leading to a relatively high carbon storage capacity (31.5 kg cm(-2) ). Deciduous needle leaf forest had the longest residence time (163.3 years) and low NPP, leading to moderate carbon storage (18.3 kg cm(-2) ). The longest τE in deciduous needle leaf forest was ascribed to its longest τ'E (43.6 years) and small ξ (0.14 on litter/soil carbon decay rates). Incorporation of nitrogen processes into the CABLE model decreased Xss in all biomes via reduced NPP (e.g., -12.1% in shrub land) or decreased τE or both. The decreases in τE resulted from nitrogen-induced changes in τ'E (e.g., -26.7% in C3 grassland) through carbon allocation among plant pools and transfers from plant to litter and soil pools. Our framework can be used to facilitate data model comparisons and model intercomparisons via tracking a few traceable components for all terrestrial carbon

Transfer and mobility of trace metallic elements in the sedimentary column of continental hydro-systems

International Nuclear Information System (INIS)

Devallois, V.

2009-02-01

In freshwater systems, trace metal pollutants are transferred into water and sedimentary columns under dissolved forms and/or fixed onto solid particles. Accumulated in the sedimentary areas, these latter ones can constitute important stocks of materials and associated pollutants and may impair water quality when environmental changes lead to increase their mobility. The mobility of the stocks of pollutants is mainly depending on the erosion, on the interstitial diffusion of the mobile phases (dissolved and colloidal) and on the bioturbation. In this context, this study involves the analysis of the mobility by interstitial diffusion. This topic consists in studying trace metal fractionation between their mobile (dissolved and colloidal) and non mobile (fixed onto the particles) forms. This point is governed by sorption/desorption processes at the particle surfaces. These processes are regulated by physico-chemical parameters (pH, redox potential, ionic strength...) and are influenced by biogeochemical reactions resulting from the oxidation of the organic matter by the microbial activity. These reactions generate vertical profiles of nutrients and metal concentrations along the sedimentary column. To understand these processes, this work is based on a mixed approach that combines in situ, analysis and modelling. In situ experimental part consists in sampling natural sediments cores collected at 4 different sites (1 site in Durance and 3 sites on the Rhone). These samples are analyzed according to an analytical protocol that provides the vertical distribution of physicochemical parameters (pH, redox potential, size distribution, porosity), nutrients and solid - liquid forms of trace metals (cobalt, copper, nickel, lead, zinc). The analysis and interpretation of these experimental results are based on a model that was developed during this study and that includes: 1) model of interstitial diffusion (Boudreau, 1997), 2) biogeochemical model (Wang and Van Cappellen

Soil engineering in vivo: harnessing natural biogeochemical systems for sustainable, multi-functional engineering solutions

OpenAIRE

DeJong, Jason T.; Soga, Kenichi; Banwart, Steven A.; Whalley, W. Richard; Ginn, Timothy R.; Nelson, Douglas C.; Mortensen, Brina M.; Martinez, Brian C.; Barkouki, Tammer

2010-01-01

Carbon sequestration, infrastructure rehabilitation, brownfields clean-up, hazardous waste disposal, water resources protection and global warming—these twenty-first century challenges can neither be solved by the high-energy consumptive practices that hallmark industry today, nor by minor tweaking or optimization of these processes. A more radical, holistic approach is required to develop the sustainable solutions society needs. Most of the above challenges occur within, are supported on, ar...

Clio: An Autonomous Vertical Sampling Vehicle for Global Ocean Biogeochemical Mapping

Science.gov (United States)

Jakuba, M.; Gomez-Ibanez, D.; Saito, M. A.; Dick, G.; Breier, J. A., Jr.

2014-12-01

We report the preliminary design of a fast vertical profiling autonomous underwater vehicle, called Clio, designed to cost-effectively improve the understanding of marine microorganism ecosystem dynamics on a global scale. The insights into biogeochemical cycles to be gained from illuminating the relationships between ocean life and chemistry have led to establishment of the GEOTRACES program. The nutrient and trace element profiles generated by GEOTRACES will provide insight into what is happening biogeochemically, but not how it is happening, i.e., what biochemical pathways are active? Advances in sequencing technology and in situ preservation have made it possible to study the genomics (DNA), transcriptomics (RNA), proteomics (proteins and enzymes), metabolomics (lipids and other metabolites), and metallomics (metals), associated with marine microorganisms; however, these techniques require sample collection. To this end, Clio will carry two to four SUspended Particle Rosette (SUPR) multi-samplers to depths of 6000 m. Clio is being designed specifically to complement the GEOTRACES program—to operate simultaneously and independently of the wire-based sampling protocols developed for GEOTRACES. At each GEOTRACES ocean transect sampling station, Clio will be deployed from the ship, transit vertically to the seafloor, and then ascend to, and stop at up to 32 sampling depths, where it will filter up to 150 l of seawater per sample. Filtered samples for RNA will be administered a dose of preservative (RNALater) in situ. Clio must efficiently hold station at multiple depths between the surface and 6000 m, but also move rapidly between sampling depths. It must be chemically clean and avoid disturbing the water column while sampling. Clio must be operationally friendly, requiring few personnel to operate, and have minimal impact on shipboard operations. We have selected a positively-buoyant thruster-driven design with a quasi-isopycnal construction. Our simulations

GeoCEGAS: natural gas distribution management system

Energy Technology Data Exchange (ETDEWEB)

Ribeiro, Lorena C.J. [Companhia de Gas do Ceara (CEGAS), Fortaleza, CE (Brazil); Targa, Fernando O. [Gestao Empresarial e Informatica Ltda. (GEMPI), Sao Paulo, SP (Brazil)

2009-07-01

This Technical Paper approach the conception, architecture, design, construction, and implementation of GeoCEGAS, a spatially enabled corporate management information system, oriented to store and provide Web access, to information associated with the natural gas distribution network, owned by CEGAS. This paper reports business processes, business entities and business intelligence approached on the project, as well as an overview of system architecture, applications, and technology used on the implementation of GeoCEGAS. Finally, is presented an introduction to the work methodology used, as well a synopsis of benefits achievements. (author)

Urban pollution of sediments: Impact on the physiology and burrowing activity of tubificid worms and consequences on biogeochemical processes

Energy Technology Data Exchange (ETDEWEB)

Pigneret, M., E-mail: mathilde.pigneret@univ-lyon1.fr [LEHNA, UMR CNRS 5023, Ecologie des Hydrosystèmes Naturels et Anthropisés, Université de Lyon, Université Lyon 1, ENTPE, 6 rue Raphael Dubois, 69622 Villeurbanne (France); Mermillod-Blondin, F.; Volatier, L.; Romestaing, C. [LEHNA, UMR CNRS 5023, Ecologie des Hydrosystèmes Naturels et Anthropisés, Université de Lyon, Université Lyon 1, ENTPE, 6 rue Raphael Dubois, 69622 Villeurbanne (France); Maire, E.; Adrien, J. [MATEIS, UMR CNRS 5510, INSA de Lyon, 25 avenue Jean Capelle, 69621 Villeurbanne (France); Guillard, L.; Roussel, D.; Hervant, F. [LEHNA, UMR CNRS 5023, Ecologie des Hydrosystèmes Naturels et Anthropisés, Université de Lyon, Université Lyon 1, ENTPE, 6 rue Raphael Dubois, 69622 Villeurbanne (France)

2016-10-15

In urban areas, infiltration basins are designed to manage stormwater runoff from impervious surfaces and allow the settling of associated pollutants. The sedimentary layer deposited at the surface of these structures is highly organic and multicontaminated (mainly heavy metals and hydrocarbons). Only few aquatic species are able to maintain permanent populations in such an extreme environment, including the oligochaete Limnodrilus hoffmeisteri. Nevertheless, the impact of urban pollutants on these organisms and the resulting influence on infiltration basin functioning remain poorly studied. Thus, the aim of this study was to determine how polluted sediments could impact the survival, the physiology and the bioturbation activity of L. hoffmeisteri and thereby modify biogeochemical processes occurring at the water-sediment interface. To this end, we conducted laboratory incubations of worms, in polluted sediments from infiltration basins or slightly polluted sediments from a stream. Analyses were performed to evaluate physiological state and burrowing activity (X-ray micro-tomography) of worms and their influences on biogeochemical processes (nutrient fluxes, CO{sub 2} and CH{sub 4} degassing rates) during 30-day long experiments. Our results showed that worms exhibited physiological responses to cope with high pollution levels, including a strong ability to withstand the oxidative stress linked to contamination with heavy metals. We also showed that the presence of urban pollutants significantly increased the burrowing activity of L. hoffmeisteri, demonstrating the sensitivity and the relevance of such a behavioural response as biomarker of sediment toxicity. In addition, we showed that X-ray micro-tomography was an adequate technique for accurate and non-invasive three-dimensional investigations of biogenic structures formed by bioturbators. The presence of worms induced stimulations of nutrient fluxes and organic matter recycling (between + 100% and 200% of CO

For Nature: Deep Greening World-Systems Analysis for the 21st Century

Directory of Open Access Journals (Sweden)

Sing S. Chew

2015-08-01

Full Text Available From its conception the world-systems perspective has been preoccupied with the study of long term global transformations (see for ex., Frank 1968, 1979; Wallerstein 1974; Amin 1974; Wolf, 1982; Chase-Dunn 1989; Chase-Dunn and Hall 1992; Kaplan 1978.2. To this extent, the various structural relationships, trends, and cycles of the world system have been identified to explain the processes of global transformation. The varied attempts to pinpoint and analyze these relations, trends, and cycles have been within the context of connections between humans, classes, status groups, industries, regions, and states in the world economy. From an ecological point of view (ontologically and epistemologically, such a manner of understanding change is quite anthropocentric, as global transformation necessitates a changing relationship with Nature. In an era of increasing global concern and awareness of the finite nature of natural resources and the growing realization of the contemporary losses in plant and animal species and the continued susceptibility of the human species to climatological changes and diseases despite various scientific and technological advances, we need to consider that besides social relations and structures, the basis of human reproduction includes our relationships with the non-human world (ecology. World-systems /world system analyses need to move beyond deciphering the processes of global change only through the social (anthropocentric dimension of the relations underlining these processes. Keeping to just the social relations/structures of the reproduction of the system limits the range of explanations we can provide for global transformation, and also restricts the dimensions whereby the basis for these changes can be explored. This paper is an attempt to introduce the other basic dimension (our relations with Nature into the overall equation of world-systems/world system analyses for our understanding of global change. Ultimately

Proposal for Holistic Assessment of Urban System Resilience to Natural Disasters

Science.gov (United States)

Koren, David; Kilar, Vojko; Rus, Katarina

2017-10-01

Urban system is a complex mix of interdependent components and dynamic interactions between them that enable it to function effectively. Resilience of urban system indicates the ability of a system to resist, absorb, accommodate to and recover from the effects of a hazard in a timely and efficient manner. In the relevant literature, most studies consider individual components separately. On the other hand, the purpose of this paper is to assess the urban system as a whole, considering all relevant components and their interactions. The goal is a study of possibilities for holistic evaluation of urban system resilience to natural disasters. Findings from the preliminary study are presented: (i) the definition of urban system and categorization of its components, (ii) a set of attributes of individual components with impact on disaster resilience of the entire system and (iii) review of different methods and approaches for resilience assessment. Based on literature review and extensive preliminary studies a new conceptual framework for urban resilience assessment is proposed. In the presented paper, a conceptual model of urban system by abstraction of its components as nodes (buildings), patches - specific nodes with spatial properties (open space), links (infrastructures) and base layer (community) is created. In the suggested model, each component is defined by its own quantitative attributes, which have been identified to have an important impact on the urban system resilience to natural disasters. System is presented as a mathematical graph model. Natural disaster is considered an external factor that affects the existing system and leads to some system distortion. In further analyses, mathematical simulation of various natural disasters scenarios is going to be carried out, followed by comparison of the system functionality before and after the accident. Various properties of the system (accessibility, transition, complexity etc.) are going to be analysed with

MOPS-1.0: towards a model for the regulation of the global oceanic nitrogen budget by marine biogeochemical processes

Directory of Open Access Journals (Sweden)

I. Kriest

2015-09-01

Analysis of the model misfit with respect to observed biogeochemical tracer distributions and fluxes suggests a particle flux profile close to the one suggested by Martin et al. (1987. Simulated pelagic denitrification best agrees with the lower values between 59 and 84 Tg N yr−1 recently estimated by other authors.

Status, Antimicrobial Mechanism, and Regulation of Natural Preservatives in Livestock Food Systems.

Science.gov (United States)

Lee, Na-Kyoung; Paik, Hyun-Dong

2016-01-01

This review discusses the status, antimicrobial mechanisms, application, and regulation of natural preservatives in livestock food systems. Conventional preservatives are synthetic chemical substances including nitrates/nitrites, sulfites, sodium benzoate, propyl gallate, and potassium sorbate. The use of artificial preservatives is being reconsidered because of concerns relating to headache, allergies, and cancer. As the demand for biopreservation in food systems has increased, new natural antimicrobial compounds of various origins are being developed, including plant-derived products (polyphenolics, essential oils, plant antimicrobial peptides (pAMPs)), animal-derived products (lysozymes, lactoperoxidase, lactoferrin, ovotransferrin, antimicrobial peptide (AMP), chitosan and others), and microbial metabolites (nisin, natamycin, pullulan, ε-polylysine, organic acid, and others). These natural preservatives act by inhibiting microbial cell walls/membranes, DNA/RNA replication and transcription, protein synthesis, and metabolism. Natural preservatives have been recognized for their safety; however, these substances can influence color, smell, and toxicity in large amounts while being effective as a food preservative. Therefore, to evaluate the safety and toxicity of natural preservatives, various trials including combinations of other substances or different food preservation systems, and capsulation have been performed. Natamycin and nisin are currently the only natural preservatives being regulated, and other natural preservatives will have to be legally regulated before their widespread use.

Natural attenuation of metals and radionuclides - An overview of the Sandia/DOE approach

International Nuclear Information System (INIS)

Waters, R.D.; Brady, P.V.; Borns, D.J.

1998-02-01

Sandia National Laboratories is developing guidelines that outline the technical basis for relying on natural attenuation for the remediation of metals and radionuclide-contaminated soils and groundwaters at US Department of Energy (DOE) sites for those specific cases where natural processes are effective at ameliorating soil and groundwater toxicity. Remediation by monitored natural attenuation (MNA) requires a clear identification of the specific reaction(s) by which contaminant levels are made less available as well as considerable long-term monitoring. Central to MNA is the development of a conceptual model describing the biogeochemical behavior of contaminant(s) in the subsurface. The conceptual model will be used to make testable predictions of contaminant availability over time. In many cases, comparison between this prediction and field measurements will provide the test of whether MNA is to be implemented. As a result, development of the conceptual model should guide site characterization activities as well as long-term monitoring

Catastrophes in nature and society mathematical modeling of complex systems

CERN Document Server

Khlebopros, Rem G; Fet, Abram I

2007-01-01

Many people are concerned about crises leading to disasters in nature, in social and economic life. The book offers a popular account of the causative mechanisms of critical states and breakdown in a broad range of natural and cultural systems - which obey the same laws - and thus makes the reader aware of the origin of catastrophic events and the ways to avoid and mitigate their negative consequences. The authors apply a single mathematical approach to investigate the revolt of cancer cells that destroy living organisms and population outbreaks that upset natural ecosystems, the balance between biosphere and global climate interfered lately by industry, the driving mechanisms of market and related economic and social phenomena, as well as the electoral system the proper use of which is an arduous accomplishment of democracy.

Compound-specific isotopic analyses: a novel tool for reconstruction of ancient biogeochemical processes

Science.gov (United States)

Hayes, J. M.; Freeman, K. H.; Popp, B. N.; Hoham, C. H.

1990-01-01

Patterns of isotopic fractionation in biogeochemical processes are reviewed and it is suggested that isotopic fractionations will be small when substrates are large. If so, isotopic compositions of biomarkers will reflect those of their biosynthetic precursors. This prediction is tested by consideration of results of analyses of geoporphyrins and geolipids from the Greenhorn Formation (Cretaceous, Western Interior Seaway of North America) and the Messel Shale (Eocene, lacustrine, southern Germany). It is shown (i) that isotopic compositions of porphyrins that are related to a common source, but which have been altered structurally, cluster tightly and (ii) that isotopic differences between geolipids and porphyrins related to a common source are equal to those observed in modern biosynthetic products. Both of these observations are consistent with preservation of biologically controlled isotopic compositions during diagenesis. Isotopic compositions of individual compounds can thus be interpreted in terms of biogeochemical processes in ancient depositional environments. In the Cretaceous samples, isotopic compositions of n-alkanes are covariant with those of total organic carbon, while delta values for pristane and phytane are covariant with those of porphyrins. In this unit representing an open marine environment, the preserved acyclic polyisoprenoids apparently derive mainly from primary material, while the extractable, n-alkanes derive mainly from lower levels of the food chain. In the Messel Shale, isotopic compositions of individual biomarkers range from -20.9 to -73.4% vs PDB. Isotopic compositions of specific compounds can be interpreted in terms of origin from methylotrophic, chemautotrophic, and chemolithotrophic microorganisms as well as from primary producers that lived in the water column and sediments of this ancient lake.

Fractal reactor: An alternative nuclear fusion system based on nature's geometry

International Nuclear Information System (INIS)

Siler, T. L.

2007-01-01

The author presents his concept of the Fractal Reactor, which explores the possibility of building a plasma fusion power reactor based on the real geometry of nature [fractals], rather than the virtual geometry that Euclid postulated around 330 BC; nearly every architect of our plasma fusion devices has been influenced by his three-dimensional geometry. The idealized points, lines, planes, and spheres of this classical geometry continue to be used to represent the natural world and to describe the properties of all geometrical objects, even though they neither accurately nor fully convey nature's structures and processes. The Fractal Reactor concept contrasts the current containment mechanisms of both magnetic and inertial containment systems for confining and heating plasmas. All of these systems are based on Euclidean geometry and use geometrical designs that, ultimately, are inconsistent with the Non-Euclidean geometry and irregular, fractal forms of nature (3). The author explores his premise that a controlled, thermonuclear fusion energy system might be more effective if it more closely embodies the physics of a star

Soil Biogeochemical and Microbial Feedbacks along a Snowmelt-Dominated Hillslope-to-Floodplain Transect in Colorado.

Science.gov (United States)

Sorensen, P.; Beller, H. R.; Bill, M.; Bouskill, N.; Brodie, E.; Chakraborty, R.; Conrad, M. E.; Karaoz, U.; Polussa, A.; Steltzer, H.; Wang, S.; Williams, K. H.; Wilmer, C.; Wu, Y.

2017-12-01

Nitrogen export from mountainous watersheds is a product of multiple interactions among hydrological processes and soil-microbial-plant feedbacks along the continuum from terrestrial to aquatic environments. In snow-dominated systems, like the East River Watershed (CO), seasonal processes such as snowmelt exert significant influence on the annual hydrologic cycle and may also link spatially distinct catchment subsystems, such as hillslope and adjoining riparian floodplains. Further, snowmelt is occurring earlier each year and this is predicted to result in a temporal asynchrony between historically coupled microbial nutrient release and plant nutrient demand in spring, with the potential to increase N export from the East River Watershed. Here we summarize biogeochemical data collected along a hillslope-to-riparian floodplain transect at the East River site. Starting in Fall 2016, we sampled soils at 3 depths and measured dissolved pools of soil nutrients (e.g., NH4+, NO3-, DOC, P), microbial biomass CN, and microbial community composition over a seasonal time course, through periods of snow accumulation, snowmelt, and plant senescence. Soil moisture content in the top 5 cm of floodplain soils was nearly 4X greater across sampling dates, coinciding with 2X greater microbial biomass C, larger extractable pools of NH4+, and smaller pools of NO3- in floodplain vs. hillslope soils. These results suggest that microbially mediated redox processes played an important role in N cycling along the transect. Hillslope vs. floodplain location also appeared to be a key factor that differentiated soil microbial communities (e.g., a more important factor than seasonality or soil depth or type). Snow accumulation and snowmelt exerted substantial influence on soil biogeochemistry. For example, microbial biomass accumulation increased about 2X beneath the winter snowpack. Snowmelt resulted in a precipitous crash in the microbial population, with 2.5X reductions in floodplain and 2X

Natural circulating passive cooling system for nuclear reactor containment structure

Science.gov (United States)

Gou, Perng-Fei; Wade, Gentry E.

1990-01-01

A passive cooling system for the contaminant structure of a nuclear reactor plant providing protection against overpressure within the containment attributable to inadvertent leakage or rupture of the system components. The cooling system utilizes natural convection for transferring heat imbalances and enables the discharge of irradiation free thermal energy to the atmosphere for heat disposal from the system.

Knowledge Systems and Natural Resources : Management, Policy ...

International Development Research Centre (IDRC) Digital Library (Canada)

31 oct. 2007 ... Depuis quelques années, les chercheurs, les responsables des politiques et les militants du développement s'intéressent fortement aux systèmes de connaissances. Knowledge Systems and Natural Resources est un recueil unique d'études de cas réalisées au Népal. Cet ouvrage apporte un éclairage ...

Virus Database and Online Inquiry System Based on Natural Vectors.

Science.gov (United States)

Dong, Rui; Zheng, Hui; Tian, Kun; Yau, Shek-Chung; Mao, Weiguang; Yu, Wenping; Yin, Changchuan; Yu, Chenglong; He, Rong Lucy; Yang, Jie; Yau, Stephen St

2017-01-01

We construct a virus database called VirusDB (http://yaulab.math.tsinghua.edu.cn/VirusDB/) and an online inquiry system to serve people who are interested in viral classification and prediction. The database stores all viral genomes, their corresponding natural vectors, and the classification information of the single/multiple-segmented viral reference sequences downloaded from National Center for Biotechnology Information. The online inquiry system serves the purpose of computing natural vectors and their distances based on submitted genomes, providing an online interface for accessing and using the database for viral classification and prediction, and back-end processes for automatic and manual updating of database content to synchronize with GenBank. Submitted genomes data in FASTA format will be carried out and the prediction results with 5 closest neighbors and their classifications will be returned by email. Considering the one-to-one correspondence between sequence and natural vector, time efficiency, and high accuracy, natural vector is a significant advance compared with alignment methods, which makes VirusDB a useful database in further research.

Thermodynamic Modeling of Natural Gas Systems Containing Water

DEFF Research Database (Denmark)

Karakatsani, Eirini K.; Kontogeorgis, Georgios M.

2013-01-01

As the need for dew point specifications remains very urgent in the natural gas industry, the development of accurate thermodynamic models, which will match experimental data and will allow reliable extrapolations, is needed. Accurate predictions of the gas phase water content in equilibrium...... with a heavy phase were previously obtained using cubic plus association (CPA) coupled with a solid phase model in the case of hydrates, for the binary systems of water–methane and water–nitrogen and a few natural gas mixtures. In this work, CPA is being validated against new experimental data, both water...... content and phase equilibrium data, and solid model parameters are being estimated for four natural gas main components (methane, ethane, propane, and carbon dioxide). Different tests for the solid model parameters are reported, including vapor-hydrate-equilibria (VHE) and liquid-hydrate-equilibria (LHE...

Photobleaching Response of Different Sources of Chromophoric Dissolved Organic Matter Exposed to Natural Solar Radiation Using Absorption and Excitation?Emission Matrix Spectra

OpenAIRE

Zhang, Yunlin; Liu, Xiaohan; Osburn, Christopher L.; Wang, Mingzhu; Qin, Boqiang; Zhou, Yongqiang

2013-01-01

CDOM biogeochemical cycle is driven by several physical and biological processes such as river input, biogeneration and photobleaching that act as primary sinks and sources of CDOM. Watershed-derived allochthonous (WDA) and phytoplankton-derived autochthonous (PDA) CDOM were exposed to 9 days of natural solar radiation to assess the photobleaching response of different CDOM sources, using absorption and fluorescence (excitation-emission matrix) spectroscopy. Our results showed a marked decrea...

Nonequilibrium thermodynamics and maximum entropy production in the Earth system: applications and implications.

Science.gov (United States)

Kleidon, Axel

2009-06-01

The Earth system is maintained in a unique state far from thermodynamic equilibrium, as, for instance, reflected in the high concentration of reactive oxygen in the atmosphere. The myriad of processes that transform energy, that result in the motion of mass in the atmosphere, in oceans, and on land, processes that drive the global water, carbon, and other biogeochemical cycles, all have in common that they are irreversible in their nature. Entropy production is a general consequence of these processes and measures their degree of irreversibility. The proposed principle of maximum entropy production (MEP) states that systems are driven to steady states in which they produce entropy at the maximum possible rate given the prevailing constraints. In this review, the basics of nonequilibrium thermodynamics are described, as well as how these apply to Earth system processes. Applications of the MEP principle are discussed, ranging from the strength of the atmospheric circulation, the hydrological cycle, and biogeochemical cycles to the role that life plays in these processes. Nonequilibrium thermodynamics and the MEP principle have potentially wide-ranging implications for our understanding of Earth system functioning, how it has evolved in the past, and why it is habitable. Entropy production allows us to quantify an objective direction of Earth system change (closer to vs further away from thermodynamic equilibrium, or, equivalently, towards a state of MEP). When a maximum in entropy production is reached, MEP implies that the Earth system reacts to perturbations primarily with negative feedbacks. In conclusion, this nonequilibrium thermodynamic view of the Earth system shows great promise to establish a holistic description of the Earth as one system. This perspective is likely to allow us to better understand and predict its function as one entity, how it has evolved in the past, and how it is modified by human activities in the future.

Bacterial Production and Enzymatic Activities in Deep-Sea Sediments of the Pacific Ocean: Biogeochemical Implications of Different Temperature Constraints

Science.gov (United States)

Danovaro, R.; Corinaldesi, C.; dell'Anno, A.

2002-12-01

The deep-sea bed, acting as the ultimate sink for organic material derived from the upper oceans primary production, is now assumed to play a key role in biogeochemical cycling of organic matter on global scale. Early diagenesis of organic matter in marine sediments is dependent upon biological processes (largely mediated by bacterial activity) and by molecular diffusion. Organic matter reaching the sea floor by sedimentation is subjected to complex biogeochemical transformations that make organic matter largely unsuitable for direct utilization by benthic heterotrophs. Extracellular enzymatic activities in the sediment is generally recognized as the key step in the degradation and utilization of organic polymers by bacteria and a key role in biopolymeric carbon mobilization is played by aminopeptidase, alkaline phosphatase and glucosidase activities. In the present study we investigated bacterial density, bacterial C production and exo-enzymatic activities (aminopeptidase, glucosidase and phosphatase activity) in deep-sea sediments of the Pacific Ocean in relation with the biochemical composition of sediment organic matter (proteins, carbohydrates and lipids), in order to gather information on organic matter cycling and diagenesis. Benthic viral abundance was also measured to investigate the potential role of viruses on microbial loop functioning. Sediment samples were collected at eight stations (depth ranging from 2070-3100 m) along two transects located at the opposite side (north and south) of ocean seismic ridge Juan Fernandez (along latitudes 33° 20' - 33° 40'), constituted by the submerged vulcanoes, which connects the Chilean coasts to Rapa Nui Island. Since the northern and southern sides of this ridge apparently displayed small but significant differences in deep-sea temperature (related to the general ocean circulation), this sampling strategy allowed also investigating the role of different temperature constraints on bacterial activity and

GEOTRACES – An international study of the global marine biogeochemical cycles of trace elements and their isotopes

OpenAIRE

Henderson, G.M.; Anderson, R.F.; Adkins, J.; Andersson, P.; Boyle, E.A.; Cutter, Greg; Baar, H. de; Eisenhauer, Anton; Frank, Martin; Francois, R.; Orians, Kristin; Gamo, T.; German, C.; Jenkins, W.; Moffett, J.

2007-01-01

Trace elements serve important roles as regulators of ocean processes including marine ecosystem dynamics and carbon cycling. The role of iron, for instance, is well known as a limiting micronutrient in the surface ocean. Several other trace elements also play crucial roles in ecosystem function and their supply therefore controls the structure, and possibly the productivity, of marine ecosystems. Understanding the biogeochemical cycling of these micronutrients requires knowledge of their div...

Progressive nature of heart failure and systems biology

Directory of Open Access Journals (Sweden)

George E. Louridas

2015-01-01

Full Text Available The progressive nature of heart failure (HF is the predominant cause for the clinical course that the HF syndrome is taking. Systems biology methodology is of the utmost importance to explain and comprehend the built-in mechanisms of adverse clinical progression. Various heart diseases produce myocardial damage with subsequent left ventricular remodeling which is the principal underlying pathophysiological mechanism for the clinical progression of HF. The self-organized positive feedback stabilization mechanisms of left ventricular remodeling, adrenergic stimulation and activation of the renin-angiotensin-aldosterone system and natriuretic peptide systems, are hierarchical adaptive processes. These adaptive processes are responsible for further left ventricular remodeling with subsequent clinical deterioration and for the emergence of clinical phenotypes. These mechanisms are counteracted with angiotensin-converting enzyme inhibitors, angiotensin receptor blockers and β-blockers in an attempt to improve the adverse clinical phenomena of HF progression in a new but clinically worse stabilization level. In this review our intention is to underline the progressive nature of the HF syndrome and to demonstrate the significance of ventricular remodeling and the role of self-organized positive feedback adaptive processes.

Improving National Capability in Biogeochemical Flux Modelling: the UK Environmental Virtual Observatory (EVOp)

Science.gov (United States)

Johnes, P.; Greene, S.; Freer, J. E.; Bloomfield, J.; Macleod, K.; Reaney, S. M.; Odoni, N. A.

2012-12-01

The best outcomes from watershed management arise where policy and mitigation efforts are underpinned by strong science evidence, but there are major resourcing problems associated with the scale of monitoring needed to effectively characterise the sources rates and impacts of nutrient enrichment nationally. The challenge is to increase national capability in predictive modelling of nutrient flux to waters, securing an effective mechanism for transferring knowledge and management tools from data-rich to data-poor regions. The inadequacy of existing tools and approaches to address these challenges provided the motivation for the Environmental Virtual Observatory programme (EVOp), an innovation from the UK Natural Environment Research Council (NERC). EVOp is exploring the use of a cloud-based infrastructure in catchment science, developing an exemplar to explore N and P fluxes to inland and coastal waters in the UK from grid to catchment and national scale. EVOp is bringing together for the first time national data sets, models and uncertainty analysis into cloud computing environments to explore and benchmark current predictive capability for national scale biogeochemical modelling. The objective is to develop national biogeochemical modelling capability, capitalising on extensive national investment in the development of science understanding and modelling tools to support integrated catchment management, and supporting knowledge transfer from data rich to data poor regions, The AERC export coefficient model (Johnes et al., 2007) has been adapted to function within the EVOp cloud environment, and on a geoclimatic basis, using a range of high resolution, geo-referenced digital datasets as an initial demonstration of the enhanced national capacity for N and P flux modelling using cloud computing infrastructure. Geoclimatic regions are landscape units displaying homogenous or quasi-homogenous functional behaviour in terms of process controls on N and P cycling

Couplings between changes in the climate system and biogeochemistry

Energy Technology Data Exchange (ETDEWEB)

Menon, Surabi; Denman, Kenneth L.; Brasseur , Guy; Chidthaisong, Amnat; Ciais, Philippe; Cox, Peter M.; Dickinson, Robert E.; Hauglustaine, Didier; Heinze, Christoph; Holland, Elisabeth; Jacob , Daniel; Lohmann, Ulrike; Ramachandran, Srikanthan; Leite da Silva Dias, Pedro; Wofsy, Steven C.; Zhang, Xiaoye

2007-10-01

The Earth's climate is determined by a number of complex connected physical, chemical and biological processes occurring in the atmosphere, land and ocean. The radiative properties of the atmosphere, a major controlling factor of the Earth's climate, are strongly affected by the biophysical state of the Earth's surface and by the atmospheric abundance of a variety of trace constituents. These constituents include long-lived greenhouse gases (LLGHGs) such as carbon dioxide (CO{sub 2}), methane (CH{sub 4}) and nitrous oxide (N{sub 2}O), as well as other radiatively active constituents such as ozone and different types of aerosol particles. The composition of the atmosphere is determined by processes such as natural and anthropogenic emissions of gases and aerosols, transport at a variety of scales, chemical and microphysical transformations, wet scavenging and surface uptake by the land and terrestrial ecosystems, and by the ocean and its ecosystems. These processes and, more generally the rates of biogeochemical cycling, are affected by climate change, and involve interactions between and within the different components of the Earth system. These interactions are generally nonlinear and may produce negative or positive feedbacks to the climate system. An important aspect of climate research is to identify potential feedbacks and assess if such feedbacks could produce large and undesired responses to perturbations resulting from human activities. Studies of past climate evolution on different time scales can elucidate mechanisms that could trigger nonlinear responses to external forcing. The purpose of this chapter is to identify the major biogeochemical feedbacks of significance to the climate system, and to assess current knowledge of their magnitudes and trends. Specifically, this chapter will examine the relationships between the physical climate system and the land surface, the carbon cycle, chemically reactive atmospheric gases and aerosol

Biogeochemical malfunctioning in sediments beneath a deep-water fish farm.

Science.gov (United States)

Valdemarsen, Thomas; Bannister, Raymond J; Hansen, Pia K; Holmer, Marianne; Ervik, Arne

2012-11-01

We investigated the environmental impact of a deep water fish farm (190 m). Despite deep water and low water currents, sediments underneath the farm were heavily enriched with organic matter, resulting in stimulated biogeochemical cycling. During the first 7 months of the production cycle benthic fluxes were stimulated >29 times for CO(2) and O(2) and >2000 times for NH(4)(+), when compared to the reference site. During the final 11 months, however, benthic fluxes decreased despite increasing sedimentation. Investigations of microbial mineralization revealed that the sediment metabolic capacity was exceeded, which resulted in inhibited microbial mineralization due to negative feed-backs from accumulation of various solutes in pore water. Conclusions are that (1) deep water sediments at 8 °C can metabolize fish farm waste corresponding to 407 and 29 mmol m(-2) d(-1) POC and TN, respectively, and (2) siting fish farms at deep water sites is not a universal solution for reducing benthic impacts. Copyright © 2012 Elsevier Ltd. All rights reserved.

Relative Linkages of Stream Dissolved Oxygen with the Hydroclimatic and Biogeochemical Drivers across the Gulf Coast of U.S.A.

Science.gov (United States)

Gebreslase, A. K.; Abdul-Aziz, O. I.

2017-12-01

Dynamics of coastal stream water quality is influenced by a multitude of interacting environmental drivers. A systematic data analytics approach was employed to determine the relative linkages of stream dissolved oxygen (DO) with the hydroclimatic and biogeochemical variables across the Gulf Coast of U.S.A. Multivariate pattern recognition techniques of PCA and FA, alongside Pearson's correlation matrix, were utilized to examine the interrelation of variables at 36 water quality monitoring stations from USGS NWIS and EPA STORET databases. Power-law based partial least square regression models with a bootstrap Monte Carlo procedure (1000 iterations) were developed to estimate the relative linkages of dissolved oxygen with the hydroclimatic and biogeochemical variables by appropriately resolving multicollinearity (Nash-Sutcliffe efficiency = 0.58-0.94). Based on the dominant drivers, stations were divided into four environmental regimes. Water temperature was the dominant driver of DO in the majority of streams, representing most the northern part of Gulf Coast states. However, streams in the southern part of Texas and Florida showed a dominant pH control on stream DO. Further, streams representing the transition zone of the two environmental regimes showed notable controls of multiple drivers (i.e., water temperature, stream flow, and specific conductance) on the stream DO. The data analytics research provided profound insight to understand the dynamics of stream DO with the hydroclimatic and biogeochemical variables. The knowledge can help water quality managers in formulating plans for effective stream water quality and watershed management in the U.S. Gulf Coast. Keywords Data analytics, coastal streams, relative linkages, dissolved oxygen, environmental regimes, Gulf Coast, United States.

Development of Modal Aerosol Module in CAM5 for Biogeochemical Cycles

Energy Technology Data Exchange (ETDEWEB)

Liu, Xiaohong [Univ. of Wyoming, Laramie, WY (United States)

2017-11-18

This project aims at developing new capabilities for the Modal Aerosol Module in the DOE’s E3SM model with the applications to the global biogeochemical cycle. The impacts of the new developments on model simulations of clouds and climate will be examined. There are thee objectives for this project study: Implementing primary marine organic aerosols into the modal aerosol module (MAM) and investigate effects of primary marine organic aerosols on climate in E3SM; Implementing dust speciation in MAM and investigate the effect of dust species on mixed-phase clouds through indirect effects in E3SM; Writing papers documenting the new MAM developments (e.g., MAM4 documentation paper, marine organic aerosol paper, dust speciation); These objectives will be accomplished in collaborations with Drs. Phil Rasch, Steve Ghan, and Susannah Burrows at Pacific Northwest National Laboratory.

The Imbalance of Water in Nature as System

Science.gov (United States)

Kontar, V. A.; Imbalance of Water in Nature

2011-12-01

Consider some of the water-containing area. Choose some the factors which we consider important to the system. The system contains a system factors, and the external environment these factors doesn't contain. Between the system and the external environment must be some flows into the system, out of the system and along the border. If the flows into and out of the system are not equal, that means within the system exactly something is happening. But the equality of the flows into and out of the system does not mean that within the system nothing happens. It is extremely important to determine the time factor. Everything has a beginning and an end. Each factor has its own life from 0 to 1, as well as their watches. Thus that within the system and the environment at the same time are going a lot of the watches and each watch is going by their own pace. System-wide time is needed to describe the system as a whole and to be able to re-measure the individual time of each factor. It is also very important to identify each factor of the system, environment and border. Definition of each particular factor depends on the level of our knowledge. There are many examples where one factor was divided into several, and vice versa, several factors have combined in one or even disappear as a non-existent. Each factor is determined by specific people for reasons of convenience, the specific of tasks, the possible accuracy of measurement, available resources, etc. The development of the science and applications are going to the direction of the clearer separation of factors and the precision of their measurements. Now is extremely important to more clearly define the boundaries of systems, factors and the allowed accuracy of their measurements. With such a revision, many previously balanced situations become to the imbalance. There are many specific details for each case, but they do not change the basic approach described above. If not clearly resolved the questions listed above so

Using natural gas generation to improve power system efficiency in China

International Nuclear Information System (INIS)

Hu, Junfeng; Kwok, Gabe; Xuan, Wang; Williams, James H.; Kahrl, Fredrich

2013-01-01

China's electricity sector faces the challenge of managing cost increases, improving reliability, and reducing its environmental footprint even as operating conditions become more complex due to increasing renewable penetration, growing peak demand, and falling system load factors. Addressing these challenges will require changes in how power generation is planned, priced, and dispatched in China. This is especially true for natural gas generation, which is likely to play an important role in power systems worldwide as a flexible generation resource. Although natural gas is commonly perceived to be economically uncompetitive with coal in China, these perceptions are based on analysis that fails to account for the different roles that natural gas generation plays in power systems—baseload, load following, and peaking generation. Our analysis shows that natural gas generation is already cost-effective for meeting peak demand in China, resulting in improved capacity factors and heat rates for coal-fired generators and lower system costs. We find that the largest barrier to using natural gas for peaking generation in China is generation pricing, which could be addressed through modest reforms to support low capacity factor generation. - Highlights: • Using gas generation as a “capacity resource” in China could have multiple benefits. • Benefits include lower total costs, improved efficiency for coal generators. • Price reforms needed to support low capacity factor generation in China

Upwelling events, coastal offshore exchange, links to biogeochemical processes - Highlights from the Baltic Sea Science Congress

Directory of Open Access Journals (Sweden)

Bogdan Ołdakowski

2008-03-01

Full Text Available The Baltic Sea Science Congress was held at Rostock University, Germany, from 19 to 22 March 2007. In the session entitled"Upwelling events, coastal offshore exchange, links to biogeochemical processes" 20 presentations were given,including 7 talks and 13 posters related to the theme of the session.This paper summarises new findings of the upwelling-related studies reported in the session. It deals with investigationsbased on the use of in situ and remote sensing measurements as well as numerical modelling tools. The biogeochemicalimplications of upwelling are also discussed.Our knowledge of the fine structure and dynamic considerations of upwelling has increased in recent decades with the advent ofhigh-resolution modern measurement techniques and modelling studies. The forcing and the overall structure, duration and intensity ofupwelling events are understood quite well. However, the quantification of related transports and the contribution to the overall mixingof upwelling requires further research. Furthermore, our knowledge of the links between upwelling and biogeochemical processes is stillincomplete. Numerical modelling has advanced to the extent that horizontal resolutions of c. 0.5 nautical miles can now be applied,which allows the complete spectrum of meso-scale features to be described. Even the development of filaments can be describedrealistically in comparison with high-resolution satellite data.But the effect of upwelling at a basin scale and possible changes under changing climatic conditions remain open questions.

How Reducing was the Late Devonian Ocean? The Role of Extensive Expansion of Anoxia in Marine Biogeochemical Cycles of Redox Sensitive Metals.

Science.gov (United States)

Sahoo, S. K.; Jin, H.

2017-12-01

The evolution of Earth's biogeochemical cycles is intimately linked to the oxygenation of the oceans and atmosphere. The Late Devonian is no exception as its characterized with mass extinction and severe euxinia. Here we use concentrations of Molybdenum (Mo), Vanadium (V), Uranium (U) and Chromium (Cr) in organic rich black shales from the Lower Bakken Formation of the Williston Basin, to explore the relationship between extensive anoxia vs. euxinia and it's relation with massive release of oxygen in the ocean atmosphere system. XRF data from 4 core across the basin shows that modern ocean style Mo, U and Cr enrichments are observed throughout the Lower Bakken Formation, yet V is not enriched until later part of the formation. Given the coupling between redox-sensitive-trace element cycles and ocean redox, various models for Late Devonian ocean chemistry imply different effects on the biogeochemical cycling of major and trace nutrients. Here, we examine the differing redox behavior of molybdenum and vanadium under an extreme anoxia and relatively low extent of euxinia. The model suggests that Late Devonian was perhaps extensively anoxic- 40-50% compared to modern seafloor area, and a very little euxinia. Mo enrichments extend up to 500 p.p.m. throughout the section, representative of a modern reducing ocean. However, coeval low V enrichments only support towards anoxia, where anoxia is a source of V, and a sink for Mo. Our model suggests that the oceanic V reservoir is extremely sensitive to perturbations in the extent of anoxic condition, particularly during post glacial times.

Emergent Properties in Natural and Artificial Dynamical Systems

CERN Document Server

Aziz-Alaoui, M.A

2006-01-01

An important part of the science of complexity is the study of emergent properties arising through dynamical processes in various types of natural and artificial systems. This is the aim of this book, which is the outcome of a discussion meeting within the first European conference on complex systems. It presents multidisciplinary approaches for getting representations of complex systems and using different methods to extract emergent structures. This carefully edited book studies emergent features such as self organization, synchronization, opening on stability and robustness properties. Invariant techniques are presented which can express global emergent properties in dynamical and in temporal evolution systems. This book demonstrates how artificial systems such as a distributed platform can be used for simulation used to search emergent placement during simulation execution.

Hydrological mixing and geochemical processes characterization in an estuarine/mangrove system using environmental tracers in Babitonga Bay (Santa Catarina, Brazil)

Science.gov (United States)

Barros Grace, Virgínia; Mas-Pla, Josep; Oliveira Novais, Therezinha; Sacchi, Elisa; Zuppi, Gian Maria

2008-03-01

The hydrologic complex of Babitonga Bay (Brazil) forms a vast environmental complex where agriculture, shellfish farming, and industries coexist with a unique natural area of Atlantic rain forest and mangrove systems. The origin of different continental hydrological components, the environmental transition between saline and freshwaters, and the influence of the seasonality on Babitonga Bay waters are evaluated using isotopes and chemistry. End-member mixing analysis is used to explore hydrological processes in the bay. We show that a mixing of waters from different origins takes place in the bay modifying its chemical characteristics. Furthermore, biogeochemical processes related to well-developed mangrove systems are responsible for an efficient bromide uptake, which limit its use as a tracer as commonly used in non-biologically active environments. Seasonal behaviours are also distinguished from our datasets. The rainy season (April) provides a homogenization of the hydrological processes that is not seen after the dry season (October), when larger spatial differences appear and when the effects of biological processes on the bay hydrochemistry are more dynamic, or can be better recognized. Moreover, Cl/Br and stable isotopes of water molecule allow a neat definition of the hydrological and biogeochemical processes that control chemical composition in coastal and transition areas.

In-stream biogeochemical processes of a temporary river.

Science.gov (United States)

Tzoraki, Ourania; Nikolaidis, Nikolaos P; Amaxidis, Yorgos; Skoulikidis, Nikolaos Th

2007-02-15

A reach at the estuary of Krathis River in Greece was used to assess how in-stream processes alter its hydrologic and biogeochemical regime. Krathis River exhibited high annual flow variability and its transmission losses become significant, especially during the dry months. These transmission losses are enhanced in chemistry due to release of nutrients from river sediments. These fluxes are significant because they correspond to 11% of the dissolved inorganic nitrogen flux of the river. Release of nitrogen species was influenced by temperature, while release of phosphate was not because phosphate levels were below the equilibrium concentration. There is a significant amount of sediments with fine composition that create "hot spot" areas in the river reach. These sediments are mobilized during the first flush events in the fall carrying with them a significant load of nutrient and suspended matter to the coastal zone. The nutrient organic content of sediments was also significant and it was studied in terms of its mineralization capacity. The capacity for mineralization was influenced by soil moisture, exhibiting significant capacity even at moisture levels of 40%. Temporary rivers are sensitive ecosystems, vulnerable to climate changes. In-stream processes play a significant role in altering the hydrology and biogeochemistry of the water and its impacts to the coastal zone.

ROLE OF DISCRETE NATURE OF CHIP FORMATION AND NATURAL VIBRATIONS OF SYSTEM COMPONENTS IN CHATTER FORMATION DURING METAL CUTTING

Directory of Open Access Journals (Sweden)

A. K. M. Nurulamin

2010-05-01

Full Text Available In the present work a review of the existing theories of chatter formation has been conducted and the weaknesses of the most widely accepted ‘Regenerative Chatter theory’ in explaining various phenomena related to chatter formation have been identified. An attempt has been made in this work to determine the common causes of chatter formation in different metal cutting operations, namely, turning, thread cutting and end milling conducted on plain carbon steel AISI 1040. Experimental investigations have been conducted during the above types of machining processes to identify the marks of instability and chatter on the formed chips. It has been identified that in all the three machining operations the chips formed show a common type of discreteness in the form of secondary saw teeth, which appear at the free edge of the chip. Mechanism of formation of these teeth has been studied and the frequencies of their formation have been determined for different cutting conditions. Apart from the secondary saw teeth primary saw teeth have also been identified at the main section of the chip and their frequencies were also determined. At the same time the natural vibrations of the main system components have been identified and the acceleration amplitudes at the prominent natural frequencies during actual machining were recoded using a dedicated vibration monitoring system. The frequencies of secondary chip serration and the natural frequencies of the system components were plotted against cutting speed. Acceleration amplitudes at the prominent natural frequencies were also plotted separately against cutting force. Based on comparison and analysis of these two frequency and amplitude graphs it was concluded that chatter (vibration with relatively high amplitude appears in the system when the frequency of secondary saw teeth approaches values equal to half or integer multiple of a prominent natural frequency of the system resulting in resonance. In the

The effect of gold mining and processing on biogeochemical cycles in Muteh area, Isfahan province, Iran

Science.gov (United States)

Keshavarzi, B.; Moore, F.

2009-04-01

content in all analysed samples is higher than the published standard levels. The most probable source for As contamination is the high concentration of this element in tap water and nutrients in all trophic levels. As content was also found to be high in livestock's wool and hair. Arsenic toxicity is probably the main reason for the observed hyperpigmentation and keratosis of palms and soles seen in the villagers. The high concentration of arsenic in various biogeochemical cycles in the Muteh region is the result of the geological nature of the Muteh district enhanced by gold mining and processing which plays an active role in the remobilization of this elements.

Contrasting biogeochemical responses of ENSO induced upwelling variability in the Humboldt Current System

Science.gov (United States)

Franco, Ana C.; Gruber, Nicolas; Münnich, Matthias

2017-04-01

The Humboldt Current System (HCS) is one of the most productive ecosystems in the world. This high productivity is supported by a large input of nutrients from the subsurface layers to the surface due to year-round upwelling. However, upwelling also supplies waters with low pH and low aragonite saturation state potentially affecting many organisms, especially those that calcify. The influence, extent and source of upwelled water vary substantially on interannual timescales in association with the El Niño/Southern Oscillation (ENSO) phenomenon, generating natural contrasting responses on the biogeochemistry of this system. Here we analyze these responses using an eddy resolving, basin-scale ocean model that covers the whole Pacific Ocean with high resolution (4 km) on the west coast of South America. We performed a simulation of the last 30 years (hindcast simulation) that allows us to investigate the influence of at least eight El Niño episodes and eight La Niña episodes on productivity variations and changes in oxygen concentration and aragonite saturation state. An absolute change in surface omega aragonite of almost 2 units, as well as an absolute change of the aragonite saturation depth of 200 m result from the change of an El Niño phase to a La Niña phase. This variability is on the same order of magnitude as the projected change in the aragonite saturation state in a centennial timescale. During La Niña events, a lower aragonite saturation state values and reduced oxygen concentration in the surface layer are a direct consequence of enhanced upwelling and increased net primary productivity. The opposite is true during El Niño events, where high values of omega aragonite occur in concordance with extraordinarily low net primary productivity values.

Failure modes and natural control time for distributed vibrating systems

International Nuclear Information System (INIS)

Reid, R.M.

1994-01-01

The eigenstructure of the Gram matrix of frequency exponentials is used to study linear vibrating systems of hyperbolic type with distributed control. Using control norm as a practical measure of controllability and the vibrating string as a prototype, it is demonstrated that hyperbolic systems have a natural control time, even when only finitely many modes are excited. For shorter control times there are identifiable control failure modes which can be steered to zero only with very high cost in control norm. Both natural control time and the associated failure modes are constructed for linear fluids, strings, and beams, making note of the essential algorithms and Mathematica code, and displaying results graphically

Biogeochemical Cycles for Combining Chemical Knowledge and ESD Issues in Greek Secondary Schools Part II: Assessing the Impact of the Intervention

Science.gov (United States)

Koutalidi, Sophia; Psallidas, Vassilis; Scoullos, Michael

2016-01-01

In searching for effective ways to combine science/chemical education with EE/ESD, new didactic materials were designed and produced focussing on biogeochemical cycles and their connection to sustainable development. The materials were experimentally applied in 16 Greek schools under the newly introduced compulsory "school project" which…

Application of a SEEK filter to a 1D biogeochemical model of the Ligurian Sea: Twin experiments and real data assimilation

NARCIS (Netherlands)

Raick, C.; Alvera-Azcarate, A.; Barth, A.; Brankart, J.-M.; Soetaert, K.E.R.; Grégoire, M.

2007-01-01

The Singular Evolutive Extended Kalman (SEEK) filter has been implemented to assimilate in-situ data in a 1D coupled physical-ecosystem model of the Ligurian Sea. The biogeochemical model describes the partly decoupled nitrogen and carbon cycles of the pelagic food web. The GHER hydrodynamic model

Regional impacts of iron-light colimitation in a global biogeochemical model

Science.gov (United States)

Galbraith, E. D.; Gnanadesikan, A.; Dunne, J. P.; Hiscock, M. R.

2010-03-01

Laboratory and field studies have revealed that iron has multiple roles in phytoplankton physiology, with particular importance for light-harvesting cellular machinery. However, although iron-limitation is explicitly included in numerous biogeochemical/ecosystem models, its implementation varies, and its effect on the efficiency of light harvesting is often ignored. Given the complexity of the ocean environment, it is difficult to predict the consequences of applying different iron limitation schemes. Here we explore the interaction of iron and nutrient cycles in an ocean general circulation model using a new, streamlined model of ocean biogeochemistry. Building on previously published parameterizations of photoadaptation and export production, the Biogeochemistry with Light Iron Nutrients and Gasses (BLING) model is constructed with only four explicit tracers but including macronutrient and micronutrient limitation, light limitation, and an implicit treatment of community structure. The structural simplicity of this computationally-inexpensive model allows us to clearly isolate the global effect that iron availability has on maximum light-saturated photosynthesis rates vs. the effect iron has on photosynthetic efficiency. We find that the effect on light-saturated photosynthesis rates is dominant, negating the importance of photosynthetic efficiency in most regions, especially the cold waters of the Southern Ocean. The primary exceptions to this occur in iron-rich regions of the Northern Hemisphere, where high light-saturated photosynthesis rates allow photosynthetic efficiency to play a more important role. In other words, the ability to efficiently harvest photons has little effect in regions where light-saturated growth rates are low. Additionally, we speculate that the phytoplankton cells dominating iron-limited regions tend to have relatively high photosynthetic efficiency, due to reduced packaging effects. If this speculation is correct, it would imply that

Regional impacts of iron-light colimitation in a global biogeochemical model

Directory of Open Access Journals (Sweden)

E. D. Galbraith

2010-03-01

Full Text Available Laboratory and field studies have revealed that iron has multiple roles in phytoplankton physiology, with particular importance for light-harvesting cellular machinery. However, although iron-limitation is explicitly included in numerous biogeochemical/ecosystem models, its implementation varies, and its effect on the efficiency of light harvesting is often ignored. Given the complexity of the ocean environment, it is difficult to predict the consequences of applying different iron limitation schemes. Here we explore the interaction of iron and nutrient cycles in an ocean general circulation model using a new, streamlined model of ocean biogeochemistry. Building on previously published parameterizations of photoadaptation and export production, the Biogeochemistry with Light Iron Nutrients and Gasses (BLING model is constructed with only four explicit tracers but including macronutrient and micronutrient limitation, light limitation, and an implicit treatment of community structure. The structural simplicity of this computationally-inexpensive model allows us to clearly isolate the global effect that iron availability has on maximum light-saturated photosynthesis rates vs. the effect iron has on photosynthetic efficiency. We find that the effect on light-saturated photosynthesis rates is dominant, negating the importance of photosynthetic efficiency in most regions, especially the cold waters of the Southern Ocean. The primary exceptions to this occur in iron-rich regions of the Northern Hemisphere, where high light-saturated photosynthesis rates allow photosynthetic efficiency to play a more important role. In other words, the ability to efficiently harvest photons has little effect in regions where light-saturated growth rates are low. Additionally, we speculate that the phytoplankton cells dominating iron-limited regions tend to have relatively high photosynthetic efficiency, due to reduced packaging effects. If this speculation is correct

Implications of meltwater pulse events for soil biology and biogeochemical cycling in a polar desert

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Becky A. Ball

2011-12-01

Full Text Available The McMurdo Dry Valleys are one of the most arid environments on Earth. Over the soil landscape for the majority of the year, biological and ecosystem processes in the dry valleys are constrained by the low temperatures and limited availability of water. The prevalence of these physical limitations in controlling biological and ecosystem processes makes the dry valleys a climate-sensitive system, poised to experience substantial changes following projected future warming. Short-duration increases in summer temperatures are associated with pulses of water from melting ice reserves, including glaciers, snow and permafrost. Such pulses alter soil geochemistry by mobilizing and redistributing soil salts (via enhanced weathering, solubility and mobility, which can alter habitat suitability for soil organisms. Resulting changes in soil community composition or distribution may alter the biogeochemical processes in which they take part. Here, we review the potential impacts of meltwater pulses and present new field data documenting instances of meltwater pulse events that result from different water sources and hydrological patterns, and discuss their potential influence on soil biology and biogeochemistry. We use these examples to discuss the potential impacts of future climate change on the McMurdo Dry Valley soil ecosystem.

Conflicting Epistemologies and Inference in Coupled Human and Natural Systems

Science.gov (United States)

Garcia, M. E.

2017-12-01

Last year, I presented a model that projects per capita water consumption based on changes in price, population, building codes, and water stress salience. This model applied methods from hydrological science and engineering to relationships both within and beyond their traditional scope. Epistemologically, the development of mathematical models of natural or engineered systems is objectivist while research examining relationships between observations, perceptions and action is commonly constructivist or subjectivist. Drawing on multiple epistemologies is common in, and perhaps central to, the growing fields of coupled human and natural systems, and socio-hydrology. Critically, these philosophical perspectives vary in their view of the nature of the system as mechanistic, adaptive or constructed, and the split between aleatory and epistemic uncertainty. Interdisciplinary research is commonly cited as a way to address the critical and domain crossing challenge of sustainability as synthesis across perspectives can offer a more comprehensive view of system dynamics. However, combining methods and concepts from multiple ontologies and epistemologies can introduce contradictions into the logic of inference. These contractions challenge the evaluation of research products and the implications for practical application of research findings are not fully understood. Reflections on the evaluation, application, and generalization of the water consumption model described above are used to ground these broader questions and offer thoughts on the way forward.

Studies of natural analogues and geological systems. Their importance to performance assessment

International Nuclear Information System (INIS)

Brandberg, F.; Grundfelt, B.; Hoeglund, L.O.; Skagius, K.; Karlsson, Fred; Smellie, J.

1992-04-01

This review has involved studies of natural analogues and natural geological systems leading to the identification and quantification of processes and features of importance to the performance and safety of repositories for radioactive waste. The features and processes selected for the study comprise general geochemical issues related to the performance of the near- and of the far-field, the performance and durability of construction materials and the effects of glaciation. For each of these areas a number of potentially important processes for repository performance have been described, and evidence for their existence, as well as quantification of parameters of models describing the processes, have been sought from major natural analogue studies and site investigations. The review has aimed at covering a relatively broad range of issues at the expense of in-depth analysis. The quantitative data presented are in most cases compilations of data from the literature; in a few cases results of evaluations made within the current project are included. The results of the study show that studies of natural analogues and natural geological systems have provided significant information regarding many issues of importance to repository performance. In several cases the evidence from natural analogues has demonstrated that processes assumed to take place in repositories actually occur in natural systems or under conditions similar to those predicted to prevail in a future repository. One example of such a process is coprecipitation of fission products and ferric oxyhydroxides as an analogue to corrosion products from a steel canister. In addition, the study of concentration gradients of uranium and other trace substances in the rock surrounding groundwater conduits confirm that matrix diffusion occurs in nature and that the diffusivities in the rock matrix measured in the laboratory are consistent with the observations in nature

Biogeochemical Modeling of the Second Rise of Oxygen

Science.gov (United States)

Smith, M. L.; Catling, D.; Claire, M.; Zahnle, K.

2014-03-01

The rise of atmospheric oxygen set the tempo for the evolution of complex life on Earth. Oxygen levels are thought to have increased in two broad steps: one step occurred in the Archean ~ 2.45 Ga (the Great Oxidation Event or GOE), and another step occured in the Neoproterozoic ~750-580 Ma (the Neoprotoerozoic Oxygenation Event or NOE). During the NOE, oxygen levels increased from ~1-10% of the present atmospheric level (PAL) (Holland, 2006), to ~15% PAL in the late Neoproterozoic, to ~100% PAL later in the Phanerozoic. Complex life requires O2, so this transition allowed complex life to evolve. We seek to understand what caused the NOE. To explore causes for the NOE, we build upon the biogeochemical model of Claire et al. (2006), which calculates the redox evolution of the atmosphere, ocean, biosphere, and crust in the Archean through to the early Proterozoic. In this model, the balance between oxygenconsuming and oyxgen-producing fluxes evolves over time such that at ~2.4 Ga, the rapidly acting sources of oxygen outweigh the rapidly-acting sinks. Or, in other words, at ~2.4 Ga, the flux of oxygen from organic carbon burial exceeds the sinks of oxygen from reaction with reduced volcanic and metamoprphic gases. The model is able to drive oxygen levels to 1-10% PAL in the Proterozoic; however, the evolving redox fluxes in the model cannot explain how oxygen levels pushed above 1-10% in the late Proterozoic. The authors suggest that perhaps another buffer, such as sulfur, is needed to describe Proterozoic and Phanerozoic redox evolution. Geologic proxies show that in the Proterozoic, up to 10% of the deep ocean may have been sulfidic. With this ocean chemistry, the global sulfur cycle would have worked differently than it does today. Because the sulfur and oxygen cycles interact, the oxygen concentration could have permanently changed due to an evolving sulfur cycle (in combination with evolving redox fluxes associated with other parts of the oxygen cycle and carbon

MODELING THE PROCESSES OF CONTROL OF COMPLEXLY ORGANIZED “NATURE-SOCIETY” SYSTEMS

Directory of Open Access Journals (Sweden)

S. L. Turkov

2017-01-01

Full Text Available The report highlights some questions of modeling the processes of control for “naturesociety” systems. The purpose and common direction for using the results is to work out the “human-machine” systems of planning (or support for making the optimum decisions during realization of “Sustainable Development” conception as the official doctrine for the development of Russia (1996.The research has been based on: the new paradigm of system presentation of the world, the theory of “noosphere” by P.T. de Chardin, E. Le Roy, V.I. Vernadsky, “new theory of entropy” by A.N. Panchenkov (1999. The object of research is the class of Active Complexly organized “nature-society” systems; the subject – concepts of “balance” for integrated systems and Conception of “Sustainable Development”; the methods for researching are the Game-Theory modeling, the “Game against Nature”, coalition, cooperation etc according to condition for staging problems, games. During modeling this ensures the full integration of all accessible today natural sciences knowledge, as well as possibility to carry out computing operations of situation control for “naturesociety” systems.The research foresees execution of the following five stages of the problem study. Information modeling for possible structures of object (the starting field of knowledge is “geoecology”. The system analysis and synthesis of permissible dynamics and outside conditions of its development. The mathematical modeling for natural resources used at regional and local levels. The technological design work (the GIS-, GRID-technologies and artificial intellect systems for control of making decisions. The numerical experiments and checking the efficiency of models and algorithms. Methodically they are presented as a consecutively connected aggregate of “structure”, “functional” and “normative” models. A new – “geosystem” – approach offered to research the

Lacustrine wetland in an agricultural catchment: nitrogen removal and related biogeochemical processes

Directory of Open Access Journals (Sweden)

R. Balestrini

2008-03-01

Full Text Available The role of specific catchment areas, such as the soil-river or lake interfaces, in removing or buffering the flux of N from terrestrial to aquatic ecosystems is globally recognized but the extreme variability of microbiological and hydrological processes make it difficult to predict the extent to which different wetlands function as buffer systems. In this paper we evaluate the degree to which biogeochemical processes in a lacustrine wetland are responsible for the nitrate removal from ground waters feeding Candia Lake (Northern Italy. A transect of 18 piezometers was installed perpendicular to the shoreline, in a sub-unit formed by 80 m of poplar plantation, close to a crop field and 30 m of reed swamp. The chemical analysis revealed a drastic NO₃^–-N ground water depletion from the crop field to the lake, with concentrations decreasing from 15–18 mg N/l to the detection limit within the reeds. Patterns of Cl^–, SO₄^2–, O₂, NO₂^–-N, HCO₃^– and DOC suggest that the metabolic activity of bacterial communities, based on the differential use of electron donors and acceptors in redox reactions is the key function of this system. The significant inverse relationship found between NO₃^–-N and HCO₃^– is a valuable indicator of the denitrification activity. The pluviometric regime, the temperature, the organic carbon availability and the hydrogeomorphic properties are the main environmental factors affecting the N transformations in the studied lacustrine ecosystem.

Predominant natural red-shift of quasi-conservative nonlinear systems

International Nuclear Information System (INIS)

Pugno, Nicola Maria; Carpinteri, Alberto; Delsanto, Pier Paolo

2009-01-01

Recent discoveries of nonclassical nonlinear phenomena are attracting a large interest in the scientific community, especially in material science. In spite of this, the natural frequency shift related to the appearance of such phenomena remains partially unclear. In this paper, we apply the general and only recently developed Interaction Box Formalism for investigating if a universality in the natural frequency shift of quasi-conservative nonlinear systems exists. Such universality clearly emerges as a rupture in the symmetry, usually leading to a red-shift, quantifiable as a function of the higher- and sub-harmonic generation.

Are Human and Natural Systems Decoupling?

Science.gov (United States)

Ehrlich, P. R.; Ehrlich, A. H.

2012-12-01

Typically, studies of coupled human and natural systems focus on reciprocating interactions and feedbacks between social systems and their biophysical environments. A major challenge today for CHANS scholars is to determine whether significant coupling remains or whether society is simply plunging ahead without reacting effectively to the deterioration of the environment. Thresholds for serious climate disruption are passing, toxification of Earth is proceeding apace and producing worrying symptoms, losses of vital biodiversity are at a 65 million-year high with serious consequences for ecosystem services, the epidemiological environment is deteriorating and a race is building to control water flows and extract the last high-quality resources, increasing the chances of ending civilization in an environment-wrecking nuclear war. The social system has attempted to respond to this perfect storm of problems. In the 1960s, building on much earlier work, scientists began assessing the consequences of an ever-growing human population and expanding consumption, overuse of pesticides, radioactive fallout, air and water pollution, and other environmental issues - and to recommend ameliorative steps. In the mid-1980s, biologists formed the discipline of conservation biology with the explicit purpose of stemming the hemorrhage of biodiversity. In the late 1980s, perhaps the single most important reaction to the worsening environmental situation was the development of the Montreal Protocol to preserve the vital stratospheric ozone layer. Around the same time, it dawned on the scientific community that climate disruption was going to be more immediate and dangerous than previously thought, but attempts by the world community to take mitigating steps have been pathetic. Action to deal with other dimensions of the environmental dilemma has been utterly inadequate. To see the growing disconnect, one only has to consider the attention paid in public discourse to the relatively

49 CFR 571.303 - Standard No. 303; Fuel system integrity of compressed natural gas vehicles.

Science.gov (United States)

2010-10-01

... compressed natural gas vehicles. 571.303 Section 571.303 Transportation Other Regulations Relating to... system integrity of compressed natural gas vehicles. S1. Scope. This standard specifies requirements for the integrity of motor vehicle fuel systems using compressed natural gas (CNG), including the CNG fuel...

Global early warning systems for natural hazards: systematic and people-centred.

Science.gov (United States)

Basher, Reid

2006-08-15

To be effective, early warning systems for natural hazards need to have not only a sound scientific and technical basis, but also a strong focus on the people exposed to risk, and with a systems approach that incorporates all of the relevant factors in that risk, whether arising from the natural hazards or social vulnerabilities, and from short-term or long-term processes. Disasters are increasing in number and severity and international institutional frameworks to reduce disasters are being strengthened under United Nations oversight. Since the Indian Ocean tsunami of 26 December 2004, there has been a surge of interest in developing early warning systems to cater to the needs of all countries and all hazards.

The immune system, natural autoantibodies and general homeostasis in health and disease.

Science.gov (United States)

Poletaev, A; Boura, P

2011-10-01

It is generally accepted that the destination of the immune system is not only to discriminate between self and non-self but also to mount responses against non-self. During the last decades, it became evident that weak self-reactivity is a necessary condition for immune homeostasis. Natural self reactivity and the internal image created by autoantibodies, participate greatly to the maintenance of homeostasis. Under conditions of increased or altered antigenic pressure, the homeostatic status is disrupted and the organism becomes vulnerable to the emergence of diseases. "Immunculus" is the self-reactive and interconnected entity of the immune system, provided by a complicated network of natural autoantibobies of different specificity, as a mosaic picture. Quantitative changes in each part of the image are related to variations of expression of relative antigens. The immune system takes in account image information from the continuous screening of the antigenic status and compares between presented state and the desired (optimal) one. Substantial and prolonged deviations from the optimal state, triggers the induction of compensatory and reparative processes, aiming to restore molecular and functional homeostasis. So, natural autoimmunity through the ability of natural a-Abs to induce mechanisms of natural and acquired immunity, aims to prevent pathogenic processes and maintain or restore health status.

Status of the IAEA coordinated research project on natural circulation phenomena, modelling, and reliability of passive systems that utilize natural circulation

International Nuclear Information System (INIS)

Reyes, J.N. Jr.; Cleveland, J.; Aksan, N.

2004-01-01

The International Atomic Energy Agency (IAEA) has established a Coordinated Research Project (CRP) titled ''Natural Circulation Phenomena, Modelling and Reliability of Passive Safety Systems that Utilize Natural Circulation. '' This work has been organized within the framework of the IAEA Department of Nuclear Energy's Technical Working Groups for Advanced Technologies for Light Water Reactors and Heavy Water Reactors (the TWG-LWR and the TWG-HWR). This CRP is part of IAEA's effort to foster international collaborations that strive to improve the economic performance of future water-cooled nuclear power plants while meeting stringent safety requirements. Thus far, IAEA has established 12 research agreements with organizations from industrialized Member States and 3 research contracts with organizations from developing Member States. The objective of the CRP is to enhance our understanding of natural circulation phenomena in water-cooled reactors and passive safety systems. The CRP participants are particularly interested in establishing a natural circulation and passive safety system thermal hydraulic database that can be used to benchmark computer codes for advanced reactor systems design and safety analysis. An important aspect of this CRP relates to developing methodologies to assess the reliability of passive safety systems in advanced reactor designs. This paper describes the motivation and objectives of the CRP, the research plan, and the role of each of the participating organizations. (author)

Environmental and biogeochemical changes following a decade's reclamation in the Dapeng (Tapong) Bay, southwestern Taiwan

Science.gov (United States)

Hung, J.-J.; Huang, W.-C.; Yu, C.-S.

2013-09-01

This study examines the environmental and biogeochemical changes in Dapeng (formerly spelled Tapong) Bay, a semi-enclosed coastal lagoon in southwestern Taiwan, after two major reclamation works performed between 1999 and 2010. The lagoon was largely occupied by oyster culture racks and fish farming cages before December, 2002. Substantial external inputs of nutrients and organic carbon and the fairly long water exchange time (τ) (10 ± 2 days) caused the lagoon to enter a eutrophic state, particularly at the inner lagoon, which directly received nutrient inputs. However, the entire lagoon showed autotrophic, and the estimated net ecosystem production (NEP) during the first stage was 5.8 mol C m-2 yr-1. After January, 2003, the aquaculture structures were completely removed, and the τ decreased to 6 ± 2 days. The annual mean concentrations of dissolved oxygen increased, and nutrients decreased substantially, likely due to improved water exchange, absence of feeding and increased biological utilization. The NEP increased 37% to 7.7 mol C m-2 yr-1 after structure removal. The second reclamation work beginning from July, 2006, focused on establishing artificial wetlands for wastewater treatment and on dredging bottom sediment. Although the τ did not change significantly (8 ± 3 days), substantial decreases in nutrient concentrations and dissolved organic matter continued. The NEP (14.3 mol C m-2 yr-1) increased 85% compared to that in the second stage. The data suggest that the reclamations substantially improved water quality, carbon and nutrient biogeochemical processes and budgets in this semi-enclosed ecosystem.

Biogeochemical Impact of Snow Cover and Cyclonic Intrusions on the Winter Weddell Sea Ice Pack

Science.gov (United States)

Tison, J.-L.; Schwegmann, S.; Dieckmann, G.; Rintala, J.-M.; Meyer, H.; Moreau, S.; Vancoppenolle, M.; Nomura, D.; Engberg, S.; Blomster, L. J.; Hendrickx, S.; Uhlig, C.; Luhtanen, A.-M.; de Jong, J.; Janssens, J.; Carnat, G.; Zhou, J.; Delille, B.

2017-12-01

Sea ice is a dynamic biogeochemical reactor and a double interface actively interacting with both the atmosphere and the ocean. However, proper understanding of its annual impact on exchanges, and therefore potentially on the climate, notably suffer from the paucity of autumnal and winter data sets. Here we present the results of physical and biogeochemical investigations on winter Antarctic pack ice in the Weddell Sea (R. V. Polarstern AWECS cruise, June-August 2013) which are compared with those from two similar studies conducted in the area in 1986 and 1992. The winter 2013 was characterized by a warm sea ice cover due to the combined effects of deep snow and frequent warm cyclones events penetrating southward from the open Southern Ocean. These conditions were favorable to high ice permeability and cyclic events of brine movements within the sea ice cover (brine tubes), favoring relatively high chlorophyll-a (Chl-a) concentrations. We discuss the timing of this algal activity showing that arguments can be presented in favor of continued activity during the winter due to the specific physical conditions. Large-scale sea ice model simulations also suggest a context of increasingly deep snow, warm ice, and large brine fractions across the three observational years, despite the fact that the model is forced with a snowfall climatology. This lends support to the claim that more severe Antarctic sea ice conditions, characterized by a longer ice season, thicker, and more concentrated ice are sufficient to increase the snow depth and, somehow counterintuitively, to warm the ice.

A system for tritium analysis in natural water

International Nuclear Information System (INIS)

Mozeto, A.A.

1977-01-01

A method for the analysis, by scintillation counting, of tritium in natural water enriched electrolytically, is presented. The characteristics of the proposed system are indicated by experimental parameters, and by the performance obtained in the analysis of rain and under ground waters. An evaluation of the precison and reproducibility of the measurements is also made [pt

Water, Energy, and Biogeochemical Model (WEBMOD), user’s manual, version 1

Science.gov (United States)

Webb, Richard M.T.; Parkhurst, David L.

2017-02-08

The Water, Energy, and Biogeochemical Model (WEBMOD) uses the framework of the U.S. Geological Survey (USGS) Modular Modeling System to simulate fluxes of water and solutes through watersheds. WEBMOD divides watersheds into model response units (MRU) where fluxes and reactions are simulated for the following eight hillslope reservoir types: canopy; snowpack; ponding on impervious surfaces; O-horizon; two reservoirs in the unsaturated zone, which represent preferential flow and matrix flow; and two reservoirs in the saturated zone, which also represent preferential flow and matrix flow. The reservoir representing ponding on impervious surfaces, currently not functional (2016), will be implemented once the model is applied to urban areas. MRUs discharge to one or more stream reservoirs that flow to the outlet of the watershed. Hydrologic fluxes in the watershed are simulated by modules derived from the USGS Precipitation Runoff Modeling System; the National Weather Service Hydro-17 snow model; and a topography-driven hydrologic model (TOPMODEL). Modifications to the standard TOPMODEL include the addition of heterogeneous vertical infiltration rates; irrigation; lateral and vertical preferential flows through the unsaturated zone; pipe flow draining the saturated zone; gains and losses to regional aquifer systems; and the option to simulate baseflow discharge by using an exponential, parabolic, or linear decrease in transmissivity. PHREEQC, an aqueous geochemical model, is incorporated to simulate chemical reactions as waters evaporate, mix, and react within the various reservoirs of the model. The reactions that can be specified for a reservoir include equilibrium reactions among water; minerals; surfaces; exchangers; and kinetic reactions such as kinetic mineral dissolution or precipitation, biologically mediated reactions, and radioactive decay. WEBMOD also simulates variations in the concentrations of the stable isotopes deuterium and oxygen-18 as a result of

Pb, Cd, Cu and Zn biogeochemical behaviour and biological transfer processes in the Northwestern Mediterranean

International Nuclear Information System (INIS)

Nicolas, E.; Marty, J.C.; Miquel, J.C.; Fowler, S.W.

1999-01-01

Cd, Pb, Cu and Zn concentrations were determined in planktonic organisms (Salps, copepods), their associated faecal pellets and in particles collected at 200 and 2000 m depth in sediment traps moored in the Ligurian Sea. Al and P were also measured and taken as tracers of lithogenic and biogenic components, respectively. The aim of this work was to determine the fluxes of trace metals in the Ligurian Sea and their variations with depth, and to to assess the biogeochemical behaviour of elements having, for some of them, an anthropogenic origin, by the study of biologically-mediated uptake and removal processes

Geochemical variability of soils and biogeochemical variability of plants in the Piceance Basin, Colorado

Science.gov (United States)

Tuttle, M.L.; Severson, R.C.; Dean, W.E.; Klusman, R.W.

1986-01-01

Geochemical baselines for native soils and biogeochemical baselines for plants in the Piceance basin provide data that can be used to assess geochemical and biogeochemical effects of oil-shale development, monitor changes in the geochemical and biogeochemical environment during development, and assess the degree of success of rehabilitation of native materials after development. Baseline values for 52 properties in native soils, 15 properties in big sagebrush, and 13 properties in western wheatgrass were established. Our Study revealed statistically significant regional variations of the following properties across the basin: in soil&-aluminum, cobalt, copper, iron, manganese, sodium, nickel, phosphorus, lead, scandium, titanium, vanadium, zinc, organic and total carbon, pH, clay, dolomite, sodium feldspar, and DTPA-extractable calcium, cadmium, iron, potassium, manganese, nickel, phosphorus, yttrium, and zinc; in big sagebrush-barium, calcium, copper, magnesium, molybdenum, sodium, strontium, zinc, and ash; and in western wheatgrass-boron, barium, calcium, magnesium, manganese, molybdenum, strontium, zinc, and ash. These variations show up as north-south trends across the basin, or they reflect differences in elevation, hydrology, and soil parent material. Baseline values for properties that do not have statistically significant regional variations can be represented by geometric means and deviations calculated from all values within the basin. Chemical and mineralogical analyses of soil and chemical analyses of western wheatgrass samples from Colorado State University's experimental revegetation plot at Anvil Points provide data useful in assessing potential effects on soil and plant properties when largescale revegetation operations begin. The concentrations of certain properties are related to the presence of topsoil over spent shale in the lysimeters. In soils, calcium, fluorine, lithium, magnesium, sodium, phosphorus, strontium, carbonate and total carbon

EPOCA/EUR-OCEANS data compilation on the biological and biogeochemical responses to ocean acidification

Directory of Open Access Journals (Sweden)

A.-M. Nisumaa

2010-07-01

Full Text Available The uptake of anthropogenic CO₂ by the oceans has led to a rise in the oceanic partial pressure of CO₂, and to a decrease in pH and carbonate ion concentration. This modification of the marine carbonate system is referred to as ocean acidification. Numerous papers report the effects of ocean acidification on marine organisms and communities but few have provided details concerning full carbonate chemistry and complementary observations. Additionally, carbonate system variables are often reported in different units, calculated using different sets of dissociation constants and on different pH scales. Hence the direct comparison of experimental results has been problematic and often misleading. The need was identified to (1 gather data on carbonate chemistry, biological and biogeochemical properties, and other ancillary data from published experimental data, (2 transform the information into common framework, and (3 make data freely available. The present paper is the outcome of an effort to integrate ocean carbonate chemistry data from the literature which has been supported by the European Network of Excellence for Ocean Ecosystems Analysis (EUR-OCEANS and the European Project on Ocean Acidification (EPOCA. A total of 185 papers were identified, 100 contained enough information to readily compute carbonate chemistry variables, and 81 data sets were archived at PANGAEA – The Publishing Network for Geoscientific & Environmental Data. This data compilation is regularly updated as an ongoing mission of EPOCA.

Data access: http://doi.pangaea.de/10.1594/PANGAEA.735138

Environmental and natural resource implications of sustainable urban infrastructure systems

Science.gov (United States)

Bergesen, Joseph D.; Suh, Sangwon; Baynes, Timothy M.; Kaviti Musango, Josephine

2017-12-01

As cities grow, their environmental and natural resource footprints also tend to grow to keep up with the increasing demand on essential urban services such as passenger transportation, commercial space, and thermal comfort. The urban infrastructure systems, or socio-technical systems providing these services are the major conduits through which natural resources are consumed and environmental impacts are generated. This paper aims to gauge the potential reductions in environmental and resources footprints through urban transformation, including the deployment of resource-efficient socio-technical systems and strategic densification. Using hybrid life cycle assessment approach combined with scenarios, we analyzed the greenhouse gas (GHG) emissions, water use, metal consumption and land use of selected socio-technical systems in 84 cities from the present to 2050. The socio-technical systems analyzed are: (1) bus rapid transit with electric buses, (2) green commercial buildings, and (3) district energy. We developed a baseline model for each city considering gross domestic product, population density, and climate conditions. Then, we overlaid three scenarios on top of the baseline model: (1) decarbonization of electricity, (2) aggressive deployment of resource-efficient socio-technical systems, and (3) strategic urban densification scenarios to each city and quantified their potentials in reducing the environmental and resource impacts of cities by 2050. The results show that, under the baseline scenario, the environmental and natural resource footprints of all 84 cities combined would increase 58%-116% by 2050. The resource-efficient scenario along with strategic densification, however, has the potential to curve down GHG emissions to 17% below the 2010 level in 2050. Such transformation can also limit the increase in all resource footprints to less than 23% relative to 2010. This analysis suggests that resource-efficient urban infrastructure and decarbonization of

Response of O2 and pH to ENSO in the California Current System in a high-resolution global climate model

Science.gov (United States)

Turi, Giuliana; Alexander, Michael; Lovenduski, Nicole S.; Capotondi, Antonietta; Scott, James; Stock, Charles; Dunne, John; John, Jasmin; Jacox, Michael

2018-02-01

Coastal upwelling systems, such as the California Current System (CalCS), naturally experience a wide range of O2 concentrations and pH values due to the seasonality of upwelling. Nonetheless, changes in the El Niño-Southern Oscillation (ENSO) have been shown to measurably affect the biogeochemical and physical properties of coastal upwelling regions. In this study, we use a novel, high-resolution global climate model (GFDL-ESM2.6) to investigate the influence of warm and cold ENSO events on variations in the O2 concentration and the pH of the CalCS coastal waters. An assessment of the CalCS response to six El Niño and seven La Niña events in ESM2.6 reveals significant variations in the response between events. However, these variations overlay a consistent physical and biogeochemical (O2 and pH) response in the composite mean. Focusing on the mean response, our results demonstrate that O2 and pH are affected rather differently in the euphotic zone above ˜ 100 m. The strongest O2 response reaches up to several hundreds of kilometers offshore, whereas the pH signal occurs only within a ˜ 100 km wide band along the coast. By splitting the changes in O2 and pH into individual physical and biogeochemical components that are affected by ENSO variability, we found that O2 variability in the surface ocean is primarily driven by changes in surface temperature that affect the O2 solubility. In contrast, surface pH changes are predominantly driven by changes in dissolved inorganic carbon (DIC), which in turn is affected by upwelling, explaining the confined nature of the pH signal close to the coast. Below ˜ 100 m, we find conditions with anomalously low O2 and pH, and by extension also anomalously low aragonite saturation, during La Niña. This result is consistent with findings from previous studies and highlights the stress that the CalCS ecosystem could periodically undergo in addition to impacts due to climate change.

NBS measurement system for natural argon-37

International Nuclear Information System (INIS)

Currie, L.A.; Lindstrom, R.M.

1973-01-01

A project to determine the cosmic-ray production rate and the natural levels of 35-day half-life 37 Ar in the atmosphere has been underway at the National Bureau of Standards for about the past year. The prime objective of this project is to determine the spatial dependence of 37 Ar production in the atmosphere, and the spatial distribution of the naturally-produced 37 Ar (observed concentrations). The results of this study are to be used, in cooperation with L. Machta (National Oceanographic and Atmospheric Administration), to derive information about atmospheric mixing. The purpose of this communication, however, is to present a general description of the various components of the measurement system. As the lowest concentrations of interest are but approximately equal to 10 -3 dpm ( 37 Ar)/l-Ar, very high sensitivity measurement techniques are required. Among the techniques which we have adopted are: quantitative separation of the noble gases from about 1 m 3 of air, using a CaC 2 reactor; gas chromatographic separation of the argon fraction; isotopic enrichment (by a factor of approximately equal to 100) of purified argon; use of specially selected low-level gas proportional counters together with massive shielding and anticoincidence meson cancellation; and the application of pulse discrimination based upon both amplitude (energy) and pulse shape. Finally, on-line computer techniques are being applied for data acquisition and system control

Understanding oceanic migrations with intrinsic biogeochemical markers.

Directory of Open Access Journals (Sweden)

Raül Ramos

2009-07-01

Full Text Available Migratory marine vertebrates move annually across remote oceanic water masses crossing international borders. Many anthropogenic threats such as overfishing, bycatch, pollution or global warming put millions of marine migrants at risk especially during their long-distance movements. Therefore, precise knowledge about these migratory movements to understand where and when these animals are more exposed to human impacts is vital for addressing marine conservation issues. Because electronic tracking devices suffer from several constraints, mainly logistical and financial, there is emerging interest in finding appropriate intrinsic markers, such as the chemical composition of inert tissues, to study long-distance migrations and identify wintering sites. Here, using tracked pelagic seabirds and some of their own feathers which were known to be grown at different places and times within the annual cycle, we proved the value of biogeochemical analyses of inert tissue as tracers of marine movements and habitat use. Analyses of feathers grown in summer showed that both stable isotope signatures and element concentrations can signal the origin of breeding birds feeding in distinct water masses. However, only stable isotopes signalled water masses used during winter because elements mainly accumulated during the long breeding period are incorporated into feathers grown in both summer and winter. Our findings shed new light on the simple and effective assignment of marine organisms to distinct oceanic areas, providing new opportunities to study unknown migration patterns of secretive species, including in relation to human-induced mortality on specific populations in the marine environment.

Development and validation of natural circulation based systems for new WWER designs

International Nuclear Information System (INIS)

Kurakov, Y.A.; Dragunov, Y.G.; Podshibiakin, A.K.; Fil, N.S.; Logvinov, S.A.; Sitnik, Y.K.; Berkovich, V.M.; Taranov, G.S.

2002-01-01

Elaboration and introduction of NPP designs with improved technical and economic parameters are defined as an important element of the National Program of nuclear power development approved by the Russian Federation Government in 1998. This Program considers the designs of WWER-1000/V-392 and WWER-640/ V-407 power units as the priority projects of the new generation NPPs with increased safety. A number of passive systems based on natural circulation phenomena are used in V-392 and V-407 designs to prevent or mitigate severe accidents. Design basis, configuration and effect of some naturally driven systems of V-392 design sited at Novovoronezh are mainly reflected in the present paper. One of the most important mean for severe accident prevention in V-392 design is so called SPOT - passive heat removal system designed to remove core decay heat in case of station blackout (including failure of all diesel generators). This system extracts the steam from the steam generator, condenses it and returns water to steam generator by natural circulation. The SPOT heat exchangers are cooled by atmospheric air coming by natural circulation through a special direct action control gates which operate passively as well. Extensive experimental investigation of the different aspects of this system operation has been carried out to validate its functioning under real plant conditions. In particular, full-scale section of air heat exchanger-condenser has been tested with natural circulation steam, condensate and air paths modeled. The environment air temperature and steam pressure condensing were varied in the wide range, and the relevant experimental results are being discussed in this paper. The effect of wind velocity and direction to the containment is also checked by the experiments. (author)

The role of industrial nitrogen in the global nitrogen biogeochemical cycle

Science.gov (United States)

Gu, Baojing; Chang, Jie; Min, Yong; Ge, Ying; Zhu, Qiuan; Galloway, James N.; Peng, Changhui

2013-01-01

Haber-Bosch nitrogen (N) has been increasingly used in industrial products, e.g., nylon, besides fertilizer. Massive numbers of species of industrial reactive N (Nr) have emerged and produced definite consequences but receive little notice. Based on a comprehensive inventory, we show that (1) the industrial N flux has increased globally from 2.5 to 25.4 Tg N yr−1 from 1960 through 2008, comparable to the NOx emissions from fossil fuel combustion; (2) more than 25% of industrial products (primarily structural forms, e.g., nylon) tend to accumulate in human settlements due to their long service lives; (3) emerging Nr species define new N-assimilation and decomposition pathways and change the way that Nr is released to the environment; and (4) the loss of these Nr species to the environment has significant negative human and ecosystem impacts. Incorporating industrial Nr into urban environmental and biogeochemical models could help to advance urban ecology and environmental sciences. PMID:23999540

In vitro growth and leaf anatomy of Cattleya walkeriana (Gardner, 1839 grown in natural ventilation system

Directory of Open Access Journals (Sweden)

Adriano Bortolotti da Silva

2014-12-01

Full Text Available Natural ventilation system facilitates gaseous exchanges in in vitro plants promoting changes in the leaf tissue, which can be evaluated through the leaf anatomy, and it allows a cultivation closer to the photoautrophic micropropagation. The objective of this work was to evaluate the effects on in vitro growth and on the leaf anatomy of Cattleya walkeriana grown in natural and conventional ventilation system with different concentrations of sucrose (0; 15; 30 and 45 L-1 combined with different cultivation systems (conventional micropropagation and natural ventilation system. The culture medium was composed of MS salts, solidified with 7 g L-1 of agar and pH adjusted to 5.8. Forty milliliters of culture medium were distributed in 250 mL flasks, autoclaved at 120 ºC for 20 minutes. The greater plant growth, as well as the greater thickness of the mesophyll was observed with the use of 20 g L-1 sucrose in natural ventilation system. Plants grown in natural ventilation system showed a thicker leaf mesophyll, which is directly related to photoautotrophic crops. The natural ventilation system induced more elliptical stomata and probably more functional formats.

High spatial variability in biogeochemical rates and microbial communities across Louisiana salt marsh landscapes

Science.gov (United States)

Roberts, B. J.; Chelsky, A.; Bernhard, A. E.; Giblin, A. E.

2017-12-01

Salt marshes are important sites for retention and transformation of carbon and nutrients. Much of our current marsh biogeochemistry knowledge is based on sampling at times and in locations that are convenient, most often vegetated marsh platforms during low tide. Wetland loss rates are high in many coastal regions including Louisiana which has the highest loss rates in the US. This loss not only reduces total marsh area but also changes the relative allocation of subhabitats in the remaining marsh. Climate and other anthropogenic changes lead to further changes including inundation patterns, redox conditions, salinity regimes, and shifts in vegetation patterns across marsh landscapes. We present results from a series of studies examining biogeochemical rates, microbial communities, and soil properties along multiple edge to interior transects within Spartina alterniflora across the Louisiana coast; between expanding patches of Avicennia germinans and adjacent S. alterniflora marshes; in soils associated with the four most common Louisiana salt marsh plants species; and across six different marsh subhabitats. Spartina alterniflora marsh biogeochemistry and microbial populations display high spatial variability related to variability in soil properties which appear to be, at least in part, regulated by differences in elevation, hydrology, and redox conditions. Differences in rates between soils associated with different vegetation types were also related to soil properties with S. alterniflora soils often yielding the lowest rates. Biogeochemical process rates vary significantly across marsh subhabitats with individual process rates differing in their hotspot habitat(s) across the marsh. Distinct spatial patterns may influence the roles that marshes play in retaining and transforming nutrients in coastal regions and highlight the importance of incorporating spatial sampling when scaling up plot level measurements to landscape or regional scales.

Natural gas transmission and distribution model of the National Energy Modeling System

International Nuclear Information System (INIS)

1997-02-01

The Natural Gas Transmission and Distribution Model (NGTDM) is the component of the National Energy Modeling System (NEMS) that is used to represent the domestic natural gas transmission and distribution system. NEMS was developed in the Office of Integrated Analysis and Forecasting of the Energy Information Administration (EIA). NEMS is the third in a series of computer-based, midterm energy modeling systems used since 1974 by the EIA and its predecessor, the Federal Energy Administration, to analyze domestic energy-economy markets and develop projections. From 1982 through 1993, the Intermediate Future Forecasting System (IFFS) was used by the EIA for its analyses, and the Gas Analysis Modeling System (GAMS) was used within IFFS to represent natural gas markets. Prior to 1982, the Midterm Energy Forecasting System (MEFS), also referred to as the Project Independence Evaluation System (PIES), was employed. NEMS was developed to enhance and update EIA's modeling capability by internally incorporating models of energy markets that had previously been analyzed off-line. In addition, greater structural detail in NEMS permits the analysis of a broader range of energy issues. The time horizon of NEMS is the midterm period (i.e., through 2015). In order to represent the regional differences in energy markets, the component models of NEMS function at regional levels appropriate for the markets represented, with subsequent aggregation/disaggregation to the Census Division level for reporting purposes

Natural gas transmission and distribution model of the National Energy Modeling System

Energy Technology Data Exchange (ETDEWEB)

NONE

1997-02-01

The Natural Gas Transmission and Distribution Model (NGTDM) is the component of the National Energy Modeling System (NEMS) that is used to represent the domestic natural gas transmission and distribution system. NEMS was developed in the Office of Integrated Analysis and Forecasting of the Energy Information Administration (EIA). NEMS is the third in a series of computer-based, midterm energy modeling systems used since 1974 by the EIA and its predecessor, the Federal Energy Administration, to analyze domestic energy-economy markets and develop projections. From 1982 through 1993, the Intermediate Future Forecasting System (IFFS) was used by the EIA for its analyses, and the Gas Analysis Modeling System (GAMS) was used within IFFS to represent natural gas markets. Prior to 1982, the Midterm Energy Forecasting System (MEFS), also referred to as the Project Independence Evaluation System (PIES), was employed. NEMS was developed to enhance and update EIA`s modeling capability by internally incorporating models of energy markets that had previously been analyzed off-line. In addition, greater structural detail in NEMS permits the analysis of a broader range of energy issues. The time horizon of NEMS is the midterm period (i.e., through 2015). In order to represent the regional differences in energy markets, the component models of NEMS function at regional levels appropriate for the markets represented, with subsequent aggregation/disaggregation to the Census Division level for reporting purposes.

Abiotic and biotic controls over biogeochemical cycles in drylands: Insights from climate change and nitrogen deposition experiments on the Colorado Plateau

Science.gov (United States)

Reed, S.; Ferrenberg, S.; Tucker, C.; Rutherford, W. A.; Wertin, T. M.; McHugh, T. A.; Morrissey, E.; Kuske, C.; Mueller, R.; Belnap, J.

2016-12-01

As for all ecosystems, biogeochemical cycling in drylands represents numerous intricate connections between biotic and abiotic controls. However, patterns of many fundamental ecosystem processes that generally hold across global gradients fall apart at the arid and semiarid end of the spectrum, and data point to an exceptionally strong role for abiotic controls in explaining these patterns. Further, there are multiple dryland characteristics - such as extreme aridity and high UV radiation, as well as specialized biological communities - which can point to a conclusion that "drylands are different". Indeed, drylands are often characterized by their harsh environment, by the diverse classes of biota representing a range of traits aimed at surviving such harsh conditions, and, more recently, by the suggestion of dramatic biotic responses to seemingly subtle changes in abiotic factors. In this talk, we will explore a range of biotic and abiotic controls over fundamental biogeochemical cycling in drylands using data from a suite of manipulation experiments on the Colorado Plateau, USA. We will present results from field treatments that speak to the effects of increasing temperature, altered precipitation regimes, increased nitrogen availability via deposition, and the effects of altered litterfall inputs. Biogeochemical processes we explore will include plant photosynthesis, soil photosynthesis and respiration (with a focus on biological soil crusts), litter decomposition, and nutrient cycling. In addition, we will assess how treatments alter dryland community composition, as well as the resultant feedbacks of community shifts to environmental change. Taken together we will use these diverse datasets to ask questions about what makes drylands different or, instead, if a holistic joining of biotic and abiotic perspectives suggests they are not so different after all. These data will not only lend insight into the partitioning of and balance between biotic and abiotic

Global Analysis, Interpretation and Modelling: An Earth Systems Modelling Program

Science.gov (United States)

Moore, Berrien, III; Sahagian, Dork

1997-01-01

The Goal of the GAIM is: To advance the study of the coupled dynamics of the Earth system using as tools both data and models; to develop a strategy for the rapid development, evaluation, and application of comprehensive prognostic models of the Global Biogeochemical Subsystem which could eventually be linked with models of the Physical-Climate Subsystem; to propose, promote, and facilitate experiments with existing models or by linking subcomponent models, especially those associated with IGBP Core Projects and with WCRP efforts. Such experiments would be focused upon resolving interface issues and questions associated with developing an understanding of the prognostic behavior of key processes; to clarify key scientific issues facing the development of Global Biogeochemical Models and the coupling of these models to General Circulation Models; to assist the Intergovernmental Panel on Climate Change (IPCC) process by conducting timely studies that focus upon elucidating important unresolved scientific issues associated with the changing biogeochemical cycles of the planet and upon the role of the biosphere in the physical-climate subsystem, particularly its role in the global hydrological cycle; and to advise the SC-IGBP on progress in developing comprehensive Global Biogeochemical Models and to maintain scientific liaison with the WCRP Steering Group on Global Climate Modelling.

Towards a community Earth System Model

Science.gov (United States)

Blackmon, M.

2003-04-01

The Community Climate System Model, version 2 (CCSM2), was released in June 2002. CCSM2 has several new components and features, which I will discuss briefly. I will also show a few results from a multi-century equilibrium run with this model, emphasizing the improvements over the earlier simulation using the original CSM. A few flaws and inadequacies in CCSM2 have been identified. I will also discuss briefly work underway to improve the model and present results, if available. CCSM2, with improvements, will be the basis for the development of a Community Earth System Model (CESM). The highest priority for expansion of the model involves incorporation of biogeosciences into the coupled model system, with emphasis given to the carbon, nitrogen and iron cycles. The overall goal of the biogeosciences project within CESM is to understand the regulation of planetary energetics, planetary ecology, and planetary metabolism through exchanges of energy, momentum, and materials among atmosphere, land, and ocean, and the response of the climate system through these processes to changes in land cover and land use. In particular, this research addresses how biogeochemical coupling of carbon, nitrogen, and iron cycles affects climate and how human perturbations of these cycles alter climate. To accomplish these goals, the Community Land Model, the land component of CCSM2, is being developed to include river routing, carbon and nitrogen cycles, emissions of mineral aerosols and biogenic volatile organic compounds, dry deposition of various gases, and vegetation dynamics. The carbon and nitrogen cycles are being implemented using parameterizations developed as part of a state-of-the-art ecosystem biogeochemistry model. The primary goal of this research is to provide an accurate net flux of CO2 between the land and the atmosphere so that CESM can be used to study the dynamics of the coupled climate-carbon system. Emissions of biogenic volatile organic compounds are also based on a

Managing Watersheds as Couple Human-Natural Systems: A Review of Research Opportunities

Science.gov (United States)

Cai, X.

2011-12-01

Many watersheds around the world are impaired with severe social and environmental problems due to heavy anthropogenic stresses. Humans have transformed hydrological and biochemical processes in watersheds from a stationary to non-stationary status through direct (e.g., water withdrawals) and indirect (e.g., altering vegetation and land cover) interferences. It has been found that in many watersheds that socio-economic drivers, which have caused increasingly intensive alteration of natural processes, have even overcome natural variability to become the dominant factor affecting the behavior of watershed systems. Reversing this trend requires an understanding of the drivers of this intensification trajectory, and needs tremendous policy reform and investment. As stressed by several recent National Research Council (NRC) reports, watershed management will pose an enormous challenge in the coming decades. Correspondingly, the focus of research has started an evolution from the management of reservoir, stormwater and aquifer systems to the management of integrated watershed systems, to which policy instruments designed to make more rational economic use of water resources are likely to be applied. To provide a few examples: reservoir operation studies have moved from a local to a watershed scale in order to consider upstream best management practices in soil conservation and erosion control and downstream ecological flow requirements and water rights; watersheds have been modeled as integrated hydrologic-economic systems with multidisciplinary modeling efforts, instead of traditional isolated physical systems. Today's watershed management calls for a re-definition of watersheds from isolated natural systems to coupled human-natural systems (CHNS), which are characterized by the interactions between human activities and natural processes, crossing various spatial and temporal scales within the context of a watershed. The importance of the conceptual innovation has been

Advanced and natural interaction system for motion-impaired users

OpenAIRE

Manresa Yee, Cristina Suemay

2009-01-01

Human-computer interaction is an important area that searches for better and more comfortable systems to promote communication between humans and machines. Vision-based interfaces can offer a more natural and appealing way of communication. Moreover, it can help in the e-accessibility component of the e-inclusion. The aim is to develop a usable system, that is, the end-user must consider the use of this device effective, efficient and satisfactory. The research's main contribution is SINA, a ...

Soil temperature variability in complex terrain measured using fiber-optic distributed temperature sensing

Science.gov (United States)

Soil temperature (Ts) exerts critical controls on hydrologic and biogeochemical processes but magnitude and nature of Ts variability in a landscape setting are rarely documented. Fiber optic distributed temperature sensing systems (FO-DTS) potentially measure Ts at high density over a large extent. ...

A carborne gamma-ray spectrometer system for natural radioactivity mapping and environmental monitoring

International Nuclear Information System (INIS)

Grasty, R.L.; Cox, J.R.

1997-01-01

This paper summarizes the experience gained in the use of a carborne gamma-ray spectrometer system for mapping both natural and man-made radiation. Particular emphasis is placed on the calibration of the system for converting the gamma-ray measurements to ground concentrations of potassium, uranium and thorium and the activity of 137 Cs. During the Finnish Emergency Response Exercise (Resume95), the carborne system was shown to be effective in mapping both natural and man-made radiation from 137 Cs fallout and in locating radioactive sources. The application of the carborne system for mineral exploration is also demonstrated. (au)

Atomic switch networks-nanoarchitectonic design of a complex system for natural computing.

Science.gov (United States)

Demis, E C; Aguilera, R; Sillin, H O; Scharnhorst, K; Sandouk, E J; Aono, M; Stieg, A Z; Gimzewski, J K

2015-05-22

Self-organized complex systems are ubiquitous in nature, and the structural complexity of these natural systems can be used as a model to design new classes of functional nanotechnology based on highly interconnected networks of interacting units. Conventional fabrication methods for electronic computing devices are subject to known scaling limits, confining the diversity of possible architectures. This work explores methods of fabricating a self-organized complex device known as an atomic switch network and discusses its potential utility in computing. Through a merger of top-down and bottom-up techniques guided by mathematical and nanoarchitectonic design principles, we have produced functional devices comprising nanoscale elements whose intrinsic nonlinear dynamics and memorization capabilities produce robust patterns of distributed activity and a capacity for nonlinear transformation of input signals when configured in the appropriate network architecture. Their operational characteristics represent a unique potential for hardware implementation of natural computation, specifically in the area of reservoir computing-a burgeoning field that investigates the computational aptitude of complex biologically inspired systems.

Exploring the Influence of Topography on Belowground C Processes Using a Coupled Hydrologic-Biogeochemical Model

Science.gov (United States)

Shi, Y.; Davis, K. J.; Eissenstat, D. M.; Kaye, J. P.; Duffy, C.; Yu, X.; He, Y.

2014-12-01

Belowground carbon processes are affected by soil moisture and soil temperature, but current biogeochemical models are 1-D and cannot resolve topographically driven hill-slope soil moisture patterns, and cannot simulate the nonlinear effects of soil moisture on carbon processes. Coupling spatially-distributed physically-based hydrologic models with biogeochemical models may yield significant improvements in the representation of topographic influence on belowground C processes. We will couple the Flux-PIHM model to the Biome-BGC (BBGC) model. Flux-PIHM is a coupled physically-based land surface hydrologic model, which incorporates a land-surface scheme into the Penn State Integrated Hydrologic Model (PIHM). The land surface scheme is adapted from the Noah land surface model. Because PIHM is capable of simulating lateral water flow and deep groundwater, Flux-PIHM is able to represent the link between groundwater and the surface energy balance, as well as the land surface heterogeneities caused by topography. The coupled Flux-PIHM-BBGC model will be tested at the Susquehanna/Shale Hills critical zone observatory (SSHCZO). The abundant observations, including eddy covariance fluxes, soil moisture, groundwater level, sap flux, stream discharge, litterfall, leaf area index, above ground carbon stock, and soil carbon efflux, make SSHCZO an ideal test bed for the coupled model. In the coupled model, each Flux-PIHM model grid will couple a BBGC cell. Flux-PIHM will provide BBGC with soil moisture and soil temperature information, while BBGC provides Flux-PIHM with leaf area index. Preliminary results show that when Biome- BGC is driven by PIHM simulated soil moisture pattern, the simulated soil carbon is clearly impacted by topography.

A data management system to enable urgent natural disaster computing

Science.gov (United States)

Leong, Siew Hoon; Kranzlmüller, Dieter; Frank, Anton

2014-05-01

Civil protection, in particular natural disaster management, is very important to most nations and civilians in the world. When disasters like flash floods, earthquakes and tsunamis are expected or have taken place, it is of utmost importance to make timely decisions for managing the affected areas and reduce casualties. Computer simulations can generate information and provide predictions to facilitate this decision making process. Getting the data to the required resources is a critical requirement to enable the timely computation of the predictions. An urgent data management system to support natural disaster computing is thus necessary to effectively carry out data activities within a stipulated deadline. Since the trigger of a natural disaster is usually unpredictable, it is not always possible to prepare required resources well in advance. As such, an urgent data management system for natural disaster computing has to be able to work with any type of resources. Additional requirements include the need to manage deadlines and huge volume of data, fault tolerance, reliable, flexibility to changes, ease of usage, etc. The proposed data management platform includes a service manager to provide a uniform and extensible interface for the supported data protocols, a configuration manager to check and retrieve configurations of available resources, a scheduler manager to ensure that the deadlines can be met, a fault tolerance manager to increase the reliability of the platform and a data manager to initiate and perform the data activities. These managers will enable the selection of the most appropriate resource, transfer protocol, etc. such that the hard deadline of an urgent computation can be met for a particular urgent activity, e.g. data staging or computation. We associated 2 types of deadlines [2] with an urgent computing system. Soft-hard deadline: Missing a soft-firm deadline will render the computation less useful resulting in a cost that can have severe

Delineating the relationship between chromophoric dissolved organic matter (CDOM) variability and biogeochemical parameters in a shallow continental shelf

OpenAIRE

Sourav Das; Sugata Hazra; Aneesh A. Lotlikar; Isha Das; Sandip Giri; Abhra Chanda; Anirban Akhand; Sourav Maity; T. Srinivasa Kumar

2016-01-01

Absorption coefficient of chromophoric dissolved organic matter (CDOM) at 440 nm [aCDOM (440)], sea surface salinity (SSS), total suspended matter (TSM) and chlorophyll-a (chl-a) were measured during October, 2014 to March, 2015 in the shallow continental shelf waters of the Hugli Estuary, adjacent to West Bengal coast, India. The primary objective of the study was to characterize the relationship between aCDOM (440) and the above mentioned biogeochemical parameters. Upon analyzing the result...

Natural circulation in water cooled nuclear power plants: Phenomena, models, and methodology for system reliability assessments

International Nuclear Information System (INIS)

2005-11-01

In recent years it has been recognized that the application of passive safety systems (i.e. those whose operation takes advantage of natural forces such as convection and gravity), can contribute to simplification and potentially to improved economics of new nuclear power plant designs. Further, the IAEA Conference on The Safety of Nuclear Power: Strategy for the Future which was convened in 1991 noted that for new plants 'the use of passive safety features is a desirable method of achieving simplification and increasing the reliability of the performance of essential safety functions, and should be used wherever appropriate'. Considering the weak driving forces of passive systems based on natural circulation, careful design and analysis methods must be employed to assure that the systems perform their intended functions. To support the development of advanced water cooled reactor designs with passive systems, investigations of natural circulation are an ongoing activity in several IAEA Member States. Some new designs also utilize natural circulation as a means to remove core power during normal operation. In response to the motivating factors discussed above, and to foster international collaboration on the enabling technology of passive systems that utilize natural circulation, an IAEA Coordinated Research Project (CRP) on Natural Circulation Phenomena, Modelling and Reliability of Passive Systems that Utilize Natural Circulation was started in early 2004. Building on the shared expertise within the CRP, this publication presents extensive information on natural circulation phenomena, models, predictive tools and experiments that currently support design and analyses of natural circulation systems and highlights areas where additional research is needed. Therefore, this publication serves both to provide a description of the present state of knowledge on natural circulation in water cooled nuclear power plants and to guide the planning and conduct of the CRP in

Biogeochemical Impact of Long-Range Transported Dust over Northern South China Sea

Science.gov (United States)

Tsay, Si-Chee; Wang, S. H.; Hsu, N. C.

2011-01-01

Transpacific transport and impact of Asian dust aerosols have been well documented (e.g., results from ACE-Asia and regional follow-on campaigns), but little is known about dust invasion to the South China Sea (SCS). On 19-21 March 2010, a fierce Asian dust storm affected large areas from the Gobi deserts to the West Pacific, including Taiwan and Hong Kong. As a pilot study of the 7-SEAS (Seven South East Asian Studies) in the northern SCS, detailed characteristics of long-range transported dust aerosols were first observed by a comprehensive set of ground-based instruments deployed at the Dongsha islands (20deg42'52" N, 116deg43'51" E). Aerosol measurements such as particle mass concentrations, size distribution, optical properties, hygroscopicity, and vertical profiles help illustrate the evolution of this dust outbreak. Our results indicate that these dust particles were mixed with anthropogenic and marine aerosols, and transported near the surface. Satellite assessment of biogeochemical impact of dust deposition into open oceans is hindered by our current inability in retrieving areal dust properties and ocean colors over an extensive period of time, particularly under the influence of cloudy conditions. In this paper, we analyze the changes of retrieved Chlorophyll-a (Chl-a) concentration over the northern SCS, considered as oligotophic waters in the spring, from long-term SeaWiFS measurements since 1997. Over the past decade, six long-range transported dust events are identified based on spatiotemporal evolutions of PM10 measurements from regional monitoring stations, with the aid of trajectory analysis. Multi-year composites of Chl-a imagery for dust event and non-dust background during March-April are applied to overcome insufficient retrievals of Chl-a due to cloudy environment. Due to anthropogenic modification within a shallow boundary layer off the densely populated and industrial southeast coast of China, the iron ion activation of deliquescent dust

Biogeochemical study of termite mounds: a case study from Tummalapalle area of Andhra Pradesh, India.

Science.gov (United States)

Arveti, Nagaraju; Reginald, S; Kumar, K Sunil; Harinath, V; Sreedhar, Y

2012-04-01

Termite mounds are abundant components of Tummalapalle area of uranium mineralization of Cuddapah District of Andhra Pradesh, India. The systematic research has been carried out on the application of termite mound sampling to mineral exploration in this region. The distribution of chemical elements Cu, Pb, Zn, Ni, Co, Cr, Li, Rb, Sr, Ba, and U were studied both in termite soils and adjacent surface soils. Uranium accumulations were noticed in seven termite mounds ranging from 10 to 36 ppm. A biogeochemical parameter called "Biological Absorption Coefficient" of the termite mounds indicated the termite affected soils contained huge amounts of chemical elements than the adjacent soils.

Tracing global biogeochemical cycles and meridional overturning circulation using chromophoric dissolved organic matter

Science.gov (United States)

Nelson, Norman B.; Siegel, David A.; Carlson, Craig A.; Swan, Chantal M.

2010-02-01

Basin-scale distributions of light absorption by chromophoric dissolved organic matter (CDOM) are positively correlated (R2 > 0.8) with apparent oxygen utilization (AOU) within the top kilometer of the Pacific and Indian Oceans. However, a much weaker correspondence is found for the Atlantic (R2 organic matter from sinking particles. The observed meridional-depth sections of CDOM result from a balance between biogeochemical processes (autochthonous production and solar bleaching) and the meridional overturning circulation. Rapid mixing in the Atlantic dilutes CDOM in the interior and implies that the time scale for CDOM accumulation is greater than ˜50 years. CDOM emerges as a unique tracer for diagnosing changes in biogeochemistry and the overturning circulation, similar to dissolved oxygen, with the additional feature that it can be quantified from satellite observation.

[New polymer-drug systems based on natural and synthetic polymers].

Science.gov (United States)

Racoviţă, Stefania; Vasiliu, Silvia; Foia, Liliana

2010-01-01

The great versatility of polymers makes them very useful in the biomedical and pharmaceutical fields. The combination of natural and synthetic polymers leads to new materials with tailored functional properties. The aim of this work consists in the preparation of new drug delivery system based on chitosan (natural polymer) and polybetaines (synthetic polymers), by a simple process, well known in the literature as complex coacervation methods. Also, the adsorption and release studies of two antibiotics as well as the preservation of their bactericidal capacities were performed.

Physical and biogeochemical controls on light attenuation in a eutrophic, back-barrier estuary

Science.gov (United States)

Ganju, Neil K.; Miselis, Jennifer L.; Aretxabaleta, Alfredo L.

2014-01-01

Light attenuation is a critical parameter governing the ecological function of shallow estuaries. In these systems primary production is often dominated by benthic macroalgae and seagrass; thus light penetration to the bed is of primary importance. We quantified light attenuation in three seagrass meadows in Barnegat Bay, New Jersey, a shallow eutrophic back-barrier estuary; two of the sites were located within designated Ecologically Sensitive Areas (ESAs). We sequentially deployed instrumentation measuring photosynthetically active radiation, chlorophyll-a (chl-a) fluorescence, dissolved organic matter fluorescence (fDOM; a proxy for colored DOM absorbance), turbidity, pressure, and water velocity at 10 min intervals over three week periods at each site. At the southernmost site, where sediment availability was highest, light attenuation was highest and dominated by turbidity and to a lesser extent chl-a and CDOM. At the central site, chl-a dominated followed by turbidity and CDOM, and at the northernmost site turbidity and CDOM contributed equally to light attenuation. At a given site, the temporal variability of light attenuation exceeded the difference in median light attenuation at the three sites, indicating the need for continuous high-temporal resolution measurements. Vessel wakes, anecdotally implicated in increasing sediment resuspension, did not contribute to local resuspension within the seagrass beds, though frequent vessel wakes were observed in the channels. With regards to light attenuation and water clarity, physical and biogeochemical variables appear to outweigh any regulation of boat traffic within the ESAs.

Biogeochemical Hotspots: Small Geographically Isolated Wetlands and their Impacts at the Landscape Scale

Science.gov (United States)

Basu, N. B.

2017-12-01

Wetlands provide a wide variety of ecosystem services, including retention of sediment and nutrients, and subsequent improvements in downstream water quality. In fact, a recent review suggests that 64% of reactive nitrogen (N) retention in US freshwater systems occurs in wetlands, while 28% occurs in lakes and reservoirs, and only 8% occurs in streams and rivers. Although the processes controlling nutrient retention in wetlands are well known, there is a lack of quantitative understanding of the relative nutrient filtering abilities of wetlands of various sizes, and in various landscape positions. Our inability to recognize the value of wetlands has led to their dramatic loss in the last few decades. Specifically, there has been an increased loss of geographically isolated wetlands, small upland wetlands that receive fewer legal protections due to their apparent isolation from jurisdictional waters. In this study, we use a meta-analyses approach to quantify the role of small wetlands in landscape scale nutrient processing. We synthesized data from 600 lentic systems around the world to gain insight into the relationship between hydrologic and biogeochemical controls on nutrient retention. Our results indicate that the first-order reaction rate constant k(T-1), is inversely proportional to the residence time, across 6 orders of magnitude in residence time for total N, total P, nitrate, and phosphate. We used a sediment-water model to show how nutrient removal processes are impacted by system size. Finally, the k-residence time relationships were upscaled to the landscape scale using a wetland size-frequency distribution. Results suggest that small wetlands play a disproportionately large role in landscape-scale nutrient processing—50% of nitrogen removal occurs in wetlands smaller than 10^2.5 m2 in our example. Thus, given the same loss in wetland area, the nutrient retention potential lost is greater when smaller wetlands are preferentially lost from the

Nouns referring to tools and natural objects differentially modulate the motor system.

Science.gov (United States)

Gough, Patricia M; Riggio, Lucia; Chersi, Fabian; Sato, Marc; Fogassi, Leonardo; Buccino, Giovanni

2012-01-01

While increasing evidence points to a critical role for the motor system in language processing, the focus of previous work has been on the linguistic category of verbs. Here we tested whether nouns are effective in modulating the motor system and further whether different kinds of nouns - those referring to artifacts or natural items, and items that are graspable or ungraspable - would differentially modulate the system. A Transcranial Magnetic Stimulation (TMS) study was carried out to compare modulation of the motor system when subjects read nouns referring to objects which are Artificial or Natural and which are Graspable or Ungraspable. TMS was applied to the primary motor cortex representation of the first dorsal interosseous (FDI) muscle of the right hand at 150 ms after noun presentation. Analyses of Motor Evoked Potentials (MEPs) revealed that across the duration of the task, nouns referring to graspable artifacts (tools) were associated with significantly greater MEP areas. Analyses of the initial presentation of items revealed a main effect of graspability. The findings are in line with an embodied view of nouns, with MEP measures modulated according to whether nouns referred to natural objects or artifacts (tools), confirming tools as a special class of items in motor terms. Additionally our data support a difference for graspable versus non graspable objects, an effect which for natural objects is restricted to initial presentation of items. Copyright © 2011 Elsevier Ltd. All rights reserved.

Improving the analysis of biogeochemical patterns associated with internal waves in the strait of Gibraltar using remote sensing images

Science.gov (United States)

Navarro, Gabriel; Vicent, Jorge; Caballero, Isabel; Gómez-Enri, Jesús; Morris, Edward P.; Sabater, Neus; Macías, Diego; Bolado-Penagos, Marina; Gomiz, Juan Jesús; Bruno, Miguel; Caldeira, Rui; Vázquez, Águeda

2018-05-01

High Amplitude Internal Waves (HAIWs) are physical processes observed in the Strait of Gibraltar (the narrow channel between the Atlantic Ocean and the Mediterranean Sea). These internal waves are generated over the Camarinal Sill (western side of the strait) during the tidal outflow (toward the Atlantic Ocean) when critical hydraulic conditions are established. HAIWs remain over the sill for up to 4 h until the outflow slackens, being then released (mostly) towards the Mediterranean Sea. These have been previously observed using Synthetic Aperture Radar (SAR), which captures variations in surface water roughness. However, in this work we use high resolution optical remote sensing, with the aim of examining the influence of HAIWs on biogeochemical processes. We used hyperspectral images from the Hyperspectral Imager for the Coastal Ocean (HICO) and high spatial resolution (10 m) images from the MultiSpectral Instrument (MSI) onboard the Sentinel-2A satellite. This work represents the first attempt to examine the relation between internal wave generation and the water constituents of the Camarinal Sill using hyperspectral and high spatial resolution remote sensing images. This enhanced spatial and spectral resolution revealed the detailed biogeochemical patterns associated with the internal waves and suggests local enhancements of productivity associated with internal waves trains.

A system-level modelling perspective of the KwaZulu-Natal Bight ...

African Journals Online (AJOL)

Requirements to take the hydrodynamic, biogeochemical and first ecosystem modelling efforts towards a meaningful predictive capability are discussed. The importance of adopting a system-level view of the bight and its connected systems for realistic exploration of global change scenarios is highlighted. Keywords: ...

The role of open ocean boundary forcing on seasonal to decadal-scale variability and long-term change of natural shelf hypoxia

International Nuclear Information System (INIS)

Monteiro, Pedro M S; Dewitte, Boris; Paulmier, Aurelien; Scranton, Mary I; Van der Plas, Anja K

2011-01-01

In this study we investigate the possible reasons for the widespread differences between the seasonal cycles of carbon production and export compared to those of hypoxia in eastern boundary upwelling systems. An idealized model is proposed that qualitatively characterizes the relative roles of physics and biogeochemical fluxes. The model is tested on three contrasting upwelling systems: the Benguela (from relatively aerated to interannual anoxic), the Humboldt (sub-oxic and interannually anoxic) and the Cariaco (permanently anoxic). Overall we propose that shelf hypoxia variability can be explained on the basis of the interaction between ventilation by ocean boundary forcing through ocean-shelf exchange and the role of shelf geometry in the retention of shelf-based particulate organic carbon (POC) fluxes. We aim to identify the hypoxia regimes associated with low ventilation-wide-shelf systems and high ventilation-narrow-shelf systems, considering them as extremes of conditions controlled by the two factors. We propose that this may help to explain differences in the seasonal cycles of the biogeochemical drivers and responses as well as difference between upwelling systems and within individual upwelling systems. It is suggested that when seasonal hypoxia emerges it does so preferentially at a wide-shelf part of a system.

Aquifer/aquitard interfaces: mixing zones that enhance biogeochemical reactions

Science.gov (United States)

McMahon, P. B.

2001-01-01

Several important biogeochemical reactions are known to occur near the interface between aquifer and aquitard sediments. These reactions include O2 reduction; denitrification; and Fe3+, SO42-, and CO2 (methanogenesis) reduction. In some settings, these reactions occur on the aquitard side of the interface as electron acceptors move from the aquifer into the electron-donor-enriched aquitard. In other settings, these reactions occur on the aquifer side of the interface as electron donors move from the aquitard into the electron-acceptor-enriched, or microorganism-enriched, aquifer. Thus, the aquifer/aquitard interface represents a mixing zone capable of supporting greater microbial activity than either hydrogeologic unit alone. The extent to which biogeochemical reactions proceed in the mixing zone and the width of the mixing zone depend on several factors, including the abundance and solubility of electron acceptors and donors on either side of the interface and the rate at which electron acceptors and donors react and move across the interface. Biogeochemical reactions near the aquifer/aquitard interface can have a substantial influence on the chemistry of water in aquifers and on the chemistry of sediments near the interface. Résumé. Il se produit au voisinage de l'interface entre les aquifères et les imperméables plusieurs réactions biogéochimiques importantes. Il s'agit des réactions de réduction de l'oxygène, de la dénitrification et de la réduction de Fe3+, SO42- et CO2 (méthanogenèse). Dans certaines situations, ces réactions se produisent du côté imperméable de l'interface, avec des accepteurs d'électrons qui vont de l'aquifère vers l'imperméable riche en donneurs d'électrons. Dans d'autres situations, ces réactions se produisent du côté aquifère de l'interface, avec des donneurs d'électrons qui se déplacent de l'imperméable vers l'aquifère riche en accepteurs d'électrons ou en microorganismes. Ainsi, l'interface aquif

Forms and subannual variability of nitrogen and phosphorus loading to global river networks over the 20th century

NARCIS (Netherlands)

Vilmin, Lauriane; Mogollón, José M.; Beusen, Arthur H.W.; Bouwman, Alexander F.

2018-01-01

Nitrogen (N) and phosphorus (P) play a major role in the biogeochemical functioning of aquatic systems. N and P transfer to surface freshwaters has amplified during the 20th century, which has led to widespread eutrophication problems. The contribution of different sources, natural and

A carborne gamma-ray spectrometer system for natural radioactivity mapping and environmental monitoring

Energy Technology Data Exchange (ETDEWEB)

Grasty, R.L.; Cox, J.R. [Exploranium Ltd., Mississauga, Ontario (Canada)

1997-12-31

This paper summarizes the experience gained in the use of a carborne gamma-ray spectrometer system for mapping both natural and man-made radiation. Particular emphasis is placed on the calibration of the system for converting the gamma-ray measurements to ground concentrations of potassium, uranium and thorium and the activity of {sup 137}Cs. During the Finnish Emergency Response Exercise (Resume95), the carborne system was shown to be effective in mapping both natural and man-made radiation from {sup 137}Cs fallout and in locating radioactive sources. The application of the carborne system for mineral exploration is also demonstrated. (au). 10 refs.

A carborne gamma-ray spectrometer system for natural radioactivity mapping and environmental monitoring

Energy Technology Data Exchange (ETDEWEB)

Grasty, R L; Cox, J R [Exploranium Ltd., Mississauga, Ontario (Canada)

1998-12-31

This paper summarizes the experience gained in the use of a carborne gamma-ray spectrometer system for mapping both natural and man-made radiation. Particular emphasis is placed on the calibration of the system for converting the gamma-ray measurements to ground concentrations of potassium, uranium and thorium and the activity of {sup 137}Cs. During the Finnish Emergency Response Exercise (Resume95), the carborne system was shown to be effective in mapping both natural and man-made radiation from {sup 137}Cs fallout and in locating radioactive sources. The application of the carborne system for mineral exploration is also demonstrated. (au). 10 refs.