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Sample records for abundant organic matter

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

    EPA Science Inventory

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

  2. Organic matter degradation drives benthic cyanobacterial mat abundance on Caribbean coral reefs.

    PubMed

    Brocke, Hannah J; Polerecky, Lubos; de Beer, Dirk; Weber, Miriam; Claudet, Joachim; Nugues, Maggy M

    2015-01-01

    Benthic cyanobacterial mats (BCMs) are impacting coral reefs worldwide. However, the factors and mechanisms driving their proliferation are unclear. We conducted a multi-year survey around the Caribbean island of Curaçao, which revealed highest BCM abundance on sheltered reefs close to urbanised areas. Reefs with high BCM abundance were also characterised by high benthic cover of macroalgae and low cover of corals. Nutrient concentrations in the water-column were consistently low, but markedly increased just above substrata (both sandy and hard) covered with BCMs. This was true for sites with both high and low BCM coverage, suggesting that BCM growth is stimulated by a localised, substrate-linked release of nutrients from the microbial degradation of organic matter. This hypothesis was supported by a higher organic content in sediments on reefs with high BCM coverage, and by an in situ experiment which showed that BCMs grew within days on sediments enriched with organic matter (Spirulina). We propose that nutrient runoff from urbanised areas stimulates phototrophic blooms and enhances organic matter concentrations on the reef. This organic matter is transported by currents and settles on the seabed at sites with low hydrodynamics. Subsequently, nutrients released from the organic matter degradation fuel the growth of BCMs. Improved management of nutrients generated on land should lower organic loading of sediments and other benthos (e.g. turf and macroalgae) to reduce BCM proliferation on coral reefs. PMID:25941812

  3. Organic Matter Degradation Drives Benthic Cyanobacterial Mat Abundance on Caribbean Coral Reefs

    PubMed Central

    Brocke, Hannah J.; Polerecky, Lubos; de Beer, Dirk; Weber, Miriam; Claudet, Joachim; Nugues, Maggy M.

    2015-01-01

    Benthic cyanobacterial mats (BCMs) are impacting coral reefs worldwide. However, the factors and mechanisms driving their proliferation are unclear. We conducted a multi-year survey around the Caribbean island of Curaçao, which revealed highest BCM abundance on sheltered reefs close to urbanised areas. Reefs with high BCM abundance were also characterised by high benthic cover of macroalgae and low cover of corals. Nutrient concentrations in the water-column were consistently low, but markedly increased just above substrata (both sandy and hard) covered with BCMs. This was true for sites with both high and low BCM coverage, suggesting that BCM growth is stimulated by a localised, substrate-linked release of nutrients from the microbial degradation of organic matter. This hypothesis was supported by a higher organic content in sediments on reefs with high BCM coverage, and by an in situ experiment which showed that BCMs grew within days on sediments enriched with organic matter (Spirulina). We propose that nutrient runoff from urbanised areas stimulates phototrophic blooms and enhances organic matter concentrations on the reef. This organic matter is transported by currents and settles on the seabed at sites with low hydrodynamics. Subsequently, nutrients released from the organic matter degradation fuel the growth of BCMs. Improved management of nutrients generated on land should lower organic loading of sediments and other benthos (e.g. turf and macroalgae) to reduce BCM proliferation on coral reefs. PMID:25941812

  4. Organic matter degradation drives benthic cyanobacterial mat abundance on Caribbean coral reefs.

    PubMed

    Brocke, Hannah J; Polerecky, Lubos; de Beer, Dirk; Weber, Miriam; Claudet, Joachim; Nugues, Maggy M

    2015-01-01

    Benthic cyanobacterial mats (BCMs) are impacting coral reefs worldwide. However, the factors and mechanisms driving their proliferation are unclear. We conducted a multi-year survey around the Caribbean island of Curaçao, which revealed highest BCM abundance on sheltered reefs close to urbanised areas. Reefs with high BCM abundance were also characterised by high benthic cover of macroalgae and low cover of corals. Nutrient concentrations in the water-column were consistently low, but markedly increased just above substrata (both sandy and hard) covered with BCMs. This was true for sites with both high and low BCM coverage, suggesting that BCM growth is stimulated by a localised, substrate-linked release of nutrients from the microbial degradation of organic matter. This hypothesis was supported by a higher organic content in sediments on reefs with high BCM coverage, and by an in situ experiment which showed that BCMs grew within days on sediments enriched with organic matter (Spirulina). We propose that nutrient runoff from urbanised areas stimulates phototrophic blooms and enhances organic matter concentrations on the reef. This organic matter is transported by currents and settles on the seabed at sites with low hydrodynamics. Subsequently, nutrients released from the organic matter degradation fuel the growth of BCMs. Improved management of nutrients generated on land should lower organic loading of sediments and other benthos (e.g. turf and macroalgae) to reduce BCM proliferation on coral reefs.

  5. Occurrence and abundance of carbohydrates and amino compounds in sequentially extracted labile soil organic matter fractions.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study aimed to investigate the content of carbohydrates and amino compounds in three labile fraction of soil organic matter (SOM). Soil samples were collected from two agricultural fields in southern Italy and the light fraction (LF), the 500–53-µm particulate organic matter (POM) and the mobil...

  6. Organic matter formed from hydrolysis of metal carbides of the iron peak of cosmic elemental abundance

    NASA Astrophysics Data System (ADS)

    Cataldo, Franco

    2003-01-01

    This work is a modern revisitation of an old idea of great chemists of the past such as Berthelot, Mendeleev, Cloez and Moissan: the formation of organic matter under pre-biotic conditions starting from the hydrolysis of metal carbides. This idea was originally proposed for the formation of petroleum in the Earth and was extended to other bodies of the solar system by Sokolov at the end of the 19th century. The reason for this revisitation lies in the fact that complex organic matter resembling a petroleum fraction may exist in certain protoplanetary nebulae. The present work starts with a survey of the theory of the inorganic origin of petroleum and reports on current evidence for its derivation from residues of formerly living matter, but also considers theories that admit both a biogenic and an abiogenic origin for petroleum. By considering the cosmic abundance of elements and the evidence concerning the presence of carbides in meteorites, we discuss the formation, structure and hydrolysis products derived from the metal carbides of the iron peak of cosmic elemental abundance. Chromium carbide (Cr3C2) has then been used as a model compound for all the key carbides of the iron peak of the cosmic abundance (Cr, Fe, Ni, V, Mn, Co) and it has been hydrolysed under different conditions and the hydrocarbons formed have been analysed using electronic spectroscopy, high-performance liquid chromatography with a diode-array detector (HPLC-DAD) and by Fourier-transform infrared (FT-IR) spectroscopy. Methane, a series of about 20 different alkenes with single and conjugated double bonds have been detected. Paraffins are formed simultaneously with the alkene series but no acetylenic hydrocarbons have been detected. This study confirms early works considering the easy hydrolysis of the carbides of Cr, Fe, Ni, Mn and Co with the formation of H2, a series of alkanes including methane and a series of alkenes including ethylene. The peculiar behaviour of copper carbide (copper is

  7. Identification, abundance and origin of atmospheric organic particulate matter in a Portuguese rural area

    NASA Astrophysics Data System (ADS)

    Pio, C. A.; Alves, C. A.; Duarte, A. C.

    Respirable suspended particles high-volume samples were collected from a coastal-rural site in the centre of Portugal in August 1997 and their solvent-extractable organic compounds were subjected to characterisation by gas chromatography-mass spectrometry. Particles were also analysed by a thermal/optical technique in order to determine their black and organic carbon content. The total lipid extract yields ranged from 20 to 63 μg m -3, containing mainly aliphatic hydrocarbons such as n-alkanes, acids, alcohols, aldehydes, ketones and polycyclic aromatic hydrocarbons. The higher input of vascular plant wax components was demonstrated by the distribution patterns of the n-alkanes, n-alkanoic acids and n-alkanols homologous series, with C max at C 29, C 22/C 24 and C 30, respectively. The CPI values for these series were in the range 1.8-9.7, being indicative of recent biogenic input from microbial lipid residues and flora epicuticular components. Specific natural constituents (e.g. phytosterols, terpenes, etc.) were identified as molecular markers. Some oxidation products from volatile organic precursors were also present in the aerosols. In addition, all samples had a component of petroleum hydrocarbons representing urban and vehicular emissions probably transported from the nearest cities and from the motorway in the vicinity. This data set could be used to make a mass balance with organic carbon, organic extracts and elutable matter, permitting also the comparison with lipid signatures observed for other regions.

  8. Soil compaction and organic matter affect conifer seedling nonmycorrhizal and ectomycorrhizal root tip abundance and diversity. Forest Service research paper

    SciTech Connect

    Amaranthus, M.P.; Page-Dumroese, D.; Harvey, A.; Cazares, E.; Bednar, L.F.

    1996-05-01

    Three levels of organic matter removal (bole only; bole and crowns; and bole, crowns, and forest floor) and three levels of mechanical soil compaction (no compaction, moderate compaction, and severe soil compaction) were studied as they influence Douglas-fir (Pseudotsuga menziesii var. glauca (Beissn.) Franco) and western white pine (Pinus monticola Dougl. ex D. Don) seedlings following outplanting. Moderate and severe soil compaction significantly reduced nonmycorrhizal root tip abundance on both Douglas-fir and western white pine seedlings (p less than or equal to 0.05). Ectomycorrhizal root tip abundance was significantly reduced on Douglas-fir seedlings in severely compacted areas with bole and crowns and bole, crowns, and forest floor removed. Ectomycorrhizal diversity also was significantly reduced on Douglas-fir seedlings in all severely compacted areas.

  9. Enzymatic activities and prokaryotic abundance in relation to organic matter along a West-East Mediterranean transect (TRANSMED cruise).

    PubMed

    Zaccone, R; Boldrin, A; Caruso, G; La Ferla, R; Maimone, G; Santinelli, C; Turchetto, M

    2012-07-01

    The distribution of extracellular enzymatic activities (EEA) [leucine aminopeptidase (LAP), ß-glucosidase (GLU), alkaline phosphatase (AP)], as well as that of prokaryotic abundance (PA) and biomass (PB), dissolved organic carbon (DOC), particulate organic carbon and particulate total nitrogen (POC, PTN), was determined in the epi-, meso-, and bathypelagic waters of the Mediterranean Sea along a West-East transect and at one Atlantic station located outside the Strait of Gibraltar. This study represents a synoptical evaluation of the microbial metabolism during early summer. Decreasing trends with depth were observed for most of the parameters (PA, PB, AP, DOC, POC, PTN). Significant differences between the western and eastern basins of the Mediterranean Sea were found, displaying higher rates of LAP and GLU and lower C/N ratios more in the eastern than in the western areas. Conversely, in the epipelagic layer, PA and PB were found to be higher in the western than in the eastern basins. PB was significantly related to DOC concentration (all data, n = 145, r = 0.53, P < 0.01), while significant correlations of EEA with POC and PTN were found in the epipelagic layer, indicating an active response of microbial metabolism to organic substrates. Specific enzyme activities normalized to cell abundance pointed out high values of LAP and GLU in the bathypelagic layer, especially in the eastern basin, while cell-specific AP was high in the epi- and bathypelagic zone of the eastern basin indicating a rapid regeneration of inorganic P for both prokaryotes and phytoplankton needs. Low activity and abundance characterized the Atlantic station, while opposite trends of these parameters were observed along the Mediterranean transect, showing the uncoupling between abundance and activity data. In the east Mediterranean Sea, decomposition processes increased probably in response to mesoscale structures which lead to organic matter downwelling. PMID:22349935

  10. Resolving the influence of nitrogen abundances on sediment organic matter in macrophyte-dominated lakes, using fluorescence spectroscopy.

    PubMed

    Yao, Xin; Wang, Shengrui; Jiao, Lixin; Yan, Caihong; Jin, Xiangcan

    2015-01-01

    A controlled experiment was designed to resolve the influence of nitrogen abundance on sediment organic matters in macrophyte-dominated lakes using fluorescence analysis. Macrophyte biomass showed coincident growth trends with time, but different variation rates with nitrogen treatment. All plant growth indexes with nitrogen addition (N, NH4Cl 100, 200, 400mg/kg, respectively) were lower than those of the control group. Four humic-like components, two autochthonous tryptophan-like components, and one autochthonous tyrosine-like component were identified using the parallel factor analysis model. The results suggested that the relative component changes of fluorescence in the colonized sediments were in direct relation to the change of root biomass with time. In the experiment, the root formation parameters of the plants studied were significantly affected by adding N in sediments, which may be related to the reason that the root growth was affected by N addition. Adding a low concentration of N to sediments can play a part in supplying nutrients to the plants. However, the intensive uptake of NH4(+) may result in an increase in the intracellular concentration of ammonia, which is highly toxic to the plant cells. Hence, our experiment results manifested that organic matter cycling in the macrophyte-dominated sediment was influenced by nitrogen enrichment through influencing vegetation and relevant microbial activity. PMID:25597678

  11. Molecular characterization of dissolved organic matter in glacial ice: coupling natural abundance 1H NMR and fluorescence spectroscopy.

    PubMed

    Pautler, Brent G; Woods, Gwen C; Dubnick, Ashley; Simpson, André J; Sharp, Martin J; Fitzsimons, Sean J; Simpson, Myrna J

    2012-04-01

    Glaciers and ice sheets are the second largest freshwater reservoir in the global hydrologic cycle, and the onset of global climate warming has necessitated an assessment of their contributions to sea-level rise and the potential release of nutrients to nearby aquatic environments. In particular, the release of dissolved organic matter (DOM) from glacier melt could stimulate microbial activity in both glacial ecosystems and adjacent watersheds, but this would largely depend on the composition of the material released. Using fluorescence and (1)H NMR spectroscopy, we characterize DOM at its natural abundance in unaltered samples from a number of glaciers that differ in geographic location, thermal regime, and sample depth. Parallel factor analysis (PARAFAC) modeling of DOM fluorophores identifies components in the ice that are predominantly proteinaceous in character, while (1)H NMR spectroscopy reveals a mixture of small molecules that likely originate from native microbes. Spectrofluorescence also reveals a terrestrial contribution that was below the detection limits of NMR; however, (1)H nuclei from levoglucosan was identified in Arctic glacier ice samples. This study suggests that the bulk of the DOM from these glaciers is a mixture of biologically labile molecules derived from microbes.

  12. Terracidiphilus gabretensis gen. nov., sp. nov., an Abundant and Active Forest Soil Acidobacterium Important in Organic Matter Transformation

    PubMed Central

    García-Fraile, Paula; Benada, Oldrich; Cajthaml, Tomáš; Baldrian, Petr

    2015-01-01

    Understanding the activity of bacteria in coniferous forests is highly important, due to the role of these environments as a global carbon sink. In a study of the microbial biodiversity of montane coniferous forest soil in the Bohemian Forest National Park (Czech Republic), we succeeded in isolating bacterial strain S55T, which belongs to one of the most abundant operational taxonomic units (OTUs) in active bacterial populations, according to the analysis of RNA-derived 16S rRNA amplicons. The 16S rRNA gene sequence analysis showed that the species most closely related to strain S55T include Bryocella elongata SN10T (95.4% identity), Acidicapsa ligni WH120T (95.2% identity), and Telmatobacter bradus TPB6017T (95.0% identity), revealing that strain S55T should be classified within the phylum Acidobacteria, subdivision 1. Strain S55T is a rod-like bacterium that grows at acidic pH (3 to 6). Its phylogenetic, genotypic, phenotypic, and chemotaxonomic characteristics indicate that strain S55T corresponds to a new genus within the phylum Acidobacteria; thus, we propose the name Terracidiphilus gabretensis gen. nov., sp. nov. (strain S55T = NBRC 111238T = CECT 8791T). This strain produces extracellular enzymes implicated in the degradation of plant-derived biopolymers. Moreover, analysis of the genome sequence of strain S55T also reveals the presence of enzymatic machinery required for organic matter decomposition. Soil metatranscriptomic analyses found 132 genes from strain S55T being expressed in the forest soil, especially during winter. Our results suggest an important contribution of T. gabretensis S55T in the carbon cycle in the Picea abies coniferous forest. PMID:26546425

  13. Diquark abundance in stellar matter

    SciTech Connect

    Horvath, J.E.; de Freitas Pacheco, J.A.; de Araujo, J.C.N. )

    1992-11-15

    The clustering of quarks into pairs (diquarks) has been suggested recently to play an important role in dense matter and its astrophysical realization in neutron-star cores. We address in this work the features of diquark matter by employing an accurate equation of state valid for the effective {lambda}{phi}{sup 4} diquark theory, and find milder (although non-negligible) effects than in previous calculations. Some considerations on the very presence of a diquark-dominated region immediately above the deconfinement density are also given.

  14. Effect of petroleum products on the decomposition of soil organic matter as assessed by 13C natural abundance

    NASA Astrophysics Data System (ADS)

    Stelmach, Wioleta; Szarlip, Paweł; Trembaczowski, Andrzej; Bieganowski, Andrzej

    2016-04-01

    Petroleum products are common contaminants in soils due to human activities. They are toxic for microorganisms and threat their functions, including decomposition of soil organic matter (SOM). The direct estimation of altered SOM decomposition - based on the CO2 emission - is impossible after oil contamination, because oil decomposition also contributes to the CO2 release. We used the natural differences in the isotopic signature (δ13C) of SOM and of oil products to partition the total CO2 for both sources and to analyze the suppression of SOM decomposition. The dynamics of 13C fractionation during the mineralization of gasoline and diesel was measured during 42 days. The 13C fractionation varied between -8.8‰ and +3.6‰ within the first 10 days, and stabilized thereafter at about -5.3‰ for gasoline and +3.2‰ for diesel. These 13C fractionations and δ13C values of CO2 emitted from the soil were used for correct partitioning of the total CO2. Contamination with gasoline reduced the CO2 efflux from SOM decomposition by a factor of 25 (from 151 to 6 mg C-CO2 kg-1 soil during 42 days). The negative effect of diesel was much lower: the CO2 efflux from SOM was decreased by less than a factor of 2. The strong effect of gasoline versus diesel reflects the lower absorption of gasoline to mineral particles and the development of a thin film on water surfaces, leading to toxicity for microorganisms. We conclude that the small differences of 13C of SOM and of organic pollutants can be used to partition CO2 fluxes and analyze pollutant effects on SOM decomposition.

  15. Effect of petroleum products on the decomposition of soil organic matter as assessed by 13C natural abundance

    NASA Astrophysics Data System (ADS)

    Stelmach, Wioleta; Szarlip, Paweł; Trembaczowski, Andrzej; Bieganowski, Andrzej

    2016-04-01

    Petroleum products are common contaminants in soils due to human activities. They are toxic for microorganisms and threat their functions, including decomposition of soil organic matter (SOM). The direct estimation of altered SOM decomposition - based on the CO2 emission - is impossible after oil contamination, because oil decomposition also contributes to the CO2 release. We used the natural differences in the isotopic signature (δ13C) of SOM and of oil products to partition the total CO2 for both sources and to analyze the suppression of SOM decomposition. The dynamics of 13C fractionation during the mineralization of gasoline and diesel was measured during 42 days. The 13C fractionation varied between -8.8‰ and +3.6‰ within the first 10 days, and stabilized thereafter at about -5.3‰ for gasoline and +3.2‰ for diesel. These 13C fractionations and δ13C values of CO2 emitted from the soil were used for correct partitioning of the total CO2. Contamination with gasoline reduced the CO2 efflux from SOM decomposition by a factor of 25 (from 151 to 6 mg C-CO2 kg‑1 soil during 42 days). The negative effect of diesel was much lower: the CO2 efflux from SOM was decreased by less than a factor of 2. The strong effect of gasoline versus diesel reflects the lower absorption of gasoline to mineral particles and the development of a thin film on water surfaces, leading to toxicity for microorganisms. We conclude that the small differences of 13C of SOM and of organic pollutants can be used to partition CO2 fluxes and analyze pollutant effects on SOM decomposition.

  16. Spatiotemporal variations in the abundance and composition of bulk and chromophoric dissolved organic matter in seasonally hypoxia-influenced Green Bay, Lake Michigan, USA.

    PubMed

    DeVilbiss, Stephen E; Zhou, Zhengzhen; Klump, J Val; Guo, Laodong

    2016-09-15

    Green Bay, Lake Michigan, USA, is the largest freshwater estuary in the Laurentian Great Lakes and receives disproportional terrestrial inputs as a result of a high watershed to bay surface area ratio. While seasonal hypoxia and the formation of "dead zones" in Green Bay have received increasing attention, there are no systematic studies on the dynamics of dissolved organic matter (DOM) and its linkage to the development of hypoxia. During summer 2014, bulk dissolved organic carbon (DOC) analysis, UV-vis spectroscopy, and fluorescence excitation-emission matrices (EEMs) coupled with PARAFAC analysis were used to quantify the abundance, composition and source of DOM and their spatiotemporal variations in Green Bay, Lake Michigan. Concentrations of DOC ranged from 202 to 571μM-C (average=361±73μM-C) in June and from 279 to 610μM-C (average=349±64μM-C) in August. In both months, absorption coefficient at 254nm (a254) was strongly correlated to bulk DOC and was most abundant in the Fox River, attesting a dominant terrestrial input. Non-chromophoric DOC comprised, on average, ~32% of bulk DOC in June with higher terrestrial DOM and ~47% in August with higher aquagenic DOM, indicating that autochthonous and more degraded DOM is of lower optical activity. PARAFAC modeling on EEM data resulted in four major fluorescent DOM components, including two terrestrial humic-like, one aquagenic humic-like, and one protein-like component. Variations in the abundance of DOM components further supported changes in DOM sources. Mixing behavior of DOM components also indicated that while bulk DOM behaved quasi-conservatively, significant compositional changes occurred during transport from the Fox River to the open bay.

  17. The effects of the 2010 flood on the composition and abundance of the terrestrial organic matter in sediments along the inner-shelf off the Changjiang Estuary, China

    NASA Astrophysics Data System (ADS)

    Li, X.; Bianchi, T. S.; Allison, M. A.; Chapman, P.; Yang, G.

    2011-12-01

    Surface sediments were collected within the primary depositional pathway along the inner-shelf off the Changjiang Estuary in winter 2009 and fall 2010 - before and after the 2010 flood in the Changjiang River. Multiple proxies (stable isotopes, lignin-phenols, pigments, cutins) were analyzed to examine the influence of this flooding event on the composition and abundance of river-derived terrestrial organic matter in sediments off the Changjiang Estuary. Elemental and stable isotope analyses showed significantly higher molar C/N ratios and enriched δ13C signatures for 2010 samples, which likely reflected inputs of C4 vascular plant materials. Post-flood concentrations of lignin-phenols were significantly lower in concentration than pre-flood concentrations in 2009. Lignin-phenol acid/aldehyde (Ad/Al) ratios, the lignin degradation index, showed significantly more degraded lignin post-flood in 2010 than that in 2009, which suggests greater inputs of lignins that were likely associated more with degraded soils, due to enhanced erosion from the flood, than surface plant litter. This was also in good agreement with higher inputs of another lignin soil proxy, the 3,5-Bd (3,5-dihydroxybenzoic acid) /V. Lignin-phenol source plots showed no significant differences in pre-and post flood sources, with sources largely consisting of a mixture of woody and non-woody gymnosperm and angiosperm inputs. Short lived radionuclides such as 7Be, 234Th analysis showed no apparent short-term sediment accumulation. The lack of evidence for new sediments deposited to the inner shelf after the flood was likely influenced in part, by the effects of extensive upstream damming on the Changjiang, especially the more recently constructed Three Gorges Dam.

  18. 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

  19. Dark Energy and The Dark Matter Relic Abundance

    SciTech Connect

    Rosati, Francesca

    2004-11-17

    Two mechanisms by which the quintessence scalar could enhance the relic abundance of dark matter particles are discussed. These effects can have an impact on supersymmetric candidates for dark matter.

  20. 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.

  1. 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.

  2. Abundance of Asymmetric Dark Matter in Brane World Cosmology

    NASA Astrophysics Data System (ADS)

    Abdusattar, Haximjan; Iminniyaz, Hoernisa

    2016-09-01

    Relic abundance of asymmetric Dark Matter particles in brane world cosmological scenario is investigated in this article. Hubble expansion rate is enhanced in brane world cosmology and it affects the relic abundance of asymmetric Dark Matter particles. We analyze how the relic abundance of asymmetric Dark Matter is changed in this model. We show that in such kind of nonstandard cosmological scenario, indirect detection of asymmetric Dark Matter is possible if the cross section is small enough which let the anti-particle abundance kept in the same amount with the particle. We show the indirect detection signal constraints can be used to such model only when the cross section and the 5-dimensional Planck mass scale are in appropriate values. Supported by the National Natural Science Foundation of China under Grant No. 11365022

  3. Elemental abundances in meteoritic and terrestrial matter

    NASA Technical Reports Server (NTRS)

    Schmitt, R. A.

    1974-01-01

    Major and trace element analyses of over 180 individual chondrules from 12 carbonaceous chondrites are reported, including individual analyses of 60 chondrules from Pueblito de Allende. Siderophile elements in most chondrules are depleted, compared to the whole chondrite. Correlations of Al-Ir and Ir-Sc among chondrules high in Ca and Al were observed. A Cu-Mn correlation was also found for chondrules from some meteorites. No correlation was observed between Au and other siderophile elements (Fe, Ni, Co and Ir). It is suggested that these elemental associations were present in the material from which the chondrules formed. Compositionally, chondrules appear to be a multicomponent mixture of remelted dust. One component displaying an Al-Ir correlation is identified as Allende-type white aggregates. The other components are a material chemically similar to the present matrix and sulfides-plus-metal material. Abundances of the REE (rare earth elements) were measured in ordinary Allende chondrules and were 50% higher than REE abundances in Mokoia chondrules; REE abundances in Ca-Al rich chondrules were similar to REE abundances in Ca-rich white aggregates.

  4. Detection and structural identification of dissolved organic matter in Antarctic glacial ice at natural abundance by SPR-W5-WATERGATE 1H NMR spectroscopy.

    PubMed

    Pautler, Brent G; Simpson, André J; Simpson, Myrna J; Tseng, Li-Hong; Spraul, Manfred; Dubnick, Ashley; Sharp, Martin J; Fitzsimons, Sean J

    2011-06-01

    Dissolved organic matter (DOM) is ubiquitous in aquatic ecosystems and is derived from various inputs that control its turnover. Glaciers and ice sheets are the second largest water reservoir in the global hydrologic cycle, but little is known about glacial DOM composition or contributions to biogeochemical cycling. Here we employ SPR-W5-WATERGATE (1)H NMR spectroscopy to elucidate and quantify the chemical structures of DOM constituents in Antarctic glacial ice as they exist in their natural state (average DOC of 8 mg/L) without isolation or preconcentration. This Antarctic glacial DOM is predominantly composed of a mixture of small recognizable molecules differing from DOM in marine, lacustrine, and other terrestrial environments. The major constituents detected in three distinct types of glacial ice include lactic and formic acid, free amino acids, and a mixture of simple sugars and amino sugars with concentrations that vary between ice types. The detection of free amino acid and amino sugar monomer components of peptidoglycan within the ice suggests that Antarctic glacial DOM likely originates from in situ microbial activity. As these constituents are normally considered to be biologically labile (fast cycling) in nonglacial environments, accelerated glacier melt and runoff may result in a flux of nutrients into adjacent ecosystems.

  5. Helium and neon abundances and compositions in cometary matter.

    PubMed

    Marty, Bernard; Palma, Russell L; Pepin, Robert O; Zimmermann, Laurent; Schlutter, Dennis J; Burnard, Peter G; Westphal, Andrew J; Snead, Christopher J; Bajt, Sasa; Becker, Richard H; Simones, Jacob E

    2008-01-01

    Materials trapped and preserved in comets date from the earliest history of the solar system. Particles captured by the Stardust spacecraft from comet 81P/Wild 2 are indisputable cometary matter available for laboratory study. Here we report measurements of noble gases in Stardust material. Neon isotope ratios are within the range observed in "phase Q," a ubiquitous, primitive organic carrier of noble gases in meteorites. Helium displays 3He/4He ratios twice those in phase Q and in Jupiter's atmosphere. Abundances per gram are surprisingly large, suggesting implantation by ion irradiation. The gases are probably carried in high-temperature igneous grains similar to particles found in other Stardust studies. Collectively, the evidence points to gas acquisition in a hot, high ion-flux nebular environment close to the young Sun.

  6. Helium and Neon Abundances and Compositions in Cometary Matter

    SciTech Connect

    Marty, B; Palma, R L; Pepin, R O; Zimmmermann, L; Schlutter, D J; Burnard, P G; Westphal, A J; Snead, C J; Bajt, S; Becker, R H; Simones, J E

    2007-10-15

    Materials trapped and preserved in comets date from the earliest history of the solar system. Particles captured by the Stardust spacecraft from comet Wild 2 are indisputable cometary matter available for laboratory study. Here they report measurements of noble gases in Stardust material. neon isotope ratios are within the range observed in 'phase Q', a ubiquitous, primitive organic carrier of noble gases in meteorites. Helium displays {sup 3}He/{sup 4}He ratios twice those in phase Q and in Jupiter's atmosphere. Abundances per gram are surprisingly large, suggesting implantation by ion irradiation. The gases are carried in high temperature igneous grains similar to particles found in other Stardust studies. Collectively the evidence points to gas acquisition in a hot, high ion flux nebular environment close to the young Sun.

  7. 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

  8. 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

  9. Organic Matter Management

    SciTech Connect

    Izaurralde, Roberto C.; Cerri, Carlos C.

    2002-01-01

    Soil organic matter (S)M) is an essential attribute of soil quality with a key role in soil conservation and sustainable agriculture. Many practices-some involving land use changes-have been shown to increase SOM and thus received considerable attention for their possible role in climate change mitigation. Carbon sequestration in managed soils occurs when there is a net removal of atmospheric CO2 because of the balance between carbon inputs (net primary productivity) and outputs (soil respiration, management-related C emissions). Soil C sequestration has the additional appeal that all its practices conform to principles of sustainable agriculture (e.g., reduced tillage, erosion control, diverse cropping systems, improved soil fertility). Long-term field experiments have been instrumental to increase our understanding of SOM dynamics. This chapter presents fundamental concepts to guide readers on the role of SOM in sustainable agriculture and climate change mitigation.

  10. The secondary history of Sutter's Mill CM carbonaceous chondrite based on water abundance and the structure of its organic matter from two clasts

    NASA Astrophysics Data System (ADS)

    Beck, P.; Quirico, E.; Garenne, A.; Yin, Q.-Z.; Bonal, L.; Schmitt, B.; Montes-Hernandez, G.; Montagnac, G.; Chiriac, R.; Toche, F.

    2014-11-01

    Sutter's Mill is a regolith breccia composed of both heavily altered clasts and more reduced xenoliths. Here, we present a detailed investigation of fragments of SM18 and SM51. We have characterized the water content and the mineralogy by infrared (IR) and thermogravimetric analysis (TGA) and the structure of the organic compounds by Raman spectroscopy, to characterize the secondary history of the clasts, including aqueous alteration and thermal metamorphism. The three methods used in this study suggest that SM18 was significantly heated. The amount of water contained in phyllosilicates derived by TGA is estimated to be approximately 3.2 wt%. This value is quite low compared with other CM chondrites that typically range from 6 to 12 wt%. The infrared transmission spectra of SM18 show that the mineralogy of the sample is dominated by a mixture of phyllosilicate and olivine. SM18 shows an intense peak at 11.2 μm indicative of olivine (Fig. 1). If we compare SM18 with other CM and metamorphosed CM chondrites, it shows one of the most intense olivine signatures, and therefore a lower proportion of phyllosilicate minerals. The Raman results tend to support a short-duration heating hypothesis. In the ID/IG versus FWHM-D diagram, SM18 appears to be unusual compared to most CM samples, and close to the metamorphosed CM chondrites Pecora Escarpment (PCA) 91008 and PCA 02012. In the case of SM51, infrared spectroscopy reveals that olivine is less abundant than in SM18 and the 10 μm silicate feature is more similar to that of moderately altered CM chondrites (like Murchison or Queen Alexandra Range [QUE] 97990). Raman spectroscopy does not clearly point to a heating event for SM51 in the ID/IG versus FWHM-D diagram. However, TGA analysis suggests that SM51 was slightly dehydrated as the amount of water contained in phyllosilicates is approximately 3.7 wt%, which is higher than SM18, but still lower than phyllosilicate water contents in weakly altered CM chondrites

  11. 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.

  12. N-15 NMR spectra of naturally abundant nitrogen in soil and aquatic natural organic matter samples of the International Humic Substances Society

    USGS Publications Warehouse

    Thorn, K.A.; Cox, L.G.

    2009-01-01

    The naturally abundant nitrogen in soil and aquatic NOM samples from the International Humic Substances Society has been characterized by solid state CP/MAS 15N NMR. Soil samples include humic and fulvic acids from the Elliot soil, Minnesota Waskish peat and Florida Pahokee peat, as well as the Summit Hill soil humic acid and the Leonardite humic acid. Aquatic samples include Suwannee River humic, fulvic and reverse osmosis isolates, Nordic humic and fulvic acids and Pony Lake fulvic acid. Additionally, Nordic and Suwannee River XAD-4 acids and Suwannee River hydrophobic neutral fractions were analyzed. Similar to literature reports, amide/aminoquinone nitrogens comprised the major peaks in the solid state spectra of the soil humic and fulvic acids, along with heterocyclic and amino sugar/terminal amino acid nitrogens. Spectra of aquatic samples, including the XAD-4 acids, contain resolved heterocyclic nitrogen peaks in addition to the amide nitrogens. The spectrum of the nitrogen enriched, microbially derived Pony Lake, Antarctica fulvic acid, appeared to contain resonances in the region of pyrazine, imine and/or pyridine nitrogens, which have not been observed previously in soil or aquatic humic substances by 15N NMR. Liquid state 15N NMR experiments were also recorded on the Elliot soil humic acid and Pony Lake fulvic acid, both to examine the feasibility of the techniques, and to determine whether improvements in resolution over the solid state could be realized. For both samples, polarization transfer (DEPT) and indirect detection (1H-15N gHSQC) spectra revealed greater resolution among nitrogens directly bonded to protons. The amide/aminoquinone nitrogens could also be observed by direct detection experiments.

  13. N-15 NMR spectra of naturally abundant nitrogen in soil and aquatic natural organic matter samples of the International Humic Substances Society

    SciTech Connect

    Thorn, Kevin A.; Cox, Larry G.

    2009-02-28

    The naturally abundant nitrogen in soil and aquatic NOM samples from the International Humic Substances Society has been characterized by solid state CP/MAS ¹⁵N NMR. Soil samples include humic and fulvic acids from the Elliot soil, Minnesota Waskish peat and Florida Pahokee peat, as well as the Summit Hill soil humic acid and the Leonardite humic acid. Aquatic samples include Suwannee River humic, fulvic and reverse osmosis isolates, Nordic humic and fulvic acids and Pony Lake fulvic acid. Additionally, Nordic and Suwannee River XAD-4 acids and Suwannee River hydrophobic neutral fractions were analyzed. Similar to literature reports, amide/aminoquinone nitrogens comprised the major peaks in the solid state spectra of the soil humic and fulvic acids, along with heterocyclic and amino sugar/terminal amino acid nitrogens. Spectra of aquatic samples, including the XAD-4 acids, contain resolved heterocyclic nitrogen peaks in addition to the amide nitrogens. The spectrum of the nitrogen enriched, microbially derived Pony Lake, Antarctica fulvic acid, appeared to contain resonances in the region of pyrazine, imine and/or pyridine nitrogens, which have not been observed previously in soil or aquatic humic substances by ¹⁵N NMR. Liquid state ¹⁵N NMR experiments were also recorded on the Elliot soil humic acid and Pony Lake fulvic acid, both to examine the feasibility of the techniques, and to determine whether improvements in resolution over the solid state could be realized. For both samples, polarization transfer (DEPT) and indirect detection (¹H–¹⁵N gHSQC) spectra revealed greater resolution among nitrogens directly bonded to protons. The amide/aminoquinone nitrogens could also be observed by direct detection experiments.

  14. Factors Regulating Soil Organic Matter Chlorination

    NASA Astrophysics Data System (ADS)

    Svensson, T.; Gustavsson, M.; Reyier, H.; Rietz, K.; Karlsson, S.; Göransson, C.; Andersson, M.; Öberg, G.; Bastviken, D.

    2013-12-01

    Natural chlorination of organic matter is a common process in various soils. Despite the widespread abundance of soil organic chlorine, knowledge on the processes and regulation of soil organic matter chlorination are modest. The purpose of this study is to elucidate how environmental factors may influence chlorination of organic matter in soil. Four factors were chosen for this study; water content, and nitrogen, organic carbon, and chloride concentrations. The variables are all known in different ways as important for microbes and transformation of chlorine in soil. The soil was collected from 5-15 cm depth in a coniferous forest southeast of Sweden. To test how the selected factors influenced chlorination of organic matter, we used soil laboratory incubations using 36Cl-chloride as a radioisotopic marker. A multivariate factorial design with two levels of i) soil moisture, ii) chloride amendment, iii) nitrogen amendment, and iv) glucose and maltose addition was used to simultaneously test for possible combination effects for all factors. A known radioactivity of 36chloride was added to the soil samples and incubated with four different factor treatments during an incubation period of 15 and 60 days. This presentation will discuss the results of this study including what combination of factors enhanced or hampered chlorination and thereby discuss previous observed variability of organic chlorine and chloride in soil.

  15. 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.

  16. The abundance of Kaluza-Klein dark matter with coannihilation

    SciTech Connect

    Burnell, Fiona; Kribs, Graham D.

    2006-01-01

    In universal extra dimension models, the lightest Kaluza-Klein (KK) particle is generically the first KK excitation of the photon and can be stable, serving as particle dark matter. We calculate the thermal relic abundance of the KK photon for a general mass spectrum of KK excitations including full coannihilation effects with all (level-one) KK excitations. We find that including coannihilation can significantly change the relic abundance when the coannihilating particles are within about 20% of the mass of the KK photon. Matching the relic abundance with cosmological data, we find the mass range of the KK photon is much wider than previously found, up to about 2 TeV if the masses of the strongly interacting level-one KK particles are within 5% of the mass of the KK photon. We also find cases where several coannihilation channels compete (constructively and destructively) with one another. The lower bound on the KK photon mass, about 540 GeV when just right-handed KK leptons coannihilate with the KK photon, relaxes upward by several hundred GeV when coannihilation with electroweak KK gauge bosons of the same mass is included.

  17. 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.

  18. 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.

  19. The abundance and environment of dark matter haloes

    NASA Astrophysics Data System (ADS)

    Metuki, Ofer; Libeskind, Noam I.; Hoffman, Yehuda

    2016-07-01

    An open question in cosmology and the theory of structure formation is to what extent does environment affect the properties of galaxies and haloes. The present paper aims at shedding light on this problem. The paper focuses on the analysis of a dark matter only simulation and it addresses the issue of how the environment affects the abundance of haloes, which are assigned four attributes: their virial mass, an ambient density calculated with an aperture that scales with Rvir (ΔM), a fixed-aperture (ΔR) ambient density, and a cosmic web classification (i.e. voids, sheets, filaments, and knots, as defined by the V-web algorithm). ΔM is the mean density around a halo evaluated within a sphere of a radius of 5Rvir, where Rvir is the virial radius. ΔR is the density field Gaussian smoothed with R = 4 h-1 Mpc, evaluated at the centre of the halo. The main result of the paper is that the difference between haloes in different web elements stems from the difference in their mass functions, and does not depend on their adaptive-aperture ambient density. A dependence on the fixed-aperture ambient density is induced by the cross-correlation between the mass of a halo and its fixed-aperture ambient density.

  20. 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.

  1. 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

  2. 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.

  3. Abundance of complex organic molecules in comets

    NASA Astrophysics Data System (ADS)

    Biver, N.; Bockelée-Morvan, D.; Debout, V.; Crovisier, J.; Moreno, R.; Boissier, J.; Lis, D.; Colom, P.; Paubert, G.; Dello Russo, N.; Vervack, R.; Weaver, H.

    2014-07-01

    The IRAM-30m submillimetre radio telescope has now an improved sensitivity and versality thanks to its wide-band EMIR receivers and high-resolution FFT spectrometer. Since 2012, we have undertaken ~70 GHz wide spectral surveys in the 1-mm band in several comets: C/2009 P1 (Garradd), C/2011 L4 (PanSTARRS), C/2012 F6 (Lemmon), C/2012 S1 (ISON), and C/2013 R1 (Lovejoy). Since their discovery in comet C/1995 O1 (Hale-Bopp) in 1997 (Bockelée-Morvan et al. 2000, Crovisier et al. 2004a, 2004b), we have detected complex CHO(N)-molecules such as formic acid (HCOOH), formamide (NH_2CHO), acetaldehyde (CH_3CHO), and ethylene glycol ((CH_2OH)_2) in several other comets. HCOOH has now been detected in 6 other comets since 2004, and formamide, ethylene glycol, and acetaldehyde were re-detected for the first time in comets Lemmon or Lovejoy in 2013 (Biver et al. 2014). We will present the abundances relative to water we derive for these species, and the sensitive upper limits we obtain for other complex CHO-bearing molecules. We will discuss the implication of these findings on the origin of cometary material in comparison with observations of such molecules in the interstellar medium.

  4. Effects of earthworms and plants on the soil structure, the physical stabilization of soil organic matter and the microbial abundance and diversity in soil aggregates in a long term study

    NASA Astrophysics Data System (ADS)

    Zangerlé, Anne; Hissler, Christophe; Lavelle, Patrick

    2014-05-01

    Earthworms and plant roots, as ecosystem engineers, have large effects on biotic and abiotic properties of the soil system. They create biogenic soil macroaggregates (i.e. earthworm casts and root macroaggregates) with specific physical, chemical and microbiological properties. Research to date has mainly considered their impacts in isolation thereby ignoring potential interactions between these organisms. On the other hand, most of the existing studies focused on short to midterm time scale. We propose in this study to consider effect of earthworms and plants on aggregate dynamics at long time scale. A 24 months macrocosm experiment, under semi-controlled conditions, was conducted to assess the impacts of corn and endogeic plus anecic earthworms (Apporectodea caliginosa and Lumbricus terrestris) on soil structure, C stabilization and microbial abundance and biodiversity. Aggregate stability was assessed by wet-sieving. Macroaggregates (>2 mm) were also visually separated according to their biological origin (e.g., earthworms, roots). Total C and N contents were measured in aggregates of all size classes and origins. Natural abundances of 13C of corn, a C4 plant, were used as a supplemental marker of OM incorporation in aggregates. The genetic structure and the abundance of the bacterial and fungal communities were characterized by using respectively the B- and F-ARISA fingerprinting approach and quantitative PCR bacteria (341F/515R) and fungi (FF330/FR1). They significantly impacted the soil physical properties in comparison to the other treatments: lower bulk density in the first 10cm of the soil with 0.95 g/cm3 in absence of corn plants and 0.88 g/cm3 in presence of corn plants compared to control soil (1.21g/cm3). The presence of earthworms increased aggregate stability (mean weight diameter) by 7.6 %, while plants alone had no simple impacts on aggregation. A significant interaction revealed that earthworms increased aggregate stability in the presence of

  5. 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

  6. Distribution and abundance of organic thiols

    NASA Technical Reports Server (NTRS)

    Fahey, R.

    1985-01-01

    The role of glutathione (GSH) in protecting against the toxicity of oxygen and oxygen by products is well established for all eukaryotes studied except Entamoeba histolytica which lacks mitochrondria, chloroplasts, and microtubules. The GSH is not universal among prokaryotes. Entamoeba histolytica does not produce GSH or key enzymes of GSH metabolism. A general method of thiol analysis based upon fluorescent labeling with monobromobimane and HPLC separation of the resulting thiol derivatives was developed to determine the occurrence of GSH and other low molecular weight thiols in bacteria. Glutathione is the major thiol in cyanobacteria and in most bacteria closely related to the purple photosynthetic bacteria, but GSH was not found in archaebacteria, green bacteria, or GRAM positive bacteria. It suggested that glutathione metabolism was incorporated into eukaryotes at the time that mitochondria and chloroplasts were acquired by endosymbiosis. In Gram positive aerobes, coenzyme A occurs at millimolar levels and CoA disulfide reductases are identified. The CoA, rather than glutathione, may function in the oxygen detoxification processes of these organisms.

  7. 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

  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. 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.

  10. Soil organic matter contribution to the NW Mediterranean (Invited)

    NASA Astrophysics Data System (ADS)

    Kim, J.; Buscail, R.; Blokker, J.; Kerhervé, P.; Schouten, S.; Ludwig, W.; Sinninghe Damsté, J. S.

    2009-12-01

    The BIT (Branched and Isoprenoid Tetraether) index has recently been introduced as a proxy for soil organic matter input and is based on the relative abundance of non-isoprenoidal glycerol dialkyl glycerol tetraethers (GDGTs) derived from organisms living in terrestrial environments versus a structurally related isoprenoid GDGT “crenarchaeol” produced by marine Crenarchaeota (Hopmans et al., 2004). In this study, detailed spatial distribution patterns of BIT index were investigated in combination with other organic parameters in the continental margin of the north western Mediterranean. Based on a transect sampling strategy from source (land) to sink (sea) via river, we analysed a variety of soils from the Têt and Rhône basins, suspended particulate matter in waters of the Têt and Rhône rivers flowing into the Gulf of Lions, and marine surface sediments from the Gulf of Lions collected before and after a flood occurred in June 2008. Our study allows us to track BIT values along the transport pathway of soil organic matter and thus to estimate soil organic matter contribution in marine sediments in the Gulf of Lions (NW Mediterranean), a river-dominated continental margin. Hopmans, E.C., Weijers, J.W.H., Schefuss, E., Herfort, L., Sinninghe Damsté, J.S., Schouten, S., 2004. A novel proxy for terrestrial organic matter in sediments based on branched and isoprenoidtetraether lipids. Earth and Planetary Science Letters 224, 107-116.

  11. 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.

  12. Contribution of plant lignin to the soil organic matter formation and stabilization

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Lignin is the third most abundant plant constituent after cellulose and hemicellulose and thought to be one of the building blocks for soil organic matter formation. Lignin can be used as a predictor for long-term soil organic matter stabilization and C sequestration. Soils and humic acids from fo...

  13. 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.

  14. 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.

  15. 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.

  16. Fractionation of halogenated organic matter present in rain and snow

    PubMed

    Laniewski; Boren; Grimvall

    1999-01-01

    Organic matter in samples of rain and snow from Sweden, Poland, Germany and the Republic of Ireland was fractionated by employing a series of filtration, purging, evaporation and extraction steps. Determinations of the group parameter AOX (adsorbable organic halogens) in aqueous phases and EOX (extractable organic halogens) in organic phases showed that halogenated organic matter present in bulk precipitation is composed of several different groups of compounds. The largest amounts of organically bound halogens were found in fractions of relatively polar and non-volatile to semivolatile compounds. In particular, a significant part of the AOX could be attributed to alkaline-labile organic bases. Gas chromatographic analysis of different organic extracts in the chlorine channel of an atomic emission detector (AED) resulted in chromatograms with few distinct peaks, and analysis in the bromine channel did not produce any distinct peaks. Chlorinated acetic acids were the most abundant halogenated organic acids, and chlorinated alkyl phosphates were normally responsible for the largest peaks in the chlorine chromatogram of neutral, hexane-extractable compounds. When analysing volatiles, 1,4-dichlorobenzene and a thus far unidentified chloroorganic compound often caused the largest response in the chlorine channel of the AED system.

  17. Organic matter variations in transgressive and regressive shales

    USGS Publications Warehouse

    Pasley, M.A.; Gregory, W.A.; Hart, G.F.

    1991-01-01

    Organic matter in the Upper Cretaceous Mancos Shale adjacent to the Tocito Sandstone in the San Juan Basin of New Mexico was characterized using organic petrology and organic geochemistry. Differences in the organic matter found in these regressive and transgressive offshore marine sediments have been documented and assessed within a sequence stratigraphic framework. The regressive Lower Mancos Shale below the Tocito Sandstone contains abundant well preserved phytoclasts and correspondingly low hydrogen indices. Total organic carbon values for the regressive shale are low. Sediments from the transgressive systems tract (Tocito Sandstone and overlying Upper Mancos Shale) contain less terrestrially derived organic matter, more amorphous non-structured protistoclasts, higher hydrogen indices and more total organic carbon. Advanced stages of degradation are characteristic of the phytoclasts found in the transgressive shale. Amorphous material in the transgressive shale fluoresces strongly while that found in the regressive shale is typically non-fluorescent. Data from pyrolysis-gas chromatography confirm these observations. These differences are apparently related to the contrasting depositional styles that were active on the shelf during regression and subsequent transgression. It is suggested that data from organic petrology and organic geochemistry provide greater resolution in sedimentologic and stratigraphic interpretations, particularly when working with basinward, fine-grained sediments. Petroleum source potential for the regressive Lower Mancos Shale below the Tocito Sandstone is poor. Based on abundant fluorescent amorphous material, high hydrogen indices, and high total organic carbon, the transgressive Upper Mancos Shale above the Tocito Sandstone possesses excellent source potential. This suggests that appreciable source potential can be found in offshore, fine-grained sediments of the transgressive systems tract below the condensed section and associated

  18. Differences in spectroscopic characteristics between dissolved and particulate organic matters in sediments: Insight into distribution behavior of sediment organic matter.

    PubMed

    He, Wei; Jung, Heonjae; Lee, Jong-Hyun; Hur, Jin

    2016-03-15

    In this study, we examined the distribution behavior of sediment organic matter (SOM) between dissolved and particulate phases and the potential influencing factors by comparing the spectroscopic features of pore water organic matter (PWOM) and alkaline-extractable organic matter (AEOM) of river sediments. The characteristics of SOM were described by several selected spectral indicators and fluorescence excitation emission matrix (EEM)-parallel factor analysis (PARAFAC). The spectral indicators showed that larger sized SOM molecules with a higher aromatic content were more enriched in sediment particles than in pore water. The relative ratios of humification index between dissolved and particulate phases revealed that the SOM constituents with a higher degree of structural condensation were preferentially distributed onto sediment particles. EEM-PARAFAC demonstrated different distribution behaviors of protein-like (tyrosine-like and tryptophan-like) and humic-like substances in sediments. The relative abundance of tyrosine-like component was much higher in PWOM than in AEOM, whereas the other three components tended to be more abundant in AEOM. The predominant presence of tyrosine-like component suggests its potential operation as a discriminant indicator between PWOM and AEOM. Spearman correlations and non-metric multidimensional scaling further revealed that distribution of protein-like components onto sediment particles might be associated with reductive environments, aluminum minerals, and anthropogenic activities of upstream watersheds. This study demonstrated a successful application of using EEM-PARAFAC to examine the distribution behavior of different SOM constitutes between dissolved and solid phases.

  19. 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.

  20. The Role of Electroweak Corrections for the Dark Matter Relic Abundance

    SciTech Connect

    Ciafaloni, Paolo; Comelli, Denis; Simone, Andrea De; Morgante, Enrico; Riotto, Antonio; Urbano, Alfredo E-mail: comelli@fe.infn.it E-mail: enrico.morgante@unige.ch E-mail: alfredo.urbano@sissa.it

    2013-10-01

    We analyze the validity of the theorems concerning the cancellation of the infrared and collinar divergences in the case of dark matter freeze-out in the early universe. In particular, we compute the electroweak logarithmic corrections of infrared origin to the annihilation cross section of a dark matter particle being the neutral component of a SU(2){sub L} multiplet. The inclusion of processes with final state W can modify significantly the cross sections computed with only virtual W exchange. Our results show that the inclusion of infrared logs is necessary for a precise computation of the dark matter relic abundance.

  1. 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.)

  2. 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.

  3. 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.

  4. Stable carbon isotope ratios of rock varnish organic matter: a new paleoenvironmental indicator.

    PubMed

    Dorn, R I; Deniro, M J

    1985-03-22

    Stable carbon isotope ratios of organic matter in rock varnishes of Holocene age from western North America and the Middle East show a strong association with the environment. This isotopic variability reflects the abundance of plants with different photosynthetic pathways in adjacent vegetation. Analyses of different layers of varnish on late Pleistocene desert landforms indicate that the carbon isotopic composition of varnish organic matter is a paleoenvironmental indicator. PMID:17777781

  5. Stable carbon isotope ratios of rock varnish organic matter: a new paleoenvironmental indicator.

    PubMed

    Dorn, R I; Deniro, M J

    1985-03-22

    Stable carbon isotope ratios of organic matter in rock varnishes of Holocene age from western North America and the Middle East show a strong association with the environment. This isotopic variability reflects the abundance of plants with different photosynthetic pathways in adjacent vegetation. Analyses of different layers of varnish on late Pleistocene desert landforms indicate that the carbon isotopic composition of varnish organic matter is a paleoenvironmental indicator.

  6. Subaerial weathering of sedimentary organic matter

    USGS Publications Warehouse

    Clayton, J.L.; Swetland, P.J.

    1978-01-01

    Small diameter core samples were taken from outcrops of the Permian Phosphoria Formation and the Cretaceous Pierre Shale of the Western United States to determine the effects of weathering on organic matter in shale outcrops. While the Pierre Shale core showed no evidence of weathering, the Phosphoria Formation showed significant reduction of overall organic content and pronounced changes in organic composition over the near-surface interval of the core. Total organic carbon is lower by as much as 60% over the upper 2 ft of the core. Chloroform-soluble organic matter and total hydrocarbon (C15+) concentrations are 50% lower over this same interval. The ratio of saturated to aromatic hydrocarbons decreases steadily with core depth over the upper 2.6 ft of the core. Aromatic hydrocarbons are enriched in the stable carbon-13 isotope by an average of 1.7%. over this same interval. Shallow core samples also show a loss of n-paraffins relative to branched/cyclic compounds in the saturated C15+ fraction. Although the extent of weathering is variable, certain characteristic effects are recognizable and can be applied to the interpretation of outcrop data in organic geochemical studies. ?? 1978.

  7. 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.

  8. Isotopic analysis of cometary organic matter

    NASA Astrophysics Data System (ADS)

    Kerridge, J. F.

    1991-04-01

    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.

  9. 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.

  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. Nondestructive, in situ, cellular-scale mapping of elemental abundances including organic carbon in permineralized fossils

    PubMed Central

    Boyce, C. K.; Hazen, R. M.; Knoll, A. H.

    2001-01-01

    The electron microprobe allows elemental abundances to be mapped at the μm scale, but until now high resolution mapping of light elements has been challenging. Modifications of electron microprobe procedure permit fine-scale mapping of carbon. When applied to permineralized fossils, this technique allows simultaneous mapping of organic material, major matrix-forming elements, and trace elements with μm-scale resolution. The resulting data make it possible to test taphonomic hypotheses for the formation of anatomically preserved silicified fossils, including the role of trace elements in the initiation of silica precipitation and in the prevention of organic degradation. The technique allows one to understand the localization of preserved organic matter before undertaking destructive chemical analyses and, because it is nondestructive, offers a potentially important tool for astrobiological investigations of samples returned from Mars or other solar system bodies. PMID:11371632

  12. 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

  13. Matrix protected organic matter in a river dominated margin: A possible mechanism to sequester terrestrial organic matter?

    NASA Astrophysics Data System (ADS)

    Mead, Ralph N.; Goñi, Miguel A.

    2008-06-01

    The provenance of organic matter in surface sediments from the northern Gulf of Mexico was investigated by analyzing the compositions of lipid biomarkers ( n-alkanes, fatty acids, sterols) liberated after a series of chemical treatments designed to remove different organo-mineral matrix associations (i.e. freely extractable, base-hydrolyzable, unhydrolyzable). Bulk analyses of the organic matter (carbon content, carbon:nitrogen ratios, stable and radiocarbon isotopic analyses) were also performed on the intact sediments and their non-hydrolyzable, demineralized residue. We found recognizable lipids from distinct sources, including terrestrial vascular plants, bacteria and marine algae and zooplankton, within each of the isolated fractions. Based on the lipid signatures and bulk compositions, the organic matter within the unhydrolyzable fractions appeared to be the most diagenetically altered, was the oldest in age, and had the highest abundance of terrigenous lipids. In contrast, the base-hydrolyzable fraction was the most diagentically unaltered, had the youngest ages and was most enriched in N and marine lipids. Our results indicate that fresh, autochthonous organic matter is the most important contributor to base-hydrolyzable lipids, whereas highly altered allochthonous sources appear to be predominant source of unhydrolyzable lipids in the surface sediments from the Atchafalaya River shelf. Overall, the lipid biomarker signatures of intact sediments were biased towards the autochthonous source because many of the organic compounds indicative of degraded, terrigenous sources were protected from extraction and saponification by organo-mineral matrices. It is only after these protective matrices were removed by treatment with HCl and HF that these compounds became evident.

  14. Enhancement of the natural organic matter removal from drinking water by nanofiltration.

    PubMed

    Matilainen, A; Liikanen, R; Nyström, M; Lindqvist, N; Tuhkanen, T

    2004-03-01

    Finnish surface waters are abundant in natural organic matter. Natural organic matter can be removed from drinking water in a water treatment process by coagulation and filtration. The standard treatment operations are not able to remove the smallest molar mass fraction of organic matter and the intermediate molar mass matter is only partly removed. The removal of residual natural organic matter from drinking water by nanofiltration was evalueted in this study. Three different nanofiltration membranes were compared in filtering six pre-treated surface waters. The total organic carbon content of the feed waters varied from 2.0 to 4.2 mg l(-1). Other water quality parameters measured were conductivity, alkalinity, hardness, UV-absorbance, SUVA, E2/E3 value and molecular size distribution by high-performance size-exclusion chromatography. The natural organic matter removal efficiencies of the membranes were good and varied between 100% and 49%, and between 85% and 47% according to molecular size distribution and total organic carbon measurements, respectively. Removal of different molecular size fractions varied from 100% to 56%, 100% to 54% and 88% to 19%, regarding high molar mass, intermediate molar mass and low molar mass organic matter, respectively. The Desal-5 DL membrane produced the highest natural organic matter removals.

  15. 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.

  16. 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...

  17. Factors controlling the abundance of organic sulfur in flash pyrolyzates of Upper Cretaceous kerogens from Sergipe Basin, Brazil

    USGS Publications Warehouse

    Carmo, A.M.; Stankiewicz, B.A.; Mastalerz, Maria; Pratt, L.M.

    1997-01-01

    The molecular and elemental composition of immature kerogens isolated from Upper Cretaceous marine carbonates from Sergipe Basin, Brazil were investigated using combined pyrolysis-gas chromatography/mass spectrometry and organic petrographic techniques. The kerogens are predominantly composed of reddish-fluorescing amorphous organic matter (AOM) and variable amounts of yellow-fluorescing alginite and liptodetrinite. The abundance of organic sulfur in the kerogens inferred from the ratio 2-ethyl-5-methylthiophene/(1,2-dimethylbenzene + dec-1-ene) in the pyrolyzates is variable and may be related to changes in the type of primary organic input and/or to variations in rates of bacterial sulfate reduction. A concomitant increase in S/C and O/C ratios determined in situ using the electron microprobe is observed in AOM and alginites and may be related to a progressive oxidation of the organic matter during sulfurization. The S/C ratio of the AOM is systematically higher than the S C ratio of the alginites. Combined with a thiophene distribution characteristic of pyrolyzates of Type II organic matter, the higher S/C of AOM in Sergipe kerogens suggests that sulfurization and incorporation of low-molecular weight lipids derived from normal marine organic matter into the kerogen structure predominated over direct sulfurization of highly aliphatic algal biomacromolecules.The molecular and elemental composition of immature kerogens isolated from Upper Cretaceous marine carbonates from Sergipe Basin, Brazil were investigated using combined pyrolysis-gas chromatography/mass spectrometry and organic petrographic techniques. The kerogens are predominantly composed of reddish-fluorescing amorphous organic matter (AOM) and variable amounts of yellow-fluorescing alginite and liptodetrinite. The abundance of organic sulfur in the kerogens inferred from the ratio 2-ethyl-5-methylthiophene/(1,2-dimethylbenzene+dec-1-ene) in the pyrolyzates is variable and may be related to changes in

  18. 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.

  19. The surface area of soil organic matter

    USGS Publications Warehouse

    Chiou, C.T.; Lee, J.-F.; Boyd, S.A.

    1990-01-01

    The previously reported surface area for soil organic matter (SOM) of 560-800 m2/g as determined by the ethylene glycol (EG) retention method was reexamined by the standard BET method based on nitrogen adsorption at liquid nitrogen temperature. Test samples consisted of two high organic content soils, a freeze-dried soil humic acid, and an oven-dried soil humic acid. The measured BET areas for these samples were less than 1 m2/g, except for the freeze-dried humic acid. The results suggest that surface adsorption of nonionic organic compounds by SOM is practically insignificant in comparison to uptake by partition. The discrepancy between the surface areas of SOM obtained by BET and EG methods was explained in terms of the 'free surface area' and the 'apparent surface area' associated with these measurements.The previously reported surface area for soil organic matter (SOM) of 560-800 m2/g as determined by the ethylene glycol (EG) retention method was reexamined by the standard BET method based on nitrogen adsorption at liquid nitrogen temperature. Test samples consisted of two high organic content soils, a freeze-dried soil humic acid, and an oven-dried soil humic acid. The measured BET areas for these samples were less than 1 m2/g, except for the freeze-dried humic acid. The results suggest that surface adsorption of nonionic organic compounds by SOM is practically insignificant in comparison to uptake by partition. The discrepancy between the surface areas of SOM obtained by BET and EG methods was explained in terms of the 'free surface area' and the 'apparent surface area' associated with these measurements.

  20. Estimating the global abundance of ground level presence of particulate matter (PM2.5).

    PubMed

    Lary, David J; Faruque, Fazlay S; Malakar, Nabin; Moore, Alex; Roscoe, Bryan; Adams, Zachary L; Eggelston, York

    2014-12-01

    With the increasing awareness of the health impacts of particulate matter, there is a growing need to comprehend the spatial and temporal variations of the global abundance of ground level airborne particulate matter with a diameter of 2.5 microns or less (PM2.5). Here we use a suite of remote sensing and meteorological data products together with ground-based observations of particulate matter from 8,329 measurement sites in 55 countries taken 1997-2014 to train a machine-learning algorithm to estimate the daily distributions of PM2.5 from 1997 to the present. In this first paper of a series, we present the methodology and global average results from this period and demonstrate that the new PM2.5 data product can reliably represent global observations of PM2.5 for epidemiological studies.

  1. Organic geochemical analysis of sedimentary organic matter associated with uranium

    USGS Publications Warehouse

    Leventhal, J.S.; Daws, T.A.; Frye, J.S.

    1986-01-01

    Samples of sedimentary organic matter from several geologic environments and ages which are enriched in uranium (56 ppm to 12%) have been characterized. The three analytical techniqyes used to study the samples were Rock-Eval pyrolysis, pyrolysis-gas chromatography-mass spectrometry, and solid-state C-13 nuclear magnetic resonance (NMR) spectroscopy. In samples with low uranium content, the pyrolysis-gas chromatography products contain oxygenated functional groups (as hydroxyl) and molecules with both aliphatic and aromatic carbon atoms. These samples with low uranium content give measurable Rock-Eval hydrocarbon and organic-CO2 yields, and C-13 NMR values of > 30% aliphatic carbon. In contrast, uranium-rich samples have few hydrocarbon pyrolysis products, increased Rock-Eval organic-CO2 contents and > 70% aromatic carbon contents from C-13 NMR. The increase in aromaticity and decrease in hydrocarbon pyrolysis yield are related to the amount of uranium and the age of the uranium minerals, which correspond to the degree of radiation damage. The three analytical techniques give complementary results. Increase in Rock-Eval organic-CO2 yield correlates with uranium content for samples from the Grants uranium region. Calculations show that the amount of organic-CO2 corresponds to the quantity of uranium chemically reduced by the organic matter for the Grants uranium region samples. ?? 1986.

  2. Fluorescent organic matter in carbonaceous chondrites.

    PubMed

    Murae, T

    1999-01-01

    Fluorescent organic matter in carbonaceous chondrites was investigated using a microscope equipped with a fluorescence spectrophotometer. Fluorescent particles were observed in powdered CM2 carbonaceous chondrites (Y-74662, Y-7791198, and Murchison) without carbon enrichment by acid treatments. Although it was difficult to find fluorescent particles in powdered sample of C3 chondrites (ALH-77307, Y-791717, and Allende) without acid treatments, many fluorescent particles were observed after carbon enrichment by acid treatments. Fluorescence of coronene and shock-altered graphite were observed using the same microscope and the same conditions as those for carbonaceous chondrites.

  3. 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

  4. 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

  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. 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

  7. [Dynamics of organic matter decomposition and microflora composition of forest litter in artificial biogeocenoses].

    PubMed

    Mukhortova, L V; Evgrafova, S Iu

    2005-01-01

    The dynamics of litter stock, microbial biomass, and composition and structure of microbial communities, were studied in the course of soil organic matter transformation during vegetation season. The dynamics of litter stock in coniferous and deciduous forests proved to correlate with the biomass and total abundance of microorganisms, particularly, with the proportion of microfungi in the microbial community.

  8. The Origin of Organic Matter in the Solar System: Evidence from Interplanetary Dust Particles

    NASA Technical Reports Server (NTRS)

    Flynn, G. J.; Keller, L. P.; Jacobsen, C.; Wirick, S.

    2001-01-01

    The origin of the organic matter in interplanetary materials has not been established. A variety of mechanisms have been proposed, with two extreme cases being a Fisher-Tropsch type process operating in the gas phase of the solar nebula or a Miller-Urey type process, which requires interaction with an aqueous fluid, presumably occurring on an asteroid. In the Fisher-Tropsch case, we might expect similar organic matter in hydrated and anhydrous interplanetary materials. However, aqueous alteration is required in the case of the Miller-Urey process, and we would expect to see organic matter preferentially in interplanetary materials that exhibit evidence of aqueous activity, such as the presence of hydrated silicates. The types and abundance of organic matter in meteorites have been used as an indicator of the origin of organic matter in the Solar System. Indigenous complex organic matter, including amino acids, has been found in hydrated carbonaceous chondrite meteorites, such as Murchison. Much lower amounts of complex organic matter, possibly only terrestrial contamination, have been found in anhydrous carbonaceous chondrite meteorites, such as Allende, that contain most of their carbon in elemental form. These results seem to favor production of the bulk of the organic matter in the Solar System by aqueous processing on parent bodies such as asteroids, a Miller-Urey process. However, the hydrated carbonaceous chondrite meteorites have approximately solar abundances of the moderately volatile elements, while all anhydrous carbonaceous chondrite meteorites have significantly lower contents of these moderately volatile elements. Two mechanisms, incomplete condensation or evaporation, both of which involve processing at approx. 1200 C, have been suggested to explain the lower content of the moderately volatile elements in all anhydrous meteorites. Additional information is contained in the original extended abstract.

  9. 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.

  10. Dissolved organic matter photolysis in Canadian arctic thaw ponds

    NASA Astrophysics Data System (ADS)

    Laurion, Isabelle; Mladenov, Natalie

    2013-09-01

    The abundant thaw lakes and ponds in the circumarctic receive a new pool of organic carbon as permafrost peat soils degrade, which can be exposed to significant irradiance that potentially increases as climate warms and ice cover shortens. Exposure to sunlight is known to accelerate the transformation of dissolved organic matter (DOM) into molecules that can be more readily used by microbes. We sampled the water from two common classes of ponds found in the ice-wedge system of continuous permafrost regions of Canada, polygonal and runnel ponds, and followed the transformation of DOM over 12 days by looking at dissolved organic carbon (DOC) concentration and DOM absorption and fluorescence properties. The results indicate a relatively fast decay of color (3.4 and 1.6% loss d-1 of absorption at 320 nm for the polygonal and runnel pond, respectively) and fluorescence (6.1 and 8.3% loss d-1 of total fluorescent components, respectively) at the pond surface, faster in the case of humic-like components, but insignificant losses of DOC over the observed period. This result indicates that direct DOM mineralization (photochemical production of CO2) is apparently minor in thaw ponds compared to the photochemical transformation of DOM into less chromophoric and likely more labile molecules with a greater potential for microbial mineralization. Therefore, DOM photolysis in arctic thaw ponds can be considered as a catalytic mechanism, accelerating the microbial turnover of mobilized organic matter from thawing permafrost and the production of greenhouse gases, especially in the most shallow ponds. Under a warming climate, this mechanism will intensify as summers lengthen.

  11. Dilaton dominance in the early universe dilutes dark matter relic abundances

    SciTech Connect

    Lahanas, A. B.

    2011-05-15

    The role of the dilaton field and its coupling to matter may result in a dilution of dark matter (DM) relic densities. This is to be contrasted with quintessence scenarios in which relic densities are augmented, due to modification of the expansion rate, since the Universe is not radiation dominated at DM decoupling. The dilaton field, besides this, affects relic densities through its coupling to dust which tends to decrease relic abundances. Thus two separate mechanisms compete with each other resulting, in general, in a decrease of the relic density. This feature may be welcomed and can help the situation if direct dark matter experiments point towards small neutralino-nucleon cross sections, implying small neutralino annihilation rates and hence large relic densities, at least in the popular supersymmetric scenarios. In the presence of a diluting mechanism, both experimental constraints can be met. The role of the dilaton for this mechanism has been studied in the context of the noncritical string theory but in this work we follow a rather general approach assuming that the dilaton dominates only at early eras long before big bang nucleosynthesis.

  12. Bacteria-organic matter coupling and its significance for oceanic carbon cycling.

    PubMed

    Azam, F; Smith, D C; Steward, G F; Hagström, A

    1994-09-01

    This paper synthesizes current ideas on the role of the microbial loop in carbon fluxes in the ocean and proposes some directions for future research. Organic matter flux into bacteria is highly variable, which can significantly influence the pathways of carbon flow in the ocean. A goal for future research is to elucidate the mechanistic bases of bacteria-organic matter coupling. This research should take into consideration the micrometer-scale distribution of bacteria and the composition, structure, and dynamics of the organic matter field in the bacterium's microhabitat. The ideas on the interactions of bacteria with the particulate organic phase need to be revised in view of recent findings of highly abundant, previously unknown particles ranging in size from nanometers to hundreds of micrometers. The "hot-spots" in the distribution of organic matter and remineralized nutrients can influence the rates as well as the direction of biogeochemical fluxes. Slow-to-degrade dissolved organic matter (DOM) may be produced because of loose bacteria-organic matter coupling resulting in DOM storage. Its use at a later time and place has profound implications for carbon fluxes and food web dynamics. A fundamental research need for the future is to understand the ecological interactions among the members of the microbial loop in an appropriate microhabitat context. While this goal was previously intractable, new molecular and optical techniques should make it possible to understand the biogeochemical activities of the microbial loop in terms of the ecology and evolution of pelagic microbial communities.

  13. Influence of paleoenvironmental factors on preservation of organic matter in Middle Cretaceous Greenhorn formation, Pueblo Colorado

    SciTech Connect

    Pratt, L.M.

    1984-09-01

    Sedimentological and geochemical studies of the Upper Cretaceous Hartland Shale and overlying Bridge Creek Limestone Members of the Greenhorn Formation reveal close associations between abundance of current-induced sedimentary structures, extent of bioturbation, and type of preserved organic matter. Abundant hydrogen-rich organic matter (4-5 wt. %) and low sulfur to organic carbon ratios are characteristic of the laminated facies, which lack current-induced sedimentary structures. Sparse hydrogen-poor organic matter (0.1-0.5 wt. %) and relatively high sulfur to organic carbon ratios are characteristic of the bioturbated facies, which contain numerous sedimentary structures indicative of current. The concentration of oxygen in the benthic environment and the degree of bioturbation of the sediment apparently were determined principally by the rate that oxygen was supplied advectively (by currents) rather than by the rate of oxygen consumption (by decomposition). It is proposed that episodes of high river discharge lead to density stratification of the water column and in turn to quiescent oxygen-depleted bottom water and high preservation of organic matter, thus accounting for the intermittent widespread deposition of organic-rich strata during maximum transgression and depth of the Greenhorn sea. The lateral association of voluminous deltaic deposits with deep-water black shales in other elongate or restricted marine basins may have causes similar to those envisioned for the Hartland Shale and Bridge Creek Limestone Members.

  14. 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

  15. 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

  16. Insights into the nature of cometary organic matter from terrestrial analogues

    NASA Astrophysics Data System (ADS)

    Court, Richard W.; Sephton, Mark A.

    2012-04-01

    The nature of cometary organic matter is of great interest to investigations involving the formation and distribution of organic matter relevant to the origin of life. We have used pyrolysis-Fourier transform infrared (FTIR) spectroscopy to investigate the chemical effects of the irradiation of naturally occurring bitumens, and to relate their products of pyrolysis to their parent assemblages. The information acquired has then been applied to the complex organic matter present in cometary nuclei and comae. Amalgamating the FTIR data presented here with data from published studies enables the inference of other comprehensive trends within hydrocarbon mixtures as they are progressively irradiated in a cometary environment, namely the polymerization of lower molecular weight compounds; an increased abundance of polycyclic aromatic hydrocarbon structures; enrichment in 13C; reduction in atomic H/C ratio; elevation of atomic O/C ratio and increase in the temperature required for thermal degradation. The dark carbonaceous surface of a cometary nucleus will display extreme levels of these features, relative to the nucleus interior, while material in the coma will reflect the degree of irradiation experienced by its source location in the nucleus. Cometary comae with high methane/water ratios indicate a nucleus enriched in methane, favouring the formation of complex organic matter via radiation-induced polymerization of simple precursors. In contrast, production of complex organic matter is hindered in a nucleus possessing a low methane/water ration, with the complex organic matter that does form possessing more oxygen-containing species, such as alcohol, carbonyl and carboxylic acid functional groups, resulting from reactions with hydroxyl radicals formed by the radiolysis of the more abundant water. These insights into the properties of complex cometary organic matter should be of particular interest to both remote observation and space missions involving in situ

  17. Spectrophotometric discrimination of river dissolved organic matter

    NASA Astrophysics Data System (ADS)

    Baker, Andy

    2002-11-01

    There is a need to be able to differentiate the dissolved organic matter (DOM) fraction in river waters. Research in the 1970s and 1980s has attempted to utilize both absorbance and fluorescence to distinguish between DOM fractions in river waters, but both were limited by the available technology. Total organic carbon content has, therefore, been widely used as a standard method of measuring DOM concentration, although it has little power to differentiate DOM fractions. Recent advances in fluorescence spectrophotometry enable rapid and optically precise analysis of DOM. Here, we show how a combination of both fluorescence and absorbance can be used to discriminate statistically between spatial variations of DOM in tributaries in a small catchment of the Ouseburn, NE England. The results of the discriminant analysis suggest that about 70% of the samples can be correctly classified to its tributary. Discriminant function 1 explains 60·8% of the variance in the data and the fulvic-like fluorescence intensity has the largest absolute correlation within this function; discriminant function 2 explains a further 21·5% of the variance and the fulvic-like fluorescence emission wavelength has the largest absolute correlation within this function. The discriminant analysis does not correctly classify all tributaries every time, and successfully discriminates between the different tributaries 70% of the time. Occasions when the tributary waters are less well discriminated are due to either episodic pollution events (at two sites) or due to tributaries that have strong seasonal trends in spectrophotometric parameters, which allows the sites to be misclassified. Results suggest that spectrophotometric techniques have considerable potential in the discrimination of DOM in rivers.

  18. 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.

  19. Sources of organic matter for intertidal consumers on Ascophyllum-shores (SW Iceland): a multi-stable isotope approach

    NASA Astrophysics Data System (ADS)

    Sarà, G.; de Pirro, M.; Romano, C.; Rumolo, P.; Sprovieri, M.; Mazzola, A.

    2007-12-01

    Stable isotopes were used to examine the origin of organic matter in Icelandic Ascophyllum-based habitats, the role of different organic matters in filling intertidal food webs and the food preferences of the most abundant suspension feeders, grazers and predators. We selected three intertidal sites on the SW coast of Iceland where we sampled in early September 2004, organic matter sources (POM, SOM and most abundant primary producers, A. nodosum and F. vesciculosus) and the most abundant macrofauna species (barnacles, mussels, gastropods, sponge and crabs). Even though the primary production ( Ascophyllum-based) was the same at the three study sites, the isotopic composition of common-among-sites organisms varied due to local differences in the origin of available POM and SOM and in food web structures.

  20. Diagenesis of marine and lacustrine organic matter during sinking and after sedimentation

    SciTech Connect

    Meyers, P.A. . Dept. of Geological Sciences)

    1992-01-01

    The abundance and composition of organic matter in sediments is part of the geological record of aquatic conditions and biological communities of the present and the past. Sediment trap studies have shown that only a small fraction of the original amount of organic matter produced in the photic zone survives destruction and alteration during sinking to the bottoms of lakes and oceans, however. Susceptibility to degradation varies among the wide spectrum of molecular types comprising organic matter. Selective losses modify the character of the surviving small fraction of organic matter which becomes incorporated in bottom sediments. Drilled cores of marine and freshwater sediments have revealed that continued alterations occur to organic matter to sub-bottom depths of hundreds of meters, corresponding to millions of years. Despite the many potential modifications which could be imposed on bulk organic matter, source and paleoenvironmental information remains preserved in the molecular, elemental, and isotopic compositions of some of its components. Bulk C/N values and [delta]C-13 values, for example, appear to retain source signatures which, after some early diagenetic modifications.

  1. 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

  2. Sources of organic matter in Ria Formosa revealed by stable isotope analysis

    NASA Astrophysics Data System (ADS)

    Machás, Raquel; Santos, Rui

    1999-07-01

    The aim of this study is to assess the major sources of organic matter for macroconsumers in the Ria Formosa tidal lagoon. The C, S and N isotopic natural abundances of abundant primary producers of particulate organic matter (POM) and Mytilus galloprovincialis muscle and digestive gland were analysed. The chlorophyll a (Chl a), the suspended particulate matter (SPM) and the POM were measured along the Faro-Olhão channel. The range of variation of stable isotope values among primary producers in Ria Formosa was low suggesting difficulties in the assessment of their relative contribution to higher levels of the food web. Chl a values decreased from outer station to inner station, while SPM and POM values increased. The multiple isotope approach illustrates that POM values along the Faro-Olhão channel, may result from a mixture of upland plants, benthic plants and phytoplankton. Mussel values indicate a selective diet of benthic macrophytes and phytoplankton, with the relative proportions of each determined by the location in the channel. During winters, the upland plants may be an important source of organic matter in the inner lagoon while phytoplankton was an important source of organic matter in the outer lagoon.

  3. 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

  4. Sources and diagenesis of organic matter in tidal flat sediments from the German Wadden Sea

    NASA Astrophysics Data System (ADS)

    Volkman, J. K.; Rohjans, D.; Rullkötter, J.; Scholz-Böttcher, B. M.; Liebezeit, G.

    2000-07-01

    The sources and diagenesis of organic matter in a sediment core from the Swinnplate backbarrier area near Spiekeroog Island in the northwest German Wadden Sea have been examined using stable carbon isotopes, 14C-ages and lipid biomarker data. Twenty-two core sections were analysed from the surface to a depth of 90 cm, representing sedimentation over the past approximately 200 years. Total organic carbon (TOC) contents were highly variable (0.1-1%), as was the grain size with some core sections containing up to 50% of clay and silt (mud fraction). These data indicate a highly variable depositional regime in which organic matter is extensively degraded both before and after incorporation into the sediments. The TOC content was strongly correlated with the abundance of the mud fraction, indicating the importance of organic matter sorption onto particles for preservation of both marine and terrestrial organic matter. Sediments near the top of the core were enriched in marine organic matter, but terrestrial organic matter predominated in most core sections. Some samples showed higher TOC contents than might be predicted from the TOC-grain size relationship. Isotope and biomarker studies showed that these contained additional terrestrial organic matter from peats, possibly eroded from areas to the west of the investigated area. The organic matter in these layers had the lightest values of δ 13C (about -26‰ compared with a more typical mixed marine-terrestrial value of -24‰). Most of the n-alkane distributions show a strong predominance of odd-carbon-number alkanes typical of the distributions found in higher plant waxes. All core sections contained abundant long-chain alcohols and triterpenoid alcohols such as α-amyrin, β-amyrin, lupeol, taraxerol, taraxerone and friedelin from higher plants. The dihydroxy triterpenoid betulin was particularly abundant confirming that eroded peats are a major source of the lipids. Further confirmation was obtained from AMS

  5. Organic matter bioavailability controls the active bacterial fraction in deep-sea sediments

    NASA Astrophysics Data System (ADS)

    Luna, G. M.; Giuliano, L.; Danovaro, R.

    2003-04-01

    Deep-sea sediments, covering more than 60% of the earth surface, represent the largest Earth's ecosystem. Bacteria are the most abundant component and the major players of biogeochemical transformations. However, the knowledge of the physiological and metabolic state of bacterial cells in deep-sea sediments is still extremely poor, thus limiting our actual comprehension of bacterial role on C cycling and early diagenesis on global scale. The recent discovery that a large bacterial fraction is dead and/or inactive suggests that the rather constant bacterial number in the deep sea might be due to the inappropriate methodology of estimation. We investigated the abundance of nucleoid-containing cells (NuCC), assumed to be the active bacterial fraction, and their relative contribution to total bacterial counts in Mediterranean deep-sea sediments (from 670 to 2570 m depth), together with measurements of sedimentary organic matter. Our results indicate that living bacterial cells accounted for 14 to 70% of total bacterial number. The active bacterial abundance decreased by 4 times with increasing station depth. Moreover, NuCC abundance strongly decreased with increasing depth in the sediment, together with the decrease of organic matter concentrations (in terms of protein, carbohydrates and pigments). Our findings indicate that the bioavailable fraction of organic matter exert a strong control on activity and turnover rates of microbial assemblages in deep sea.

  6. 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.

  7. Dodelson-Widrow production of sterile neutrino Dark Matter with non-trivial initial abundance

    NASA Astrophysics Data System (ADS)

    Merle, Alexander; Schneider, Aurel; Totzauer, Maximilian

    2016-04-01

    The simplest way to create sterile neutrinos in the early Universe is by their admixture to active neutrinos. However, this mechanism, connected to the Dark Matter (DM) problem by Dodelson and Widrow (DW), cannot simulatenously meet the relic abundance constraint as well as bounds from structure formation and X-rays. Nonetheless, unless a symmetry forces active-sterile mixing to vanish exactly, the DW mechanism will unavoidably affect the sterile neutrino DM population created by any other production mechanism. We present a semi-analytic approach to the DW mechanism acting on an arbitrary initial abundance of sterile neutrinos, allowing to combine DW with any other preceeding production mechanism in a physical and precise way. While previous analyses usually assumed that the spectra produced by DW and another mechanism can simply be added, we use our semi-analytic results to discuss the validity of this assumption and to quantify its accurateness, thereby also scrutinising the DW spectrum and the derived mass bounds. We then map our results to the case of sterile neutrino DM from the decay of a real SM singlet coupled to the Higgs. Finally, we will investigate aspects of structure formation beyond the usual simple free-streaming estimates in order to judge on the effects of the DW modification on the sterile neutrino DM spectra generated by scalar decay.

  8. Chemodiversity of dissolved organic matter in the Amazon Basin

    NASA Astrophysics Data System (ADS)

    Gonsior, Michael; Valle, Juliana; Schmitt-Kopplin, Philippe; Hertkorn, Norbert; Bastviken, David; Luek, Jenna; Harir, Mourad; Bastos, Wanderley; Enrich-Prast, Alex

    2016-07-01

    Regions in the Amazon Basin have been associated with specific biogeochemical processes, but a detailed chemical classification of the abundant and ubiquitous dissolved organic matter (DOM), beyond specific indicator compounds and bulk measurements, has not yet been established. We sampled water from different locations in the Negro, Madeira/Jamari and Tapajós River areas to characterize the molecular DOM composition and distribution. Ultrahigh-resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) combined with excitation emission matrix (EEM) fluorescence spectroscopy and parallel factor analysis (PARAFAC) revealed a large proportion of ubiquitous DOM but also unique area-specific molecular signatures. Unique to the DOM of the Rio Negro area was the large abundance of high molecular weight, diverse hydrogen-deficient and highly oxidized molecular ions deviating from known lignin or tannin compositions, indicating substantial oxidative processing of these ultimately plant-derived polyphenols indicative of these black waters. In contrast, unique signatures in the Madeira/Jamari area were defined by presumably labile sulfur- and nitrogen-containing molecules in this white water river system. Waters from the Tapajós main stem did not show any substantial unique molecular signatures relative to those present in the Rio Madeira and Rio Negro, which implied a lower organic molecular complexity in this clear water tributary, even after mixing with the main stem of the Amazon River. Beside ubiquitous DOM at average H / C and O / C elemental ratios, a distinct and significant unique DOM pool prevailed in the black, white and clear water areas that were also highly correlated with EEM-PARAFAC components and define the frameworks for primary production and other aspects of aquatic life.

  9. The Carboniferous carbon isotope record from sedimentary organic matter: can we disentangle the carbon cycle?

    NASA Astrophysics Data System (ADS)

    Davies, S. J.; Bennett, C. E.; Leng, M. J.; Kearsey, T.; Marshall, J. E.; Millward, D.; Reeves, E. J.; Snelling, A.; Sherwin, J. E.

    2014-12-01

    A comprehensive analysis of the δ13C composition of sedimentary organic matter from Euramerican Carboniferous successions indicates there are significant shifts in δ13C through this key time interval. Our studies have revealed that, at an individual location, the source and delivery mechanism of the sediment contribute to the type of organic matter preserved and, in turn this influences the measured δ13C values from bulk sedimentary organic matter of organic matter. In general, where marine-derived organic matter is dominant in these Carboniferous successions then δ13C values are characteristically lower compared to the higher values encountered where terrestrial plant-derived material is most abundant. The implication of these observations is that an apparent carbon isotope excursion identified from the bulk organic matter may reflect a change in transport processes, or depositional environment, rather than a perturbation in the global carbon cycle. In our most recent studies, however, we compare δ13C values from specific wood fragments and bulk sedimentary organic matter from non-marine, marine basinal, and marine shelfal successions from the earliest Mississippian through to the early Pennsylvanian. These data indicate that early Mississippian δ13C of organic matter is far less negative (around -22%0) than material of Late Mississippian age (around -26%0), however by the early Pennsylvanian, δ13C values return to -22%0. There are some δ13C data from brachiopod carbonate from this time interval and similar shifts are indicated. Our data are beginning to address whether we can identify a primary carbon cycle signal from the Carboniferous record using δ13C from a range of sedimentary environments. If we can, there are still questions around what the record is telling us about the global carbon cycle during a period when plant groups, including lycopods and seed ferns, rapidly diversified.

  10. 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

  11. Extraterrestrial Organic Matter and the Detection of Life

    NASA Astrophysics Data System (ADS)

    Sephton, Mark A.; Botta, Oliver

    A fundamental goal of a number of forthcoming space missions is the detection and characterization of organic matter on planetary surfaces. Successful interpretation of data generated by in situ experiments will require discrimination between abiogenic and biogenic organic compounds. Carbon-rich meteorites provide scientists with examples of authentic extraterrestrial organic matter generated in the absence of life. Outcomes of meteorite studies include clues to protocols that will enable the unequivocal identification of organic matter derived from life. In this chapter we summarize the diagnostic abiogenic features of key compound classes involved in life detection and discuss their implications for analytical instruments destined to fly on future spacecraft missions.

  12. Extraterrestrial Organic Matter and the Detection of Life

    NASA Astrophysics Data System (ADS)

    Sephton, Mark A.; Botta, Oliver

    2008-03-01

    A fundamental goal of a number of forthcoming space missions is the detection and characterization of organic matter on planetary surfaces. Successful interpretation of data generated by in situ experiments will require discrimination between abiogenic and biogenic organic compounds. Carbon-rich meteorites provide scientists with examples of authentic extraterrestrial organic matter generated in the absence of life. Outcomes of meteorite studies include clues to protocols that will enable the unequivocal identification of organic matter derived from life. In this chapter we summarize the diagnostic abiogenic features of key compound classes involved in life detection and discuss their implications for analytical instruments destined to fly on future spacecraft missions.

  13. 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

  14. Abiotic emissions of methane and reduced organic compounds from organic matter

    NASA Astrophysics Data System (ADS)

    Roeckmann, T.; Keppler, F.; Vigano, I.; Derendorp, L.; Holzinger, R.

    2012-12-01

    Recent laboratory studies show that the important greenhouse gas methane, but also other reduced atmospheric trace gases, can be emitted by abiotic processes from organic matter, such as plants, pure organic compounds and soils. It is very difficult to distinguish abiotic from biotic emissions in field studies, but in laboratory experiments this is easier because it is possible to carefully prepare/sterilize samples, or to control external parameters. For example, the abiotic emissions always show a strong increase with temperature when temperatures are increased to 70C or higher, well above the temperature optimum for bacterial activity. UV radiation has also been clearly shown to lead to emission of methane and other reduced gases from organic matter. Interesting information on the production mechanism has been obtained from isotope studies, both at natural abundance and with isotope labeling. For example, the methoxyl groups of pectin were clearly identified to produce methane. However, analysis of the isotopic composition of methane from natural samples clearly indicates that there must be other molecular mechanisms that lead to methane production. Abiotic methane generation could be a ubiquitous process that occurs naturally at low rates from many different sources.

  15. 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.

  16. Organic matter and metamorphic history of CO chondrites

    NASA Astrophysics Data System (ADS)

    Bonal, Lydie; Bourot-Denise, Michèle; Quirico, Eric; Montagnac, Gilles; Lewin, Eric

    2007-03-01

    The metamorphic grades of a series of eight CO3 chondrites (ALHA77307, Colony, Kainsaz, Felix, Lancé, Ornans, Warrenton and Isna) have been quantified. The method used was based on the structural grade of the organic matter trapped in the matrix, which is irreversibly transformed by thermal metamorphism. The maturation of the organic matter is independent with respect to the mineralogical context and aqueous alteration. This metamorphic tracer is thus valid whatever the chemical class of chondrites. Moreover, it is sensitive to the peak metamorphic temperature. The structural grade of the organic matter was used along with other metamorphic tracers such as petrography of opaque minerals, Fa and Fs silicate composition in type I chondrules, presolar grains and noble gas (P3 component) abundance. The deduced metamorphic hierarchy and the attributed petrographic types are the following: ALHA77307 (3.03) < Colony (3.1) < Kainsaz (3.6) < Felix (3.6 (1)) < Ornans (3.6 (2)) < Lancé (3.6 (3)) < Warrenton (3.7 (1)) < Isna (3.7 (2)). For most metamorphosed objects, the peak metamorphic temperature can be estimated using a geothermometer calibrated with terrestrial metasediments [Beyssac O., Goffe B., Chopin C., and Rouzaud J. N. (2002) Raman spectrum of carbonaceous material in metasediments: a new geothermometer. J. Metamorph. Geol., 20, 859-871]. A value of 330 °C was obtained for Allende (CV chondrite), Warrenton and Isna, consistent with temperatures estimated from Fe diffusion [Weinbruch S., Armstrong J., and Palme H. (1994). Constraints on the thermal history of the Allende parent body as derive from olivine-spinel thermometry and Fe/Mg interdiffusion in olivine. Geochim. Cosmochim. Acta58(2), 1019-1030.], from the Ni content in sulfide-metal assemblages [Zanda B., Bourot-Denise M., and Hewins R. (1995) Condensate sulfide and its metamorphic transformations in primitive chondrites. Meteorit. Planet. Sci.30, A605.] and from the d002 interlayer spacing in poorly

  17. Input of organic matter enhances degradation of weathered diesel fuel in sub-tropical sediments.

    PubMed

    Horel, Agota; Mortazavi, Behzad; Sobecky, Patricia A

    2015-11-15

    We investigated different types of biostimulation practices to enhance degradation of weathered conventional diesel fuel in sandy beach sediments from coastal Alabama. Biodegradation rates were measured following the addition of either inorganic nutrients, or organic matter derived from either plant material (Spartina alterniflora) or fish tissue (Chloroscombrus chrysurus) both common to the region. The greatest hydrocarbon degradation rates were observed in the C. chrysurus amended treatments (k=0.0119 d(-1)). Treatment with fish-derived organic matter increased the degradation rates by 104% as compared to control treatments, while inorganic nutrient addition increased the degradation rates by 57%. The addition of plant derived organic matter, however, only marginally enhanced the degradation rates (~7%) during the course of the study. Bacterial 16S rRNA analyses revealed that most sediment microorganisms belonged to the classes; Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria, and Bacteroidetes. The most frequently abundant hydrocarbon degraders were mostly similar to Achromobater sp., Microbulbifer sp., Ruegeria sp., and Pseudomonas sp.

  18. Anatomy of a cluster IDP. Part 2: Noble gas abundances, trace element geochemistry, isotopic abundances, and trace organic chemistry of several fragments from L2008#5

    NASA Technical Reports Server (NTRS)

    Thomas, K. L.; Clemett, S. J.; Flynn, G. J.; Keller, L. P.; Mckay, David S.; Messenger, S.; Nier, A. O.; Schlutter, D. J.; Sutton, S. R.; Walker, R. M.

    1994-01-01

    The topics discussed include the following: noble gas content and release temperatures; trace element abundances; heating summary of cluster fragments; isotopic measurements; and trace organic chemistry.

  19. 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.

  20. 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

  1. 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.

  2. Nitrogen Isotopic Composition of Organic Matter in a Pristine Collection IDP

    NASA Technical Reports Server (NTRS)

    Messenger, S.; Nakamura-Messenger, K.; Keller, L. P.; Clemett, S. J.; Nguyen, A. N.; Walker, Robert M.

    2012-01-01

    Anhydrous chondritic porous interplanetary dust particles (CP IDPs) are probable cometary materials that show primitive characteristics, such as unequilibrated mineralogy, fragile structure, and abundant presolar grains and organic matter [1-3]. CP IDPs are richer in aliphatic species and N-bearing aromatic hydrocarbons than meteoritic organics and commonly exhibit highly anomalous H and N isotopic compositions [4,5]. Cometary organic matter is of interest in part because it has escaped the hydrothermal processing experienced by meteorites. However, IDPs are collected using silicon oil that must be removed with strong organic solvents such as hexane. This procedure is likely to have removed some fraction of soluble organic phases in IDPs. We recently reported the first stratospheric collection of IDPs without the use of silicone oil [6]. Here we present initial studies of the carbonaceous material in an IDP from this collection.

  3. 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

  4. 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.

  5. 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

  6. Influence of land use on soil organic matter

    NASA Astrophysics Data System (ADS)

    Rogeon, H.; Lemée, L.; Chabbi, A.; Ambles, A.

    2009-04-01

    Soil organic matter (SOM) is actually of great environmental interest as the amount of organic matter stored in soils represents one of the largest reservoirs of organic carbon on the global scale [1]. Indeed, soil carbon storage capacity represents 1500 to 2000 Gt for the first meter depth, which is twice the concentration of atmospheric CO2 [2]. Furthermore, human activities, such as deforestation (which represents a flux of 1.3 Gt C/year), contribute to the increase in atmospheric CO2 concentration for about one percent a year [3]. Therefore, carbon dioxide sequestration in plant and carbon storage in soil and biomass could be considered as a complementary solution against climate change. The stock of carbon in soils is greatly influenced by land use (ca 70 Gt for a forest soil or a grassland against 40 Gt for an arable land). Furthermore the molecular composition of SOM should be also influenced by vegetation. In this context, four horizons taken between 0-120 cm from the same profile of a soil under grassland and forest located in the vicinity of Poitiers (INRA Lusignan, ORE Prairie) were compared. For the surface horizon, the study is improved with the results from the cultivated soil from INRA Versailles. Soil organic matter was characterized using IR spectroscopy, elemental analysis and thermal analysis. Granulometric fractionation into sand (50-2000 μm), silt (2-50 μm) and clay (<2 μm) was conducted. The organic matter associated with the mineral fractions was thus characterized using thermochemolysis coupled with gas chromatography and mass spectrometry (Py-GC/MS). The total lipidic fractions were extracted with CH2Cl2/MeOH using an accelerated solvent extraction (ASE). In the three soils, lipids are concentrated into the superficial horizon (0-30 cm) which indicates a low mobilisation. Lipids from the superficial horizon are more abundant for the arable soil (1010 ppm) than for the two other (400 ppm). Lipids from the forest and the grassland were

  7. Assessment of soil organic matter fluxes at the EU level

    NASA Astrophysics Data System (ADS)

    Gobin, Anne; Campling, Paul

    2010-05-01

    Soil has a complex relationship with climate change. Soil helps take carbon dioxide out of the air and as such it absorbs millions of tons each year, but with the Earth still warming micro-organisms grow faster, consume more soil organic matter and release carbon dioxide. The net result is a relative decline in soil organic carbon. With a growing population and higher bio-energy demands, more land is likely to be required for settlement, for commercial activity and for bio-energy production. Conversions from terrestrial ecosystems to urban and commercial activity will alter both the production and losses of organic matter, and have an indirect impact on potential SOM levels. Conversions between different terrestrial ecosystems have a direct impact on SOM levels. Net SOM losses are reported for several land conversions, e.g. from grassland to arable land, from wetlands to drained agricultural land, from crop rotations to monoculture, reforestation of agricultural land. In the context of looking for measures to support best practices to manage soil organic matter in Europe we propose a method to assess soil organic matter fluxes at the EU level. We adopt a parsimonious approach that is comparable to the nutrient balance approaches developed by the OECD and Eurostat. We describe the methodology and present the initial results of a European carbon balance indicator that uses existing European statistical and land use change databases. The carbon balance consists of the following components: organic matter production (I), organic matter losses (O), land use changes that effect both production and losses (E). These components are set against the (mostly legislative) boundary conditions that determine the maximum input potential (MIP) for soil organic matter. In order to budget SOM losses due to mineralisation, runs will be made with a multi-compartment SOM model that takes into account management practices, climate and different sources of organic matter.

  8. 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.

  9. Fractionation and characterization of organic matter in wastewater from a swine waste-retention basin

    USGS Publications Warehouse

    Leenheer, Jerry A.; Rostad, Colleen E.

    2004-01-01

    Organic matter in wastewater sampled from a swine waste-retention basin in Iowa was fractionated into 14 fractions on the basis of size (particulate, colloid, and dissolved); volatility; polarity (hydrophobic, transphilic, hydrophilic); acid, base, neutral characteristics; and precipitate or flocculates (floc) formation upon acidification. The compound-class composition of each of these fractions was determined by infrared and 13C-NMR spectral analyses. Volatile acids were the largest fraction with acetic acid being the major component of this fraction. The second most abundant fraction was fine particulate organic matter that consisted of bacterial cells that were subfractionated into extractable lipids consisting of straight chain fatty acids, peptidoglycans components of bacterial cell walls, and protein globulin components of cellular plasma. The large lipid content of the particulate fraction indicates that non-polar contaminants, such as certain pharmaceuticals added to swine feed, likely associate with the particulate fraction through partitioning interactions. Hydrocinnamic acid is a major component of the hydrophobic acid fraction, and its presence is an indication of anaerobic degradation of lignin originally present in swine feed. This is the first study to combine particulate organic matter with dissolved organic matter fractionation into a total organic matter fractionation and characterization.

  10. Pyrolysis-combustion 14C dating of soil organic matter

    USGS Publications Warehouse

    Wang, Hongfang; Hackley, Keith C.; Panno, S.V.; Coleman, D.D.; Liu, J.C.-L.; Brown, J.

    2003-01-01

    Radiocarbon (14C) dating of total soil organic matter (SOM) often yields results inconsistent with the stratigraphic sequence. The onerous chemical extractions for SOM fractions do not always produce satisfactory 14C dates. In an effort to develop an alternative method, the pyrolysis-combustion technique was investigated to partition SOM into pyrolysis volatile (Py-V) and pyrolysis residue (Py-R) fractions. The Py-V fractions obtained from a thick glacigenic loess succession in Illinois yielded 14C dates much younger but more reasonable than the counterpart Py-R fractions for the soil residence time. Carbon isotopic composition (??13C) was heavier in the Py-V fractions, suggesting a greater abundance of carbohydrate- and protein-related constituents, and ??13C was lighter in the Py-R fractions, suggesting more lignin- and lipid-related constituents. The combination of 14C dates and ??13C values indicates that the Py-V fractions are less biodegradation resistant and the Py-R fractions are more biodegradation resistant. The pyrolysis-combustion method provides a less cumbersome approach for 14C dating of SOM fractions. With further study, this method may become a useful tool for analyzing unlithified terrestrial sediments when macrofossils are absent. ?? 2003 University of Washington. Published by Elsevier Inc. All rights reserved.

  11. Soil organic matter quantity and quality shape microbial community compositions of subtropical broadleaved forests.

    PubMed

    Ding, Junjun; Zhang, Yuguang; Wang, Mengmeng; Sun, Xin; Cong, Jing; Deng, Ye; Lu, Hui; Yuan, Tong; Van Nostrand, Joy D; Li, Diqiang; Zhou, Jizhong; Yang, Yunfeng

    2015-10-01

    As two major forest types in the subtropics, broadleaved evergreen and broadleaved deciduous forests have long interested ecologists. However, little is known about their belowground ecosystems despite their ecological importance in driving biogeochemical cycling. Here, we used Illumina MiSeq sequencing targeting 16S rRNA gene and a microarray named GeoChip targeting functional genes to analyse microbial communities in broadleaved evergreen and deciduous forest soils of Shennongjia Mountain of Central China, a region known as 'The Oriental Botanic Garden' for its extraordinarily rich biodiversity. We observed higher plant diversity and relatively richer nutrients in the broadleaved evergreen forest than the deciduous forest. In odds to our expectation that plant communities shaped soil microbial communities, we found that soil organic matter quantity and quality, but not plant community parameters, were the best predictors of microbial communities. Actinobacteria, a copiotrophic phylum, was more abundant in the broadleaved evergreen forest, while Verrucomicrobia, an oligotrophic phylum, was more abundant in the broadleaved deciduous forest. The density of the correlation network of microbial OTUs was higher in the broadleaved deciduous forest but its modularity was smaller, reflecting lower resistance to environment changes. In addition, keystone OTUs of the broadleaved deciduous forest were mainly oligotrophic. Microbial functional genes associated with recalcitrant carbon degradation were also more abundant in the broadleaved deciduous forests, resulting in low accumulation of organic matters. Collectively, these findings revealed the important role of soil organic matter in shaping microbial taxonomic and functional traits.

  12. 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...

  13. Soil organic matter dynamics and the global carbon cycle

    SciTech Connect

    Post, W.M.; Emanuel, W.R.; King, A.W.

    1992-01-01

    The large size and potentially long residence time of the soil organic matter pool make it an important component of the global carbon cycle. Net terrestrial primary production of about 60 Pg C[center dot]yr[sup -1] is, over a several-year period of time, balanced by an equivalent flux of litter production and subsequent decomposition of detritus and soil organic matter. We will review many of the major factors that influence soil organic matter dynamics that need to be explicitly considered in development of global estimates of carbon turnover in the world's soils. We will also discuss current decomposition models that are general enough to be used to develop a representation of global soil organic matter dynamics.

  14. Soil organic matter dynamics and the global carbon cycle

    SciTech Connect

    Post, W.M.; Emanuel, W.R.; King, A.W.

    1992-12-01

    The large size and potentially long residence time of the soil organic matter pool make it an important component of the global carbon cycle. Net terrestrial primary production of about 60 Pg C{center_dot}yr{sup -1} is, over a several-year period of time, balanced by an equivalent flux of litter production and subsequent decomposition of detritus and soil organic matter. We will review many of the major factors that influence soil organic matter dynamics that need to be explicitly considered in development of global estimates of carbon turnover in the world`s soils. We will also discuss current decomposition models that are general enough to be used to develop a representation of global soil organic matter dynamics.

  15. The role of clay minerals in the preservation of organic matter in sediments of qinghai lake, NW China

    USGS Publications Warehouse

    Yu, B.; Dong, H.; Jiang, H.; Lv, G.; Eberl, D.; Li, S.; Kim, J.

    2009-01-01

    The role of saline lake sediments in preserving organic matter has long been recognized. In order to further understand the preservation mechanisms, the role of clay minerals was studied. Three sediment cores, 25, 57, and 500 cm long, were collected from Qinghai Lake, NW China, and dissected into multiple subsamples. Multiple techniques were employed, including density fractionation, X-ray diffraction, scanning and transmission electron microscopy (SEM and TEM), total organic carbon (TOC) and carbon compound analyses, and surface area determination. The sediments were oxic near the water-sediment interface, but became anoxic at depth. The clay mineral content was as much as 36.8%, consisting mostly of illite, chlorite, and halloysite. The TEM observations revealed that organic matter occurred primarily as organic matter-clay mineral aggregates. The TOC and clay mineral abundances are greatest in the mid-density fraction, with a positive correlation between the TOC and mineral surface area. The TOC of the bulk sediments ranges from 1 to 3% with the non-hydrocarbon fraction being predominant, followed by bitumen, saturated hydrocarbon, aromatic hydrocarbons, and chloroform-soluble bitumen. The bimodal distribution of carbon compounds of the saturated hydrocarbon fraction suggests that organic matter in the sediments was derived from two sources: terrestrial plants and microorganisms/algae. Depthrelated systematic changes in the distribution patterns of the carbon compounds suggest that the oxidizing conditions and microbial abundance near the water-sediment interface promote degradation of labile organic matter, probably in adsorbed form. The reducing conditions and small microbial biomass deeper in the sediments favor preservation of organic matter, because of the less labile nature of organic matter, probably occurring within clay mineral-organic matter aggregates that are inaccessible to microorganisms. These results have important implications for our

  16. Cross Sections, relic abundance, and detection rates for neutralino dark matter

    SciTech Connect

    Griest, K.

    1988-06-01

    Neutralino annihilation and elastic scattering cross sections are derived which differ in important ways from previous work. These are applied to relic abundance calculations and to direct detection of neutralino dark matter from the galactic halo. Assuming the neutralino to be the lightest supersymmetric particle and that it is less massive than the Z sup 0, we find relic densities of neutralinos greater than 4 percent of critical density for almost all values of the supersymmetric parameters. We constrain the parameter space by using results from PETRA (chargino mass less than 23 GeV) and ASP, and then assuming a critical density of neutralinos, display event rates in a cryogenic detector for a variety of models. A new term implies spin independent elastic scattering even for those majorana particles and inclusion of propagator momenta increases detection rates by 10 to 300 percent for pure photinos. Z sup 0-squark interference leads to very low detection rates for some values of the parameters. The new term in the elastic cross section dominates for heavy, mostly spinless materials and mitigates the negative interference cancellations in light materials; except for the pure photino or pure higgsinos cases where it does not contribute. In general, the rates can be substantially different from the pure photino and pure higgsino special cases usually considered.

  17. Cross sections, relic abundance, and detection rates for neutralino dark matter

    SciTech Connect

    Griest, K.

    1988-10-15

    Neutralino annihilation and elastic scattering cross sections are derived which differ in important ways from previous work. These are applied to relic abundance calculations and to direct detection of neutralino dark matter from the galactic halo. Assuming the neutralino is the lightest supersymmetric particle and that it is less massive than the Z/sup 0/, we find relic densities of neutralinos greater than 4% of critical density for almost all values of the supersymmetric parameters. We constrain the parameter space by using results from the DESY e/sup +/e/sup -/ storage ring PETRA (chargino mass less than 23 GeV) and the ASP detector at the SLAC storage ring PEP, and then assuming a critical density of neutralinos, display event rates in a cryogenic detector for a variety of models. A new term implies ''spin-independent'' elastic scattering even for these Majorana particles and inclusion of propagator momenta increases detection rates by 10--300 % even for pure photinos. Z/sup 0/-squark interference leads to very low detection rates for some values of the parameters. The new term in the elastic cross section dominates for heavy, mostly spinless materials and mitigates the negative interference cancellations in light materials, except for the pure photino or pure Higgsino cases where it does not contribute. In general, the rates can be substantially different from the pure photino and pure Higgsino special cases usually considered.

  18. Cross Sections, relic abundance, and detection rates for neutralino dark matter

    NASA Technical Reports Server (NTRS)

    Griest, Kim

    1988-01-01

    Neutralino annihilation and elastic scattering cross sections are derived which differ in important ways from previous work. These are applied to relic abundance calculations and to direct detection of neutralino dark matter from the galactic halo. Assuming the neutralino to be the lightest supersymmetric particle and that it is less massive than the Z sup 0, we find relic densities of neutralinos greater than 4 percent of critical density for almost all values of the supersymmetric parameters. We constrain the parameter space by using results from PETRA (chargino mass less than 23 GeV) and ASP, and then assuming a critical density of neutralinos, display event rates in a cryogenic detector for a variety of models. A new term implies spin independent elastic scattering even for those majorana particles and inclusion of propagator momenta increases detection rates by 10 to 300 percent for pure photinos. Z sup 0-squark interference leads to very low detection rates for some values of the parameters. The new term in the elastic cross section dominates for heavy, mostly spinless materials and mitigates the negative interference cancellations in light materials; except for the pure photino or pure higgsinos cases where it does not contribute. In general, the rates can be substantially different from the pure photino and pure higgsino special cases usually considered.

  19. Seasonal Changes in Arctic Dissolved Organic Matter

    NASA Astrophysics Data System (ADS)

    Boot, C. M.; Wallenstein, M. D.; Schimel, J.

    2011-12-01

    The Arctic is a landscape in flux. Temperatures are shifting upward and plant communities are transitioning from tussock to shrub tundra in some regions. Decomposition processes sensitive to temperature, moisture, and plant inputs are controls on the source/sink dynamics of the Arctic C pool. The response of decomposition to warming will, in part, determine if the Arctic C pool feeds back positively or negatively to climate change. The portion of the C pool immediately available to decomposers is dissolved organic matter (DOM). The aim of this is study is to examine the molecular composition of DOM to determine which components vary seasonally in soil pore water among three vegetation types at Toolik Field Station in Alaska. Vegetation types include wet sedge (Carex aquatilis and Eriophorum angustifolium), moist acidic tussock (E. vaginatum) and shrub tundra (Betula nana and Salix sp.). These sites were sampled during winter/summer transitions in 2010 in order to capture both growing season and winter dynamics. We expected the chemical composition of DOM in pore water to be distinct among plant communities due to differences in root exudates, litter chemistry and microbial community; and vary seasonally due to shifting temperature and water availability and their impacts on decomposition of DOM. Soil pore water was isolated through centrifugation and is being characterized with ultra high performance liquid chromatography (UPLC) in line with a quadrupole time of flight mass spectrometer (QTOF-MS) as well as with specific UV absorbance at 254 nm (SUVA), and excitation emission matrices (EEMs) generated by fluorescence spectroscopy. The DOM concentrations across vegetation types show consistent seasonal patterns, spiking at thaw, and declining through late summer. As soils freeze these patterns diverge-in tussock soils DOM concentration decreases slightly, while in shrub and wet sedge sites it increases. SUVA values (indicator of aromaticity) were consistent among

  20. Big-bang nucleosynthesis and the relic abundance of dark matter in a stau-neutralino coannihilation scenario

    SciTech Connect

    Jittoh, Toshifumi; Koike, Masafumi; Sato, Joe; Yamanaka, Masato; Kohri, Kazunori; Shimomura, Takashi

    2008-09-01

    A scenario of the big-bang nucleosynthesis is analyzed within the minimal supersymmetric standard model, which is consistent with a stau-neutralino coannihilation scenario to explain the relic abundance of dark matter. We find that we can account for the possible discrepancy of the abundance of {sup 7}Li between the observation and the prediction of the big-bang nucleosynthesis by taking the mass of the neutralino as 300 GeV and the mass difference between the stau and the neutralino as (100-120) MeV. We can therefore simultaneously explain the abundance of the dark matter and that of {sup 7}Li by these values of parameters. The lifetime of staus in this scenario is predicted to be O(100-1000) sec.

  1. Land-use Effect on Stream Organic Matter Composition in Two Metropolitan Areas in USA

    NASA Astrophysics Data System (ADS)

    Duan, S.; Kaushal, S.; Amon, R. M.; Brinkmeyer, R.

    2011-12-01

    displacement of waste water treatment plant in upper watershed. Organic matter compositions of suspended sediment, however, were more related to abundance of phytoplankton biomass.

  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. Organic matter and containment of uranium and fissiogenic isotopes at the Oklo natural reactors

    USGS Publications Warehouse

    Nagy, B.; Gauthier-Lafaye, F.; Holliger, P.; Davis, D.W.; Mossman, D.J.; Leventhal, J.S.; Rigali, M.J.; Parnell, J.

    1991-01-01

    SOME of the Precambrian natural fission reactors at Oklo in Gabon contain abundant organic matter1,2, part of which was liquefied at the time of criticality and subsequently converted to a graphitic solid3,4. The liquid organic matter helps to reduce U(VI) to U(IV) from aqueous solutions, resulting in the precipitation of uraninite5. It is known that in the prevailing reactor environments, precipitated uraninite grains incorporated fission products. We report here observations which show that these uraninite crystals were held immobile within the resolidified, graphitic bitumen. Unlike water-soluble (humic) organic matter, the graphitic bituminous organics at Oklo thus enhanced radionu-clide containment. Uraninite encased in solid graphitic matter in the organic-rich reactor zones lost virtually no fissiogenic lan-thanide isotopes. The first major episode of uranium and lead migration was caused by the intrusion of a swarm of adjacent dolerite dykes about 1,100 Myr after the reactors went critical. Our results from Oklo imply that the use of organic, hydrophobic solids such as graphitic bitumen as a means of immobilizing radionuclides in pretreated nuclear waste warrants further investigation. ?? 1991 Nature Publishing Group.

  4. 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.

  5. Natural organic matter properties in Swedish agricultural streams

    NASA Astrophysics Data System (ADS)

    Bieroza, Magdalena; Kyllmar, Katarina; Bergström, Lars; Köhler, Stephan

    2016-04-01

    We have analysed natural organic matter (NOM) properties in 18 agricultural streams in Sweden covering a broad range of environmental (climate, soil type), land use and water quality (nutrient and concentrations, pH, alkalinity) characteristics. Stream water samples collected every two weeks within an ongoing Swedish Monitoring Programme for Agriculture have been analysed for total/dissolved organic carbon, absorbance and fluorescence spectroscopy. A number of quantitative and qualitative spectroscopic parameters was calculated to help to distinguish between terrestrially-derived, refractory organic material and autochthonous, labile material indicative of biogeochemical transformations of terrestrial NOM and recent biological production. The study provides insights into organic matter properties and carbon budgets in agricultural streams and improves understanding of how agricultural catchments transform natural and anthropogenic fluxes of organic matter and nutrients to signals observed in receiving waters.

  6. 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.

  7. 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

  8. 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 ...

  9. Extremely reducing conditions reached during basaltic intrusion in organic matter-bearing sediments

    NASA Astrophysics Data System (ADS)

    Iacono-Marziano, Giada; Gaillard, Fabrice; Scaillet, Bruno; Polozov, Alexander G.; Marecal, Virginie; Pirre, Michel; Arndt, Nicholas T.

    2012-12-01

    Redox conditions in magma are widely interpreted as internally buffered and closely related to that of their mantle source regions. We use thermodynamic calculations to show that high-temperature interaction between magma and organic matter can lead to a dramatic reduction of the magma redox state, and significant departure from that of the original source. Field studies provide direct evidence of the process that we describe, with reported occurrences of graphite and native iron in igneous mafic rocks, implying very reducing conditions that are almost unknown in average terrestrial magmas. We calculate that the addition of 0.6 wt% organic matter (in the form of CH or CH2) to a standard basalt triggers graphite and native iron crystallization at depths of few hundred meters. Interaction with organic matter also profoundly affects the abundance and the redox state of the gases in equilibrium with the magma, which are CO-dominated with H2 as the second most abundant species on a molar basis, H2O and CO2 being minor constituents. The assimilation of only 0.1 wt% organic matter by a basalt causes a decrease in its oxygen fugacity of 2-orders of magnitude. The assimilation of 0.6 wt% organic matter at depths<500 m implies minimum CO content in the magma of 1 wt%, other gas components being less than 0.1 wt%. In the light of our calculations, we suggest that the production of native iron-bearing lava flows and associated intrusions was most likely accompanied by degassing of CO-rich gases, whose fluxes depended on the magma production rates.

  10. Radiocarbon and stable carbon isotope compositions of chemically fractionated soil organic matter in a temperate-zone forest.

    PubMed

    Koarashi, Jun; Iida, Takao; Asano, Tomohiro

    2005-01-01

    To better understand the role of soil organic matter in terrestrial carbon cycle, carbon isotope compositions in soil samples from a temperate-zone forest were measured for bulk, acid-insoluble and base-insoluble organic matter fractions separated by a chemical fractionation method. The measurements also made it possible to estimate indirectly radiocarbon ((14)C) abundances of acid- and base-soluble organic matter fractions, through a mass balance of carbon among the fractions. The depth profiles of (14)C abundances showed that (1) bomb-derived (14)C has penetrated the first 16cm mineral soil at least; (2) Delta(14)C values of acid-soluble organic matter fraction are considerably higher than those of other fractions; and (3) a significant amount of the bomb-derived (14)C has been preserved as the base-soluble organic matter around litter-mineral soil boundary. In contrast, no or little bomb-derived (14)C was observed for the base-insoluble fraction in all sampling depths, indicating that this recalcitrant fraction, accounting for approximately 15% of total carbon in this temperate-zone forest soil, plays a role as a long-term sink in the carbon cycle. These results suggest that bulk soil organic matter cannot provide a representative indicator as a source or a sink of carbon in soil, particularly on annual to decadal timescales. PMID:15603904

  11. Organic matter heterogeneities in 2.72 Ga stromatolites: Alteration versus preservation by sulfur incorporation

    NASA Astrophysics Data System (ADS)

    Lepot, Kevin; Benzerara, Karim; Rividi, Nicolas; Cotte, Marine; Brown, Gordon E., Jr.; Philippot, Pascal

    2009-11-01

    The stromatolites of the weakly metamorphosed 2.72 Ga Tumbiana Formation present abundant organic globules that resemble in size, shape and distribution the microorganisms observed in modern stromatolites. In order to evaluate the significance of these cell-like organic materials, we characterized organic matter in-situ down to the nanoscale using a combination of Fourier-transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), Raman microspectroscopy, scanning transmission X-ray microscopy (STXM) and transmission electron microscopy (TEM). These analyses revealed the occurrence of two distinct types of organic matter forming μm-scale textural and chemical heterogeneities distributed in distinct mineralogical laminae of the stromatolites. Type A organic matter, which is by far the most abundant, consists of sulfur-poor organic matter that is located in mud-type laminae at grain boundaries, mostly in association with silicate minerals. In contrast, Type B organic matter is rare and preserved as inclusions in the core of calcite grains forming laminates. It occurs as micrometer-sized cell-like globules containing variable amounts of organic sulfur likely in the form of thiophenes. Different scenarios may account for these compositional heterogeneities in the kerogen. Based on textural and compositional analogies with modern stromatolites, it is argued that Type B sulfur-rich globules may represent microbial cells protected by mineral encapsulation and selectively preserved through polymerization by early diagenetic sulfurization. In modern sediments, this reaction is fuelled by bacterial sulfate reduction (BSR). This metabolism has been widely considered as a major driver in modern stromatolites calcification and could thus have played an important role in the formation of the Tumbiana Formation stromatolites. In contrast, Type A sulfur-poor organic matter corresponds to either fossil extracellular polymer substances (EPS) or recondensed kerogen

  12. Comprehensive characterization of atmospheric organic matter in Fresno, California fog water

    USGS Publications Warehouse

    Herckes, P.; Leenheer, J.A.; Collett, J.L.

    2007-01-01

    Fogwater collected during winter in Fresno (CA) was characterized by isolating several distinct fractions and characterizing them by infrared and nuclear magnetic resonance (NMR) spectroscopy. More than 80% of the organic matter in the fogwater was recovered and characterized. The most abundant isolated fractions were those comprised of volatile acids (24% of isolated carbon) and hydrophilic acids plus neutrals (28%). Volatile acids, including formic and acetic acid, have been previously identified as among the most abundant individual species in fogwater. Recovered hydrophobic acids exhibited some properties similar to aquatic fulvic acids. An insoluble particulate organic matter fraction contained a substantial amount of biological material, while hydrophilic and transphilic fractions also contained material suggestive of biotic origin. Together, these fractions illustrate the important contribution biological sources make to organic matter in atmospheric fog droplets. The fogwater also was notable for containing a large amount of organic nitrogen present in a variety of species, including amines, nitrate esters, peptides, and nitroso compounds. ?? 2007 American Chemical Society.

  13. From microbial biomass compounds to non-living soil organic matter - Microbial biomass as a significant source for soil organic matter formation

    NASA Astrophysics Data System (ADS)

    Miltner, A.; Kindler, R.; Hoffmann-Jäniche, C.; Schmidt-Brücken, B.; Kästner, M.

    2009-04-01

    Soil organic matter is one of the most important pools of the global carbon cycle. Recently, it has been suggested that microbial biomass is a significant source for the formation of refractory organic matter. We tested the relevance of this source by incubation of soil with 13C-labeled Escherichia coli cells. We traced the labeled carbon in fatty acids and amino acids, both in the microbial biomass and in the bulk soil. We also localized cells and their debris by scanning electron microscopy. Although we could not detect any living cells after 100 days, about 50% of the carbon remained in the soil after 224 days. The amount of label in the fatty acids indicated that microbial lipids were degraded faster than the bulk microbial biomass. Their labeling pattern showed that they were redistributed from E. coli to the microbial food web and from the living biomass to non-living soil organic matter. In contrast, the label in the total amino acids did not decrease significantly during incubation. Proteins are thus surprisingly stable in soil, but they also shifted from microbial biomass to non-living soil organic matter. The scanning electron micrographs showed only isolated intact microbial cells in our soil, but patches of organic material of unknown origin which are about 20 - 50 nm2 in size were quite abundant. Dying microbial cells therefore are a significant carbon source for the formation of refractory organic material, but the morphology of the cells changes during degradation, as cell structures cannot be found frequently in soils.

  14. Organic matter composition and macrofaunal diversity in sediments of the Condor Seamount (Azores, NE Atlantic)

    NASA Astrophysics Data System (ADS)

    Bongiorni, Lucia; Ravara, Ascensão; Parretti, Paola; Santos, Ricardo S.; Rodrigues, Clara F.; Amaro, Teresa; Cunha, Marina R.

    2013-12-01

    In recent years increasing knowledge has been accumulated on seamounts ecology; however their sedimentary environments and associated biological communities remain largely understudied. In this study we investigated quantity and biochemical composition of organic matter and macrofaunal diversity in sediments of the Condor Seamount (NE Atlantic, Azores). In order to test the effect of the seamount on organic matter distribution, sediment samples were collected in 6 areas: the summit, the northern and southern flanks and bases, and in an external far field site. Macrofauna abundance and diversity were investigated on the summit, the southern flank and in the far field site. The organic matter distribution reflected the complex hydrodynamic conditions occurring on the Condor. Concentrations of organic matter compounds were generally lower on the whole seamount than in the far field site and on the seamount summit compared to flanks and bases. A clear difference was also evident between the northern and southern slopes of the Condor, suggesting a role of the seamount in conditioning sedimentation processes and distribution of food resources for benthic consumers. Macrofauna assemblages changed significantly among the three sampling sites. High abundance and dominance, accompanied by low biodiversity, characterized the macrofauna community on the Condor summit, while low dominance and high biodiversity were observed at the flank. Our results, although limited to five samples on the seamount and two off the seamount, do not necessarily support the paradigm that seamounts are more biodiverse than the surrounding seafloor. However, the abundance (and biomass), functional diversity and taxonomical distinctiveness of the macrofaunal assemblages from the Condor Seamount suggest that seamounts habitats may play a relevant role in adding to the regional biodiversity.

  15. Dissolved Organic Matter in the Hudson River Plume

    NASA Astrophysics Data System (ADS)

    Chen, R. F.; Gardner, G. B.

    2004-12-01

    As part of the LATTE (Lagrangian Transport and Transformation Experiment) program, dissolved organic carbon (DOC), total nitrogen (TN), and chromophoric dissolved organic matter (CDOM) were measured in the Hudson River Estuary and Plume. As revealed by high resolution measurements from the Integrated Coastal Observation System (ICOS), dissolved organic matter has several sources within the estuary including the Hudson and Raritan Rivers, and a yet unidentified anthropogenic source off Manhattan. The quantity of dissolved organic matter that is exported from the Hudson River Estuary is significantly greater than that which the Hudson River can supply by simply conservative mixing with coastal seawater. In May, 2004, rhodamine dye was injected at the surface as the plume flowed out onto the New York/New Jersey shelf, once as the plume turned north towards Long Island, and once as the plume flowed south along the New Jersey coast. The ECOShuttle (a towed-undulating vehicle) carrying a rhodamine fluorometer was able to track these dye patches. An examination of dissolved organic matter transformations that occurred over these two to two and one-half day Lagrangian experiments will be discussed. In addition seasonal distributions of dissolved organic matter distributions will be presented from cruises in June 2003, June 2004 and September 2004 under different river flow and wind conditions.

  16. 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.

  17. 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,…

  18. PHOTOCHEMICAL TRANSFORMATIONS OF DISSOLVED ORGANIC MATTER IN A BLACKWATER RIVER

    EPA Science Inventory

    We examined photochemical alterations of dissolved organic matter (DOM) from the Satilla River, a high DOC (10-40 mg/liter) blackwater river of southeast Georgia. Water samples were filtered to remove most organisms, placed in quartz tubes, and incubated under natural sunlight a...

  19. 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

  20. Significance of organic matter in Eocene turbidite sediments (SE Pyrenees, Spain)

    NASA Astrophysics Data System (ADS)

    Caja, M. A.; Permanyer, A.

    2008-11-01

    Although turbidite deposits are classically considered to be good reservoir rocks for oil and gas, there are no reports concerning their source rock potential in the literature. The sediments from the Vallfogona Formation in the South-Eastern Pyrenees present numerous organic matter-rich levels interbedded in sandstones and coarse turbidite deposits. Two types of organic matter deposits were differentiated on the basis of organic geochemistry and petrography: type A and type B. Type A was deposited in a carbonate marine environment under hypersaline conditions as indicated mainly by even/odd n-alkane predominance, pristane and phytane ratio (Pr/Ph) < 1, presence of gammacerane, and trisnorneohopane over trisnorhopane ratio (Ts/Tm) > 1. Type B was deposited in a more mud-rich marine environment evidenced by the predominance of odd n-alkane, Pr/Ph ≥ 1, Ts/Tm < 1, the absence of gammacerane, similar concentrations of the C27 and C29 regular steranes, and the greater abundance of C27 diasteranes. Turbidite facies can be regarded as an environment where organic matter sedimentation is heterogeneous in type and amount. This study suggests that turbidite deposits with interbedded organic matter-rich levels may act as a combined source reservoir system.

  1. Significance of organic matter in Eocene turbidite sediments (SE Pyrenees, Spain).

    PubMed

    Caja, M A; Permanyer, A

    2008-11-01

    Although turbidite deposits are classically considered to be good reservoir rocks for oil and gas, there are no reports concerning their source rock potential in the literature. The sediments from the Vallfogona Formation in the South-Eastern Pyrenees present numerous organic matter-rich levels interbedded in sandstones and coarse turbidite deposits. Two types of organic matter deposits were differentiated on the basis of organic geochemistry and petrography: type A and type B. Type A was deposited in a carbonate marine environment under hypersaline conditions as indicated mainly by even/odd n-alkane predominance, pristane and phytane ratio (Pr/Ph) < 1, presence of gammacerane, and trisnorneohopane over trisnorhopane ratio (Ts/Tm) > 1. Type B was deposited in a more mud-rich marine environment evidenced by the predominance of odd n-alkane, Pr/Ph > or = 1, Ts/Tm < 1, the absence of gammacerane, similar concentrations of the C(27) and C(29) regular steranes, and the greater abundance of C(27) diasteranes. Turbidite facies can be regarded as an environment where organic matter sedimentation is heterogeneous in type and amount. This study suggests that turbidite deposits with interbedded organic matter-rich levels may act as a combined source-reservoir system.

  2. The post-Paleozoic chronology and mechanism of 13C depletion in primary marine organic matter

    NASA Technical Reports Server (NTRS)

    Popp, B. N.; Takigiku, R.; Hayes, J. M.; Louda, J. W.; Baker, E. W.

    1989-01-01

    Carbon-isotopic compositions of geoporphyrins have been measured from marine sediments of Mesozoic and Cenozoic age in order to elucidate the timing and extent of depletion of 13C in marine primary producers. These results indicate that the difference in isotopic composition of coeval marine carbonates and marine primary photosynthate was approximately 5 to 7 permil greater during the Mesozoic and early Cenozoic than at present. In contrast to the isotopic record of marine primary producers, isotopic compositions of terrestrial organic materials have remained approximately constant for this same interval of time. This difference in the isotopic records of marine and terrestrial organic matter is considered in terms of the mechanisms controlling the isotopic fractionation associated with photosynthetic fixation of carbon. We show that the decreased isotopic fractionation between marine carbonates and organic matter from the Early to mid-Cenozoic may record variations in the abundance of atmospheric CO2.

  3. 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...

  4. The activated sludge ecosystem contains a core community of abundant organisms

    PubMed Central

    Saunders, Aaron M; Albertsen, Mads; Vollertsen, Jes; Nielsen, Per H

    2016-01-01

    Understanding the microbial ecology of a system requires that the observed population dynamics can be linked to their metabolic functions. However, functional characterization is laborious and the choice of organisms should be prioritized to those that are frequently abundant (core) or transiently abundant, which are therefore putatively make the greatest contribution to carbon turnover in the system. We analyzed the microbial communities in 13 Danish wastewater treatment plants with nutrient removal in consecutive years and a single plant periodically over 6 years, using Illumina sequencing of 16S ribosomal RNA amplicons of the V4 region. The plants contained a core community of 63 abundant genus-level operational taxonomic units (OTUs) that made up 68% of the total reads. A core community consisting of abundant OTUs was also observed within the incoming wastewater to three plants. The net growth rate for individual OTUs was quantified using mass balance, and it was found that 10% of the total reads in the activated sludge were from slow or non-growing OTUs, and that their measured abundance was primarily because of immigration with the wastewater. Transiently abundant organisms were also identified. Among them the genus Nitrotoga (class Betaproteobacteria) was the most abundant putative nitrite oxidizer in a number of activated sludge plants, which challenges previous assumptions that Nitrospira (phylum Nitrospirae) are the primary nitrite-oxidizers in activated sludge systems with nutrient removal. PMID:26262816

  5. Molecular-level analysis of organic matter structure and composition from different soil mineral fractions

    NASA Astrophysics Data System (ADS)

    Clemente, J. S.; Gregorich, E. G.; Simpson, A. J.; Simpson, M. J.

    2009-04-01

    The formation and turnover of soil organic matter (SOM) depends on the inherent chemical characteristics of biomolecular inputs (lignin, proteins, carbohydrates, macromolecular lipids, etc.) as well as the interactions between biomolecules and soil mineral fractions. The objective of this study is to characterize organic matter associated with the light, sand, silt and clay fractions of a Canadian agricultural soil. And, because lignin is believed to be a major contributor in SOM formation and preservation, the oxidation state of lignin in the different mineral fractions was measured using mild alkaline copper oxidation and gas chromatography - mass spectrometery which releases lignin phenols that are indicative of lignin sources and stage of degradation. For example, an increase in the acid/aldehyde (Ad/Al) ratio of lignin phenols has been observed with increased lignin degradation (and oxidation). In this study, lignin phenols from organic matter associated with the clay fraction had higher Ad/Al ratios for both syringyl and vanillyl lignin monomers when compared to that associated with silt, sand and the whole soil. These results suggest that either lignin degradation is enhanced by SOM association with clay surfaces or that oxidized lignin is preserved on clay mineral surfaces via sorption after partial degradation has occurred. The structural characteristics of organic matter from the soil fractions will also be examined by solid-state 13C nuclear magnetic resonance (NMR) spectroscopy. Organic matter associated with each mineral fraction will be extracted with NaOH for high resolution solution-state NMR spectroscopy. Results from NMR analysis will determine the relative abundance of functional groups (alkane, aromatic, carbonyl, alkoxy) in each of the soil fractions. Relative intensities of the functional groups are indicative of relative contributions of biomolecular classes such as lipids, lignin, fatty acids, and sugars to the organic matter associated with

  6. Molecular-Level Analysis of Organic Matter Structure and Composition from Different Soil Mineral Fractions

    NASA Astrophysics Data System (ADS)

    Clemente, J. S.; Gregorich, E. G.; Simpson, A. J.; Simpson, M. J.

    2009-05-01

    The formation and turnover of soil organic matter (SOM) depends on the inherent chemical characteristics of biomolecular inputs (lignin, proteins, carbohydrates, macromolecular lipids, etc.) as well as the interactions between biomolecules and soil mineral fractions. The objective of this study is to characterize organic matter associated with the light, sand, silt and clay fractions of a Canadian agricultural soil. And, because lignin is believed to be a major contributor in SOM formation and preservation, the oxidation state of lignin in the different mineral fractions was measured using mild alkaline copper oxidation and gas chromatography - mass spectrometery which releases lignin phenols that are indicative of lignin sources and stage of degradation. For example, an increase in the acid/aldehyde (Ad/Al) ratio of lignin phenols has been observed with increased lignin degradation (and oxidation). In this study, lignin phenols from organic matter associated with the clay fraction had higher Ad/Al ratios for both syringyl and vanillyl lignin monomers when compared to that associated with silt, sand and the whole soil. These results suggest that either lignin degradation is enhanced by SOM association with clay surfaces or that oxidized lignin is preserved on clay mineral surfaces via sorption after partial degradation has occurred. The structural characteristics of organic matter from the soil fractions will also be examined by solid-state 13C nuclear magnetic resonance (NMR) spectroscopy. Organic matter associated with each mineral fraction will be extracted with NaOH for high resolution solution-state NMR spectroscopy. Results from NMR analysis will determine the relative abundance of functional groups (alkane, aromatic, carbonyl, alkoxy) in each of the soil fractions. Relative intensities of the functional groups are indicative of relative contributions of biomolecular classes such as lipids, lignin, fatty acids, and sugars to the organic matter associated with

  7. Bird diversity and abundance in organic and conventional apple orchards in northern Japan

    PubMed Central

    Katayama, Naoki

    2016-01-01

    Many studies have investigated the benefits of agri-environmental schemes, such as organic farming, on biodiversity conservation in annual systems, but their effectiveness in perennial systems is less well understood, particularly in bird communities in temperate regions of Asia. This study examined the effects of organic farming practices on species richness and abundance of breeding birds in apple orchards in northern Japan. Bird counts were conducted in six pairs of organic and conventional orchards during the breeding season in April and May 2015. The total species richness of birds, estimated by sample- and coverage-based rarefaction and extrapolation curves, was greater in organic orchards than in conventional orchards. Among the three dietary guilds (insectivore, granivore, and omnivore), only insectivorous species were more abundant in organic orchards than in conventional ones. This study offers the first quantitative evidence that organic farming can be beneficial for enhancing the diversity of birds, particularly of insectivores, in fruit orchards in Japan. PMID:27677408

  8. 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.

  9. 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

  10. Transplanting an organization: how does culture matter.

    PubMed

    Munich, Richard L

    2011-01-01

    Cultural differences are often cited as a major obstacle to the successful transition/integration into new situations of organizations. In this contribution, the author details the changing cultural factors impacting the operation and move of the Menninger Clinic from autonomous status to an affiliation with and first year of operation in the Baylor College of Medicine and Methodist Hospital Health Care System. Both functional and dysfunctional consequences are outlined, and specific examples illustrate how the organization's leadership and staff struggled to adapt during this complicated process. Based on the experience within the Clinic, general recommendations for managing such an acculturation are provided.

  11. 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.

  12. 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.

  13. Consequences of organic farming and landscape heterogeneity for species richness and abundance of farmland birds.

    PubMed

    Smith, Henrik G; Dänhardt, Juliana; Lindström, Ake; Rundlöf, Maj

    2010-04-01

    It has been suggested that organic farming may benefit farmland biodiversity more in landscapes that have lost a significant part of its former landscape heterogeneity. We tested this hypothesis by comparing bird species richness and abundance during the breeding season in organic and conventional farms, matched to eliminate all differences not directly linked to the farming practice, situated in either homogeneous plains with only a little semi-natural habitat or in heterogeneous farmland landscapes with abundant field borders and semi-natural grasslands. The effect of farm management on species richness interacted with landscape structure, such that there was a positive relationship between organic farming and diversity only in homogeneous landscapes. This pattern was mainly dependent on the species richness of passerine birds, in particular those that were invertebrate feeders. Species richness of non-passerines was positively related to organic farming independent of the landscape context. Bird abundance was positively related to landscape heterogeneity but not to farm management. This was mainly because the abundance of passerines, particularly invertebrate feeders, was positively related to landscape heterogeneity. We suggest that invertebrate feeders particularly benefit from organic farming because of improved foraging conditions through increased invertebrate abundances in otherwise depauperate homogeneous landscapes. Although many seed-eaters also benefit from increased insect abundance, they may also utilize crop seed resources in homogeneous landscapes and conventional farms. The occurrence of an interactive effect of organic farming and landscape heterogeneity on bird diversity will have consequences for the optimal allocation of resources to restore the diversity of farmland birds.

  14. Importance of microbial soil organic matter processing in dissolved organic carbon production.

    PubMed

    Malik, Ashish; Gleixner, Gerd

    2013-10-01

    Soil dissolved organic carbon (DOC) sources and its seasonal dynamics are poorly known. We aimed to determine the contribution of plant and soil organic matter (SOM) to size classes of DOC in a field experiment with C3 to C4 vegetation change on two soil types through different seasons. Stable isotope ratios of DOC size classes were measured using size exclusion chromatography (SEC) coupled online to liquid chromatography-isotope ratio mass spectrometry (LC-IRMS). SEC resolved DOC into three size classes: very high molecular weight/vHMW (> 10 kDa), high molecular weight/HMW (0.4-10 kDa), and low molecular weight/LMW (< 0.4 kDa). HMW DOC was most abundant in all seasons, soil types, and depths. In contrast, vHMW DOC was only seen postsnowmelt in upper 20 cm and was mainly (87 ± 9%) plant-derived. Through all seasons, HMW and LMW DOC had less than 30% recent plant contribution. Similar size range and source of DOC size classes and soil chloroform fumigation extracts suggest microbial origin of DOC. Thus, microbial SOM recycling is an important process in DOC production. We suggest that DOC molecules get partitioned manifold between soil solution and the mineral matrix (chromatography), thereby getting constantly decomposed, altered, or produced anew by soil microorganisms (reactive transport).

  15. 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.

  16. Characterization and origin of polar dissolved organic matter from the Great Salt Lake

    USGS Publications Warehouse

    Leenheer, J.A.; Noyes, T.I.; Rostad, C.E.; Davisson, M.L.

    2004-01-01

    Polar dissolved organic matter (DOM) was isolated from a surface-water sample from the Great Salt Lake by separating it from colloidal organic matter by membrane dialysis, from less-polar DOM fractions by resin sorbents, and from inorganic salts by a combination of sodium cation exchange followed by precipitation of sodium salts by acetic acid during evaporative concentration. Polar DOM was the most abundant DOM fraction, accounting for 56% of the isolated DOM. Colloidal organic matter was 14C-age dated to be about 100% modern carbon and all of the DOM fractions were 14C-age dated to be between 94 and 95% modern carbon. Average structural models of each DOM fraction were derived that incorporated quantitative elemental and infrared, 13C-NMR, and electrospray/mass spectrometric data. The polar DOM model consisted of open-chain N-acetyl hydroxy carboxylic acids likely derived from N-acetyl heteropolysaccharides that constituted the colloidal organic matter. The less polar DOM fraction models consisted of aliphatic alicyclic ring structures substituted with carboxyl, hydroxyl, ether, ester, and methyl groups. These ring structures had characteristics similar to terpenoid precursors. All DOM fractions in the Great Salt Lake are derived from algae and bacteria that dominate DOM inputs in this lake.

  17. Organic Matter in Rivers: The Crossroads between Climate and Water Quality

    SciTech Connect

    Davisson, M L

    2001-04-27

    All surface waters in the world contain dissolved organic matter and its concentration depends on climate and vegetation. Dissolved organic carbon (DOC) is ten times higher in wetlands and swamps than in surface water of arctic, alpine, or arid climate. Climates of high ecosystem productivity (i.e., tropics) typically have soils with low organic carbon storage, but drain high dissolved organic loads to rivers. Regions with lower productivity (e.g. grasslands) typically have high soil carbon storage while adjacent rivers have high DOC contents. Most DOC in a free-flowing river is derived from leaching vegetation and soil organic matter, whereas in dammed rivers algae may comprise a significant portion. Water chemistry and oxygen-18 abundance of river water, along with radiocarbon and carbon-13 isotope abundance measurements of DOC were used to distinguish water and water quality sources in the Missouri River watershed. Drinking water for the City of St. Louis incorporates these different sources, and its water quality depends mostly on whether runoff is derived from the upper or the lower watershed, with the lower watershed contributing water with the highest DOC. During drinking water chlorination, DOC forms carcinogenic by-products in proportion to the amount of DOC present. This has recently led the USEPA to propose federal regulation standards. Restoration of natural riparian habitat such as wetlands will likely increase DOC concentrations in river water.

  18. Scavenging of soluble organic matter from the prebiotic oceans.

    PubMed

    Nissenbaum, A

    1976-12-01

    The existence of hot or cold "nutrient broth" or "primeval soup" is challenged on the basis of the recent geochemistry of soluble organic carbon in the oceans. Most of the dissolved organic carbon is recycled quickly by organisms, but the residual, biologically refractive, organic matter is efficiently scavenged from the oceans (residence time of 1000 to 3500 years) by nonbiologically mediated chemical and physical processes, such as adsorption on sinking minerals, polymerization and aggregation to humic type polymers or by aggregation to particulate matter through bubbling and sinking of this material to the ocean bottom. Since there is no reason to believe that such nonbiological scavenging was not operative in the prebiotic oceans as well, then the prolonged existence of "organic soup" is very doubtful. The question of the origin of life is thus assumed to be related to solid-liquid interfacial activity, and the answer may be associated with sediment-water interaction rather than with solution chemistry.

  19. Natural, anthropogenic and fossil organic matter in river sediments and suspended particulate matter: a multi-molecular marker approach.

    PubMed

    Micić, V; Kruge, M A; Köster, J; Hofmann, T

    2011-02-01

    Different classes of organic matter (OM) have been systematically investigated in sediments and suspended particulate matter (SPM) along the Danube River in order to understand causes of compositional changes. Analytical pyrolysis revealed the dominance of natural organic matter (NOM) in most of the samples. The predominance of aquatic biomass is evident mainly from the abundance of organonitrogen compounds and phenol distributions. As the river enters a forested gorge, the terrestrial component of the NOM in sediments is more significant. This is reflected in abundant methoxyphenols and a very high carbon preference index. SPM sample from a tributary shows a unique geochemical signature. It contains abundant carboxylic acids, amines, isoprenoids in the pyrolyzate, and is dominated by phytol and 24-methyl-cholesta-5,24(28)-dien-3β-ol in the extract, produced by a diatom bloom. Wax esters with a relatively high proportion of short, methyl-branched alkyl-chains appear together with abundant phytadienes and n-C(17) alkane in some samples, suggesting a microbial origin. Anthropogenic OM from runoff and atmospheric deposition was evident from a minor input of polycyclic aromatic hydrocarbons (PAHs) originating from mixed combustion sources. Multivariate analysis using PAH data led us to define simple molecular ratios to distinguish the PAH composition in sand and silty sediments. The newly defined ratios are the alkylated phenanthrenes and anthracenes ratio (APA; C(1)-C(3)/C(0)-C(3) phenanthrenes and anthracenes) and the PAH ring number ratio (RN; 5-6 ring parent PAHs/all parent PAHs). This demonstrates that alkylated, as well as 5-6 ring PAHs are better preserved in the finer than in coarser grained sediments. A ubiquitous, but minor input of petroleum-related contamination with a uniform composition was evident in all samples as revealed by the analysis of petroleum biomarkers. This study demonstrates that the investigation of different classes of riverine OM

  20. Influence of organic matter on collembolan communities in reedbed habitats

    NASA Astrophysics Data System (ADS)

    Uteseny, K.; Drapela, T.; Frouz, J.

    2009-04-01

    The combination of the organic matter, micro-climatic environments and plant cover belongs to important factors for the distribution of soil meso-fauna, especially Collembola. There are no studies attending to these factors on collembolan communities in reedbed vegetation. The main goals of our investigation were therefore to compare diversity of Collembola in redbed habitats of Lake Neudsiedl, eastern Austria, and to assess particularly the role of organic matter with regard to the collembolan community structure. Soil samples were taken from April 1997 to October 1997 at fifteen study sites covered with Phragmatis australis of different age. Changes in the structure and composition of the assemblages of Collembola were examined.

  1. 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.

  2. 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

  3. 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

  4. Pre-biotic organic matter from comets and asteroids.

    PubMed

    Anders, E

    1989-11-16

    Several authors have suggested that comets or carbonaceous asteroids contributed large amounts of organic matter to the primitive Earth, and thus possibly played a vital role in the origin of life. But organic matter cannot survive the extremely high temperatures (>10(4) K) reached on impact, which atomize the projectile and break all chemical bonds. Only fragments small enough to be gently decelerated by the atmosphere--principally meteors of 10(-12)-10(-6) g--can deliver their 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 approximately 0.006 g cm-2 intact organic carbon would accumulate in 10(8) yr, but at the higher rates of approximately 4 x 10(9) yr ago, about 20 g cm-2 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.

  5. 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

  6. 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.

  7. 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.

  8. 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.

  9. Biomass burning as the main source of organic aerosol particulate matter in Malaysia during haze episodes.

    PubMed

    Radzi bin Abas, M; Oros, Daniel R; Simoneit, B R T

    2004-05-01

    The haze episodes that occurred in Malaysia in September-October 1991, August-October 1994 and September-October 1997 have been attributed to suspended smoke particulate matter from biomass burning in southern Sumatra and Kalimantan, Indonesia. In the present study, polar organic compounds in aerosol particulate matter from Malaysia are converted to their trimethylsilyl derivatives and analyzed by gas chromatography-mass spectrometry in order to better assess the contribution of the biomass burning component during the haze episodes. On the basis of this analysis, levoglucosan was found to be the most abundant organic compound detected in almost all samples. The monosaccharides, alpha- and beta-mannose, the lignin breakdown products, vanillic and syringic acids and the minor steroids, cholesterol and beta-sitosterol were also present in some samples. The presence of the tracers from smoke overwhelmed the typical signatures of emissions from traffic and other anthropogenic activities in the urban areas.

  10. Abundance matters: a field experiment testing the more individuals hypothesis for richness–productivity relationships

    PubMed Central

    Yee, D. A.; Juliano, S. A.

    2007-01-01

    The more individuals hypothesis (MIH) postulates that productivity increases species richness by increasing mean equilibrium population size, thereby reducing the probability of local extinction. We tested the MIH for invertebrates colonizing microcosms that simulated tree holes by manipulating productivity through additions of leaf or animal detritus and subsequently determining the relationships among richness, total abundance, abundance per species, and measures of productivity. We quantified productivity as the rate of microorganism protein synthesis, microorganism metabolic rate, nutrient ion concentration, and type and amount of detritus. Microcosms with animal detritus attracted more species, more individuals per species, and more total individuals than did microcosms with similar amounts of leaf detritus. Relationships between richness or abundance and productivity varied with date. Richness in June increased as a linear function of productivity, whereas the power function predicted by the MIH fit best in July. Abundance in June and July was best described by a power function of productivity, but the linear function predicted by the MIH fit best in September. Abundance per species was best described by a power function of productivity in June and July. Path analysis showed that the indirect effect of productivity through abundance on richness that is predicted by MIH was important in all months, and that direct links between productivity and richness were unnecessary. Our results support many of the predictions of the MIH, but they also suggest that the effects of abundance on richness may be more complex than expected. PMID:17401581

  11. The Contribution of Fungal Necromass to Soil Organic Matter Storage

    NASA Astrophysics Data System (ADS)

    Schreiner, K. M.; Blair, N. E.; Buiser, A.; Egerton-Warburton, L.

    2013-12-01

    Saprotrophic fungi have the ability to degrade the three most important biopolymers: cellulose, lignin, and chitin, and therefore are key moderators of a globally important flow of carbon. However, little is known about how that carbon is transformed and/or stored in soil organic matter (SOM). Fungi are also known to produce a variety of biopolymers, such as chitin, melanin, glucan, and mucus-like exudates, and it is likely that these compounds contribute to long-term storage of SOM. In fact, recent work with ectomycorrhizal fungi has shown that a portion of the fungal necromass survives after degradation times of a few weeks to one month (e.g. Drigo et al. 2012, Clemmenson et al. 2013). Until now, the potential contribution of other abundant fungi to recalcitrant SOM has been unknown. Soil incubations have been performed with the common saprotrophic fungus, Fusarium avencum. Approximately 80% of the fungal material was found to turnover over on a time period of days, but 15% of the original biomass was left over at the end of the two-month degradation experiment in both laboratory experiments and in situ in the Dixon Prairie of the Chicago Botanic Garden. In both experiments, degradation was performed by a natural soil microbial consortium. Residual fungal material at each point in the decomposition sequence was analyzed using FTIR and thermochemolysis-GCMS with tetramethyl ammonium hydroxide. The recalcitrant fraction contained carbohydrate and amide-linked functional groups, which is consistent with the chitin or chitosan biopolymer. The breakdown of more labile organic carbon (including proteins and ester-linked groups) appears to occur on a more rapid time scale. Additionally, lipid biomarker analyses revealed a succession of microbial degraders in the degradation process. This is the first time a study of this kind has been performed using a widely distributed saprotrophic fungus, and indicates that these fungi are potentially important in long-term C

  12. Chemoselective single-site Earth-abundant metal catalysts at metal-organic framework nodes.

    PubMed

    Manna, Kuntal; Ji, Pengfei; Lin, Zekai; Greene, Francis X; Urban, Ania; Thacker, Nathan C; Lin, Wenbin

    2016-01-01

    Earth-abundant metal catalysts are critically needed for sustainable chemical synthesis. Here we report a simple, cheap and effective strategy of producing novel earth-abundant metal catalysts at metal-organic framework (MOF) nodes for broad-scope organic transformations. The straightforward metalation of MOF secondary building units (SBUs) with cobalt and iron salts affords highly active and reusable single-site solid catalysts for a range of organic reactions, including chemoselective borylation, silylation and amination of benzylic C-H bonds, as well as hydrogenation and hydroboration of alkenes and ketones. Our structural, spectroscopic and kinetic studies suggest that chemoselective organic transformations occur on site-isolated, electron-deficient and coordinatively unsaturated metal centres at the SBUs via σ-bond metathesis pathways and as a result of the steric environment around the catalytic site. MOFs thus provide a novel platform for the development of highly active and affordable base metal catalysts for the sustainable synthesis of fine chemicals.

  13. Chemoselective single-site Earth-abundant metal catalysts at metal-organic framework nodes

    NASA Astrophysics Data System (ADS)

    Manna, Kuntal; Ji, Pengfei; Lin, Zekai; Greene, Francis X.; Urban, Ania; Thacker, Nathan C.; Lin, Wenbin

    2016-08-01

    Earth-abundant metal catalysts are critically needed for sustainable chemical synthesis. Here we report a simple, cheap and effective strategy of producing novel earth-abundant metal catalysts at metal-organic framework (MOF) nodes for broad-scope organic transformations. The straightforward metalation of MOF secondary building units (SBUs) with cobalt and iron salts affords highly active and reusable single-site solid catalysts for a range of organic reactions, including chemoselective borylation, silylation and amination of benzylic C-H bonds, as well as hydrogenation and hydroboration of alkenes and ketones. Our structural, spectroscopic and kinetic studies suggest that chemoselective organic transformations occur on site-isolated, electron-deficient and coordinatively unsaturated metal centres at the SBUs via σ-bond metathesis pathways and as a result of the steric environment around the catalytic site. MOFs thus provide a novel platform for the development of highly active and affordable base metal catalysts for the sustainable synthesis of fine chemicals.

  14. Organic Matter Loading Modifies the Microbial Community Responsible for Nitrogen Loss in Estuarine Sediments.

    PubMed

    Babbin, Andrew R; Jayakumar, Amal; Ward, Bess B

    2016-04-01

    Coastal marine sediments, as locations of substantial fixed nitrogen loss, are very important to the nitrogen budget and to the primary productivity of the oceans. Coastal sediment systems are also highly dynamic and subject to periodic natural and anthropogenic organic substrate additions. The response to organic matter by the microbial community involved in nitrogen loss processes was evaluated using mesocosms of Chesapeake Bay sediments. Over the course of a 50-day incubation, rates of anammox and denitrification were measured weekly using (15)N tracer incubations, and samples were collected for genetic analysis. Rates of both nitrogen loss processes and gene abundances associated with them corresponded loosely, probably because heterogeneities in sediments obscured a clear relationship. The rates of denitrification were stimulated more, and the fraction of nitrogen loss attributed to anammox slightly reduced, by the higher organic matter addition. Furthermore, the large organic matter pulse drove a significant and rapid shift in the denitrifier community composition as determined using a nirS microarray, indicating that the diversity of these organisms plays an essential role in responding to anthropogenic inputs. We also suggest that the proportion of nitrogen loss due to anammox in these coastal estuarine sediments may be underestimated due to temporal dynamics as well as from methodological artifacts related to conventional sediment slurry incubation approaches. PMID:26520832

  15. 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

  16. 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

  17. 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.

  18. 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...

  19. 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...

  20. 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 ...

  1. 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.

  2. 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...

  3. 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...

  4. Molecular characterization of dissolved organic matter in pore water of continental shelf sediments

    NASA Astrophysics Data System (ADS)

    Schmidt, Frauke; Elvert, Marcus; Koch, Boris P.; Witt, Matthias; Hinrichs, Kai-Uwe

    2009-06-01

    Dissolved organic matter (DOM) in sediment pore water is a complex molecular mixture reflecting various sources and biogeochemical processes. In order to constrain those sources and processes, molecular variations of pore water DOM in surface sediments from the NW Iberian shelf were analyzed by ultrahigh-resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) and compared to river and marine water column DOM. Weighted average molecular element ratios of oxygen to carbon ((O/C) wa) and hydrogen to carbon ((H/C) wa) provided general information about DOM sources. DOM in local rivers was more oxygenated ((O/C) wa 0.52) and contained less hydrogen ((H/C) wa 1.15) than marine pore water DOM (mean (O/C) wa 0.50, mean (H/C) wa 1.26). The relative abundance of specific compound groups, such as highly oxygenated aromatic compounds or nitrogen-bearing compounds with low H/C ratios, correspond to a high concentration of lignin phenols (160 μg/g sediment dry weight) and a high TOC/TN ratio (13.3) in the sedimentary organic matter and were therefore assigned to terrestrial sources. The lower degree of unsaturation and a higher relative abundance of nitrogen-bearing compounds in the pore water DOM reflected microbial activity within the sediment. One sampling site on the shelf with a high sediment accumulation, and a humic-rich river sample showed a wide range of sulfur compounds in the DOM, accompanied by a higher abundance of lipid biomarkers for sulfate-reducing bacteria, probably indicating early diagenetic sulfurization of organic matter.

  5. 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.

  6. Characterisation of the organic matter pool in manures.

    PubMed

    Moral, R; Moreno-Caselles, J; Perez-Murcia, M D; Perez-Espinosa, A; Rufete, B; Paredes, C

    2005-01-01

    In this research, different types of animal manure were evaluated with respect to organic matter (OM), total organic carbon (C(ot)), total N (N(t)), C(ot)/N(t) ratio, water-soluble organic carbon (C(w)), organic N (N(org)), carbohydrates, C(w)/N(org) ratio, humic acid-like carbon (C(ha)), fulvic acid-like carbon (C(fa)), humification index ((C(ha)/C(ot))x100) (HI) and the C(ha)/C(fa) and NH(4)(+)-N/NO(3)(-)-N ratios. In comparison with the limits set by the Spanish legislation for organic fertilisers, most of the manures had high OM contents, moderate N(org) concentrations (except in the case of the chicken and pig manures where this parameter was high) and C(ot)/N(t) ratios above the value stated in the legislation. The study of the different fractions of organic matter showed that the horse, pig and rabbit manures had the greatest content of C(ot). However, the fraction of easily-biodegradable organic compounds (C(w)) was significantly higher in the horse, goat and chicken manures. The study also showed that, in most cases, the percentage of fulvic acid-like C was greater than that of the humic acid-like C, indicating that the organic matter of these wastes is not completely humified. Values of HI ((C(ha)/C(ot))x100) and C(ha)/C(fa) ratio in the studied manures were not significantly different. Regarding the parameters related to the organic matter stability such as C(w), carbohydrates and the C(ot)/N(t), C(w)/N(org) and NH(4)(+)-N/NO(3)(-)-N ratios, it has been determined that the organic matter of these materials was not completely stabilised. The heterogeneity in OM composition of the studied manures did not allow the formulation of simple equations for evaluation of the composition of these wastes from easily-determined parameters.

  7. 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.

  8. 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.

  9. 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.

  10. Nature of particulate organic matter in the River Indus, Pakistan

    NASA Astrophysics Data System (ADS)

    Ittekkot, Venugopalan; Arain, Rafee

    1986-08-01

    Suspended sediments from the Indus River collected during 1981 through 1983 were analyzed for POC and its constituent fractions including amino acids, amino sugars and sugars. Percentage of POC decreased with increasing suspended matter concentrations, which suggested dilution of organic matter by mineral matter. The concentrations of amino acids, amino sugars and sugars varied, respectively, between 180 and 2000 μg/l, 5 and 125 μg/l, and 60 and 1100 μg/l. Their contributions to POC varied between 2 and 60% for amino acids and amino sugars, and between 2 and 15% for sugars. They were high during low sediment discharge (February to June), and low during high sediment discharge (August and September). Suspended sediments associated with high sediment discharge periods were characterized by low ratios of: (i) aspartic acid:β-alanine (ii) glutamic acid:γ-aminobutyric acid (iii) amino acids:amino sugars (iv) hexoses:pentoses. These and the relative distribution pattern of the monosaccharides such as galactose, arabinose, mannose and xylose indicated that, not only dilution, but also differences in the sources and processes affect the POC transport in the Indus River. These result in transport of biodegraded organic matter during high sediment discharge periods: this appears to be common to other major rivers of the region, with depositional centers in deep sea areas. These rivers, with their high sediment loads, could contribute up to 8 to 11% of the global annual organic carbon burial in marine sediments.

  11. X-RAY PROPERTIES OF YOUNG EARLY-TYPE GALAXIES. II. ABUNDANCE RATIO IN THE HOT INTERSTELLAR MATTER

    SciTech Connect

    Kim, Dong-Woo; Fabbiano, Giuseppina; Pipino, Antonio

    2012-05-20

    Using Chandra X-ray observations of young, post-merger elliptical galaxies, we present X-ray characteristics of age-related observational results by comparing them with typical old elliptical galaxies in terms of metal abundances in the hot interstellar matter (ISM). While the absolute element abundances may be uncertain because of unknown systematic errors and partly because of the smaller amount of hot gas in young ellipticals, the relative abundance ratios (e.g., the {alpha}-element to Fe ratio, and most importantly the Si/Fe ratio) can be relatively well constrained. In two young elliptical galaxies (NGC 720 and NGC 3923) we find that the Si to Fe abundance ratio is super-solar (at a 99% significance level), in contrast to typical old elliptical galaxies where the Si to Fe abundance ratio is close to solar. Also, the O/Mg ratio is close to solar in the two young elliptical galaxies, as opposed to the sub-solar O/Mg ratio reported in old elliptical galaxies. Both features appear to be less significant outside the effective radius (roughly 30'' for the galaxies under study), consistent with the observations that confine to the centermost regions the signatures of recent star formation in elliptical galaxies. Observed differences between young and old elliptical galaxies can be explained by the additional contribution from SNe II ejecta in the former. In young elliptical galaxies, the later star formation associated with recent mergers would have a dual effect, resulting both in galaxy scale winds-and therefore smaller observed amounts of hot ISM-because of the additional SN II heating, and in different metal abundances, because of the additional SN II yields.

  12. Organic amendments enhance microbial diversity and abundance of functional genes in Australian Soils

    NASA Astrophysics Data System (ADS)

    Aldorri, Sind; McMillan, Mary; Pereg, Lily

    2016-04-01

    Food and cash crops play important roles in Australia's economy with black, grey and red clay soil, widely use for growing cotton, wheat, corn and other crops in rotation. While the majority of cotton growers use nitrogen and phosphate fertilizers only in the form of agrochemicals, a few experiment with the addition of manure or composted plant material before planting. We hypothesized that the use of such organic amendments would enhance the soil microbial function through increased microbial diversity and abundance, thus contribute to improved soil sustainability. To test the hypothesis we collected soil samples from two cotton-growing farms in close geographical proximity and with mostly similar production practices other than one grower has been using composted plants as organic amendment and the second farmer uses only agrochemicals. We applied the Biolog Ecoplate system to study the metabolic signature of microbial communities and used qPCR to estimate the abundance of functional genes in the soil. The soil treated with organic amendments clearly showed higher metabolic activity of a more diverse range of carbon sources as well as higher abundance of genes involved in the nitrogen and phosphorous cycles. Since microbes undertake a large number of soil functions, the use of organic amendments can contribute to the sustainability of agricultural soils.

  13. Direct Evidence Linking Soil Organic Matter Development to Microbial Communities

    NASA Astrophysics Data System (ADS)

    Kallenbach, C.; Grandy, S.

    2013-12-01

    Despite increasing recognition of microbial contributions to soil organic matter (SOM) formation there is little experimental evidence linking microbial processes to SOM development and the mechanisms responsible remain unclear. Specifically, if stable SOM is largely comprised of microbial products, we need to better understand the soil conditions that influence microbial biomass production and ultimately its stability. Microbial physiology, such as microbial growth efficiency (MGE) and rate (MGR) have direct influences on microbial biomass production and are highly sensitive to resource quality. Therefore, the importance of resource quality on SOM is not necessarily a function of resistance to decay but the degree to which it optimizes microbial biomass production. While resource quality may have an indirect effect on SOM abundance via its influence on microbial physiology, SOM stabilization of labile microbial products may rely heavily on a soil's capacity to form organo-mineral interactions. To examine the relative importance of soil microbial community function, resource quality and mineralogy on direct microbial contributions to SOM formation and stability, an ongoing 15-mo incubation experiment was set up using artificial, initially C- and microbial-free soils. Soil microcosms were constructed by mixing sand with either kaolinite or montmorillonite clays followed with a natural soil microbial inoculum. For both soil mineral treatments, weekly additions of glucose, cellobiose, or syringol are carried out, with an additional treatment of plant leachate to serve as a reference. This simplified system allows us to determine if, in the absence of plant-derived C, microbial products using simple substrates can result in chemically complex SOM similar to natural soils. Over the course of the incubation, MGE, MGR, microbial activity, and SOM accumulation rates are monitored. Pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) is used to track the microbial

  14. Hydrographic controls on marine organic matter fate and microbial diversity in the western Irish Sea

    NASA Astrophysics Data System (ADS)

    O'Reilly, Shane; Szpak, Michal; Monteys, Xavier; Flanagan, Paul; Allen, Christopher; Kelleher, Brian

    2014-05-01

    Cycling of organic matter (OM) is the key biological process in the marine environment1 and knowledge of the sources and the reactivity of OM, in addition to factors controlling its distribution in estuarine, coastal and shelf sediments are of key importance for understanding global biogeochemical cycles2. With recent advances in cultivation-independent molecular approaches to microbial ecology, the key role of prokaryotes in global biogeochemical cycling in marine ecosystems has been emphasised3,4. However, spatial studies combining the distribution and fate of OM with microbial community abundance and diversity remain rare. Here, a combined spatial lipid biomarker and 16S rRNA tagged pyrosequencing study was conducted in surface sediments and particulate matter across hydrographically distinct zones associated with the seasonal western Irish Sea gyre. The aim was to assess the spatial variation of, and factors controlling, marine organic cycling and sedimentary microbial communities across these distinct zones. The distribution of phospholipid fatty acids, source-specific sterols, wax esters and C25 highly branched isoprenoids indicate that diatoms, dinoflagellates and green algae were the major contributors of marine organic matter, while the distribution of cholesterol, wax esters and C20 and C22 polyunsaturated fatty acids have highlighted the importance of copepod grazing for mineralizing organic matter in the water column5. This marine OM production and mineralisation was greatest in well-mixed waters compared to offshore stratified waters. Lipid analysis and 16S rRNA PCR-DGGE profiling also suggests that sedimentary bacterial abundance increases while community diversity decreases in offshore stratified waters. The major bacterial classes are the Deltaproteobacteria, Clostridia, Flavobacteriia, Gammaproteobactera and Bacteroiidia. At the family/genus level most groups appear to be associated with organoheterotrophic processing of sedimentary OM, ranging

  15. 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.

  16. Sedimentary process control on carbon isotope composition of sedimentary organic matter in an ancient shallow-water shelf succession

    NASA Astrophysics Data System (ADS)

    Davies, S. J.; Leng, M. J.; Macquaker, J. H. S.; Hawkins, K.

    2012-11-01

    Source and delivery mechanisms of organic matter are rarely considered when interpreting changing δ13C through sedimentary successions even though isotope excursions are widely used to identify and correlate global perturbations in the carbon cycle. Combining detailed sedimentology and geochemistry we demonstrate how organic carbon abundance and δ13C values from sedimentary organic matter from Carboniferous-aged mudstones are influenced by the proportion of terrestrial versus water column-derived organic matter. Silt-bearing clay-rich shelf mudstones that were deposited by erosive density flows are characterized by 1.8-2.4% organic carbon and highδ13C values (averaging -22.9 ± 0.3‰, n = 12). Typically these mudstones contain significant volumes of terrestrial plant-derived material. In contrast, clay-rich lenticular mudstones, with a marine macrofauna, are the products of the transport of mud fragments, eroded from pre-existing water-rich shelfal muds, when shorelines were distant and biological productivity in the water column was high. Higher organic carbon (2.1-5.2%) and lowerδ13C values (averaging -24.3 ± 0.5‰, n = 11) characterize these mudstones and are interpreted to reflect a greater contribution by (isotopically more negative) amorphous organic matter derived from marine algae. Differences in δ13C between terrestrial and marine organic matter allow the changing proportions from different sources to be tracked through this succession. Combining δ13C values with zirconium (measured from whole rock), here used as a proxy for detrital silt input, provides a novel approach to distinguishing mudstone provenance and ultimately using δ13C to identify oil-prone organic matter in potential source rocks. These results have important implications for using bulk organic matter to identify and characterize global C-isotope excursions.

  17. Cu Binding to Iron Oxide-Organic Matter Coprecipitates in Solid and Dissolved Phases

    NASA Astrophysics Data System (ADS)

    Vadas, T. M.; Koenigsmark, F.

    2015-12-01

    Recent studies indicate that Cu is released from wetlands following storm events. Assymetrical field flow field fractionation (AF4) analyses as well as total and dissolved metal concentration measurements suggest iron oxide-organic matter complexes control Cu retention and release. Coprecipitation products of Fe oxide and organic matter were prepared under conditions similar to the wetland to assess Cu partitioning to and availability from solid phases that settle from solution as well as phases remaining suspended. Cu coprecipitation and sorption to organomineral precipitation solids formed at different Fe:organic carbon (OC) ratios were compared for net Cu removal and extractability. As more humic acid was present during precipitation of Fe, TEM images indicated smaller Fe oxide particles formed within an organic matrix as expected. In coprecipitation reactions, as the ratio of Fe:OC decreased, more Cu was removed from solution at pH 5.5 and below. However, in sorption reactions, there was an inhibition of Cu removal at low OC concentrations. As the pH increased from 5.5 to 7 and as solution phase OC concentration increased, more Cu remained dissolved in both coprecipitation and sorption reactions. The addition of Ca2+, glycine, histidine and citric acid or lowering the pH resulted in more extractable Cu from the coprecipitation compared with the sorption reactions. The variations in Cu extraction were likely due to a combination of a more amorphous structure in CPT products, and the relative abundance of available Fe oxide or OC binding sites. Suspended Fe oxide-organic matter coprecipitates were assessed using AF4 coupled to online TOC analysis and ICP-MS. In laboratory prepared samples, Cu was observed in a mixture of small 1-5 nm colloids of Fe oxide-organic matter precipitates, but the majority was observed in larger organic matter colloids and were not UV absorbing, suggesting more aliphatic carbon materials. In field samples, up to 60% of the dissolved Cu

  18. Dark matter relic abundance and big bang nucleosynthesis in Horava's gravity

    SciTech Connect

    Lambiase, G.

    2011-05-15

    The cosmological consequences of Horava's gravity are reviewed in the frameworks of the PAMELA experiment (which has reported an excess of positron events that likely can be ascribed to weakly interacting massive particles dark matter) and of big bang nucleosynthesis. Constraints on parameters characterizing Horawa's cosmology are derived.

  19. Arsenic and selenium mobilisation from organic matter treated mine spoil with and without inorganic fertilisation.

    PubMed

    Moreno-Jiménez, Eduardo; Clemente, Rafael; Mestrot, Adrien; Meharg, Andrew A

    2013-02-01

    Organic matter amendments are applied to contaminated soil to provide a better habitat for re-vegetation and remediation, and olive mill waste compost (OMWC) has been described as a promising material for this aim. We report here the results of an incubation experiment carried out in flooded conditions to study its influence in As and metal solubility in a trace elements contaminated soil. NPK fertilisation and especially organic amendment application resulted in increased As, Se and Cu concentrations in pore water. Independent of the amendment, dimethylarsenic acid (DMA) was the most abundant As species in solution. The application of OMWC increased pore water dissolved organic-carbon (DOC) concentrations, which may explain the observed mobilisation of As, Cu and Se; phosphate added in NPK could also be in part responsible of the mobilisation caused in As. Therefore, the application of soil amendments in mine soils may be particularly problematic in flooded systems.

  20. 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.

  1. Determination of Natural 14C Abundances in Dissolved Organic Carbon in Organic-Rich Marine Sediment Porewaters by Thermal Sulfate Reduction

    NASA Astrophysics Data System (ADS)

    Johnson, L.; Komada, T.

    2010-12-01

    The abundances of natural 14C in dissolved organic carbon (DOC) in the marine environment hold clues regarding the processes that influence the biogeochemical cycling of this large carbon reservoir. At present, UV irradiation is the widely accepted method for oxidizing seawater DOC for determination of their 14C abundances. This technique yields precise and accurate values with low blanks, but it requires a dedicated vacuum line, and hence can be difficult to implement. As an alternative technique that can be conducted on a standard preparatory vacuum line, we modified and tested a thermal sulfate reduction method that was previously developed to determine δ13C values of marine DOC (Fry B. et al., 1996. Analysis of marine DOC using a dry combustion method. Mar. Chem., 54: 191-201.) to determine the 14C abundances of DOC in marine sediment porewaters. In this method, the sample is dried in a 100 ml round-bottom Pyrex flask in the presence of excess oxidant (K2SO4) and acid (H3PO4), and combusted at 550 deg.C. The combustion products are cryogenically processed to collect and quantify CO2 using standard procedures. Materials we have oxidized to date range from 6-24 ml in volume, and 95-1500 μgC in size. The oxidation efficiency of this method was tested by processing known amounts of reagent-grade dextrose and sucrose (as examples of labile organic matter), tannic acid and humic acid (as examples of complex natural organic matter), and porewater DOC extracted from organic-rich nearshore sediments. The carbon yields for all of these materials averaged 99±4% (n=18). The 14C abundances of standard materials IAEA C-6 and IAEA C-5 processed by this method using >1mgC aliquots were within error of certified values. The size and the isotopic value of the blank were determined by a standard dilution technique using IAEA C-6 and IAEA C-5 that ranged in size from 150 to 1500 μgC (n=4 and 2, respectively). This yielded a blank size of 6.7±0.7 μgC, and a blank isotopic

  2. Role of organic matter in framboidal pyrite oxidation.

    PubMed

    Rigby, P A; Dobos, S K; Cook, F J; Goonetilleke, A

    2006-08-31

    An experimental system has been set up to investigate the reaction kinetics of framboidal pyrite oxidation in real, reactive acid sulfate soil assemblages. This study was undertaken to determine the degree to which pyrite oxidation rates are reduced by bacteriological reactions and organic matter, which both modify the net reaction mechanisms and compete for available oxygen. The results from these experimental runs not only confirm the role of organic matter in mitigating pyrite oxidation but indicate that at least initially, the acidity produced is consumed or otherwise ameliorated by parallel reactions. Tracking pH or [H+] in both a reactor and in soil does not accurately reflect reaction progress and may not correctly indicate the true level of risk. In comparison, the tracking of pyrite oxidation with the concentration of sulfate in solution is not affected by side reactions or precipitation and is therefore a better indicator for the rate of pyrite destruction. PMID:16839593

  3. Chemical characterization of high molecular weight dissolved organic matter in fresh and marine waters

    NASA Astrophysics Data System (ADS)

    Repeta, Daniel J.; Quan, Tracy M.; Aluwihare, Lihini I.; Accardi, AmyMarie

    2002-03-01

    The high molecular weight fraction of dissolved organic matter in a suite of lakes, rivers, seawater, and marine sediment interstitial water samples was collected by ultrafiltration and characterized by molecular level and spectroscopic techniques. Proton nuclear magnetic resonance spectra of all samples show a high degree of similarity, with major contributions from carbohydrates, bound acetate, and lipids. Molecular level analyses of neutral sugars show seven monosaccharides, rhamnose, fucose, arabinose, xylose, mannose, glucose, and galactose, to be abundant, and to occur in comparable relative amounts in each sample. Previous studies have emphasized the distinctive composition of dissolved humic substances in fresh and marine waters, and have attributed these differences to sources and transformations of organic matter unique to each environment. In contrast we find a large fraction of freshwater high molecular weight dissolved organic matter (HMWDOM; > 1kD) to be indistinguishable from marine HMWDOM in bulk and molecular-level chemical properties. Aquatic HMWDOM is similar in chemical composition to biologically derived acylated heteropolysaccharides isolated from marine algal cultures, suggesting a biological source for some fraction of persistent HMWDOM. High molecular weight DOC contributes 51 ± 26% of the total DOC, and monosaccharides 18 ± 8% of the total HMWDOC in our freshwater samples. These contributions are on average higher and more variable, but not significantly different than for surface seawater (30% and 16% respectively). Biogeochemical processes that produce, accumulate, and recycle DOM may therefore share important similarities and be broadly comparable across a range of environmental settings.

  4. Prebiotic Organic Matter from the Center of the Galaxy

    NASA Astrophysics Data System (ADS)

    Halfen, DeWayne; Ziurys, Lucy M.

    2016-06-01

    The origins of life on Earth must have begun with simple organic compounds. A plausible source of such prebiotic molecules was the interstellar medium (ISM). Of the over 160 molecules that have been identified in interstellar gas, about half have been discovered in one source, Sagittarius B2(N), located in the Galactic Center. This giant molecular cloud is also home to many large organic species observed in the ISM. How complex these species can become is unknown. In order to accurately establish an inventory of potentially, prebiotic organic molecules, we completed a continuous spectral-line survey of Sgr B2(N) at the confusion limit using the Arizona Radio Observatory facilities: the Kitt Peak 12 m and the Submillimeter Telescope. The survey covers the 1, 2, and 3 mm atmospheric windows in the range 68 - 280 GHz, and about 15,000 individual spectral lines have been observed. Seventy-four molecules have been identified in the data, including several potential prebiotic species, such as glycolaldehyde, acetamide, and methyl isocyanate. These molecules are relatively abundant in Sgr B2(N), with fractional abundances of f ~ 10-10 - 10-12 relative to H2. Current results of this survey will be presented, along with its implications for interstellar organic chemistry and prebiotic synthesis. A comparison with organics found in comets and meteorites will also be discussed.

  5. Carbon isotopic studies of organic matter in precambrian rocks.

    PubMed

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

    1972-03-17

    Reduced carbon in early Precambrian cherts of the Fig Tree and upper and middle Onverwacht groups of South Africa is isotopically similar (the average value of delta(13)C(PDB) is -28.7 per mil) to photosynthetically produced organic matter of younger geological age. Reduced carbon in lower Onverwacht cherts (Theespruit formation) is anomalously heavy (the average value of delta(13)C(PDB) is -16.5 per mil). This discontinuity may reflect a major event in biological evolution.

  6. 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.

  7. The role of fungi for carbon decomposition in soils of different structure and fresh organic matter content

    NASA Astrophysics Data System (ADS)

    Schmidt, Sonja; Chenu, Claire; Falconer, Ruth; Geradin, Cyril; Nunan, Naoise; Otten, Wilfred; Pouteau, Valerie

    2014-05-01

    Sequestration of C in soils has a major influence on climate change. Fungi play an important role in carbon decomposition and sequestration but the effect of soil structure and input of fresh organic matter (particulate organic matter POM) is still unclear. Fungi is predominant involved in cellulose decomposition and the priming effect (PE) where old SOM is decomposed by using fresh carbon as a source of energy. Information on how soil structure affects colonisation and decomposition of POM and SOM by fungi could help to get explain processes involved in carbon sequestration and CO2respiration. The objective of this study was to get a better understanding on the involvement of fungi in CO2 emissions arising from soils and to gain information on what factors in the soil are driving organic matter (OM) decomposition. Experimental data on fungal growth and carbon decomposition as affected by POM abundance and soil structure were obtained. Sterilised maize straw (1-2 mm2) and soil (

  8. Thermodynamics of uranium/organic matter interactions in hydrothermal systems

    NASA Astrophysics Data System (ADS)

    Richard, L.

    2003-04-01

    Organic matter is commonly encountered in and around uranium and other ore deposits, which raises the question of the role played by organic compounds in the formation of these deposits (Landais and Gize, 1997). One of the best known examples is the observation of uraninite crystals entrapped within solid bitumens in the Oklo natural reactors. This observation led Nagy et al. (1991) to propose that a liquid, aliphatic-rich bitumen may have acted as a reductant to precipitate uraninite from hydrothermal solutions according to the reaction VIUO2+2(aq)+H_2O(l)=IVUO2(c)+2H^+(aq)+0.5 O2(g). The liquid bitumen was simultaneously oxidized into a polyaromatic solid, which may be represented by the reaction 2.7n- C20H42(l) + 17.85 O2(g) = C54H42(c)+35.7 H_2O(l) where n-C20H42(l) denotes n-eicosane present in the liquid bitumen, and C54H42(c) represents an idealized polyaromatic solid. Recent advances in theoretical organic geochemistry made it possible to generate a comprehensive thermodynamic database for hundreds of crystalline, liquid, gas and aqueous organic compounds of geochemical interest (Shock and Helgeson, 1990; Shock, 1995; Amend and Helgeson, 1997; Helgeson et al., 1998; Richard and Helgeson, 1998; Richard, 2001), which can be used together with thermodynamic properties for uranium-bearing minerals and aqueous species (Grenthe et al., 1992; Shock et al., 1997) to characterize uranium/organic matter interactions in hydrothermal systems as a function of temperature, pressure, oxygen fugacity, and organic matter composition. Activity-fO_2 diagrams have been constructed at a series of temperatures and pressures to investigate possible genetic relationships between uranium mineralizations and solid bitumens of various compositions.

  9. Xiphinema americanum as Affected by Soil Organic Matter and Porosity.

    PubMed

    Ponchillia, P E

    1972-07-01

    The effects of four soil types, soil porosity, particle size, and organic matter were tested on survival and migration of Xiphinema americanum. Survival and migration were significantly greater in silt loam than in clay loam and silty clay soils. Nematode numbers were significantly greater in softs planted with soybeans than in fallow softs. Nematode survival was greatest at the higher of two pore space levels in four softs. Migration of X. americanum through soft particle size fractions of 75-150, 150-250, 250-500, 500-700, and 700-1,000 mu was significantly greater in the middle three fractions, with the least occurring in the smallest fraction. Additions of muck to silt loam and loamy sand soils resulted in reductions in survival and migration of the nematode. The fulvic acid fraction of muck, extracted with sodium hydroxide, had a deleterious effect on nematode activity. I conclude that soils with small amounts of air-filled pore space, extremes in pore size, or high organic matter content are deleterious to the migration and survival of X. americanum, and that a naturally occurring toxin affecting this species may be present in native soft organic matter.

  10. 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.

  11. 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.

  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. 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.

  14. 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.

  15. Contributions of organic matter and organic sulfur redox processes to electron flow in anoxic incubations of peat

    NASA Astrophysics Data System (ADS)

    YU, Zhiguo; Peiffer, Stefan; Göttlicher, Jörg; Knorr, Klaus-Holger

    2015-04-01

    Anaerobic decomposition of peat soils involves a number of interdependent microbial processes that ultimately generate CO2 and CH4. In many peat soils, a high ratio of CO2:CH4 was reported, which presumably results from a direct or indirect role of soil organic matter serving as an electron acceptor. Therefore, in this study we intended to test the hypothesis that organic matter (OM) suppresses methanogenesis and sustains anaerobic CO2 production, serving as i) direct electron acceptor or ii) via supporting internal sulfur cycling to maintains CO2 production through bacterial sulfate reduction (BSR). We incubated peat samples of commercial bog peat, inoculated with a small amount of fresh peat to introduce an active microbial community. Samples were amended with sulfate or sulfide and incubated under anoxic conditions for 6 weeks at 30 ° C. Upon anaerobic incubation of peat virtually devoid of inorganic electron acceptors, CO2 and CH4 were produced at a ratio of 3.2. According to the electron budget, the calculated electron accepting capacity (EAC) of OM was 2.36 μeq cm3 d-1. Addition of sulfate significantly increased CO2 production and effectively suppressed CH4 production. After subtracting the EAC provided though sulfate addition (0.97~2.81 μeq cm-3 d-1), EACs supplied by OM reached 3.88 to 4.85 μeq cm-3 d-1.The contribution of organic sulfur was further evaluated by XANES spectroscopy and using natural abundance of δ34S as a tracer. Results demonstrated that BSR involved both addition of H2S and sulfate to OM leading to a formation of reduced organic sulfur and partial changes of oxidized organic sulfur species. The original peat prior to incubation contained 70.5% reduced organic S (R-S-H, R-S-R, R-S-S-R), and 25.9% oxidized S (R-SO3, R-SO2-R, R-SO4-R), whereas the treatment with H2S or sulfate addition comprised 75.7~ 81.1% reduced organic S, and only 21.1~18.9 % oxidized S. Our results imply that that organic matter contributes to anaerobic respiration

  16. 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...

  17. 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.

  18. 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.

  19. 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.

  20. 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

  1. 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.

  2. Organic Nitrogen-Driven Stimulation of Arbuscular Mycorrhizal Fungal Hyphae Correlates with Abundance of Ammonia Oxidizers

    PubMed Central

    Bukovská, Petra; Gryndler, Milan; Gryndlerová, Hana; Püschel, David; Jansa, Jan

    2016-01-01

    Large fraction of mineral nutrients in natural soil environments is recycled from complex and heterogeneously distributed organic sources. These sources are explored by both roots and associated mycorrhizal fungi. However, the mechanisms behind the responses of arbuscular mycorrhizal (AM) hyphal networks to soil organic patches of different qualities remain little understood. Therefore, we conducted a multiple-choice experiment examining hyphal responses to different soil patches within the root-free zone by two AM fungal species (Rhizophagus irregularis and Claroideoglomus claroideum) associated with Medicago truncatula, a legume forming nitrogen-fixing root nodules. Hyphal colonization of the patches was assessed microscopically and by quantitative real-time PCR (qPCR) using AM taxon-specific markers, and the prokaryotic and fungal communities in the patches (pooled per organic amendment treatment) were profiled by 454-amplicon sequencing. Specific qPCR markers were then designed and used to quantify the abundance of prokaryotic taxa showing the strongest correlation with the pattern of AM hyphal proliferation in the organic patches as per the 454-sequencing. The hyphal density of both AM fungi increased due to nitrogen (N)-containing organic amendments (i.e., chitin, DNA, albumin, and clover biomass), while no responses as compared to the non-amended soil patch were recorded for cellulose, phytate, or inorganic phosphate amendments. Abundances of several prokaryotes, including Nitrosospira sp. (an ammonium oxidizer) and an unknown prokaryote with affiliation to Acanthamoeba endosymbiont, which were frequently recorded in the 454-sequencing profiles, correlated positively with the hyphal responses of R. irregularis to the soil amendments. Strong correlation between abundance of these two prokaryotes and the hyphal responses to organic soil amendments by both AM fungi was then confirmed by qPCR analyses using all individual replicate patch samples. Further

  3. Organic Nitrogen-Driven Stimulation of Arbuscular Mycorrhizal Fungal Hyphae Correlates with Abundance of Ammonia Oxidizers.

    PubMed

    Bukovská, Petra; Gryndler, Milan; Gryndlerová, Hana; Püschel, David; Jansa, Jan

    2016-01-01

    Large fraction of mineral nutrients in natural soil environments is recycled from complex and heterogeneously distributed organic sources. These sources are explored by both roots and associated mycorrhizal fungi. However, the mechanisms behind the responses of arbuscular mycorrhizal (AM) hyphal networks to soil organic patches of different qualities remain little understood. Therefore, we conducted a multiple-choice experiment examining hyphal responses to different soil patches within the root-free zone by two AM fungal species (Rhizophagus irregularis and Claroideoglomus claroideum) associated with Medicago truncatula, a legume forming nitrogen-fixing root nodules. Hyphal colonization of the patches was assessed microscopically and by quantitative real-time PCR (qPCR) using AM taxon-specific markers, and the prokaryotic and fungal communities in the patches (pooled per organic amendment treatment) were profiled by 454-amplicon sequencing. Specific qPCR markers were then designed and used to quantify the abundance of prokaryotic taxa showing the strongest correlation with the pattern of AM hyphal proliferation in the organic patches as per the 454-sequencing. The hyphal density of both AM fungi increased due to nitrogen (N)-containing organic amendments (i.e., chitin, DNA, albumin, and clover biomass), while no responses as compared to the non-amended soil patch were recorded for cellulose, phytate, or inorganic phosphate amendments. Abundances of several prokaryotes, including Nitrosospira sp. (an ammonium oxidizer) and an unknown prokaryote with affiliation to Acanthamoeba endosymbiont, which were frequently recorded in the 454-sequencing profiles, correlated positively with the hyphal responses of R. irregularis to the soil amendments. Strong correlation between abundance of these two prokaryotes and the hyphal responses to organic soil amendments by both AM fungi was then confirmed by qPCR analyses using all individual replicate patch samples. Further

  4. Chemoselective single-site Earth-abundant metal catalysts at metal-organic framework nodes.

    PubMed

    Manna, Kuntal; Ji, Pengfei; Lin, Zekai; Greene, Francis X; Urban, Ania; Thacker, Nathan C; Lin, Wenbin

    2016-01-01

    Earth-abundant metal catalysts are critically needed for sustainable chemical synthesis. Here we report a simple, cheap and effective strategy of producing novel earth-abundant metal catalysts at metal-organic framework (MOF) nodes for broad-scope organic transformations. The straightforward metalation of MOF secondary building units (SBUs) with cobalt and iron salts affords highly active and reusable single-site solid catalysts for a range of organic reactions, including chemoselective borylation, silylation and amination of benzylic C-H bonds, as well as hydrogenation and hydroboration of alkenes and ketones. Our structural, spectroscopic and kinetic studies suggest that chemoselective organic transformations occur on site-isolated, electron-deficient and coordinatively unsaturated metal centres at the SBUs via σ-bond metathesis pathways and as a result of the steric environment around the catalytic site. MOFs thus provide a novel platform for the development of highly active and affordable base metal catalysts for the sustainable synthesis of fine chemicals. PMID:27574182

  5. Chemoselective single-site Earth-abundant metal catalysts at metal–organic framework nodes

    PubMed Central

    Manna, Kuntal; Ji, Pengfei; Lin, Zekai; Greene, Francis X.; Urban, Ania; Thacker, Nathan C.; Lin, Wenbin

    2016-01-01

    Earth-abundant metal catalysts are critically needed for sustainable chemical synthesis. Here we report a simple, cheap and effective strategy of producing novel earth-abundant metal catalysts at metal–organic framework (MOF) nodes for broad-scope organic transformations. The straightforward metalation of MOF secondary building units (SBUs) with cobalt and iron salts affords highly active and reusable single-site solid catalysts for a range of organic reactions, including chemoselective borylation, silylation and amination of benzylic C–H bonds, as well as hydrogenation and hydroboration of alkenes and ketones. Our structural, spectroscopic and kinetic studies suggest that chemoselective organic transformations occur on site-isolated, electron-deficient and coordinatively unsaturated metal centres at the SBUs via σ-bond metathesis pathways and as a result of the steric environment around the catalytic site. MOFs thus provide a novel platform for the development of highly active and affordable base metal catalysts for the sustainable synthesis of fine chemicals. PMID:27574182

  6. 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.

  7. Organic matter and nutrient inputs to the Humber Estuary, England.

    PubMed

    Boyes, Suzanne; Elliott, Michael

    2006-01-01

    Estuaries are sinks for organic matter and nutrients entering both from their catchments and also from the adjacent lands and urban areas and in turn they are sources of such materials to the adjacent coast. The present paper quantifies the relative amounts of natural and anthropogenic organic matter and nutrients entering the Humber Estuary, Eastern England, including the allochthonous and autochthonous materials, those from urban and industrial sewage and from the catchment drainage of arable land. These data thus give a budget for the estuary which in turn answers questions fundamental to the management of the estuary. The estimations within the study have been carried out against a background of designating estuaries under the European Union Urban Waste-water Treatment Directive and the EU Nitrates Directive. The assessment has particularly addressed the question, related to the former Directive, of whether the Humber Estuary is eutrophic or likely to become eutrophic unless management measures are taken. Thus the paper indicates the nature and value of control measures such as treatment plant upgrading and the designation of Nitrate Vulnerable Zones. The paper includes the recent national and European discussions on the designation of areas under these Directives. Finally, the study has allowed a quantification of the present organic inputs to the estuary in comparison to those entering prior to large scale land-claim which had removed natural organic-producing wetlands.

  8. New upper limit on strange quark matter abundance in cosmic rays with the PAMELA space experiment.

    PubMed

    Adriani, O; Barbarino, G C; Bazilevskaya, G A; Bellotti, R; Boezio, M; Bogomolov, E A; Bongi, M; Bonvicini, V; Bottai, S; Bruno, A; Cafagna, F; Campana, D; Carlson, P; Casolino, M; Castellini, G; De Donato, C; De Santis, C; De Simone, N; Di Felice, V; Formato, V; Galper, A M; Karelin, A V; Koldashov, S V; Koldobskiy, S; Krutkov, S Y; Kvashnin, A N; Leonov, A; Malakhov, V; Marcelli, L; Martucci, M; Mayorov, A G; Menn, W; Mergè, M; Mikhailov, V V; Mocchiutti, E; Monaco, A; Mori, N; Munini, R; Osteria, G; Palma, F; Panico, B; Papini, P; Pearce, M; Picozza, P; Ricci, M; Ricciarini, S B; Sarkar, R; Scotti, V; Simon, M; Sparvoli, R; Spillantini, P; Stozhkov, Y I; Vacchi, A; Vannuccini, E; Vasilyev, G; Voronov, S A; Yurkin, Y T; Zampa, G; Zampa, N

    2015-09-11

    In this work we present results of a direct search for strange quark matter (SQM) in cosmic rays with the PAMELA space spectrometer. If this state of matter exists it may be present in cosmic rays as particles, called strangelets, having a high density and an anomalously high mass-to-charge (A/Z) ratio. A direct search in space is complementary to those from ground-based spectrometers. Furthermore, it has the advantage of being potentially capable of directly identifying these particles, without any assumption on their interaction model with Earth's atmosphere and the long-term stability in terrestrial and lunar rocks. In the rigidity range from 1.0 to ∼1.0×10^{3}  GV, no such particles were found in the data collected by PAMELA between 2006 and 2009. An upper limit on the strangelet flux in cosmic rays was therefore set for particles with charge 1≤Z≤8 and mass 4≤A≤1.2×10^{5}. This limit as a function of mass and as a function of magnetic rigidity allows us to constrain models of SQM production and propagation in the Galaxy. PMID:26406816

  9. New Upper Limit on Strange Quark Matter Abundance in Cosmic Rays with the PAMELA Space Experiment

    NASA Astrophysics Data System (ADS)

    Adriani, O.; Barbarino, G. C.; Bazilevskaya, G. A.; Bellotti, R.; Boezio, M.; Bogomolov, E. A.; Bongi, M.; Bonvicini, V.; Bottai, S.; Bruno, A.; Cafagna, F.; Campana, D.; Carlson, P.; Casolino, M.; Castellini, G.; de Donato, C.; de Santis, C.; de Simone, N.; di Felice, V.; Formato, V.; Galper, A. M.; Karelin, A. V.; Koldashov, S. V.; Koldobskiy, S.; Krutkov, S. Y.; Kvashnin, A. N.; Leonov, A.; Malakhov, V.; Marcelli, L.; Martucci, M.; Mayorov, A. G.; Menn, W.; Mergè, M.; Mikhailov, V. V.; Mocchiutti, E.; Monaco, A.; Mori, N.; Munini, R.; Osteria, G.; Palma, F.; Panico, B.; Papini, P.; Pearce, M.; Picozza, P.; Ricci, M.; Ricciarini, S. B.; Sarkar, R.; Scotti, V.; Simon, M.; Sparvoli, R.; Spillantini, P.; Stozhkov, Y. I.; Vacchi, A.; Vannuccini, E.; Vasilyev, G.; Voronov, S. A.; Yurkin, Y. T.; Zampa, G.; Zampa, N.; Pamela Collaboration

    2015-09-01

    In this work we present results of a direct search for strange quark matter (SQM) in cosmic rays with the PAMELA space spectrometer. If this state of matter exists it may be present in cosmic rays as particles, called strangelets, having a high density and an anomalously high mass-to-charge (A /Z ) ratio. A direct search in space is complementary to those from ground-based spectrometers. Furthermore, it has the advantage of being potentially capable of directly identifying these particles, without any assumption on their interaction model with Earth's atmosphere and the long-term stability in terrestrial and lunar rocks. In the rigidity range from 1.0 to ˜1.0 ×103 GV , no such particles were found in the data collected by PAMELA between 2006 and 2009. An upper limit on the strangelet flux in cosmic rays was therefore set for particles with charge 1 ≤Z ≤8 and mass 4 ≤A ≤1.2 ×105 . This limit as a function of mass and as a function of magnetic rigidity allows us to constrain models of SQM production and propagation in the Galaxy.

  10. New upper limit on strange quark matter abundance in cosmic rays with the PAMELA space experiment.

    PubMed

    Adriani, O; Barbarino, G C; Bazilevskaya, G A; Bellotti, R; Boezio, M; Bogomolov, E A; Bongi, M; Bonvicini, V; Bottai, S; Bruno, A; Cafagna, F; Campana, D; Carlson, P; Casolino, M; Castellini, G; De Donato, C; De Santis, C; De Simone, N; Di Felice, V; Formato, V; Galper, A M; Karelin, A V; Koldashov, S V; Koldobskiy, S; Krutkov, S Y; Kvashnin, A N; Leonov, A; Malakhov, V; Marcelli, L; Martucci, M; Mayorov, A G; Menn, W; Mergè, M; Mikhailov, V V; Mocchiutti, E; Monaco, A; Mori, N; Munini, R; Osteria, G; Palma, F; Panico, B; Papini, P; Pearce, M; Picozza, P; Ricci, M; Ricciarini, S B; Sarkar, R; Scotti, V; Simon, M; Sparvoli, R; Spillantini, P; Stozhkov, Y I; Vacchi, A; Vannuccini, E; Vasilyev, G; Voronov, S A; Yurkin, Y T; Zampa, G; Zampa, N

    2015-09-11

    In this work we present results of a direct search for strange quark matter (SQM) in cosmic rays with the PAMELA space spectrometer. If this state of matter exists it may be present in cosmic rays as particles, called strangelets, having a high density and an anomalously high mass-to-charge (A/Z) ratio. A direct search in space is complementary to those from ground-based spectrometers. Furthermore, it has the advantage of being potentially capable of directly identifying these particles, without any assumption on their interaction model with Earth's atmosphere and the long-term stability in terrestrial and lunar rocks. In the rigidity range from 1.0 to ∼1.0×10^{3}  GV, no such particles were found in the data collected by PAMELA between 2006 and 2009. An upper limit on the strangelet flux in cosmic rays was therefore set for particles with charge 1≤Z≤8 and mass 4≤A≤1.2×10^{5}. This limit as a function of mass and as a function of magnetic rigidity allows us to constrain models of SQM production and propagation in the Galaxy.

  11. 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.

  12. High-resolution NMR of hydrogen in organic solids by DNP enhanced natural abundance deuterium spectroscopy.

    PubMed

    Rossini, Aaron J; Schlagnitweit, Judith; Lesage, Anne; Emsley, Lyndon

    2015-10-01

    We demonstrate that high field (9.4 T) dynamic nuclear polarization (DNP) at cryogenic (∼100 K) sample temperatures enables the rapid acquisition of natural abundance (1)H-(2)H cross-polarization magic angle spinning (CPMAS) solid-state NMR spectra of organic solids. Spectra were obtained by impregnating substrates with a solution of the stable DNP polarizing agent TEKPol in tetrachloroethane. Tetrachloroethane is a non-solvent for the solids, and the unmodified substrates are then polarized through spin diffusion. High quality natural abundance (2)H CPMAS spectra of histidine hydrochloride monohydrate, glycylglycine and theophylline were acquired in less than 2h, providing direct access to hydrogen chemical shifts and quadrupolar couplings. The spectral resolution of the (2)H solid-state NMR spectra is comparable to that of (1)H spectra obtained with state of the art homonuclear decoupling techniques.

  13. A human interactome in three quantitative dimensions organized by stoichiometries and abundances.

    PubMed

    Hein, Marco Y; Hubner, Nina C; Poser, Ina; Cox, Jürgen; Nagaraj, Nagarjuna; Toyoda, Yusuke; Gak, Igor A; Weisswange, Ina; Mansfeld, Jörg; Buchholz, Frank; Hyman, Anthony A; Mann, Matthias

    2015-10-22

    The organization of a cell emerges from the interactions in protein networks. The interactome is critically dependent on the strengths of interactions and the cellular abundances of the connected proteins, both of which span orders of magnitude. However, these aspects have not yet been analyzed globally. Here, we have generated a library of HeLa cell lines expressing 1,125 GFP-tagged proteins under near-endogenous control, which we used as input for a next-generation interaction survey. Using quantitative proteomics, we detect specific interactions, estimate interaction stoichiometries, and measure cellular abundances of interacting proteins. These three quantitative dimensions reveal that the protein network is dominated by weak, substoichiometric interactions that play a pivotal role in defining network topology. The minority of stable complexes can be identified by their unique stoichiometry signature. This study provides a rich interaction dataset connecting thousands of proteins and introduces a framework for quantitative network analysis. PMID:26496610

  14. High-resolution NMR of hydrogen in organic solids by DNP enhanced natural abundance deuterium spectroscopy

    NASA Astrophysics Data System (ADS)

    Rossini, Aaron J.; Schlagnitweit, Judith; Lesage, Anne; Emsley, Lyndon

    2015-10-01

    We demonstrate that high field (9.4 T) dynamic nuclear polarization (DNP) at cryogenic (∼100 K) sample temperatures enables the rapid acquisition of natural abundance 1H-2H cross-polarization magic angle spinning (CPMAS) solid-state NMR spectra of organic solids. Spectra were obtained by impregnating substrates with a solution of the stable DNP polarizing agent TEKPol in tetrachloroethane. Tetrachloroethane is a non-solvent for the solids, and the unmodified substrates are then polarized through spin diffusion. High quality natural abundance 2H CPMAS spectra of histidine hydrochloride monohydrate, glycylglycine and theophylline were acquired in less than 2 h, providing direct access to hydrogen chemical shifts and quadrupolar couplings. The spectral resolution of the 2H solid-state NMR spectra is comparable to that of 1H spectra obtained with state of the art homonuclear decoupling techniques.

  15. Investigating the Bowland Shale: Preliminary Insights into Understanding the Spatial and Temporal Distribution of Organic Matter

    NASA Astrophysics Data System (ADS)

    Emmings, Joseph; Davies, Sarah; Stephenson, Michael; Vane, Chris; Leng, Melanie

    2015-04-01

    The Bowland Shale (late Mississippian, early Carboniferous) has potential for the unconventional extraction of hydrocarbons in the UK and in equivalent successions that extend across Europe to the Lublin Basin, Poland. The Bowland Shale was deposited in a marine epicontinental seaway and in a basinal setting. This study seeks to characterise the controls (sedimentological, geochemical, biological, preservation) on the spatial and temporal distribution of organic matter in the Bowland Shale within the Craven Basin (UK) and link this to resource potential. This approach can also contribute to understanding the role that these basins had as a sink for organic carbon (hence sequestered CO2) on the geological timescale. The preliminary data presented delineate variation in lithology (utilising sedimentary logging, optical and scanning electron microscopy) and organic carbon content (including TOC and stable isotope analysis) through an exposed succession of the Bowland Shale, located in the Craven Basin, Lancashire. These analyses are compared with time-equivalent borehole core sample(s) also located within the Craven Basin. The study will seek to quantify the effect of modern weathering, by comparing between outcrop and borehole samples. Where modern weathering is considered to be minimal, such analyses can be utilised as an analogue used during exploration for, and classification of, prospective hydrocarbon intervals for unconventional extraction. Future analyses will target approximately time-equivalent sections across the Craven Basin in order to delineate the variation in type, abundance and spatial distribution of organic matter in more proximal and/or distal locations.

  16. Thraustochytrids, a neglected component of organic matter decomposition and food webs in marine sediments.

    PubMed

    Bongiorni, Lucia

    2012-01-01

    Decomposition of organic matter in marine sediments is a critical step influencing oxygen and carbon fluxes. In addition to heterotrophic bacteria and fungi, osmoheterotrophic protists may contribute to this process, but the extent of their role as decomposers is still unknown. Among saprophytic protists, the thraustochytrids have been isolated from different habitats and substrates. Recently, they have been reported to be particularly abundant in marine sediments characterized by the presence of recalcitrant organic matter such as seagrass and mangrove detritus where they can reach biomass comparable to those of other protists and bacteria. In addition, their capacity to produce a wide spectrum of enzymes suggests a substantial role of thraustochytrids in sedimentary organic decomposition. Moreover, thraustochytrids may represent a food source for several benthic microorganisms and animals and may be involved in the upgrading of nutrient-poor organic detritus. This chapter presents an overview on studies of thraustochytrids in benthic ecosystems and discusses future prospectives and possible methods to quantify their role in benthic food webs.

  17. 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

  18. 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.

  19. 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.

  20. 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.

  1. Probabilisitc Geobiological Classification Using Elemental Abundance Distributions and Lossless Image Compression in Recent and Modern Organisms

    NASA Technical Reports Server (NTRS)

    Storrie-Lombardi, Michael C.; Hoover, Richard B.

    2005-01-01

    Last year we presented techniques for the detection of fossils during robotic missions to Mars using both structural and chemical signatures[Storrie-Lombardi and Hoover, 2004]. Analyses included lossless compression of photographic images to estimate the relative complexity of a putative fossil compared to the rock matrix [Corsetti and Storrie-Lombardi, 2003] and elemental abundance distributions to provide mineralogical classification of the rock matrix [Storrie-Lombardi and Fisk, 2004]. We presented a classification strategy employing two exploratory classification algorithms (Principal Component Analysis and Hierarchical Cluster Analysis) and non-linear stochastic neural network to produce a Bayesian estimate of classification accuracy. We now present an extension of our previous experiments exploring putative fossil forms morphologically resembling cyanobacteria discovered in the Orgueil meteorite. Elemental abundances (C6, N7, O8, Na11, Mg12, Ai13, Si14, P15, S16, Cl17, K19, Ca20, Fe26) obtained for both extant cyanobacteria and fossil trilobites produce signatures readily distinguishing them from meteorite targets. When compared to elemental abundance signatures for extant cyanobacteria Orgueil structures exhibit decreased abundances for C6, N7, Na11, All3, P15, Cl17, K19, Ca20 and increases in Mg12, S16, Fe26. Diatoms and silicified portions of cyanobacterial sheaths exhibiting high levels of silicon and correspondingly low levels of carbon cluster more closely with terrestrial fossils than with extant cyanobacteria. Compression indices verify that variations in random and redundant textural patterns between perceived forms and the background matrix contribute significantly to morphological visual identification. The results provide a quantitative probabilistic methodology for discriminating putatitive fossils from the surrounding rock matrix and &om extant organisms using both structural and chemical information. The techniques described appear applicable

  2. Application of organic geochemistry to detect signatures of organic matter in the Haughton impact structure

    NASA Astrophysics Data System (ADS)

    Parnell, John; Lee, Pascal; Osinski, Gordon R.; Cockell, Charles S.

    2005-12-01

    Organic geochemistry applied to samples of bedrock and surface sediment from the Haughton impact structure detects a range of signatures representing the impact event and the transfer of organic matter from the crater bedrock to its erosion products. The bedrock dolomite contains hydrocarbon-bearing fluid inclusions which were incorporated before the impact event. Comparison of biomarker data from the hydrocarbons in samples inside and outside of the crater show the thermal signature of an impact. The occurrence of hydrocarbon inclusions in hydrothermal mineral samples shows that organic matter was mobilized and migrated in the immediate aftermath of the impact. The hydrocarbon signature was then transferred from bedrock to the crater-fill lacustrine deposits and present-day sediments in the crater, including wind-blown detritus in snow/ice. Separate signatures are detected from modern microbial life in crater rock and sediment samples. Signatures in Haughton crater samples are readily detectable because they include hydrocarbons generated by the burial of organic matter. This type of organic matter is not expected in crater samples on other planets, but the Haughton data show that, using very high resolution detection of organic compounds, any signature of primitive life in the crater rocks could be transferred to surface detritus and so extend the sampling medium.

  3. 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

  4. The nature of Cu bonding to natural organic matter

    NASA Astrophysics Data System (ADS)

    Manceau, Alain; Matynia, Anthony

    2010-05-01

    Copper biogeochemistry is largely controlled by its bonding to natural organic matter (NOM) for reasons not well understood. Using XANES and EXAFS spectroscopy, along with supporting thermodynamic equilibrium calculations and structural and steric considerations, we show evidence at pH 4.5 and 5.5 for a five-membered Cu(malate) 2-like ring chelate at 100-300 ppm Cu concentration, and a six-membered Cu(malonate)) 1-2-like ring chelate at higher concentration. A "structure fingerprint" is defined for the 5.0-7.0 Å -1 EXAFS region which is indicative of the ring size and number (i.e., mono- vs. bis-chelate), and the distance and bonding of axial oxygens (O ax) perpendicular to the chelate plane formed by the four equatorial oxygens (O eq) at 1.94 Å. The stronger malate-type chelate is a C 4 dicarboxylate, and the weaker malonate-type chelate a C 3 dicarboxylate. The malate-type chelate owes its superior binding strength to an -OH for -H substitution on the α carbon, thus offering additional binding possibilities. The two new model structures are consistent with the majority of carboxyl groups being clustered and α-OH substitutions common in NOM, as shown by recent infrared and NMR studies. The high affinity of NOM for Cu(II) is explained by the abundance and geometrical fit of the two types of structures to the size of the equatorial plane of Cu(II). The weaker binding abilities of functionalized aromatic rings also is explained, as malate-type and malonate-type structures are present only on aliphatic chains. For example, salicylate is a monocarboxylate which forms an unfavorable six-membered chelate, because the OH substitution is in the β position. Similarly, phthalate is a dicarboxylate forming a highly strained seven-membered chelate. Five-membered Cu(II) chelates can be anchored by a thiol α-SH substituent instead of an alcohol α-OH, as in thio-carboxylic acids. This type of chelate is seldom present in NOM, but forms rapidly when Cu(II) is photoreduced

  5. [Transformation of soil organic matter in microarthropod community from the Northern Taiga of West Siberia].

    PubMed

    Mordkovich, V G; Berezina, O G; Liubechanskiĭ, I I; Andrievskiĭ, V S; Marchenko, I I

    2006-01-01

    Recolonization of defaunated soil by springtails as well as by gamasid and oribatid mites and the changes in organic matter content of soil were studied in the northern taiga. After a one-year exposure in gauze bags (1.7 mm mesh), the abundance of microarthropods was higher but the number of species was lower compared to the surrounding soil. Large surface and litter forms did not colonize the samples, while the number of small and/or soil forms was higher. Soil samples inaccessible for microarthropods (0.15 mm mesh) were depleted of organic carbon compared to both surrounding soil and recolonized samples. The content of humic and fulvic acids was higher in the samples inaccessible to microarthropods. Humification processes prevailed in soils in the absence of microarthropods.

  6. Uranium(IV) Complexation by Natural Organic Matter Controls Speciation in the Subsurface

    NASA Astrophysics Data System (ADS)

    Bone, S.; Dynes, J.; Fendorf, S. E.; Jones, M. E.; Bargar, J.

    2014-12-01

    Uranium contaminates groundwater at many sites throughout the United States. At the aquifer in Rifle, CO, U(IV) has been found to accumulate in natural organic matter (NOM)-rich sediments comprising buried alluvial material. We expect that NOM, which is composed of detrital plant material and microbial biomass and necromass, profoundly influences the speciation of U(IV). Specifically, we hypothesize that NOM forms stable complexes with U(IV) (i.e., "noncrystalline" U(IV)), particularly through organic phosphorus moieties associated with bacteria and exopolymeric substances (EPS). Complexation with NOM can help to explain why noncrystalline U(IV) is more abundant in the subsurface than the mineral uraninite (UO2). The abundance and relative reactivity of non-crystalline U(IV) suggests that it drives U fate and transport in the subsurface. W are examining the reduction of U(VI) and subsequent complexation of U(IV) in model NOM systems comprising homogenized, partially degraded plant material, which is analogous to the detrital plant material abundant in Rifle sediments, and its associated microbial consortia. We employ a suite of spectroscopic (X-ray absorption spectroscopies) and microscopic (scanning transmission X-ray microscopy, scanning electron microscopy, and nano-scale secondary ion mass spectrometry) tools that allow us to identify the number and types of coordinating ligands and the distribution of U with respect to NOM components, including bacterial cells, plant matter and entrained minerals. In preliminary experiments we found that 50 - 100 % of U(VI) was reduced to U(IV) within several days. Furthermore, NOM was observed to sorb both U(VI), as a carbonyl complex, and U(IV), possibly as a phosphoryl complex. Further microscopic analyses are designed to elucidate whether U(IV)-P complexes are associated with bacteria or EPS. Our research suggests a new, more complicated model for U(IV) speciation in subsurface sediments, in which complexation by NOM, as

  7. 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.

  8. 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 ...

  9. 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.

  10. 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

  11. 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

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

    PubMed

    Schroth, Andrew W; Bostick, Benjamin C; Kaste, James M; Friedland, Andrew J

    2008-05-15

    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(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 (approximately 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.

  13. 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

  14. 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.

  15. 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.

  16. 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.

  17. 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

  18. 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

  19. 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

  20. 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.

  1. Particulate organic matter sinks and sources in high Arctic fjord

    NASA Astrophysics Data System (ADS)

    Kuliński, Karol; Kędra, Monika; Legeżyńska, Joanna; Gluchowska, Marta; Zaborska, Agata

    2014-11-01

    The main aim of this paper is to present results on concentrations, fluxes and isotopic composition (δ13Corg) of particulate and sedimentary organic carbon (measures of particulate and sedimentary organic matter, respectively) in Kongsfjorden, Spitsbergen. The terrestrial particulate organic carbon (POC) input to the Kongsfjorden reached 760 · 106 ± 145 · 106 g Corg y- 1, forced mostly by the glaciers' activity. This constituted 5-10% of the bulk POC supplied to the system. Marine primary production was the main source of the remaining 90-95% of POC. Organic carbon burial rates amounted to 9 ± 1 g Corg m- 2 y- 1 in the central and 13 ± 1 g Corg m- 2 y- 1 in the outer part of the fjord. Two terrestrial POM δ13Corg end members were identified: the ancient organic matter (OM) supplied by glaciers and rivers fed by water discharged from the glaciers (from - 25.4‰ to - 25.1‰), and the fresh terrestrial POM (from - 26.7‰ to - 26.6‰). Marine OM was characterized by a wide range of δ13Corg signatures: from ≤ - 26.1‰ for the phytoplankton depleted in 13Corg to ca. - 15.8‰ for debris of marine phytobenthos. The lack of distinct marine δ13Corg end member and the resemblance of phytoplankton δ13Corg signatures to the terrestrial POM δ13Corg end member precluded the use of the two δ13Corg end member mixing model to trace the terrestrial OM in Kongsfjorden, which is also very likely to happen in other Arctic regions.

  2. Association of organic matter and ferrihydrite: adsorption versus coprecipitation

    NASA Astrophysics Data System (ADS)

    Eusterhues, K.; Rennert, T.; Knicker, H.; Totsche, K. U.

    2009-04-01

    Ferrihydrite (Fh) - even if present at low concentrations - may control the available surface area and therefore, the behaviour of nutrients and pollutants in soils. Its precipitation often takes place in the presence of dissolved organic matter (OM). This involves processes such as adsorption, but also coprecipitation, flocculation/coagulation and poisoning of crystal growth. In this study, we compare coprecipitation of organic matter and ferrihydrite with pure adsorption of OM on ferrihydrite. We therefore prepared an adsorption series and a coprecipitation series using (i) water extractable organic matter from a forest topsoil and (ii) sulfite extractable lignin from paper. Products were investigated by N2-adsorption, XRD and FTIR. In coprecipitation experiments with both types of OM we observed a strong interference of the organic molecules with crystal growth leading to smaller Fh crystals, increased lattice spacings and a lower crystallinity. The highest achieved C loadings were found at approximately 200 mg C per g Fh for the adsorption and coprecipitation of the soil extract as well as for the adsorption of lignin. Coprecipitation of lignin, in contrast, resulted in a much higher maximum loading of 360 mg C per g Fh. The FTIR spectrum of the unreacted soil extract is mainly characterized by carboxyl C and polysaccharide C, with a smaller contribution of phenolic C. Spectra of the adsorbed or coprecipitated soil extract reveal weaker bands and lowered wave numbers indicating removal from solution followed by the formation of chemical bonds between the organic species and Fh by inner-sphere surface complexes. The FTIR spectrum of the lignin material shows a strong contribution of carboxyl C, polysaccharide C, and several aromatic C species. Again, all of these C species seem to form surface complexes after reaction with Fh in adsorption and coprecipitation experiments. Interestingly, at low initial C concentrations in all experiments the sorption of carboxyl

  3. 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

  4. 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.

  5. Soil organic matter in the Moscow State University botanical garden on the Vorob'evy Hills

    NASA Astrophysics Data System (ADS)

    Rozanova, M. S.; Prokof'eva, T. V.; Lysak, L. V.; Rakhleeva, A. A.

    2016-09-01

    Humification conditions and humus status parameters in arboretum soils of the Moscow State University botanical garden on the Vorob'evy Hills have been studied. Although microbiological activity is reduced, the warm and mild climate in the city, the eutrophication of soils (due to atmospheric fallouts and dissolution of construction waste inclusions), the retention of plant waste on the soil surface, and the presence of abundant primary destructors (mesofauna) have resulted in the formation of organic matter with specific characteristics. During the 60 years that have elapsed since the arboretum establishment, soils with a high content (up to 10-14%) of humate humus (CHA/CFA > 1) characterized by a higher degree of humification than in the control soils under herbaceous vegetation have been developed in the area. Large reserves of organic carbon have been noted not only in the upper 30-cm-thick soil layer, but also in the 1-m-thick layer due to organic matter of buried and technogenic horizons.

  6. Riverine Dissolved Organic Matter Degradation Modeled Through Microbial Incubations of Vascular Plant Leachates

    NASA Astrophysics Data System (ADS)

    Harfmann, J.; Hernes, P.; Chuang, C. Y.

    2015-12-01

    Dissolved organic matter (DOM) contains as much carbon as is in the atmosphere, provides the main link between terrestrial and marine carbon reservoirs, and fuels the microbial food web. The fate and removal of DOM is a result of several complex conditions and processes, including photodegradation, sorption/desorption, dominant vascular plant sources, and microbial abundance. In order to better constrain factors affecting microbial degradation, laboratory incubations were performed using Sacramento River water for microbial inoculums and vascular plant leachates. Four vascular plant sources were chosen based on their dominance in the Sacramento River Valley: gymnosperm needles from Pinus sabiniana (foothill pine), angiosperm dicot leaves from Quercus douglassi (blue oak), angiosperm monocot mixed annual grasses, and angiosperm monocot mixed Schoenoplectus acutus (tule) and Typha spp. (cattails). Three concentrations of microbial inoculum were used for each plant material, ranging from 0.2% to 10%. Degradation was monitored as a function of time using dissolved organic carbon (DOC), UV-Vis absorbance, and fluorescent dissolved organic matter (fDOM), and was compared across vascular plant type and inoculum concentration.

  7. Chemical characterization of microbial-dominated soil organic matter in the Garwood Valley, Antarctica

    NASA Astrophysics Data System (ADS)

    Feng, Xiaojuan; Simpson, André J.; Gregorich, Edward G.; Elberling, Bo; Hopkins, David W.; Sparrow, Ashley D.; Novis, Philip M.; Greenfield, Lawrence G.; Simpson, Myrna J.

    2010-11-01

    Despite its harsh environmental conditions, terrestrial Antarctica contains a relatively large microbial biomass. Natural abundance carbon and nitrogen stable isotope signatures of organic materials in the dry valleys indicate mixed provenance of the soil organic matter (SOM) with varying proportions of contributions from lichens, mosses, lake-derived algae and cyanobacteria. Here we employed two complementary analytical techniques, biomarker measurements by gas chromatography/mass spectrometry and solution-state 1H nuclear magnetic resonance spectroscopy, to provide further information at a molecular-level about the composition and possible source of SOM in the Garwood Valley, Antarctica. The predominance of branched alkanes and short-chain lipids in the solvent extracts indicates that the primary contribution to the SOM was microbial-derived. Chemical structures in the NaOH extracts from soils were also dominated by amide, peptides, and a CH 3-dominating aliphatic region that were characteristic of microbial signatures. Furthermore, the SOM in the Garwood Valley contained compounds that were different from those in the cyanobacteria-dominated mat from a nearby lake (including monoethyl alkanes and enriched side-chain protons). This observation suggests that easily degradable carbon sources from the nearby lake did not dominate the SOM, which is consistent with a fast turnover of the mat-derived organic matter found in the valley. This study highlights the important role of native soil microbes in the carbon transformation and biogeochemistry in terrestrial Antarctica.

  8. Influence of dissolved organic carbon content on modelling natural organic matter acid-base properties.

    PubMed

    Garnier, Cédric; Mounier, Stéphane; Benaïm, Jean Yves

    2004-10-01

    Natural organic matter (NOM) behaviour towards proton is an important parameter to understand NOM fate in the environment. Moreover, it is necessary to determine NOM acid-base properties before investigating trace metals complexation by natural organic matter. This work focuses on the possibility to determine these acid-base properties by accurate and simple titrations, even at low organic matter concentrations. So, the experiments were conducted on concentrated and diluted solutions of extracted humic and fulvic acid from Laurentian River, on concentrated and diluted model solutions of well-known simple molecules (acetic and phenolic acids), and on natural samples from the Seine river (France) which are not pre-concentrated. Titration experiments were modelled by a 6 acidic-sites discrete model, except for the model solutions. The modelling software used, called PROSECE (Programme d'Optimisation et de SpEciation Chimique dans l'Environnement), has been developed in our laboratory, is based on the mass balance equilibrium resolution. The results obtained on extracted organic matter and model solutions point out a threshold value for a confident determination of the studied organic matter acid-base properties. They also show an aberrant decreasing carboxylic/phenolic ratio with increasing sample dilution. This shift is neither due to any conformational effect, since it is also observed on model solutions, nor to ionic strength variations which is controlled during all experiments. On the other hand, it could be the result of an electrode troubleshooting occurring at basic pH values, which effect is amplified at low total concentration of acidic sites. So, in our conditions, the limit for a correct modelling of NOM acid-base properties is defined as 0.04 meq of total analysed acidic sites concentration. As for the analysed natural samples, due to their high acidic sites content, it is possible to model their behaviour despite the low organic carbon concentration.

  9. Orchid bees as bio-indicators for organic coffee farms in Costa Rica: does farm size affect their abundance?

    PubMed

    Hedström, Ingemar; Denzel, Andrew; Owens, Gareth

    2006-09-01

    The potential of Euglossini bees, especially Euglossa, as biological indicators of organic vs nonorganic coffee farms was studied in Atenas and San Isidro, Alajuela, Costa Rica using 1.8-cineole as lure. Observations were made for three days at each of four farms and complemented with data from a year of observations. Orchid bees were in greater abundance in the organic farms (t-Student test). However, lower abundances suggest that an organic farm may be negatively affected by the proximity of non-organic farms, depending on its size and distance. Orchid bees may be indicators of organic coffee farms.

  10. 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.

  11. 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.

  12. 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.

  13. Ironing out the details of soil organic matter cycling: The unique role of Fe-bearing minerals in regulating organic matter transformation in soils

    NASA Astrophysics Data System (ADS)

    Heckman, K. A.; Lawrence, C. R.; Harden, J. W.; Crate, J.; Swanston, C.

    2015-12-01

    Interest in the influence of mineral chemistry on soil organic matter cycling has been steadily growing, with the role of iron specifically garnering a great deal of attention. Empirical evidence from both lab and field based studies suggest that the interactions of Fe-bearing minerals and colloidal Fe species are unique from the interactions of the soil mineral matrix as a whole and may have a disproportionate influence on soil organic matter. We present results from a suite of studies examining Fe-organic matter interactions which utilize a broad range of technical approaches and highlight the use of radiocarbon analysis in terrestrial carbon cycle studies. Data suggests that interaction of organics with Fe-bearing moieties induces consistent partitioning of organics between dissolved and surface bound organic matter pools, including significant consequences for N and P availability and biodegradability of soil organic matter. Selective dissolution techniques have revealed that Fe-humus complexes comprise a significant pool of soil organic matter which cycles on a shorter-term basis across a variety of ecosystems types, while sequential density separation combined with x-ray diffraction imply concentration and long-term preservation of N-rich organics on Fe-bearing crystalline mineral surfaces. Our results explore the unique and multifaceted roles of Fe in regulating organic matter transformation and preservation in a range of soil types.

  14. 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

  15. 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

  16. 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.

  17. 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.

  18. 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

  19. Black Carbon - Soil Organic Matter abiotic and biotic interactions

    NASA Astrophysics Data System (ADS)

    Cotrufo, Francesca; Boot, Claudia; Denef, Karolien; Foster, Erika; Haddix, Michelle; Jiang, Xinyu; Soong, Jennifer; Stewart, Catherine

    2014-05-01

    Wildfires, prescribed burns and the use of char as a soil amendment all add large quantities of black carbon to soils, with profound, yet poorly understood, effects on soil biology and chemical-physical structure. We will present results emerging from our black carbon program, which addresses questions concerning: 1) black carbon-soil organic matter interactions, 2) char decomposition and 3) impacts on microbial community structure and activities. Our understanding derives from a complementary set of post-fire black carbon field surveys and laboratory and field experiments with grass and wood char amendments, in which we used molecular (i.e., BPCA, PLFA) and isotopic (i.e., 13C and 15N labelled char) tracers. Overall, emerging results demonstrate that char additions to soil are prone to fast erosion, but a fraction remains that increases water retention and creates a better environment for the microbial community, particularly favoring gram negative bacteria. However, microbial decomposition of black carbon only slowly consumes a small fraction of it, thus char still significantly contributes to soil carbon sequestration. This is especially true in soils with little organic matter, where black carbon additions may even induce negative priming.

  20. 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.

  1. 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

  2. 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.

  3. CO2 Losses from Terrestrial Organic Matter through Photodegradation

    NASA Astrophysics Data System (ADS)

    Rutledge, S.; Campbell, D. I.; Baldocchi, D. D.; Schipper, L. A.

    2010-12-01

    Net ecosystem exchange (NEE) is the sum of CO2 uptake by plants and CO2 losses from both living plants and dead organic matter. In all but a few ecosystem scale studies on terrestrial carbon cycling, losses of CO2 from dead organic matter are assumed to be the result of microbial respiration alone. Here we provide evidence for an alternative, previously largely underestimated mechanism for ecosystem-scale CO2 emissions. The process of photodegradation, the direct breakdown of organic matter by solar radiation, was found to contribute substantially to the ecosystem scale CO2 losses at both a bare peatland in New Zealand, and a summer-dead grassland in California. Comparisons of daytime eddy covariance (EC) data with data collected at the same time using an opaque chamber and the CO2 soil gradient technique, or with night-time EC data collected during similar moisture and temperature conditions were used to quantify the direct effect of exposure of organic matter to solar radiation. At a daily scale, photodegradation contributed up to 62% and 92% of summer mid-day CO2 fluxes at the de-vegetated peatland and at the grassland during the dry season, respectively. Irradiance-induced CO2 losses were estimated to be 19% of the total annual CO2 loss at the peatland, and almost 60% of the dry season CO2 loss at the grassland. Small-scale measurements using a transparent chamber confirmed that CO2 emissions from air-dried peat and grass occurred within seconds of exposure to light when microbial activity was inhibited. Our findings imply that photodegradation could be important for many ecosystems with exposed soil organic matter, litter and/or standing dead material. Potentially affected ecosystems include sparsely vegetated arid and semi-arid ecosystems (e.g. shrublands, savannahs and other grasslands), bare burnt areas, agricultural sites after harvest or cultivation (especially if crop residues are left on the surface), deciduous forests after leaf fall, or ecosystems

  4. Effects of dissolved organic matter from a eutrophic lake on the freely dissolved concentrations of emerging organic contaminants.

    PubMed

    Xiao, Yi-Hua; Huang, Qing-Hui; Vähätalo, Anssi V; Li, Fei-Peng; Chen, Ling

    2014-08-01

    The authors studied the effects of dissolved organic matter (DOM) on the bioavailability of bisphenol A (BPA) and chloramphenicol by measuring the freely dissolved concentrations of the contaminants in solutions containing DOM that had been isolated from a mesocosm in a eutrophic lake. The abundance and aromaticity of the chromophoric DOM increased over the 25-d mesocosm experiment. The BPA freely dissolved concentration was 72.3% lower and the chloramphenicol freely dissolved concentration was 56.2% lower using DOM collected on day 25 than using DOM collected on day 1 of the mesocosm experiment. The freely dissolved concentrations negatively correlated with the ultraviolent absorption coefficient at 254 nm and positively correlated with the spectral slope of chromophoric DOM, suggesting that the bioavailability of these emerging organic contaminants depends on the characteristics of the DOM present. The DOM-water partition coefficients (log KOC ) for the emerging organic contaminants positively correlated with the aromaticity of the DOM, measured as humic acid-like fluorescent components C1 (excitation/emission=250[313]/412 nm) and C2 (excitation/emission=268[379]/456 nm). The authors conclude that the bioavailability of emerging organic contaminants in eutrophic lakes can be affected by changes in the DOM.

  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. Climate Change Impacts on Soil Organic Matter: New Insights from Molecular-Level Studies

    NASA Astrophysics Data System (ADS)

    Simpson, M. J.; Feng, X.; Simpson, A.

    2009-05-01

    Natural organic matter is ubiquitously found in the environment and plays a critical role in several biogeochemical processes such as the regulation of atmospheric CO2, agricultural sustainability, and the fate and transport of problematic organic chemicals in the environment. Organic matter preserved within the sedimentary record also holds key information about early life on earth, insights into past climates, and the presence of specific organic matter structures is often used in the search for life on other planets. Despite the importance of natural organic matter in several disciplines, the vast majority of organic matter remains "molecularly uncharacterized" (Hedges et al. 2000, Org. Geochem. 31:945-958). The lack of organic matter structural information is mostly due to the complex nature and uniqueness of organic matter but also due to the lack of sophisticated analytical strategies designed specifically for the study of organic matter structure and environmental reactivity. Organic matter is a collection of compounds from various plant, microbial, and anthropogenic sources, all at various stages of oxidation (decomposition) and represents the most naturally occurring complex mixture on earth. Organic geochemists have long used biomarker methods to study the sources, structures, and stage of organic matter oxidation however biomarker methods only extract and measure a small fraction of the total organic matter composition. Nuclear magnetic resonance (NMR), namely solid-state 13C NMR spectroscopy, has been used extensively to study organic matter structure but suffers from poor spectral resolution due to organic matter heterogeneity and strong dipolar coupling in solids. This presentation will highlight the development of molecular-level analytical methods for organic matter and demonstrate their utility in studying soil organic matter biogeochemistry with global warming. The use of biomarker methods with conventional and innovative NMR methods in tandem

  7. Mesopelagic N2 Fixation Related to Organic Matter Composition in the Solomon and Bismarck Seas (Southwest Pacific).

    PubMed

    Benavides, Mar; Moisander, Pia H; Berthelot, Hugo; Dittmar, Thorsten; Grosso, Olivier; Bonnet, Sophie

    2015-01-01

    Dinitrogen (N2) fixation was investigated together with organic matter composition in the mesopelagic zone of the Bismarck (Transect 1) and Solomon (Transect 2) Seas (Southwest Pacific). Transparent exopolymer particles (TEP) and the presence of compounds sharing molecular formulae with saturated fatty acids and sugars, as well as dissolved organic matter (DOM) compounds containing nitrogen (N) and phosphorus (P) were higher on Transect 1 than on Transect 2, while oxygen concentrations showed an opposite pattern. N2 fixation rates (up to ~1 nmol N L-1 d-1) were higher in Transect 1 than in Transect 2, and correlated positively with TEP, suggesting a dependence of diazotroph activity on organic matter. The scores of the multivariate ordination of DOM molecular formulae and their relative abundance correlated negatively with bacterial abundances and positively with N2 fixation rates, suggesting an active bacterial exploitation of DOM and its use to sustain diazotrophic activity. Sequences of the nifH gene clustered with Alpha-, Beta-, Gamma- and Deltaproteobacteria, and included representatives from Clusters I, III and IV. A third of the clone library included sequences close to the potentially anaerobic Cluster III, suggesting that N2 fixation was partially supported by presumably particle-attached diazotrophs. Quantitative polymerase chain reaction (qPCR) primer-probe sets were designed for three phylotypes and showed low abundances, with a phylotype within Cluster III at up to 103 nifH gene copies L-1. These results provide new insights into the ecology of non-cyanobacterial diazotrophs and suggest that organic matter sustains their activity in the mesopelagic ocean. PMID:26659074

  8. Mesopelagic N2 Fixation Related to Organic Matter Composition in the Solomon and Bismarck Seas (Southwest Pacific).

    PubMed

    Benavides, Mar; Moisander, Pia H; Berthelot, Hugo; Dittmar, Thorsten; Grosso, Olivier; Bonnet, Sophie

    2015-01-01

    Dinitrogen (N2) fixation was investigated together with organic matter composition in the mesopelagic zone of the Bismarck (Transect 1) and Solomon (Transect 2) Seas (Southwest Pacific). Transparent exopolymer particles (TEP) and the presence of compounds sharing molecular formulae with saturated fatty acids and sugars, as well as dissolved organic matter (DOM) compounds containing nitrogen (N) and phosphorus (P) were higher on Transect 1 than on Transect 2, while oxygen concentrations showed an opposite pattern. N2 fixation rates (up to ~1 nmol N L-1 d-1) were higher in Transect 1 than in Transect 2, and correlated positively with TEP, suggesting a dependence of diazotroph activity on organic matter. The scores of the multivariate ordination of DOM molecular formulae and their relative abundance correlated negatively with bacterial abundances and positively with N2 fixation rates, suggesting an active bacterial exploitation of DOM and its use to sustain diazotrophic activity. Sequences of the nifH gene clustered with Alpha-, Beta-, Gamma- and Deltaproteobacteria, and included representatives from Clusters I, III and IV. A third of the clone library included sequences close to the potentially anaerobic Cluster III, suggesting that N2 fixation was partially supported by presumably particle-attached diazotrophs. Quantitative polymerase chain reaction (qPCR) primer-probe sets were designed for three phylotypes and showed low abundances, with a phylotype within Cluster III at up to 103 nifH gene copies L-1. These results provide new insights into the ecology of non-cyanobacterial diazotrophs and suggest that organic matter sustains their activity in the mesopelagic ocean.

  9. Mesopelagic N2 Fixation Related to Organic Matter Composition in the Solomon and Bismarck Seas (Southwest Pacific)

    PubMed Central

    Benavides, Mar; Moisander, Pia H.; Berthelot, Hugo; Dittmar, Thorsten; Grosso, Olivier; Bonnet, Sophie

    2015-01-01

    Dinitrogen (N2) fixation was investigated together with organic matter composition in the mesopelagic zone of the Bismarck (Transect 1) and Solomon (Transect 2) Seas (Southwest Pacific). Transparent exopolymer particles (TEP) and the presence of compounds sharing molecular formulae with saturated fatty acids and sugars, as well as dissolved organic matter (DOM) compounds containing nitrogen (N) and phosphorus (P) were higher on Transect 1 than on Transect 2, while oxygen concentrations showed an opposite pattern. N2 fixation rates (up to ~1 nmol N L-1 d-1) were higher in Transect 1 than in Transect 2, and correlated positively with TEP, suggesting a dependence of diazotroph activity on organic matter. The scores of the multivariate ordination of DOM molecular formulae and their relative abundance correlated negatively with bacterial abundances and positively with N2 fixation rates, suggesting an active bacterial exploitation of DOM and its use to sustain diazotrophic activity. Sequences of the nifH gene clustered with Alpha-, Beta-, Gamma- and Deltaproteobacteria, and included representatives from Clusters I, III and IV. A third of the clone library included sequences close to the potentially anaerobic Cluster III, suggesting that N2 fixation was partially supported by presumably particle-attached diazotrophs. Quantitative polymerase chain reaction (qPCR) primer-probe sets were designed for three phylotypes and showed low abundances, with a phylotype within Cluster III at up to 103 nifH gene copies L-1. These results provide new insights into the ecology of non-cyanobacterial diazotrophs and suggest that organic matter sustains their activity in the mesopelagic ocean. PMID:26659074

  10. Characterization of dissolved organic matter for prediction of trihalomethane formation potential in surface and sub-surface waters.

    PubMed

    Awad, John; van Leeuwen, John; Chow, Christopher; Drikas, Mary; Smernik, Ronald J; Chittleborough, David J; Bestland, Erick

    2016-05-01

    Dissolved organic matter (DOM) in surface waters used for drinking purposes can vary markedly in character dependent on their sources within catchments. The character of DOM further influences the formation of disinfection by products when precursor DOM present in drinking water reacts with chlorine during disinfection. Here we report the development of models that describe the formation potential of trihalomethanes (THMFP) dependent on the character of DOM in waters from discrete catchments with specific land-use and soil textures. DOM was characterized based on UV absorbance at 254 nm, apparent molecular weight and relative abundances of protein-like and humic-like compounds. DOM character and Br concentration (up to 0.5 mg/L) were used as variables in models (R(2)>0.93) of THMFP, which ranged from 19 to 649 μg/L. Chloroform concentration (12-594 μg/L) and relative abundance (27-99%) were first modeled (R(2)>0.85) and from these, the abundances of bromodichloromethane and chlorodibromomethane estimated using power and exponential functions, respectively (R(2)>0.98). From these, the abundance of bromoform is calculated. The proposed model may be used in risk assessment of catchment factors on formation of trihalomethanes in drinking water, in context of treatment efficiency for removal of organic matter. PMID:26874432

  11. 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

  12. 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

  13. Impact of Native and Invasive Earthworm Activity on Forest Soil Organic Matter Dynamics

    NASA Astrophysics Data System (ADS)

    Top, Sara; Filley, Timothy

    2010-05-01

    Many northern North American forests are experiencing the introduction of exotic European lumbricid species earthworms with documented losses in litter layers, expansion of A-horizons, loss of the organic horizon, changes in fine root density, and shifts in microbial populations as a result. Some of these forests were previously devoid of these ecosystem engineers. We compare the soil isotope and molecular chemistry from two free air CO2 enrichment (FACE) forest experiments (aspen FACE at Rhinelander, Wisconsin and sweet gum FACE at Oak Ridge National Lab, Tennessee) that lie within the zones of earthworm invasion. These sites exhibit differences in amounts of exotic and native species as well as endogeic (predominantly mineral soil dwelling) and epigeic (litter and organic matter horizon dwelling) types. We investigated the impact of earthworm activity by tracking the relative abundance and stable carbon isotope compositions of lignin and substituted fatty acids extracted from isolated earthworms and their fecal pellets and from host soils. Additionally, 15N-labeled additions to the soil provide additional methods for tracking earthworm impacts. Indications of root vs leaf input to earthworm casts and fecal matter were derived from differences in the chemical composition of cutin, suberin, and lignin. The isotopically depleted CO2 used in FACE and the resulting isotopically depleted plant organic matter afford an excellent opportunity to assess biopolymer-specific turnover dynamics. We find that endogeic species are proportionately more responsible for fine root cycling while some epigeic species are responsible for microaggregation of foliar cutin. CSIA of fecal pellet lignin and SFA indicate how these biopolymer pools can be derived from variable sources, roots, background soil, foliar tissue within one earthworm. Additionally, CSIA indicates the distinct roles that different earthworm types have in "aging" surface soil biopolymer pools through encapsulation and

  14. Geochemical drivers of organic matter decomposition in the active layer of Arctic tundra

    NASA Astrophysics Data System (ADS)

    Herndon, E.; Roy Chowdhury, T.; Mann, B.; Graham, D. E.; Wullschleger, S. D.; Gu, B.; Liang, L.

    2014-12-01

    Arctic tundra soils store large quantities of organic carbon that are susceptible to decomposition and release to the atmosphere as CO2 and CH4. Decomposition rates are limited by cold temperatures and widespread anoxia; however, ongoing changes in soil temperature, thaw depth, and water saturation are expected to influence rates and pathways of organic matter decomposition. In order to predict greenhouse gas releases from high-latitude ecosystems, it is necessary to identify how geochemical factors (e.g. terminal electron acceptors, carbon substrates) influence CO2 and CH4 production in tundra soils. This study evaluates spatial patterns of aqueous geochemistry in the active layer of low- to high-centered polygons located at the Barrow Environmental Observatory in northern Alaska. Pore waters from saturated soils were low in sulfate and nitrate but contained abundant Fe which may serve a major terminal electron acceptor for anaerobic microbial metabolism. Relatively high concentrations of soluble Fe accumulated in the middle of the active layer near the boundary between the organic and mineral horizon, and we infer that Fe-oxide reduction and dissolution in the mineral horizon produced soluble Fe that diffused upwards and was stabilized by complexation with dissolved organic matter. Fe concentrations in the bulk soil were higher in organic than mineral horizons due to the presence of these organic-Fe complexes and Fe-oxide precipitates. Dissolved CH4 increased with increasing proportions of dissolved Fe(III) in saturated soils from transitional and low-centered polygons. The opposite trend was observed in drier soils from flat- and high-centered polygons where deeper oxidation fronts may inhibit methanogenesis. Using multiple spectroscopic and molecular methods (e.g. UV-Vis, Fourier transform infrared, ultrahigh resolution mass spectrometry), we also observed that pore waters from the middle of the active layer contained more aromatic organics than in mineral

  15. 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.

  16. Spectroscopic characterization of dissolved organic matter isolated from rainwater.

    PubMed

    Santos, Patrícia S M; Otero, Marta; Duarte, Regina M B O; Duarte, Armando C

    2009-02-01

    Rainwater is a matrix containing extremely low concentrations (in the range of muM C) of dissolved organic carbon (DOC) and for its characterization, an efficient extraction procedure is essential. A recently developed procedure based on adsorption onto XAD-8 and XAD-4 resins in series was used in this work for the extraction and isolation of rainwater dissolved organic matter (DOM). Prior to the isolation and fractionation of DOM, and to obtain sufficient mass for the spectroscopic analyses, individual rainwater samples were batched together according to similar meteorological conditions on a total of three composed samples. The results of the isolation procedure indicated that the resin tandem procedure is not applicable for rainwater DOM since the XAD-4 resin caused samples contamination. On the other hand, the XAD-8 resin allowed DOM recoveries of 39.9-50.5% of the DOC of the original combined samples. This recovered organic fraction was characterized by UV-visible, molecular fluorescence, FTIR-ATR and 1H NMR spectroscopies. The chemical characterization of the rainwater DOM showed that the three samples consist mostly of hydroxylated and carboxylic acids with a predominantly aliphatic character, containing a minor component of aromatic structures. The obtained results suggest that the DOM in rainwater, and consequently in the precursor atmospheric particles, may have a secondary origin via the oxidation of volatile organic compounds from different origins.

  17. Iron traps terrestrially derived dissolved organic matter at redox interfaces.

    PubMed

    Riedel, Thomas; Zak, Dominik; Biester, Harald; Dittmar, Thorsten

    2013-06-18

    Reactive iron and organic carbon are intimately associated in soils and sediments. However, to date, the organic compounds involved are uncharacterized on the molecular level. At redox interfaces in peatlands, where the biogeochemical cycles of iron and dissolved organic matter (DOM) are coupled, this issue can readily be studied. We found that precipitation of iron hydroxides at the oxic surface layer of two rewetted fens removed a large fraction of DOM via coagulation. On aeration of anoxic fen pore waters, >90% of dissolved iron and 27 ± 7% (mean ± SD) of dissolved organic carbon were rapidly (within 24 h) removed. Using ultra-high-resolution MS, we show that vascular plant-derived aromatic and pyrogenic compounds were preferentially retained, whereas the majority of carboxyl-rich aliphatic acids remained in solution. We propose that redox interfaces, which are ubiquitous in marine and terrestrial settings, are selective yet intermediate barriers that limit the flux of land-derived DOM to oceanic waters. PMID:23733946

  18. Hydrogen and carbon isotopes of petroleum and related organic matter

    NASA Astrophysics Data System (ADS)

    Yeh, Hsueh-Wen; Epstein, Samuel

    1981-05-01

    D/H and 13C /12C ratios were measured for 114 petroleum samples and for several samples of related organic matter. δD of crude oil ranges from -85 to -181‰, except for one distillate (-250‰) from the Kenai gas field; δ13C of crude oil ranges from -23.3 to -32.5‰, Variation in δD and δ13C values of compound-grouped fractions of a crude oil is small, 3 and 1.1%., respectively, and the difference in δD and δ13C between oil and coeval wax is slight. Gas fractions are 53-70 and 22.6-23.2‰ depleted in D and 13C, respectively, relative to the coexisting oil fractions. The δD and δ13C values of the crude oils appear to be largely determined by the isotopic compositions of their organic precursors. The contribution of terrestrial organic debris to the organic precursors of most marine crude oils may be significant.

  19. Measuring Organic Matter with COSIMA on Board Rosetta

    NASA Astrophysics Data System (ADS)

    Briois, C.; Baklouti, D.; Bardyn, A.; Cottin, H.; Engrand, C.; Fischer, H.; Fray, N.; Godard, M.; Hilchenbach, M.; von Hoerner, H.; Höfner, H.; Hornung, K.; Kissel, J.; Langevin, Y.; Le Roy, L.; Lehto, H.; Lehto, K.; Orthous-Daunay, F. R.; Revillet, C.; Rynö, J.; Schulz, R.; Silen, J. V.; Siljeström, S.; Thirkell, L.

    2014-12-01

    Comets are believed to contain the most pristine material of our Solar System materials and therefore to be a key to understand the origin of the Solar System, and the origin of life. Remote sensing observations have led to the detection of more than twenty simple organic molecules (Bockelée-Morvan et al., 2004; Mumma and Charnley, 2011). Experiments on-board in-situ exploration missions Giotto and Vega and the recent Stardust sample return missions have shown that a significant fraction of the cometary grains consists of organic matter. Spectra showed that both the gaseous (Mitchell et al., 1992) and the solid phase (grains) (Kissel and Krueger, 1987) contained organic molecules with higher masses than those of the molecules detected by remote sensing techniques in the gaseous phase. Some of the grains analyzed in the atmosphere of comet 1P/Halley seem to be essentially made of a mixture of carbon, hydrogen, oxygen and nitrogen (CHON grains, Fomenkova, 1999). Rosetta is an unparalleled opportunity to make a real breakthrough into the nature of cometary matter, both in the gas and in the solid phase. The dust mass spectrometer COSIMA on Rosetta will analyze organic and inorganic phases in the dust. The organic phases may be refractory, but some organics may evaporate with time from the dust and lead to an extended source in the coma. Over the last years, we have prepared the cometary rendezvous by the analysis of various samples with the reference model of COSIMA. We will report on this calibration data set and on the first results of the in-situ analysis of cometary grains as captured, imaged and analyzed by COSIMA. References : Bockelée-Morvan, D., et al. 2004. (Eds.), Comets II. the University of Arizona Press, Tucson, USA, pp. 391-423 ; Fomenkova, M.N., 1999. Space Science Reviews 90, 109-114 ; Kissel, J., Krueger, F.R., 1987. Nature 326, 755-760 ; Mitchell, et al. 1992. Icarus 98, 125-133 ; Mumma, M.J., Charnley, S.B., 2011. Annual Review of Astronomy and

  20. Organic matter loss from cultivated peat soils in Sweden

    NASA Astrophysics Data System (ADS)

    Berglund, Örjan; Berglund, Kerstin

    2015-04-01

    The degradation of drained peat soils in agricultural use is an underestimated source of loss of organic matter. Oxidation (biological degradation) of agricultural peat soils causes a loss of organic matter (OM) of 11 - 22 t ha-1 y-1 causing a CO2 emission of 20 - 40 t ha-1 y-1. Together with the associated N2O emissions from mineralized N this totals in the EU to about 98.5 Mton CO2 eq per year. Peat soils are very prone to climate change and it is expected that at the end of this century these values are doubled. The degradation products pollute surface waters. Wind erosion of peat soils in arable agriculture can cause losses of 3 - 30 t ha-1 y-1 peat also causing air pollution (fine organic particles). Subsidence rates are 1 - 2 cm per year which leads to deteriorating drainage effect and make peat soils below sea or inland water levels prone to flooding. Flooding agricultural peat soils is in many cases not possible without high costs, high GHG emissions and severe water pollution. Moreover sometimes cultural and historic landscapes are lost and meadow birds areas are lost. In areas where the possibility to regulate the water table is limited the mitigation options are either to increase biomass production that can be used as bioenergy to substitute some fossil fuel, try to slow down the break-down of the peat by different amendments that inhibit microbial activity, or permanent flooding. The negative effects of wind erosion can be mitigated by reducing wind speed or different ways to protect the soil by crops or fiber sheets. In a newly started project in Sweden a typical peat soil with and without amendment of foundry sand is cropped with reed canary grass, tall fescue and timothy to investigate the yield and greenhouse gas emissions from the different crops and how the sand effect the trafficability and GHG emissions.

  1. BiOMAS: Biochip for Organic Matter Analysis in Space

    NASA Astrophysics Data System (ADS)

    Dobrijevic, Michel; Incerti, Sebastien; Baque, Mickael; Le Postollec, Aurelie; Coussot, Gaelle; Moretto, Philippe; Vandenabeele Trambouze, Odile

    The search for the first steps of a prebiotic chemistry and the detection of life in the Solar System are ones of the great challenges of new upcoming space missions. In particular, some instruments will be designed to detect traces of organic matter on extra-terrestrial objects like Mars, Titan, comets, etc. A new and promising technique based on biochips is recommended by space agencies (ESA and NASA). A biochip is a miniaturized device composed of biological sensitive systems grafted on a slide. It allows the quantification of numerous target molecules simultaneously (from hundreds to thousands). With the support of the French space agency (CNES), our team currently develops a biochip especially designed for planetary exploration. The BiOMAS (Biochip for Organic Matter Analysis in Space) project, in progress for four years, has an interdisciplinary dimension bringing together specialists evolving in different area (planetology, physics, chemistry, biology and materials science) and developing complementary competences. A space biochip should be highly sensitive, specific and robust, allowing the detection of traces of various organic molecules (individuals and families). Since the conception of the biochip is at the heart of the instrumental specification, our aim is to optimize all the components (including the slide material, the ligands, the chemical bonds and the detection system) in order to meet both analytical and space constraints. Two different types of ligands (antibodies and aptamers) are under study to reach this objective. In space conditions, a lot of constraints might alter the efficiency of this analytical tool (irradiation by cosmic rays, temperature variations, vacuum, long duration mission, etc). Therefore, designing such a biochip requires testing the resistance of all its components to space conditions. Main concepts and current developments of the project are presented.

  2. Significance of Isotopically Labile Organic Hydrogen in Thermal Maturation of Organic Matter

    SciTech Connect

    Arndt Schimmelmann; Maria Mastalerz

    2010-03-30

    Isotopically labile organic hydrogen in fossil fuels occupies chemical positions that participate in isotopic exchange and in chemical reactions during thermal maturation from kerogen to bitumen, oil and gas. Carbon-bound organic hydrogen is isotopically far less exchangeable than hydrogen bound to nitrogen, oxygen, or sulfur. We explore why organic hydrogen isotope ratios express a relationship with organic nitrogen isotope ratios in kerogen at low to moderate maturity. We develop and apply new techniques to utilize organic D/H ratios in organic matter fractions and on a molecular level as tools for exploration for fossil fuels and for paleoenvironmental research. The scope of our samples includes naturally and artificially matured substrates, such as coal, shale, oil and gas.

  3. SNC Meteorites, Organic Matter and a New Look at Viking

    NASA Technical Reports Server (NTRS)

    Warmflash, David M.; Clemett, Simon J.; McKay, David S.

    2001-01-01

    Recently, evidence has begun to grow supporting the possibility that the Viking GC-MS would not have detected certain carboxylate salts that could have been present as metastable oxidation products of high molecular weight organic species. Additionally, despite the instrument's high sensitivity, the possibility had remained that very low levels of organic matter, below the instrument's detection limit, could have been present. In fact, a recent study indicates that the degradation products of several million microorganisms per gram of soil on Mars would not have been detected by the Viking GC-MS. Since the strength of the GC-MS findings was considered enough to dismiss the biology packet, particularly the LR results, any subsequent evidence suggesting that organic molecules may in fact be present on the Martian surface necessitates a re-evaluation of the Viking LR data. In addition to an advanced mass spectrometer to look for isotopic signatures of biogenic processes, future lander missions will include the ability to detect methane produced by methanogenic bacteria, as well as techniques based on biotechnology. Meanwhile, the identification of Mars samples already present on Earth in the form of the SNC meteorites has provided us with the ability to study samples of the Martian upper crust a decade or more in advance of any planned sample return missions. While contamination issues are of serious concern, the presence of indigenous organic matter in the form of polycyclic aromatic hydrocarbons has been detected in the Martian meteorites ALH84001 and Nakhla, while there is circumstantial evidence for carbonaceous material in Chassigny. The radiochronological ages of these meteorites are 4.5 Ga, 1.3 Ga, and 165 Ma respectively representing a span of time in Earth history from the earliest single-celled organisms to the present day. Given this perspective on organic material, a biological interpretation to the Viking LR results can no longer be ruled out. In the LR

  4. Spatio-temporal distribution of organic and inorganic pollutants from Lake Geneva (Switzerland) reveals strong interacting effects of sewage treatment plant and eutrophication on microbial abundance.

    PubMed

    Thevenon, Florian; Graham, Neil D; Herbez, Aline; Wildi, Walter; Poté, John

    2011-07-01

    Variation with depth and time of organic matter (carbon, nitrogen, phosphorus), inorganic pollutant (mercury), as well as bacterial abundance and activity, were investigated for the first time in sediment profiles of different parts of Lake Geneva (Switzerland) over the last decades. The highest organic contents (about 32%), mercury concentration (27 mg kg(-1)), bacterial abundance (in order of 9×10(9) cell g(-1) dry sediment), and bacterial activity (1299 Relative Light Units (RLU)) were found in the highly polluted sediments contaminated by the waste water treatment plant (WWTP) discharge, which deposited during the period of cultural eutrophication. Such data, which contrast with the other sampled sites from deeper and more remote parts of the lake, prove that the organic matter and nutrients released from the municipal WWTP have considerable effects on bacterial abundance and activities in freshwater sediments. In fact, the relatively unpolluted deepwater sites and the coastal polluted site show large synchronous increases in bacterial densities linked to the anoxic conditions in the 1970s (lake eutrophication caused by external nutrient input) that subsequently increased the nutrient loading fluxes. These results show that the microbial activities response to natural or human-induced changing limnological conditions (e.g., nutrient supply, oxygen availability, redox conditions) constitutes a threat to the security of water resources, which in turn poses concerns for the world's freshwater resources in the context of global warming and the degradation of water quality (oxygen depletion in the bottom water due to reduced deep waters mixing). Moreover, the accumulation of inorganic pollutants such as high mercury (methyl-mercury) concentration may represent a significant source of toxicity for sediment dwelling organisms.

  5. Quality of fresh organic matter affects priming of soil organic matter and substrate utilization patterns of microbes

    NASA Astrophysics Data System (ADS)

    Wang, Hui; Boutton, Thomas W.; Xu, Wenhua; Hu, Guoqing; Jiang, Ping; Bai, Edith

    2015-05-01

    Changes in biogeochemical cycles and the climate system due to human activities are expected to change the quantity and quality of plant litter inputs to soils. How changing quality of fresh organic matter (FOM) might influence the priming effect (PE) on soil organic matter (SOM) mineralization is still under debate. Here we determined the PE induced by two 13C-labeled FOMs with contrasting nutritional quality (leaf vs. stalk of Zea mays L.). Soils from two different forest types yielded consistent results: soils amended with leaf tissue switched faster from negative PE to positive PE due to greater microbial growth compared to soils amended with stalks. However, after 16 d of incubation, soils amended with stalks had a higher PE than those amended with leaf. Phospholipid fatty acid (PLFA) results suggested that microbial demand for carbon and other nutrients was one of the major determinants of the PE observed. Therefore, consideration of both microbial demands for nutrients and FOM supply simultaneously is essential to understand the underlying mechanisms of PE. Our study provided evidence that changes in FOM quality could affect microbial utilization of substrate and PE on SOM mineralization, which may exacerbate global warming problems under future climate change.

  6. Quality of fresh organic matter affects priming of soil organic matter and substrate utilization patterns of microbes.

    PubMed

    Wang, Hui; Boutton, Thomas W; Xu, Wenhua; Hu, Guoqing; Jiang, Ping; Bai, Edith

    2015-01-01

    Changes in biogeochemical cycles and the climate system due to human activities are expected to change the quantity and quality of plant litter inputs to soils. How changing quality of fresh organic matter (FOM) might influence the priming effect (PE) on soil organic matter (SOM) mineralization is still under debate. Here we determined the PE induced by two (13)C-labeled FOMs with contrasting nutritional quality (leaf vs. stalk of Zea mays L.). Soils from two different forest types yielded consistent results: soils amended with leaf tissue switched faster from negative PE to positive PE due to greater microbial growth compared to soils amended with stalks. However, after 16 d of incubation, soils amended with stalks had a higher PE than those amended with leaf. Phospholipid fatty acid (PLFA) results suggested that microbial demand for carbon and other nutrients was one of the major determinants of the PE observed. Therefore, consideration of both microbial demands for nutrients and FOM supply simultaneously is essential to understand the underlying mechanisms of PE. Our study provided evidence that changes in FOM quality could affect microbial utilization of substrate and PE on SOM mineralization, which may exacerbate global warming problems under future climate change. PMID:25960162

  7. Quality of fresh organic matter affects priming of soil organic matter and substrate utilization patterns of microbes.

    PubMed

    Wang, Hui; Boutton, Thomas W; Xu, Wenhua; Hu, Guoqing; Jiang, Ping; Bai, Edith

    2015-01-01

    Changes in biogeochemical cycles and the climate system due to human activities are expected to change the quantity and quality of plant litter inputs to soils. How changing quality of fresh organic matter (FOM) might influence the priming effect (PE) on soil organic matter (SOM) mineralization is still under debate. Here we determined the PE induced by two (13)C-labeled FOMs with contrasting nutritional quality (leaf vs. stalk of Zea mays L.). Soils from two different forest types yielded consistent results: soils amended with leaf tissue switched faster from negative PE to positive PE due to greater microbial growth compared to soils amended with stalks. However, after 16 d of incubation, soils amended with stalks had a higher PE than those amended with leaf. Phospholipid fatty acid (PLFA) results suggested that microbial demand for carbon and other nutrients was one of the major determinants of the PE observed. Therefore, consideration of both microbial demands for nutrients and FOM supply simultaneously is essential to understand the underlying mechanisms of PE. Our study provided evidence that changes in FOM quality could affect microbial utilization of substrate and PE on SOM mineralization, which may exacerbate global warming problems under future climate change.

  8. Strong pathways for incorporation of terrestrially derived organic matter into benthic communities

    NASA Astrophysics Data System (ADS)

    McLeod, Rebecca J.; Wing, Stephen R.

    2009-05-01

    In Fiordland, New Zealand, large volumes of organic matter are deposited into the marine environment from pristine forested catchments. Analyses of δ15N, δ13C and δ34S were employed to determine whether these inputs were contributing to marine food webs via assimilation by common macroinvertebrates inhabiting the inner reaches of the fjords. Terrestrially derived organic matter (TOM) had values of δ15N, δ13C and δ34S that were distinct from other carbon source pools, providing sufficient power to quantify the contribution of TOM to the benthic food web. Isotopic values among macroinvertebrates varied significantly, with consistently low values of δ15N, δ13C and δ34S for the abundant deposit feeders Echinocardium cordatum (Echinodermata) and Pectinaria australis (Annelida), indicating assimilation of TOM. High concentrations of bacterial fatty acid biomarkers in E. cordatum, and values of δ13C of these biomarkers similar to TOM (-27 to -30‰) confirmed that TOM is indirectly assimilated by these sea urchins via heterotrophic bacteria. TOM was also found to enter the infaunal food web via chemoautotrophic bacteria that live symbiotically within Solemya parkinsonii (Bivalvia). Echinocardium cordatum, Pectinaria australis and S. parkinsonii comprised up to 33.5% of the biomass of the macroinfaunal community, and thus represent strong pathways for movement of organic matter from the forested catchments into the benthic food web. This demonstration of connectivity among adjacent marine and terrestrial habitats has important implications for coastal land management, and highlights the importance of intact coastal forests to marine ecosystem function.

  9. Storage and turnover of organic matter in soil

    SciTech Connect

    Torn, M.S.; Swanston, C.W.; Castanha, C.; Trumbore, S.E.

    2008-07-15

    Historically, attention on soil organic matter (SOM) has focused on the central role that it plays in ecosystem fertility and soil properties, but in the past two decades the role of soil organic carbon in moderating atmospheric CO{sub 2} concentrations has emerged as a critical research area. This chapter will focus on the storage and turnover of natural organic matter in soil (SOM), in the context of the global carbon cycle. Organic matter in soils is the largest carbon reservoir in rapid exchange with atmospheric CO{sub 2}, and is thus important as a potential source and sink of greenhouse gases over time scales of human concern (Fischlin and Gyalistras 1997). SOM is also an important human resource under active management in agricultural and range lands worldwide. Questions driving present research on the soil C cycle include: Are soils now acting as a net source or sink of carbon to the atmosphere? What role will soils play as a natural modulator or amplifier of climatic warming? How is C stabilized and sequestered, and what are effective management techniques to foster these processes? Answering these questions will require a mechanistic understanding of how and where C is stored in soils. The quantity and composition of organic matter in soil reflect the long-term balance between plant carbon inputs and microbial decomposition, as well as other loss processes such as fire, erosion, and leaching. The processes driving soil carbon storage and turnover are complex and involve influences at molecular to global scales. Moreover, the relative importance of these processes varies according to the temporal and spatial scales being considered; a process that is important at the regional scale may not be critical at the pedon scale. At the regional scale, SOM cycling is influenced by factors such as climate and parent material, which affect plant productivity and soil development. More locally, factors such as plant tissue quality and soil mineralogy affect

  10. Genetic variability of respiratory complex abundance, organization, and activity in mouse brain

    PubMed Central

    Buck, Kari J.; Walter, Nicole A.R.; Denmark, Deaunne L.

    2013-01-01

    Mitochondrial dysfunction is implicated in the etiology and pathogenesis of numerous human disorders involving tissues with high energy demand. Murine models are widely used to elucidate genetic determinants of phenotypes relevant to human disease, with recent studies of C57BL/6J (B6), DBA/2J (D2) and B6xD2 populations implicating naturally occurring genetic variation in mitochondrial function/dysfunction. Using blue native polyacrylamide gel electrophoresis, immunoblots, and in-gel activity analyses of complexes I, II, IV and V, our studies are the first to assess abundance, organization, and catalytic activity of mitochondrial respiratory complexes and supercomplexes in mouse brain. Remarkable strain differences in supercomplex assembly and associated activity are evident, without differences in individual complexes I, II, III, or IV. Supercomplexes I1III2IV2-3 exhibit robust complex III immunoreactivity and complex I and IV activities in D2, but with little detected in B6 for I1III2IV2, and I1III2IV3 is not detected in B6. I1III2IV1 and I1III2 are abundant and catalytically active in both strains, but significantly more so in B6. Furthermore, while supercomplex III2IV1 is abundant in D2, none is detected in B6. In aggregate, these results indicate a shift toward more highly assembled supercomplexes in D2. Respiratory supercomplexes are thought to increase electron flow efficiency and individual complex stability, and to reduce electron leak and generation of reactive oxygen species. Our results provide a framework to begin assessing the role of respiratory complex suprastructure in genetic vulnerability and treatment for a wide variety of mitochondrial-related disorders. PMID:24164700

  11. Predators alter community organization of coral reef cryptofauna and reduce abundance of coral mutualists

    NASA Astrophysics Data System (ADS)

    Stier, A. C.; Leray, M.

    2014-03-01

    Coral reefs are the most diverse marine systems in the world, yet our understanding of the processes that maintain such extraordinary diversity remains limited and taxonomically biased toward the most conspicuous species. Cryptofauna that live deeply embedded within the interstitial spaces of coral reefs make up the majority of reef diversity, and many of these species provide important protective services to their coral hosts. However, we know very little about the processes governing the diversity and composition of these less conspicuous but functionally important species. Here, we experimentally quantify the role of predation in driving the community organization of small fishes and decapods that live embedded within Pocillopora eydouxi, a structurally complex, reef-building coral found widely across the Indo-Pacific. We use surveys to describe the natural distribution of predators, and then, factorially manipulate two focal predator species to quantify the independent and combined effects of predator density and identity on P. eydouxi-dwelling cryptofauna. Predators reduced abundance (34 %), species richness (20 %), and modified species composition. Rarefaction revealed that observed reductions in species richness were primarily driven by changes in abundance. Additionally, the two predator species uniquely affected the beta diversity and composition of the prey assemblage. Predators reduced the abundance and modified the composition of a number of mutualist fishes and decapods, whose benefit to the coral is known to be both diversity- and density-dependent. We predict that the density and identity of predators present within P. eydouxi may substantially alter coral performance in the face of an increased frequency and intensity of natural and anthropogenic stressors.

  12. Saltcedar (Tamarix ramosissima) invasion alters organic matter dynamics in a desert stream

    USGS Publications Warehouse

    Kennedy, T.A.; Hobbie, S.E.

    2004-01-01

    1. We investigated the impacts of saltcedar invasion on organic matter dynamics in a spring-fed stream (Jackrabbit Spring) in the Mojave Desert of southern Nevada, U.S.A., by experimentally manipulating saltcedar abundance. 2. Saltcedar heavily shaded Jackrabbit Spring and shifted the dominant organic matter inputs from autochthonous production that was available throughout the year to allochthonous saltcedar leaf litter that was strongly pulsed in the autumn. Specifically, reaches dominated by saltcedar had allochthonous litter inputs of 299 g ash free dry mass (AFDM) m-2 year-1, macrophyte production of 15 g AFDM m-2 year-1 and algal production of 400 g AFDM m-2 year-1, while reaches dominated by native riparian vegetation or where saltcedar had been experimentally removed had allochthonous litter inputs of 7-34 g AFDM m -2 year-1, macrophyte production of 118-425 g AFDM m -2 year-1 and algal production of 640-900 g AFDM m -2 year-1. 3. A leaf litter breakdown study indicated that saltcedar also altered decomposition in Jackrabbit Spring, mainly through its influence on litter quality rather than by altering the environment for decomposition. Decomposition rates for saltcedar were lower than for ash (Fraxinus velutina), the dominant native allochthonous litter type, but faster than for bulrush (Scirpus americanus), the dominant macrophyte in this system.

  13. Molecular characterization of effluent organic matter identified by ultrahigh resolution mass spectrometry.

    PubMed

    Gonsior, Michael; Zwartjes, Matthew; Cooper, William J; Song, Weihua; Ishida, Kenneth P; Tseng, Linda Y; Jeung, Matthew K; Rosso, Diego; Hertkorn, Norbert; Schmitt-Kopplin, Philippe

    2011-04-01

    Effluent dissolved organic matter (EfOM) collected from the secondary-treated wastewater of the Orange County Sanitation District (OCSD) located in Fountain Valley, California, USA was compared to natural organic matter collected from the Suwannee River (SRNOM), Florida using ultrahigh resolution electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). Furthermore, the two different treatment processes at OCSD, activated sludge and trickling filter, were separately investigated. The blend of these two effluents was further evaluated after it had passed through the microfiltration process of the Advanced Water Purification Facility (AWPF) at Orange County Water District (OCWD). EfOM contained 872 different m/z peaks that were unambiguously assigned to exact molecular formulae containing a single sulfur atom and carbon, hydrogen and oxygen atoms (CHOS formulae). In contrast, the SRNOM sample only contained 152 CHOS formulae. The trend in CHO molecular compositions was opposite with 2500 CHO formulae assigned for SRNOM but only about 1000 for EfOM. The CHOS-derived mass peaks with highest abundances in EfOM could be attributed to surfactants such as linear alkyl benzene sulfonates (LAS), their co-products dialkyl tetralin sulfonates (DATS) and their biodegraded metabolites such as sulfophenyl carboxylic acids (SPC). The differences between the treatments were found minor with greater differences between sampling dates than treatment methods used.

  14. How Reliable is the Bulk δ13C value of Soil Organic Matter in Paleovegetational Reconstruction?

    NASA Astrophysics Data System (ADS)

    Sanyal, P.; Rakshit, S.

    2015-12-01

    Carbon isotope ratios of soil/paleosol organic matter (δ13CSOM) have been used to reconstruct abundance of C3-C4 plants survived in the landscape as the δ13C value of C3 (-27‰) and C4 (-12.5 ‰) plants are distinctly different. In an attempt to reconstruct the abundance of C3 and C4 plants, δ13CSOM have been measured from three soil profiles developed on flood plain of the Gangetic plain, Mohanpur, West Bengal, India. Satellite images reveal that the investigated sediments have been deposited in an oxbow lake setting of the river Ganges. The total organic carbon content of the profile ranges from 0.9% to 0.1%. The δ13CSOM values mostly range from -19.2‰ to -22‰ except a rapid positive excursions of ~5‰ at 1.5 m depth showing enriched value (-14.2‰) in all the three profiles. Based on mass balance calculation using the δ13C values of C3 and C4 plants, the δ13CSOM in the Gangetic plain indicate presence of both C3 and C4 plants in the floodplain. However, characterization of alkanes separated from lipids extracted from the same soil organic matter reveals dominant preferences in short carbon chain (C14, C16, C18, C20) with a little preferences for higher chain (C29, C31, C33). Interestingly, n-alkanes at 1.5 m depth shows very high concentration in short chain n-alkanes. Since the lower chain n-alkane represents aquatic productivity or intense bacterial decomposition and higher chain indicates the contribution from C3-C4 plants, the data from the investigated sedimentary profile shows contribution mostly from aquatic vegetation with a little contribution from terrestrial plants. This implies that before using bulk δ13CSOM value for reconstruction of C3-C4 plants from soil/paleosol, characterization (molecular level) of soil organic matter is required

  15. Microbial response to the effect of quantity and quality soil organic matter alteration after laboratory heating

    NASA Astrophysics Data System (ADS)

    Bárcenas-Moreno, G.; Escalante, E.; Pérez-Bejarano, A.; Zavala, L. M.; Jordán, A.

    2012-04-01

    Fire-induced soil changes influence indirectly on soil microbial response, mainly due to pH increases and organic matter alterations. Partial carbon combustion can originate both, an increase in microbial activity due to dissolved organic carbon increases (Bárcenas-Moreno and Bååth, 2099, Bárcenas-Moreno et al., 2011), as well as limitation of microbial growth, either due to diminution of some fractions of organic matter (Fernández et al., 1997) or due to the formation of toxic compounds (Widden and Parkinson, 1975; Diaz-Raviña et al., 1996). The magnitude or direction of these changes is conditioned mainly by fire intensity and plant species, so forest with different vegetation could promote different quantity and quality alterations of soil organic matter after fire which leads to different soil microbial response. The objective of this work was to differentiate between the effect of reduction of carbon content and the presence of substances with inhibitory effect on soil microorganisms, inoculating microorganisms from an unaltered forest area on heated soil extract-based culture media. Soil collected from two different vegetation forest, pine (P) and oak (O) forests, with similar soil characteristics was sieved and heated at 450 °C in a muffle furnace. Heated and unheated soil was used to prepare culture media resulting in different treatments: pine unheated (PUH), pine heated at 450 °C (P450), Oak unheated (OUH) and oak heated at 450 °C (O450). To isolate inhibition of microbial proliferation and nutrient limitation, different nutritive supplements were added to the media, obtaining two levels of nutrient status for each media described above: no nutrients added (-) and nutrients added (+). Colony forming units (CFU) were enumerated as estimation of viable and cultivable microbial abundance and soil parameters characterization was also realized. Significant differences were found between CFU isolated using heated and unheated soil extract-based media

  16. Soil organic matter dynamics under different land-use in grasslands in Inner Mongolia (northern China)

    NASA Astrophysics Data System (ADS)

    Zhao, L.; Wu, W.; Xu, X.; Xu, Y.

    2014-04-01

    We examined bulk soil properties and molecular biomarker distributions in surface soils from Inner Mongolia grasslands in order to understand the responses of soil organic matter to different land-use. The total of sixteen soils were collected from severely degraded grassland by overgrazing (DG), native grassland without apparent anthropogenic disturbance (NG), groundwater-sustaining grassland (GG) and restored grassland from previous potato cropland (RG). Compared to NG, soil organic carbon content was lower by 50% in DG, but higher by six-fold in GG and one-fold in RG. The δ13C values of soil organic carbon were -24.2 ± 0.6‰ in DG, -24.9 ± 0.6‰ in NG, -25.1 ± 0.1‰ in RG and -26.2 ± 0.6‰ in GG, reflecting different degradation degrees of soil organic matter or different water use efficiencies. The soils in DG contained the lowest abundance of aliphatic lipids (n-alkanes, n-alkanols, n-alkanoic acids, ω-hydroxylalkanoic acids and α-hydroxylalkanoic acids) and lignin-phenols, suggesting selective removal of these biochemically recalcitrant biomarkers with grassland degradation by microbial respiration or wind erosion. Compared to NG, the soils in GG and RG increased ω-hydroxylalkanoic acids by 60-70%, a biomarker for suberin from roots, and increased α-hydroxylalkanoic acids by 10-20%, a biomarker for both cutin and suberin. Our results demonstrate that the groundwater supply and cultivation-restoration practices in Inner Mongolia grasslands not only enhance soil organic carbon sequestration, but also change the proportions of shoot vs. root-derived carbon in soils. This finding has important implications for global carbon cycle since root derived aliphatic carbon has a longer residence time than the aboveground tissue-derived carbon in soils.

  17. Soil organic matter dynamics under different land use in grasslands in Inner Mongolia (northern China)

    NASA Astrophysics Data System (ADS)

    Zhao, L.; Wu, W.; Xu, X.; Xu, Y.

    2014-09-01

    We examined bulk soil properties and molecular biomarker distributions in surface soils from Inner Mongolian grasslands in order to understand the responses of soil organic matter to different land use. A total of 16 soils were collected from severely degraded grassland by overgrazing (DG), native grassland without apparent anthropogenic disturbance (NG), groundwater-sustaining grassland (GG) and restored grassland from previous potato cropland (RG). Compared to NG, soil organic carbon content was lower by 50% in DG, but higher by six-fold in GG and one-fold in RG. The δ13C values of soil organic carbon were -24.2 ± 0.6‰ in DG, -24.9 ± 0.6‰ in NG, -25.1 ± 0.1‰ in RG and -26.2 ± 0.6‰ in GG, reflecting different degradation degrees of soil organic matter or different water use efficiencies. The soils in DG contained the lowest abundance of aliphatic lipids (n-alkanes, n-alkanols, n-alkanoic acids, ω-hydroxylalkanoic acids and α-hydroxyalkanoic acids) and lignin-phenols, suggesting selective removal of these biochemically recalcitrant biomarkers with grassland degradation by microbial respiration or wind erosion. Compared to NG, the soils in GG and RG increased ω-hydroxylalkanoic acids by 60-70%, a biomarker for suberin from roots, and increased α-hydroxylalkanoic acids by 10-20%, a biomarker for both cutin and suberin. Our results demonstrate that the groundwater supply and cultivation-restoration practices in Inner Mongolian grasslands not only enhance soil organic carbon sequestration, but also change the proportions of shoot- versus root-derived carbon in soils. This finding has important implications for the global carbon cycle since root-derived aliphatic carbon has a longer residence time than the aboveground tissue-derived carbon in soils.

  18. Molecular insights into the microbial formation of marine dissolved organic matter: recalcitrant or labile?

    NASA Astrophysics Data System (ADS)

    Koch, B. P.; Kattner, G.; Witt, M.; Passow, U.

    2014-02-01

    The degradation of marine dissolved organic matter (DOM) is an important control variable in the global carbon cycle and dependent on the DOM composition. For our understanding of the kinetics of organic matter cycling in the ocean, it is therefore crucial to achieve a mechanistic and molecular understanding of its transformation processes. A long-term microbial experiment was performed to follow the production of non-labile DOM by marine bacteria. Two different glucose concentrations and dissolved algal exudates were used as substrates. We monitored the bacterial abundance, concentrations of dissolved and particulate organic carbon (DOC, POC), nutrients, amino acids, and transparent exopolymer particles (TEP) for two years. Ultrahigh resolution Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR-MS) allowed the molecular characterization of extracted DOM after 70 days and after ∼2 years of incubation. Although glucose was quickly degraded, a DOC background was generated in glucose incubations. Only 20% of the organic carbon from algal exudate was degraded within the 2 years of incubation. TEP, which are released by micro-organisms, were produced during glucose degradation but decreased within less than three weeks back to half of the maximum concentration and were below detection in all treatments after 2 years. The molecular analysis demonstrated that DOM generated during glucose degradation differed appreciably from DOM produced during the degradation of the algal exudates. Our results led to several conclusions: (i) Higher substrate levels result in a higher level of non-labile DOC which is an important prerequisite for carbon sequestration in the ocean; (ii) TEP are generated by bacteria but are also degraded rapidly, thus limiting their potential contribution to carbon sequestration; (iii) The molecular signatures of DOM derived from algal exudates or glucose after 70 days of incubation differed strongly from refractory DOM. After 2 years

  19. Organic matter recycling in a shallow coastal zone (NW Mediterranean): The influence of local and global climatic forcing and organic matter lability on hydrolytic enzyme activity

    NASA Astrophysics Data System (ADS)

    Misic, Cristina; Harriague, Anabella Covazzi

    2008-12-01

    Seawater and sediment were collected on a monthly basis from a shallow (10.5 m depth) coastal site in the Ligurian Sea (NW Mediterranean) from November 1993 to December 1994 to determine the main environmental forces that influenced the biogeochemical processes and to study the relationships between the availability and lability of the organic matter (OM) and hydrolytic enzymatic activity. The current direction throughout the sampling year was influenced by the climatic conditions, which showed significant correlations with north atlantic oscillation (NAO) index values. The current generally flowed northwards in spring. This could cause significantly lower transparency values than in the summer, when an eastward current probably reduced the allochthonous input of material from the main local watercourse and contributed to turning the conditions from mesotrophic to oligotrophic. Spring and summer were separated by transitional periods more than by the canonical autumn and winter seasons. These transitions were characterised by a reduction in salinity values and by resuspension caused by water column mixing and a current flowing towards the southwest. The significant inverse correlations of the chlorophyll- a and protein concentrations, bacterial abundance and proteolysis of the bottom seawater and transparency showed the direct influence of resuspension on the organic matter dynamics. Moreover, OM trophic quality influenced the bacterial parameters and the enzymatic activities. The glycolytic β glucosidase and chitinase activities and their bacterial cell-specific hydrolytic rates were higher when substrates such as hydrolysable proteins were available, while they decreased when refractory compounds were abundant. The low leucine aminopeptidase: β glucosidase ratio values observed in the water column were presumably related to the potential ease with which microbes obtained protein-derived materials and energy, the protein hydrolysable fraction being estimated at

  20. Distribution of some organic components in two forest soils profiles with evidence of soil organic matter leaching.

    NASA Astrophysics Data System (ADS)

    Álvarez-Romero, Marta; Papa, Stefania; Lozano-García, Beatriz; Parras-Alcántara, Luis; Coppola, Elio

    2015-04-01

    Soil stores organic carbon more often than we can find in living vegetation and atmosphere together. This reservoir is not inert, but it is constantly in a dynamic phase of inputs and losses. Soil organic carbon mainly depends on land cover, environment conditions and soil properties. After soil deposition, the organic residues of different origin and nature, the Soil Organic Matter (SOM) can be seen involved in two different processes during the pedogenesis: mineralization and humification. The transport process along profile happens under certain conditions such as deposition of high organic residues amount on the top soil, high porosity of the soil caused by sand or skeleton particles, that determine a water strong infiltrating capacity, also, extreme temperatures can slow or stop the mineralization and/or humification process in one intermediate step of the degradation process releasing organic metabolites with high or medium solubility and high loads of water percolating in relation to intense rainfall. The transport process along soil profile can take many forms that can end in the formation of Bh horizons (h means accumulation of SOM in depth). The forest cover nature influence to the quantity and quality of the organic materials deposited with marked differences between coniferous and deciduous especially in relation to resistance to degradation. Two soils in the Campania region, located in Lago Laceno (Avellino - Italy) with different forest cover (Pinus sp. and Fagus sp.) and that meets the requirements of the place and pedological formation suitable for the formation and accumulation of SOM in depth (Bh horizon) were studied. The different soil C fractions were determinated and were assessed (Ciavatta C. et al. 1990; Dell'Abate M.T. et al. 2002) for each soil profile the Total Extractable Lipids (TEL). Furthermore, the lignin were considered as a major component of soil organic matter (SOM), influencing its pool-size and its turnover, due to the high

  1. Sources, Ages, and Alteration of Organic Matter in Estuaries.

    PubMed

    Canuel, Elizabeth A; Hardison, Amber K

    2016-01-01

    Understanding the processes influencing the sources and fate of organic matter (OM) in estuaries is important for quantifying the contributions of carbon from land and rivers to the global carbon budget of the coastal ocean. Estuaries are sites of high OM production and processing, and understanding biogeochemical processes within these regions is key to quantifying organic carbon (Corg) budgets at the land-ocean margin. These regions provide vital ecological services, including nutrient filtration and protection from floods and storm surge, and provide habitat and nursery areas for numerous commercially important species. Human activities have modified estuarine systems over time, resulting in changes in the production, respiration, burial, and export of Corg. Corg in estuaries is derived from aquatic, terrigenous, and anthropogenic sources, with each source exhibiting a spectrum of ages and lability. The complex source and age characteristics of Corg in estuaries complicate our ability to trace OM along the river-estuary-coastal ocean continuum. This review focuses on the application of organic biomarkers and compound-specific isotope analyses to estuarine environments and on how these tools have enhanced our ability to discern natural sources of OM, trace their incorporation into food webs, and enhance understanding of the fate of Corg within estuaries and their adjacent waters. PMID:26407145

  2. Sources, Ages, and Alteration of Organic Matter in Estuaries.

    PubMed

    Canuel, Elizabeth A; Hardison, Amber K

    2016-01-01

    Understanding the processes influencing the sources and fate of organic matter (OM) in estuaries is important for quantifying the contributions of carbon from land and rivers to the global carbon budget of the coastal ocean. Estuaries are sites of high OM production and processing, and understanding biogeochemical processes within these regions is key to quantifying organic carbon (Corg) budgets at the land-ocean margin. These regions provide vital ecological services, including nutrient filtration and protection from floods and storm surge, and provide habitat and nursery areas for numerous commercially important species. Human activities have modified estuarine systems over time, resulting in changes in the production, respiration, burial, and export of Corg. Corg in estuaries is derived from aquatic, terrigenous, and anthropogenic sources, with each source exhibiting a spectrum of ages and lability. The complex source and age characteristics of Corg in estuaries complicate our ability to trace OM along the river-estuary-coastal ocean continuum. This review focuses on the application of organic biomarkers and compound-specific isotope analyses to estuarine environments and on how these tools have enhanced our ability to discern natural sources of OM, trace their incorporation into food webs, and enhance understanding of the fate of Corg within estuaries and their adjacent waters.

  3. Sources, Ages, and Alteration of Organic Matter in Estuaries

    NASA Astrophysics Data System (ADS)

    Canuel, Elizabeth A.; Hardison, Amber K.

    2016-01-01

    Understanding the processes influencing the sources and fate of organic matter (OM) in estuaries is important for quantifying the contributions of carbon from land and rivers to the global carbon budget of the coastal ocean. Estuaries are sites of high OM production and processing, and understanding biogeochemical processes within these regions is key to quantifying organic carbon (Corg) budgets at the land-ocean margin. These regions provide vital ecological services, including nutrient filtration and protection from floods and storm surge, and provide habitat and nursery areas for numerous commercially important species. Human activities have modified estuarine systems over time, resulting in changes in the production, respiration, burial, and export of Corg. Corg in estuaries is derived from aquatic, terrigenous, and anthropogenic sources, with each source exhibiting a spectrum of ages and lability. The complex source and age characteristics of Corg in estuaries complicate our ability to trace OM along the river-estuary-coastal ocean continuum. This review focuses on the application of organic biomarkers and compound-specific isotope analyses to estuarine environments and on how these tools have enhanced our ability to discern natural sources of OM, trace their incorporation into food webs, and enhance understanding of the fate of Corg within estuaries and their adjacent waters.

  4. Organic-matter retention and macroinvertebrate utilization of seasonally inundated bryophytes in a mid-order Piedmont River

    USGS Publications Warehouse

    Wood, James; Pattillo, Meryom; Freeman, Mary C.

    2016-01-01

    There is increased understanding of the role of bryophytes in supporting invertebrate biomass and for their influence on nutrient cycling and carbon balance in aquatic systems, but the structural and functional role of bryophytes growing in seasonally inundated habitats is substantially less studied. We conducted a study on the Middle Oconee River, near Athens, GA, to assess invertebrate abundance and organic-matter retention in seasonally inundated patches of the liverwort Porella pinnata, a species that tends to be submerged only when water levels in rivers are substantially above base flow. Aquatic invertebrate utilization of these seasonally inundated habitats has rarely been investigated. Macroinvertebrate biomass, insect density, and organic-matter content were significantly greater in patches of P. pinnata than on adjacent bare rock. Bryophyte biomass explained additional variation in organic matter, insect biomass, and density. The most abundant insects in P. pinnata patches were Dipterans and Plecopterans. Our results suggest an important structural role of seasonally inundated bryophyte habitats in riverine ecosystems.

  5. Targeted Access to the Genomes of Low Abundance Organisms in Complex Microbial Communities

    SciTech Connect

    Podar, Mircea; Abulencia, Carl; Walcher, Marion; Hutchinson, Don; Zengler, Karsten; Garcia, Joseph; Holland, Trevin; Cotton, Dave; Hauser, Loren John; Keller, Martin

    2007-01-01

    Current metagenomic approaches to the study of complex microbial consortia provide a glimpse into the community metabolism, and occasionally allow genomic assemblies for the most abundant organisms. However, little information is gained for the members of the community present at low frequency, especially those representing yet uncultured taxa-which includes the bulk of the diversity present in most environments. Here we used phylogenetically directed cell separation by fluorescence in situ hybridization and flow cytometry, followed by amplification and sequencing of a fraction of the genomic DNA of several bacterial cells that belong to the TM7 phylum. Partial genomic assembly allowed, for the first time, a look into the evolution and potential metabolism of a soil representative from this group of organisms for which there are no species in stable laboratory cultures. Genomic reconstruction from targeted cells of uncultured organisms directly isolated from the environment represents a powerful approach to access any specific members of a community and an alternative way to assess the community metabolic potential.

  6. Impact of natural organic matter (NOM) on freshwater amphipods.

    PubMed

    Timofeyev, Maxim A; Wiegand, Claudia; Kent Burnison, B; Shatilina, Zhanna M; Pflugmacher, Stephan; Steinberg, Christian E W

    2004-02-01

    Natural organic matter (NOM) isolated from the eutrophic Sanctuary Pond (Point Pelee National Park, Canada) has an adverse impact on amphipod species (Gammarus tigrinus and Chaetogammarus ischnus from Lake Müggelsee, Germany, and Eulimnogammarus cyaneus, from Lake Baikal, Russia). Increases in amphipod mortality, changes in peroxidase activity and increases of heat shock protein (hsp70) expression were observed upon exposure to NOM. The highest resistance to the adverse impact of NOM was observed with the endemic Baikalian amphipod E. cyaneus. However, the mechanisms behind this finding remains obscure. If differences in the sensitivity of the hsp70 antibody may be excluded, different modes of action may be postulated: because the adverse impact of NOM may be caused by reactive oxygen species (ROS) and the NOM itself, the observed differences may be due to the action of ROS alone (with E. cyaneus) and a combination of both adverse modes of action (European species). PMID:14967505

  7. Modeling of natural organic matter transport processes in groundwater.

    PubMed Central

    Yeh, T C; Mas-Pla, J; McCarthy, J F; Williams, T M

    1995-01-01

    A forced-gradient tracer test was conducted at the Georgetown site to study the transport of natural organic matter (NOM) in groundwater. In particular, the goal of this experiment was to investigate the interactions between NOM and the aquifer matrix. A detailed three-dimensional characterization of the hydrologic conductivity heterogeneity of the site was obtained using slug tests. The transport of a conservative tracer (chloride) was successfully reproduced using these conductivity data. Despite the good simulation of the flow field, NOM breakthrough curves could not be reproduced using a two-site sorption model with spatially constant parameters. Preliminary results suggest that different mechanisms for the adsorption/desorption processes, as well as their spatial variability, may significantly affect the transport and fate of NOM. PMID:7621798

  8. [Dissolved organic matter (DOM) dynamics in karst aquifer systems].

    PubMed

    Yao, Xin; Zou, Sheng-Zhang; Xia, Ri-Yuan; Xu, Dan-Dan; Yao, Min

    2014-05-01

    Dissolved organic matter (DOM) and nutrients have a unique way of producing, decomposing and storing in southwest karst water systems. To understand the biogeochemical cycle of DOM in karst aquifer systems, we investigated the behavioral changes of DOM fluorescence components in Zhaidi karst river system. Two humic-like components (C1 and C2), and one autochthonous tyrosine-like component (C4) were identified using the parallel factor analysis (PARAFAC) model. Compared with the traditional physical and chemical indicators, spatial heterogeneity of DOM was more obvious, which can reflect the subtle changes in groundwater system. Traditional indicators mainly reflect the regional characteristics of karst river system, while DOM fluorescence components reflect the attribute gaps of sampling types.

  9. Systematic approaches to comprehensive analyses of natural organic matter

    USGS Publications Warehouse

    Leenheer, Jerry A.

    2009-01-01

    The more that is learned of the chemistry of aquatic natural organic matter (NOM) the greater is the scientific appreciation of the vast complexity of this subject. This complexity is due not only to a multiplicity of precursor molecules in any environment but to their associations with each other and with other components of local environments such as clays, mineral acids and dissolved metals. In addition, this complex system is subject to constant change owing to environmental variables and microbial action. Thus, there is a good argument that no two NOM samples are exactly the same even from the same source at nearly the same time. When ubiquity of occurrence, reaction with water treatment chemicals, and subsequent human exposure are added to the list of NOM issues, one can understand the appeal that this subject holds for a wide variety of environmental scientists.

  10. New monoaromatic steroids in organic matter of the apocatagenesis zone

    NASA Astrophysics Data System (ADS)

    Kashirtsev, V. A.; Fomin, A. N.; Shevchenko, N. P.; Dolzhenko, K. V.

    2016-08-01

    According to the materials of geochemical study in the core of the ultradeep hole SV-27 of aromatic fractions of bitumoids of the Vilyui syneclise (East Siberia) by the method of chromatography-mass spectrometry, starting from the depth of >5000 m, four diastereomers of previously unknown hydrocarbons, which become predominant in the fraction at a depth of ˜6500 m, were distinguished. Similar hydrocarbons were found in organic matter of Upper Paleozoic rocks of the Kharaulakh anticlinorium in the Verkhoyansk folded area. According to the intense molecular ion m/z 366 and the character of the basic fragmental ions (m/z 238, 309, and 323), the major structure of the compounds studied was determined as 17-desmethyl-23-methylmonoaromatic steroid C27. The absence of such steroids in oil of the Vilyui syneclise shows that deep micro-oils did not participate in the formation of oil fringes of gas condensate deposits of the region.

  11. A search for presolar organic matter in meteorite

    NASA Technical Reports Server (NTRS)

    Yang, J.; Epstein, S.

    1985-01-01

    The D/H ratios and the C-13/C-12 ratios of acid-insoluble organic matter of 4 meteorites, Ochansk (H4), Plainview (H5), Gladstone (H6) and Odessa (IA), were measured. delta-D values for hydrogen extracted by stepwise combustion were negative, down to -280 deg/infinity. delta-C-13 values were also negative except in the case of the carbon coming off at the highest temperature steps for Plainview and Odessa meteorites. The concentrations of C-13-rich carbon were 3-5 orders of magnitude smaller than those found in Murchison meteorite, suggesting that relic grains of stellar condensates were mostly destroyed in the meteorites examined.

  12. Grown organic matter as a fuel raw material resource

    NASA Technical Reports Server (NTRS)

    Roller, W. L.; Keener, H. M.; Kline, R. D.; Mederski, H. J.; Curry, R. B.

    1975-01-01

    An extensive search was made on biomass production from the standpoint of climatic zones, water, nutrients, costs and energy requirements for many species. No exotic species were uncovered that gave hope for a bonanza of biomass production under culture, location, and management markedly different from those of existing agricultural concepts. A simulation analysis of biomass production was carried out for six species using conventional production methods, including their production costs and energy requirements. These estimates were compared with data on food, fiber, and feed production. The alternative possibility of using residues from food, feed, or lumber was evaluated. It was concluded that great doubt must be cast on the feasibility of producing grown organic matter for fuel, in competition with food, feed, or fiber. The feasibility of collecting residues may be nearer, but the competition for the residues for return to the soil or cellulosic production is formidable.

  13. Ecophysiology of uncultivated marine euryarchaea is linked to particulate organic matter

    PubMed Central

    Orsi, William D; Smith, Jason M; Wilcox, Heather M; Swalwell, Jarred E; Carini, Paul; Worden, Alexandra Z; Santoro, Alyson E

    2015-01-01

    Particles in aquatic environments host distinct communities of microbes, yet the evolution of particle-specialized taxa and the extent to which specialized microbial metabolism is associated with particles is largely unexplored. Here, we investigate the hypothesis that a widely distributed and uncultivated microbial group—the marine group II euryarchaea (MGII)—interacts with living and detrital particulate organic matter (POM) in the euphotic zone of the central California Current System. Using fluorescent in situ hybridization, we verified the association of euryarchaea with POM. We further quantified the abundance and distribution of MGII 16 S ribosomal RNA genes in size-fractionated seawater samples and compared MGII functional capacity in metagenomes from the same fractions. The abundance of MGII in free-living and >3 μm fractions decreased with increasing distance from the coast, whereas MGII abundance in the 0.8–3 μm fraction remained constant. At several offshore sites, MGII abundance was highest in particle fractions, indicating that particle-attached MGII can outnumber free-living MGII under oligotrophic conditions. Compared with free-living MGII, the genome content of MGII in particle-associated fractions exhibits an increased capacity for surface adhesion, transcriptional regulation and catabolism of high molecular weight substrates. Moreover, MGII populations in POM fractions are phylogenetically distinct from and more diverse than free-living MGII. Eukaryotic phytoplankton additions stimulated MGII growth in bottle incubations, providing the first MGII net growth rate measurements. These ranged from 0.47 to 0.54 d−1. However, MGII were not recovered in whole-genome amplifications of flow-sorted picoeukaryotic phytoplankton and heterotrophic nanoflagellates, suggesting that MGII in particle fractions are not physically attached to living POM. Collectively, our results support a linkage between MGII ecophysiology and POM, implying that

  14. Lack of enhanced preservation of organic matter in sediments under the oxygen minimum on the Oman Margin

    SciTech Connect

    Pedersen, T.F. ); Shimmield, G.B.; Price, N.B. )

    1992-01-01

    The impingement of oxygen minima on continental margins is widely thought to promote the accumulation of sedimentary facies enriched in well-preserved organic matter. It is shown here, however, that such a relationship does not clearly apply to the productive Oman Margin in the Arabian Sea, which hosts one of the most severe oxygen minima in the oceans. Measurements made on the 0-1 cm depth interval from fourteen box cores collected from the outer shelf-upper continental slope area off Oman show that (1) deposited organic matter is overwhelmingly of marine origin, (2) there is no significant correlation between the abundance of sedimentary organic carbon (C{sub org}) and the bottom-water O{sub 2} concentration, (3) there is no relation between the sedimentary C{sub org}:N ratio and bottom-water O{sub 2}, and (4) there is no correlation between the hydrogen index (HI) of the organic matter and bottom water oxygen. There are, however, significant correlations between the C{sub org}:N ratio and the I:C{sub org}, Cr:Al, and Zr:Al ratios, as well as between the C{sub org}:N ratio and the hydrogen index. Overall, these data suggest that the bottom water oxygen concentration has little effect in governing either the distribution of the degree of preservation of organic matter on this margin. Thus, the generally high but spatially variable C{sub org} content of the sediments on the Oman Margin may not reflect the occurrence of an oxygen minimum but instead be the result of a high settling flux of organic matter, supported by monsoon-driven upwelling, and post-depositional redistribution of the organic material by hydrodynamic influences.

  15. Priming-induced Changes in Permafrost Soil Organic Matter Decomposition

    NASA Astrophysics Data System (ADS)

    Pegoraro, E.; Schuur, E.; Bracho, R. G.

    2015-12-01

    Warming of tundra ecosystems due to climate change is predicted to thaw permafrost and increase plant biomass and litter input to soil. Additional input of easily decomposable carbon can alter microbial activity by providing a much needed energy source, thereby accelerating soil organic matter decomposition. This phenomenon, known as the priming effect, can increase CO2 flux from soil to the atmosphere. However, the extent to which this mechanism can decrease soil carbon stocks in the Arctic is unknown. This project assessed priming effects on permafrost soil collected from a moist acidic tundra site in Healy, Alaska. We hypothesized that priming would increase microbial activity by providing microbes with a fresh source of carbon, thereby increasing decomposition of old and slowly decomposing carbon. Soil from surface and deep layers were amended with multiple pulses of uniformly 13C labeled glucose and cellulose, and samples were incubated at 15° C to quantify whether labile substrate addition increased carbon mineralization. We quantified the proportion of old carbon mineralization by measuring 14CO2. Data shows that substrate addition resulted in higher respiration rates in amended soils; however, priming was only observed in deep layers, where 30% more soil-derived carbon was respired compared to control samples. This suggests that microbes in deep layers are limited in energy, and the addition of labile carbon increases native soil organic matter decomposition, especially in soil with greater fractions of slowly decomposing carbon. Priming in permafrost could exacerbate the effects of climate change by increasing mineralization rates of carbon accumulated over the long-term in deep layers. Therefore, quantifying priming effect in permafrost soils is imperative to understanding the dynamics of carbon turnover in a warmer world.

  16. Molecular characterization of dissolved organic matter (DOM): a critical review.

    PubMed

    Nebbioso, Antonio; Piccolo, Alessandro

    2013-01-01

    Advances in water chemistry in the last decade have improved our knowledge about the genesis, composition, and structure of dissolved organic matter, and its effect on the environment. Improvements in analytical technology, for example Fourier-transform ion cyclotron (FT-ICR) mass spectrometry (MS), homo and hetero-correlated multidimensional nuclear magnetic resonance (NMR) spectroscopy, and excitation emission matrix fluorimetry (EEMF) with parallel factor (PARAFAC) analysis for UV-fluorescence spectroscopy have resulted in these advances. Improved purification methods, for example ultrafiltration and reverse osmosis, have enabled facile desalting and concentration of freshly collected DOM samples, thereby complementing the analytical process. Although its molecular weight (MW) remains undefined, DOM is described as a complex mixture of low-MW substances and larger-MW biomolecules, for example proteins, polysaccharides, and exocellular macromolecules. There is a general consensus that marine DOM originates from terrestrial and marine sources. A combination of diagenetic and microbial processes contributes to its origin, resulting in refractory organic matter which acts as carbon sink in the ocean. Ocean DOM is derived partially from humified products of plants decay dissolved in fresh water and transported to the ocean, and partially from proteinaceous and polysaccharide material from phytoplankton metabolism, which undergoes in-situ microbial processes, becoming refractory. Some of the DOM interacts with radiation and is, therefore, defined as chromophoric DOM (CDOM). CDOM is classified as terrestrial, marine, anthropogenic, or mixed, depending on its origin. Terrestrial CDOM reaches the oceans via estuaries, whereas autochthonous CDOM is formed in sea water by microbial activity; anthropogenic CDOM is a result of human activity. CDOM also affects the quality of water, by shielding it from solar radiation, and constitutes a carbon sink pool. Evidence in support

  17. Effects of warming on stream biofilm organic matter use capabilities.

    PubMed

    Ylla, Irene; Canhoto, Cristina; Romaní, Anna M

    2014-07-01

    The understanding of ecosystem responses to changing environmental conditions is becoming increasingly relevant in the context of global warming. Microbial biofilm communities in streams play a key role in organic matter cycling which might be modulated by shifts in flowing water temperature. In this study, we performed an experiment at the Candal stream (Portugal) longitudinally divided into two reaches: a control half and an experimental half where water temperature was 3 °C above that of the basal stream water. Biofilm colonization was monitored during 42 days in the two stream halves. Changes in biofilm function (extracellular enzyme activities and carbon substrate utilization profiles) as well as chlorophyll a and prokaryote densities were analyzed. The biofilm in the experimental half showed a higher capacity to decompose cellulose, hemicellulose, lignin, and peptidic compounds. Total leucine-aminopeptidase, cellobiohydrolase and β-xylosidase showed a respective 93, 66, and 61% increase in activity over the control; much higher than would be predicted by only the direct temperature physical effect. In contrast, phosphatase and lipase activity showed the lowest sensitivity to temperature. The biofilms from the experimental half also showed a distinct functional fingerprint and higher carbon usage diversity and richness, especially due to a wider use of polymers and carbohydrates. The changes in the biofilm functional capabilities might be indirectly affected by the higher prokaryote and chlorophyll density measured in the biofilm of the experimental half. The present study provides evidence that a realistic stream temperature increase by 3 °C changes the biofilm metabolism to a greater decomposition of polymeric complex compounds and peptides but lower decomposition of lipids. This might affect stream organic matter cycling and the transfer of carbon to higher trophic levels.

  18. Ocean warming-acidification synergism undermines dissolved organic matter assembly.

    PubMed

    Chen, Chi-Shuo; Anaya, Jesse M; Chen, Eric Y-T; Farr, Erik; Chin, Wei-Chun

    2015-01-01

    Understanding the influence of synergisms on natural processes is a critical step toward determining the full-extent of anthropogenic stressors. As carbon emissions continue unabated, two major stressors--warming and acidification--threaten marine systems on several scales. Here, we report that a moderate temperature increase (from 30°C to 32°C) is sufficient to slow--even hinder--the ability of dissolved organic matter, a major carbon pool, to self-assemble to form marine microgels, which contribute to the particulate organic matter pool. Moreover, acidification lowers the temperature threshold at which we observe our results. These findings carry implications for the marine carbon cycle, as self-assembled marine microgels generate an estimated global seawater budget of ~1016 g C. We used laser scattering spectroscopy to test the influence of temperature and pH on spontaneous marine gel assembly. The results of independent experiments revealed that at a particular point, both pH and temperature block microgel formation (32°C, pH 8.2), and disperse existing gels (35°C). We then tested the hypothesis that temperature and pH have a synergistic influence on marine gel dispersion. We found that the dispersion temperature decreases concurrently with pH: from 32°C at pH 8.2, to 28°C at pH 7.5. If our laboratory observations can be extrapolated to complex marine environments, our results suggest that a warming-acidification synergism can decrease carbon and nutrient fluxes, disturbing marine trophic and trace element cycles, at rates faster than projected.

  19. Ocean warming-acidification synergism undermines dissolved organic matter assembly.

    PubMed

    Chen, Chi-Shuo; Anaya, Jesse M; Chen, Eric Y-T; Farr, Erik; Chin, Wei-Chun

    2015-01-01

    Understanding the influence of synergisms on natural processes is a critical step toward determining the full-extent of anthropogenic stressors. As carbon emissions continue unabated, two major stressors--warming and acidification--threaten marine systems on several scales. Here, we report that a moderate temperature increase (from 30°C to 32°C) is sufficient to slow--even hinder--the ability of dissolved organic matter, a major carbon pool, to self-assemble to form marine microgels, which contribute to the particulate organic matter pool. Moreover, acidification lowers the temperature threshold at which we observe our results. These findings carry implications for the marine carbon cycle, as self-assembled marine microgels generate an estimated global seawater budget of ~1016 g C. We used laser scattering spectroscopy to test the influence of temperature and pH on spontaneous marine gel assembly. The results of independent experiments revealed that at a particular point, both pH and temperature block microgel formation (32°C, pH 8.2), and disperse existing gels (35°C). We then tested the hypothesis that temperature and pH have a synergistic influence on marine gel dispersion. We found that the dispersion temperature decreases concurrently with pH: from 32°C at pH 8.2, to 28°C at pH 7.5. If our laboratory observations can be extrapolated to complex marine environments, our results suggest that a warming-acidification synergism can decrease carbon and nutrient fluxes, disturbing marine trophic and trace element cycles, at rates faster than projected. PMID:25714090

  20. Relating hygroscopicity and composition of organic aerosol particulate matter

    SciTech Connect

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

    2011-01-01

    A hygroscopicity tandem differential mobility analyzer (HTDMA) was used to measure the water uptake (hygroscopicity) of secondary organic aerosol (SOA) formed during the chemical and photochemical oxidation of several organic precursors in a smog chamber. Electron ionization mass spectra of the non-refractory submicron aerosol were simultaneously determined with an aerosol mass spectrometer (AMS), and correlations between the two different signals were investigated. SOA hygroscopicity was found to strongly correlate with the relative abundance of the ion signal m/z 44 expressed as a fraction of total organic signal (f44). m/z 44 is due mostly to the ion fragment CO2+ for all types of SOA systems studied, and has been previously shown to strongly correlate with organic O/C for ambient and chamber OA. The analysis was also performed on ambient OA from two field experiments at the remote site Jungfraujoch, and the megacity Mexico City, where similar results were found. A simple empirical linear relation between the hygroscopicity of OA at subsaturated RH, as given by the hygroscopic growth factor (GF) or "κorg" parameter, and f44 was determined and is given by κorg = 2.2 × f44 - 0.13. This approximation can be further verified and refined as the database for AMS and HTDMA measurements is constantly being expanded around the world. Finally, the use of this approximation could introduce an important simplification in the parameterization of hygroscopicity of OA in atmospheric models, since f44 is correlated with the photochemical age of an air mass.

  1. Response of Dissolved Organic Matter to Warming and Nitrogen Addition

    NASA Astrophysics Data System (ADS)

    Choi, J. H.; Nguyen, H.

    2014-12-01

    Dissolved Organic Matter (DOM) is a ubiquitous mixture of soluble organic components. Since DOM is produced from the terrestrial leachate of various soil types, soil may influence the chemistry and biology of freshwater through the input of leachate and run-off. The increased temperature by climate change could dramatically change the DOM characteristics of soils through enhanced decomposition rate and losses of carbon from soil organic matter. In addition, the increase in the N-deposition affects DOM leaching from soils by changing the carbon cycling and decomposition rate of soil decay. In this study, we conducted growth chamber experiments using two types of soil (wetland and forest) under the conditions of temperature increase and N-deposition in order to investigate how warming and nitrogen addition influence the characteristics of the DOM leaching from different soil types. This leachate controls the quantity and quality of DOM in surface water systems. After 10 months of incubation, the dissolved organic carbon (DOC) concentrations decreased for almost samples in the range of 7.6 to 87.3% (ANOVA, p<0.05). The specific UV absorption (SUVA) values also decreased for almost samples after the first 3 months and then increased gradually afterward in range of 3.3 to 108.4%. Both time and the interaction between time and the temperature had the statistically significant effects on the SUVA values (MANOVA, p<0.05). Humification index (HIX) showed the significant increase trends during the duration of incubation and temperature for almost the samples (ANOVA, p<0.05). Higher decreases in the DOC values and increases in HIX were observed at higher temperatures, whereas the opposite trend was observed for samples with N-addition. The PARAFAC results showed that three fluorescence components: terrestrial humic (C1), microbial humic-like (C2), and protein-like (C3), constituted the fluorescence matrices of soil samples. During the experiment, labile DOM from the soils was

  2. Sediment oxygen consumption and vertical flux of organic matter in the Seto Inland Sea, Japan

    NASA Astrophysics Data System (ADS)

    Nakamura, Y.

    2003-02-01

    Vertical flux of organic matter and rates of sediment oxygen consumption (SOC) were measured in summer 2000 at a muddy sediment site (21 m depth) in the Seto Inland Sea, Japan. During the 26-day experimental period (15 July to 9 August), a diatom bloom occurred, lasting for about a week. The vertical flux of organic carbon and chlorophyll a ( FC and Fchl), measured at 12.5 m depth, showed a sharp peak following the development of the bloom. Under these conditions, SOC ranged from 1.4 to 3.0 mmol O 2 m -2 h -1, and it was strongly influenced by the biomass of macrozoobenthos present in the experimental chambers used for SOC measurements. However, macrozoobenthic oxygen consumption made up only 5% of SOC. SOC variations were not coupled with corresponding changes in FC or Fchl. The effects of other factors, such as water temperature, as well as levels of sediment chlorophyll a and bacterial abundance, were minor, presumably because these parameters did not vary strongly during the study period. The average SOC value corrected for macrozoobenthos oxygen consumption (1.8 mmol O 2 m -2 h -1) and converted into the decomposition rate of organic material was nearly balanced with the FC averaged over the experimental period (0.7 C m -2 day -1). This indicates that this muddy sediment area in the Seto Inland Sea plays an important role in the degradation of organic material supplied from the water column.

  3. A depocenter of organic matter at 7800 m depth in the SE Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Danovaro, R.; Della Croce, N.; Dell'Anno, A.; Pusceddu, A.

    2003-12-01

    The Atacama trench, the deepest ecosystem of the southern Pacific Ocean (ca. 8000 m depth) was investigated during the Atacama Trench International Expedition. Sediments, collected at three bathyal stations (1040-1355 m depth) and at a hadal site (7800 m) were analyzed for organic matter quantity and biochemical composition (in terms of phytopigments, proteins, carbohydrates and lipids), bacterial abundance, biomass and carbon production and extracellular enzymatic activities. Functional chlorophyll- a (18.0±0.10 mg m -2), phytodetritus (322.2 mg m -2) and labile organic carbon (16.9±4.3 g C m -2) deposited on surface sediments at hadal depth (7800 m) reached concentrations similar to those encountered in highly productive shallow coastal areas. High values of bacterial C production and aminopeptidase activity were also measured (at in situ temperature and 1 atm). The chemical analyses of the Atacama hadal sediments indicate that this trench behaves as a deep oceanic trap for organic material. We hypothesize that, despite the extreme physical conditions, benthic microbial processes might be accelerated as a result of the organic enrichment.

  4. [Characterizing Structural Composition of Dissolved and Particulate Organic Matter from Sediment Pore Water in a Urban River Using Excitation-Emission Matrix Fluorescence with Self-Organizing Map].

    PubMed

    Yu, Hui-bin; Song, Yong-hui; Yang, Nan; Du, Er-deng; Peng, Jian-feng; Zhi, Er-quan

    2015-04-01

    Excitation-emission matrix (EEM) fluorescence with self-organizing map was applied to characterize structural composition and spatial distribution of dissolved (DOM) and particulate (POM) organic matter from sediment pore water in a typical urban river. Ten sediment pore water samples were collected from the mainstream of Baitabuhe River in Shenyang City of northeast China, along a human impact gradient, i. e. river source, rural and urban regions. DOM and POM were extracted from the pore water, and their EEM fluorescence spectra were measured. ƒ450/500 of DOM ranged from 1.82 to 1.91, indicating that DOM is mainly from microbial source; ƒ450/500 of POM ranged from 1.42 to 1.68, suggesting that POM derived from land. Four components were identified from DOM and POM fractions by self-organizing map, which included tyrosine-like, tryptophan-like, fulvic-like and humic-like matters. Tyrosine-like originated from fresh and less-degraded material with a high potential for oxida- tion, which was considered as representative components of DOM and POM. Tryptophan-like was associated with microbial byproduct-like material, and can indicate microbial activities. The abundance sum of all components in DOM is roughly 2 times more than that in POM. The mean relative abundance of tyrosine-like was more than 50%, while tryptophan-like was about 18.6%-23.1%. Abundance of fulvic-like was much more than that of humic-like, but they were only a small proportion of organic matter fractions. Based on principal component analysis, the characteristics of DOM and POM distinctly were distributed along river source, rural region and urban region, proving that the river was deeply influenced by human activity. PMID:26197578

  5. Geochemical drivers of organic matter decomposition in Arctic tundra soils

    SciTech Connect

    Herndon, Elizabeth M.; Yang, Ziming; Graham, David E.; Wullschleger, Stan D.; Gu, Baohua; Liang, Liyuan; Bargar, John; Janot, Noemie; Regier, Tom Z.

    2015-12-07

    Climate change is warming tundra ecosystems in the Arctic, resulting in the decomposition of previously-frozen soil organic matter (SOM) and release of carbon (C) to the atmosphere; however, the processes that control SOM decomposition and C emissions remain highly uncertain. In this study, we evaluate geochemical factors that influence anaerobic production of carbon dioxide (CO2) and methane (CH4) in the active layers of four ice-wedge polygons. Surface and soil pore waters were collected during the annual thaw season over a two-year period in an area containing waterlogged, low-centered polygons and well-drained, high-centered polygons. We report spatial and seasonal patterns of dissolved gases in relation to the geochemical properties of Fe and organic C as determined using spectroscopic and chromatographic techniques. Iron was present as Fe(II) in soil solution near the permafrost boundary but enriched as Fe(III) in the middle of the active layer, similar to dissolved aromatic-C and organic acids. Dissolved CH4 increased relative to dissolved CO2 with depth and varied with soil moisture in the middle of the active layer in patterns that were positively correlated with the proportion of dissolved Fe(III) in transitional and low-centered polygon soils but negatively correlated in the drier flat- and high-centered polygons. These results suggest that microbial-mediated Fe oxidation and reduction influence respiration/fermentation of SOM and production of substrates (e.g., low-molecular-weight organic acids) for methanogenesis. As a result, we infer that geochemical differences induced by water saturation dictate microbial products of SOM decomposition, and Fe geochemistry is an important factor regulating methanogenesis in anoxic tundra soils.

  6. Geochemical drivers of organic matter decomposition in Arctic tundra soils

    DOE PAGES

    Herndon, Elizabeth M.; Yang, Ziming; Graham, David E.; Wullschleger, Stan D.; Gu, Baohua; Liang, Liyuan; Bargar, John; Janot, Noemie; Regier, Tom Z.

    2015-12-07

    Climate change is warming tundra ecosystems in the Arctic, resulting in the decomposition of previously-frozen soil organic matter (SOM) and release of carbon (C) to the atmosphere; however, the processes that control SOM decomposition and C emissions remain highly uncertain. In this study, we evaluate geochemical factors that influence anaerobic production of carbon dioxide (CO2) and methane (CH4) in the active layers of four ice-wedge polygons. Surface and soil pore waters were collected during the annual thaw season over a two-year period in an area containing waterlogged, low-centered polygons and well-drained, high-centered polygons. We report spatial and seasonal patterns ofmore » dissolved gases in relation to the geochemical properties of Fe and organic C as determined using spectroscopic and chromatographic techniques. Iron was present as Fe(II) in soil solution near the permafrost boundary but enriched as Fe(III) in the middle of the active layer, similar to dissolved aromatic-C and organic acids. Dissolved CH4 increased relative to dissolved CO2 with depth and varied with soil moisture in the middle of the active layer in patterns that were positively correlated with the proportion of dissolved Fe(III) in transitional and low-centered polygon soils but negatively correlated in the drier flat- and high-centered polygons. These results suggest that microbial-mediated Fe oxidation and reduction influence respiration/fermentation of SOM and production of substrates (e.g., low-molecular-weight organic acids) for methanogenesis. As a result, we infer that geochemical differences induced by water saturation dictate microbial products of SOM decomposition, and Fe geochemistry is an important factor regulating methanogenesis in anoxic tundra soils.« less

  7. Adsorption of paraquat on soil organic matter: effect of exchangeable cations and dissolved organic carbon.

    PubMed

    Gondar, Dora; López, Rocío; Antelo, Juan; Fiol, Sarah; Arce, Florencio

    2012-10-15

    Herbicides that interact with soil organic matter do so with both the solid and the dissolved fractions, so that the distribution of herbicide between the soil solution and solid phases is determined by competitive effects. In the present study, adsorption experiments were carried out with the cationic herbicide paraquat and untreated and acid-washed samples of a peat soil, at different values of pH and ionic strength. Less herbicide was adsorbed onto the untreated peat than onto the acid-washed peat; the difference was due to the presence of exchangeable cations, as demonstrated in experiments carried out by adding Ca(2+) to suspensions of acid-washed peat. The results were interpreted by an electrostatic model and the fitting parameters indicated that the adsorption constants were the same for both samples of peat, although the number of binding sites available was different. Simultaneous resolution of the adsorption equilibrium of paraquat for the soil organic matter (SOM) and of the binding equilibrium between paraquat and dissolved organic matter (DOM) enabled the distribution of paraquat between the solid and solution phases to be determined. The increased solubility of the SOM with increasing pH led to a decrease in the fraction of paraquat retained on the peat surface above pH 5.5, which favors the mobility of the herbicide in the soil.

  8. Partition of nonpolar organic pollutants from water to soil and sediment organic matters

    USGS Publications Warehouse

    Chiou, C.T.

    1995-01-01

    The partition coefficients (Koc) of carbon tetrachloride and 1,2-dichlorobenzene between normal soil/sediment organic matter and water have been determined for a large set of soils, bed sediments, and suspended solids from the United States and the People's Republic of China. The Koc values for both solutes are quite invariant either for the soils or for the bed sediments; the values on bed sediments are about twice those on soils. The similarity of Koc values between normal soils and between normal bed sediments suggests that natural organic matters in soils (or sediments) of different geographic origins exhibit comparable polarities and possibly comparable compositions. The results also suggest that the process that converts eroded soils into bed sediments brings about a change in the organic matter property. The difference between soil and sediment Koc values provides a basis for identifying the source of suspended solids in river waters. The very high Koc values observed for some special soils and sediments are diagnostic of severe anthropogenic contamination.

  9. Molecular-level dynamics of refractory dissolved organic matter

    NASA Astrophysics Data System (ADS)

    Niggemann, J.; Gerdts, G.; Dittmar, T.

    2012-04-01

    Refractory dissolved organic matter (DOM) accounts for most of the global oceanic organic carbon inventory. Processes leading to its formation and factors determining its stability are still largely unknown. We hypothesize that refractory DOM carries a universal molecular signature. Characterizing spatial and temporal variability in this universal signature is a key to understanding dynamics of refractory DOM. We present results from a long-term study of the DOM geo-metabolome in the open North Sea. Geo-metabolomics considers the entity of DOM as a population of compounds, each characterized by a specific function and reactivity in the cycling of energy and elements. Ten-thousands of molecular formulae were identified in DOM by ultrahigh resolution mass spectrometry analysis (FT-ICR-MS, Fourier-Transform Ion Cyclotron Resonance Mass Spectrometry). The DOM pool in the North Sea was influenced by a complex interplay of processes that produced, transformed and degraded dissolved molecules. We identified a stable fraction in North Sea DOM with a molecular composition similar to deep ocean DOM. Molecular-level changes in this stable fraction provide novel information on dynamics and interactions of refractory DOM.

  10. Removal of bromide and natural organic matter by anion exchange.

    PubMed

    Hsu, Susan; Singer, Philip C

    2010-04-01

    Bromide removal by anion exchange was explored for various water qualities, process configurations, and resin characteristics. Simulated natural waters containing different amounts of natural organic matter (NOM), bicarbonate, chloride, and bromide were treated with a polyacrylate-based magnetic ion exchange (MIEX) resin on a batch basis to evaluate the effectiveness of the resin for removal of bromide. While bromide removal was achieved to some degree, alkalinity (bicarbonate), dissolved organic carbon (DOC), and chloride were shown to inhibit bromide removal in waters with bromide concentrations of 100 and 300 microg/L. Water was also treated using a two-stage batch MIEX process. Two-stage treatment resulted in only a slight improvement in bromide removal compared to single-stage treatment, presumably due to competition with the high concentration of chloride which is present along with bromide in natural waters. In view of the relatively poor bromide removal results for the MIEX resin, a limited set of experiments was performed using polystyrene resins. DOC and bromide removal were compared by treating model waters with MIEX and two polystyrene resins, Ionac A-641 and Amberlite IRA910. The two polystyrene resins were seen to be more effective for bromide removal, while the MIEX resin was more effective at removing DOC.

  11. Precipitates in landfill leachate mediated by dissolved organic matters.

    PubMed

    Li, Zhenze; Xue, Qiang; Liu, Lei; Li, Jiangshan

    2015-04-28

    Clogging of landfill leachate collection system is so ubiquitous that it causes problems to landfills. Although precipitations of calcite and other minerals have been widely observed, the mechanism of precipitation remains obscure. We examined the clog composition, dissolved organic matters, leachate chemical compositions and the correlation of these variables in view of the precipitation process. It is shown that Dissolved Organic Carbon (DOC) inhibits precipitation of landfill leachate. Using the advanced NICA-Donnan model, the analysis of aqueous chemical reactions between Mg-Ca-DOC-CO2 suggests a good agreement with experimental observations. Calcite and dolomite are both found to be oversaturated in most of the landfill leachate samples. DOC is found to preferentially bind with Mg than Ca, leading to more likely precipitation of Calcite than dolomite from landfill leachate. The NICA-Donnan model gives a reasonable estimation of dolomite saturation index in a wide range of DOC. Modeling confirms the major precipitation mechanism in terms of alkaline earth metal carbonate. Uncertainties in model parameters are discussed with particular focus on DOC composition, functional group types and density concentration and the influential factors. PMID:25661175

  12. Transformation of organic matters in animal wastes during composting.

    PubMed

    Wang, Ke; He, Chao; You, Shijie; Liu, Weijie; Wang, Wei; Zhang, Ruijun; Qi, Huanhuan; Ren, Nanqi

    2015-12-30

    The transformation of organic matters in swine, cow and chicken manures was compared and evaluated using elemental analysis, FTIR, (13)C NMR, pyrolysis/GC/MS, Biolog and multiple fluorochrome over 60 days composting. The results revealed that cow manure exhibited the greatest C/N and aromaticity, whereas chicken manure exhibited the highest nitrogen and sulfur contents. O-alkyl-C was predominant carbon structure in the three manures. Alkyl-C and carboxyl-C were decomposed dramatically in initial 10 days, and mineralization of O-alkyl-C dominated the curing stage. During pyrolysis of chicken, cow, and swine manures, the majority products were fatty acids, phenols and cholestene derivatives, respectively, however, phenols and cholestene derivatives were strongly reduced in the mature manures. Furthermore, microorganisms in the raw cow, chicken and swine manure demonstrated the highest degradation capabilities for carbohydrates, lipids and amino acids, respectively. Spatial differences in the contents of solid organics in the manure particles were negligible through detection by multiple staining methods during composting.

  13. Effects of pressure on thermal evolution of organic matter

    SciTech Connect

    Goffe, B.; Domine, F. )

    1989-09-01

    In the internal metamorphic zones of the French Alps, organic matter-bearing terrestrial sediments of Dogger age underwent an Eocene high-pressure metamorphic event (607 kbar at 300{degree}-330{degree}C). These metasediments now contain, trapped in metamorphic minerals, low evolved kerogen (small extent of molecular orientation), heavy hydrocarbon compounds (aromatic and aliphatic up to C{sup 30} with traces of pristane and phytane molecules), and gases with low C{sup 1}/C{sup 2}-C{sup 6} ratios. However, the degree of organic maturation (equivalent to catagenesis) is much less than that predicted by classical models. This field example indicates that the oil window opens with increasing pressure. Experimental pyrolysis of supercritical hexane performed in a closed, constant-pressure gold reactor at 210-15,600 bars pressure range and 290{degree}-365{degree}C, clearly demonstrates the important influence of pressure on the product distribution of hexane pyrolysis: as pressure is increased, relative light product yields decrease and heavy products increase. This can be interpreted mainly by considering the activation volumes of the reactions involved. In conclusion, the experimental and natural examples presented here indicate that the rate of thermal maturation decreases with pressure.

  14. Transformation of organic matters in animal wastes during composting.

    PubMed

    Wang, Ke; He, Chao; You, Shijie; Liu, Weijie; Wang, Wei; Zhang, Ruijun; Qi, Huanhuan; Ren, Nanqi

    2015-12-30

    The transformation of organic matters in swine, cow and chicken manures was compared and evaluated using elemental analysis, FTIR, (13)C NMR, pyrolysis/GC/MS, Biolog and multiple fluorochrome over 60 days composting. The results revealed that cow manure exhibited the greatest C/N and aromaticity, whereas chicken manure exhibited the highest nitrogen and sulfur contents. O-alkyl-C was predominant carbon structure in the three manures. Alkyl-C and carboxyl-C were decomposed dramatically in initial 10 days, and mineralization of O-alkyl-C dominated the curing stage. During pyrolysis of chicken, cow, and swine manures, the majority products were fatty acids, phenols and cholestene derivatives, respectively, however, phenols and cholestene derivatives were strongly reduced in the mature manures. Furthermore, microorganisms in the raw cow, chicken and swine manure demonstrated the highest degradation capabilities for carbohydrates, lipids and amino acids, respectively. Spatial differences in the contents of solid organics in the manure particles were negligible through detection by multiple staining methods during composting. PMID:26311195

  15. Chromophoric dissolved organic matter export from U.S. rivers

    NASA Astrophysics Data System (ADS)

    Spencer, Robert G. M.; Aiken, George R.; Dornblaser, Mark M.; Butler, Kenna D.; Holmes, R. Max; Fiske, Greg; Mann, Paul J.; Stubbins, Aron

    2013-04-01

    Chromophoric dissolved organic matter (CDOM) fluxes and yields from 15 major U.S. rivers draining an assortment of terrestrial biomes are presented. A robust relationship between CDOM and dissolved organic carbon (DOC) loads is established (e.g., a350 versus DOC; r2 = 0.96, p < 0.001). Calculated CDOM yields are also correlated to watershed percent wetland (e.g. a350; r2 = 0.81, p < 0.001) providing a method for the estimation of CDOM export from ungauged watersheds. A large variation in CDOM yields was found across the rivers. The two rivers in the north-eastern U.S. (Androscoggin and Penobscot), the Edisto draining into the South Atlantic Bight, and some rivers draining into the Gulf of Mexico (Atchafalaya and Mobile) exhibit the highest CDOM yields, linked to extensive wetlands in these watersheds. If the Edisto CDOM yield is representative of other rivers draining into the South Atlantic Bight, this would result in a CDOM load equivalent to that of the Mississippi from a region of approximately 10% of the Mississippi watershed, indicating the importance of certain regions with respect to the role of terrigenous CDOM in ocean color budgets.

  16. Chromophoric Dissolved Organic Matter Export from U.S. Rivers

    NASA Astrophysics Data System (ADS)

    Spencer, R. G.; Aiken, G.; Dornblaser, M.; Butler, K. D.; Holmes, R. M.; Fiske, G.; Mann, P. J.; Stubbins, A.

    2012-12-01

    Chromophoric dissolved organic matter (CDOM) fluxes and yields from 15 major U.S. rivers draining an assortment of terrestrial biomes are presented. Utilizing CDOM and dissolved organic carbon (DOC) flux data we establish a robust universal relationship between CDOM and DOC loads. The application of this relationship allows future studies to derive DOC loads from CDOM utilizing emerging in-situ or remote sensing technologies and thus refine river-to-ocean DOC fluxes, as well as exploit historic imagery to examine how fluxes may have changed. Calculated CDOM yields from the 15 U.S. rivers highlight the importance of certain regions with respect to CDOM flux to the coastal ocean. This approach indicates that future studies might predict CDOM and DOC yields for different watershed types that could then be readily converted to loads providing for the estimation of CDOM and DOC export from ungauged watersheds. Examination of CDOM yields also highlights important geographical regions for future study with respect to the role of terrigenous CDOM in ocean color budgets and CDOM's role in biogeochemical processes.

  17. Toward an experimental synthesis of the chondritic insoluble organic matter

    NASA Astrophysics Data System (ADS)

    Biron, Kasia; Derenne, Sylvie; Robert, FrançOis; Rouzaud, Jean-NoëL.

    2015-08-01

    Based on the statistical model proposed for the molecular structure of the insoluble organic matter (IOM) isolated from the Murchison meteorite, it was recently proposed that, in the solar T-Tauri disk regions where (photo)dissociation of gaseous molecules takes place, aromatics result from the cyclization/aromatization of short aliphatics. This hypothesis is tested in this study, with n-alkanes being submitted to high-frequency discharge at low pressure. The contamination issue was eliminated using deuterated precursor. IOM was formed and studied using solid-state nuclear magnetic resonance, pyrolysis coupled to gas chromatography and mass spectrometry, RuO4 oxidation, and high-resolution transmission electron microscopy. It exhibits numerous similarities at the molecular level with the hydrocarbon backbone of the natural IOM, reinforcing the idea that the initial precursors of the IOM were originally chains in the gas. Moreover, a fine comparison between the chemical structure of several meteorite IOM suggests either that (i) the meteorite IOMs share a common precursor standing for the synthetic IOM or that (ii) the slight differences between the meteorite IOMs reflect differences in their environment at the time of their formation i.e., related to plasma temperature that, in turn, dictates the dissociation-recombination rates of organic fragments.

  18. Precipitates in landfill leachate mediated by dissolved organic matters.

    PubMed

    Li, Zhenze; Xue, Qiang; Liu, Lei; Li, Jiangshan

    2015-04-28

    Clogging of landfill leachate collection system is so ubiquitous that it causes problems to landfills. Although precipitations of calcite and other minerals have been widely observed, the mechanism of precipitation remains obscure. We examined the clog composition, dissolved organic matters, leachate chemical compositions and the correlation of these variables in view of the precipitation process. It is shown that Dissolved Organic Carbon (DOC) inhibits precipitation of landfill leachate. Using the advanced NICA-Donnan model, the analysis of aqueous chemical reactions between Mg-Ca-DOC-CO2 suggests a good agreement with experimental observations. Calcite and dolomite are both found to be oversaturated in most of the landfill leachate samples. DOC is found to preferentially bind with Mg than Ca, leading to more likely precipitation of Calcite than dolomite from landfill leachate. The NICA-Donnan model gives a reasonable estimation of dolomite saturation index in a wide range of DOC. Modeling confirms the major precipitation mechanism in terms of alkaline earth metal carbonate. Uncertainties in model parameters are discussed with particular focus on DOC composition, functional group types and density concentration and the influential factors.

  19. Global effects of agriculture on fluvial dissolved organic matter.

    PubMed

    Graeber, Daniel; Boëchat, Iola G; Encina-Montoya, Francisco; Esse, Carlos; Gelbrecht, Jörg; Goyenola, Guillermo; Gücker, Björn; Heinz, Marlen; Kronvang, Brian; Meerhoff, Mariana; Nimptsch, Jorge; Pusch, Martin T; Silva, Ricky C S; von Schiller, Daniel; Zwirnmann, Elke

    2015-11-06

    Agricultural land covers approximately 40% of Earth's land surface and affects hydromorphological, biogeochemical and ecological characteristics of fluvial networks. In the northern temperate region, agriculture also strongly affects the amount and molecular composition of dissolved organic matter (DOM), which constitutes the main vector of carbon transport from soils to fluvial networks and to the sea, and is involved in a large variety of biogeochemical processes. Here, we provide first evidence about the wider occurrence of agricultural impacts on the concentration and composition of fluvial DOM across climate zones of the northern and southern hemispheres. Both extensive and intensive farming altered fluvial DOM towards a more microbial and less plant-derived composition. Moreover, intensive farming significantly increased dissolved organic nitrogen (DON) concentrations. The DOM composition change and DON concentration increase differed among climate zones and could be related to the intensity of current and historical nitrogen fertilizer use. As a result of agriculture intensification, increased DON concentrations and a more microbial-like DOM composition likely will enhance the reactivity of catchment DOM emissions, thereby fuelling the biogeochemical processing in fluvial networks, and resulting in higher ecosystem productivity and CO2 outgassing.

  20. Mineral surface-organic matter interactions: basics and applications

    NASA Astrophysics Data System (ADS)

    Valdrè, G.; Moro, D.; Ulian, G.

    2012-03-01

    The ability to control the binding of biological and organic molecules to a crystal surface is central in several fields; for example, in biotechnology, catalysis, molecular microarrays, biosensors preparation and environmental sciences. The nano-morphology and nanostructure at the surface may have physico-chemical properties that are very different from those of the underlying mineral substrate. Recent developments in scanning probe microscopy (SPM) have widened the spectrum of possible investigations that can be performed at the nanometric level on the surface of minerals. They range from the study of physical properties such as surface potential, electric field topological determination, Brønsted-Lowry site distributions, to chemical and spectroscopic analysis in air, in liquid or in gaseous environments. After an introduction to SPM modes of operation and new SPM-based technological developments, we will present recent examples of applications in the study of interactions between organic matter and mineral surface and report on the advances in knowledge that have been made by the use of scanning probe microscopy.

  1. Effects of agricultural practices on organic matter degradation in ditches

    PubMed Central

    Hunting, Ellard R.; Vonk, J. Arie; Musters, C.J.M.; Kraak, Michiel H.S.; Vijver, Martina G.

    2016-01-01

    Agricultural practices can result in differences in organic matter (OM) and agricultural chemical inputs in adjacent ditches, but its indirect effects on OM composition and its inherent consequences for ecosystem functioning remain uncertain. This study determined the effect of agricultural practices (dairy farm grasslands and hyacinth bulb fields) on OM degradation by microorganisms and invertebrates with a consumption and food preference experiment in the field and in the laboratory using natural OM collected from the field. Freshly cut grass and hyacinths were also offered to control for OM composition and large- and small mesh-sizes were used to distinguish microbial decomposition and invertebrate consumption. Results show that OM decomposition by microorganisms and consumption by invertebrates was similar throughout the study area, but that OM collected from ditches adjacent grasslands and freshly cut grass and hyacinths were preferred over OM collected from ditches adjacent to a hyacinth bulb field. In the case of OM collected from ditches adjacent hyacinth bulb fields, both microbial decomposition and invertebrate consumption were strongly retarded, likely resulting from sorption and accumulation of pesticides. This outcome illustrates that differences in agricultural practices can, in addition to direct detrimental effects on aquatic organisms, indirectly alter the functioning of adjacent aquatic ecosystems. PMID:26892243

  2. Role of dissolved organic matter in ice photochemistry.

    PubMed

    Grannas, Amanda M; Pagano, Lisa P; Pierce, Brittany C; Bobby, Rachel; Fede, Alexis

    2014-09-16

    In this study, we provide evidence that dissolved organic matter (DOM) plays an important role in indirect photolysis processes in ice, producing reactive oxygen species (ROS) and leading to the efficient photodegradation of a probe hydrophobic organic pollutant, aldrin. Rates of DOM-mediated aldrin loss are between 2 and 56 times faster in ice than in liquid water (depending on DOM source and concentration), likely due to a freeze-concentration effect that occurs when the water freezes, providing a mechanism to concentrate reactive components into smaller, liquid-like regions within or on the ice. Rates of DOM-mediated aldrin loss are also temperature dependent, with higher rates of loss as temperature decreases. This also illustrates the importance of the freeze-concentration effect in altering reaction kinetics for processes occurring in environmental ices. All DOM source types studied were able to mediate aldrin loss, including commercially available fulvic and humic acids and an authentic Arctic snow DOM sample isolated by solid phase extraction, indicating the ubiquity of DOM in indirect photochemistry in environmental ices. PMID:25157605

  3. Effects of agricultural practices on organic matter degradation in ditches.

    PubMed

    Hunting, Ellard R; Vonk, J Arie; Musters, C J M; Kraak, Michiel H S; Vijver, Martina G

    2016-01-01

    Agricultural practices can result in differences in organic matter (OM) and agricultural chemical inputs in adjacent ditches, but its indirect effects on OM composition and its inherent consequences for ecosystem functioning remain uncertain. This study determined the effect of agricultural practices (dairy farm grasslands and hyacinth bulb fields) on OM degradation by microorganisms and invertebrates with a consumption and food preference experiment in the field and in the laboratory using natural OM collected from the field. Freshly cut grass and hyacinths were also offered to control for OM composition and large- and small mesh-sizes were used to distinguish microbial decomposition and invertebrate consumption. Results show that OM decomposition by microorganisms and consumption by invertebrates was similar throughout the study area, but that OM collected from ditches adjacent grasslands and freshly cut grass and hyacinths were preferred over OM collected from ditches adjacent to a hyacinth bulb field. In the case of OM collected from ditches adjacent hyacinth bulb fields, both microbial decomposition and invertebrate consumption were strongly retarded, likely resulting from sorption and accumulation of pesticides. This outcome illustrates that differences in agricultural practices can, in addition to direct detrimental effects on aquatic organisms, indirectly alter the functioning of adjacent aquatic ecosystems. PMID:26892243

  4. Role of dissolved organic matter in ice photochemistry.

    PubMed

    Grannas, Amanda M; Pagano, Lisa P; Pierce, Brittany C; Bobby, Rachel; Fede, Alexis

    2014-09-16

    In this study, we provide evidence that dissolved organic matter (DOM) plays an important role in indirect photolysis processes in ice, producing reactive oxygen species (ROS) and leading to the efficient photodegradation of a probe hydrophobic organic pollutant, aldrin. Rates of DOM-mediated aldrin loss are between 2 and 56 times faster in ice than in liquid water (depending on DOM source and concentration), likely due to a freeze-concentration effect that occurs when the water freezes, providing a mechanism to concentrate reactive components into smaller, liquid-like regions within or on the ice. Rates of DOM-mediated aldrin loss are also temperature dependent, with higher rates of loss as temperature decreases. This also illustrates the importance of the freeze-concentration effect in altering reaction kinetics for processes occurring in environmental ices. All DOM source types studied were able to mediate aldrin loss, including commercially available fulvic and humic acids and an authentic Arctic snow DOM sample isolated by solid phase extraction, indicating the ubiquity of DOM in indirect photochemistry in environmental ices.

  5. Global effects of agriculture on fluvial dissolved organic matter

    PubMed Central

    Graeber, Daniel; Boëchat, Iola G.; Encina-Montoya, Francisco; Esse, Carlos; Gelbrecht, Jörg; Goyenola, Guillermo; Gücker, Björn; Heinz, Marlen; Kronvang, Brian; Meerhoff, Mariana; Nimptsch, Jorge; Pusch, Martin T.; Silva, Ricky C. S.; von Schiller, Daniel; Zwirnmann, Elke

    2015-01-01

    Agricultural land covers approximately 40% of Earth’s land surface and affects hydromorphological, biogeochemical and ecological characteristics of fluvial networks. In the northern temperate region, agriculture also strongly affects the amount and molecular composition of dissolved organic matter (DOM), which constitutes the main vector of carbon transport from soils to fluvial networks and to the sea, and is involved in a large variety of biogeochemical processes. Here, we provide first evidence about the wider occurrence of agricultural impacts on the concentration and composition of fluvial DOM across climate zones of the northern and southern hemispheres. Both extensive and intensive farming altered fluvial DOM towards a more microbial and less plant-derived composition. Moreover, intensive farming significantly increased dissolved organic nitrogen (DON) concentrations. The DOM composition change and DON concentration increase differed among climate zones and could be related to the intensity of current and historical nitrogen fertilizer use. As a result of agriculture intensification, increased DON concentrations and a more microbial-like DOM composition likely will enhance the reactivity of catchment DOM emissions, thereby fuelling the biogeochemical processing in fluvial networks, and resulting in higher ecosystem productivity and CO2 outgassing. PMID:26541809

  6. Organic matter in the ancient Alpine Tethyan Ocean Continental Transition

    NASA Astrophysics Data System (ADS)

    Mateeva, Tsvetomila; Wolff, George; Kusznir, Nick; Wheeler, John; Manataschal, Gianreto

    2016-04-01

    Studies of hydrothermal vents in modern ocean settings suggest that methane produced by serpentinization can support methanotrophic bio-systems. Are such bio-systems locally restricted to hydrothermal vents or are more pervasive, being linked with the geology of serpentinized mantle in the subsurface? Answering this question has implications for our understanding of the global importance of hidden sub-surface bio-systems, the fate of methane and the carbon cycle. The ocean-continent transition (OCT) of magma-poor rifted continental margins, exhumed within mountain belts by continent collision, provides an opportunity to investigate this question. Initial data from the Totalp unit in the Eastern Swiss Alps, representing exhumed OCT of the Alpine Tethyan rifted continental margin, shows the presence of various hydrocarbons (Mateeva et al., in prep.). Samples from other Tethyan OCT locations, consisting of the Tasna nappe and Platta unit of the Eastern Swiss Alps and Chenaillet in the Western Alps, have also been analysed to investigate the presence or absence of methanotrophic biosystems within serpentinized exhumed mantle and associated ophicalcite and syn-rift sediments. Samples from these remnant Tethyan OCT locations are characterized by low and varied organic carbon concentrations that reflect the large lithological diversity of this area. The samples contain hydrocarbons in the form of n-alkanes mostly in the range C20 - C32, polynuclear aromatic hydrocarbons (PAHs) and various biomarkers (e.g. steranes, hopanes). A typical sample from the hydrothermal system in Platta shows the lithological characteristics of a black smoker, but with no indication of a more developed biosystem. Preliminary results from the examined Tethyan OCT locations (Tasna, Platta, Chenaillet) show evidence for the preservation of marine organic matter in the serpentinized mantle and overlying sediments, although there is no unequivocal indication that the organic matter is generated from

  7. Do Long-Term Changes in Organic Matter Inputs to Forest Soils Affect Dissolved Organic Matter Chemistry and Export?

    NASA Astrophysics Data System (ADS)

    Lajtha, K.; Strid, A.; Lee, B. S.

    2014-12-01

    Dissolved organic matter (DOM) production and transport play an important role in regulating organic matter (OM) distribution through a soil profile and ultimately, OM stabilization or export to aquatic systems. The contributions of varying OM inputs to the quality and amount of DOM as it passes through a soil profile remain relatively unknown. The Detrital Input and Removal Treatment (DIRT) site at the H. J. Andrews Experimental Forest in Oregon has undergone 17 years of litter, wood and root input manipulations and allows us to guage shifts in DOM chemistry induced by long-term changes to aboveground and belowground OM additions and exclusions. Using fluorescence and UV spectroscopy to characterize fluorescent properties, extent of decomposition, and sources of DOM in streams and soil solutions collected with lysimeters and soil extractions, we have assessed the importance of fresh OM inputs to DOM chemistry. Soil extracts from DIRT plots had a higher fluorescence index (FI) than lysimeter solutions or stream water. A high FI in surface water is generally interpreted as indicative of a high proportion of microbially-derived DOM. However, we suspect that the high FI in soil extracts is due to a higher proportion of non-aromatic DOM from fresh soil that microorganisms consume in transit through the soil profile to lysimeters or to streams. High redox index (RI) values were observed in lysimeters from the April 2014 sampling compared with the November 2013 sampling. These RI values show evidence of more reducing conditions at the end of the rainy season in the spring compared to the onset of the rainy season in the fall. Lysimeter water collected in No Input, No Litter, and No Root treatments contained high proportions of protein, suggesting the absence of carbon inputs changes activities of the microbial community. Observed variations reflect the viability of using fluorescent properties to explore the terrestrial-aquatic interface.

  8. Abundance of potentially pathogenic micro-organisms in Penaeus monodon larvae rearing systems in India.

    PubMed

    Vaseeharan, Baskaralingam; Ramasamy, Palaniappan

    2003-01-01

    Monodon baculovirls (MBV), external fouling organisms (EFO) and bacteria (especially Vibrio species) were monitored during 1996-1997 at nine different Penaeus monodon rearing hatcheries in India. Total cultivable heterotrophic bacteria, Vibrio-like-bacteria, presumptive Vibrio harveyi, Vibrio anguillarum, Vibrio vulnificus counts were determined from shrimp eggs, post larvae, rearing tank water, source sea water, feed (Artemia nauplii and microencapsulated feed). The MBV infected post larvae and their environment showed higher Vibrio-like-bacteria than uninfected post larvae. An overwhelming predominance of presumptive Vibrio harveyi and Vibrio anguillarum was observed in post larval rearing tank water, MBV infected and uninfected post larvae. Vibrio-like-bacteria in Artemia nauplii clearly showed the possible source of these pathogenic bacteria in the hatchery environments. Quantitative analysis of Vibrio-like-bacteria in hatcheries revealed that when the Vibrio-like-bacteria increases to 2 x 10(2) CFU mortality of the post larvae occurs. Abundance of these micro-organisms in hatchery samples indicated that they are opportunistic pathogens which can invade the shrimp tissue, subsequently cause disease when the post larvae were under stressful conditions.

  9. Effects of multiple levels of social organization on survival and abundance.

    PubMed

    Ward, Eric J; Semmens, Brice X; Holmes, Elizabeth E; Balcomb Iii, Ken C

    2011-04-01

    Identifying how social organization shapes individual behavior, survival, and fecundity of animals that live in groups can inform conservation efforts and improve forecasts of population abundance, even when the mechanism responsible for group-level differences is unknown. We constructed a hierarchical Bayesian model to quantify the relative variability in survival rates among different levels of social organization (matrilines and pods) of an endangered population of killer whales (Orcinus orca). Individual killer whales often participate in group activities such as prey sharing and cooperative hunting. The estimated age-specific survival probabilities and survivorship curves differed considerably among pods and to a lesser extent among matrilines (within pods). Across all pods, males had lower life expectancy than females. Differences in survival between pods may be caused by a combination of factors that vary across the population's range, including reduced prey availability, contaminants in prey, and human activity. Our modeling approach could be applied to demographic rates for other species and for parameters other than survival, including reproduction, prey selection, movement, and detection probabilities. PMID:21054527

  10. Pelagic and sympagic contribution of organic matter to zooplankton and vertical export in the Barents Sea marginal ice zone

    NASA Astrophysics Data System (ADS)

    Tamelander, Tobias; Reigstad, Marit; Hop, Haakon; Carroll, Michael L.; Wassmann, Paul

    2008-10-01

    The structure and function of the marine food web strongly regulate the cycling of organic matter derived from primary production by phytoplankton and ice algae in Arctic shelf seas. Improved knowledge of trophic relationships and export of organic matter from the surface layer is needed to better understand how the Arctic marine ecosystem may respond to climate-related changes in distribution of sea ice, water masses, and associated primary production regimes. Pelagic and sympagic inputs of organic matter to dominant meso- and macrozooplankton species and vertical export were investigated in the northern Barents Sea by means of stable carbon and nitrogen isotopes (δ 13C and δ 15N). Samples were collected during spring and summer (2003-2005) from a total of 13 stations with different ice conditions, abundances of ice algae, and phytoplankton bloom phases. δ 13C signatures were different in organic matter of phytoplankton (mean -24.3‰) and ice algal origin (mean -20.0‰). Stable carbon isotope compositions showed that most of the energy assimilated by zooplankton originated from pelagic primary production, but at times ice algae also contributed to zooplankton diets. Trophic level (TL) estimates of copepods ( Calanus glacialis and Calanus hyperboreus) and krill ( Thysanoessa inermis and Thysanoessa longicaudata), calculated based on δ 15N values, varied among stations from 1.3 to 2.7 and from 1.5 to 3.1, for respective taxa. TL in C. glacialis was significantly and inversely related to the depth-integrated phytoplankton chlorophyll a concentration. A similar trend, although weaker, also was observed for the other species. This relationship indicates that copepods graze primarily on the abundant autotrophic biomass during the peak bloom phase. At stations with lower chlorophyll a concentration, the TL of Calanus spp. was 1.0 higher, indicating omnivory outside the peak bloom phase in response to changed food availability. The majority of organic matter

  11. Adaptation of an abundant Roseobacter RCA organism to pelagic systems revealed by genomic and transcriptomic analyses.

    PubMed

    Voget, Sonja; Wemheuer, Bernd; Brinkhoff, Thorsten; Vollmers, John; Dietrich, Sascha; Giebel, Helge-Ansgar; Beardsley, Christine; Sardemann, Carla; Bakenhus, Insa; Billerbeck, Sara; Daniel, Rolf; Simon, Meinhard

    2015-02-01

    The RCA (Roseobacter clade affiliated) cluster, with an internal 16S rRNA gene sequence similarity of >98%, is the largest cluster of the marine Roseobacter clade and most abundant in temperate to (sub)polar oceans, constituting up to 35% of total bacterioplankton. The genome analysis of the first described species of the RCA cluster, Planktomarina temperata RCA23, revealed that this phylogenetic lineage is deeply branching within the Roseobacter clade. It shares not >65.7% of homologous genes with any other organism of this clade. The genome is the smallest of all closed genomes of the Roseobacter clade, exhibits various features of genome streamlining and encompasses genes for aerobic anoxygenic photosynthesis (AAP) and CO oxidation. In order to assess the biogeochemical significance of the RCA cluster we investigated a phytoplankton spring bloom in the North Sea. This cluster constituted 5.1% of the total, but 10-31% (mean 18.5%) of the active bacterioplankton. A metatranscriptomic analysis showed that the genome of P. temperata RCA23 was transcribed to 94% in the bloom with some variations during day and night. The genome of P. temperata RCA23 was also retrieved to 84% from metagenomic data sets from a Norwegian fjord and to 82% from stations of the Global Ocean Sampling expedition in the northwestern Atlantic. In this region, up to 6.5% of the total reads mapped on the genome of P. temperata RCA23. This abundant taxon appears to be a major player in ocean biogeochemistry. PMID:25083934

  12. Adaptation of an abundant Roseobacter RCA organism to pelagic systems revealed by genomic and transcriptomic analyses

    PubMed Central

    Voget, Sonja; Wemheuer, Bernd; Brinkhoff, Thorsten; Vollmers, John; Dietrich, Sascha; Giebel, Helge-Ansgar; Beardsley, Christine; Sardemann, Carla; Bakenhus, Insa; Billerbeck, Sara; Daniel, Rolf; Simon, Meinhard

    2015-01-01

    The RCA (Roseobacter clade affiliated) cluster, with an internal 16S rRNA gene sequence similarity of >98%, is the largest cluster of the marine Roseobacter clade and most abundant in temperate to (sub)polar oceans, constituting up to 35% of total bacterioplankton. The genome analysis of the first described species of the RCA cluster, Planktomarina temperata RCA23, revealed that this phylogenetic lineage is deeply branching within the Roseobacter clade. It shares not >65.7% of homologous genes with any other organism of this clade. The genome is the smallest of all closed genomes of the Roseobacter clade, exhibits various features of genome streamlining and encompasses genes for aerobic anoxygenic photosynthesis (AAP) and CO oxidation. In order to assess the biogeochemical significance of the RCA cluster we investigated a phytoplankton spring bloom in the North Sea. This cluster constituted 5.1% of the total, but 10–31% (mean 18.5%) of the active bacterioplankton. A metatranscriptomic analysis showed that the genome of P. temperata RCA23 was transcribed to 94% in the bloom with some variations during day and night. The genome of P. temperata RCA23 was also retrieved to 84% from metagenomic data sets from a Norwegian fjord and to 82% from stations of the Global Ocean Sampling expedition in the northwestern Atlantic. In this region, up to 6.5% of the total reads mapped on the genome of P. temperata RCA23. This abundant taxon appears to be a major player in ocean biogeochemistry. PMID:25083934

  13. Evolution of organic matter in Orgueil, Murchison and Renazzo during parent body aqueous alteration: In situ investigations

    NASA Astrophysics Data System (ADS)

    Le Guillou, Corentin; Bernard, Sylvain; Brearley, Adrian J.; Remusat, Laurent

    2014-04-01

    Chondrites accreted the oldest solid materials in the solar system including dust processed in the protoplanetary disk and diverse organic compounds. After accretion, asteroidal alteration may have impacted organic particles in various ways. To constrain these processes, we conducted a comprehensive study of organics disseminated within the matrices of the three carbonaceous chondrite falls, Renazzo (CR2), Murchison (CM2) and Orgueil (CI). By combining synchrotron-based STXM and TEM analyses on FIB sections of samples previously characterized by NanoSIMS, we investigated the influence of aqueous alteration on the morphology, isotopic signature, molecular structure, spatial distribution, and mineralogical environment of the organic matter within the matrices. Two different populations of materials are distinguishable: sub-micrometric individual grains, likely dominated by insoluble compounds and diffuse organic matter, finely interspersed within phyllosilicates and/or (amorphous) nanocarbonates at the nanometer scale. We suggest that this latter component, which is depleted in aromatics and enriched in carboxylic functional groups, may be dominated by soluble compounds. Organic matter in Renazzo (CR) mainly consists of chemically-homogeneous individual grains surrounded by amorphous and nanocrystalline phyllosilicates. Evidence of connectivity between organic grains and fractures indicates that redistribution has occurred: some areas containing diffuse organic matter can be observed. This diffuse organic component is more abundant in Murchison (CM) and Orgueil (CI). This is interpreted as resulting from fluid transport at the micrometer scale and encapsulation within recrystallized alteration phases. In contrast to Renazzo, organic grains in Murchison and Orgueil display strong chemical heterogeneities, likely related to chemical evolution during aqueous alteration. The observations suggest that the altering fluid was a brine with elevated concentrations of both

  14. Key soil functional properties affected by soil organic matter - evidence from published literature

    NASA Astrophysics Data System (ADS)

    Murphy, Brian

    2015-07-01

    The effect of varying the amount of soil organic matter on a range of individual soil properties was investigated using a literature search of published information largely from Australia, but also included relevant information from overseas. Based on published pedotransfer functions, soil organic matter was shown to increase plant available water by 2 to 3 mm per 10 cm for each 1% increase in soil organic carbon, with the largest increases being associated with sandy soils. Aggregate stability increased with increasing soil organic carbon, with aggregate stability decreasing rapidly when soil organic carbon fell below 1.2 to 1.5 5%. Soil compactibility, friability and soil erodibility were favourably improved by increasing the levels of soil organic carbon. Nutrient cycling was a major function of soil organic matter. Substantial amounts of N, P and S become available to plants when the soil organic matter is mineralised. Soil organic matter also provides a food source for the microorganisms involved in the nutrient cycling of N, P, S and K. In soils with lower clay contents, and less active clays such as kaolinites, soil organic matter can supply a significant amount of the cation exchange capacity and buffering capacity against acidification. Soil organic matter can have a cation exchange capacity of 172 to 297 cmol(+)/kg. As the cation exchange capacity of soil organic matter varies with pH, the effectiveness of soil organic matter to contribute to cation exchange capacity below pH 5.5 is often minimal. Overall soil organic matter has the potential to affect a range of functional soil properties.

  15. Biogeochemical and hydrographic controls on chromophoric dissolved organic matter distribution in the Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Swan, Chantal M.; Siegel, David A.; Nelson, Norman B.; Carlson, Craig A.; Nasir, Elora

    2009-12-01

    Recent in situ observations of chromophoric dissolved organic material (CDOM) in the Pacific Ocean reveal the biogeochemical controls on CDOM and indicate predictive potential for open-ocean CDOM in diagnosing particulate organic matter (POM) remineralization rates within ocean basins. Relationships between CDOM and concentrations of dissolved oxygen, nutrients and inorganic carbon in the subthermocline waters of the Pacific reflect the relative influences of water mass ventilation and water-column oxidative remineralization. Apparent in situ oxygen utilization (AOU) accounts for 86% and 61% of variance in CDOM abundance, respectively, in Antarctic Intermediate Water and North Pacific Intermediate Water. In the deep waters of the Pacific below the zone of remineralization, AOU explains 26% of CDOM variability. The AOU-CDOM relationship results from competing biogeochemical and advective processes within the ocean interior. Dissolved organic carbon (DOC) is not statistically linked to the CDOM or AOU distributions, indicating that the majority of CDOM production occurs during the remineralization of sinking POM and thus potentially provides key information about carbon export. Once formed in the ocean interior, CDOM is relatively stable until it reaches the surface ocean where it is destroyed by solar bleaching. Susceptibility to bleaching confers an additional tracer-like quality for CDOM in water masses with active convection, such as mode waters that appear as subsurface CDOM minima. In the surface ocean, atypically low CDOM abundance highlights a region of unusually extreme oligotrophy: the subtropical South Pacific gyre. For these hyper-oligotrophic waters, the present CDOM observations are consistent with analysis of in situ radiometric observations of light attenuation and reflectance, demonstrating the accuracy of the CDOM spectrophotometric observations. Overall, we illustrate how CDOM abundance in the ocean interior can potentially diagnose rates of

  16. Soil organic matter on citrus plantation in Eastern Spain

    NASA Astrophysics Data System (ADS)

    Cerdà, Artemi; Pereira, Paulo; Novara, Agata; Prosdocimi, Massimo

    2015-04-01

    Citrus plantations in Eastern Spain are the main crop and Valencia region is the largest world exporter. The traditional plantation are located on flood irrigated areas and the new plantation are located on slopes were drip irrigation is the source of the wetting. It has been demonstrate that the citrus plantations contribute to high erosion rates on slopes (Cerdà et al., 2009b) as it is usual on agriculture land (Cerdà et al., 2009a), but when organic farming is present the soil erosion is much lower (Cerdà and Jurgensen, 2008; Cerdà et al., 2009; Cerdà and Jurgensen, 2011). This is a worldwide phenomenon (Wu et al., 2007; Wu et al., 2011; Xu et al., 2010; Xu et al., 2012a; Xu et al., 2012b), which are a key factor of the high erosion rates in rural areas (García Orenes et al., 2009: García Orenes et al., 20010; García Orenes et al., 2012; Haregewyn et al., 2013; Zhao et al., 2013). The key factor of the contrasted response of soils to the rain in citrus is the organic matter cover. This is why the Soil Erosion and Degradation Research Team developed a survey to determine the soil erosion rates on citrus orchards under different managements. A hundred of samples were collected in a citrus plantation on slope under conventional management (Chemical management), one on organic farming, one on traditional flood irrigated organic farming and one on traditional chemical flooding farm. The organic farming soils were treated with 10000 Kg ha-1 of manure yearly. The results show that the mean soil organic matter content was 1.24 %, 3.54%, 5,43% and 2.1% respectively, which show a clear impact of organic farming in the recovery of the soil organic matter. meanwhile the on the slopes and the flood-irrigated soils are Acknowledgements The research projects GL2008-02879/BTE, LEDDRA 243857 and PREVENTING AND REMEDIATING DEGRADATION OF SOILS IN EUROPE THROUGH LAND CARE (RECARE)FP7- ENV-2013- supported this research. References Cerdà, A., Flanagan, D.C., le Bissonnais

  17. Effects of the fungicide pyrimethanil on biofilm and organic matter processing in outdoor lentic mesocosms.

    PubMed

    Abelho, Manuela; Martins, Tiago Fortunato; Shinn, Cândida; Moreira-Santos, Matilde; Ribeiro, Rui

    2016-01-01

    The effect of the fungicide pyrimethanil (0.7 mg L(−1)) on biofilm development and alder leaf litter decomposition in aquatic ecosystems was assessed in outdoor lentic mesocosms immediately and 274 days after pyrimethanil application. Pyrimethanil decreased ergosterol concentrations (an indicator of fungal biomass) and the abundance and richness of the macroinvertebrate community associated with decomposing leaves. However, because neither fungi nor macroinvertebrates were main factors contributing to decomposition in this particular system, organic matter processing rates were not affected. After 274 days, pyrimethanil concentration in the water column was ≤0.004 mg L(−1) but richness, biomass and composition of the invertebrate community associated with decomposing leaf-litter still showed the effect. The comparison of ergosterol (a molecule existing on both algae and fungal cell membranes), with chlorophyll (an indicator of algal biomass) associated with biofilm suggests that pyrimethanil may decrease fungal biomass and alter the relative abundance of algae and fungi on biofilm developing in control- and treated-mesocosms. PMID:26496930

  18. The flux of organic matter through a peatland ecosystem - evidence from thermogravimetric analysis

    NASA Astrophysics Data System (ADS)

    Worrall, Fred; Moody, Catherine; Clay, Gareth

    2016-04-01

    Carbon budgets of peatlands are now common and studies have considered nitrogen, oxygen and energy budgets, but no study has considered the whole composition of the organic matter as it transfers through and into a peatland. Organic matter samples were taken from each organic matter reservoir found in and each fluvial flux from a peatland and analysed the samples by thermogravimetric analysis. The samples analysed were: aboveground, belowground, heather, mosses and sedges, litter layer, a peat core, and monthly samples of particulate and dissolved organic matter. All organic matter samples were taken from a 100% peat catchment within Moor House National Nature Reserve in the North Pennines, UK, and collected samples were compared to standards of lignin, cellulose, humic acid and plant protein. Results showed that the thermogravimetric trace of the sampled organic matter were distinctive with the DOM traces being marked out by very low thermal stability relative other organic matter types. The peat profile shows a significant trend with depth from vegetation- to lignin-like composition. When all traces are weighted according to the observed dry matter and carbon budgets for the catchment then it is possible to judge what has been lost in the transition through and into the ecosystem. By plotting this "lost" trace it possible to assess its composition which is either 97% cellulose and 3% humic acid or 92% and 8% lignin. This has important implications for what controls the organic matter balance of peatlands and it suggests that the oxidation state (OR) of peatland is less than 1.

  19. Vehicular emissions of organic particulate matter in Sao Paulo, Brazil

    NASA Astrophysics Data System (ADS)

    Oyama, B. S.; Andrade, M. F.; Herckes, P.; Dusek, U.; Röckmann, T.; Holzinger, R.

    2015-12-01

    Vehicular emissions have a strong impact on air pollution in big cities. Many factors affect these emissions: type of vehicle, type of fuel, cruising velocity, and brake use. This study focused on emissions of organic compounds by Light (LDV) and Heavy (HDV) duty vehicle exhaust. The study was performed in the city of Sao Paulo, Brazil, where vehicles run on different fuels: gasoline with 25 % ethanol (called gasohol), hydrated ethanol, and diesel (with 5 % of biodiesel). The vehicular emissions are an important source of pollutants and the principal contribution to fine particulate matter (smaller than 2.5 μm, PM2.5) in Sao Paulo. The experiments were performed in two tunnels: Janio Quadros (TJQ) where 99 % of the vehicles are LDV, and Rodoanel Mario Covas (TRA) where up to 30 % of the fleet was HDV. The PM2.5 samples were collected on quartz filters in May and July 2011 at TJQ and TRA, respectively, using two samplers operating in parallel. The samples were analyzed by Thermal-Desorption Proton-Transfer-Reaction Mass-Spectrometry (TD-PTR-MS), and by Thermal-Optical Transmittance (TOT). The organic aerosol (OA) desorbed at TD-PTR-MS represented around 30 % of the OA estimated by the TOT method, mainly due to the different desorption temperatures, with a maximum of 870 and 350 °C for TOT and TD-PTR-MS, respectively. Average emission factors (EF) organic aerosol (OA) and organic carbon (OC) were calculated for HDV and LDV fleet. We found that HDV emitted more OA and OC than LDV, and that OC emissions represented 36 and 43 % of total PM2.5 emissions from LDV and HDV, respectively. More than 700 ions were identified by TD-PTR-MS and the EF profiles obtained from HDV and LDV exhibited distinct features. Nitrogen-containing compounds measured in the desorbed material up to 350 °C contributed around 20 % to the EF values for both types of vehicles, possibly associated with incomplete fuel burning. Additionally, 70 % of the organic compounds measured from the aerosol

  20. Chemical composition of dissolved organic matter draining permafrost soils

    NASA Astrophysics Data System (ADS)

    Ward, Collin P.; Cory, Rose M.

    2015-10-01

    Northern circumpolar permafrost soils contain roughly twice the amount of carbon stored in the atmosphere today, but the majority of this soil organic carbon is perennially frozen. Climate warming in the arctic is thawing permafrost soils and mobilizing previously frozen dissolved organic matter (DOM) from deeper soil layers to nearby surface waters. Previous studies have reported that ancient DOM draining deeper layers of permafrost soils was more susceptible to degradation by aquatic bacteria compared to modern DOM draining the shallow active layer of permafrost soils, and have suggested that DOM chemical composition may be an important control for the lability of DOM to bacterial degradation. However, the compositional features that distinguish DOM drained from different depths in permafrost soils are poorly characterized. Thus, the objective of this study was to characterize the chemical composition of DOM drained from different depths in permafrost soils, and relate these compositional differences to its susceptibility to biological degradation. DOM was leached from the shallow organic mat and the deeper permafrost layer of soils within the Imnavait Creek watershed on the North Slope of Alaska. DOM draining both soil layers was characterized in triplicate by coupling ultra-high resolution mass spectrometry, 13C solid-state NMR, and optical spectroscopy methods with multi-variate statistical analyses. Reproducibility of replicate mass spectra was high, and compositional differences resulting from interfering species or isolation effects were significantly smaller than differences between DOM drained from each soil layer. All analyses indicated that DOM leached from the shallower organic mat contained higher molecular weight, more oxidized, and more unsaturated aromatic species compared to DOM leached from the deeper permafrost layer. Bacterial production rates and bacterial efficiencies were significantly higher for permafrost compared to organic mat DOM

  1. Do aggregate stability and soil organic matter content increase following organic inputs?

    NASA Astrophysics Data System (ADS)

    Lehtinen, Taru; Gísladóttir, Guðrún; van Leeuwen, Jeroen P.; Bloem, Jaap; Steffens, Markus; Vala Ragnarsdóttir, Kristin

    2014-05-01

    Agriculture is facing several challenges such as loss of soil organic matter (SOM); thus, sustainable farming management practices are needed. Organic farming is growing as an alternative to conventional farming; in Iceland approximately 1% and in Austria 16% of utilized agricultural area is under organic farming practice. We analyzed the effect of different farming practices (organic, and conventional) on soil physicochemical and microbiological properties in grassland soils in Iceland and cropland soils in Austria. Organic farms differed from conventional farms by absence of chemical fertilizers and pesticide use. At these farms, we investigated soil physicochemical (e.g. soil texture, pH, CAL-extractable P and K) and microbiological properties (fungal and bacterial biomass and activity). The effects of farming practices on soil macroaggregate stability and SOM quantity, quality and distribution between different fractions were studied following a density fractionation. In Iceland, we sampled six grassland sites on Brown (BA) and Histic (HA) Andosols; two sites on extensively managed grasslands, two sites under organic and two sites under conventional farming practice. In Austria, we sampled four cropland sites on Haplic Chernozems; two sites under organic and two sites under conventional farming practice. We found significantly higher macroaggregate stability in the organic compared to the conventional grasslands in Iceland. In contrast, slightly higher macroaggregation in conventional compared to the organic farming practice was found in croplands in Austria, although the difference was not significant. Macroaggregates were positively correlated with fungal biomass in Iceland, and with Feo and fungal activity in Austria. In Austria, SOM content and nutrient status (except for lower CAL-extractable P at one site) were similar between organic and conventional farms. Our results show that the organic inputs may have enhanced macroaggregation in organic farming

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

    NASA Astrophysics Data System (ADS)

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

    2010-11-01

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

  3. Vertical transport of particulate organic matter regulated by fjord topography

    NASA Astrophysics Data System (ADS)

    Erlandsson, Carina P.

    2008-03-01

    The deepwater in many areas with restricted water exchange suffers from low oxygen concentrations due to degradation of organic matter. The objective of this study was to investigate how topography may influence the vertical transport, Fc, of particulate organic matter, POM, to the deepwater. A conceptual/analytical model for Fc was developed covering the combination of the three possible sources of POM/nutrients to an enclosed area; the coastal water, local supply, and nutrient rich local deepwater. The mathematical formulation of the conceptual model includes several factors describing to which degree various physical mechanisms in the fjord are influencing Fc. The model consists of submodels for the different sources of POM/nutrients. A one-dimensional process oriented numerical model was used to test the conceptual model. Restricted water exchange with the coastal water led to decreased import of POM and thereby decreased vertical transport, Fc, of coastal POM. The contribution to Fc by local input of nutrients to the surface layer was described by a function of the residence time of the water above sill level, Tsw and the time Tp it takes for POM produced in the surface layer to settle below sill level. The recirculation of POM produced due to basin water renewals was shown to be a function of several factors: The relation between the depth of photic zone, Hp and the sill depth, Ht, the vertical velocity of the rising nutrient rich water mass versus the settling velocity of POM, etc. The results based on the conceptual submodels agreed well with the results from the process oriented numerical model. Methods to identify the trophic state of coastal waters, and also simple models to calculate the effect of a local point source, can be found in literature. However, using the model developed in this paper the effects of nutrient enrichment from different sources can be quantified in a simple and more efficient way than earlier. The model can thus be used to

  4. Heavy metals fractionation and organic matter mineralisation in contaminated calcareous soil amended with organic materials.

    PubMed

    Clemente, Rafael; Escolar, Angeles; Bernal, M Pilar

    2006-10-01

    Degradation of organic matter (OM) from organic amendments used in the remediation of metal contaminated soils leads to changes in soil chemical properties shortly after their addition, which may affect the soil metal distribution. The effects of two differing organic amendments on OM mineralisation and fractionation of heavy metals in a contaminated soil were investigated in an incubation experiment. The treatments were: control unamended soil, soil amended with fresh cow manure, and soil amended with a compost having a high maturity degree. The soil used was characteristic of the mining area at La Unión (Murcia, Spain) with 28% CaCO(3) and sandy-loam texture (pH 7.7; 2602 mg kg(-1)Zn; 1572 mg kg(-1)Pb). Manure and compost C-mineralisation after 56 days (24% and 3.8%, respectively) were below values reported previously for uncontaminated soils. Both amendments favoured Zn and Pb fixation, particularly the manure. Mn solubility increased at the beginning of the experiment due to a pH effect, and only Cu solubility increased through organic matter chelation in both amended soils.

  5. The Isiokpo oil-pipeline leakage: total organic carbon/organic matter contents of affected soils.

    PubMed

    Osuji, Leo C; Adesiyan, Samuel O

    2005-08-01

    The environmental impact of the 1997 leakage of the high-pressure crude-oil pipeline at Isiokpo in the Niger Delta in the southeast of Nigeria was evaluated, with particular reference to total-organic-carbon (TOC) and total-organic-matter (TOM) contents of soils within the vicinity of the oil spillage. The soils, taken from depths of 0-15 cm (surface) and 15-30 cm (subsurface), were found to be more acidic (pH 4.2-5.6) than the unpolluted soils, with a high average moisture content of 6.8%. The extractable hydrocarbon content ranged from 2.71-3.48 mg/kg, indicating hydrocarbon contamination. However, contrary to expectation, the TOC and TOM contents of the polluted soils did not show any significant increase in concentration, supposedly due to natural rehabilitation of the affected mat layer of soils. Thus, notwithstanding the possible proliferation of heterotrophic organisms by the presence of the added petroleum hydrocarbons, environmental conditions such as weathering and climatic predispositions, as well as physico-chemical parameters such as pH, moisture content, and temperature must have encumbered the carbon-mineralizing capacity of the heterotrophs, thereby reducing the turnover of carbon and the decomposition of organic matter. The restrictions by high moisture content might not come directly from H(2)O itself, but are probably a consequence of hindered soil ventilation, which reduces O(2) supply and gaseous diffusion, conditions that might have been substantially aggravated by the added petroleum hydrocarbons.

  6. Electron Shuttling Capacity of Solid-Phase Organic Matter in Forest Soils

    NASA Astrophysics Data System (ADS)

    Patel, A.; Zhao, Q.; Yang, Y.

    2015-12-01

    Soil organic matter, as an electron shuttle, plays an important role in regulating the biogeochemical cycles of metals, especially the redox reactions for iron. Microorganisms can reduce soil organic matter under anaerobic conditions, and biotically-reduced soil organic matter can abiotically donate electrons to ferric oxides. Such soil organic matter-mediated electron transport can facilitate the interactions between microorganisms and insoluble terminal electron acceptors, i.e. iron minerals. Most previous studies have been focused on the electron shuttling processes through dissolved soil organic matter, and scant information is available for solid-phase soil organic matter. In this study, we aim to quantify the electron accepting capacity for solid-phase organic matter in soils collected from four different forests in the United States, including Truckee (CA), Little Valley (NV), Howland (ME) and Hart (MI). We used Shewanella oneidensisMR-1 to biotically reduce soil slurries, and then quantified the electrons transferred to solid-phase and solution-phase organic matter by reacting them with Fe(III)-nitrilotriacetic acid (Fe(III)-NTA). The generation of Fe(II) was measured by a ferrozine assay to calculate the electron accepting capacity of soil organic matter. Our preliminary results showed that the Truckee soil organic matter can accept 0.51±0.07 mM e-/mol carbon. We will measure the electron accepting capacity for four different soils and correlate them to the physicochemical properties of soils. Potential results will provide information about the electron accepting capacity of solid-phase soil organic matter and its governing factors, with broad implication on the coupled biogeochemical cycles of carbon and iron.

  7. Response of Benthic Foraminifera to Organic Matter Quantity and Quality and Bioavailable Concentrations of Metals in Aveiro Lagoon (Portugal)

    PubMed Central

    Martins, Maria Virgínia Alves; Silva, Frederico; Laut, Lazaro L. M.; Frontalini, Fabrizio; Clemente, Iara M. M. M.; Miranda, Paulo; Figueira, Rubens; Sousa, Silvia H. M.; Dias, João M. Alveirinho

    2015-01-01

    This work analyses the distribution of living benthic foraminiferal assemblages of surface sediments in different intertidal areas of Ria de Aveiro (Portugal), a polihaline and anthropized coastal lagoon. The relationships among foraminiferal assemblages in association with environmental parameters (temperature, salinity, Eh and pH), grain size, the quantity and quality of organic matter (enrichment in carbohydrates, proteins and lipids), pollution caused by metals, and mineralogical data are studied in an attempt to identify indicators of adaptability to environmental stress. In particular, concentrations of selected metals in the surficial sediment are investigated to assess environmental pollution levels that are further synthetically parameterised by the Pollution Load Index (PLI). The PLI variations allowed the identification of five main polluted areas. Concentrations of metals were also analysed in three extracted phases to evaluate their possible mobility, bioavailability and toxicity in the surficial sediment. Polluted sediment in the form of both organic matter and metals can be found in the most confined zones. Whereas enrichment in organic matter and related biopolymers causes an increase in foraminifera density, pollution by metals leads to a decline in foraminiferal abundance and diversity in those zones. The first situation may be justified by the existence of opportunistic species (with high reproduction rate) that can live in low oxic conditions. The second is explained by the sensitivity of some species to pressure caused by metals. The quality of the organic matter found in these places and the option of a different food source should also explain the tolerance of several species to pollution caused by metals, despite their low reproductive rate in the most polluted areas. In this study, species that are sensitive and tolerant to organic matter and metal enrichment are identified, as is the differential sensitivity/tolerance of some species to

  8. Response of benthic foraminifera to organic matter quantity and quality and bioavailable concentrations of metals in Aveiro Lagoon (Portugal).

    PubMed

    Martins, Maria Virgínia Alves; Silva, Frederico; Laut, Lazaro L M; Frontalini, Fabrizio; Clemente, Iara M M M; Miranda, Paulo; Figueira, Rubens; Sousa, Silvia H M; Dias, João M Alveirinho

    2015-01-01

    This work analyses the distribution of living benthic foraminiferal assemblages of surface sediments in different intertidal areas of Ria de Aveiro (Portugal), a polihaline and anthropized coastal lagoon. The relationships among foraminiferal assemblages in association with environmental parameters (temperature, salinity, Eh and pH), grain size, the quantity and quality of organic matter (enrichment in carbohydrates, proteins and lipids), pollution caused by metals, and mineralogical data are studied in an attempt to identify indicators of adaptability to environmental stress. In particular, concentrations of selected metals in the surficial sediment are investigated to assess environmental pollution levels that are further synthetically parameterised by the Pollution Load Index (PLI). The PLI variations allowed the identification of five main polluted areas. Concentrations of metals were also analysed in three extracted phases to evaluate their possible mobility, bioavailability and toxicity in the surficial sediment. Polluted sediment in the form of both organic matter and metals can be found in the most confined zones. Whereas enrichment in organic matter and related biopolymers causes an increase in foraminifera density, pollution by metals leads to a decline in foraminiferal abundance and diversity in those zones. The first situation may be justified by the existence of opportunistic species (with high reproduction rate) that can live in low oxic conditions. The second is explained by the sensitivity of some species to pressure caused by metals. The quality of the organic matter found in these places and the option of a different food source should also explain the tolerance of several species to pollution caused by metals, despite their low reproductive rate in the most polluted areas. In this study, species that are sensitive and tolerant to organic matter and metal enrichment are identified, as is the differential sensitivity/tolerance of some species to

  9. Response of benthic foraminifera to organic matter quantity and quality and bioavailable concentrations of metals in Aveiro Lagoon (Portugal).

    PubMed

    Martins, Maria Virgínia Alves; Silva, Frederico; Laut, Lazaro L M; Frontalini, Fabrizio; Clemente, Iara M M M; Miranda, Paulo; Figueira, Rubens; Sousa, Silvia H M; Dias, João M Alveirinho

    2015-01-01

    This work analyses the distribution of living benthic foraminiferal assemblages of surface sediments in different intertidal areas of Ria de Aveiro (Portugal), a polihaline and anthropized coastal lagoon. The relationships among foraminiferal assemblages in association with environmental parameters (temperature, salinity, Eh and pH), grain size, the quantity and quality of organic matter (enrichment in carbohydrates, proteins and lipids), pollution caused by metals, and mineralogical data are studied in an attempt to identify indicators of adaptability to environmental stress. In particular, concentrations of selected metals in the surficial sediment are investigated to assess environmental pollution levels that are further synthetically parameterised by the Pollution Load Index (PLI). The PLI variations allowed the identification of five main polluted areas. Concentrations of metals were also analysed in three extracted phases to evaluate their possible mobility, bioavailability and toxicity in the surficial sediment. Polluted sediment in the form of both organic matter and metals can be found in the most confined zones. Whereas enrichment in organic matter and related biopolymers causes an increase in foraminifera density, pollution by metals leads to a decline in foraminiferal abundance and diversity in those zones. The first situation may be justified by the existence of opportunistic species (with high reproduction rate) that can live in low oxic conditions. The second is explained by the sensitivity of some species to pressure caused by metals. The quality of the organic matter found in these places and the option of a different food source should also explain the tolerance of several species to pollution caused by metals, despite their low reproductive rate in the most polluted areas. In this study, species that are sensitive and tolerant to organic matter and metal enrichment are identified, as is the differential sensitivity/tolerance of some species to

  10. Effect of temperature on the decomposition rate of labile and stable organic matter in an agrochernozem

    NASA Astrophysics Data System (ADS)

    Larionova, A. A.; Kvitkina, A. K.; Yevdokimov, I. V.; Bykhovets, S. S.; Stulin, A. F.

    2014-05-01

    An hypothesis about the different temperature dependences of the decomposition of the labile and stable organic carbon pools has been tested using an agrochernozem sampled from an experimental plot of 42-year-old continuous corn in Voronezh oblast. The partitioning of the CO2 loss during the decomposition of the labile and stable soil organic matter (SOM) at 2, 12, and 22°C in a long-term incubation experiment was performed using the method of 13C natural abundance by C3-C4 transition. On the basis of the determined decomposition constants, the SOM pools have been arranged in an order according to their increasing stability: plant residues < new (C4) SOM < old (C3) SOM. The tested hypothesis has been found valid only for a limited temperature interval. The temperature coefficient Q 10 increases in the stability order from 1.2 to 4.3 in the interval of 12-22°C. At low temperatures (2-12°C), the values of Q 10 insignificantly vary among the SOM pools and lie in the range of 2.2-2.8. Along with the decomposition constants of the SOM, the new-to-old carbon ratio in the CO2 efflux from the soil and the magnitude of the negative priming effect for the old SOM caused by the input of new organic matter depend on the temperature. In the soil under continuous corn fertilized with NPK, the increased decomposition of C3 SOM is observed compared to the unfertilized control; the temperature dependences of the SOM decomposition are similar in both agrochernozem treatments.

  11. Effects of Natural Organic Matter on Stability, Transport and Deposition of Engineered Nano-particles in Porous Media

    EPA Science Inventory

    The interaction of nano-particles and organic substances, like natural organic matter, could have significant influence on the fate, transport and bioavailability of toxic substances. Natural organic matter (NOM) is a mixture of chemically complex polyelectrolytes with varying m...

  12. Geochemical imprint of depositional conditions on organic matter in laminated-Bioturbated interbeds from fine-grained marine sequences

    USGS Publications Warehouse

    Pratt, L.M.; Claypool, G.E.; King, J.D.

    1986-01-01

    Laminated organic-rich shales are interbedded at a scale of centimeters to a few meters with bioturbated organic-poor mudstones or limestones in some fine-grained marine sequences. We have analyzed the organic matter in pairs of laminated/bioturbated interbeds from Cretaceous and Devonian rocks deposited in epicontinental and oceanic settings for the purpose of studying the influence of depositional and early diagenetic environment on the organic geochemical properties of marine shales. Results of these analyses indicate that for rocks that are still in a diagenetic stage of thermal alteration, the relative abundance of biomarker compounds and specific biomarker indices can be useful indicators of depositional and early diagenetic conditions. Pristane/phytane ratios are generally highest for laminated rocks from epicontinental basins and appear to reflect the input of isoprenoid precursors more than oxygenated versus anoxic depositional conditions. The thermally immature laminated rocks are characterized by relatively high contents of 17??(H), 21??(H)-hopanes, hopenes, sterenes and diasterenes, and by strong predominance of the 22R over 22S homohopane isomers. Thermally immature bioturbated samples are characterized by absence of the ??,??-hopanes, by low contents of both saturated and unsaturated polycyclic hydrocarbons, and by slight or no predominance of the 22R over 22S homohopane isomers. There are less obvious compositional differences between the saturated hydrocarbons in the laminated and bioturbated units from the thermally mature sequences. For both the thermally mature and immature laminated samples, the degree of isomerization at the 22C position for hopanes and at the 20C position for steranes is generally consistent with the degree of thermal maturity interpreted from other properties of the organic matter. The bioturbated samples, however, exhibit inconsistent and anomalously high degrees of isomerization for the homohopanes, resulting either from

  13. Coupled Ocean-Atmosphere Loss of Refractory Marine Dissolved Organic Matter

    NASA Astrophysics Data System (ADS)

    Kieber, D. J.; Keene, W. C.; Frossard, A. A.; Long, M. S.; Russell, L. M.; Maben, J. R.; Kinsey, J. D.; Tyssebotn, I. M.; Quinn, P.; Bates, T. S.

    2013-12-01

    Marine aerosol produced in the oceans from bursting bubbles and breaking waves is number dominated by submicron aerosol that are highly enriched in marine organic matter relative to seawater. Recent studies suggest that these organic-rich, submicron aerosol have a major impact on tropospheric chemistry and climate. It has been assumed this marine-derived aerosol organic matter is of recent origin stemming from biological activity in the photic zone. However, we deployed a marine aerosol generator on a recent cruise in the Sargasso Sea with seawater collected from 2500 m and showed that the aerosol generated from this seawater was enriched with organic matter to the same level as observed in surface Sargasso seawater, implying that the marine organic matter flux from the oceans into atmospheric aerosol is partly due to marine organic matter not of recent origin. We propose that marine aerosol production and subsequent physical and photochemical atmospheric evolution is the main process whereby old, refractory organic matter is removed from the oceans, thereby closing the carbon budget in the oceans and solving a long-standing conundrum regarding the removal mechanism for this organic matter in the sea. The implications of this study for couplings in the ocean-atmosphere cycling of organic matter will be discussed.

  14. Influence of soil organic matter composition on the partition of organic compounds

    USGS Publications Warehouse

    Rutherford, D.W.; Chiou, C.T.; Klle, D.E.

    1992-01-01

    The sorption at room temperature of benzene and carbon tetrachloride from water on three high-organic-content soils (muck, peat, and extracted peat) and on cellulose was determined in order to evaluate the effect of sorbent polarity on the solute partition coefficients. The isotherms are highly linear for both solutes on all the organic matter samples, which is consistent with a partition model. For both solutes, the extracted peat shows the greatest sorption capacity while the cellulose shows the lowest capacity; the difference correlates with the polar-to-nonpolar group ratio [(O + N)/C] of the sorbent samples. The relative increase of solute partition coefficient (Kom) with a decrease of sample polar content is similar for both solutes, and the limiting sorption capacity on a given organic matter sample is comparable between the solutes. This observation suggests that one can estimate the polarity effect of a sample of soil organic matter (SOM) on Kom of various nonpolar solutes by determining the partition coefficient of single nonpolar solute when compositional analysis of the SOM is not available. The observed dependence of Kom on sample polarity is used to account for the variation of Kom values of individual compounds on different soils that results from change in the polar group content of SOM. On the assumption that the carbon content of SOM in "ordinary soils" is 53-63%, the calculated variation of Kom is a factor of ???3. This value is in agreement with the limit of variation of most Kom data with soils of relatively high SOM contents.

  15. The effects of organic matter-mineral interactions and organic matter chemistry on diuron sorption across a diverse range of soils.

    PubMed

    Smernik, Ronald J; Kookana, Rai S

    2015-01-01

    Sorption of non-ionic organic compounds to soil is usually expressed as the carbon-normalized partition coefficient (KOC), because it is assumed that the main factor that influences the amount sorbed is the organic carbon content of the soil. However, KOC can vary by a factor of at least ten across a range of soils. We investigated two potential causes of variation in diuron KOC - organic matter-mineral interactions and organic matter chemistry - for a diverse set of 34 soils from Sri Lanka, representing a wide range of soil types. Treatment with hydrofluoric acid (HF-treatment) was used to concentrate soil organic matter. HF-treatment increased KOC for the majority of soils (average factor 2.4). We attribute this increase to the blocking of organic matter sorption sites in the whole soils by minerals. There was no significant correlation between KOC for the whole soils and KOC for the HF-treated soils, indicating that the importance of organic matter-mineral interactions varied greatly amongst these soils. There was as much variation in KOC across the HF-treated soils as there was across the whole soils, indicating that the nature of soil organic matter is also an important contributor to KOC variability. Organic matter chemistry, determined by solid-state (13)C nuclear magnetic resonance (NMR) spectroscopy, was correlated with KOC for the HF-treated soils. In particular, KOC increased with the aromatic C content (R=0.64, p=1×10(-6)), and decreased with O-alkyl C (R=-0.32, p=0.03) and alkyl C (R=-0.41, p=0.004) content.

  16. The effects of organic matter-mineral interactions and organic matter chemistry on diuron sorption across a diverse range of soils.

    PubMed

    Smernik, Ronald J; Kookana, Rai S

    2015-01-01

    Sorption of non-ionic organic compounds to soil is usually expressed as the carbon-normalized partition coefficient (KOC), because it is assumed that the main factor that influences the amount sorbed is the organic carbon content of the soil. However, KOC can vary by a factor of at least ten across a range of soils. We investigated two potential causes of variation in diuron KOC - organic matter-mineral interactions and organic matter chemistry - for a diverse set of 34 soils from Sri Lanka, representing a wide range of soil types. Treatment with hydrofluoric acid (HF-treatment) was used to concentrate soil organic matter. HF-treatment increased KOC for the majority of soils (average factor 2.4). We attribute this increase to the blocking of organic matter sorption sites in the whole soils by minerals. There was no significant correlation between KOC for the whole soils and KOC for the HF-treated soils, indicating that the importance of organic matter-mineral interactions varied greatly amongst these soils. There was as much variation in KOC across the HF-treated soils as there was across the whole soils, indicating that the nature of soil organic matter is also an important contributor to KOC variability. Organic matter chemistry, determined by solid-state (13)C nuclear magnetic resonance (NMR) spectroscopy, was correlated with KOC for the HF-treated soils. In particular, KOC increased with the aromatic C content (R=0.64, p=1×10(-6)), and decreased with O-alkyl C (R=-0.32, p=0.03) and alkyl C (R=-0.41, p=0.004) content. PMID:24972176

  17. 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.

  18. Sorptive stabilization of organic matter by amorphous Al hydroxide

    NASA Astrophysics Data System (ADS)

    Schneider, M. P. W.; Scheel, T.; Mikutta, R.; van Hees, P.; Kaiser, K.; Kalbitz, K.

    2010-03-01

    Amorphous Al hydroxides (am-Al(OH) 3) strongly sorb and by this means likely protect dissolved organic matter (OM) against microbial decay in soils. We carried out batch sorption experiments (pH 4.5; 40 mg organic C L -1) with OM extracted from organic horizons under a Norway spruce and a European beech forest. The stabilization of OM by sorption was analyzed by comparing the CO 2 mineralized during the incubation of sorbed and non-sorbed OM. The mineralization of OM was evaluated based in terms of (i) the availability of the am-Al(OH) 3, thus surface OM loadings, (ii) spectral properties of OM, and (iii) the presence of phosphate as a competitor for OM. This was done by varying the solid-to-solution ratio (SSR = 0.02-1.2 g L -1) during sorption. At low SSRs, hence limited am-Al(OH) 3 availability, only small portions of dissolved OM were sorbed; for OM from Oa horizons, the mineralization of the sorbed fraction exceeded that of the original dissolved OM. The likely reason is competition with phosphate for sorption sites favouring the formation of weak mineral-organic bindings and the surface accumulation of N-rich, less aromatic and less complex OM. This small fraction controlled the mineralization of sorbed OM even at higher SSRs. At higher SSRs, i.e., with am-Al(OH) 3 more available, competition of phosphate decreased and aromatic compounds were sorbed selectively, which resulted in pronounced resistance of sorbed OM against decay. The combined OC mineralization of sorbed and non-sorbed OM was 12-65% less than that of the original DOM. Sorbed OM contributed only little to the overall OC mineralization. Stabilization of OC increased in direct proportion to am-Al(OH) 3 availability, despite constant aromatic C (˜30%). The strong stabilization at higher mineral availability is primarily governed by strong Al-OM bonds formed under less competitive conditions. Due to these strong bonds and the resulting strong stabilization, the surface loading, a proxy for the

  19. Sustaining effect of soil warming on organic matter decomposition

    NASA Astrophysics Data System (ADS)

    Hou, Ruixing; Ouyang, Zhu; Dorodnikov, Maxim; Wilson, Glenn; Kuzyakov, Yakov

    2015-04-01

    Global warming affects various parts of carbon (C) cycle including acceleration of soil organic matter (SOM) decomposition with strong feedback to atmospheric CO2 concentration. Despite many soil warming studies showed changes of microbial community structure, only very few were focused on sustainability of soil warming on microbial activity associated with SOM decomposition. Two alternative hypotheses: 1) acclimation because of substrate exhaustion and 2) sustaining increase of microbial activity with accelerated decomposition of recalcitrant SOM pools were never proven under long term field conditions. This is especially important in the nowadays introduced no-till crop systems leading to redistribution of organic C at the soil surface, which is much susceptible to warming effects than the rest of the profile. We incubated soil samples from a four-year warming experiment with tillage (T) and no-tillage (NT) practices under three temperatures: 15, 21, and 27 °C, and related the evolved total CO2 efflux to changes of organic C pools. Warmed soils released significantly more CO2 than the control treatment (no warming) at each incubation temperature, and the largest differences were observed under 15 °C (26% increase). The difference in CO2 efflux from NT to T increase with temperature showing high vulnerability of C stored in NT to soil warming. The Q10 value reflecting the sensitivity of SOM decomposition to warming was lower for warmed than non-warmed soil indicating better acclimation of microbes or lower C availability during long term warming. The activity of three extracellular enzymes: β-glucosidase, chitinase, sulphatase, reflecting the response of C, N and S cycles to warming, were significantly higher under warming and especially under NT compared to two other respective treatments. The CO2 released during 2 months of incubation consisted of 85% from recalcitrant SOM and the remaining 15% from microbial biomass and extractable organic C based on the

  20. Macroinvertebrate and organic matter export from headwater tributaries of a Central Appalachian stream

    EPA Science Inventory

    Headwater streams export organisms and other materials to their receiving streams and macroinvertebrate drift can shape colonization dynamics in downstream reaches while providing food for downstream consumers. Spring-time macroinvertebrate drift and organic matter export was me...

  1. Sources and Distribution of Organic Matter in Sediments of the Louisiana Continental Shelf

    EPA Science Inventory

    Both riverine and marine sources of organic matter (OM) contribute to sediment organic pools, and either source can contribute significantly to sediment accumulation, burial, and remineralization rates on river dominated continental shelf systems. For the Louisiana continental sh...

  2. Tillage, crop rotation, and organic amendment effect on changes in soil organic matter.

    PubMed

    Rickman, R; Douglas, C; Albrecht, S; Berc, J

    2002-01-01

    Carbon sequestration in agricultural soils is controlled by the balance of added organic residues and microbial oxidation of both residues and native organic matter (OM) as moderated by management and tillage. The PC-based model CQESTR predicts decomposition of residues, organic amendments and soil OM, based on cropping practices. CQESTR uses RUSLE (Revised Universal Soil Loss Equation) crop rotation and management practice, crop production, and operation databases. These data are supplemented with residue nitrogen and soil OM, bulk density, and layer thickness. CQESTR was calibrated with soil carbon data from 70-year-long experiments at the Research Center at Pendleton, OR. The calibrated model provides estimates with a 95% confidence interval of 0.33% OM. Validation at 11 independent sites resulted in a matching of observed with calculated OM with a 95% confidence interval of 0.55% OM. A 12th site, with a history of severe erosion, provided a poor match.

  3. Variation in assimilable organic carbon formation during chlorination of Microcystis aeruginosa extracellular organic matter solutions.

    PubMed

    Sun, Xingbin; Yuan, Ting; Ni, Huishan; Li, Yanpeng; Hu, Yang

    2016-07-01

    This study investigated the chlorination of Microcystis aeruginosa extracellular organic matter (EOM) solutions under different conditions, to determine how the metabolites produced by these organisms affect water safety and the formation of assimilable organic carbon (AOC). The effects of chlorine dosages, coagulant dosage, reaction time and temperature on the formation of AOC were investigated during the disinfection of M.aeruginosa metabolite solutions. The concentration of AOC followed a decreasing and then increasing pattern with increasing temperature and reaction time. The concentration of AOC decreased and then increased with increasing chlorination dosage, followed by a slight decrease at the highest level of chlorination. However, the concentration of AOC decreased continuously with increasing coagulant dosage. The formation of AOC can be suppressed under appropriate conditions. In this study, chlorination at 4mg/L, combined with a coagulant dose of 40mg/L at 20°C over a reaction time of 12hr, produced the minimum AOC. PMID:27372113

  4. Photodegradation of dissolved organic matter in ice under solar irradiation.

    PubMed

    Xue, Shuang; Wang, Chao; Zhang, Zhaohong; Song, Youtao; Liu, Qiang

    2016-02-01

    The photodegradation behavior of dissolved organic matter (DOM) with different origins in ice under solar irradiation was investigated. Exposure to sunlight at 2.7 × 10(5) J m(-2) resulted in dissolved organic carbon (DOC) reductions of 22.1-36.5% in ice. The naturally occurring DOM had higher photodegradation potentials than the wastewater-derived DOM in ice. Ultraviolet (UV)-absorbing compounds in DOM, regardless of DOM origin, had much higher photodegradation potentials than gross DOC in ice. The susceptibility of UV-absorbing compounds with natural origin to sunlight exposure in ice was higher than those derived from wastewater. Trihalomethane (THM) precursors were more susceptible to photochemical reactions than gross DOC and haloacetic acid (HAA) precursors in ice. THM precursors in naturally occurring DOM were more photoreactive than those in wastewater-derived DOM in ice, while the photoreactivity of HAA precursors in ice was independent of DOM origin. In ice, the photoreactivity of humic-like fluorescent materials, regardless of DOM origin, was higher than that of gross DOC and protein-like fluorescent materials. DOC reductions caused by sunlight irradiation were found to be negatively correlated to DOC levels, and positively correlated to the aromaticity of DOM. The photodegradation of both wastewater-derived and naturally occurring DOM in ice was significantly facilitated at both acid and alkaline pH, as compared to neutral pH. The photodegradation of DOM in ice, regardless of the origin, was facilitated by nitrate ion [Formula: see text] , nitrite ion [Formula: see text] , ferric ion (Fe(3+)) and ferrous ion (Fe(2+)), and on the other hand, was inhibited by chloridion ion (Cl(-)) and copper ion (Cu(2+)).

  5. Natural organic matter fouling behaviors on superwetting nanofiltration membranes.

    PubMed

    Shan, Linglong; Fan, Hongwei; Guo, Hongxia; Ji, Shulan; Zhang, Guojun

    2016-04-15

    Nanofiltration has been widely recognized as a promising technology for the removal of micro-molecular organic components from natural water. Natural organic matter (NOM), a very important precursor of disinfection by-products, is currently considered as the major cause of membrane fouling. It is necessary to develop a membrane with both high NOM rejection and anti-NOM fouling properties. In this study, both superhydrophilic and superhydrophobic nanofiltration membranes for NOM removal have been fabricated. The fouling behavior of NOM on superwetting nanofiltration membranes has been extensively investigated by using humic acid (HA) as the model foulant. The extended Derjaguin-Landau-Verwey-Overbeek approach and nanoindentor scratch tests suggested that the superhydrophilic membrane had the strongest repulsion force to HA due to the highest positive total interaction energy (ΔG(TOT)) value and the lowest critical load. Excitation emission matrix analyses of natural water also indicated that the superhydrophilic membrane showed resistance to fouling by hydrophobic substances and therefore high removal thereof. Conversely, the superhydrophobic membrane showed resistance to fouling by hydrophilic substances and therefore high removal capacity. Long-term operation suggested that the superhydrophilic membrane had high stability due to its anti-NOM fouling capacity. Based on the different anti-fouling properties of the studied superwetting membranes, a combination of superhydrophilic and superhydrophobic membranes was examined to further improve the removal of both hydrophobic and hydrophilic pollutants. With a combination of superhydrophilic and superhydrophobic membranes, the NOM rejection (RUV254) and DOC removal rates (RDOC) could be increased to 83.6% and 73.3%, respectively. PMID:26900973

  6. Relating changes of organic matter composition of two German peats to climatic conditions during peat formation

    NASA Astrophysics Data System (ADS)

    Knicker, Heike; Nikolova, Radoslava; Rumpel, Cornelia; González-Vila, Francisco, J.; Drösler, Matthias

    2010-05-01

    less favorable climatic conditions during the formation of the alpine fen. The distribution of n-alkanes, n-fatty acids and n-alkan-2-ones demonstrated changes related to vegetational shifts throughout the peat profiles. The source materials included remains from mosses, higher terrestrial plants as well as microbial sources. In the peat of the "Großer Bolchow", contributions from phytoplankton were also identified. Among the alkyl series, the n-alkanes evidenced the highest reliability as biomarkers in the peat deposits. Although combination of the results of the three alkyl series were complementary, in some cases, this approach lead to ambiguities, possibly because of selective preservation of certain lipids during peatification. Thus, to verify the analytical results, they were supplemented with field assessment data. Subjecting the two peats to CuO-oxidation revealed mainly contributions of mosses and grasses. The analysis of the degradation stage of the lignin derivatives supported the decomposition pattern already revealed by the δ13C data and the NMR analysis. In summary, our study confirmed that in peat, changes in biomarker abundance and distribution are in accordance with chemical alterations of the organic matter composition. However, both biomarker abundance and the degradation state of the organic material did not indicate a constant increase of the humification with peat depths but showed clear fluctuations along the core. This is in line with the constantly changing climatic conditions during peat formation that are either favoring or hindering organic matter accumulation.

  7. Chemotaxis toward phytoplankton drives organic matter partitioning among marine bacteria

    PubMed Central

    Smriga, Steven; Fernandez, Vicente I.; Mitchell, James G.; Stocker, Roman

    2016-01-01

    The microenvironment surrounding individual phytoplankton cells is often rich in dissolved organic matter (DOM), which can attract bacteria by chemotaxis. These “phycospheres” may be prominent sources of resource heterogeneity in the ocean, affecting the growth of bacterial populations and the fate of DOM. However, these effects remain poorly quantified due to a lack of quantitative ecological frameworks. Here, we used video microscopy to dissect with unprecedented resolution the chemotactic accumulation of marine bacteria around individual Chaetoceros affinis diatoms undergoing lysis. The observed spatiotemporal distribution of bacteria was used in a resource utilization model to map the conditions under which competition between different bacterial groups favors chemotaxis. The model predicts that chemotactic, copiotrophic populations outcompete nonmotile, oligotrophic populations during diatom blooms and bloom collapse conditions, resulting in an increase in the ratio of motile to nonmotile cells and in the succession of populations. Partitioning of DOM between the two populations is strongly dependent on the overall concentration of bacteria and the diffusivity of different DOM substances, and within each population, the growth benefit from phycospheres is experienced by only a small fraction of cells. By informing a DOM utilization model with highly resolved behavioral data, the hybrid approach used here represents a new path toward the elusive goal of predicting the consequences of microscale interactions in the ocean. PMID:26802122

  8. Dissolved organic matter reduces algal accumulation of methylmercury

    USGS Publications Warehouse

    Luengen, Allison C.; Fisher, Nicholas S.; Bergamaschi, Brian A.

    2012-01-01

    Dissolved organic matter (DOM) significantly decreased accumulation of methylmercury (MeHg) by the diatom Cyclotella meneghiniana in laboratory experiments. Live diatom cells accumulated two to four times more MeHg than dead cells, indicating that accumulation may be partially an energy-requiring process. Methylmercury enrichment in diatoms relative to ambient water was measured by a volume concentration factor (VCF). Without added DOM, the maximum VCF was 32 x 104, and the average VCF (from 10 to 72 h) over all experiments was 12.6 x 104. At very low (1.5 mg/L) added DOM, VCFs dropped by approximately half. At very high (20 mg/L) added DOM, VCFs dropped 10-fold. Presumably, MeHg was bound to a variety of reduced sulfur sites on the DOM, making it unavailable for uptake. Diatoms accumulated significantly more MeHg when exposed to transphilic DOM extracts than hydrophobic ones. However, algal lysate, a labile type of DOM created by resuspending a marine diatom in freshwater, behaved similarly to a refractory DOM isolate from San Francisco Bay. Addition of 67 μM L-cysteine resulted in the largest drop in VCFs, to 0.28 x 104. Although the DOM composition influenced the availability of MeHg to some extent, total DOM concentration was the most important factor in determining algal bioaccumulation of MeHg.

  9. Results of the 2008 dissolved organic matter fluorescence intercalibration study

    NASA Astrophysics Data System (ADS)

    Murphy, K. R.; Butler, K.; Spencer, R. G.; Boehme, J.; Aiken, G.

    2009-12-01

    In 2008, 20 laboratories around the world participated in an intercalibration study of organic matter fluorescence measurements via Excitation-Emission Matrix Spectroscopy (EEMS). The goal was to assess the variability of fluorescence measurements obtained for identical samples (n = 5 natural samples, Suwanee River Fulvic Acid, quinine sulphate and four Starna Fluorescence Reference cells) by different laboratories, and to examine potential sources of this variability. Operator error was found to be a significant source of variability, with 6 laboratories submitting erroneous EEMs in an initial round. Uncorrected EEMs were significantly different from corrected EEMs, particularly at relatively low and relatively high excitation (λex) and emission (λem) wavelengths. When data from each lab were corrected according to a standard set of algorithms, the variability between EEMs for the same sample measured by different labs was wavelength dependent, with EEMs normalized to raman areas more similar at low λex and λem, and EEMs normalized to quinine sulphate equivalents more similar at higher wavelengths. The results confirm the importance of (1) applying spectral corrections prior to comparing fluorescence data acquired on different instruments, (2) full reporting of correction procedures and implementation according to an agreed standard protocol, and (3) strict implementation of quality assurance protocols prior to reporting EEMs.

  10. Soil microstructure and organic matter: keys for chlordecone sequestration.

    PubMed

    Woignier, T; Fernandes, P; Soler, A; Clostre, F; Carles, C; Rangon, L; Lesueur-Jannoyer, M

    2013-11-15

    Past applications of chlordecone, a persistent organochlorine pesticide, have resulted in diffuse pollution of agricultural soils, and these have become sources of contamination of cultivated crops as well as terrestrial and marine ecosystems. Chlordecone is a very stable and recalcitrant molecule, mainly present in the solid phase, and has a strong affinity for organic matter. To prevent consumer and ecosystem exposure, factors that influence chlordecone migration in the environment need to be evaluated. In this study, we measured the impact of incorporating compost on chlordecone sequestration in andosols as a possible way to reduce plant contamination. We first characterized the transfer of chlordecone from soil to plants (radish, cucumber, and lettuce). Two months after incorporation of the compost, soil-plant transfers were reduced by a factor of 1.9-15 depending on the crop. Our results showed that adding compost modified the fractal microstructure of allophane clays thus favoring chlordecone retention in andosols. The complex structure of allophane and the associated low accessibility are important characteristics governing the fate of chlordecone. These results support our proposal for an alternative strategy that is quite the opposite of total soil decontamination: chlordecone sequestration.

  11. [Effects of dissolved organic matter on copper absorption by ryegrass].

    PubMed

    Tang, Chao; Wang, Bin; Liu, Man-Qiang; Hu, Feng; Li, Hui-Xin; Jiao, Jia-Guo

    2012-08-01

    In this study, dissolved organic matter (DOM) was extracted from earthworm casts and from the cattle manure with which the earthworms were fed, and a water culture experiment was conducted to study the effects of the DOM on the copper (Cu2+) absorption by ryegrass in the presence of different concentration Cu2+ (0, 5 and 10 mg x L(-1)). With the increasing concentration of Cu2+ in the medium, there was a gradual decrease in the dry mass of ryegrass shoots and roots and in the root length, surface area, volume, and tip number. In the presence of medium Cu2+, DOM increased the biomass of shoots and roots and the root length, surface area, volume, and tip number significantly. DOM reduced the Cu2+ concentration in roots, promoted the Cu2+ translocation from roots to shoots, and significantly increased the Cu2+ accumulation in shoots. The DOM from earthworm casts had better effects than that from cattle manure, and high concentration DOM had better effects than low concentration DOM. PMID:23189712

  12. Soil microstructure and organic matter: keys for chlordecone sequestration.

    PubMed

    Woignier, T; Fernandes, P; Soler, A; Clostre, F; Carles, C; Rangon, L; Lesueur-Jannoyer, M

    2013-11-15

    Past applications of chlordecone, a persistent organochlorine pesticide, have resulted in diffuse pollution of agricultural soils, and these have become sources of contamination of cultivated crops as well as terrestrial and marine ecosystems. Chlordecone is a very stable and recalcitrant molecule, mainly present in the solid phase, and has a strong affinity for organic matter. To prevent consumer and ecosystem exposure, factors that influence chlordecone migration in the environment need to be evaluated. In this study, we measured the impact of incorporating compost on chlordecone sequestration in andosols as a possible way to reduce plant contamination. We first characterized the transfer of chlordecone from soil to plants (radish, cucumber, and lettuce). Two months after incorporation of the compost, soil-plant transfers were reduced by a factor of 1.9-15 depending on the crop. Our results showed that adding compost modified the fractal microstructure of allophane clays thus favoring chlordecone retention in andosols. The complex structure of allophane and the associated low accessibility are important characteristics governing the fate of chlordecone. These results support our proposal for an alternative strategy that is quite the opposite of total soil decontamination: chlordecone sequestration. PMID:24056248

  13. The Organic Matter Biogeochemistry of the Congo River

    NASA Astrophysics Data System (ADS)

    Spencer, R. G.; Hernes, P.; Wabakanghanzi, J.; Bienvenu, D. J.; Six, J.

    2015-12-01

    Organic matter (OM) represents a fundamental link between terrestrial and aquatic carbon cycles and plays an essential role in aquatic ecosystem biogeochemistry. The Congo River, which drains pristine tropical forest and savannah is the second largest exporter of terrestrial carbon to the ocean, and represents a historically understudied basin. Our ongoing projects in the Congo Basin aim to provide pertinent information on transport and emissions of carbon by rivers that need to be incorporated into carbon budgets of terrestrial ecosystems. To date the Congo Basin has seen only limited perturbation but the carbon locked away in the Congo, as in other tropical rainforests is increasingly vulnerable to release into the aquatic system and the atmosphere. However, riverine carbon transport (both of OM to the oceans and release of CO2 to the atmosphere) as a driver of global carbon cycling is still largely overlooked. Here we present data from a multi-season field campaign to quantify the transport fluxes, mineralization fluxes, and chemical character of Congo River OM, and to elucidate how these properties relate to each other and vary seasonally driven by hydrology within the Congo Basin. Existing data demonstrates that although tropical rivers do not experience the seasonal climatic extremes of temperate or northern high-latitude rivers, they all demonstrate similar effects due to changing hydrologic inputs with respect to OM dynamics. Specifically flushing periods appear to warrant further study as maximal export of reactive freshly leached plant material occurs during this time period.

  14. Chemotaxis toward phytoplankton drives organic matter partitioning among marine bacteria.

    PubMed

    Smriga, Steven; Fernandez, Vicente I; Mitchell, James G; Stocker, Roman

    2016-02-01

    The microenvironment surrounding individual phytoplankton cells is often rich in dissolved organic matter (DOM), which can attract bacteria by chemotaxis. These "phycospheres" may be prominent sources of resource heterogeneity in the ocean, affecting the growth of bacterial populations and the fate of DOM. However, these effects remain poorly quantified due to a lack of quantitative ecological frameworks. Here, we used video microscopy to dissect with unprecedented resolution the chemotactic accumulation of marine bacteria around individual Chaetoceros affinis diatoms undergoing lysis. The observed spatiotemporal distribution of bacteria was used in a resource utilization model to map the conditions under which competition between different bacterial groups favors chemotaxis. The model predicts that chemotactic, copiotrophic populations outcompete nonmotile, oligotrophic populations during diatom blooms and bloom collapse conditions, resulting in an increase in the ratio of motile to nonmotile cells and in the succession of populations. Partitioning of DOM between the two populations is strongly dependent on the overall concentration of bacteria and the diffusivity of different DOM substances, and within each population, the growth benefit from phycospheres is experienced by only a small fraction of cells. By informing a DOM utilization model with highly resolved behavioral data, the hybrid approach used here represents a new path toward the elusive goal of predicting the consequences of microscale interactions in the ocean.

  15. Chemotaxis toward phytoplankton drives organic matter partitioning among marine bacteria.

    PubMed

    Smriga, Steven; Fernandez, Vicente I; Mitchell, James G; Stocker, Roman

    2016-02-01

    The microenvironment surrounding individual phytoplankton cells is often rich in dissolved organic matter (DOM), which can attract bacteria by chemotaxis. These "phycospheres" may be prominent sources of resource heterogeneity in the ocean, affecting the growth of bacterial populations and the fate of DOM. However, these effects remain poorly quantified due to a lack of quantitative ecological frameworks. Here, we used video microscopy to dissect with unprecedented resolution the chemotactic accumulation of marine bacteria around individual Chaetoceros affinis diatoms undergoing lysis. The observed spatiotemporal distribution of bacteria was used in a resource utilization model to map the conditions under which competition between different bacterial groups favors chemotaxis. The model predicts that chemotactic, copiotrophic populations outcompete nonmotile, oligotrophic populations during diatom blooms and bloom collapse conditions, resulting in an increase in the ratio of motile to nonmotile cells and in the succession of populations. Partitioning of DOM between the two populations is strongly dependent on the overall concentration of bacteria and the diffusivity of different DOM substances, and within each population, the growth benefit from phycospheres is experienced by only a small fraction of cells. By informing a DOM utilization model with highly resolved behavioral data, the hybrid approach used here represents a new path toward the elusive goal of predicting the consequences of microscale interactions in the ocean. PMID:26802122

  16. Natural organic matter enhanced mobility of nano zerovalent iron.

    PubMed

    Johnson, Richard L; Johnson, Graham O'Brien; Nurmi, James T; Tratnyek, Paul G

    2009-07-15

    Column studies showed that the mobility of nanometer-sized zerovalent iron (nZVI) through granular media is greatly increased in the presence of natural organic matter (NOM). At NOM concentrations of 20 mg/L or greater, the nZVI was highly mobile during transport experiments in 0.15-m long columns packed with medium sand. Below 20 mg/L NOM, mobility of the nZVI was less; however, even at 2 mg/L the nZVI showed significantly increased mobility compared to the no-NOM case. Spectrophotometric and aggregation studies of nZVI suspensions in the presence of NOM suggest that sorption of the NOM onto the nZVI, resulting in a reduced sticking coefficient, may be the primary mechanism of enhanced mobility. Modeling the mobility of nZVI in porous media with filtration theory is challenging, but calibration of a simple model with experimental results from the column experiments reported here allows simulation of transport distances during injection. The simulation results show that the increased mobility due to NOM combined with the decrease in mobility due to decreased velocity with distance from an injection well could produce an injection zone that is wide enough to be useful for remediation but small enough to avoid reaching unwanted receptors. PMID:19708381

  17. The chemical ecology of soil organic matter molecular constituents.

    PubMed

    Simpson, Myrna J; Simpson, André J

    2012-06-01

    Soil organic matter (OM) contains vast stores of carbon, and directly supports microbial, plant, and animal life by retaining essential nutrients and water in the soil. Soil OM plays important roles in biological, chemical, and physical processes within the soil, and arguably plays a major role in maintaining long-term ecological stability in a changing world. Despite its importance, there is a great deal still unknown about soil OM chemical ecology. The development of sophisticated analytical methods have reshaped our understanding of soil OM composition, which is now believed to be comprised of plant and microbial products at various stages of decomposition. The methods also have recently been applied to study environmental change in various settings and have provided unique insight with respect to soil OM chemical ecology. The goal of this review is to highlight the methods used to characterize soil OM structure, source, and degradation that have enabled precise observations of OM and associated ecological shifts. Although the chemistry of soil OM is important in its overall fate in ecosystems, the studies conducted to date suggest that ecological function is not defined by soil OM chemistry alone. The long-standing questions regarding soil OM stability and recalcitrance will likely be answered when several molecular methods are used in tandem to closely examine structure, source, age, degradation stage, and interactions of specific OM components in soil.

  18. Mercury reduction and complexation by natural organic matter

    SciTech Connect

    Gu, Baohua; Bian, Yongrong; Miller, Carrie L; Dong, Wenming; Jiang, Xin; Liang, Liyuan

    2011-01-01

    Mercuric Hg(II) species form complexes with natural dissolved organic matter (DOM) such as humic acid (HA), and this binding is known to affect the chemical and biological transformation and cycling of mercury in aquatic environments. Dissolved elemental mercury, Hg(0), is also widely observed in sediments and water. However, reactions between Hg(0) and DOM have rarely been studied in anoxic environments. Here, under anoxic dark conditions we show strong interactions between reduced HA and Hg(0) through thiol-ligand induced oxidative complexation with an estimated binding capacity of about 3.5 umol Hg(0)/g HA and a partitioning coefficient greater than 10^6 mL/g. We further demonstrate that Hg(II) can be effectively reduced to Hg(0) in the presence of as little as 0.2 mg/L reduced HA, whereas production of purgeable Hg(0) is inhibited by complexation as HA concentration increases. This dual role played by DOM in the reduction and complexation of mercury is likely widespread in anoxic sediments and water and can be expected to significantly influence the mercury species transformations and biological uptake that leads to the formation of toxic methylmercury.

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

    USGS Publications Warehouse

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

    2014-01-01

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

  20. Biochemical composition of organic matter in UK Midlands catchments: implications for drinking water treatment

    NASA Astrophysics Data System (ADS)

    Bieroza, M.; Bridgeman, J.; Baker, A.

    2007-12-01

    Insufficient removal of natural organic matter at treatment works can lead to the formation of potentially carcinogenic disinfection by-products (mainly trihalomethanes and haloacetic acids, THMs and HAAs) due to reactions of residual organic matter with chlorine added at the disinfection stage of water treatment process. However, the total organic carbon (TOC) removal efficiency is controlled by the content and character of organic matter in treated water, spatially and temporally dependent (e.g. the ratio of hydrophylic and hydrophobic fractions). Thus, a better understanding of organic matter composition can affect the treatment process strategies, improving the THM formation prediction and the quantification of coagulant and disinfection dosages. Fluorescence analysis of organic matter composition and treatment efficiency has been carried out on raw and partially-treated water samples from catchments in the Midlands region of the UK. The catchments cover an area of different water sources, ranging from upland, peaty-rich subcatchments with coloured, young waters, to agriculturally transformed lowland subcatchments. From the spectrophotometric analysis of raw water it was found that, the abstraction from river with water storage in reservoirs corresponds with a hydrophilic character of organic matter, rather high microbial fraction and high TOC. Opposite properties (hydrophobic, low microbial and variable TOC) are specific for sites with abstraction and storage processes within reservoirs. For direct abstraction from rivers, without water storing in reservoir, a common pattern is intermediate character of organic matter. The fluorescence excitation-emission matrix (EEM) technique was used for the assessment of water treatment works performance (TOC removal) and organic matter characterization. The freshwater organic matter exhibits specific fluorescence properties, with increased intensities of fluorescence in some regions of the EEM, resulting from the water

  1. Comparison of polycyclic aromatic hydrocarbon distributions and sedimentary organic matter characteristics in contaminated, coastal sediments from Pensacola Bay, Florida.

    PubMed

    Simpson, Myrna J; Chefetz, Benny; Deshmukh, Ashish P; Hatcher, Patrick G

    2005-03-01

    In this study, we examined the distribution of polycyclic aromatic hydrocarbons (PAHs) in a contaminated coastal area and the characteristics of the natural organic matter in tandem. We present a detailed study of PAH concentration, distribution, and organic matter characteristics of three core samples from Pensacola Bay, Florida. Solid-state 13C Nuclear Magnetic Resonance (NMR), pyrolysis gas chromatography coupled with mass spectrometry (GC-MS), and tetramethyl ammonium hydroxide (TMAH) thermochemolysis GC-MS were applied to obtain structural details about the sedimentary organic matter. Elemental compositions (carbon and nitrogen) and estimates of black carbon contents are also reported. These coastal sediments were found to contain more PAHs in the upper 15 cm layers than in the bottom 15-25 cm samples. The samples that contained the most PAHs also contained the least amount of aromatic carbon and contained a significant amount of paraffinic carbon. Lignin-derived pyrolysis and TMAH thermochemolysis products were abundant and generally higher in all of the samples in comparison to those reported for modern coastal sediments, indicating a large flux of terrestrial carbon. The black carbon contents were found to range from 4.3% to 6.8%, which are significantly lower than other reports of black carbon in sediments, which represent as much as 65% of the total organic carbon content. The low black carbon content suggests that this type of refractory carbon may not be as responsible for regulating PAH distribution as indicated by other researchers.

  2. FACTORS INFLUENCING PHOTOREACTIONS OF DISSOLVED ORGANIC MATTER IN A COASTAL RIVER OF THE SOUTHEASTERN UNITED STATES

    EPA Science Inventory

    Photoreactions of dissolved organic matter can affect the oxidizing capacity, nutrient dynamics, trace gas exchange, and color of surface waters. This study focuses on factors that affect the photoreactions of the colored dissolved organic matter (CDOM) in the Satilla River, a co...

  3. Advances in understanding the molecular structure of soil organic matter: Implications for interactions in the environment

    EPA Science Inventory

    We take a historic approach to explore how concepts of the chemical and physical nature of soil organic matter have evolved over time. We emphasize conceptual and analytical achievements in organic matter research over the last two decades and demonstrate how these developments h...

  4. Organic matter and nutrient cycling in linked glacier-stream ecosystems along the Gulf of Alaska

    NASA Astrophysics Data System (ADS)

    Scott, D.; Hood, E. W.; Nassry, M. Q.; Vermilyea, A.

    2010-12-01

    Glacial ecosystems cover approximately 10% of the Earth’s surface and contribute large volumes of runoff to rivers and coastal oceans. Moreover, anticipated future changes in glacial runoff are markedly larger than those projected for non-glacial river systems. Recent research on the biogeochemistry of glacier ecosystems has shown that glacier environments contain abundant microbial communities and are more biogeochemically active than was previously believed. Runoff from glaciers typically contains low concentrations of dissolved organic matter (DOM) and nutrients, however at low latitudes and in coastal regions, high water fluxes can amplify material concentrations, such that biogeochemical (C, N, and P) fluxes from glacial watersheds can be substantial. As a result, glacier runoff has the potential to be an important biogeochemical subsidy to downstream freshwater and marine ecosystems. Glaciers in coastal watersheds along the Gulf of Alaska (GOA) are thinning and receding at rapid rates, leading to a transition from ecosystems dominated by glacial ice and rock to ecosystems containing developed soils and vegetation. Within this context, we are examining how the quality and quantity of carbon and nutrients within stream networks changes as a function of landcover. Our research is focused on a series of watersheds, primarily in southeastern Alaska, that range in glacier coverage from 0 to >60%. We are using these watersheds to substitute space for time and begin to unravel how both the magnitude and timing of watershed fluxes of C, N, and P may change as glaciers continue to recede. Our previous results have shown that different levels of glacial coverage alter the timing and magnitude of fresh water, dissolved organic matter and nutrient yields. Our results suggest that a lower extent of glacial coverage within a watershed leads to higher amounts of dissolved organic matter, but decreased phosphorous yields. We have also found that the glaciers are a

  5. Decomposition of soil organic matter from boreal black spruce forest: Environmental and chemical controls

    USGS Publications Warehouse

    Wickland, K.P.; Neff, J.C.

    2008-01-01

    Black spruce forests are a dominant covertype in the boreal forest region, and they inhabit landscapes that span a wide range of hydrologic and thermal conditions. These forests often have large stores of soil organic carbon. Recent increases in temperature at northern latitudes may be stimulating decomposition rates of this soil carbon. It is unclear, however, how changes in environmental conditions influence decomposition in these systems, and if substrate controls of decomposition vary with hydrologic and thermal regime. We addressed these issues by investigating the effects of temperature, moisture, and organic matter chemical characteristics on decomposition of fibric soil horizons from three black spruce forest sites. The sites varied in drainage and permafrost, and included a "Well Drained" site where permafrost was absent, and "Moderately well Drained" and "Poorly Drained" sites where permafrost was present at about 0.5 m depth. Samples collected from each site were incubated at five different moisture contents (2, 25, 50, 75, and 100% saturation) and two different temperatures (10??C and 20??C) in a full factorial design for two months. Organic matter chemistry was analyzed using pyrolysis gas chromatography-mass spectrometry prior to incubation, and after incubation on soils held at 20??C, 50% saturation. Mean cumulative mineralization, normalized to initial carbon content, ranged from 0.2% to 4.7%, and was dependent on temperature, moisture, and site. The effect of temperature on mineralization was significantly influenced by moisture content, as mineralization was greatest at 20??C and 50-75% saturation. While the relative effects of temperature and moisture were similar for all soils, mineralization rates were significantly greater for samples from the "Well Drained" site compared to the other sites. Variations in the relative abundances of polysaccharide-derivatives and compounds of undetermined source (such as toluene, phenol, 4-methyl phenol, and

  6. Cosorption study of organic pollutants and dissolved organic matter in a soil.

    PubMed

    Flores-Céspedes, F; Fernández-Pérez, M; Villafranca-Sánchez, M; González-Pradas, E

    2006-08-01

    In this study we have evaluated the effects of dissolved organic matter (DOM) on sorption of imidacloprid, 3,4-dichloroaniline (3,4-DCA) and 4-bromoaniline (4-BA) on a typical calcareous soil (Luvic Xerosol) from south-eastern Spain. Two different types of DOM were used, that is to say, dissolved natural organic matter extracts from a commercial peat (DNOM) and a high-purity tannic acid (TA) solution. The experiments were carried out in a 0.01 M CaCl2 aqueous medium at 25 degrees C. The results indicated that the presence of both DNOM and TA, over a concentration range of 15-100 mg L(-1), produced an increase in the amount of 3,4-DCA and 4-BA sorbed and a decrease in the amount of imidacloprid retained on the soil studied. A modified distribution coefficient, K(doc), has been proposed as a safer parameter for soil sorption predictions of organic pollutants and it could be of help to model the fate of these in the environment.

  7. Soil organic matter on citrus plantation in Eastern Spain

    NASA Astrophysics Data System (ADS)

    Cerdà, Artemi; Pereira, Paulo; Novara, Agata; Prosdocimi, Massimo

    2015-04-01

    Citrus plantations in Eastern Spain are the main crop and Valencia region is the largest world exporter. The traditional plantation are located on flood irrigated areas and the new plantation are located on slopes were drip irrigation is the source of the wetting. It has been demonstrate that the citrus plantations contribute to high erosion rates on slopes (Cerdà et al., 2009b) as it is usual on agriculture land (Cerdà et al., 2009a), but when organic farming is present the soil erosion is much lower (Cerdà and Jurgensen, 2008; Cerdà et al., 2009; Cerdà and Jurgensen, 2011). This is a worldwide phenomenon (Wu et al., 2007; Wu et al., 2011; Xu et al., 2010; Xu et al., 2012a; Xu et al., 2012b), which are a key factor of the high erosion rates in rural areas (García Orenes et al., 2009: García Orenes et al., 20010; García Orenes et al., 2012; Haregewyn et al., 2013; Zhao et al., 2013). The key factor of the contrasted response of soils to the rain in citrus is the organic matter cover. This is why the Soil Erosion and Degradation Research Team developed a survey to determine the soil erosion rates on citrus orchards under different managements. A hundred of samples were collected in a citrus plantation on slope under conventional management (Chemical management), one on organic farming, one on traditional flood irrigated organic farming and one on traditional chemical flooding farm. The organic farming soils were treated with 10000 Kg ha-1 of manure yearly. The results show that the mean soil organic matter content was 1.24 %, 3.54%, 5,43% and 2.1% respectively, which show a clear impact of organic farming in the recovery of the soil organic matter. meanwhile the on the slopes and the flood-irrigated soils are Acknowledgements The research projects GL2008-02879/BTE, LEDDRA 243857 and PREVENTING AND REMEDIATING DEGRADATION OF SOILS IN EUROPE THROUGH LAND CARE (RECARE)FP7- ENV-2013- supported this research. References Cerdà, A., Flanagan, D.C., le Bissonnais

  8. Heat impact caused molecular level changes in solid and dissolved soil organic matter

    NASA Astrophysics Data System (ADS)

    Hofmann, Diana; Steffen, Bernhard; Eckhardt, Kai-Uwe; Leinweber, Peter

    2015-04-01

    The ubiquitous abundance of pyrolysed, highly aromatic organic matter, called "Black Carbon" (BC), in all environmental compartments became increasingly important in different fields of research beyond intensive investigated atmospheric aerosol due to climatic relevance. Its predominant high resistance to abiotic and biotic degradation resulted in turnover times from less than a century to several millennia. This recalcitrance led to the enrichment of BC in soils, accounting for 1-6% (European forest soils) to 60% (Chernozems) of total soil organic matter (SOM). Hence, soil BC acts an important sink in the global carbon cycle. In contrast, consequences for the nitrogen cycle up to date are rather inconsistently discussed. Soil related dissolved organic matter (DOM) is a major controlling factor in soil formation, an important pathway of organic matter transport and one of the largest active carbon reservoirs on earth, if considering oceans and other bodies of water. The aim of this study was to evaluate the effects of artificially simulated wildfire by thermal treatment on the molecular composition of water extractable soil organic matter (DOM). Soils from two outdoor lysimeters with different management history were investigated. Soil samples, non-heated and heated up to 350°C were analyzed for elemental composition (carbon, nitrogen and sulfur) and for bulk molecular composition by Pyrolysis-Field Ionization Mass Spectrometry (Py-FIMS) and synchrotron-based X-ray Absorption Near-Edge Spectroscopy (XANES) at the C- and N K-edges. DOM-samples obtained by hot water extraction, desalting and concentration by solid phase extraction were subsequently analyzed by flow injection analysis in a Fourier Transform Ion Cyclotron Resonance Mass Spectrometer (FTICR-MS), equipped with an ESI source and a 7 T supra-conducting magnet (LTQ-FT Ultra, ThermoFisher Scientific). This technique is the key technique for the analysis of complex samples due to its outstanding mass

  9. Where is DNA preserved in soil organic matter?

    NASA Astrophysics Data System (ADS)

    Zaccone, Claudio; Beneduce, Luciano; Plaza, César

    2015-04-01

    Deoxyribonucleic acid (DNA) consists of long chains of alternating sugar and phosphate residues twisted in the form of a helix. Upon decomposition of plant and animal debris, this nucleic acid is released into the soil, where its fate is still not completely understood. In fact, although DNA is one of the organic compounds from living cells that is apparently broken down rapidly in soils, it is also potentially capable of being incorporated in (or interact with) the precursors of humic molecules. In order to track DNA occurrence in soil organic matter (SOM) fractions, an experiment was set up as a randomized complete block design with two factors, namely biochar addition and organic amendment. In particular, biochar (BC), applied at a rate of 20 t/ha, was combined with municipal solid waste compost (BC+MC) at a rate equivalent to 75 kg/ha of potentially available N, and with sewage sludge (BC+SS) at a rate equivalent to 75 kg/ha of potentially available N. Using a physical fractionation method, free SOM located between aggregates (unprotected C pool; FR), SOM occluded within macroaggregates (C pool weakly protected by physical mechanisms; MA), SOM occluded within microaggregates (C pool strongly protected by physical mechanisms; MI), and SOM associated with the mineral fractions (chemically-protected C pool; MIN) were separated from soil samples. DNA was then isolated from each fraction of the two series, as well as from the unamended soil (C) and from the bulk soils (WS), using Powersoil DNA isolation kit (MoBio, CA, USA) with a modified protocol. Data clearly show that the DNA survived the SOM fractionation, thus suggesting that physical fractionation methods create less artifacts compared to the chemical ones. Moreover, in both BC+MC and BC+SS series, most of the isolated DNA was present in the FR fraction, followed by the MA and the MI fractions. No DNA was recovered from the MIN fraction. This finding supports the idea that most of the DNA occurring in the SOM

  10. Soil Organic Matter Effects on Phosphorus Sorption: a Path Analysis

    SciTech Connect

    Kang, J.; Hesterberg, D; Osmond, D

    2009-01-01

    While P sorption in mineral soils has been extensively studied, P sorption behavior in organic-rich soils is less known. This study was conducted to determine the relationships between Langmuir P sorption maxima (S{sub max}) and selected physicochemical properties of soils, with particular emphasis on organic matter (OM) content. The S{sub max} values were determined for 72 soil samples from the North Carolina Coastal Plain, along with pH, clay and OM contents, oxalate-extractable P (P{sub ox}), Al (Al{sub ox}), and Fe (Fe{sub ox}), and Mehlich 3 extractable P (P{sub M3}), Al (Al{sub M3}), and Fe (Fe{sub M3}). Path analysis was used to examine direct and indirect effects of soil properties on S{sub max}. In the oxalate path analysis, the direct effects of clay, Al{sub ox}, and Fe{sub ox} on S{sub max} were significant in the order Al{sub ox} > clay > Fe{sub ox} (P < 0.05). The S{sub max} was highly influenced by the indirect effect of Al{sub ox} and Fe{sub ox} through OM content. A two-piece segmented linear relationship existed between S{sub max} and OM and the regression slope in soils with OM {le} 49 g kg{sup -1} was 10-fold greater than that for soils with OM > 49 g kg{sup -1}. This finding suggested that noncrystalline or organically bound Al and Fe in the soils with OM > 49 g kg{sup -1} is less effective for P sorption than in the soils with lower OM content. In the Mehlich 3 path analysis, the direct effects of clay, OM, and Al{sub M3} on S{sub max} were significant in the order Al{sub M3} > OM > clay (P < 0.05) while the direct effect of Fe{sub M3} on S{sub max} was not significant. Oxalate may be better suited than Mehlich 3 as an extractant for predicting P sorption capacity in the Coastal Plain soils.

  11. 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.

  12. Quantitative retrieving of soil organic matter using field spectrometer and hyperspectral remote sensing

    NASA Astrophysics Data System (ADS)

    Zhuo, Luo; Liu, Yaolin; Chen, Jie; Hu, Changji; Wu, Jian

    2008-12-01

    As the important component of soil, soil organic matter not only provides every nutrient element for crop, but also has determinant effect for forming of soil structure and melioration the soil physical character. Mapping and dating soil organic matter is of great importance in soil use and evaluation. In this study we examine the feasibility of soil organic matter content by using Hyperspectrally reflective remote sensing methodology. This technique was tested in Xiaochang County located in Hubei province. The soil reflectance properties of samples were measured in the laboratory by ASD field spectrometer. The correlation analysis related with organic matter content was processed from three factors: the spectral reflectance parameter ((lgρ)', ρ/ ρ450-750 and (1/lgρ623)'/ (1/lgρ564)'). The results show that the correlation coefficients of r values were: organic matter identification index (ρ/ ρ450-750) > logarithmic first derivative of reflectivity ((lgρ)') > organic matter mix identification index ((1/lgρ623)'/(1/lgρ564)'). Knowing these correlations we were able to use the best prominence correlation of organic matter identification index of 1850nm wavelength as the variable regression to build up statistical regression analysis. We used five model types (Linear Function, Logarithmic Function, Quadratic Function, Power Function and Exponential Function) to forecast the soil organic matter content Hyperion model. The accuracy assessment (R2= 0.8484) by relating forecasted organic matter values with Quadratic Function regression showed that the model is reliable and significantly correlative with known stabilization processes throughout the study area. The quantitative methodology developed in this study for refutations soil organic matter content can be adapted to other regions throughout the world.

  13. Estimating toxic damage to soil ecosystems from soil organic matter profiles

    USGS Publications Warehouse

    Beyer, W.N.

    2001-01-01

    Concentrations of particulate and total organic matter were measured in upper soil profiles at 26 sites as a potential means to identify toxic damage to soil ecosystems. Because soil organic matter plays a role in cycling nutrients, aerating soil, retaining water, and maintaining tilth, a significant reduction in organic matter content in a soil profile is not just evidence of a change in ecosystem function, but of damage to that soil ecosystem. Reference sites were selected for comparison to contaminated sites, and additional sites were selected to illustrate how variables other than environmental contaminants might affect the Soil organic matter profile. The survey was undertaken on the supposition that environmental contaminants and other stressors reduce the activity of earthworms and other macrofauna, inhibiting the incorporation of organic matter into the soil profile. The profiles of the unstressed soils showed a continuous decrease in organic matter content from the uppermost mineral soil layer (0-2.5 cm) down to 15 cm. Stressed soils showed an abrupt decrease in soil organic matter content below a depth of 2.5 cm. The 2.5-5.0 cm layer of stressed soils--such as found in a pine barren, an orchard, sites contaminated with zinc, and a site with compacted soil--had less than 4% total organic matter and less than 1% particulate organic matter. However, damaged soil ecosystems were best identified by comparison of their profiles to the profiles of closely matched reference soils, rather than by comparison to these absolute values. The presence or absence of earthworms offered a partial explanation of observed differences in soil organic matter profiles.

  14. Transport of organic contaminants in subsoil horizons and effects of dissolved organic matter related to organic waste recycling practices.

    PubMed

    Chabauty, Florian; Pot, Valérie; Bourdat-Deschamps, Marjolaine; Bernet, Nathalie; Labat, Christophe; Benoit, Pierre

    2016-04-01

    Compost amendment on agricultural soil is a current practice to compensate the loss of organic matter. As a consequence, dissolved organic carbon concentration in soil leachates can be increased and potentially modify the transport of other solutes. This study aims to characterize the processes controlling the mobility of dissolved organic matter (DOM) in deep soil layers and their potential impacts on the leaching of organic contaminants (pesticides and pharmaceutical compounds) potentially present in cultivated soils receiving organic waste composts. We sampled undisturbed soil cores in the illuviated horizon (60-90 cm depth) of an Albeluvisol. Percolation experiments were made in presence and absence of DOM with two different pesticides, isoproturon and epoxiconazole, and two pharmaceutical compounds, ibuprofen and sulfamethoxazole. Two types of DOM were extracted from two different soil surface horizons: one sampled in a plot receiving a co-compost of green wastes and sewage sludge applied once every 2 years since 1998 and one sampled in an unamended plot. Results show that DOM behaved as a highly reactive solute, which was continuously generated within the soil columns during flow and increased after flow interruption. DOM significantly increased the mobility of bromide and all pollutants, but the effects differed according the hydrophobic and the ionic character of the molecules. However, no clear effects of the origin of DOM on the mobility of the different contaminants were observed.