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Sample records for organic matter diagenesis

  1. Roles of organic matter in sediment diagenesis

    SciTech Connect

    Gautier, D.L.

    1986-01-01

    This book is a collection of papers presented at a 1984 symposium of the Society of Economic Paleontologists and Mineralogists (SEPM). It purpose, in the words of its editor, is to bring to the attention of the sedimentological community the importance of interaction of organic compounds with the inorganic sedimentary system and the degree to which organic compounds drive diagenetic systems. Its 16 papers cover topics ranging from laboratory carbonate dissolution to hydrocarbon source-rock evaluation. It contains an excellent group of papers on the role of organic-inorganic interactions in porosity enhancement. An excellent contribution is the paper on organic and inorganic diagenesis in the Shinjo oil field of Japan. At the other end of the scale, however, are several theoretical papers that present greatly oversimplified and/or underedited thermodynamic and mass-transfer models. Nearly all of the papers contribute to the dialogue between organic and inorganic sedimentologists. Because much of this interchange has occurred in support of petroleum exploration, the dialogue has waxed and waned with the ups and downs of the oil market. However, hydrocarbon prospects do not necessarily present the best opportunities for unraveling the complex interrelations between organic and inorganic diagenesis. These interrelations are important in a wide range of diagenetic settings, including early diagenesis in low-organic sediments that have little or no hydrocarbon potential. It is hoped that this book will pave the way for expanded basic research in one of the most important aspects of sediment diagenesis.

  2. Maturation of organic matter during experimental simulation of carbonate diagenesis

    SciTech Connect

    Ferguson, J.; Bush, P.R.; Clarke, B.A. )

    1989-09-01

    An earlier investigation involving the simulation of the early stages of diagenesis of carbonate ooids has been extended to include skeletal carbonates and carbonate mud. The experiments, lasting up to 70 days at elevated hydrostatic pressure and temperatures of 180{degree}-210{degree}C, used natural sea water and recent calcitic and aragonitic carbonate materials collected from Florida Bay and the Bahamas. The results give insight into the processes of maturation and diagenesis of the organic and inorganic fractions. Analysis of the organic fraction, both before and after the experiments, gives indicates of possible pathways of maturation during early diagenesis. A small amount of data is also available on the fate of sugars and amino acids in the system. Overall, the experiments closely approximate the natural system. Reactions occurring in the inorganic components are closely allied to those in the organic fraction. Indeed, two of the critical factors in early carbonate diagenesis are the amount and quality of organic matter and the shape, size, and nature of the carbonate grains. Changes in the carbonate fraction taking place during and after the experiments have been deduced by monitoring the pore fluid chemistry and by analyzing the final solid product. These results are discussed briefly and related to changes in the organic phase.

  3. Carbon isotope fractionation of sapropelic organic matter during early diagenesis

    USGS Publications Warehouse

    Spiker, E. C.; Hatcher, P.G.

    1984-01-01

    Study of an algal, sapropelic sediment from Mangrove Lake, Bermuda shows that the mass balance of carbon and stable carbon isotopes in the major organic constituents is accounted for by a relatively straightforward model of selective preservation during diagenesis. The loss of 13C-enriched carbohydrates is the principal factor controlling the intermolecular mass balance of 13C in the sapropel. Results indicate that labile components are decomposed leaving as a residual concentrate in the sediment an insoluble humic substance that may be an original biochemical component of algae and associated bacteria. An overall decrease of up to about 4??? in the ?? 13C values of the organic matter is observed as a result of early diagenesis. ?? 1984.

  4. Organic matter diagenesis in shallow water carbonate sediments

    NASA Astrophysics Data System (ADS)

    Ingalls, Anitra E.; Aller, Robert C.; Lee, Cindy; Wakeham, Stuart G.

    2004-11-01

    Muddy carbonate deposits near the Dry Tortugas, Florida, are characterized by high organic carbon remineralization rates. However, approximately half of the total sedimentary organic matter potentially supporting remineralization is occluded in CaCO 3 minerals (intracrystalline). While a portion of nonintracrystalline organic matter appears to cycle rapidly, intracrystalline organic matter has an approximately constant concentration with depth, suggesting that as long as its protective mineral matrix is intact, it is not readily remineralized. Organic matter in excess of intracrystalline organic matter that is preserved may have a variety of mineral associations (e.g., intercrystalline, adsorbed or detrital). In surface sediment, aspartic acid contributed ˜22 mole % and ˜50 mole % to nonintracrystalline and intracrystalline pools, respectively. In deeper sediment (1.6-1.7m), the composition of hydrolyzable amino acids in both pools was similar (aspartic acid ˜40 mole %). Like amino acids, intracrystalline and nonintracrystalline fatty acids have different compositions in surface sediments, but are indistinguishable at depth. These data suggest that preserved organic matter in the nonintracrystalline pool is stabilized by its interactions with CaCO 3. Neutral lipids are present in very low abundances in the intracrystalline pool and are extensively degraded in both the intracrystalline and nonintracrystalline pools, suggesting that mineral interactions do not protect these compounds from degradation. The presence of chlorophyll- a, but absence of phytol, in the intracrystalline lipid pool demonstrates that chloropigments are present only in the nonintracrystalline pool. Sedimentary chloropigments decrease with depth at similar rates in Dry Tortugas sediments as found in alumino-silicate sediments from the Long Island Sound, suggesting that chloropigment degradation is largely unaffected by mineral interactions. Overall, however, inclusion and protection of

  5. Organic matter oxidation and aragonite diagenesis in a coral reef

    SciTech Connect

    Tribble, G.W. Univ. of Hawaii, Honolulu )

    1993-05-01

    A combination of field and theoretical work is used to study controls on the saturation state of aragonite inside a coral-reef framework. A closed-system ion-speciation model is used to evaluate the effect of organic-matter oxidation on the saturation state of aragonite. The aragonite saturation state initially drops below 1 but becomes oversaturated during sulfate reduction. The C:N ratio of the organic matter affects the degree of oversaturation with N-poor organic material resulting in a system more corrosive to aragonite. Precipitation of sulfide as FeS strongly affects the aragonite saturation state, and systems with much FeS formation will have a stronger tendency to become oversaturated with respect to aragonite. Both precipitation and dissolution of aragonite are predicted at different stages of the organic reaction pathway if the model system is maintained at aragonite saturation. Field data from a coral-reef framework indicate that the system maintains itself at aragonite saturation, and model-predicted changes in dissolved calcium follow those observed in the interstitial waters of the reef. Aragonite probably acts as a solid-phase buffer in regulating the pH of interstitial waters. Because interstitial water in the reef has a short residence time, the observed equilibration suggests rapid kinetics.

  6. Microbial Nitrogen Cycling Associated with the Early Diagenesis of Organic Matter in Subseafloor Sediments

    NASA Astrophysics Data System (ADS)

    Zhao, R.

    2015-12-01

    The early diagenesis of organic matter is the major energy source of marine sedimentary biosphere and thus controls its population size; however, the vertical distribution of any functional groups along with the diagenesis of organic matter is remained unclear, especially for those microbes involved in nitrogen transformation which serve as a major control on the nitrogen flux between reservoirs. Here we investigated the vertical distributions of various functional groups in five sediment cores retrieved from Arctic Mid-Ocean Ridge (AMOR), with emphasis on the nitrifiers, denitrifiers and anaerobic ammonium oxidizing bacteria (anammox). We observed the clear geochemical zonation associated with organic matter diagenesis in the sediments based on the pore water profiles of oxygen, nitrate, ammonium, manganese and sulfate, with distinct geochemical transition zones at the boundaries of geochemical zones, including oxic-anoxic transition zone (OATZ) and nitrate-manganese reduction zone (NMTZ). Nitrate was produced in surface oxygenated sediments and nitrate consumption mainly took place at the NMTZ, splitted between re-oxidation of ammonium and manganese (II). Abundances of ammonia oxidizers, nitrite oxidizers, and denitrifiers, estimated through quantitative PCR targeting their respective functional genes, generally decrease with depth, but constantly elevated around the OATZ, NMTZ, and manganese-reduction zone as well. Anammox bacteria were only detected around the NMTZ where both nitrate/nitrite and ammonium are available. These depth profiles of functional groups were also confirmed by the community structure profiling by prokaryotic 16S rRNA gene tag pyrosequencing. Cell-specific rates of nitrification and denitrification, calculated from the bulk net reaction rates divided by functional group abundances, were similar to those values from oligotrophic sediments like North Pond and thus suggested that nitrifiers and denitirifiers populations were in maintenance

  7. Early diagenesis of organic matter in a Sawgrass peat from the Everglades, Florida

    USGS Publications Warehouse

    Orem, W.H.; Hatcher, P.G.

    1987-01-01

    The transformation of plant biopolymers to humic substances in peats during early diagenesis is a critical but poorly understood step in the formation of coal. This paper presents results concerning the structural interrelationships among various fractions of the organic matter in peat and the dissolved organic matter in the pore water from a site in The Everglades, relying primarily on elemental analysis and 13C nuclear magnetic resonance for structural elucidation. Our goal was to obtaine some insight into the sequence of steps involved in the formation of humic substances. Results show that the major change occurring in the whole peat during diagenesis is loss of carbohydrates. The components of the peat which are more resistant to microbial degradation become concentrated in the humin fraction. This resistant fraction of the organic matter includes aliphatic and aromatic components. The aromatic components are thought to be derived from lignin while the aliphatic moieties may represent decomposed algal remains. The carbohydrates lost from the whole peat appear to be concentrated in the fulvic acids and the dissolved organic matter in the pore water. The humic acids consist predominantly of aromatic and aliphatic structures, and may represent partially degraded lignin-like structures and aliphatic compounds from algae. The data presented here suggest that humic and fulvic acids are the partially degraded fractions of the peat while the humin contains the resistant or preserved portion of the organic matter. The proposition that humic substances are formed by the condensation of amino acids and sugars is not supported by the results of this study. ?? 1987.

  8. Organic matter diagenesis and hydrocarbon generation on outer Continental Margin of northwestern Australia

    SciTech Connect

    Meyers, P.A.; Snowdon, L.R.; Heggie, D.; Bent, A.

    1989-03-01

    Organic geochemical analyses of sediments and rocks obtained from drill sites on the Exmouth and Wombat Plateaus and the Argo Abyssal Plain on the northwestern margin of Australia were done onboard the JOIDES Resolution during Ocean Drilling Program Legs 122 and 123. These analyses provide information about the sources of organic matter to these offshore locations from Triassic to Holocene times and also indicate the degree of postdepositional diagenesis and maturation the organic matter has experienced. Because this margin has interest to petroleum explorationists, these data have practical as well as fundamental significance. Triassic claystones (equivalent to the onshore Mungeroo Formation) from the Wombat Plateau contain up to several percent of land-derived organic carbon. Neocomian siltstones and claystones (equivalent to the Barrow Group and Muderong Shale) from the Exmouth Plateau hold similar organic matter but at lower concentrations. Younger sediments are generally very lean in organic matter. Gas chromatographic analysis of extractable hydrocarbons shows a large and often dominant contribution of continental components, notably n-alkanes with a strong odd/even ratio and tricyclic diterpanes. Both Rock-Eval and hydrocarbon results agree in indicating low to moderate levels of thermal maturity. Locations on the Exmouth Plateau typically contain large amounts of thermogenic gaseous hydrocarbons dominated by methane. Concentrations peak in Senonian chalk sequences. In Neocomian siltstones and claystones, methane-ethane ratios diminish as concentrations decrease. The source of these hydrocarbons is likely to be the Triassic coals and coaly material below the Dingo claystone, which was not drilled during these legs but has been characterized from industry wells on this passive margin.

  9. Comprehensive assessment of precursors, diagenesis, and reactivity to water treatment of dissolved and colloidal organic matter

    USGS Publications Warehouse

    Leenheer, J.A.

    2004-01-01

    A comprehensive isolation, fractionation, and characterization research approach was developed for dissolved and colloidal organic matter (DOM) in water, and it was applied to various surface- and groundwaters to assess DOM precursors, DOM diagenesis, and DOM reactivity to water treatment processes. Major precursors for natural DOM are amino sugars, condensed tannins, and terpenoids. Amino sugar colloids derived from bacterial cell walls are incompletely removed by drinking water treatment and foul reverse osmosis membranes, but are nearly quantitatively removed by soil/aquifer treatment. When chlorinated, amino sugars produce low yields of regulated disinfection by-products (DBFs) but they produce significant chlorine demand that is likely caused by chlorination of free amino groups. Condensed tannins are major precursors for "blackwater" DOM such as that found in the Suwannee River. This DOM produces high yields of DBPs upon chorination, and is efficiently removed by coagulation/flocculation treatment. Terpenoid-derived DOM appears to be biologically refractory, infiltrates readily into groundwater with little removal by soil/aquifer treatment, gives low DBF-yields upon chlorination and is poorly removed by coagulation/flocculation treatments. Peptides derived from proteins are major components of the base DOM fraction (10% or less of the mass of DOM), and this fraction produces large yields of haloacetonitriles upon chorination.

  10. Maturation of organic matter in Paleocene-Eocene Wilcox group south Texas: relationship to clay diagenesis and sandstone cementation

    SciTech Connect

    Jenden, P.D.; Kaplan, I.R.

    1984-04-01

    Thirty-three mudstone core and cuttings samples ranging in depth of 1.6-4.7 km (5200-15,400 ft) and in temperature from 80/sup 0/ to 210/sup 0/C (175-410/sup 0/F) were obtained from wells in south Texas. The results of closed-system pyrolyses and bitumen and kerogen analyses are related to available data on clay mineralogy and sandstone cement. This study examines the diagenesis of Wilcox organic matter, the migration of hydrocarbons, and the importance of organically derived CO/sub 2/ in sandstone cementation. The samples average 1% TOC, contain type 111 kerogen, and generally show bitumen contents less than or equal to about 150 mg/gC. Modeling indicates that primary migration of methane and light hydrocarbons in aqueous solution is capable of producing giant (greater than or equal to 1 tcf) gas and condensate fields. Because hydrocarbon generation does not occur until after the main stage of illitization, smectite accounts for less than 25% of the total water involved. Pyrolysis experiments indicate that as much as 150 mg/gC CO/sub 2/ may be liberated by Wilcox organic matter during diagenesis to present-day temperatures of 100/sup 0/C (212/sup 0/F). The main zone of oil generation occurs at subsurface temperatures of 95..pi..-125/sup 0/C (203/sup 0/-257/sup 0/F). The timing of these processes suggest that CO/sub 2/ could lay an important role in creating secondary sandstones porosity for hydrocarbon migration. The delta/sup 13/C values indicate that 25% of the carbonate cement present in Wilcox sandstones may originate from decomposition and diagenesis of organic matter.

  11. Diagenesis of amorphous organic matter as an essential aspect of genesis and alteration of tabular-type uranium-vanadium deposits, Colorado Plateau

    SciTech Connect

    Spirakis, C.S.; Hansley, P.L.

    1987-05-01

    Organic matter was the key to the initial concentration of uranium and vanadium (during the sulfate reduction stage of early diagenesis) in all sandstone-hosted, tabular deposits in the Morrison Formation, Colorado Plateau. In deposits rich in amorphous organic matter, as are many in the Grants uranium region (GUR), diagenesis did not proceed beyond sulfate reduction. In contrast, in organic-poor, chlorite deposits of the Henry Mountains district, /sup 13/C- and /sup 18/O-enriched dolomites preserve evidence of a subsequent methanogenic stage. In these and similar organic-poor deposits in the Slick Rock district and in parts of the GUR, aluminosilicate dissolution (including a distinctive, organic-acid-induced etching of garnets) and growth of coarse-grained coffinite, albite, ankerite, and chlorite suggest diagenesis reached the organic acid stage. Temperature and thermal maturation indicators (vitrinite reflectance, type IIb chlorite, ordered illite/smectite, and fluid inclusion data) are consistent with temperatures of organic-acid stage diagenesis (approx. 100/sup 0/C). The localization of these alterations in and around organic-poor, clay-rich ore; the similarities in type and sequence of these alterations to the normal alteration of organic-bearing sediments; the alteration of iron-titanium oxides (attributed to the action of soluble organic complexes) around both organic-rich and organic-poor deposits; and the gradation from organic-rich to organic-poor, chlorite-rich deposits (in GUR) suggest that (1) amorphous organic matter was involved in the genesis of all of these deposits and (2) differences among deposits may reflect varying degrees of diagenesis of the organic matter.

  12. Early diagenesis of recently deposited organic matter: A 9-yr time-series study of a flood deposit

    NASA Astrophysics Data System (ADS)

    Tesi, T.; Langone, L.; Goñi, M. A.; Wheatcroft, R. A.; Miserocchi, S.; Bertotti, L.

    2012-04-01

    In Fall 2000, the Po River (Italy) experienced a 100-yr return period flood that resulted in a 1-25 cm-thick deposit in the adjacent prodelta (10-25 m water depth). In the following years, numerous post-depositional perturbations occurred including bioturbation, reworking by waves with heights exceeding 5 m, as well as periods of extremely high and low sediment supply. Cores collected in the central prodelta after the Fall 2000 flood and over the following 9 yr, allowed characterization of the event-strata in their initial state and documentation of their subsequent evolution. Sedimentological characteristics were investigated using X-radiographs and sediment texture analyses, whereas the composition of sedimentary organic matter (OM) was studied via bulk and biomarker analyses, including organic carbon (OC), total nitrogen (TN), carbon stable isotope composition (δ13C), lignin phenols, cutin-products, p-hydroxy benzenes, benzoic acids, dicarboxylic acids, and fatty acids. The 9-yr time-series analysis indicated that roughly the lower half of the original event bed was preserved in the sediment record. Conversely, the upper half of the deposit experienced significant alterations including bioturbation, addition of new material, as well as coarsening. Comparison of the recently deposited material with 9-yr old preserved strata represented a unique natural laboratory to investigate the diagenesis of sedimentary OM in a non-steady system. Bulk data indicated that OC and TN were degraded at similar rates (loss ∼17%) whereas biomarkers exhibited a broad spectrum of reactivities (loss from ∼6% to ∼60%) indicating selective preservation during early diagenesis. Given the relevance of episodic sedimentation in several margins, this study has demonstrated the utility of event-response and time-series sampling of the seabed for understanding the early diagenesis in non-steady conditions.

  13. Impact of the simulated diagenesis on sorption of naphthalene and 1-naphthol by soil organic matter and its precursors.

    PubMed

    Guo, Xiaoying; Wang, Xilong; Zhou, Xinzhe; Ding, Xing; Fu, Bin; Tao, Shu; Xing, Baoshan

    2013-01-01

    Soil organic matter (SOM) in a peat soil, humic acid, and humin and their precursors (i.e., cellulose and lignin) were treated at high temperature (250 and 400 °C) with high pressure in a sealed platinum reaction kittle to simulate the influence of diagenesis on their composition and structure, and impact of the simulated diagenesis on sorption behaviors of hydrophobic organic compounds (HOCs) (i.e., naphthalene and 1-naphthol) by these samples was investigated. High temperature and pressure treatment greatly influenced chemical composition and physical properties of the original samples and their sorption for both naphthalene and 1-naphthol. Sorption of naphthalene by all samples was jointly regulated by hydrophobic and π-π interactions with their alkyl and aromatic carbon moieties, which was derived from the positive correlation between total hydrophobic carbon content of all sorbents and their organic carbon content-normalized sorption coefficients (Koc) for this compound (p = 0.075). However, sorption of 1-naphthol by the tested sorbents was governed by hydrogen bonding with their O-containing polar functionalities, as derived from the positive correlation between Koc values of 1-Naph and their polarity index ((O+N)/C). Difference in sorption mechanisms of naphthalene and 1-naphthol by the original and treated samples noted the great influence of chemical composition of sorbates on their interaction and essential roles of specific interactions (e.g., hydrogen bonding) in sorption of polar compound (i.e., 1-naphthol) to these sorbents. Surface area (SA) and porosity data of sorbents obtained from N2 sorption-desorption isotherms at 77 K showed that new SA and pores were created during the diagenetic process of all original samples, which provided substantial sorption sites and thus enhanced sorption of naphthalene and 1-naphthol. Among all tested samples, physicochemical properties of cellulose were most strongly affected by the simulated diagenetic process

  14. Jellyfish Lake, Palau: early diagenesis of organic matter in sediments of an anoxic marine lake

    USGS Publications Warehouse

    Orem, W.H.; Burnett, W.C.; Landing, W.M.; Lyons, W.B.; Showers, W.

    1991-01-01

    The major postdepositional change in the sedimentary organic matter is carbohydrate biodegradation. Lignin and aliphatic substances are preserved in the sediments. Dissolved organic matter in pore waters is primarily composed of carbohydrates, reflecting the degradation of sedimentary carbohydrates. Rate constants for organic carbon degradation and sulfate reduction in sediments of the lake are about 10?? lower than in other anoxic sediments. This may reflect the vascular plant source and partly degraded nature of the organic matter reaching the sediments of the lake. -from Authors

  15. Organic matter diagenesis as the key to a unifying theory for the genesis of tabular uranium-vanadium deposits in the Morrison Formation, Colorado Plateau

    USGS Publications Warehouse

    Hansley, P.L.; Spirakis, C.S.

    1992-01-01

    Interstitial, epigenetic amorphous organic matter is intimately associated with uranium in the Grants uranium region and is considered essential to genetic models for these deposits. In contrast, uranium minerals are intimately associated with authigenic vanadium chlorite and vanadium oxides in amorphous organic matter-poor ores of the Slick Rock and Henry Mountains mining districts and therefore, in some genetic models amorphous organic matter is not considered crucial to the formation of these deposits. Differences in organic matter content can be explained by recognizing that amorphous organic matter-poor deposits have been subjected to more advanced stages of diagenesis than amorphous organic matter-rich deposits. Evidence that amorphous organic matter was involved in the genesis of organic matter-poor, as well as organic matter-rich, deposits is described. -from Authors

  16. The early diagenesis of aliphatic hydrocarbons and organic matter in sedimentary particulates from Dabob Bay, Washington

    NASA Astrophysics Data System (ADS)

    Prahl, Fredrick G.; Bennett, Joseph T.; Carpenter, Roy

    1980-12-01

    Aliphatic hydrocarbon compositions were quantitatively characterized in plankton, sediment trap-collected particulate materials and sediments from Dabob Bay using high resolution glass capillary gas chromatography. The average net accumulation of individual hydrocarbons measured in a 1-yr series of sediment traps was compared with the net accumulation of corresponding compounds measured in three depth intervals of 210Pb-dated bottom sediments. Systematic and rapid decreases in the net accumulation of individual hydrocarbons were observed from the sediment traps to the sediments. Most pronounced decreases were measured for planktonically derived hydrocarbon constituents (e.g. pristane and two unsaturated compounds) which are rapidly remineralized at or near the sediment-water interface. Consequently, the amount of each compound measured in deposited sediments is not necessarily a quantitative indication of its initial flux to the sediments. The n-alkanes (C 25,27,29,31). characteristic of terrestrial plant waxes, are the predominant hydrocarbons measured by 4-6 cm depth in these sediments and show reasonably constant net accumulation below this interval. Significant diagenetic alteration of the bulk organic matter contained in the average sediment trap particulate material is also noted through comparison with bottom sediments on the basis of organic C/N and δ 13C measurements. Organic matter elementally similar to marine plankton is preferentially remineralized upon deposition of the sedimentary particulates. The residual organic matter remaining and buried in the bottom sediments closely resembles terrestrial organic matter.

  17. Diagenesis of Organic Matter in a Virginia Salt Marsh: Evaluation Through Compound Specific Isotope Analysis

    NASA Astrophysics Data System (ADS)

    Macko, S. A.; Geyer, M.

    2004-05-01

    Resolving the early diagenetic pathways to preservation of organic matter in a sedimentary sequence is one of the most intriguing challenges in organic geochemistry. What is preserved is usually ascribed to be either the product of retention of refractory materials or "protected" remnants of the destruction of the more labile matter, or more likely, a combination of both processes. A third mechanism, acquisition of newly synthesized material resulting from microbially mediated reactions, is less frequently invoked. In this study, the sources for the preserved organic matter and the sedimentary history of a Spartina marsh sequence on North Hog Island at the Virginia Coast Reserve Long Term Ecological Research (VCR-LTER) site are reported. Through the utilization of both carbon and nitrogen bulk isotopic compositions and compound specific isotopic analyses (CSIA) as well as the distributions of individual fatty acids, the depositional sequences are assessed. The variations in the cores for bulk organic carbon and nitrogen delta 13C and delta 15N typically ranged from -17 to -15 permil and +4 to +10 permil, respectively. The isotopic compositions generally show a trend of increasing in the heavy isotope downcore. These variations can be attributed to microbial utilization of amino acids resulting in bulk isotopic enrichments in deeper layers. Extensive microbial activity was evidenced at depth with increased amounts of odd-chain and branched-chain fatty acids. Overall, there is a decline with increasing depth in the amount of quantifiable fatty acids. Through the CSIA measurements, the original source of the preserved molecular components was observed to be essentially that of the Spartina, with loss of unsaturation deeper in the sequence. At greater depths, newly synthesized, longer-chain, unsaturated fatty acids were observed, possibly resulting from anaerobic pathways. Through mass balance using isotopic compositions of proposed bacterial endmember fatty acids, a

  18. Does anoxia affect organic matter preservation Diagenesis and burial of the major biochemicals under oxic and anoxic depositional conditions

    SciTech Connect

    Cowie, G.L. . Dept. of Oceanography); Hedges, J.I. . School of Oceanography)

    1992-01-01

    The role of anoxia in organic matter (OM) preservation in coastal sediments is tested directly using sediment trap and core samples from Dabob Bay (Washington State) and Saanich Inlet (British Columbia). These sites are similar in productivity, OM sources and sedimentation rates, but differ in that Dabob Bay bottom waters are permanently oxygenated whereas those of Saanich Inlet are anoxic except for occasional autumn flushing events. Samples were analyzed for organic carbon, nitrogen, amino acids, neutral sugars and lignin. Mixed terrigenous and marine OM sources are indicated at both sites, but there is a lower terrigenous OM contribution in Saanich Inlet than in Dabob Bay. Major, highly selective OM losses occur at the benthic interface of both sites with very similar reactivity patterns. The following general order of reactivity, equivalent to preferential loss of marine OM, is observed: total amino acids > total sugars [ge] nitrogen > organic carbon > lignin. Sedimentary diagenesis is less selective and less extensive, and in Dabob Bay is largely masked by bioturbation. Calculated biochemical losses at the benthic interface are consistently higher in Dabob Bay, possibly suggesting uniformly higher degradation rates under aerobic conditions, but most readily explained by mixing of surficial sediments. At both sites, there are also clear differences in calculated burial efficiency among the various measured OM components. However, despite OM source differences, burial efficiency values at the two sites are indistinguishable. These results indicate that anoxia ultimately has no measurable effect on OM preservation at these sites.

  19. A quantitative reconstruction of organic matter and nutrient diagenesis in Mediterranean Sea sediments over the Holocene

    NASA Astrophysics Data System (ADS)

    Reed, Daniel C.; Slomp, Caroline P.; de Lange, Gert J.

    2011-10-01

    A multicomponent diagenetic model was developed and applied to reconstruct the conditions under which the most recent sapropel, S1, was deposited in the eastern Mediterranean Sea. Simulations demonstrate that bottom waters must have been anoxic and sulphidic during the formation of S1 and that organic matter deposition was approximately three times higher than at present. Nevertheless, most present day sediment and pore water profiles — with the exception of pyrite, iron oxyhydroxides, iron-bound phosphorus and phosphate — can be reproduced under a wide range of redox conditions during formation of S1 by varying the depositional flux of organic carbon. As a result, paleoredox indicators (e.g., C org:S ratio, C org:P org ratio, trace metals) are needed when assessing the contribution of oxygen-depletion and enhanced primary production to the formation of organic-rich layers in the geological record. Furthermore, simulations show that the organic carbon concentration in sediments is a direct proxy for export production under anoxic bottom waters. The model is also used to examine the post-depositional alteration of the organic-rich layer focussing on nitrogen, phosphorus, and organic carbon dynamics. After sapropel formation, remineralisation is dominated by aerobic respiration at a rate that is inversely proportional to the time since bottom waters became oxic once again. A sensitivity analysis was undertaken to identify the most pertinent parameters in regulating the oxidation of sapropels, demonstrating that variations in sedimentation rate, depositional flux of organic carbon during sapropel formation, bottom water oxygen concentration, and porosity have the largest impact. Simulations reveal that sedimentary nutrient cycling was markedly different during the formation of S1, as well as after reoxygenation of bottom waters. Accumulation of organic nitrogen in sediments doubled during sapropel deposition, representing a significant nitrogen sink. Following

  20. Nitrogen isotope geochemistry of organic matter and minerals during diagenesis and hydrocarbon migration

    NASA Astrophysics Data System (ADS)

    Williams, Lynda B.; Ferrell, Ray E., Jr.; Hutcheon, Ian; Bakel, Allen J.; Walsh, Maud M.; Krouse, H. Roy

    1995-02-01

    The magnitude of isotopic variations between organic and inorganic nitrogen was examined in samples from three stacked hydrocarbon reservoirs in the Fordoche Field (Louisiana Gulf Coast Basin, USA). Measurements were made of δ 15N in kerogen, bitumen, oil, formation water, and fixed-NH 4 extracted from mudstones, nonproductive sandstones, and productive sandstones. Nitrogen isotope fractionation occurs because 14N is released preferentially to 15N from organic molecules during thermal maturation. Released 14N goes into solution, or may be adsorbed by minerals, leaving crude oil enriched in 15N. Diagenetic clay minerals (e.g., illite) commonly form in the temperature range of hydrocarbon generation, and NH 4+ may be fixed in clay interlayers with an isotopic ratio similar to that of the migrating fluids. Results indicate that the influence of organic matter on mineral δ 15N depends on the timing of authigenic mineral formation relative to fluid migration. The average δ 15N of kerogen (3.2 ± 0.3‰) and fixed-NH 4 from mudstones (3.0 ± 1.4) is similar, while bitumen increases from +3.5 to +5.1‰ with depth. In deep reservoir sandstones (>100°C), the δ 15N of crude oil averages +5.2 ± 0.4‰, similar to the δ 15N of bitumen in the proposed source rocks. Formation waters are 14N-enriched with an average δ 15N of -2.2 ± 2.6‰. Fixed-NH 4 δ 15N values lie between that of the oil and water. The average δ 15N of fixed-NH 4 is 3.0 ± 1.2‰ in productive sandstones, and 0.2 ± 2.4‰ innonproductive sandstones. In the shallower reservoir sandstones (<90°C) fixed-NH 4 is apparently not influenced by the presently associated fluids. Productive and nonproductive sandstones have distinctly low average δ 15N values (-1.2 ± 0.8‰), yet crude oil (+11.1 ± 0.3‰) and water (+3.8 ± 0.1‰) have been 15N-enriched by ˜6‰ relative to the deeper reservoirs. This suggests that the present fluids migrated into the reservoir after authigenic illite had formed

  1. Organic diagenesis in commercial nuclear wastes

    SciTech Connect

    Toste, A.P.; Lechner-Fish, T.J.

    1988-01-01

    The nuclear industry currently faces numerous challenges. Large volumes of already existing wastes must be permanently disposed using environmentally acceptable technologies. Numerous criteria must be addressed before wastes can be permanently disposed. Waste characterization is certainly one of the key criteria for proper waste management. some wastes are complex melting pots of inorganics, radiochemicals, and, occasionally, organics. It is clear, for example, that organics have been used extensively in nuclear operations, such as waste reprocessing, and continue to be used widely as solvents, decontamination agents, etc. The authors have analyzed the organic content of many kinds of nuclear wastes, ranging from commercial to defense wastes. In this paper, the finale analyses are described of three commercial wastes: one waste from a pressurized water reactor (PWR) and two wastes from a boiling water reactor (BWR). The PWR waste is a boric acid concentrate waste. The two BWR wastes, BWR wastes Nos. 1 and 2, are evaporator concentrates of liquid wastes produced during the regeneration of ion-exchange resins used to purify reactor process water. In preliminary analyses, which were reported previously, a few know organics and myriad unknowns were detected. Recent reexamination of mass-spectral data, coupled with reanalysis of the wastes, has resulted in the firm identification of the unknowns. Most of the compounds, over thirty distinct organics, are derived from the degradation, or diagenesis, of source-term organics, revealing, for the first time, that organic diagenesis in commercial wastes is both vigorous and varied.

  2. Organic carbon concentration profiles in recent cave sediments: records of agricultural pollution or diagenesis?

    PubMed

    Bottrell, S H

    1996-01-01

    Recent (<7 years old) cave sediments in Speedwell Cavern, Derbyshire, show an approximately exponential decay of organic carbon with depth. This phenomenon was thought to be due to one of two causes: (i) changing agricultural practice within the catchment feeding the cave, especially the increased use of sewage sludge and animal slurry as fertilizer; (ii) a relatively constant organic carbon concentration over time in the input sediment, with subsequent carbon mineralization during diagenesis. Carbon isotope composition of the organic material and the evolution of H/C ratio with depth indicate that the latter hypothesis is correct and that the profiles result from microbial diagenesis, not increased organic carbon inputs. By comparison with sediment of known (7 years) age, temporal decay constants for organic matter can be derived; these lie between rates previously determined for organic matter decomposition in marine sediments and soils. The H/C ratio of organic matter can be modelled as a function of time and proceeds in a similar fashion to soil organic material. PMID:15091425

  3. Distribution and diagenesis of organic and inorganic phosphorus in sediments of the Baltic proper.

    PubMed

    Edlund, G; Carman, R

    2001-11-01

    Measurements of the distribution of organic and inorganic phosphorus in the sediment have been performed at 10 sites, in the central-northern Baltic proper. Variations in deposition environment and environmental properties, such as redox chemistry and bottom water dynamics, apparently affect the distribution by altering the supply and diagenesis of organic and inorganic phosphorus constituents. The C/P and the N/P ratios of the sediment are highly divergent (higher) from the average Redfield ratio for marine living organisms at all examined sites. This indicates preferential autolytic organic phosphorus degradation and/or (deeper down in the sediment) altered input of terrestrial organic matter. The redox condition seems to affect the degradation efficiency of the organic matter since higher concentrations of C(org) occur at anoxic conditions than at oxic. At two sites significant amounts of C(inorg) have been detected indicating authigenic precipitation of carbonates. Further, authigenic precipitation of phosphate minerals also seems to occur at certain environmental conditions. PMID:11695582

  4. Amino acid diagenesis, organic carbon and nitrogen mineralization in surface sediments from the inner Oslofjord, Norway

    SciTech Connect

    Haugen, J.E. ); Lichtentaler, R. )

    1991-06-01

    Total hydrolyzed amino acids (THAA), total organic carbon (TOC), and total nitrogen (TN) have been measured in an oxic and anoxic surface sediment from the inner Oslofjord. Downcore variations of these parameters are ascribed to both diagenesis and changes in organic matter supply, the latter being most important. These changes are most prominent in the anoxic sediment, which reflects the eutrophication history of the innermost part of the fjord. Downcore, THAA content decreased from 3.8 to 2.0 mg/g (salt-free dry weight) in the oxic sediment and from 22.3 to 3.8 mg/g in the anoxic sediment. Total amino acid nitrogen varied between 17 and 34% of total nitrogen in the oxic, and 25 and 54% in the anoxic, sediment. Organic carbon and organic nitrogen accumulation rates and depth integrated mineralization rates are about three times higher in the anoxic sediment than in the oxic sediment. Recycling of amino acids accounted for 4 to 12% of the total organic carbon and 13 to 40% of the total organic nitrogen regenerated in these sediments.

  5. Sulfur diagenesis in marine sediments

    NASA Technical Reports Server (NTRS)

    Goldhaber, M.

    1985-01-01

    Bacterial sulfate reduction occurs in all marine sediments that contain organic matter. Aqueous sulfide (HS-, H2S), one of the initial products of bacterial sulfide reduction, is extremely reactive with iron bearing minerals: sulfur is fixed into sediments as iron sulfide (first FeS and then Fe2S2). A working definition is given of sulfur diagenesis in marine sediments. Controls and consequences of sulfate reduction rates in marine sediments are examined.

  6. soil organic matter fractionation

    NASA Astrophysics Data System (ADS)

    Osat, Maryam; Heidari, Ahmad

    2010-05-01

    Carbon is essential for plant growth, due to its effects on other soil properties like aggregation. Knowledge of dynamics of organic matter in different locations in the soil matrix can provide valuable information which affects carbon sequestration and soil the other soil properties. Extraction of soil organic matter (SOM) fractions has been a long standing approach to elucidating the roles of soil organic matter in soil processes. Several kind fractionation methods are used and all provide information on soil organic matter function. Physical fractionation capture the effects on SOM dynamics of the spatial arrangement of primary and secondary organomineral particles in soil while chemical fractionation can not consider the spatial arrangement but their organic fractions are suitable for advanced chemical characterization. Three method of physical separation of soil have been used, sieving, sedimentation and densitometry. The distribution of organic matter within physical fractions of the soil can be assessed by sieving. Sieving separates soil particles based strictly on size. The study area is located on north central Iran, between 35° 41'- 36° 01' N and 50° 42'- 51° 14' E. Mean annual precipitation about 243.8 mm and mean annual air temperature is about 14.95 °C. The soil moisture and temperature regime vary between aridic-thermic in lower altitudes to xeric-mesic in upper altitudes. More than 36 surface soil samples (0-20 cm) were collected according to land-use map units. After preliminary analyzing of samples 10 samples were selected for further analyses in five size fractions and three different time intervals in September, January and April 2008. Fractionation carried out by dry sieving in five classes, 1-2 mm, 0.5-1 mm, 270 μm-0.5mm, 53-270 μm and <53 μm. Organic matter and C/N ratio were determined for all fractions at different time intervals. Chemical fractionation of organic matter also carried out according to Tan (2003), also Mineralogical

  7. Is old organic matter simple organic matter?

    NASA Astrophysics Data System (ADS)

    Nunan, Naoise; Lerch, Thomas; Pouteau, Valérie; Mora, Philippe; Changey, Fréderique; Kätterer, Thomas; Herrmann, Anke

    2016-04-01

    Bare fallow soils that have been deprived of fresh carbon inputs for prolonged periods contain mostly old, stable organic carbon. In order to shed light on the nature of this carbon, the functional diversity profiles (MicroResp™, Biolog™ and enzyme activity spectra) of the microbial communities of long-term barefallow soils were analysed and compared with those of the microbial communities from their cultivated counterparts. The study was based on the idea that microbial communities adapt to their environment and that therefore the catabolic and enzymatic profiles would reflect the type of substrates available to the microbial communities. The catabolic profiles suggested that the microbial communities in the long-term bare-fallow soil were exposed to a less diverse range of substrates and that these substrates tended to be of simpler molecular forms. Both the catabolic and enzyme activity profiles suggested that the microbial communities from the long-term bare-fallow soils were less adapted to using polymers. These results do not fit with the traditional view of old, stable carbon being composed of complex, recalcitrant polymers. An energetics analysis of the substrate use of the microbial communities for the different soils suggested that the microbial communities from the long-term bare-fallow soils were better adapted to using readily oxidizable,although energetically less rewarding, substrates. Microbial communities appear to adapt to the deprivation of fresh organic matter by using substrates that require little investment.

  8. Scattered organic matter of carbonate rocks; main forms, evolutionary characteristics and importance in evaluating oil and gas content

    SciTech Connect

    Fu. J.; Jia, R.

    1984-01-01

    It is stated that in relation to the evolution of SOM in carbonate rocks, there are 2 important aspects related to the features of diagenesis of these rocks: 1) displacement of organic matter from the rock because of crystal growth, resulting in a decrease in the total quantity of organic matter in carbonates which is especially significant at early stages of diagenesis; 2) isolation (''protection'') of organic matter by the mineral mass which is the most characteristic for the late stages of diagenesis. The SOM of carbonate rocks can be divided into three types according to the nature of organic matter and the type of protection in diagenesis: 1) absorbed, 2) in crystallization traps, 3) organic inclusions. Protection by the mineral mass means that the processes of SOM metamorphism occurs very slowly, therefore determination of the degree of SOM maturity in the crystallization traps plays an important role in determining the generation potential of the carbonates. A large part of the inclusions is represented by organic matter which has migrated, therefore, study of the inclusion matter is important for studying the primary and secondary migration, as well as for hydrocarbon accumulation in the carbonates.

  9. Repetitive, multistage near surface and subsequent burial diagenesis in the Middle Ordovician Chickamauga organic buildups from Alabama

    SciTech Connect

    Tobin, K.J.; Walker, K.R.; Srinivasan, K. . Dept. of Geological Sciences)

    1992-01-01

    Middle Ordovician Chickamauga organic buildups from Red Mountain Expressway (RME) and Tidwell Hollow (TWH) in A have a complex diagenetic history when compared to approximately coeval Holston and Effna buildups of TN and VA. Near surface diagenetic history of the AL buildups at RME consists of two phases of marine and meteoric diagenesis. At TWH meteoric diagenesis occurred between initial and final generations of marine diagenesis. Initial marine diagenesis consisted of decay of sponges and dasyclad algae forming molds, micritization of fossils, and minor precipitation of fibrous calcite and turbid syntaxial overgrowths. A relative sea level rise at the top of the chickamauga is recorded by minor precipitation of fibrous calcite in selective voids and on equant calcite substrates suggestive of replacement of meteoric fluids in voids by marine waters. Extensive development of selective and non-selective porosity occurred during the final meteoric phase. Voids have the following occlusion history: (1) [+-] initial precipitation of a thin layer of equant calcite, (2) peloidal and/or micritic internal sedimentation, (3) [+-] deposition of turbid vadose silt, and (4) precipitation of pore-central equant (drusy) calcite. All meteoric features described above occurred during single generation at TWH and were associated with an exposure surface. A meteoric origin for equant calcite cements is supported by stable isotopic data which is slightly depleted relative to original marine compositions obtained from other Middle Ordovician buildups in the Southern Appalachians. In summary, porosity development is related to extensive subaerial exposure and the lack of continuously increasing burial immediately after deposition. The Holston and Effna buildups were buried under thick onlap sequences immediately after deposition.

  10. Thermodynamic simulation of the interaction of the system “water - mineral sediment - organic matter” at the diagenesis stage

    NASA Astrophysics Data System (ADS)

    Sidkina, E. S.; Rizhenko, B. N.; Cherkasova, E. V.

    2016-03-01

    The current study examines thermodynamic calculations of interaction of the “water - mineral sediment - organic matter” system at temperatures and pressures of diagenesis. In the course of reactions mature kerogen forms in the system, mainly C292H288O12, rarely C128H68O7 including accompanying substances (hydrocarbons, nitrogen compounds). The removal of CO2(g) and N2 (g) from the system promotes the reaction. It is found that the aqueous phase during the formation of kerogen does not change significantly. In general, there occur desalination and changes of pH and Eh, as well as the increase in dissolved CO2 content in water composition.

  11. Black shale - its deposition and diagenesis.

    USGS Publications Warehouse

    Tourtelot, H.A.

    1979-01-01

    Depositional processes involve a range of relationships among such factors as organic productivity, clastic sedimentation rate, and the intensity of oxidation by which organic matter is destroyed. If enough organic material is present to exhaust the oxygen in the environment, black shale results. During diagenesis for a thickness of a few meters beneath the surface, sulfate is reduced and sulfide minerals may be deposited. Fermentation reactions in the next several hundred meters result in biogenic methane, followed successively at greater depths by decarboxylation reactions and thermal maturation that form additional hydrocarbons. -from Author

  12. Arctic River organic matter transport

    NASA Astrophysics Data System (ADS)

    Raymond, Peter; Gustafsson, Orjan; Vonk, Jorien; Spencer, Robert; McClelland, Jim

    2016-04-01

    Arctic Rivers have unique hydrology and biogeochemistry. They also have a large impact on the Arctic Ocean due to the large amount of riverine inflow and small ocean volume. With respect to organic matter, their influence is magnified by the large stores of soil carbon and distinct soil hydrology. Here we present a recap of what is known of Arctic River organic matter transport. We will present a summary of what is known of the ages and sources of Arctic River dissolved and particulate organic matter. We will also discuss the current status of what is known about changes in riverine organic matter export due to global change.

  13. Carbon dioxide and organic acids: origin and role in burial diagenesis (Texas Gulf Coast Tertiary)

    SciTech Connect

    Lundegard, P.D.

    1985-01-01

    Carbon dioxide produced by decarboxylation of organic matter is not a dominant factor in secondary porosity development. Material balance calculations indicate the amount of feldspar and carbonate dissolution that has taken place in Tertiary sandstones of the Texas Gulf Coast far exceeds that which is explainable by decarboxylation. Other potential sources of acid for dissolution reactions include reverse weathering reactions in shales, an hydrous pyrolysis reactions between organic carbon and oxygen in H/sub 2/O to yield CO/sub 2/ or organic acids. Considerations of CO/sub 2/ solubility and the temperature distribution of organic acids imply that these species must be generated locally to cause significant dissolution. The CO/sub 2/ content of gas from Gulf Coast Tertiary sandstones is proportional to reservoir age, and increases with depth and temperature at a rate that is approximately exponential. In the Wilcox Formation the increase in CO/sub 2/ content continues beyond depths where dissolved organic acids are abundant and where kerogen has lost its oxygen from functional groups that are readily liberated as CO/sub 2/. In this formation the /sup 13/C of CO/sub 2/ and CH/sub 4/ are proportional to temperature and to each other. Either mixing with fluids derived from the Mesozoic carbonate section of deep CO/sub 2/ generation by kinetically controlled organic reactions may explain these data. Organic acid concentration with depth and temperature indicates a non-biological origin by thermal cracking of kerogen during burial. Continued burial leads to their thermal decomposition. Cessation of burial may lead to meteoric water invasion and organic acid destruction by biological processes. The effect of time on organic acid production is minor compared to temperature.

  14. Origin distribution and alteration of organic matter and generation and migration of hydrocarbons in Austin Chalk, Upper Cretaceous, Southeastern Texas

    NASA Astrophysics Data System (ADS)

    Grabowski, G. J., Jr.

    1981-08-01

    The Austin Chalk is an impure onshore chalk that was deposited on a ramp marginal to the Gulf of Mexico during the Late Cretaceous. Basinal chalks are organic rich, commonly containing 0.5-5.0% amorphous, sapropelic kerogen derived from marine organic matter with only trace amounts of terrestial kerogen. Less organic matter was deposited and perserved in oxygenated shallow water, and fresh-water diagenesis oxidized the organic matter on outcrop. In each sample, the kerogen is concentrated in microstylolites, with organic fluids segregated in micropores in the chalk.

  15. Estrone degradation: does organic matter (quality), matter?

    PubMed

    Tan, David T; Temme, Hanna R; Arnold, William A; Novak, Paige J

    2015-01-01

    Understanding the parameters that drive E1 degradation is necessary to improve existing wastewater treatment systems and evaluate potential treatment options. Organic matter quality could be an important parameter. Microbial communities grown from activated sludge seeds using different dissolved organic matter sources were tested for E1 degradation rates. Synthetic wastewater was aged, filter-sterilized, and used as a carbon and energy source to determine if recalcitrant organic carbon enhances E1 degradation. Higher E1 degradation was observed by biomass grown on 8 d old synthetic wastewater compared to biomass grown on fresh synthetic wastewater (P = 0.033) despite much lower concentrations of bacteria. Minimal or no E1 degradation was observed in biomass grown on 2 d old synthetic wastewater. Organic carbon analyses suggest that products of cell lysis or microbial products released under starvation stress stimulate E1 degradation. Additional water sources were also tested: lake water, river water, and effluents from a municipal wastewater treatement plant and a treatment wetland. E1 degradation was only observed in biomass grown in treatment effluent. Nitrogen, dissolved organic carbon, and trace element concentrations were not causative factors for E1 degradation. In both experiments, spectrophotometric analyses reveal degradation of E1 is associated with microbially derived organic carbon but not general recalcitrance. PMID:25454582

  16. Study of the organic matter in the DSDP /JOIDES/ cores, legs 10-15. [Deep Sea Drilling Program

    NASA Technical Reports Server (NTRS)

    Simoneit, B. R. T.; Burlingame, A. L.

    1974-01-01

    The composition of the organic matter collected on legs 10 to 15 of the DSDP (Deep Sea Drilling Project) is described. Distributions of various alkanes, carboxylic acids, steroids and terpenoids, isoprenoid ketones and olefins, and aromatic polycyclic compounds are given. Samples analyzed had terrigenous clay components, with variable organic carbon contents and thus diverse solvent soluble matter. The distribution patterns for the various compound series monitored were of marine derivation, with the terrigenous components superimposed. Diagenesis of steroids appeared to proceed via both stanones and stanols to their respective steranes. Degradative processes were observed to be operative: oxidative products, mainly ketones derived from steroids and phytol, were identified, probably due to microbial alteration prior to or during sedimentation. Loss of alkane and fatty acid C preferences and presence of polycyclic aromatics evinced maturation. Results indicate that the accumulation, degradation, diagenesis and maturation of organic matter occurs in various steps in the deep sea environment.

  17. Interstellar organic matter in meteorites

    NASA Technical Reports Server (NTRS)

    Yang, J.; Epstein, S.

    1983-01-01

    Deuterium-enriched hydrogen is present in organic matter in such meteorites as noncarbonaceous chondrites. The majority of the unequilibrated primitive meteorites contain hydrogen whose D/H ratios are greater than 0.0003, requiring enrichment (relative to cosmic hydrogen) by isotope exchange reactions taking place below 150 K. The D/H values presented are the lower limits for the organic compounds derived from interstellar molecules, since all processes subsequent to their formation, including terrestrial contamination, decrease their D/H ratios. In contrast, the D/H ratios of hydrogen associated with hydrated silicates are relatively uniform for the meteorites analyzed. The C-13/C-12 ratios of organic matter, irrespective of D/H ratio, lie well within those observed for the earth. Present findings suggest that other interstellar material, in addition to organic matter, is preserved and is present in high D/H ratio meteorites.

  18. Diagenesis and catagenesis of marine kerogen precursors

    SciTech Connect

    Rafalska-Bloch, J.

    1987-01-01

    The approaches used were (1) investigations of marine kerogen precursors in a natural environment, e.g., in reefal carbonate sediments (in Puerto Rico and Belize) and (2) laboratory modeling of the condensation of marine kerogen precursors, i.e., amino acids and sugars and subsequent formation and reactions of melanoidin polymers. The organic facies model of a reef environment was developed from the analysis of (1) total organic carbon, (2) visual protokerogen types, (3) Rock-Eval indices and (4) sedimentological considerations. Rates of melanoidin formation, incorporation of amino acid and glucose into the melanoidin polymers and their attendant decrease in the melanoidin solutions were evaluated. The observed pattern was that of initially rapid loss of biomonomers from the melanoidin solutions and concomitant formation of melanoidin polymers. The rate of incorporation of amino acids into the polymers is related partly to glucose concentration and partly to the type of amino acid. The racemization rates of amino acids were also investigated. During the course of melanoidin formation the original amino acid abundances and stereochemistry are redistributed during simulated diagenesis. This may have implications for natural environments where diagenesis may obscure the original depositional signal and complicate geochronological studies. Catagenetic evolution of both synthetic geopolymer (lysine, histidine, arginine, glucose - melanoidin) and natural geopolymers (Belizian organic matter) was simulated using hydrous pyrolysis.

  19. Dissolved organic matter in anoxic pore waters from Mangrove Lake, Bermuda

    USGS Publications Warehouse

    Orem, W.H.; Hatcher, P.G.; Spiker, E. C.; Szeverenyi, N.M.; Maciel, G.E.

    1986-01-01

    Dissolved organic matter and dissolved inorganic chemical species in anoxic pore water from Mangrove Lake, Bermuda sediments were studied to evaluate the role of pore water in the early diagenesis of organic matter. Dissolved sulphate, titration alkalinity, phosphate, and ammonia concentration versus depth profiles were typical of many nearshore clastic sediments and indicated sulphate reduction in the upper 100 cm of sediment. The dissolved organic matter in the pore water was made up predominantly of large molecules, was concentrated from large quantities of pore water by using ultrafiltration and was extensively tudied by using elemental and stable carbon isotope analysis and high-resolution, solid state 13C nuclear magnetic resonance and infrared spectroscopy. The results indicate that this material has a predominantly polysaccharide-like structure and in addition contains a large amount of oxygen-containing functional groups (e.g., carboxyl groups). The 13C nulcear magnetic resonance spectra of the high-molecular-weight dissolved organic matter resemble those of the organic matter in the surface sediments of Mangrove Lake. We propose that this high-molecular-weight organic matter in pore waters represents the partially degraded, labile organic components of the sedimentary organic matter and that pore waters serve as a conduit for removal of these labile organic components from the sediments. The more refractory components are, thus, selectively preserved in the sediments as humic substances (primarily humin). ?? 1986.

  20. Organic matter and benthic metabolism in Lake Illawarra, Australia

    NASA Astrophysics Data System (ADS)

    Qu, Wenchuan; Morrison, R. J.; West, R. J.; Su, Chenwei

    2006-10-01

    Carbon and nitrogen contents (total organic carbon and total nitrogen), chlorophyll-a concentrations in surface sediments and benthic sediment-water fluxes of oxygen and carbon dioxide were investigated at five stations in Lake Illawarra (Australia) to compare the sources/quality of sedimentary organic matter and the characteristics of diagenesis and benthic biogeochemical processes for different primary producers (e.g., seagrass, microphytobenthos and macroalgae) and/or sediment types (sand or mud). The unvegetated sediments showed lower C/N ratios (with the lowest value occurring in the deep organic-rich muddy site) than the seagrass ( Ruppia or Zostera) beds, which may be due to the contribution of microalgae (mainly diatoms) to the sedimentary organic matter pool. This was also supported by the detection of microalgal pigments in the bare sediments. On an annual basis, seagrass beds exhibited the highest gross primary productivity (O 2 or TCO 2 fluxes), while the lowest rates occurred in the deep central basin of the Lake. Seasonally, there was a general trend of highest production in spring or summer, and lowest production in winter or autumn. Organic carbon oxidation scenarios, evaluated by either calcium carbonate dissolution or sulfate reduction models, indicated that both models can explain organic matter mineralization. Trophic status was evaluated using different indices including benthic trophic state index, net O 2 fluxes and P/ R ratios for Lake Illawarra, which led to similar trophic classifications in general, and also the same trends in spatial and seasonal variations. Overall, these data indicated that the Lake was heterotrophic on an annual basis, as the total community carbon respiration exceeded production, and this supported an earlier LOICZ mass balance/stoichiometric modelling conclusion.

  1. Depletion of 13C in Cretaceous marine organic matter: Source, diagenetic, or environmental sigal?

    USGS Publications Warehouse

    Dean, W.E.; Arthur, M.A.; Claypool, G.E.

    1986-01-01

    Geochemical studies of Cretaceous strata rich in organic carbon (OC) from Deep Sea Drilling Project (DSDP) sites and several land sections reveal several consistent relationships among amount of OC, hydrocarbon generating potential of kerogen (measured by pyrolysis as the hydrogen index, HI), and the isotopic composition of the OC. First, there is a positive correlation between HI and OC in strata that contain more than about 1% OC. Second, percent OC and HI often are negatively correlated with carbon isotopic composition (?? 13C) of kerogen. The relationship between HI and OC indicates that as the amount of organic matter increases, this organic matter tends to be more lipid rich reflecting the marine source of the organic matter. Cretaceous samples that contain predominantly marine organic matter tend to be isotopically lighter than those that contain predominantly terrestrial organic matter. Average ?? 13C values for organic matter from most Cretaceous sites are between -26 and -28???, and values heavier than about -25??? occur at very few sites. Most of the ?? 13C values of Miocene to Holocene OC-rich strata and modern marine plankton are between -16 to -23???. Values of ??13C of modern terrestrial organic matter are mostly between -23 and -33???. The depletion of terrestial OC in 13C relative to marine planktonic OC is the basis for numerous statements in the literature that isotopically light Cretaceous organic matter is of terrestrial origin, even though other organic geochemical and(or) optical indicators show that the organic matter is mainly of marine origin. A difference of about 5??? in ?? 13C between modern and Cretaceous OC-rich marine strata suggests either that Cretaceous marine planktonic organic matter had the same isotopic signature as modern marine plankton and that signature has been changed by diagenesis, or that OC derived from Cretaceous marine plankton was isotopically lighter by about 5??? relative to modern plankton OC. Diagenesis does

  2. Early organic diagenesis: The significance of progressive subsurface oxidation fronts in pelagic sediments

    NASA Astrophysics Data System (ADS)

    Wilson, T. R. S.; Thomson, J.; Colley, S.; Hydes, D. J.; Higgs, N. C.; Sørensen, J.

    1985-03-01

    Porewater and solid phase geochemical data at two contrasting NE Atlantic stations are reported. Station 10552, on the Cape Verde abyssal plain, is a site of slow pelagic accumulation ( ca. 0.4 cm kyr -1). Molecular oxygen is present in the sediment column to at least 2 m, and probably much deeper, labile organic-carbon is almost totally consumed in the upper few centimetres of the sediment. By contrast, at station 10554 on the Madeira abyssal plain, the pelagic sequence has been interrupted by the occasional deposition of organic-rich turbidites. Porewater oxygen and nitrate profiles show that subsurface organic metabolism of the organic-carbon associated with the uppermost turbidite layer is a significant fraction of the overall metabolism in the sediment column. This metabolism occurs at a relatively thin reaction front which progresses deeper into the turbidite with time. This phenomenon exerts a controlling influence on the present nutrient profile and redox succession. In a less extreme form, substrate distributions of this latter type are not uncommon in Atlantic sediments. A model has been developed which is controlled by both oxygen and nitrate data. This model permits a vertical profile of metabolic activity to be derived, and also gives estimates of the reaction rate constants and solid phase mixing rates at these two contrasting stations. About 30% of the total activity at station 10554 is located within the turbidite at the deepening reaction front; this is a non-steady-state condition. In fact, it is found that the integrated metabolic activity at the two stations is not dissimilar ( ca. 1-2 × 10 -13moles cm -2 sec -1). The striking differences in redox profile are therefore primarily attributable to differences in the distribution of metabolic activity within the column.

  3. The fate of terrestrial organic matter in two Scottish sea lochs

    NASA Astrophysics Data System (ADS)

    Loh, P. S.; Reeves, A. D.; Harvey, S. M.; Overnell, J.; Miller, A. E. J.

    2008-02-01

    Sea lochs are zones of rapid organic matter (OM) turnover. Most of this OM is of allochthonous origin, being introduced into the lochs via freshwater input. In this study the behaviour of terrestrially derived OM was elucidated using a combination of parameters which indicate OM diagenesis in the near surface sediments from two Scottish sea lochs, Loch Creran and Loch Etive. Alkaline CuO oxidation was used to determine lignin phenols which serve as biomarkers for terrestrial OM in sediments. Stable carbon isotope, total carbon and nitrogen and total OM (including the labile and refractory fractions) compositions were also determined. Lignin materials in the lochs were generally highly degraded and undergo little degradation further seaward. The vanillic acid to vanillin ratio, (Ad/Al)v in the lochs ranged from 0.52 to 2.69. However, there was a fraction of relatively fresh, land-derived OM, still undergoing degradation adding to the carbon cycling in the lochs, as indicated by the Rp values (ratio of refractory to total OM) and OC/N ratios in the surface sediments. The hydrological and hydrodynamic regimes in Loch Creran result in several phenomena such as the transportation of terrestrial debris via hydrodynamic sorting processes and the promotion of surface sediment diagenesis by bioturbation. Frequent water renewal results in better water circulation and oxygenation which facilitate OM decomposition. In Loch Etive the less frequent renewal gives rise to a more constant OM diagenesis along the loch.

  4. Extraterrestrial organic matter: a review.

    PubMed

    Irvine, W M

    1998-10-01

    We review the nature of the widespread organic material present in the Milky Way Galaxy and in the Solar System. Attention is given to the links between these environments and between primitive Solar System objects and the early Earth, indicating the preservation of organic material as an interstellar cloud collapsed to form the Solar System and as the Earth accreted such material from asteroids, comets and interplanetary dust particles. In the interstellar medium of the Milky Way Galaxy more than 100 molecular species, the bulk of them organic, have been securely identified, primarily through spectroscopy at the highest radio frequencies. There is considerable evidence for significantly heavier organic molecules, particularly polycyclic aromatics, although precise identification of individual species has not yet been obtained. The so-called diffuse interstellar bands are probably important in this context. The low temperature kinetics in interstellar clouds leads to very large isotopic fractionation, particularly for hydrogen, and this signature is present in organic components preserved in carbonaceous chondritic meteorites. Outer belt asteroids are the probable parent bodies of the carbonaceous chondrites, which may contain as much as 5% organic material, including a rich variety of amino acids, purines, pyrimidines, and other species of potential prebiotic interest. Richer in volatiles and hence less thermally processed are the comets, whose organic matter is abundant and poorly characterized. Cometary volatiles, observed after sublimation into the coma, include many species also present in the interstellar medium. There is evidence that most of the Earth's volatiles may have been supplied by a 'late' bombardment of comets and carbonaceous meteorites, scattered into the inner Solar System following the formation of the giant planets. How much in the way of intact organic molecules of potential prebiotic interest survived delivery to the Earth has become an

  5. Extraterrestrial organic matter: a review

    NASA Technical Reports Server (NTRS)

    Irvine, W. M.

    1998-01-01

    We review the nature of the widespread organic material present in the Milky Way Galaxy and in the Solar System. Attention is given to the links between these environments and between primitive Solar System objects and the early Earth, indicating the preservation of organic material as an interstellar cloud collapsed to form the Solar System and as the Earth accreted such material from asteroids, comets and interplanetary dust particles. In the interstellar medium of the Milky Way Galaxy more than 100 molecular species, the bulk of them organic, have been securely identified, primarily through spectroscopy at the highest radio frequencies. There is considerable evidence for significantly heavier organic molecules, particularly polycyclic aromatics, although precise identification of individual species has not yet been obtained. The so-called diffuse interstellar bands are probably important in this context. The low temperature kinetics in interstellar clouds leads to very large isotopic fractionation, particularly for hydrogen, and this signature is present in organic components preserved in carbonaceous chondritic meteorites. Outer belt asteroids are the probable parent bodies of the carbonaceous chondrites, which may contain as much as 5% organic material, including a rich variety of amino acids, purines, pyrimidines, and other species of potential prebiotic interest. Richer in volatiles and hence less thermally processed are the comets, whose organic matter is abundant and poorly characterized. Cometary volatiles, observed after sublimation into the coma, include many species also present in the interstellar medium. There is evidence that most of the Earth's volatiles may have been supplied by a 'late' bombardment of comets and carbonaceous meteorites, scattered into the inner Solar System following the formation of the giant planets. How much in the way of intact organic molecules of potential prebiotic interest survived delivery to the Earth has become an

  6. Photodissolution of soil organic matter

    USGS Publications Warehouse

    Mayer, L.M.; Thornton, K.R.; Schick, L.L.; Jastrow, J.D.; Harden, J.W.

    2012-01-01

    Sunlight has been shown to enhance loss of organic matter from aquatic sediments and terrestrial plant litter, so we tested for similar reactions in mineral soil horizons. Losses of up to a third of particulate organic carbon occurred after continuous exposure to full-strength sunlight for dozens of hours, with similar amounts appearing as photodissolved organic carbon. Nitrogen dissolved similarly, appearing partly as ammonium. Modified experiments with interruption of irradiation to include extended dark incubation periods increased loss of total organic carbon, implying remineralization by some combination of light and microbes. These photodissolution reactions respond strongly to water content, with reaction extent under air-dry to fully wet conditions increasing by a factor of 3-4 fold. Light limitation was explored using lamp intensity and soil depth experiments. Reaction extent varied linearly with lamp intensity. Depth experiments indicate that attenuation of reaction occurs within the top tens to hundreds of micrometers of soil depth. Our data allow only order-of-magnitude extrapolations to field conditions, but suggest that this type of reaction could induce loss of 10-20% of soil organic carbon in the top 10. cm horizon over a century. It may therefore have contributed to historical losses of soil carbon via agriculture, and should be considered in soil management on similar time scales. ?? 2011 Elsevier B.V.

  7. The contentious nature of soil organic matter.

    PubMed

    Lehmann, Johannes; Kleber, Markus

    2015-12-01

    The exchange of nutrients, energy and carbon between soil organic matter, the soil environment, aquatic systems and the atmosphere is important for agricultural productivity, water quality and climate. Long-standing theory suggests that soil organic matter is composed of inherently stable and chemically unique compounds. Here we argue that the available evidence does not support the formation of large-molecular-size and persistent 'humic substances' in soils. Instead, soil organic matter is a continuum of progressively decomposing organic compounds. We discuss implications of this view of the nature of soil organic matter for aquatic health, soil carbon-climate interactions and land management. PMID:26595271

  8. Control of organic matter on the magnetic properties of surficial marine sediments. A simple kinetic model

    NASA Astrophysics Data System (ADS)

    Mohamed Falcon, K. J.; Andrade, A.; Rey, D.; Rubio, B.

    2014-12-01

    Magnetic properties of marine sediments in the Galician Rias, in NW Spain, have shown that in these shallow marine settings the magnetic mineral assemblage, and its bulk magnetic properties, is controlled by grain size, wave climate, and organic matter content. The grain size effect is explained by concentration of diamagnetic biogenic carbonates in the coarse fraction, which dilutes the concentration-dependent magnetic properties. Furthermore, this effect is enhanced by the hydrodynamic sorting of the heavy minerals, like magnetite, that become concentrated in the finer fractions. Waves on the other hand concentrate the coarser bioclasts in the shallower areas along the coastal margins of the rias, and consequently these areas show the lowest magnetic mineral concentrations. Magnetic minerals are therefore more abundant in the deeper central axis and towards the external, more oceanic, areas of the rias. Another effect of waves is periodic resuspension of fine sediments, which allows them to be reoxigenated preventing the onset of reductive diagenesis. This effect is best seen in sediment cores, where organic matter remineralization promotes dissolution of magnetic iron oxides and oxyhydroxides. Areas where resuspension is frequent and/or deeper areas where sediments stay in the water column for longer have lower degrees of reductive early diagenesis. In addition to its downcore effect, organic matter also controls the magnetic properties of surficial sediments. Our results in the Ria de Muros, at the north of our study area, have shown that a simple kinetic model is enough to quantify the effect of organic matter content on the dissolution of magnetite. We have found that a Total Organic Carbon increase of 0.35% reduces magnetite concentration of surface samples by half. These effects observed in the Ria de Muros have also been confirmed for published results in the southern Rias Baixas previously studied by our research group.

  9. Priming of native soil organic matter by pyrogenic organic matter

    NASA Astrophysics Data System (ADS)

    DeCiucies, Silene; Dharmakeerthi, Saman; Whitman, Thea; Woolf, Dominic; Lehmann, Johannes

    2015-04-01

    Priming, in relation to pyrogenic organic matter (PyOM), describes the change in mineralization rate of non-pyrogenic ("native") soil organic matter (nSOM) due to the addition of PyOM. Priming may be 'positive', in that the addition of pyC increases the mineralization rate of native SOM, or 'negative', in that the mineralization rate of nSOM is decreased. Reasons for increased mineralization may include: (i) co-metabolism: microbial decomposition of labile C-additions increases microbial activity, and facilitates additional decomposition of npSOC by active enzymes; (ii) stimulation: substrate additions result in lifted pH, nutrient, oxygen, or water constraints resulting in increased microbial activity. Decreased mineralization may be a result of: (i) inhibition: the opposite of stimulation whereby constraints are aggravated by substrate addition. Substrate addition may also cause inhibition by interfering with enzymes or signaling compounds; (ii) preferential substrate utilization: labile fraction of PyOM additions are preferentially used up by microbes thus causing a decrease in nSOC decomposition; (iii) sorption: organic compounds are adsorbed onto PyOM surfaces, decreasing their rate of mineralization; (iv) stabilization: formation of organo-mineral associations forms stable SOC pools. We have conducted a suite of experiments to investigate these potential interactions. In a seven year long incubation study, PyOM additions increased total OM mineralization for the first 2.5 years, was equal to control after 6.2 years, and was 3% lower after 7.1 years. Cumulative nSOM mineralization was 23% less with the PyOM additions than without, and over 60% of the added PyOM was present in the labile soil fraction after the 7.1 year incubation. Two additional incubation studies, one with and without plants, showed greater nSOM mineralization in the short term and lower nSOM mineralization over the long term. Increased nSOC mineralization due to the presence of plants was

  10. Rare earth elements and neodymium isotopes in sedimentary organic matter

    NASA Astrophysics Data System (ADS)

    Freslon, Nicolas; Bayon, Germain; Toucanne, Samuel; Bermell, Sylvain; Bollinger, Claire; Chéron, Sandrine; Etoubleau, Joel; Germain, Yoan; Khripounoff, Alexis; Ponzevera, Emmanuel; Rouget, Marie-Laure

    2014-09-01

    (inferred from the analysis of local surface seawater). A notable exception is the case of organic matter (OM) fractions leached from cold seep sediment samples, which sometimes exhibit εNd values markedly different from both terrigenous and surface seawater signatures. This suggests that a significant fraction of organic compounds in these sediments may be derived from chemosynthetic processes, recycling pore water REE characterized by a distinct isotopic composition. Overall, our results confirm that organic matter probably plays an important role in the oceanic REE budget, through direct scavenging and remineralization within the water column. Both the high REE abundances and the shape of shale-normalized patterns for leached SOM also suggest that OM degradation in sub-surface marine sediments during early diagenesis could control, to a large extent, the distribution of REE in pore waters. Benthic fluxes of organic-bound REE could hence substantially contribute to the exchange processes between particulates and seawater that take place at ocean margins. Neodymium isotopes could provide useful information for tracing the origin (terrestrial versus marine) and geographical provenance of organic matter, with potential applications in paleoceanography. In particular, future studies should further investigate the potential of Nd isotopes in organic compounds preserved in sedimentary records for reconstructing past variations of surface ocean circulation.

  11. Direct evidence for organic carbon preservation as clay-organic nanocomposites in a Devonian black shale; from deposition to diagenesis

    NASA Astrophysics Data System (ADS)

    Kennedy, Martin John; Löhr, Stefan Carlos; Fraser, Samuel Alex; Baruch, Elizabeth Teresa

    2014-02-01

    The burial of marine sourced organic carbon (OC) in continental margin sediments is most commonly linked to oceanographic regulation of bottom-water oxygenation (anoxia) and/or biological productivity. Here we show an additional influence in the Devonian Woodford Shale, in which OC occurs as nanometer intercalations with specific phyllosilicate minerals (mixed-layer illite/smectite) that we term organo-mineral nanocomposites. High resolution transmission electron microscopic (HRTEM) images provide direct evidence of this nano-scale relationship. While discrete micron-scale organic particles, such as Tasmanites algal cysts, are present in some lamina, a strong relation between total organic carbon (TOC) and mineral surface area (MSA) over a range of 15% TOC indicate that the dominant association of organic carbon is with mineral surfaces and not as discrete pelagic grains, consistent with HRTEM images of nanocomposites. Where periods of oxygenation are indicated by bioturbation, this relationship is modified by a shift to lower OC loading on mineral surfaces and reduced MSA variability likely resulting from biological mixing and homogenization of the sediment, oxidative burn down of OC and/or stripping of OC from minerals in animal guts. The TOC-MSA relationship extends across a range of burial depths and thermal maturities into the oil window and persists through partial illitization. Where illitization occurs, the loss of mineral surface area associated with the collapse of smectite interlayer space results in a systematic increase in TOC:MSA and reorganization of organic carbon and clays into nano-scale aggregates. While the Woodford Shale is representative of black shale deposits commonly thought to record heightened marine productivity and/or anoxia, our results point to the importance of high surface area clay minerals for OC enrichment. Given that the vast majority of these clay minerals are formed in soils before being transported to continental margin

  12. Soil Organic Matter in Agricultural Systems

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In agricultural systems, soil organic matter (SOM) has been recognized as an important source of nutrients and maintains favorable soil structure. Organic matter is considered a major binding agent that stabilizes soil aggregates. Soil aggregates especially, water stable aggregates, are important i...

  13. Isotopic composition of pyrite: Relationship to organic matter type and iron availability in some North American cretaceous shales

    USGS Publications Warehouse

    Gautier, D.L.

    1987-01-01

    The S isotope composition of pyrite in Cretaceous shales from the Western Interior of North America is related to organic C abundance, kerogen type and Fe availability. Both calcareous and noncalcareous rocks show a correlation between S and C, but noncalcareous rocks are relatively enriched in S with a higher S C ratio. This higher ratio probably shows that pyrite formation was Fe limited in the calcareous rocks. Organic-carbon-rich noncalcareous shales accumulated slowly beneath anoxic bottom waters. The anoxic bottom waters allowed hydrogen-rich organic matter to be preserved. Such shales have a narrow range of 34S-depleted sulfide and have Fe S ratios like stoichiometric pyrite, suggesting that pyrite formation in organic-rich shales was also limited by Fe availability. Conversely, organic-poor shales commonly accumulated at comparatively high rates, contain hydrogen-poor and refractory organic matter, and have a wide range of pyrite-S isotopic compositions. These organic-poor shales contain post-sulfidic authigenic minerals such as siderite and have excess reactive Fe rather than pyrite stoichiometry. Evidently Fe played a large role in early diagenesis and determined the course of post-sulfidic diagenesis. Fe availability was, however, mainly controlled by provenance, by the rates of sediment accumulation, and by the oxygen content of the depositional environment. ?? 1987.

  14. Environmental factors regulating soil organic matter chlorination

    NASA Astrophysics Data System (ADS)

    Svensson, Teresia; Montelius, Malin; Reyier, Henrik; Rietz, Karolina; Karlsson, Susanne; Lindberg, Cecilia; Andersson, Malin; Danielsson, Åsa; Bastviken, David

    2016-04-01

    Natural chlorination of organic matter is common in soils. Despite the widespread abundance of soil chlorinated soil organic matter (SOM), frequently exceeding soil chloride abundance in surface soils, and a common ability of microorganisms to produce chlorinated SOM, we lack fundamental knowledge about dominating processes and organisms responsible for the chlorination. To take one step towards resolving the terrestrial chlorine (Cl) puzzle, this study aims to analyse how environmental factors influence chlorination of SOM. Four factors were chosen for this study: soil moisture (W), nitrogen (N), chloride (Cl) and organic matter quality (C). These factors are all known to be important for soil processes. Laboratory incubations with 36Cl as a Cl tracer were performed in a two soil incubation experiments. It was found that addition of chloride and nitrogen seem to hamper the chlorination. For the C treatment, on the other hand, the results show that chlorination is enhanced by increased availability of labile organic matter (glucose and maltose). Even higher chlorination was observed when nitrogen and water were added in combination with labile organic matter. The effect that more labile organic matter strongly stimulated the chlorination rates was confirmed by the second separate experiment. These results indicate that chlorination was not primarily a way to cut refractory organic matter into digestible molecules, representing one previous hypothesis, but is related with microbial metabolism in other ways that will be further discussed in our presentation.

  15. Chemodestructive fractionation of soil organic matter

    NASA Astrophysics Data System (ADS)

    Popov, A. I.; Rusakov, A. V.

    2016-06-01

    The method of chemodestructive fractionation is suggested to assess the composition of soil organic matter. This method is based on determination of the resilience of soil organic matter components and/or different parts of organic compounds to the impact of oxidizing agents. For this purpose, a series of solutions with similar concentration of the oxidant (K2Cr2O7), but with linearly increasing oxidative capacity was prepared. Chemodestructive fractionation showed that the portion of easily oxidizable (labile) organic matter in humus horizons of different soil types depends on the conditions of soil formation. It was maximal in hydromorphic soils of the taiga zone and minimal in automorphic soils of the dry steppe zone. The portion of easily oxidizable organic matter in arable soils increased with an increase in the rate of organic fertilizers application. The long-lasting agricultural use of soils and burying of the humus horizons within the upper one-meter layer resulted in the decreasing content of easily oxidizable organic matter. It was found that the portion of easily oxidizable organic matter decreases by the mid-summer or fall in comparison with the spring or early summer period.

  16. ENVIRONMENTAL PHOTOPROCESSES INVOLVING NATURAL ORGANIC MATTER

    EPA Science Inventory

    Current research is reviewed on the photoreactions that occur when sunlight interacts with soil and aquatic organic matter. The primary focus is on photoprocesses involving humic substances. Investigations of the direct photoreactions of humic substances are discussed, with empha...

  17. Limitations on lowstand meteoric diagenesis in the Pliocene-Pleistocene of Florida and Great Bahama Bank: Implications for eustatic sea-level models

    SciTech Connect

    Melim, L.A.

    1996-10-01

    Data from three Bahamian and South Floridan cores with deeper water facies show that, contrary to current models, there is no phreatic meteoric diagenesis that can be attributed to large-scale sea-level lowstands. Models of meteoric diagenesis in carbonate sediments commonly assume major phreatic alteration during glacio-eustatic sea-level lowstands. However, the diagenesis previously attributed to large-scale (> 80 m) lowstands is found in shallow-water facies that have been repetitively exposed. In order to document diagenesis from large-scale lowstands, an interval is needed that was deposited in deeper water and not immediately exposed to meteoric fluids. Three cores with such deeper-water facies indicate that the majority of phreatic meteoric diagenesis in Florida and the Bahamas happened during glacio-eustatic highstands, not during lowstands. The data also suggest that diagenetically active meteoric lenses in Florida and the Bahamas are restricted to within 60 m, and perhaps less, of the land surface. The most likely reasons deeper lenses are chemically inactive are (1) the greater percolation distance allows the water to reach saturation prior to entering the lens, and (2) the large distance exceeds the reach of soil-derived organic matter, known to drive diagenesis in meteorite lenses. Models that currently assume a constant rate for alteration in meteoric fluids need to accommodate this variation with thickness of the vadose zone. 29 refs., 5 figs.

  18. Early diagenesis and nutrient benthic fluxes in the Adriatic Sea

    NASA Astrophysics Data System (ADS)

    Spagnoli, F.; Frascari, F.; Marcaccio, M.; Bergamin, M. C.

    2003-04-01

    Early diagenesis processes and dissolved nutrient benthic fluxes of Northern and Central Adriatic Sea bottom sediments were investigate in order to know different sedimentary environmental settings. The study was carried out in 12 stations by means of an integrated analysis of pore water and solid phase composition. In each station one core, about one meter long, was collected. In the solid phase the following parameters were determined: grain size, mineralogy, Fe, Mn, Ca, Mg, Al, S, organic carbon, total nitrogen, total P. In pore waters nitrate, nitrite, ammonia, phosphate, alkalinity, sulphate, Fe, Mn and silica were analysed. Benthic fluxes were measured in situ, by benthic chamber, and calculated by modelisation of pore waters. In each station also the chemical-physical parameters of water column were measured. The area North of the Po River is characterised mainly by carbonate sediments, by low phosphate fluxes towards water column, in some cases even negative, due to authigenic apatite precipitation and by low ammonia fluxes for low reactive organic matter inputs. Near Tagliamento and Adige-Brenta river mouths sediments are higher in organic matter contents in comparison with offshore areas. In these environments pore water nutrient regeneration takes place in the uppermost centimetres of sediment by oxic and suboxic organic matter degradation (Adige-Brenta prodelta sediments) or at higher depth by organic matter degradation, mainly anoxic, via sulphate reduction (Tagliamento prodelta area). Fluxes of phosphate and TCO2 in these two areas are slowly higher than other North Po River areas. The Po River proximal prodelta area is characterised by high ammonia, phosphate and TCO2 fluxes due to high organic matter and silicate inputs, degrading mainly in anoxic conditions by sulphate reduction. When bottom water column reach anoxic conditions in these areas also Fe, Mn and phosphate fluxes increase for dissolution of Fe and Mn oxi-hydroxide surface layer. South

  19. Ionic Liquid Extractions of Soil Organic Matter

    NASA Astrophysics Data System (ADS)

    Patti, Antonio; Macfarlane, Douglas; Clarke, Michael

    2010-05-01

    A large range of ionic liquids with the ability to dissolve different classes of natural biopolymers (e.g. cellulose, lignin, protein) have been reported in the literature. These have the potential to isolate different fractions of soil organic matter, thus yielding novel information that is not available through other extraction procedures. The ionic liquids dimethylammonium dimethylcarbamate (DIMCARB), alkylbenzenesulfonate and 1-butyl-3methylimidazolium chloride (Bmim Cl) can solubilise selected components of soil organic matter. Soil extractions with these materials showed that the organic matter recovered showed chemical properties that were consistent with humic substances. These extracts had a slightly different organic composition than the humic acids extracted using the traditional International Humic Substances Society (IHSS) method. The ionic liquids also solubilised some inorganic matter from the soil. Humic acids recovered with alkali were also partially soluble in the ionic liquids. DIMCARB appeared to chemically interfere with organic extract, increasing the level of nitrogen in the sample. It was concluded that the ionic liquid Bmim Cl may function as a useful solvent for SOM, and may be used to recover organic matter of a different character to that obtained with alkali

  20. Humic acids contribution to sedimentary organic matter on a shallow continental shelf (northern Adriatic Sea)

    NASA Astrophysics Data System (ADS)

    Giani, M.; Rampazzo, F.; Berto, D.

    2010-12-01

    The shallow northern Adriatic Sea receives large river runoff, predominantly from the Po River, which is the main allochthonous source of nutrients and organic matter. The origin and quality of organic matter deposited in the sediments can influence the degradation processes and oxygen consumption in the bottom waters as well as the fate of many pollutants. Therefore the humic acids (HA) were quantified in surface and sub-surface sediments collected in an area of the north-western Adriatic platform south of Po River. HA showed to have a relevant contribution to sedimentary organic matter. HA content in sediments were positively correlated with the organic carbon concentration and negatively with redox potential and pH, particularly in sub-surface reduced sediments, suggesting their important role in the diagenetic processes taking place in anoxic conditions. Elemental composition of HA extracted from surface and sub-surface sediments showed a wide range of variation of the C org/N ratios which could be due to a mixed (terrestrial and marine) origin and/or an elevated bacteria degradation of nitrogen during diagenesis processes in sediments. The spectroscopic ratios A 2/A 4 and A 4/A 6 of HA confirmed a mixed origin with a high degree of condensation of the HA extracted from sediments.

  1. Organic Matter Loading Affects Lodgepole Pine Seedling Growth

    NASA Astrophysics Data System (ADS)

    Wei, Xiaohua; Li, Qinglin; Waterhouse, M. J.; Armleder, H. M.

    2012-06-01

    Organic matter plays important roles in returning nutrients to the soil, maintaining forest productivity and creating habitats in forest ecosystems. Forest biomass is in increasing demand for energy production, and organic matter has been considered as a potential supply. Thus, an important management question is how much organic matter should be retained after forest harvesting to maintain forest productivity. To address this question, an experimental trial was established in 1996 to evaluate the responses of lodgepole pine seedling growth to organic matter loading treatments. Four organic matter loading treatments were randomly assigned to each of four homogeneous pine sites: removal of all organic matter on the forest floor, organic matter loading quantity similar to whole-tree-harvesting residuals left on site, organic matter loading quantity similar to stem-only-harvesting residuals, and organic matter loading quantity more similar to what would be found in disease- or insect-killed stands. Our 10-year data showed that height and diameter had 29 and 35 % increase, respectively, comparing the treatment with the most organic matter loading to the treatment with the least organic matter loading. The positive response of seedling growth to organic matter loading may be associated with nutrients and/or microclimate change caused by organic matter, and requires further study. The dynamic response of seedling growth to organic matter loading treatments highlights the importance of long-term studies. Implications of those results on organic matter management are discussed in the context of forest productivity sustainability.

  2. Correlation of soil and sediment organic matter polarity to aqueous sorption of nonionic compounds

    USGS Publications Warehouse

    Kile, D.E.; Wershaw, R. L.; Chiou, C.T.

    1999-01-01

    Polarities of the soiL/sediment organic matter (SOM) in 19 soil and 9 freshwater sediment sam pies were determined from solid-state 13C-CP/MAS NMR spectra and compared with published partition coefficients (K(oc)) of carbon tetrachloride (CT) from aqueous solution. Nondestructive analysis of whole samples by solid-state NMR permits a direct assessment of the polarity of SOM that is not possible by elemental analysis. The percent of organic carbon associated with polar functional groups was estimated from the combined fraction of carbohydrate and carboxylamide-ester carbons. A plot of the measured partition coefficients (K(oc)) of carbon tetrachloride (CT) vs. percent polar organic carbon (POC) shows distinctly different populations of soils and sediments as well as a roughly inverse trend among the soil/sediment populations. Plots of K(oc) values for CT against other structural group carbon fractions did not yield distinct populations. The results indicate that the polarity of SOM is a significant factor in accounting for differences in K(oc) between the organic matter in soils and sediments. The alternate direct correlation of the sum of aliphatic and aromatic structural carbons with K(oc) illustrates the influence of nonpolar hydrocarbon on solute partition interaction. Additional elemental analysis data of selected samples further substantiate the effect of the organic matter polarity on the partition efficiency of nonpolar solutes. The separation between soil and sediment samples based on percent POC reflects definite differences of the properties of soil and sediment organic matters that are attributable to diagenesis.Polarities of the soil/sediment organic matter (SOM) in 19 soil and 9 freshwater sediment samples were determined from solid-state 13C-CP/MAS NMR spectra and compared with published partition coefficients (Koc) of carbon tetrachloride (CT) from aqueous solution. Nondestructive analysis of whole samples by solid-state NMR permits a direct

  3. HEALTH ASSESSMENT DOCUMENT FOR POLYCYCLIC ORGANIC MATTER

    EPA Science Inventory

    The document responds to Section 122 of the Clean Air Act as Amended August 1977, which requires the Administrator to decide whether atmospheric emissions of polycyclic organic matter (POM) potentially endanger public health. This document reviews POM data on chemical and physica...

  4. Carbonate diagenesis and porosity

    SciTech Connect

    Moore, C.H. )

    1989-01-01

    Carbonate diagenesis is a subject of enormous complexity because of the basic chemical reactivity of carbonate minerals. These carbonate minerals react quickly with natural waters that either dissolve the carbonates, or precipitate new carbonates to bring the water into equilibrium with the host carbonate sediments and rocks. These rock-water interactions either create porosity by dissolution, or destroy porosity by the precipitation of carbonate cements into pore spaces. This book examines these relationships in detail.

  5. Organic matter of urban soils: A review

    NASA Astrophysics Data System (ADS)

    Vodyanitskii, Yu. N.

    2015-08-01

    Urban environment exerts an ambiguous effect on the organic pool of soils; it may decrease (as compared to the background values) in some parts of a city and increase in other parts. The organic matter accumulation in urban soils is promoted by the input of aerial organic pollutants; slowed down mineralization of plant residues under the influence of contamination; and increased productivity of the plants owing to elevated temperatures, high content of carbon dioxide in the air, and maintenance of green zones (sodding of vast areas in cities, application of peat, irrigation and drainage of soils.)

  6. Ocean metabolism and dissolved organic matter: How do small dissolved molecules persist in the ocean?

    NASA Astrophysics Data System (ADS)

    Benner, Ronald

    2010-05-01

    The ocean reservoir of dissolved organic matter (DOM) is among the largest global reservoirs (~700 Pg C) of reactive organic carbon. Marine primary production (~50 Pg C/yr) by photosynthetic microalgae and cyanobacteria is the major source of organic matter to the ocean and the principal substrate supporting marine food webs. The direct release of DOM from phytoplankton and other organisms as well as a variety of other processes, such as predation and viral lysis, contribute to the ocean DOM reservoir. Continental runoff and atmospheric deposition are relatively minor sources of DOM to the ocean, but some components of this material appear to be resistant to decomposition and to have a long residence time in the ocean. Concentrations of DOM are highest in surface waters and decrease with depth, a pattern that reflects the sources and diagenesis of DOM in the upper ocean. Most (70-80%) marine DOM exists as small molecules of low molecular weight (<1 kDalton). Surprisingly, high-molecular-weight (>1 kDalton) DOM is relatively enriched in major biochemicals, such as combined neutral sugars and amino acids, and is more bioavailable than low-molecular-weight DOM. The observed relationships among the size, composition, and reactivity of DOM have led to the size-reactivity continuum model, which postulates that diagenetic processes lead to the production of smaller molecules that are structurally altered and resistant to microbial degradation. The radiocarbon content of these small dissolved molecules also indicates these are the most highly aged components of DOM. Chemical signatures of bacteria are abundant in DOM and increase during diagenesis, indicating bacteria are an important source of slowly cycling biochemicals. Recent analyses of DOM isolates by ultrahigh-resolution mass spectrometry have revealed an incredibly diverse mixture of molecules. Carboxyl-rich alicyclic molecules are abundant in DOM, and they appear to be derived from diagenetically

  7. Organic matters: investigating the sources, transport, and fate of organic matter in Fanno Creek, Oregon

    USGS Publications Warehouse

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

    2015-01-01

    The U.S. Geological Survey (USGS), in cooperation with Clean Water Services, recently completed an investigation into the sources, transport, and fate of organic matter in the Fanno Creek watershed. The information provided by this investigation will help resource managers to implement strategies aimed at decreasing the excess supply of organic matter that contributes to low dissolved-oxygen levels in Fanno Creek and downstream in the Tualatin River during summer. This fact sheet summarizes the findings of the investigation.

  8. Organic matter and sandstone-type uranium deposits: a primer

    USGS Publications Warehouse

    Leventhal, Joel S.

    1979-01-01

    Organic material is intimately associated with sandstone-type uranium deposits in the western United States.. This report gives details of the types of organic matter and their possible role in producing a uranium deposit. These steps include mobilization of uranium from igneous rocks, transportation from the surface, concentration by organic matter, reduction by organic matter, and preservation of the uranium deposit.

  9. Structurally controlled fluid flow and diagenesis along the Moab fault, SE Utah: Organic-inorganic interactions and their effects on fault cementation

    NASA Astrophysics Data System (ADS)

    Eichhubl, P.; Davatzes, N. C.; Aydin, A.

    2002-12-01

    The hydraulic properties of faults in clastic sedimentary sequences are traditionally considered a function of stratigraphic juxtaposition and fault rock composition. Diagenetic effects, in particular organic-inorganic interactions, and their spatial association with the fault architecture, are only rudimentarily explored. Here, we mapped the type and extent of diagenetic alteration along the Moab fault to assess the interrelationships among fault architecture, fault hydraulic properties, and fault rock diagenesis. The Moab fault, a normal fault with up to 1 km of throw and a small strike-slip component, is segmented along strike by branch points and relays. Fault branch points are associated with extensive carbonate cementation of faulted eolian Jurassic sandstone. Within the fault damage zone the abundance of concretions and veins and the diameter of concretions decrease with distance from the fault. Carbonate is spatially associated with bleaching of the reddish hematite-cemented sandstones. Pore and fracture-filling dead oil in bleached and carbonate cemented zones is indicative of bleaching due to reducing aqueous fluids in association with hydrocarbon migration along the fault. Fault-related cementation was potentially controlled by two processes: (1) rapid upward fluid flow along the fault and (2) microbially mediated degradation of hydrocarbons in contact with meteoric water. Evidence for rapid fluid flow is provided by clastic dikes associated with the fault. A drop in CO2 partial pressure during rapidly upward flowing fluid flow would favor carbonate precipitation. Evidence for carbonate precipitation due to hydrocarbon degradation is inferred through the close association of residual oil and calcite or malachite. Release of CO2 by the microbial degradation of oil in the presence of organic acids can increase alkalinity resulting in carbonate precipitation. The involvement of organic acids in fault cementation is suggested by feldspar dissolution and by

  10. Analysis of Organic matter from cloud particles

    NASA Astrophysics Data System (ADS)

    Bank, Shelton; Castillo, Raymond

    1987-03-01

    Organic matter collected from filtration of two separate cloud events was analysed by Fourier Transform Infrared Spectroscopy. Particles collected from different size filters were separated by color and each type of particle gave rise to a characteristic spectrum. The major constituents were identified as complex proteins and cellulose. Additionally, some degraded material (likely protein) and an unidentified orange-brown material were present. Finally some trace components were identified as wax, oil, silicon oil, polyvinyl chloride, calcium carbonate, clay, sand and polyethylene.

  11. Isotopic analysis of cometary organic matter

    NASA Technical Reports Server (NTRS)

    Kerridge, John F.

    1991-01-01

    Carbon isotope ratios have been measured for CN in the coma of Comet Halley and for several CHON particles emitted by Halley. Of these, only the CHON-particle data may be reasonably related to organic matter in the cometary nucleus, but the true range of (C-13)/(C-12) values in those particles is quite uncertain. The D/H ratio in H2O in the Halley coma resembles that in Titan/Uranus.

  12. Organic matter matters for ice nuclei of agricultural soil origin

    NASA Astrophysics Data System (ADS)

    Tobo, Y.; DeMott, P. J.; Hill, T. C. J.; Prenni, A. J.; Swoboda-Colberg, N. G.; Franc, G. D.; Kreidenweis, S. M.

    2014-04-01

    Heterogeneous ice nucleation is a~crucial process for forming ice-containing clouds and subsequent ice-induced precipitation. The importance for ice nucleation of airborne desert soil dusts composed predominantly of minerals is relatively well understood. On the other hand, the potential influence of agricultural soil dusts on ice nucleation has been poorly recognized, despite recent estimates that they may account for up to ∼25% of the global atmospheric dust load. We have conducted freezing experiments with various dusts, including agricultural soil dusts derived from the largest dust source region in North America. Here we show evidence for the significant role of soil organic matter (SOM) in particles acting as ice nuclei (IN) under mixed-phase cloud conditions. We find that the ice nucleating ability of the agricultural soil dusts is similar to that of desert soil dusts, but is reduced to almost the same level as that of clay minerals (e.g., kaolinite) after either H2O2 digestion or dry heating to 300 °C. In addition, based on chemical composition analysis, we show that organic-rich particles are more important than mineral particles for the ice nucleating ability of the agricultural soil dusts at temperatures warmer than about -36 °C. Finally, we suggest that such organic-rich particles of agricultural origin (namely, SOM particles) may contribute significantly to the ubiquity of organic-rich IN in the global atmosphere.

  13. Organic matter matters for ice nuclei of agricultural soil origin

    NASA Astrophysics Data System (ADS)

    Tobo, Y.; DeMott, P. J.; Hill, T. C. J.; Prenni, A. J.; Swoboda-Colberg, N. G.; Franc, G. D.; Kreidenweis, S. M.

    2014-08-01

    Heterogeneous ice nucleation is a crucial process for forming ice-containing clouds and subsequent ice-induced precipitation. The importance for ice nucleation by airborne desert soil dusts composed predominantly of minerals is widely acknowledged. However, the potential influence of agricultural soil dusts on ice nucleation has been poorly recognized, despite recent estimates that they may account for up to 20-25% of the global atmospheric dust load. We have conducted freezing experiments with various dusts, including agricultural soil dusts derived from the largest dust-source region in North America. Here we show evidence for the significant role of soil organic matter (SOM) in particles acting as ice nuclei (IN) under mixed-phase cloud conditions. We find that the ice-nucleating ability of the agricultural soil dusts is similar to that of desert soil dusts, but is clearly reduced after either H2O2 digestion or dry heating to 300 °C. In addition, based on chemical composition analysis, we demonstrate that organic-rich particles are more important than mineral particles for the ice-nucleating ability of the agricultural soil dusts at temperatures warmer than about -36 °C. Finally, we suggest that such organic-rich particles of agricultural origin (namely, SOM particles) may contribute significantly to the ubiquity of organic-rich IN in the global atmosphere.

  14. Isolation and chemical characterization of dissolved and colloidal organic matter

    USGS Publications Warehouse

    Aiken, G.; Leenheer, J.

    1993-01-01

    Commonly used techniques for the concentration and isolation of organic matter from water, such as preparative chromatography, ultrafiltration and reverse osmosis, and the methods used to analyze the organic matter obtained by these methods are reviewed. The development of methods to obtain organic matter that is associated with fractions of the dissolved organic carbon other than humic substances, such as organic bases, hydrophilic organic acids and colloidal organic matter are discussed. Methods specifically used to study dissolved organic nitrogen and dissolved organic phosphorous are also discussed. -from Authors

  15. Reactive-transport modeling of iron diagenesis and associated organic carbon remineralization in a Florida (USA) subterranean estuary

    USGS Publications Warehouse

    Roy, Moutusi; Martin, Jonathan B.; Smith, Christopher G.; Cable, Jaye E.

    2011-01-01

    Iron oxides are important terminal electron acceptors for organic carbon (OC) remineralization in subterranean estuaries, particularly where oxygen and nitrate concentrations are low. In Indian River Lagoon, Florida, USA, terrestrial Fe-oxides dissolve at the seaward edge of the seepage face and flow upward into overlying marine sediments where they precipitate as Fe-sulfides. The dissolved Fe concentrations vary by over three orders of magnitude, but Fe-oxide dissolution rates are similar across the 25-m wide seepage face, averaging around 0.21 mg/cm2/yr. The constant dissolution rate, but differing concentrations, indicate Fe dissolution is controlled by a combination of increasing lability of dissolved organic carbon (DOC) and slower porewater flow velocities with distance offshore. In contrast, the average rate constants of Fe-sulfide precipitation decrease from 21.9 × 10-8 s-1 to 0.64 × 10-8 s-1 from the shoreline to the seaward edge of the seepage face as more oxygenated surface water circulates through the sediment. The amount of OC remineralized by Fe-oxides varies little across the seepage face, averaging 5.34 × 10-2 mg/cm2/yr. These rates suggest about 3.4 kg of marine DOC was remineralized in a 1-m wide, shore-perpendicular strip of the seepage face as the terrestrial sediments were transgressed over the past 280 years. During this time, about 10 times more marine solid organic carbon (SOC) accumulated in marine sediments than were removed from the underlying terrestrial sediments. Indian River Lagoon thus appears to be a net sink for marine OC.

  16. Reactivity of recently deposited organic matter: Degradation of lipid compounds near the sediment-water interface

    NASA Astrophysics Data System (ADS)

    Canuel, Elizabeth A.; Martens, Christopher S.

    1996-05-01

    The usefulness of biomarker compounds buried in marine sediments depends upon a quantita tive understanding of the effects of early diagenesis on their distribution. To address this, a new experimental approach was utilized to determine rates of degradation in a coastal sediment. Rates of degradation for solvent-extractable lipid components were quantified in four sediment horizons composed of newly accumulated organic matter (31-144 days since deposition). Sediment accumulation rate data derived from changes in the inventory of Be-7 ( t 1/2 = 53.3 days) were combined with concentration data for lipid biomarker compounds, enabling us to evaluate the reactivity of organic matter in the upper 8 cm of the rapidly accumulating sediments of Cape Lookout Bight, North Carolina, USA (CLB). Net rates of loss and rate constants were calculated for individual compounds belonging to three classes of lipids: fatty acids, sterols, and n-alkanes. Individual components showed a range in reactivity, in some cases (fatty acids), attributable to differences in their biological sources. Rates and rate constants were consistently highest in the surficial sediments (0-2.5 cm), indicating that the reactivity of a given molecule(s) decreases over time, and beginning soon after deposition. Comparison with apparent rate constants ( k') calculated over longer timescales (one and ten years) shows that steady-state diagenetic models underestimate rates of degradation at or near the sediment-water interface by an order of magnitude.

  17. Abiotic Bromination of Soil Organic Matter.

    PubMed

    Leri, Alessandra C; Ravel, Bruce

    2015-11-17

    Biogeochemical transformations of plant-derived soil organic matter (SOM) involve complex abiotic and microbially mediated reactions. One such reaction is halogenation, which occurs naturally in the soil environment and has been associated with enzymatic activity of decomposer organisms. Building on a recent finding that naturally produced organobromine is ubiquitous in SOM, we hypothesized that inorganic bromide could be subject to abiotic oxidations resulting in bromination of SOM. Through lab-based degradation treatments of plant material and soil humus, we have shown that abiotic bromination of particulate organic matter occurs in the presence of a range of inorganic oxidants, including hydrogen peroxide and assorted forms of ferric iron, producing both aliphatic and aromatic forms of organobromine. Bromination of oak and pine litter is limited primarily by bromide concentration. Fresh plant material is more susceptible to bromination than decayed litter and soil humus, due to a labile pool of mainly aliphatic compounds that break down during early stages of SOM formation. As the first evidence of abiotic bromination of particulate SOM, this study identifies a mechanistic source of the natural organobromine in humic substances and the soil organic horizon. Formation of organobromine through oxidative treatments of plant material also provides insights into the relative stability of aromatic and aliphatic components of SOM. PMID:26468620

  18. Soil organic matter composition affected by potato cropping managements

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Organic matter is a small but important soil component. As a heterogeneous mixture of geomolecules and biomolecules, soil organic matter (SOM) can be fractionated into distinct pools with different solubility and lability. Water extractable organic matter (WEOM) fraction is the most labile and mobil...

  19. Glacioeustasy, meteoric diagenesis, and the carbon cycle during the Middle Carboniferous

    NASA Astrophysics Data System (ADS)

    Dyer, Blake; Maloof, Adam C.; Higgins, John A.

    2015-10-01

    Middle Carboniferous carbonates in the western U.S. have undergone Pleistocene Bahamas-style meteoric diagenesis that may be associated with expanding late Paleozoic ice sheets. Fourteen stratigraphic sections from carbonate platforms illustrate the regional distribution and variable intensity of physical and chemical diagenesis just below the Middle Carboniferous unconformity. These sections contain top-negative carbon isotope excursions that terminate in regional exposure surfaces that are associated with some combination of karst towers, desiccation cracks, fabric destructive recrystallization, or extensive root systems. The timing of the diagenesis is synchronous with similarly scaled top-negative carbon isotope excursions observed by others in England, Kazakhstan, and China. The mass flux of negative carbon required to generate similar isotopic profiles across the areal extent of Middle Carboniferous platform carbonates is a significant component of the global carbon cycle. We present a simple carbon box model to illustrate that the δ13C of dissolved inorganic carbon in the ocean could be elevated by ˜1.4‰ as isotopically light carbon from the weathering of terrestrial organic matter reacts with exposed platforms before reaching the ocean and atmosphere. These results represent an improvement on global biogeochemical models that have struggled to provide a congruent solution to the high δ13C of the late Paleozoic icehouse.

  20. Organic Matter: Productivity, accumulation, and preservation in recent and ancient sediments

    SciTech Connect

    Whelan, J.; Farrington, J.W.

    1992-01-01

    The 22 chapters of the volume are divided into four basic sections: Preliminaries (3 chapters); Recent Sediments and Depositional Environments (7 chapters); Transitions (7 chapters); and Ancient Sediments (5 chapters). The Preliminaries section has a great historical vignette of John Hunt presented by Wally Dow and a paper by Hunt himself on simple graphical procedures for estimating, quickly, rough measures of organic maturity in sedimentary basins. The theme of the papers in the Recent Sediments section is concerned with preservation of organic matter and the relation of that preservation to anoxic conditions, and the controls on spatial and temporal variations of anoxia. Each paper not only provides background geologic conditions appropriate to the investigation undertaken, but also has copious data from case studies to buttress the basic geochemical factors being addressed. The examples used are world-wide so that a variety of processes are examined. In the Transition section, the theme of the potpourri of papers is concerned with attempts to use recorders of organic matter alteration (biomarkers, bitumens, stable carbon isotope changes) in connection with early-stage diagenesis and catagenesis data in order to link those recorders to more direct measures of alteration. The general idea being, presumably, to provide a smooth transition from direct statements of alteration to the indirect inferences that have to be made in Ancient Sediments. The Ancient Sediments section looks more to the hydrocarbons, their compounds, and direct aliphatic/aromatic signatures to identify sources, generation timing, facies control, and depositional environment changes impacting hydrocarbon measures of organic matter maturation.

  1. Soil organic matter prediction using environmental factors

    NASA Astrophysics Data System (ADS)

    Oueslati, I.; Allamano, P.; Claps, P.; Bonifacio, E.

    2009-04-01

    Organic matter is one of the most important properties affecting soil chemical and physical fertility, but it influences also soil hydrologic parameters. It is easily measured by chemical analyses, but in large scale studies its prediction is desirable. This study aims at predicting the spatial distribution of the soil organic matter concentration (SOM) in forest topsoils in Piedmont (North West Italy) using continuous predictors (in forms of auxiliary maps). As predictors we selected: the digital elevation model (DEM, 50 meter resolution), the mean annual precipitation, the soil dryness index and normal difference vegetation index (NDVI, 1 km resolution). Using the Geographic Information System SAGA, the terrain attributes were computed from the DEM, namely are: elevation, slope, aspect and mean curvature associated with hydrological parameters namely, the compound topographic index (CTI) and stream power index (SPI). From the long term monthly average of NDVI the mean annual value and the coefficient of variation (CV) were also derived. This data set was used to estimate the SOM concentration by regression analysis. To test the relationship between the SOM and the environmental variables, 66 soil profiles were used. Several variables were found to be significantly correlated with SOM concentration: elevation, slope, mean NDVI, CV(NDVI), precipitation and dryness index, with correlation coefficients, r, of the linear regressions ranging from 0.12 to 0.63. However, only precipitation and mean NDVI were retained when a stepwise multiple regression was used. Although these two predictors contribute only partially to explain SOM variability (R2=0.42). The importance of vegetation is clearly depicted by the significant effect of NDVI, while the precipitation may contribute to the explanation in a less direct way because of the complex links between climate and organic matter transformation in soils.

  2. A comprehensive survey of lignin geochemistry in the sedimentary organic matter along the Kapuas River (West Kalimantan, Indonesia)

    NASA Astrophysics Data System (ADS)

    Loh, Pei Sun; Chen, Chen-Tung Arthur; Anshari, Gusti Z.; Wang, Jough-Tai; Lou, Jiann-Yuh; Wang, Shu-Lun

    2012-01-01

    In this first study of lignin geochemistry in the world's longest river on an island, surface sediments were collected along the Kapuas River, three lakes in the upper river, a tributary in the lower river and a separate river during June-July 2007 and December 2007-January 2008. The samples were analyzed for lignin-derived phenols and bulk elemental and stable carbon isotope compositions. Λ values (the sum of eight lignin phenols, expressed as mg/100 mg organic carbon (OC)) ranged from 0.13 to 3.70. Ratios of syringyl/vanillyl (S/V) and cinnamyl/vanillyl (C/V) ranged from 0.34 to 1.18 and 0.28 to 1.40, respectively, indicating the presence of non-woody angiosperm tissues. The high vanillic acid to vanillin (Ad/Al)v (0.71-2.01) and syringic acid to syringaldehyde (Ad/Al)s (0.72-2.12) ratios indicate highly degraded lignin materials. In the upper Kapuas River, highly degraded soil materials discharged from lands that were barren as a result of deforestation activities were detected in the locations directly in those vicinities. The middle Kapuas River showed rapid organic matter degradation, probably due to the presence of fresh terrestrial and phytoplankton organic matter fueling the biogeochemical cycling. The Kapuas Kecil River, one of the two branches in the lower reach of the Kapuas River, showed higher levels and diagenesis of sedimentary organic matter due to input from anthropogenic sources and increased marine organic matter near the mouth. This study shows that different stretches along the river exhibit different levels and composition of sedimentary organic matter, as well as different carbon dynamics, which is directly attributable to the varying landscapes and quality of organic matter.

  3. The fate of airborne polycyclic organic matter.

    PubMed Central

    Nielsen, T; Ramdahl, T; Bjørseth, A

    1983-01-01

    Biological tests have shown that a significant part of the mutagenicity of organic extracts of collected airborne particulate matter is not due to polycyclic aromatic hydrocarbons (PAH). It is possible that part of these unknown compounds are transformation products of PAH. This survey focuses on the reaction of PAH in the atmosphere with other copollutants, such as nitrogen oxides, sulfur oxides, ozone and free radicals and their reaction products. Photochemically induced reactions of PAH are also included. The reactivity of particle-associated PAH is discussed in relation to the chemical composition and the physical properties of the carrier. Recommendations for future work are given. PMID:6825615

  4. Mapping Soil Organic Matter with Hyperspectral Imaging

    NASA Astrophysics Data System (ADS)

    Moni, Christophe; Burud, Ingunn; Flø, Andreas; Rasse, Daniel

    2014-05-01

    Soil organic matter (SOM) plays a central role for both food security and the global environment. Soil organic matter is the 'glue' that binds soil particles together, leading to positive effects on soil water and nutrient availability for plant growth and helping to counteract the effects of erosion, runoff, compaction and crusting. Hyperspectral measurements of samples of soil profiles have been conducted with the aim of mapping soil organic matter on a macroscopic scale (millimeters and centimeters). Two soil profiles have been selected from the same experimental site, one from a plot amended with biochar and another one from a control plot, with the specific objective to quantify and map the distribution of biochar in the amended profile. The soil profiles were of size (30 x 10 x 10) cm3 and were scanned with two pushbroomtype hyperspectral cameras, one which is sensitive in the visible wavelength region (400 - 1000 nm) and one in the near infrared region (1000 - 2500 nm). The images from the two detectors were merged together into one full dataset covering the whole wavelength region. Layers of 15 mm were removed from the 10 cm high sample such that a total of 7 hyperspectral images were obtained from the samples. Each layer was analyzed with multivariate statistical techniques in order to map the different components in the soil profile. Moreover, a 3-dimensional visalization of the components through the depth of the sample was also obtained by combining the hyperspectral images from all the layers. Mid-infrared spectroscopy of selected samples of the measured soil profiles was conducted in order to correlate the chemical constituents with the hyperspectral results. The results show that hyperspectral imaging is a fast, non-destructive technique, well suited to characterize soil profiles on a macroscopic scale and hence to map elements and different organic matter quality present in a complete pedon. As such, we were able to map and quantify biochar in our

  5. Organic Matter in the Outer Solar System

    NASA Technical Reports Server (NTRS)

    Cruiskshank, Dale P.; DeVincenzi, Donald L. (Technical Monitor)

    2000-01-01

    Many solid bodies in the outer Solar System are covered with ices of various compositions, including water, carbon dioxide, methane, nitrogen, and other molecules that are solid at the low temperatures that prevail there. These ices have all been detected by remote sensing observations made with telescopes on Earth, or more recently, spacecraft in orbit (notably Galileo at Jupiter). The data also reveal other solid materials that could be minerals or complex carbon-bearing organic molecules. A study in progress using large ground-based telescopes to acquire infrared spectroscopic data, and laboratory results on the optical properties of complex organic matter, seeks to identify the non-icy materials on several satellites of Saturn, Uranus, and Neptune. The work on the satellites of Saturn is in part preparatory to the Cassini spacecraft investigation of the Saturn system, which will begin in 2004 and extend for four years.

  6. Isotopic compositions of carbonates and organic carbon from upper Proterozoic successions in Namibia: stratigraphic variation and the effects of diagenesis and metamorphism

    NASA Technical Reports Server (NTRS)

    Kaufman, A. J.; Hayes, J. M.; Knoll, A. H.; Germs, G. J.

    1991-01-01

    The carbon isotope geochemistry of carbonates and organic carbon in the late Proterozoic Damara Supergroup of Namibia, including the Nama, Witvlei, and Gariep groups on the Kalahari Craton and the Mulden and Otavi groups on the Congo Craton, has been investigated as an extension of previous studies of secular variations in the isotopic composition of late Proterozoic seawater. Subsamples of microspar and dolomicrospar were determined, through petrographic and cathodoluminescence examination, to represent the "least-altered" portions of the rock. Carbon-isotopic abundances in these phases are nearly equal to those in total carbonate, suggesting that 13C abundances of late Proterozoic fine-grained carbonates have not been significantly altered by meteoric diagenesis, although 18O abundances often differ significantly. Reduced and variable carbon-isotopic differences between carbonates and organic carbon in these sediments indicate that isotopic compositions of organic carbon have been altered significantly by thermal and deformational processes, likely associated with the Pan-African Orogeny. Distinctive stratigraphic patterns of secular variation, similar to those noted in other, widely separated late Proterozoic basins, are found in carbon-isotopic compositions of carbonates from the Nama and Otavi groups. For example, in Nama Group carbonates delta 13C values rise dramatically from -4 to +5% within a short stratigraphic interval. This excursion suggests correlation with similar excursions noted in Ediacaran-aged successions of Siberia, India, and China. Enrichment of 13C (delta 13C> +5%) in Otavi Group carbonates reflects those in Upper Riphean successions of the Akademikerbreen Group, Svalbard, its correlatives in East Greenland, and the Shaler Group, northwest Canada. The widespread distribution of successions with comparable isotopic signatures supports hypotheses that variations in delta 13C reflect global changes in the isotopic composition of late

  7. Isotopic compositions of carbonates and organic carbon from upper Proterozoic successions in Namibia: stratigraphic variation and the effects of diagenesis and metamorphism.

    PubMed

    Kaufman, A J; Hayes, J M; Knoll, A H; Germs, G J

    1991-01-01

    The carbon isotope geochemistry of carbonates and organic carbon in the late Proterozoic Damara Supergroup of Namibia, including the Nama, Witvlei, and Gariep groups on the Kalahari Craton and the Mulden and Otavi groups on the Congo Craton, has been investigated as an extension of previous studies of secular variations in the isotopic composition of late Proterozoic seawater. Subsamples of microspar and dolomicrospar were determined, through petrographic and cathodoluminescence examination, to represent the "least-altered" portions of the rock. Carbon-isotopic abundances in these phases are nearly equal to those in total carbonate, suggesting that 13C abundances of late Proterozoic fine-grained carbonates have not been significantly altered by meteoric diagenesis, although 18O abundances often differ significantly. Reduced and variable carbon-isotopic differences between carbonates and organic carbon in these sediments indicate that isotopic compositions of organic carbon have been altered significantly by thermal and deformational processes, likely associated with the Pan-African Orogeny. Distinctive stratigraphic patterns of secular variation, similar to those noted in other, widely separated late Proterozoic basins, are found in carbon-isotopic compositions of carbonates from the Nama and Otavi groups. For example, in Nama Group carbonates delta 13C values rise dramatically from -4 to +5% within a short stratigraphic interval. This excursion suggests correlation with similar excursions noted in Ediacaran-aged successions of Siberia, India, and China. Enrichment of 13C (delta 13C> +5%) in Otavi Group carbonates reflects those in Upper Riphean successions of the Akademikerbreen Group, Svalbard, its correlatives in East Greenland, and the Shaler Group, northwest Canada. The widespread distribution of successions with comparable isotopic signatures supports hypotheses that variations in delta 13C reflect global changes in the isotopic composition of late

  8. Soil organic matter mineralization in frozen soils

    NASA Astrophysics Data System (ADS)

    Harrysson Drotz, S.; Sparrman, T.; Schleucher, J.; Nilsson, M.; Öquist, M. G.

    2009-12-01

    Boreal forest soils are frozen for a large part of the year and soil organic matter mineralization during this period has been shown to significantly influence the C balance of boreal forest ecosystems. Mineralization proceeds through heterotrophic microbial activity, but the understanding of the environmental controls regulating soil organic matter mineralization under frozen conditions is poor. Through a series of investigations we have addressed this issue in order to elucidate to what extent a range of environmental factors control mineralization processes in frozen soils and also the microbial communities potential to oxidize organic substrates and grow under such conditions. The unfrozen water content in the frozen soils was shown to be an integral control on the temperature response of biogenic CO2 production across the freezing point of bulk soil water. We found that osmotic potential was an important contributor to the total water potential and, hence, the unfrozen water content of frozen soil. From being low and negligible in an unfrozen soil, the osmotic potential was found to contribute up to 70% of the total water potential in frozen soil, greatly influencing the volume of liquid water. The specific factors of how soil organic matter composition affected the unfrozen water content and CO2 production of frozen soil were studied by CP-MAS NMR. We concluded that abundance of aromatics and recalcitrant compounds showed a significant positive correlation with unfrozen water content and these were also the major soil organic fractions that similarly correlated with the microbial CO2 production of the frozen soils. Thus, the hierarchy of environmental factors controlling SOM mineralization changes as soils freeze and environmental controls elucidated from studies of unfrozen systems can not be added on frozen conditions. We have also investigated the potential activity of soil microbial communities under frozen conditions in order to elucidate temperature

  9. Stability of Ferrihydrite and Organic Matter in Ferrihydrite-Organic Matter Associations

    NASA Astrophysics Data System (ADS)

    Eusterhues, K.; Totsche, K. U.

    2015-12-01

    Iron oxides can bind particularly large amounts of organic matter (OM) and seem to be an important control on OM storage in many soils. To better understand the interactions between Fe oxides and OM, we produced ferrihydrite-OM associations by adsorption and coprecipitation in laboratory experiments. Because ferrihydrites are often formed in OM-rich solutions, we assume that coprecipitation is a common process in nature. In contrast to adsorption on pre-existing ferrihydrite surfaces, coprecipitation involves adsorption, occlusion (physical entrapment of OM), formation of Fe-OM complexes, and poisoning of ferrihydrite growth. The reactivity of coprecipitates may therefore differ from ferriydrites with adsorbed OM. Incubation experiments with an inoculum extracted from a Podzol forest-floor were carried out to quantify the mineralization of the adsorbed and coprecipitated organic matter. These experiments showed that the association with ferrihydrite stabilized the associated organic matter, but that differences in the degradability of adsorbed and coprecipitated organic matter were small. We therefore conclude that coprecipitation does not lead to a significant formation of microbial inaccessible organic matter domains. Microbial reduction experiments were performed using Geobacter bremensis. We observed that increasing amounts of associated OM led to decreasing initial reaction rates and a decreasing degree of dissolution. Reduction of coprecipitated ferrihydrites was faster than reduction of ferrihydrites with adsorbed OM. Our data demonstrate that the association with ferrihydrite can effectively stabilize labile polysaccharides. Vice versa, these polysaccharides may protect ferrihydrite from reduction by Geobacter-like bacteria. However, a challenge for future studies will be to link formation and degradation of mineral-organic associations to natural porous systems, that is, to the complex interplay of mass transport and microbial distribution in the

  10. Spectral fingerprinting of soil organic matter composition

    NASA Astrophysics Data System (ADS)

    Cecillon, L.; Certini, G.; Lange, H.; Forte, C.; Strand, L. T.

    2009-04-01

    The determination of soil organic matter (SOM) composition relies on a variety of chemical and physical methods, most of them time consuming and expensive. Hitherto, such methodological limitations have hampered the use of detailed SOM composition in process-based models of SOM dynamics, which usually include only three poorly defined carbon pools. Here we show a novel approach merging both near and mid infrared spectroscopy into a single fingerprint for an expeditious prediction of the molecular composition of organic materials in soil, as inferred from a molecular mixing model (MMM) based on 13C nuclear magnetic resonance (NMR), which describes SOM as a mixture of common biologically derived polymers. Infrared and solid-state 13C NMR spectroscopic measurements were performed on a set of mineral and organic soil samples presenting a wide range of organic carbon content (2 to 500 g kg-1), collected in a boreal heathland (Storgama, Norway). The implementation of the MMM using 13C NMR spectra allowed the calculation of five main biochemical components (carbohydrate, protein, lignin, lipids and black carbon) for each sample. Partial least squares regression models were developed for the five biopolymers using outer product analysis of near and mid infrared spectra (Infrared-OPA). All models reached ratios of performance to deviation (RPD) above 2 and specific infrared wavenumbers associated to each biochemical component were identified. Our results demonstrate that Infrared-OPA provides a robust and cost-effective fingerprint of SOM composition that could be useful for the routine assessment of soil carbon pools.

  11. The Characteristics of Organic Matter from the Triassic Clays of nw Margin of the Holy Cross Mts (Poland) — Preliminary Report

    NASA Astrophysics Data System (ADS)

    Marynowski, Leszek; Wyszomirski, Piotr; Kurkiewicz, Sławomir

    2006-01-01

    The molecular character of organic matter in Triassic clays on the NW border of the Holy Cross Mts was determined in apolar, aromatic and polar fractions of extractable organic matter (OM) using GC-MS analysis. The contribution of terrestrial higher plants to the kerogene is revealed by the dominant presence of odd long-chain n-alkanes and by the occurrence of retene. Benzophenone, fluorenone, cyclopenta(def)phenanthrenone, antracenone and benzanthrone were among the compounds identified in polar fractions of the soluble organic matter. These commonly originate during strong oxidation of sedimentary organic matter. The aromatic fraction is characterised by the presence of phenyl derivatives (PhPAC) such as phenylnaphthalenes, terphenyls, phenyldibenzofurans and phenylphenanthrenes that are also products of the abiotic oxidation of organic matter. The oxidation processes that occurred during sedimentation and during early diagenesis resulted in a very significant decrease in the organic matter content in the clays. This decrease considerably influences their technological properties.

  12. Relating dissolved organic matter fluorescence to functional properties

    NASA Astrophysics Data System (ADS)

    Tipping, E.; Baker, A.; Thacker, S.; Gondar, D.

    2007-12-01

    The fluorescence excitation emission matrix properties of dissolved organic matter from three rivers and one lake in NW England are analysed. Sites are sampled in duplicate and for some sites seasonally to cover variations in dissolved organic matter composition, river flow, and carbon isotopic (13C, 14C) variability. Results are compared to the functional properties of the dissolved organic matter, the functional assays provide quantitative information on light absorption, fluorescence, photochemical fading, pH buffering, copper binding, benzo[a]pyrene binding, hydrophilicity and adsorption to alumina. Fluorescence characterization of the dissolved organic matter samples demonstrates that peak C fluorescence emission wavelength, the ratio of peak T to peak C fluorescence intensity, and the fluorescence : absorbance ratio best differentiate different dissolved organic matter samples. These parameters correspond to dissolved organic matter aromaticity, the ratio of labile to recalcitrant organic matter, and dissolved organic matter molecular weight. Peak C fluorescence emission wavelength, the ratio of peak T to peak C fluorescence intensity, and the fluorescence : absorbance ratio fluorescence parameters also have strong correlations with several of the functional assays, in particular the extinction coefficients, benzo(a)pyrene binding and alumina adsorption, and buffering capacity. In many cases, regression equations with a correlation coefficient >0.9 are obtained, suggesting that dissolved organic matter functional character can be predicted from DOM fluorescence properties. For one site, the relationship between dissolved organic matter source, fluorescence, function and carbon isotopic composition is discussed.

  13. Diagenesis in halite-cemented source rocks, Middle Devonian, Saskatchewan

    SciTech Connect

    Kendall, A.C. ); Abbott, G.D.; D'Elia, V.A.A. )

    1990-05-01

    Porosity in Dawson Bay carbonates is halite plugged and the formation is sandwiched between thick units of bedded halite. The presence of displacive halite crystals within fine-grained carbonates (implying sediment plasticity during halite emplacement) and uncompacted organic-rich, carbonate-poor stromatolites indicate halite cementation occurred at an early stage. Also, halite cementation must have been completed prior to porosity loss in overlying bedded halites. By comparison with Holocene/Pleistocene bedded halites, this cementation occurred with only tens of meters of overburden. Early complete halite cementation should have converted Dawson Bay carbonates into virtually a closed system and greatly curtailed or inhibited organic-matter maturation within them Organic-rich carbonates occur immediately below Dawson Bay evaporites as rocks containing an anomalously abundant benthos (stromatoporoids, brachiopods) or as a more restricted facies, lacking megafossils or containing gastropods. Some restricted carbonates contain more than 2% extractable organic carbon. The n-alkane, pentacyclic triterpane, nonrearranged sterane and disterane distributions suggest two distinct populations of samples are present. Biomarker distributions are difficult to interpret in terms of estimating organic maturity because of source rock environmental factors (hypersalinity), but appear to be inconsistent with the geological prognosis that these source rocks would have been isolated early in their diagenesis. The problem of how kerogens can be altered in an apparently closed system has yet to be resolved.

  14. Organic biomarkers to describe the major carbon inputs and cycling of organic matter in the central Great Barrier Reef region

    NASA Astrophysics Data System (ADS)

    Burns, Kathryn; Brinkman, Diane

    2011-06-01

    Controversy surrounds the sources and transport of land derived pollutants in the Great Barrier Reef ecosystem because there is insufficient knowledge of the mechanism of movement of organic contaminants and the cycling of organic matter in this dynamic system. Thus a sediment and sediment trap study was used to describe the composition of resuspended and surface sediments in the south central Great Barrier Reef and its lagoon. This region is characterised by strong tides (6-8 m at Mackay) and trade winds regularly about 15-20 knots. A series of organic biomarkers detailed the cyclical processes of sediment resuspension, recolonising with marine algae and bacteria, packaging into zooplankton faecal pellets and resettlement to sediments where the organics undergo further diagenesis. With each cycle the inshore sediments are diluted with CaCO 3 reef sediments and moved further offshore with the strong ebb tide currents. This results in transport of land derived materials offshore and little storage of organic materials in the lagoon or reef sediments. These processes were detailed by inorganic measurements such as %CaCO 3 and Al/Ca ratios, and by the compositions of hydrocarbon, sterol, alcohol, and fatty acid lipid fractions. Persistent contaminants such as coal dust from a coastal loading facility can be detected in high concentration inshore and decreasing out to the shelf break at 180 m approximately 40 nautical miles offshore. The normal processes would likely be amplified during cyclonic and other storms. The lipids show the sources of carbon to include diatoms and other phytoplankton, creanaerchaeota, sulfate reducing and other bacteria, land plants including mangrove leaves, plus coal dust and other petroleum contaminants.

  15. Potential Marine Organisms Affecting Airborne Primary Organic Matter

    NASA Astrophysics Data System (ADS)

    Aller, J. Y.; Alpert, P. A.; Knopf, D. A.

    2012-12-01

    The oceans cover 70% of earth with the marine environment contributing ~50% of the global biomass. Particularly during periods of high biological activity associated with phytoplankton blooms, primary emitted aerosol particles dominated by organic compounds in the submicron size range, are ejected from surface waters increasing in concentration exponentially with overlying wind speeds. This is significant for clouds and climate particularly over nutrient rich polar seas, where seawater concentrations of biogenic particles can reach 109 cells per ml during spring phytoplankton blooms, and even 106 cells per ml in winter when empty frustules and fragments of diatoms are resuspensed from shallow shelf sediments by strong winds, and mix with living pico- and nanoplankton in surface sea waters. This organic aerosol fraction can have a significant impact on the ability of ocean derived aerosol to act as cloud condensation nuclei. It has been shown that small insoluble organic particles are aerosolized from the sea surface microlayer (SML) via bubble bursting. The exact composition and complexity of the SML varies spatially and temporally but includes phytoplankton cells, microorganisms, organic debris, and a complex mixture of proteins, polysaccharides, humic-type material and waxes, microgels and colloidal nanogels, and strong surface active lipids. The specific chemical composition is dependent on the fractionation of organic matter which originates from in-situ production, from underlying water and even from atmospheric deposition. These conditions will most likely determine the nature of the organic and biogenic material. Here we review the types, sizes, and properties of ocean-derived particles and organic material which present potential candidates for airborne biogenic and organic particles.

  16. Laboratory simulation of organic geochemical processes.

    NASA Technical Reports Server (NTRS)

    Eglinton, G.

    1972-01-01

    Discussion of laboratory simulations that are important to organic geochemistry in that they provide direct evidence relating to geochemical cycles involving carbon. Reviewed processes and experiments include reactions occurring in the geosphere, particularly, short-term diagenesis of biolipids and organochlorine pesticides in estuarine muds, as well as maturation of organic matter in ancient sediments.

  17. Spatial variation in the origin and reactivity of dissolved organic matter in Oregon-Washington coastal waters

    NASA Astrophysics Data System (ADS)

    Lu, YueHan; Edmonds, Jennifer W.; Yamashita, Youhei; Zhou, Bin; Jaegge, Andrea; Baxley, Matthew

    2015-01-01

    Combining stable carbon isotopic signatures (δ13C-DOC) and optical properties of dissolved organic matter (DOM), we examined spatial variability in the sources and reactivity of DOM from Oregon-Washington coastal waters, with a particular focus on evaluating whether these measurements may reliably trace terrigenous DOM in coastal oceans. We sampled four stations on the continental shelf and four stations on the continental slope near the mouth of the Columbia River, with sampling depths ranging from 0 to 1,678 m. Nitrate and phosphate concentrations were largely controlled by organic matter (OM) regeneration although the river plume may have led to excess nitrates in relation to phosphates near the river mouth and/or the surface. Four fluorescence components (C1 to C4) were identified by using excitation emission matrices-parallel factor analysis. C1 and C2 were assigned as humic-like components which represented degraded DOM rather than OM of allochthonous or autochthonous origin. C3 and C4 were both labile, protein-like components representing autochthonous contributions, while C4 was more sensitive to diagenesis. In the shallow water layer (salinity ≤32.5 and depth ≤50 m), the variation in absorption properties (SUVA254 and ɛ280), fluorescence index, freshness index ( β/ α), percent fluorescence of C3, and δ13C-DOC revealed that the Columbia River plume exported DOM that was characterized by greater aromaticity, higher molecular weight, and being more decomposed than marine, autochthonous DOM. However, these signatures of terrigenous DOM disappeared rapidly with increasing depth and offshore distance. In the intermediate and deep water layers (salinity >32.5), the DOM indices were most driven by diagenesis, with changes in percent fluorescence components indicating increasing accumulation of humic DOM relative to protein-like DOM with depth. Principal component analysis that collectively assessed the DOM indices suggests that diagenesis was the primary

  18. Sensitivity of soil organic matter in anthropogenically disturbed organic soils

    NASA Astrophysics Data System (ADS)

    Säurich, Annelie; Tiemeyer, Bärbel; Bechtold, Michel; Don, Axel; Freibauer, Annette

    2016-04-01

    Drained peatlands are hotspots of carbon dioxide (CO2) emissions from agriculture. However, the variability of CO2 emissions increases with disturbance, and little is known on the soil properties causing differences between seemingly similar sites. Furthermore the driving factors for carbon cycling are well studied for both genuine peat and mineral soil, but there is a lack of information concerning soils at the boundary between organic and mineral soils. Examples for such soils are both soils naturally relatively high in soil organic matter (SOM) such as Humic Gleysols and former peat soils with a relative low SOM content due to intensive mineralization or mixing with underlying or applied mineral soil. The study aims to identify drivers for the sensitivity of soil organic matter and therefore for respiration rates of anthropogenically disturbed organic soils, especially those near the boundary to mineral soils. Furthermore, we would like to answer the question whether there are any critical thresholds of soil organic carbon (SOC) concentrations beyond which the carbon-specific respiration rates change. The German agricultural soil inventory samples all agricultural soils in Germany in an 8x8 km² grid following standardized protocols. From this data and sample base, we selected 120 different soil samples from more than 80 sites. As reference sites, three anthropogenically undisturbed peatlands were sampled as well. We chose samples from the soil inventory a) 72 g kg-1 SOC and b) representing the whole range of basic soil properties: SOC (72 to 568 g kg-1), total nitrogen (2 to 29 g kg-1), C-N-ratio (10 to 80) bulk density (0.06 to 1.41 g/cm³), pH (2.5 to 7.4), sand (0 to 95 %) and clay (2 to 70 %) content (only determined for samples with less than 190 g kg-1 SOC) as well as the botanical origin of the peat (if determinable). Additionally, iron oxides were determined for all samples. All samples were sieved (2 mm) and incubated at standardized water content and

  19. Soil Organic Matter and Management of Plant-Parasitic Nematodes

    PubMed Central

    Widmer, T. L.; Mitkowski, N. A.; Abawi, G. S.

    2002-01-01

    Organic matter and its replenishment has become a major component of soil health management programs. Many of the soil's physical, chemical, and biological properties are a function of organic matter content and quality. Adding organic matter to soil influences diverse and important biological activities. The diversity and number of free-living and plant-parasitic nematodes are altered by rotational crops, cover crops, green manures, and other sources of organic matter. Soil management programs should include the use of the proper organic materials to improve soil chemical, physical, and biological parameters and to suppress plant-parasitic nematodes and soilborne pathogens. It is critical to monitor the effects of organic matter additions on activities of major and minor plant-parasitic nematodes in the production system. This paper presents a general review of information in the literature on the effects of crop rotation, cover crops, and green manures on nematodes and their damage to economic crops. PMID:19265946

  20. Soil organic matter and management of plant-parasitic nematodes.

    PubMed

    Widmer, T L; Mitkowski, N A; Abawi, G S

    2002-12-01

    Organic matter and its replenishment has become a major component of soil health management programs. Many of the soil's physical, chemical, and biological properties are a function of organic matter content and quality. Adding organic matter to soil influences diverse and important biological activities. The diversity and number of free-living and plant-parasitic nematodes are altered by rotational crops, cover crops, green manures, and other sources of organic matter. Soil management programs should include the use of the proper organic materials to improve soil chemical, physical, and biological parameters and to suppress plant-parasitic nematodes and soilborne pathogens. It is critical to monitor the effects of organic matter additions on activities of major and minor plant-parasitic nematodes in the production system. This paper presents a general review of information in the literature on the effects of crop rotation, cover crops, and green manures on nematodes and their damage to economic crops. PMID:19265946

  1. Bioavailability and diagenetic state of dissolved organic matter in riparian groundwater

    NASA Astrophysics Data System (ADS)

    Peter, Simone; Shen, Yuan; Kaiser, Karl; Benner, Ronald; Durisch-Kaiser, Edith

    2012-12-01

    Riparian groundwater can exhibit considerable patchiness in the concentration and reactivity of dissolved organic matter (DOM), which ultimately shapes subsurface biogeochemical transformations. Free and combined amino acids are bioavailable constituents of DOM, and their concentration and composition can provide valuable information about the diagenetic state of DOM. Based on riparian groundwater samples and relevant DOM end-member samples, we adapted the amino-acid-based marine DOM degradation index (DI) to groundwater. The groundwater DI was applied to evaluate the spatial and temporal variability in the bioavailability and diagenetic state of riparian DOM in a restored and a channelized section of the River Thur, Switzerland. Among different indicators for DOM diagenetic state (total hydrolysable amino acid concentrations, C-normalized yields, and the contribution of nonprotein amino acids), the groundwater DI correlated best with the activity of the enzyme leucine-aminopeptidase and bacterial secondary production in riparian groundwater. The "freshest" DOM was consistently found in the channel and during high-flow conditions in the groundwater of the restored riparian section and was spatially constrained to a zone inhabited by a dense willow population. The use of amino acid data and the newly developed DI for DOM in groundwater is a promising approach for characterizing the spatial and temporal dynamics of DOM reactivity and diagenesis within riparian groundwater.

  2. Aerobic methane production from organic matter

    NASA Astrophysics Data System (ADS)

    Vigano, I.

    2010-01-01

    Methane, together with H2O, CO2 and N2O, is an important greenhouse gas in th e Earth’s atmosphere playing a key role in the radiative budget. It has be en known for decades that the production of the reduced compound CH4 is possible almost exclusively in anoxic environments per opera of one of the most importan t class of microorganisms which form the Archaea reign. Methane can be produced also from incomplete combustion of organic material. The generation of CH4 in an oxygenated environment under near-ambient conditions is a new discovery made in 2006 by Keppler et. al where surprisingly they measured emissions of this green house gas from plants incubated in chambers with air containing 20% of oxygen. A lthough the estimates on a global scale are still object of an intensive debate, the results presented in this thesis clearly show the existence of methane prod uction under oxic conditions for non living plant material. Temperature and UV l ight are key factors that drive the generation of CH4 from plant matter in a wel l oxygenated environment.

  3. The evolution of organic matter in space.

    PubMed

    Ehrenfreund, Pascale; Spaans, Marco; Holm, Nils G

    2011-02-13

    Carbon, and molecules made from it, have already been observed in the early Universe. During cosmic time, many galaxies undergo intense periods of star formation, during which heavy elements like carbon, oxygen, nitrogen, silicon and iron are produced. Also, many complex molecules, from carbon monoxide to polycyclic aromatic hydrocarbons, are detected in these systems, like they are for our own Galaxy. Interstellar molecular clouds and circumstellar envelopes are factories of complex molecular synthesis. A surprisingly high number of molecules that are used in contemporary biochemistry on the Earth are found in the interstellar medium, planetary atmospheres and surfaces, comets, asteroids and meteorites and interplanetary dust particles. Large quantities of extra-terrestrial material were delivered via comets and asteroids to young planetary surfaces during the heavy bombardment phase. Monitoring the formation and evolution of organic matter in space is crucial in order to determine the prebiotic reservoirs available to the early Earth. It is equally important to reveal abiotic routes to prebiotic molecules in the Earth environments. Materials from both carbon sources (extra-terrestrial and endogenous) may have contributed to biochemical pathways on the Earth leading to life's origin. The research avenues discussed also guide us to extend our knowledge to other habitable worlds. PMID:21220279

  4. TILLAGE AND RESIDUE MANAGEMENT EFFECTS ON SOIL ORGANIC MATTER

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This college-level textbook is designed to help students and researchers understand the complexity of how to manage soil organic matter in a diversity of agroecosystems. This chapter describes the current state of knowledge on how tillage and residue management affect soil organic matter. Types of t...

  5. Complexation of trace metals by adsorbed natural organic matter

    USGS Publications Warehouse

    Davis, J.A.

    1984-01-01

    The adsorption behavior and solution speciation of Cu(II) and Cd(II) were studied in model systems containing colloidal alumina particles and dissolved natural organic matter. At equilibrium a significant fraction of the alumina surface was covered by adsorbed organic matter. Cu(II) was partitioned primarily between the surface-bound organic matter and dissolved Cu-organic complexes in the aqueous phase. Complexation of Cu2+ with the functional groups of adsorbed organic matter was stronger than complexation with uncovered alumina surface hydroxyls. It is shown that the complexation of Cu(II) by adsorbed organic matter can be described by an apparent stability constant approximately equal to the value found for solution phase equilibria. In contrast, Cd(II) adsorption was not significantly affected by the presence of organic matter at the surface, due to weak complex formation with the organic ligands. The results demonstrate that general models of trace element partitioning in natural waters must consider the presence of adsorbed organic matter. ?? 1984.

  6. Kinetics of desorption of organic compounds from dissolved organic matter.

    PubMed

    Kopinke, Frank-Dieter; Ramus, Ksenia; Poerschmann, Juergen; Georgi, Anett

    2011-12-01

    This study presents a new experimental technique for measuring rates of desorption of organic compounds from dissolved organic matter (DOM) such as humic substances. The method is based on a fast solid-phase extraction of the freely dissolved fraction of a solute when the solution is flushed through a polymer-coated capillary. The extraction interferes with the solute-DOM sorption equilibrium and drives the desorption process. Solutes which remain sorbed to DOM pass through the extraction capillary and can be analyzed afterward. This technique allows a time resolution for the desorption kinetics from subseconds up to minutes. It is applicable to the study of interaction kinetics between a wide variety of hydrophobic solutes and polyelectrolytes. Due to its simplicity it is accessible for many environmental laboratories. The time-resolved in-tube solid-phase microextraction (TR-IT-SPME) was applied to two humic acids and a surfactant as sorbents together with pyrene, phenanthrene and 1,2-dimethylcyclohexane as solutes. The results give evidence for a two-phase desorption kinetics: a fast desorption step with a half-life of less than 1 s and a slow desorption step with a half-life of more than 1 min. For aliphatic solutes, the fast-desorbing fraction largely dominates, whereas for polycyclic aromatic hydrocarbons such as pyrene, the slowly desorbing, stronger-bound fraction is also important. PMID:22035249

  7. Organic Matter Polymerization by Disulfide Bonding Near the Chemocline in Cariaco Basin

    NASA Astrophysics Data System (ADS)

    Raven, M. R.; Adkins, J. F.; Sessions, A. L.

    2013-12-01

    The preservation of organic carbon in sediments as kerogen is an essential pathway in the global carbon cycle, but the chemical reactions involved in kerogen formation remain poorly understood. Previous researchers have found that many sediments deposited under euxinic conditions contain sulfur-bearing non-polar lipids as well as disulfide bonds among lipid and carbohydrate monomers. It remains unclear, however, when during organic matter decomposition and diagenesis these different sulfur-bearing structures form, and how different environmental conditions affect the extent of organic matter sulfurization. We investigate organic sulfurization processes armed with a technique for measuring the sulfur-isotopic compositions of individual organosulfur compounds by coupled gas chromatography - inductively coupled plasma mass spectrometry. Organic compounds were extracted from sediments and water column sediment traps from Cariaco Basin, a euxinic basin in the Caribbean Sea. We measured the sulfur-isotopic compositions of both non-polar lipids and of derivatized disulfide-bound compounds from eight sediment trap profiles and a six-meter-long sediment core. In Cariaco Basin, lipid sulfurization processes appear to begin near the chemocline and continue in sediments on timescales of thousands of years. Slow diagenetic sulfurization in sediments produces lipid monomers with sulfur atoms in ring structures that are 34S-depleted relative to coexisting dissolved sulfide. Lipid monomers become progressively enriched in 34S over time, indicating ongoing formation coinciding with an increase in the amount of total sulfur in bulk kerogen. One of the most abundant monomers observed in Cariaco sediments, a phytol-related thiophene, is also produced intermittently near the chemocline. Phytol thiophene δ34S values in sediment traps are similar to those observed in shallow Cariaco sediments except during occasional ';enrichment events,' when phytol thiophene δ34S values increase to

  8. Subcritical water extraction of organic matter from sedimentary rocks.

    PubMed

    Luong, Duy; Sephton, Mark A; Watson, Jonathan S

    2015-06-16

    Subcritical water extraction of organic matter containing sedimentary rocks at 300°C and 1500 psi produces extracts comparable to conventional solvent extraction. Subcritical water extraction of previously solvent extracted samples confirms that high molecular weight organic matter (kerogen) degradation is not occurring and that only low molecular weight organic matter (free compounds) are being accessed in analogy to solvent extraction procedures. The sedimentary rocks chosen for extraction span the classic geochemical organic matter types. A type I organic matter-containing sedimentary rock produces n-alkanes and isoprenoidal hydrocarbons at 300°C and 1500 psi that indicate an algal source for the organic matter. Extraction of a rock containing type II organic matter at the same temperature and pressure produces aliphatic hydrocarbons but also aromatic compounds reflecting the increased contributions from terrestrial organic matter in this sample. A type III organic matter-containing sample produces a range of non-polar and polar compounds including polycyclic aromatic hydrocarbons and oxygenated aromatic compounds at 300°C and 1500 psi reflecting a dominantly terrestrial origin for the organic materials. Although extraction at 300°C and 1500 psi produces extracts that are comparable to solvent extraction, lower temperature steps display differences related to organic solubility. The type I organic matter produces no products below 300°C and 1500 psi, reflecting its dominantly aliphatic character, while type II and type III organic matter contribute some polar components to the lower temperature steps, reflecting the chemical heterogeneity of their organic inventory. The separation of polar and non-polar organic compounds by using different temperatures provides the potential for selective extraction that may obviate the need for subsequent preparative chromatography steps. Our results indicate that subcritical water extraction can act as a suitable

  9. Dissolved Organic Matter and Emerging Contaminants in Urban Stream Ecosystems

    NASA Astrophysics Data System (ADS)

    Kaushal, S. S.; Findlay, S.; Groffman, P.; Belt, K.; Delaney, K.; Sides, A.; Walbridge, M.; Mayer, P.

    2009-05-01

    We investigated the effects of urbanization on the sources, bioavailability and forms of natural and anthropogenic organic matter found in streams located in Maryland, U.S.A. We found that the abundance, biaoavailability, and enzymatic breakdown of dissolved organic carbon (DOC), dissolved organic nitrogen (DON), and dissolved organic phosphorus (DOP) increased in streams with increasing watershed urbanization suggesting that organic nutrients may represent a growing form of nutrient loading to coastal waters associated with land use change. Organic carbon, nitrogen, and phosphorus in urban streams were elevated several-fold compared to forest and agricultural streams. Enzymatic activities of stream microbes in organic matter decomposition were also significantly altered across watershed land use. Chemical characterization suggested that organic matter in urban streams originated from a variety of sources including terrestrial, sewage, and in-stream transformation. In addition, a characterization of emerging organic contaminants (polyaromatic cyclic hydrocarbons, organochlorine pesticides, and polybrominated diphenyl ether flame retardents), showed that organic contaminants and dissolved organic matter increase with watershed urbanization and fluctuate substantially with changing climatic conditions. Elucidating the emerging influence of urbanization on sources, transport, and in-stream transformation of organic nutrients and contaminants will be critical in unraveling the changing role of organic matter in urban degraded and restored stream ecosystems.

  10. Changes in River Organic Matter Through Time.

    NASA Astrophysics Data System (ADS)

    Hudson, N.; Baker, A.; Ward, D.

    2006-12-01

    fluorescence, as an increase in pH was also observed in these samples. This work illustrates the dynamic character of river organic matter within a timescale and under conditions that are representative of the natural system.

  11. Degradation of natural organic matter: A thermodynamic analysis

    NASA Astrophysics Data System (ADS)

    LaRowe, Douglas E.; Van Cappellen, Philippe

    2011-04-01

    The oxidative degradation of organic matter is a key process in the biogeochemical functioning of the earth system. Quantitative models of organic matter degradation are therefore essential for understanding the chemical state and evolution of the Earth's near-surface environment, and to forecast the biogeochemical consequences of ongoing regional and global change. The complex nature of biologically produced organic matter represents a major obstacle to the development of such models, however. Here, we compare the energetics of the oxidative degradation of a large number of naturally occurring organic compounds. By relating the Gibbs energies of half reactions describing the complete mineralization of the compounds to their average nominal carbon oxidation state, it becomes possible to estimate the energetic potential of the compounds based on major element (C, H, N, O, P, S) ratios. The new energetic description of organic matter can be combined with bioenergetic theory to rationalize observed patterns in the decomposition of natural organic matter. For example, the persistence of cell membrane derived compounds and complex organics in anoxic settings is consistent with their limited catabolic potential under these environmental conditions. The proposed approach opens the way to include the thermodynamic properties of organic compounds in kinetic models of organic matter degradation.

  12. Spatial Complexity of Soil Organic Matter Forms at Nanometre Scales

    SciTech Connect

    Lehmann,J.; Solomon, D.; Kinyangi, J.; Dathe, L.; Wirick, S.; Jacobsen, C.

    2008-01-01

    Organic matter in soil has been suggested to be composed of a complex mixture of identifiable biopolymers1 rather than a chemically complex humic material2. Despite the importance of the spatial arrangement of organic matter forms in soil3, its characterization has been hampered by the lack of a method for analysis at fine scales. X-ray spectromicroscopy has enabled the identification of spatial variability of organic matter forms, but was limited to extracted soil particles4 and individual micropores within aggregates5, 6. Here, we use synchrotron-based near-edge X-ray spectromicroscopy7 of thin sections of entire and intact free microaggregates6 to demonstrate that on spatial scales below 50 nm resolution, highly variable yet identifiable organic matter forms, such as plant or microbial biopolymers, can be found in soils at distinct locations of the mineral assemblage. Organic carbon forms detected at this spatial scale had no similarity to organic carbon forms of total soil. In contrast, we find that organic carbon forms of total soil were remarkably similar between soils from several temperate and tropical forests with very distinct vegetation composition and soil mineralogy. Spatial information on soil organic matter forms at the scale provided here could help to identify processes of organic matter cycling in soil, such as carbon stability or sequestration and responses to a changing climate.

  13. Deformation behaviors of peat with influence of organic matter.

    PubMed

    Yang, Min; Liu, Kan

    2016-01-01

    Peat is a kind of special material rich in organic matter. Because of the high content of organic matter, it shows different deformation behaviors from conventional geotechnical materials. Peat grain has a non-negligible compressibility due to the presence of organic matter. Biogas can generate from peat and can be trapped in form of gas bubbles. Considering the natural properties of peat, a special three-phase composition of peat is described which indicates the existence of organic matter and gas bubbles in peat. A stress-strain-time model is proposed for the compression of organic matter, and the surface tension effect is considered in the compression model of gas bubbles. Finally, a mathematical model has been developed to simulate the deformation behavior of peat considering the compressibility of organic matter and entrapped gas bubbles. The deformation process is the coupling of volume variation of organic matter, gas bubbles and water drainage. The proposed model is used to simulate a series of peat laboratory oedometer tests, and the model can well capture the test results with reasonable model parameters. Effects of model parameters on deformation of peat are also analyzed. PMID:27247870

  14. Spectral band selection for classification of soil organic matter content

    NASA Technical Reports Server (NTRS)

    Henderson, Tracey L.; Szilagyi, Andrea; Baumgardner, Marion F.; Chen, Chih-Chien Thomas; Landgrebe, David A.

    1989-01-01

    This paper describes the spectral-band-selection (SBS) algorithm of Chen and Landgrebe (1987, 1988, and 1989) and uses the algorithm to classify the organic matter content in the earth's surface soil. The effectiveness of the algorithm was evaluated comparing the results of classification of the soil organic matter using SBS bands with those obtained using Landsat MSS bands and TM bands, showing that the algorithm was successful in finding important spectral bands for classification of organic matter content. Using the calculated bands, the probabilities of correct classification for climate-stratified data were found to range from 0.910 to 0.980.

  15. Interstellar chemistry recorded in organic matter from primitive meteorites.

    PubMed

    Busemann, Henner; Young, Andrea F; Alexander, Conel M O'd; Hoppe, Peter; Mukhopadhyay, Sujoy; Nittler, Larry R

    2006-05-01

    Organic matter in extraterrestrial materials has isotopic anomalies in hydrogen and nitrogen that suggest an origin in the presolar molecular cloud or perhaps in the protoplanetary disk. Interplanetary dust particles are generally regarded as the most primitive solar system matter available, in part because until recently they exhibited the most extreme isotope anomalies. However, we show that hydrogen and nitrogen isotopic compositions in carbonaceous chondrite organic matter reach and even exceed those found in interplanetary dust particles. Hence, both meteorites (originating from the asteroid belt) and interplanetary dust particles (possibly from comets) preserve primitive organics that were a component of the original building blocks of the solar system. PMID:16675696

  16. Pyrogenic organic matter can alter microbial communication

    NASA Astrophysics Data System (ADS)

    Masiello, Caroline; Gao, Xiaodong; Cheng, Hsiao-Ying; Silberg, Jonathan

    2016-04-01

    Soil microbes communicate with each other to manage a large range of processes that occur more efficiently when microbes are able to act simultaneously. This coordination occurs through the continuous production of signaling compounds that are easily diffused into and out of cells. As the number of microbes in a localized environment increases, the internal cellular concentration of these signaling compounds increases, and when a threshold concentration is reached, gene expression shifts, leading to altered (and coordinated) microbial behaviors. Many of these coordinated behaviors have biogeochemically important outcomes. For example, methanogenesis, denitrification, biofilm formation, and the development of plant-rhizobial symbioses are all regulated by a simple class of cell-cell signaling molecules known as acyl homoserine lactones (AHLs). Pyrogenic organic matter in soils can act to disrupt microbial communication through multiple pathways. In the case of AHLs, charcoal's very high surface area can sorb these signaling compounds, preventing microbes from detecting each others' presence (Masiello et al., 2014). In addition, the lactone ring in AHLs is vulnerable to pH increases accompanying PyOM inputs, with soil pH values higher than 7-8 leading to ring opening and compound destabilization. Different microbes use different classes of signaling compounds, and not all microbial signaling compounds are pH-vulnerable. This implies that PyOM-driven pH increases may trigger differential outcomes for Gram negative bacteria vs fungi, for example. A charcoal-driven reduction in microbes' ability to detect cell-cell communication compounds may lead to a shift in the ability of microbes to participate in key steps of C and N cycling. For example, an increase in an archaeon-specific AHL has been shown to lead to a cascade of metabolic processes that eventually results in the upregulation of CH4 production (Zhang et al., 2012). Alterations in similar AHL compounds leads to

  17. Investigation of the organic matter in inactive nuclear tank liquids

    SciTech Connect

    Schenley, R.L.; Griest, W.H.

    1990-08-01

    Environmental Protection Agency (EPA) methodology for regulatory organics fails to account for the organic matter that is suggested by total organic carbon (TOC) analysis in the Oak Ridge National Laboratory (ORNL) inactive nuclear waste-tank liquids and sludges. Identification and measurement of the total organics are needed to select appropriate waste treatment technologies. An initial investigation was made of the nature of the organics in several waste-tank liquids. This report details the analysis of ORNL wastes.

  18. Geochemical effects of rapid sedimentation in aquatic systems: Minimal diagenesis and the preservation of historical metal signatures

    USGS Publications Warehouse

    Callender, E.

    2000-01-01

    Rapid sedimentation exerts a pronounced influence on early sedimentary diagenesis in that there is insufficient time for a sediment particle to equilibrate in any one sediment layer before that layer may be displaced vertically by another layer. These sedimentation patterns are common in surface-water reservoirs whose sedimentation rates (1-10 cm yr-1) are several orders of magnitude greater than those for natural lakes (0.01-0.5 cm yr-1). Two examples of the effects of rapid sedimentation on geochemical metal signatures are presented here. Interstitial-water data (Fe) from two sites in the Cheyenne River Embayment of Lake Oahe on the Missouri River illustrate the effects of changing sedimentation rates on dissolved species. Rapid burial during high-flow yrs appears to limit early sedimentary diagenesis to aerobic respiration. Solid-phase metal data (Pb) from a site in Pueblo Reservoir on the upper Arkansas River in Colorado appear to record historical releases by flooding of abandoned mine sites upstream in Leadville, Colorado. Interstitial-water ammonia and ferrous Fe data indicate that at least one interval at depth in the sediment where solid metal concentrations peak is a zone of minimal diagenesis. The principal diagenetic reactions that occur in these sediments are aerobic respiration and the reduction of Mn and Fe oxides. Under slower sedimentation conditions, there is sufficient time for particulate organic matter to decompose and create a diagenetic environment where metal oxides may not be stable. The quasi-steady-state interstitial Fe profiles from Tidal Potomac River sediments are an example of such a situation. This occurs primarily because the residence time of particles in the surficial sediment column is long enough to allow benthic organisms and bacteria to perform their metabolic functions. When faster sedimentation prevails, there is less time for these metabolic reactions to occur since the organisms do not occupy a sediment layer for any

  19. Characterizing Variability In Ohio River Natural Organic Matter

    EPA Science Inventory

    Surface water contains natural organic matter (NOM) which reacts with disinfectants creating disinfection byproducts (DBPs), some of which are USEPA regulated contaminants. Characterizing NOM can provide important insight on DBP formation and water treatment process adaptation t...

  20. Ectomycorrhizal fungi - potential organic matter decomposers, yet not saprotrophs.

    PubMed

    Lindahl, Björn D; Tunlid, Anders

    2015-03-01

    Although hypothesized for many years, the involvement of ectomycorrhizal fungi in decomposition of soil organic matter remains controversial and has not yet been fully acknowledged as an important factor in the regulation of soil carbon (C) storage. Here, we review recent findings, which support the view that some ectomycorrhizal fungi have the capacity to oxidize organic matter, either by 'brown-rot' Fenton chemistry or using 'white-rot' peroxidases. We propose that ectomycorrhizal fungi benefit from organic matter decomposition primarily through increased nitrogen mobilization rather than through release of metabolic C and question the view that ectomycorrhizal fungi may act as facultative saprotrophs. Finally, we discuss how mycorrhizal decomposition may influence organic matter storage in soils and mediate responses of ecosystem C sequestration to environmental changes. PMID:25524234

  1. Artificial maturation of an immature sulfur- and organic matter-rich limestone from the Ghareb Formation, Jordan

    USGS Publications Warehouse

    Koopmans, M.P.; Rijpstra, W.I.C.; De Leeuw, J. W.; Lewan, M.D.; Damste, J.S.S.

    1998-01-01

    An immature (Ro=0.39%), S-rich (S(org)/C = 0.07), organic matter-rich (19.6 wt. % TOC) limestone from the Ghareb Formation (Upper Cretaceous) in Jordan was artificially matured by hydrous pyrolysis (200, 220 ..., 300??C; 72 h) to study the effect of progressive diagenesis and early catagenesis on the amounts and distributions of hydrocarbons, organic sulfur compounds and S-rich geomacromolecules. The use of internal standards allowed the determination of absolute amounts. With increasing thermal maturation, large amounts of alkanes and alkylthiophenes with predominantly linear carbon skeletons are generated from the kerogen. The alkylthiophene isomer distributions do not change significantly with increasing thermal maturation, indicating the applicability of alkylthiophenes as biomarkers at relatively high levels of thermal maturity. For a given carbon skeleton, the saturated hydrocarbon, alkylthiophenes and alkylbenzo[b]thiophenes are stable forms at relatively high temperatures, whereas the alkylsulfides are not stable. The large amount of alkylthiophenes produced relative to the alkanes may be explained by the large number of monosulfide links per carbon skeleton. These results are in good agreement with those obtained previously for an artificial maturation series of an immature S-rich sample from the Gessoso-solfifera Formation.An immature (Ro = 0.39%), S-rich (Sorg/C = 0.07), organic matter-rich (19.6 wt.% TOC) limestone from the Ghareb Formation (Upper Cretaceous) in Jordan was artificially matured by hydrous pyrolysis (200, 220, ..., 300??C; 72 h) to study the effect of progressive diagenesis and early catagenesis on the amounts and distributions of hydrocarbons, organic sulfur compounds and S-rich geomacromolecules. The use of internal standards allowed the determination of absolute amounts. With increasing thermal maturation, large amounts of alkanes and alkylthiophenes with predominantly linear carbon skeletons are generated from the kerogen. The

  2. Composition and reactivity of ferrihydrite-organic matter associations

    NASA Astrophysics Data System (ADS)

    Eusterhues, Karin; Hädrich, Anke; Neidhardt, Julia; Küsel, Kirsten; Totsche, Kai

    2014-05-01

    The formation of organo-mineral associations affects many soil forming processes. On the one hand, it will influence soil organic matter composition and development, because the complex organic matter mixtures usually fractionate during their association with mineral surfaces. Whereas the associated fraction is supposed to be stabilized, the non-associated fraction remains mobile and available to degradation by microorganisms. On the other hand, the organic coating will completely change the interface properties of Fe oxides such as solubility, charge and hydrophobicity. This in turn will strongly influence their reactivity towards nutrients and pollutants, the adsorption of new organic matter, and the availability of ferric Fe towards microorganisms. To better understand such processes we produced ferrihydrite-organic matter associations by adsorption and coprecipitation in laboratory experiments. As a surrogate for dissolved soil organic matter we used the water-extractable fraction of a Podzol forest-floor layer under spruce. Sorptive fractionation of the organic matter was investigated by 13C NMR and FTIR. Relative to the original forest-floor extract, the ferrihydrite-associated OM was enriched in polysaccharides but depleted in aliphatic C and carbonyl C, especially when adsorption took place. Liquid phase incubation experiments were carried out with an inoculum extracted from the podzol forest-floor under oxic conditions at pH 4.8 to quantify the mineralization of the adsorbed and coprecipitated organic matter. These experiments showed that the association with ferrihydrite stabilized the associated organic matter, but that differences in the degradability of adsorbed and coprecipitated organic matter were small. We therefore conclude that coprecipitation does not lead to a significant formation of microbial inaccessible organic matter domains. Microbial reduction experiments were performed using Geobacter bremensis. We observed that increasing amounts of

  3. Paleomagnetic dating of burial diagenesis in Mississippian carbonates, Utah

    NASA Astrophysics Data System (ADS)

    Blumstein, Angela M.; Elmore, R. Douglas; Engel, Michael H.; Elliot, Crawford; Basu, Ankan

    2004-04-01

    The objective of this study is to test models for the origin of widespread secondary magnetizations in the Mississippian Deseret Limestone. The Delle Phosphatic Member of the Deseret Limestone is a source rock for hydrocarbons, and modeling studies indicate that it entered the oil window in the Early Cretaceous during the Sevier orogeny. Paleomagnetic and rock magnetic results from the Deseret Limestone and the stratigraphically equivalent Chainman Shale in central and western Utah indicate that the units contain two ancient magnetizations residing in magnetite. Burial temperatures are too low for the magnetizations to be thermoviscous in origin, and they are interpreted to be chemical remanent magnetizations (CRMs). Fold tests from western Utah indicate the presence of a prefolding Triassic to Jurassic CRM. Geochemical (87Sr/86Sr, δ13C, and δ18O) and petrographic analyses suggest that externally derived fluids did not alter these rocks. This CRM was acquired at the beginning of the oil window and is interpreted to be the result of burial diagenesis of organic matter. A second younger CRM in western central Utah is apparently postfolding and is probably Late Cretaceous to early Tertiary in age. On the basis of the thermal modeling, the timing overlaps with the oil window. These results are consistent with a connection between organic matter maturation and remagnetization. Modeling of the smectite-to-illite transformation in the Deseret Limestone suggests a mean age prior to acquisition of both CRMs, although the range for illitization overlaps with the Triassic to Jurassic CRM. The results of this study support the hypothesis that pervasive CRMs can be related to burial diagenetic processes. In addition, paleomagnetism can be used to determine the timing of such processes, which can benefit hydrocarbon exploration efforts.

  4. High dimensional reflectance analysis of soil organic matter

    NASA Technical Reports Server (NTRS)

    Henderson, T. L.; Baumgardner, M. F.; Franzmeier, D. P.; Stott, D. E.; Coster, D. C.

    1992-01-01

    Recent breakthroughs in remote-sensing technology have led to the development of high spectral resolution imaging sensors for observation of earth surface features. This research was conducted to evaluate the effects of organic matter content and composition on narrowband soil reflectance across the visible and reflective infrared spectral ranges. Organic matter from four Indiana agricultural soils, ranging in organic C content from 0.99 to 1.72 percent, was extracted, fractionated, and purified. Six components of each soil were isolated and prepared for spectral analysis. Reflectance was measured in 210 narrow bands in the 400- to 2500-nm wavelength range. Statistical analysis of reflectance values indicated the potential of high dimensional reflectance data in specific visible, near-infrared, and middle-infrared bands to provide information about soil organic C content, but not organic matter composition. These bands also responded significantly to Fe- and Mn-oxide content.

  5. The search for indigenous lunar organic matter.

    NASA Technical Reports Server (NTRS)

    Sagan, C.

    1972-01-01

    It is argued that the absence of organic compounds from returned lunar samples is to be expected even for a lunar history rich in primordial organics. The sites most likely to yield lunar organic compounds have not been investigated, and there may be an area of investigation conceivably critical to problems in prebiological chemistry and the early history of the solar system awaiting continued lunar exploration, manned or unmanned.

  6. Organic Matter in Space (IAU S251)

    NASA Astrophysics Data System (ADS)

    Kwok, Sun; Sanford, Scott

    2009-01-01

    Preface; From the local organising committee; Organising committee; Conference participants; Opening address of Symposium 251 C. Cesarsky; Session I. Observations of organic compounds beyond the Solar System William Irvine, Ewine van Dishoeck, Yvonne Pendleton and Hans Olofsson; Session II. Organic compounds within the Solar System Scott Sandford, Ernst Zinner and Dale Cruikshank; Session III. Laboratory analogues of organic compounds in space Max Bernstein and Thomas Henning; Banquet speech; Author index; Object index.

  7. Organic Matter in Space (IAU S251)

    NASA Astrophysics Data System (ADS)

    Kwok, Sun; Sanford, Scott

    2008-10-01

    Preface; From the local organising committee; Organising committee; Conference participants; Opening address of Symposium 251 C. Cesarsky; Session I. Observations of organic compounds beyond the Solar System William Irvine, Ewine van Dishoeck, Yvonne Pendleton and Hans Olofsson; Session II. Organic compounds within the Solar System Scott Sandford, Ernst Zinner and Dale Cruikshank; Session III. Laboratory analogues of organic compounds in space Max Bernstein and Thomas Henning; Banquet speech; Author index; Object index.

  8. Mineralogy and diagenesis of miocene and pleistocene sediments, Northeastern Gulf of Mexico

    SciTech Connect

    Conner, S.P.; Denham, M.E.; Tieh, T.T.

    1988-01-01

    Cored Miocene and Pleistocene sediments from the northeastern Gulf of Mexico (ranging in depth from 1,400 to 2,000 m) consist of interbedded sands, silts, and muds with varying degrees of consolidation. Samples selected from these sediments were studied for their mineralogy and diagenesis. The Miocene sediments represent various subenvironments of the ancestral Mississippi River delta complex; Pleistocene sediments are marine shelf deposits. Sands from both Miocene and Pleistocene cores are fine to very fine-grained feldspathic litharenites with abundant (approx. = 25%) matrix fines and minor (<7%) carbonate clasts and shell fragments. Carbonate diagenesis is a continuing process in these sediments. Clayey sands contain disseminated siderite crystallites formed during organic matter fermentation. In clean sands, scattered thin (<15 cm) bands of poikilotopic carbonate-cemented sand are present in the middle of thicker unconsolidated intervals. Cemented bands are thicker in the Miocene section, having grown during burial through dissolution of shell fragments and reprecipitation at the margin of cemented zones. Diagenetic events evident in the Miocene core illustrate processes that could occur in the Pleistocene sediments with continued burial. These are: (1) dolomitization of some calcite cements, (2) precipitation of Fe-carbonate as crystallites, rims on dolomite cements, and overgrowths on siderite crystallites, and (3) zeolite formation on amorphous silica substrates. Amorphous silica is associated with limited dissolution of feldspars or lithic fragments.

  9. Modeling organic matter stabilization during windrow composting of livestock effluents.

    PubMed

    Oudart, D; Paul, E; Robin, P; Paillat, J M

    2012-01-01

    Composting is a complex bioprocess, requiring a lot of empirical experiments to optimize the process. A dynamical mathematical model for the biodegradation of the organic matter during the composting process has been developed. The initial organic matter expressed by chemical oxygen demand (COD) is decomposed into rapidly and slowly degraded compartments and an inert one. The biodegradable COD is hydrolysed and consumed by microorganisms and produces metabolic water and carbon dioxide. This model links a biochemical characterization of the organic matter by Van Soest fractionating with COD. The comparison of experimental and simulation results for carbon dioxide emission, dry matter and carbon content balance showed good correlation. The initial sizes of the biodegradable COD compartments are explained by the soluble, hemicellulose-like and lignin fraction. Their sizes influence the amplitude of the carbon dioxide emission peak. The initial biomass is a sensitive variable too, influencing the time at which the emission peak occurs. PMID:23393964

  10. Defining the quality of soil organic matter

    EPA Science Inventory

    Soils represent the largest terrestrial pool of carbon (C) and hold approximately two-thirds of all C held in these ecosystems. However, not all C in soils is of equal quality. Some fractions of the organic forms, i.e., soil organic carbon (SOC) have long residence times while ...

  11. Onshore-offshore gradient in reductive early diagenesis in coastal marine sediments of the Ria de Vigo, Northwest Iberian Peninsula

    NASA Astrophysics Data System (ADS)

    Mohamed, K. J.; Rey, D.; Rubio, B.; Dekkers, M. J.; Roberts, A. P.; Vilas, F.

    2011-04-01

    Early diagenetic modification of magnetic properties is an important process in marine sediments, but temporal and spatial variability of diagenetic processes have rarely been reported for recent coastal sediments. The magnetic properties of sediments from the Ria de Vigo (NW Spain) define a marked three-part zonation with depth. The uppermost zone is magnetically dominated by (titano-)magnetite. In the intermediate zone, rapid down-core dissolution of (titano-)magnetite increases the relative influence of high-coercivity magnetic minerals, which react more slowly during reductive dissolution than (titano-)magnetite. This zone is characterized by the ubiquitous occurrence of framboidal iron sulphides. Pyrite is the dominant iron sulphide, but framboidal ferrimagnetic greigite is also frequently observed in association with pyrite. The lowermost zone is characterized by an almost complete depletion of magnetic minerals associated with progressive reduction of detrital iron oxides with depth. This zonation is controlled by organic matter diagenesis, which varies with water depth and wave-induced sediment resuspension and organic matter reoxidation in the water column. This leads to a shallowing and thinning of each zone with more intense reductive diagenesis toward the interior of the ria. Such a zonation seems to be a common feature in shallow water marine environments. If preserved, the described zonation and its spatial variability provide a potential tool for detecting estuarine-like environments in the geological record. Magnetic detection of current or past reductive conditions also has important implications for assessing paleoenvironmental proxies that are sensitive to diagenetic redox state.

  12. Effects of Crayfish on Quality of Fine Particulate Organic Matter

    NASA Astrophysics Data System (ADS)

    Montemarano, J. J.; Kershner, M. W.; Leff, L. G.

    2005-05-01

    The origin and ontogeny of detritus often determines its bioavailability. Crayfish shred and consume detrital organic matter, influencing fine particulate organic matter (FPOM) availability, composition and quality. Given consumption of FPOM by many invertebrates, crayfish can indirectly affect these organisms by altering FPOM bioavailability through organic matter fragmentation, biofilm disturbance, and defecation. These effects may or may not vary among coarse particulate organic matter (CPOM) from different leaf species. To assess crayfish effects on FPOM quality, crayfish were fed stream-conditioned maple or oak leaves in hanging 1-mm mesh-bottom baskets in aquaria. After 12 h, crayfish and remaining leaves were removed. FPOM fragments that fell through the mesh were vacuum filtered and analyzed for percent organic matter, C:N ratio, and bacterial abundance. The same analyses were conducted on crayfish feces collected using finger cots encasing crayfish abdomens. C:N ratios did not differ between feces and maple leaf CPOM, but were lower in FPOM produced through fragmentation and disturbance (P = 0.023). Overall, crayfish alter the ontogeny of detritus, which may, in turn, affect stream FPOM dynamics.

  13. Organic Matter Application Can Reduce Copper Toxicity in Tomato Plants

    ERIC Educational Resources Information Center

    Campbell, Brian

    2010-01-01

    Copper fungicides and bactericides are often used in tomato cultivation and can cause toxic Cu levels in soils. In order to combat this, organic matter can be applied to induce chelation reactions and form a soluble complex by which much of the Cu can leach out of the soil profile or be taken up safely by plants. Organic acids such as citric,…

  14. Black Carbon in Estuarine and Coastal Ocean Dissolved Organic Matter

    NASA Technical Reports Server (NTRS)

    Mannino, Antonio; Harvey, H. Rodger

    2003-01-01

    Analysis of high-molecular-weight dissolved organic matter (DOM) from two estuaries in the northwest Atlantic Ocean reveals that black carbon (BC) is a significant component of previously uncharacterized DOM, suggesting that river-estuary systems are important exporters of recalcitrant dissolved organic carbon to the ocean.

  15. Pedogenesis evolution of mine technosols: focus onto organic matter implication

    NASA Astrophysics Data System (ADS)

    Grégoire, Pascaud; Marilyne, Soubrand; Laurent, Lemee; Husseini Amelène, El-Mufleh Al; Marion, Rabiet; Emmanuel, Joussein

    2014-05-01

    Keywords: Mine technosols, pedogenesis, organic matter, environmental impact, pyr-GC-MS Technosols include soils subject to strong anthropogenic pressure and particularly to soil influenced by human transformed materials. In this context, abandoned mine sites contain a large amount of transformed waste materials often enriched with metals and/or metalloids. The natural evolution of technosols (pedogenesis) may induces the change in contaminants behaviour in term of stability of bearing phases, modification of pH oxydo-reduction conditions, organic matter turnover, change in permeability, or influence of vegetation cover. The fate of these elements in the soil can induce major environmental problems (contamination of biosphere and water resource). This will contribute to a limited potential use of these soils, which represent yet a large area around the world. The initial contamination of the parental material suggests that the pedological cover would stabilize the soil; however, the chemical reactivity must be taken in consideration particularly with respect to potential metal leachings. In this case, it is quite important to understand the development of soil in this specific context. Consequently, the global aims of this study are to understand the functioning of mine Technosols focusing onto the organic matter implication in their pedogenesis. Indeed, soil organic matter constitutes an heterogeneous fraction of organic compounds that plays an important role in the fate and the transport of metals and metalloids in soils. Three different soil profiles were collected representative to various mining context (contamination, time, climat), respectively to Pb-Ag, Sn and Au exploitations. Several pedological parameters were determined like CEC, pH, %Corg, %Ntot, C/N ratio, grain size distribution and chemical composition. The evolution of the nature of organic matter in Technosol was studied by elemental analyses and thermochemolysis was realized on the total and

  16. Selective preservation of organic matter in marine environments; processes and impact on the sedimentary record

    NASA Astrophysics Data System (ADS)

    Zonneveld, K. A. F.; Versteegh, G. J. M.; Kasten, S.; Eglinton, T. I.; Emeis, K.-C.; Huguet, C.; Koch, B. P.; de Lange, G. J.; de Leeuw, J. W.; Middelburg, J. J.; Mollenhauer, G.; Prahl, F. G.; Rethemeyer, J.; Wakeham, S. G.

    2010-02-01

    The present paper is the result of a workshop sponsored by the DFG Research Center/Cluster of Excellence MARUM "The Ocean in the Earth System", the International Graduate College EUROPROX, and the Alfred Wegener Institute for Polar and Marine Research. The workshop brought together specialists on organic matter degradation and on proxy-based environmental reconstruction. The paper deals with the main theme of the workshop, understanding the impact of selective degradation/preservation of organic matter (OM) in marine sediments on the interpretation of the fossil record. Special attention is paid to (A) the influence of the molecular composition of OM in relation to the biological and physical depositional environment, including new methods for determining complex organic biomolecules, (B) the impact of selective OM preservation on the interpretation of proxies for marine palaeoceanographic and palaeoclimatic reconstruction, and (C) past marine productivity and selective preservation in sediments. It appears that most of the factors influencing OM preservation have been identified, but many of the mechanisms by which they operate are partly, or even fragmentarily, understood. Some factors have not even been taken carefully into consideration. This incomplete understanding of OM breakdown hampers proper assessment of the present and past carbon cycle as well as the interpretation of OM based proxies and proxies affected by OM breakdown. To arrive at better proxy-based reconstructions "deformation functions" are needed, taking into account the transport and diagenesis-related molecular and atomic modifications following proxy formation. Some emerging proxies for OM degradation may shed light on such deformation functions. The use of palynomorph concentrations and selective changes in assemblage composition as models for production and preservation of OM may correct for bias due to selective degradation. Such quantitative assessment of OM degradation may lead to more

  17. GROUNDWATER TRANSPORT OF HYDROPHOBIC ORGANIC COMPOUNDS IN THE PRESENCE OF DISSOLVED ORGANIC MATTER

    EPA Science Inventory

    The effects of dissolved organic matter (DOM) on the transport of hydrophobic organic compounds in soil columns were investigated. Three compounds (naphthalene, phenanthrene and DDT) that spanned three orders of magnitude in water solubility were used. Instead of humic matter, mo...

  18. Interstellar and Solar System Organic Matter Preserved in Interplanetary Dust

    NASA Astrophysics Data System (ADS)

    Messenger, Scott R.; Nakamura-Messenger, Keiko

    2015-08-01

    Interplanetary dust particles (IDPs) collected in the Earth’s stratosphere derive from collisions among asteroids and by the disruption and outgassing of short-period comets. Chondritic porous (CP) IDPs are among the most primitive Solar System materials. CP-IDPs have been linked to cometary parent bodies by their mineralogy, textures, C-content, and dynamical histories. CP-IDPs are fragile, fine-grained (< um) assemblages of anhydrous amorphous and crystalline silicates, oxides and sulfides bound together by abundant carbonaceous material. Ancient silicate, oxide, and SiC stardust grains exhibiting highly anomalous isotopic compositions are abundant in CP-IDPs, constituting 0.01 - 1 % of the mass of the particles. The organic matter in CP-IDPs is isotopically anomalous, with enrichments in D/H reaching 50x the terrestrial SMOW value and 15N/14N ratios up to 3x terrestrial standard compositions. These anomalies are indicative of low T (10-100 K) mass fractionation in cold molecular cloud or the outermost reaches of the protosolar disk. The organic matter shows distinct morphologies, including sub-um globules, bubbly textures, featureless, and with mineral inclusions. Infrared spectroscopy and mass spectrometry studies of organic matter in IDPs reveals diverse species including aliphatic and aromatic compounds. The organic matter with the highest isotopic anomalies appears to be richer in aliphatic compounds. These materials also bear similarities and differences with primitive, isotopically anomalous organic matter in carbonaceous chondrite meteorites. The diversity of the organic chemistry, morphology, and isotopic properties in IDPs and meteorites reflects variable preservation of interstellar/primordial components and Solar System processing. One unifying feature is the presence of sub-um isotopically anomalous organic globules among all primitive materials, including IDPs, meteorites, and comet Wild-2 samples returned by the Stardust mission. We will present

  19. The fate of nitrogen in sediments - can proteinaceous material survive sediment diagenesis?

    SciTech Connect

    Knicker, H.; Hatcher, P.G.

    1996-12-31

    Recent {sup 13}C and {sup 15}N NMR spectroscopic studies of marine sediments indicate that most of the refractory nitrogen derives from selectively preserved recalcitrant residues of algal material (algaenan). {sup 15}N NMR spectra of these materials show that most of the nitrogen (>80 %) is amide-N and free amino-N. The similarity of these spectra with those obtained from fresh algal material suggests that peptide-like structures may be able to survive chemical and biological degradation. Using a new technique of tetramethylammonium hydroxide (TMAH) thermochemolysis, the algaenans, the sediments and bovine albumin are shown to contain products characteristic of proteinaceous materials. This strongly supports the concept that peptide-like structures are surviving sediment diagenesis. We suggest that this survival is, in part, due to encapsulation of proteins into the polymeric network of macromolecular sedimentary organic matter which has previously been shown to exhibit hydrophobic properties.

  20. Compartmental model for organic matter digestion in facultative ponds.

    PubMed

    Giraldo, E; Garzón, A

    2002-01-01

    A model has been developed for the digestion of organic matter in facultative ponds in tropical regions. Complete mixing has been assumed for the aerobic and anaerobic compartments. Settling, aerobic layer oxidation, and anaerobic layer methanogenesis are the main processes for organic matter removal in the water column. Exchange processes between layers are dispersive or soluble exchange, solubilization and transport of organic matter from sediments to water column are also taken into account. Degradation of organic matter in the sediments produces gaseous emissions to the water column. The exchange between bubbles ascending and the water column was measured. The model was calibrated with data obtained from a pilot facultative pond built in Muña Reservoir in Bogotá. The pond was sampled during 4 months to compare data between its water hyacinth covered section and uncovered section. The results clearly show the relative importance of different BOD removal processes in facultative ponds and suggest modifications to further improve performance. The results from the model suggest that internal loadings to facultative ponds due to solubilization and return of organic matter from the sediments to the aerobic layer greatly influence the soluble BOD effluent concentration. Aerobic degradation activity in the facultative pond does not affect significantly the effluent concentration. Anaerobic degradation activity in the facultative pond can more easily achieve increases in the removal efficiencies of BOD. PMID:11833730

  1. Black carbon and organic matter stabilization in soil

    NASA Astrophysics Data System (ADS)

    Lehmann, J.; Liang, B.; Sohi, S.; Gaunt, J.

    2007-12-01

    Interaction with minerals is key to stabilization of organic matter in soils. Stabilization is commonly perceived to occur due to entrapment in pore spaces, encapsulation within aggregates or interaction with mineral surfaces. Typically only interactions between organic matter and minerals are considered in such a model. Here we demonstrate that black carbon may act very similar to minerals in soil in that it enhances the stabilization of organic matter. Mineralization of added organic matter was slower and incorporation into intra-aggregate fractions more rapid in the presence of black carbon. Added double-labeled organic matter was recovered in fractions with high amounts of black carbon. Synchrotron-based near-edge x-ray fine structure (NEXAFS) spectroscopy coupled to scanning transmission x-ray microscopy (STXM) suggested a possible interaction of microorganisms with black carbon surfaces and metabolization of residues. These findings suggest a conceptual model that includes carbon-carbon interactions and by-passing for more rapid stabilization of litter into what is commonly interpreted as stable carbon pools.

  2. Removal of dissolved organic matter by anion exchange: Effect of dissolved organic matter properties

    USGS Publications Warehouse

    Boyer, T.H.; Singer, P.C.; Aiken, G.R.

    2008-01-01

    Ten isolates of aquatic dissolved organic matter (DOM) were evaluated to determine the effect that chemical properties of the DOM, such as charge density, aromaticity, and molecular weight, have on DOM removal by anion exchange. The DOM isolates were characterized asterrestrial, microbial, or intermediate humic substances or transphilic acids. All anion exchange experiments were conducted using a magnetic ion exchange (MIEX) resin. The charge density of the DOM isolates, determined by direct potentiometric titration, was fundamental to quantifying the stoichiometry of the anion exchange mechanism. The results clearly show that all DOM isolates were removed by anion exchange; however, differences among the DOM isolates did influence their removal by MIEX resin. In particular, MIEX resin had the greatest affinity for DOM with high charge density and the least affinity for DOM with low charge density and low aromaticity. This work illustrates that the chemical characteristics of DOM and solution conditions must be considered when evaluating anion exchange treatment for the removal of DOM. ?? 2008 American Chemical Society.

  3. Organic matter on asteroid 130 Elektra

    NASA Technical Reports Server (NTRS)

    Cruikshank, D. P.; Brown, R. H.

    1987-01-01

    Infrared absorption spectra of a low-albedo water-rich asteroid appear to show a weak 3.4-micrometer carbon-hydrogen stretching mode band, which suggests the presence of hydrocarbons on asteroid 130 Elektra. The organic extract from the primitive carbonaceous chondritic Murchison meteorite shows similar spectral bands.

  4. Organic matter in the Saturn system

    NASA Technical Reports Server (NTRS)

    Sagan, C.; Khare, B. N.; Lewis, J. S.

    1984-01-01

    Theoretical and experimental predictions of the formation (and outgassing) of organic molecules in the outer solar system are compared with Voyager IRIS spectral data for the Titan atmosphere. The organic molecules of Titan are of interest because the species and processes within the atmosphere of that moon may have had analogs in the early earth atmosphere 4 Gyr ago. The spacecraft data confirmed the presence of alkanes, ethane, propane, ethylene, alkynes, acetylene, butadiene, methylacetylene, nitriles, hydrogen cyanide, cyanoacetylene, and cyanogen, all heavier than the dominant CH4. Experimental simulation of the effects of UV photolysis, alpha and gamma ray irradiation, electrical discharges and proton and electron bombardment of similar gas mixtures has shown the best promise for modeling the reactions producing the Titan atmosphere chemicals.

  5. Impact of Diagenesis on Biosignature Preservation Potential in Playa Lake Evaporites in Verde Formation, Arizona: Implications for Mars Exploration

    NASA Astrophysics Data System (ADS)

    Shkolyar, S.; Farmer, J. D.

    2015-12-01

    Major priorities for Mars science include assessing the preservation potential and impact of diagenesis on biosignature preservation in aqueous sedimentary environments. We address these priorities with field and lab studies of playa evaporites of the Verde Formation (upper Pliocene) in Arizona. Evaporites studied include bottom-nucleated halite and displacive growth gypsum in magnesite-rich mudstone. These lithotypes are potential analogs for ancient lacustrine habitable environments on Mars. This study aimed to understand organic matter preservation potential under different diagenetic histories. Methods combined outcrop-scale field observations and lab analyses, including: (1) thin-section petrography to understand diagenetic processes and paragenesis; (2) X-ray powder diffraction to obtain bulk mineralogy; (3) Raman spectroscopy to identify and place phases (and kerogenous fossil remains) within a microtextural context; (4) Total Organic Carbon (TOC) analyses to estimate weight percentages of preserved organic carbon for each subfacies endmember; and (5) electron microprobe to create 2D kerogen maps semi-quantifying kerogen preservation in each subfacies. Results revealed complex diagenetic histories for each evaporite subfacies and pathways for organic matter preservation. Secondary gypsum grew displacively within primary playa lake mudstones during early diagenesis. Mudstones then experienced cementation by Mg-carbonates. Displacive-growth gypsum was sometimes dissolved, forming crystal molds. These molds were later either infilled by secondary sulfates or recrystallized to gypsum pseudomorphs with minor phases present (i.e., glauberite). These observations helped define taphonomic models for organic matter preservation in each subfacies. This work has the potential to inform in situ target identification, sampling strategies, and data interpretations for future Mars Sample Return missions (e.g., sample caching strategies for NASA's Mars 2020 mission).

  6. Do soils loose phosphorus with dissolved organic matter?

    NASA Astrophysics Data System (ADS)

    Kaiser, K.; Brödlin, D.; Hagedorn, F.

    2014-12-01

    During ecosystem development and soil formation, primary mineral sources of phosphorus are becoming increasingly depleted. Inorganic phosphorus forms tend to be bound strongly to or within secondary minerals, thus, are hardly available to plants and are not leached from soil. What about organic forms of phosphorus? Since rarely studied, little is known on the composition, mobility, and bioavailability of dissolved organic phosphorus. There is some evidence that plant-derived compounds, such as phytate, bind strongly to minerals as well, while microbial compounds, such as nucleotides and nucleic acids, may represent more mobile fractions of soil phosphorus. In some weakly developed, shallow soils, leaching losses of phosphorus seem to be governed by mobile organic forms. Consequently, much of the phosphorus losses observed during initial stages of ecosystem development may be due to the leaching of dissolved organic matter. However, the potentially mobile microbial compounds are enzymatically hydrolysable. Forest ecosystems on developed soils already depleted in easily available inorganic phosphorus are characterized by rapid recycling of organic phosphors. That can reduce the production of soluble forms of organic phosphorus as well as increase the enzymatic hydrolysis and subsequent plant uptake of phosphorus bound within dissolved organic matter. This work aims at giving an outlook to the potential role of dissolved organic matter in the cycling of phosphorus within developing forest ecosystems, based on literature evidence and first results of ongoing research.

  7. Isotopic composition of hydrogen in insoluble organic matter from cherts

    NASA Technical Reports Server (NTRS)

    Krishnamurthy, R. V.; Epstein, S.

    1991-01-01

    Robert (1989) reported the presence of unusually enriched hydrogen in the insoluble HF-HCl residue extracted from two chert samples of Eocene and Pliocene ages. Since the presence of heavy hydrogen might be due to the incorporation of extraterrestrial materials, we desired to reexamine the same samples to isolate the D-rich components. Our experiments did not reveal any D-rich components, but the hydrogen isotope composition of the insoluble residue of the two chert samples was well within the range expected for terrestrial organic matter. We also describe a protocol that needs to be followed in the hydrogen isotope analysis of any insoluble organic matter.

  8. Detection of organic matter in interstellar grains.

    PubMed

    Pendleton, Y J

    1997-06-01

    Star formation and the subsequent evolution of planetary systems occurs in dense molecular clouds, which are comprised, in part, of interstellar dust grains gathered from the diffuse interstellar medium (DISM). Radio observations of the interstellar medium reveal the presence of organic molecules in the gas phase and infrared observational studies provide details concerning the solid-state features in dust grains. In particular, a series of absorption bands have been observed near 3.4 microns (approximately 2940 cm-1) towards bright infrared objects which are seen through large column densities of interstellar dust. Comparisons of organic residues, produced under a variety of laboratory conditions, to the diffuse interstellar medium observations have shown that aliphatic hydrocarbon grains are responsible for the spectral absorption features observed near 3.4 microns (approximately 2940 cm-1). These hydrocarbons appear to carry the -CH2- and -CH3 functional groups in the abundance ratio CH2/CH3 approximately 2.5, and the amount of carbon tied up in this component is greater than 4% of the cosmic carbon available. On a galactic scale, the strength of the 3.4 microns band does not scale linearly with visual extinction, but instead increases more rapidly for objects near the Galactic Center. A similar trend is noted in the strength of the Si-O absorption band near 9.7 microns. The similar behavior of the C-H and Si-O stretching bands suggests that these two components may be coupled, perhaps in the form of grains with silicate cores and refractory organic mantles. The ubiquity of the hydrocarbon features seen in the near infrared near 3.4 microns throughout out Galaxy and in other galaxies demonstrates the widespread availability of such material for incorporation into the many newly forming planetary systems. The similarity of the 3.4 microns features in any organic material with aliphatic hydrocarbons underscores the need for complete astronomical observational

  9. Andic soils : mineralogical effect onto organic matter dynamics, organic matter effect onto mineral dynamics, or both?

    NASA Astrophysics Data System (ADS)

    Basile-Doelsch, Isabelle; Amundson, Ronald; Balesdent, Jérome; Borschneck, Daniel; Bottero, Jean-Yves; Colin, Fabrice; de Junet, Alexis; Doelsch, Emmanuel; Legros, Samuel; Levard, Clément; Masion, Armand; Meunier, Jean-Dominique; Rose, Jérôme

    2014-05-01

    From a strictly mineralogical point of view, weathering of volcanic glass produces secondary phases that are short range ordered alumino-silicates (SRO-AlSi). These are imogolite tubes (2 to 3 nm of diameter) and allophane supposedly spheres (3.5 to 5 nm). Their local structure is composed of a curved gibbsite Al layer and Si tetrahedra in the vacancies (Q0). Proto-imogolites have the same local structure but are roof-shape nanoparticles likely representing the precursors of imogolite and allophanes (Levard et al. 2010). These structures and sizes give to the SRO-AlSi large specific surfaces and high reactivities. In some natural sites, imogolites and allophanes are formed in large quantities. Aging of these phases may lead to the formation of more stable minerals (halloysite, kaolinite and gibbsite) (Torn et al 1997). In natural environments, when the weathering of volcanic glass is associated with the establishment of vegetation, the soils formed are generally andosols. These soils are particularly rich in organic matter (OM), which is explained by the high ability of SRO-AlSi mineral phases to form bonds with organic compounds. In a first order "bulk" approach, it is considered that these bonds strongly stabilize the organic compounds as their mean age can reach more than 10 kyrs in some studied sites (Basile-Doelsch et al. 2005; Torn et al. 1997). However, the structure of the mineral phases present in andosols deserves more attention. Traditionally, the presence in the SRO-AlSi andosols was shown by selective dissolution approaches by oxalate and pyrophosphate. Using spectroscopic methods, mineralogical analysis of SRO-AlSi in andosols samples showed that these mineral phases were neither imogolites nor allophanes as originally supposed, but only less organized structures remained in a state of proto-imogolites (Basile-Doelsch al. 2005 ; Levard et al., 2012). The presence of OM would have an inhibitory effect on the formation of secondary mineral phases, by

  10. Composition of dissolved organic matter in groundwater

    NASA Astrophysics Data System (ADS)

    Longnecker, Krista; Kujawinski, Elizabeth B.

    2011-05-01

    Groundwater constitutes a globally important source of freshwater for drinking water and other agricultural and industrial purposes, and is a prominent source of freshwater flowing into the coastal ocean. Therefore, understanding the chemical components of groundwater is relevant to both coastal and inland communities. We used electrospray ionization coupled with Fourier-transform ion cyclotron resonance mass spectrometry (ESI FT-ICR MS) to examine dissolved organic compounds in groundwater prior to and after passage through a sediment-filled column containing microorganisms. The data revealed that an unexpectedly high proportion of organic compounds contained nitrogen and sulfur, possibly due to transport of surface waters from septic systems and rain events. We matched 292 chemical features, based on measured mass:charge ( m/z) values, to compounds stored in the Kyoto Encyclopedia of Genes and Genomes (KEGG). A subset of these compounds (88) had only one structural isomer in KEGG, thus supporting tentative identification. Most identified elemental formulas were linked with metabolic pathways that produce polyketides or with secondary metabolites produced by plants. The presence of polyketides in groundwater is notable because of their anti-bacterial and anti-cancer properties. However, their relative abundance must be quantified with appropriate analyses to assess any implications for public health.

  11. Interstellar and Solar System Organic Matter Preserved in Interplanetary Dust

    NASA Technical Reports Server (NTRS)

    Messenger, Scott; Nakamura-Messenger, Keiko

    2015-01-01

    Interplanetary dust particles (IDPs) collected in the Earth's stratosphere derive from collisions among asteroids and by the disruption and outgassing of short-period comets. Chondritic porous (CP) IDPs are among the most primitive Solar System materials. CP-IDPs have been linked to cometary parent bodies by their mineralogy, textures, C-content, and dynamical histories. CP-IDPs are fragile, fine-grained (less than um) assemblages of anhydrous amorphous and crystalline silicates, oxides and sulfides bound together by abundant carbonaceous material. Ancient silicate, oxide, and SiC stardust grains exhibiting highly anomalous isotopic compositions are abundant in CP-IDPs, constituting 0.01 - 1 % of the mass of the particles. The organic matter in CP-IDPs is isotopically anomalous, with enrichments in D/H reaching 50x the terrestrial SMOW value and 15N/14N ratios up to 3x terrestrial standard compositions. These anomalies are indicative of low T (10-100 K) mass fractionation in cold molecular cloud or the outermost reaches of the protosolar disk. The organic matter shows distinct morphologies, including sub-um globules, bubbly textures, featureless, and with mineral inclusions. Infrared spectroscopy and mass spectrometry studies of organic matter in IDPs reveals diverse species including aliphatic and aromatic compounds. The organic matter with the highest isotopic anomalies appears to be richer in aliphatic compounds. These materials also bear similarities and differences with primitive, isotopically anomalous organic matter in carbonaceous chondrite meteorites. The diversity of the organic chemistry, morphology, and isotopic properties in IDPs and meteorites reflects variable preservation of interstellar/primordial components and Solar System processing. One unifying feature is the presence of sub-um isotopically anomalous organic globules among all primitive materials, including IDPs, meteorites, and comet Wild-2 samples returned by the Stardust mission.

  12. Caracterisation of anthropogenic contribution to the coastal fluorescent organic matter

    NASA Astrophysics Data System (ADS)

    El Nahhal, Ibrahim; Nouhi, Ayoub; Mounier, Stéphane

    2015-04-01

    It is known that most of the coastal fluorescent organic matter is of a terrestrial origin (Parlanti, 2000; Tedetti, Guigue, & Goutx, 2010). However, the contribution of the anthropogenic organic matter to this pool is not well defined and evaluated. In this work the monitoring of little bay (Toulon Bay, France) was done in the way to determine the organic fluorescent response during a winter period. The sampling campaign consisted of different days during the month of December, 2014 ( 12th, 15th, 17th, 19th) on 21 different sampling sites for the fluorescence measurements (without any filtering of the samples) and the whole month of December for the bacterial and the turbidity measurements. Excitation Emission Matrices (EEMs) of fluorescence (from 200 to 400 nm and 220 to 420 nm excitation and emission range) were treated by parallel factor analysis (PARAFAC).The parafac analysis of the EEM datasets was conducted using PROGMEEF software in Matlab langage. On the same time that the turbidity and bacterial measurement (particularly the E.Coli concentration) were determined. The results gives in a short time range, information on the the contribution of the anthropogenic inputs to the coastal fluorescent organic matter. In addition, the effect of salinity on the photochemical degradation of the anthropogenic organic matter (especially those from wastewater treatment plants) will be studied to investigate their fate in the water end member by the way of laboratory experiments. Parlanti, E. (2000). Dissolved organic matter fluorescence spectroscopy as a tool to estimate biological activity in a coastal zone submitted to anthropogenic inputs. Organic Geochemistry, 31(12), 1765-1781. doi:10.1016/S0146-6380(00)00124-8 Tedetti, M., Guigue, C., & Goutx, M. (2010). Utilization of a submersible UV fluorometer for monitoring anthropogenic inputs in the Mediterranean coastal waters. Marine Pollution Bulletin, 60(3), 350-62. doi:10.1016/j.marpolbul.2009.10.018

  13. A marine sink for chlorine in natural organic matter

    NASA Astrophysics Data System (ADS)

    Leri, Alessandra C.; Mayer, Lawrence M.; Thornton, Kathleen R.; Northrup, Paul A.; Dunigan, Marisa R.; Ness, Katherine J.; Gellis, Austin B.

    2015-08-01

    Chloride--the most abundant ion in sea water--affects ocean salinity, and thereby seawater density and ocean circulation. Its lack of reactivity gives it an extremely long residence time. Other halogens are known to be incorporated into marine organic matter. However, evidence of similar transformations of seawater chloride is lacking, aside from emissions of volatile organochlorine by marine algae. Here we report high organochlorine concentrations from 180 to 700 mg kg-1 in natural particulate organic matter that settled into sediment traps at depths between 800 and 3,200 m in the Arabian Sea, taken between 1994 and 1995. X-ray spectromicroscopic imaging of chlorine bonding reveals that this organochlorine exists primarily in concentrated aliphatic forms consistent with lipid chlorination, along with a more diffuse aromatic fraction. High aliphatic organochlorine in particulate material from cultured phytoplankton suggests that primary production is a source of chlorinated organic matter. We also found that particulate algal detritus can act as an organic substrate for abiotic reactions involving Fe2+, H2O2 or light that incorporate chlorine into organic matter at levels up to several grams per kilogram. We conclude that transformations of marine chloride to non-volatile organochlorine through biological and abiotic pathways represent an oceanic sink for this relatively unreactive element.

  14. Adsorption combined with ultrafiltration to remove organic matter from seawater.

    PubMed

    Tansakul, Chatkaew; Laborie, Stéphanie; Cabassud, Corinne

    2011-12-01

    Organic fouling and biofouling are the major severe types of fouling of reverse osmosis (RO) membranes in seawater (SW) desalination. Low pressure membrane filtration such as ultrafiltration (UF) has been developed as a pre-treatment before reverse osmosis. However, UF alone may not be an effective enough pre-treatment because of the existence of low-molecular weight dissolved organic matter in seawater. Therefore, the objective of the present work is to study a hybrid process, powdered activated carbon (PAC) adsorption/UF, with real seawater and to evaluate its performance in terms of organic matter removal and membrane fouling. The effect of different PAC types and concentrations is evaluated. Stream-activated wood-based PAC addition increased marine organic matter removal by up to 70% in some conditions. Moreover, coupling PAC adsorption with UF decreased UF membrane fouling and the fouling occurring during short-term UF was totally reversible. It can be concluded that the hybrid PAC adsorption/UF process performed in crossflow filtration mode is a relevant pre-treatment process before RO desalination, allowing organic matter removal of 75% and showing no flux decline for short-term experiments. PMID:21996607

  15. Nickel as indicator of fresh organic matter in upwelling sediments

    NASA Astrophysics Data System (ADS)

    Böning, Philipp; Shaw, Tim; Pahnke, Katharina; Brumsack, Hans-Jürgen

    2015-08-01

    Trace metals involved in biological cycling (e.g. Cd, Cu, Ni, Zn) typically accumulate in upwelling sediments due to a high productivity-related particle flux and an enhanced preservation at depth. However, poor constraint on the contribution of lithogenic metal fraction, early diagenetic transformation processes and anthropogenic metal inputs may complicate sediment metal signatures. The identification of source and accumulation mechanisms is essential to the validation of these metals as productivity proxies. Here we combine data from various short cores (upper 50 cm) and two longer cores of organic-rich upwelling sediments (Peru, Namibia, Chile and Gulf of California), which suggest a highly significant, linear and uniform relationship between Ni and total organic carbon (TOC). The overall high Ni enrichment may be explained by the occurrence of diatoms, which dominate productivity in these systems. The Peru surface sediments (upper 2 cm) show a less pronounced Ni-TOC relationship and support a transition between lower Ni/TOC ratio of East Pacific water column particles and the higher Ni/TOC ratio observed in deeper sediments. In Peru surface sediments, the process is confirmed as a stoichiometric relation between Ni and total chlorins (the immediate degradation products of chlorophyll pigments), which is not observed for Cu or Zn. Our data strongly support previous findings that Ni is a clear (if not the best) indicator of the organic sinking flux. This is also due to the fact that Ni signatures undergo less alteration associated with sulfur and manganese cycling and low contribution from anthropogenic sources. The apparently exclusive Ni-chlorin stoichiometry suggests that Ni may be associated with enzymes that are involved in photoautotrophic production, which underlines the previous finding from laboratory experiments and field work that diatoms have a dominant role in marine Ni cycling. The Ni/chlorin ratio increases with increasing sediment depth

  16. Processing of Atmospheric Organic Matter by California Radiation Fogs

    NASA Astrophysics Data System (ADS)

    Collett, J. L.; Youngster, S. B.; Lee, T.; Chang, H.; Herckes, P.

    2005-12-01

    In many environments, organic compounds account for a significant fraction of fine particle mass. Because the lifetimes of accumulation mode aerosol particles are governed largely by interactions with clouds, it is important to understand how organic aerosol particles are processed by clouds and fogs. Recently we have examined the organic composition of radiation fogs in central California as well as how these fogs process organic aerosol particles and soluble organic trace gases. Observations indicate that organic matter is a significant component of the fog droplets, comprising approximately one-third of the total solute mass concentration. Concentrations of total organic carbon (TOC) range from approximately 2 to 41 ppmC. Approximately three-fourths of organic matter is typically found in solution as dissolved organic carbon (DOC). A variety of efforts have been made to characterize the composition of the fog organic matter, including analyses by GC/MS, HPLC, IC, NMR and IR. The most abundant species are typically low molecular weight carboxylic acids, small carbonyls and dicarbonyls, and sugar anhydrides. These species have been observed collectively to account for roughly 20-30 percent of the fog DOC. Dicarboxylic acids, frequently used as model compounds for organic CCN, typically account for only a few percent of the organic carbon, with oxalic acid the most important contributor. A significant portion of the fog DOC appears to be comprised of high molecular weight compounds (> 500 Da). Analyses also reveal the presence of organic molecular markers associated with particles produced by various combustion processes. Comparisons of pre-fog and interstitial aerosol samples reveal differences in the relative particle scavenging efficiencies of the fog drops between organic and elemental carbon and between different types of organic carbon. Measurements using a two-stage fog water collector reveal that organic matter tends to be enriched in smaller fog droplets

  17. Analysis of the Organic Matter in Interplanetary Dust Particles: Clues to the Organic Matter in Comets, Asteroids, and Interstellar Grains

    NASA Technical Reports Server (NTRS)

    Flynn, G. J.; Keller, L. P.

    2003-01-01

    Reflection spectroscopy suggests the C- , P-, and D-types of asteroids contain abundant carbon, but these Vis-nearIR spectra are featureless, providing no information on the type(s) of carbonaceous matter. Infrared spectroscopy demonstrates that organic carbon is a significant component in comets and as grains or grain coatings in the interstellar medium. Most of the interplanetary dust particles (IDPs) recovered from the Earth s stratosphere are believed to be fragments from asteroids or comets, thus characterization of the carbon in IDPs provides the opportunity to determine the type(s) and abundance of organic matter in asteroids and comets. Some IDPs exhibit isotopic excesses of D and N-15, indicating the presence of interstellar material. The characterization of the carbon in these IDPs, and particularly any carbon spatially associated with the isotopic anomalies, provides the opportunity to characterize interstellar organic matter.

  18. Aggregation of organic matter by pelagic tunicates

    SciTech Connect

    Pomeroy, L.R.; Deibel, D.

    1980-07-01

    Three genera of pelagic tunicates were fed concentrates of natural seston and an axenic diatom culture. Fresh and up to 4-day-old feces resemble flocculent organic aggregates containing populations of microorganisms, as described from highly productive parts of the ocean, and older feces resemble the nearly sterile flocculent aggregates which are ubiquitous in surface waters. Fresh feces consist of partially digested phytoplankton and other inclusions in an amorphous gelatinous matrix. After 18 to 36 h, a population of large bacteria develops in the matrix and in some of the remains of phytoplankton contained in the feces. From 48 to 96 h, protozoan populations arise which consume the bacteria and sometimes the remains of the phytoplankton in the feces. Thereafter only a sparse population of microorganisms remains, and the particles begin to fragment. Water samples taken in or below dense populations of salps and doliolids contained greater numbers of flocculent aggregates than did samples from adjacent stations.

  19. Search for Organic Matter in Leonid Meteoroids

    NASA Technical Reports Server (NTRS)

    Rairden, Richard L.; Jenniskens, Peter; Laux, Christophe O.; DeVincenzi, Donald L. (Technical Monitor)

    2000-01-01

    Near-ultraviolet 300-410 nm spectra of Leonid meteors were obtained in an effort to measure the strong B to X emission band of the radical CN in Leonid meteor spectra at 387 nm. CN is an expected product of ablation of nitrogen containing organic carbon in the meteoroids as well as a possible product of the aerothermochemistry induced by the kinetic energy of the meteor. A slitless spectrograph with objective grating was deployed on FISTA during the 1999 Leonid Multi-Instrument Aircraft Campaign. Fifteen first-order UV spectra were captured near the 02:00 UT meteor storm peak on November 18. It is found that neutral iron lines dominate the spectrum, with no clear sign of the CN band. The meteor plasma contains less than one CN molecule per three Fe atoms at the observed altitude of about 100 km.

  20. Ultrathin organic semiconductor films--soft matter effect.

    PubMed

    Wang, Tong; Yan, Donghang

    2014-05-01

    The growth of organic semiconductor thin films has been a crucial issue in organic electronics, especially the growth at the early stages. The thin-film phase has been found to be a common phenomenon in many organic semiconductor thin films, which is closely related with the weak van der Waals interaction between organic molecules, the long-range interaction between organic molecules and the substrate, as well as the soft matter characteristics of ultrathin films. The growth behavior and soft matter characteristics of the thin-film phase have great effects on thin film morphology and structure, for example, the formation and coalescence of grain boundaries, which further influences the performance of organic electronic devices. The understanding of thin-film phase and its intrinsic quality is necessary for fabricating large-size, highly ordered, continuous and defect-free ultrathin films. This review will focus on the growth behavior of organic ultrathin films, i.e., the level of the first several molecular layers, and provide an overview of the soft matter characteristics. PMID:24548597

  1. Bromination of marine particulate organic matter through oxidative mechanisms

    NASA Astrophysics Data System (ADS)

    Leri, Alessandra C.; Mayer, Lawrence M.; Thornton, Kathleen R.; Ravel, Bruce

    2014-10-01

    Although bromine (Br) is considered conservative in seawater, it exhibits a well established correlation with organic carbon in marine sediments. This carbon-bromine association was recently attributed to covalent bonding, with organobromine in sinking particulates providing a putative link between sedimentary organobromine and organic matter cycling in surface waters. We hypothesized that phytoplankton detritus, a major precursor of sedimentary organic matter, would be susceptible to bromination through oxidative attack. Through a series of model experiments, we demonstrate incorporation of Br into algal particulate detritus through peroxidative and photochemical mechanisms. Peroxidative bromination was enhanced by addition of exogenous bromoperoxidase, but the enzyme was not required for the reaction. Fenton-like reaction conditions also promoted bromination, especially under solar irradiation, implicating radical mechanisms in the euphotic zone as another abiotic source of brominated particulates. These reactions produced aliphatic and aromatic forms of organobromine, suggesting that lipid- and protein-rich components of algal membranes provide suitable substrates for bromination. Biogenic organobromines in certain genera of phytoplankton also appeared in both aliphatic and aromatic forms. Experimental evidence and samples from oceanic midwater sediment traps imply that the aromatic fraction is more stable than the aliphatic. These experiments establish Br as a versatile oxidant in the transformation of planktonic organic matter through both enzymatic and abiotic mechanisms. Organobromine may serve as a marker of oxidative breakdown of marine organic detritus, with the metastable component providing a short-lived indicator of early-stage oxidation. By altering the stability of aliphatic and aromatic moieties, bromination may affect the availability of organic matter to organisms, with consequences for the preservation and degradation of marine organic carbon.

  2. The Relationship Between Dissolved Organic Matter Composition and Organic Matter Optical Properties in Freshwaters

    NASA Astrophysics Data System (ADS)

    Aiken, G.; Spencer, R. G.; Butler, K.

    2010-12-01

    Dissolved organic matter (DOM) chemistry and flux are potentially useful, albeit, underutilized, indicators of watershed characteristics, climate influences on watershed hydrology and soils, and changes associated with resource management. Source materials, watershed geochemistry, oxidative processes and hydrology exert strong influences on the nature and reactivity of DOM in aquatic systems. The molecules that comprise DOM, in turn, control a number of environmental processes important for ecosystem function including light penetration and photochemistry, microbial activity, mineral dissolution/precipitation, and the transport and reactivity of hydrophobic compounds and metals (e.g. Hg). In particular, aromatic molecules derived from higher plants exert strong controls on aquatic photochemistry, and on the transport and biogeochemistry of metals. Assessment of DOM composition and transport, therefore, can provide a basis for understanding watershed processes and biogeochemistry of rivers and streams. Here we present results of multi-year studies designed to assess the seasonal and spatial variability of DOM quantity and quality for 57 North American Rivers. DOM concentrations and composition, based on DOM fractionation on XAD resins, ultraviolet (UV)/visible absorption and fluorescence spectroscopic analyses, and specific compound analyses, varied greatly both between sites and seasonally within a given site. DOM in these rivers exhibited a wide range of concentration (<80 to >4000 µM C* L-1) and specific ultra-violet absorbance at 254 nm (SUVA254) (0.6 to 5 L *mg C-1 *m-1), an optical measurement that is an indicator of aromatic carbon content. In almost all systems, UV absorbance measured at specific wavelengths (e.g. 254 nm) correlated strongly with DOM and hydrophobic organic acid (HPOA) content (aquatic humic substances). The relationships between dissolved organic carbon (DOC) concentration and absorbance for the range of systems were quite variable due to

  3. Lyophilization and Reconstitution of Reverse Osmosis Concentrated Natural Organic Matter

    EPA Science Inventory

    Disinfection by-product (DBP) research can be complicated by difficulties in shipping large water quantities and changing natural organic matter (NOM) characteristics over time. To overcome these issues, it is advantageous to have a reliable method for concentrating and preservin...

  4. Forms and Bioavailability of Phosphorus Associated With Natural Organic Matter

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Natural organic matter (NOM) is an important ingredient in soil which can improve physical, chemical, and biological properties of soils and nutrient supplies. In this study, we investigated the spectral features and potential availability of phosphorus (P) in the IHSS Elliott Soil humic acid standa...

  5. Organic Matter Balance: Managing for Soil Protection and Bioenergy Production

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soils are an important natural resource allowing the production of food, feed, fiber and fuel. The growing demand for these services or products requires we protect the soil resource. Many characteristics of high quality soils can be related to the quantity and quality of soil organic matter (organi...

  6. Relating Soil Organic Matter Dynamics to its Molecular Structure

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Our understanding of the dynamics of soil organic matter (SOM) must be integrated with a sound knowledge of it biochemical complexity. The molecular structure of SOM was determined in 98% sand soils to eliminate the known protective effects of clay on the amount and turnover rate of the SOM constitu...

  7. Calculation of the enthalpy of formation of coal organic matter

    SciTech Connect

    A.M. Gyul'maliev; M.Ya. Shpirt

    2008-10-15

    The enthalpy of formation for the organic matter of coals in the coal rank series was calculated from the heat of the complete combustion reaction. Three variants were considered in which the experimental heating values and the values found from the correlation equation or calculated using the Mendeleev formula were taken as the heat of the complete combustion of coals.

  8. SOURCES OF FINE PARTICLE ORGANIC MATTER IN BOISE

    EPA Science Inventory

    Ambient concentrations of fine particle extracted organic matter (EOM) measured at the Elm Grove Park and Fire Station sites in Boise have been apportioned to their two principal sources, woodsmoke and motor vehicle emissions. A multiple linear regression method using lead and po...

  9. Organic matter in a coal ball: Peat or coal?

    USGS Publications Warehouse

    Hatcher, P.G.; Lyons, P.C.; Thompson, C.L.; Brown, F.W.; Maciel, G.E.

    1982-01-01

    Chemical analyses of morphologically preserved organic matter in a Carboniferous coal ball reveal that the material is coalified to a rank approximately equal to that of the surrounding coal. Hence, the plant tissues in the coal ball were chemically altered by coalification processes and were not preserved as peat. Copyright ?? 1982 AAAS.

  10. Photoproduction of Carbon Monoxide from Natural Organic Matter

    EPA Science Inventory

    Pioneering studies by Valentine provided early kinetic results that used carbon monoxide (CO) production to evaluate the photodecomposition of aquatic natural organic matter (NOM) . (ES&T 1993 27 409-412). Comparatively few kinetic studies have been conducted of the photodegradat...

  11. Quenching and Sensitizing Fullerene Photoreactions by Natural Organic Matter

    EPA Science Inventory

    Effects of natural organic matter (NOM) on the photoreaction kinetics of fullerenes (i.e., C60 and fullerenol) were investigated using simulated sunlight and monochromatic radiation (365 nm). NOM from several sources quenched (slowed) the photoreaction of C60 aggregates in water ...

  12. Protection of Organic Matter from Enzyme Degradation by Mineral Mesopores

    NASA Astrophysics Data System (ADS)

    Zimmerman, A. R.; Chorover, J. D.; Brantley, S. L.

    2003-12-01

    Mineral mesopores (2-50 nm diameter) may sequester organic matter (natural and pollutant) and protect it from microbial and fungal enzymatic degradation in soils and sediments. Synthetic mesoporous alumina and silica minerals with uniform pore sizes and shapes were used to test the role of mesopores in protecting organic matter from enzymatic degradation. A model humic compound, L-3-4-dihydroxyphenylalanine (L-DOPA), was sorbed to the internal surfaces of mesoporous alumina (8.2 nm diameter pores) and mesoporous silica (3.4 nm diameter pores) as well as to the external surfaces of nonporous alumina and silica analogues. A fungal derived enzyme, laccase, was added to these sorbate-sorbent pairs in aqueous solution and activity was monitored by oxygen consumption. Though enzyme activity was suppressed in both cases by mineral-enzyme interaction (enzyme inhibition likely due to adsorption of the enzyme), both the rate and total extent of enzyme-mediated degradation of mesopore-sorbed L-DOPA was 3-40 times lower than that of the externally-sorbed analogue. These results provide, for the first time, direct evidence for the viability of the proposed mesopore protection mechanism for the sequestration and preservation of sedimentary organic matter and organic contaminants. Mesopore adsorption/desorption phenomena may also help explain the slow degradation of organic contaminants in soil and sediment and may prove useful as delivery vehicles for organic compounds to agricultural, medical or environmental systems.

  13. CHROMOPHORIC DISSOLVED ORGANIC MATTER (CDOM) DERIVED FROM DECOMPOSITION OF VARIOUS VASCULAR PLANT AND ALGAL SOURCES

    EPA Science Inventory

    Chromophoric dissolved organic (CDOM) in aquatic environments is derived from the microbial decomposition of terrestrial and microbial organic matter. Here we present results of studies of the spectral properties and photoreactivity of the CDOM derived from several organic matter...

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

    EPA Science Inventory

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

  15. Molecular characterization of soil organic matter: a historic overview

    NASA Astrophysics Data System (ADS)

    Kögel-Knabner, Ingrid; Rumpel, Cornelia

    2014-05-01

    The characterization of individual molecular components of soil organic matter started in the early 19th century, but proceeded slowly. The major focus at this time was on the isolation and differentiation of different humic and fulvic acid fractions, which were considered to have a defined chemical composition and structure. The isolation and structural anlysis of specific individual soil organic matter components became more popular in the early 20th century. In 1936 40 different individual compounds had been isolated and a specific chemical strucutre had been attributed. These structural attributions were confirmed later for some, but not all of these individual compounds. In the 1950 much more individual compounds could be isolated and characterized, using complicated and time consuming chromatography. It became obvious that soil also contains a number of compounds of microbial origin, such as e.g., amino sugars and lipids. With the improvement of chrmoatographic separation techniques and the use of gas chromatography in combination with thin layerchromatography in the 1960 hundreds of individual compounds have been isolated and identified, most of them after chemical degradation of humic or fulvic acids. The chemical degradative techniques were amended with analytical pyrolysis in the 1970s. More and more, bulk soil organic matter was analyzed with these techniques and the advent of solid-stae 13C NMR spectroscopy around the 1980s allowed for the characterization of the composition of bulk soil organic matter. The gas chromatographic separation of organic matter can nowadays be combined with specific detectors, such that specific attributes ofindividual molecules can be analyzed, e.g. the radiocarbon content or the stable isotope composition.

  16. Cumulative effects of biochar, mineral and organic fertilizers on soil organic matter

    NASA Astrophysics Data System (ADS)

    Plaza, César; López-de-Sá, Esther G.; Gascó, Gabriel; Méndez, Ana; Zaccone, Claudio

    2016-04-01

    We investigated the effect of three consecutive annual applications of biochar at rates of 0 and 20 t ha-1, in a factorial combination with a mineral fertilizer (NPK and nitrosulfate) and two types of organic amendment (municipal solid waste compost and sewage sludge), on soil organic matter in a field experiment under Mediterranean conditions. Biochar increased significantly soil organic C content and C/N ratio. In biochar-amended soils, soil organic C increased significantly with the addition of municipal solid waste compost and sewage sludge. To capture organic matter protection mechanisms related to aggregation and mineral interaction, the soil samples will be fractionated into free (unprotected), intra-macroaggregate, intra-microaggregate, and mineral-associated organic matter pools, and the isolated fractions will be subjected to further chemical and spectroscopic analysis.

  17. Impact of stylolitization on diagenesis of a Lower Cretaceous carbonate reservoir from a giant oilfield, Abu Dhabi, United Arab Emirates

    NASA Astrophysics Data System (ADS)

    Paganoni, Matteo; Al Harthi, Amena; Morad, Daniel; Morad, Sadoon; Ceriani, Andrea; Mansurbeg, Howri; Al Suwaidi, Aisha; Al-Aasm, Ihsan S.; Ehrenberg, Stephen N.; Sirat, Manhal

    2016-04-01

    Bed-parallel stylolites are a widespread diagenetic feature in Lower Cretaceous limestone reservoirs, Abu Dhabi, United Arab Emirates (UAE). Diagenetic calcite, dolomite, kaolin and small amounts of pyrite, fluorite, anhydrite and sphalerite occur along and in the vicinity of the stylolites. Petrographic observations, negative δ18OVPDB, fluid inclusion microthermometry, and enrichment in 87Sr suggest that these cements have precipitated from hot basinal brines, which migrated along the stylolites and genetically related microfractures (tension gashes). Fluid migration was presumably related to lateral tectonic compression events related to the foreland basin formation. The low solubility of Al3 + in formation waters suggests that kaolin precipitation was linked to derivation of organic acids during organic matter maturation, probably in siliciclastic source rocks. The mass released from stylolitization was presumably re-precipitated as macro- and microcrystalline calcite cement in the host limestones. The flanks of the oilfield (water zone) display more frequent presence and higher amplitude of stylolites, lower porosity and permeability, higher homogenization temperatures and more radiogenic composition of carbonates compared to the crest (oil zone). This indicates that oil emplacement retards diagenesis. This study demonstrates that stylolitization plays a crucial role in fluid flow and diagenesis of carbonate reservoirs during basin evolution.

  18. Bacterial biomarkers thermally released from dissolved organic matter

    USGS Publications Warehouse

    Greenwood, P.F.; Leenheer, J.A.; McIntyre, C.; Berwick, L.; Franzmann, P.D.

    2006-01-01

    Hopane biomarker products were detected using microscale sealed vessel (MSSV) pyrolysis gas chromatography-mass spectrometry (GC-MS) analysis of dissolved organic matter from natural aquatic systems colonised by bacterial populations. MSSV pyrolysis can reduce the polyhydroxylated alkyl side chain of bacteriohopanepolyols, yielding saturated hopane products which are more amenable to GC-MS detection than their functionalised precursors. This example demonstrates how the thermal conditions of MSSV pyrolysis can reduce the biologically-inherited structural functionality of naturally occurring organic matter such that additional structural fragments can be detected using GC methods. This approach complements traditional analytical pyrolysis methods by providing additional speciation information useful for establishing the structures and source inputs of recent or extant organic material. ?? 2006.

  19. Pre-biotic organic matter from comets and asteroids

    NASA Technical Reports Server (NTRS)

    Anders, Edward

    1989-01-01

    Only meteoritic fragments small enough to be gently decelerated by the atmosphere (10 to the -12th g to 10 to the -6th g) can deliver organic matter intact. The amount of such 'soft-landed' organic carbon can be estimated from data for the infall rate of meteoritic matter. At present rates, only about 0.0006 g/sq cm intact organic carbon would accumulate in 100 million years, but at the higher rates of about four billion yr ago, about 20 g/sq cm may have accumulated in the few hundred million years between the last cataclysmic impact and the beginning of life. It may have included some biologically important compounds that did not form by abiotic synthesis on earth.

  20. An Investigation Into the Molecular and Isotopic Composition of Diatom Frustule-Bound Organic Matter: Method Development for New Proxies

    NASA Astrophysics Data System (ADS)

    Bridoux, M. C.; Ingalls, A. E.

    2009-12-01

    Diatoms are single cell phytoplankton that are ubiquitous in marine ecosystems and are responsible for up to 40% of the carbon fixed annually in the ocean. Their intricately nanopatterned siliceous frustules are formed under the control of template organic molecules, some of which are incorporated into the frustule during growth. Several diatom frustule-based paleoproxies have been developed to exploit these microfossils because they are from a known phytoplankton source that is relatively unaltered from diagenesis. Among these proxies, diatom frustule-bound organic matter (OM) is recognized as a potentially important material for use in paleoreconstructions of past productivity (13C/12C), nutrient utilization (15N/14N) as well as to determine the radiocarbon age of sedimentary frustules (Δ14C). Despite numerous advances, diatom frustule-bound OM remains poorly characterized. Here we focus on the chemical characterization of diatom frustule-bound OM with the goal of developing molecular and compound-specific isotope methods to better reconstruct the past environments of diatom rich regions such as the Southern Ocean and the North Pacific. To do this, we 1) chemically cleaned diatom frustules, 2) dissolve them in HF to release organic compounds embedded in the frustules and 3) unambiguously characterized this organic matter by ion pairing reversed phase liquid chromatography coupled to diode array, electrospray ionization - ion trap mass spectrometry (ESI/IT-MSn) and accurate mass quadrupole time of flight mass spectrometry (Q-TOF). These analyses reveal the presence of low molecular weight, UV light absorbing compounds called mycosporine-like amino acids (MAAs) and a series of long chain polyamines (LCPAs) consisting of N-methylated derivatives of polypropyleneimine units attached to putrescine. LCPAs are known to direct silicification, while MAAs are thought to provide sunscreen to many marine organisms. The presence of these specific biomarkers in sediment

  1. Evalution of soil organic matter contents using spectral inhance indeces

    NASA Astrophysics Data System (ADS)

    Faghih, Athar; Heidari, Ahmad

    2010-05-01

    Topography composed of elevation, slope, and aspect, that through the influence microclimate and chemical and physical properties of land affects the amount of organic carbon. Because of the height difference between hydrology and temperature regime in mountainous regions are collaborating and that difference has led to differences in the composition and distribution patterns of vegetation, the soil and organic matter decomposition rate is. Effect of climate change on soil organic carbon storage and its distribution is different in different regions, and the main factors creating differences, temperature and rainfall levels are on the order and the growth rate plant species and organic carbon mineralization rate impact.to evaluate these factors first ETM+ satellite images of 2002 North range lands, Karaj river basin prepared, then image processing and image classification as supervision and unsupervision was done. Then NDVI, TNDVI, VI, IR/R, Square IR/R indices obtained for study area and on the basis of these indices study area units was specified. Digital elevation model (DEM) using the region as a 1:50000 topographic map was produced before. Using Arc- GIS image and maps physiographic, location sampling based physiographic units changes and temperature change with the opposite slope directions sample have been made. By using GPS, 24 positions for surface samples and 4 pedons determined and sampled. Physical and chemical sample properties have based on size and by using dry sieve and OC, N and C/N ratio respectively specified in them. Then, using Exel software existing relationships between different parameters were studied. The results showed that, with increases. In the slope of the north and west due to the ability to maintain more moisture, have organic matter, more than the southern and eastern slopes. Correlation coefficients obtained included: correlation coefficient between organic matter and elevation 0.84, correlation coefficient between organic matter

  2. Decomposition and recycling of organic matter in muds of the Gulf of Papua, northern Coral Sea

    NASA Astrophysics Data System (ADS)

    Along, Daniel M.

    Most sediment and organic material transported from rivers of southern Papua New Guinea enters into the Gulf of Papua, depositing on the inner shelf as either laminated or bioturbated, silt-dominated mud. These facies are the major trawling grounds for a growing penaeid prawn fishery. In contrast to most other terrigenous shelf deposits, decomposition processes in the upper 20 cm of these Papuan silts are apparently dominated by oxic and suboxic diagenesis. Rates of surface oxygen consumption were high (mean = 26.9; range = 17.8-46.8 mmol O 2 m -2 d -1) as were bacterial numbers (range: 1-4 × 10 10 cells g -1 DW) and rates of bacterial carbon production (tritiated thymidine uptake; range: 3-f0 gC m -2 d -1). Rates of sulfate reduction were low (range: 3.6-6.8 mmol S m -2 d -1) with little (18-25%) of the total reduced 35S0 4 recovered as acid-volatile sulfide. Free sulfides were not detected in porewaters. Total solid-phase S concentrations were low (0.15-0.20% DW) indicating low net S precipitation in the upper 20 cm. Concentrations of dissolved Fe and Mn were elevated in porewaters in the laminated silts. Solid-phase Fe concentrations were moderately high (range: 4.6-5.3% DW) and measured dissolved metal and nutrient fluxes suggest active Fe and Mn reduction (at some stations) and generally high turnover of the porewater N pools. The domination of oxidants other than sulfate and probable C limitation in these moderately Ferich silts, results in aSC signature comparable to freshwater sediments. These diagenetic patterns are reminiscent of those measured in muds on the Amazon shelf and may similarly be attributed to dilution of reactive organic matter combined with intense physical reworking and/or bioturbation, promoting oxidant recharge and favoring decomposition processes other than sulfate reduction. Rapid rates of detrital decomposition lead to fast rates of benthic nutrient release that contribute, on average, 71% and 35% of the daily N and P requirements of

  3. EXPLORING THE FEEDBACKS BETWEEN CRETACEOUS OCEAN CIRCULATION, OCEANIC REDOX DYNAMICS AND SEDIMENT DIAGENESIS

    NASA Astrophysics Data System (ADS)

    Arndt, S.; Godderis, Y.; Donnadieu, Y.; Regnier, P.

    2009-12-01

    The Mid-Cretaceous oceanic anoxic events (OAEs) are witnesses of major perturbations of the Earth climate, which resulted from important changes in structure of the ocean-atmosphere system and its biogeochemical functioning. They are globally well documented by the ubiquitous presence of organic carbon-rich black shale layers. However, the exact nature and functioning of the palaeo-environment that fostered the massive and almost ubiquitous deposition of organic carbon-rich sediments is still a matter of debate. Numerous outstanding questions remain, not only concerning the dependence of black shale deposition on ocean circulation and redox zonation, but also its influence on the global ocean-atmosphere system. A new version of the coupled Earth system model GEOCLIM, which combines a climate model (FOAM 3-D GCM) with a vertically resolved diffusion-advection box model of the global ocean, a pelagic biogeochemical model and a fully formulated diagenetic model (BNRS) is used to examine the feedbacks between paleocirculation, ocean redox dynamics, sediment diagenesis and global climate. Different scenarios are designed to assess the influence of the global circulation on the biogeochemical functioning of the ocean during a mid-Cretaceous OAE. Simulation results illustrate the strong feedbacks between Cretaceous ocean circulation, oceanic geochemical dynamics, bioproductivity and sediment diagenesis. A weakening of the deep ocean ventilation increases the importance of diagenetic processes on the geochemical characteristics of the ocean. Ocean anoxia/euxinia can easily develop if the sedimentary nutrient recycling is high enough to sustain enhanced primary production. Thus, the earth system model provides a rational support for a detailed quantitative understanding of the ocean's biogeochemical response to potential circulation changes during a mid-Cretaceous OAE. It helps identify plausible scenarios for black shale deposition which are compared with simulation

  4. Exploring the feedbacks between Cretaceous ocean circulation, oceanic redox dynamics and sediment diagenesis

    NASA Astrophysics Data System (ADS)

    Arndt, Sandra; Regnier, Pierre; Donnadieu, Yannick; Godderis, Yves

    2010-05-01

    The Mid-Cretaceous oceanic anoxic events (OAEs) are witnesses of major perturbations of the Earth climate, which resulted from important changes in structure of the ocean-atmosphere system and its biogeochemical functioning. They are globally well documented by the ubiquitous presence of organic carbon-rich black shale layers. However, the exact nature and functioning of the palaeo-environment that fostered the massive and almost ubiquitous deposition of organic carbon-rich sediments is still a matter of debate. Numerous outstanding questions remain, not only concerning the dependence of black shale deposition on ocean circulation and redox zonation, but also its influence on the global ocean-atmosphere system. A new version of the coupled Earth system model GEOCLIM, which combines a climate model (FOAM 3-D GCM) with a vertically resolved diffusion-advection box model of the global ocean, a pelagic biogeochemical model and a fully formulated diagenetic model (BNRS) is used to examine the feedbacks between paleocirculation, ocean redox dynamics, sediment diagenesis and global climate. Different scenarios are designed to assess the influence of the global circulation on the biogeochemical functioning of the ocean during a mid-Cretaceous OAE. Simulation results illustrate the strong feedbacks between Cretaceous ocean circulation, oceanic geochemical dynamics, bioproductivity and sediment diagenesis. A weakening of the deep ocean ventilation increases the importance of diagenetic processes on the geochemical characteristics of the ocean. Ocean anoxia/euxinia can easily develop if the sedimentary nutrient recycling is high enough to sustain enhanced primary production. Thus, the earth system model provides a rational support for a detailed quantitative understanding of the ocean's biogeochemical response to potential circulation changes during a mid-Cretaceous OAE.

  5. Loss of organic matter from riverine particles in deltas

    SciTech Connect

    Keil, R.G.; Quay, P.D.; Richey, J.E.

    1997-04-01

    In order to examine the transport and burial of terrigenous organic matter along the coastal zones of large river systems, we assessed organic matter dynamics in coupled river/delta systems using mineral surface area as a conservative tracer for discharged riverine particulate organic matter (POM). Most POM in the rivers studied (n = 6) is tightly associated with suspended mineral materiaL e.g., it is sorbed to mineral surfaces. Average organic loadings in the Amazon River (0.67 - 0.14 Mg C m{sup -2}), the river for which we have the largest dataset, are approximately twice that of sedimentary minerals from the Amazon Delta (-0.35 mg C m{sup -2}). Stable carbon isotope analysis indicate that approximately two-thirds of the total carbon on the deltaic particles is terrestrial. The combined surface-normalized, isotope-distinguished estimate is that >70% of the Amazon fluvial POM is not buried in the delta consistent with other independent evidence. Losses of terrestrial POM have also been quantified for the river/delta systems of Columbia in the USA, Fly in New Guinea. and Huange-He in China. If the losses of riverine POM observed in these river/delta systems are representative of rivers worldwide, then the surface-constrained analyses point toward a global loss of fluvial POM in delta regions of {approximately}0.1 x 10{sup 15} g C y{sup -1}. 28 refs., 2 figs., 1 tab.

  6. A method for the determination of nitrogen in clays, with application to the burial diagenesis of shales

    SciTech Connect

    Schroder, P.A. . Dept. of Geology); Ingall, E.D. )

    1994-07-01

    A new operationally defined method for the measurement of fixed inorganic nitrogen (N[sub fix]) associated with clays has been tested and applied to a sequence of mixed-layer illite/smectite (I/S) (ranging from 40 to 68% illite in I/S) in shales from a drill site in Terrebonne Parish, Louisiana. This new method has distinct advantages over other methods in that it is simple and can accommodate small sample sizes (10 mg). N[sub fix] is measured, using a carbon-nitrogen analyzer, on a sample that has been ashed for 8 hr at 450 C to remove organic and non-fixed inorganic nitrogen. Total nitrogen is measured on an separate untreated sample. Content of organic carbon and nitrogen can be assessed by the weight-percent difference between untreated and ashed samples. Fourier-transform infrared spectroscopy confirmed the presence of nitrogen as ammonium in untreated and heat-treated samples. N[sub fix] content of the < 0.2 [mu]m fraction of the shale sequence correlates positively (R[sup 2] = 0.91) with the percent of illite in the mixed-layer I/S. Corresponding with the increase in percent of illite in I/S with depth, an increase in N[sub fix] content is also seen with increasing depth of burial. Nitrogen from thermal breakdown of organic-matter during later diagenesis probably provides the N[sub fix] found in I/S. In the range of diagenesis studied here, N[sub fix] concentration appears to depend on the available fixing capacity of illite. Because nitrogen content varies with organic-matter type, however, caution should be used when assuming this relationship for other diagenetic environments.

  7. Photochemical Degradation of Persistent Organic Pollutants: A Study of Ice Photochemistry Mediated by Dissolved Organic Matter

    NASA Astrophysics Data System (ADS)

    Bobby, R.; Pagano, L.; Grannas, A. M.

    2012-12-01

    It is well established that ice is a reactive medium in the environment and that active photochemistry occurs in frozen systems. Snow and ice contain a number of absorbing species including nitrate, peroxide and organic matter. Upon irradiation, they can generate a variety of reactive intermediates such as hydroxyl radical and singlet oxygen. It has been shown that dissolved organic matter is a ubiquitous component of snow and ice and plays an important role in overall light absorption properties of the sample. Additionally, the reactive intermediates produced can further react with contaminants present and alter their fate in the environment. Unfortunately, the role of dissolved organic matter in ice photochemistry has received little attention. Here we present results from laboratory-based studies aimed at elucidating the role of dissolved organic matter photochemistry on contaminant degradation in ice. Aqueous samples of our target pollutant, aldrin (20 μg/L), in liquid and frozen phases, were irradiated under Q-Panel 340 lamps to simulate the UV radiation profile of natural sunlight. Results indicated that frozen samples degraded more quickly than liquid samples and that the addition of dissolved organic matter increases the aldrin degradation rate significantly. Both terrestrial (Suwannee River, U.S.) and microbial sources (Pony Lake, Antarctica) of DOM were able to sensitize aldrin loss in ice. Scavengers of singlet oxygen, such as furfuryl alcohol and β-carotene, were also added to DOM solutions. Based on the type of organic matter present, the scavengers had different effects on the photochemical degradation of aldrin. Our results indicate that natural organic matter present in ice is an important component of ice photochemical processes.

  8. Oxytetracycline sorption to organic matter by metal-bridging.

    PubMed

    MacKay, Allison A; Canterbury, Brian

    2005-01-01

    The sorption of oxytetracycline to metal-loaded ion exchange resin and to natural organic matter by the formation of ternary complexes between polyvalent metal cations and sorbent- and sorbate ligand groups was investigated. Oxytetracycline (OTC) sorption to Ca- and Cu-loaded Chelex-100 resin increased with increasing metal/sorbate ratio at pH 7.6 (OTC speciation: 55% zwitterion, 45% anion). Greater sorption to Cu- than Ca-loaded resin was observed, consistent with the greater stability constants of Cu with both the resin sites and with OTC. Oxytetracycline sorption to organic matter was measured at pH 5.5 (OTC speciation: 1% cation, 98% zwitterion, 1% anion). No detectable sorption was measured for cellulose or lignin sorbents that contain few metal-complexing ligand groups. Sorption to Aldrich humic acid increased from "clean" < "dirty" (no cation exchange pretreatment) < Al-amended < Fe(III)-amended clean humic acid with K(d) values of 5500, 32000, 48000, and 250000 L kg(-1) C, respectively. Calcium amendments of clean humic acid suggested that a portion of the sorbed OTC was interacting by cation exchange. Oxytetracycline sorption coefficients for all humic acid sorbents were well-correlated with the total sorbed Al-plus-Fe(III) concentrations (r(2) = 0.87, log-log plot), suggesting that sorption by ternary complex formation with humic acid is important. Results of this research indicate that organic matter may be an important sorbent phase in soils and sediments for pharmaceutical compounds that can complex metals by the formation of ternary complexes between organic matter ligand groups and pharmaceutical ligand groups. PMID:16221815

  9. Temperature sensitivity of organic-matter decay in tidal marshes

    USGS Publications Warehouse

    Kirwan, Matthew L.; Guntenspergen, Glenn R.; Langley, J.A.

    2014-01-01

    Approximately half of marine carbon sequestration takes place in coastal wetlands, including tidal marshes, where organic matter contributes to soil elevation and ecosystem persistence in the face of sea-level rise. The long-term viability of marshes and their carbon pools depends, in part, on how the balance between productivity and decay responds to climate change. Here, we report the sensitivity of labile soil organic-matter decay in tidal marshes to seasonal and latitudinal variations in temperature measured over a 3-year period. We find a moderate increase in decay rate at warmer temperatures (3-6% per °C, Q10 = 1.3-1.5). Despite the profound differences between microbial metabolism in wetlands and uplands, our results indicate a strong conservation of temperature sensitivity. Moreover, simple comparisons with organic-matter production suggest that elevated atmospheric CO2 and warmer temperatures will accelerate carbon accumulation in marsh soils, and potentially enhance their ability to survive sea-level rise.

  10. Flocculation of Clay and Organic Matter in Turbid Salt Water

    NASA Astrophysics Data System (ADS)

    Reed, A. H.; Yin, H.; Zhang, G.; Tan, X.; Furukawa, Y.

    2010-12-01

    Sediment transport and deposition in estuaries and tidal flats are often dominated by the aggregation of clay and organic matter into composite particles or “flocs”. The stability of the flocs is important in determining the distance over which the sediment is transported and the areas to which the sediment is deposited. During floc transport from riverine to oceanic environments, stability is determined by suspended sediment concentrations, sediment types, organic matter type, fluid flow rates and small scale turbulence. In a series of laboratory experiments, interactions between clay sediments and organic matter were evaluated within a flow column that was filled with saline water. The focus of this investigation was on changes in floc size, density and strength as flow velocities and turbulent stresses were altered. Significant changes in the floc shape, consolidation, density and behavior were determined for flow rates and Reynolds numbers that are common to riverine environments. The variability in floc composition was also shown to influence bulk sediment properties: heat transport, acoustic propagation and shear strength, while sediments were entrained in high-density suspensions and low-density deposits.

  11. Methylmercury production in estuarine sediments: role of organic matter

    PubMed Central

    Schartup, Amina T.; Mason, Robert P.; Balcom, Prentiss H.; Hollweg, Terill A.; Chen, Celia Y.

    2013-01-01

    Methylmercury (MeHg) affects wildlife and human health mainly through marine fish consumption. In marine systems, MeHg is formed from inorganic mercury (HgII) species primarily in sediments then accumulates and biomagnifies in the food web. Most of the fish consumed in the US are from estuarine and marine systems highlighting the importance of understanding MeHg formation in these productive regions. Sediment organic matter has been shown to limit mercury methylation in estuarine ecosystems, as a result it is often described as the primary control over MeHg production. In this paper, we explore the role of organic matter by looking at the effects of its changing sediment concentrations on the methylation rates across multiple estuaries. We measured sedimentary MeHg production at eleven estuarine sites that were selected for their contrasting biogeochemical characteristics, mercury (Hg) content, and location in the Northeastern US (ME, NH, CT, NY, and NJ). Sedimentary total Hg concentrations ranged across five orders of magnitude, increasing in concentration from the pristine, sandy sediments of Wells (ME), to industrially contaminated areas like Portsmouth (NH) and Hackensack (NJ). We find that methylation rates are the highest at locations with high Hg content (relative to carbon), and that organic matter does not hinder mercury methylation in estuaries. PMID:23194318

  12. Comments on D/H ratios in chondritic organic matter

    NASA Astrophysics Data System (ADS)

    Smith, J. W.; Rigby, D.

    1981-06-01

    D/H ratios in chondritic organic matter are investigated. Demineralized organic residues obtained from previous experiments were dried in a quartz reaction vessel under vacuum for 60 minutes at 250-300 C and then combusted in oxygen for 20 minutes at 850 C. The apparatus is described and the results of the experiments such as D/H ratios in water and measurements on total carbon dioxide are given. Atomic H/C ratios calculated directly from the quantities of carbon dioxide and water recovered, are reported according to Standard Mean Ocean Water and Pee Dee Belemnite, using the customary notation.

  13. Carbon isotopic studies of organic matter in Precambrian rocks.

    NASA Technical Reports Server (NTRS)

    Oehler, D. Z.; Schopf, J. W.; Kvenvolden, K. A.

    1972-01-01

    A survey has been undertaken of the carbon composition of the total organic fraction of a suite of Precambrian sediments to detect isotopic trends possibly correlative with early evolutionary events. Early Precambrian cherts of the Fig Tree and upper and middle Onverwacht groups of South Africa were examined for this purpose. Reduced carbon in these cherts was found to be isotopically similar to photosynthetically produced organic matter of younger geological age. Reduced carbon in lower Onverwacht cherts was found to be anomalously heavy; it is suggested that this discontinuity may reflect a major event in biological evolution.

  14. Organic matter in meteorites and comets - Possible origins

    NASA Technical Reports Server (NTRS)

    Anders, Edward

    1991-01-01

    At least six extraterrestrial environments may have contributed organic compounds to meteorites and comets: solar nebula, giant-planet subnebulae, asteroid interiors containing liquid water, carbon star atmospheres, and diffuse or dark interstellar clouds. The record in meteorites is partly obscured by pervasive reheating that transformed much of the organic matter to kerogen; nonetheless, it seems that all six formation sites contributed. For comets, the large abundance of HCHO, HCN, and unsaturated hydrocarbons suggests an interstellar component of 50 percent or more, but the contributions of various interstellar processes, and of a solar-nebula component, are hard to quantify. A research program is outlined that may help reduce these uncertainties.

  15. Flood Pulse Influence on Export of Terrestrial Organic Matter

    NASA Astrophysics Data System (ADS)

    Dalzell, B. J.; Harbor, J. M.; Filley, T. R.

    2004-12-01

    While much attention has been placed on characterizing Terrestrial Organic Matter (TOM) export from large rivers, recent research has shown that in-stream processing of TOM in smaller streams and rivers over shorter time scales can be an important upland component of regional carbon budgets not detected at the outlets of large rivers. With predictions of climate change accompanied by more intense rainfall patterns in some areas, it is important to understand the linkage between flood events and watershed export of TOM. To this end, we have collected water samples from Big Pine Creek watershed, an 850km2 watershed located in west central Indiana. Organic carbon in dissolved, colloidal, and particulate size fractions has been described with molecular and stable carbon isotope techniques to track source, quantity, and compositional changes of TOM over changing flow conditions. Results from these samples show that flood conditions export dramatically more TOM; not only from increases in discharge, but also from increases in concentration of terrestrial organic carbon to all size fractions. While molecular biomarkers show increases in terrestrial organic matter, bulk stable carbon isotope values show that the sources of TOM do not remain constant. Rather, relative contributions from C4 plants (corn in this study area) increase during flood conditions by up to 40 percent. Finally, increases in rainfall intensity are likely to disproportionately increase organic carbon export from terrestrial systems, especially from smaller watersheds where short duration and high intensity flow events dominate annual discharge.

  16. Why dissolved organic matter (DOM) enhances photodegradation of methylmercury

    SciTech Connect

    Qian, Yun; Yin, Xiangping Lisa; Brooks, Scott C; Liang, Liyuan; Gu, Baohua

    2014-01-01

    Methylmercury (MeHg) is known to degrade photochemically, but it remains unclear what roles naturally dissolved organic matter (DOM) and complexing organic ligands play in MeHg photodegradation. Here we investigate the rates and mechanisms of MeHg photodegradation using DOM samples with varying oxidation states and origins as well as organic ligands with known molecular structures. All DOM and organic ligands increased MeHg photodegradation under solar irradiation, but the first-order rate constants varied depending on the oxidation state of DOM and the type and concentration of the ligands. Compounds containing both thiols and aromatics (e.g., thiosalicylate and reduced DOM) increased MeHg degradation rates far greater than those containing only aromatic or thiol functional groups (e.g., salicylate or glutathione). Our results suggest that, among other factors, the synergistic effects of thiolate and aromatic moieties in DOM greatly enhance MeHg photodegradation.

  17. SOIL NITROGEN TRANSFORMATIONS AND ROLE OF LIGHT FRACTION ORGANIC MATTER IN FOREST SOILS

    EPA Science Inventory

    Depletion of soil organic matter through cultivation may alter substrate availability for microbes, altering the dynamic balance between nitrogen (N) immobilization and mineralization. Soil light fraction (LF) organic matter is an active pool that decreases upon cultivation, and...

  18. Soil Quality of Restinga Forest: Organic Matter and Aluminum Saturation

    NASA Astrophysics Data System (ADS)

    Rodrigues Almeida Filho, Jasse; Casagrande, José Carlos; Martins Bonilha, Rodolfo; Soares, Marcio Roberto; Silva, Luiz Gabriel; Colato, Alexandre

    2013-04-01

    The restinga vegetation (sand coastal plain vegetation) consists of a mosaic of plant communities, which are defined by the characteristics of the substrates, resulting from the type and age of the depositional processes. This mosaic complex of vegetation types comprises restinga forest in advanced (high restinga) and medium regeneration stages (low restinga), each with particular differentiating vegetation characteristics. Of all ecosystems of the Atlantic Forest, restinga is the most fragile and susceptible to anthropic disturbances. The purpose of this study was evaluating the organic matter and aluminum saturation effects on soil quality index (SQI). Two locations were studied: State Park of the Serra do Mar, Picinguaba, in the city of Ubatuba (23°20' e 23°22' S / 44°48' e 44°52' W), and State Park of Cardoso Island in the city of Cananéia (25°03'05" e 25°18'18" S / 47°53'48" e 48° 05'42" W). The soil samples were collect at a depth of 0-10 cm, where concentrate 70% of vegetation root system. Was studied an additive model to evaluate soil quality index. The shallow root system development occurs due to low calcium levels, whose disability limits their development, but also can reflect on delay, restriction or even in the failure of the development vegetation. The organic matter is kept in the soil restinga ecosystem by high acidity, which reduces the decomposition of soil organic matter, which is very poor in nutrients. The base saturation, less than 10, was low due to low amounts of Na, K, Ca and Mg, indicating low nutritional reserve into the soil, due to very high rainfall and sandy texture, resulting in high saturation values for aluminum. Considering the critical threshold to 3% organic matter and for aluminum saturation to 40%, the IQS ranged from 0.95 to 0.1 as increased aluminum saturation and decreased the soil organic matter, indicating the main limitation to the growth of plants in this type of soil, when deforested.

  19. Soil organic matter regulates molybdenum storage and mobility in forests

    USGS Publications Warehouse

    Marks, Jade A; Perakis, Steven; King, Elizabeth K; Pett-Ridge, Julie

    2015-01-01

    The trace element molybdenum (Mo) is essential to a suite of nitrogen (N) cycling processes in ecosystems, but there is limited information on its distribution within soils and relationship to plant and bedrock pools. We examined soil, bedrock, and plant Mo variation across 24 forests spanning wide soil pH gradients on both basaltic and sedimentary lithologies in the Oregon Coast Range. We found that the oxidizable organic fraction of surface mineral soil accounted for an average of 33 %of bulk soil Mo across all sites, followed by 1.4 % associated with reducible Fe, Al, and Mn-oxides, and 1.4 % in exchangeable ion form. Exchangeable Mo was greatest at low pH, and its positive correlation with soil carbon (C) suggests organic matter as the source of readily exchangeable Mo. Molybdenum accumulation integrated over soil profiles to 1 m depth (τMoNb) increased with soil C, indicating that soil organic matter regulates long-term Mo retention and loss from soil. Foliar Mo concentrations displayed no relationship with bulk soil Mo, and were not correlated with organic horizon Mo or soil extractable Mo, suggesting active plant regulation of Mo uptake and/or poor fidelity of extractable pools to bioavailability. We estimate from precipitation sampling that atmospheric deposition supplies, on average, over 10 times more Mo annually than does litterfall to soil. In contrast, bedrock lithology had negligible effects on foliar and soil Mo concentrations and on Mo distribution among soil fractions. We conclude that atmospheric inputs may be a significant source of Mo to forest ecosystems, and that strong Mo retention by soil organic matter limits ecosystem Mo loss via dissolution and leaching pathways.

  20. Influence of vegetation changes on soil organic matter

    NASA Astrophysics Data System (ADS)

    Nørnberg, Per

    In a heath region at Hjelm Hede in Denmark oak trees are invading a Calluna/Empetrum vegetation. In less than a century the oak invasion has caused considerable changes in the soil: what was once an O-horizon under Calluna has changed to an A-horizon under oak; the Calluna E-horizon has lost its distinct appearance; and the sharp boundary between E and Bh has been obliterated. The directly visible changes are associated with a rise in pH of about one unit in the top horizon under the oaks, an increasing content of organic matter in the E-horizon, a decreasing content of organic matter in the Bh-horizon, and a fall in the C/N ratio. In order to estimate the total microbiological activity, cotton strips were placed in the upper soil horizons. The loss in tensile strength during two summer months was 10-15% under Calluna, but more than 50% under oaks. Initial attempts to find differences in the type and content of organic matter showed that the most abundant low-molecular organic acids extracted from the Of-horizons were 3,4-dihydroxybenzoic acid (protocatechuic acid), 4-hydroxybenzoic acid and 4-hydroxy-3-methoxybenzoic acid (vanillic acid). The extraction was done in 0.1 M sodium pyrophosphate at pH 10.2. The organic compounds were determined by HPLC. The 3,4-dihydroxybenzoic acid was relatively the most important compound under the Calluna heath, whereas 4-hydroxy-3-methoxybenzoic acid was most important under oaks. Extractions were performed on water samples from field lysimeter experiments to determine whether the substituted benzoic acids in the soil water arose under transport. These extractions exposed a ppm concentration of 2,4-dichlorobenzoic acid, a compound believed to originate from microbial decomposition of lysimeter material.

  1. Isotopic constraints on the origin of meteoritic organic matter

    NASA Technical Reports Server (NTRS)

    Kerridge, J. F.

    1991-01-01

    Salient features of the isotopic distribution of H, C and N in the organic material found in carbonaceous meteorites are noted. Most organic fractions are strongly enriched in D with respect to the D/H ratio characteristic of H2 in the protosolar system; substantial variations in C-13/C-12 ratio are found among different molecular species, with oxidised species tending to be C-13 enriched relative to reduced species; some homologous series reveal systematic decrease in C-13/C-12 with increasing C number; considerable variation in N-15/N-14 ratio is observed within organic matter, though no systematic pattern to its distribution has yet emerged; no interelement correlations have been observed between isotope enrichments for the different biogenic elements. The isotopic complexity echoes the molecular diversity observed in meteoritic organic matter and suggests that the organic matter was formed by multiple processes and/or from multiple sources. However, existence of a few systematic patterns points towards survival of isotopic signatures characteristic of one or more specific processes. The widespread D enrichment implies either survival of many species of interstellar molecule or synthesis from a reservoir containing a significant interstellar component. Several of the questions raised above can be addressed by more detailed determination of the distribution of the H, C and N isotopes among different well-characterized molecular fractions. Thus, the present study is aimed at discovering whether the different amino acids have comparable D enrichments, which would imply local synthesis from a D-enriched reservoir, or very viable D enrichments, which would imply survival of some interstellar amino acids. The same approach is also being applied to polycyclic aromatic hydrocarbons. Because the analytical technique employed (secondary ion mass spectrometry) can acquire data for all three isotopic systems from each molecular fraction, any presently obscured interelement

  2. The composition and degradability of upland dissolved organic matter

    NASA Astrophysics Data System (ADS)

    Moody, Catherine; Worrall, Fred; Clay, Gareth

    2016-04-01

    In order to assess controls on the degradability of DOM in stream water, samples of dissolved organic matter (DOM) and particulate organic matter (POM) were collected every month for a period of 24 months from an upland, peat-covered catchment in northern England. Each month the degradability of the DOM was assessed by exposing river water to light for up to 24 hours, and the change in the dissolved organic carbon (DOC) concentration in the water was measured. To provide context for the analysis of DOM and its degradability, samples of peat, vegetation, and litter were also taken from the same catchment and analysed. The organic matter samples were analysed by several methods including: elemental analysis (CHN and O), bomb calorimetry, thermogravimetric analysis, pyrolysis GC/MS, ICP-OES, stable isotope analysis (13C and 15N) and 13C solid state nuclear magnetic resonance (NMR). The water samples were analysed for pH, conductivity, absorbance at 400nm, anions, cations, particulate organic carbon (POC) and DOC concentrations. River flow conditions and meteorology were also recorded at the site and included in the analysis of the composition and degradability of DOM. The results of multiple regression models showed that the rates of DOC degradation were affected by the N-alkyl, O-alkyl, aldehyde and aromatic relative intensities, gross heat, OR and C:N. Of these, the N-alkyl relative intensity had the greatest influence, and this in turn was found to be dependent on the rainfall and soil temperature in the week before sampling.

  3. Using Riverine Natural Organic Matter to Test the Hypothesis that Soil Organic Matter is Modified by Contact with Sodium Hydroxide

    NASA Astrophysics Data System (ADS)

    Perdue, E. Michael; Driver, Shamus; Hertkorn, Norbert; Harir, Mourad; Schmitt-Kopplin, Philippe

    2016-04-01

    It has been postulated by some scientists that soil humic acids and fulvic acids are an artifact of alkaline extractions of soil. Riverine natural organic matter (NOM) is obtained in part by dissolution and transport of organic matter from soils by meteoric waters at acidic to circumneutral pH. The NOM may be fractionated into humic acid (HA), fulvic acid (FA), and hydrophilic NOM by adsorption of HA and FA onto XAD-8 resin at pH < 2, followed by their desorption with NaOH at pH 13. Alternatively, riverine NOM may be concentrated using reverse osmosis (RO) and desalted by cation exchange. Several properties of Suwannee River NOM prior to its isolation, after concentration by RO, and after the XAD-8 process are compared to detect modifications that might have resulted from exposure of the sample to low and high pH.

  4. Is organic matter found in glaciers similar to soil organic matter? A detailed molecular-level investigation of organic matter found in cryoconite holes on the Athabasca Glacier

    NASA Astrophysics Data System (ADS)

    Simpson, M. J.; Xu, Y.; Eyles, N.; Simpson, A. J.; Baer, A.

    2009-04-01

    Cryoconite is a dark-coloured, dust-like material found on the surfaces of glaciers. Cryoconite has received much interest recently because cryoconite holes, which are produced by accelerated ice melt, act as habitats for microbes on glacier surfaces and accelerate ice melt. To the best of our knowledge, cyroconite organic matter (COM) has not yet been chemically characterized at the molecular level. In this study, organic matter biomarkers and a host of Nuclear Magnetic Resonance (NMR) techniques were used to characterize COM from the Athabasca Glacier in the Canadian Rocky Mountains. The research questions that were targeted by this study include: 1) what are the sources of COM on the Athabasca Glacier; 2) are there any biomarker and/or NMR evidence for microbial community activity in the cryoconite holes; and 3) is the COM structurally similar to terrestrial OM? Solvent extracts contained large quantities of fatty acids, n-alkanols, n-alkanes, wax esters and sterols. A large contribution of C23, C25 and C27 relative to C29 and C31 n-alkanes suggests that allochthonous COM is mainly from lower order plants (mosses, lichens). This is confirmed by the absence of lignin phenols (after copper (II) oxidation) in extracts and NMR analyses of COM. Solution-state 1H NMR reveals prominent signals from microbial components, while solid-state 13C Cross Polarization Magic Angle Spinning NMR analysis shows an atypically high alkyl/O-alkyl ratio, suggesting that COM is unique compared to organic matter found in nearby soils. The NMR results suggest that COM is dominated by microbial-derived compounds which were confirmed by phospholipid fatty acid analysis, which showed a significant microbial contribution, primarily from bacteria and minor microeukaryotes. Both biomarker and NMR data suggest that COM likely supports active microbial communities on the Athabasca Glacier and that COM composition is uniquely different than that found in terrestrial environments. Our data

  5. An analysis of the chemical character of dissolved organic matter and soluble soil organic matter within the same catchment

    NASA Astrophysics Data System (ADS)

    Gabor, R. S.; Russell, N.; McKnight, D. M.

    2010-12-01

    Trends of increasing dissolved organic matter (DOM) concentrations have been reported in many parts of the world. To better understand how organic matter is transported throughout and used within watersheds, it is important to measure not only how much there is, but to also its chemical character. In this study, spectroscopic techniques were used to analyze the DOM from Boulder Creek in Colorado, as well as the soluble organic matter in soil from a smaller catchment within the watershed. Samples from the creek were taken at regular intervals for several years and the DOM quantity and quality was analyzed to determine both seasonal impacts and the affect of Barker Dam halfway up the watershed. Observed trends followed similar patterns to that seen in other alpine ecosystems, with a peak in microbial DOM just before snowmelt, followed by increasing terrestrial input. However, the storage in the reservoir made the signal less clear below the dam. Soil organic matter samples were taken with an aim to observing both spatial and temporal patterns. A large number of both surface and deep samples were taken in one time snapshot, and surface samples were taken from the same plots over several months beginning during snowmelt and reaching the end of the growing season. Surface samples displayed a stronger correlation with DOM in the stream than samples taken at depth, indicating much of the DOM comes from overland flow. However, strong microbial signals from samples at depth indicated the possibility that microbes may be using OM as an electron acceptor during bedrock weathering processes. Little variation was shown temporally in surface samples, although there was some seen in the riparian zone during snowmelt.

  6. Photochemical flocculation of terrestrial dissolved organic matter and iron

    NASA Astrophysics Data System (ADS)

    Helms, John R.; Mao, Jingdong; Schmidt-Rohr, Klaus; Abdulla, Hussain; Mopper, Kenneth

    2013-11-01

    Dissolved organic matter (DOM) rich water samples (Great Dismal Swamp, Virginia) were 0.1-μm filtered and UV-irradiated in a solar simulator for 30 days. During the irradiation, pH increased, particulate organic matter (POM) and particulate iron formed. After 30 days, 7% of the dissolved organic carbon (DOC) was converted to POC while 75% was remineralized. Approximately 87% of the iron was removed from the dissolved phase after 30 days, but iron did not flocculate until a major fraction of DOM was removed by photochemical degradation and flocculation (>10 days); thus, during the initial 10 days, there were sufficient organic ligands present or the pH was low enough to keep iron in solution. Nuclear magnetic resonance and Fourier transform infrared spectroscopies indicated that photochemically flocculated POM was more aliphatic than the residual non-flocculated DOM. Photochemically flocculated POM was also enriched in amide functionality, while carbohydrate-like material was resistant to both photochemical degradation and flocculation. Abiotic photochemical flocculation likely removes a significant fraction of terrestrial DOM from the upper water column between headwaters and the ocean, but has previously been ignored. Preliminary evidence suggests that this process may significantly impact the transport of DOM and POM in ocean margin environments including estuaries.

  7. Formation of soil organic matter via biochemical and physical pathways of litter mass loss

    NASA Astrophysics Data System (ADS)

    Cotrufo, M. Francesca; Soong, Jennifer L.; Horton, Andrew J.; Campbell, Eleanor E.; Haddix, Michelle L.; Wall, Diana H.; Parton, William J.

    2015-10-01

    Soil organic matter is the largest terrestrial carbon pool. The pool size depends on the balance between formation of soil organic matter from decomposition of plant litter and its mineralization to inorganic carbon. Knowledge of soil organic matter formation remains limited and current C numerical models assume that stable soil organic matter is formed primarily from recalcitrant plant litter. However, labile components of plant litter could also form mineral-stabilized soil organic matter. Here we followed the decomposition of isotopically labelled above-ground litter and its incorporation into soil organic matter over three years in a grassland in Kansas, USA, and used laboratory incubations to determine the decay rates and pool structure of litter-derived organic matter. Early in decomposition, soil organic matter formed when non-structural compounds were lost from litter. Soil organic matter also formed at the end of decomposition, when both non-structural and structural compounds were lost at similar rates. We conclude that two pathways yield soil organic matter efficiently. A dissolved organic matter-microbial path occurs early in decomposition when litter loses mostly non-structural compounds, which are incorporated into microbial biomass at high rates, resulting in efficient soil organic matter formation. An equally efficient physical-transfer path occurs when litter fragments move into soil.

  8. Competitive Sorption and Desorption of Chlorinated Organic Solvents (DNAPLs) in Engineered Natural Organic Matter

    SciTech Connect

    Tang, Jixin; Weber, Walter J., Jr.

    2004-03-31

    The effects of artificially accelerated geochemical condensation and maturation of natural organic matter on the sorption and desorption of trichloroethylene (TCE) and tetrachloroethylene (PCE) were studied. The sorption and desorption of TCE in the presence and absence of the competing PCE and 1,2-dichlorobenzene (DCB) were also examined. A sphagnum peat comprising geologically young organic matter was artificially ''aged'' using superheated water, thus increasing the aromaticity and the degree of condensation of its associated organic matter. The sorption of all solutes tested were increased remarkably and their respective desorptions reduced, by the aged peat. The sorption capacities and isotherm nonlinearities of the peat for both TCE and PCE were found to increase as treatment temperature increased. In the competitive sorption studies, both PCE and DCB were found to depress TCE sorption, with PCE having greater effects than DCB, presumably because the molecular structure o f the former is more similar to that of TCE.

  9. Remote monitoring of organic matter in the ocean

    NASA Astrophysics Data System (ADS)

    Niccolai, Filippo; Bazzani, Marco; Cecchi, Giovanna; Innamorati, Mario; Massi, Luca; Nuccio, Caterina; Santoleri, Rosalia

    1999-12-01

    The monitoring of organic matter, suspended or dissolved in the water column, is relevant for the study of the aquatic environment. Actually, the Dissolved Organic Matter (DOM) represents a major reservoir of reactive carbon in the global carbon cycle, thus influencing significantly the marine ecosystem. Due to the strong absorption in the near ultraviolet, DOM reduces considerably the extinction path of solar light in the water column, affecting phytoplankton population and its vertical distribution. The measurement of the DOM absorption coefficient has to be regarded as a good parameter for the monitoring of water quality. This paper deals with the measurements carried out during the oceanographic campaign 'Marine Fronts,' which took place in the Western Mediterranean Sea and Atlantic Ocean from July 14 to August 5, 1998. In this measurement campaign, a high spectral resolution fluorescence lidar (FLIDAR) was installed on the rear-deck of the O/V 'Urania,' acquiring remote fluorescence spectra both in ship motion and in stations. A particular attention was devoted to the monitoring of DOM distribution in the different water masses in marine frontal areas. The lidar data were compared and integrated with SST satellite data and biological samplings. The results show that FLIDAR data agree with satellite imagery, particularly for marine front detection. The comparison with water sample data gave indications for retrieving the DOM absorption coefficient directly from fluorescence remote spectra. In addition, a protein like fluorescence band was detected in the measurements carried out on total suspended matter filtered from the water samplings.

  10. Photochemical production of singlet oxygen from particulate organic matter.

    PubMed

    Appiani, Elena; McNeill, Kristopher

    2015-03-17

    Dissolved organic matter is established as one of the most relevant photosensitizers in aquatic environments, producing singlet oxygen (1O2) alongside other photochemically produced reactive intermediates. While the production of 1O2 from DOM has been well studied, the relative importance of particulate organic matter (POM) to the overall 1O2 production is less well understood. POM is known to play an important role in pollutant fate through the sorption and transport of hydrophobic pollutants. If POM is directly involved in 1O2 production, sorbed molecules would be expected to undergo enhanced photodegradation. In this work, synthetic POM was prepared by coating silica particles with commercial humic acid. The photochemical behavior of these POM samples was compared to dissolved commercial humic acids (DOM). Suspended natural sediment was also studied to test the environmental relevance of the synthetic POM model. Synthetic POM particles appear to simulate well the 1O2-production of suspended sediment. The 1O2 concentrations experienced by POM-sorbed probe molecules was up to 30% higher than experienced by DOM-sorbed ones, even though the aqueous concentration of 1O2 in irradiated POM suspensions was much lower than the analogous DOM solutions. These results were interpreted with a reaction-diffusion model, which suggested that the production rate of 1O2 by POM is lower than DOM, but the loss of 1O2 from the POM-phase is also lower than DOM. Based on the experimental results of this study, calculations were conducted to estimate the impact of removing POM on 1O2-mediated processes. These calculations indicate that compounds with a log Koc value near 4 will be most affected by removal of POM and that the magnitude of the effect is proportional to the fraction of the total organic matter represented by POM. This study demonstrates that particles can play an important role in the degradation of organic compounds via aquatic photochemistry. PMID:25674663

  11. Organic speciation of size-segregated atmospheric particulate matter

    NASA Astrophysics Data System (ADS)

    Tremblay, Raphael

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

  12. Missing links in the root-soil organic matter continuum.

    SciTech Connect

    O'Brien, S. L.; Iversen, C. M.; Biosciences Division; ORNL

    2009-01-01

    The soil environment remains one of the most complex and poorly understood research frontiers in ecology. Soil organic matter (SOM), which spans a continuum from fresh detritus to highly processed, mineral-associated organic matter, is the foundation of sustainable terrestrial ecosystems. Heterogeneous SOM pools are fueled by inputs from living and dead plants, driven by the activity of micro- and mesofauna, and are shaped by a multitude of abiotic factors (Fig. 1). The specialization required to measure unseen processes that occur on a wide range of spatial and temporal scales has led to the partitioning of soil ecology research across several disciplines. In the organized oral session 'Missing links in the root-soil organic matter continuum' at the annual Ecological Society of America meeting in Albuquerque, NM, USA, we joined the call for greater communication and collaboration among ecologists who work at the root-soil interface (e.g. Coleman, 2008). Our goal was to bridge the gap between scientific disciplines and to synthesize disconnected pieces of knowledge from root-centric and soil-centric studies into an integrated understanding of belowground ecosystem processes. We focused this report around three compelling themes that arose from the session: (1) the influence of the rhizosphere on SOM cycling, (2) the role of soil heterotrophs in driving the transformation of root detritus to SOM, and (3) the controlling influence of the soil environment on SOM dynamics. We conclude with a discussion of new approaches for gathering data to bridge gaps in the root-SOM continuum and to inform the next generation of ecosystem models.

  13. Modelling of organic matter dynamics during the composting process.

    PubMed

    Zhang, Y; Lashermes, G; Houot, S; Doublet, J; Steyer, J P; Zhu, Y G; Barriuso, E; Garnier, P

    2012-01-01

    Composting urban organic wastes enables the recycling of their organic fraction in agriculture. The objective of this new composting model was to gain a clearer understanding of the dynamics of organic fractions during composting and to predict the final quality of composts. Organic matter was split into different compartments according to its degradability. The nature and size of these compartments were studied using a biochemical fractionation method. The evolution of each compartment and the microbial biomass were simulated, as was the total organic carbon loss corresponding to organic carbon mineralisation into CO(2). Twelve composting experiments from different feedstocks were used to calibrate and validate our model. We obtained a unique set of estimated parameters. Good agreement was achieved between the simulated and experimental results that described the evolution of different organic fractions, with the exception of some compost because of a poor simulation of the cellulosic and soluble pools. The degradation rate of the cellulosic fraction appeared to be highly variable and dependent on the origin of the feedstocks. The initial soluble fraction could contain some degradable and recalcitrant elements that are not easily accessible experimentally. PMID:21978424

  14. Soil dissolved organic matter export to coastal temperate rainforest streams

    NASA Astrophysics Data System (ADS)

    Edwards, R. T.; D'Amore, D. V.; Hood, E.; Johnson, A.

    2006-12-01

    The north coastal temperate rainforest is a dynamic area of biogeochemical exchange between terrestrial and aquatic ecosystems. Wetlands and poorly drained soils dominate the landscape, where wetlands alone comprise 30% of the watersheds. The region is experiencing warming with potentially profound impacts on soil processes, forest structure, stream productivity, and the large and valuable salmon fishery. There are few data on stream chemistry, biological productivity, or discharge among soils and streams in the region. To predict the impact of climate change, management practices or land use on streams we need better baseline data on soil-stream interactions in temperate rainforest watersheds. We measured weekly export of dissolved organic matter from 3 dominant soil vegetation communities (peat bogs, forested wetlands and mineral soil uplands) during spring through fall of 2006. Three replicate sites for each soil type were gauged with weirs and fluxes of major forms of carbon, nitrogen and phosphorus measured. Discharge dominated the seasonal flux dynamics but major differences in export and area-specific export emphasized differences in soil-specific transformations on nutrient export potential. Export per unit soil area varied from 0.01 to 25 kg C/ha/day. Peat bogs exported 2-5 times as much per unit area as the other two soils. Forested wetlands were intermediate between bogs and uplands in export per unit area. Mean daily carbon fluxes from gauged subcatchments ranged from 0.01 to 75 kg C/day. Because they are larger than bogs, forested wetlands exported the greatest amount of DOC at our study locations, with uplands exporting intermediate amounts during spring floods. Uplands and bogs exported far less than forested wetlands during normal flow conditions. Total nitrogen fluxes were dominated by organic forms and seasonal trends closely followed the patterns observed for DOC. Although wetlands of either type export more organic matter per unit area, the

  15. ENVIRONMENTAL RESEARCH BRIEF: CHARACTERIZATION OF ORGANIC MATTER IN SOIL AND AQUIFER SOLIDS

    EPA Science Inventory

    The focus of this work was the evaluation of analytical methods to determine and characterize fractions of subsurface organic matter. Major fractions of total organic carbon (TOC) include: particulate organic carbon (POC) in aquifer material, dissolved organic carbon (DOC) and ...

  16. Processing of atmospheric organic matter by California radiation fogs

    NASA Astrophysics Data System (ADS)

    Collett, Jeffrey L., Jr.; Herckes, Pierre; Youngster, Sarah; Lee, Taehyoung

    2008-03-01

    Considerable effort has been put into characterizing the ionic composition of fogs and clouds over the past twenty-five years. Recently it has become evident that clouds and fogs often contain large concentrations of organic material as well. Here we report findings from a series of studies examining the organic composition of radiation fogs in central California. Organic compounds in these fogs comprise a major fraction of total solute mass, with total organic carbon sometimes reaching levels of several tens of mg/L. This organic matter is comprised of a wide variety of compounds, ranging from low molecular weight organic acids to high molecular weight compounds with molecular masses approaching several hundred to a thousand g/mole. The most abundant individual compounds are typically formic acid, acetic acid, and formaldehyde. High concentrations are also observed of some dicarboxylic acids (e.g., oxalate) and dicarbonyls (e.g., glyoxal and methylglyoxal) and of levoglucosan, an anhydrosugar characteristically emitted by biomass combustion. Many other compounds have been identified in fog water by GC/MS, including long chain n-alkanoic acids, n-alkanes, PAH, and others, although these compounds typically comprise a total of only a few percent of fog TOC. Measurements of fog scavenging of organic and elemental carbon reveal preferential scavenging of organic carbon. Tracking of individual organic compounds utilized as source type markers suggests the fogs differentially scavenge carbonaceous particles from different source types, with more active processing of wood smoke than vehicle exhaust. Observations of high deposition velocities of fog-borne organic carbon, in excess of 1 cm/s, indicate that fogs in the region represent an important mechanism for cleansing the atmosphere of pollution.

  17. Soft X-Ray Photoionizing Organic Matter from Comet Wild 2: Evidence for the Production of Organic Matter by Impact Processes

    NASA Technical Reports Server (NTRS)

    Zolensky, Michael E.; Wirick, S.; Flynn, G. J.; Jacobsen, C.; Na

    2011-01-01

    The Stardust mission collected both mineral and organic matter from Comet Wild 2 [1,2,3,4]. The organic matter discovered in Comet Wild 2 ranges from aromatic hydrocarbons to simple aliphatic chains and is as diverse and complex as organic matter found in carbonaceous chondrites and interplanetary dust particles.[3,5,6,7,8,9]. Compared to insoluble organic matter from carbonaceous chondrites the organic matter in Comet Wild 2 more closely resembles organic matter found in the IDPS both hydrous and anhydrous. Common processes for the formation of organic matter in space include: Fischer-Tropsch, included with this aqueous large body and moderate heating alterations; UV irradiation of ices; and; plasma formation and collisions. The Fischer-Tropsch could only occur on large bodies processes, and the production of organic matter by UV radiation is limited by the penetration depth of UV photons, on the order of a few microns or less for most organic matter, so once organic matter coats the ices it is formed from, the organic production process would stop. Also, the organic matter formed by UV irradiation would, by the nature of the process, be in-sensitive to photodissocation from UV light. The energy of soft X-rays, 280-300 eV occur within the range of extreme ultraviolet photons. During the preliminary examination period we found a particle that nearly completely photoionized when exposed to photons in the energy range 280-310eV. This particle experienced a long exposure time to the soft x-ray beam which caused almost complete mass loss so little chemical information was obtain. During the analysis of our second allocation we have discovered another particle that photoionized at these energies but the exposure time was limited and more chemical information was obtained.

  18. Mercury dilution by autochthonous organic matter in a fertilized mangrove wetland.

    PubMed

    Machado, Wilson; Sanders, Christian J; Santos, Isaac R; Sanders, Luciana M; Silva-Filho, Emmanoel V; Luiz-Silva, Wanilson

    2016-06-01

    A dated sediment core from a highly-fertilized mangrove wetland located in Cubatão (SE Brazil) presented a negative correlation between mercury (Hg) and organic carbon contents. This is an unusual result for a metal with well-known affinity to organic matter. A dilution of Hg concentrations by autochthonous organic matter explained this observation, as revealed by carbon stable isotopes signatures (δ(13)C). Mercury dilution by the predominant mangrove-derived organic matter counterbalanced the positive influences of algal-derived organic matter and clay contents on Hg levels, suggesting that deleterious effects of Hg may be attenuated. Considering the current paradigm on the positive effect of organic matter on Hg concentrations in coastal sediments and the expected increase in mangrove organic matter burial due to natural and anthropogenic stimulations of primary production, predictions on the influences of organic matter on Hg accumulation in mangrove wetlands deserve caution. PMID:26874872

  19. Unraveling the chemical space of terrestrial and meteoritic organic matter

    NASA Astrophysics Data System (ADS)

    Schmitt-Kopplin, Philippe; Harir, Mourad; Hertkorn, Norbert; Kanawati, Basem; Ruf, Alexander; Quirico, Eric; Bonal, Lydie; Beck, Pierre; Gabelica, Zelimir

    2015-04-01

    In terrestrial environments natural organic matter (NOM) occurs in soils, freshwater and marine environments, in the atmosphere and represents an exceedingly complex mixture of organic compounds that collectively exhibits a nearly continuous range of properties (size-reactivity continuum). In these materials, the "classical" biogeosignatures of the (biogenic and geogenic) precursor molecules, like lipids, lignins, proteins and natural products have been attenuated, often beyond recognition, during a succession of biotic and abiotic (e.g. photo- and redox chemistry) reactions. Because of this loss of biochemical signature, these materials can be designated non-repetitive complex systems. The access to extra-terrestrial organic matter is given i.e. in the analysis of meteoritic materials. Numerous descriptions of organic molecules present in organic chondrites have improved our understanding of the early interstellar chemistry that operated at or just before the birth of our solar system. However, many molecular analyses are so far targeted toward selected classes of compounds with a particular emphasis on biologically active components in the context of prebiotic chemistry. Here we demonstrate that a non-targeted ultrahigh-resolution molecular analysis of the solvent-accessible organic fraction of meteorite extracted under mild conditions allows one to extend its indigenous chemical diversity to tens of thousands of different molecular compositions and likely millions of diverse structures. The description of the molecular complexity provides hints on heteroatoms chronological assembly, shock and thermal events and revealed recently new classes of thousands of novel organic, organometallic compounds uniquely found in extra-terrestrial materials and never described in terrestrial systems. This high polymolecularity suggests that the extraterrestrial chemodiversity is high compared to terrestrial relevant biological and biogeochemical-driven chemical space. (ultra

  20. Organic Matter as an Indicator of Soil Degradation

    NASA Astrophysics Data System (ADS)

    Romero Diaz, Asuncion; Damian Ruiz Sinoga, Jose

    2010-05-01

    Numerous and expensive physical-chemical tests are often carried out to determine the level of soil degration. This study was to find one property, as Organic Matter, which is usually analyzed for determine the soil degradation status. To do this 19 areas in the south and southeast of the Iberian Peninsula (provinces of Málaga, Granada, Almería y Murcia) were selected and a wide sampling process was carried out. Sampling points were spread over a wide pluviometric gradient (from 1100 mm/yr to 232 mm/yr) covering the range from Mediterranean wet to dry. 554 soil surface samples were taken from soil (0-10 cm) and the following properties were analyzed: Texture, Organic Matter (OM), Electric Conductivity (EC), Aggregate Stability (AE) y Cation Exchange Capacity (CEC). These properties were intercorrelated and also with rainfall and the K factor of soil erosion, calculated for each sampling point. Los results obtained by applying the Pearson correlation coefficient to the database shows how as rainfall increases so does OM content (0,97) and la CEC (0,89), but K factor (-0,80) reacts inversely. The content of OM in the soil is related to its biological activity and this in turn is the result of available wáter within the system and, consequently, rainfall. This is specially important in fragile and complex ecogeomorphological systems as is the case of the Mediterranean, where greater or lesser rainfall is similarly reflected in the levels of increase or decrease of soil organic matter. This affirmation is reinforced by linking the organic matter of the soil with other indicative properties such as CEC and erosion, as has been shown by various authors (Imeson y Vis, 1984; De Ploey & Poesen, 1985; Le Bissonnais, 1996; Boix-Fayos et al., 2001; Cammeraat y Imeson, 1998; Cerdá, 1998). As has been stated, there is a direct relationship between rainfall, organic matter content, cation exchange capacity, structural stability, and the resistence to soil erosion factor

  1. Lead sequestration and species redistribution during soil organic matter decomposition

    USGS Publications Warehouse

    Schroth, A.W.; Bostick, B.C.; Kaste, J.M.; Friedland, A.J.

    2008-01-01

    The turnover of soil organic matter (SOM) maintains a dynamic chemical environment in the forest floor that can impact metal speciation on relatively short timescales. Here we measure the speciation of Pb in controlled and natural organic (O) soil horizons to quantify changes in metal partitioning during SOM decomposition in different forest litters. We provide a link between the sequestration of pollutant Pb in O-horizons, estimated by forest floor Pb inventories, and speciation using synchrotron-based X-ray fluorescence and X-ray absorption spectroscopy. When Pb was introduced to fresh forest Oi samples, it adsorbed primarily to SOM surfaces, but as decomposition progressed over two years in controlled experiments, up to 60% of the Pb was redistributed to pedogenic birnessite and ferrihydrite surfaces. In addition, a significant fraction of pollutant Pb in natural soil profiles was associated with similar mineral phases (???20-35%) and SOM (???65-80%). Conifer forests have at least 2-fold higher Pb burdens in the forest floor relative to deciduous forests due to more efficient atmospheric scavenging and slower organic matter turnover. We demonstrate that pedogenic minerals play an important role in surface soil Pb sequestration, particularly in deciduous forests, and should be considered in any assessment of pollutant Pb mobility. ?? 2008 American Chemical Society.

  2. Lead Sequestration and Species Redistribution During Soil Organic Matter Decomposition

    SciTech Connect

    Schroth,A.; Bostick, B.; Kaste, J.; Friedland, A.

    2008-01-01

    The turnover of soil organic matter (SOM) maintains a dynamic chemical environment in the forest floor that can impact metal speciation on relatively short timescales. Here we measure the speciation of Pb in controlled and natural organic (O) soil horizons to quantify changes in metal partitioning during SOM decomposition in different forest litters. We provide a link between the sequestration of pollutant Pb in O-horizons, estimated by forest floor Pb inventories, and speciation using synchrotron-based X-ray fluorescence and X-ray absorption spectroscopy. When Pb was introduced to fresh forest Oi samples, it adsorbed primarily to SOM surfaces, but as decomposition progressed over two years in controlled experiments, up to 60% of the Pb was redistributed to pedogenic birnessite and ferrihydrite surfaces. In addition, a significant fraction of pollutant Pb in natural soil profiles was associated with similar mineral phases ({approx}20-35%) and SOM ({approx}65-80%). Conifer forests have at least 2-fold higher Pb burdens in the forest floor relative to deciduous forests due to more efficient atmospheric scavenging and slower organic matter turnover. We demonstrate that pedogenic minerals play an important role in surface soil Pb sequestration, particularly in deciduous forests, and should be considered in any assessment of pollutant Pb mobility.

  3. Lead Sequestration And Species Redistribution During Soil Organic Matter Decomposition

    SciTech Connect

    Schroth, A.W.; Bostick, B.C.; Kaste, J.M.; Friedland, A.J.

    2009-05-27

    The turnover of soil organic matter (SOM) maintains a dynamic chemical environment in the forest floor that can impact metal speciation on relatively short timescales. Here we measure the speciation of Pb in controlled and natural organic (O) soil horizons to quantify changes in metal partitioning during SOM decomposition in different forest litters. We provide a link between the sequestration of pollutant Pb in O-horizons, estimated by forest floor Pb inventories, and speciation using synchrotron-based X-rayfluorescence and X-ray absorption spectroscopy. When Pb was introduced to fresh forest O{sub i} samples, it adsorbed primarily to SOM surfaces, but as decomposition progressed over two years in controlled experiments, up to 60% of the Pb was redistributed to pedogenic birnessite and ferrihydrite surfaces. In addition, a significant fraction of pollutant Pb in natural soil profiles was associated with similar mineral phases ({approx}20--35%) and SOM ({approx}65--80%). Conifer forests have at least 2-fold higher Pb burdens in the forest floor relative to deciduous forests due to more efficient atmospheric scavenging and slower organic matter turnover. We demonstrate that pedogenic minerals play an important role in surface soil Pb sequestration, particularly in deciduous forests, and should be considered in any assessment of pollutant Pb mobility.

  4. Complexation of lead by organic matter in Luanda Bay, Angola.

    PubMed

    Leitão, Anabela; Santos, Ana Maria; Boaventura, Rui A R

    2015-10-01

    Speciation is defined as the distribution of an element among different chemical species. Although the relation between speciation and bioavailability is complex, the metal present as free hydrated ion, or as weak complexes able to dissociate, is usually more bioavailable than the metal incorporated in strong complexes or adsorbed on colloidal or particulate matter. Among the analytical techniques currently available, anodic stripping voltammetry (ASV) has been one of the most used in the identification and quantification of several heavy metal species in aquatic systems. This work concerns the speciation study of lead, in original (natural, non-filtered) and filtered water samples and in suspensions of particulate matter and sediments from Luanda Bay (Angola). Complexes of lead with organics were identified and quantified by differential pulse anodic stripping voltammetry technique. Each sample was progressively titrated with a Pb(II) standard solution until complete saturation of the organic ligands. After each addition of Pb(II), the intensity, potential and peak width of the voltammetric signal were measured. The results obtained in this work show that more than 95 % of the lead in the aquatic environment is bound in inert organic complexes, considering all samples from different sampling sites. In sediment samples, the lead is totally (100 %) complexed with ligands adsorbed on the particles surface. Two kinds of dominant lead complexes, very strong (logK >11) and strong to moderately strong (8< logK <11), were found, revealing the lead affinity for the stronger ligands. PMID:27624745

  5. Effects of Dissolved Organic Matter Source on Wetland Bacterial Metabolism

    NASA Astrophysics Data System (ADS)

    Ward, A. K.

    2005-05-01

    Wetlands are rich environments for organic matter production from a variety of wetland plant types. Investigations of the Talladega Wetland Ecosystem (TWE) in the southeastern U.S. show that bacterioplankton productivity is driven by dissolved organic carbon derived from wetland plants. The TWE is formed from a small coastal plain stream that has been dammed by beaver activity and resides in a forested catchment. In this study, bacterioplankton communities sampled from the wetland were amended with leachate from two different plants common in the TWE, the soft rush, Juncus effusus, and hazel alder, Alnus serrulata, and compared to unamended controls. The bacterioplankton response was examined by measuring bacterial carbon productivity and by an array of fluorescent microscope techniques used to distinguish metabolically active and non-active cells. Both plant leachates elicited rapid and significant increases in productivity and numbers of metabolically active bacterial cells. However, the timeframe of response, the magnitude of response, and the bacterial morphotypes varied depending on the leachate source. This study suggests that wetland bacterial communities contain different sub-component populations that may generally occur in low numbers, but that can adapt and respond rapidly to different sources of organic matter native to the wetland.

  6. Missing links in the root-soil organic matter continuum

    SciTech Connect

    O'Brien, Sarah L.; Iversen, Colleen M

    2009-01-01

    The soil environment remains one of the most complex and poorly understood research frontiers in ecology. Soil organic matter (SOM), which spans a continuum from fresh detritus to highly processed, mineral-associated organic matter, is the foundation of sustainable terrestrial ecosystems. Heterogeneous SOM pools are fueled by inputs from living and dead plants, driven by the activity of micro- and mesofauna, and are shaped by a multitude of abiotic factors. The specialization required to measure unseen processes that occur on a wide range of spatial and temporal scales has led to the partitioning of soil ecology research across several disciplines. In the organized oral session 'Missing links in the root-soil organic matter continuum' at the annual Ecological Society of America meeting in Albuquerque, NM, USA, we joined the call for greater communication and collaboration among ecologists who work at the root-soil interface (e.g. Coleman, 2008). Our goal was to bridge the gap between scientific disciplines and to synthesize disconnected pieces of knowledge from root-centric and soil-centric studies into an integrated understanding of belowground ecosystem processes. We focused this report around three compelling themes that arose from the session: (1) the influence of the rhizosphere on SOM cycling, (2) the role of soil heterotrophs in driving the transformation of root detritus to SOM, and (3) the controlling influence of the soil environment on SOM dynamics. We conclude with a discussion of new approaches for gathering data to bridge gaps in the root-SOM continuum and to inform the next generation of ecosystem models. Although leaf litter has often been considered to be the main source of organic inputs to soil, Ann Russell synthesized a convincing body of work demonstrating that roots, rather than surface residues, control the accumulation of SOM in a variety of ecosystems. Living roots, which are chemically diverse and highly dynamic, also influence a wide

  7. Priming of soil organic matter decomposition in cryoturbated Arctic soils

    NASA Astrophysics Data System (ADS)

    Richter, A.; Wild, B.; Schnecker, J.; Rusalimova, O.

    2012-12-01

    The Arctic is subjected to particularly high rates of warming, with profound consequences for the carbon cycle: on the one hand plant productivity and C storage in plant biomass have been shown to increase strongly in many parts of the Arctic, on the other hand, increasing rates of soil organic matter (SOM) decomposition have been reported. One of the possibilities that could reconcile these observations is, that increased plant growth may lead to increased root exudation rates, which are known to stimulate microbial turnover of organic matter under certain circumstances, in a process termed "priming" of SOM. Two mechanisms have been brought forward that may be responsible for priming: first, easily assimilable material exuded by plant roots may help microbes to overcome their energy limitation and second, this input of labile carbon could lead to a nitrogen limitation of the microbial community and lead to nitrogen mining, i.e. decomposition of N-rich SOM. We here report on an incubation study with arctic soil investigating potential priming of SOM decomposition in organic topsoil horizons, cryoturbated organic matter and subsoil mineral horizons of tundra soil from the Taymyr peninsula in Siberia. We used arctic soils, that are characterized by cryoturbation (mixing of soil layers due to freezing and thawing), for this study. Turbated cryosols store more than 580 Gt C globally, a significant proportion of which is stored in the cryoturbated organic matter. We hypothesized that an increased availability of labile compounds would increase SOM decomposition rates, and that this effect would be strongest in horizons with a low natural availability of labile C, i.e. in the mineral subsoil. We amended soils with 13C labelled glucose, cellulose, amino acids or proteins, and measured the mineralization of SOM C as well as microbial community composition and potential activities of extracellular enzymes. Our results demonstrate that topsoil organic, cryoturbated and

  8. Persistence of soil organic matter as an ecosystem property

    SciTech Connect

    Schmidt, M.W.; Torn, M. S.; Abiven, S.; Dittmar, T.; Guggenberger, G.; Janssens, I.A.; Kleber, M.; Kögel-Knabner, I.; Lehmann, J.; Manning, D.A.C.; Nannipieri, P.; Rasse, D.P.; Weiner, S.; Trumbore, S.E.

    2011-08-15

    Globally, soil organic matter (SOM) contains more than three times as much carbon as either the atmosphere or terrestrial vegetation. Yet it remains largely unknown why some SOM persists for millennia whereas other SOM decomposes readily—and this limits our ability to predict how soils will respond to climate change. Recent analytical and experimental advances have demonstrated that molecular structure alone does not control SOM stability: in fact, environmental and biological controls predominate. Here we propose ways to include this understanding in a new generation of experiments and soil carbon models, thereby improving predictions of the SOM response to global warming.

  9. Aquatic Organic Matter Fluorescence - from phenomenon to application

    NASA Astrophysics Data System (ADS)

    Reynolds, Darren

    2014-05-01

    The use of fluorescence to quantify and characterise aquatic organic matter in river, ocean, ground water and drinking and waste waters has come along way since its discovery as a phenomenon in the early 20th century. For example, there are over 100 papers published each year in international peer reviewed journals, an order of magnitude increase since a decade ago (see Figure taken from ISI database from 1989 to 2007 for publications in the fields of river water and waste water). Since then it has been extensively used as a research tool since the 1990's by scientists and is currently used for a wide variety of applications within a number of sectors. Universities, organisations and companies that research into aquatic organic matter have either recently readily use appropriate fluorescence based techniques and instrumentation. In industry and government, the technology is being taken up by environmental regulators and water and wastewater companies. This keynote presentation will give an overview of aquatic organic matter fluorescence from its conception as a phenomenon through to its current use in a variety of emerging applications within the sectors concerned with understanding, managing and monitoring the aquatic environment. About the Speaker Darren Reynolds pioneered the use of fluorescence spectroscopy for the analysis of wastewaters in the 1990's. He currently leads a research group within the Centre for Research in Biosciences and sits on the Scientific Advisory Board for the Institute of Bio-Sensing Technology at the University of the West of England, Bristol. He is a multidisciplinary scientist concerned with the development of technology platforms for applications in the fields of environment/agri-food and health. His current research interests include the development of optical technologies and techniques for environmental and biological sensing and bio-prospecting applications. He is currently involved in the development and use of synthetic biology

  10. Persistence of soil organic matter as an ecosystem property.

    PubMed

    Schmidt, Michael W I; Torn, Margaret S; Abiven, Samuel; Dittmar, Thorsten; Guggenberger, Georg; Janssens, Ivan A; Kleber, Markus; Kögel-Knabner, Ingrid; Lehmann, Johannes; Manning, David A C; Nannipieri, Paolo; Rasse, Daniel P; Weiner, Steve; Trumbore, Susan E

    2011-10-01

    Globally, soil organic matter (SOM) contains more than three times as much carbon as either the atmosphere or terrestrial vegetation. Yet it remains largely unknown why some SOM persists for millennia whereas other SOM decomposes readily--and this limits our ability to predict how soils will respond to climate change. Recent analytical and experimental advances have demonstrated that molecular structure alone does not control SOM stability: in fact, environmental and biological controls predominate. Here we propose ways to include this understanding in a new generation of experiments and soil carbon models, thereby improving predictions of the SOM response to global warming. PMID:21979045

  11. Conservative or reactive? Mechanistic chemical perspectives on organic matter stability

    NASA Astrophysics Data System (ADS)

    Koch, Boris

    2016-04-01

    Carbon fixation by terrestrial and marine primary production has a fundamental seasonal effect on the atmospheric carbon content and it profoundly contributes to long-term carbon storage in form of organic matter (OM) in soils, water, and sediments. The efficacy of this sequestration process strongly depends on the degree of OM persistence. Therefore, one of the key issues in dissolved and particulate OM research is to assess the stability of reservoirs and to quantify their contribution to global carbon fluxes. Incubation experiments are helpful to assess OM stability during the first, early diagenetic turnover induced by sunlight or microbes. However, net carbon fluxes within the global carbon cycle also act on much longer time scales, which are not amenable in experiments. It is therefore critical to improve our mechanistic understanding to be able to assess potential future changes in the organic matter cycle. This session contribution highlights some achievements and open questions in the field. An improved mechanistic understanding of OM turnover particularly depends on the molecular characterization of biogeochemical processes and their kinetics: (i) in soils and sediments, aggregation/disaggregation of OM is primarily controlled by its molecular composition. Hence, the chemical composition determines the transfer of organic carbon from the large particulate to the small dissolved organic matter reservoir - an important substrate for microbial metabolism. (ii) In estuaries, dissolved organic carbon gradients usually suggest conservative behavior, whereas molecular-level studies reveal a substantial chemical modification of terrestrial DOM along the land-ocean interface. (iii) In the ocean, previous studies have shown that the recalcitrance of OM depends on bulk concentration and energy yield. However, ultrahigh resolution mass spectrometry in combination with radiocarbon analyses also emphasized that stability is tightly connected to molecular composition

  12. Do organic matter matter? Contribution of organic matter on scavenging and fractionation of natural radionuclides in the Oceanic Flux Program (OFP) site of Bermuda

    NASA Astrophysics Data System (ADS)

    Chuang, C.; Santschi, P. H.; Conte, M. H.; Schumann, D.; Ayranov, M.

    2012-12-01

    Natural particle-reactive radionuclides, 234Th, 233Pa, 210Po, 210Pb and 7Be, have been used for estimating particulate organic carbon (POC) export flux in the ocean for decades. However, by simply relying on empirically determined isotope ratios to POC and other parameters, sometimes results from field studies are puzzling and become controversial (e.g., one is summarized in Li, 2005). The picture becomes clearer when it was noticed that a missing fraction, e.g., natural organic matter, could be the cause. For example, a series of field and lab studies demonstrated that biopolymers excreted by marine micro-organisms are likely carrier molecules for a number of these isotopes (e.g., Guo et al., 2002; Quigley et al., 2002; Santschi et al., 2003; Roberts et al., 2009; Hung et al., 2010; Xu et al., 2011; Hung et al., 2012; Yang et al., 2012). To examine the effect of organic composition of the particle on the scavenging and fractionation of selected natural radionuclides (e.g., Th, Pa, Pb, Po, Be), organic composition (e.g., protein, polysaccharides, uronic acid, siderophore and amino acid contents, and etc.) and particle-water partition coefficients (Kd) were determined for sediment trap material collected in the Oceanic Flux Program (OFP) site of Bermuda (500, 1500 and 3200 m). Results showed that different organic components contribute differently to the fractionation of different radionuclides from the three depths. We conclude that natural organic matter control on the particle-water partition coefficients cannot be ignored.

  13. The abiotic degradation of soil organic matter to oxalic acid

    NASA Astrophysics Data System (ADS)

    Studenroth, Sabine; Huber, Stefan; Schöler, H. F.

    2010-05-01

    The abiotic degradation of soil organic matter to volatile organic compounds was studied intensely over the last years (Keppler et al., 2000; Huber et al., 2009). It was shown that soil organic matter is oxidised due to the presence of iron (III), hydrogen peroxide and chloride and thereby produces diverse alkyl halides, which are emitted into the atmosphere. The formation of polar halogenated compounds like chlorinated acetic acids which are relevant toxic environmental substances was also found in soils and sediments (Kilian et al., 2002). The investigation of the formation of other polar halogenated and non-halogenated compounds like diverse mono- and dicarboxylic acids is going to attain more and more importance. Due to its high acidity oxalic acid might have impacts on the environment e.g., nutrient leaching, plant diseases and negative influence on microbial growth. In this study, the abiotic formation of oxalic acid in soil is examined. For a better understanding of natural degradation processes mechanistic studies were conducted using the model compound catechol as representative for structural elements of the humic substances and its reaction with iron (III) and hydrogen peroxide. Iron is one of the most abundant elements on earth and hydrogen peroxide is produced by bacteria or through incomplete reduction of oxygen. To find suitable parameters for an optimal reaction and a qualitative and quantitative analysis method the following reaction parameters are varied: concentration of iron (III) and hydrogen peroxide, time dependence, pH-value and influence of chloride. Analysis of oxalic acid was performed employing an ion chromatograph equipped with a conductivity detector. The time dependent reaction shows a relatively fast formation of oxalic acid, the optimum yield is achieved after 60 minutes. Compared to the concentration of catechol an excess of hydrogen peroxide as well as a low concentration of iron (III) are required. In absence of chloride the

  14. Morphological Study of Insoluble Organic Matter Residues from Primitive

    NASA Technical Reports Server (NTRS)

    Changela, H. G.; Stroud, R. M.; Peeters, Z.; Nittler, L. R.; Alexander, C. M. O'D.; DeGregorio, B. T.; Cody, G. D.

    2012-01-01

    Insoluble organic matter (IOM) constitutes a major proportion, 70-99%, of the total organic carbon found in primitive chondrites [1, 2]. One characteristic morphological component of IOM is nanoglobules [3, 4]. Some nanoglobules exhibit large N-15 and D enrichments relative to solar values, indicating that they likely originated in the ISM or the outskirts of the protoplanetary disk [3]. A recent study of samples from the Tagish Lake meteorite with varying levels of hydrothermal alteration suggest that nanoglobule abundance decreases with increasing hydrothermal alteration [5]. The aim of this study is to further document the morphologies of IOM from a range of primitive chondrites in order to determine any correlation of morphology with petrographic grade and chondrite class that could constrain the formation and/or alteration mechanisms.

  15. Literature review of organic matter transport from marshes

    NASA Technical Reports Server (NTRS)

    Dow, D. D.

    1982-01-01

    A conceptual model for estimating a transport coefficient for the movement of nonliving organic matter from wetlands to the adjacent embayments was developed in a manner that makes it compatible with the Earth Resources Laboratory's Productive Capacity Model. The model, which envisages detritus movement from wetland pixels to the nearest land-water boundary followed by movement within the water column from tidal creeks to the adjacent embayment, can be transposed to deal with only the interaction between tidal water and the marsh or to estimate the transport from embayments to the adjacent coastal waters. The outwelling hypothesis postulated wetlands as supporting coastal fisheries either by exporting nutrients, such as inorganic nitrogen, which stimulated the plankton-based grazing food chain in the water column, or through the export of dissolved and particulate organic carbon which provided a benthic, detritus-based food web which provides the food source for the grazing food chain in a more indirect fashion.

  16. Release of biodegradable dissolved organic matter from ancient sedimentary rocks

    NASA Astrophysics Data System (ADS)

    Schillawski, Sarah; Petsch, Steven

    2008-09-01

    Sedimentary rocks contain the largest mass of organic carbon on Earth, yet these reservoirs are not well integrated into modern carbon budgets. Here we describe the release of dissolved organic matter (DOM) from OM-rich sedimentary rocks under simulated weathering conditions. Results from column experiments demonstrate slow, sustained release of DOM from ancient sedimentary rocks under simulated weathering conditions. 1H-NMR analysis of shale-derived DOM reveals a highly aliphatic, carbohydrate-poor material distinct from other natural DOM pools. Shale-derived DOM is rapidly assimilated and biodegraded by aerobic heterotrophic bacteria. Consequently, no compositional signature of shale-derived DOM other than 14C-depletion is likely to persist in rivers or other surface reservoirs. Combined, these efforts show that dissolution provides a mechanism for the conversion of refractory kerogen into labile biomass, linking rock weathering with sedimentary OM oxidation and the delivery of aged OM to rivers and ocean margins.

  17. Nature and transformation of dissolved organic matter in treatment wetlands

    USGS Publications Warehouse

    Barber, L.B.; Leenheer, J.A.; Noyes, T.I.; Stiles, E.A.

    2001-01-01

    This investigation into the occurrence, character, and transformation of dissolved organic matter (DOM) in treatment wetlands in the western United States shows that (i) the nature of DOM in the source water has a major influence on transformations that occur during treatment, (ii) the climate factors have a secondary effect on transformations, (iii) the wetlands receiving treated wastewater can produce a net increase in DOM, and (iv) the hierarchical analytical approach used in this study can measure the subtle DOM transformations that occur. As wastewater treatment plant effluent passes through treatment wetlands, the DOM undergoes transformation to become more aromatic and oxygenated. Autochthonous sources are contributed to the DOM, the nature of which is governed by the developmental stage of the wetland system as well as vegetation patterns. Concentrations of specific wastewaterderived organic contaminants such as linear alkylbenzene sulfonate, caffeine, and ethylenediaminetetraacetic acid were significantly attenuated by wetland treatment and were not contributed by internal loading.

  18. Photosensitizing properties of water-extractable organic matter from soils.

    PubMed

    Nkhili, Ezzhora; Boguta, Patrycja; Bejger, Romualda; Guyot, Ghislain; Sokołowska, Zofia; Richard, Claire

    2014-01-01

    Water-extractable organic matter (WEOM) was extracted using pure water from two black soils and from the Elliott reference soil of the International Humic Substances Society (IHSS). WEOMs were characterized by chemical and spectroscopic methods. The apparent quantum yields of singlet oxygen, triplet excited states and hydroxyl radicals formation upon irradiation within the wavelength range 290-450 nm were determined using chemical probes and compared to those of standard Elliott humic substances. In general, the aromatic content, as measured by the SUVA value, was close in WEOMs and humic substances, while the E2/E3 was higher and the humification index lower in the former. Quantum yield values measured for WEOMs fell within the range of those found for basic medium extracted humic substances or were even higher in one case. Thus, water soluble aromatic moiety of the soil organic matter, especially those with low humification degree, is important for the photosensitizing properties. We also found that WEOMs sensitized the bisphenol A phototransformation with rates of the same order of magnitude for all the samples. PMID:24083904

  19. Wastewater disinfection and organic matter removal using ferrate (VI) oxidation.

    PubMed

    Bandala, Erick R; Miranda, Jocelyn; Beltran, Margarita; Vaca, Mabel; López, Raymundo; Torres, Luis G

    2009-09-01

    The use of iron in a +6 valence state, (Fe (VI), as FeO4(-2)) was tested as a novel alternative for wastewater disinfection and decontamination. The removal of organic matter (OM) and index microorganisms present in an effluent of a wastewater plant was determined using FeO4(-2) without any pH adjustment. It was observed that concentrations of FeO4(-2) ranging between 5 and 14 mg l(-1) inactivated up to 4-log of the index microorganisms (initial concentration c.a. 10(6) CFU/100 ml) and achieved OM removal up to almost 50%. The performance of FeO4(-2) was compared with OM oxidation and disinfection using hypochlorite. It was observed that hypochlorite was less effective in OM oxidation and coliform inactivation than ferrate. Results of this work suggest that FeO4(-2) could be an interesting oxidant able to deactivate pathogenic microorganisms in water with high OM content and readily oxidize organic matter without jeopardizing its efficiency on microorganism inactivation. PMID:19491501

  20. Photochemical and Nonphotochemical Transformations of Cysteine with Dissolved Organic Matter.

    PubMed

    Chu, Chiheng; Erickson, Paul R; Lundeen, Rachel A; Stamatelatos, Dimitrios; Alaimo, Peter J; Latch, Douglas E; McNeill, Kristopher

    2016-06-21

    Cysteine (Cys) plays numerous key roles in the biogeochemistry of natural waters. Despite its importance, a full assessment of Cys abiotic transformation kinetics, products and pathways under environmental conditions has not been conducted. This study is a mechanistic evaluation of the photochemical and nonphotochemical (dark) transformations of Cys in solutions containing chromophoric dissolved organic matter (CDOM). The results show that Cys underwent abiotic transformations under both dark and irradiated conditions. Under dark conditions, the transformation rates of Cys were moderate and were highly pH- and temperature-dependent. Under UVA or natural sunlight irradiations, Cys transformation rates were enhanced by up to two orders of magnitude compared to rates under dark conditions. Product analysis indicated cystine and cysteine sulfinic acid were the major photooxidation products. In addition, this study provides an assessment of the contributions of singlet oxygen, hydroxyl radical, hydrogen peroxide, and triplet dissolved organic matter to the CDOM-sensitized photochemical oxidation of Cys. The results suggest that another unknown pathway was dominant in the CDOM-sensitized photodegradation of Cys, which will require further study to identify. PMID:27172378

  1. An enhanced capillary electrophoresis method for characterizing natural organic matter.

    PubMed

    Cottrell, Barbara A; Cheng, Wei Ran; Lam, Buuan; Cooper, William J; Simpson, Andre J

    2013-02-21

    Natural organic matter (NOM) is ubiquitous and is one of the most complex naturally occurring mixtures. NOM plays an essential role in the global carbon cycle; atmospheric and natural water photochemistry; and the long-range transport of trace compounds and contaminants. There is a dearth of separation techniques capable of resolving this highly complex mixture. To our knowledge, this is the first reported use of ultrahigh resolution counterbalance capillary electrophoresis to resolve natural organic matter. The new separation strategy uses a low pH, high concentration phosphate buffer to reduce the capillary electroosmotic flow (EOF). Changing the polarity of the electrodes reverses the EOF to counterbalance the electrophoretic mobility. Sample stacking further improves the counterbalance separation. The combination of these conditions results in an electropherogram comprised up to three hundred peaks superimposed on the characteristic "humic hump" of NOM. Fraction collection, followed by three-dimensional emission excitation spectroscopy (EEMs) and UV spectroscopy generated a distinct profile of fluorescent and UV absorbing components. This enhanced counterbalance capillary electrophoresis method is a potentially powerful technique for the characterization and separation of NOM and complex environmental mixtures in general. PMID:23289095

  2. Terrestrial and marine perspectives on modeling organic matter degradation pathways.

    PubMed

    Burd, Adrian B; Frey, Serita; Cabre, Anna; Ito, Takamitsu; Levine, Naomi M; Lønborg, Christian; Long, Matthew; Mauritz, Marguerite; Thomas, R Quinn; Stephens, Brandon M; Vanwalleghem, Tom; Zeng, Ning

    2016-01-01

    Organic matter (OM) plays a major role in both terrestrial and oceanic biogeochemical cycles. The amount of carbon stored in these systems is far greater than that of carbon dioxide (CO2 ) in the atmosphere, and annual fluxes of CO2 from these pools to the atmosphere exceed those from fossil fuel combustion. Understanding the processes that determine the fate of detrital material is important for predicting the effects that climate change will have on feedbacks to the global carbon cycle. However, Earth System Models (ESMs) typically utilize very simple formulations of processes affecting the mineralization and storage of detrital OM. Recent changes in our view of the nature of this material and the factors controlling its transformation have yet to find their way into models. In this review, we highlight the current understanding of the role and cycling of detrital OM in terrestrial and marine systems and examine how this pool of material is represented in ESMs. We include a discussion of the different mineralization pathways available as organic matter moves from soils, through inland waters to coastal systems and ultimately into open ocean environments. We argue that there is strong commonality between aspects of OM transformation in both terrestrial and marine systems and that our respective scientific communities would benefit from closer collaboration. PMID:26015089

  3. Synergy of fresh and accumulated organic matter to bacterial growth.

    PubMed

    Farjalla, Vinicius F; Marinho, Claudio C; Faria, Bias M; Amado, André M; Esteves, Francisco de A; Bozelli, Reinaldo L; Giroldo, Danilo

    2009-05-01

    The main goal of this research was to evaluate whether the mixture of fresh labile dissolved organic matter (DOM) and accumulated refractory DOM influences bacterial production, respiration, and growth efficiency (BGE) in aquatic ecosystems. Bacterial batch cultures were set up using DOM leached from aquatic macrophytes as the fresh DOM pool and DOM accumulated from a tropical humic lagoon. Two sets of experiments were performed and bacterial growth was followed in cultures composed of each carbon substrate (first experiment) and by carbon substrates combined (second experiment), with and without the addition of nitrogen and phosphorus. In both experiments, bacterial production, respiration, and BGE were always higher in cultures with N and P additions, indicating a consistent inorganic nutrient limitation. Bacterial production, respiration, and BGE were higher in cultures set up with leachate DOM than in cultures set up with humic DOM, indicating that the quality of the organic matter pool influenced the bacterial growth. Bacterial production and respiration were higher in the mixture of substrates (second experiment) than expected by bacterial production and respiration in single substrate cultures (first experiment). We suggest that the differences in the concentration of some compounds between DOM sources, the co-metabolism on carbon compound decomposition, and the higher diversity of molecules possibly support a greater bacterial diversity which might explain the higher bacterial growth observed. Finally, our results indicate that the mixture of fresh labile and accumulated refractory DOM that naturally occurs in aquatic ecosystems could accelerate the bacterial growth and bacterial DOM removal. PMID:18985269

  4. Organic matter turnover in subsoils: current knowledge and future challenges

    NASA Astrophysics Data System (ADS)

    Marschner, Bernd

    2014-05-01

    In the past, carbon flux measurements and modelling have mostly considered the topsoil where C-concentrations, root densities and microbial activities are generally highest. However, depending on climate zone and land use, this soil compartment contains only 30-50% of the C-stocks of the first meter. If the deeper subsoil down to 3 m is also considered, the contribution of topsoil carbon stocks to total soil C-pools is only 20-40%. Another distinct property of subsoil organic matter is its high apparent 14C age. The 14C age of bulk soil organic matter below 30 cm depth generally increases continuously indicating mean residence times of several 103 to 104 years. Large pool size and high radiocarbon age suggest that subsoil OM has accumulated at very low rates over very long time periods and therefore appears to be very stable. In this review, several hypotheses for explaining why subsoil SOM is so seemingly old and inert are presented. These questions are being addressed in a recently granted German research unit consisting of 9 subprojects from all soil science disciplines using field measurements of C-fluxes, 14C analyses and conducting field and lab experiments.

  5. Land Application of Wastes: An Educational Program. Organic Matter - Module 17, Objectives, and Script.

    ERIC Educational Resources Information Center

    Clarkson, W. W.; And Others

    This module sketches out the impact of sewage organic matter on soils. For convenience, that organic matter is separated into the readily decomposable compounds and the more resistant material (volatile suspended solids, refractory organics, and sludges). The fates of those organics are reviewed along with loading rates and recommended soil…

  6. Evaluating Carbon Isotope Signature of Bulk Organic Matter and Plant Wax Derived n-alkanes from Lacustrine Sediments as Climate Proxies along the Western Side of the Andes

    NASA Astrophysics Data System (ADS)

    Contreras, S.; Werne, J. P.; Araneda, A.; Conejero, C. A.

    2015-12-01

    Sedimentary carbon isotope values (δ13C) of bulk organic matter and long chain (C25 to C35) n-alkanes are among the most long-lived and widely utilized proxies of organic matter and vegetation source. The carbon distribution (e.g. average carbon chain length, ACL) and isotope signature from long chain n-alkanes had been intensively used on paleoclimate studies because they are less influenced by diagenesis, differential preservation of compound classes, and changes in the sources of organic matter than bulk δ13C values. Recently, studies of modern plant n-alkanes have challenged the use of carbon distribution and carbon isotope signature from sedimentary n-alkanes as reliable indicators of vegetation and climate change. The climate in central-south western South America (SA) is projected to become significantly warmer and drier over the next several decades to centuries in response to anthropogenically driven warming. Paleolimnological studies along western SA are critical to obtain more realistic and reliable regional reconstructions of past climate and environments, including vegetation and water budget variability. Here we discuss bulk δ13C, distribution and δ13C in long chain n-alkanes from a suite of ~40 lake surface sediment (core-top) samples spanning the transition from a Mediterranean climate with a patchwork of cultivated vegetation, pastureland, conifers in central Chile to a rainy temperate climate dominated by broadleaf deciduous and evergreen forest. Data are compared to the latitudinal and orographic climatic trends of the Andes based on the climatology (e.g. precipitation and temperature) of the locations of all lakes involved in this study, using monthly gridded reanalysis products of the Climate Forecast System Reanalysis (CFSR), based on the NCEP global forecast model and meteorological stations available in the region, from January 1979 to December 2010 with a 0.5° horizontal resolution.

  7. Sulfur species behavior in soil organic matter during decomposition

    NASA Astrophysics Data System (ADS)

    Schroth, Andrew W.; Bostick, Benjamin C.; Graham, Margaret; Kaste, James M.; Mitchell, Myron J.; Friedland, Andrew J.

    2007-12-01

    Soil organic matter (SOM) is a primary reservoir of terrestrial sulfur (S), but its role in the global S cycle remains poorly understood. We examine S speciation by X-ray absorption near-edge structure (XANES) spectroscopy to describe S species behavior during SOM decomposition. Sulfur species in SOM were best represented by organic sulfide, sulfoxide, sulfonate, and sulfate. The highest fraction of S in litter was organic sulfide, but as decomposition progressed, relative fractions of sulfonate and sulfate generally increased. Over 6-month laboratory incubations, organic sulfide was most reactive, suggesting that a fraction of this species was associated with a highly labile pool of SOM. During humification, relative concentrations of sulfoxide consistently decreased, demonstrating the importance of sulfoxide as a reactive S phase in soil. Sulfonate fractional abundance increased during humification irrespective of litter type, illustrating its relative stability in soils. The proportion of S species did not differ systematically by litter type, but organic sulfide became less abundant in conifer SOM during decomposition, while sulfate fractional abundance increased. Conversely, deciduous SOM exhibited lesser or nonexistent shifts in organic sulfide and sulfate fractions during decomposition, possibly suggesting that S reactivity in deciduous litter is coupled to rapid C mineralization and independent of S speciation. All trends were consistent in soils across study sites. We conclude that S reactivity is related to speciation in SOM, particularly in conifer forests, and S species fractions in SOM change during decomposition. Our data highlight the importance of intermediate valence species (sulfoxide and sulfonate) in the pedochemical cycling of organic bound S.

  8. Sulfur species behavior in soil organic matter during decomposition

    USGS Publications Warehouse

    Schroth, A.W.; Bostick, B.C.; Graham, M.; Kaste, J.M.; Mitchell, M.J.; Friedland, A.J.

    2007-01-01

    Soil organic matter (SOM) is a primary re??servoir of terrestrial sulfur (S), but its role in the global S cycle remains poorly understood. We examine S speciation by X-ray absorption near-edge structure (XANES) spectroscopy to describe S species behavior during SOM decomposition. Sulfur species in SOM were best represented by organic sulfide, sulfoxide, sulfonate, and sulfate. The highest fraction of S in litter was organic sulfide, but as decomposition progressed, relative fractions of sulfonate and sulfate generally increased. Over 6-month laboratory incubations, organic sulfide was most reactive, suggesting that a fraction of this species was associated with a highly labile pool of SOM. During humification, relative concentrations of sulfoxide consistently decreased, demonstrating the importance of sulfoxide as a reactive S phase in soil. Sulfonate fractional abundance increased during humification irrespective of litter type, illustrating its relative stability in soils. The proportion of S species did not differ systematically by litter type, but organic sulfide became less abundant in conifer SOM during decomposition, while sulfate fractional abundance increased. Conversely, deciduous SOM exhibited lesser or nonexistent shifts in organic sulfide and sulfate fractions during decomposition, possibly suggesting that S reactivity in deciduous litter is coupled to rapid C mineralization and independent of S speciation. All trends were consistent in soils across study sites. We conclude that S reactivity is related to spqciation in SOM, particularly in conifer forests, and S species fractions in SOM change, during decomposition. Our data highlight the importance of intermediate valence species (sulfoxide and sulfonate) in the pedochemical cycling of organic bound S. Copyright 2007 by the American Geophysical Union.

  9. Potential enzyme activities in cryoturbated organic matter of arctic soils

    NASA Astrophysics Data System (ADS)

    Schnecker, J.; Wild, B.; Rusalimova, O.; Mikutta, R.; Guggenberger, G.; Richter, A.

    2012-12-01

    An estimated 581 Gt organic carbon is stored in arctic soils that are affected by cryoturbtion, more than in today's atmosphere (450 Gt). The high amount of organic carbon is, amongst other factors, due to topsoil organic matter (OM) that has been subducted by freeze-thaw processes. This cryoturbated OM is usually hundreds to thousands of years old, while the chemical composition remains largely unaltered. It has therefore been suggested, that the retarded decomposition rates cannot be explained by unfavourable abiotic conditions in deeper soil layers alone. Since decomposition of soil organic material is dependent on extracellular enzymes, we measured potential and actual extracellular enzyme activities in organic topsoil, mineral subsoil and cryoturbated material from three different tundra sites, in Zackenberg (Greenland) and Cherskii (North-East Siberia). In addition we analysed the microbial community structure by PLFAs. Hydrolytic enzyme activities, calculated on a per gram dry mass basis, were higher in organic topsoil horizons than in cryoturbated horizons, which in turn were higher than in mineral horizons. When calculated on per gram carbon basis, the activity of the carbon acquiring enzyme exoglucanase was not significantly different between cryoturbated and topsoil organic horizons in any of the three sites. Oxidative enzymes, i.e. phenoloxidase and peroxidase, responsible for degradation of complex organic substances, showed higher activities in topsoil organic and cryoturbated horizons than in mineral horizons, when calculated per gram dry mass. Specific activities (per g C) however were highest in mineral horizons. We also measured actual cellulase activities (by inhibiting microbial uptake of products and without substrate addition): calculated per g C, the activities were up to ten times as high in organic topsoil compared to cryoturbated and mineral horizons, the latter not being significantly different. The total amount of PLFAs, as a proxy for

  10. DETOXIFICATION OF OUTFALL WATER USING NATURAL ORGANIC MATTER

    SciTech Connect

    Halverson, N.; Looney, B.; Millings, M.; Nichols, R.; Noonkester, J.; Payne, B.

    2010-07-13

    To protect stream organisms in an ephemeral stream at the Savannah River Site, a proposed National Pollutant Discharge Elimination System (NPDES) permit reduced the copper limit from 25 {micro}g/l to 6 {micro}g/l at Outfall H-12. Efforts to reduce copper in the wastewater and stormwater draining to this outfall did not succeed in bringing copper levels below this limit. Numerous treatment methods were considered, including traditional methods such as ion exchange and natural treatment alternatives such as constructed wetlands and peat beds, all of which act to remove copper. However, the very low target metal concentration and highly variable outfall conditions presented a significant challenge for these treatment technologies. In addition, costs and energy use for most of these alternatives were high and secondary wastes would be generated. The Savannah River National Laboratory developed an entirely new 'detoxification' approach to treat the outfall water. This simple, lower-cost detoxification system amends outfall water with natural organic matter to bind up to 25 {micro}g/l copper rather than remove it, thereby mitigating its toxicity and protecting the sensitive species in the ecosystem. The amendments are OMRI (Organic Materials Review Institute) certified commercial products that are naturally rich in humic acids and are commonly used in organic farming.