Sorptive fractionation of organic matter and formation of organo-hydroxy-aluminum complexes during litter biodegradation in the presence of gibbsite

Treesearch

K. Heckman; A.S. Grandy; X. Gao; M. Keiluweit; K. Wickings; K. Carpenter; J. Chorover; C. Rasmussen

2013-01-01

Solid and aqueous phase Al species are recognized to affect organic matter (OM) stabilization in forest soils. However, little is known about the dynamics of formation, composition and dissolution of organo-Al hydroxide complexes in microbially-active soil systems, where plant litter is subject to microbial decomposition in close proximity to mineral weathering...

From lepton protoplasm to the genesis of hadrons

NASA Astrophysics Data System (ADS)

Eliseev, S. M.; Kosmachev, O. S.

2016-01-01

Theory of matter under extreme conditions opens a new stage in particle physics. It is necessary here to combine Dirac's elementary particle physics with Prigogine's dynamics of nonequilibrium systems. In the article we discuss the problem of the hierarchy of complexity. What can be considered as the lowest level of the organization of extreme matter on the basis of which the self-organization of the complex form occur?

Preservation of organic matter in marine sediments by inner-sphere interactions with reactive iron

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barber, Andrew; Brandes, Jay; Leri, Alessandra

Interactions between organic matter and mineral matrices are critical to the preservation of soil and sediment organic matter. In addition to clay minerals, Fe(III) oxides particles have recently been shown to be responsible for the protection and burial of a large fraction of sedimentary organic carbon (OC). Through a combination of synchrotron X-ray techniques and high-resolution images of intact sediment particles, we assessed the mechanism of interaction between OC and iron, as well as the composition of organic matter co-localized with ferric iron. We present scanning transmission x-ray microscopy images at the Fe L 3 and C K1 edges showingmore » that the organic matter co-localized with Fe(III) consists primarily of C=C, C=O and C-OH functional groups. Coupling the co-localization results to iron K-edge X-ray absorption spectroscopy fitting results allowed to quantify the relative contribution of OC-complexed Fe to the total sediment iron and reactive iron pools, showing that 25–62% of total reactive iron is directly associated to OC through inner-sphere complexation in coastal sediments, as much as four times more than in low OC deep sea sediments. Direct inner-sphere complexation between OC and iron oxides (Fe-O-C) is responsible for transferring a large quantity of reduced OC to the sedimentary sink, which could otherwise be oxidized back to CO 2.« less

Thermochemolysis: A New Sample Preparation Approach for the Detection of Organic Components of Complex Macromolecules in Mars Rocks via Gas Chromatography Mass Spectrometry in SAM on MSL

NASA Technical Reports Server (NTRS)

Eugenbrode, J.; Glavin, D.; Dworkin, J.; Conrad, P.; Mahaffy, P.

2011-01-01

Organic chemicals, when present in extraterrestrial samples, afford precious insight into past and modern conditions elsewhere in the Solar System . No single technology identifies all molecular components because naturally occurring molecules have different chemistries (e.g., polar vs. non-polar, low to high molecular weight) and interface with the ambient sample chemistry in a variety of modes (i.e., organics may be bonded, absorbed or trapped by minerals, liquids, gases, or other organics). More than 90% of organic matter in most natural samples on Earth and in meteorites is composed of complex macromolecules (e.g. biopolymers, complex biomolecules, humic substances, kerogen) because the processes that tend to break down organic molecules also tend towards complexation of the more recalcitrant components. Thus, methodologies that tap the molecular information contained within macromolecules may be critical to detecting extraterrestrial organic matter and assessing the sources and processes influencing its nature.

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

PubMed

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

2016-10-04

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

New Approaches in Soil Organic Matter Fluorescence; A Solid Phase Fluorescence Approach

NASA Astrophysics Data System (ADS)

Bowman, M. M.; Sanclements, M.; McKnight, D. M.

2017-12-01

Fluorescence spectroscopy is a well-established technique to investigate the composition of organic matter in aquatic systems and is increasingly applied to soil organic matter (SOM). Current methods require that SOM be extracted into a liquid prior to analysis by fluorescence spectroscopy. Soil extractions introduce an additional layer of complexity as the composition of the organic matter dissolved into solution varies based upon the selected extractant. Water is one of the most commonly used extractant, but only extracts the water-soluble fraction of the SOM with the insoluble soil organic matter fluorescence remaining in the soil matrix. We propose the use of solid phase fluorescence on whole soils as a potential tool to look at the composition of organic matter without the extraction bias and gain a more complete understand of the potential for fluorescence as a tool in terrestrial studies. To date, the limited applications of solid phase fluorescence have ranged from food and agriculture to pharmaceutical with no clearly defined methods and limitations available. We are aware of no other studies that use solid phase fluorescence and thus no clear methods to look at SOM across a diverse set of soil types and ecosystems. With this new approach to fluorescence spectroscopy there are new challenges, such as blank correction, inner filter effect corrections, and sample preparation. This work outlines a novel method for analyzing soil organic matter using solid phase fluorescence across a wide range of soils collected from the National Ecological Observatory Network (NEON) eco-domains. This method has shown that organic matter content in soils must be diluted to 2% to reduce backscattering and oversaturation of the detector in forested soils. In mineral horizons (A) there is observed quenching of the humic-like organic matter, which is likely a result of organo-mineral complexation. Finally, we present preliminary comparisons between solid and liquid phase fluorescence, which provide new insights into fluorescence studies in terrestrial systems.

Influence of salinity and organic matter on silver accumulation in Gulf toadfish (Opsanus beta).

PubMed

Nichols, Joel W; Brown, Stephanie; Wood, Chris M; Walsh, Patrick J; Playle, Richard C

2006-06-30

To help extend the freshwater based biotic ligand model for silver (Ag) into brackish and saltwater conditions, 50g Gulf toadfish (Opsanus beta) were acclimated to 2.5%, 5%, 10%, 20%, 40%, 80%, or 100% salt water and exposed for 6d to 1.0microM AgNO(3), with or without 10mg C/L organic matter. Suwannee River natural organic matter collected by reverse osmosis was used. Silver accumulation in toadfish gills and plasma decreased as salinity increased, indicating low bioavailability of AgCl complexes. Complexation of Ag by organic matter, normally important in freshwater conditions, was less important as salinity increased. Although relatively little intestinal Ag uptake was observed, both liver and bile accumulated Ag from water imbibed past the isosmotic salinity point ( approximately 1/3 salt water). Toadfish also produced intestinal carbonate pellets, minerals which did not influence Ag accumulation. Our results further stress the importance of Ag speciation, physiological mechanisms, and intestinal Ag uptake when modelling Ag uptake and toxicity beyond freshwater conditions.

The nature and function of microbial enzymes in subsurface marine sediments

NASA Astrophysics Data System (ADS)

Steen, A. D.; Schmidt, J.

2016-02-01

Isotopic and genomic evidence indicates that marine sediments contain populations of active heterotrophic microorganisms which appear to metabolize old, detrital, apparently recalcitrant organic matter. In surface communities, heterotrophs use extracellular enzymes to access complex organic matter. In subsurface sediments, in which microbial doubling times can be on the order of hundreds or thousands of years, it is not clear whether extracellular enzymes could remain stable and active long enough to constitute a 'profitable' stragtegy for accessing complex organic carbon. Here we present evidence that a wide range of extracellular enzyme are active in subsurface sediments from two different environments: the White Oak River, NC, and deep (up to 80 m) sediments of the Baltic Sea Basin recovered from IODP Expedition 347. In the White Oak River, enzymes from deeper sediments appear to be better-adapted to highly-degraded organic matter than enzymes from surface sediments. In the Baltic Sea, preliminary data suggest that enzymes related to nitrogen acquisition are preferentially expressed. By characterizing the extracellular enzymes present in marine sediments, we hope to achieve a better understanding of the mechanisms that control sedimentary organic matter remineralization and preservation.

Total organic carbon and humus fractions in restored soils from limestone quarries in semiarid climate, SE Spain

NASA Astrophysics Data System (ADS)

Luna Ramos, Lourdes; Miralles Mellado, Isabel; Ángel Domene Ruiz, Miguel; Solé Benet, Albert

2016-04-01

Mining activities generate erosion and loss of plant cover and soil organic matter (SOM), especially in arid and semiarid Mediterranean regions. A precondition for ecosystem restoration in such highly disturbed areas is the development of functional soils with sufficient organic matter. But the SOM quality is also important to long-term C stabilization. The resistance to biodegradation of recalcitrant organic matter fractions has been reported to depend on some intrinsic structural factors of humic acid substances and formation of amorphous organo-mineral recalcitrant complexes. In an experimental soil restoration in limestone quarries in the Sierra de Gádor (Almería), SE Spain, several combinations of organic amendments (sewage sludge and compost from domestic organic waste) and mulches (gravel and woodchip) were added in experimental plots using a factorial design. In each plot, 75 native plants (Anthyllis cytisoides, A. terniflora and Macrochloa tenacissima) were planted and five years after the start of the experiment total organic carbon (TOC), physico-chemical soil properties and organic C fractions (particulate organic matter, H3PO4-fulvic fraction, fulvic acids (FA), humic acids (HA) and humin) were analyzed. We observed significant differences between treatments related to the TOC content and the HA/FA ratio. Compost amendments increased the TOC, HA content and HA/FA ratio, even higher than in natural undisturbed soils, indicating an effective clay humus-complex pointing to progressively increasing organic matter quality. Soils with sewage sludge showed the lowest TOC and HA/FA ratio and accumulated a lower HA proportion indicating poorer organic matter quality and comparatively lower resilience than in natural soils and soils amended with compost.

Investigating microbial cycling of recalcitrant organic matter in marine sediments using natural isotope respirometry in a novel, carbon-free bioreactor

NASA Astrophysics Data System (ADS)

Mahmoudi, N.; Beaupre, S. R.; Pearson, A.

2016-02-01

Marine sediments harbor complex microbial communities that play a key role in the cycling of carbon and nutrients. Reactions initiated by microbial enzymes at the molecular scale drive the rate and extent of organic matter degradation to CO2 and CH4. Organic matter is comprised of multiple carbon pools with different intrinsic turnover times. It is hypothesized that microbes will degrade younger pools with more labile compounds, while older pools with refractory compounds will remain unutilized. However, many studies have shown that microbes are capable of respiring older, refractory pools of organic matter in a number of environments. In order to better understand microbial carbon cycling and the fate of recalcitrant organic matter, we constructed a novel bioreactor system to measure carbon isotopes during microbial degradation of complex organic matter. This system enables us to measure the natural isotopic signature (δ13C and Δ14C ) of microbially-respired CO2, thereby allowing us to determine the age of the organic matter that is being respired. We investigated microbial carbon utilization in sediments from Falmouth, MA and observed a pattern of successive microbial respiration such that several peaks appear over the course of a 7-day incubation. Δ14C signatures of CO2 fractions collected during incubation ranged from -185 to +70‰ with the majority of CO2 appearing to be modern. This indicates that the microbial community is primarily are respiring labile organic matter from fast cycling pools. Interestingly, the observation of multiple peaks with similar Δ14C signatures suggests that organic matter is degraded in a step-wise manner by a succession of microbial taxa. Illumina sequencing of 16S rRNA genes will identify these successions of bacteria (and archaea), while enzymatic analyses may help determine the metabolic pathways that correspond to each peak. Our study will provide a molecular-level framework for organic matter degradation and provide insight into patterns of microbial carbon utilization, linking these observations to genomic and metabolomics information.

Effect of moisture on disintegration kinetics during anaerobic digestion of complex organic substrates.

PubMed

Liotta, Flavia; d'Antonio, Giuseppe; Esposito, Giovanni; Fabbricino, Massimiliano; Frunzo, Luigi; van Hullebusch, Eric D; Lens, Piet N L; Pirozzi, Francesco

2014-01-01

The role of the moisture content and particle size (PS) on the disintegration of complex organic matter during the wet anaerobic digestion (AD) process was investigated. A range of total solids (TS) from 5% to 11.3% and PS from 0.25 to 15 mm was evaluated using carrot waste as model complex organic matter. The experimental results showed that the methane production rate decreased with higher TS and PS. A modified version of the AD model no.1 for complex organic substrates was used to model the experimental data. The simulations showed a decrease of the disintegration rate constants with increasing TS and PS. The results of the biomethanation tests were used to calibrate and validate the applied model. In particular, the values of the disintegration constant for various TS and PS were determined. The simulations showed good agreement between the numerical and observed data.

Synthesis of Amino Acid Precursors with Organic Solids in Planetesimals with Liquid Water

NASA Technical Reports Server (NTRS)

Kebukawa, Y; Misawa, S.; Matsukuma, J.; Chan, Q. H. S.; Kobayashi, J.; Tachibana, S.; Zolensky, M. E.

2017-01-01

Amino acids are important ingredients of life that would have been delivered to Earth by extraterrestrial sources, e.g., comets and meteorites. Amino acids are found in aqueously altered carbonaceous chondrites in good part in the form of precursors that release amino acids after acid hydrolysis. Meanwhile, most of the organic carbon (greater than 70 weight %) in carbonaceous chondrites exists in the form of solvent insoluble organic matter (IOM) with complex macromolecular structures. Complex macromolecular organic matter can be produced by either photolysis of interstellar ices or aqueous chemistry in planetesimals. We focused on the synthesis of amino acids during aqueous alteration, and demonstrated one-pot synthesis of a complex suite of amino acids simultaneously with IOM via hydrothermal experiments simulating the aqueous processing

Leaching of copper and nickel in soil-water systems contaminated by bauxite residue (red mud) from Ajka, Hungary: the importance of soil organic matter.

PubMed

Lockwood, Cindy L; Stewart, Douglas I; Mortimer, Robert J G; Mayes, William M; Jarvis, Adam P; Gruiz, Katalin; Burke, Ian T

2015-07-01

Red mud is a highly alkaline (pH >12) waste product from bauxite ore processing. The red mud spill at Ajka, Hungary, in 2010 released 1 million m(3) of caustic red mud into the surrounding area with devastating results. Aerobic and anaerobic batch experiments and solid phase extraction techniques were used to assess the impact of red mud addition on the mobility of Cu and Ni in soils from near the Ajka spill site. Red mud addition increases aqueous dissolved organic carbon (DOC) concentrations due to soil alkalisation, and this led to increased mobility of Cu and Ni complexed to organic matter. With Ajka soils, more Cu was mobilised by contact with red mud than Ni, despite a higher overall Ni concentration in the solid phase. This is most probably because Cu has a higher affinity to form complexes with organic matter than Ni. In aerobic experiments, contact with the atmosphere reduced soil pH via carbonation reactions, and this reduced organic matter dissolution and thereby lowered Cu/Ni mobility. These data show that the mixing of red mud into organic rich soils is an area of concern, as there is a potential to mobilise Cu and Ni as organically bound complexes, via soil alkalisation. This could be especially problematic in locations where anaerobic conditions can prevail, such as wetland areas contaminated by the spill.

Aqueous Cr(VI) reduction by electrodeposited zero-valent iron at neutral pH: acceleration by organic matters.

PubMed

Liu, Junxi; Wang, Chuan; Shi, Jianying; Liu, Hong; Tong, Yexiang

2009-04-15

This work investigated the effect of co-existing organic matters on aqueous Cr(VI) reduction by electrodeposited zero-valent iron (ED Fe(0)) at neutral pH. The ED Fe(0) prepared in a solution containing mixture of saccharin, L-ascorbic acid and sodium dodecyl sulfate showed higher activity in reducing the aqueous Cr(VI) at neutral pH than that prepared without any organic presence. XRD and SEM indicated that the structure of ED Fe(0) was significantly improved to nano-scale by the presence of organic mixture in the preparation solution. Further, the ED Fe(0) activity in the Cr(VI) reduction at neutral pH was increased by the co-existence of citric acid or oxalic acid in the chromate solution. Electrochemical impedance spectroscopy (EIS) demonstrated that the corrosive current increased with the concentration of organic matter in the reaction solution. With the co-existing organic matters in the preparation solution, the ED Fe(0) corroded more rapidly due to its nano-size, thus the Cr(VI) reduction by the ferrous iron was accelerated. With the co-existing organic matters in the reaction solution, the Cr(VI) reduction was accelerated by a Fe(II) complex as the main electron donor, and a prevention of the passivation due to the Fe(III) and Cr(III) complexes also accelerated the Cr(VI) reduction.

Geochemical controls on vanadium accumulation in fossil fuels

USGS Publications Warehouse

Breit, G.N.; Wanty, R.B.

1989-01-01

High vanadium contents in petroleum and other fossil fuels have been attributed to organic-matter type, organisms, volcanic emanations, diffusion of sea water, and epigenetic enrichment. However, these factors are inadequate to account for the high abundance of vanadium in some fossil fuels and the paucity in others. By examining vanadium deposits in sedimentary rocks with sparse organic matter, constraints are placed on processes controlling vanadium accumulation in organic-rich sediments. Vanadium, as vanadate (V(V)), entered some depositional basins in oxidizing waters from dry, subaerial environments. Upon contact with organic matter in anoxic waters, V(V) is reduced to vanadyl (V(IV)), which can be removed from the water column by adsorption. H2S reduces V(IV) to V(III), which hydrolyzes and precipitates. The lack of V(III) in petroleum suggests that reduction of V(IV) to V(III) is inhibited by organic complexes. In the absence of strong complexing agents, V(III) forms and is incorporated in clay minerals.

Geochemical controls of vanadium accumulation in fossil fuels

USGS Publications Warehouse

Breit, G.N.; Wanty, R.B.

1989-01-01

High vanadium contents in petroleum and other fossil fuels have been attributed to organic-matter type, organisms, volcanic emanations, diffusion of sea water, and epigenetic enrichment. However, these factors are inadequate to account for the high abundance of vanadium in some fossil fuels and the paucity in others. By examining vanadium deposits in sedimentary rocks with sparse organic matter, constraints are placed on processes controlling vanadium accumulation in organic-rich sediments. Vanadium, as vanadate (V(V)), entered some depositional basins in oxidizing waters from dry, subaerial environments. Upon contact with organic matter in anoxic waters, V(V) is reduced to vanadyl (V(IV)), which can be removed from the water column by adsorption. H2S reduces V(IV) to V(III), which hydrolyzes and precipitates. The lack of V(III) in petroleum suggests that reduction of V(IV) to V(III) is inhibited by organic complexes. In the absence of strong complexing agents, V(III) forms and is incorporated in clay minerals.

Origin and distribution of the organic matter in the distal lobe of the Congo deep-sea fan - A Rock-Eval survey

NASA Astrophysics Data System (ADS)

Baudin, François; Stetten, Elsa; Schnyder, Johann; Charlier, Karine; Martinez, Philippe; Dennielou, Bernard; Droz, Laurence

2017-08-01

The Congo River, the second largest river in the world, is a major source of organic matter for the deep Atlantic Ocean because of the connection of its estuary to the deep offshore area by a submarine canyon which feeds a vast deep-sea fan. The lobe zone of this deep-sea fan is the final receptacle of the sedimentary inputs presently channelled by the canyon and covers an area of 2500 km². The quantity and the source of organic matter preserved in recent turbiditic sediments from the distal lobe of the Congo deep-sea fan were assessed using Rock-Eval pyrolysis analyses. Six sites, located at approximately 5000 m water-depth, were investigated. The mud-rich sediments of the distal lobe contain high amounts of organic matter ( 3.5 to 4% Corg), the origin of which is a mixture of terrestrial higher-plant debris, soil organic matter and deeply oxidized phytoplanktonic material. Although the respective contribution of terrestrial and marine sources of organic matter cannot be precisely quantified using Rock-Eval analyses, the terrestrial fraction is dominant according to similar hydrogen and oxygen indices of both suspended and bedload sediments from the Congo River and that deposited in the lobe complex. The Rock-Eval signature supports the 70% to 80% of the terrestrial fraction previously estimated using C/N and δ13Corg data. In the background sediment, the organic matter distribution is homogeneous at different scales, from a single turbiditic event to the entire lobe, and changes in accumulation rates only have a limited effect on the quantity and quality of the preserved organic matter. Peculiar areas with chemosynthetic bivalves and/or bacterial mats, explored using ROV Victor 6000, show a Rock-Eval signature similar to background sediment. This high organic carbon content associated to high sedimentation rates (> 2 to 20 mm.yr-1) in the Congo distal lobe complex implies a high burial rate for organic carbon. Consequently, the Congo deep-sea fan represents an enormous sink of terrestrial organic matter when compared to other turbiditic systems over the world.

PHOTOCHEICAL PRODUCTION OF HYDROXYL RADICAL IN NATURAL WATER - THE ROLE OF IRON AND DISSOLVED ORGANIC MATTER

EPA Science Inventory

Photochemical hydroxyl radical (OH) production was measured in several natural waters to investigate the importance of colored dissolved organic matter (CDOM) and iron-CDOM complexes as sources of OH. High rates of OH photoproduction in highly colored, iron-rich, acidic waters a...

Energy Transformations of Soil Organic Matter in a Changing World

NASA Astrophysics Data System (ADS)

Herrmann, A. M.; Coucheney, E.; Grice, S. M.; Ritz, K.; Harris, J.

2011-12-01

The role of soils in governing the terrestrial carbon balance is acknowledged as being important but remains poorly understood within the context of climate change. Soils exchange energy with their surroundings and are therefore open systems thermodynamically, but little is known how energy transformations of decomposition processes are affected by temperature. Soil organic matter and the soil biomass can be conceptualised as analogous to the 'fuel' and 'biological engine' of the earth, respectively, and are pivotal in driving the belowground carbon cycle. Thermodynamic principles of soil organic matter decomposition were evaluated by means of isothermal microcalorimetry (TAM Air, TA Instruments, Sollentuna Sweden: (i) Mineral forest soils from the Flakaliden long-term nitrogen fertilisation experiment (Sweden) were amended with a range of different substrates representing structurally simple to complex, ecologically pertinent organic matter and heat signatures were determined at temperatures between 5 and 25°C. (ii) Thermodynamic and resource-use efficiencies of the biomass were determined in arable soils which received contrasting long-term management regimes with respect to organic matter and nitrogen since 1956. The work showed that (i) structurally labile components have higher activation energy and temperature dependence than structurally more complex organic components. This is, however, in contrast to the thermodynamic argument which suggests the opposite that reactions metabolising structurally complex, aromatic components have higher temperature dependence than reactions metabolising structurally more labile components. (ii) Microbial communities exposed to long-term stress by heavy metal and low pH were less thermodynamic efficient and showed a decrease in resource-use efficiency in comparison with conventional input regimes. Differences in efficiencies were mirrored in both the phenotypic and functional profiles of the communities. We will present our findings illustrating the capacity of isothermal microcalorimetry to evaluate temperature dependencies of soil organic matter decomposition, associated energy transformations and thermodynamic principles in soil ecosystems.

A Robust Analysis Method For Δ13c Signal Of Bulk Organic Matter In Speleothems

NASA Astrophysics Data System (ADS)

Bian, F.; Blyth, A. J.; Smith, C.; Baker, A.

2017-12-01

Speleothems preserve organic matter that is derived from both the surface soil and cave environments. This organic matter can be used to understand paleoclimate and paleoenvironments. However, a stable and quick micro-analysis method to measure the δ13C signals from speleothem organic matter separate from the total δ13C remains absent. And speleothem organic geochemistry is still relatively unexplored compared to inorganic geochemistry. In this research, for the organic matter analysis, bulk homogeneous power samples were obtained from one large stalagmite. These were dissolved by phosphoric acid to produce the aqueous solution. Then, the processed solution was degassed through a rotational vacuum concentrator. A liquid chromatograph was coupled to IRMS to control the oxidization and the measurement of analytes. This method is demonstrated to be robust for the analysis of speleothem d13C organic matter analysis under different preparation and instrumental settings, with the low standard deviation ( 0.2‰), and low sample consumption (<25 mg). Considering the complexity of cave environments, this method will be useful in further investigations the δ13C of entrapped organic matter and environmental controls in other climatic and ecological contexts, including the determination of whether vegetation or soil microbial activity is the dominant control on speleothem d13C of organic matter.

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,…

Major structural components in freshwater dissolved organic matter.

PubMed

Lam, Buuan; Baer, Andrew; Alaee, Mehran; Lefebvre, Brent; Moser, Arvin; Williams, Antony; Simpson, André J

2007-12-15

Dissolved organic matter (DOM) contains a complex array of chemical components that are intimately linked to many environmental processes, including the global carbon cycle, and the fate and transport of chemical pollutants. Despite its importance, fundamental aspects, such as the structural components in DOM remain elusive, due in part to the molecular complexity of the material. Here, we utilize multidimensional nuclear magnetic resonance spectroscopy to demonstrate the major structural components in Lake Ontario DOM. These include carboxyl-rich alicyclic molecules (CRAM), heteropolysaccharides, and aromatic compounds, which are consistent with components recently identified in marine dissolved organic matter. In addition, long-range proton-carbon correlations are obtained for DOM, which support the existence of material derived from linear terpenoids (MDLT). It is tentatively suggested that the bulk of freshwater dissolved organic matter is aliphatic in nature, with CRAM derived from cyclic terpenoids, and MDLT derived from linear terpenoids. This is in agreement with previous reports which indicate terpenoids as major precursors of DOM. At this time it is not clear in Lake Ontario whether these precursors are of terrestrial or aquatic origin or whether transformations proceed via biological and/ or photochemical processes.

Activation energy and energy density: a bioenergetic framework for assessing soil organic matter stability

NASA Astrophysics Data System (ADS)

Williams, E. K.; Plante, A. F.

2017-12-01

The stability and cycling of natural organic matter depends on the input of energy needed to decompose it and the net energy gained from its decomposition. In soils, this relationship is complicated by microbial enzymatic activity which decreases the activation energies associated with soil organic matter (SOM) decomposition and by chemical and physical protection mechanisms which decreases the concentrations of the available organic matter substrate and also require additional energies to overcome for decomposition. In this study, we utilize differential scanning calorimetry and evolved CO2 gas analysis to characterize differences in the energetics (activation energy and energy density) in soils that have undergone degradation in natural (bare fallow), field (changes in land-use), chemical (acid hydrolysis), and laboratory (high temperature incubation) experimental conditions. We will present this data in a novel conceptual framework relating these energy dynamics to organic matter inputs, decomposition, and molecular complexity.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

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

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

DOE PAGES

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

2016-09-16

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

Storage and Bioavailability of Molybdenum in Soils Increased by Organic Matter Complexation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wichard, T.; Mishra, B; Myneni, S

2009-01-01

The micronutrient molybdenum is a necessary component of the nitrogen-fixing enzyme nitrogenase1, 2. Molybdenum is very rare in soils, and is usually present in a highly soluble form, making it susceptible to leaching3, 4. However, it is generally thought that molybdenum attaches to mineral surfaces in acidic soils; this would prevent its escape into the groundwater, but would also impede uptake by microbes3. Here we use X-ray spectroscopy to examine the chemical speciation of molybdenum in soil samples from forests in Arizona and New Jersey. We show that in the leaf litter layer, most of the molybdenum forms strong complexesmore » with plant-derived tannins and tannin-like compounds; molybdenum binds to these organic ligands across a wide pH range. In deeper soils, molybdenum binds to both iron oxides and natural organic matter. We suggest that the molybdenum bound to organic matter can be captured by small complexing agents that are released by nitrogen-fixing bacteria; the molybdenum can then be incorporated into nitrogenase. We conclude that the binding of molybdenum to natural organic matter helps prevent leaching of molybdenum, and is thus a critical step in securing new nitrogen in terrestrial ecosystems.« less

Effects of soil temperature, flooding, and organic matter addition on N2O emissions from a soil of Hongze Lake wetland, China.

PubMed

Lu, Yan; Xu, Hongwen

2014-01-01

The objectives of this study were to test the effects of soil temperature, flooding, and raw organic matter input on N2O emissions in a soil sampled at Hongze Lake wetland, Jiangsu Province, China. The treatments studied were-peat soil (I), peat soil under flooding (II), peat soil plus raw organic matter (III), and peat soil under flooding plus organic matter. These four treatments were incubated at 20°C and 35°C. The result showed that temperature increase could enhance N2O emissions rate and cumulative emissions significantly; moreover, the flooded soil with external organic matter inputs showed the lowest cumulative rise in N2O emissions due to temperature increment. Flooding might inhibit soil N2O emissions, and the inhibition was more pronounced after organic matter addition to the original soil. Conversely, organic matter input explained lower cumulative N2O emissions under flooding. Our results suggest that complex interactions between flooding and other environmental factors might appear in soil N2O emissions. Further studies are needed to understand potential synergies or antagonisms between environmental factors that control N2O emissions in wetland soils.

Role of Organic Matter in the Removal of Heavy Metals in Stormwater Runoff

NASA Astrophysics Data System (ADS)

Barrett, M.; Ingenloff, C.; Katz, L.

2011-12-01

Heavy metals (copper, zinc, and lead) are common constituents in highway runoff and concentrations in runoff from highway facilities are particularly high. These concentrations are also generally higher than observed in natural water bodies and several studies have demonstrated acute and chronic toxicity to aquatic ecosystems. One focus of this project is to assess the potential of sorption to reduce the concentration of metals in runoff. The difficulty evaluating adsorption in multi-component systems is to capture the impacts of background organic matter and other complexing ions on adsorption behavior. Very few studies have evaluated the ability of surface complexation models to predict adsorption in systems that contain organic matter from highway runoff. Moreover, the composition of the organic matter in stormwater runoff can be significantly different from natural organic matter typically used to assess the impact of background organics on metal ion adsorption. This research project specifically addresses these concerns and examines the impact of highway runoff on the adsorption behavior to determine whether existing surface complexation and chemical speciation models and parameter databases can be used to predict adsorption of target metal ions in these waters. Previous research has employed both actual storm water that has been obtained from actual field highway runoff sites as well as synthetic storm water compositions that have attempted to mimic the major components of natural storm water. Researchers and practitioners in the field generally agree on the importance of capturing the background water matrix; however, concerns associated with required volumes, holding times, aging, consistency and temporal and spatial variability often favor the use of synthetic formulations. While synthetic storm water can achieve the required consistency, numerous artifacts can be introduced due to the high reactivity of trace metal ions with background inorganic and organic ligands. Of particular concern, is the background organic matrix associated with stormwater. While most of the inorganic composition of natural stormwater can be adequately characterized using routine analytical procedures, characterization of organic matter to the same level of detail is not possible. Indeed, methods for characterization of natural organic matter typically only provide operational definitions of the composition. A compromise between using natural and synthetic storm water was therefore made by recognizing the importance of capturing the organic matter from natural storm water, but adding the flexibility of using synthetic storm water to provide the ionic composition. To alleviate concerns associated with storing large volumes and aging of organic solutions, the storm water was concentrated within twenty-four hours of collection using reverse osmosis and then freeze-dried. The freeze-dried organic matter will be reconstituted as needed at concentrations that mimic the initial total organic concentration of the stormwater when it was collected. This paper provides detailed guidance for the preparation of a synthetic water that can be used to simulate stormwater composition.

Wood Smoke

EPA Pesticide Factsheets

Smoke is made up of a complex mixture of gases and fine, microscopic particles produced when wood and other organic matter burn. The biggest health threat from wood smoke comes from fine particles (also called particulate matter).

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.

Organic nitrogen storage in mineral soil: Implications for policy and management.

PubMed

Bingham, Andrew H; Cotrufo, M Francesca

2016-05-01

Nitrogen is one of the most important ecosystem nutrients and often its availability limits net primary production as well as stabilization of soil organic matter. The long-term storage of nitrogen-containing organic matter in soils was classically attributed to chemical complexity of plant and microbial residues that retarded microbial degradation. Recent advances have revised this framework, with the understanding that persistent soil organic matter consists largely of chemically labile, microbially processed organic compounds. Chemical bonding to minerals and physical protection in aggregates are more important to long-term (i.e., centuries to millennia) preservation of these organic compounds that contain the bulk of soil nitrogen rather than molecular complexity, with the exception of nitrogen in pyrogenic organic matter. This review examines for the first time the factors and mechanisms at each stage of movement into long-term storage that influence the sequestration of organic nitrogen in the mineral soil of natural temperate ecosystems. Because the factors which govern persistence are different under this newly accepted paradigm we examine the policy and management implications that are altered, such as critical load considerations, nitrogen saturation and mitigation consequences. Finally, it emphasizes how essential it is for this important but underappreciated pool to be better quantified and incorporated into policy and management decisions, especially given the lack of evidence for many soils having a finite capacity to sequester nitrogen. Published by Elsevier B.V.

Ultrafiltration for the Determination of Cu Complexed with Dissolved Organic Matters of Different Molecular Weight from a Eutrophic River, China.

PubMed

Li, Anding; Zhang, Yan; Zhou, Beihai; Xin, Kailing; Gu, Yingnan; Xu, Weijie; Tian, Jie

2018-05-21

The molecular weight of dissolved organic matter (DOM) is one of the essential factors controlling the properties of metal complexes. A continuous ultrafiltration experiment was designed to study the properties of Cu complexes with different molecular weights in a river before and after eutrophication. The results showed that the concentration of DOM increased from 26.47 to 38.20 mg/L during the eutrophication process, however, DOM was still dominated by the small molecular weight fraction before and after eutrophication. The amount of Cu-DOM complexes increased with the increasing of molecular weight, however, the amounts of DOM-Cu complexes before eutrophication were higher than those after eutrophication. This is because DOM contained more -COOH and -OH before eutrophication and these functional groups are the active sites complexed with Cu.

Linking aboveground net primary productivity to soil carbon and dissolved organic carbon in complex terrain

Treesearch

F.S. Peterson; K. Lajtha

2013-01-01

Factors influencing soil organic matter (SOM) stabilization and dissolved organic carbon (DOC) content in complex terrain, where vegetation, climate, and topography vary over the scale of a few meters, are not well understood. We examined the spatial correlations of lidar and geographic information system-derived landscape topography, empirically measured soil...

The size-reactivity continuum of major bioelements in the ocean.

PubMed

Benner, Ronald; Amon, Rainer M W

2015-01-01

Most of the carbon fixed in primary production is rapidly cycled and remineralized, leaving behind various forms of organic carbon that contribute to a vast reservoir of nonliving organic matter in seawater. Most of this carbon resides in dissolved molecules of varying bioavailability and reactivity, and aspects of the cycling of this carbon remain an enigma. The size-reactivity continuum model provides a conceptual framework for understanding the mechanisms governing the formation and mineralization of this carbon. In the seawater bioassay experiments that served as the original basis for this model, investigators observed that larger size classes of organic matter were more bioavailable and more rapidly remineralized by microbes than were smaller size classes. Studies of the chemical composition and radiocarbon content of marine organic matter have further indicated that the complexity and age of organic matter increase with decreasing molecular size. Biodegradation processes appear to shape the size distribution of organic matter and the nature of the small dissolved molecules that persist in the ocean.

Multi-spectroscopic investigation on the complexation of tetracycline with dissolved organic matter derived from algae and macrophyte.

PubMed

Bai, Leilei; Zhao, Zhen; Wang, Chunliu; Wang, Changhui; Liu, Xin; Jiang, Helong

2017-11-01

Interactions of antibiotics with algae-derived dissolved organic matter (ADOM) and macrophyte-derived dissolved organic matter (MDOM) are of vital importance to the transport and ecotoxicity of antibiotics in eutrophic freshwater lakes. Multi-spectroscopic techniques were used to investigate the complexation of tetracycline (TTC) with ADOM and MDOM collected from Lake Taihu (China). The 3 fluorescent components, tyrosine-, tryptophan-, and humic-like component, were identified by excitation emission matrix spectra with parallel factor analysis. Their fluorescence was quenched at different degree by TTC titration through static quenching. The complexation of TTC induced conformational changes in DOM fractions. Synchronous fluorescence spectra combined with two dimensional correlation spectroscopy further suggested that the formation of TTC-DOM complexes occurred on the sequential order of tryptophan-like→tyrosine-like→humic-like component. The effective quenching constants of tryptophan- and tyrosine-like component were similar, higher than those of humic-like component. The strong binding ability and abundant content of protein-like substances indicated their prominent role in the TTC-DOM complexation. Fourier transform infrared spectroscopy further revealed that the heterogeneous functional groups, including amide I and II, aromatics, and aliphatics, were responsible for the complexation. These results highlight the significant impact of the overgrowth of algae and macrophyte on the environmental behavior of antibiotics in waters. Copyright © 2017 Elsevier Ltd. All rights reserved.

Enhanced dissolution of cinnabar (mercuric sulfide) by dissolved organic matter isolated from the Florida Everglades

USGS Publications Warehouse

Ravichandran, Mahalingam; Aiken, George R.; Reddy, Michael M.; Ryan, Joseph N.

1998-01-01

Organic matter isolated from the Florida Everglades caused a dramatic increase in mercury release (up to 35 μM total dissolved mercury) from cinnabar (HgS), a solid with limited solubility. Hydrophobic (a mixture of both humic and fulvic) acids dissolved more mercury than hydrophilic acids and other nonacid fractions of dissolved organic matter (DOM). Cinnabar dissolution by isolated organic matter and natural water samples was inhibited by cations such as Ca2+. Dissolution was independent of oxygen content in experimental solutions. Dissolution experiments conducted in DI water (pH = 6.0) had no detectable (<2.5 nM) dissolved mercury. The presence of various inorganic (chloride, sulfate, or sulfide) and organic ligands (salicylic acid, acetic acid, EDTA, or cysteine) did not enhance the dissolution of mercury from the mineral. Aromatic carbon content in the isolates (determined by 13C NMR) correlated positively with enhanced cinnabar dissolution. ζ-potential measurements indicated sorption of negatively charged organic matter to the negatively charged cinnabar (pHpzc = 4.0) at pH 6.0. Possible mechanisms of dissolution include surface complexation of mercury and oxidation of surface sulfur species by the organic matter.

Extraction and characterization of ternary complexes between natural organic matter, cations, and oxyanions from a natural soil.

PubMed

Peel, Hannah R; Martin, David P; Bednar, Anthony J

2017-06-01

Natural organic matter (NOM) can have a significant influence on the mobility and fate of inorganic oxyanions, such as arsenic and selenium, in the environment. There is evidence to suggest that interactions between NOM and these oxyanions are facilitated by bridging cations (primarily Fe 3+ ) through the formation of ternary complexes. Building on previous work characterizing ternary complexes formed in the laboratory using purified NOM, this study describes the extraction and characterization of intact ternary complexes directly from a soil matrix. The complexes are stable to the basic extraction conditions (pH 12) and do not appear to change when the pH of the extract is adjusted back to neutral. The results suggest that ternary complexes between NOM, cations, and inorganic oxyanions exist in natural soils and could play a role in the speciation of inorganic oxyanions in environmental matrices. Published by Elsevier Ltd.

Effect of soil properties on pure and formulated mesotrione adsorption onto vertisol (Limagne plane, Puy-de-Dôme, France).

PubMed

Alekseeva, Tatiana; Kolyagin, Yury; Sancelme, Martine; Besse-Hoggan, Pascale

2014-09-01

The fate of ionisable pesticides in the environment is complex as it is importantly related to many soil properties: pH, mineralogy, organic matter content and other soil characteristics. The adsorption of a weak acid herbicide, mesotrione, was studied in detail on whole and peroxide-treated vertisol topsoil and also on its granulometric fractions (clay, silt, sand) to evaluate the role of mineralogy and different organic matter pools. The soil studied is alkaline silty loam with smectite as the main clay mineral. It contains 1.7% organic carbon, mostly stabilized as a complex with smectite. Humus is of fulvic type. Mesotrione adsorption occurs on both mineral and organic constituents. Adsorption is weak and mesotrione can be easily and totally desorbed. As shown with (13)C NMR experiments, adsorption best correlates with the alkyl and carboxylic carbon content, and occurs on both bound and free organic matter. No difference of mesotrione sorption was observed with the formulation Callisto®. Copyright © 2014 Elsevier Ltd. All rights reserved.

Organic geochemistry and brine composition in Great Salt, Mono, and Walker Lakes

USGS Publications Warehouse

Domagalski, Joseph L.; Orem, W.H.; Eugster, H.P.

1989-01-01

Samples of Recent sediments, representing up to 1000 years of accumulation, were collected from three closed basin lakes (Mono Lake, CA, Walker Lake, NV, and Great Salt Lake, UT) to assess the effects of brine composition on the accumulation of total organic carbon, the concentration of dissolved organic carbon, humic acid structure and diagenesis, and trace metal complexation. The Great Salt Lake water column is a stratified Na-Mg-Cl-SO4 brine with low alkalinity. Algal debris is entrained in the high density (1.132-1.190 g/cc) bottom brines, and in this region maximum organic matter decomposition occurs by anaerobic processes, with sulfate ion as the terminal electron acceptor. Organic matter, below 5 cm of the sediment-water interface, degrades at a very slow rate in spite of very high pore-fluid sulfate levels. The organic carbon concentration stabilizes at 1.1 wt%. Mono Lake is an alkaline (Na-CO3-Cl-SO4) system. The water column is stratified, but the bottom brines are of lower density relative to the Great Salt Lake, and sedimentation of algal debris is rapid. Depletion of pore-fluid sulfate, near l m of core, results in a much higher accumulation of organic carbon, approximately 6 wt%. Walker Lake is also an alkaline system. The water column is not stratified, and decomposition of organic matter occurs by aerobic processes at the sediment-water interface and by anaerobic processes below. Total organic carbon and dissolved organic carbon concentrations in Walker Lake sediments vary with location and depth due to changes in input and pore-fluid sulfate concentrations. Nuclear magnetic resonance studies (13C) of humic substances and dissolved organic carbon provide information on the source of the Recent sedimentary organic carbon (aquatic vs. terrestrial), its relative state of decomposition, and its chemical structure. The spectra suggest an algal origin with little terrestrial signature at all three lakes. This is indicated by the ratio of aliphatic to aromatic carbon and the absence of chemical structures indicative of the lignin of vascular plants. The dissolved organic carbon of the Mono Lake pore fluids is structurally related to humic acid and is also related to carbohydrate metabolism. The alkaline pore fluids, due to high pH, solubilize high molecular weight organic matter from the sediments. This hydrophilic material is a metal complexing agent. Despite very high algal productivities, organic carbon accumulation can be low in stratified lakes if the anoxic bottom waters are hypersaline with high concentrations of sulfate ion. Labile organic matter is recycled to the water column and the sedimentary organic matter is relatively nonsusceptible to bacterial metabolism. As a result, pore-fluid dissolved organic carbon and metal-organic complexation are low. ?? 1989.

One-pot synthesis of amino acid precursors with insoluble organic matter in planetesimals with aqueous activity.

PubMed

Kebukawa, Yoko; Chan, Queenie H S; Tachibana, Shogo; Kobayashi, Kensei; Zolensky, Michael E

2017-03-01

The exogenous delivery of organic molecules could have played an important role in the emergence of life on the early Earth. Carbonaceous chondrites are known to contain indigenous amino acids as well as various organic compounds and complex macromolecular materials, such as the so-called insoluble organic matter (IOM), but the origins of the organic matter are still subject to debate. We report that the water-soluble amino acid precursors are synthesized from formaldehyde, glycolaldehyde, and ammonia with the presence of liquid water, simultaneously with macromolecular organic solids similar to the chondritic IOM. Amino acid products from hydrothermal experiments after acid hydrolysis include α-, β-, and γ-amino acids up to five carbons, for which relative abundances are similar to those extracted from carbonaceous chondrites. One-pot aqueous processing from simple ubiquitous molecules can thus produce a wide variety of meteoritic organic matter from amino acid precursors to macromolecular IOM in chondrite parent bodies.

Organic matter in hydrothermal metal ores and hydrothermal fluids

USGS Publications Warehouse

Orem, W.H.; Spiker, E. C.; Kotra, R.K.

1990-01-01

Massive polymetallic sulfides are currently being deposited around active submarine hydrothermal vents associated with spreading centers. Chemoautolithotrophic bacteria are responsible for the high production of organic matter also associated with modern submarine hydrothermal activity. Thus, there is a significant potential for organic matter/metal interactions in these systems. We have studied modern and ancient hydrothermal metal ores and modern hydrothermal fluids in order to establish the amounts and origin of the organic matter associated with the metal ores. Twenty-six samples from modern and ancient hydrothermal systems were surveyed for their total organic C contents. Organic C values ranged from 0.01% to nearly 4.0% in these samples. Metal ores from modern and ancient sediment-covered hydrothermal systems had higher organic C values than those from modern and ancient hydrothermal systems lacking appreciable sedimentary cover. One massive pyrite sample from the Galapagos spreading center (3% organic C) had stable isotope values of -27.4% (??13C) and 2.1% (??15N), similar to those in benthic siphonophors from active vents and distinct from seep sea sedimentary organic matter. This result coupled with other analyses (e.g. 13C NMR, pyrolysis/GC, SEM) of this and other samples suggests that much of the organic matter may originate from chemoautolithotrophic bacteria at the vents. However, the organic matter in hydrothermal metal ores from sediment covered vents probably arises from complex sedimentary organic matter by hydrothermal pyrolysis. The dissolved organic C concentrations of hydrothermal fluids from one site (Juan de Fuca Ridge) were found to be the same as that of background seawater. This result may indicate that dissolved organic C is effectively scavenged from hydrothermal fluids by biological activity or by co-precipitation with metal ores. ?? 1990.

Phenanthrene sorption with heterogeneous organic matter in a landfill aquifer material

USGS Publications Warehouse

Karapanagioti, H.K.; Sabatini, D.A.; Kleineidam, S.; Grathwohl, P.; Ligouis, B.

1999-01-01

Phenanthrene was used as a model chemical to study the sorption properties of Canadian River Alluvium aquifer material. Both equilibrium and kinetic sorption processes were evaluated through batch studies. The bulk sample was divided into subsamples with varying properties such as particle size, organic content, equilibration time, etc. in order to determine the effect of these properties on resulting sorption parameters. The data have been interpreted and the effect of experimental variables was quantified using the Freundlich isotherm model and a numerical solution of Fick's 2nd law in porous media. Microscopic organic matter characterization proved to be a valuable tool for explaining the results. Different organic matter properties and sorption mechanisms were observed for each soil subsample. Samples containing coal particles presented high Koc values. Samples with organic matter dominated by organic coatings on quartz grains presented low Koc values and contained a high percentage of fast sorption sites. The numerical solution of Fick's 2ndlaw requires the addition of two terms (fast and slow) in order to fit the kinetics of these heterogeneous samples properly. These results thus demonstrate the need for soil organic matter characterization in order to predict and explain the sorption properties of a soil sample containing heterogeneous organic matter and also the difficulty and complexity of modeling sorption in such samples.

Hydrolytic microbial communities in terrestrial ecosystems

NASA Astrophysics Data System (ADS)

Manucharova, Natalia; Chernov, Timofey; Kolcova, Ekaterina; Zelezova, Alena; Lukacheva, Euhenia; Zenova, Galina

2014-05-01

Hydrolytic microbial communities in terrestrial ecosystems Manucharova N.A., Chernov T.I., Kolcova E.M., Zelezova A.D., Lukacheva E.G. Lomonosov Moscow State University, Russia Vertical differentiation of terrestrial biogeocenoses is conditioned by the formation of vertical tiers that differ considerably in the composition and structure of microbial communities. All the three tiers, phylloplane, litter and soil, are united by a single flow of organic matter, and are spatially separated successional stages of decomposition of organic substances. Decomposition of organic matter is mainly due to the activity of microorganisms producing enzymes - hydrolase and lyase - which destroy complex organic compounds. Application of molecular biological techniques (FISH) in environmental studies provides a more complete information concerning the taxonomic diversity and potential hydrolytic activity of microbial complexes of terrestrial ecosystems that exist in a wide range of environmental factors (moisture, temperature, redox potential, organic matter). The combination of two molecular biological techniques (FISH and DGGE-analysis of fragments of gene 16S rRNA total amplificate) enables an informative assessment of the differences in the structure of dominant and minor components of hydrolytic complexes formed in different tiers of terrestrial ecosystems. The functional activity of hydrolytic microbial complexes of terrestrial ecosystems is determined by the activity of dominant and minor components, which also have a high gross enzymatic activity. Degradation of biopolymers in the phylloplane is mainly due to the representatives of the Proteobacteria phylogenetic group (classes alpha and beta). In mineral soil horizons, the role of hydrolytic representatives of Firmicutes and Actinobacteria increases. Among the key environmental parameters that determine the functional activity of the hydrolytic (chitinolytic) complex of soil layer (moisture, nutrient supply, successional time), the most significant one is moisture. Moisture levels providing maximum activity of a hydrolytic microbial complex depend on the soil type. Development of a hydrolytic microbial complex occurs in a very wide moisture range - from values close to field capacity to those close to the wilting moisture point. The functional role of mycelial actinobacteria in the metabolism of chitin consists, on the one hand, in active decomposition of this biopolymer, and on the other hand, in the regulation of microbial hydrolytic complex activity through the production of biologically active regulatory metabolites, which occurs in a wide range of environmental parameters (moisture, temperature, organic matter, successional time). Experimental design is applicable to identify in situ optimal values of environmental factors that considerably affect the functional parameters of hydrolytic microbial complexes.

Method of loading organic materials with group III plus lanthanide and actinide elements

DOEpatents

Bell, Zane W [Oak Ridge, TN; Huei-Ho, Chuen [Oak Ridge, TN; Brown, Gilbert M [Knoxville, TN; Hurlbut, Charles [Sweetwater, TX

2003-04-08

Disclosed is a composition of matter comprising a tributyl phosphate complex of a group 3, lanthanide, actinide, or group 13 salt in an organic carrier and a method of making the complex. These materials are suitable for use in solid or liquid organic scintillators, as in x-ray absorption standards, x-ray fluorescence standards, and neutron detector calibration standards.

Organic matter accumulation and community change at the peatland-upland interface: inferences from 14C and 210Pb dated profiles

Treesearch

Ilka E. Bauer; Jagtar S. Bhatti; Christopher Swanston; R. Kelman Wieder; Caroline M. Perston

2009-01-01

Peatland-margin habitats with organic matter accumulation of 40-150 cm make up a significant but poorly quantified portion of Canada's boreal forest region. Spanning the transition between non-wetland forest and fen proper, these ecosystems represent a zone of complex environmental and vegetation change, yet little is known about their ecological function or...

Temporal evolution of cadmium, copper and lead concentration in the Venice Lagoon water in relation with the speciation and dissolved/particulate partition.

PubMed

Morabito, Elisa; Radaelli, Marta; Corami, Fabiana; Turetta, Clara; Toscano, Giuseppa; Capodaglio, Gabriele

2018-04-01

In order to study the role of sediment re-suspension and deposition versus the role of organic complexation, we investigated the speciation of cadmium (Cd), copper (Cu) and lead (Pb) in samples collected in the Venice Lagoon during several campaigns from 1992 to 2006. The increment in Cd and Pb concentration in the dissolved phases, observed in the central and northern basins, can be linked to important alterations inside the lagoon caused by industrial and urban factors. The study focuses on metal partition between dissolved and particulate phases. The analyses carried out in different sites illustrate the complex role of organic matter in the sedimentation process. While Cd concentration in sediments can be correlated with organic matter, no such correlation can be established in the case of Pb, whose particulate concentration is related only to the dissolved concentration. In the case of Cu, the role of organic complexation remains unclear. Copyright © 2017 Elsevier Ltd. All rights reserved.

From precision polymers to complex materials and systems

NASA Astrophysics Data System (ADS)

Lutz, Jean-François; Lehn, Jean-Marie; Meijer, E. W.; Matyjaszewski, Krzysztof

2016-05-01

Complex chemical systems, such as living biological matter, are highly organized structures based on discrete molecules in constant dynamic interactions. These natural materials can evolve and adapt to their environment. By contrast, man-made materials exhibit simpler properties. In this Review, we highlight that most of the necessary elements for the development of more complex synthetic matter are available today. Using modern strategies, such as controlled radical polymerizations, supramolecular polymerizations or stepwise synthesis, polymers with precisely controlled molecular structures can be synthesized. Moreover, such tailored polymers can be folded or self-assembled into defined nanoscale morphologies. These self-organized macromolecular objects can be at thermal equilibrium or can be driven out of equilibrium. Recently, in the latter case, interesting dynamic materials have been developed. However, this is just a start, and more complex adaptive materials are anticipated.

Accumulation of organic matter in the in the Rome trough of the Appalachian basin and its subsequent thermal history

DOE Office of Scientific and Technical Information (OSTI.GOV)

Curtis, J.B.; Faure, G.

1997-03-01

We used geochemical data to examine the origin and preservation of organic matter contained in the lower part of the Huron Member of the Ohio Shale formation and the Rhinestreet Shale Member of the West Falls Formation (Devonian) in Kentucky, Ohio, West Virginia, and Virginia. The thermal history of the organic matter was determined by relating relative temperatures experienced by the organic matter to the geologic setting. The organic matter in these formations is predominantly marine in origin and was most probably derived largely from algal organisms. Although the rate of production of marine organic matter may have been uniformmore » within the basin, its preservation apparently was controlled by the existence of a set of fault-bounded anoxic subbasins associated with the Rome trough, a Cambrian structural complex. These subbasins apparently were anoxic because they limited oxygen recharge by circulating waters. Preservation of organic matter was also enhanced by periodic blooms of the alga Tasmanites and similar organisms in the waters above the subbasins during both early Huron and Rhinestreet deposition. A significant negative correlation was identified between the vitrinite reflectance peak temperature, and integrated measure of the thermal history of a rock, and the hydrogen index, a measure of the remaining hydrocarbon-generation potential of kerogen. Although peak temperatures were controlled by burial depth, excess heating occurred locally, perhaps by hot brines rising from depth through fractures associated with major structures in the study area.« less

Measuring organic matter in Everglades wetlands and the Everglades Agricultural Area

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wright, Alan L.; Hanlon, Edward A.

Here, organic matter is a complex material that represents the long-term decay products from plants and other organisms in the soil. When organic matter is allowed to build up in a soil, the soil color at the surface usually turns a darker color, often with a red or brown hue. Typically in Florida mineral soils, organic matter content is quite low, within the range of 1 to 5%. However, in some soils that remain flooded for most of the year, organic matter can build up with time and actually become the soil. Such is the case for the organic soils,more » or histosols, found in southern Florida. These organic soils comprise much of the Water Conservation Areas, Everglades National Park (ENP), Big Cypress Basin, and the Everglades Agricultural Area (EAA). It is important to document organic matter accumulation in the Everglades to gauge the effectiveness of wetland creation and succession. For the EAA, the drained soils lose organic matter due to oxidation, so measurement of the organic matter content of these soils over the course of time indicates the oxidation potential and mineral incorporation from bedrock. Due to the wide diversity of soil types and methods of measuring soil organic matter, there is a need to devise a more universal method applicable to many types of histosols in south Florida. The intent of this publication is: 1.To describe a simple laboratory method for determining the organic matter content of the organic soils of southern Florida and demonstrate the importance of using this new procedure for improved accuracy and precision; 2.To utilize this updated laboratory procedure for field sites across Everglades wetlands and the EAA; and 3. To recommend this procedure be used by growers, state and federal agencies, and university and agency researchers dealing with the management of organic soils in southern Florida. Growers can use this improvement to organic matter measurement to keep lab testing costs low while getting a better, more quantitative estimate of organic carbon (organic matter) for decisions regarding pesticide applications and estimated contribution of nutrients released from the organic matter in their fields. Restoration efforts in the Everglades wetlands can be better documented with the lower cost, but now equally as useful, LOI test for organic carbon. Improvements to soil organic matter coupled with other measurements of biological health of the system can be documented with less work using the adjusted LOI calculations.« less

Delivery of complex organic compounds from evolved stars to the solar system.

PubMed

Kwok, Sun

2011-12-01

Stars in the late stages of evolution are able to synthesize complex organic compounds with aromatic and aliphatic structures over very short time scales. These compounds are ejected into the interstellar medium and distributed throughout the Galaxy. The structures of these compounds are similar to the insoluble organic matter found in meteorites. In this paper, we discuss to what extent stellar organics has enriched the primordial Solar System and possibly the early Earth.

Quantifying the degradation of organic matter in marine sediments: A review and synthesis

NASA Astrophysics Data System (ADS)

Arndt, Sandra; Jørgensen, B. B.; LaRowe, D. E.; Middelburg, J. J.; Pancost, R. D.; Regnier, P.

2013-08-01

Quantifying the rates of biogeochemical processes in marine sediments is essential for understanding global element cycles and climate change. Because organic matter degradation is the engine behind benthic dynamics, deciphering the impact that various forces have on this process is central to determining the evolution of the Earth system. Therefore, recent developments in the quantitative modeling of organic matter degradation in marine sediments are critically reviewed. The first part of the review synthesizes the main chemical, biological and physical factors that control organic matter degradation in sediments while the second part provides a general review of the mathematical formulations used to model these processes and the third part evaluates their application over different spatial and temporal scales. Key transport mechanisms in sedimentary environments are summarized and the mathematical formulation of the organic matter degradation rate law is described in detail. The roles of enzyme kinetics, bioenergetics, temperature and biomass growth in particular are highlighted. Alternative model approaches that quantify the degradation rate constant are also critically compared. In the third part of the review, the capability of different model approaches to extrapolate organic matter degradation rates over a broad range of temporal and spatial scales is assessed. In addition, the structure, functions and parameterization of more than 250 published models of organic matter degradation in marine sediments are analyzed. The large range of published model parameters illustrates the complex nature of organic matter dynamics, and, thus, the limited transferability of these parameters from one site to another. Compiled model parameters do not reveal a statistically significant correlation with single environmental characteristics such as water depth, deposition rate or organic matter flux. The lack of a generic framework that allows for model parameters to be constrained in data-poor areas seriously limits the quantification of organic matter degradation on a global scale. Therefore, we explore regional patterns that emerge from the compiled more than 250 organic matter rate constants and critically discuss them in their environmental context. This review provides an interdisciplinary view on organic matter degradation in marine sediments. It contributes to an improved understanding of global patterns in benthic organic matter degradation, and helps identify outstanding questions and future directions in the modeling of organic matter degradation in marine sediments.

Preliminary investigation of phosphorus adsorption onto two types of iron oxide-organic matter complexes.

PubMed

Yan, Jinlong; Jiang, Tao; Yao, Ying; Lu, Song; Wang, Qilei; Wei, Shiqiang

2016-04-01

Iron oxide (FeO) coated by natural organic matter (NOM) is ubiquitous. The associations of minerals with organic matter (OM) significantly changes their surface properties and reactivity, and thus affect the environmental fate of pollutants, including nutrients (e.g., phosphorus (P)). In this study, ferrihydrite/goethite-humic acid (FH/GE-HA) complexes were prepared and their adsorption characteristics on P at various pH and ionic strength were investigated. The results indicated that the FeO-OM complexes showed a decreased P adsorption capacity in comparison with bare FeO. The maximum adsorption capacity (Qmax) decreased in the order of FH (22.17 mg/g)>FH-HA (5.43 mg/g)>GE (4.67 mg/g)>GE-HA (3.27 mg/g). After coating with HA, the amorphous FH-HA complex still showed higher P adsorption than the crystalline GE-HA complex. The decreased P adsorption observed might be attributed to changes of the FeO surface charges caused by OM association. The dependence of P adsorption on the specific surface area of adsorbents suggests that the FeO component in the complexes is still the main contributor for the adsorption surfaces. The P adsorptions on FeO-HA complexes decreased with increasing initial pH or decreasing initial ionic strength. A strong dependence of P adsorption on ionic strength and pH may demonstrate that outer-sphere complexes between the OM component on the surface and P possibly coexist with inner-sphere surface complexes between the FeO component and P. Therefore, previous over-emphasis on the contributions of original minerals to P immobilization possibly over-estimates the P loading capacity of soils, especially in humic-rich areas. Copyright © 2015. Published by Elsevier B.V.

Density fractionation of forest soils: methodological questions and interpretation of incubation results and turnover time in an ecosystem context

Treesearch

Susan E. Crow; Christopher W. Swanston; Kate Lajtha; J. Renee Brooks; Heath Keirstead

2007-01-01

Soil organic matter (SOM) is often separated by physical means to simplify a complex matrix into discrete fractions. A frequent approach to isolating two or more fractions is based on differing particle densities and uses a high density liquid such as sodium polytungstate (SPT). Soil density fractions are often interpreted as organic matter pools with different carbon...

Utilization of forest slash to sequester carbon in loblolly pine plantations in the lower coastal plain

Treesearch

F. Sanchez; E.A. Carter; W. Edwards

2002-01-01

Soil-organic matter (SOM) is a complex array of components including soil fauna and flora at different stages of decomposition (Berg et al., 1982). Its concentration in soils can vary from 0.5% in mineral soils to almost 100% in peat soils (Brady, 1974). Organic matter (OM) in the surface mineral soil is considered a major determinant of forest ecosystem productivity...

METHODS FOR THE DETERMINATION OF TOTAL ORGANIC ...

EPA Pesticide Factsheets

Organic matter in soils and sediments is widely distributed over the earth's surface occurring in almost all terrestrial and aquatic environments (Schnitzer, 1978). Soils and sediments contain a large variety of organic materials ranging from simple sugars and carbohydrates to the more complex proteins, fats, waxes, and organic acids. Important characteristics of the organic matter include their ability to: form water-soluble and water- insoluble complexes with metal ions and hydrous oxides; interact with clay minerals and bind particles together; sorb and desorb both naturally-occurring and anthropogenically-introduced organic compounds; absorb and release plant nutrients; and hold water in the soil environment. As a result of these characteristics, the determination of total organic carbon (a measure of one of the chemical components of organic matter that is often used as an indicator of its presence in a soil or sediment) is an essential part of any site characterization since its presence or absence can markedly influence how chemicals will react in the soil or sediment. Soil and sediment total organic carbon (TOC) determinations are typically requested with contaminant analyses as part of an ecological risk assessment data package. TOC contents may be used qualitatively to assess the nature of the sampling location (e.g., was it a depositional area) or may be used to normalize portions of the analytical chemistry data set (e.g., equilibrium partitioning).

Geophysiology, Extended Organisms, and the Problem of Emergent Homeostasis

NASA Astrophysics Data System (ADS)

Turner, S.

2001-12-01

Physiology may be broadly defined as the managed flow of matter, energy and information. Central to this concept is the attendant phenomenon of homeostasis, doing physiological work to balance the thermodynamically driven flows of matter, energy or information that naturally attend to living things. Organisms in general exhibit what might be termed a "strong" homeostasis, in which well-regulated and complex physiological machines drive the physiological fluxes of matter, energy and information within the organism and at the organism's outermost integumentary boundary. Organisms also structure their environments to manage flows of matter, energy and information between themselves and their environment. In so doing, living things constitute a sort of extended organism, in which an organism's physiology reaches beyond the outermost boundary of the skin. Geophysiology's radical promise is that physiology can arise at levels of organization higher than the organism, ranging from social insect colonies through ecosystems, perhaps even to the biosphere itself. However, a simple demonstration that organisms affect the flows of matter, energy and information in their environments is not sufficient to qualify as physiology. That amounts to a demonstration that organisms do physiological work on their environments, which is neither a radical nor a new idea. To be truly physiological, geophysiology must exhibit physiology's most essential attribute, namely homeostasis. Finding homeostasis and explaining how it works in the extended organism is geophysiology's radical challenge.

Predicting organic matter, nitrogen, and phosphorus concentrations in runoff from peat extraction sites using partial least squares regression

NASA Astrophysics Data System (ADS)

Tuukkanen, T.; Marttila, H.; Kløve, B.

2017-07-01

Organic matter and nutrient export from drained peatlands is affected by complex hydrological and biogeochemical interactions. Here partial least squares regression (PLSR) was used to relate various soil and catchment characteristics to variations in chemical oxygen demand (COD), total nitrogen (TN), and total phosphorus (TP) concentrations in runoff. Peat core samples and water quality data were collected from 15 peat extraction sites in Finland. PLSR models constructed by cross-validation and variable selection routines predicted 92, 88, and 95% of the variation in mean COD, TN, and TP concentration in runoff, respectively. The results showed that variations in COD were mainly related to net production (temperature and water-extractable dissolved organic carbon (DOC)), hydrology (topographical relief), and solubility of dissolved organic matter (peat sulfur (S) and calcium (Ca) concentrations). Negative correlations for peat S and runoff COD indicated that acidity from oxidation of organic S stored in peat may be an important mechanism suppressing organic matter leaching. Moreover, runoff COD was associated with peat aluminum (Al), P, and sodium (Na) concentrations. Hydrological controls on TN and COD were similar (i.e., related to topography), whereas degree of humification, bulk density, and water-extractable COD and Al provided additional explanations for TN concentration. Variations in runoff TP concentration were attributed to erosion of particulate P, as indicated by a positive correlation with suspended sediment concentration (SSC), and factors associated with metal-humic complexation and P adsorption (peat Al, water-extractable P, and water-extractable iron (Fe)).

Influence of organic substrates on the kinetics of bacterial As(III) oxidation

NASA Astrophysics Data System (ADS)

Lescure, T.; Joulian, C.; Bauda, P.; Hénault, C.; Battaglia-Brunet, F.

2012-04-01

Soil microflora plays a major role on the behavior of metals and metalloids. Arsenic speciation, in particular, is related to the activity of bacteria able to oxidize, reduce or methylate this element, and determines mobility, bioavailability and toxicity of As. Arsenite (AsIII) is more toxic and more mobile than arsenate (AsV). Bacterial As(III)-oxidation tends to reduce the toxicity of arsenic in soils and the risk of transfer toward underlying aquifers, that would affect the quality of water resources. Previous results suggest that organic matter may affect kinetics or efficiency of bacterial As(III)-oxidation in presence of oxygen, thus in conventional physico-chemical conditions of a surface soil. Different hypothesis can be proposed to explain the influence of organic matter on As(III) oxidation. Arsenic is a potential energy source for bacteria. The presence of easily biodegradable organic matter may inhibit the As(III) oxidation process because bacteria would first metabolize these more energetic substrates. A second hypothesis would be that, in presence of organic matter, the Ars system involved in bacterial resistance to arsenic would be more active and would compete with the Aio system of arsenite oxidation, decreasing the global As(III) oxidation rate. In addition, organic matter influences the solubility of iron oxides which often act as the main pitfalls of arsenic in soils. The concentration and nature of organic matter could therefore have a significant influence on the bioavailability of arsenic and hence on its environmental impact. The influence of organic matter on biological As(III) oxidation has not yet been determined in natural soils. In this context, soil amendment with organic matter during operations of phytostabilization or, considering diffuse pollutions, through agricultural practices, may affect the mobility and bio-availability of the toxic metalloid. The objective of the present project is to quantify the influence of organic matter on the bacterial speciation of arsenic in contaminated soils. Moreover, the biogeochemical consequences of this phenomenon on the mobility and ecotoxicity of this metalloid will be studied. The first task of this program is the precise and systematic investigation of the influence of different types and concentrations of organic matters on the activity of As(III)-oxidizing pure strains. Influence of aspartate, succinate (simple substrates) and yeast extract (complex substrate) on As(III)-oxidation kinetics has been studied. For each experiment, the bacterial growth and the expression of genes involved in the speciation of arsenic, i.e. aio and ars genes, has been monitored. A direct perspective of this work will be to perform experiments with humic and fulvic acids (complex organic matter commonly found in soils), and with water-extracted organic matter from polluted soils. Then the As(III)-oxidation activity of bacterial communities extracted from contaminated soils will be followed. These assays should allow the screening of conditions which will be applied in subsequent experiments with several real contaminated soils, including a former mining site, impacted industrial sites, and a forest soil heavily contaminated after arsenical ammunitions storage. This work is co-funded by BRGM and ADEME (convention TEZ 11-16).

THERMODYNAMIC MODELING OF LIQUID AEROSOLS CONTAINING DISSOLVED ORGANICS AND ELECTROLYTES

EPA Science Inventory

Many tropospheric aerosols contain large fractions of soluble organic material, believed to derive from the oxidation of precursors such alpha-pinene. The chemical composition of aerosol organic matter is complex and not yet fully understood.

The key properties of solu...

Accounting for natural organic matter in aqueous chemical equilibrium models: a review of the theories and applications

NASA Astrophysics Data System (ADS)

Dudal, Yves; Gérard, Frédéric

2004-08-01

Soil organic matter consists of a highly complex and diversified blend of organic molecules, ranging from low molecular weight organic acids (LMWOAs), sugars, amines, alcohols, etc., to high apparent molecular weight fulvic and humic acids. The presence of a wide range of functional groups on these molecules makes them very reactive and influential in soil chemistry, in regards to acid-base chemistry, metal complexation, precipitation and dissolution of minerals and microbial reactions. Out of these functional groups, the carboxylic and phenolic ones are the most abundant and most influential in regards to metal complexation. Therefore, chemical equilibrium models have progressively dealt with organic matter in their calculations. This paper presents a review of six chemical equilibrium models, namely N ICA-Donnan, E Q3/6, G EOCHEM, M INTEQA2, P HREEQC and W HAM, in light of the account they make of natural organic matter (NOM) with the objective of helping potential users in choosing a modelling approach. The account has taken various faces, mainly by adding specific molecules within the existing model databases (E Q3/6, G EOCHEM, and P HREEQC) or by using either a discrete (W HAM) or a continuous (N ICA-Donnan and M INTEQA2) distribution of the deprotonated carboxylic and phenolic groups. The different ways in which soil organic matter has been integrated into these models are discussed in regards to the model-experiment comparisons that were found in the literature, concerning applications to either laboratory or natural systems. Much of the attention has been focused on the two most advanced models, W HAM and N ICA-Donnan, which are able to reasonably describe most of the experimental results. Nevertheless, a better knowledge of the humic substances metal-binding properties is needed to better constrain model inputs with site-specific parameter values. This represents the main axis of research that needs to be carried out to improve the models. In addition to humic substances, more non-humic compounds should also be introduced in model databases, notably the ones that readily interact with the soil microorganisms. Thermodynamic data are generally available for most of these compounds, such as low molecular-weight organic acids. However, the more complex non-humic substances, exhibiting a ratio of hydrophobic versus hydrophilic bonds lower than humic substances, need to be further characterised for a comprehensive implementation in chemical equilibrium models.

A multi-instrumental geochemical study of anomalous uranium enrichment in coal.

PubMed

Havelcová, Martina; Machovič, Vladimír; Mizera, Jiří; Sýkorová, Ivana; Borecká, Lenka; Kopecký, Lubomír

2014-11-01

Contents of uranium in coals from Odeř in the northernmost part of the Sokolov Basin, Czech Republic, in the vicinity of the well known St. Joachimsthal uranium ore deposits, reach extremely high values. In the present work, coal samples with contents of uranium ranging from 0.02 to 6 wt.% were studied. The study employing a whole complex of analytical techniques has been aimed at identification of changes in the structure of coal organic matter, which are associated with the high contents of uranium in coal. The study includes proximate and ultimate analyses, multielement analysis by instrumental neutron and photon activation analyses, micropetrographic analysis by optical microscopy, ESEM/EDX analysis of mineral matter, infrared and Raman spectroscopies, solvent extraction followed by gas chromatography with mass spectroscopy (GC/MS), and analytical pyrolysis (Py-GC/MS). The study has confirmed previously proposed explanation of uraniferous mineralization in sedimentary carboniferous substances by the mechanism of reduction and fixation of soluble U(VI) (uranyl, UO2(2+)) species (e.g., humic, carbonate/hydroxo/phosphate complexes) by sedimentary organic matter under diagenetic or hydrothermal conditions, and formation of insoluble U(IV) species as phosphate minerals and uraninite. The process is accompanied with alteration and destruction of the coal organic matter. The changes in the structure of coal organic matter involve dehydrogenation and oxidation mainly in the aliphatic, aromatic and hydroxyl structures, and an increase in aromaticity, content of ether bonds, and the degree of coalification. Copyright © 2014 Elsevier Ltd. All rights reserved.

Copper toxicity and organic matter: Resiliency of watersheds in the Duluth Complex, Minnesota, USA

USGS Publications Warehouse

Piatak, Nadine; Seal, Robert; Jones, Perry M.; Woodruff, Laurel G.

2015-01-01

We estimated copper (Cu) toxicity in surface water with high dissolved organic matter (DOM) for unmined mineralized watersheds of the Duluth Complex using the Biotic Ligand Model (BLM), which evaluates the effect of DOM, cation competition for biologic binding sites, and metal speciation. A sediment-based BLM was used to estimate stream-sediment toxicity; this approach factors in the cumulative effects of multiple metals, incorporation of metals into less bioavailable sulfides, and complexation of metals with organic carbon. For surface water, the formation of Cu-DOM complexes significantly reduces the amount of Cu available to aquatic organisms. The protective effects of cations, such as calcium (Ca) and magnesium (Mg), competing with Cu to complex with the biotic ligand is likely not as important as DOM in water with high DOM and low hardness. Standard hardness-based water quality criteria (WQC) are probably inadequate for describing Cu toxicity in such waters and a BLM approach may yield more accurate results. Nevertheless, assumptions about relative proportions of humic acid (HA) and fulvic acid (FA) in DOM significantly influence BLM results; the higher the HA fraction, the higher calculated resiliency of the water to Cu toxicity. Another important factor is seasonal variation in water chemistry, with greater resiliency to Cu toxicity during low flow compared to high flow.Based on generally low total organic carbon and sulfur content, and equivalent metal ratios from total and weak partial extractions, much of the total metal concentration in clastic streambedsediments may be in bioavailable forms, sorbed on clays or hydroxide phases. However, organicrich fine-grained sediment in the numerous wetlands may sequester significant amount of metals, limiting their bioavailability. A high proportion of organic matter in waters and some sediments will play a key role in the resiliency of these watersheds to potential additional metal loads associated with future mining operations.

Carbohydrates as indicators of biogeochemical processes

NASA Astrophysics Data System (ADS)

Lazareva, E. V.; Romankevich, E. A.

2012-05-01

A method is presented to study the carbohydrate composition of marine objects involved into sedimento- and diagenesis (plankton, particulate matter, benthos, and bottom sediments). The analysis of the carbohydrates is based upon the consecutive separation of their fractions with different solvents (water, alkali, and acid). The ratio of the carbohydrate fractions allows one to evaluate the lability of the carbohydrate complex. It is also usable as an indicator of the biogeochemical processes in the ocean, as well of the genesis and the degree of conversion of organic matter in the bottom sediments and nodules. The similarity in the monosaccharide composition is shown for dissolved organic matter and aqueous and alkaline fractions of seston and particulate matter.

PHYS: Division of Physical Chemistry 258 - Properties and Origins of Cometary and Asteroidal Organic Matter Delivered to the Early Earth

NASA Technical Reports Server (NTRS)

Messenger, Scott; Nguyen, Ann

2017-01-01

Comets and asteroids may have contributed much of the Earth's water and organic matter. The Earth accretes approximately 4x10(exp 7) Kg of dust and meteorites from these sources every year. The least altered meteorites contain complex assemblages of organic compounds and abundant hydrated minerals. These carbonaceous chondrite meteorites probably derive from asteroids that underwent hydrothermal processing within the first few million years after their accretion. Meteorite organics show isotopic and chemical signatures of low-T ion-molecule and grain-surface chemistry and photolysis of icy grains that occurred in cold molecular clouds and the outer protoplanetary disk. These signatures have been overprinted by aqueously mediated chemistry in asteroid parent bodies, forming amino acids and other prebiotic molecules. Comets are much richer in organic matter but it is less well characterized. Comet dust collected in the stratosphere shows larger H and N isotopic anomalies than most meteorites, suggesting better preservation of primordial organics. Rosetta studies of comet 67P coma dust find complex organic matter that may be related to the macromolecular material that dominates the organic inventory of primitive meteorites. The exogenous organic material accreting on Earth throughout its history is made up of thousands of molecular species formed in diverse processes ranging from circumstellar outflows to chemistry at near absolute zero in dark cloud cores and the formative environment within minor planets. NASA and JAXA are currently flying sample return missions to primitive, potentially organic-rich asteroids. The OSIRIS-REx and Hayabusa2 missions will map their target asteroids, Bennu and Ryugu, in detail and return regolith samples to Earth. Laboratory analyses of these pristine asteroid samples will provide unprecedented views of asteroidal organic matter relatively free of terrestrial contamination within well determined geological context. Studies of extraterrestrial materials and returned samples are essential to understand the origins of Solar System organic material and the roles of comets and asteroids to providing the starting materials for the emergence of life.

The chemical composition of aerosols from Wildland fires: Current state of the science and possible new directions.

EPA Science Inventory

Wildland fire emits a substantial quantity of aerosol to the atmosphere. These aerosols typically comprise a complex mixture of organic matter and refractory elemental or black carbon with a relatively minor contribution of inorganic matter from soils and plant micronutrients. Id...

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

EPA Science Inventory

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

Relevant role of dissolved humic matter in phosphorus bioavailability in natural and agronomical ecosystems through the formation of Humic-(Metal)-Phosphate complexes

NASA Astrophysics Data System (ADS)

Baigorri, Roberto; Urrutia, Óscar; Erro, Javier; Pazos-Pérez, Nicolás; María García-Mina, José

2016-04-01

Natural Organic Matter (NOM) and the NOM fraction present in soil solution (dissolved organic matter: DOM) are currently considered as fundamental actors in soil fertility and crop mineral nutrition. Indeed, decreases in crop yields as well as soil erosion are closely related to low values of NOM and, in fact, the use of organic amendments as both soil improvers and plant growth enhancers is very usual in countries with soils poor in NOM. This role of NOM (and DOM) seems to be associated with the presence of bio-transformed organic molecules (humic substances) with high cation chelating-complexing ability. In fact, bioavailable micronutrients with metallic character in soil solutions of alkaline and calcareous soils are forming stable complexes with DOM. This beneficial action of DOM also concerns other plant nutrients such as inorganic phosphate (Pi). Among the different mechanisms involved in the beneficial action of DOM on P bioavailability, the possible formation of poly-nuclear complexes including stable chemical bonds between negative binding sites in humic substances and Pi through metal bridges in soil solution might be relevant, especially in acidic soils. In fact, several studies have proven that these complexes can be obtained in the laboratory and are very efficient in prevent Pi soil fixation and improve Pi root uptake. However, clear experimental evidence about their presence in soil solutions of natural and agronomical soil ecosystems has not published yet. We present here experimental results supporting the real presence of stable Pi-metal-Humic (PMH) complexes in the soil solution of several acidic soils. The study is based on the physico-chemical characterization (31P-NMR, FTIR, TEM-EDAX, ICP-OES) of the DOM fraction isolated by ultrafiltration from the soil solution of several representative acidic soils. In average, more than 60 % of Pi was found in the soil solution humic fraction forming stable humic-metal (Fe, Al) complexes.

Physical and Chemical Properties of Anthropogenic Aerosols: An Overview

EPA Science Inventory

Aerosol chemical composition is complex. Combustion aerosols can comprise tens of thousands of organic compounds, refractory brown and black carbon, heavy metals, cations, anions, salts, and other inorganic phases. Aerosol organic matter normally contains semivolatile material th...

An original data treatment for infrared spectra of organic matter, application to extracted soil organic matter

NASA Astrophysics Data System (ADS)

Gomes Rossin, Bruna; Redon, Roland; Raynaud, Michel; Nascimento, Nadia Regina; Mounier, Stéphane

2017-04-01

Infrared spectra of extracted organic matter are easy and rapid to do, but generally hard to interpreted over the presence or not of certain organic functions. Indeed, the organic matter is a complex mixture of molecules often having absorption overlapping and it is also difficult to have a well calibrated or normalised spectra due to the difficulty to have a well known solid content or homogeneity for a sample (Monakhova et al. 2015, Tadini et al. 2015, Bardy et al. 2008). In this work, the IRTF (InfraRed Fourier Transform) spectra were treated by an original algorithm developed to obtain the principal components of the IRTF spectra and their contributions for each sample. This bilinear decomposition used a PCA initialisation and the principal components were estimated from vectors calculated by PCA and linearly combined to provide non-negative signals minimizing a criterion based on cross-correlation. Hence, using this decomposition, it is possible to define IRTF signal of organic matter fractions like humic acid or fulvic acid depending on their origin like surface of depth of soil profiles. The method was used on a set of sample from Upper Negro River Basin (Amazon, Brazil) (Bueno,2009), where three soils sequences from surface to two meter depth containing 10 slices each. The sequences were sampled on a podzol well drain, a hydromorphic podzol and a cryptopodzol. From the IRTF data five representative component spectra were defined for all the extracted organic matter , and using other chemical composition information, a mechanism of organic matter fate is proposed to explain the observed results. Bardy, M., E. Fritsch, S. Derenne, T. Allard, N. R. do Nascimento, and G. T. Bueno. 2008. "Micromorphology and Spectroscopic Characteristics of Organic Matter in Waterlogged Podzols of the Upper Amazon Basin." Geoderma 145 (3-4): 222-30. Bueno, G.T. Appauvrissement et podzolisation des latérites du baissin du Rio Negro et gênese dês Podzols dans le haut bassin amazonien. [PHD] .Universidade Estadual Paulista "Júlio de Mesquita Filho";2009. Monakhova, Yulia B., Alexey M. Tsikin, Svetlana P. Mushtakova, and Mauro Mecozzi. 2015. "Independent Component Analysis and Multivariate Curve Resolution to Improve Spectral Interpretation of Complex Spectroscopic Data Sets: Application to Infrared Spectra of Marine Organic Matter Aggregates." Microchemical Journal, Devoted to the Application of Microtechniques in All Branches of Science 118 (January): 211-22. Tadini, Amanda Maria, Gustavo Nicolodelli, Stephane Mounier, Célia Regina Montes, and Débora Marcondes Bastos Pereira Milori. 2015. "The Importance of Humin in Soil Characterisation: A Study on Amazonian Soils Using Different Fluorescence Techniques." The Science of the Total Environment 537 (December): 152-58.

Disrupted subject-specific gray matter network properties and cognitive dysfunction in type 1 diabetes patients with and without proliferative retinopathy.

PubMed

van Duinkerken, Eelco; Ijzerman, Richard G; Klein, Martin; Moll, Annette C; Snoek, Frank J; Scheltens, Philip; Pouwels, Petra J W; Barkhof, Frederik; Diamant, Michaela; Tijms, Betty M

2016-03-01

Type 1 diabetes mellitus (T1DM) patients, especially with concomitant microvascular disease, such as proliferative retinopathy, have an increased risk of cognitive deficits. Local cortical gray matter volume reductions only partially explain these cognitive dysfunctions, possibly because volume reductions do not take into account the complex connectivity structure of the brain. This study aimed to identify gray matter network alterations in relation to cognition in T1DM. We investigated if subject-specific structural gray matter network properties, constructed from T1-weighted MRI scans, were different between T1DM patients with (n = 51) and without (n = 53) proliferative retinopathy versus controls (n = 49), and were associated to cognitive decrements and fractional anisotropy, as measured by voxel-based TBSS. Global normalized and local (45 bilateral anatomical regions) clustering coefficient and path length were assessed. These network properties measure how the organization of connections in a network differs from that of randomly connected networks. Global gray matter network topology was more randomly organized in both T1DM patient groups versus controls, with the largest effects seen in patients with proliferative retinopathy. Lower local path length values were widely distributed throughout the brain. Lower local clustering was observed in the middle frontal, postcentral, and occipital areas. Complex network topology explained up to 20% of the variance of cognitive decrements, beyond other predictors. Exploratory analyses showed that lower fractional anisotropy was associated with a more random gray matter network organization. T1DM and proliferative retinopathy affect cortical network organization that may consequently contribute to clinically relevant changes in cognitive functioning in these patients. © 2015 Wiley Periodicals, Inc.

Organic carbon accumulation in modern sediments of the Angola basin influenced by the Congo deep-sea fan

NASA Astrophysics Data System (ADS)

Baudin, François; Martinez, Philippe; Dennielou, Bernard; Charlier, Karine; Marsset, Tania; Droz, Laurence; Rabouille, Christophe

2017-08-01

Geochemical data (total organic carbon-TOC content, δ13Corg, C:N, Rock-Eval analyses) were obtained on 150 core tops from the Angola basin, with a special focus on the Congo deep-sea fan. Combined with the previously published data, the resulting dataset (322 stations) shows a good spatial and bathymetric representativeness. TOC content and δ13Corg maps of the Angola basin were generated using this enhanced dataset. The main difference in our map with previously published ones is the high terrestrial organic matter content observed downslope along the active turbidite channel of the Congo deep-sea fan till the distal lobe complex near 5000 m of water-depth. Interpretation of downslope trends in TOC content and organic matter composition indicates that lateral particle transport by turbidity currents is the primary mechanism controlling supply and burial of organic matter in the bathypelagic depths.

Fifteen years of PARAFAC application to organic matter fluorescence - progress, problems and possibilities

NASA Astrophysics Data System (ADS)

Murphy, K.; Stedmon, C. A.; Wunsch, U.

2017-12-01

The study of dissolved organic matter in aquatic milieu frequently involves measuring and interpreting fluorescence excitation emission matrices (EEMs) as a proxy for studying the total organic matter pool. Parallel Factor Analysis (PARAFAC) is used widely to identify and track independent organic matter fractions. This approach assumes that each EEM reflects the combined fluorescence signal from a limited number of unique, non-interacting chemical components, which are determined via a fitting algorithm. During the past fifteen years, considerable progress in understanding dissolved organic matter fluorescence has been achieved with the aid of PARAFAC; however, very few identical or ubiquitous fluorescence spectra have been independently identified. We studied the influence of wavelength selection on PARAFAC models and found this factor to have a decisive impact on PARAFAC spectra despite receiving little attention in most studies. Because large, chemically-diverse datasets may be too complex to analyse with PARAFAC, we are exploring novel methods for increasing variability in small datasets in order to reduce biases and increase interpretability. Our results suggest that spectral variability in PARAFAC models between studies are in many cases due to artefacts that could be minimised by careful experimental and modelling approaches.

Detritus fuels ecosystem metabolism but not metazoan food webs in San Francisco estuary's freshwater delta

USGS Publications Warehouse

Sobczak, W.V.; Cloern, J.E.; Jassby, A.D.; Cole, B.E.; Schraga, T.S.; Arnsberg, A.

2005-01-01

Detritus from terrestrial ecosystems is the major source of organic matter in many streams, rivers, and estuaries, yet the role of detritus in supporting pelagic food webs is debated. We examined the importance of detritus to secondary productivity in the Sacramento and San Joaquin River Delta (California, United States), a large complex of tidal freshwater habitats. The Delta ecosystem has low primary productivity but large detrital inputs, so we hypothesized that detritus is the primary energy source fueling production in pelagic food webs. We assessed the sources, quantity, composition, and bioavailability of organic matter among a diversity of habitats (e.g., marsh sloughs, floodplains, tidal lakes, and deep river channels) over two years to test this hypothesis. Our results support the emerging principle that detritus dominates riverine and estuarine organic matter supply and supports the majority of ecosystem metabolism. Yet in contrast to prevailing ideas, we found that detritus was weakly coupled to the Delta's pelagic food web. Results from independent approaches showed that phytoplankton production was the dominant source of organic matter for the Delta's pelagic food web, even though primary production accounts for a small fraction of the Delta's organic matter supply. If these results are general, they suggest that the value of organic matter to higher trophic levels, including species targeted by programs of ecosystem restoration, is a function of phytoplankton production. ?? 2005 Estuarine Research Federation.

Organic Chemistry of Meteorites

NASA Technical Reports Server (NTRS)

Chang, S.; Morrison, David (Technical Monitor)

1994-01-01

Studies of the molecular structures and C,N,H-isotopic compositions of organic matter in meteorites reveal a complex history beginning in the parent interstellar cloud which spawned the solar system. Incorporation of interstellar dust and gas in the protosolar nebula followed by further thermal and aqueous processing on primordial parent bodies of carbonaceous, meteorites have produced an inventory of diverse organic compounds including classes now utilized in biochemistry. This inventory represents one possible set of reactants for chemical models for the origin of living systems on the early Earth. Evidence bearing on the history of meteoritic organic matter from astronomical observations and laboratory investigations will be reviewed and future research directions discussed.

Sorptive fractionation of organic matter and formation of organo-hydroxy-aluminum complexes during litter biodegradation in the presence of gibbsite

NASA Astrophysics Data System (ADS)

Heckman, K.; Grandy, A. S.; Gao, X.; Keiluweit, M.; Wickings, K.; Carpenter, K.; Chorover, J.; Rasmussen, C.

2013-11-01

Solid and aqueous phase Al species are recognized to affect organic matter (OM) stabilization in forest soils. However, little is known about the dynamics of formation, composition and dissolution of organo-Al hydroxide complexes in microbially-active soil systems, where plant litter is subject to microbial decomposition in close proximity to mineral weathering reactions. We incubated gibbsite-quartz mineral mixtures in the presence of forest floor material inoculated with a native microbial consortium for periods of 5, 60 and 154 days. At each time step, samples were density separated into light (<1.6 g cm-3), intermediate (1.6-2.0 g cm-3), and heavy (>2.0 g cm-3) fractions. The light fraction was mainly comprised of particulate organic matter, while the intermediate and heavy density fractions contained moderate and large amounts of Al-minerals, respectively. Multi-method interrogation of the fractions indicated the intermediate and heavy fractions differed both in mineral structure and organic compound composition. X-ray diffraction analysis and SEM/EDS of the mineral component of the intermediate fractions indicated some alteration of the original gibbsite structure into less crystalline Al hydroxide and possibly proto-imogolite species, whereas alteration of the gibbsite structure was not evident in the heavy fraction. DRIFT, Py-GC/MS and STXM/NEXAFS results all showed that intermediate fractions were composed mostly of lignin-derived compounds, phenolics, and polysaccharides. Heavy fraction organics were dominated by polysaccharides, and were enriched in proteins, N-bearing compounds, and lipids. The source of organics appeared to differ between the intermediate and heavy fractions. Heavy fractions were enriched in 13C with lower C/N ratios relative to intermediate fractions, suggesting a microbial origin. The observed differential fractionation of organics among hydroxy-Al mineral types suggests that microbial activity superimposed with abiotic mineral-surface-mediated fractionation leads to strong density differentiation of organo-mineral complex composition even over the short time scales probed in these incubation experiments. The data highlight the strong interdependency of mineral transformation, microbial community activity, and organic matter stabilization during biodegradation.

COPPER COMPLEXATION BY NATURAL ORGANIC MATTER IN CONTAMINATED AND UNCOMTAINATED GROUND WATER

EPA Science Inventory

Ground-water samples were collected from an uncontaminated and a contaminated site. Copper complexation was characterized by ion-selective electrode (ISE), fluorescence quenching (FQ), and cathodic stripping voltammetric (CSV) titrations. All of the samples were titrated at their...

Chapter A6. Section 6.7. Turbidity

USGS Publications Warehouse

Anderson, Chauncey W.

2005-01-01

Turbidity is one of the indicators used to assess the environmental health of water bodies. Turbidity is caused by the presence of suspended and dissolved matter, such as clay, silt, finely divided organic matter, plankton and other microscopic organisms, organic acids, and dyes. This section of the National Field Manual (NFM) describes the USGS protocols for determining turbidity in surface and ground waters, including extensive guidance for equipment selection and data reporting. It includes the revised approach to turbidity measurement and reporting that was implemented by the U.S. Geological Survey (USGS) in October 2004 to account for technological advances and consequent measurement complexities.

Origin and Evolution of Prebiotic Organic Matter as Inferred from the Tagish Lake Meteorite

NASA Technical Reports Server (NTRS)

Herd, Christopher D.; Blinova, Alexandra; Simkus, Danielle N.; Huang, Yongsong; Tarozo, Rafael; Alexander, Conel M.; Gyngard, Frank; Nittler, Larry R.; Cody, George D.; Fogel, Marilyn L.;

Pyrolysis Mass Spectrometry of Complex Organic Materials.

ERIC Educational Resources Information Center

Meuzelaar, Henk L. C.; And Others

1984-01-01

Illustrates the state of the art in pyrolysis mass spectrometry techniques through applications in: (1) structural determination and quality control of synthetic polymers; (2) quantitative analysis of polymer mixtures; (3) classification and structural characterization of fossil organic matter; and (4) nonsupervised numerical extraction of…

Analysis of the chemical and physical properties of combustion aerosols: Properties overview

EPA Science Inventory

Aerosol chemical composition is remarkably complex. Combustion aerosols can comprise tens of thousands of organic compounds and fragments, refractory carbon, metals, cations, anions, salts, and other inorganic phases and substituents [Hays et al., 2004]. Aerosol organic matter no...

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

EPA Science Inventory

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

Identification of Mercury and Dissolved Organic Matter Complexes Using Ultrahigh Resolution Mass Spectrometry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Hongmei; Johnston, Ryne C.; Mann, Benjamin F.

The chemical speciation and bioavailability of mercury (Hg) is markedly influenced by its complexation with naturally dissolved organic matter (DOM) in aquatic environments. To date, however, analytical methodologies capable of identifying such complexes are scarce. Here in this paper, we utilize ultrahigh resolution Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) coupled with electrospray ionization to identify individual Hg–DOM complexes. The measurements were performed by direct infusion of DOM in a 1:1 methanol:water solution at a Hg to dissolved organic carbon (DOC) molar ratio of 3 × 10 –4. Heteroatomic molecules, especially those containing multiple S and N atoms, weremore » found to be among the most important in forming strong complexes with Hg. Major Hg–DOM complexes of C 10H 21N 2S 4Hg + and C 8H 17N 2S 4Hg + were identified based on both the exact molecular mass and patterns of Hg stable isotope distributions detected by FTICR-MS. Density functional theory was used to predict the solution-phase structures of candidate molecules. Finally, these findings represent the first step to unambiguously identify specific DOM molecules in Hg binding, although future studies are warranted to further optimize and validate the methodology so as to explore detailed molecular compositions and structures of Hg–DOM complexes that affect biological uptake and transformation of Hg in the environment.« less

Identification of Mercury and Dissolved Organic Matter Complexes Using Ultrahigh Resolution Mass Spectrometry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Hongmei; Johnston, Ryne C.; Mann, Benjamin F.

The chemical speciation and bioavailability of mercury (Hg) is markedly influenced by its complexation with naturally dissolved organic matter (DOM) in aquatic environments. To date, however, analytical methodologies capable of identifying such complexes are scarce. Here, we utilize ultrahigh resolution Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) coupled with electrospray ionization to identify individual Hg-DOM complexes. The measurements were performed by direct infusion of DOM in a 1:1 methanol:water solution at a Hg to dissolved organic carbon (DOC) molar ratio of 3 × 10 -4. Heteroatomic molecules, especially those containing multiple S and N atoms, were found to bemore » among the most important in forming strong complexes with Hg. Major Hg-DOM complexes of C10H21N2S4Hg+ and C8H17N2S4Hg+ were identified based on both the exact molecular mass and patterns of Hg stable isotope distributions detected by FTICR-MS. Density functional theory was used to predict the solution-phase structures of candidate molecules. These findings represent the first step to unambiguously identify specific DOM molecules in Hg binding, although future studies are warranted to further optimize and validate the methodology so as to explore detailed molecular compositions and structures of Hg-DOM complexes that affect biological uptake and transformation of Hg in the environment.« less

Identification of Mercury and Dissolved Organic Matter Complexes Using Ultrahigh Resolution Mass Spectrometry

DOE PAGES

Chen, Hongmei; Johnston, Ryne C.; Mann, Benjamin F.; ...

2016-12-22

The chemical speciation and bioavailability of mercury (Hg) is markedly influenced by its complexation with naturally dissolved organic matter (DOM) in aquatic environments. To date, however, analytical methodologies capable of identifying such complexes are scarce. Here in this paper, we utilize ultrahigh resolution Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) coupled with electrospray ionization to identify individual Hg–DOM complexes. The measurements were performed by direct infusion of DOM in a 1:1 methanol:water solution at a Hg to dissolved organic carbon (DOC) molar ratio of 3 × 10 –4. Heteroatomic molecules, especially those containing multiple S and N atoms, weremore » found to be among the most important in forming strong complexes with Hg. Major Hg–DOM complexes of C 10H 21N 2S 4Hg + and C 8H 17N 2S 4Hg + were identified based on both the exact molecular mass and patterns of Hg stable isotope distributions detected by FTICR-MS. Density functional theory was used to predict the solution-phase structures of candidate molecules. Finally, these findings represent the first step to unambiguously identify specific DOM molecules in Hg binding, although future studies are warranted to further optimize and validate the methodology so as to explore detailed molecular compositions and structures of Hg–DOM complexes that affect biological uptake and transformation of Hg in the environment.« less

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.

Effects of Pedogenic Fe Oxides on Soil Aggregate-Associated Carbon

NASA Astrophysics Data System (ADS)

Asefaw Berhe, A.; Jin, L.

2017-12-01

Carbon sequestration is intimately related to the soil structure, mainly soil aggregate dynamics. Carbon storage in soil aggregates has been recognized as an important carbon stabilization mechanism in soils. Organic matter and pedogenic Fe oxides are major binding agents that facilitate soil aggregate formation and stability. However, few studies have investigated how different forms of pedogenic Fe oxides can affect soil carbon distribution in different aggregate-size fractions. We investigated sequentially extracted pedogenic Fe oxides (in the order of organically complexed Fe extracted with sodium pyrophosphate, poorly-crystalline Fe oxides extracted with hydroxylamine hydrochloride, and crystalline Fe oxides extracted with dithionite hydrochloride) and determined the amount and nature of C in macroaggregates (2-0.25mm), microaggregates (0.25-0.053mm), and two silt and clay fractions (0.053-0.02mm, and <0.02mm) in Musick soil from Sierra Nevada mountain in California. We also determined how pedogenic Fe oxides affect soil carbon distribution along soil depth gradients. Findings of our study revealed that the proportion of organic matter complexed Fe decreased, but the proportion of crystalline Fe increased with increasing soil depths. Poorly crystalline Fe oxides (e.g. ferrihydrite) was identified as a major Fe oxide in surface soil, whereas crystalline Fe oxides (e.g. goethite) were found in deeper soil layers. These results suggest that high concentration of organic matter in surface soil suppressed Fe crystallization. Calcium cation was closely related to the pyrophosphate extractable Fe and C, which indicates that calcium may be a major cation that contribute to the organic matter complexed Fe and C pool. Increasing concentrations of extractable Fe and C with decreasing aggregate size fractions also suggests that Fe oxides play an important role in formation and stability of silt and clay fractions, and leading to further stabilization of carbon in soil. Our findings provide mechanistic understanding of how pedogenic Fe oxides play important role in carbon stabilization in different aggregate-size fractions in soil.

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.

Sorption and speciation of iodine in groundwater system: The roles of organic matter and organic-mineral complexes.

PubMed

Li, Junxia; Zhou, Hailing; Wang, Yanxin; Xie, Xianjun; Qian, Kun

2017-06-01

Characterizing the properties of main host of iodine in soil/sediment and the geochemical behaviors of iodine species are critical to understand the mechanisms of iodine mobilization in groundwater systems. Four surface soil and six subsurface sediment samples were collected from the iodine-affected area of Datong basin in northern China to conduct batch experiments and to evaluate the effects of NOM and/or organic-mineral complexes on iodide/iodate geochemical behaviors. The results showed that both iodine contents and k f -iodate values had positive correlations with solid TOC contents, implying the potential host of NOM for iodine in soil/sediment samples. The results of chemical removal of easily extracted NOM indicated that the NOM of surface soils is mainly composed of surface embedded organic matter, while sediment NOM mainly occurs in the form of organic-mineral complexes. After the removal of surface sorbed NOM, the decrease in k f -iodate value of treated surface soils indicates that surface sorbed NOM enhances iodate adsorption onto surface soil. By contrast, k f -iodate value increases in several H 2 O 2 -treated sediment samples, which was considered to result from exposed rod-like minerals rich in Fe/Al oxyhydroxide/oxides. After chemical removal of organic-mineral complexes, the lowest k f -iodate value for both treated surface soils and sediments suggests the dominant role of organic-mineral complexes on controlling the iodate geochemical behavior. In comparison with iodate, iodide exhibited lower affinities on all (un)treated soil/sediment samples. The understanding of different geochemical behaviors of iodine species helps to explain the occurrence of high iodine groundwater with iodate and iodide as the main species in shallow (oxidizing conditions) and deep (reducing conditions) groundwater. Copyright © 2017 Elsevier B.V. All rights reserved.

Sorption and speciation of iodine in groundwater system: The roles of organic matter and organic-mineral complexes

NASA Astrophysics Data System (ADS)

Li, Junxia; Zhou, Hailing; Wang, Yanxin; Xie, Xianjun; Qian, Kun

2017-06-01

Characterizing the properties of main host of iodine in soil/sediment and the geochemical behaviors of iodine species are critical to understand the mechanisms of iodine mobilization in groundwater systems. Four surface soil and six subsurface sediment samples were collected from the iodine-affected area of Datong basin in northern China to conduct batch experiments and to evaluate the effects of NOM and/or organic-mineral complexes on iodide/iodate geochemical behaviors. The results showed that both iodine contents and kf-iodate values had positive correlations with solid TOC contents, implying the potential host of NOM for iodine in soil/sediment samples. The results of chemical removal of easily extracted NOM indicated that the NOM of surface soils is mainly composed of surface embedded organic matter, while sediment NOM mainly occurs in the form of organic-mineral complexes. After the removal of surface sorbed NOM, the decrease in kf-iodate value of treated surface soils indicates that surface sorbed NOM enhances iodate adsorption onto surface soil. By contrast, kf-iodate value increases in several H2O2-treated sediment samples, which was considered to result from exposed rod-like minerals rich in Fe/Al oxyhydroxide/oxides. After chemical removal of organic-mineral complexes, the lowest kf-iodate value for both treated surface soils and sediments suggests the dominant role of organic-mineral complexes on controlling the iodate geochemical behavior. In comparison with iodate, iodide exhibited lower affinities on all (un)treated soil/sediment samples. The understanding of different geochemical behaviors of iodine species helps to explain the occurrence of high iodine groundwater with iodate and iodide as the main species in shallow (oxidizing conditions) and deep (reducing conditions) groundwater.

Effect of dietary protein on hybrid tilapia production in a biofloc technology system

USDA-ARS?s Scientific Manuscript database

In an outdoor biofloc technology (BFT) production system a complex of living organisms that includes phytoplankton, zooplankton, ciliates, nematodes, bacteria, all closely associated with particulate organic matter, is maintained suspended in the water column by continuous aeration. Tilapia grown in...

Chloramination of Concentrated Drinking Water for Disinfection Byproduct Mixtures Creation- Indianapolis

EPA Science Inventory

Complex mixtures of disinfection by-products (DBPs) are formed when the disinfectant oxidizes constituents (e.g., natural organic matter (NOM) and organic pollutants) found in the source water. Since 1974, over 600 DBPs have been identified in drinking water. Despite intense iden...

Coagulation of micro-polluted Pearl River water with IPF-PACls.

PubMed

Xu, Yi; Sun, Wei; Wang, Dong-sheng; Tang, Hong-xiao

2004-01-01

Water samples collected from early March 2001 to the end of April 2002 at the branch of Pearl River around the Guangzhou City were analyzed for its micro-polluted characteristics. The coagulation behavior of polyaluminum chlorides (PACls) was then examined focusing on the effect of primary water quality and speciation distribution. The results showed that PACls exhibit better coagulation efficiency than alum in accordance with the different speciation. The turbidity removal property of PACls is evidently better than alum at low dosage. While in neutral zone (about 6.5-7.5), the turbidity removal of PACls decreases owing to the restabilization of particles at higher dosage. The organic matters in raw water exhibit marked influence on coagulation. In acidic zone, organic matters complex with polymer species and promote the formation of flocs. With an increase in pH, the complexation of organics with polymer species gradually decreases, and the removal of organics mainly depends on adsorption. The effect is evidently improved with the raise of B value.

Temperature-driven decoupling of key phases of organic matter degradation in marine sediments.

PubMed

Weston, Nathaniel B; Joye, Samantha B

2005-11-22

The long-term burial of organic carbon in sediments results in the net accumulation of oxygen in the atmosphere, thereby mediating the redox state of the Earth's biosphere and atmosphere. Sediment microbial activity plays a major role in determining whether particulate organic carbon is recycled or buried. A diverse consortium of microorganisms that hydrolyze, ferment, and terminally oxidize organic compounds mediates anaerobic organic matter mineralization in anoxic sediments. Variable temperature regulation of the sequential processes, leading from the breakdown of complex particulate organic carbon to the production and subsequent consumption of labile, low-molecular weight, dissolved intermediates, could play a key role in controlling rates of overall organic carbon mineralization. We examined sediment organic carbon cycling in a sediment slurry and in flow through bioreactor experiments. The data show a variable temperature response of the microbial functional groups mediating organic matter mineralization in anoxic marine sediments, resulting in the temperature-driven decoupling of the production and consumption of organic intermediates. This temperature-driven decoupling leads to the accumulation of labile, low-molecular weight, dissolved organic carbon at low temperatures and low-molecular weight dissolved organic carbon limitation of terminal metabolism at higher temperatures.

Electrokinetic treatment of an agricultural soil contaminated with heavy metals.

PubMed

Figueroa, Arylein; Cameselle, Claudio; Gouveia, Susana; Hansen, Henrik K

2016-07-28

The high organic matter content in agricultural soils tends to complex and retain contaminants such as heavy metals. Electrokinetic remediation was tested in an agricultural soil contaminated with Co(+2), Zn(+2), Cd(+2), Cu(+2), Cr(VI), Pb(+2) and Hg(+2). The unenhanced electrokinetic treatment was not able to remove heavy metals from the soil due to the formation of precipitates in the alkaline environment in the soil section close to the cathode. Moreover, the interaction between metals and organic matter probably limited metal transportation under the effect of the electric field. Citric acid and ethylenediaminetetraacetic acid (EDTA) were used in the catholyte as complexing agents in order to enhance the extractability and removal of heavy metals from soil. These complexing agents formed negatively charged complexes that migrated towards the anode. The acid front electrogenerated at the anode favored the dissolution of heavy metals that were transported towards the cathode. The combined effect of the soil pH and the complexing agents resulted in the accumulation of heavy metals in the center of the soil specimen.

Mercury reduction and complexation by natural organic matter in anoxic environments.

PubMed

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

2011-01-25

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 thiolate ligand-induced oxidative complexation with an estimated binding capacity of ~3.5 μmol Hg/g HA and a partitioning coefficient >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 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.

Soil Organic Matter in Its Native State: Unravelling the Most Complex Biomaterial on Earth.

PubMed

Masoom, Hussain; Courtier-Murias, Denis; Farooq, Hashim; Soong, Ronald; Kelleher, Brian P; Zhang, Chao; Maas, Werner E; Fey, Michael; Kumar, Rajeev; Monette, Martine; Stronks, Henry J; Simpson, Myrna J; Simpson, André J

2016-02-16

Since the isolation of soil organic matter in 1786, tens of thousands of publications have searched for its structure. Nuclear magnetic resonance (NMR) spectroscopy has played a critical role in defining soil organic matter but traditional approaches remove key information such as the distribution of components at the soil-water interface and conformational information. Here a novel form of NMR with capabilities to study all physical phases termed Comprehensive Multiphase NMR, is applied to analyze soil in its natural swollen-state. The key structural components in soil organic matter are identified to be largely composed of macromolecular inputs from degrading biomass. Polar lipid heads and carbohydrates dominate the soil-water interface while lignin and microbes are arranged in a more hydrophobic interior. Lignin domains cannot be penetrated by aqueous solvents even at extreme pH indicating they are the most hydrophobic environment in soil and are ideal for sequestering hydrophobic contaminants. Here, for the first time, a complete range of physical states of a whole soil can be studied. This provides a more detailed understanding of soil organic matter at the molecular level itself key to develop the most efficient soil remediation and agricultural techniques, and better predict carbon sequestration and climate change.

The impact of pre-oxidation with potassium permanganate on cyanobacterial organic matter removal by coagulation.

PubMed

Naceradska, Jana; Pivokonsky, Martin; Pivokonska, Lenka; Baresova, Magdalena; Henderson, Rita K; Zamyadi, Arash; Janda, Vaclav

2017-05-01

The study investigates the effect of permanganate pre-oxidation on the coagulation of peptides/proteins of Microcystis aeruginosa which comprise a major proportion of the organic matter during cyanobacterial bloom decay. Four different permanganate dosages (0.1, 0.2, 0.4 and 0.6 mg KMnO 4 mg -1 DOC) were applied prior to coagulation by ferric sulphate. Moreover, changes in sample characteristics, such as UV 254 , DOC content and molecular weight distribution, after pre-oxidation were monitored. The results showed that permanganate pre-oxidation led to a reduction in coagulant dose, increased organic matter removals by coagulation (by 5-12% depending on permanganate dose), microcystin removal (with reductions of 91-96%) and a shift of the optimum pH range from 4.3 to 6 without to 5.5-7.3 with pre-oxidation. Degradation of organic matter into inorganic carbon and adsorption of organic matter onto hydrous MnO 2 are suggested as the main processes responsible for coagulation improvement. Moreover, permanganate prevented the formation of Fe-peptide/protein complexes that inhibit coagulation at pH about 6.2 without pre-oxidation. The study showed that carefully optimized dosing of permanganate improves cyanobacterial peptide/protein removal, with the benefit of microcystin elimination. Copyright © 2017 Elsevier Ltd. All rights reserved.

Hydrogenation of Organic Matter as a Terminal Electron Sink Sustains High CO 2 :CH 4 Production Ratios During Anaerobic Decomposition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wilson, Rachel M.; Tfaily, Malak M.; Rich, Virginia I.

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

Hydrogenation of Organic Matter as a Terminal Electron Sink Sustains High CO 2 :CH 4 Production Ratios During Anaerobic Decomposition

DOE PAGES

Wilson, Rachel M.; Tfaily, Malak M.; Rich, Virginia I.; ...

2017-07-03

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

Cation-induced coagulation of aquatic plant-derived dissolved organic matter: Investigation by EEM-PARAFAC and FT-IR spectroscopy.

PubMed

Liu, Shasha; Zhu, Yuanrong; Liu, Leizhen; He, Zhongqi; Giesy, John P; Bai, Yingchen; Sun, Fuhong; Wu, Fengchang

2018-03-01

Complexation and coagulation of plant-derived dissolved organic matter (DOM) by metal cations are important biogeochemical processes of organic matter in aquatic systems. Thus, coagulation and fractionation of DOM derived from aquatic plants by Ca(II), Al(III), and Fe(III) ions were investigated. Metal ion-induced removal of DOM was determined by analyzing dissolved organic carbon in supernatants after addition of these metal cations individually. After additions of metal ions, both dissolved and coagulated organic fractions were characterized by use of fluorescence excitation emission matrix-parallel factor (EEM-PARAFAC) analysis and Fourier transform infrared (FT-IR) spectroscopy. Addition of Ca(II), Fe(III) or Al(III) resulted in net removal of aquatic plant-derived DOM. Efficiencies of removal of DOM by Fe(III) or Al(III) were greater than that by Ca(II). However, capacities to remove plant-derived DOM by the three metals were less than which had been previously reported for humic materials. Molecular and structural features of plant-derived DOM fractions in associations with metal cations were characterized by changes in fluorescent components and infrared absorption peaks. Both aromatic and carboxylic-like organic matters could be removed by Ca(II), Al(III) or Fe(III) ions. Whereas organic matters containing amides were preferentially removed by Ca(II), and phenolic materials were selectively removed by Fe(III) or Al(III). These observations indicated that plant-derived DOM might have a long-lasting effect on water quality and organisms due to its poor coagulation with metal cations in aquatic ecosystems. Plant-derived DOM is of different character than natural organic matter and it is not advisable to attempt removal through addition of metal salts during treatment of sewage. Copyright © 2017 Elsevier Ltd. All rights reserved.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wilson, Rachel M.; Tfaily, Malak M.; Rich, Virginia I.

Once inorganic electron acceptors are depleted, organic matter in anoxic environments decomposes by hydrolysis, fermentation, and methanogenesis, requiring syntrophic interactions between microorganisms to achieve energetic favorability. In this classic anaerobic food chain, methanogenesis represents the terminal electron accepting (TEA) process, ultimately producing equimolar CO2 and CH4 for each molecule of organic matter degraded. However, CO2:CH4 production in Sphagnum-derived, mineral-poor, cellulosic peat often substantially exceeds this 1:1 ratio, even in the absence of measureable inorganic TEAs. Since the oxidation state of C in both cellulose-derived organic matter and acetate is 0, and CO2 has an oxidation state of +4, if CH4more » (oxidation state -4) is not produced in equal ratio, then some other compound(s) must balance CO2 production by receiving 4 electrons. Here we present evidence for ubiquitous hydrogenation of diverse unsaturated compounds that appear to serve as organic TEAs in peat, thereby providing the necessary electron balance to sustain CO2:CH4 >1. While organic electron acceptors have previously been proposed to drive microbial respiration of organic matter through the reversible reduction of quinone moieties, the hydrogenation mechanism that we propose, by contrast, reduces C-C double bonds in organic matter thereby serving as 1) a terminal electron sink, 2) a mechanism for degrading complex unsaturated organic molecules, 3) a potential mechanism to regenerate electron-accepting quinones, and, in some cases, 4) a means to alleviate the toxicity of unsaturated aromatic acids. This mechanism for CO2 generation without concomitant CH4 production has the potential to regulate the global warming potential of peatlands by elevating CO2:CH4 production ratios.« less

Formation of mercury sulfide from Hg(II)−thiolate complexes in natural organic matter

USGS Publications Warehouse

Alain Manceau,; Cyprien Lemouchi,; Mironel Enescu,; Anne-Claire Gaillot,; Martine Lanson,; Valerie Magnin,; Pieter Glatzel,; Poulin, Brett; Ryan, Joseph N.; Aiken, George R.; Isabelle Gautier-Lunea,; Kathryn L. Nagy,

2015-01-01

Methylmercury is the environmental form of neurotoxic mercury that is biomagnified in the food chain. Methylation rates are reduced when the metal is sequestered in crystalline mercury sulfides or bound to thiol groups in macromolecular natural organic matter. Mercury sulfide minerals are known to nucleate in anoxic zones, by reaction of the thiol-bound mercury with biogenic sulfide, but not in oxic environments. We present experimental evidence that mercury sulfide forms from thiol-bound mercury alone in aqueous dark systems in contact with air. The maximum amount of nanoparticulate mercury sulfide relative to thiol-bound mercury obtained by reacting dissolved mercury and soil organic matter matches that detected in the organic horizon of a contaminated soil situated downstream from Oak Ridge, TN, in the United States. The nearly identical ratios of the two forms of mercury in field and experimental systems suggest a common reaction mechanism for nucleating the mineral. We identified a chemical reaction mechanism that is thermodynamically favorable in which thiol-bound mercury polymerizes to mercury–sulfur clusters. The clusters form by elimination of sulfur from the thiol complexes via breaking of mercury–sulfur bonds as in an alkylation reaction. Addition of sulfide is not required. This nucleation mechanism provides one explanation for how mercury may be immobilized, and eventually sequestered, in oxygenated surface environments.

Perry's Scheme of Intellectual and Epistemological Development as a Framework for Describing Student Difficulties in Learning Organic Chemistry

ERIC Educational Resources Information Center

Grove, Nathaniel P.; Bretz, Stacey Lowery

2010-01-01

We have investigated student difficulties with the learning of organic chemistry. Using Perry's Model of Intellectual Development as a framework revealed that organic chemistry students who function as dualistic thinkers struggle with the complexity of the subject matter. Understanding substitution/elimination reactions and multi-step syntheses is…

Production of hybrid striped bass stockers in a biofloc system

USDA-ARS?s Scientific Manuscript database

High yields can be obtained from an outdoor biofloc technology (BFT) production system in response to high stocking and feeding rates because a complex of living organisms, including phytoplankton and bacteria, closely associated with particulate organic matter that is maintained in suspension in th...

Persistence of soil organic matter in eroding versus depositional landform positions

USGS Publications Warehouse

Berhe, Asmeret Asefaw; Harden, Jennifer W.; Torn, Margaret S.; Kleber, Markus; Burton, Sarah D.; Harte, John

2012-01-01

Soil organic matter (SOM) processes in dynamic landscapes are strongly influenced by soil erosion and sedimentation. We determined the contribution of physical isolation of organic matter (OM) inside aggregates, chemical interaction of OM with soil minerals, and molecular structure of SOM in controlling storage and persistence of SOM in different types of eroding and depositional landform positions. By combining density fractionation with elemental and spectroscopic analyses, we showed that SOM in depositional settings is less transformed and better preserved than SOM in eroding landform positions. However, which environmental factors exert primary control on storage and persistence of SOM depended on the nature of the landform position considered. In an annual grassland watershed, protection of SOM by physical isolation inside aggregates and chemical association of organic matter (complexation) with soil minerals, as assessed by correlation with radiocarbon concentration, were more effective in the poorly drained, lowest-lying depositional landform positions, compared to well-drained landform positions in the upper parts of the watershed. Results of this study demonstrated that processes of soil erosion and deposition are important mechanisms of long-term OM stabilization.

Microbial Breakdown of Organic Carbon in the Diverse Sediments of Guaymas Basin

NASA Astrophysics Data System (ADS)

Hoarfrost, A.; Snider, R.; Arnosti, C.

2015-12-01

Guaymas Basin is characterized by sediments under conditions ranging from hemipelagic to hydrothermal. This wide range in geochemical contexts results in diverse microbial communities that may have varying abilities to access organic matter. We can address these functional differences by comparing enzyme activities initializing the breakdown of organic matter across these sediment types; however, previous direct measurements of the extracellular hydrolysis of complex organic carbon in sediments are sparse. We measured this first step of heterotrophic processing of organic matter in sediments at 5-10cm and 55-60cm depth from a wide range of environmental settings in Guaymas Basin. Sediment sources included sulfidic seeps on the Sonora Margin, hemipelagic ridge flank sediments, and hydrothermically altered Sonora Margin sediments bordering a methane seep site. Hydrolysis of organic substrates varied by depth and by sediment source, but despite high energy potential and organic carbon load in sulfidic sediments, activity was not highest where hydrothermal influence was highest. These results suggest that heterotrophic breakdown of organic carbon in Guaymas Basin sediments may be sensitive to factors including varying composition of organic carbon available in different sediment types, or differences in microbial community capacities to access specific organic substrates.

Elucidating Microbial Species-Specific Effects on Organic Matter Transformation in Marine Sediments

NASA Astrophysics Data System (ADS)

Mahmoudi, N.; Enke, T. N.; Beaupre, S. R.; Teske, A.; Cordero, O. X.; Pearson, A.

2017-12-01

Microbial transformation and decomposition of organic matter in sediments constitutes one of the largest fluxes of carbon in marine environments. Mineralization of sedimentary organic matter by microorganisms results in selective degradation such that bioavailable or accessible compounds are rapidly metabolized while more recalcitrant, complex compounds are preserved and buried in sediment. Recent studies have found that the ability to use different carbon sources appears to vary among microorganisms, suggesting that the availability of certain pools of carbon can be specific to the taxa that utilize the pool. This implies that organic matter mineralization in marine environments may depend on the metabolic potential of the microbial populations that are present and active. The goal of our study was to investigate the extent to which organic matter availability and transformation may be species-specific using sediment from Guaymas Basin (Gulf of California). We carried out time-series incubations using bacterial isolates and sterilized sediment in the IsoCaRB system which allowed us to measure the production rates and natural isotopic signatures (δ13C and Δ14C) of microbially-respired CO2. Separate incubations using two different marine bacterial isolates (Vibrio sp. and Pseudoalteromonas sp.) and sterilized Guaymas Basin sediment under oxic conditions showed that the rate and total quantity of organic matter metabolized by these two species differs. Approximately twice as much CO2 was collected during the Vibrio sp. incubation compared to the Pseudoalteromonas sp. incubation. Moreover, the rate at which organic matter was metabolized by the Vibrio sp. was much higher than the Pseudoalteromonas sp. indicating the intrinsic availability of organic matter in sediments may depend on the species that is present and active. Isotopic analyses of microbially respired CO2 will be used to constrain the type and age of organic matter that is accessible to each species. Moreover, molecular analysis of subsamples collected from each incubation will link carbon utilization with the underlying gene expression. Our study sheds light on the degree to which the metabolic capacities of microorganisms affect carbon transformation in sedimentary environments.

Influence of dissolved organic matter on the complexation of mercury under sulfidic conditions.

PubMed

Miller, Carrie L; Mason, Robert P; Gilmour, Cynthia C; Heyes, Andrew

2007-04-01

The complexation of Hg under sulfidic conditions influences its bioavailability for microbial methylation. Neutral dissolved Hg-sulfide complexes are readily available to Hg-methylating bacteria in culture, and thermodynamic models predict that inorganic Hg-sulfide complexes dominate dissolved Hg speciation under natural sulfidic conditions. However, these models have not been validated in the field. To examine the complexation of Hg in natural sulfidic waters, octanol/water partitioning methods were modified for use under environmentally relevant conditions, and a centrifuge ultrafiltration technique was developed. These techniques demonstrated much lower concentrations of dissolved Hg-sulfide complexes than predicted. Furthermore, the study revealed an interaction between Hg, dissolved organic matter (DOM), and sulfide that is not captured by current thermodynamic models. Whereas Hg forms strong complexes with DOM under oxic conditions, these complexes had not been expected to form in the presence of sulfide because of the stronger affinity of Hg for sulfide relative to its affinity for DOM. The observed interaction between Hg and DOM in the presence of sulfide likely involves the formation of a DOM-Hg-sulfide complex or results from the hydrophobic partitioning of neutral Hg-sulfide complexes into the higher-molecular-weight DOM. An understanding of the mechanism of this interaction and determination of complexation coefficients for the Hg-sulfide-DOM complex are needed to adequately assess how our new finding affects Hg bioavailability, sorption, and flux.

Geobacter Project

DOE Office of Scientific and Technical Information (OSTI.GOV)

Derek Lovley; Maddalena Coppi; Stacy Ciufo

Analysis of the Genetic Potential and Gene Expression of Microbial Communities Involved in the In Situ Bioremediation of Uranium and Harvesting Electrical Energy from Organic Matter The primary goal of this research is to develop conceptual and computational models that can describe the functioning of complex microbial communities involved in microbial processes of interest to the Department of Energy. Microbial Communities to be Investigated: (1) Microbial community associated with the in situ bioremediation of uranium-contaminated groundwater; and (2) Microbial community that is capable of harvesting energy from waste organic matter in the form of electricity.

Trace metal mobilization by organic soil amendments: insights gained from analyses of solid and solution phase complexation of cadmium, nickel and zinc.

PubMed

Welikala, Dharshika; Hucker, Cameron; Hartland, Adam; Robinson, Brett H; Lehto, Niklas J

2018-05-01

The accumulation of Cd in soils worldwide has increased the demand for methods to reduce the metal's plant bioavailability. Organic matter rich soil amendments have been shown to be effective in achieving this. However, it is not known how long these amendments can retain the Cd, and whether dissolved organic matter (DOM) released from them can enhance the metal's mobility in the environment. In this study we sought to test the Cd binding capacity of various organic soil amendments, and evaluate differences in characteristics of the DOM released to see if they can explain the lability of the Cd-DOM complexes. We collected ten organic soil amendments from around New Zealand: five different composts, biosolids from two sources, two types of peat and spent coffee grounds. We characterised the amendments' elemental composition and their ability to bind the Cd. We then selected two composts and two peats for further tests, where we measured the sorption of Ni or Zn by the amendments. We analysed the quality of the extracted DOM from the four amendments using 3D Excitation Emission Matrix analysis, and tested the lability of the metal-DOM complexes using an adapted diffusive gradients in thin-films (DGT) method. We found that composts bound the most Cd and that the emergent Cd-DOM complexes were less labile than those from the peats. Ni-DOM complexes were the least labile. The aromaticity of the extracted DOM appears to be an important factor in determining the lability of Ni complexes, but less so for Zn and Cd. Copyright © 2018 Elsevier Ltd. All rights reserved.

Kinetic controls on the complexation between mercury and dissolved organic matter in a contaminated environment.

PubMed

Miller, Carrie L; Southworth, George; Brooks, Scott; Liang, Liyuan; Gu, Baohua

2009-11-15

The interaction of mercury (Hg) with dissolved natural organic matter (NOM) under equilibrium conditions is the focus of many studies but the kinetic controls on Hg-NOM complexation in aquatic systems have often been overlooked. We examined the rates of Hg-NOM complexation both in a contaminated Upper East Fork Poplar Creek (UEFPC) in Oak Ridge, Tennessee, and in controlled laboratory experiments using reducible Hg (Hg(R)) measurements and C(18) solid phase extraction techniques. Of the filterable Hg at the headwaters of UEFPC, >90% was present as Hg(R) and this fraction decreased downstream but remained >29% of the filterable Hg at all sites. The presence of higher Hg(R) concentrations than would be predicted under equilibrium conditions in UEFPC and in experiments with a NOM isolate suggests that kinetic reactions are controlling the complexation between Hg and NOM. The slow formation of Hg-NOM complexes is attributed to competitive ligand exchange among various moieties and functional groups in NOM with a range of binding strengths and configurations. This study demonstrates the need to consider the effects of Hg-NOM complexation kinetics on processes such as Hg methylation and solid phase partitioning.

Residual organic matter and microbial respiration in bottom ash: Effects on metal leaching and eco-toxicity.

PubMed

Ilyas, A; Persson, K M; Persson, M

2015-09-01

A common assumption regarding the residual organic matter, in bottom ash, is that it does not represent a significant pool of organic carbon and, beyond metal-ion complexation process, it is of little consequence to evolution of ash/leachate chemistry. This article evaluates the effect of residual organic matter and associated microbial respiratory processes on leaching of toxic metals (i.e. arsenic, copper, chromium, molybdenum, nickel, lead, antimony and zinc), eco-toxicity of ash leachates. Microbial respiration was quantified with help of a respirometric test equipment OXITOP control system. The effect of microbial respiration on metal/residual organic matter leaching and eco-toxicity was quantified with the help of batch leaching tests and an eco-toxicity assay - Daphnia magna. In general, the microbial respiration process decreased the leachate pH and eco-toxicity, indicating modification of bioavailability of metal species. Furthermore, the leaching of critical metals, such as copper and chromium, decreased after the respiration in both ash types (fresh and weathered). It was concluded that microbial respiration, if harnessed properly, could enhance the stability of fresh bottom ash and may promote its reuse. © The Author(s) 2015.

Chloraminated Concentrated Drinking Water for Disinfection Byproduct Mixtures Research: Evaluating Free Chlorine Contact Times

EPA Science Inventory

Complex mixtures of disinfection by-products (DBPs) are formed when the disinfectant oxidizes constituents (e.g., natural organic matter (NOM) and organic pollutants) present in the source water. Since 1974, over 600 DBPs have been identified in drinking water, yet a large portio...

Chloramination of Concentrated Drinking Water: Evaluation of Disinfection Byproduct Formation and Dosing Scenarios - Portland

EPA Science Inventory

Complex mixtures of disinfection by-products (DBPs) are formed when the disinfectant oxidizes constituents (e.g., natural organic matter (NOM) and organic pollutants) found in the source water. Since 1974, over 600 DBPs have been identified in drinking water. Despite intense iden...

Differential contributions of dorso-ventral and rostro-caudal prefrontal white matter tracts to cognitive control in healthy older adults.

PubMed

Strenziok, Maren; Greenwood, Pamela M; Santa Cruz, Sophia A; Thompson, James C; Parasuraman, Raja

2013-01-01

Prefrontal cortex mediates cognitive control by means of circuitry organized along dorso-ventral and rostro-caudal axes. Along the dorso-ventral axis, ventrolateral PFC controls semantic information, whereas dorsolateral PFC encodes task rules. Along the rostro-caudal axis, anterior prefrontal cortex encodes complex rules and relationships between stimuli, whereas posterior prefrontal cortex encodes simple relationships between stimuli and behavior. Evidence of these gradients of prefrontal cortex organization has been well documented in fMRI studies, but their functional correlates have not been examined with regard to integrity of underlying white matter tracts. We hypothesized that (a) the integrity of specific white matter tracts is related to cognitive functioning in a manner consistent with the dorso-ventral and rostro-caudal organization of the prefrontal cortex, and (b) this would be particularly evident in healthy older adults. We assessed three cognitive processes that recruit the prefrontal cortex and can distinguish white matter tracts along the dorso-ventral and rostro-caudal dimensions -episodic memory, working memory, and reasoning. Correlations between cognition and fractional anisotropy as well as fiber tractography revealed: (a) Episodic memory was related to ventral prefrontal cortex-thalamo-hippocampal fiber integrity; (b) Working memory was related to integrity of corpus callosum body fibers subserving dorsolateral prefrontal cortex; and (c) Reasoning was related to integrity of corpus callosum body fibers subserving rostral and caudal dorsolateral prefrontal cortex. These findings confirm the ventrolateral prefrontal cortex's role in semantic control and the dorsolateral prefrontal cortex's role in rule-based processing, in accordance with the dorso-ventral prefrontal cortex gradient. Reasoning-related rostral and caudal superior frontal white matter may facilitate different levels of task rule complexity. This study is the first to demonstrate dorso-ventral and rostro-caudal prefrontal cortex processing gradients in white matter integrity.

Light Regimes Shape Utilization of Extracellular Organic C and N in a Cyanobacterial Biofilm

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stuart, Rhona K.; Mayali, Xavier; Boaro, Amy A.

2016-06-28

Although it is becoming clear that many microbial primary producers can also play a role as organic consumers, we know very little about the metabolic regulation of photoautotroph organic matter consumption. Cyanobacteria in phototrophic biofilms can reuse extracellular organic carbon, but the metabolic drivers of extracellular processes are surprisingly complex. We investigated the metabolic foundations of organic matter reuse by comparing exoproteome composition and incorporation of 13C-labeled and 15N-labeled cyanobacterial extracellular organic matter (EOM) in a unicyanobacterial biofilm incubated using different light regimes. In the light and the dark, cyanobacterial direct organic C assimilation accounted for 32% and 43%, respectively,more » of all organic C assimilation in the community. Under photosynthesis conditions, we measured increased excretion of extracellular polymeric substances (EPS) and proteins involved in micronutrient transport, suggesting that requirements for micronutrients may drive EOM assimilation during daylight hours. This interpretation was supported by photosynthesis inhibition experiments, in which cyanobacteria incorporated N-rich EOM-derived material. In contrast, under dark, C-starved conditions, cyanobacteria incorporated C-rich EOM-derived organic matter, decreased excretion of EPS, and showed an increased abundance of degradative exoproteins, demonstrating the use of the extracellular domain for C storage. Sequence-structure modeling of one of these exoproteins predicted a specific hydrolytic activity that was subsequently detected, confirming increased EOM degradation in the dark. Associated heterotrophic bacteria increased in abundance and upregulated transport proteins under dark relative to light conditions. Taken together, our results indicate that biofilm cyanobacteria are successful competitors for organic C and N and that cyanobacterial nutrient and energy requirements control the use of EOM. IMPORTANCECyanobacteria are globally distributed primary producers, and the fate of their fixed C influences microbial biogeochemical cycling. This fate is complicated by cyanobacterial degradation and assimilation of organic matter, but because cyanobacteria are assumed to be poor competitors for organic matter consumption, regulation of this process is not well tested. In mats and biofilms, this is especially relevant because cyanobacteria produce an extensive organic extracellular matrix, providing the community with a rich source of nutrients. Light is a well-known regulator of cyanobacterial metabolism, so we characterized the effects of light availability on the incorporation of organic matter. Using stable isotope tracing at the single-cell level, we quantified photoautotroph assimilation under different metabolic conditions and integrated the results with proteomics to elucidate metabolic status. We found that cyanobacteria effectively compete for organic matter in the light and the dark and that nutrient requirements and community interactions contribute to cycling of extracellular organic matter.« less

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

NASA Astrophysics Data System (ADS)

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

2015-12-01

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

Energetic Limitations on Microbial Respiration of Organic Compounds using Aqueous Fe(III) Complexes

NASA Astrophysics Data System (ADS)

Naughton, H.; Fendorf, S. E.

2015-12-01

Soil organic matter constitutes up to 75% of the terrestrial carbon stock. Microorganisms mediate the breakdown of organic compounds and the return of carbon to the atmosphere, predominantly through respiration. Microbial respiration requires an electron acceptor and an electron donor such as small fatty acids, organic acids, alcohols, sugars, and other molecules that differ in oxidation state of carbon. Carbon redox state affects how much energy is required to oxidize a molecule through respiration. Therefore, different organic compounds should offer a spectrum of energies to respiring microorganisms. However, microbial respiration has traditionally focused on the availability and reduction potential of electron acceptors, ignoring the organic electron donor. We found through incubation experiments that the organic compound serving as electron donor determined how rapidly Shewanella putrefaciens CN32 respires organic substrate and the extent of reduction of the electron acceptor. We simulated a range of energetically favorable to unfavorable electron acceptors using organic chelators bound to Fe(III) with equilibrium stability constants ranging from log(K) of 11.5 to 25.0 for the 1:1 complex, where more stable complexes are less favorable for microbial respiration. Organic substrates varied in nominal oxidation state of carbon from +2 to -2. The most energetically favorable substrate, lactate, promoted up to 30x more rapid increase in percent Fe(II) compared to less favorable substrates such as formate. This increased respiration on lactate was more substantial with less stable Fe(III)-chelate complexes. Intriguingly, this pattern contradicts respiration rate predicted by nominal oxidation state of carbon. Our results suggest that organic substrates will be consumed so long as the energetic toll corresponding to the electron donor half reaction is counterbalanced by the energy available from the electron accepting half reaction. We propose using the chemical structure of organic matter, elucidated with techniques such as FT-ICR MS, to improve microbial decomposition and carbon cycling models by incorporating energetic limitations due to carbon oxidation.

Three-Dimensional Anatomy of the White Matter Fibers of the Temporal Lobe: Surgical Implications.

PubMed

Pescatori, Lorenzo; Tropeano, Maria Pia; Manfreda, Andrea; Delfini, Roberto; Santoro, Antonio

2017-04-01

The aim of this work is to describe in detail the complex 3-dimensional organization of the white matter of the temporal lobe and discuss the surgical implications of the approaches to lesions located into the mesial temporal region and within the temporal horn and the atrium of the lateral ventricles. Sixteen human cerebral hemispheres fixed in a 10% formalin solution for at least 40 days were studied. After removal of the arachnoid membrane, the hemispheres were frozen at -15°C for at least 14 days, and the Klingler technique, which consists of the microscopic dissection and progressive identification of white matter fibers, was performed. The dissection allowed us to appreciate the topographical organization of the white matter of the temporal lobe identifying the most important association, projection, and commissural fasciculi. The dissection from the lateral side allowed the progressive visualization of the superior longitudinal fasciculus and its components, the extreme and external capsule, the uncinate fasciculus, the inferior fronto-occipital fasciculus, the anterior commissure, the internal capsule, and the optic radiations. The dissection was completed from the inferior and medial side for identification of the cingulum and the fornix. The complex 3-dimensional organization of the white matter substance of the temporal lobe is characterized by 2 main systems of boundaries: the sagittal stratum and the temporal stem. Their knowledge is essential for the appropriate treatment of pathologies localized in this region as demonstrated by the 2 clinical cases presented in this work. Copyright © 2017 Elsevier Inc. All rights reserved.

Origin of organic matter in the protosolar nebula and in comets

NASA Technical Reports Server (NTRS)

Greenberg, J. M.; Shalabiea, O. M.; Mendoza-Gomez, C. X.; Schutte, W.; Gerakines, P. A.

1994-01-01

Comet organics are traced to their origin in interstellar space. Possible sources of comet organics from solar nebula chemistry are briefly discussed. The infrared spectra of interstellar dust are compared with spectra of solar (space) irradiated laboratory organic residues and with meteorites. The spectra compare very favorably. The atomic composition of first generation laboratory organic residues compares favorably with that of comet Halley organics if divided into approrpriate 'volatile' (less refreactory) and 'refractory' (more refractory) complex organics.

Fact or artifact: the representativeness of ESI-MS for complex natural organic mixtures.

PubMed

Novotny, Nicole R; Capley, Erin N; Stenson, Alexandra C

2014-04-01

Because mass spectrometers provide their own dispersion and resolution of analytes, electrospray ionization mass spectrometry (ESI-MS) has become a workhorse for the characterization of complex mixtures from aerosols to crude oil. Unfortunately, ESI mass spectra commonly contain multimers, adducts and fragments. For the characterization of complex mixtures of unknown initial composition, this presents a significant concern. Mixed-multimer formation could potentially lead to results that bare no resemblance to the original mixture. Conversely, ESI-MS has continually reflected subtle differences between natural organic matter mixtures that are in agreement with prediction or theory. Knowing the real limitations of the technique is therefore critical to avoiding both over-interpretation and unwarranted skepticism. Here, data were collected on four mass spectrometers under a battery of conditions. Results indicate that formation of unrepresentative ions cannot entirely be ruled out, but non-covalent multimers do not appear to make a major contribution to typical natural organic matter spectra based on collision-induced dissociation results. Multimers also appear notably reduced when a cooling gas is present in the accumulation region of the mass spectrometer. For less complex mixtures, the choice of spray solvent can make a difference, but generally spectrum cleanliness (i.e. representativeness) comes at the price of increased selectivity. Copyright © 2014 John Wiley & Sons, Ltd.

Nanospace-Mediated Self-Organization of Nanoparticles in Flexible Porous Polymer Templates.

PubMed

Kuroda, Yoshiyuki; Muto, Itaru; Shimojima, Atsushi; Wada, Hiroaki; Kuroda, Kazuyuki

2017-09-12

Self-organization is a fundamental process for the construction of complex hierarchically ordered nanostructures, which are widespread in biological systems. However, precise control of size, shape, and surface properties is required for self-organization of nanoparticles. Here, we demonstrate a novel self-organization phenomenon mediated by flexible nanospaces in templates. Inorganic nanoparticles (e.g., silica, zirconia, and titania) are deposited in porous polymer thin films with randomly distributed pores on the surface, leaving a partially filled nanospace in each pore. Heating at temperatures beyond the glass transition temperature of the template leads to self-organization of the inorganic nanoparticles into one-dimensional chainlike networks. The self-organization is mediated by the deformation and fusion of the residual nanospaces, and it can be rationally controlled by sequential heat treatments. These results show that a nanospace, defined by the nonexistence of matter, interacts indirectly with matter and can be used as a component of self-organization systems.

Fragmentation studies of fulvic acids using collision induced dissociation fourier transform ion cyclotron resonance mass spectrometry.

PubMed

Witt, Matthias; Fuchser, Jens; Koch, Boris P

2009-04-01

The complex natural organic matter standard Suwannee river fulvic acid (SRFA) was analyzed by negative ion mode electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI FTICR MS) using on-resonance collision induced dissociation (CID) of single ultrahigh resolved mass peaks in the ICR cell. Molecular formula assignment of precursor masses resulted in exactly one molecular formula for each of the peaks. Analyses of the corresponding fragment spectra and comparison to different standard substances revealed specific neutral losses and fragmentation patterns which result in structures consisting of a high degree of carboxyl- and fewer hydroxyl groups. The comparison of fragmented mass peaks within different pseudohomologous series (CH(2)-series, and CH(4) vs O exchange) suggested structurally based differences between these series. CID FTICR MS allowed isolating single mass peaks in a very complex natural organic matter spectrum. Subsequently, fragmentation gave structural insights into this material. Our results suggest that the structural diversity in complex humic substances is not as high as expected.

Iron disulfide minerals and the genesis of roll-type uranium deposits.

USGS Publications Warehouse

Reynolds, R.L.; Goldhaber, M.B.

1983-01-01

Studies of the distribution of and textural relationships among pyrite and marcasite in host rocks for a number of roll-type sedimentary U deposits have enabled identification of several generations of FeS2 minerals. A critical factor influencing mineral formation is the complex relationship of pH and the S species that are precursors of FeS2 minerals. The presence or absence of intrinsic organic matter for bacterial sulphate reduction also plays a key role. In deposits lacking such organic matter, the pre-ore is often euhedral pyrite and the ore-stage is marcasite. In contrast, in deposits containing organic matter the pre-ore is pyrite occurring as framboids or as replacements of plant material, and the ore-stage is also pyrite. These contrasting FeS2 assemblages and their respective modes of origin are consistent with previously proposed biogenic and nonbiogenic theories of the genesis of roll-type U deposits. -J.E.S.

Soil Organic Matter (SOM): Molecular Simulations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Andersen, Amity

Molecular simulation is a powerful tool used to gain an atomistic, molecular, and nanoscale level understanding of the structure, dynamics, and interactions from adsorption on minerals and assembly in aggregates of soil organic matter (SOM). Given the importance of SOM fate and persistence in soils and the current knowledge gaps, applications of atomistic scale simulations to study the complex compounds in SOM and their interactions in self-assembled aggregates composed of different organic matter compounds and with mineral surfaces of different types common in soils are few and far between. Here, we describe various molecular simulation methods that are currently inmore » use in various areas and applicable to SOM research, followed by a brief survey of specific applications to SOM research and an illustration with our own recent efforts in this area. We conclude with an outlook and the challenges for future research in this area.« less

The biogeochemistry of anchialine caves: Progress and possibilities

USGS Publications Warehouse

Pohlman, John W.

2011-01-01

Recent investigations of anchialine caves and sinkholes have identified complex food webs dependent on detrital and, in some cases, chemosynthetically produced organic matter. Chemosynthetic microbes in anchialine systems obtain energy from reduced compounds produced during organic matter degradation (e.g., sulfide, ammonium, and methane), similar to what occurs in deep ocean cold seeps and mud volcanoes, but distinct from dominant processes operating at hydrothermal vents and sulfurous mineral caves where the primary energy source is mantle derived. This review includes case studies from both anchialine and non-anchialine habitats, where evidence for in situ chemosynthetic production of organic matter and its subsequent transfer to higher trophic level metazoans is documented. The energy sources and pathways identified are synthesized to develop conceptual models for elemental cycles and energy cascades that occur within oligotrophic and eutrophic anchialine caves. Strategies and techniques for testing the hypothesis of chemosynthesis as an active process in anchialine caves are also suggested.

Removal of organic matter and ammonia nitrogen from landfill leachate by ultrasound.

PubMed

Wang, Songlin; Wu, Xiaohui; Wang, Yansong; Li, Qifen; Tao, Meijun

2008-09-01

Experiments on the removal of organic matters and ammonia nitrogen from landfill leachate by ultrasound irradiation were carried out. The effects of COD reduction and ammonia removal of power input, initial concentration, initial pH and aeration were studied. It was found that the sonolysis of organic matters proceeds via reaction with ()OH radicals; a thermal reaction also occurs with a small contribution. The rise of COD at some intervals could be explained by the complexity of organic pollutant sonolysis in landfill leachate. Ultrasonic irradiation was shown to be an effective method for the removal of ammonia nitrogen from landfill leachate. After 180 min ultrasound irradiation, up to 96% ammonia nitrogen removal efficiency can be obtained. It was found that the mechanism of ammonia nitrogen removal by ultrasound irradiation is largely that the free ammonia molecules in leachate enter into the cavitation bubbles and transform into nitrogen molecules and hydrogen molecules via pyrolysis under instant high temperature and high pressure in the cavitation bubbles.

Formularity: Software for Automated Formula Assignment of Natural and Other Organic Matter from Ultrahigh-Resolution Mass Spectra.

PubMed

Tolić, Nikola; Liu, Yina; Liyu, Andrey; Shen, Yufeng; Tfaily, Malak M; Kujawinski, Elizabeth B; Longnecker, Krista; Kuo, Li-Jung; Robinson, Errol W; Paša-Tolić, Ljiljana; Hess, Nancy J

2017-12-05

Ultrahigh resolution mass spectrometry, such as Fourier transform ion cyclotron resonance mass spectrometry (FT ICR MS), can resolve thousands of molecular ions in complex organic matrices. A Compound Identification Algorithm (CIA) was previously developed for automated elemental formula assignment for natural organic matter (NOM). In this work, we describe software Formularity with a user-friendly interface for CIA function and newly developed search function Isotopic Pattern Algorithm (IPA). While CIA assigns elemental formulas for compounds containing C, H, O, N, S, and P, IPA is capable of assigning formulas for compounds containing other elements. We used halogenated organic compounds (HOC), a chemical class that is ubiquitous in nature as well as anthropogenic systems, as an example to demonstrate the capability of Formularity with IPA. A HOC standard mix was used to evaluate the identification confidence of IPA. Tap water and HOC spike in Suwannee River NOM were used to assess HOC identification in complex environmental samples. Strategies for reconciliation of CIA and IPA assignments were discussed. Software and sample databases with documentation are freely available.

Physical and chemical evolution of reduced organic matter in the ISM

NASA Technical Reports Server (NTRS)

Jenniskens, Peter; Blake, David F.

1995-01-01

Icy mantles on interstellar grains have been a topic of study in airborne astronomy. Recent laboratory analog studies of the yield of organic residue from UV photolyzed ices have shown that this mechanism can be the most significant source of complex reduced organic matter in the interstellar medium. However, the total yield is a function of the occurrence of heating events that evaporate the ice, i.e. T is greater than 130 K, and the mechanism for such events is debated. Recently, we proposed that the recombination of radicals in the ice does not need high temperature excursions and, instead, occurs during a structural transformation of water ice at temperatures in the range 38 - 68 K.

Can organic matter hide from decomposers in the labyrinth of soil aggregates? Micro-engineered Soil Chips challenging foraging fungi

NASA Astrophysics Data System (ADS)

Hammer, Edith C.; Aleklett, Kristin; Arellano Caicedo, Carlos G.; Bengtsson, Martin; Micaela Mafla Endara, Paola; Ohlsson, Pelle

2017-04-01

From the point of view of microorganisms, the soil environment is an enormously complex labyrinth with paths and dead-end streets, where resources and shelters are unevenly distributed. We study foraging strategies of soil organisms, especially fungi, and the possibility of physio-spatial stabilization of organic matter by "hiding" in occluded soil spaces. We manipulate growth habitat microstructure with lab-on-a-chip techniques, where we designed complex environments with channels and obstacle at dimensions of the size of hyphae, and construct them in the transparent, gas-permeable polymer PDMS. We fill those with different nutrient solutions or combine with mineral nutrient gradients, and inoculate them with soil organisms. We analyze organisms and substrates with microscopy, fluorescence microscopy and analytical chemistry. We compared different soil litter decomposers and an arbuscular mycorrhizal fungus for their ability to forage through complex air-gap structures and attempt to classify them into functional traits concerning their mycelium directionality, space-exploring approach and ability to grow through acute angles and narrow constrictions. We identified structures which are very difficult to penetrate for most species, and compounds located behind such features may thus be spatially unavailable for decomposers. We discuss our approach in comparison to soil pore space tomographic analyses and findings we made in the pore space of colonized wood biochar.

Impact of natural organic matter and increased water hardness on DGT prediction of copper bioaccumulation by yellow lampmussel (Lampsilis cariosa) and fathead minnow (Pimephales promelas).

PubMed

Philipps, Rebecca R; Xu, Xiaoyu; Mills, Gary L; Bringolf, Robert B

2018-06-01

We conducted an exposure experiment with Diffusive Gradients in Thin- Films (DGT), fathead minnow (Pimephales promelas), and yellow lampmussel (Lampsilis cariosa) to estimate bioavailability and bioaccumulation of Cu. We hypothesized that Cu concentrations measured by DGT can be used to predict Cu accumulation in aquatic animals and alterations of water chemistry can affect DGT's predict ability. Three water chemistries (control soft water, hard water, and addition of natural organic matter (NOM)) and three Cu concentrations (0, 30, and 60 μg/L) were selected, so nine Cu-water chemistry combinations were used. NOM addition treatments resulted in decreased concentrations of DGT-measured Cu and free Cu ion predicted by Biotic Ligand Model (BLM). Both hard water and NOM addition treatments had reduced concentrations of Cu ion and Cu-dissolved organic matter complexes compared to other treatments. DGT-measured Cu concentrations were linearly correlated to fish accumulated Cu, but not to mussel accumulated Cu. Concentrations of bioavailable Cu predicted by BLM, the species complexed with biotic ligands of aquatic organisms and, was highly correlated to DGT-measured Cu. In general, DGT-measured Cu fit Cu accumulations in fish, and this passive sampling technique is acceptable at predicting Cu concentrations in fish in waters with low NOM concentrations. Copyright © 2018 Elsevier Ltd. All rights reserved.

Mercury reduction and complexation by natural organic matter in anoxic environments

PubMed Central

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 thiolate ligand-induced oxidative complexation with an estimated binding capacity of ~3.5 μmol Hg/g HA and a partitioning coefficient >106 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 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. PMID:21220311

Interaction of bisphenol A with dissolved organic matter in extractive and adsorptive removal processes.

PubMed

Zhu, Fei-Die; Choo, Kwang-Ho; Chang, Hyun-Shik; Lee, Byunghwan

2012-05-01

The fate of endocrine disrupting chemicals (EDCs) in natural and engineered systems is complicated due to their interactions with various water constituents. This study investigated the interaction of bisphenol A (BPA) with dissolved organic matter (DOM) and colloids present in surface water and secondary effluent as well as its adsorptive removal by powdered activated carbons. The solid phase micro-extraction (SPME) method followed by thermal desorption and gas chromatography-mass spectrometry (GC-MS) was utilized for determining the distribution of BPA molecules in water. The BPA removal by SPME decreased with the increased DOM content, where the formation of BPA-DOM complexes in an aqueous matrix was responsible for the reduced extraction of BPA. Colloidal particles in water samples sorbed BPA leading to the marked reduction of liquid phase BPA. BPA-DOM complexes had a negative impact on the adsorptive removal of BPA by powered activated carbons. The complex formation was characterized based on Fourier transform infrared (FTIR) and ultraviolet-visible (UV-Vis) spectroscopy, along with the calculation of molecular interactions between BPA and functional groups in DOM. It was found that the hydrogen bonding between DOM and BPA would be preferred over aromatic interactions. A pseudo-equilibrium molecular coordination model for the complexation between a BPA molecule and a hydroxyl group of the DOM was developed, which enabled estimation of the maximum sorption site and complex formation constant as well as prediction of organic complexes at various DOM levels. Copyright © 2012 Elsevier Ltd. All rights reserved.

Reactivity and mobilization of permafrost-derived organic matter along the Lena River Delta - Laptev Sea transition

NASA Astrophysics Data System (ADS)

Koch, Boris P.; Dubinenkov, Ivan; Flerus, Ruth; Schmitt-Kopplin, Philippe; Kattner, Gerhard

2015-04-01

The impact of global warming on organic carbon budgets in permafrost systems are not well constrained. Changes in organic carbon fluxes caused by permafrost thaw depend on microbial activity, coastal erosion, mobilization of organic matter by increased porewater fluxes, and the inherent chemical stability of organic matter in permafrost soils. Here we aim at the identification and molecular characterization of active and inactive dissolved organic matter (DOM) components within the river-ocean transition. We studied four transects in the coastal Laptev Sea characterized by steep physico-chemical gradients. Molecular information on solid-phase extracted DOM was derived from ultrahigh resolution mass spectrometry. Changes of the chemical composition with salinity were used as a measure for DOM reactivity. Although changes of dissolved organic carbon (DOC) in the estuary suggested conservative mixing, only 27% of the identified molecular formulas behaved conservatively, 32% were moderately affected, and 41% were actively involved in estuarine processes. The molecular complexity in the DOM samples increased with growing marine influence and the average elemental composition (i.e. relative contribution of organic nitrogen and oxygen compounds) changed significantly with increasing salinity. These chemical changes were consistent with the results of a 20-day microbial incubation experiment, during which more than half of the permafrost-derived DOC was mineralized. We conclude that, although the DOC gradient in the estuary suggests conservative behavior, terrestrial DOM is substantially affected by estuarine processes which in turn also impact organic carbon budgets in the Lena Delta.

Investigation of vertical distribution and morphology of indigenous organic matter at Sleeping Bear site, Michigan

NASA Astrophysics Data System (ADS)

West, C. C.; Lyon, W. G.; Ross, D. L.; Pennington, L. K.

1994-11-01

This study evaluates the nature and origin of particulate organic carbon and organic coatings on aquifer sands upgradient from a fuel spill site near the Sleeping Bear Dunes National Lakeshore in Michigan. The distribution of carbon was found to be highly complex due to the occurrence of high organic carbon horizons, bounded above and below by high carbonate sediments. The organic coatings on the sands were examined using white light and fluorescence microscopy and by scanning electron microscopy. Core samples were analyzed for organic and inorganic carbon, solution pH, humic/fulvic acid ratios, and insoluble organic matter content (that is, humin) as a function of depth from the ground surface. The organic geochemistry of the soil profile at this site was found to be significantly influenced by the carbonates producing a sharp boundary of precipitated organic matter. This boundary was followed by coatings of predominantly fulvic acid salts on mineral grains deeper in the soil column. The coatings extended into the aquifer. The existence of native organic films on sand grains is well documented in the soils literature. The study reported here was greatly aided by this information and provides the framework for future studies concerning the influence of carbon distribution, chemical identity, and morphology on contaminant fate and transport processes.

Complex Organic Parents during Star-Forming Infall

NASA Astrophysics Data System (ADS)

Drozdovskaya, Maria; Walsh, Catherine; Visser, Ruud; Harsono, Daniel; van Dishoeck, Ewine

2013-07-01

Stars are born upon the gravitation infall of clumps in molecular clouds. Complex organic compounds have been observed to accompany star formation and are also believed to be the simplest ingredients to life. Therefore understanding complex organics under star forming conditions is fundamentally interesting. This work models the formation and distribution of several potential parent species for complex organic compounds, such as formaldehyde (H2CO) and methanol (CH3OH), along trajectories of matter parcels, as they undergo infall from the cold outer envelope towards the hot core region and eventually onto the disk. The code from Visser et al. (2009, 2011) serves as the basis for this research. The gas-phase chemistry network has now been expanded with grain-surface reactions to form CH3OH and, ultimately, larger organics such as methyl formate (HCOOCH3) and dimethyl ether (CH3OCH3). The intention behind this work is to obtain information on complex organic parents in the star formation scenario by means of a physically and chemically robust model. The availability of complex organic compounds will vary depending on where the parent species are abundant, such as in the pre-stellar stage, hot-core, or only in the disk; and where they are available for a sufficient amount of time for the complexity enhancement. Such model-based conclusions can then be used in order to explain the observational data on complex organic compounds.

The Effects of Permafrost Thaw on Organic Matter Quality and Availability Along a Hill Slope in Northeastern Siberia

NASA Astrophysics Data System (ADS)

Connolly, C. T.; Spawn, S.; Ludwig, S.; Schade, J. D.; Natali, S.

2014-12-01

Climate warming and permafrost thaw in northeastern Siberia are expected to change the quantity and quality of organic matter (OM) transported through watersheds, releasing previously frozen carbon (C) to biologically available pool. Hill slopes have shown to influence the distribution of OM, resulting in a downhill accumulation of available C and nutrients relative to uphill. Here we examine how future permafrost thaw will change OM quality and availability along a hill slope in a larch-dominated watershed. We collected soils from the thawed organic and mineral layers, and 1m deep permafrost cores for dissolved organic C (DOC) and total dissolved N (TDN), C composition from measures of colored dissolved organic matter (CDOM), DOC lability from biodegradable DOC (BDOC) incubations, C and nutrient availability from extracellular-enzyme assays (EEA's), and microbial respiration from aerobic soil incubations. Here we show that organic soils (O), in comparison to mineral soils (M) and permafrost (P) are the most abundant source of C (avg O DOC: 51.6mg/L), exhibiting low molecular complexity (avg O SUVA254: 4.05) and high quality. Evidence suggests permafrost OM may be an equally abundant, and more labile source of C than mineral soils (highest P DOC: 16.1 mg/L, lowest P SUVA254: 6.32; median M DOC: 18.5 mg/L, median M SUVA254: 24.0). Furthermore, we demonstrate that there may be a positive relationship in the rate of C mineralization and distance downhill, showing 15-30% greater CO2 production/gC downhill relative to uphill. Evidence also supports a similar relationship in permafrost DOC content and molecular complexity, showing more DOC of a lower complexity further downhill. This indicates DOC transport may have been occurring through the active layer and downhill during ice-rich permafrost formation, and may supply a labile source of carbon to lowland areas and adjacent stream networks upon thaw.

Chemical Structural Characteristics of HULIS and Other Fractionated Organic Matter in Urban Aerosols: Results from Mass Spectral and FT-IR Analysis.

PubMed

Chen, Qingcai; Ikemori, Fumikazu; Higo, Hayato; Asakawa, Daichi; Mochida, Michihiro

2016-02-16

The chemical characteristics of complex organic matter in atmospheric aerosols remain poorly understood. Water-insoluble organic matter (WISOM) and water-soluble organic matter (WSOM) in the total suspended particulates collected in the city of Nagoya in summer/early autumn and winter were extracted using multiple solvents. Two fractions of humic-like substances, showing neutral and acidic behavior (HULIS-n and HULIS-a, respectively), and the remaining highly polar part (HP-WSOM) were fractionated from WSOM using solid phase extraction. The chemical structural characteristics and concentrations of the organic matter were investigated using mass spectrometry and Fourier transform infrared (FT-IR) spectroscopy. WISOM and HULIS-n had low O/C ratios (0.1 and 0.4, respectively) and accounted for a large fraction of the organics in aerosols (70%). HULIS-a and HP-WSOM had higher O/C ratios (0.7 and 1.0, respectively), and their concentrations in summer and early autumn were on average ∼2 times higher than those in winter. The mass spectrum and FT-IR analyses suggest the following: (1) WISOM were high-molecular-weight aliphatics (primarily C27-C32) with small proportions of -CH3, -OH, and C═O groups; (2) HULIS-n was abundant in aliphatic structures and hydroxyl groups (primarily C9-C18) and by branched structures; (3) HULIS-a and HP-WSOM contained relatively large amounts of low-molecular-weight carboxylic acids and alcohols (primarily C4-C10); and (4) WISOM and HULIS-n were relatively abundant in amines and organic nitrates.

Seasonal and air mass trajectory effects on dissolved organic matter of bulk deposition at a coastal town in south-western Europe.

PubMed

Santos, Patrícia S M; Santos, Eduarda B H; Duarte, Armando C

2013-01-01

Rainwater contains a complex mixture of organic compounds which may influence climate, terrestrial and maritime ecosystems and thus human health. In this work, the characteristics of DOM of bulk deposition at a coastal town on the southwest of Europe were assessed by UV-visible and three-dimensional excitation-emission matrix fluorescence spectroscopies and by dissolved organic carbon (DOC) content. The seasonal and air mass trajectory effects on dissolved organic matter (DOM) of bulk deposition were evaluated. The absorbance at 250 nm (UV(250 nm)) and integrated fluorescence showed to be positively correlated with each other, and they were also positively correlated to the DOC in bulk deposition, which suggest that a constant fraction of DOM is likely to fluoresce. There was more chromophoric dissolved organic matter (CDOM) present in summer and autumn seasons than in winter and spring. Bulk deposition associated with terrestrial air masses contained a higher CDOM content than bulk deposition related to marine air masses, thus highlighting the contribution of terrestrial/anthropogenic sources.

Characterizing The Microbial Lability And Isotopic (14C, 13C) Signatures Of Marine Organic Matter With A Novel Culture Vessel System

NASA Astrophysics Data System (ADS)

Beaupre, S. R.; Mahmoudi, N.; Pearson, A.

2016-02-01

The rate at which non-living organic matter is respired in the ocean is an unconstrained and important property of the marine carbon cycle. Studies of inherent mineralization rates are complicated by the fact that marine organic matter is a mixture of compounds that vary in reactivity and concentration. While natural radiocarbon ages (14C, half-life = 5730 yr) have served as proxies for lability, they have not been used extensively to characterize that fraction of marine organic matter that is biologically accessible. To address this problem, we developed a novel batch culture system to monitor the time-dependent production rates and isotopic signatures of CO2 released during microbial degradation of natural organic matter. The system simulated a nepheloid layer by maintaining a slurry of decarbonated sediment and minimal media (M9) in a custom 2-liter culture vessel. The natural microbial community was allowed to develop within the sediment, and respired CO2 was continuously sparged from the medium with helium and oxygen, quantified in real time with an infrared gas analyzer, and isolated as a series of contiguous fractions for subsequent isotopic (∆14C, d13C) characterization. Control experiments indicated the accumulation of just 4.5 mg of background carbon per hour of continuous gas flow, which constituted ≤ 10 % of the respired carbon mass in each fraction. Since ∆14C values are conserved during molecular transformations, this low-blank system enables the detection of subtle shifts in the "age" of organic matter respired during the course of a culture experiment. Analyses of sediments from Falmouth, MA revealed both a variable CO2 production rate and an increase in post-bomb ∆14C values during a 10-day incubation. This suggests that the microbial lability of organic matter at this site decreased non-linearly with apparent 14C age, and that the least labile fraction observed was not more than 50 years old. These results underscore the complex relationship between microbial communities, organic matter composition, and its 14C age distribution.

A comparison of soil organic matter physical fractionation methods

NASA Astrophysics Data System (ADS)

Duddigan, Sarah; Alexander, Paul; Shaw, Liz; Collins, Chris

2017-04-01

Selecting a suitable physical fractionation to investigate soil organic matter dynamics from the plethora that are available is a difficult task. An initial investigation of four different physical fractionation methods was conducted (i) Six et al. (2002); (ii) Zimmermann et al. (2007); (iii) Sohi et al. (2001); and (iv) Plaza et al. (2013). Soils used for this were from a long-term organic matter field plot study where a sandy loam soil was subjected to the following treatments: Peat (Pt), Horse Manure (H), Garden Compost (GCf), Garden Compost at half rate (GCh), and a bare plot control (BP). Although each of these methods involved the isolation of unique fractions, in the interest of comparison, each fraction was categorised as either being (i) physically protected (i.e. in aggregates); (ii) chemically protected (such as in organo-mineral complexes); or (iii) unprotected by either of these mechanisms (so-called 'free' organic matter). Regardless of the fractionation method used, a large amount of the variation in total C contents of the different treated soils is accounted for by the differences in unprotected particulate organic matter. When comparing the methods to one another there were no consistent differences in carbon content in the physically protected, chemically protected, or unprotected fractions as operationally defined across all the five organic matter treatments. Therefore fractionation method selection, for this research, was primarily driven by the practicalities of conducting each method in the lab. All of the methods tested had their limitations, for use in this research. This is not a criticism of the methods themselves but largely a result of the lack of suitability for these particular samples. For example, samples that contain a lot of gravel can lead to problems for methods that use size distribution for fractionation. Problems can also be encountered when free particulate organic matter contributes a large proportion of the sample, leaving insufficient sample for further fractionation. This highlights the need for an understanding of the nature of your sample prior to method selection.

Sustainability assessment of traditional fisheries in Cau Hai lagoon (South China Sea).

PubMed

Marconi, Michele; Sarti, Massimo; Marincioni, Fausto

2010-01-01

Overfishing and progressive environmental degradation of the Vietnamese Cau Hai coastal lagoon appear to be threatening the ecological integrity and water quality of the largest estuarine complex of Southeast Asia. This study assessed the relationships between the density of traditional fisheries and organic matter sedimentary contents in Cau Hai lagoon. Data revealed that the density of stake traps (the most common fishing gear used in this lagoon), decreasing hydrodynamic energy in shallow water, causes the accumulation of a large fraction of organic matter refractory to degradation. The relationship between biopolymeric carbon (a proxy of availability of organic matter) and stake traps density fits a S-shape curve. The logistic equation calculated a stake traps density of 90 m of net per hectare, as the threshold over which maximum accumulation of organic matter occurs in Cau Hai. With such level of stake trap density, and assuming a theoretical stationary status of the lagoon, the time necessary for the system to reach hypoxic conditions has been calculated to be circa three weeks. We recommend that this density threshold should not be exceeded in the Cau Hai lagoon and that further analyses of organic loads in the sediment should be conducted to monitor the trophic conditions of this highly eutrophicated lagoon. 2010 Elsevier Ltd. All rights reserved.

Organic matter sources and rehabilitation of the Sacramento-San Joaquin Delta (California, USA)

USGS Publications Warehouse

Jassby, A.D.; Cloern, J.E.

2000-01-01

1. The Sacramento San Joaquin River Delta, a complex mosaic of tidal freshwater habitats in California, is the focus of a major ecosystem rehabilitation effort because of significant long-term changes in critical ecosystem functions. One of these functions is the production, transport and transformation of organic matter that constitutes the primary food supply, which may be sub-optimal at trophic levels supporting fish recruitment. A long historical data set is used to define the most important organic matter sources, the factors underlying their variability, and the implications of ecosystem rehabilitation actions for these sources. 2. Tributary-borne loading is the largest organic carbon source on an average annual Delta-wide basis; phytoplankton production and agricultural drainage are secondary; wastewater treatment plant discharge, tidal marsh drainage and possibly aquatic macrophyte production are tertiary; and benthic microalgal production, urban run-off and other sources are negligible. 3. Allochthonous dissolved organic carbon must be converted to particulate form - with losses due to hydraulic flushing and to heterotroph growth inefficiency - before it becomes available to the metazoan food web. When these losses are accounted for, phytoplankton production plays a much larger role than is evident from a simple accounting of bulk organic carbon sources, especially in seasons critical for larval development and recruitment success. Phytoplankton-derived organic matter is also an important component of particulate loading to the Delta. 4. The Delta is a net producer of organic matter in critically dry years but, because of water diversion from the Delta, transport of organic matter from the Delta to important, downstream nursery areas in San Francisco Bay is always less than transport into the Delta from upstream sources. 5. Of proposed rehabilitation measures, increased use of floodplains probably offers the biggest increase in organic matter sources. 6. An isolated diversion facility - channelling water from the Sacramento River around the Delta to the water projects - would result in substantial loading increases during winter and autumn, but little change in spring and summer when food availability probably matters most to developing organisms. 7. Flow and fish barriers in the channel could have significant effects, especially on phytoplankton sources and in dry years, by eliminating 'short-circuits' in the transport of organic matter to diversion points. 8. Finally, productivity of intentionally flooded islands probably would exceed that of adjacent channels because of lower turbidity and shallower mean depth, although vascular plants rather than phytoplankton could dominate if depths were too shallow. Copyright (C) 2000 John Wiley and Sons, Ltd.

Solubility and transport of Cr(III) in a historically contaminated soil - Evidence of a rapidly reacting dimeric Cr(III) organic matter complex.

PubMed

Löv, Åsa; Sjöstedt, Carin; Larsbo, Mats; Persson, Ingmar; Gustafsson, Jon Petter; Cornelis, Geert; Kleja, Dan B

2017-12-01

Chromium is a common soil contaminant and, although it has been studied widely, questions about its speciation and dissolutions kinetics remain unanswered. We combined information from an irrigation experiment performed with intact soil columns with data from batch experiments to evaluate solubility and mobilization mechanisms of Cr(III) in a historically contaminated soil (>65 years). Particulate and colloidal Cr(III) forms dominated transport in this soil, but their concentrations were independent of irrigation intensity (2-20 mm h -1 ). Extended X-ray absorption fine structure (EXAFS) measurements indicated that Cr(III) associated with colloids and particles, and with the solid phase, mainly existed as dimeric hydrolyzed Cr(III) bound to natural organic matter. Dissolution kinetics of this species were fast (≤1 day) at low pH (<3) and slightly slower (≤5 days) at neutral pH. Furthermore, it proved possible to describe the solubility of the dimeric Cr(III) organic matter complex with a geochemical equilibrium model using only generic binding parameters, opening the way for use of geochemical models in risk assessments of Cr(III)-contaminated sites. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Implications of effluent organic matter and its hydrophilic fraction on zinc(II) complexation in rivers under strong urban pressure: aromaticity as an inaccurate indicator of DOM-metal binding.

PubMed

Louis, Yoann; Pernet-Coudrier, Benoît; Varrault, Gilles

2014-08-15

The zinc binding characteristics of dissolved organic matter (DOM) fractions from the Seine River Basin were studied after being separated and extracted according to their polarity: hydrophobic, transphilic, and hydrophilic. The applied experimental methodology was based on a determination of labile zinc species by means of differential pulse anodic stripping voltammetry (DPASV) at increasing concentrations of total zinc on a logarithmic scale and at fixed levels of: pH, ionic strength, and temperature. Fitting the DOM fractions with two discrete classes of ligands successfully allowed determining the conditional zinc binding constants (Ki) as well as total ligand density (LiT). The binding constants obtained for each DOM fraction were then compared and discussed with respect to the hydrophobic/hydrophilic nature and sample origin. Results highlighted a strong complexation of zinc to the effluent organic matter and especially the most hydrophilic fraction, which also displayed a very low specific UV absorbance. Although the biotic ligand model takes into account the quality of DOM through UV absorbance in the predictions of metal bioavailability and toxicity, this correction is not efficient for urban waters. Copyright © 2014 Elsevier B.V. All rights reserved.

Toward self-organization and complex matter.

PubMed

Lehn, Jean-Marie

2002-03-29

Beyond molecular chemistry based on the covalent bond, supramolecular chemistry aims at developing highly complex chemical systems from components interacting through noncovalent intermolecular forces. Over the past quarter century, supramolecular chemistry has grown into a major field and has fueled numerous developments at the interfaces with biology and physics. Some of the conceptual advances and future challenges are profiled here.

Stable carbon and nitrogen isotope composition of aquatic and terrestrial plants of the San Francisco Bay estuarine system

USGS Publications Warehouse

Cloern, J.E.; Canuel, E.A.; Harris, D.

2002-01-01

We report measurements of seasonal variability in the C-N stable isotope ratios of plants collected across the habitat mosaic of San Francisco Bay, its marshes, and its tributary river system. Analyses of 868 plant samples were binned into 10 groups (e.g., terrestrial riparian, freshwater phytoplankton, salt marsh) to determine whether C-N isotopes can be used as biomarkers for tracing the origins of organic matter in this river-marsh-estuary complex. Variability of ??13C and ??15N was high (???5-10???) within each plant group, and we identified three modes of variability: (1) between species and their microhabitats, (2) over annual cycles of plant growth and senescence, and (3) between living and decomposing biomass. These modes of within-group variability obscure any source-specific isotopic signatures, confounding the application of C-N isotopes for identifying the origins of organic matter. A second confounding factor was large dissimilarity between the ??13C-??15N of primary producers and the organic-matter pools in the seston and sediments. Both confounding factors impede the application of C-N isotopes to reveal the food supply to primary consumers in ecosystems supporting diverse autotrophs and where the isotopic composition of organic matter has been transformed and become distinct from that of its parent plant sources. Our results support the advice of others: variability of C-N stable isotopes within all organic-matter pools is high and must be considered in applications of these isotopes to trace trophic linkages from primary producers to primary consumers. Isotope-based approaches are perhaps most powerful when used to complement other tools, such as molecular biomarkers, bioassays, direct measures of production, and compilations of organic-matter budgets.

News and Views: Gemini hits 1000 papers; Comet Elenin? Forget it! Sellers launches course; Merry Christmas from 18th-century Lapland; ET: where are they all hiding? SETI in the city; Complex organic molecules may not mean life

NASA Astrophysics Data System (ADS)

2011-12-01

No-one has yet found artefacts from an alien civilization, but have we looked hard enough? Astronomers seeking signs of extraterrestrial intelligence have suggested a novel approach: look for alien cities. The search for signs of life in the universe has included the detection of complex organic molecules, seen as a step on the way to living things. But now analysis of spectral signatures known as Unidentified Infrared Emission features found in stars, interstellar space and galaxies suggest that complex organic molecules can be made in stars in a matter of weeks without the presence of life.

Molecular Studies of Complex Soil Organic Matter Interactions with Metal Ions and Mineral Surfaces using Classical Molecular Dynamics and Quantum Chemistry Methods

NASA Astrophysics Data System (ADS)

Andersen, A.; Govind, N.; Laskin, A.

2017-12-01

Mineral surfaces have been implicated as potential protectors of soil organic matter (SOM) against decomposition and ultimate mineralization to small molecules which can provide nutrients for plants and soil microbes and can also contribute to the Earth's elemental cycles. SOM is a complex mixture of organic molecules of biological origin at varying degrees of decomposition and can, itself, self-assemble in such a way as to expose some biomolecule types to biotic and abiotic attack while protecting other biomolecule types. The organization of SOM and SOM with mineral surfaces and solvated metal ions is driven by an interplay of van der Waals and electrostatic interactions leading to partitioning of hydrophilic (e.g. sugars) and hydrophobic (e.g., lipids) SOM components that can be bridged with amphiphilic molecules (e.g., proteins). Classical molecular dynamics simulations can shed light on assemblies of organic molecules alone or complexation with mineral surfaces. The role of chemical reactions is also an important consideration in potential chemical changes of the organic species such as oxidation/reduction, degradation, chemisorption to mineral surfaces, and complexation with solvated metal ions to form organometallic systems. For the study of chemical reactivity, quantum chemistry methods can be employed and combined with structural insight provided by classical MD simulations. Moreover, quantum chemistry can also simulate spectroscopic signatures based on chemical structure and is a valuable tool in interpreting spectra from, notably, x-ray absorption spectroscopy (XAS). In this presentation, we will discuss our classical MD and quantum chemistry findings on a model SOM system interacting with mineral surfaces and solvated metal ions.

Spatial pattern formation of microbes at the soil microscale affect soil C and N turnover in an individual-based microbial community model

NASA Astrophysics Data System (ADS)

Kaiser, Christina; Evans, Sarah; Dieckmann, Ulf; Widder, Stefanie

2016-04-01

At the μm-scale, soil is a highly structured and complex environment, both in physical as well as in biological terms, characterized by non-linear interactions between microbes, substrates and minerals. As known from mathematics and theoretical ecology, spatial structure significantly affects the system's behaviour by enabling synergistic dynamics, facilitating diversity, and leading to emergent phenomena such as self-organisation and self-regulation. Such phenomena, however, are rarely considered when investigating mechanisms of microbial soil organic matter turnover. Soil organic matter is the largest terrestrial reservoir for organic carbon (C) and nitrogen (N) and plays a pivotal role in global biogeochemical cycles. Still, the underlying mechanisms of microbial soil organic matter buildup and turnover remain elusive. We explored mechanisms of microbial soil organic matter turnover using an individual-based, stoichiometrically and spatially explicit computer model, which simulates the microbial de-composer system at the soil microscale (i.e. on a grid of 100 x 100 soil microsites). Soil organic matter dynamics in our model emerge as the result of interactions among individual microbes with certain functional traits (f.e. enzyme production rates, growth rates, cell stoichiometry) at the microscale. By degrading complex substrates, and releasing labile substances microbes in our model continusly shape their environment, which in turn feeds back to spatiotemporal dynamics of the microbial community. In order to test the effect of microbial functional traits and organic matter input rate on soil organic matter turnover and C and N storage, we ran the model into steady state using continuous inputs of fresh organic material. Surprisingly, certain parameter settings that induce resource limitation of microbes lead to regular spatial pattern formation (f.e. moving spiral waves) of microbes and substrate at the μm-scale at steady-state. The occurrence of these pattern can be explained by the Turing mechanism. These pattern formation had strong consequences for process rates, as well as for C and N storage in the soil at the steady state: Scenarios that exhibited pattern formation were generally associated with higher C storage at steady state compared to those without pattern formation (i.e. at non-limiting conditions for microbes). Moreover, pattern formation lead to a spatial decoupling of C and N turnover processes, and to a spatial decoupling of microbial N mineralization and N immobilization. Taken together, our theoretical analysis shows that self-organisation may be a feature of the soil decomposer system, with consequences for process rates of microbial C and N turnover. Pattern formation through spatial self-organization, which has been observed on larger spatial scales in other resource-limited communities (e.g., vegetation patterns in arid or wetland eco-systems), may also occur at the soil microscale, leaving its mark on the soil's storage capacity for C and N.

Defining and Using the Subject Matter Expert's Role in Transforming Army Training and Education Programs

ERIC Educational Resources Information Center

Wilson, William Rollyn

2009-01-01

The United States Army is a complex and diverse organization that must keep pace with the changing global environment to meet its Constitutional responsibility to fight and win the nation's wars. Today, organizations, doctrine, logistics, material, facilities, concepts, techniques, procedures, and training and education are all changing to meet…

Molecular identification of organic compounds in atmospheric complex mixtures and relationship to atmospheric chemistry and sources.

PubMed

Mazurek, Monica A

2002-12-01

This article describes a chemical characterization approach for complex organic compound mixtures associated with fine atmospheric particles of diameters less than 2.5 m (PM2.5). It relates molecular- and bulk-level chemical characteristics of the complex mixture to atmospheric chemistry and to emission sources. Overall, the analytical approach describes the organic complex mixtures in terms of a chemical mass balance (CMB). Here, the complex mixture is related to a bulk elemental measurement (total carbon) and is broken down systematically into functional groups and molecular compositions. The CMB and molecular-level information can be used to understand the sources of the atmospheric fine particles through conversion of chromatographic data and by incorporation into receptor-based CMB models. Once described and quantified within a mass balance framework, the chemical profiles for aerosol organic matter can be applied to existing air quality issues. Examples include understanding health effects of PM2.5 and defining and controlling key sources of anthropogenic fine particles. Overall, the organic aerosol compositional data provide chemical information needed for effective PM2.5 management.

Organic matter in extraterrestrial water-bearing salt crystals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chan, Queenie H. S.; Zolensky, Michael E.; Kebukawa, Yoko

Direct evidence of complex prebiotic chemistry from a water-rich world in the outer solar system is provided by the 4.5-billion-year-old halite crystals hosted in the Zag and Monahans (1998) meteorites. This study offers the first comprehensive organic analysis of the soluble and insoluble organic compounds found in the millimeter-sized halite crystals containing brine inclusions and sheds light on the nature and activity of aqueous fluids on a primitive parent body. Associated with these trapped brines are organic compounds exhibiting wide chemical variations representing organic precursors, intermediates, and reaction products that make up life’s precursor molecules such as amino acids. Themore » organic compounds also contain a mixture of C-, O-, and N-bearing macromolecular carbon materials exhibiting a wide range of structural order, as well as aromatic, ketone, imine, and/or imidazole compounds. The enrichment in 15N is comparable to the organic matter in pristine Renazzo-type carbonaceous chondrites, which reflects the sources of interstellar 15N, such as ammonia and amino acids. The amino acid content of the Zag halite deviates from the meteorite matrix, supporting an exogenic origin of the halite, and therefore, the Zag meteorite contains organics synthesized on two distinct parent bodies. Lastly, our study suggests that the asteroidal parent body where the halite precipitated, potentially asteroid 1 Ceres, shows evidence for a complex combination of biologically and prebiologically relevant molecules.« less

Organic matter in extraterrestrial water-bearing salt crystals

PubMed Central

Chan, Queenie H. S.; Zolensky, Michael E.; Kebukawa, Yoko; Fries, Marc; Ito, Motoo; Steele, Andrew; Rahman, Zia; Nakato, Aiko; Kilcoyne, A. L. David; Suga, Hiroki; Takahashi, Yoshio; Takeichi, Yasuo; Mase, Kazuhiko

2018-01-01

Direct evidence of complex prebiotic chemistry from a water-rich world in the outer solar system is provided by the 4.5-billion-year-old halite crystals hosted in the Zag and Monahans (1998) meteorites. This study offers the first comprehensive organic analysis of the soluble and insoluble organic compounds found in the millimeter-sized halite crystals containing brine inclusions and sheds light on the nature and activity of aqueous fluids on a primitive parent body. Associated with these trapped brines are organic compounds exhibiting wide chemical variations representing organic precursors, intermediates, and reaction products that make up life’s precursor molecules such as amino acids. The organic compounds also contain a mixture of C-, O-, and N-bearing macromolecular carbon materials exhibiting a wide range of structural order, as well as aromatic, ketone, imine, and/or imidazole compounds. The enrichment in 15N is comparable to the organic matter in pristine Renazzo-type carbonaceous chondrites, which reflects the sources of interstellar 15N, such as ammonia and amino acids. The amino acid content of the Zag halite deviates from the meteorite matrix, supporting an exogenic origin of the halite, and therefore, the Zag meteorite contains organics synthesized on two distinct parent bodies. Our study suggests that the asteroidal parent body where the halite precipitated, potentially asteroid 1 Ceres, shows evidence for a complex combination of biologically and prebiologically relevant molecules. PMID:29349297

Organic matter in extraterrestrial water-bearing salt crystals

DOE PAGES

Chan, Queenie H. S.; Zolensky, Michael E.; Kebukawa, Yoko; ...

2018-01-10

Direct evidence of complex prebiotic chemistry from a water-rich world in the outer solar system is provided by the 4.5-billion-year-old halite crystals hosted in the Zag and Monahans (1998) meteorites. This study offers the first comprehensive organic analysis of the soluble and insoluble organic compounds found in the millimeter-sized halite crystals containing brine inclusions and sheds light on the nature and activity of aqueous fluids on a primitive parent body. Associated with these trapped brines are organic compounds exhibiting wide chemical variations representing organic precursors, intermediates, and reaction products that make up life’s precursor molecules such as amino acids. Themore » organic compounds also contain a mixture of C-, O-, and N-bearing macromolecular carbon materials exhibiting a wide range of structural order, as well as aromatic, ketone, imine, and/or imidazole compounds. The enrichment in 15N is comparable to the organic matter in pristine Renazzo-type carbonaceous chondrites, which reflects the sources of interstellar 15N, such as ammonia and amino acids. The amino acid content of the Zag halite deviates from the meteorite matrix, supporting an exogenic origin of the halite, and therefore, the Zag meteorite contains organics synthesized on two distinct parent bodies. Lastly, our study suggests that the asteroidal parent body where the halite precipitated, potentially asteroid 1 Ceres, shows evidence for a complex combination of biologically and prebiologically relevant molecules.« less

Organic matter in extraterrestrial water-bearing salt crystals.

PubMed

Chan, Queenie H S; Zolensky, Michael E; Kebukawa, Yoko; Fries, Marc; Ito, Motoo; Steele, Andrew; Rahman, Zia; Nakato, Aiko; Kilcoyne, A L David; Suga, Hiroki; Takahashi, Yoshio; Takeichi, Yasuo; Mase, Kazuhiko

2018-01-01

Direct evidence of complex prebiotic chemistry from a water-rich world in the outer solar system is provided by the 4.5-billion-year-old halite crystals hosted in the Zag and Monahans (1998) meteorites. This study offers the first comprehensive organic analysis of the soluble and insoluble organic compounds found in the millimeter-sized halite crystals containing brine inclusions and sheds light on the nature and activity of aqueous fluids on a primitive parent body. Associated with these trapped brines are organic compounds exhibiting wide chemical variations representing organic precursors, intermediates, and reaction products that make up life's precursor molecules such as amino acids. The organic compounds also contain a mixture of C-, O-, and N-bearing macromolecular carbon materials exhibiting a wide range of structural order, as well as aromatic, ketone, imine, and/or imidazole compounds. The enrichment in 15 N is comparable to the organic matter in pristine Renazzo-type carbonaceous chondrites, which reflects the sources of interstellar 15 N, such as ammonia and amino acids. The amino acid content of the Zag halite deviates from the meteorite matrix, supporting an exogenic origin of the halite, and therefore, the Zag meteorite contains organics synthesized on two distinct parent bodies. Our study suggests that the asteroidal parent body where the halite precipitated, potentially asteroid 1 Ceres, shows evidence for a complex combination of biologically and prebiologically relevant molecules.

Characterization of organic matter in cloud waters sampled at the puy de Dôme mountain using FT-ICR-MS

NASA Astrophysics Data System (ADS)

Bianco, A.; Chaumerliac, N.; Vaitilingom, M.; Deguillaume, L.; Bridoux, M. C.

2017-12-01

The chemical composition of organic matter in cloud water is highly complex. The organic species result from their dissolution from the gas phase or from the soluble fraction of the particle phase. They are also produced by aqueous phase reactivity. Several low molecular weight organic species have been quantified such as aldehydes and carboxylic acids. Recently, amino acids were also detected in cloud water and their presence is related to the presence of microorganisms. Compounds presenting similarities with high molecular weight organic substances or HULIS found in aerosols were also observed in clouds. Overall, these studies mainly focused on individual compounds or functional groups rather than the complex mixture at the molecular level. This study presents a non-targeted approach to characterize the organic matter in clouds. Samples were collected at the puy de Dôme Mountain (France). Two cloud water samples (June & July 2016) were analyzed using high resolution mass spectrometry (ESI-FT-ICR-MS 9.4T). A reversed solid phase extraction (SPE) procedure was performed to concentrate dissolved organic matter components. Composer (v.1.5.3) software was used to filter the mass spectral data, recalibrate externally the dataset and calculate all possible formulas for detected anions. The first cloud sample (June) resulted from air mass coming from the North (North Sea) while the second one (July) resulted from air mass coming from the West (Atlantic Ocean). Thus, both cloud events derived from marine air masses but were characterized by different hydrogen peroxide concentration and dissolved organic carbon content and were sampled at different periods during the day. Elemental compositions of 6487 and 3284 unique molecular species were identified in each sample. Nitrogen-containing compounds (CHNO compounds), sulfur-containing compounds (CHOS & CHNOS compounds) and other oxygen-containing compounds (CHO compounds) with molecular weights up to 800 Da were detected. The main class is CHNO (53% for both samples) while sulfur-containing compounds represent for the two samples respectively 21 & 14% of the total assigned molecular formulas. CHO compounds molecular formulas are respectively 25 & 32%. Among the two samples, only 2490 molecular formulas were found common to the two samples.

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.

Bacterial Production and Enzymatic Activities in Deep-Sea Sediments of the Pacific Ocean: Biogeochemical Implications of Different Temperature Constraints

NASA Astrophysics Data System (ADS)

Danovaro, R.; Corinaldesi, C.; dell'Anno, A.

2002-12-01

The deep-sea bed, acting as the ultimate sink for organic material derived from the upper oceans primary production, is now assumed to play a key role in biogeochemical cycling of organic matter on global scale. Early diagenesis of organic matter in marine sediments is dependent upon biological processes (largely mediated by bacterial activity) and by molecular diffusion. Organic matter reaching the sea floor by sedimentation is subjected to complex biogeochemical transformations that make organic matter largely unsuitable for direct utilization by benthic heterotrophs. Extracellular enzymatic activities in the sediment is generally recognized as the key step in the degradation and utilization of organic polymers by bacteria and a key role in biopolymeric carbon mobilization is played by aminopeptidase, alkaline phosphatase and glucosidase activities. In the present study we investigated bacterial density, bacterial C production and exo-enzymatic activities (aminopeptidase, glucosidase and phosphatase activity) in deep-sea sediments of the Pacific Ocean in relation with the biochemical composition of sediment organic matter (proteins, carbohydrates and lipids), in order to gather information on organic matter cycling and diagenesis. Benthic viral abundance was also measured to investigate the potential role of viruses on microbial loop functioning. Sediment samples were collected at eight stations (depth ranging from 2070-3100 m) along two transects located at the opposite side (north and south) of ocean seismic ridge Juan Fernandez (along latitudes 33° 20' - 33° 40'), constituted by the submerged vulcanoes, which connects the Chilean coasts to Rapa Nui Island. Since the northern and southern sides of this ridge apparently displayed small but significant differences in deep-sea temperature (related to the general ocean circulation), this sampling strategy allowed also investigating the role of different temperature constraints on bacterial activity and biogeochemical processes and to define possible scenarios dealing with climate induced changes in deep-sea conditions.

[Effect of Charge-Transfer Complex on Ultraviolet-Visible (UV-Vis) Absorption Property of Chromophoric Dissolved Organic Matter (CDOM) in Waters of Typical Water-Level Fluctuation Zones of the Three Gorges Reservoir Areas].

PubMed

Jiang, Tao; Liang, Jian; Zhang, Mu-xue; Wang, Ding-yong; Wei, Shi-qiang; Lu, Song

2016-02-15

As an important fraction of dissolved organic matter (DOM), chromophoric dissolved organic matter (CDOM) plays a key role in decision of the optical properties and photogeochemistry of DOM, and further affects pollutant fate and global carbon cycle. These optical properties are ascribed to two chromophoric systems including superposition of individual chromophores and charge-transfer (CT) complexation between electron donor (e.g., phenols and indoles) and acceptor (e.g., quinones and other oxidized aromatics) in DOM structures. Thus in this study, based on the "double-chromophoric system" model, DOM samples from four typical water-level fluctuation zones of Three Gorges Reservoir (TGR) areas were selected, to investigate the effect and contribution of charge-transfer complex to ultraviolet-visible (UV-Vis) absorption property of CDOM. Using NaBH, reduction method, original featureless absorption curve was classified into two independent curves caused by individual chromophoric group, which were derived from a simple superposition of independent chromophore and charge-transfer complex, respectively. Also, the changes in curve properties and specific parameters before and after NaBH4 reduction were compared. The results showed that in all DOM samples from the four sites of TGR, more than 35% of absorption was attributed from CT complex. Shibaozhai of Zhongxian and Zhenxi of Fuling showed the highest proportion ( > 50%). It suggested that the role of CT complex in CDOM property could not be neglected. After removal of CT complex, absorption curve showed blue-shift and CDOM concentration [a (355)] decreased significantly. Meanwhile, because of deforming of bonds by reduction, DOM structures became more dispersive and the molecular size was decreased, resulting in the lower spectral slope (S) observed, which evidentially supported that the supermolecular association structure of DOM was self-assembled through CT complex. Meanwhile, deceasing hydrophobic components led to decreased apparent aromaticity (lower SUVA values), whereas specific parameters including SUVA, CDOM and SR still were applicable for comparison among different DOM samples instead of the same sample without consideration of "double-cbromopboric system" model involving tbe role of CT complex. Comparatively, S(275-295) was dynamic due to tbe impact of CT effect. Furtbermore, establisbing DOC estimation model by short-wavelength range of CDOM was recommended because of its stability despite of CT complex.

Sediment-water partitioning of inorganic mercury in estuaries.

PubMed

Turner, A; Millward, G E; Le Roux, S M

2001-12-01

The sediment-water partitioning and speciation of inorganic mercury have been studied under simulated estuarine conditions by monitoring the hydrophobicity and uptake of dissolved 203Hg(II) in samples from a variety of estuarine environments. A persistent increase in the distribution coefficientwith increasing salinity is inconsistent with inorganic speciation calculations, which predict an increase in the concentration of the soluble HgCl4(2-) complex (or reduction in sediment-water distribution coefficient) with increasing salinity. Partition data are, however, defined by an empirical equation relating to the salting out of nonelectrolytes via electrostriction and are characterized by salting constants between about 1.4 and 2.0 L mol(-1). Salting out of the neutral, covalent chloro-complex, HgCl2(0), is predicted but cannot account for the magnitude of salting out observed. Since Hg(II) strongly complexes with dissolved (and particulate) organic matter in natural environments, of more significance appears to be the salting out of Hg(II)-organic complexes. Operational measurements of the speciation of dissolved Hg(II) using Sep-Pak C18 columns indicate a reduction in the proportion of hydrophobic (C18-retained) dissolved Hg(II) complexes with increasing salinity, both in the presence and absence of suspended particles. Ratios of hydrophobic Hg(ll) before and after particle addition suggest a coupled salting out-sorption mechanism, with the precise nature of Hg(II) species salted out being determined bythe characteristics and concentrations of dissolved and sediment organic matter.

A ω-mercaptoundecylphosphonic acid chemically modified gold electrode for uranium determination in waters in presence of organic matter.

PubMed

Merli, Daniele; Protti, Stefano; Labò, Matteo; Pesavento, Maria; Profumo, Antonella

2016-05-01

A chemically modified electrode (CME) on a gold surface assembled with a ω-phosphonic acid terminated thiol was investigated for its capability to complex uranyl ions. The electrode, characterized by electrochemical techniques, demonstrated to be effective for the determination of uranyl at sub-μgL(-1) level by differential pulse adsorptive stripping voltammetry (DPAdSV) in environmental waters, also in presence of humic matter and other potential chelating agents. The accuracy of the measurements was investigated employing as model probes ligands of different complexing capability (humic acids and EDTA). Copyright © 2016 Elsevier B.V. All rights reserved.

Preparatory steps for a robust dynamic model for organically bound tritium dynamics in agricultural crops

DOE Office of Scientific and Technical Information (OSTI.GOV)

Melintescu, A.; Galeriu, D.; Diabate, S.

2015-03-15

The processes involved in tritium transfer in crops are complex and regulated by many feedback mechanisms. A full mechanistic model is difficult to develop due to the complexity of the processes involved in tritium transfer and environmental conditions. First, a review of existing models (ORYZA2000, CROPTRIT and WOFOST) presenting their features and limits, is made. Secondly, the preparatory steps for a robust model are discussed, considering the role of dry matter and photosynthesis contribution to the OBT (Organically Bound Tritium) dynamics in crops.

Extraction of an urease-active organo-complex from soil.

NASA Technical Reports Server (NTRS)

Burns, R. G.; El-Sayed, M. H.; Mclaren, A. D.

1972-01-01

Description of an extraction from a Dublin clay loam soil of a colloidal organic matter complex that is urease active and, by X-ray analysis, free of clays. Urease activity in the clay-free precipitates, as in the soil, was not destroyed by the activity of an added proteolytic enzyme, pronase. This is attributed to the circumstance that native soil urease resides in organic colloidal particles with pores large enough for water, urea, ammonia, and carbon dioxide to pass freely, but nevertheless small enough to exclude pronase.

Self-organizing biochemical cycle in dynamic feedback with soil structure

NASA Astrophysics Data System (ADS)

Vasilyeva, Nadezda; Vladimirov, Artem; Smirnov, Alexander; Matveev, Sergey; Tyrtyshnikov, Evgeniy; Yudina, Anna; Milanovskiy, Evgeniy; Shein, Evgeniy

2016-04-01

In the present study we perform bifurcation analysis of a physically-based mathematical model of self-organized structures in soil (Vasilyeva et al., 2015). The state variables in this model included microbial biomass, two organic matter types, oxygen, carbon dioxide, water content and capillary pore size. According to our previous experimental studies, organic matter affinity to water is an important property affecting soil structure. Therefore, organic matter wettability was taken as principle distinction between organic matter types in this model. It considers general known biological feedbacks with soil physical properties formulated as a system of parabolic type non-linear partial differential equations with elements of discrete modeling for water and pore formation. The model shows complex behavior, involving emergence of temporal and spatial irregular auto-oscillations from initially homogeneous distributions. The energy of external impact on a system was defined by a constant oxygen level on the boundary. Non-linear as opposed to linear oxygen diffusion gives possibility of modeling anaerobic micro-zones formation (organic matter conservation mechanism). For the current study we also introduced population competition of three different types of microorganisms according to their mobility/feeding (diffusive, moving and fungal growth). The strongly non-linear system was solved and parameterized by time-optimized algorithm combining explicit and implicit (matrix form of Thomas algorithm) methods considering the time for execution of the evaluated time-step according to accuracy control. The integral flux of the CO2 state variable was used as a macroscopic parameter to describe system as a whole and validation was carried out on temperature series of moisture dependence for soil heterotrophic respiration data. Thus, soil heterotrophic respiration can be naturally modeled as an integral result of complex dynamics on microscale, arising from biological processes formulated as a sum of state variables products, with no need to introduce any saturation functions, such as Mikhaelis-Menten type kinetics, inside the model. Analyzed dynamic soil model is being further developed to describe soil structure formation and its effect on organic matter decomposition at macro-scale, to predict changes with external perturbations. To link micro- and macro-scales we additionally model soil particles aggregation process. The results from local biochemical soil organic matter cycle serve as inputs to aggregation process, while the output aggregate size distributions define physical properties in the soil profile, these in turn serve as dynamic parameters in local biochemical cycles. The additional formulation is a system of non-linear ordinary differential equations, including Smoluchowski-type equations for aggregation and reaction kinetics equations for coagulation/adsorption/adhesion processes. Vasilyeva N.A., Ingtem J.G., Silaev D.A. Nonlinear dynamical model of microbial growth in soil medium. Computational Mathematics and Modeling, vol. 49, p.31-44, 2015 (in Russian). English version is expected in corresponding vol.27, issue 2, 2016.

Why dissolved organic matter (DOM) enhances photodegradation of methylmercury

DOE Office of Scientific and Technical Information (OSTI.GOV)

Qian, Yun; Yin, Xiangping Lisa; Brooks, Scott C

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 degradationmore » 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.« less

Formation and processing of organics in the early solar system.

PubMed

Kerridge, J F

1999-01-01

Until pristine samples can be returned from cometary nuclei, primitive meteorites represent our best source of information about organic chemistry in the early solar system. However, this material has been affected by secondary processing on asteroidal parent bodies which probably did not affect the material now present in cometary nuclei. Production of meteoritic organic matter apparently involved the following sequence of events: Molecule formation by a variety of reaction pathways in dense interstellar clouds; Condensation of those molecules onto refractory interstellar grains; Irradiation of organic-rich interstellar-grain mantles producing a range of molecular fragments and free radicals; Inclusion of those interstellar grains into the protosolar nebula with probable heating of at least some grain mantles during passage through the shock wave bounding the solar accretion disc; Agglomeration of residual interstellar grains and locally produced nebular condensates into asteroid-sized planetesimals; Heating of planetesimals by decay of extinct radionuclides; Melting of ice to produce liquid water within asteroidal bodies; Reaction of interstellar molecules, fragments and radicals with each other and with the aqueous environment, possibly catalysed by mineral grains; Loss of water and other volatiles to space yielding a partially hydrated lithology containing a complex suite of organic molecules; Heating of some of this organic matter to generate a kerogen-like complex; Mixing of heated and unheated material to yield the meteoritic material now observed. Properties of meteoritic organic matter believed to be consistent with this scenario include: Systematic decrease of abundance with increasing C number in homologous series of characterisable molecules; Complete structural diversity within homologous series; Predominance of branched-chain isomers; Considerable isotopic variability among characterisable molecules and within kerogen-like material; Substantial deuterium enrichment in all organic fractions; Some fractions significantly enriched in nitrogen-15; Modest excesses of L-enantiomers in some racemisation-resistant molecules but no general enantiomeric preference. Despite much speculation about the possible role of Fischer-Tropsch catalytic hydrogenation of CO in production of organic molecules in the solar nebula, no convincing evidence for such material has been found in meteorites. A similarity between some meteoritic organics and those produced by Miller-Urey discharge synthesis may reflect involvement of common intermediates rather than the operation of electric discharges in the early solar system. Meteoritic organic matter constitutes a useful, but not exact, guide to what we shall find with in situ analytical and sample-return missions to cometary nuclei.

Organic matter in primitive meteorites: a study of the hydrogen isotopic distribution in CM-type carbonaceous chondrites

NASA Astrophysics Data System (ADS)

Piani, L.; Yurimoto, H.; Remusat, L.; Gonzales, A.; Marty, B.

2017-12-01

Chondrite meteorites are fragments of rocks coming from small bodies of the asteroid belt and constitute witnesses of the volatile-rich reservoirs present in the inner protoplanetary disk. Among these meteorites, carbonaceous chondrites contain the largest quantity of water and organic matter and are one of the most probable candidates for the delivery of water and molecular origin of life to Earth. Organic matter in carbonaceous chondrites is intimately mixed with hydrated minerals challenging its in situ characterization and the determination of its H-isotope composition (Le Guillou et al., GCA 131, 2014). Organic matter occurs as soluble components (in water or organic solvents) and an insoluble macromolecule. The insoluble organic matter (IOM) is efficiently isolated after acid leaching of the chondrite minerals. IOM has thus been investigated by a large set of analytical techniques allowing its structural organization, chemical composition and isotopic composition to be determined at several scales (e.g. Derenne and Robert, MAPS 45, 2010). In the soluble counterpart (SOM), targeted studies have shown large ranges of D/H ratios in the different classes of soluble organic compounds (i.e. carboxylic acids, ketones and aldehydes, amino-acids etc.) (Remusat, Planetary Mineralogy 15, 2015 and references therein). This D/H distribution indicates a complex and probably multiple-stage synthesis of this organic compounds occurring at different stages of the disk evolution. Nevertheless, inventories of the known C-bearing species in carbonaceous chondrites (carbonates, SOM and IOM) show that about 40-50 % of the carbon is hidden within the matrix (Alexander et al., MAPS 50, 2015). In this study, we perform in situ hydrogen isotope analyses at the micrometer scale by secondary ion mass spectrometry to investigate the distribution of organic matter in primitive chondrites without the use of any chemical treatment. Correlated analyses of the D/H and C/H ratios allow us to decipher the H contribution of water-bearing minerals and to estimate the hydrogen isotopic composition of water in chondrites (Piani et al., submitted). Comparison of spot analyses and isotope images obtained in situ and on isolated IOM gives clues on the nature of the organic components of carbonaceous asteroid rocks.

Carbon Dioxide Effects Research and Assessment Program. The role of tropical forests on the world carbon cycle

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brown, S.; Lugo, A. E.; Liegel, B.

1980-08-01

Tropical forests constitute about half of the world's forest and are characterized by rapid rates of organic matter turnover and high storages of organic matter. Tropical forests are considered to be one of the most significant terrestrial elements in the equation that balances the carbon cycle of the world. As discussed in the paper by Tosi, tropical and subtropical latitudes are more complex in terms of climate and vegetation composition than temperate and boreal latitudes. The implications of the complexity of the tropics and the disregard of this complexity by many scientists is made evident in the paper by Brownmore » and Lugo which shows that biomass estimates for tropical ecosystems have been overestimated by at least 100%. The paper by Brown shows that that rates of succession in the tropics are extremely rapid in terms of the ability of moist and wet forests to accumulate organic matter. Yet, in arid tropical Life Zones succession is slow. This leads to the idea that the question of whether tropical forests are sinks or sources of carbon must be analyzed in relation to Life Zones and to intensities of human activity in these Zones. The paper by Lugo presents conceptual models to illustrate this point and the paper by Tosi shows how land uses in the tropics also correspond to Life Zone characteristics. The ultimate significance of land use to the question of the carbon balance in a large region is addressed in the paper by Detwiler and Hall.« less

Sedimentary organic matter in two Spitsbergen fjords: Terrestrial and marine contributions based on carbon and nitrogen contents and stable isotopes composition

NASA Astrophysics Data System (ADS)

Koziorowska, Katarzyna; Kuliński, Karol; Pempkowiak, Janusz

2016-02-01

The aim of this study was to estimate the spatial variability of organic carbon (Corg) and total nitrogen (Ntot) concentrations, Corg/Ntot ratios, stable isotopes of carbon and nitrogen (δ13Corg, δ15Ntot) and the proportions of autochthonous and allochtonous organic matter within recently deposited sediments of two Spitsbergen fjords: the Hornsund and the Adventfjord, which are affected to a different degree by the West Spitsbergen Current. Corg concentrations ranged from 1.38% to 1.98% in the Hornsund and from 1.73% to 3.85% in the Adventfjord. In both fjords the highest Corg concentrations were measured at the innermost stations and they decreased towards the mouths of the fjords. This suggests fresh water runoff to be an important source of organic matter (OM) for surface sediments. The results showed that both fjords differ significantly in terms of sedimentary organic matter characteristics. The samples from the Hornsund, except those from the innermost station in the Brepollen, had relatively low Corg/Ntot ratios, all within a narrow range (from 9.7 to 11.3). On the other hand significantly higher Corg/Ntot ratios, varying within a broad range (from 14.6 to 33.0), were measured in the Adventfjord. The samples from the Hornsund were characterized by higher δ13Corg (from -24.90‰ to -23.87‰) and δ15Ntot (from 3.02‰ to 4.93‰) than those from the Adventfjord (-25.94‰ to -24.69‰ and from 0.71‰ to 4.00‰, respectively). This is attributed to a larger proportion of marine organic matter. Using the two end-member approach proportions of terrestrial organic matter were evaluated. Terrestrial OM contribution for the Adventfjord was in the range of 82-83%, while in case of the Hornsund the results were in the range of 69-75%, with the exception of the innermost part of the fjord, where terrestrial organic matter contribution ranged from 80 to 82%. The strong positive correlation between δ13Corg and δ15Ntot was revealed. This was taken as an indicator that fresh, labile organic matter is the base of the trophic pyramid. The conclusion regarding a more complex food web in the Horsund, based on larger δ15Ntot values, is further substantiated by the larger proportion of autochthonous, labile organic matter found in the Hornsund's sediments.

Differential Contributions of Dorso-Ventral and Rostro-Caudal Prefrontal White Matter Tracts to Cognitive Control in Healthy Older Adults

PubMed Central

Strenziok, Maren; Greenwood, Pamela M.; Santa Cruz, Sophia A.; Thompson, James C.; Parasuraman, Raja

2013-01-01

Prefrontal cortex mediates cognitive control by means of circuitry organized along dorso-ventral and rostro-caudal axes. Along the dorso-ventral axis, ventrolateral PFC controls semantic information, whereas dorsolateral PFC encodes task rules. Along the rostro-caudal axis, anterior prefrontal cortex encodes complex rules and relationships between stimuli, whereas posterior prefrontal cortex encodes simple relationships between stimuli and behavior. Evidence of these gradients of prefrontal cortex organization has been well documented in fMRI studies, but their functional correlates have not been examined with regard to integrity of underlying white matter tracts. We hypothesized that (a) the integrity of specific white matter tracts is related to cognitive functioning in a manner consistent with the dorso-ventral and rostro-caudal organization of the prefrontal cortex, and (b) this would be particularly evident in healthy older adults. We assessed three cognitive processes that recruit the prefrontal cortex and can distinguish white matter tracts along the dorso-ventral and rostro-caudal dimensions –episodic memory, working memory, and reasoning. Correlations between cognition and fractional anisotropy as well as fiber tractography revealed: (a) Episodic memory was related to ventral prefrontal cortex-thalamo-hippocampal fiber integrity; (b) Working memory was related to integrity of corpus callosum body fibers subserving dorsolateral prefrontal cortex; and (c) Reasoning was related to integrity of corpus callosum body fibers subserving rostral and caudal dorsolateral prefrontal cortex. These findings confirm the ventrolateral prefrontal cortex's role in semantic control and the dorsolateral prefrontal cortex's role in rule-based processing, in accordance with the dorso-ventral prefrontal cortex gradient. Reasoning-related rostral and caudal superior frontal white matter may facilitate different levels of task rule complexity. This study is the first to demonstrate dorso-ventral and rostro-caudal prefrontal cortex processing gradients in white matter integrity. PMID:24312550

Chemical fractionation-enhanced structural characterization of marine dissolved organic matter

NASA Astrophysics Data System (ADS)

Arakawa, N.; Aluwihare, L.

2016-02-01

Describing the molecular fingerprint of dissolved organic matter (DOM) requires sample processing methods and separation techniques that can adequately minimize its complexity. We have employed acid hydrolysis as a way to make the subcomponents of marine solid phase-extracted (PPL) DOM more accessible to analytical techniques. Using a combination of NMR and chemical derivatization or reduction analyzed by comprehensive (GCxGC) gas chromatography, we observed chemical features strikingly similar to terrestrial DOM. In particular, we observed reduced alicylic hydrocarbons believed to be the backbone of previously identified carboxylic rich alicyclic material (CRAM). Additionally, we found carbohydrates, amino acids and small lipids and acids.

A Review on Advanced Treatment of Pharmaceutical Wastewater

NASA Astrophysics Data System (ADS)

Guo, Y.; Qi, P. S.; Liu, Y. Z.

2017-05-01

The composition of pharmaceutical wastewater is complex, which is high concentration of organic matter, microbial toxicity, high salt, and difficult to biodegrade. After secondary treatment, there are still trace amounts of suspended solids and dissolved organic matter. To improve the quality of pharmaceutical wastewater effluent, advanced treatment is essential. In this paper, the classification of the pharmaceutical technology was introduced, and the characteristics of pharmaceutical wastewater effluent quality were summarized. The methods of advanced treatment of pharmaceutical wastewater were reviewed afterwards, which included coagulation and sedimentation, flotation, activated carbon adsorption, membrane separation, advanced oxidation processes, membrane separation and biological treatment. Meanwhile, the characteristics of each process were described.

Zinc and copper behaviour at the soil-river interface: New insights by Zn and Cu isotopes in the organic-rich Rio Negro basin

NASA Astrophysics Data System (ADS)

Guinoiseau, Damien; Gélabert, Alexandre; Allard, Thierry; Louvat, Pascale; Moreira-Turcq, Patricia; Benedetti, Marc F.

2017-09-01

The complex behaviour of Zn and Cu at the soil-river interface was investigated in soil and riverine water samples from the Rio Negro basin, a secondary tributary of the Rio Amazonas, using their stable isotope compositions. This acidic and organic river drains two types of intensely weathered terrains: podzols in its upstream part, and lateritic soils downstream. Bulk soil particles, suspended particulate matter (SPM) as well as colloidal fractions were sampled across the whole basin during low and high water stages. In the basin, Zn and Cu are mostly exported from lateritic soils and transported by organic colloids where significant losses are observed in the downstream part of the river. The use of δ66Zn and δ65Cu measurements reveals distinct stories for these two metals in suspended sediments and colloids. In the colloids, the constant δ66Zncoll across the basin is induced by the same weak association mode between Zn and organic ligands, regardless of the origin of the water. By contrast, in SPM, the speciation of Zn and thus δ66ZnSPM differ according to the type of drained soils. Zn is associated with organic complexes in particles exported with water draining podzol whereas Zn2+ is incorporated in the structure of the remaining kaolinite clays in lateritic output. The stronger reactivity of Cu than Zn with organic ligands induces its complete complexation. Copper is controlled by refractory particulate organic matter (POM) and by reactive colloidal organic matter; the latter being enriched in 65Cu due to stronger binding interactions than in POM. While the Cu content remains constant in the upstream part of the Rio Negro, downstream, the decrease of SPM and colloidal Cu fluxes is associated with a constant δ65CuSPM and with an increase of δ65Cucoll at the Rio Negro outlet. Geochemical mass balance modelling, based on SPM, Cu and Zn fluxes in SPM and their associated isotopic signatures, confirms distinct host phases for Zn and Cu, and identifies the most probable places where losses of these two metals occur. In colloids, the observed Cu isotope fractionation (from 0.24 to 0.45‰) superimposed on the significant Cucoll loss is assumed to result from a new isotopic equilibrium in a low velocity and high productivity zone: Cu-rich colloids enriched in 63Cu aggregate and settle down, whereas the remaining heavy Cu is partially complexed on strong organic ligands secreted by phytoplankton, forming new Cu-colloids.

Controls on the distribution of arsenic in lake sediments impacted by 65 years of gold ore processing in subarctic Canada: the role of organic matter

NASA Astrophysics Data System (ADS)

Galloway, Jennifer; Palmer, Michael; Swindles, Graeme T.; Sanei, Hamed; Jamieson, Heather E.; Parsons, Michael; Macumber, Andrew L.; Patterson, Tim; Falck, Hendrik

2017-04-01

Gold mines in the Yellowknife region of the Northwest Territories, Canada, operated from 1938 to 2003 and released approximately 20,000 tonnes of arsenic trioxide to the environment through stack emissions. This release resulted in highly elevated arsenic concentrations in lake surface waters and sediments relative to Canadian drinking water standards and guidelines for the protection of aquatic life. High northern latitudes are experiencing substantial impacts, including changes in bio-physico-chemical processes, due to climate change. Determining the affect of warming climate on contamination is complicated by the fact that little is known of climate change controls on As mobility and bioavailability. Further, while the role of dissolved organic matter in As cycling is relatively well characterized in soils and wetland sediments, few studies have investigated the role of solid organic matter in lacustrine systems. We use a meta-analytical approach to better understand controls on sedimentary arsenic distribution in lakes within a 50 km2 area of historic mineral processing activities. Arsenic concentrations in near surface sediments of the 100 lakes studied range from 5 mg/kg to over 10,000 mg/kg (median 81 mg/kg). Distance from the historical Giant Mine roaster stack and the amount of labile organic matter (S1 carbon as determined by Rock Eval pyrolysis) in lake sediments are the variables most strongly correlated with sedimentary As concentrations (Spearman's rank correlation As:distance from historic roaster rs=-0.57, p<0.05; As:S1 rs=0.55, p<0.05). The S1 fraction, volatile hydrocarbons derived from readily degradable geolipids and pigments predominantly originating from authochthonous organic matter, represents a small portion of the overall total organic carbon in the sedimentary material analyzed (median 2.33 wt.%). However, this fraction of organic matter has large potential to influence element concentrations in lake sediments through coating of pre-existing solid-phase As-mineral complexes, direct As-organic matter interactions, and promotion of microbial-mediated reduction and precipitation of As-bearing minerals.

Investigation of vertical distribution and morphology of indigenous organic matter Sleeping Bear site, Michigan

DOE Office of Scientific and Technical Information (OSTI.GOV)

West, C.C.; Lyon, W.G.; Ross, D.L.

1994-11-01

This study evaluates the nature and origin of particulate organic carbon and organic coatings on aquifer sands upgradient from a fuel spill site near the Sleeping Bear Dunes National Lakeshore in Michigan. The distribution of carbon was found to be highly complex due to the occurrence of high organic carbon horizons, bounded above and below by high carbonate sediments. The organic coatings on the sands were examined using white light and fluorescence microscopy and by scanning electron microscopy. Core samples were analyzed for organic and inorganic carbon, solution pH, humic/fulvic acid ratios, and insoluable organic matter content (that is, humin)more » as function of depth from the ground surface. The organic geochemistry of the soil profile at this site was found to be significantly influenced by the carbonates producing a sharp boundary of precipitated organic matter. This boundary was followed by coatings of predominantly fulvic acid salts on mineral grains deeper in the soil column. The coatings extended into the aquifer. The existence of native organic films on sand grains is well documented in the soils literature. The study reported here was greatly aided by this information and provides the framework for future studies concerning the influence of carbon distribution, chemical identity, and morphology on contaminant fate and transport processes. 56 refs., 9 figs., 2 tabs.« less

Extracellular enzyme kinetics scale with resource availability

EPA Science Inventory

Microbial community metabolism relies on external digestion, mediated by extracellular enzymes that break down complex organic matter into molecules small enough for cells to assimilate. We analyzed the kinetics of 40 extracellular enzymes that mediate the degradation and assimi...

The Role of Ultrahigh Resolution Fourier Transform Mass Spectrometry (FT-MS) in Astrobiology-Related Research: Analysis of Meteorites and Tholins.

PubMed

Somogyi, Árpád; Thissen, Roland; Orthous-Daunay, Francois-Régis; Vuitton, Véronique

2016-03-24

It is an important but also a challenging analytical problem to understand the chemical composition and structure of prebiotic organic matter that is present in extraterrestrial materials. Its formation, evolution and content in the building blocks ("seeds") for more complex molecules, such as proteins and DNA, are key questions in the field of exobiology. Ultrahigh resolution mass spectrometry is one of the best analytical techniques that can be applied because it provides reliable information on the chemical composition and structure of individual components of complex organic mixtures. Prebiotic organic material is delivered to Earth by meteorites or generated in laboratories in simulation (model) experiments that mimic space or atmospheric conditions. Recent representative examples for ultrahigh resolution mass spectrometry studies using Fourier-transform (FT) mass spectrometers such as Orbitrap and ion cyclotron resonance (ICR) mass spectrometers are shown and discussed in the present article, including: (i) the analysis of organic matter of meteorites; (ii) modeling atmospheric processes in ICR cells; and (iii) the structural analysis of laboratory made tholins that might be present in the atmosphere and surface of Saturn's largest moon, Titan.

The Role of Ultrahigh Resolution Fourier Transform Mass Spectrometry (FT-MS) in Astrobiology-Related Research: Analysis of Meteorites and Tholins

PubMed Central

Somogyi, Árpád; Thissen, Roland; Orthous-Daunay, Francois-Régis; Vuitton, Véronique

2016-01-01

It is an important but also a challenging analytical problem to understand the chemical composition and structure of prebiotic organic matter that is present in extraterrestrial materials. Its formation, evolution and content in the building blocks (“seeds”) for more complex molecules, such as proteins and DNA, are key questions in the field of exobiology. Ultrahigh resolution mass spectrometry is one of the best analytical techniques that can be applied because it provides reliable information on the chemical composition and structure of individual components of complex organic mixtures. Prebiotic organic material is delivered to Earth by meteorites or generated in laboratories in simulation (model) experiments that mimic space or atmospheric conditions. Recent representative examples for ultrahigh resolution mass spectrometry studies using Fourier-transform (FT) mass spectrometers such as Orbitrap and ion cyclotron resonance (ICR) mass spectrometers are shown and discussed in the present article, including: (i) the analysis of organic matter of meteorites; (ii) modeling atmospheric processes in ICR cells; and (iii) the structural analysis of laboratory made tholins that might be present in the atmosphere and surface of Saturn’s largest moon, Titan. PMID:27023520

Uranium and organic matters: use of pyrolysis-gas chromatography, carbon, hydrogen, and uranium contents to characterize the organic matter from sandstone-type deposits

USGS Publications Warehouse

Leventhal, Joel S.

1979-01-01

Organic matter seems to play an important role in the genesis of uranium deposits in sandstones in the western United States. Organic materials associated with ore from the Texas coastal plain, Tertiary basins of Wyoming, Grants mineral belt of New Mexico, and the Uravan mineral belt of Utah and Colorado vary widely in physical appearance and chemical composition. Partial characterization of organic materials is achieved by chemical analyses to determine atomic hydrogen-to-carbon (H/C) ratios and by gas chromatographic analyses to determine the molecular fragments evolved during stepwise pyrolysis. From the pyrolysis experiments the organic materials can be classified and grouped: (a) lignites from Texas and Wyoming and (b) hydrogen poor materials, from Grants and Uravan mineral belts and Wyoming; (c) naphthalene-containing materials from Grants mineral belt and Wyoming; and (d) complex and aromatic materials from Uravan, Grants and Wyoming. The organic materials analyzed have atomic H/C ratios that range from approximately 0.3 to at least 1.5. The samples with higher H/C ratios yield pyrolysis products that contain as many as 30 carbon atoms per molecule. Samples with low H/C ratios are commonly more uraniferous and yield mostly methane and low-molecular-weight gases during pyrolysis.

A divergent heritage for complex organics in Isheyevo lithic clasts

NASA Astrophysics Data System (ADS)

van Kooten, Elishevah M. M. E.; Nagashima, Kazuhide; Kasama, Takeshi; Wampfler, Susanne F.; Ramsey, Jon P.; Frimann, Søren; Balogh, Zoltan I.; Schiller, Martin; Wielandt, Daniel P.; Franchi, Ian A.; Jørgensen, Jes K.; Krot, Alexander N.; Bizzarro, Martin

2017-05-01

Primitive meteorites are samples of asteroidal bodies that contain a high proportion of chemically complex organic matter (COM) including prebiotic molecules such as amino acids, which are thought to have been delivered to Earth via impacts during the early history of the Solar System. Thus, understanding the origin of COM, including their formation pathway(s) and environment(s), is critical to elucidate the origin of life on Earth as well as assessing the potential habitability of exoplanetary systems. The Isheyevo CH/CBb carbonaceous chondrite contains chondritic lithic clasts with variable enrichments in 15N believed to be of outer Solar System origin. Using transmission electron microscopy (TEM-EELS) and in situ isotope analyses (SIMS and NanoSIMS), we report on the structure of the organic matter as well as the bulk H and N isotope composition of Isheyevo lithic clasts. These data are complemented by electron microprobe analyses of the clast mineral chemistry and bulk Mg and Cr isotopes obtained by inductively coupled plasma and thermal ionization mass spectrometry, respectively (MC-ICPMS and TIMS). Weakly hydrated (A) clasts largely consist of Mg-rich anhydrous silicates with local hydrated veins composed of phyllosilicates, magnetite and globular and diffuse organic matter. Extensively hydrated clasts (H) are thoroughly hydrated and contain Fe-sulfides, sometimes clustered with organic matter, as well as magnetite and carbonates embedded in a phyllosilicate matrix. The A-clasts are characterized by a more 15N-rich bulk nitrogen isotope composition (δ15N = 200-650‰) relative to H-clasts (δ15N = 50-180‰) and contain extremely 15N-rich domains with δ15N < 5000‰. The D/H ratios of the clasts are correlated with the degree of clast hydration and define two distinct populations, which we interpret as reflecting mixing between D-poor fluid(s) and distinct organic endmember components that are variably D-rich. High-resolution N isotope data of 15N-rich domains show that the lithic clast diffuse organic matter is typically more 15N-rich than globular organic matter. The correlated δ15N values and C/N ratios of nanoglobules require the existence of multiple organic components, in agreement with the H isotope data. The combined H and N isotope data suggest that the organic precursors of the lithic clasts are defined by an extremely 15N-poor (similar to solar) and D-rich component for H-clasts, and a moderately 15N-rich and D-rich component for A-clasts. In contrast, the composition of the putative fluids is inferred to include D-poor but moderately to extremely 15N-rich H- and N-bearing components. The variable 15N enrichments in H- and A-clasts are associated with structural differences in the N bonding environments of their diffuse organic matter, which are dominated by amine groups in H-clasts and nitrile functional groups in A-clasts. We suggest that the isotopically divergent organic precursors in Isheyevo clasts may be similar to organic moieties in carbonaceous chondrites (CI, CM, CR) and thermally recalcitrant organic compounds in ordinary chondrites, respectively. The altering fluids, which are inferred to cause the 15N enrichments observed in the clasts, may be the result of accretion of variable abundances of NH3 and HCN ices. Finally, using bulk Mg and Cr isotope composition of clasts, we speculate on the accretion regions of the various primitive chondrites and components and the origin of the Solar System's N and H isotope variability.

The Combined Role Of Manganese Oxides And Microbes In The yAbiotic Uptake Of Amino Acid Nitrogen Into Litter And Soil Organic yMatter

NASA Astrophysics Data System (ADS)

Filley, T. R.; Dria, K.

2004-12-01

Soil organic matter (SOM) is the largest terrestrial C and N store. Microbial yand abiotic processes that control the transformation of protein nitrogen in litter and ysoils into macromolecular humic materials play an important role in organic matter ystorage and soil productivity. There are major gaps, however, in our understanding of ythese processes and behaviors. Abiotic reactions of amines, phenols and sugars derived yfrom forest leachates or present in detrital and litter organic matter are known to be ykey processes in the formation of complex organic nitrogen. We present here the yresults from a study designed to investigate how the inherent chemistry of lignin, leaf ylitter, and progressively advanced brown-rot wood decay impact the chemical reaction yof amino acids with this organic matter. Additionally, experiments in the presence of ybirnessite (MnO2) were also conducted to investigate the role of mineral induced phenol yoxidation on specific amino acid chemical humifcation processes. Solid and liquid state yNMR, 13C-labelled tetramethyl ammonium hydroxide thermochemolysis and stable ycarbon and nitrogen isotope ratio mass spectrometry were used to track the alteration yof litter material and document uptake of 13C and 15N labeled amino acids. yPreliminary results from birnessite-containing experiments suggest that the metal-ypromoted oxidation of the lignin, leaf litter, and, in particular, demethylated brown rot ywood residues, is necessary to convert the phenols to quinones of some type permitting yamine addition. This relationship is particularly true for the production of soluble yfractions after two and six weeks of reaction in the presence of the manganese oxides. yAdditionally, the production of leachable organic matter with incorporated N was ypromoted in the soluble fractions. Ongoing NMR studies will elucidate the nature of ythe chemical binding in these experiments. y

Depositional environment and organic matter accumulation of Upper Ordovician–Lower Silurian marine shale in the Upper Yangtze Platform, South China

USGS Publications Warehouse

Li, Yangfang; Zhang, Tongwei; Ellis, Geoffrey S.; Shao, Deyong

2017-01-01

The main controlling factors of organic matter accumulation in the Upper Ordovician Wufeng–Lower Silurian Longmaxi Formations are complex and remain highly controversial. This study investigates the vertical variation of total organic carbon (TOC) content as well as major and trace element concentrations of four Ordovician–Silurian transition sections from the Upper Yangtze Platform of South China to reconstruct the paleoenvironment of these deposits and to improve our understanding of those factors that have influenced organic matter accumulation in these deposits.The residual TOC content of the Wufeng Formation averages 3.2% and ranges from 0.12 to 6.0%. The overlying lower Longmaxi Formation displays higher TOC content (avg. 4.4%), followed upsection by consistent and lower values that average 1.6% in the upper Longmaxi Formation. The concentration and covariation of redox-sensitive trace elements (Mo, U and V) suggest that organic-rich intervals of the Wufeng Formation accumulated under predominantly anoxic conditions. Organic-rich horizons of the lower Longmaxi Formation were deposited under strongly anoxic to euxinic conditions, whereas organic-poor intervals of the upper Longmaxi Formation accumulated under suboxic conditions. Positive correlations between redox proxies and TOC contents suggest that organic matter accumulation was predominantly controlled by preservation. Barium excess (Baxs) values indicate high paleoproductivity throughout the entire depositional sequence, with an increase in the lower Longmaxi Formation. Increased productivity may have been induced by enhanced P recycling, as evidenced by elevated Corg/Ptot ratios. Mo–U covariation and Mo/TOC values reveal that the Wufeng Formation was deposited under extremely restricted conditions, whereas the Longmaxi Formation accumulated under moderately restricted conditions. During the Late Ordovician, the extremely restricted nature of ocean circulation on the Upper Yangtze Platform in tandem with enhanced stratification of the water column promoted anoxic conditions favorable for the preservation of organic matter. During Early Silurian time, organic matter accumulation was principally controlled by changes in sea level, which affected terrigenous flux, redox conditions, and the degree of nutrition recycling.

Dissolved effluent organic matter: Characteristics and potential implications in wastewater treatment and reuse applications.

PubMed

Michael-Kordatou, I; Michael, C; Duan, X; He, X; Dionysiou, D D; Mills, M A; Fatta-Kassinos, D

2015-06-15

Wastewater reuse is currently considered globally as the most critical element of sustainable water management. The dissolved effluent organic matter (dEfOM) present in biologically treated urban wastewater, consists of a heterogeneous mixture of refractory organic compounds with diverse structures and varying origin, including dissolved natural organic matter, soluble microbial products, endocrine disrupting compounds, pharmaceuticals and personal care products residues, disinfection by-products, metabolites/transformation products and others, which can reach the aquatic environment through discharge and reuse applications. dEfOM constitutes the major fraction of the effluent organic matter (EfOM) and due to its chemical complexity, it is necessary to utilize a battery of complementary techniques to adequately describe its structural and functional character. dEfOM has been shown to exhibit contrasting effects towards various aquatic organisms. It decreases metal uptake, thus potentially reducing their bioavailability to exposed organisms. On the other hand, dEfOM can be adsorbed on cell membranes inducing toxic effects. This review paper evaluates the performance of various advanced treatment processes (i.e., membrane filtration and separation processes, activated carbon adsorption, ion-exchange resin process, and advanced chemical oxidation processes) in removing dEfOM from wastewater effluents. In general, the literature findings reveal that dEfOM removal by advanced treatment processes depends on the type and the amount of organic compounds present in the aqueous matrix, as well as the operational parameters and the removal mechanisms taking place during the application of each treatment technology. Copyright © 2015 Elsevier Ltd. All rights reserved.

Using Coupled Models to Study the Effects of River Discharge on Biogeochemical Cycling and Hypoxia in the Northern Gulf of Mexico

NASA Technical Reports Server (NTRS)

Penta, Bradley; Ko, D.; Gould, Richard W.; Arnone, Robert A.; Greene, R.; Lehrter, J.; Hagy, James; Schaeffer, B.; Murrell, M.; Kurtz, J.;

Soil organic matter in podzol horizons of the Amazon region: Humification, recalcitrance, and dating.

PubMed

Tadini, Amanda M; Nicolodelli, Gustavo; Senesi, Giorgio S; Ishida, Débora A; Montes, Célia R; Lucas, Yves; Mounier, Stéphane; Guimarães, Francisco E G; Milori, Débora M B P

2018-02-01

Characteristics of soil organic matter (SOM) are important, especially in the Amazon region, which represents one of the world's most relevant carbon reservoirs. In this work, the concentrations of carbon and differences in its composition (humification indexes) were evaluated and compared for several horizons (0 to 390cm) of three typical Amazonian podzol profiles. Fluorescence spectroscopy was used to investigate the humic acid (HA) fractions of SOM isolated from the different samples. Simple and labile carbon structures appeared to be accumulated in surface horizons, while more complex humified compounds were leached and accumulated in intermediate and deeper Bh horizons. The results suggested that the humic acids originated from lignin and its derivatives, and that lignin could accumulate in some Bh horizons. The HA present in deeper Bh horizons appeared to originate from different formation pathways, since these horizons showed different compositions. There were significant compositional changes of HA with depth, with four types of organic matter: recalcitrant, humified, and old dating; labile and young dating; humified and young dating; and little humified and old dating. Therefore, the humification process had no direct relation with the age of the organic matter in the Amazonian podzols. Copyright © 2017 Elsevier B.V. All rights reserved.

Dissipative solitons with energy and matter flows: Fundamental building blocks for the world of living organisms

NASA Astrophysics Data System (ADS)

Akhmediev, N.; Soto-Crespo, J. M.; Brand, H. R.

2013-05-01

We consider a combined model of dissipative solitons that are generated due to the balance between gain and loss of energy as well as to the balance between input and output of matter. The system is governed by the generic complex Ginzburg-Landau equation, which is coupled to a common reaction-diffusion (RD) system. Such a composite dynamical system may describe nerve pulses with a significant part of electromagnetic energy involved. We present examples of such composite dissipative solitons and analyse their internal balances between energy and matter generation and dissipation.

PEaCH4 v.2.0: A modelling platform to predict early diagenetic processes in marine sediments with a focus on biogenic methane - Case study: Offshore Namibia

NASA Astrophysics Data System (ADS)

Arning, Esther T.; Häußler, Steffen; van Berk, Wolfgang; Schulz, Hans-Martin

2016-07-01

The modelling of early diagenetic processes in marine sediments is of interest in marine science, and in the oil and gas industry, here, especially with respect to methane occurrence and gas hydrate formation as resources. Early diagenesis in marine sediments evolves from a complex web of intertwining (bio)geochemical reactions. It comprises microbially catalysed reactions and inorganic mineral-water-gas interactions. A model that will describe and consider all of these reactions has to be complex. However, it should be user-friendly, as well as to be applicable for a broad community and not only for experts in the field of marine chemistry. The presented modelling platform PeaCH4 v.2.0 combines both aspects, and is Microsoft Excel©-based. The modelling tool is PHREEQC (version 2), a computer programme for speciation, batch-reaction, one-dimensional transport, and inverse geochemical calculations. The conceptual PEaCH4 model is based on the conversion of sediment-bound degradable organic matter. PEaCH4 v.2.0 was developed to quantify and predict early diagenetic processes in marine sediments with the focus on biogenic methane formation and its phase behaviour, and allows carbon mass balancing. In regard to the irreversible degradation of organic matter, it comprises a "reaction model" and a "kinetic model" to predict methane formation. Both approaches differ in their calculations and outputs as the "kinetic model" considers the modelling time to integrate temperature dependent biogenic methane formation in its calculations, whereas the "reaction model" simply relies on default organic matter degradation. With regard to the inorganic mineral-water-gas interactions, which are triggered by irreversible degradation of organic matter, PEaCH4 v.2.0 is based on chemical equilibrium thermodynamics, appropriate mass-action laws, and their temperature dependent equilibrium constants. The programme is exemplarily presented with the example of upwelling sediments off Namibia, ODP Leg 175, Site 1082. The application demonstrates that the modelling platform PEaCH4 v.2.0 provides a user-friendly, but complex scientific tool that delivers retraceable information about early diagenetic processes and products in marine sediments.

Light Regimes Shape Utilization of Extracellular Organic C and N in a Cyanobacterial Biofilm

PubMed Central

Stuart, Rhona K.; Mayali, Xavier; Boaro, Amy A.; Zemla, Adam; Everroad, R. Craig; Nilson, Daniel; Weber, Peter K.; Lipton, Mary; Bebout, Brad M.; Pett-Ridge, Jennifer

2016-01-01

ABSTRACT Although it is becoming clear that many microbial primary producers can also play a role as organic consumers, we know very little about the metabolic regulation of photoautotroph organic matter consumption. Cyanobacteria in phototrophic biofilms can reuse extracellular organic carbon, but the metabolic drivers of extracellular processes are surprisingly complex. We investigated the metabolic foundations of organic matter reuse by comparing exoproteome composition and incorporation of 13C-labeled and 15N-labeled cyanobacterial extracellular organic matter (EOM) in a unicyanobacterial biofilm incubated using different light regimes. In the light and the dark, cyanobacterial direct organic C assimilation accounted for 32% and 43%, respectively, of all organic C assimilation in the community. Under photosynthesis conditions, we measured increased excretion of extracellular polymeric substances (EPS) and proteins involved in micronutrient transport, suggesting that requirements for micronutrients may drive EOM assimilation during daylight hours. This interpretation was supported by photosynthesis inhibition experiments, in which cyanobacteria incorporated N-rich EOM-derived material. In contrast, under dark, C-starved conditions, cyanobacteria incorporated C-rich EOM-derived organic matter, decreased excretion of EPS, and showed an increased abundance of degradative exoproteins, demonstrating the use of the extracellular domain for C storage. Sequence-structure modeling of one of these exoproteins predicted a specific hydrolytic activity that was subsequently detected, confirming increased EOM degradation in the dark. Associated heterotrophic bacteria increased in abundance and upregulated transport proteins under dark relative to light conditions. Taken together, our results indicate that biofilm cyanobacteria are successful competitors for organic C and N and that cyanobacterial nutrient and energy requirements control the use of EOM. PMID:27353754

Light Regimes Shape Utilization of Extracellular Organic C and N in a Cyanobacterial Biofilm

DOE PAGES

Stuart, Rhona K.; Mayali, Xavier; Boaro, Amy A.; ...

2016-06-28

Here it is becoming clear that many microbial primary producers can also play a role as organic consumers, we know very little about the metabolic regulation of photoautotroph organic matter consumption. Cyanobacteria in phototrophic biofilms can reuse extracellular organic carbon, but the metabolic drivers of extracellular processes are surprisingly complex. We investigated the metabolic foundations of organic matter reuse by comparing exoproteome composition and incorporation of 13C-labeled and 15N-labeled cyanobacterial extracellular organic matter (EOM) in a unicyanobacterial biofilm incubated using different light regimes. In the light and the dark, cyanobacterial direct organic C assimilation accounted for 32% and 43%, respectively,more » of all organic C assimilation in the community. Under photosynthesis conditions, we measured increased excretion of extracellular polymeric substances (EPS) and proteins involved in micronutrient transport, suggesting that requirements for micronutrients may drive EOM assimilation during daylight hours. This interpretation was supported by photosynthesis inhibition experiments, in which cyanobacteria incorporated N-rich EOM-derived material. In contrast, under dark, C-starved conditions, cyanobacteria incorporated C-rich EOM-derived organic matter, decreased excretion of EPS, and showed an increased abundance of degradative exoproteins, demonstrating the use of the extracellular domain for C storage. Sequence-structure modeling of one of these exoproteins predicted a specific hydrolytic activity that was subsequently detected, confirming increased EOM degradation in the dark. Associated heterotrophic bacteria increased in abundance and upregulated transport proteins under dark relative to light conditions. Taken together, our results indicate that biofilm cyanobacteria are successful competitors for organic C and N and that cyanobacterial nutrient and energy requirements control the use of EOM.« less

Dissociation kinetics of Fe(III)- and Al(III)-natural organic matter complexes at pH 6.0 and 8.0 and 25 °C

NASA Astrophysics Data System (ADS)

Jones, Adele M.; Pham, A. Ninh; Collins, Richard N.; Waite, T. David

2009-05-01

The rate at which iron- and aluminium-natural organic matter (NOM) complexes dissociate plays a critical role in the transport of these elements given the readiness with which they hydrolyse and precipitate. Despite this, there have only been a few reliable studies on the dissociation kinetics of these complexes suggesting half-times of some hours for the dissociation of Fe(III) and Al(III) from a strongly binding component of NOM. First-order dissociation rate constants are re-evaluated here at pH 6.0 and 8.0 and 25 °C using both cation exchange resin and competing ligand methods for Fe(III) and a cation exchange resin method only for Al(III) complexes. Both methods provide similar results at a particular pH with a two-ligand model accounting satisfactorily for the dissociation kinetics results obtained. For Fe(III), half-times on the order of 6-7 h were obtained for dissociation of the strong component and 4-5 min for dissociation of the weak component. For aluminium, the half-times were on the order of 1.5 h and 1-2 min for the strong and weak components, respectively. Overall, Fe(III) complexes with NOM are more stable than analogous complexes with Al(III), implying Fe(III) may be transported further from its source upon dilution and dispersion.

Organic compounds in circumstellar and interstellar environments.

PubMed

Kwok, Sun

2015-06-01

Recent research has discovered that complex organic matter is prevalent throughout the Universe. In the Solar System, it is found in meteorites, comets, interplanetary dust particles, and planetary satellites. Spectroscopic signatures of organics with aromatic/aliphatic structures are also found in stellar ejecta, diffuse interstellar medium, and external galaxies. From space infrared spectroscopic observations, we have found that complex organics can be synthesized in the late stages of stellar evolution. Shortly after the nuclear synthesis of the element carbon, organic gas-phase molecules are formed in the stellar winds, which later condense into solid organic particles. This organic synthesis occurs over very short time scales of about a thousand years. In order to determine the chemical structures of these stellar organics, comparisons are made with particles produced in the laboratory. Using the technique of chemical vapor deposition, artificial organic particles have been created by injecting energy into gas-phase hydrocarbon molecules. These comparisons led us to believe that the stellar organics are best described as amorphous carbonaceous nanoparticles with mixed aromatic and aliphatic components. The chemical structures of the stellar organics show strong similarity to the insoluble organic matter found in meteorites. Isotopic analysis of meteorites and interplanetary dust collected in the upper atmospheres have revealed the presence of pre-solar grains similar to those formed in old stars. This provides a direct link between star dust and the Solar System and raises the possibility that the early Solar System was chemically enriched by stellar ejecta with the potential of influencing the origin of life on Earth.

COP-compost: a software to study the degradation of organic pollutants in composts.

PubMed

Zhang, Y; Lashermes, G; Houot, S; Zhu, Y-G; Barriuso, E; Garnier, P

2014-02-01

Composting has been demonstrated to be effective in degrading organic pollutants (OP) whose behaviour depends on the composting conditions, the microbial populations activated and interactions with organic matters. The fate of OP during composting involves complex mechanisms and models can be helpful tools for educational and scientific purposes, as well as for industrialists who want to optimise the composting process for OP elimination. A COP-Compost model, which couples an organic carbon (OC) module and an organic pollutant (OP) module and which simulates the changes of organic matter, organic pollutants and the microbial activities during the composting process, has been proposed and calibrated for a first set of OP in a previous study. The objectives of the present work were (1) to introduce the COP-Compost model from its convenient interface to a potential panel of users, (2) to show the variety of OP that could be simulated, including the possibility of choosing between degradation through co-metabolism or specific metabolism and (3) to show the effect of the initial characteristics of organic matter quality and its microbial biomass on the simulated results of the OP dynamic. In the model, we assumed that the pollutants can be adsorbed on organic matter according to the biochemical quality of the OC and that the microorganisms can degrade the pollutants at the same time as they degrade OC (by co-metabolism). A composting experiment describing two different (14)C-labelled organic pollutants, simazine and pyrene, were chosen from the literature because the four OP fractions simulated in the model were measured during the study (the mineralised, soluble, sorbed and non-extractable fractions). Except for the mineralised fraction of simazine, a good agreement was achieved between the simulated and experimental results describing the evolution of the different organic fractions. For simazine, a specific biomass had to be added. To assess the relative importance of organic matter dynamics on the organic pollutants' behaviour, a sensitivity analysis was conducted. The sensitivity analysis demonstrated that the parameters associated with organic matter dynamics and its initial microbial biomass greatly influenced the evolution of all the OP fractions, although the initial biochemical quality of the OC did not have a significant impact on the OP evolution.

Transport, speciation, toxicity, and treatability of highway stormwater discharged to receiving waters in Louisiana.

DOT National Transportation Integrated Search

2013-01-01

Stormwater from transportation land uses is a complex heterogeneous mixture of particulate matter, nutrients (phosphorus and nitrogen), heavy metals, inorganic, and organic compounds with variations in flow and mass loadings by orders of magnitude du...

ASSAYING PARTICLE-BOUND POLYCYCLIC AROMATIC HYDROCARBONS (PAH) FROM ARCHIVED PM2.5 FILTERS

EPA Science Inventory

Airborne particulate matter contains numerous organic species, including several polycyclic aromatic hydrocarbons (PAHs) that are known or suspected carcinogens. Existing methods for measuring airborne PAHs are complex and costly, primarily because they are designed to collect...

THE TOXICOLOGY OF COMPLEX MIXTURES OF DISINFECTION BY-PRODUCTS

EPA Science Inventory

Chemical disinfection of water is a major public health advance that has decreased dramatically water-borne disease. Chemical disinfectants react with naturally occurring organic and inorganic matter in water to produce a wide variety of disinfection byproducts (DBPs). DBP num...

Properties and reactivity of Fe-organic matter associations formed by coprecipitation versus adsorption: Clues from arsenate batch adsorption

NASA Astrophysics Data System (ADS)

Mikutta, Robert; Lorenz, Dennis; Guggenberger, Georg; Haumaier, Ludwig; Freund, Anja

2014-11-01

Ferric oxyhydroxides play an important role in controlling the bioavailability of oxyanions such as arsenate and phosphate in soil. Despite this, little is known about the properties and reactivity of Fe(III)-organic matter phases derived from adsorption (reaction of organic matter (OM) to post-synthesis Fe oxide) versus coprecipitation (formation of Fe oxides in presence of OM). Coprecipitates and adsorption complexes were synthesized at pH 4 using two natural organic matter (NOM) types extracted from forest floor layers (Oi and Oa horizon) of a Haplic Podzol. Iron(III) coprecipitates were formed at initial molar metal-to-carbon (M/C) ratios of 1.0 and 0.1 and an aluminum (Al)-to-Fe(III) ratio of 0.2. Sample properties were studied by X-ray diffraction, X-ray photoelectron spectroscopy (XPS), N2 gas adsorption, dynamic light scattering, and electrophoretic mobility measurements. Arsenic [As(V)] adsorption to Fe-OM phases was studied in batch experiments (168 h, pH 4, 100 μM As). The organic carbon (OC) contents of the coprecipitates (82-339 mg g-1) were higher than those of adsorption complexes (31 and 36 mg g-1), leading to pronounced variations in specific surface area (9-300 m2 g-1), average pore radii (1-9 nm), and total pore volumes (11-374 mm3 g-1) but being independent of the NOM type or the presence of Al. The occlusion of Fe solids by OM (XPS surface concentrations: 60-82 atom% C) caused comparable pHPZC (1.5-2) of adsorption complexes and coprecipitates. The synthesis conditions resulted in different Fe-OM association modes: Fe oxide particles in 'M/C 0.1' coprecipitates covered to a larger extent the outermost aggregate surfaces, for some 'M/C 1.0' coprecipitates OM effectively enveloped the Fe oxides, while OM in the adsorption complexes primarily covered the outer aggregate surfaces. Despite of their larger OC contents, adsorption of As(V) was fastest to coprecipitates formed at low Fe availability (M/C 0.1) and facilitated by desorption of weakly bonded OC and disaggregation. In contrast, 'M/C 1.0' coprecipitates showed a comparable rate of As uptake as the adsorption complexes. While small mesopores (2-10 nm) promoted the fast As uptake particularly to 'M/C 0.1' coprecipitates, the presence of micropores (<2 nm) appeared to impair As desorption. This study shows that the environmental reactivity of poorly crystalline Fe(III) oxides in terrestrial and aquatic systems can largely vary depending on the formation conditions. Carbon-rich Fe phases precipitated at low M/C ratios may play a more important role in oxyanion immobilization and Fe and C cycling than phases formed at higher M/C ratios or respective adsorption complexes.

Interactions of specific extracellular organic matter and polyaluminum chloride and their roles in the algae-polluted water treatment.

PubMed

Tang, Xiaomin; Zheng, Huaili; Gao, Baoyu; Zhao, Chuanliang; Liu, Bingzhi; Chen, Wei; Guo, Jinsong

2017-06-15

Extracellular organic matter (EOM) is ubiquitous in the algae-polluted water and has a significant impact on the human health and drinking water treatment. We investigate the different characteristics of dissolved extracellular organic matter (dEOM) and bound extracellular organic matter (bEOM) recovered from the various growth period of Microcystis aeruginosa and the interactions of them and polyaluminum chloride (PACl). The roles of the different EOM in the algae-polluted water treatment are also discussed. The functional groups of aromatic, OH, NH, CN and NO in bEOM possessing the stronger interaction with hydroxyl aluminum compared with dEOM is responsible for bEOM and algae removal. Some low molecular weight (MW) organic components and protein-like substances in bEOM are most easily removed. And dEOM weakly reacts with PACl or inhibits coagulation, especially dEOM with the high MW organic components. The main coagulation mechanisms of bEOM are the generation of insoluble Al-bEOM through complexation, the bridge of AlO 4 Al 12 (OH) 24 (H 2 O) 12 7+ (Al 13 ), the adsorption of Al(OH) 3(am) and the entrapment of flocs. The adsorption of Al 13 and Al(OH) 3(am) mainly contribute to dEOM removal. It is also recommended to treat the algae with dEOM and bEOM at the initial stage. Copyright © 2017 Elsevier B.V. All rights reserved.

Enzymatic Regulation of Organic Matter Metabolism in Siberia's Kolyma River Watershed

NASA Astrophysics Data System (ADS)

Mann, P. J.; Sobczak, W. V.; Vonk, J. E.; Davydova, A.; Schade, J. D.; Bulygina, E. B.; Davydov, S.; Zimov, N.; Holmes, R. M.

2011-12-01

Arctic soils contain vast amounts of ancient organic carbon locked up in permafrost. This organic matter can be unlocked via permafrost thaw and bacterial processing. Microbial communities release enzymes into the environment (ectoenzymes) as a means of degrading organic matter and to acquire carbon, nitrogen and phosphorus for assimilation. Limited ectoenzyme production, or unfavourable in-situ conditions (e.g. temperature, oxygen) can limit degradation of permafrost on land. Environmental conditions may become more favourable for bacterial degradation as carbon compounds are released from permafrost into Arctic streams and rivers. We measured the potential activities of a suite of ectoenzymes within surface waters collected from a range of streams and rivers throughout the Kolyma River basin, Siberia. Ectoenzyme activities were additionally measured in Kolyma river waters collected at three distinct periods of the hydrograph (under-ice, freshet and summer conditions). In total, seven enzymes were studied allowing bacterial requirements for a wide range of compounds including lignin, carbohydrates, proteins and cellulose to be assessed. To investigate the lability of the carbon pool within these waters, we measured the biological oxygen demand over 5 days (BOD). Significant correlations were observed between phenol oxidase activity and BOD across all of the study sites, suggesting the rate of phenolic degradation may be a controlling factor in organic carbon metabolism. The activity rate in ectoenzymes that catalyze phosphate, lignin and carbon substrates varied significantly within the Kolyma river over the hydrograph, indicating that seasonal changes in organic matter composition may also shift the limiting resource for bacterial degradation. High activity rates in ectoenzymes that catalyze lignin, chitin, cellulose and proteins were measured in waters draining permafrost ice complexes. These results suggest that organic carbon is continually processed throughout the stream network, and that its ultimate fate is linked to organic matter composition. We demonstrate that organic carbon derived from ancient permafrost thaw may be highly labile to bacterial communities within Arctic aquatic ecosystems.

Seasonal and spatial variability of the organic matter-to-organic carbon mass ratios in Chinese urban organic aerosols and a first report of high correlations between aerosol oxalic acid and zinc

NASA Astrophysics Data System (ADS)

Xing, L.; Fu, T.-M.; Cao, J. J.; Lee, S. C.; Wang, G. H.; Ho, K. F.; Cheng, M.-C.; You, C.-F.; Wang, T. J.

2013-01-01

We calculated the organic matter to organic carbon mass ratios (OM/OC mass ratios) in PM2.5 collected from 14 Chinese cities during summer and winter of 2003 and analyzed the causes for their seasonal and spatial variability. The OM/OC mass ratios were calculated two ways. Using a mass balance method, the calculated OM/OC mass ratios averaged 1.92 ± 0.39 yr-round, with no significant seasonal or spatial variation. The second calculation was based on chemical species analyses of the organic compounds extracted from the PM2.5 samples using dichloromethane/methanol and water. The calculated OM/OC mass ratio in summer was relatively high (1.75 ± 0.13) and spatially-invariant, due to vigorous photochemistry and secondary OA production throughout the country. The calculated OM/OC mass ratio in winter (1.59 ± 0.18) was significantly lower than that in summer, with lower values in northern cities (1.51 ± 0.07) than in southern cities (1.65 ± 0.15). This likely reflects the wider usage of coal for heating purposes in northern China in winter, in contrast to the larger contributions from biofuel and biomass burning in southern China in winter. On average, organic matters constituted 36% and 34% of Chinese urban PM2.5 mass in summer and winter, respectively. We reported, for the first time, high correlations between Zn and oxalic acid in Chinese urban aerosols in summer. This is consistent with the formation of stable Zn oxalate complex in the aerosol phase previously proposed by Furukawa and Takahashi (2011). We found that many other dicarboxylic acids were also highly correlated with Zn in the summer Chinese urban aerosol samples, suggesting that they may also form stable organic complexes with Zn. Such formation may have profound implications for the atmospheric abundance and hygroscopic property of aerosol dicarboxylic acids.

Application of Bayesian belief net in modelling the origin and effects of terrigenous dissolved organic matter in a boreal aquatic ecosystem

NASA Astrophysics Data System (ADS)

Rahikainen, Mika; Hoikkala, Laura; Soinne, Helena

2013-04-01

Bayesian belief nets (BBN) are capable of developing holistic understanding of the origin, transportation, and effects of dissolved organic matter (DOM) in ecosystems. The role of riverine DOM, transporting carbon and macronutrients N and P into lakes and coastal areas, has been largely neglected in research about processes influencing aquatic ecosystem functions although dissolved organic matter provides a significant nutrient source for primary producers in aquatic environments. This neglect has also contributed to the environmental policies which are focused in the control of inorganic N and P load. It is of great social and economic interest to gain improved knowledge of whether the currently applied policy instruments act in synchrony in mitigating eutrophication caused by N and P versus DOM load. DOM is a complex mixture of compounds that are poorly characterized. DOM export is strongly regulated by land use (urban, forest, agricultural land, peat land), in addition to soil type and soil organic carbon concentration. Furthermore, the composition of DOM varies according to its origin. The fate and effects of DOM loads in the fresh water and coastal environments depend, for example, on their biodegradability. Degradation kinetics again depends on the interactions between composition of the DOM pool and the receiving environment. Impact studies of dissolved organic matter pose a complicated environmental impact assessment challenge for science. There exists strategic uncertainty in the science about the causal dependencies and about the quality of knowledge related to DOM. There is a clear need for systematization in the approach as uncertainty is typically high about many key processes. A cross-sectorial, integrative analysis will aid in focusing on the most relevant issues. A holistic and unambiguous analysis will provide support for policy-decisions and management by indicating which outcome is more probable than another. The task requires coupling complex models of different environmental compartments (soil chemistry, agricultural management practices, aquatic processes, costs and benefits for society) with explicit treatment of uncertainty. In order to achieve policy relevance, these models have to be integrated into resource management. We use a Bayesian belief net to describe the probabilistic dependencies among the driving forces, processes, and impacts relevant to dissolved organic matter in boreal waterways.

Use of an exchange method to estimate the association and dissociation rate constants of cadmium complexes formed with low-molecular-weight organic acids commonly exuded by plant roots.

PubMed

Schneider, André; Nguyen, Christophe

2011-01-01

Organic acids released from plant roots can form complexes with cadmium (Cd) in the soil solution and influence metal bioavailability not only due to the nature and concentration of the complexes but also due to their lability. The lability of a complex influences its ability to buffer changes in the concentration of free ions (Cd); it depends on the association (, m mol s) and dissociation (, s) rate constants. A resin exchange method was used to estimate and (m mol s), which is the conditional estimate of depending on the calcium (Ca) concentration in solution. The constants were estimated for oxalate, citrate, and malate, three low-molecular-weight organic acids commonly exuded by plant roots and expected to strongly influence Cd uptake by plants. For all three organic acids, the and estimates were around 2.5 10 m mol s and 1.3 × 10 s, respectively. Based on the literature, these values indicate that the Cd- low-molecular-weight organic acids complexes formed between Cd and low-molecular-weight organic acids may be less labile than complexes formed with soil soluble organic matter but more labile than those formed with aminopolycarboxylic chelates. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

What's in a Name Change?

NASA Astrophysics Data System (ADS)

Martin, Joseph D.

2015-03-01

When solid state physics emerged in the 1940s, its name was controversial. By the 1970s, some physicists came to prefer "condensed matter" as a way to identify the discipline of physics examining complex matter. Physicists and historians often gloss this transition as a simple rebranding of a problematically named field, but attention to the motives behind these names reveals telling nuances. "Solid state physics" and "condensed matter physics"—along with "materials science," which also emerged during the Cold War—were named in accordance with ideological commitments about the identity of physics. Historians, therefore, can profitably understand solid state and condensed matter physics as distinct disciplines. Condensed matter, rather than being continuous with solid state physics, should be considered alongside materials science as an outlet for specific frustrations with the way solid state was organized.

Influences of NOM composition and bacteriological characteristics on biological stability in a full-scale drinking water treatment plant.

PubMed

Park, Ji Won; Kim, Hyun-Chul; Meyer, Anne S; Kim, Sungpyo; Maeng, Sung Kyu

2016-10-01

The influences of natural organic matter (NOM) and bacteriological characteristics on the biological stability of water were investigated in a full-scale drinking water treatment plant. We found that prechlorination decreased the hydrophobicity of the organic matter and significantly increased the high-molecular-weight (MW) dissolved organic matter, such as biopolymers and humic substances. High-MW organic matter and structurally complex compounds are known to be relatively slowly biodegradable; however, because of the prechlorination step, the indigenous bacteria could readily utilise these fractions as assimilable organic carbon. Sequential coagulation and sedimentation resulted in the substantial removal of biopolymer (74%), humic substance (33%), bacterial cells (79%), and assimilable organic carbon (67%). Rapid sand and granular activated carbon filtration induced an increase in the low-nucleic-acid content bacteria; however, these bacteria were biologically less active in relation to enzymatic activity and ATP. The granular activated carbon step was essential to securing biological stability (the ability to prevent bacterial growth) by removing the residual assimilable organic carbon that had formed during the ozone treatment. The growth potential of Escherichia coli and indigenous bacteria were found to differ in respect to NOM characteristics. In comparison with E. coli, the indigenous bacteria utilised a broader range of NOM as a carbon source. Principal component analysis demonstrated that the measured biological stability of water could differ, depending on the NOM characteristics, as well as on the bacterial inoculum selected for the analysis. Copyright © 2016 Elsevier Ltd. All rights reserved.

A Simplified Representation of the Chemical Nature and Reactions of Soil Humus.

ERIC Educational Resources Information Center

Stevenson, F. J.; Olsen, R. A.

1989-01-01

Presented is a comprehensible structural representation of humic substances. A number of important roles of soil organic matter, including contribution to the cation-exchange capacity, binding of pesticides, and formation of complexes with micronutrient cations, are illustrated. (Author/CW)

The ectomycorrhizal fungus Paxillus involutus converts organic matter in plant litter using a trimmed brown-rot mechanism involving Fenton chemistry

PubMed Central

Rineau, Francois; Roth, Doris; Shah, Firoz; Smits, Mark; Johansson, Tomas; Canbäck, Björn; Olsen, Peter Bjarke; Persson, Per; Grell, Morten Nedergaard; Lindquist, Erika; Grigoriev, Igor V; Lange, Lene; Tunlid, Anders

2012-01-01

Soils in boreal forests contain large stocks of carbon. Plants are the main source of this carbon through tissue residues and root exudates. A major part of the exudates are allocated to symbiotic ectomycorrhizal fungi. In return, the plant receives nutrients, in particular nitrogen from the mycorrhizal fungi. To capture the nitrogen, the fungi must at least partly disrupt the recalcitrant organic matter–protein complexes within which the nitrogen is embedded. This disruption process is poorly characterized. We used spectroscopic analyses and transcriptome profiling to examine the mechanism by which the ectomycorrhizal fungus Paxillus involutus degrades organic matter when acquiring nitrogen from plant litter. The fungus partially degraded polysaccharides and modified the structure of polyphenols. The observed chemical changes were consistent with a hydroxyl radical attack, involving Fenton chemistry similar to that of brown-rot fungi. The set of enzymes expressed by Pa. involutus during the degradation of the organic matter was similar to the set of enzymes involved in the oxidative degradation of wood by brown-rot fungi. However, Pa. involutus lacked transcripts encoding extracellular enzymes needed for metabolizing the released carbon. The saprotrophic activity has been reduced to a radical-based biodegradation system that can efficiently disrupt the organic matter–protein complexes and thereby mobilize the entrapped nutrients. We suggest that the released carbon then becomes available for further degradation and assimilation by commensal microbes, and that these activities have been lost in ectomycorrhizal fungi as an adaptation to symbiotic growth on host photosynthate. The interdependence of ectomycorrhizal symbionts and saprophytic microbes would provide a key link in the turnover of nutrients and carbon in forest ecosystems. PMID:22469289

Organic matter compounds as source indicators and tracers for marine pollution in a western Mediterranean coastal zone.

PubMed

Amorri, Jalila; Geffroy-Rodier, Claude; Boufahja, Fehmi; Mahmoudi, Ezzeddine; Aïssa, Patricia; Ksibi, Mohamed; Amblès, André

2011-11-01

Complex organic compounds found in oil and sediments linked with a particular source (such as algae, bacteria or vascular plants) are defined as biomarkers and are useful dating indicators in organic geochemistry. This paper presents the composition of the organic matter (OM) on marine surface sediments from a degraded Tunisian coast analysed by pyrolysis and gas chromatography-mass spectrometry (GC-MS). High total OM contents (0.3-4.2%) were detected with high levels of saturated linear hydrocarbons. The aliphatic lipids had contributed with up to 11.7% of the total OM, and their distribution had consisted of resolved compounds (n-alkanes and fatty acid (FAs)) and an unresolved complex mixture. Hydrocarbons, primarily n-alkanes, were ranged from 368 to 3,886 μg g(-1). The FAs (674-2,568 μg g(-1)) were dominated by derived primary production, and the short chain FAs (C16 and C18) were the most abundant throughout. The ubiquitous presence of petroleum contamination, mainly from offshore oil exploration, discharge of pollutants from rivers, shipping activities and atmospheric deposition was found in all samples. The Gabès littoral seems to be quite to very polluted near the industrial zone of Ghannouch. The C/H ratio (generally around 5.9), the thermal analysis and GC-MS of n-alkanes and FAs showed that the OM in the studied area was composed of anthropogenic/petrogenic, marine and continental sources. Our study represents an innovative approach to assessing environmental pollution. The evaluation of organic matter by examination of sterols, alkanes and fatty acids allows the identification of source, both anthropogenic and natural.

Organic matter exploitation in a highly turbid environment: Planktonic food web in the Charente estuary, France

NASA Astrophysics Data System (ADS)

Modéran, Julien; David, Valérie; Bouvais, Pierre; Richard, Pierre; Fichet, Denis

2012-02-01

Estuaries are highly dynamic systems where multiple organic matter sources coexist and where complex biogeochemical processes greatly affect their fate. Although zooplankton plays a key role of in the energy fluxes between primary sources and exploited macrofauna, there is still a critical lack of field information concerning the spatio-temporal variability of the trophic pathways supporting its high biomasses in estuaries. From January 2007 to January 2008, suspended matter, microphytobenthos and zooplankton were sampled along the salinity gradient of the Charente estuary to determine their carbon and nitrogen stable isotope composition. The relative homogeneity of the δ 13C values of particulate organic matter (POM) all along the estuary (-23.6 to -26.5‰ except in March and June, ˜ -28.5‰) was attributed to physical mixing of marine and terrestrially derived organic matter with the great load of tidally resuspended particles. The five zooplankton taxa analysed displayed a wide range of δ 13C (from -34.9 to -17.4‰) and δ 15N values (3.4-15.2‰) over the year, providing strong evidence for high selectivity toward different organic matter sources and reinforcing the idea that a spatio-temporal succession of species assemblages lead to multiple trophic pathways and may stabilize the estuarine trophic network. The high δ 15N values of Eurytemora affinis in the maximum turbidity zone were believed to reflect a higher carnivorous tendency as a functional response to the strong decrease of phytoplankton availability. Conversely, Acartia spp. appeared unable to change their diet in the same way and was thus unable to colonize upstream areas. Stable isotope analysis also revealed that Mesopodopsis slabberi mostly relied on fresh phytoplankton and microphytobenthos while Neomysis integer presented a clear carnivorous tendency toward copepods, at least during the warm period. Additionally evidence was provided for passive (downstream advection of freshwater cladocerans with river runoffs) and active (coast-estuary seasonal migration of M. slabberi) longitudinal movements in estuarine organisms.

Influence of iron redox cycling on organo-mineral associations in Arctic tundra soil

DOE PAGES

Herndon, Elizabeth; Oak Ridge National Lab.; AlBashaireh, Amineh; ...

2017-03-25

Arctic tundra stores large quantities of soil organic matter under varying redox conditions. As the climate warms, these carbon reservoirs are susceptible to increased rates of decomposition and release to the atmosphere as the greenhouse gases carbon dioxide (CO 2) and methane (CH 4). Geochemical interactions between soil organic matter and minerals influence decomposition in many environments but remain poorly understood in Arctic tundra systems and are not considered in decomposition models. The accumulation of iron (Fe) oxyhydroxides and organo- iron precipitates at redox interfaces may be particularly important for carbon cycling given that ferric iron [Fe(III)] species can enhancemore » decomposition by serving as terminal electron acceptors in anoxic soils or inhibit microbial decomposition by binding organic molecules. Here in this paper, we examine chemical properties of solid-phase Fe and organic matter in organic and mineral horizons within the seasonally thawed active layer of Arctic tundra on the North Slope of Alaska. Spectroscopic techniques, including micro-X-ray fluorescence ( XRF) mapping, micro-X-ray absorption near-edge structure ( XANES) spectroscopy, and Fourier transform infrared spectroscopy (FTIR), were coupled with chemical sequential extractions and physical density fractionations to evaluate the spatial distribution and speciation of Fe-bearing phases and associated organic matter in soils. Organic horizons were enriched in poorly crystalline and crystalline iron oxides, and approximately 60% of total Fe stored in organic horizons was calculated to derive from upward translocation from anoxic mineral horizons. Ferrihydrite and goethite were present as coatings on mineral grains and plant debris, and in aggregates with clays and particulate organic matter. Minor amounts of ferrous iron [Fe(II)] were present in iron sulfides (i.e., pyrite and greigite) in mineral horizon soils and iron phosphates (vivianite) in organic horizons. Concentrations of organic carbon in the organic horizons (28 ± 5% wt. % C) were approximately twice the concentrations in the mineral horizons (14 ± 2 % wt. C), and organic matter was dominated by base-extractable and insoluble organics enriched in aromatic and aliphatic moieties. Conversely, water-soluble organic molecules and organics solubilized through acid-dissolution of iron oxides comprised < 2% of soil organic C and were consistent with a mixture of alcohols, sugars, and small molecular weight organic acids and aromatics released through decomposition of larger molecules. Integrated over the entire depth of the active layer, soils contained 11± 4 kg m -2 low- density, particulate organic C and 19 ± 6 kg m -2 high-density, mineral-associated organic C, indicating that 63 ±19% of organic C in the active layer was associated with the mineral fraction. We conclude that organic horizons were enriched in poorly crystalline and crystalline iron oxide phases derived from upward translocation of dissolved Fe(II) and Fe(III) from mineral horizons. Precipitation of iron oxides at the redox interface has the potential to contribute to mineral protection of organic matter and increase the residence time of organic carbon in arctic soils. Our results suggest that iron oxides may inhibit organic carbon degradation by binding low-molecular-weight organic compounds, stabilizing soil aggregates, and forming thick coatings around particulate organic matter. Organic matter released through acid-dissolution of iron oxides could represent a small pool of readily-degradable organic molecules temporarily stabilized by sorption to iron oxyhydroxide surfaces. The distribution of iron in organic complexes and inorganic phases throughout the soil column constrains Fe(III) availability to anaerobic iron-reducing microorganisms that oxidize organic matter to produce CO 2 and CH 4 in these anoxic environments. Future predictions of carbon storage and respiration in the arctic tundra should consider such influences of mineral stabilization under changing redox conditions.« less

Influence of iron redox cycling on organo-mineral associations in Arctic tundra soil

NASA Astrophysics Data System (ADS)

Herndon, Elizabeth; AlBashaireh, Amineh; Singer, David; Roy Chowdhury, Taniya; Gu, Baohua; Graham, David

2017-06-01

Arctic tundra stores large quantities of soil organic matter under varying redox conditions. As the climate warms, these carbon reservoirs are susceptible to increased rates of decomposition and release to the atmosphere as the greenhouse gases carbon dioxide (CO2) and methane (CH4). Geochemical interactions between soil organic matter and minerals influence decomposition in many environments but remain poorly understood in Arctic tundra systems and are not considered in decomposition models. The accumulation of iron (Fe) oxyhydroxides and organo-iron precipitates at redox interfaces may be particularly important for carbon cycling given that ferric iron [Fe(III)] species can enhance decomposition by serving as terminal electron acceptors in anoxic soils or inhibit microbial decomposition by binding organic molecules. Here, we examine chemical properties of solid-phase Fe and organic matter in organic and mineral horizons within the seasonally thawed active layer of Arctic tundra on the North Slope of Alaska. Spectroscopic techniques, including micro-X-ray fluorescence (μXRF) mapping, micro-X-ray absorption near-edge structure (μXANES) spectroscopy, and Fourier transform infrared spectroscopy (FTIR), were coupled with chemical sequential extractions and physical density fractionations to evaluate the spatial distribution and speciation of Fe-bearing phases and associated organic matter in soils. Organic horizons were enriched in poorly crystalline and crystalline iron oxides, and approximately 60% of total Fe stored in organic horizons was calculated to derive from upward translocation from anoxic mineral horizons. Ferrihydrite and goethite were present as coatings on mineral grains and plant debris, and in aggregates with clays and particulate organic matter. Minor amounts of ferrous iron [Fe(II)] were present in iron sulfides (i.e., pyrite and greigite) in mineral horizon soils and iron phosphates (vivianite) in organic horizons. Concentrations of organic carbon in the organic horizons (28 ± 5 wt.% C) were approximately twice the concentrations in the mineral horizons (14 ± 2 wt.% C), and organic matter was dominated by base-extractable and insoluble organics enriched in aromatic and aliphatic moieties. Conversely, water-soluble organic molecules and organics solubilized through acid-dissolution of iron oxides comprised <2% of soil organic C and were consistent with a mixture of alcohols, sugars, and small molecular weight organic acids and aromatics released through decomposition of larger molecules. Integrated over the entire depth of the active layer, soils contained 11 ± 4 kg m-2 low-density, particulate organic C and 19 ± 6 kg m-2 high-density, mineral-associated organic C, indicating that 63 ± 19% of organic C in the active layer was associated with the mineral fraction. We conclude that organic horizons were enriched in poorly crystalline and crystalline iron oxide phases derived from upward translocation of dissolved Fe(II) and Fe(III) from mineral horizons. Precipitation of iron oxides at the redox interface has the potential to contribute to mineral protection of organic matter and increase the residence time of organic carbon in arctic soils. Our results suggest that iron oxides may inhibit organic carbon degradation by binding low-molecular-weight organic compounds, stabilizing soil aggregates, and forming thick coatings around particulate organic matter. Organic matter released through acid-dissolution of iron oxides could represent a small pool of readily-degradable organic molecules temporarily stabilized by sorption to iron oxyhydroxide surfaces. The distribution of iron in organic complexes and inorganic phases throughout the soil column constrains Fe(III) availability to anaerobic iron-reducing microorganisms that oxidize organic matter to produce CO2 and CH4 in these anoxic environments. Future predictions of carbon storage and respiration in the arctic tundra should consider such influences of mineral stabilization under changing redox conditions.

Influence of iron redox cycling on organo-mineral associations in Arctic tundra soil

DOE Office of Scientific and Technical Information (OSTI.GOV)

Herndon, Elizabeth; Oak Ridge National Lab.; AlBashaireh, Amineh

Arctic tundra stores large quantities of soil organic matter under varying redox conditions. As the climate warms, these carbon reservoirs are susceptible to increased rates of decomposition and release to the atmosphere as the greenhouse gases carbon dioxide (CO 2) and methane (CH 4). Geochemical interactions between soil organic matter and minerals influence decomposition in many environments but remain poorly understood in Arctic tundra systems and are not considered in decomposition models. The accumulation of iron (Fe) oxyhydroxides and organo- iron precipitates at redox interfaces may be particularly important for carbon cycling given that ferric iron [Fe(III)] species can enhancemore » decomposition by serving as terminal electron acceptors in anoxic soils or inhibit microbial decomposition by binding organic molecules. Here in this paper, we examine chemical properties of solid-phase Fe and organic matter in organic and mineral horizons within the seasonally thawed active layer of Arctic tundra on the North Slope of Alaska. Spectroscopic techniques, including micro-X-ray fluorescence ( XRF) mapping, micro-X-ray absorption near-edge structure ( XANES) spectroscopy, and Fourier transform infrared spectroscopy (FTIR), were coupled with chemical sequential extractions and physical density fractionations to evaluate the spatial distribution and speciation of Fe-bearing phases and associated organic matter in soils. Organic horizons were enriched in poorly crystalline and crystalline iron oxides, and approximately 60% of total Fe stored in organic horizons was calculated to derive from upward translocation from anoxic mineral horizons. Ferrihydrite and goethite were present as coatings on mineral grains and plant debris, and in aggregates with clays and particulate organic matter. Minor amounts of ferrous iron [Fe(II)] were present in iron sulfides (i.e., pyrite and greigite) in mineral horizon soils and iron phosphates (vivianite) in organic horizons. Concentrations of organic carbon in the organic horizons (28 ± 5% wt. % C) were approximately twice the concentrations in the mineral horizons (14 ± 2 % wt. C), and organic matter was dominated by base-extractable and insoluble organics enriched in aromatic and aliphatic moieties. Conversely, water-soluble organic molecules and organics solubilized through acid-dissolution of iron oxides comprised < 2% of soil organic C and were consistent with a mixture of alcohols, sugars, and small molecular weight organic acids and aromatics released through decomposition of larger molecules. Integrated over the entire depth of the active layer, soils contained 11± 4 kg m -2 low- density, particulate organic C and 19 ± 6 kg m -2 high-density, mineral-associated organic C, indicating that 63 ±19% of organic C in the active layer was associated with the mineral fraction. We conclude that organic horizons were enriched in poorly crystalline and crystalline iron oxide phases derived from upward translocation of dissolved Fe(II) and Fe(III) from mineral horizons. Precipitation of iron oxides at the redox interface has the potential to contribute to mineral protection of organic matter and increase the residence time of organic carbon in arctic soils. Our results suggest that iron oxides may inhibit organic carbon degradation by binding low-molecular-weight organic compounds, stabilizing soil aggregates, and forming thick coatings around particulate organic matter. Organic matter released through acid-dissolution of iron oxides could represent a small pool of readily-degradable organic molecules temporarily stabilized by sorption to iron oxyhydroxide surfaces. The distribution of iron in organic complexes and inorganic phases throughout the soil column constrains Fe(III) availability to anaerobic iron-reducing microorganisms that oxidize organic matter to produce CO 2 and CH 4 in these anoxic environments. Future predictions of carbon storage and respiration in the arctic tundra should consider such influences of mineral stabilization under changing redox conditions.« less

PREFACE: Topics in the application of scattering methods to investigate the structure and dynamics of soft condensed matter

NASA Astrophysics Data System (ADS)

Chen, Sow-Hsin; Baglioni, Piero

2006-09-01

This special issue of Journal of Physics: Condensed Matter gathers together a series of contributions presented at the workshop entitled `Topics in the Application of Scattering Methods to Investigate the Structure and Dynamics of Soft Condensed Matter' held at Pensione Bencista, Fiesole, Italy, a wonderful Italian jewel tucked high in the hills above Florence. This immaculate 14th century villa is a feast for the eyes with antiques and original artwork everywhere you turn, and a stunning view of Florence, overlooking numerous villas and groves of olive trees. The meeting consisted of about 40 invited talks delivered by a selected group of prominent physicists and chemists from the USA, Mexico, Europe and Asia working in the fields of complex and glassy liquids. The topics covered by the talks included: simulations on the liquid-liquid transition phenomenon dynamic crossover in deeply supercooled confined water thermodynamics and dynamics of complex fluids dynamics of interfacial water structural arrest transitions in colloidal systems structure and dynamics in complex systems structure of supramolecular assemblies The choice of topics is obviously heavily biased toward the current interests of the two organizers of the workshop, in view of the fact that one of the incentives for organizing the meeting was to celebrate Sow-Hsin Chen’s life-long scientific activities on the occasion of his 70th birthday. The 21 articles presented in this issue are a state-of-the-art description of the different aspects reported at the workshop from all points of view---experimental, theoretical and numerical. The interdisciplinary nature of the talks should make this special issue of interest to a broad community of scientists involved in the study of the properties of complex fluids, soft condensed matter and disordered glassy systems. We are grateful to the Consorzio per lo Sviluppo dei Sistemi a Grande Interfase (CSGI), Florence, Italy and to the Materials Science Program of the US Department of Energy for their support of the workshop.

Quality control considerations for size exclusion chromatography with online ICP-MS: a powerful tool for evaluating the size dependence of metal-organic matter complexation.

PubMed

McKenzie, Erica R; Young, Thomas M

2013-01-01

Size exclusion chromatography (SEC), which separates molecules based on molecular volume, can be coupled with online inductively coupled plasma mass spectrometry (ICP-MS) to explore size-dependent metal-natural organic matter (NOM) complexation. To make effective use of this analytical dual detector system, the operator should be mindful of quality control measures. Al, Cr, Fe, Se, and Sn all exhibited columnless attenuation, which indicated unintended interactions with system components. Based on signal-to-noise ratio and peak reproducibility between duplicate analyses of environmental samples, consistent peak time and height were observed for Mg, Cl, Mn, Cu, Br, and Pb. Al, V, Fe, Co, Ni, Zn, Se, Cd, Sn, and Sb were less consistent overall, but produced consistent measurements in select samples. Ultrafiltering and centrifuging produced similar peak distributions, but glass fiber filtration produced more high molecular weight (MW) peaks. Storage in glass also produced more high MW peaks than did plastic bottles.

The characteristics of dissolved organic matter (DOM) in storm sewer sediments and the binding interaction with Cu(II) in four typical regions in Beijing, China.

PubMed

Zhang, Ziyang; Li, Kun; Zhang, Xiaoran; Li, Haiyan

2017-07-01

In this work, dissolved organic matter (DOM) was extracted from storm sewer sediments collected in four typical regions (residential, campus, traffic and business regions) in Beijing, China. The basic characteristics of DOM were analyzed by UV-visible spectroscopy (UV-Vis), excitation-emission matrix Fluorescence Spectroscopy and Fourier Transform Infrared Spectroscopy. Furthermore, the complexation between DOM and Cu(II) were investigated. The results showed that there were large amount of aromatic structure in the DOM extracted from storm sewer sediments. The microbial activities had also made a contribution to the DOM in storm sewer sediments. The composition of DOM influenced the complexing capacity of Cu(II) greatly, which may be attributed to the protein-like and humic-like substances in storm sewer sediments. This study demonstrated valuable information on the structure present in the DOM of storm sewer sediments and provided new insight for exploring the relationship between DOM and co-existing heavy metals in storm sewer sediments.

Unseen players shape benthic competition on coral reefs.

PubMed

Barott, Katie L; Rohwer, Forest L

2012-12-01

Recent work has shown that hydrophilic and hydrophobic organic matter (OM) from algae disrupts the function of the coral holobiont and promotes the invasion of opportunistic pathogens, leading to coral morbidity and mortality. Here we refer to these dynamics as the (3)DAM [dissolved organic matter (DOM), direct contact, disease, algae and microbes] model. There is considerable complexity in coral-algae interactions; turf algae and macroalgae promote heterotrophic microbial overgrowth of coral, macroalgae also directly harm the corals via hydrophobic OM, whereas crustose coralline algae generally encourage benign microbial communities. In addition, complex flow patterns transport OM and pathogens from algae to downstream corals, and direct algal contact enhances their delivery. These invisible players (microbes, viruses, and OM) are important drivers of coral reefs because they have non-linear responses to disturbances and are the first to change in response to perturbations, providing near real-time trajectories for a coral reef, a vital metric for conservation and restoration. Copyright © 2012 Elsevier Ltd. All rights reserved.

Organic solvent soluble oxide supported hydrogenation catalyst precursors

DOEpatents

Edlund, David J.; Finke, Richard G.; Saxton, Robert J.

1992-01-01

The present invention discloses two polyoxoanion supported metal complexes found to be useful in olefin hydrogenation. The complexes are novel compositions of matter which are soluble in organic solvents. In particular, the compositions of matter comprise A.sub.x [L.sub.n Ir.sup.(I) .multidot.X.sub.2 M.sub.15 M'.sub.3 O.sub.62 ].sup.x- and A.sub.y [L.sub.n Ir.sup.(I) .multidot.X.sub.2 M.sub.9 M'.sub.3 O.sub.40 ].sup.y- where L is a ligand preferably chosen from 1,5-cyclooctadiene (COD), ethylene, cyclooctene, norbornadiene and other olefinic ligands; n=1 or 2 depending upon the number of double bonds present in the ligand L; X is a "hetero" atom chosen from B, Si, Ge, P, As, Se, Te, I, Co, Mn and Cu; M is either W or Mo; M' is preferably Nb or V but Ti, Zr, Ta, Hf are also useful; and A is a countercation preferably selected from tetrabutyl ammonium and alkali metal ions.

Chemical evolution of atmospheric organic carbon over multiple generations of oxidation

NASA Astrophysics Data System (ADS)

Isaacman-VanWertz, Gabriel; Massoli, Paola; O'Brien, Rachel; Lim, Christopher; Franklin, Jonathan P.; Moss, Joshua A.; Hunter, James F.; Nowak, John B.; Canagaratna, Manjula R.; Misztal, Pawel K.; Arata, Caleb; Roscioli, Joseph R.; Herndon, Scott T.; Onasch, Timothy B.; Lambe, Andrew T.; Jayne, John T.; Su, Luping; Knopf, Daniel A.; Goldstein, Allen H.; Worsnop, Douglas R.; Kroll, Jesse H.

2018-02-01

The evolution of atmospheric organic carbon as it undergoes oxidation has a controlling influence on concentrations of key atmospheric species, including particulate matter, ozone and oxidants. However, full characterization of organic carbon over hours to days of atmospheric processing has been stymied by its extreme chemical complexity. Here we study the multigenerational oxidation of α-pinene in the laboratory, characterizing products with several state-of-the-art analytical techniques. Although quantification of some early generation products remains elusive, full carbon closure is achieved (within measurement uncertainty) by the end of the experiments. These results provide new insights into the effects of oxidation on organic carbon properties (volatility, oxidation state and reactivity) and the atmospheric lifecycle of organic carbon. Following an initial period characterized by functionalization reactions and particle growth, fragmentation reactions dominate, forming smaller species. After approximately one day of atmospheric aging, most carbon is sequestered in two long-lived reservoirs—volatile oxidized gases and low-volatility particulate matter.

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

PubMed

Rao, Ashit; Cölfen, Helmut

2018-03-24

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

Chemical evolution of atmospheric organic carbon over multiple generations of oxidation.

PubMed

Isaacman-VanWertz, Gabriel; Massoli, Paola; O'Brien, Rachel; Lim, Christopher; Franklin, Jonathan P; Moss, Joshua A; Hunter, James F; Nowak, John B; Canagaratna, Manjula R; Misztal, Pawel K; Arata, Caleb; Roscioli, Joseph R; Herndon, Scott T; Onasch, Timothy B; Lambe, Andrew T; Jayne, John T; Su, Luping; Knopf, Daniel A; Goldstein, Allen H; Worsnop, Douglas R; Kroll, Jesse H

2018-04-01

The evolution of atmospheric organic carbon as it undergoes oxidation has a controlling influence on concentrations of key atmospheric species, including particulate matter, ozone and oxidants. However, full characterization of organic carbon over hours to days of atmospheric processing has been stymied by its extreme chemical complexity. Here we study the multigenerational oxidation of α-pinene in the laboratory, characterizing products with several state-of-the-art analytical techniques. Although quantification of some early generation products remains elusive, full carbon closure is achieved (within measurement uncertainty) by the end of the experiments. These results provide new insights into the effects of oxidation on organic carbon properties (volatility, oxidation state and reactivity) and the atmospheric lifecycle of organic carbon. Following an initial period characterized by functionalization reactions and particle growth, fragmentation reactions dominate, forming smaller species. After approximately one day of atmospheric aging, most carbon is sequestered in two long-lived reservoirs-volatile oxidized gases and low-volatility particulate matter.

Genetic difference but functional similarity among fish gut bacterial communities through molecular and biochemical fingerprints.

PubMed

Mouchet, Maud A; Bouvier, Corinne; Bouvier, Thierry; Troussellier, Marc; Escalas, Arthur; Mouillot, David

2012-03-01

Considering the major involvement of gut microflora in the digestive function of various macro-organisms, bacterial communities inhabiting fish guts may be the main actors of organic matter degradation by fish. Nevertheless, the extent and the sources of variability in the degradation potential of gut bacterial communities are largely overlooked. Using Biolog Ecoplate™ and denaturing gradient gel electrophoresis (DGGE), we explored functional (i.e. the ability to degrade organic matter) and genetic (i.e. identification of DGGE banding patterns) diversity of fish gut bacterial communities, respectively. Gut bacterial communities were extracted from fish species characterized by different diets sampled along a salinity gradient in the Patos-Mirim lagoons complex (Brazil). We found that functional diversity was surprisingly unrelated to genetic diversity of gut bacterial communities. Functional diversity was not affected by the sampling site but by fish species and diet, whereas genetic diversity was significantly influenced by all three factors. Overall, the functional diversity was consistently high across fish individuals and species, suggesting a wide functional niche breadth and a high potential of organic matter degradation. We conclude that fish gut bacterial communities may strongly contribute to nutrient cycling regardless of their genetic diversity and environment. © European Union 2011.

Data-Driven Astrochemistry: One Step Further within the Origin of Life Puzzle.

PubMed

Ruf, Alexander; d'Hendecourt, Louis L S; Schmitt-Kopplin, Philippe

2018-06-01

Astrochemistry, meteoritics and chemical analytics represent a manifold scientific field, including various disciplines. In this review, clarifications on astrochemistry, comet chemistry, laboratory astrophysics and meteoritic research with respect to organic and metalorganic chemistry will be given. The seemingly large number of observed astrochemical molecules necessarily requires explanations on molecular complexity and chemical evolution, which will be discussed. Special emphasis should be placed on data-driven analytical methods including ultrahigh-resolving instruments and their interplay with quantum chemical computations. These methods enable remarkable insights into the complex chemical spaces that exist in meteorites and maximize the level of information on the huge astrochemical molecular diversity. In addition, they allow one to study even yet undescribed chemistry as the one involving organomagnesium compounds in meteorites. Both targeted and non-targeted analytical strategies will be explained and may touch upon epistemological problems. In addition, implications of (metal)organic matter toward prebiotic chemistry leading to the emergence of life will be discussed. The precise description of astrochemical organic and metalorganic matter as seeds for life and their interactions within various astrophysical environments may appear essential to further study questions regarding the emergence of life on a most fundamental level that is within the molecular world and its self-organization properties.

FTIR Analysis of Functional Groups in Aerosol Particles

NASA Astrophysics Data System (ADS)

Shokri, S. M.; McKenzie, G.; Dransfield, T. J.

2012-12-01

Secondary organic aerosols (SOA) are suspensions of particulate matter composed of compounds formed from chemical reactions of organic species in the atmosphere. Atmospheric particulate matter can have impacts on climate, the environment and human health. Standardized techniques to analyze the characteristics and composition of complex secondary organic aerosols are necessary to further investigate the formation of SOA and provide a better understanding of the reaction pathways of organic species in the atmosphere. While Aerosol Mass Spectrometry (AMS) can provide detailed information about the elemental composition of a sample, it reveals little about the chemical moieties which make up the particles. This work probes aerosol particles deposited on Teflon filters using FTIR, based on the protocols of Russell, et al. (Journal of Geophysical Research - Atmospheres, 114, 2009) and the spectral fitting algorithm of Takahama, et al (submitted, 2012). To validate the necessary calibration curves for the analysis of complex samples, primary aerosols of key compounds (e.g., citric acid, ammonium sulfate, sodium benzoate) were generated, and the accumulated masses of the aerosol samples were related to their IR absorption intensity. These validated calibration curves were then used to classify and quantify functional groups in SOA samples generated in chamber studies by MIT's Kroll group. The fitting algorithm currently quantifies the following functionalities: alcohols, alkanes, alkenes, amines, aromatics, carbonyls and carboxylic acids.

Complex Catchment Processes that Control Stream Nitrogen and Organic Matter Concentrations in a Northeastern USA Upland Catchment

NASA Astrophysics Data System (ADS)

Sebestyen, S. D.; Shanley, J. B.; Pellerin, B.; Saraceno, J.; Aiken, G. R.; Boyer, E. W.; Doctor, D. H.; Kendall, C.

2009-05-01

There is a need to understand the coupled biogeochemical and hydrological processes that control stream hydrochemistry in upland forested catchments. At watershed 9 (W-9) of the Sleepers River Research Watershed in the northeastern USA, we use high-frequency sampling, environmental tracers, end-member mixing analysis, and stream reach mass balances to understand dynamic factors affect forms and concentrations of nitrogen and organic matter in streamflow. We found that rates of stream nitrate processing changed during autumn baseflow and that up to 70% of nitrate inputs to a stream reach were retained. At the same time, the stream reach was a net source of the dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) fractions of dissolved organic matter (DOM). The in-stream nitrate loss and DOM gains are examples of hot moments of biogeochemical transformations during autumn when deciduous litter fall increases DOM availability. As hydrological flowpaths changed during rainfall events, the sources and transformations of nitrate and DOM differed from baseflow. For example, during storm flow we measured direct inputs of unprocessed atmospheric nitrate to streams that were as large as 30% of the stream nitrate loading. At the same time, stream DOM composition shifted to reflect inputs of reactive organic matter from surficial upland soils. The transport of atmospheric nitrate and reactive DOM to streams underscores the importance of quantifying source variation during short-duration stormflow events. Building upon these findings we present a conceptual model of interacting ecosystem processes that control the flow of water and nutrients to streams in a temperate upland catchment.

Humic substances-mediated microbial reductive dehalogenation of triclosan

NASA Astrophysics Data System (ADS)

Wang, L.; Xu, S.; Yang, Y.

2015-12-01

The role of natural organic matter in regulating the redox reactions as an electron shuttle has received lots of attention, because it can significantly affect the environmental degradation of contaminants and biogeochemical cycles of major elements. However, up to date, limited studies examined the role of natural organic matter in affecting the microbial dehalogenation of emergent organohalides, a critical detoxification process. In this study, we investigated the humic substance (HS)-mediated microbial dehalogenation of triclosan, a widely used antimicrobial agent. We found that the presence of HS stimulated the microbial degradation of triclosan by Shewanella putrefaciens CN-32. In the absence of HS, the triclosan was degraded gradually, achieving 8.6% residual at 8 days. With HS, the residual triclosan was below 2% after 4 days. Cl- was confirmed by ion chromatography analysis, but the dehalogenation processes and other byproducts warrant further investigations. The impact of HS on the degradation of triclosan was highly dependent on the concentration of HS. When the HS was below 15 mg/L, the degradation rate constant for triclosan increased with the organic carbon concentration. Beyond that point, the increased organic carbon concentration decreased the degradation of triclosan. Microbially pre-reduced HS abiotically reduced triclosan, testifying the electron shuttling processes. These results indicate that dissolved organic matter plays a dual role in regulating the degradation of triclosan: it mediates electron transport and inhibits the bioavailability through complexation. Such novel organic matter-mediated reactions for organohalides are important for evaluating the natural attenuation of emergent contaminants and designing cost-effective engineering treatment.

Assessing food web dynamics and relative importance of organic matter sources for fish species in two Portuguese estuaries: a stable isotope approach.

PubMed

França, Susana; Vasconcelos, Rita P; Tanner, Susanne; Máguas, Cristina; Costa, Maria José; Cabral, Henrique N

2011-10-01

Stable carbon and nitrogen isotopes (δ¹³C, δ¹⁵N) were used to analyse food web dynamics of two of the main estuaries of the Portuguese coast: Tejo and Mira. The ultimate sources of organic matter supporting production of some of the most abundant and commercially important fish species were determined; and seasonal, inter- and intra- estuarine differences in the trophic relations among producers and consumers were identified. Stable isotope analysis was performed in different producers, primary consumers (main prey items for fish) and fish species (Solea solea, Solea senegalensis, Pomatoschistus microps, Dicentrarchus labrax, Liza ramada, Diplodus vulgaris and Atherina presbyter) of two areas in each estuary, in July and October 2009. Model calculations showed that the main prey for the fish species in the Tejo estuary used mostly salt marsh-derived organic matter as nutritional sources, with no marked differences between the sampled months. Trophic levels of fish species from the same estuary differed at multiple scales: inter-species, seasonally and spatially (both between and within estuaries). Significant differences in isotopic composition of fish species were more pronounced spatially (between the two sampled areas in the estuary) than seasonally (between sampled months). Trophic relationships in both estuaries demonstrated that organic matter is transferred to higher trophic positions mainly through benthic pathways. This shows the flexibility of these species to share resources and to exploit temporary peaks in prey populations. The present results showed that extensive disturbance in intertidal habitats from both estuaries may potentially change the balance of organic matter in the base of these complex food webs. Copyright © 2011 Elsevier Ltd. All rights reserved.

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.

Abiotic Bromination of Soil Organic Matter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Leri, Alessandra C.; Ravel, Bruce

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 andmore » 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.« less

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.

The microbial community of a passive biochemical reactor treating arsenic, zinc, and sulfate-rich seepage.

PubMed

Baldwin, Susan Anne; Khoshnoodi, Maryam; Rezadehbashi, Maryam; Taupp, Marcus; Hallam, Steven; Mattes, Al; Sanei, Hamed

2015-01-01

Sulfidogenic biochemical reactors (BCRs) for metal removal that use complex organic carbon have been shown to be effective in laboratory studies, but their performance in the field is highly variable. Successful operation depends on the types of microorganisms supported by the organic matrix, and factors affecting the community composition are unknown. A molecular survey of a field-based BCR that had been removing zinc and arsenic for over 6 years revealed that the microbial community was dominated by methanogens related to Methanocorpusculum sp. and Methanosarcina sp., which co-occurred with Bacteroidetes environmental groups, such as Vadin HA17, in places where the organic matter was more degraded. The metabolic potential for organic matter decomposition by Ruminococcaceae was prevalent in samples with more pyrolyzable carbon. Rhodobium- and Hyphomicrobium-related genera within the Rhizobiales order that have the metabolic potential for dark hydrogen fermentation and methylotrophy, and unclassified Comamonadaceae were the dominant Proteobacteria. The unclassified environmental group Sh765B-TzT-29 was an important Delta-Proteobacteria group in this BCR that co-occurred with the dominant Rhizobiales operational taxonomic units. Organic matter degradation is one driver for shifting the microbial community composition and therefore possibly the performance of these bioreactors over time.

Metal complexation properties of freshwater dissolved organic matter are explained by its aromaticity and by anthropogenic ligands.

PubMed

Baken, Stijn; Degryse, Fien; Verheyen, Liesbeth; Merckx, Roel; Smolders, Erik

2011-04-01

Dissolved organic matter (DOM) in surface waters affects the fate and environmental effects of trace metals. We measured variability in the Cd, Cu, Ni, and Zn affinity of 23 DOM samples isolated by reverse osmosis from freshwaters in natural, agricultural, and urban areas. Affinities at uniform pH and ionic composition were assayed at low, environmentally relevant free Cd, Cu, Ni, and Zn activities. The C-normalized metal binding of DOM varied 4-fold (Cu) or about 10-fold (Cd, Ni, Zn) among samples. The dissolved organic carbon concentration ranged only 9-fold in the waters, illustrating that DOM quality is an equally important parameter for metal complexation as DOM quantity. The UV-absorbance of DOM explained metal affinity only for waters receiving few urban inputs, indicating that in those waters, aromatic humic substances are the dominant metal chelators. Larger metal affinities were found for DOM from waters with urban inputs. Aminopolycarboxylate ligands (mainly EDTA) were detected at concentrations up to 0.14 μM and partly explained the larger metal affinity. Nickel concentrations in these surface waters are strongly related to EDTA concentrations (R2=0.96) and this is underpinned by speciation calculations. It is concluded that metal complexation in waters with anthropogenic discharges is larger than that estimated with models that only take into account binding on humic substances.

Do constructed wetlands remove metals or increase metal bioavailability?

PubMed

Xu, Xiaoyu; Mills, Gary L

2018-07-15

The H-02 wetland was constructed to treat building process water and storm runoff water from the Tritium Processing Facility on the Department of Energy's Savannah River Site (Aiken, SC). Monthly monitoring of copper (Cu) and zinc (Zn) concentrations and water quality parameters in surface waters continued from 2014 to 2016. Metal speciation was modeled at each sampling occasion. Total Cu and Zn concentrations released to the effluent stream were below the NPDES limit, and the average removal efficiency was 65.9% for Cu and 71.1% for Zn. The metal-removal processes were found out to be seasonally regulated by sulfur cycling indicated by laboratory and model results. High temperature, adequate labile organic matter, and anaerobic conditions during the warm months (February to August) favored sulfate reduction that produced sulfide minerals to significantly remove metals. However, the dominant reaction in sulfur cycling shifted to sulfide oxidation during the cool months (September to next March). High concentrations of metal-organic complexes were observed, especially colloidal complexes of metal and fulvic acid (FA), demonstrating adsorption to organic matter became the primary process for metal removal. Meanwhile, the accumulation of metal-FA complexes in the wetland system will cause negative effects to the surrounding environment as they are biologically reactive, highly bioavailable, and can be easily taken up and transferred to ecosystems by trophic exchange. Copyright © 2018 Elsevier Ltd. All rights reserved.

A literature review of interaction of oxidized uranium species and uranium complexes with soluble organic matter

USGS Publications Warehouse

Jennings, Joan K.; Leventhal, J.S.

1978-01-01

Organic material is commonly found associated with uranium ores in sandstone-type deposits. This review of the literature summarizes the classes and separations of naturally occurring organic material but the emphasis is on soluble organic species. The main class of materials of interest is humic substances which are high-molecular-weight complex molecules that are soluble in alkaline solution. These humic substances are able to solubilize (make soluble) minerals and also to complex [by ion exchange and (or) chelation] many cations. The natural process of soil formation results in both mineral decomposition and element complexing by organic species. Uranium in solution, such as ground water, can form many species with other elements or complexes present depending on Eh and pH. In natural systems (oxidizing Eh, pH 5-9) the uranium is usually present as a complex with hydroxide or carbonate. Thermodynamic data for these species are presented. Interacting metals and organic materials have been observed in nature and studied in the laboratory by many workers in diverse scientific disciplines. The results are not easily compared. Measurements of the degree of complexation are reported as equilibrium stability constant determinations. This type of research has been done for Mn, Fe, Cu, Zn, Pb, Ni, Co, Mg, Ca, Al, and to a limited degree for U. The use of Conditional Stability Constants has given quantitative results in some cases. The methods utilized in experiments and calculations are reviewed.

Development and validation of a MODIS colored dissolved organic matter (CDOM) algorithm in northwest Florida estuaries

EPA Science Inventory

Satellite remote sensing provides synoptic and frequent monitoring of water quality parameters that aids in determining the health of aquatic ecosystems and the development of effective management strategies. Northwest Florida estuaries are classified as optically-complex, or wat...

Chemical modeling of boron adsorption by humic materials using the constant capacitance model

USDA-ARS?s Scientific Manuscript database

The constant capacitance surface complexation model was used to describe B adsorption behavior on reference Aldrich humic acid, humic acids from various soil environments, and dissolved organic matter extracted from sewage effluents. The reactive surface functional groups on the humic materials wer...

The circuitry of ecosystem metabolism: CO2 and CH4 flux from permafrost soils

USDA-ARS?s Scientific Manuscript database

Microbial decomposition of thawed permafrost organic matter could release greenhouse gases (GHG) to the atmosphere and accelerate the carbon (C)-climate feedback. Greenhouse gas emissions from thawed permafrost are difficult to predict because they result from complex interactions between abiotic dr...

Comparison of Solid-Water Partitions of Radiocesium in River Waters in Fukushima and Chernobyl Areas.

PubMed

Takahashi, Yoshio; Fan, Qiaohui; Suga, Hiroki; Tanaka, Kazuya; Sakaguchi, Aya; Takeichi, Yasuo; Ono, Kanta; Mase, Kazuhiko; Kato, Kenji; Kanivets, Vladimir V

2017-09-29

Adsorption of radiocesium (RCs) on particulate matters in aquatic environment is important to understand its mobility and bioavailability. We here focused on factors controlling partition of RCs on particulate matters and sediments in Kuchibuto (Fukushima) and Pripyat (Chernobyl) Rivers, though RCs level in water was much smaller than WHO guideline. Moreover, Cs speciation and organic matter-clay mineral interaction were studied: (i) extended X-ray absorption fine structure showed that the contribution of outer-sphere complex of Cs on particulate matters is larger in Chernobyl than in Fukushima and (ii) scanning transmission X-ray microscope revealed larger association of humic substances and clay minerals in Chernobyl partly due to high [Ca 2+ ] in the Pripyat River. Consequently, RCs is more soluble in the Pripyat River due to weaker interaction of RCs with clay minerals caused by the inhibition effect of the adsorbed humic substances. In contrast, particulate matters and sediments in the Kuchibuto River display high adsorption affinity with lesser inhibition effect of adsorbed humic substances. This difference is possibly governed by the geology and soil type of provenances surrounding both catchments (Fukushima: weathered granite; Chernobyl: peat wetland and carbonate platform) which leads to high concentrations of organic matter and Ca 2+ in the Pripyat River.

Dissimilatory Fe(III) and Mn(IV) reduction.

PubMed Central

Lovley, D R

1991-01-01

The oxidation of organic matter coupled to the reduction of Fe(III) or Mn(IV) is one of the most important biogeochemical reactions in aquatic sediments, soils, and groundwater. This process, which may have been the first globally significant mechanism for the oxidation of organic matter to carbon dioxide, plays an important role in the oxidation of natural and contaminant organic compounds in a variety of environments and contributes to other phenomena of widespread significance such as the release of metals and nutrients into water supplies, the magnetization of sediments, and the corrosion of metal. Until recently, much of the Fe(III) and Mn(IV) reduction in sedimentary environments was considered to be the result of nonenzymatic processes. However, microorganisms which can effectively couple the oxidation of organic compounds to the reduction of Fe(III) or Mn(IV) have recently been discovered. With Fe(III) or Mn(IV) as the sole electron acceptor, these organisms can completely oxidize fatty acids, hydrogen, or a variety of monoaromatic compounds. This metabolism provides energy to support growth. Sugars and amino acids can be completely oxidized by the cooperative activity of fermentative microorganisms and hydrogen- and fatty-acid-oxidizing Fe(III) and Mn(IV) reducers. This provides a microbial mechanism for the oxidation of the complex assemblage of sedimentary organic matter in Fe(III)- or Mn(IV)-reducing environments. The available evidence indicates that this enzymatic reduction of Fe(III) or Mn(IV) accounts for most of the oxidation of organic matter coupled to reduction of Fe(III) and Mn(IV) in sedimentary environments. Little is known about the diversity and ecology of the microorganisms responsible for Fe(III) and Mn(IV) reduction, and only preliminary studies have been conducted on the physiology and biochemistry of this process. PMID:1886521

Pedogenic formation of montmorillonite from a 2:1-2:2 intergrade clay mineral

USGS Publications Warehouse

Malcolm, R.L.; Nettleton, W.D.; McCracken, R.J.

1968-01-01

Montmorillonite was found to be the dominant clay mineral in surface horizons of certain soils of the North Carolina Coastal Plain whereas a 2:1-2:2 intergrade clay mineral was dominant in subjacent horizons. In all soils where this clay mineral sequence was found, the surface horizon was low in pH (below 4⋅5) and high in organic matter content. In contrast, data from studies of other soils of this region (Weed and Nelson, 1962) show that: (1) montmorillonite occurs infrequently; (2) maximum accumulation of the 2:1-2:2 intergrade normally occurs in the surface horizon and decreases with depth in the profile; (3) organic matter contents are low; and (4) pH values are only moderately acid (pH 5-6).It is theorized that the montmorillonite in the surface horizon of the soils studied originated by pedogenic weathering of the 2:1-2:2 intergrade clay mineral. The combined effects of low pH (below 4⋅5) and high organic matter content in surface horizons are believed to be the agents responsible for this mineral transformation. The protonation and solubilization (reverse of hydrolysis) of Al-polymers in the interlayer of expansible clay minerals will occur at or below pH 4⋅5 depending on the charge and steric effects of the interlayer. A low pH alone may cause this solubilization and thus mineral transformation, but in the soils studied the organic matter is believed to facilitate and accelerage the transformation. The intermediates of organic matter decomposition provide an acid environment, a source of protons, and a source of watersoluble mobile organic substances (principally fulvic acids) which have the ability to complex the solubilized aluminum and move it down the profile. This continuous removal of solubilized aluminum would provide for a favorable gradient for aluminum solubilization.The drainage class or position in a catena is believed to be less important than the chemical factors in formation of montmorillonite from 2:1-2:2 intergrade, because montmorillonite is present in all drainage classes if the surface horizon is low in pH and high in organic matter.

Effects of sediment composition on inorganic mercury partitioning, speciation and bioavailability in oxic surficial sediments.

PubMed

Zhong, Huan; Wang, Wen-Xiong

2008-01-01

Artificially prepared sediments were used to assess the effects of sediment composition on inorganic Hg partitioning, speciation and bioavailability. Organic coating in sediment greatly increased the Hg partitioning and the amount of bioavailable Hg bound with the clay and the Fe and Mn oxides, but had little effect on that bound with the quartz and calcium carbonate as a result of weaker binding of humic acids and fulvic acids. The clay content increased the concentration of Hg in the sediments but inhibited the gut juice extraction due to the strong binding of Hg-organic matter (OM) complexes. Most Hg in the sediments was complexed by OM (mainly distributed in the organo-complexed phase and the strongly complexed phase), and the Hg-OM complexes (especially Hg in the strongly complexed phase) in sediments contributed much to gut juice extraction. Redistribution of Hg-OM complexes between sediments and gut juices may occur during gut juice extraction and modify Hg bioavailability and speciation in sediments.

High-field FT-ICR-MS and aromaticity equivalent approach for structural identification of water soluble organic compounds (WSOC)

NASA Astrophysics Data System (ADS)

Harir, Mourad; Yassine, Mahmoud M.; Dabek-Zlotorzynska, Ewa; Hertkorn, Norbert; Schmitt-Kopplin, Philippe

2015-04-01

Organic aerosol (OA) makes up a large and often dominant fraction, (20 to 90%) of the submicron atmospheric particulate mass, and its effects are becoming increasingly important in determining climatic and health effects of atmospheric aerosols. Despite the abundance of OA, our understanding of the sources, formation processes and atmospheric properties of OA is limited. Atmospheric OA has both primary (directly emitted) and secondary (formed in the atmosphere from precursor gases) sources, which can be natural (e.g. vegetation) and/or anthropogenic (e.g. fossil-based vehicle exhaust or biomass burning). A significant fraction of OA contains as much as 20-70% of water soluble organic compounds (WSOC). The WSOC fraction is a very complex mixture of low volatility, polyfunctional aliphatic and aromatic compounds containing carboxyl, alcohol, carbonyl, sulfo, nitro, and other functionalities. This high degree of chemical complexity of atmospheric organics has inspired a number of sophisticated approaches that are capable of identifying and detecting a variety of different analytes in OA. Accordingly, one of the most challenging areas of atmospheric particulate matter (PM) analysis is to comprehend the molecular complexity of the OA, especially WSOC fraction, a significant component of atmospheric fine PM (PM2.5). The sources of WSOC are not well understood, especially the relative contributions of primary vs. secondary organic aerosol. Therefore, the molecular characterization of WSOC is important because it allows gaining insight into aerosol sources and underlying mechanisms of secondary organic aerosols (SOA) formation and transformation. In this abstract, molecular characterization of WSOC was achieved using high-field mass spectrometry FT-ICR-MS and aromaticity equivalent approach. Aromaticity equivalent (Xc), defined recently as a new parameter calculated from the assigned molecular formulas (complementary to the aromaticity index [1]), is introduced to improve identification and characterization of aromatic and condensed aromatic compounds in WSOC [2]. We proposed threshold values of Xc≥ 2.5000 and Xc≥ 2.7143 as ambiguous minimum criteria for the presence of aromatic structure and condensed aromatic compounds, respectively. The advantage of employing this parameter is that Xc would have a constant value for each proposed core structure regardless the degree of alkylation, and thus visual representation and structural interpretations of the spectra become advantageous for characterizing and comparing complex samples. Diesel particulate matter (DPM) and two atmospheric aerosols collected in the industrial area affected by biomass burning events were used to study the applicability of the proposed criteria for the improved identification of aromatic and condensed aromatic structures in complex mixtures in the FT-ICR mass spectra. References [1] Koch.BP, Dittmar.T. From mass to structure: an aromaticity index for high-resolution mass data of natural organic matter. Rapid Commun. Mass Spectrom. 2006, 20, 926-932 [2] Yassine.MM, Harir.M, Dabek-Zlotorzynska.E, Schmitt-Kopplin.Ph. Structural characterization of organic aerosol using Fourier transform ion cyclotron resonance mass spectrometry: Aromaticity equivalent approach. Rapid Commun. Mass Spectrom. 2014. 28. 2445-2454

Effect of Natural Organic Matter on Plutonium Sorption to Goethite

DOE PAGES

Conroy, Nathan A.; Zavarin, Mavrik; Kersting, Annie B.; ...

2016-11-21

For this research, the effect of citric acid (CA), desferrioxamine B (DFOB), fulvic acid (FA), and humic acid (HA) on plutonium (Pu) sorption to goethite was studied as a function of organic carbon concentration and pH using batch sorption experiments at 5 mg C·L –1 and 50 mg C·L –1 natural organic matter (NOM), 10 –9–10 –10 M 238Pu, and 0.1 g·L –1 goethite concentrations, at pH 3, 5, 7, and 9. Low sorption of ligands coupled with strong Pu complexation decreased Pu sorption at pH 5 and 7, relative to a ligand-free system. Conversely, CA, FA, and HA increasedmore » Pu sorption to goethite at pH 3, suggesting ternary complex formation or, in the case of humic acid, incorporation into HA aggregates. Mechanisms for ternary complex formation were characterized by Fourier transform infrared spectroscopy in the absence of Pu. CA and FA demonstrated clear surface interactions at pH 3, HA appeared unchanged suggesting HA aggregates had formed, and no DFOB interactions were observed. Plutonium sorption decreased in the presence of DFOB (relative to a ligand free system) at all pH values examined. Thus, DFOB does not appear to facilitate formation of ternary Pu-DFOB-goethite complexes. At pH 9, Pu sorption in the presence of all NOM increased relative to pH 5 and 7; speciation models attributed this to Pu(IV) hydrolysis competing with ligand complexation, increasing sorption. In conclusion, the results indicate that in simple Pu-NOM-goethite ternary batch systems, NOM will decrease Pu sorption to goethite at all but particularly low pH conditions.« less

Organic matter and salinity modify cadmium soil (phyto)availability.

PubMed

Filipović, Lana; Romić, Marija; Romić, Davor; Filipović, Vilim; Ondrašek, Gabrijel

2018-01-01

Although Cd availability depends on its total concentration in soil, it is ultimately defined by the processes which control its mobility, transformations and soil solution speciation. Cd mobility between different soil fractions can be significantly affected by certain pedovariables such as soil organic matter (SOM; over formation of metal-organic complexes) and/or soil salinity (over formation of metal-inorganic complexes). Phytoavailable Cd fraction may be described as the proportion of the available Cd in soil which is actually accessible by roots and available for plant uptake. Therefore, in a greenhouse pot experiment Cd availability was observed in the rhizosphere of faba bean exposed to different levels of SOM, NaCl salinity (50 and 100mM) and Cd contamination (5 and 10mgkg -1 ). Cd availability in soil does not linearly follow its total concentration. Still, increasing soil Cd concentration may lead to increased Cd phytoavailability if the proportion of Cd 2+ pool in soil solution is enhanced. Reduced Cd (phyto)availability by raised SOM was found, along with increased proportion of Cd-DOC complexes in soil solution. Data suggest decreased Cd soil (phyto)availability with the application of salts. NaCl salinity affected Cd speciation in soil solution by promoting the formation of CdCl n 2-n complexes. Results possibly suggest that increased Cd mobility in soil does not result in its increased availability if soil adsorption capacity for Cd has not been exceeded. Accordingly, chloro-complex possibly operated just as a Cd carrier between different soil fractions and resulted only in transfer between solid phases and not in increased (phyto)availability. Copyright © 2017 Elsevier Inc. All rights reserved.

Underestimation of phosphorus fraction change in the supernatant after phosphorus adsorption onto iron oxides and iron oxide-natural organic matter complexes.

PubMed

Yan, Jinlong; Jiang, Tao; Yao, Ying; Wang, Jun; Cai, Yuanli; Green, Nelson W; Wei, Shiqiang

2017-05-01

The phosphorus (P) fraction distribution and formation mechanism in the supernatant after P adsorption onto iron oxides and iron oxide-humic acid (HA) complexes were analyzed using the ultrafiltration method in this study. With an initial P concentration of 20mg/L (I=0.01mol/L and pH=7), it was shown that the colloid (1kDa-0.45μm) component of P accounted for 10.6%, 11.6%, 6.5%, and 4.0% of remaining total P concentration in the supernatant after P adsorption onto ferrihydrite (FH), goethite (GE), ferrihydrite-humic acid complex (FH-HA), goethite-humic acid complex (GE-HA), respectively. The <1kDa component of P was still the predominant fraction in the supernatant, and underestimated colloidal P accounted for 2.2%, 55.1%, 45.5%, and 38.7% of P adsorption onto the solid surface of FH, FH-HA, GE and GE-HA, respectively. Thus, the colloid P could not be neglected. Notably, it could be interpreted that Fe 3+ hydrolysis from the adsorbents followed by the formation of colloidal hydrous ferric oxide aggregates was the main mechanism for the formation of the colloid P in the supernatant. And colloidal adsorbent particles co-existing in the supernatant were another important reason for it. Additionally, dissolve organic matter dissolved from iron oxide-HA complexes could occupy large adsorption sites of colloidal iron causing less colloid P in the supernatant. Ultimately, we believe that the findings can provide a new way to deeply interpret the geochemical cycling of P, even when considering other contaminants such as organic pollutants, heavy metal ions, and arsenate at the sediment/soil-water interface in the real environment. Copyright © 2016. Published by Elsevier B.V.

Effect of Natural Organic Matter on Plutonium Sorption to Goethite

DOE Office of Scientific and Technical Information (OSTI.GOV)

Conroy, Nathan A.; Zavarin, Mavrik; Kersting, Annie B.

For this research, the effect of citric acid (CA), desferrioxamine B (DFOB), fulvic acid (FA), and humic acid (HA) on plutonium (Pu) sorption to goethite was studied as a function of organic carbon concentration and pH using batch sorption experiments at 5 mg C·L –1 and 50 mg C·L –1 natural organic matter (NOM), 10 –9–10 –10 M 238Pu, and 0.1 g·L –1 goethite concentrations, at pH 3, 5, 7, and 9. Low sorption of ligands coupled with strong Pu complexation decreased Pu sorption at pH 5 and 7, relative to a ligand-free system. Conversely, CA, FA, and HA increasedmore » Pu sorption to goethite at pH 3, suggesting ternary complex formation or, in the case of humic acid, incorporation into HA aggregates. Mechanisms for ternary complex formation were characterized by Fourier transform infrared spectroscopy in the absence of Pu. CA and FA demonstrated clear surface interactions at pH 3, HA appeared unchanged suggesting HA aggregates had formed, and no DFOB interactions were observed. Plutonium sorption decreased in the presence of DFOB (relative to a ligand free system) at all pH values examined. Thus, DFOB does not appear to facilitate formation of ternary Pu-DFOB-goethite complexes. At pH 9, Pu sorption in the presence of all NOM increased relative to pH 5 and 7; speciation models attributed this to Pu(IV) hydrolysis competing with ligand complexation, increasing sorption. In conclusion, the results indicate that in simple Pu-NOM-goethite ternary batch systems, NOM will decrease Pu sorption to goethite at all but particularly low pH conditions.« less

Subsumed complexity: abiogenesis as a by-product of complex energy transduction.

PubMed

Adam, Z R; Zubarev, D; Aono, M; Cleaves, H James

2017-12-28

The origins of life bring into stark relief the inadequacy of our current synthesis of thermodynamic, chemical, physical and information theory to predict the conditions under which complex, living states of organic matter can arise. Origins research has traditionally proceeded under an array of implicit or explicit guiding principles in lieu of a universal formalism for abiogenesis. Within the framework of a new guiding principle for prebiotic chemistry called subsumed complexity , organic compounds are viewed as by-products of energy transduction phenomena at different scales (subatomic, atomic, molecular and polymeric) that retain energy in the form of bonds that inhibit energy from reaching the ground state. There is evidence for an emergent level of complexity that is overlooked in most conceptualizations of abiogenesis that arises from populations of compounds formed from atomic energy input. We posit that different forms of energy input can exhibit different degrees of dissipation complexity within an identical chemical medium. By extension, the maximum capacity for organic chemical complexification across molecular and macromolecular scales subsumes, rather than emerges from, the underlying complexity of energy transduction processes that drive their production and modification.This article is part of the themed issue 'Reconceptualizing the origins of life'. © 2017 The Author(s).

Subsumed complexity: abiogenesis as a by-product of complex energy transduction

NASA Astrophysics Data System (ADS)

Adam, Z. R.; Zubarev, D.; Aono, M.; Cleaves, H. James

2017-11-01

The origins of life bring into stark relief the inadequacy of our current synthesis of thermodynamic, chemical, physical and information theory to predict the conditions under which complex, living states of organic matter can arise. Origins research has traditionally proceeded under an array of implicit or explicit guiding principles in lieu of a universal formalism for abiogenesis. Within the framework of a new guiding principle for prebiotic chemistry called subsumed complexity, organic compounds are viewed as by-products of energy transduction phenomena at different scales (subatomic, atomic, molecular and polymeric) that retain energy in the form of bonds that inhibit energy from reaching the ground state. There is evidence for an emergent level of complexity that is overlooked in most conceptualizations of abiogenesis that arises from populations of compounds formed from atomic energy input. We posit that different forms of energy input can exhibit different degrees of dissipation complexity within an identical chemical medium. By extension, the maximum capacity for organic chemical complexification across molecular and macromolecular scales subsumes, rather than emerges from, the underlying complexity of energy transduction processes that drive their production and modification. This article is part of the themed issue 'Reconceptualizing the origins of life'.

Comprehensive chemical characterization of industrial PM2.5 from steel industry activities

NASA Astrophysics Data System (ADS)

Sylvestre, Alexandre; Mizzi, Aurélie; Mathiot, Sébastien; Masson, Fanny; Jaffrezo, Jean L.; Dron, Julien; Mesbah, Boualem; Wortham, Henri; Marchand, Nicolas

2017-03-01

Industrial sources are among the least documented PM (Particulate Matter) source in terms of chemical composition, which limits our understanding of their effective impact on ambient PM concentrations. We report 4 chemical emission profiles of PM2.5 for multiple activities located in a vast metallurgical complex. Emissions profiles were calculated as the difference of species concentrations between an upwind and a downwind site normalized by the absolute PM2.5 enrichment between both sites. We characterized the PM2.5 emissions profiles of the industrial activities related to the cast iron (complex 1) and the iron ore conversion processes (complex 2), as well as 2 storage areas: a blast furnace slag area (complex 3) and an ore terminal (complex 4). PM2.5 major fractions (Organic Carbon (OC) and Elemental Carbon (EC), major ions), organic markers as well as metals/trace elements are reported for the 4 industrial complexes. Among the trace elements, iron is the most emitted for the complex 1 (146.0 mg g-1 of PM2.5), the complex 2 (70.07 mg g-1) and the complex 3 (124.4 mg g-1) followed by Al, Mn and Zn. A strong emission of Polycyclic Aromatic Hydrocarbons (PAH), representing 1.3% of the Organic Matter (OM), is observed for the iron ore transformation complex (complex 2) which merges the activities of coke and iron sinter production and the blast furnace processes. In addition to unsubstituted PAHs, sulfur containing PAHs (SPAHs) are also significantly emitted (between 0.011 and 0.068 mg g-1) by the complex 2 and could become very useful organic markers of steel industry activities. For the complexes 1 and 2 (cast iron and iron ore converters), a strong fraction of sulfate ranging from 0.284 to 0.336 g g-1) and only partially neutralized by ammonium, is observed indicating that sulfates, if not directly emitted by the industrial activity, are formed very quickly in the plume. Emission from complex 4 (Ore terminal) are characterized by high contribution of Al (125.7 mg g-1 of PM2.5) but also, in a lesser extent, of Fe, Mn, Ti and Zn. We also highlighted high contribution of calcium ranging from 0.123 to 0.558 g g-1 for all of the industrial complexes under study. Since calcium is also widely used as a proxy of the dust contributions in source apportionment studies, our results suggest that this assumption should be reexamined in environments impacted by industrial emissions.

Investigation of extractable organic compounds in deep-sea hydrothermal vent fluids along the Mid-Atlantic Ridge

NASA Astrophysics Data System (ADS)

McCollom, Thomas M.; Seewald, Jeffrey S.; German, Christopher R.

2015-05-01

The possibility that deep-sea hydrothermal vents may contain organic compounds produced by abiotic synthesis or by microbial communities living deep beneath the surface has led to numerous studies of the organic composition of vent fluids. Most of these studies have focused on methane and other light hydrocarbons, while the possible occurrence of more complex organic compounds in the fluids has remained largely unstudied. To address this issue, the presence of higher molecular weight organic compounds in deep-sea hydrothermal fluids was assessed at three sites along the Mid-Atlantic Ridge that span a range of temperatures (51 to >360 °C), fluid compositions, and host-rock lithologies (mafic to ultramafic). Samples were obtained at several sites within the Lucky Strike, Rainbow, and Lost City hydrothermal fields. Three methods were employed to extract organic compounds for analysis, including liquid:liquid extraction, cold trapping on the walls of a coil of titanium tubing, and pumping fluids through cartridges filled with solid phase extraction (SPE) sorbents. The only samples to consistently yield high amounts of extractable organic compounds were the warm (51-91 °C), highly alkaline fluids from Lost City, which contained elevated concentrations of C8, C10, and C12n-alkanoic acids and, in some cases, trithiolane, hexadecanol, squalene, and cholesterol. Collectively, the C8-C12 acids can account for about 15% of the total dissolved organic carbon in the Lost City fluids. The even-carbon-number predominance of the alkanoic acids indicates a biological origin, but it is unclear whether these compounds are derived from microbial activity occurring within the hydrothermal chimney proximal to the site of fluid discharge or are transported from deeper within the system. Hydrothermal fluids from the Lucky Strike and Rainbow fields were characterized by an overall scarcity of extractable dissolved organic compounds. Trace amounts of aromatic hydrocarbons including phenanthrenes and benzothiophene were the only compounds that could be identified as indigenous components of these fluids. Although hydrocarbons and fatty acids were observed in some samples, those compounds were likely derived from particulate matter or biomass entrained during fluid collection. In addition, extracts of some fluid samples from the Rainbow field were found to contain an unresolved complex mixture (UCM) of organic compounds. This UCM shared some characteristics with organic matter extracted from bottom seawater, suggesting that the organic matter observed in these samples might represent seawater-derived compounds that had persisted, albeit with partial alteration, during circulation through the hydrothermal system. While there is considerable evidence that Rainbow and Lost City vent fluids contain methane and other light hydrocarbons produced through abiotic reduction of inorganic carbon, we found no evidence for more complex organic compounds with an abiotic origin in the same fluids.

DETERMINATION OF THE MERCURY COMPLEXATION CHARACTERISTICS OF DISSOLVED ORGANIC MATTER IN NATURAL WATERS WITH "REDUCIBLE HG" TITRATIONS. (R827635)

EPA Science Inventory

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

Limitations and potential of spectral subtractions in fourier-transform infrared (FTIR) spectroscopy of soil samples

USDA-ARS?s Scientific Manuscript database

Soil science research is increasingly applying Fourier transform infrared (FTIR) spectroscopy for analysis of soil organic matter (SOM). However, the compositional complexity of soils and the dominance of the mineral component can limit spectroscopic resolution of SOM and other minor components. The...

Laboratory simulated hydrothermal alteration of sedimentary organic matter from Guaymas Basin, Gulf of California. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Leif, Roald N.

1993-01-01

High temperature alteration of sedimentary organic matter associated with marine hydrothermal systems involves complex physical and chemical processes that are not easily measured in most natural systems. Many of these processes can be evaluated indirectly by examining the geochemistry of the hydrothermal system in the laboratory. In this investigation, an experimental organic geochemical approach to studying pyrolysis of sedimentary organic matter is applied to the hydrothermal system in the Guaymas Basin, Gulf of California. A general survey of hydrothermal oils and extractable organic matter (bitumen) in hydrothermally altered sediments identified several homologous series of alkanones associated with a high temperature hydrothermal origin. The alkanones range in carbon number from C11 to C30 with no carbon number preference. Alkan-2-ones are in highest concentrations, with lower amounts of 3-, 4-, 5- (and higher) homologs. The alkanones appear to be pyrolysis products synthesized under extreme hydrothermal conditions. Hydrous pyrolysis and confinement pyrolysis experiments were performed to simulate thermally enhanced diagenetic and catagenetic changes in the immature sedimentary organic matter. The extent of alteration was measured by monitoring the n-alkanes, acyclic isoprenoids, steroid and triterpenoid biomarkers, polycyclic aromatic hydrocarbons and alkanones. The results were compared to bitumen extracts from sediments which have been naturally altered by a sill intrusion and accompanied hydrothermal fluid flow. These pyrolysis experiments duplicated many of the organic matter transformations observed in the natural system. Full hopane and sterane maturation occurred after 48 hr in experiments at 330 deg C with low water/rock mass ratios (0.29). A variety of radical and ionic reactions are responsible for the organic compound conversions which occur under extreme hydrothermal conditions. Short duration pyrolysis experiments revealed that a portion of the hydrocarbons generated from kerogen was observed to go through alkene intermediates, and the rate of alkene isomerization was influenced by the ionic strength and catalytic mineral phases. Confinement of the organic pyrolysate to the bulk sediment accelerated the rates of the biomarker epimerization reactions, suggesting that these reactions are influenced strongly by the association of the inorganic matrix, and that the relative rates of some ionic and radical reactions can be influenced by the water/rock ratio during the pyrolysis experiments.

Impact of natural organic matter coatings on the microbial reduction of iron oxides

NASA Astrophysics Data System (ADS)

Poggenburg, Christine; Mikutta, Robert; Schippers, Axel; Dohrmann, Reiner; Guggenberger, Georg

2018-03-01

Iron (Fe) oxyhydroxides are important constituents of the soil mineral phase known to stabilize organic matter (OM) under oxic conditions. In an anoxic milieu, however, these Fe-organic associations are exposed to microbial reduction, releasing OM into soil solution. At present, only few studies have addressed the influence of adsorbed natural OM (NOM) on the reductive dissolution of Fe oxyhydroxides. This study therefore examined the impact of both the composition and concentration of adsorbed NOM on microbial Fe reduction with regard to (i) electron shuttling, (ii) complexation of Fe(II,III), (iii) surface site coverage and/or pore blockage, and (iv) aggregation. Adsorption complexes with varying carbon loadings were synthesized using different Fe oxyhydroxides (ferrihydrite, lepidocrocite, goethite, hematite, magnetite) and NOM of different origin (extracellular polymeric substances from Bacillus subtilis, OM extracted from soil Oi and Oa horizons). The adsorption complexes were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), N2 gas adsorption, electrophoretic mobility and particle size measurements, and OM desorption. Incubation experiments under anaerobic conditions were conducted for 16 days comparing two different strains of dissimilatory Fe(III)-reducing bacteria (Shewanella putrefaciens, Geobacter metallireducens). Mineral transformation during reduction was assessed via XRD and FTIR. Microbial reduction of the pure Fe oxyhydroxides was controlled by the specific surface area (SSA) and solubility of the minerals. For Shewanella putrefaciens, the Fe reduction of adsorption complexes strongly correlated with the concentration of potentially usable electron-shuttling molecules for NOM concentrations <2 mg C L-1, whereas for Geobacter metallireducens, Fe reduction depended on the particle size and thus aggregation of the adsorption complexes. These diverging results suggest that the influence of NOM on the stability of Fe-organic associations in soils cannot easily be assessed without considering the composition of the microbial soil community.

Biochar contribution to soil pH buffer capacity

NASA Astrophysics Data System (ADS)

Tonutare, Tonu; Krebstein, Kadri; Utso, Maarius; Rodima, Ako; Kolli, Raimo; Shanskiy, Merrit

2014-05-01

Biochar as ecologically clean and stable form of carbon has complex of physical and chemical properties which make it a potentially powerful soil amendment (Mutezo, 2013). Therefore during the last decade the biochar application as soil amendment has been a matter for a great number of investigations. For the ecological viewpoint the trend of decreasing of soil organic matter in European agricultural land is a major problem. Society is faced with the task to find possibilities to stabilize or increase soil organic matter content in soil and quality. The availability of different functional groups (e.g. carboxylic, phenolic, acidic, alcoholic, amine, amide) allows soil organic matter to buffer over a wide range of soil pH values (Krull et al. 2004). Therefore the loss of soil organic matter also reduces cation exchange capacity resulting in lower nutrient retention (Kimetu et al. 2008). Biochar can retain elements in soil directly through the negative charge that develops on its surfaces, and this negative charge can buffer acidity in the soil. There are lack of investigations about the effect of biochar to soil pH buffering properties, The aim of our investigation was to investigate the changes in soil pH buffer capacity in a result of addition of carbonizated material to temperate region soils. In the experiment different kind of softwood biochars, activated carbon and different soil types with various organic matter and pH were used. The study soils were Albeluvisols, Leptosols, Cambisols, Regosols and Histosols . In the experiment the series of the soil: biochar mixtures with the biochar content 0 to 100% were used. The times of equiliberation between solid and liquid phase were from 1 to 168 hours. The suspension of soil: biochar mixtures was titrated with HCl solution. The titration curves were established and pH buffer capacities were calculated for the pH interval from 3.0 to 10.0. The results demonstrate the dependence of pH buffer capacity from soil type, organic matter and type of added carbonizated material. Our study showed that the biochar content has significant role in total pH buffer capacity in soil:biochar system . References. Kimetu, J.M., Lehmann, J., Ngoze, S.O., Mugendi, D.N., Kinyangi, J., Riha, S.J., Verchot, L., Recha, J.W., Pell, A.N. 2008. Reversibility of Soil Productivity Decline with Organic Matter of Differing Quality Along a Degradation Gradient. Ecosystems, 11, 726-739. Krull, E. S., Skjemstad, J.O., Baldock, J.A. 2004 'Functions of Soil Organic Matter and the Effect on Soil Properties'. GRDC report. Project CSO 00029. Mutezo, W.T., 2013. Early crop growth and yield responses of maize (Zea mays) to biochar applied on soil. International Working Paper Series, 13/03, 50 pp.

Spatial arrangement of organic compounds on a model mineral surface: implications for soil organic matter stabilization.

PubMed

Petridis, Loukas; Ambaye, Haile; Jagadamma, Sindhu; Kilbey, S Michael; Lokitz, Bradley S; Lauter, Valeria; Mayes, Melanie A

2014-01-01

The complexity of the mineral-organic carbon interface may influence the extent of stabilization of organic carbon compounds in soils, which is important for global climate futures. The nanoscale structure of a model interface was examined here by depositing films of organic carbon compounds of contrasting chemical character, hydrophilic glucose and amphiphilic stearic acid, onto a soil mineral analogue (Al2O3). Neutron reflectometry, a technique which provides depth-sensitive insight into the organization of the thin films, indicates that glucose molecules reside in a layer between Al2O3 and stearic acid, a result that was verified by water contact angle measurements. Molecular dynamics simulations reveal the thermodynamic driving force behind glucose partitioning on the mineral interface: The entropic penalty of confining the less mobile glucose on the mineral surface is lower than for stearic acid. The fundamental information obtained here helps rationalize how complex arrangements of organic carbon on soil mineral surfaces may arise.

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

USGS Publications Warehouse

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

1992-01-01

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

Self-Organization of Metal Nanoparticles in Light: Electrodynamics-Molecular Dynamics Simulations and Optical Binding Experiments.

PubMed

McCormack, Patrick; Han, Fei; Yan, Zijie

2018-02-01

Light-driven self-organization of metal nanoparticles (NPs) can lead to unique optical matter systems, yet simulation of such self-organization (i.e., optical binding) is a complex computational problem that increases nonlinearly with system size. Here we show that a combined electrodynamics-molecular dynamics simulation technique can simulate the trajectories and predict stable configurations of silver NPs in optical fields. The simulated dynamic equilibrium of a two-NP system matches the probability density of oscillations for two optically bound NPs obtained experimentally. The predicted stable configurations for up to eight NPs are further compared to experimental observations of silver NP clusters formed by optical binding in a Bessel beam. All configurations are confirmed to form in real systems, including pentagonal clusters with five-fold symmetry. Our combined simulations and experiments have revealed a diverse optical matter system formed by anisotropic optical binding interactions, providing a new strategy to discover artificial materials.

Antarctic snow: metals bound to high molecular weight dissolved organic matter.

PubMed

Calace, Nicoletta; Nardi, Elisa; Pietroletti, Marco; Bartolucci, Eugenia; Pietrantonio, Massimiliana; Cremisini, Carlo

2017-05-01

In this paper we studied some heavy metals (Cu, Zn, Cd, Pb, As, U) probably associated to high molecular weight organic compounds present in the Antarctic snow. Snow-pit samples were collected and analysed for high molecular weight fraction and heavy metals bound to them by means of ultrafiltration treatment. High molecular weight dissolved organic matter (HMW-DOM) recovered by ultrafiltration showed a dissolved organic carbon concentration (HMW-DOC) of about 18-83% of the total dissolved organic carbon measured in Antarctic snow. The characterisation of HMW-DOM fraction evidenced an ageing of organic compounds going from surface layers to the deepest ones with a shift from aliphatic compounds and proteins/amino sugars to more high unsaturated character and less nitrogen content. The heavy metals associated to HMW-DOM fraction follows the order: Zn > Cu > Pb > Cd ∼ As ∼ U. The percentage fraction of metals bound to HMW-DOM respect to total metal content follows the order: Cu > Pb > Zn, Cd in agreement with humic substance binding ability (Irwing-William series). Going down to depth of trench, all metals except arsenic, showed a high concentration peak corresponding to 2.0-2.5 m layer. This result was attributed to particular structural characteristic of organic matter able to form different type of complexes (1:1, 1:2, 1:n) with metals. Copyright © 2017 Elsevier Ltd. All rights reserved.

Search for biochemical fossils on earth and non-biological organic molecules on Jupiter, Saturn and Titan

NASA Astrophysics Data System (ADS)

Nagy, Bartholomew

1982-07-01

Recognizable remnants of ancient biochemicals may survive under mild/moderate geological environments. Acyclic isoprenoid hydrocarbons, cyclic hydrocarbons with terpenoid carbon skeletons (e.g. hopanes) and vanadyl and nickel porphyrins have been isolated from organic matter, including petroleum, in Phanerozoic sedimentary rocks. Remnants of lignin have also been found. Usually, carbohydrates do not survive long; they degrade and/or react with other organic substances to form macromolecular matter. Proteins, e.g. apparently those in dinosaur bone collagen, break down relatively rapidly. Life arose during the Precambrian and potential biochemical fossils, e.g. n-alkanes, 2,5-dimethylfuran have been isolated from Precambrian kerogens. Traces of hydrocarbons, NH3, PH3 occur on Jupiter and Saturn. Hydrocarbons, N2 and HCN, the latter a key intermediary in the laboratory abiological syntheses of amino acids and nucleic acid bases, are present on Titan where life could not have evolved. Precursor abiological organic molecules of some complexity may have been synthesized on Titan and the Jovian planets.

Previously unknown class of metalorganic compounds revealed in meteorites

PubMed Central

Ruf, Alexander; Kanawati, Basem; Hertkorn, Norbert; Yin, Qing-Zhu; Moritz, Franco; Harir, Mourad; Lucio, Marianna; Michalke, Bernhard; Wimpenny, Joshua; Shilobreeva, Svetlana; Bronsky, Basil; Saraykin, Vladimir; Gabelica, Zelimir; Gougeon, Régis D.; Quirico, Eric; Ralew, Stefan; Jakubowski, Tomasz; Haack, Henning; Gonsior, Michael; Jenniskens, Peter; Hinman, Nancy W.; Schmitt-Kopplin, Philippe

2017-01-01

The rich diversity and complexity of organic matter found in meteorites is rapidly expanding our knowledge and understanding of extreme environments from which the early solar system emerged and evolved. Here, we report the discovery of a hitherto unknown chemical class, dihydroxymagnesium carboxylates [(OH)2MgO2CR]−, in meteoritic soluble organic matter. High collision energies, which are required for fragmentation, suggest substantial thermal stability of these Mg-metalorganics (CHOMg compounds). This was corroborated by their higher abundance in thermally processed meteorites. CHOMg compounds were found to be present in a set of 61 meteorites of diverse petrological classes. The appearance of this CHOMg chemical class extends the previously investigated, diverse set of CHNOS molecules. A connection between the evolution of organic compounds and minerals is made, as Mg released from minerals gets trapped into organic compounds. These CHOMg metalorganic compounds and their relation to thermal processing in meteorites might shed new light on our understanding of carbon speciation at a molecular level in meteorite parent bodies. PMID:28242686

Spectral Exploration of Calcium Accumulation in Organic Matter in Gray Desert Soil from Northwest China

PubMed Central

Wang, Ping; Ma, Yucui; Wang, Xihe; Jiang, Hong; Liu, Hua; Ran, Wei; Shen, Qirong

2016-01-01

Little attention has been paid to the accumulation of soil organic matter (SOM) in the fringes of the mid-latitude desert. In this paper, soil samples from a long-term field experiment conducted from 1990 to 2013 at a research station in Urumqi, China by different fertilizer treatments, were used to determine soil properties and soil dissolved organic matter (DOM) by chemical analysis, fluorescence excitation emission matrix (EEM) spectroscopy, and high resolution-transmission electron microscopy (HR-TEM). The binding features of DOM under the addition of Ca2+ were analyzed using a two-dimensional (2D) Fourier transform infrared (FTIR) spectrometer further to explore the response of the DOM to increasing concentrations of Ca2+. Long-term application of chemical fertilizers and goat manure increased soil organic carbon (SOC) by 1.34- and 1.86-fold, respectively, relative to the non-fertilized control (8.95g.kg-1). Compared with the control, application of chemical fertilizers and manure significantly increased the concentrations of Ca, Mg, Si, humic and fulvic acid-like substances in DOM but decreased the amounts of trivalent metals (Al and Fe) and protein-like substances. Although crystalline Al/Fe nanoparticles and amorphous or short-range-order Si/Al nanoparticles existed in all DOM samples, crystalline Ca/Si nanoparticles were predominant in the samples treated with goat manure. Although organic matter and Si-O-containing nanoparticles were involved in the binding of Ca2+ to DOM, application of chemical fertilizers weakened Ca2+ association with components of the amide II group (1510 cm-1) and Si-O linkage (1080 cm-1), whereas application of goat manure enhanced the affinity of Ca2+ for Si-O linkage. Our results suggested that the enrichment of Ca in gray desert soil possibly helps accumulate SOM by forming crystalline Ca/Si nanoparticles in addition to Ca2+ and organic matter complexes. PMID:26751962

Spectral Exploration of Calcium Accumulation in Organic Matter in Gray Desert Soil from Northwest China.

PubMed

Wang, Ping; Ma, Yucui; Wang, Xihe; Jiang, Hong; Liu, Hua; Ran, Wei; Shen, Qirong

2016-01-01

Little attention has been paid to the accumulation of soil organic matter (SOM) in the fringes of the mid-latitude desert. In this paper, soil samples from a long-term field experiment conducted from 1990 to 2013 at a research station in Urumqi, China by different fertilizer treatments, were used to determine soil properties and soil dissolved organic matter (DOM) by chemical analysis, fluorescence excitation emission matrix (EEM) spectroscopy, and high resolution-transmission electron microscopy (HR-TEM). The binding features of DOM under the addition of Ca(2+) were analyzed using a two-dimensional (2D) Fourier transform infrared (FTIR) spectrometer further to explore the response of the DOM to increasing concentrations of Ca(2+). Long-term application of chemical fertilizers and goat manure increased soil organic carbon (SOC) by 1.34- and 1.86-fold, respectively, relative to the non-fertilized control (8.95 g.kg(-1)). Compared with the control, application of chemical fertilizers and manure significantly increased the concentrations of Ca, Mg, Si, humic and fulvic acid-like substances in DOM but decreased the amounts of trivalent metals (Al and Fe) and protein-like substances. Although crystalline Al/Fe nanoparticles and amorphous or short-range-order Si/Al nanoparticles existed in all DOM samples, crystalline Ca/Si nanoparticles were predominant in the samples treated with goat manure. Although organic matter and Si-O-containing nanoparticles were involved in the binding of Ca(2+) to DOM, application of chemical fertilizers weakened Ca(2+) association with components of the amide II group (1510 cm(-1)) and Si-O linkage (1080 cm(-1)), whereas application of goat manure enhanced the affinity of Ca(2+) for Si-O linkage. Our results suggested that the enrichment of Ca in gray desert soil possibly helps accumulate SOM by forming crystalline Ca/Si nanoparticles in addition to Ca(2+) and organic matter complexes.

Effects of molecular weight of natural organic matter on cadmium mobility in soil environments and its carbon isotope characteristics.

PubMed

Mahara, Y; Kubota, T; Wakayama, R; Nakano-Ohta, T; Nakamura, T

2007-11-15

We investigated the role of natural organic matter in cadmium mobility in soil environments. We collected the dissolved organic matter from two different types of natural waters: pond surface water, which is oxic, and deep anoxic groundwater. The collected organic matter was fractionated into four groups with molecular weights (unit: Da (Daltons)) of <1 x 10(3), 1-10 x 10(3), 10-100 x 10(3), and >100 x 10(3). The organic matter source was land plants, based on the carbon isotope ratios (delta(13)C/(12)C). The organic matter in surface water originated from presently growing land plants, based on (14)C dating, but the organic matter in deep groundwater originated from land plants that grew approximately 4000 years ago. However, some carbon was supplied by the high-molecular-weight fraction of humic substances in soil or sediments. Cadmium interacted in a system of siliceous sand, fractionated organic matter, and water. The lowest molecular weight fraction of organic matter (<1 x 10(3)) bound more cadmium than did the higher molecular weight fractions. Organic matter in deep groundwater was more strongly bound to cadmium than was organic matter in surface water. The binding behaviours of organic matter with cadmium depended on concentration, age, molecular weight, and degradation conditions of the organic matter in natural waters. Consequently, the dissolved, low-molecular-weight fraction in organic matter strongly influences cadmium migration and mobility in the environment.

Modeling fluid diffusion in cerebral white matter with random walks in complex environments

NASA Astrophysics Data System (ADS)

Levy, Amichai; Cwilich, Gabriel; Buldyrev, Sergey V.; Weeden, Van J.

2012-02-01

Recent studies with diffusion MRI have shown new aspects of geometric order in the brain, including complex path coherence within the cerebral cortex, and organization of cerebral white matter and connectivity across multiple scales. The main assumption of these studies is that water molecules diffuse along myelin sheaths of neuron axons in the white matter and thus the anisotropy of their diffusion tensor observed by MRI can provide information about the direction of the axons connecting different parts of the brain. We model the diffusion of particles confined in the space of between the bundles of cylindrical obstacles representing fibrous structures of various orientations. We have investigated the directional properties of the diffusion, by studying the angular distribution of the end point of the random walks as a function of their length, to understand the scale over which the distribution randomizes. We will show evidence of qualitative change in the behavior of the diffusion for different volume fractions of obstacles. Comparisons with three-dimensional MRI images will be illustrated.

Methylmercury photodegradation in surface water of the Florida Everglades: importance of dissolved organic matter-methylmercury complexation.

PubMed

Tai, Chao; Li, Yanbin; Yin, Yongguang; Scinto, Leonard J; Jiang, Guibin; Cai, Yong

2014-07-01

Photodegradation is the major pathway of methylmercury (MeHg) degradation in many surface waters. However, the mechanism of MeHg photodegradation is still not completely understood. Dissolved organic matter (DOM) is expected to play a critical role in MeHg photodegradation. By using several techniques, including N2/O2 purging and the addition of stable isotope (Me(201)Hg), scavengers, competing ligands, and a singlet oxygen ((1)O2) generator, the role played by MeHg-DOM complexation in MeHg photodegradation of Everglades surface water was investigated. DOM appeared to be involved in MeHg photodegradation via the formation MeHg-DOM complexes based on three findings: (1) MeHg was quickly photodegraded in solutions containing DOM extracts; (2) degradation of MeHg did not occur in deionized water; and (3) addition of competing complexation reagents (dithiothreitol-DTT) dramatically prohibited the photodegradation of MeHg in Everglades water. Further experiments indicated that free radicals/reactive oxygen species, including hydroxyl radical (·OH), (1)O2, triplet excited state of DOM ((3)DOM*), and hydrated electron (e(-)aq), played a minor role in MeHg photodegradation in Everglades water, based on the results of scavenger addition, (1)O2 generator addition and N2/O2 purging. A pathway, involving direct photodegradation of MeHg-DOM complexes via intramolecular electron transfer, is proposed as the dominant mechanism for MeHg photodegradation in Everglades water.

Ultraviolet-B radiation mobilizes uranium from uranium-dissolved organic carbon complexes in aquatic systems, demonstrated by asymmetrical flow field-flow fractionation.

PubMed

Nehete, Sachin Vilas; Christensen, Terje; Salbu, Brit; Teien, Hans-Christian

2017-05-05

Humic substances have a tendency to form complexes with metal ions in aquatic medium, impacting the metal mobility, decreasing bioavailability and toxicity. Ultraviolet-B (UV-B) radiation exposure degrades the humic substance, changes their molecular weight distribution and their metal binding capacity in aquatic medium. In this study, we experimented the effect of UV-B radiation on the uranium complexed with fulvic acids and humic acids in a soft water system at different pH, uranium concentrations and radiant exposure. The concentration and distribution of uranium in a complexed form were investigated by asymmetrical flow field-flow fractionation coupled to multi detection technique (AsFlFFF-UV-ICP-MS). The major concentration of uranium present in complexes was primarily associated with average and higher molecular weight fulvic and humic acids components. The concentration of uranium in a complexed form increased with increasing fulvic and humic acid concentrations as well as pH of the solution. The higher molecular weight fraction of uranium was degraded due to the UV-B exposure, transforming about 50% of the uranium-dissolved organic carbon complexes into low molecular weight uranium species in complex form with organic ligands and/or free form. The result also suggests AsFlFFF-UV-ICP-MS to be an important separation and detection technique for understanding the interaction of radionuclides with dissolved organic matter, tracking size distribution changes during degradation of organic complexes for understanding mobility, bioavailability and ecosystem transfer of radionuclides as well as metals. Copyright © 2017 Elsevier B.V. All rights reserved.

Predicting the response of soil organic matter microbial decomposition to moisture

NASA Astrophysics Data System (ADS)

Chenu, Claire; Garnier, Patricia; Monga, Olivier; Moyano, Fernando; Pot, Valérie; Nunan, Naoise; Coucheney, Elsa; Otten, Wilfred

2014-05-01

Next to temperature, soil moisture is a main driver of soil C and N transformations in soils, because it affects microbial activity and survival. The moisture sensitivity of soil organic matter decay may be a source of uncertainty of similar magnitude to that of the temperature sensitivity and receives much less attention. The basic concepts and mechanisms relating soil water to microorganisms were identified early (i.e. in steady state conditions : direct effects on microbial physiology, diffusion substrates, nutrients, extracellular enzymes, diffusion of oxygen, movement of microorganisms). However, accounting for how moisture controls soil microbial activity remains essentially empirical and poorly accounts for soil characteristics. Soil microorganisms live in a complex 3-D framework of mineral and organic particles defining pores of various sizes, connections with adjacent pores, and with pore walls of contrasted nature, which result in a variety of microhabitats. The water regime to which microorganisms are exposed can be predicted to depend the size and connectivity of pores in which they are located. Furthermore, the spatial distribution of microorganisms as well as that of organic matter is very heterogeneous, determining the diffusion distances between substrates and decomposers. A new generation of pore scale models of C dynamics in soil may challenge the difficulty of modelling such a complex system. These models are based on an explicit representation of soil structure (i.e. soil particles and voids), microorganisms and organic matter localisation. We tested here the ability of such a model to account for changes in microbial respiration with soil moisture. In the model MOSAIC II, soil pore space is described using a sphere network coming from a geometrical modelling algorithm. MicroCT tomography images were used to implement this representation of soil structure. A biological sub-model describes the hydrolysis of insoluble SOM into dissolved organic matter, its assimilation, respiration and microbial mortality. A recent improvement of the model was the description of the diffusion of soluble organic matter. We tested the model using the results from an experiment where a simple substrate (fructose) was decomposed by bacteria within a simple media (sand). Separate incubations in microcosms were carried out using five different bacterial communities at two different moisture conditions corresponding to water potentials of -0.01 and -0.1 bars. We calibrated the biological parameters using the experimental data obtained at high water content and we tested the model without any parameters change at low water content. Both the experiments and simulations showed a decrease in mineralisation with a decrease of water content, of which pattern depended on the bacterial species and its physiological characteristics. The model was able to correctly simulate the decrease of connectivity between substrate and microorganism due the decrease of water content. The potential and required developments of such models in describing how heterotrophic respiration is affected by micro-scale distribution and processes in soils and in testing scenarios regarding water regimes in a changing climate is discussed.

Using atmospheric fallout to date organic horizon layers and quantify metal dynamics during decomposition

NASA Astrophysics Data System (ADS)

Kaste, James M.; Bostick, Benjamin C.; Heimsath, Arjun M.; Steinnes, Eiliv; Friedland, Andrew J.

2011-03-01

High concentrations of metals in organic matter can inhibit decomposition and limit nutrient availability in ecosystems, but the long-term fate of metals bound to forest litter is poorly understood. Controlled experiments indicate that during the first few years of litter decay, Al, Fe, Pb, and other metals that form stable complexes with organic matter are naturally enriched by several hundred percent as carbon is oxidized. The transformation of fresh litter to humus takes decades, however, such that current datasets describing the accumulation and release of metals in decomposing organic matter are timescale limited. Here we use atmospheric 210Pb to quantify the fate of metals in canopy-derived litter during burial and decay in coniferous forests in New England and Norway where decomposition rates are slow and physical soil mixing is minimal. We measure 210Pb inventories in the O horizon and mineral soil and calculate a 60-630 year timescale for the production of mobile organo-metallic colloids from the decomposition of fresh forest detritus. This production rate is slowest at our highest elevation (˜1000 m) and highest latitude sites (>63°N) where decomposition rates are expected to be low. We calculate soil layer ages by assuming a constant supply of atmospheric 210Pb and find that they are consistent with the distribution of geochemical tracers from weapons fallout, air pollution, and a direct 207Pb application at one site. By quantifying a gradient of organic matter ages with depth in the O horizon, we describe the accumulation and loss of metals in the soil profile as organic matter transforms from fresh litter to humus. While decomposition experiments predict that Al and Fe concentrations increase during the initial few years of decay, we show here that these metals continue to accumulate in humus for decades, and that enrichment occurs at a rate higher than can be explained by quantitative retention during decomposition alone. Acid extractable Al and Fe concentrations are higher in the humus layer of the O horizon than in the mineral soil immediately beneath this layer: it is therefore unlikely that physical soil mixing introduces significant Al and Fe to humus. This continuous enrichment of Al and Fe over time may best be explained by the recent suggestion that metals are mined from deeper horizons and brought into the O horizon via mycorrhizal plants. In sharp contrast to Al and Fe, we find that Mn concentrations in decomposing litter layers decrease exponentially with age, presumably because of leaching or rapid uptake, which may explain the low levels of acid extractable Mn in the mineral soil. This study quantifies how metals are enriched and lost in decomposing organic matter over a longer timescale than previous studies have been able to characterize. We also put new limits on the rate at which metals in litter become mobile organo-metallic complexes that can migrate to deeper soil horizons or surface waters.

Biodegradability of algal-derived organic matter in a large artificial lake by using stable isotope tracers.

PubMed

Lee, Yeonjung; Lee, Bomi; Hur, Jin; Min, Jun-Oh; Ha, Sun-Yong; Ra, Kongtae; Kim, Kyung-Tae; Shin, Kyung-Hoon

2016-05-01

In order to understand the biodegradability of algal-derived organic matter, biodegradation experiments were conducted with (13)C and (15)N-labeled natural phytoplankton and periphytic algal populations in experimental conditions for 60 days. Qualitative changes in the dissolved organic matter were also determined using parallel factor analysis and the stable carbon isotopic composition of the hydrophobic dissolved organic matter through the experimental period. Although algal-derived organic matter is considered to be easily biodegradable, the initial amounts of total organic carbon newly produced by phytoplankton and periphytic algae remained approximately 16 and 44 % after 60 days, respectively, and about 22 and 43 % of newly produced particulate nitrogen remained. Further, the dissolved organic carbon derived from both algal populations increased significantly after 60 days. Although the dissolved organic matter gradually became refractory, the contributions of the algal-derived organic matter to the dissolved organic matter and hydrophobic dissolved organic matter increased. Our laboratory experimental results suggest that algal-derived organic matter produced by phytoplankton and periphytic algae could contribute significantly to the non-biodegradable organic matter through microbial transformations.

Arsenic behavior in river sediments under redox gradient: a review.

PubMed

Gorny, Josselin; Billon, Gabriel; Lesven, Ludovic; Dumoulin, David; Madé, Benoît; Noiriel, Catherine

2015-02-01

The fate of arsenic - a redox sensitive metalloid - in surface sediments is closely linked to early diagenetic processes. The review presents the main redox mechanisms and final products of As that have been evidenced over the last years. Oxidation of organic matter and concomitant reduction of oxidants by bacterial activity result in redox transformations of As species. The evolution of the sediment reactivity will also induce secondary abiotic reactions like complexation/de-complexation, sorption, precipitation/dissolution and biotic reactions that could, for instance, lead to the detoxification of some As species. Overall, abiotic redox reactions that govern the speciation of As mostly involve manganese (hydr)-oxides and reduced sulfur species produced by the sulfate-reducing bacteria. Bacterial activity is also responsible for the inter-conversion between As(V) and As(III), as well as for the production of methylated arsenic species. In surficial sediments, sorption processes also control the fate of inorganic As(V), through the formation of inner sphere complexes with iron (hydr)-oxides, that are biologically reduced in buried sediment. Arsenic species can also be bound to organic matter, either directly to functional groups or indirectly through metal complexes. Finally, even if the role of reduced sulfur species in the cycling of arsenic in sediments has been evidenced, some of the transformations remain hypothetical and deserve further investigation. Copyright © 2014 Elsevier B.V. All rights reserved.

Organic matter composition of soil macropore surfaces under different agricultural management practices

NASA Astrophysics Data System (ADS)

Glæsner, Nadia; Leue, Marin; Magid, Jacob; Gerke, Horst H.

2016-04-01

Understanding the heterogeneous nature of soil, i.e. properties and processes occurring specifically at local scales is essential for best managing our soil resources for agricultural production. Examination of intact soil structures in order to obtain an increased understanding of how soil systems operate from small to large scale represents a large gap within soil science research. Dissolved chemicals, nutrients and particles are transported through the disturbed plow layer of agricultural soil, where after flow through the lower soil layers occur by preferential flow via macropores. Rapid movement of water through macropores limit the contact between the preferentially moving water and the surrounding soil matrix, therefore contact and exchange of solutes in the water is largely restricted to the surface area of the macropores. Organomineral complex coated surfaces control sorption and exchange properties of solutes, as well as availability of essential nutrients to plant roots and to the preferentially flowing water. DRIFT (Diffuse Reflectance infrared Fourier Transform) Mapping has been developed to examine composition of organic matter coated macropores. In this study macropore surfaces structures will be determined for organic matter composition using DRIFT from a long-term field experiment on waste application to agricultural soil (CRUCIAL, close to Copenhagen, Denmark). Parcels with 5 treatments; accelerated household waste, accelerated sewage sludge, accelerated cattle manure, NPK and unfertilized, will be examined in order to study whether agricultural management have an impact on the organic matter composition of intact structures.

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.

Modified Anaerobic Digestion Model No.1 for dry and semi-dry anaerobic digestion of solid organic waste.

PubMed

Liotta, Flavia; Chatellier, Patrice; Esposito, Giovanni; Fabbricino, Massimiliano; Frunzo, Luigi; van Hullebusch, Eric D; Lens, Piet N L; Pirozzi, Francesco

2015-01-01

The role of total solids (TS) content in anaerobic digestion of selected complex organic matter, e.g. rice straw and food waste, was investigated. A range of TS from wet (4.5%) to dry (23%) was evaluated. A modified version of the Anaerobic Digestion Model No.1 for a complex organic substrate is proposed to take into account the effect of the TS content on anaerobic digestion. A linear function that correlates the kinetic constants of three specific processes (i.e. disintegration, acetate and propionate up-take) was included in the model. Results of biomethanation and volatile fatty acids production tests were used to calibrate the proposed model. Model simulations showed a good agreement between numerical and observed data.

Presence of aliphatic and polycyclic aromatic hydrocarbons in near-surface sediments of an oil spill area in Bohai Sea.

PubMed

Li, Shuanglin; Zhang, Shengyin; Dong, Heping; Zhao, Qingfang; Cao, Chunhui

2015-11-15

In order to determine the source of organic matter and the fingerprint of the oil components, 50 samples collected from the near-surface sediments of the oil spill area in Bohai Sea, China, were analyzed for grain size, total organic carbon, aliphatic hydrocarbons (AHs), and polycyclic aromatic hydrocarbons (PAHs). The concentrations of C15-35 n-alkanes and 16 United States Environmental Protection Agency (US EPA) priority pollutant PAHs were found in the ranges of 0.88-3.48μg g(-1) and 9.97-490.13ng/g, respectively. The terrestrial organic matters characterized by C27-C35 n-alkanes and PAHs, resulting from the combustion of higher plants, are dominantly contributed from the transportation of these plants by rivers. Marine organic matters produced from plankton and aquatic plants were represented by C17-C26 n-alkanes in AHs. Crude oil, characterized by C17-C21 n-alkanes, unresolved complex mixture (UCM) with a mean response factor of C19 n-alkanes, low levels of perylene, and a high InP/(InP+BghiP) ratio, seeped into the oceans from deep hydrocarbon reservoirs, as a result of geological faults. Copyright © 2015 Elsevier Ltd. All rights reserved.

Characterictics and Sources of Organic Tracers in Atmospheric Particulate Matter from the Eastern Region of Saudi Arabia

NASA Astrophysics Data System (ADS)

Rushdi, A. I.; El-Mubarak, A. H.; Luis, L.; Mubarak, A. T.; Qurban, M.; Al-Mutlaq, K. F.; Simoneit, B. R.

2013-12-01

The formation and sources of atmospheric particulate matter (PM) can affect air quality of metropolitan areas as well as climate change. Their chemical components can be toxic to humans and hazardous to the environment. Saudi Arabia is witnessing new development and industrial activities, which are expected to contribute to natural, regional and anthropogenic PM inputs of organic tracers. This work investigates the characteristics and sources of the extractable organic matter (EOM) in atmospheric suspended PM from the city of Dhahran in the eastern part of Saudi Arabia. The major compounds were an unresolved complex mixture (UCM) of branched and cyclic hydrocarbons (12-70% of EOM), plasticizers (7-30% of EOM for aryl phosphates and 4-18% of EOM for phthalates), n-alkanes (3-15% of EOM), hopane biomarkers (0.1-4.2% of EOM), n-alkanones (0.3-1.7% of EOM), PAHs (0.1-0.6% of EOM), sterane biomarkers (0.0-0.1% of EOM), and sterols (0.0-0.1% of EOM). Plasticizers are evidently major compounds (11- 48% of EOM) in the suspended PM of Dhahran, which likely have serious public health effects and environmental consequences. The major sources of these organic tracers are emissions from industrial factories north of the city, plastics and biomass burning, and petroleum product combustion.

Spectroscopic characterization of the coordination chemistry and hydrolysis of gallium(III) in the presence of aquatic organic matter

NASA Astrophysics Data System (ADS)

Hagvall, Kristoffer; Persson, Per; Karlsson, Torbjörn

2014-12-01

Interactions between metals and natural organic matter (NOM) are of great environmental importance and one of the key factors influencing hydrolysis, solubility, and speciation of the metals. However, studying geochemically relevant metals like Al, Fe, and Cu is sometimes associated with analytical problems; for example Fe and Cu are both redox active. Gallium (Ga) is a non-redox active metal that usually occurs at very low concentrations in environmental samples and therefore a wide concentration range of metal(III)-NOM species can be explored by adding Ga(III) to such samples. This makes Ga(III) a good probe and analogue for other metal ions, in particular Al. In addition, due to the increased usage of Ga in society, a better understanding of how Ga interacts with NOM is of importance but such studies are scarce. In this work, Ga(III) interactions with two different organic materials (Suwannee River natural organic matter and Suwannee River fulvic acid) were studied using infrared (IR) and extended X-ray absorption fine structure (EXAFS) spectroscopy in a large experimental range (101-84,076 μg Ga g-1 dry weight; pH 3-8). Our IR spectroscopic results showed that Ga(III) is bonded mainly to carboxylic functional groups and suggested that only a fraction of the total number of carboxylic sites in the samples was actively involved in the bonding. Modeling of the EXAFS data revealed that Ga(III) formed mononuclear chelate complexes with NOM that strongly suppressed the hydrolysis and polymerization of Ga(III). At low Ga(III) concentrations (1675-16,649 μg g-1) organic complexes, consisting of 1-3 chelate ring structures, were the dominating species in the entire pH range while at higher concentrations (67,673-84,076 μg g-1, pH 3.0-7.0) we detected mixtures of mononuclear organic Ga(III) complexes, Ga(III) (hydr)oxide, and free Ga(III) (here defined as the hydrated Ga(III) ion and its soluble hydrolysis products). Moreover, the EXAFS results showed significantly higher contribution from second-shell C atoms (9-11) for the Ga(III)-organic complexes at the lowest concentration (101-125 μg g-1, pH 4.9-5.1), indicating formation of cage-like structures similar to Ga(III)-EDTA. Our combined results showed that Ga(III)-NOM interactions can be of importance for the solubility and speciation of Ga in environmental systems. Furthermore, the similarities between Ga(III) and previous Fe(III) results demonstrate that Ga(III) can be utilized as a probe for metal(III)-NOM interactions over an extended experimental range (e.g., pH and metal concentration) and thereby improve our knowledge about these interactions in general.

Inorganic and organic geochemical fingerprinting of sediment sources and ocean circulation on a complex continental margin (São Paulo Bight, Brazil)

NASA Astrophysics Data System (ADS)

Michaelovitch de Mahiques, Michel; Jörg Hanebuth, Till Jens; Hanae Nagai, Renata; Caruso Bícego, Marcia; Lopes Figueira, Rubens Cesar; Mello Sousa, Silvia Helena; Burone, Leticia; Franco-Fraguas, Paula; Taniguchi, Satie; Barbosa Salaroli, Alexandre; Pereira Dias, Gilberto; Menezes Prates, Denise; Fernandes Freitas, Maria Eugenia

2017-03-01

In this study, we use inorganic (metal) and organic (bulk and molecular) markers in sediment samples of the south-eastern Brazilian margin to investigate the response of geochemical fingerprints to the complex hydrodynamic processes present in the area. Results indicate the potential of export of terrigenous siliciclastic and organic constituents to the upper slope, even in an area with limited fluvial supply.

Metal contents and especially the ln(Ti / Al) and ln(Fe / K) ratios make it possible to recognise the extension of shelf sediments toward the upper slope. Potassium, here expressed as ln(K / Sc) and ln(K / Al) ratios used as proxies of illite-kaolinite variations, proved to be an important parameter, especially because it allowed us to decipher the imprint of the northward flow of the Intermediate Western Boundary Current (IWBC) in comparison to the southward flows of the Brazil Current (BC) and Deep Western Boundary Current (DWBC). Using organic matter analyses, we were able to evaluate the extent of terrestrial contributions to the outer shelf and slope, even without the presence of significant fluvial input. In addition, molecular markers signify a slight increase in the input of C4-derived plants to the slope sediments, transported from distant areas by the main alongshore boundary currents, indicating that the terrestrial fraction of the organic matter deposited on the slope has a distinct origin when compared to shelf sediments.

Sedimentary organic matter sources, benthic consumption and burial in west Spitsbergen fjords - Signs of maturing of Arctic fjordic systems?

NASA Astrophysics Data System (ADS)

Zaborska, Agata; Włodarska-Kowalczuk, Maria; Legeżyńska, Joanna; Jankowska, Emilia; Winogradow, Aleksandra; Deja, Kajetan

2018-04-01

Mature ecosystems sequester little organic carbon (Corg) in sediments, as the complex and effective food webs consume most available organic matter within the water column and sediment, in contrast to young systems, where a large proportion of Corg is buried in deeper sediment layers. In this paper we hypothesize that "warmer" Atlantic water influenced fjord exhibits the 'mature' system features as compared to "cooler" Arctic water influenced fjord. Corg concentrations, sources and burial rates, as well as macrobenthic community standing stocks, taxonomic and functional composition and carbon demand, were compared in two west Spitsbergen fjords that are to different extents influenced by Atlantic water and can be treated as representing a cold one (Hornsund) and a warm one (Kongsfjorden). Water, sediments and macrofauna were collected at three stations in the central basin of each fjord. Corg, Ntot, δ13Corg and δ15N were measured in suspended matter, sediment cores and possible organic matter sources. The composition of sources of sedimentary organic matter was modeled by Mix-SIAR Bayesian stable isotope mixing models. The 210Pb method was used to calculate sediment accumulation rates, Corg accumulation and burial rates. The sedimentary Corg concentration and accumulation rate were larger in Hornsund than in Kongsfjorden. The contributions of pelagic sources to the Corg in sediments were similar in both fjords, macroalgal detritus had a higher importance in Kongsfjorden, while terrestrial sources were more important in Hornsund. Similar density and species richness were noted in both fjords, but higher biomass, individual biomass, production and carbon demand of benthic communities were noted in Kongsfjorden despite the lower amounts of Corg in sediments, indicating that macrobenthos responds to quality rather than quantity of available food. Subsurface tube-building conveyer belt detritus feeders (maldanids and oweniids) were responsible for higher standing stocks and carbon consumption in Kongsfjorden. As a result of the lower Corg pool and higher benthic mineralization, the burial rates in Kongsfjorden were much lower (15 g of Corg m- 2 yr- 1) than in Hornsund (38 g of Corg m- 2 yr- 1). Our study indicates that warming of the high latitude fjordic environments may reshape the relative proportions of organic carbon sources and induce maturing of the sea bottom systems, in terms of development of stable, biologically accommodated benthic communities which more efficiently mineralize organic matter and consequently lower sequestration of organic matter in deeper sediments.

Tracers and constituents indicating the nature of organic fluxes, their origin and the effect of environmental conditions

NASA Astrophysics Data System (ADS)

Gadel, F.; Puigbó, A.; Alcan˜iz, J. M.; Charrière, B.; Serve, L.

1990-09-01

The nature of particulate organic matter was studied in suspended material sampled by bottles, particles collected by sediment traps and deposits from deltaic and open sea ecosystems of the northwestern Mediterranean. Elemental analyses were combined with pyrolysis-gas chromatography-mass spectrometry and with analysis of individual compounds such as phenols separated by high-performance liquid chromatography. In the Rhoˆne delta, a multilayered system was observed. The surficial turbid layer was enriched with fresh material of river origin. Organic matter was more altered and richer in phenols in the bottom nepheloid layer. The river regime determined the nature and quantity of suspended material: when in spate, degraded organic matter previously deposited in the river bed was transported to the sea, thereby inducing an increase of pyrolysis derived aromatic hydrocarbons. On the other hand, phenolic aldehydes increased in the bottom nepheloid layer. When water level was low, organic matter seemed to be of more local origin. The content of phenols and nitrogen-containing compounds increased. The influence of the Rhoˆne River decreased off the mouth, when terrestrial markers were diluted by products deriving from phytoplanktonic activity. Compared with suspended material, trapped organic matter was coarser, more degraded and contained more aromatic hydrocarbons. It was different in nature and size, indicating that it was trapped over a longer period. Deposits contained altered organic matter resulting from degrading processes in the water column. Sediments showed a double trend off the mouth of the river; an increase in nitrogen-containing compounds, indicating a more marine character, and a decrease in phenols and carbohydrates deriving from the terrestrial ligno-cellulosic complex. In the southwestern part of the Gulf of Lions, in the Teˆt prodelta, organic matter from sediment traps was fresher than in the Rhoˆne delta. Phenols and some carbohydrates rapidly decreased from the prodelta due to a lower runoff. During the spate, suspended material was rapidly deposited and sediments were enriched in terrestrial phenols. In the open sea environment, in the Lacaze-Duthiers Canyon at 645 m, in summer, the euphotic zone was rich in amino-sugars and contained a large diversity of phenols deriving from fish fecal pellets. In winter/spring, the development of phytoplanktonic blooms in surficial layers led to high contents of nitrogenous compounds. In deeper layers, the nature of organic matter was different from surficial layers in summer and more homogeneous in winter, although a flux of degraded material rich in pyrolysis-derived aromatic hydrocarbons and poor in nitrogenous compounds progressively sank towards the bottom. The two marine prodeltas were compared: organic matter was more degraded in suspended material and sediments collected in the submarine delta of the Rhoˆne River. Organic material originating from the river was transported further offshore, as indicated by a higher content of aromatic hydrocarbons and phenols. In the southwestern part of the Gulf of Lions, the prodelta reflected the influence of local rivers, with lower discharges.

THE INFLUENCE OF ORGANIC MATTER QUALITY ON THE TOXICITY AND PARTIONING OF SEDIMENT-ASSOCIATED FLUORANTHENE

EPA Science Inventory

Organic matter in sediment is derived from many sources, including dead plants and animals, fecal matter, and flocculated colloidal organic matter. hemical partitioning and toxicity of nonpolar organic contaminants is strongly affected by the quantity of sediment organic matter. ...

Dissolved and labile concentrations of Cd, Cu, Pb, and Zn in the South Fork Coeur d'Alene River, Idaho: Comparisons among chemical equilibrium models and implications for biotic ligand models

USGS Publications Warehouse

Balistrieri, L.S.; Blank, R.G.

2008-01-01

In order to evaluate thermodynamic speciation calculations inherent in biotic ligand models, the speciation of dissolved Cd, Cu, Pb, and Zn in aquatic systems influenced by historical mining activities is examined using equilibrium computer models and the diffusive gradients in thin films (DGT) technique. Several metal/organic-matter complexation models, including WHAM VI, NICA-Donnan, and Stockholm Humic model (SHM), are used in combination with inorganic speciation models to calculate the thermodynamic speciation of dissolved metals and concentrations of metal associated with biotic ligands (e.g., fish gills). Maximum dynamic metal concentrations, determined from total dissolved metal concentrations and thermodynamic speciation calculations, are compared with labile metal concentrations measured by DGT to assess which metal/organic-matter complexation model best describes metal speciation and, thereby, biotic ligand speciation, in the studied systems. Results indicate that the choice of model that defines metal/organic-matter interactions does not affect calculated concentrations of Cd and Zn associated with biotic ligands for geochemical conditions in the study area, whereas concentrations of Cu and Pb associated with biotic ligands depend on whether the speciation calculations use WHAM VI, NICA-Donnan, or SHM. Agreement between labile metal concentrations and dynamic metal concentrations occurs when WHAM VI is used to calculate Cu speciation and SHM is used to calculate Pb speciation. Additional work in systems that contain wide ranges in concentrations of multiple metals should incorporate analytical speciation methods, such as DGT, to constrain the speciation component of biotic ligand models. ?? 2008 Elsevier Ltd.

Interactions between iron and organic matter may influence the fate of permafrost carbon in the Arctic

NASA Astrophysics Data System (ADS)

Cory, R. M.; Trusiak, A.; Ward, C.; Kling, G. W.; Tfaily, M.; Paša-Tolić, L.; Noel, V.; Bargar, J.

2017-12-01

The ongoing thawing of permafrost soils is the only environmental change that allows tremendous stores of organic carbon (C) to be converted into carbon dioxide (CO2) on decadal time scales, thus providing a positive and accelerating feedback to global warming. Evidence suggests that iron enhances abiotic reactions that convert dissolved organic matter (DOM) to CO2 in dark soils and in sunlit surface waters depending on its redox state and association with DOM (i.e., iron-DOM complexation). However, the complexation of iron in surface waters and soils remains too poorly understood to predict how iron influences the rates of oxidation of DOM to CO2. To address this knowledge gap, we characterized iron-DOM complexation in iron-rich soil and surface waters of the Arctic, in combination with measurements of DOM oxidation to CO2. These waters contain high concentrations of dissolved iron and DOM (up to 1 and 2 mM, respectively), and low concentrations of other potential ligands for iron such as sulfide, carbonate, chloride, or bromide. Ultra-high resolution mass spectrometry (FT-ICR MS) was used to identify ligands for iron within the DOM pool, and synchrotron based X-ray analysis (XAS and EXAFS) was used to assess iron's oxidation state, to detect iron complexation, and to constrain the chemical composition of the complexes. Across a natural gradient of dissolved iron and DOM concentrations, many potential ligands were identified within DOM that are expected to complex with iron (e.g., aromatic acids). EXAFS showed substantial complexation of reduced ferrous iron (Fe(II)) to DOM in arctic soil waters, on the basis of comparison to Fe(II)-DOM reference spectra. Identification of iron complexed to DOM in soil waters is consistent with strongly co-varying iron and DOM concentrations in arctic soil and surface waters, and supports our hypothesis that complexation of iron by DOM influences dark and light redox reactions that oxidize DOM to CO2. Understanding the molecular controls on the biogeochemical reactions that convert permafrost carbon to CO2 is critical for understanding the role of the Arctic in current and future climate change.

Emergence of complex chemistry on an organic monolayer.

PubMed

Prins, Leonard J

2015-07-21

In many origin-of-life scenarios, inorganic materials, such as FeS or mineral clays, play an important role owing to their ability to concentrate and select small organic molecules on their surface and facilitate their chemical transformations into new molecules. However, considering that life is made up of organic matter, at a certain stage during the evolution the role of the inorganic material must have been taken over by organic molecules. How this exactly happened is unclear, and, indeed, a big gap separates the rudimentary level of organization involving inorganic materials and the complex organization of cells, which are the building blocks of life. Over the past years, we have extensively studied the interaction of small molecules with monolayer-protected gold nanoparticles (Au NPs) for the purpose of developing innovative sensing and catalytic systems. During the course of these studies, we realized that the functional role of this system is very similar to that typically attributed to inorganic surfaces in the early stages of life, with the important being difference that the functional properties (molecular recognition, catalysis, signaling, adaptation) originate entirely from the organic monolayer rather than the inorganic support. This led us to the proposition that this system may serve as a model that illustrates how the important role of inorganic surfaces in dictating chemical processes in the early stages of life may have been taken over by organic matter. Here, we reframe our previously obtained results in the context of the origin-of-life question. The following functional roles of Au NPs will be discussed: the ability to concentrate small molecules and create different local populations, the ability to catalyze the chemical transformation of bound molecules, and, finally, the ability to install rudimentary signaling pathways and display primitive adaptive behavior. In particular, we will show that many of the functional properties of the system originate from two features: the presence of metal ions that are complexed in the organic monolayer and the multivalent nature of the system. Complexed metal ions play an important role in determining the affinity and selectivity of the interaction with small molecules, but serve also as regulatory elements for determining how many molecules are bound simultaneously. Importantly, neighboring metal ion complexes also create catalytic pockets in which two metal ions cooperatively catalyze the cleavage of an RNA-model compound. The multivalent nature of the system permits multiple noncovalent interactions with small molecules that enhances the affinity, but is also at the basis of simple signal transduction pathways and adaptive behavior.

Speciation and Trends of Organic Nitrogen in Southeastern U.S. Fine Particulate Matter (PM2.5)

EPA Science Inventory

Dissolved free amino acids (FAA; amino acids present in a dissolvable state) and combined AA (CAA; amino acids present in peptides, proteins, or humic complexes) in fine aerosols (PM) are investigated at a semi-urban site in the southeastern US. Detection of native (chemically un...

Microbial community structure is affected by cropping sequences and poultry litter under long-term no-tillage

USDA-ARS?s Scientific Manuscript database

Soil microorganisms play essential roles in soil organic matter dynamics and nutrient cycling in agroecosystems and have been used as soil quality indicators. The response of soil microbial communities to land management is complex and the long-term impacts of cropping systems on soil microbes is l...

Prospects and challenges for fungal metatranscriptomics of complex communities

Treesearch

Cheryl R. Kuske; Cedar N. Hesse; Jean F. Challacombe; Daniel Cullen; Joshua R. Herr; Rebecca C. Mueller; Adrian Tsang; Rytas Vilgalys

2015-01-01

The ability to extract and purify messenger RNA directly from plants, decomposing organic matter and soil, followed by highthroughput sequencing of the pool of expressed genes, has spawned the emerging research area of metatranscriptomics. Each metatranscriptome provides a snapshot of the composition and relative abundance of actively transcribed genes, and thus...

DENSITY FRACTIONATION OF FOREST SOILS: METHODOLOGICAL QUESTIONS AND INTERPRETATION OF INCUBATION RESULTS AND TURNOVER TIME IN AN ECOSYSTEM CONTEXT

EPA Science Inventory

Soil organic matter (SOM) is often separated by physical means to simplify a complex matrix into discrete fractions. A frequent approach to isolating two or more fractions is based on differing particle densities and uses a high density liquid such as sodium polytungstate (SPT). ...

Investigating the capability to resolve complex white matter structures with high b-value diffusion magnetic resonance imaging on the MGH-USC Connectom scanner.

PubMed

Fan, Qiuyun; Nummenmaa, Aapo; Witzel, Thomas; Zanzonico, Roberta; Keil, Boris; Cauley, Stephen; Polimeni, Jonathan R; Tisdall, Dylan; Van Dijk, Koene R A; Buckner, Randy L; Wedeen, Van J; Rosen, Bruce R; Wald, Lawrence L

2014-11-01

One of the major goals of the NIH Blueprint Human Connectome Project was to map and quantify the white matter connections in the brain using diffusion tractography. Given the prevalence of complex white matter structures, the capability of resolving local white matter geometries with multiple crossings in the diffusion magnetic resonance imaging (dMRI) data is critical. Increasing b-value has been suggested for delineation of the finer details of the orientation distribution function (ODF). Although increased gradient strength and duration increase sensitivity to highly restricted intra-axonal water, gradient strength limitations require longer echo times (TE) to accommodate the increased diffusion encoding times needed to achieve a higher b-value, exponentially lowering the signal-to-noise ratio of the acquisition. To mitigate this effect, the MGH-USC Connectom scanner was built with 300 mT/m gradients, which can significantly reduce the TE of high b-value diffusion imaging. Here we report comparisons performed across b-values based on q-ball ODF metrics to investigate whether high b-value diffusion imaging on the Connectom scanner can improve resolving complex white matter structures. The q-ball ODF features became sharper as the b-value increased, with increased power fraction in higher order spherical harmonic series of the ODF and increased peak heights relative to the overall size of the ODF. Crossing structures were detected in an increasingly larger fraction of white matter voxels and the spatial distribution of two-way and three-way crossing structures was largely consistent with known anatomy. Results indicate that dMRI with high diffusion encoding on the Connectom system is a promising tool to better characterize, and ultimately understand, the underlying structural organization and motifs in the human brain.

Complex Forms of Soil Organic Phosphorus-A Major Component of Soil Phosphorus.

PubMed

McLaren, Timothy I; Smernik, Ronald J; McLaughlin, Mike J; McBeath, Therese M; Kirby, Jason K; Simpson, Richard J; Guppy, Christopher N; Doolette, Ashlea L; Richardson, Alan E

2015-11-17

Phosphorus (P) is an essential element for life, an innate constituent of soil organic matter, and a major anthropogenic input to terrestrial ecosystems. The supply of P to living organisms is strongly dependent on the dynamics of soil organic P. However, fluxes of P through soil organic matter remain unclear because only a minority (typically <30%) of soil organic P has been identified as recognizable biomolecules of low molecular weight (e.g., inositol hexakisphosphates). Here, we use (31)P nuclear magnetic resonance spectroscopy to determine the speciation of organic P in soil extracts fractionated into two molecular weight ranges. Speciation of organic P in the high molecular weight fraction (>10 kDa) was markedly different to that of the low molecular weight fraction (<10 kDa). The former was dominated by a broad peak, which is consistent with P bound by phosphomonoester linkages of supra-/macro-molecular structures, whereas the latter contained all of the sharp peaks that were present in unfractionated extracts, along with some broad signal. Overall, phosphomonoesters in supra-/macro-molecular structures were found to account for the majority (61% to 73%) of soil organic P across the five diverse soils. These soil phosphomonoesters will need to be integrated within current models of the inorganic-organic P cycle of soil-plant terrestrial ecosystems.

Approaches to Establishing the Chemical Structure of Extraterrestrial Organic Solids

NASA Technical Reports Server (NTRS)

Cody, G. D.; Alexander, C. M. OD.; Wirick, Susan

2003-01-01

The majority of extraterrestrial organic matter in carbonaceous chondrites resides in a chemically complex, insoluble and perhaps macromolecular phase. We have been applying a series of independent solid state NMR experiments that are designed to provide a self consistent chemical characterization of this complex material. To date we have thoroughly analyzed 8 organic residues from different meteorites, including a CR2 (EET92042), CIl(Orgueil), CM2 (Murchison), Tagish Lake, CM2 (AlH83100), CM2 (Cold Bokkefeld), CM2 (Mighei), CM3 (Y86720). In fig 1. (1)H to (13)C cross polarization NMR spectra of four of these are shown. Note that there exists an enormous range in chemistry exhibited in organic solid [evident by the breadth of the spectral features both in the aliphatic region (sp(sup 3)) and the aromatic region (sp(sup 2))]. There is also considerable differences in the carbon chemistry across the meteorite groups.

Response of Peat-forming Ecosystems of the Western Antarctic Peninsula to Recent Climate Change

NASA Astrophysics Data System (ADS)

Tardona, M.; Beilman, D.; Yu, Z.; Loisel, J.

2014-12-01

Amplified warming and related environmental changes in the high latitudes have a complex geographic pattern, with the Western Antarctic Peninsula experiencing one of the fastest rates of recent warming globally. To better understand the response of terrestrial Antarctic ecosystems to polar change, we applied a paleoscience approach to organic soil profiles from 13 aerobic peatbank ecosystems on 7 islands along the peninsula from 67.6 to 64.2°S. Peatbank ecosystem ages were obtained by Radiocarbon measurements of organic matter from the base of these profiles and cluster in three groups: older than 1000 years old (as old as 2750 years old), 400-500 years old, and younger than 65 years with fixed bomb-spike carbon. Three of these peatbank profiles were studied in detail, and show growth rates over the last 65 years of ~2.5 mm yr-1. This rate is faster than those observed during previous periods but is similar to other recent nearby studies that report recent growth rates of ~2.6 mm yr-1. Organic carbon storage ranged from 6.1 to 21.3 kgC m-2. Values of moss bank organic matter δ13C show progressively more depleted δ13C values; in which depletion increases 3.0‰ over recent decades. Overall increase in source-independent discrimination is 1.7‰, consistent with published records from other locations and an increase in photosynthetic activity at the regional scale. Source-independent discrimination displays substantial variations corresponding negatively to variation of organic matter C:N values. Our results imply several recent changes in Antarctic peat forming ecosystem processes including formation of new moss banks, increased accumulation rates, and high variability in source-independent discrimination. These changes are complex but affected by contemporary climate changes of the region including increasing temperatures over the past century.

Decreased centrality of cortical volume covariance networks in autism spectrum disorders.

PubMed

Balardin, Joana Bisol; Comfort, William Edgar; Daly, Eileen; Murphy, Clodagh; Andrews, Derek; Murphy, Declan G M; Ecker, Christine; Sato, João Ricardo

2015-10-01

Autism spectrum disorders (ASD) are a group of neurodevelopmental conditions characterized by atypical structural and functional brain connectivity. Complex network analysis has been mainly used to describe altered network-level organization for functional systems and white matter tracts in ASD. However, atypical functional and structural connectivity are likely to be also linked to abnormal development of the correlated structure of cortical gray matter. Such covariations of gray matter are particularly well suited to the investigation of the complex cortical pathology of ASD, which is not confined to isolated brain regions but instead acts at the systems level. In this study, we examined network centrality properties of gray matter networks in adults with ASD (n = 84) and neurotypical controls (n = 84) using graph theoretical analysis. We derived a structural covariance network for each group using interregional correlation matrices of cortical volumes extracted from a surface-based parcellation scheme containing 68 cortical regions. Differences between groups in closeness network centrality measures were evaluated using permutation testing. We identified several brain regions in the medial frontal, parietal and temporo-occipital cortices with reductions in closeness centrality in ASD compared to controls. We also found an association between an increased number of autistic traits and reduced centrality of visual nodes in neurotypicals. Our study shows that ASD are accompanied by atypical organization of structural covariance networks by means of a decreased centrality of regions relevant for social and sensorimotor processing. These findings provide further evidence for the altered network-level connectivity model of ASD. Copyright © 2015 Elsevier Ltd. All rights reserved.

Quantitative geochemical modeling along a transect off Peru: Carbon cycling in time and space, and the triggering factors for carbon loss and storage

NASA Astrophysics Data System (ADS)

Arning, Esther T.; van Berk, Wolfgang; Schulz, Hans-Martin

2012-12-01

Early diagenetic processes in Peruvian shelf and slope sediments are numerically reproduced by applying chemical thermodynamics in a complex, universal approach using the PHREEQC (version 2) computer code. The reaction kinetics of organic carbon remineralization are integrated into a set of equilibrium reactions by defining the type and the amount of converted organic matter in a certain time step. We calculate the most intense remineralization of organic carbon for present-day shelf sites, and the final carbon pool is dominated by secondary carbonates. This serves to highlight the influence of organic matter degradation and anaerobic oxidation of methane (AOM) on diagenetic mineral formation. The enrichment of aqueous methane and the formation of methane hydrate only takes place in slope sediments with high sedimentation rates that prevent diffusive loss of methane (e.g., Sites 682 and 688). Moreover, AOM prevents the diffusion of dissolved methane into overlying seawater. Throughout the Miocene period, these sites were located on a former shelf and the total carbon loss from the sediments was significantly higher in comparison with the present-day. Compared with the present-day shelf site, organic matter remineralization is high, and methane is produced but not stored within the sediments. Our model calculations rule out the possibility of present-day and former shelf site sediments off the coast of Peru as methane reservoirs. Remineralized TOC has to be considered, particularly in older sediments, when interpreting TOC profiles and calculating mass accumulation rates of total organic carbon (MARTOC). The more organic matter has been remineralized during the depositional history, the larger the difference between MARTOC calculated from measured TOC data, and from the sum of modeled and measured TOC data. Consequently, most reliable primary productivity calculations are based on the sum of measured relict TOC and the amount of remineralized organic carbon determined by modeling.

Enzymatic regulation of organic matter metabolism in Siberia's Kolyma River Watershed

NASA Astrophysics Data System (ADS)

Mann, P. J.; Sobczak, W.; Vonk, J. E.; Davydova, A.; Schade, J.; Bulygina, E.; Davydov, S.; Zimov, N.; Holmes, R. M.

2012-04-01

Arctic soils contain vast amounts of ancient organic carbon stored in permafrost that can be unlocked and remobilised via permafrost thaw and bacterial degradation. The mechanisms regulating the release and fate of this carbon are important to understand if we wish to predict future changes in the global carbon cycle. Microbial communities release enzymes into the environment (ectoenzymes) as a means of degrading organic matter and to acquire carbon, nitrogen and phosphorus for assimilation. We measured potential activities of a suite of ectoenzymes within surface waters collected from a range of streams and rivers throughout the Kolyma River basin, Siberia. Ectoenzyme activities were additionally measured in Kolyma river waters collected at three distinct periods of the hydrograph (under-ice, freshet and summer conditions). Seven enzymes were studied allowing bacterial requirements for a wide range of compounds including lignin, carbohydrates, proteins and cellulose to be assessed. Concurrent measurements of DOC lability were conducted using biological oxygen demand assays conducted over 5 days (BOD). Phenol oxidase activity was found to strongly correlate to BOD (r2=0.68) and stream CO2 concentration (r2=0.76) across all of the study sites, suggesting the rate of phenolic degradation may be a controlling factor in organic carbon metabolism. The activity rate in ectoenzymes that catalyze phosphate, lignin and carbon substrates varied significantly within the Kolyma river over the hydrograph, suggesting that seasonal changes in organic matter composition may also shift the limiting resource for bacterial degradation. Extremely high activity rates in ectoenzymes that catalyze lignin, chitin, cellulose and proteins were measured in waters draining permafrost ice complexes. It is apparent that organic carbon is continually processed throughout the stream network, and that its ultimate fate is linked to organic matter composition. We demonstrate that organic carbon derived from ancient permafrost thaw may be highly biolabile within Arctic aquatic ecosystems.

Advanced solvent based methods for molecular characterization of soil organic matter by high-resolution mass spectrometry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tfaily, Malak M.; Chu, Rosalie K.; Tolic, Nikola

2015-05-19

Soil organic matter (SOM) a complex, heterogeneous mixture of above and belowground plant litter and animal and microbial residues at various degrees of decomposition, is a key reservoir for carbon (C) and nutrient biogeochemical cycling in soil based ecosystems. A limited understanding of the molecular composition of SOM limits the ability to routinely decipher chemical processes within soil and predict accurately how terrestrial carbon fluxes will response to changing climatic conditions and land use. To elucidate the molecular-level structure of SOM, we selectively extracted a broad range of intact SOM compounds by a combination of different organic solvents from soilsmore » with a wide range of C content. Our use of Electrospray ionization (ESI) coupled with Fourier transform ion cyclotron resonance mass spectrometry (FTICR MS) and a suite of solvents with varying polarity significantly expands the inventory of the types of organic molecules present in soils. Specifically, we found that hexane is selective for lipid-like compounds with very low O:C ratios; water was selective for carbohydrates with high O:C ratios; acetonitrile preferentially extracts lignin, condensed structures, and tannin poly phenolic compounds with O:C > 0.5; methanol has higher selectivity towards compounds characterized with low O:C < 0.5; and hexane, MeOH, ACN and water solvents increase the number and types of organic molecules extracted from soil for a broader range of chemically diverse soil types. Our study of SOM molecules by ESI-FTICR MS revealed new insight into the molecular-level complexity of organics contained in soils.« less

Pathways of anaerobic organic matter decomposition in tundra soils from Barrow, Alaska

DOE PAGES

Herndon, Elizabeth M.; Mann, Benjamin F.; Chowdhury, Taniya Roy; ...

2015-11-23

Arctic tundra soils store a large quantity of organic carbon that is susceptible to decomposition and release to the atmosphere as methane (CH 4) and carbon dioxide (CO 2) under a warming climate. Anaerobic processes that generate CH 4 and CO 2 remain unclear because previous studies have focused on aerobic decomposition pathways. To predict releases of CO 2 and CH 4 from tundra soils, it is necessary to identify pathways of soil organic matter decomposition under the anoxic conditions that are prevalent in Arctic ecosystems. Here molecular and spectroscopic techniques were used to monitor biological degradation of water-extractable organicmore » carbon (WEOC) during anoxic incubation of tundra soils from a region of continuous permafrost in northern Alaska. Organic and mineral soils from the tundra active layer were incubated at –2, +4, or +8°C for up to 60 days to mimic the short-term thaw season. Results suggest that, under anoxic conditions, fermentation converted complex organic molecules into simple organic acids that were used in concomitant Fe-reduction and acetoclastic methanogenesis reactions. Nonaromatic compounds increased over time as WEOC increased. Organic acid metabolites initially accumulated in soils but were mostly depleted by day 60 because organic acids were consumed to produce Fe(II), CO 2, and CH 4. We conclude that fermentation of nonprotected organic matter facilitates methanogenesis and Fe reduction reactions, and that the proportion of organic acids consumed by methanogenesis increases relative to Fe reduction with increasing temperature. As a result, the decomposition pathways observed in this study are important to consider in numerical modeling of greenhouse gas production in the Arctic.« less

Identification of sources and seasonal variability of organic matter in Lake Sihwa and surrounding inland creeks, South Korea.

PubMed

Lee, Yeonjung; Hong, Seongjin; Kim, Min-Seob; Kim, Dahae; Choi, Bo-Hyung; Hur, Jin; Khim, Jong Seong; Shin, Kyung-Hoon

2017-06-01

Coastal areas are subjected to significant allochthonous organic matter deposits from surrounding areas; however, limited information is available on the source and delivery of this organic matter. In this study, to assess seasonal changes in the sources of organic matter in Lake Sihwa (Korea), biodegradability, fluorescence property, and stable isotopic compositions (carbon, nitrogen, and sulfur) of the organic matter were determined. Water samples were collected from the inner lake (n = 9) and inland creeks (n = 10) in five separate events, from November 2012 to October 2013. Organic matter originating from rural, urban, and industrial areas was examined as the potential sources. The organic matter contents and biodegradability in the industrial area were the highest, whereas low concentrations and poor biodegradability of organic matter were found in the rural area, and moderate properties were observed in the urban area. In Lake Sihwa, a large concentration of total organic matter and enhanced biodegradability were observed during March and August. However, main source of organic matter differed between the sampling events. The largest contribution of organic matter, deriving from marine phytoplankton, was found in March. On the other hand, in August, the organic matter originating from the industrial area, which is characterized by high levels of heavy metals and persistent organic pollutants, was significantly increased. Our results could be useful to enhance the management of water bodies aimed at reducing the organic matter concentrations and improving the water quality of Lake Sihwa, and even that of the Yellow Sea. Copyright © 2017 Elsevier Ltd. All rights reserved.

The Irreversible Loss of a Decomposition Pathway Marks the Single Origin of an Ectomycorrhizal Symbiosis

PubMed Central

Wolfe, Benjamin E.; Tulloss, Rodham E.; Pringle, Anne

2012-01-01

Microbial symbioses have evolved repeatedly across the tree of life, but the genetic changes underlying transitions to symbiosis are largely unknown, especially for eukaryotic microbial symbionts. We used the genus Amanita, an iconic group of mushroom-forming fungi engaged in ectomycorrhizal symbioses with plants, to identify both the origins and potential genetic changes maintaining the stability of this mutualism. A multi-gene phylogeny reveals one origin of the symbiosis within Amanita, with a single transition from saprotrophic decomposition of dead organic matter to biotrophic dependence on host plants for carbon. Associated with this transition are the losses of two cellulase genes, each of which plays a critical role in extracellular decomposition of organic matter. However a third gene, which acts at later stages in cellulose decomposition, is retained by many, but not all, ectomycorrhizal species. Experiments confirm that symbiotic Amanita species have lost the ability to grow on complex organic matter and have therefore lost the capacity to live in forest soils without carbon supplied by a host plant. Irreversible losses of decomposition pathways are likely to play key roles in the evolutionary stability of these ubiquitous mutualisms. PMID:22815710

The role of attached phase soil and sediment organic matter physicochemical properties on fullerene (nC60) attachment.

PubMed

McNew, Coy P; LeBoeuf, Eugene J

2015-11-01

Attached phase soil and sediment organic matter is ubiquitous in the subsurface environment, with a tendency to strongly sorb contaminants, and therefore it may play an important role in contaminant transport. In this study, the deposition of C60 nanoparticles onto attached phase Harpeth Humic Acid and Harpeth Fulvic Acid (HHA and HFA) is explored by using a quartz crystal microbalance with dissipation monitoring and systematically varying thermal energy. By comparing the C60 attachment onto HHA and HFA surfaces to that of bare silica and DLVO predictions, we find that the HHA and HFA layers hinder attachment at low temperatures, while HHA enhances attachment at higher temperatures. Based on thermal characterization of the HHA and HFA layers compared to the corresponding attachment trends, the attachment efficiency is strongly correlated with hydration of the layer. Possible mechanisms explaining this phenomenon include water-assisted disruption of polar SOM contacts and hydration-induced swelling of the AP-SOM matrix. Since humic substances typically dominate subsurface organic matter, these results may prove crucial to understanding the complex interactions of engineered nanomaterials in both the natural and engineered environment. Copyright © 2015 Elsevier Ltd. All rights reserved.

Labile, dissolved and particulate PAHs and trace metals in wastewater: passive sampling, occurrence, partitioning in treatment plants.

PubMed

Gourlay-Francé, C; Bressy, A; Uher, E; Lorgeoux, C

2011-01-01

The occurrence and the partitioning of polycyclic aromatic hydrocarbons (PAHs) and seven metals (Al, Cd, Cr, Cu, Ni, Pb and Zn) were investigated in activated sludge wastewater treatment plants by means of passive and active sampling. Concentrations total dissolved and particulate contaminants were determined in wastewater at several points across the treatment system by means of grab sampling. Truly dissolved PAHs were sampled by means of semipermeable membrane devices. Labile (inorganic and weakly complexed) dissolved metals were also sampled using the diffusive gradient in thin film technique. This study confirms the robustness and the validity of these two passive sampling techniques in wastewater. All contaminant concentrations decreased in wastewater along the treatment, although dissolved and labile concentrations sometimes increased for substances with less affinity with organic matter. Solid-liquid and dissolved organic matter/water partitioning constants were estimated. The high variability of both partitioning constants for a simple substance and the poor relation between K(D) and K(OW) shows that the binding capacities of particles and organic matter are not uniform within the treatment and that other process than equilibrium sorption affect contaminant repartition and fate in wastewater.

Maneuvering in the Complex Path from Genotype to Phenotype

NASA Astrophysics Data System (ADS)

Strohman, Richard

2002-04-01

Human disease phenotypes are controlled not only by genes but by lawful self-organizing networks that display system-wide dynamics. These networks range from metabolic pathways to signaling pathways that regulate hormone action. When perturbed, networks alter their output of matter and energy which, depending on the environmental context, can produce either a pathological or a normal phenotype. Study of the dynamics of these networks by approaches such as metabolic control analysis may provide new insights into the pathogenesis and treatment of complex diseases.

Pluto's elongated dark regions formed by the Charon-forming giant impact

NASA Astrophysics Data System (ADS)

Genda, Hidenori; Sekine, Yusuhito; Kamata, Shunichi; Funatsu, Taro

2017-04-01

The New Horizons spacecraft has found elongated dark areas in the equatorial region of Pluto, which were informally called "the Whale" or Cthulhu Region (Stern et al. 2015). Here we examine the possibility that the dark areas on Pluto were formed by thermal alterations and polymerization of interstellar volatiles caused by a Charon-forming giant impact. Pluto is one of the largest Kuiper belt objects, which is highly likely to contain various interstellar volatiles, including aldehyde and ammonia. The previous study (Cordy et al. 2011) shows that these interstellar volatiles are thermally polymerized in solutions at high temperatures, forming complex insoluble organic solids. Given the satellite-to-planet mass ratio, the Pluto-Charon system is suggested to be of a giant impact origin (Canup 2005). Impact-induced heating on Pluto could have converted these volatile into complex organic matter in solution near the surface, which may explain the presence of dark areas in the equatorial region of Pluto. Here, we produce complex organic matter for various temperatures by thermal polymerization of formaldehyde and ammonia in solutions. By measuring the UV-VIS absorption spectra of the produced organic matter, we found that the color of the solution changes to be dark if the temerature is above 50 degree C for months or more. This duration corresponds to the cooling timescale of a water pond with 500-km thickness. By using SPH code (Genda et al. 2015), we carried out many simulations of a giant impact, and we found that a molten hot pond with > 500-km thickness is formed around the equatorial region of Pluto by a Charon-forming giant impact, if the water/rock mixing mass ratio is less than 1 or if the pre-impact interior temperature is 150 K. Both the dark equatorial region and a Charon-sized moon are formed when the pre-impact Pluto is undifferentiated. To keep a rock-rich Pluto undifferentiated at time of the giant impact, Pluto may have been formed >100 Myrs after CAIs, and the giant impact may have occurred <100 Myrs after the Pluto's formation.

Concept model of the formation process of humic acid-kaolin complexes deduced by trichloroethylene sorption experiments and various characterizations.

PubMed

Zhu, Xiaojing; He, Jiangtao; Su, Sihui; Zhang, Xiaoliang; Wang, Fei

2016-05-01

To explore the interactions between soil organic matter and minerals, humic acid (HA, as organic matter), kaolin (as a mineral component) and Ca(2+) (as metal ions) were used to prepare HA-kaolin and Ca-HA-kaolin complexes. These complexes were used in trichloroethylene (TCE) sorption experiments and various characterizations. Interactions between HA and kaolin during the formation of their complexes were confirmed by the obvious differences between the Qe (experimental sorbed TCE) and Qe_p (predicted sorbed TCE) values of all detected samples. The partition coefficient kd obtained for the different samples indicated that both the organic content (fom) and Ca(2+) could significantly impact the interactions. Based on experimental results and various characterizations, a concept model was developed. In the absence of Ca(2+), HA molecules first patched onto charged sites of kaolin surfaces, filling the pores. Subsequently, as the HA content increased and the first HA layer reached saturation, an outer layer of HA began to form, compressing the inner HA layer. As HA loading continued, the second layer reached saturation, such that an outer-third layer began to form, compressing the inner layers. In the presence of Ca(2+), which not only can promote kaolin self-aggregation but can also boost HA attachment to kaolin, HA molecules were first surrounded by kaolin. Subsequently, first and second layers formed (with inner layer compression) via the same process as described above in the absence of Ca(2+), except that the second layer continued to load rather than reach saturation, within the investigated conditions, because of enhanced HA aggregation caused by Ca(2+). Copyright © 2016 Elsevier Ltd. All rights reserved.

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

Particle size distribution of river-suspended sediments determined by in situ measured remote-sensing reflectance.

PubMed

Zhang, Yuanzhi; Huang, Zhaojun; Chen, Chuqun; He, Yijun; Jiang, Tingchen

2015-07-10

Suspended sediments in water bodies are classified into organic and inorganic matter and have been investigated by remote-sensing technology for years. Focusing on inorganic matter, however, detailed information such as the grain size of this matter has not been provided yet. In this study, we present a new solution for estimating inorganic suspended sediments' size distribution in highly complex Case 2 waters by using a simple spectrometer sensor rather than a backscattering sensor. An experiment was carried out in the Pearl River Estuary (PRE) in the dry season to collect the remote-sensing reflectance (R_rs) and particle size distribution (PSD) of inorganic suspended sediments. Based on Mie theory, PSDs in the PRE waters were retrieved by R_rs, colored dissolved organic matter, and phytoplankton. The retrieved median diameters in 12 stations show good agreement with those of laboratory analysis at root mean square error of 2.604 μm (27.63%), bias of 1.924 μm (20.42%), and mean absolute error of 2.298 μm (24.37%). The retrieved PSDs and previous PSDs were compared, and the features of PSDs in the PRE waters were concluded.

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 from degradation of complex organic matter (e.g. Tepidibacter sp.) to sulfur-dependent utilisation of simple organic molecules (e.g. Desulfobulbaceae and Desulfuromonadaceae. 1. Hedges and Keil (1995) Mar Chem 49, 81-115. 2. Baldock et al., (2004) Mar Chem 92, 39-64. 3. Deming and Baross, (1993) Plenum Press, NY. 4. 4. Gooday, (2002) J Oceanogr 58, 305-332. 5. O'Reilly et al., (2013) Estuar, Coast & Shelf Sci. http://dx.doi.org/10.1016/j.ecss.2013.11.002

Progress Towards Identifying and Quantifying the Organic Ice Nucleating Particles in Soils and Aerosols

NASA Astrophysics Data System (ADS)

Hill, T. C. J.; DeMott, P. J.; Fröhlich-Nowoisky, J.; Tobo, Y.; Suski, K. J.; Levin, E. J.; Kreidenweis, S. M.; Franc, G. D.

2014-12-01

Soil and plant surfaces emit ice nucleating particles (INP) to the atmosphere, especially when disturbed by wind, harvesting, rain or fire. Organic (biogenic) INP are abundant in most soils and dominate the population that nucleate >-15°C. For example, the sandy topsoil of sagebrush shrubland, a widespread ecotype prone to wind erosion after fire, contains ~106 organic INP g-1 at -6°C. The relevance of organic INP may also extend to colder temperatures than previously thought: Particles of soil organic matter (SOM) have been shown to be more important than mineral particles for the ice nucleating ability of agricultural soil dusts to -34°C. While the abundance of ice nucleation active (INA) bacteria on plants has been established, the identity of the organic INP in and emitted by soils remains a 40-year-old mystery. The need to understand their production and release is highlighted by recent findings that INA bacteria (measured with qPCR) account for few, if any, of the warm-temperature organic INP that predominate in boundary layer aerosols and snow; organic INP lofted with soil dusts seem a likely source. The complexity of SOM hinders its investigation. It contains decomposing plant materials, a diverse microbial and microfaunal community, humus, and inert organic matter. All are biochemically complex and all may contain ice nucleating constituents, either by design or by chance. Indeed the smoothness of the INP temperature spectra of soils is indicative of numerous, overlapping distributions of INP. We report recent progress in identifying and quantifying the organic INP in soils and boundary layer aerosols representative of West Central U.S. ecosystems, and how their characteristics may affect their dispersal. Chemical, enzymatic and DNA-based tests were used to assess contributions of INP from plant tissues, INA bacteria, INA fungi, organic crystals, monolayers of aliphatic alcohols, carbohydrates, and humic substances, while heat- and peroxide-based tests were used to estimate total organic INP abundance.

Iron oxidation stimulates organic matter decomposition in humid tropical forest soils.

PubMed

Hall, Steven J; Silver, Whendee L

2013-09-01

Humid tropical forests have the fastest rates of organic matter decomposition globally, which often coincide with fluctuating oxygen (O2 ) availability in surface soils. Microbial iron (Fe) reduction generates reduced iron [Fe(II)] under anaerobic conditions, which oxidizes to Fe(III) under subsequent aerobic conditions. We demonstrate that Fe (II) oxidation stimulates organic matter decomposition via two mechanisms: (i) organic matter oxidation, likely driven by reactive oxygen species; and (ii) increased dissolved organic carbon (DOC) availability, likely driven by acidification. Phenol oxidative activity increased linearly with Fe(II) concentrations (P < 0.0001, pseudo R(2)  = 0.79) in soils sampled within and among five tropical forest sites. A similar pattern occurred in the absence of soil, suggesting an abiotic driver of this reaction. No phenol oxidative activity occurred in soils under anaerobic conditions, implying the importance of oxidants such as O2 or hydrogen peroxide (H2 O2 ) in addition to Fe(II). Reactions between Fe(II) and H2 O2 generate hydroxyl radical, a strong nonselective oxidant of organic compounds. We found increasing consumption of H2 O2 as soil Fe(II) concentrations increased, suggesting that reactive oxygen species produced by Fe(II) oxidation explained variation in phenol oxidative activity among samples. Amending soils with Fe(II) at field concentrations stimulated short-term C mineralization by up to 270%, likely via a second mechanism. Oxidation of Fe(II) drove a decrease in pH and a monotonic increase in DOC; a decline of two pH units doubled DOC, likely stimulating microbial respiration. We obtained similar results by manipulating soil acidity independently of Fe(II), implying that Fe(II) oxidation affected C substrate availability via pH fluctuations, in addition to producing reactive oxygen species. Iron oxidation coupled to organic matter decomposition contributes to rapid rates of C cycling across humid tropical forests in spite of periodic O2 limitation, and may help explain the rapid turnover of complex C molecules in these soils. © 2013 John Wiley & Sons Ltd.

Elucidating the fate, transport and processes controlling carbon on the landscape: Biogeochemistry tools for the 21st century

NASA Astrophysics Data System (ADS)

McFarlane, K. J.; Keiluweit, M.; Nico, P. S.; Ognibene, T.; Mayali, X.; Nuccio, E.; Weber, P. K.; Pett-Ridge, J.; Guilderson, T. P.

2013-12-01

Globally, more carbon is stored belowground as soil organic matter than in terrestrial vegetation and the atmosphere combined. A critical scientific question is how soils serve as sources and sinks for atmospheric carbon dioxide (CO2) and how these sinks will evolve with expected changes in atmospheric CO2 concentrations, climate, and land-use. Carbon initially enters belowground soil pools as plant detritus, roots, and root exudates. Once in the soil, this organic matter serves as a substrate for decomposer organisms including soil animals, bacteria, and fungi. Most of this carbon is consumed and respired as CO2, but some is converted to microbial biomass and byproducts, which may leave the soil as dissolved organic carbon, be used as a substrate by other microbes, or be stabilized within the soil mineral matrix. Mechanisms that result in the stabilization of soils include: climate stabilization, physical protection within aggregates and organo-mineral complexes, and protection of potential substrates due to physiochemical barriers. These processes, which span broad temporal and spatial scales, are poorly constrained in many dynamic land surface models. At LLNL, we have developed a suite of analytical tools that allow us to follow the movement of carbon at the cell to landscape scale, including: ';Chip-SIP', ';STXM-SIMS', and new sample interfaces for accelerator mass spectrometry (AMS). Experiments, field-based and in vivo, allow us to further the mechanistic understanding of factors that control the fate, transport, and sequestration potential of belowground carbon. The Chip-SIP approach allows us to interrogate which microbial species in a complex community incorporate specific substrates (e.g. cellulose) in order to understand the production of biofuels and better elucidate energy and carbon transfers in wetlands and soils. To disentangle the complex interactions at soil-microbial-film-mineral interfaces with minimal disruption we are using a combination of high-resolution microspectroscopy (STXM-NEXAFS), electron microscopy (SEM), and nano-scale imaging mass spectrometry (nanoSIMS) collectively known as STXM-SIMS. This approach allows us to track labeled litter, exudates and microbial necromass onto microaggregate surfaces and elucidate how organic matter source and environmental conditions influences the physical and molecular fate of soil organic matter. Isotopic characterization (14C, 13C, 2H) of CH4, CO2, dissolved organic carbon (DOC) and physical sources of carbon provide the mechanistic fingerprints of the biogeochemical pathways that cycle carbon through the landscape. Building on our expertise in accelerator mass spectrometry (AMS), we are developing methods for 'direct injection' of CO2 for AMS-14C analyses. Our initial focus has been on a liquid-sample (HPLC) sample interface. The ability to handle liquid samples and continuous flows of liquid will enable more widespread and routine use of AMS in biological and environmental applications. Applied examples of these novel techniques, addressing critical questions in the biogeosciences, will be presented.

Effect of dissolved organic matter on pre-equilibrium passive sampling: A predictive QSAR modeling study.

PubMed

Lin, Wei; Jiang, Ruifen; Shen, Yong; Xiong, Yaxin; Hu, Sizi; Xu, Jianqiao; Ouyang, Gangfeng

2018-04-13

Pre-equilibrium passive sampling is a simple and promising technique for studying sampling kinetics, which is crucial to determine the distribution, transfer and fate of hydrophobic organic compounds (HOCs) in environmental water and organisms. Environmental water samples contain complex matrices that complicate the traditional calibration process for obtaining the accurate rate constants. This study proposed a QSAR model to predict the sampling rate constants of HOCs (polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and pesticides) in aqueous systems containing complex matrices. A homemade flow-through system was established to simulate an actual aqueous environment containing dissolved organic matter (DOM) i.e. humic acid (HA) and (2-Hydroxypropyl)-β-cyclodextrin (β-HPCD)), and to obtain the experimental rate constants. Then, a quantitative structure-activity relationship (QSAR) model using Genetic Algorithm-Multiple Linear Regression (GA-MLR) was found to correlate the experimental rate constants to the system state including physicochemical parameters of the HOCs and DOM which were calculated and selected as descriptors by Density Functional Theory (DFT) and Chem 3D. The experimental results showed that the rate constants significantly increased as the concentration of DOM increased, and the enhancement factors of 70-fold and 34-fold were observed for the HOCs in HA and β-HPCD, respectively. The established QSAR model was validated as credible (R Adj. 2 =0.862) and predictable (Q 2 =0.835) in estimating the rate constants of HOCs for complex aqueous sampling, and a probable mechanism was developed by comparison to the reported theoretical study. The present study established a QSAR model of passive sampling rate constants and calibrated the effect of DOM on the sampling kinetics. Copyright © 2018 Elsevier B.V. All rights reserved.

[Spatial variability of soil nutrients based on geostatistics combined with GIS--a case study in Zunghua City of Hebei Province].

PubMed

Guo, X; Fu, B; Ma, K; Chen, L

2000-08-01

Geostatistics combined with GIS was applied to analyze the spatial variability of soil nutrients in topsoil (0-20 cm) in Zunghua City of Hebei Province. GIS can integrate attribute data with geographical data of system variables, which makes the application of geostatistics technique for large spatial scale more convenient. Soil nutrient data in this study included available N (alkaline hydrolyzing nitrogen), total N, available K, available P and organic matter. The results showed that the semivariograms of soil nutrients were best described by spherical model, except for that of available K, which was best fitted by complex structure of exponential model and linear with sill model. The spatial variability of available K was mainly produced by structural factor, while that of available N, total N, available P and organic matter was primarily caused by random factor. However, their spatial heterogeneity degree was different: the degree of total N and organic matter was higher, and that of available P and available N was lower. The results also indicated that the spatial correlation of the five tested soil nutrients at this large scale was moderately dependent. The ranges of available N and available P were almost same, which were 5 km and 5.5 km, respectively. The range of total N was up to 18 km, and that of organic matter was 8.5 km. For available K, the spatial variability scale primarily expressed exponential model between 0-3.5 km, but linear with sill model between 3.5-25.5 km. In addition, five soil nutrients exhibited different isotropic ranges. Available N and available P were isotropic through the whole research range (0-28 km). The isotropic range of available K was 0-8 km, and that of total N and organic matter was 0-10 km.

Evidence and age estimation of mass wasting at the distal lobe of the Congo deep-sea fan

NASA Astrophysics Data System (ADS)

Croguennec, Claire; Ruffine, Livio; Dennielou, Bernard; Baudin, François; Caprais, Jean-Claude; Guyader, Vivien; Bayon, Germain; Brandily, Christophe; Le Bruchec, Julie; Bollinger, Claire; Germain, Yoan; Droz, Laurence; Babonneau, Nathalie; Rabouille, Christophe

2017-08-01

On continental margins, sulfate reduction occurs within the sedimentary column. It is coupled with the degradation of organic matter and the anaerobic oxidation of methane. These processes may be significantly disturbed by sedimentary events, leading to transient state profiles for the involved chemical species. Yet, little is known about the impact of turbidity currents and mass wasting on the migration of chemical species and the redox reactions in which they are involved. Due to its connection to the River, the Congo deep-sea fan continuously receives huge amount of organic matter-rich sediments primarily transported by turbidity currents, which impact on the development of the associated ecosystems (Rabouille et al., 2017). Thus, it is well suited to better understand causal relationships between sedimentary events and fluid flow path, with consequences on the zonation of early diagenesis sequences. Here, we combined sedimentological observations with geochemical analyses of pore-water and sediment samples to explore how sedimentary instabilities affected the migration of methane and the distribution of organic matter within the sedimentary column. The results unveiled mass wasting processes affecting recent turbiditic and pelagic deposits, and are interpreted as being slides/ slumps and debrites. Two slides were responsible for the exhumation of an organic matter-rich sedimentary block of more than 5 m thick and the movement of a methane-rich sedimentary block, while turbidity currents enable the intercalation of sandy intervals within a pelagic clay layer. The youngest slide promoted the development of two Sulfate Methane Transition Zones (SMTZ), and may have possibly triggered a lateral migration of methane. Numerical simulation of the sulfate profile indicates that the youngest sedimentary event has occurred around a century ago. Our study emphasizes that turbidity currents and sedimentary instabilities can significantly affect the transport paths and the distribution of both methane and organic matter in the terminal lobe complex, with consequences on geochemical zonation of the sequential early diagenetic processes within the sedimentary column.

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. Copyright © 2016 Elsevier Ltd. All rights reserved.

Bio-refractory dissolved organic matter and colorants in cassava distillery wastewater: Characterization, coagulation treatment and mechanisms.

PubMed

Zhang, Ming; Wang, Zhou; Li, Penghui; Zhang, Hua; Xie, Li

2017-07-01

An important portion of organic matter and colorants still remain in the biologically treated distillery wastewater, leaving the dark brown and odorous downstream with the heavy loading of chemical oxygen demand and the potential of forming disinfection byproducts. However, those bio-recalcitrant colorants have not been clearly recognized. The current study investigated the features of the bio-refractory organic matter and colorants in a typical distillery effluent, cassava distillery wastewater; special attention was paid to their change and behaviors in the coagulation treatment following the bio-processes. The wastewater analyses denoted that the fraction of high molecular weight (1-50 kDa and >50 kDa) became predominant after the anaerobic-aerobic processes. Importantly, the lignin breakdown products, melanoidins and lignin phenols were confirmed to be the leading colored components, according to the parallel factor analysis of fluorescence excitation-emission matrixes results. Compared with lignin phenols, the former two types of colorants exhibited stronger bio-refractory activity and resulted in smaller color reduction after the aerobic treatment. Neither advanced oxidation nor adsorption could perform efficiently as post-treatment for decolorization in this study. Nevertheless, high removal of color and dissolved organic matter (∼94.0% and ∼78.3%, respectively) could be achieved by the FeCl 3 -involved coagulation under the optimal conditions. The ferric coagulant was found to preferably interact with the aromatic compounds (such as lignin derivatives) and melanoidins via either surface complexation or electric charge neutralization, or both. The findings presented herein might provide an insight into the evaluation of bio-refractory organic colorants and the Fe(III)-involved decolorization mechanisms of ethanol production wastewaters. Copyright © 2017 Elsevier Ltd. All rights reserved.

pH : a key control of the nature and distribution of dissolved organic matter and associated trace metals in soil

NASA Astrophysics Data System (ADS)

Pédrot, M.; Dia, A.; Davranche, M.

2009-04-01

Dissolved organic matter is ubiquitous at the Earth's surface and plays a prominent role in controlling metal speciation and mobility from soils to hydrosystems. Humic substances (HS) are usually considered to be the most reactive fraction of organic matter. Humic substances are relatively small and formed by chemically diverse organic molecules, bearing different functional groups that act as binding sites for cations and mineral surfaces. Among the different environmental physicochemical parameters controlling the metal speciation, pH is likely to be the most important one. Indeed, pH affect the dissociation of functional groups, and thus can influence the HS structure, their ability to complex metals, their solubility degree allowing the formation of aggregates at the mineral surface. In this context, soil/water interactions conducted through batch system experiments, were carried out with a wetland organic-rich soil to investigate the effect of pH on the release of dissolved organic carbon (DOC) and associated trace elements. The pH was regulated between 4 and 7.5 using an automatic pH stat titrator. Ultrafiltration experiments were performed to separate the dissolved organic pool following decreasing pore sizes (30 kDa, 5 kDa and 2 kDa with 1 Da = 1 g.mol-1). The pH increase induced a significant DOC release, especially in heavy organic molecules (size >5 kDa) with a high aromaticity (>30 %). These were probably humic acids (HA). This HA release influenced (i) directly the trace element concentrations in soil solution since HA were enriched in several trace elements such as Th, REE, Y, U, Cr and Cu; and (ii) indirectly by the breaking of clay-humic complexes releasing Fe- and Al-rich nanoparticles associated with V, Pb and Ti. By contrast, at acid pH, most HS were complexed onto mineral surfaces. They also sequestered iron nanoparticles. Therefore, at low pH, most part of DOC molecules had a size < 5 kDa and lower aromaticity. Thus, the DOC was mostly composed of simple organic compounds little complexing. Consequently, the soil solution was depleted in trace elements such as Th, REE, Y, U, Cr, Cu, Al, Fe, V, Pb and Ti, but also enriched in Ca, Sr, Ba, Mn, Mg, Co, Zn and in a lesser proportion in Rb, Li and Ni. The aromaticity in the fractions <5 kDa was higher than in the fractions <30 kDa or <0.2 µm. Complementary experiments were performed to understand the HS size distribution and aromaticity according to pH and ionic strength .The molecular size and shape of HS is usually explained by two concepts: (i) the macropolymeric structure with heavy organic molecules considered to be flexible linear polyelectrolytes and (ii) the supramolecular structure with an association of a complex mixture of different molecules held together by dispersive weak forces. Ours results supported the HA supramolecular structure at neutral or basic pH conditions. But, at acid pH, a disruption of the humic supramolecular associations involved the release of small organic molecules with a high aromaticity. Moreover, this aromaticity variation can be due also to the presence of fulvic acids in the fractions <5 kDa and a mixture of heavy organic molecules little complexing in the fractions >5 kDa. These latter molecules displayed a low aromaticity decreasing the global aromaticity of the fractions <30 kDa and <0.2 µm. To summarize, these new data demonstrated that the DOC and trace element concentrations of the soil solutions were strongly controlled by pH. This parameter influenced the nature and the size of the DOC as well as, the trace element concentrations in the soil solutions, with a decreasing contribution of HA when pH decreased. This pH dependence is a key issue of concern since local (human pressure) and/or global (climatic) warning result in pH water changes.

Sorption characteristics of organic compounds on hexadecyltrimethylammonium-smectite

USGS Publications Warehouse

Boyd, Stephen A.; Mortland, Max M.; Chiou, Cary T.

1988-01-01

When hexadedyltrimethylammonium (HDTMA) ion is exchanged for metal cations like calcium in smectite, the sorptive properties of the clay are greatly modified. The resultant HDTMA-smectite complex behaves as a dual sorbent, in the sorption of organic compounds, in which the mineral fraction functions as a solid adsorbent and the organic (HDTMA) phase as a partition medium. Capacities of mineral adsorption and partition uptake by HDTMA in the HDTMA-smectites are illustrated by sorption of benzene, trichloroethene (TCE), and water as vapors on the dry sample and by sorption of benzene and TCE from water. The exchanged HDTMA in clay is found to be a much more powerful partition medium than ordinary soil organic matter in the uptake of benzene and TCE. Based on this finding, HDTMA-smectite appears to be an effective sorbent for removing organic contaminants from water. It is suggested that such sorptive organo-clay complexes could be used to enhance the containment capabilities of clay landfill liners and bentonite slurry walls.

Speciation of organic matter in sandy soil size fractions as revealed by analytical pyrolysis (Py-GC/MS) and FT-IR spectroscopy

NASA Astrophysics Data System (ADS)

Jiménez-Morillo, Nicasio T.; González-Vila, Francisco J.; Jordán, Antonio; Zavala, Lorena M.; de la Rosa, José M.; González-Pérez, José A.

2015-04-01

This research deals with the assessment of organic matter structural differences in soil physical fractions before and after lipid extractions. Soil samples were collected in sandy soils, Arenosols (WRB 2006) from the Doñana National Park (SW Spain) under different vegetation cover: cork oak (Quercus suber, QS), eagle fern (Pteridium aquilinum, PA), pine (Pinus pinea, PP) and rockrose (Halimium halimifolium, HH). Two size fractions; coarse (C: 1-2 mm) and fine (F: 0.05-0.25 mm) were studied from each soil. . In addition, the two fractions from each soil were exhaustively Soxhlet extracted with a Dichlorometane-Methanol (3:1) mixture to obtain the lipid-free fractions (LF) from each size fraction (LFC and LFF). The composition of the organic matter at a molecular level in the different soil fractions was approached by analytical pyrolysis (Py-GC/MS) and FT-IR spectroscopy. These techniques are complementary and have been found suitable for the structural characterization of complex organic matrices (Moldoveanu, 1998; Piccolo and Stevenson, 1982); whereas Py-GC/MS provides detailed structural information of individual compounds present and a finger-printing of soil organic matter, FT-IR is informative about major functional groups present. The advantages of these techniques are well known: no need for pretreatment are fast to perform, highly reproducible and only small amount of samples are needed. Soil size fractions show contrasting differences in organic matter content (C 4-7 % and F > 40 %) and conspicuous differences were found in the pyrolysis products released by the fractions studied. The main families of pyrolysis compounds have well defined macromolecular precursors, such as lignin, polypeptides, polysaccharides and lipids (González-Vila et al., 2001). The C fractions yield higher relative abundance of lignin and polysaccharide derived pyrolysis compounds. Regarding the differences in the soil organic matter as affected by the different vegetation covers, the C fraction from the PA soil presented a higher abundance of lignin derived pyrolysis products than the soils under the other vegetation. This is somehow unexpected since PA is a pteridophyte, not arboreal vegetation, i.e. low lignin content and, these lignin moieties probably remain in the soil from past vegetation or originate from surrounding woody arboreal vegetation. In contrast the F fractions released mainly lipids and aromatic compound of unspecific origin. Series of alkane/alkene pairs were present in all the pyrograms with varying abundance and composition. Lignin and polysaccharide derived pyrolysis compounds were scarce in the F fractions in all the cases, in fact, no sugar derived compounds were found in the HH sample. Regarding the composition of the LF soil fractions, the pyrolytic behavior of the LFC fractions was quite similar to the not extracted corresponding C soil fraction, showing a high proportion of lignin and sugar derived pyrolysis compounds. The LFF fractions also showed the same behavior as the C fraction, but with no lipid derived compounds which effectively indicates the occurrence of a selective and efficient removal of soil free lipids. Agreement was found between analytical pyrolysis results and FT-IR spectral features highlighting functional differences between fractions i.e. a decrease of OH- groups and an increase in aliphatics in the F fraction. With respect to the LF fractions, FT-IR spectra analysis was also consistent with the pyrolysis results with a slight increase in the lignin signals for LFF soil fractions under PA, PP and HH. For the soil under QS no differences were found between the LFF fractions and the whole organic matter in the F fraction, probably due to the high amount of organic matter in this fraction. In conclusion, despite the "a priori" low organic complexity of the collection of soils studied here, ostensible differences were found in the organic matter present in C and F soil size fractions under different vegetation covers, and not only in its intimate chemical composition, but also in its functionality. Whereas the C soil size fractions are composed mainly by relatively well recognized lignocellulosic plant residues, the F soil size fractions have a clearly distinct type of organic matter, more mature/evolved that clearly resembles the characteristics of customary wet extracted humic materials as characterized elsewhere (Stevenson, 1994; González-Pérez et al., 2013). REFERENCES: González-Pérez JA, González-Vila FJ, Almendros G, Knicker H, De la Rosa JM, Hernández Z. 2013. Revisiting Structural insights provided by analytical pyrolysis about humic substances and related bio- and geopolymers. Functions of Natural Organic Matter in Changing Environment, 3-6. DOI: 10.1007/978-94-007-5634-21 González-Vila FJ, Tinoco P, Almendros G, Martin F. 2001. Pyrolysis-GCMS analysis of the formation and degradation stages of charred residues from lignocellulosic biomass. Journal of Agricultural and Food Chemistry 49: 1128-1131. DOI: 10.1021/jf0006325. Moldoveanu SC. 1998. Analytical pyrolysis of natural organic polymers. Techniques and Instrumentation in Analytical Chemistry 20: 3-496. ISBN: 978-0-444-82203-1 Piccolo A, Stevenson FJ. 1982. Infrared-spectra of Cu2+, Pb2+, and Ca2+ complexes of soil humic substances. Geoderma 27: 195-208. DOI: 10.1016/0016-7061(82)90030-1 Stevenson, FJ. 1994. Humus chemistry. Genesis, composition, reactions (2nd edn.), John Wiley & Sons, Inc.: New York, NY, 166-187. DOI: 10.1021/ed072pA93.6. WRB 2006. World Reference Base for Soil Resources. Rome 2006 ACKNOWLEDGMENTS: This study is part of the results of the GEOFIRE Project (CGL2012-38655-C04-01) (BES-2013-062573), funded by the Spanish Ministry for Economy and Competitiveness. Dr. J.M. de la Rosa is the recipient of a fellowship from the JAE-Doc subprogram financed by the CSIC and the European Social Fund.

Simulating Soil Organic Matter with CQESTR (v.2.0): Model Description and Validation against Long-term Experiments across North America

USDA-ARS?s Scientific Manuscript database

Soil carbon (C) models are important tools for examining complex interactions between climate, crop and soil management practices, and to evaluate the long-term effects of management practices on C-storage potential in soils. CQESTR is a process-based carbon balance model that relates crop residue a...

A Summary of Publications on the Development of Mode-of-Action Information and Statistical Tools for Evaluating Health Outcomes from Drinking Water Disinfection By-Product (DBP) Exposures

EPA Science Inventory

Chemical contaminants are formed as a consequence of chemical disinfection of public drinking waters. Chemical disinfectants, which are used to kill harmful microorganisms, react with natural organic matter (NOM), bromide, iodide, and other compounds, forming complex mixtures...

Quantifying the adhesion and interaction forces between Pseudomonas aeruginosa and natural organic matter.

PubMed

Abu-Lail, Laila I; Liu, Yatao; Atabek, Arzu; Camesano, Terri A

2007-12-01

Atomic force microscopy (AFM) was used to characterize interactions between natural organic matter (NOM), and glass or bacteria. Poly(methacrylic acid) (PMA), soil humic Acid (SHA), and Suwannee River humic Acid (SRHA), were adsorbed to silica AFM probes. Adhesion forces (Fadh) for the interaction of organic-probes and glass slides correlated with organic molecular weight (MW), but not with radius of the organic aggregate (R), charge density (Q), or zeta potential (zeta). Two Pseudomonas aeruginosa strains with different lipopolysaccharides (LPS) were chosen: PAO1 (A+B+), whose LPS have common antigen (A-band) + O-antigen (B-band); and mutant AK1401 (A+B-). Fadh between bacteria and organics correlated with organic MW, R, and Q, but not zeta. PAO1 had lower Fadh with silica than NOM, which was attributed to negative charges from the B-band polymers causing electrostatic repulsion. AK1401 adhered stronger to silica than to the organics, perhaps because the absence of the B-band exposed underlying positively charged proteins. DLVO calculations could not explain the differences in the two bacteria or predict qualitative or quantitative trends in interaction forces in these systems. Molecular-level information from AFM studies can bring us closer to understanding the complex nature of bacterial-NOM interactions.

Extraterrestrial Organic Compounds in Meteorites

NASA Technical Reports Server (NTRS)

Botta, Oliver; Bada, Jeffrey L.; Meyer, Michael (Technical Monitor)

2003-01-01

Many organic compounds or their precursors found in meteorites originated in the interstellar or circumstellar medium and were later incorporated into planetesimals during the formation of the solar system. There they either survived intact or underwent further processing to synthesize secondary products on the meteorite parent body. The most distinct feature of CI and CM carbonaceous chondrites, two types of stony meteorites, is their high carbon content (up to 3% of weight), either in the form of carbonates or of organic compounds. The bulk of the organic carbon consists of an insoluble macromolecular material with a complex structure. Also present is a soluble organic fraction, which has been analyzed by several separation and analytical procedures. Low detection limits can be achieved by derivatization of the organic molecules with reagents that allow for analysis by gas chromatography/mass spectroscopy and high performance liquid chromatography. The CM meteorite Murchison has been found to contain more than 70 extraterrestrial amino acids and several other classes of compounds including carboxylic acids, hydroxy carboxylic acids, sulphonic and phosphonic acids, aliphatic, aromatic and polar hydrocarbons, fullerenes, heterocycles as well as carbonyl compounds, alcohols, amines and amides. The organic matter was found to be enriched in deuterium, and distinct organic compounds show isotopic enrichments of carbon and nitrogen relative to terrestrial matter.

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) coupled to XAD fractionation: Method to algal organic matter characterization.

PubMed

Nicolau, Rudy; Leloup, Maud; Lachassagne, Delphine; Pinault, Emilie; Feuillade-Cathalifaud, Geneviève

2015-05-01

This work is focused on the development of an analytical procedure for the improvement of the Organic Matter structure characterization, particularly the algal matter. Two fractions of algal organic matter from laboratory cultures of algae (Euglena gracilis) and cyanobacteria (Microcystis aeruginosa) were extracted with XAD resins. The fractions were studied using laser desorption ionization (LDI) and Matrix-Assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF). A comparison with the natural organic matter characteristics from commercial humic acids and fulvic acids extracted from Suwannee River was performed. Results show that algal and natural organic matters have unique quasi-polymeric structures. Significant repeating patterns were identified. Different fractions extracted from organic matter with common origin had common structures. Thus, 44, 114 and 169Da peaks separation for fractions from E. gracilis organic matter and 28, 58 and 100Da for M. aeruginosa ones were clearly observed. Using the developed protocol, a structural scheme and organic matter composition were obtained. The range 600-2000Da contained more architectural composition differences than the range 100-600Da, suggesting that organic matter is composed of an assembly of common small molecules. Associated to specific monomers, particular patterns were common to all samples but assembly and resulting structure were unique for each organic matter. Thus, XAD fractionation coupled to mass spectroscopy allowed determining a specific fingerprint for each organic matter. Copyright © 2015 Elsevier B.V. All rights reserved.

Effects of bottom water dissolved oxygen variability on copper and lead fractionation in the sediments across the oxygen minimum zone, western continental margin of India.

PubMed

Chakraborty, Parthasarathi; Chakraborty, Sucharita; Jayachandran, Saranya; Madan, Ritu; Sarkar, Arindam; Linsy, P; Nath, B Nagender

2016-10-01

This study describes the effect of varying bottom-water oxygen concentration on geochemical fractionation (operational speciation) of Cu and Pb in the underneath sediments across the oxygen minimum zone (Arabian Sea) in the west coast of India. Both, Cu and Pb were redistributed among the different binding phases of the sediments with changing dissolved oxygen level (from oxic to hypoxic and close to suboxic) in the bottom water. The average lability of Cu-sediment complexes gradually decreased (i.e., stability increased) with the decreasing dissolved oxygen concentrations of the bottom water. Decreasing bottom-water oxygen concentration increased Cu association with sedimentary organic matter. However, Pb association with Fe/Mn-oxyhydroxide phases in the sediments gradually decreased with the decreasing dissolved oxygen concentration of the overlying bottom water (due to dissolution of Fe/Mn oxyhydroxide phase). The lability of Pb-sediment complexes increased with the decreasing bottom-water oxygen concentration. This study suggests that bottom-water oxygen concentration is one of the key factors governing stability and lability of Cu and Pb complexes in the underneath sediment. Sedimentary organic matter and Fe/Mn oxyhydroxide binding phases were the major hosting phases for Cu and Pb respectively in the study area. Increasing lability of Pb-complexes in bottom sediments may lead to positive benthic fluxes of Pb at low oxygen environment. Copyright © 2016 Elsevier B.V. All rights reserved.

Thermodynamics of Molybdate Binding to Humic Acid

NASA Astrophysics Data System (ADS)

Thalhammer, K.; Gilbert, B.

2016-12-01

Molybdenum is an essential nutrient for diazotrophic bacteria that use nitrogenase I to fix atmospheric nitrogen in soils into bioavailable forms such as ammonia. This metalloid is released during rock weathering processes and at neutral pH it exists primarily as the soluble oxyanion molybdate, MoO42-. It has been established that molybdate mobility and bioavailability in soils is influenced by sorption to mineral surfaces and complexation by natural organic matter (NOM). The molybdate ion is readily bound by ortho dihydroxybenzene molecules such as catechol and catechol groups in siderophores. Humic acids (HA) found in NOM contain abundant phenolic groups and extended X-ray absorption fine structure (EXAFS) spectroscopy demonstrated that molybdate is bound by catechol-containing molecules in soil organic matter1. However, to our knowledge no quantitative determination of the affinity of molybdate to HA has been reported. We studied the interactions of molybdate with Suwannee River HA using ultraviolet-visible (UV-vis) absorption spectroscopy and isothermal titration calorimetry (ITC) to determine the conditional equilibrium constant for complexation at neutral pH. We further used ITC to investigate the thermodynamic contributions to complexation and the interaction kinetics. Addition of molybdate to HA caused the formation of complexes with UV-vis absorption spectra in good agreement with molybdate-catechol species indicating catechol groups to be the primary ligands in HA. ITC data revealed that binding enthalpies and kinetics were strongly influenced by ionic strength, suggesting a role for macromolecular reorganization driven by metalloid addition. 1. Wichard et al., Nature Geoscience 2, 625 - 629 (2009).

Origin, transport and burial of organic matter in the Whittard Canyon, North East Atlantic

NASA Astrophysics Data System (ADS)

Kershaw, C. E.

2016-02-01

Submarine canyons, large and complex topographic features commonly found at all continental margins, are usually considered efficient conduits of material to the deep sea that can also harbour varied and well developed ecosystems. Recent work from canyons of the Portuguese margin have revealed a highly heterogeneous environment home to diverse habitats, highlighting the significance of submarine canyons and the need for a more comprehensive understanding of the processes within them. Submarine environments are influenced by the variability of the oceanographic and biogeochemical regimes and the interaction with complex topography. The purpose of this research is to examine the provenance, transportation, burial potential and ecological function of sedimentary organic matter at targeted sites of the Whittard submarine canyon (Celtic Sea, North East Atlantic), one of the largest ( 100 km across, down to 4500 m depth) most complex topographic features in the North Western European Margin, and home to an array of diverse benthic ecosystems. Sediment cores down to 50 cm were collected during three surveys in 2013, 2014 and 2015 at various depths across different channels and sedimentological and biogeochemical analyses have begun. Preliminary results have provided a glimpse of the distinct energy regime of the different canyon channels and differing carbon concentrations, emphasizing the complexity of the system. The project aims to elucidate the significance of the Whittard system in marine biogeochemical cycling and deep-sea ecosystem functioning, through further mineralogical and chemical characterization.

Effects of complexation between organic matter (OM) and clay mineral on OM pyrolysis

NASA Astrophysics Data System (ADS)

Bu, Hongling; Yuan, Peng; Liu, Hongmei; Liu, Dong; Liu, Jinzhong; He, Hongping; Zhou, Junming; Song, Hongzhe; Li, Zhaohui

2017-09-01

The stability and persistence of organic matter (OM) in source rocks are of great significance for hydrocarbon generation and the global carbon cycle. Clay-OM associations commonly occur in sedimentation and diagenesis processes and can influence the pyrolytic behaviors of OM. In this study, clay-OM complexes, i.e., interlayer clay-OM complexes and clay-OM mixture, were prepared and exposed to high-pressure pyrolysis conditions in confined gold capsule reactors to assess variations in OM pyrolysis products in the presence of clay minerals. Three model organic compounds, octadecanoic acid (OA), octadecy trimethyl ammonium bromide (OTAB), and octadecylamine (ODA), were employed and montmorillonite (Mt) was selected as the representative clay mineral. The solid acidity of Mt plays a key role in affecting the amount and composition of the pyrolysis gases generated by the clay-OM complexes. The Brønsted acid sites significantly promote the cracking of hydrocarbons through a carbocation mechanism and the isomerization of normal hydrocarbons. The Lewis acid sites are primarily involved in the decarboxylation reaction during pyrolysis and are responsible for CO2 generation. Mt exhibits either a catalysis effect or pyrolysis-inhibiting during pyrolysis of a given OM depending on the nature of the model organic compound and the nature of the clay-OM complexation. The amounts of C1-5 hydrocarbons and CO2 that are released from the Mt-OA and Mt-ODA complexes were higher than those of the parent OA and ODA, respectively, indicating a catalysis effect of Mt. In contrast, the amount of C1-5 hydrocarbons produced from the pyrolysis of Mt-OTAB complexes was lower than that of OTAB, which we attribute to an inhibiting effect of Mt. This pyrolysis-inhibiting effect works through the Hoffmann elimination that is promoted by the catalysis of the Brønsted acid sites of Mt, therefore releasing smaller amounts of gas hydrocarbons than the nucleophilic reaction that is induced by the halide ions in OTAB. In particular, the interlayer space of Mt acts as an 'amplifier' that magnifies the above-mentioned catalysis or pyrolysis-inhibiting effect, due to the greater number of Brønsted acid sites with high acidity in the interlayer space. These findings are potentially important for understanding the storage and transfer mechanisms of natural OM in sedimentation and diagenesis processes.

Organic matter in central California radiation fogs.

PubMed

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

2002-11-15

Organic matter was studied in radiation fogs in the San Joaquin Valley of California during the California Regional Particulate Air Quality Study (CRPAQS). Total organic carbon (TOC) concentrations ranged from 2 to 40 ppm of C. While most organic carbon was found in solution as dissolved organic carbon (DOC), 23% on average was not dissolved inside the fog drops. We observe a clear variation of organic matter concentration with droplet size. TOC concentrations in small fog drops (<17 microm) were a factor of 3, on average, higher than TOC concentrations in larger drops. As much as half of the dissolved organic matter was determined to have a molecular weight higher than 500 Da. Deposition fluxes of organic matter in fog drops were high (0.5-4.3 microg of C m(-2) min(-1)), indicating the importance of fog processing as a vector for removal of organic matter from the atmosphere. Deposition velocities of organic matter, however, were usually found to be lower than deposition velocities for fogwater, consistent with the enrichment of the organic matter in smaller fog drops with lower terminal settling velocities.

Meteors do not break exogenous organic molecules into high yields of diatomics

NASA Technical Reports Server (NTRS)

Jenniskens, Peter; Schaller, Emily L.; Laux, Christophe O.; Wilson, Michael A.; Schmidt, Greg; Rairden, Rick L.

2004-01-01

Meteoroids that dominate the Earth's extraterrestrial mass influx (50-300 microm size range) may have contributed a unique blend of exogenous organic molecules at the time of the origin of life. Such meteoroids are so large that most of their mass is ablated in the Earth's atmosphere. In the process, organic molecules are decomposed and chemically altered to molecules differently from those delivered to the Earth's surface by smaller (<50 microm) micrometeorites and larger (>10 cm) meteorites. The question addressed here is whether the organic matter in these meteoroids is fully decomposed into atoms or diatomic compounds during ablation. If not, then the ablation products made available for prebiotic organic chemistry, and perhaps early biology, might have retained some memory of their astrophysical nature. To test this hypothesis we searched for CN emission in meteor spectra in an airborne experiment during the 2001 Leonid meteor storm. We found that the meteor's light-emitting air plasma, which included products of meteor ablation, contained less than 1 CN molecule for every 30 meteoric iron atoms. This contrasts sharply with the nitrogen/iron ratio of 1:1.2 in the solid matter of comet 1P/Halley. Unless the nitrogen content or the abundance of complex organic matter in the Leonid parent body, comet 55P/Tempel-Tuttle, differs from that in comet 1P/Halley, it appears that very little of that organic nitrogen decomposes into CN molecules during meteor ablation in the rarefied flow conditions that characterize the atmospheric entry of meteoroids approximately 50 microm-10 cm in size. We propose that the organics of such meteoroids survive instead as larger compounds.

Meteors: A Delivery Mechanism of Organic Matter to The Early Earth

NASA Technical Reports Server (NTRS)

Jenniskens, Peter; Wilson, Mike A.; Packan, Dennis; Laux, Christophe O.; Krueger, Charles H.; Boyd, Iain, D.; Popova, Olga P.; Fonda, Mark; DeVincenzi, Donald L. (Technical Monitor)

2000-01-01

All potential exogenous pre-biotic matter arrived to Earth by ways of our atmosphere, where much material was ablated during a luminous phase called 1. meteors" in rarefied flows of high (up to 270) Mach number. The recent Leonid showers offered a first glimpse into the elusive physical conditions of the ablation process and atmospheric chemistry associated with high-speed meteors. Molecular emissions were detected that trace a meteor's brilliant light to a 4,300 K warm wake rather than to the meteor's head. A new theoretical approach using the direct simulation by Monte Carlo technique identified the source-region and demonstrated that the ablation process is critical in the heating of the meteor's wake. In the head of the meteor, organic carbon appears to survive flash heating and rapid cooling. The temperatures in the wake of the meteor are just right for dissociation of CO and the formation of more complex organic compounds. The resulting materials could account for the bulk of pre-biotic organic carbon on the early Earth at the time of the origin of life.

Removal of natural organic matter from drinking water by advanced oxidation processes.

PubMed

Matilainen, Anu; Sillanpää, Mika

2010-06-01

Over the past 10-20years the amount of the natural organic matter (NOM) has been increased in raw water supplies on several areas. The presence of NOM causes many problems in drinking water treatment processes, including: (i) negative effect on water quality by colour, taste and odor problems, (ii) increased coagulant and disinfectant dose requirements (which in turn results increased sludge and potential harmful disinfection by-product formation), (iii) promoted biological growth in distribution system, and (iv) increased levels of complexed heavy metals and adsorbed organic pollutants. Thus, more efficient methods for the removal of NOM have emerged. Among these are advanced oxidation processes (AOPs). These include O(3)/H(2)O(2), O(3)/UV, UV/H(2)O(2), TiO(2)/UV, H(2)O(2)/catalyst, Fenton and photo-Fenton prosesses as well as ultrasound. In the present work, an overview of the recent research studies dealing with AOP methods for the removal of NOM and related compounds from drinking water is presented.

Evaluating oxidation-reduction properties of dissolved organic matter from Chinese milk vetch (Astragalus sinicus L.): a comprehensive multi-parametric study.

PubMed

Liu, Yong; Lou, Jun; Li, Fang-Bai; Xu, Jian-Ming; Yu, Xiong-Sheng; Zhu, Li-An; Wang, Feng

2014-08-01

Green manuring is a common practice in replenishment of soil organic matter and nutrients in rice paddy field. Owing to the complex interplay of multiple factors, the oxidation--reduction (redox) properties of dissolved organic matter (DOM) from green manure crops are presently not fully understood. In this study, a variety of surrogate parameters were used to evaluate the redox capacity and redox state of DOM derived from Chinese milk vetch (CMV, Astragalus sinicus L.) via microbial decomposition under continuously flooded (CF) and non-flooded (NF) conditions. Additionally, the correlation between the surrogate parameters of CMV-DOM and the kinetic parameters of relevant redox reactions was evaluated in a soil-water system containing CMV-DOM. Results showed that the redox properties of CMV-DOM were substantially different between the fresh and decomposed CMV-DOM treatments. Determination of the surrogate parameters via ultraviolet-visible/Fourier transform infrared absorption spectroscopy and gel permeation chromatography generally provided high-quality data for predicting the redox capacity of CMV-DOM, while the surrogate parameters determined by elemental analysis were suitable for predicting the redox state of CMV-DOM. Depending on the redox capacity and redox state of various moieties/components, NF-decomposed CMV-DOM could easily accelerate soil reduction by shuttling electrons to iron oxides, because it contained more reversible redox-active functional groups (e.g. quinone and hydroquinone pairs) than CF-decomposed CMV-DOM. This work demonstrates that a single index cannot interpret complex changes in multiple factors that jointly determine the redox reactivity of CMV-DOM. Thus, a multi-parametric study is needed for providing comprehensive information on the redox properties of green manure DOM.

Characterization of Whole Porewater Dissolved Organic Matter by 1H NMR

NASA Astrophysics Data System (ADS)

Fox, C.; Lewicki, J. P.; Abdulla, H. A.; Burdige, D.; Magen, C.; Chanton, J.; Komada, T.

2014-12-01

Dissolved organic matter (DOM) is a key intermediate in microbial remineralization of organic matter, but only a small percentage of this complex pool has been fully characterized. We present the results of a novel approach to the characterization of DOM in whole porewater samples from the anoxic sediments of the Santa Barbara Basin, California Borderland, using solution state nuclear magnetic resonance (NMR) techniques. Profiles of porewater DOM were obtained by 1H NMR from 95 to 435 cm sediment depth. 1H NMR spectra of each whole porewater sample showed continuous, broad regions from ~0.5 to ~4.5 ppm, indicative of significant signal overlap inherent to complex mixtures, superimposed on a few highly resolved peaks. The individual samples consist of a broad range of chemical environments with varying relative abundances that show a near linear trend with depth. The normalized spectral data were analyzed by principal component analysis to resolve variations in chemical composition of DOM as a function of depth. In addition to detecting the major components such as carbohydrates, cyclic aliphatics and aromatics, our results demonstrate a negative correlation between carbohydrates concurrent with a relative increase in levels of aliphatics. Furthermore, we have identified a decrease in the abundance of alkenes coupled with an increase in a broad region from ~1.9 to ~3.2 ppm, likely corresponding to signals from carboxylic-rich alicyclic molecules. In both trends, the greatest variation occurs between 115 and 135 cm, which straddles the sulfate-methane transition zone (~125 cm), potentially highlighting a region of relatively high DOM transformation. Our work has also identified thiol species which are thought to be formed by dissolved (inorganic) sulfide incorporation into porewater DOM compounds. The implications of these results with respect to carbon cycling in anaerobic sediments will be discussed.

Metal speciation in landfill leachates with a focus on the influence of organic matter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Claret, Francis, E-mail: f.claret@brgm.fr; Tournassat, Christophe; Crouzet, Catherine

Highlights: > This study characterises the heavy-metal content in leachates collected from eight landfills in France. > Most of the metals are concentrated in the <30 kDa fraction, while Pb, Cu and Cd are associated with larger particles. > Metal complexation with OM is not sufficient to explain apparent supersaturation of metals with sulphide minerals. - Abstract: This study characterises the heavy-metal content in leachates collected from eight landfills in France. In order to identify heavy metal occurrence in the different size fractions of leachates, a cascade filtration protocol was applied directly in the field, under a nitrogen gas atmospheremore » to avoid metal oxidation. The results of analyses performed on the leachates suggest that most of the metals are concentrated in the <30 kDa fraction, while lead, copper and cadmium show an association with larger particles. Initial speciation calculations, without considering metal association with organic matter, suggest that leachate concentrations in lead, copper, nickel and zinc are super-saturated with respect to sulphur phases. Speciation calculations that account for metal complexation with organic matter, considered as fulvic acids based on C1(s) NEXAFS spectroscopy, show that this mechanism is not sufficient to explain such deviation from equilibrium conditions. It is therefore hypothesized that the deviation results also from the influence of biological activity on the kinetics of mineral phase precipitation and dissolution, thus providing a dynamic system. The results of chemical analyses of sampled fluids are compared with speciation calculations and some implications for the assessment of metal mobility and natural attenuation in a context of landfill risk assessment are discussed.« less

Complexity of Bacterial Communities in a River-Floodplain System (Danube, Austria)

PubMed Central

Besemer, Katharina; Moeseneder, Markus M.; Arrieta, Jesus M.; Herndl, Gerhard J.; Peduzzi, Peter

2005-01-01

Natural floodplains play an essential role in the processing and decomposition of organic matter and in the self-purification ability of rivers, largely due to the activity of bacteria. Knowledge about the composition of bacterial communities and its impact on organic-matter cycling is crucial for the understanding of ecological processes in river-floodplain systems. Particle-associated and free-living bacterial assemblages from the Danube River and various floodplain pools with different hydrological characteristics were investigated using terminal restriction fragment length polymorphism analysis. The particle-associated bacterial community exhibited a higher number of operational taxonomic units (OTUs) and was more heterogeneous in time and space than the free-living community. The temporal dynamics of the community structure were generally higher in isolated floodplain pools. The community structures of the river and the various floodplain pools, as well as those of the particle-associated and free-living bacteria, differed significantly. The compositional dynamics of the planktonic bacterial communities were related to changes in the algal biomass, temperature, and concentrations of organic and inorganic nutrients. The OTU richness of the free-living community was correlated with the concentration and origin of organic matter and the concentration of inorganic nutrients, while no correlation with the OTU richness of the particle-associated assemblage was found. Our results demonstrate the importance of the river-floodplain interactions and the influence of damming and regulation on the bacterial-community composition. PMID:15691909

Thallium and Silver binding to dissolved organic matter

NASA Astrophysics Data System (ADS)

Benedetti, M. F.; Martin, L.; Simonucci, C.; Viollier, E.

2017-12-01

Silver (Ag) and thallium (Tl) are potential contaminants at the vicinity of mining sites and are harmful pollutants. Silver can be found in mine but also as released by the dissolution of Silver nanoparticles, a major new emerging contaminant. Tl is both lithophilic and calcophilic elements and found in sulphur ores (associated with lead, zinc, antimony…) or in rocks containing K-feldspar. Speciation of Ag and Tl is poorly known mainly due to their low concentrations in aquatic environments. Review of Ag and Tl geochemistry clearly shows a lack of quantitative information about interactions with natural organic matter. Organic ligands could play an important role in Ag or Tl bioavailability, chemical reactivity (adsorption or photo oxidation inhibition or catalysis) and hence geochemical transfers. Based on equilibrium between two solutions that are separated by a selectively permeable membrane, the so-called "Donnan membrane technique" (DMT) provides a measure of free ion concentrations. Analytes measurements are performed by HR-ICP-MS Element 2 (Thermo Scientific). Experimental setup allows the Donnan equilibrium to be reached after 100 and 120 hours for Tl. Experiments performed with purified natural organic matter allow calculating complexation constants in multiple pH conditions. With this work, we contribute new data and interpretations to an active debate on Ag and Tl geochemical modeling. In conclusion, this work brings a new view on risk assessment for mining activities.

Shape-preserving transformations of organic matter and compositions thereof

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kaehr, Bryan J.; Meyer, Kristin; Townson, Jason L.

The present invention relates to methods of transforming organic matter into organic-inorganic composites, inorganic replicas, or conductive replicas. Organic matter, such as biological cells and tissue and organs, can be converted into such composites and replicas using the methods described herein. In particular, such methods transform organic matter (into inorganic, organic-inorganic, or conductive constructs), while simultaneously preserving microscopic and/or macroscopic structural detail.

Characterization of Natural Organic Matter in Low-Carbon Environments: Extraction and Analytical Approaches

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fox, Patricia M.; Nico, Peter S.; Tfaily, Malak M.

2017-12-31

Sediment-associated natural organic matter (NOM) is a complex assemblage of organic molecules with a wide range of sizes, functional groups, and structures, which is intricately associated with mineral particles. Organic carbon (OC) concentrations in subsurface sediments are typically 10 to 200 times lower than in surface soils, posing a distinct challenge for characterization. A range of chemical extractions were evaluated for extraction of NOM, and a NOM extraction scheme was developed using a combination of sequential extraction with water (MQ) and sodium pyrophosphate at pH 10 (PP), and purification by dialysis and solid phase extraction in order to isolate differentmore » fractions of sediment-associated NOM. Analysis of these different NOM fractions was then carried out by Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible (UV-Vis) spectroscopy, and electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FTICR-MS). The OC extraction efficiency of the tested extractions followed the order PP>NaOH>HCl=hydroxylamine hydrochloride>dithionite. Greater concentrations of OC in PP vs NaOH extracts suggest that metal complexation and/or ligand exchange plays an important role in OC stabilization. Characterization of different pools of extraction NOM by FITR shows that the water soluble fraction has a higher fraction of aliphatic and carboxylic groups, while the PP fractions have higher C=C groups. This trend from aliphatic to more aromatic is also supported by the UV-Vis and ESI-FTICR-MS data.« less

Characterization of natural organic matter in low-carbon sediments: Extraction and analytical approaches

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fox, Patricia M.; Nico, Peter S.; Tfaily, Malak M.

Sediment-associated natural organic matter (NOM) is a complex assemblage of organic molecules with a wide range of sizes, functional groups, and structures, which is intricately associated with mineral particles. Organic carbon (OC) concentrations in subsurface sediments are typically 10 to 200 times lower than in surface soils, posing a distinct challenge for characterization. A range of chemical extractions were evaluated for extraction of NOM, and a NOM extraction scheme was developed using a combination of sequential extraction with water (MQ) and sodium pyrophosphate at pH 10 (PP), and purification by dialysis and solid phase extraction in order to isolate differentmore » fractions of sediment-associated NOM. Analysis of these different NOM fractions was then carried out by Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible (UV-Vis) spectroscopy, and electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FTICR-MS). The OC extraction efficiency of the tested extractions followed the order PP>NaOH>HCl=hydroxylamine hydrochloride>dithionite. Greater concentrations of OC in PP vs NaOH extracts suggest that metal complexation and/or ligand exchange plays an important role in OC stabilization. Characterization of different pools of extraction NOM by FITR shows that the water soluble fraction has a higher fraction of aliphatic and carboxylic groups, while the PP fractions have higher C=C groups. This trend from aliphatic to more aromatic is also supported by the UV-Vis and ESI-FTICR-MS data.« less

Opposing effects of different soil organic matter fractions on crop yields.

PubMed

Wood, Stephen A; Sokol, Noah; Bell, Colin W; Bradford, Mark A; Naeem, Shahid; Wallenstein, Matthew D; Palm, Cheryl A

2016-10-01

Soil organic matter is critical to sustainable agriculture because it provides nutrients to crops as it decomposes and increases nutrient- and water-holding capacity when built up. Fast- and slow-cycling fractions of soil organic matter can have different impacts on crop production because fast-cycling fractions rapidly release nutrients for short-term plant growth and slow-cycling fractions bind nutrients that mineralize slowly and build up water-holding capacity. We explored the controls on these fractions in a tropical agroecosystem and their relationship to crop yields. We performed physical fractionation of soil organic matter from 48 farms and plots in western Kenya. We found that fast-cycling, particulate organic matter was positively related to crop yields, but did not have a strong effect, while slower-cycling, mineral-associated organic matter was negatively related to yields. Our finding that slower-cycling organic matter was negatively related to yield points to a need to revise the view that stabilization of organic matter positively impacts food security. Our results support a new paradigm that different soil organic matter fractions are controlled by different mechanisms, potentially leading to different relationships with management outcomes, like crop yield. Effectively managing soils for sustainable agriculture requires quantifying the effects of specific organic matter fractions on these outcomes. © 2016 by the Ecological Society of America.

Deccesion of peat-moorsh soils under different land use

NASA Astrophysics Data System (ADS)

Lipka, K.; Zając, E.

2009-04-01

Use of peatlands has a serious impact on soil properties as well as on loss of organic matter. On the basis of survey carried out in 1976, 1993 and 2001 in the Mrowla river valley near Rzeszow, authors analysed changes of the peat-moorsh soils under different land use. The 25- year period was analysed. Survey results comprised: loss of organic matter, advance of moorsh forming process and change of prognostic soil-moisture complexes (after Okruszko). Stratigraphic profiles made in the years1996-2001 were compared and rate of organic mass loss was calculated. The highest values were stated for ploughfields with crop rotation (root plants, industrial plants and cereals). Intensified soil aeration and moorsh forming process as well as wind erosion caused gradual lowering of ground level. Depth of degraded peat layer in roof of surveyed peat deposits was between 0,2 and 0,8 m. Ground surface was lowering of 1,68 cm per year. It was found that, for ploughfields especially, peat-moorhs soil showing medium degree of moorsh forming process (MtII) and prognostic soil-moisture complex BC (periodically drying), after 17 years already, had changed into a soil with high degree of moorsh forming process (MtIII) and prognostic soil-moisture complex C (drying). For meadows and pastures land used such evident change wasn't noticed. During the whole investigation period (25 years) mean lowering of the peat-moorsh soils level along transects lines for different land use was: 1,15 cm per year for meadows and pastures, 1,58 cm pea year for plougfields and 1,38 cm per year for alder wood.

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 replacement for conventional solvent extraction of sedimentary rocks, but can also be used for any organic matter containing mineral matrix, including soils and recent sediments, and has the added benefit of tailored extraction for analytes of specific polarities. Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.

Characterization of organic matter in lake sediments from Minnesota and Yellowstone National Park

USGS Publications Warehouse

Dean, Walter E.

2006-01-01

Samples of sediment from lakes in Minnesota and Yellowstone National Park (YNP) were analyzed for organic carbon (OC), hydrogen richness by Rock-Eval pyrolysis, and stable carbon- and nitrogen-isotope composition of bulk organic matter. Values of delta 13C of lake plankton tend to be around -28 to -32 parts per thousand (0/00). Organic matter with values of delta 13C in the high negative 20s overlap with those of organic matter derived from C3 higher terrestrial plants but are at least 10 0/00 more depleted in 13C than organic matter derived from C4 terrestrial plants. If the organic matter is produced mainly by photosynthetic plankton and is not oxidized in the water column, there may be a negative correlation between H-richness (Rock-Eval pyrolysis H-index) and delta 13C, with more H-rich, algal organic matter having lower values of delta 13C. However, if aquatic organic matter is oxidized in the water column, or if the organic matter is a mixture of terrestrial and aquatic organic matter, then there may be no correlation between H-richness and carbon-isotopic composition. Values of delta 13C lower than about -28 0/00 probably indicate a contribution of bacterial biomass produced in the hypolimnion by chemoautotrophy or methanotrophy. In highly eutrophic lakes in which large amounts of 13C-depleted organic matter is continually removed from the epilimnion by photosynthesis throughout the growing season, the entire carbon reservoir in the epilimnion may become severely 13C-enriched so that 13C-enriched photosynthetic organic matter may overprint 13C-depleted chemosynthetic bacterial organic matter produced in the hypolimnon. Most processes involved with the nitrogen cycle in lakes, such as production of ammonia and nitrate, tend to produce 15N-enriched values of delta 15N. Most Minnesota lake sediments are 15N-enriched. However, some of the more OC-rich sediments have delta 15N values close to zero (delta 15N of air), suggesting that organic matter production is by nitrogen fixation, which further implies that nitrogen is limiting. Most lakes from YNP also have values of delta 15N near zero.

Perchlorate-induced combustion of organic matter with variable molecular weights: Implications for Mars missions

NASA Astrophysics Data System (ADS)

Sephton, Mark A.; Lewis, James M. T.; Watson, Jonathan S.; Montgomery, Wren; Garnier, Carole

2014-11-01

Instruments on the Viking landers and Curiosity rover analyzed samples of Mars and detected carbon dioxide and organic compounds of uncertain origin. Mineral-assisted reactions are leading to uncertainty, particularly those involving perchlorate minerals which thermally decompose to produce chlorine and oxygen which can then react with organic matter to generate organochlorine compounds and carbon dioxide. Although generally considered a problem for interpretation, the release profiles of generated gases can indicate the type of organic matter present. We have performed a set of experiments with perchlorate and organic matter of variable molecular weights. Results indicate that organic susceptibility to thermal degradation and mineral-assisted reactions is related to molecular weight. Low molecular weight organic matter reacts at lower temperatures than its high molecular weight counterparts. The natural occurrence and association of organic matter with differing molecular weights helps to discriminate between contamination (usually low molecular weight organic matter only) and indigenous carbon (commonly low and high molecular weight organic matter together). Our results can be used to provide insights into data returning from Mars.

Mosaic, self-similarity logic, and biological attraction principles: three explanatory instruments in biology.

PubMed

Agnati, Luigi F; Baluska, Frantisek; Barlow, Peter W; Guidolin, Diego

2009-11-01

From a structural standpoint, living organisms are organized like a nest of Russian matryoshka dolls, in which structures are buried within one another. From a temporal point of view, this type of organization is the result of a history comprised of a set of time backcloths which have accompanied the passage of living matter from its origins up to the present day. The aim of the present paper is to indicate a possible course of this 'passage through time, and suggest how today's complexity has been reached by living organisms. This investigation will employ three conceptual tools, namely the Mosaic, Self-Similarity Logic, and the Biological Attraction principles. Self-Similarity Logic indicates the self-consistency by which elements of a living system interact, irrespective of the spatiotemporal level under consideration. The term Mosaic indicates how, from the same set of elements assembled according to different patterns, it is possible to arrive at completely different constructions: hence, each system becomes endowed with different emergent properties. The Biological Attraction principle states that there is an inherent drive for association and merging of compatible elements at all levels of biological complexity. By analogy with the gravitation law in physics, biological attraction is based on the evidence that each living organism creates an attractive field around itself. This field acts as a sphere of influence that actively attracts similar fields of other biological systems, thereby modifying salient features of the interacting organisms. Three specific organizational levels of living matter, namely the molecular, cellular, and supracellular levels, have been considered in order to analyse and illustrate the interpretative as well as the predictive roles of each of these three explanatory principles.

Advanced solvent based methods for molecular characterization of soil organic matter by high-resolution mass spectrometry.

PubMed

Tfaily, Malak M; Chu, Rosalie K; Tolić, Nikola; Roscioli, Kristyn M; Anderton, Christopher R; Paša-Tolić, Ljiljana; Robinson, Errol W; Hess, Nancy J

2015-01-01

Soil organic matter (SOM), a complex, heterogeneous mixture of above and belowground plant litter and animal and microbial residues at various degrees of decomposition, is a key reservoir for carbon (C) and nutrient biogeochemical cycling in soil based ecosystems. A limited understanding of the molecular composition of SOM limits the ability to routinely decipher chemical processes within soil and accurately predict how terrestrial carbon fluxes will respond to changing climatic conditions and land use. To elucidate the molecular-level structure of SOM, we selectively extracted a broad range of intact SOM compounds by a combination of different organic solvents from soils with a wide range of C content. Our use of electrospray ionization (ESI) coupled with Fourier transform ion cyclotron resonance mass spectrometry (FTICR MS) and a suite of solvents with varying polarity significantly expands the inventory of the types of organic molecules present in soils. Specifically, we found that hexane is selective for lipid-like compounds with very low O/C ratios (<0.1); water (H2O) was selective for carbohydrates with high O/C ratios; acetonitrile (ACN) preferentially extracts lignin, condensed structures, and tannin polyphenolic compounds with O/C > 0.5; methanol (MeOH) has higher selectivity toward compounds characterized with low O/C < 0.5; and hexane, MeOH, ACN, and H2O solvents increase the number and types of organic molecules extracted from soil for a broader range of chemically diverse soil types. Our study of SOM molecules by ESI FTICR MS revealed new insight into the molecular-level complexity of organics contained in soils. We present the first comparative study of the molecular composition of SOM from different ecosystems using ultra high-resolution mass spectrometry.

Mosaic, Self-Similarity Logic, and Biological Attraction principles

PubMed Central

Baluška, František; Barlow, Peter W; Guidolin, Diego

2009-01-01

From a structural standpoint, living organisms are organized like a nest of Russian matryoshka dolls, in which structures are buried within one another. From a temporal point of view, this type of organization is the result of a history comprised of a set of time backcloths which have accompanied the passage of living matter from its origins up to the present day. The aim of the present paper is to indicate a possible course of this ‘passage through time, and suggest how today’s complexity has been reached by living organisms. This investigation will employ three conceptual tools, namely the Mosaic, Self-Similarity Logic, and the Biological Attraction principles. Self-Similarity Logic indicates the self-consistency by which elements of a living system interact, irrespective of the spatiotemporal level under consideration. The term Mosaic indicates how, from the same set of elements assembled according to different patterns, it is possible to arrive at completely different constructions: hence, each system becomes endowed with different emergent properties. The Biological Attraction principle states that there is an inherent drive for association and merging of compatible elements at all levels of biological complexity. By analogy with the gravitation law in physics, biological attraction is based on the evidence that each living organism creates an attractive field around itself. This field acts as a sphere of influence that actively attracts similar fields of other biological systems, thereby modifying salient features of the interacting organisms. Three specific organizational levels of living matter, namely the molecular, cellular, and supracellular levels, have been considered in order to analyse and illustrate the interpretative as well as the predictive roles of each of these three explanatory principles. PMID:20195461

Soil mixing and transport increase inventories of mineral surface area and organic carbon, with systematic shifts in C/N, δ13C, and δ15N, along a forested hillslope transect

NASA Astrophysics Data System (ADS)

Fisher, B.; Yoo, K.; Aufdenkampe, A. K.; Nater, E. A.; Aalto, R. E.; Marquard, J.

2017-12-01

The quantity of organic carbon (OC) per unit of mineral surface area (OC/SA) and the inventory of organic carbon increased by a factor of 2-3 as result of soil mixing due to soil creep, erosional movement, and in situ mixing process in a soil transect in a first-order forested watershed in the Christina River Basin Critical Zone Observatory. In the uppermost 5 meters, 50-75% of mineral specific surface area was contributed by citrate-dithionate extractable forms of iron and aluminum that comprised less than 2.5% of the total sample mass. As soils were redistributed to depositional landscape positions, mixing processes systematically decreased C/N and enriched stable isotopes of C ( δ13C) and N ( δ15N). Radiocarbon (14C) concentration of light and dense fraction OC (divided at 2.0 g cm-3), increased with depth, but results of light fraction radiocarbon were obscured by 3000-year-old charcoal. Short range order Fe- and Al-bearing minerals contributed the vast majority of specific surface area, and this finding has implications for the stability and longevity of organomineral complexes. We identified a strong correlation between C/N and the ratio of OC to mineral surface area (OC/SA), indicating that the processes that associate organic matter and minerals are fundamentally linked with organic matter composition, and both properties may provide a proxy for organic matter stabilization by soil minerals.

Influence of anoxic pore water dissolved organic matter on the fate and transport of hydrophobic organic pollutants

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hunchak-Kariouk, K.

1992-01-01

Pore water dissolved organic matter is an overlooked pool of organic matter important to the environmental fate of hydrophobic organic pollutants. The association of polychlorinated biphenyls, polyaromatic hydrocarbons and chlorinated pesticides with pore water dissolved organic matter influences their distribution and mobility within the bottom sediment environment. Steep physical, biological and chemical gradients at the sediment/water interface isolate the pore water and create unique conditions within the sediment. This study indicates that any disturbance of this environment will alter the distribution and mobility of organic pollutants by changing their association to the pore water dissolved organic matter. A small volumemore » closed equilibration method was developed to measure the solubility enhancement of 2,2' 4,4'-tetrachlorobiphenyl (TeCB) by natural dissolved organic matter. Chemical coated micro-glass beads were equilibrated with anoxic and laboratory aerated (oxic) pore water samples in flame sealed ampules. The TeCB enhanced solubilities were used to determine the pore water dissolved organic matter partition coefficient, K[sub pwdom]. The measured TeCB solubility and K[sub pwdom] were much smaller for anoxic than oxic pore waters. The dissolved organic matter sorptive capacity for the TeCB increased as the water was aerated. This change is attributed to coagulative fractionation and structural changes of the pore water dissolved organic matter during aeration and was characterized by differences in the dissolved organic matter concentration, UV absorption at 254 nm, interfacial surface tension, and sorption capacity of molecular weight fractions of anoxic and oxic pore water dissolved organic matter. The increase in partitioning indicates that there will be an increase in the mobility of the TeCB as an anoxic bottom sediment environment is disturbed and aerated.« less

Impacts of heterogeneous organic matter on phenanthrene sorption--Equilibrium and kinetic studies with aquifer material

USGS Publications Warehouse

Karapanagioti, Hrissi K.; Kleineidam, Sybille; Sabatini, David A.; Grathwohl, Peter; Ligouis, Bertrand

2000-01-01

Sediment organic matter heterogeneity in sediments is shown to impact the sorption behavior of contaminants. We investigated the sorptive properties as well as the composition of organic matter in different subsamples (mainly grain size fractions) of the Canadian River Alluvium (CRA). Organic petrography was used as a new tool to describe and characterize the organic matter in the subsamples. The samples studied contained many different types of organic matter including bituminous coal particles. Differences in sorption behavior were explained based on these various types of organic matter. Subsamples containing predominately coaly, particulate organic matter showed the highest Koc, the highest nonlinearity of sorption isotherms and the slowest sorption kinetics. Soil subsamples with organic matter present as organic coatings around the quartz grains evidenced the lowest Koc, the most linear sorption isotherms and the fastest sorption kinetics, which was not limited by slow intraparticle diffusion. Due to the high sorption capacity of the coaly particles even when it is present as only a small fraction of the composite organic content (<3%) causes Koc values which are much higher than expected for soil organic matter (e.g. Koc − Kow relationships). The results show that the identification and quantification of the coaly particles within a sediment or soil sample is a prerequisite in order to understand or predict sorption behavior of organic pollutants.

Organic Carbon Release from Groundwater Sediments under Changing Geochemical Conditions

NASA Astrophysics Data System (ADS)

Tinnacher, R. M.; Bhattacharyya, A.; Fox, P. M.; Nico, P. S.

2016-12-01

Due to climate change, local weather patterns are expected to change, especially with respect to precipitation, the frequency of extreme storm water events, and `drought-like' conditions. This in turn, may affect groundwater recharge, the geochemical conditions in natural groundwater systems, and the chemical and microbiological processes involved in organic matter degradation. Besides the complexity of organic matter structures and local limitations in nutrients, the association of organic carbon with sediment minerals can strongly limit organic matter bioaccessability and degradability. In this study, we investigate how variations in groundwater chemistry, e.g. with respect to dissolved CO2 concentrations, may potentially affect the release of natural organic carbon from groundwater sediments, and render organic matter more bioaccessible. In lab-scale experiments under anaerobic conditions, aquifer sediments from the floodplain of the Colorado River (Rifle, USA) were brought into contact with fresh, organic-carbon free groundwater solutions, at natural or reduced CO2 concentration levels. During the repeated exchange of solutions at two temperature settings (room-temperature and 4 °C), supernatant solutions were characterized in terms of pH, dissolved metal and organic carbon (OC) concentrations, and potential changes in released OC characteristics. Sediment samples were evaluated for possible differences in Fe-speciation before and after the experiment based on EXAFS (bulk Fe K-edge). Preliminary results for 20 exchanges of groundwater solutions show a repeated release of low OC concentrations ( 0.5-2 mg OC/g sediment; 0.05-0.2% of sediment-associated OC) without any apparent depletion in the overall source term over 50 days. After 14 days, room-temperature samples released slightly higher OC concentrations than samples kept at 4 °C. An increase in solution pH, after switching to a `CO2-free' groundwater solution, did not trigger a higher OC release. Last, specific UV absorbance measurements for room-temperature samples suggest changes in released OC characteristics due to repeated solution exchanges. Additional sample characterization is ongoing, with the goal to elucidate potential changes in released OC characteristics over the course of the experiment.

Photocatalytic degradation of carbamazepine, clofibric acid and iomeprol with P25 and Hombikat UV100 in the presence of natural organic matter (NOM) and other organic water constituents.

PubMed

Doll, Tusnelda E; Frimmel, Fritz H

2005-01-01

The photocatalytic degradation of natural organic matter (NOM) and organic substance mixtures under simulated solar UV light has been investigated with suspended TiO(2). It could be shown by size-exclusion chromatography that photocatalysis of NOM led to a reduction of the average hydrodynamic radii and presumably of the nominal molecular weight, too. The decrease of the UV/Vis absorption of NOM was faster than the NOM mineralization. This study also focuses on the different abilities of photocatalytic materials (P25 and Hombikat UV100) to decrease persistent substances influenced by the presence of NOM and mixtures of pharmaceuticals or diagnostic agents. In general, the presence of NOM and other organic substances retarded the photocatalysis of a specific persistent substance by the combination of radiation attenuation, competition for active sites and surface deactivation of the catalyst by adsorption. The results of this work prove that photocatalysis is a promising technology to reduce persistent substances like NOM, carbamazepine, clofibric acid, iomeprol and iopromide even if they are present in a complex matrix.

Shape-tailored polymer colloids on the road to become structural motifs for hierarchically organized materials.

PubMed

Plüisch, Claudia Simone; Wittemann, Alexander

2013-12-01

Anisometric polymer colloids are likely to behave differently when compared with centrosymmetric particles. Their study may not only shine new light on the organization of matter; they may also serve as building units with specific symmetries and complexity to build new materials from them. Polymer colloids of well-defined complex geometries can be obtained by packing a limited number of spherical polymer particles into clusters with defined configurations. Such supracolloidal architectures can be fabricated at larger scales using narrowly dispersed emulsion droplets as templates. Assemblies built from at least two different types of particles as elementary building units open perspectives in selective targeting of colloids with specific properties, aiming for mesoscale building blocks with tailor-made morphologies and multifunctionality. Polymer colloids with defined geometries are also ideal to study shape-dependent properties such as the diffusion of complex particles. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Soil organic matter composition affected by potato cropping managements

USDA-ARS?s Scientific Manuscript database

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...

Size does Matter

NASA Astrophysics Data System (ADS)

Vespignani, Alessandro

From schools of fish and flocks of birds, to digital networks and self-organizing biopolymers, our understanding of spontaneously emergent phenomena, self-organization, and critical behavior is in large part due to complex systems science. The complex systems approach is indeed a very powerful conceptual framework to shed light on the link between the microscopic dynamical evolution of the basic elements of the system and the emergence of oscopic phenomena; often providing evidence for mathematical principles that go beyond the particulars of the individual system, thus hinting to general modeling principles. By killing the myth of the ant queen and shifting the focus on the dynamical interaction across the elements of the systems, complex systems science has ushered our way into the conceptual understanding of many phenomena at the core of major scientific and social challenges such as the emergence of consensus, social opinion dynamics, conflicts and cooperation, contagion phenomena. For many years though, these complex systems approaches to real-world problems were often suffering from being oversimplified and not grounded on actual data...

Did CDM particles of mass 2.47 x 10(-3) eV interact with precursor biopolymers and nucleic acids to initiate and boost lifeforms on Earth?

PubMed

Rosen, Gerald

2011-06-01

Recent observations and theoretical studies have shown that non-baryonic Cold Dark Matter (CDM), which constitutes about 84% of all matter in the Universe, may feature a complex-scalar-field that carries particles of mass ≅ 2.47 x 10(-3)eV with the associated Compton range m(-1) ≅8.02 x 10(-3) cm, a distance on the scale of extended bionucleic acids and living cells. Such a complex-scalar-field can enter a weak-isospin Lorentz-invariant interaction that generates the flow of right-handed electrons and induces a chirality-imbued quantum chemistry on the m (-1) scale. A phenomenological Volterra-type equation is proposed for the CDM-impacted time development of N, the number of base pairs in the most advanced organism at Earth-age t. The solution to this equation suggests that the boosts in N at t ≅ 1.1 Gyr (advent of the first living prokaryotic cells), at t ≅ 2.9 Gyr (advent of eukaryotic single-celled organisms) and finally at t ≅ 4.0 Gyr (the Cambrian explosion) may be associated with three multi-Myr-duration cosmic showers of the complex-scalar-field CDM particles. If so, the signature of the particles may be detectible in Cambrian rocks.

Insights into the interaction between carbamazepine and natural dissolved organic matter in the Yangtze Estuary using fluorescence excitation-emission matrix spectra coupled with parallel factor analysis.

PubMed

Wang, Ying; Zhang, Manman; Fu, Jun; Li, Tingting; Wang, Jinggang; Fu, Yingyu

2016-10-01

The interaction between carbamazepine (CBZ) and dissolved organic matter (DOM) from three zones (the nearshore, the river channel, and the coastal areas) in the Yangtze Estuary was investigated using fluorescence quenching titration combined with excitation emission matrix spectra and parallel factor analysis (PARAFAC). The complexation between CBZ and DOM was demonstrated by the increase in hydrogen bonding and the disappearance of the C=O stretch obtained from the Fourier transform infrared spectroscopy analysis. The results indicated that two protein-like substances (component 2 and component3) and two humic-like substances (component 1 and 4) were identified in the DOM from the Yangtze Estuary. The fluorescence quenching curves of each component with the addition of CBZ and the Ryan and Weber model calculation results both demonstrated that the different components exhibited different complexation activities with CBZ. The protein-like components had a stronger affinity with CBZ than did the humic-like substances. On the other hand, the autochthonous tyrosine-like C2 played an important role in the complexation with DOM from the river channel and coastal areas, while C3 influenced by anthropogenic activities showed an obvious effect in the nearshore area. DOMs from the river channel have the highest binding capacity for CBZ, which may ascribe to the relatively high phenol content group in the DOM.

A Free Accessible Individual-Based Simulator Enabling Virtual Experiments on Soil Organic Matter Processes in Classroom

ERIC Educational Resources Information Center

Gras, Anna; Cañadas, Juan Carlos; Ginovart, Marta

2013-01-01

This work addresses and aims to fulfill a very clear need in teaching biosystem engineering. When introducing students to the complexity of soil processes, one of the frustrations that teachers often experience is the impossibility to demonstrate practically, in the lab, some of the concepts and processes discussed in class. Either the experiments…

So That's Where We Came from! A Short History of Higher Education

ERIC Educational Resources Information Center

Gratto, Fred

2010-01-01

Working on a college campus is pretty special. There is always something fun going on, sporting events to watch, lots of interesting opportunities to help people, and the setting to do work that really matters. Colleges are complex organizations, so it is good to have a broad institutional perspective to better understand what people do and why…

Aggregation and Stability of Reduced Graphene Oxide: Complex Roles of Divalent Cations, pH, and Natural Organic Matter

EPA Science Inventory

The aggregation and stability of graphene oxide (GO) and three successively reduced GO (rGO) nanomaterials were investigated. Reduced GO species were partially reduced GO (rGO-1h), intermediately reduced GO (rGO-2h), and fully reduced GO (rGO-5h). Specifically, influence of pH, i...

Isotopic characteristics of simulated meteoritic organic matter. I - Kerogen-like material

NASA Technical Reports Server (NTRS)

Kerridge, John F.; Mariner, Ruth; Flores, Jose; Chang, Sherwood

1989-01-01

Carbonaceous residues from a variety of laboratory syntheses yield release patterns for C and H isotopes during stepwise combustion that fail to mimic the striking patterns characteristic of meteoritic kerogen-like residues that otherwise superficially resemble them. It seems likely that the meteoritic material comprises a complex mixture of substances having different origins and/or synthesis conditions.

Context Matters: The Value of Analyzing Human Factors within Educational Contexts as a Way of Informing Technology-Related Decisions within Design Research

ERIC Educational Resources Information Center

MacKinnon, Kim

2012-01-01

While design research can be useful for designing effective technology integrations within complex social settings, it currently fails to provide concrete methodological guidelines for gathering and organizing information about the research context, or for determining how such analyses ought to guide the iterative design and innovation process. A…

Fungal community composition in soils subjected to long-term chemical fertilization is most influenced by the type of organic matter.

PubMed

Sun, Ruibo; Dsouza, Melissa; Gilbert, Jack A; Guo, Xisheng; Wang, Daozhong; Guo, Zhibin; Ni, Yingying; Chu, Haiyan

2016-12-01

Organic matter application is a widely used practice to increase soil carbon content and maintain soil fertility. However, little is known about the effect of different types of organic matter, or the input of exogenous species from these materials, on soil fungal communities. In this study, fungal community composition was characterized from soils amended with three types of organic matter over a 30-year fertilization experiment. Chemical fertilization significantly changed soil fungal community composition and structure, which was exacerbated by the addition of organic matter, with the direction of change influenced by the type of organic matter used. The addition of organic matter significantly increased soil fungal richness, with the greatest richness achieved in soils amended with pig manure. Importantly, following addition of cow and pig manure, fungal taxa associated with these materials could be found in the soil, suggesting that these exogenous species can augment soil fungal composition. Moreover, the addition of organic matter decreased the relative abundance of potential pathogenic fungi. Overall, these results indicate that organic matter addition influences the composition and structure of soil fungal communities in predictable ways. © 2016 Society for Applied Microbiology and John Wiley & Sons Ltd.

Development of liquid chromatography high resolution mass spectrometry strategies for the screening of complex organic matter: Application to astrophysical simulated materials.

PubMed

Eddhif, Balkis; Allavena, Audrey; Liu, Sylvie; Ribette, Thomas; Abou Mrad, Ninette; Chiavassa, Thierry; d'Hendecourt, Louis Le Sergeant; Sternberg, Robert; Danger, Gregoire; Geffroy-Rodier, Claude; Poinot, Pauline

2018-03-01

The present work aims at developing two LC-HRMS setups for the screening of organic matter in astrophysical samples. Their analytical development has been demonstrated on a 100-µg residue coming from the photo-thermo chemical processing of a cometary ice analog produced in laboratory. The first 1D-LC-HRMS setup combines a serially coupled columns configuration with HRMS detection. It has allowed to discriminate among different chemical families (amino acids, sugars, nucleobases and oligopeptides) in only one chromatographic run without neither a priori acid hydrolysis nor chemical derivatisation. The second setup is a dual-LC configuration which connects a series of trapping columns with analytical reverse-phase columns. By coupling on-line these two distinct LC units with a HRMS detection, high mass compounds (350

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.

Microbial genomics, transcriptomics and proteomics: new discoveries in decomposition research using complementary methods.

PubMed

Baldrian, Petr; López-Mondéjar, Rubén

2014-02-01

Molecular methods for the analysis of biomolecules have undergone rapid technological development in the last decade. The advent of next-generation sequencing methods and improvements in instrumental resolution enabled the analysis of complex transcriptome, proteome and metabolome data, as well as a detailed annotation of microbial genomes. The mechanisms of decomposition by model fungi have been described in unprecedented detail by the combination of genome sequencing, transcriptomics and proteomics. The increasing number of available genomes for fungi and bacteria shows that the genetic potential for decomposition of organic matter is widespread among taxonomically diverse microbial taxa, while expression studies document the importance of the regulation of expression in decomposition efficiency. Importantly, high-throughput methods of nucleic acid analysis used for the analysis of metagenomes and metatranscriptomes indicate the high diversity of decomposer communities in natural habitats and their taxonomic composition. Today, the metaproteomics of natural habitats is of interest. In combination with advanced analytical techniques to explore the products of decomposition and the accumulation of information on the genomes of environmentally relevant microorganisms, advanced methods in microbial ecophysiology should increase our understanding of the complex processes of organic matter transformation.

Dynamics of particle export on the Northwest Atlantic margin

NASA Astrophysics Data System (ADS)

Hwang, Jeomshik; Manganini, Steven J.; Montluçon, Daniel B.; Eglinton, Timothy I.

2009-10-01

The Northwest Atlantic margin is characterized by high biological productivity in shelf and slope surface waters. In addition to carbon supply to underlying sediments, the persistent, intermediate depth nepheloid layers emanating from the continental shelves, and bottom nepheloid layers maintained by strong bottom currents associated with the southward flowing Deep Western Boundary Current (DWBC), provide conduits for export of organic carbon over the margin and/or to the interior ocean. As a part of a project to understand dynamics of particulate organic carbon (POC) cycling in this region, we examined the bulk and molecular properties of time-series sediment trap samples obtained at 968 m, 1976 m, and 2938 m depths from a bottom-tethered mooring on the New England slope (water depth, 2988 m). Frequent occurrences of higher fluxes in deep relative to shallower sediment traps and low Δ 14C values of sinking POC together provide strong evidence for significant lateral transport of aged organic matter over the margin. Comparison of biogeochemical properties such as aluminum concentration and flux, and iron concentration between samples intercepted at different depths shows that particles collected by the deepest trap had more complex sources than the shallower ones. These data also suggest that at least two modes of lateral transport exist over the New England margin. Based on radiocarbon mass balance, about 30% (±10%) of sinking POC in all sediment traps is estimated to be derived from lateral transport of resuspended sediment. A strong correlation between Δ 14C values and aluminum concentrations suggests that the aged organic matter is associated with lithogenic particles. Our results suggest that lateral transport of organic matter, particularly that resulting from sediment resuspension, should be considered in addition to vertical supply of organic matter derived from primary production, in order to understand carbon cycling and export over continental margins.

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 isotopic correlation should also be revealed, which will aid in identifying pertinent synthetic processes.

Zeolite-like liquid crystals

NASA Astrophysics Data System (ADS)

Poppe, Silvio; Lehmann, Anne; Scholte, Alexander; Prehm, Marko; Zeng, Xiangbing; Ungar, Goran; Tschierske, Carsten

2015-10-01

Zeolites represent inorganic solid-state materials with porous structures of fascinating complexity. Recently, significant progress was made by reticular synthesis of related organic solid-state materials, such as metal-organic or covalent organic frameworks. Herein we go a step further and report the first example of a fluid honeycomb mimicking a zeolitic framework. In this unique self-assembled liquid crystalline structure, transverse-lying π-conjugated rod-like molecules form pentagonal channels, encircling larger octagonal channels, a structural motif also found in some zeolites. Additional bundles of coaxial molecules penetrate the centres of the larger channels, unreachable by chains attached to the honeycomb framework. This creates a unique fluid hybrid structure combining positive and negative anisotropies, providing the potential for tuning the directionality of anisotropic optical, electrical and magnetic properties. This work also demonstrates a new approach to complex soft-matter self-assembly, by using frustration between space filling and the entropic penalty of chain extension.

Research Highlight: Water-extractable organic matter from sandy loam soils

USDA-ARS?s Scientific Manuscript database

Labile organic matter plays important roles in soil health and nutrient cycling because of its dynamic nature. Water-extractable organic matter is part of the soil labile organic matter. In an article recently published in Agricultural & Environmental Letters, researchers report on the level and na...

Estimation of atmospheric columnar organic matter (OM) mass concentration from remote sensing measurements of aerosol spectral refractive indices

NASA Astrophysics Data System (ADS)

Zhang, Ying; Li, Zhengqiang; Sun, Yele; Lv, Yang; Xie, Yisong

2018-04-01

Aerosols have adverse effects on human health and air quality, changing Earth's energy balance and lead to climate change. The components of aerosol are important because of the different spectral characteristics. Based on the low hygroscopic and high scattering properties of organic matter (OM) in fine modal atmospheric aerosols, we develop an inversion algorithm using remote sensing to obtain aerosol components including black carbon (BC), organic matter (OM), ammonium nitrate-like (AN), dust-like (DU) components and aerosol water content (AW). In the algorithm, the microphysical characteristics (i.e. volume distribution and complex refractive index) of particulates are preliminarily separated to fine and coarse modes, and then aerosol components are retrieved using bimodal parameters. We execute the algorithm using remote sensing measurements of sun-sky radiometer at AERONET site (Beijing RADI) in a period from October of 2014 to January of 2015. The results show a reasonable distribution of aerosol components and a good fit for spectral feature calculations. The mean OM mass concentration in atmospheric column is account for 14.93% of the total and 56.34% of dry and fine-mode aerosol, being a fairly good correlation (R = 0.56) with the in situ observations near the surface layer.

Anthropogenic organic matter in the Great Marsh of the Indiana Dunes National Lakeshore and its implications

USGS Publications Warehouse

Mastalerz, Maria; Souch, C.; Filippelli, G.M.; Dollar, N.L.; Perkins, S.M.

2001-01-01

Cores from the Great Marsh area of the Indiana Dunes National Lakeshore were examined in order to document variations in concentration, type and size of anthropogenic organic matter (AnOM-coal, coke, etc.) and discuss their relationship to the concentration of such trace elements as Pb, Zn, and Mn in the near-surface sediment section. The results indicate that the first appearance of AnOM corresponds to the onset of industrialization in the area. There is also a general relationship between the occurrence of AnOM and Zn, Pb, and Mn. Trace metals were likely transported from the industrial sites to the area of their deposition as sulfur-bearing coatings on small anthropogenic particles. After deposition, these sulfur-bearing compounds reacted with organic matter within the marsh. As a result of bacterial reduction, the pyrite was produced, as suggested by a close relationship between the pyrite and AnOM. Distance from the industrial complex upwind as well as local hydrologic conditions are among the major factors controlling distribution of AnOM and trace elements. At the same distance from the source, types and sizes of AnOM are influenced by the duration and frequency of flooding. ?? 2001 Elsevier Science B.V. All rights reserved.

Ecosystem consequences of changing inputs of terrestrial dissolved organic matter to lakes: current knowledge and future challenges

USGS Publications Warehouse

Solomon, Christopher T.; Jones, Stuart E.; Weidel, Brian C.; Buffam, Ishi; Fork, Megan L; Karlsson, Jan; Larsen, Soren; Lennon, Jay T.; Read, Jordan S.; Sadro, Steven; Saros, Jasmine E.

2015-01-01

Lake ecosystems and the services that they provide to people are profoundly influenced by dissolved organic matter derived from terrestrial plant tissues. These terrestrial dissolved organic matter (tDOM) inputs to lakes have changed substantially in recent decades, and will likely continue to change. In this paper, we first briefly review the substantial literature describing tDOM effects on lakes and ongoing changes in tDOM inputs. We then identify and provide examples of four major challenges which limit predictions about the implications of tDOM change for lakes, as follows: First, it is currently difficult to forecast future tDOM inputs for particular lakes or lake regions. Second, tDOM influences ecosystems via complex, interacting, physical-chemical-biological effects and our holistic understanding of those effects is still rudimentary. Third, non-linearities and thresholds in relationships between tDOM inputs and ecosystem processes have not been well described. Fourth, much understanding of tDOM effects is built on comparative studies across space that may not capture likely responses through time. We conclude by identifying research approaches that may be important for overcoming those challenges in order to provide policy- and management-relevant predictions about the implications of changing tDOM inputs for lakes.

Antibacterial activity of the soil-bound antimicrobials oxytetracycline and ofloxacin.

PubMed

Peng, Feng-Jiao; Zhou, Li-Jun; Ying, Guang-Guo; Liu, You-Sheng; Zhao, Jian-Liang

2014-04-01

Soil contamination of antimicrobials has become an increasing concern because of the potential risks to the soil microbial ecosystem and human health. The present study investigated sorption and desorption behaviors of oxytetracycline (OTC) and ofloxacin (OFL) in 3 typical soils (A, B, and C), and evaluated the antibacterial activity of soil-adsorbed compounds to a pure sensitive strain Escherichia coli ATCC 25922. The results showed different sorption and desorption behaviors of OTC and OFL in the 3 soils, behaviors that were mainly influenced by soil organic matter content and cation exchange capacity (CEC) as well as pH value. In addition, complexation and cation-exchange reactions were shown to be the main sorption mechanisms. Strong adsorption was found in soil B (with a high organic matter content) and in soil C (with high CEC), whereas enhanced desorption was observed in soil A (with low organic matter content). The results also demonstrated that soil-bound antimicrobials retained antibacterial activity toward E. coli. Opposite patterns of antibacterial activity were found for the 2 antimicrobials in the 3 soils: A>B>C for OFL; and C>B>A for OTC. This finding suggests that soil-bound antimicrobials could still exert selective pressure on soil bacteria although less effectively in comparison with the dissolved forms. © 2014 SETAC.

Metal Speciation in Landfill Leachates with a Focus on the Influence of Organic Matter

DOE Office of Scientific and Technical Information (OSTI.GOV)

F Claret; C Tournassat; C Crouzet

This study characterizes the heavy-metal content in leachates collected from eight landfills in France. In order to identify heavy metal occurrence in the different size fractions of leachates, a cascade filtration protocol was applied directly in the field, under a nitrogen gas atmosphere to avoid metal oxidation. The results of analyses performed on the leachates suggest that most of the metals are concentrated in the <30 kDa fraction, while lead, copper and cadmium show an association with larger particles. Initial speciation calculations, without considering metal association with organic matter, suggest that leachate concentrations in lead, copper, nickel and zinc aremore » super-saturated with respect to sulphur phases. Speciation calculations that account for metal complexation with organic matter, considered as fulvic acids based on C1(s) NEXAFS spectroscopy, show that this mechanism is not sufficient to explain such deviation from equilibrium conditions. It is therefore hypothesized that the deviation results also from the influence of biological activity on the kinetics of mineral phase precipitation and dissolution, thus providing a dynamic system. The results of chemical analyses of sampled fluids are compared with speciation calculations and some implications for the assessment of metal mobility and natural attenuation in a context of landfill risk assessment are discussed.« less

Response of aluminum solubility to elevated nitrification in soil of a red spruce stand in eastern Maine

USGS Publications Warehouse

Lawrence, G.B.; David, M.B.

1997-01-01

Elevated concentrations of soluble Al can impair tree growth and be toxic to aquatic biota, but effects of acidic deposition on Al solubility in forest soils are only partially understood because of complex interactions with H+ and organic matter. We therefore evaluated Al solubility in two red spruce stands in eastern Maine, one of which received dry (NH4)2SO4 at a rate of 1800 equiv ha-1 yr-1 during 19891995. Samples of soil (Spodosol Oa and Bh horizons) and soil solution were collected on five dates from 1992 to 1995. The treatment elevated nitrification, causing an increase in acid input that led to inorganic Al concentrations of greater than 60 ??mol L-1 in both the Oa and Bh horizons. Solubility of Al was also lower in the Bh horizon of the treated stand than in the reference stand, a response related to higher DOC concentrations in the treated stand. Concentrations of CuCl2 and pyrophosphate-extractable Al were higher in the Oa horizon of the treated watershed than the reference stand, a result of accelerated weathering of mineral particles caused by lower solution pH in the treated stand (3.47) than in the reference stand (3.69). Dissolved Al concentrations in these soils are the result of complex mechanisms through which mineral matter, organic matter, and pH interact to control Al solubility; mechanisms that are not incorporated in current Al solubility models.

Biomimetic Phases of Microtubule-Motor Mixtures

NASA Astrophysics Data System (ADS)

Ross, Jennifer

2014-03-01

We try to determine the universal principles of organization from the molecular scale that gives rise to architecture on the cellular scale. We are specifically interested in the organization of the microtubule cytoskeleton, a rigid, yet versatile network in most cell types. Microtubules in the cell are organized by motor proteins and crosslinkers. This work applies the ideas of statistical mechanics and condensed matter physics to the non-equilibrium pattern formation behind intracellular organization using the microtubule cytoskeleton as the building blocks. We examine these processes in a bottom-up manner by adding increasingly complex protein actors into the system. Our systematic experiments expose nature's laws for organization and has large impacts on biology as well as illuminating new frontiers of non-equilibrium physics.

Coordination of Cell Polarity, Mechanics and Fate in Tissue Self-organization.

PubMed

Kim, Esther Jeong Yoon; Korotkevich, Ekaterina; Hiiragi, Takashi

2018-07-01

Self-organization guides robust, spatiotemporally ordered formation of complex tissues and ultimately whole organisms. While products of gene expression serve as building blocks of living matter, how these interact to give rise to tissues of distinct patterns and function remains a central question in biology. Tissue self-organization relies on dynamic interactions between constituents spanning a range of spatiotemporal scales with tuneable chemical and mechanical parameters. This review highlights recent studies dissecting mechanisms of these interactions. We propose that feedback interactions between cell polarity, mechanics, and fate are a key principle underlying tissue self-organization. We also provide a glimpse into how such processes can be studied in future endeavors. Copyright © 2018 Elsevier Ltd. All rights reserved.

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.

Irradiated Benzene Ice Provides Clues to Meteoritic Organic Chemistry

NASA Technical Reports Server (NTRS)

Callahan, Michael Patrick; Gerakines, Perry Alexander; Martin, Mildred G.; Hudson, Reggie L.; Peeters, Zan

2013-01-01

Aromatic hydrocarbons account for a significant portion of the organic matter in carbonaceous chondrite meteorites, as a component of both the low molecular weight, solvent-extractable compounds and the insoluble organic macromolecular material. Previous work has suggested that the aromatic compounds in carbonaceous chondrites may have originated in the radiation-processed icy mantles of interstellar dust grains. Here we report new studies of the organic residue made from benzene irradiated at 19 K by 0.8 MeV protons. Polyphenyls with up to four rings were unambiguously identified in the residue by gas chromatography-mass spectrometry. Atmospheric pressure photoionization Fourier transform mass spectrometry was used to determine molecular composition, and accurate mass measurements suggested the presence of polyphenyls, partially hydrogenated polyphenyls, and other complex aromatic compounds. The profile of low molecular weight compounds in the residue compared well with extracts from the Murchison and Orgueil meteorites. These results are consistent with the possibility that solid phase radiation chemistry of benzene produced some of the complex aromatics found in meteorites.

Characterization and source identification of organic matter in view of land uses and heavy rainfall in the Lake Shihwa, Korea.

PubMed

Lee, Yeonjung; Hur, Jin; Shin, Kyung-Hoon

2014-07-15

The characteristics and sources of organic matter in water of the Lake Shihwa, which receives inputs from rural, urban, and industrial areas, were evaluated by examining the biodegradable organic carbon concentration, fluorescence spectra, and carbon and nitrogen isotope ratios, especially during rainy season and dry season. The organic matter transported from rural areas was of refractory nature, while that of industrial origin decomposed rapidly. As compared to the dry season, the organic matter in the rainy season was characterized by a reduced labile fraction. During the dry season, the autochthonous organic matter dominated in the lake, however, the contributions of allochthonous organic sources by industrial and rural areas significantly increased at rainy season. This investigation revealed that the transport of organic matter of anthropogenic origin to the Lake Shihwa was mainly influenced by heavy rainfall. Moreover, each anthropogenic source could differently influence the occurrence of organic matter in water of the Lake Shihwa. Copyright © 2014 Elsevier Ltd. All rights reserved.

The Environmental Fate and Bioavailability of Arsenic in Cuitzeo, Michoacán, México .

NASA Astrophysics Data System (ADS)

Rivas-Valdes, M.; Fernandez-Lomelin, P.; Cram-Heydrich, S.; Gamboa-Cáceres, A.; Vanegas, C.; Cervini-Silva, J.

2007-05-01

Cuitzeo is located in Central Mexico. The Cuitzeo lake is very low, it has seven islands and a highway four kilometers long that crosses the lake. Detected concentrations of arsenic average 30-40 mg kg-1. In the salted waters a lot of "charal" (a small fish), main ingredient in many regional dishes, and ducks can be found. This study reports the effect of organic matter on As partitioning. Complexation of As with organic biomolecules that may contribute to detoxification pathways in Cuitzeo are discussed.

Equilibrium and disequilibrium chemistry of adiabatic, solar-composition planetary atmospheres

NASA Technical Reports Server (NTRS)

Lewis, J. S.

1976-01-01

The impact of atmospheric and cloud-structure models on the nonequilibrium chemical behavior of the atmospheres of the Jovian planets is discussed. Quantitative constraints on photochemical, lightning, and charged-particle production of organic matter and chromophores are emphasized whenever available. These considerations imply that inorganic chromophore production is far more important than that of organic chromophores, and that lightning is probably a negligibly significant process relative to photochemistry on Jupiter. Production of complex molecules by gas-phase disequilibrium processes on Saturn, Uranus, and Neptune is severely limited by condensation of even simple intermediates.

Perennial Antarctic lake ice: an oasis for life in a polar desert

NASA Technical Reports Server (NTRS)

Priscu, J. C.; Fritsen, C. H.; Adams, E. E.; Giovannoni, S. J.; Paerl, H. W.; McKay, C. P.; Doran, P. T.; Gordon, D. A.; Lanoil, B. D.; Pinckney, J. L.

1998-01-01

The permanent ice covers of Antarctic lakes in the McMurdo Dry Valleys develop liquid water inclusions in response to solar heating of internal aeolian-derived sediments. The ice sediment particles serve as nutrient (inorganic and organic)-enriched microzones for the establishment of a physiologically and ecologically complex microbial consortium capable of contemporaneous photosynthesis, nitrogen fixation, and decomposition. The consortium is capable of physically and chemically establishing and modifying a relatively nutrient- and organic matter-enriched microbial "oasis" embedded in the lake ice cover.

Perennial Antarctic lake ice: an oasis for life in a polar desert.

PubMed

Priscu, J C; Fritsen, C H; Adams, E E; Giovannoni, S J; Paerl, H W; McKay, C P; Doran, P T; Gordon, D A; Lanoil, B D; Pinckney, J L

1998-06-26

The permanent ice covers of Antarctic lakes in the McMurdo Dry Valleys develop liquid water inclusions in response to solar heating of internal aeolian-derived sediments. The ice sediment particles serve as nutrient (inorganic and organic)-enriched microzones for the establishment of a physiologically and ecologically complex microbial consortium capable of contemporaneous photosynthesis, nitrogen fixation, and decomposition. The consortium is capable of physically and chemically establishing and modifying a relatively nutrient- and organic matter-enriched microbial "oasis" embedded in the lake ice cover.

Organic matter degradation in surface sediments of the Changjiang estuary: Evidence from amino acids.

PubMed

Wang, Kui; Chen, Jianfang; Jin, Haiyan; Li, Hongliang; Zhang, Weiyan

2018-05-12

Organic matter degradation is a key component of the processes of carbon preservation and burial in seafloor sediments. The aim of this study was to explore organic matter degradation state within the open-shelf Changjiang Estuary of the East China Sea, using an amino acids-based degradation index (DI) in conjunction with information about organic matter source (marine versus terrestrial), bottom water oxygenation state, and sediment grain size. The relative molar percentages of 17 individual amino acids (characterized using principal component analysis) in surface sediments indicate that organic matter is degraded to varying extents across the estuary seabed. Sediments with DI >0 (relatively labile) were found mostly within a coastal hypoxic area. Sediments of DI less than -1 (relatively refractory) were found near the Changjiang River mouth and the northern and southern parts of the central shelf. We consider DI to be a more reliable indicator of degradation than simple ratios of AAs. DI was inversely correlated with the proportion of terrestrial organic material (F t ) in the sediments, indicating that relatively fresh/labile organic matter was generally associated with marine sources. DI was significantly correlated with F t and bottom water apparent oxygen utilization (AOU bot ) together. The parameter DI and the (labile) amino acid tyrosine were highest in hypoxic areas, suggesting the presence of relatively fresh organic matter, probably due to a combination of marine-source inputs and better preservation of organic matter in the silt and clay sediments of these areas (as compared to sandy sediments). Less degraded organic matter with high amino acids was also favorable to benthic animals. Overall, sedimentary estuarine organic matter was least degraded in areas characterized by marine sources of organic matter, low-oxygen conditions, and fine-grained sediments. Copyright © 2018 Elsevier B.V. All rights reserved.

Interactions between natural organic ligands and trace metals studied by fluorescence lifetime and fluorescence quenching

NASA Astrophysics Data System (ADS)

Nouhi, Ayoub; Hajjoul, Houssam; Redon, Roland; Gagné, Jean-Pierre; Mounier, Stéphane

2017-04-01

Improved insight on the interactions between natural organic ligands and trace metals is of paramount importance for better understanding transport and toxicity pathways of metal ions in the environment. Fluorescence spectroscopy allows introspecting ligands-metals interactions. Time-resolved laser fluorescence spectroscopy (TRLFS) measures fluorophore lifetime probing the local molecular environment. Excitation Emission Fluorescence Matrices (EEFMs) and their statistical treatment : parallel factor analysis (PARAFAC) using PROGMEEF Matlab homemade program, can give insight on the number or nature of organic fluorophores involved in the interactions. Quenching of fluorescence by metals can occur following two processes: dynamic and static quenching (Lakowicz, 2013). In the first case, quenching is caused by physical collisions among molecules and in the second case fluorophores can form nonfluorescent complexes with quenchers. It is possible to identify the different mechanisms because each type of quenching corresponds to a different mathematical model (Lakowicz, 2013; Valeur and Berberan-Santos, 2012). In TRLFS, the study of fluorescence decay's laws induced by nanosecond pulsed laser will allow to exactly qualify the type of interaction. The crucial point of the temporal deconvolution will be the evaluation of the best fitting between the different physical models and the decays measured. From the most suitable time decay model, it will be possible to deduce the quenching which modifies the fluorescence. The aim of this study was to characterize interactions between natural organic ligands and trace metals using fluorescence tools to evaluate the fluorescence lifetime of the fluorophore, the occurrence of quenching in presence of metal, discuss its mechanism and estimate conditional stability constants if a complex organic ligand-metal is formed. This study has been done in two steps. First, we have examined the interactions between salicylic acid and copper in order to calibrate our assays and compare our results with literature. Several studies have shown that static quenching occurs in that case (Brun and Schröder, 1975; Lavrik and Mulloev, 2010; Ventry et al., 1991; Babko, 1968). Indeed, after processing the EEFMs and TRLFS data, we found a fluorescence intensity decay by about 50% and a constant lifetime for the fluorophore suggesting a static quenching, in agreement with the literature. In the second step, we have studied the interactions between metal and different types of natural organic matters. In this case, EEMFs and TRLFS experiments were done on samples prepared by dissolving copper in four different fractions of organic matter extracted from estuarine water (St. Lawrence Estuary, Canada). Organic matter was obtained using DAX-8 and XAD-4 resins in series. Humic and fulvic acids are obtained following the IHSS protocol. The results of interaction between humic substances and copper gathered after processing data on PROGMEEF have shown a fluorescence intensity decay by about 57% for the first component and 88% for the second component. The fluorescence lifetime for both components were close to 2 ns and 6 ns respectively and the pH range was stable and close to 6. This means that a static quenching takes place in this case in agreement with the literature. Our study also focused on the investigation of complexation of organic matter by other metals in particular Aluminum, Arsenic, Europium and Uranium.

Coal-Quality Information - Key to the Efficient and Environmentally Sound Use of Coal

USGS Publications Warehouse

Finkleman, Robert B.

1997-01-01

The rock that we refer to as coal is derived principally from decomposed organic matter (plants) consisting primarily of the element carbon. When coal is burned, it produces energy in the form of heat, which is used to power machines such as steam engines or to drive turbines that produce electricity. Almost 60 percent of the electricity produced in the United States is derived from coal combustion. Coal is an extraordinarily complex material. In addition to organic matter, coal contains water (up to 40 or more percent by weight for some lignitic coals), oils, gases (such as methane), waxes (used to make shoe polish), and perhaps most importantly, inorganic matter (fig. 1). The inorganic matter--minerals and trace elements--cause many of the health, environmental, and technological problems attributed to coal use (fig. 2). 'Coal quality' is the term used to refer to the properties and characteristics of coal that influence its behavior and use. Among the coal-quality characteristics that will be important for future coal use are the concentrations, distribution, and forms of the many elements contained in the coal that we intend to burn. Knowledge of these quality characteristics in U.S. coal deposits may allow us to use this essential energy resource more efficiently and effectively and with less undesirable environmental impact.

Use of high-volume outdoor smog chamber photo-reactors for studying physical and chemical atmospheric aerosol formation and composition

NASA Astrophysics Data System (ADS)

Borrás, E.; Ródenas, M.; Vera, T.; Muñoz, A.

2015-12-01

The atmospheric particulate matter has a large impact on climate, biosphere behaviour and human health. Its study is complex because of large number of species are present at low concentrations and the continuous time evolution, being not easily separable from meteorology, and transport processes. Closed systems have been proposed by isolating specific reactions, pollutants or products and controlling the oxidizing environment. High volume simulation chambers, such as EUropean PHOtoREactor (EUPHORE), are an essential tool used to simulate atmospheric photochemical reactions. This communication describes the last results about the reactivity of prominent atmospheric pollutants and the subsequent particulate matter formation. Specific experiments focused on organic aerosols have been developed at the EUPHORE photo-reactor. The use of on-line instrumentation, supported by off-line techniques, has provided well-defined reaction profiles, physical properties, and up to 300 different species are determined in particulate matter. The application fields include the degradation of anthropogenic and biogenic pollutants, and pesticides under several atmospheric conditions, studying their contribution on the formation of secondary organic aerosols (SOA). The studies performed at the EUPHORE have improved the mechanistic studies of atmospheric degradation processes and the knowledge about the chemical and physical properties of atmospheric particulate matter formed during these processes.

Influence of Multiple Environmental Factors on Organic Matter Chlorination in Podsol Soil.

PubMed

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

2017-12-19

Natural chlorination of organic matter is common in soils. The abundance of chlorinated organic compounds frequently exceeds chloride in surface soils, and the ability to chlorinate soil organic matter (SOM) appears widespread among microorganisms. Yet, the environmental control of chlorination is unclear. Laboratory incubations with 36 Cl as a Cl tracer were performed to test how combinations of environmental factors, including levels of soil moisture, nitrate, chloride, and labile organic carbon, influenced chlorination of SOM from a boreal forest. Total chlorination was hampered by addition of nitrate or by nitrate in combination with water but enhanced by addition of chloride or most additions including labile organic matter (glucose and maltose). The greatest chlorination was observed after 15 days when nitrate and water were added together with labile organic matter. The effect that labile organic matter strongly stimulated the chlorination rates was confirmed by a second independent experiment showing higher stimulation at increased availability of labile organic matter. Our results highlight cause-effect links between chlorination and the studied environmental variables in podsol soil-with consistent stimulation by labile organic matter that did overrule the negative effects of nitrate.

Localized aliphatic organic material on the surface of Ceres

NASA Astrophysics Data System (ADS)

De Sanctis, M. C.; Ammannito, E.; McSween, H. Y.; Raponi, A.; Marchi, S.; Capaccioni, F.; Capria, M. T.; Carrozzo, F. G.; Ciarniello, M.; Fonte, S.; Formisano, M.; Frigeri, A.; Giardino, M.; Longobardo, A.; Magni, G.; McFadden, L. A.; Palomba, E.; Pieters, C. M.; Tosi, F.; Zambon, F.; Raymond, C. A.; Russell, C. T.

2017-02-01

Organic compounds occur in some chondritic meteorites, and their signatures on solar system bodies have been sought for decades. Spectral signatures of organics have not been unambiguously identified on the surfaces of asteroids, whereas they have been detected on cometary nuclei. Data returned by the Visible and InfraRed Mapping Spectrometer on board the Dawn spacecraft show a clear detection of an organic absorption feature at 3.4 micrometers on dwarf planet Ceres. This signature is characteristic of aliphatic organic matter and is mainly localized on a broad region of ~1000 square kilometers close to the ~50-kilometer Ernutet crater. The combined presence on Ceres of ammonia-bearing hydrated minerals, water ice, carbonates, salts, and organic material indicates a very complex chemical environment, suggesting favorable environments to prebiotic chemistry.

A review of surface-water sediment fractions and their interactions with persistent manmade organic compounds

USGS Publications Warehouse

Witkowski, P.J.; Smith, J.A.; Fusillo, T.V.; Chiou, C.T.

1987-01-01

This paper reviews the suspended and surficial sediment fractions and their interactions with manmade organic compounds. The objective of this review is to isolate and describe those contaminant and sediment properties that contribute to the persistence of organic compounds in surface-water systems. Most persistent, nonionic organic contaminants, such as the chlorinated insecticides and polychlorinated biphenyls (PCBs), are characterized by low water solubilities and high octanol-water partition coefficients. Consequently, sorptive interactions are the primary transformation processes that control their environmental behavior. For nonionic organic compounds, sorption is primarily attributed to the partitioning of an organic contaminant between a water phase and an organic phase. Partitioning processes play a central role in the uptake and release of contaminants by sediment organic matter and in the bioconcentration of contaminants by aquatic organisms. Chemically isolated sediment fractions show that organic matter is the primary determinant of the sorptive capacity exhibited by sediment. Humic substances, as dissolved organic matter, contribute a number of functions to the processes cycling organic contaminants. They alter the rate of transformation of contaminants, enhance apparent water solubility, and increase the carrying capacity of the water column beyond the solubility limits of the contaminant. As a component of sediment particles, humic substances, through sorptive interactions, serve as vectors for the hydrodynamic transport of organic contaminants. The capabilities of the humic substances stem in part from their polyfunctional chemical composition and also from their ability to exist in solution as dissolved species, flocculated aggregates, surface coatings, and colloidal organomineral and organometal complexes. The transport properties of manmade organic compounds have been investigated by field studies and laboratory experiments that examine the sorption of contaminants by different sediment size fractions. Field studies indicate that organic contaminants tend to sorb more to fine-grained sediment, and this correlates significantly with sediment organic matter content. Laboratory experiments have extended the field studies to a wider spectrum of natural particulates and anthropogenic compounds. Quantitation of isotherm results allows the comparison of different sediment sorbents as well as the estimation of field partition coefficients from laboratory-measured sediment and contaminant properties. Detailed analyses made on the basis of particle-size classes show that all sediment fractions need to be considered in evaluating the fate and distribution of manmade organic compounds. This conclusion is based on observations from field studies and on the variety of natural organic sorbents that demonstrate sorptive capabilities in laboratory isotherm experiments.

Influence of water chemistry and natural organic matter on active and passive uptake of inorganic mercury by gills of rainbow trout (Oncorhynchus mykiss).

PubMed

Klinck, Joel; Dunbar, Michael; Brown, Stephanie; Nichols, Joel; Winter, Anna; Hughes, Christopher; Playle, Richard C

2005-03-25

To distinguish physiologically regulated uptake from passive uptake of inorganic Hg in fish, rainbow trout (Oncorhynchus mykiss) were exposed to inorganic Hg (0.5, 1, or 2 microM total Hg) in ion-poor water with various treatments. Addition of ions to the water (mM concentrations of Ca, K, Cl) did not consistently alter Hg accumulation by trout gills, although there was a trend to higher Hg accumulation at higher ion concentrations. The apical Ca channel blockers Verapamil and lanthanum also did not consistently affect Hg accumulation by trout gills. Pre-treatment of trout with the Na channel blocker Phenamil decreased Hg uptake by about half. These results suggest a combination of physiologically regulated and passive uptake of Hg by trout gills. Strong complexing agents of Hg (EDTA, NTA, ethylenediamine, cysteine) decreased Hg-binding by trout gills in a dose-dependent manner. From these data, a conditional equilibrium binding constant for Hg to the gills was estimated as logK(Hg-gill) = 18.0, representing very strong binding of Hg to the gills. This value is a first step in creating a biotic ligand model (BLM) for inorganic Hg and fish. Natural organic matter (2-10 mg C/L) also decreased Hg-binding by trout gills, although mM concentrations of Na, K, and Cl interfered with this effect. At low concentrations of these ions, natural organic matter samples isolated from various sources bound Hg to similar degrees, as judged by Hg accumulation by trout gills. A conditional binding constant to natural organic matter (NOM) was estimated as logK(Hg-NOM) = 18.0 with about 0.5 micromol binding sites per mg C, representing strong binding of Hg to NOM.

Aluminum in Precipitation, Streams, and Shallow Groundwater in the New Jersey Pine Barrens

NASA Astrophysics Data System (ADS)

Budd, W. W.; Johnson, A. H.; Huss, J. B.; Turner, R. S.

1981-08-01

Total (acid reactive) aluminum deposited in bulk precipitation in the McDonalds Branch (New Jersey) basin was 140 mg m-2 yr-1 for the period May 1978-May 1980. Stream and groundwater outputs for the same period were 149 and 110 mg m-2 yr-1, respectively. Aluminum inputs and outputs were highest during summer months because of elevated concentrations coupled with increased precipitation and streamflow. Median acid reactive Al concentrations in precipitation, stream water, and groundwater were 100, 350, and 230 μg 1-1, respectively. In streams, acid reactive Al concentration is correlated with dissolved organic matter concentration, suggesting that Al is transported as an organometallic complex. Shallow groundwater Al concentration is apparently controlled by gibbsite solubility in mineral soils and thus is pH dependent. The relatively high Al concentrations are attributable to acid conditions and mobile organic matter.

Reactivity of Zerovalent Metals in Aquatic Media: Effects of Organic Surface Coatings

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tratnyek, Paul G.; Salter-Blanc, Alexandra; Nurmi, James

2011-09-02

Granular, reactive zerovalent metals (ZVMs)—especially iron (ZVI)—form the basis for model systems that have been used in fundamental and applied studies of a wide variety of environmental processes. This has resulted in notable advances in many areas, including the kinetics and mechanisms of contaminant reduction reactions, theory of filtration and transport of colloids in porous media, and modeling of complex reactive-transport scenarios. Recent emphasis on nano-sized ZVI has created a new opportunity: to advance the understanding of how coatings of organic polyelectrolytes—like natural organic matter (NOM)—influence the reactivity of environmental surfaces. Depending on many factors, organic coatings can be activatingmore » or passivating with respect to redox reactions at particle-solution interfaces. In this study, we show the effects of organic coatings on nZVI vary with a number of factors including: (i) time (i.e., “aging” is evident not only in the structure and composition of the nZVI but also in the interactions between nZVI and NOM) and (ii) the type of organic matter (i.e., suspensions of nZVI are stabilized by NOM and the model polyelectrolyte carboxymethylcellulose (CMC), but NOM stimulates redox reactions involving nZVI while CMC inhibits them).« less

AxTract: Toward microstructure informed tractography.

PubMed

Girard, Gabriel; Daducci, Alessandro; Petit, Laurent; Thiran, Jean-Philippe; Whittingstall, Kevin; Deriche, Rachid; Wassermann, Demian; Descoteaux, Maxime

2017-11-01

Diffusion-weighted (DW) magnetic resonance imaging (MRI) tractography has become the tool of choice to probe the human brain's white matter in vivo. However, tractography algorithms produce a large number of erroneous streamlines (false positives), largely due to complex ambiguous tissue configurations. Moreover, the relationship between the resulting streamlines and the underlying white matter microstructure characteristics remains poorly understood. In this work, we introduce a new approach to simultaneously reconstruct white matter fascicles and characterize the apparent distribution of axon diameters within fascicles. To achieve this, our method, AxTract, takes full advantage of the recent development DW-MRI microstructure acquisition, modeling, and reconstruction techniques. This enables AxTract to separate parallel fascicles with different microstructure characteristics, hence reducing ambiguities in areas of complex tissue configuration. We report a decrease in the incidence of erroneous streamlines compared to the conventional deterministic tractography algorithms on simulated data. We also report an average increase in streamline density over 15 known fascicles of the 34 healthy subjects. Our results suggest that microstructure information improves tractography in crossing areas of the white matter. Moreover, AxTract provides additional microstructure information along the fascicle that can be studied alongside other streamline-based indices. Overall, AxTract provides the means to distinguish and follow white matter fascicles using their microstructure characteristics, bringing new insights into the white matter organization. This is a step forward in microstructure informed tractography, paving the way to a new generation of algorithms able to deal with intricate configurations of white matter fibers and providing quantitative brain connectivity analysis. Hum Brain Mapp 38:5485-5500, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Constants for mercury binding by organic matter isolates from the Florida Everglades

USGS Publications Warehouse

Benoit, J.M.; Mason, R.P.; Gilmour, C.C.; Aiken, G.R.

2001-01-01

Dissolved organic matter (DOM) has been implicated as an important complexing agent for Hg that can affect its mobility and bioavailability in aquatic ecosystems. However, binding constants for natural Hg-DOM complexes are not well known. We employed a competitive ligand approach to estimate conditional stability constants for Hg complexes with DOM isolates collected from Florida Everglades surface waters. The isolates examined were the hydrophobic fraction of DOM from a eutrophic, sulfidic site (F1-HPoA) and the hydrophilic fraction from an oligotrophic, low-sulfide site (2BS-HPiA). Our experimental determinations utilized overall octanol-water partitioning coefficients (Dow) for 203Hg at 0.01 M chloride and across pH and DOM concentration gradients. Use of this radioisotope allowed rapid determinations of Hg concentrations in both water and octanol phases without problems of matrix interference. Conditional stability constants (1 = 0.06, 23??C) were log K??? = 11.8 for F1-HPoA and log K' = 10.6 for 2BS-HPiA. These are similar to previously published stability constants for Hg binding to low-molecular-weight thiols. Further, F1-HPoA showed a pH-dependent decline in Dow that was consistent with models of Hg complexation with thiol groups as the dominant Hg binding sites in DOM. These experiments demonstrate that the DOM isolates are stronger ligands for Hg than chloride ion or ethylenediamine-tetraacetic acid. Speciation calculations indicate that at the DOM concentrations frequently measured in Everglades, 20 to 40 ??M, significant complexation of Hg by DOM would be expected in aerobic (sulfide-free) surface waters. Copyright ?? 2001 Elsevier Science Ltd.

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.

What is soil organic matter worth?

PubMed

Sparling, G P; Wheeler, D; Vesely, E-T; Schipper, L A

2006-01-01

The conservation and restoration of soil organic matter are often advocated because of the generally beneficial effects on soil attributes for plant growth and crop production. More recently, organic matter has become important as a terrestrial sink and store for C and N. We have attempted to derive a monetary value of soil organic matter for crop production and storage functions in three contrasting New Zealand soil orders (Gley, Melanic, and Granular Soils). Soil chemical and physical characteristics of real-life examples of three pairs of matched soils with low organic matter contents (after long-term continuous cropping for vegetables or maize) or high organic matter content (continuous pasture) were used as input data for a pasture (grass-clover) production model. The differences in pasture dry matter yields (non-irrigated) were calculated for three climate scenarios (wet, dry, and average years) and the yields converted to an equivalent weight and financial value of milk solids. We also estimated the hypothetical value of the C and N sequestered during the recovery phase of the low organic matter content soils assuming trading with C and N credits. For all three soil orders, and for the three climate scenarios, pasture dry matter yields were decreased in the soils with lower organic matter contents. The extra organic matter in the high C soils was estimated to be worth NZ$27 to NZ$150 ha(-1) yr(-1) in terms of increased milk solids production. The decreased yields from the previously cropped soils were predicted to persist for 36 to 125 yr, but with declining effect as organic matter gradually recovered, giving an accumulated loss in pastoral production worth around NZ$518 to NZ$1239 ha(-1). This was 42 to 73 times lower than the hypothetical value of the organic matter as a sequestering agent for C and N, which varied between NZ$22,963 to NZ$90,849 depending on the soil, region, discount rates, and values used for carbon and nitrogen credits.

Influence of organic matter on the transport of Cryptosporidium parvum oocysts in a ferric oxyhydroxide-coated quartz sand saturated porous medium

USGS Publications Warehouse

Abudalo, R.A.; Ryan, J.N.; Harvey, R.W.; Metge, D.W.; Landkamer, Lee L.

2010-01-01

To assess the effect of organic matter on the transport of Cryptosporidium parvum oocysts in a geochemically heterogeneous saturated porous medium, we measured the breakthrough and collision efficiencies of oocysts as a function of dissolved organic matter concentration in a flow-through column containing ferric oxyhydroxide-coated sand. We characterized the surface properties of the oocysts and ferric oxyhydroxide-coated sand using microelectrophoresis and streaming potential, respectively, and the amount of organic matter adsorbed on the ferric oxyhydroxide-coated sand as a function of the concentration of dissolved organic matter (a fulvic acid isolated from Florida Everglades water). The dissolved organic matter had no significant effect on the zeta potential of the oocysts. Low concentrations of dissolved organic matter were responsible for reversing the charge of the ferric oxyhydroxide-coated sand surface from positive to negative. The charge reversal and accumulation of negative charge on the ferric oxyhydroxide-coated sand led to increases in oocyst breakthrough and decreases in oocyst collision efficiency with increasing dissolved organic matter concentration. The increase in dissolved organic matter concentration from 0 to 20 mg L-1 resulted in a two-fold decrease in the collision efficiency. ?? 2009 Elsevier Ltd.

The contentious nature of soil organic matter.

PubMed

Lehmann, Johannes; Kleber, Markus

2015-12-03

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.

Interactions between Silicon Oxide Nanoparticles (SONPs) and U(VI) Contaminations: Effects of pH, Temperature and Natural Organic Matters

PubMed Central

Wu, Hanyu; Li, Ping; Pan, Duoqiang; Yin, Zhuoxin; Fan, Qiaohui; Wu, Wangsuo

2016-01-01

The interactions between contaminations of U(VI) and silicon oxide nanoparticles (SONPs), both of which have been widely used in modern industry and induced serious environmental challenge due to their high mobility, bioavailability, and toxicity, were studied under different environmental conditions such as pH, temperature, and natural organic matters (NOMs) by using both batch and spectroscopic approaches. The results showed that the accumulation process, i.e., sorption, of U(VI) on SONPs was strongly dependent on pH and ionic strength, demonstrating that possible outer- and/or inner-sphere complexes were controlling the sorption process of U(VI) on SONPs in the observed pH range. Humic acid (HA), one dominated component of NOMs, bounded SONPs can enhance U(VI) sorption below pH~4.5, whereas restrain at high pH range. The reversible sorption of U(VI) on SONPs possibly indicated that the outer-sphere complexes were prevalent at pH 5. However, an irreversible interaction of U(VI) was observed in the presence of HA (Fig 1). It was mainly due to the ternary SONPs-HA-U(VI) complexes (Type A Complexes). After SONPs adsorbed U(VI), the particle size in suspension was apparently increased from ~240 nm to ~350 nm. These results showed that toxicity of both SONPs and U(VI) will decrease to some extent after the interaction in the environment. These findings are key for providing useful information on the possible mutual interactions among different contaminants in the environment. PMID:26930197

Defining organic matter quality in sediment systems: a suggested classification scheme

NASA Astrophysics Data System (ADS)

Alderson, Danielle; Evans, Martin; Rothwell, James; Boult, Stephen

2015-04-01

The quantity and quality of the mineral component of sediments is a core focus of sedimentological investigation in terrestrial systems. This is not to say that the organic component of collected sediments is simply ignored; the organic component is often scrutinised, but in some fields in a restricted manner, limited to basic characteristics such as the ratio of organic to mineral content derived from loss on ignition. There is no doubt that this information is useful; however, these types of analysis indicate the quantity of organic matter relative to a particular temporal scale or volume, rather than treating the organic fraction as a separate entity worthy of substantial investigation. The quality of the organic component is being increasingly considered in a number of fields, with molecular, thermal, spectroscopic and bulk methods being used. However, models and theories on organic matter processing in a variety of environmental systems, have been developed without clearly defining organic matter quality, because most results do not depend on an outright measure of quality (Bosatta and Agren, 1999). With approaches and techniques varying between fields, there is a need to consider a more systematic approach to the analysis and definition of organic matter quality. The disparities in the definition of the quality of organic matter, and thus how it may be measured have vital implications for the study of carbon cycling, biogeochemical processing, and ultimately ecosystem structure and function. The quality and quantity of organic matter have an influence on the chemistry and biology of systems and may reveal a wealth of past or contemporary environmental information. In this paper we provide a classification of organic matter quality and examples of potential applications and suitable techniques for the analysis of the main classes of organic matter character. A more consistent approach to organic matter characterisation has the potential to aid understanding of soils and sediments through consideration of decomposition dynamics; accounting for organic matter variety in carbon cycling and budgeting; use of organic proxies of source determination; and investigations into palaeovegetation and palaeoclimate.

Structural characteristics of fulvic acids from Continental Shelf sediments

USGS Publications Warehouse

Hatcher, P.G.; Breger, I.A.; Mattingly, M.A.

1980-01-01

Fulvic acids are those components of soil organic matter that remain soluble after a dilute alkaline extract of the soil is acidified to pH 2 (refs 1, 2). This extraction procedure has been applied to marine sediments, and the organic compounds so recovered have been called marine sedimentary fulvic acids. These fulvic acids are thought to form more complex humic substances in marine sediments by condensation reactions3. However, the chemical structural compositions of marine fulvic acids have not been defined sufficiently to allow this precursor relationship to be made. Here NMR spectroscopy is used to identify more clearly the chemical structural components of some marine sedimentary fulvic acids, thus enabling a more useful examination of their relationship to more complex humic substances. ?? 1980 Nature Publishing Group.

Removal of triazine-based pollutants from water by carbon nanotubes: Impact of dissolved organic matter (DOM) and solution chemistry.

PubMed

Engel, Maya; Chefetz, Benny

2016-12-01

Adsorption of organic pollutants by carbon nanotubes (CNTs) in the environment or removal of pollutants during water purification require deep understanding of the impacts of the presence of dissolved organic matter (DOM). DOM is an integral part of environmental systems and plays a key role affecting the behavior of organic pollutants. In this study, the effects of solution chemistry (pH and ionic strength) and the presence of DOM on the removal of atrazine and lamotrigine by single-walled CNTs (SWCNTs) was investigated. The solubility of atrazine slightly decreased (∼5%) in the presence of DOM, whereas that of lamotrigine was significantly enhanced (by up to ∼70%). Simultaneous introduction of DOM and pollutant resulted in suppression of removal of both atrazine and lamotrigine, which was attributed to DOM-pollutant competition or blockage of adsorption sites by DOM. However the decrease in removal of lamotrigine was also a result of its complexation with DOM. Pre-introduction of DOM significantly reduced pollutant adsorption by the SWCNTs, whereas introduction of DOM after the pollutant resulted in the release of adsorbed atrazine and lamotrigine from the SWCNTs. These data imply that DOM exhibits higher affinity for the adsorption sites than the triazine-based pollutants. In the absence of DOM atrazine was a more effective competitor than lamotrigine for adsorption sites in SWCNTs. However, competition between pollutants in the presence of DOM revealed lamotrigine as the better competitor. Our findings help unravel the complex DOM-organic pollutant-CNT system and will aid in CNT-implementation in water-purification technologies. Copyright © 2016 Elsevier Ltd. All rights reserved.

Biogeography and organic matter removal shape long-term effects of timber harvesting on forest soil microbial communities

Treesearch

Roland C Wilhelm; Erick Cardenas; Kendra R Maas; Hilary Leung; Larisa McNeil; Shannon Berch; William Chapman; Graeme Hope; J M Kranabetter; Stephane Dubé; Matt Busse; Robert Fleming; Paul Hazlett; Kara L Webster; David Morris; D Andrew Scott; William W Mohn

2017-01-01

The growing demand for renewable, carbon-neutral materials and energy is leading to intensified forest land-use. The long-term ecological challenges associated with maintaining soil fertility in managed forests are not yet known, in part due to the complexity of soil microbial communities and the heterogeneity of forest soils. This study determined the long-term...

Leading in Cyclical Environments: An Examination of North American Executive Leadership Styles in Global Semiconductor Organizations

ERIC Educational Resources Information Center

Gray, Terrell A., Sr.

2013-01-01

Perception is reality. No matter how you view yourself, your profile as a leader will be designed for you by those with whom you work and interact. It is vital that your leadership style have an understanding of the human complexities. Well-versed leaders inspire others while educating themselves as part of the continuum of learning (Tinney,…

Effect of humic acids on intestinal viscosity, leaky gut and ammonia excretion in a 24 h feed restriction model to induce intestinal permeability in broiler chickens

USDA-ARS?s Scientific Manuscript database

Humic acids (HA) are produced by biodegradation of organic matter that involves physical, chemical and microbiological processes, hence, HA are a complex mixture of many different acids containing carboxyl and phenolate groups. The purpose of this study was to evaluate the effect of HA on intestina...

Ferrihydrite-associated organic matter (OM) stimulates reduction by Shewanella oneidensis MR-1 and a complex microbial consortia

NASA Astrophysics Data System (ADS)

Cooper, Rebecca Elizabeth; Eusterhues, Karin; Wegner, Carl-Eric; Totsche, Kai Uwe; Küsel, Kirsten

2017-11-01

The formation of Fe(III) oxides in natural environments occurs in the presence of natural organic matter (OM), resulting in the formation of OM-mineral complexes that form through adsorption or coprecipitation processes. Thus, microbial Fe(III) reduction in natural environments most often occurs in the presence of OM-mineral complexes rather than pure Fe(III) minerals. This study investigated to what extent does the content of adsorbed or coprecipitated OM on ferrihydrite influence the rate of Fe(III) reduction by Shewanella oneidensis MR-1, a model Fe(III)-reducing microorganism, in comparison to a microbial consortium extracted from the acidic, Fe-rich Schlöppnerbrunnen fen. We found that increased OM content led to increased rates of microbial Fe(III) reduction by S. oneidensis MR-1 in contrast to earlier findings with the model organism Geobacter bremensis. Ferrihydrite-OM coprecipitates were reduced slightly faster than ferrihydrites with adsorbed OM. Surprisingly, the complex microbial consortia stimulated by a mixture of electrons donors (lactate, acetate, and glucose) mimics S. oneidensis under the same experimental Fe(III)-reducing conditions suggesting similar mechanisms of electron transfer whether or not the OM is adsorbed or coprecipitated to the mineral surfaces. We also followed potential shifts of the microbial community during the incubation via 16S rRNA gene sequence analyses to determine variations due to the presence of adsorbed or coprecipitated OM-ferrihydrite complexes in contrast to pure ferrihydrite. Community profile analyses showed no enrichment of typical model Fe(III)-reducing bacteria, such as Shewanella or Geobacter sp., but an enrichment of fermenters (e.g., Enterobacteria) during pure ferrihydrite incubations which are known to use Fe(III) as an electron sink. Instead, OM-mineral complexes favored the enrichment of microbes including Desulfobacteria and Pelosinus sp., both of which can utilize lactate and acetate as an electron donor under Fe(III)-reducing conditions. In summary, this study shows that increasing concentrations of OM in OM-mineral complexes determines microbial Fe(III) reduction rates and shapes the microbial community structure involved in the reductive dissolution of ferrihydrite. Similarities observed between the complex Fe(III)-reducing microbial consortia and the model Fe(III)-reducer S. oneidensis MR-1 suggest electron-shuttling mechanisms dominate in OM-rich environments, including soils, sediments, and fens, where natural OM interacts with Fe(III) oxides during mineral formation.

Decomposition of heterogeneous organic matterand its long-term stabilization in soils

USGS Publications Warehouse

Sierra, Carlos A.; Harmon, Mark E.; Perakis, Steven S.

2011-01-01

Soil organic matter is a complex mixture of material with heterogeneous biological, physical, and chemical properties. Decomposition models represent this heterogeneity either as a set of discrete pools with different residence times or as a continuum of qualities. It is unclear though, whether these two different approaches yield comparable predictions of organic matter dynamics. Here, we compare predictions from these two different approaches and propose an intermediate approach to study organic matter decomposition based on concepts from continuous models implemented numerically. We found that the disagreement between discrete and continuous approaches can be considerable depending on the degree of nonlinearity of the model and simulation time. The two approaches can diverge substantially for predicting long-term processes in soils. Based on our alternative approach, which is a modification of the continuous quality theory, we explored the temporal patterns that emerge by treating substrate heterogeneity explicitly. The analysis suggests that the pattern of carbon mineralization over time is highly dependent on the degree and form of nonlinearity in the model, mostly expressed as differences in microbial growth and efficiency for different substrates. Moreover, short-term stabilization and destabilization mechanisms operating simultaneously result in long-term accumulation of carbon characterized by low decomposition rates, independent of the characteristics of the incoming litter. We show that representation of heterogeneity in the decomposition process can lead to substantial improvements in our understanding of carbon mineralization and its long-term stability in soils.

Dynamics and ecological risk assessment of chromophoric dissolved organic matter in the Yinma River Watershed: Rivers, reservoirs, and urban waters.

PubMed

Li, Sijia; Zhang, Jiquan; Guo, Enliang; Zhang, Feng; Ma, Qiyun; Mu, Guangyi

2017-10-01

The extensive use of a geographic information system (GIS) and remote sensing in ecological risk assessment from a spatiotemporal perspective complements ecological environment management. Chromophoric dissolved organic matter (CDOM), which is a complex mixture of organic matter that can be estimated via remote sensing, carries and produces carcinogenic disinfection by-products and organic pollutants in various aquatic environments. This paper reports the first ecological risk assessment, which was conducted in 2016, of CDOM in the Yinma River watershed including riverine waters, reservoir waters, and urban waters. Referring to the risk formation theory of natural disaster, the entropy evaluation method and DPSIR (driving force-pressure-state-impact-response) framework were coupled to establish a hazard and vulnerability index with multisource data, i.e., meteorological, remote sensing, experimental, and socioeconomic data, of this watershed. This ecological vulnerability assessment indicator system contains 23 indicators with respect to ecological sensitivity, ecological pressure, and self-resilience. The characteristics of CDOM absorption parameters from different waters showed higher aromatic content and molecular weights in May because of increased terrestrial inputs. The assessment results indicated that the overall ecosystem risk in the study area was focused in the extremely, heavily, and moderately vulnerable regions. The ecological risk assessment results objectively reflect the regional ecological environment and demonstrate the potential of ecological risk assessment of pollutants over traditional chemical measurements. Copyright © 2017. Published by Elsevier Inc.

Pyrolysis-GCMS Analysis of Solid Organic Products from Catalytic Fischer-Tropsch Synthesis Experiments

NASA Technical Reports Server (NTRS)

Locke, Darren R.; Yazzie, Cyriah A.; Burton, Aaron S.; Niles, Paul B.; Johnson, Natasha M.

2015-01-01

Abiotic synthesis of complex organic compounds in the early solar nebula that formed our solar system is hypothesized to occur via a Fischer-Tropsch type (FTT) synthesis involving the reaction of hydrogen and carbon monoxide gases over metal and metal oxide catalysts. In general, at low temperatures (less than 200 C), FTT synthesis is expected to form abundant alkane compounds while at higher temperatures (greater than 200 C) it is expected to product lesser amounts of n-alkanes and greater amounts of alkene, alcohol, and polycyclic aromatic hydrocarbons (PAHs). Experiments utilizing a closed-gas circulation system to study the effects of FTT reaction temperature, catalysts, and number of experimental cycles on the resulting solid insoluble organic products are being performed in the laboratory at NASA Goddard Space Flight Center. These experiments aim to determine whether or not FTT reactions on grain surfaces in the protosolar nebula could be the source of the insoluble organic matter observed in meteorites. The resulting solid organic products are being analyzed at NASA Johnson Space Center by pyrolysis gas chromatography mass spectrometry (PY-GCMS). PY-GCMS yields the types and distribution of organic compounds released from the insoluble organic matter generated from the FTT reactions. Previously, exploratory work utilizing PY-GCMS to characterize the deposited organic materials from these reactions has been reported. Presented here are new organic analyses using magnetite catalyst to produce solid insoluble organic FTT products with varying reaction temperatures and number of experimental cycles.

Dissolved Organic Carbon in Leachate after Application of Granular and Liquid N-P-K Fertilizers to a Sugarcane Soil.

PubMed

Pittaway, P A; Melland, A R; Antille, D L; Marchuk, S

2018-05-01

The progressive decline of soil organic matter (SOM) threatens the sustainability of arable cropping worldwide. Residue removal and burning, destruction of protected microsites, and the acceleration of microbial decomposition are key factors. Desorption of SOM by ammonia-based fertilizers from organomineral complexes in soil may also play a role. A urea- and molasses-based liquid fertilizer formulation and a urea-based granular formulation were applied at recommended and district practice rates, respectively, to soil leaching columns, with unfertilized columns used as controls. The chemistry of leachate collected from the columns, filled with two sandy soils differing in recent cropping history, was monitored over eight successive wet-dry drainage events. The pH, electrical conductivity, and concentration and species of N in leachate was compared with the concentration and aromaticity of dissolved organic C (DOC) to indicate if salt solutions derived from the two fertilizers extracted SOM from clay mineral sites. Cation exchange capacity and exchangeable cations in the soil were monitored at the start and end of the trial. Fertilizer application increased DOC in leachate up to 40 times above the control, but reduced aromaticity (specific ultraviolet light absorbance at 253.7 nm). Dissolved organic C was linearly proportional to leachate NH-N concentration. Exchangeable Ca and Mg in soil from fertilized columns at the end of both trials were significantly lower than in unfertilized soil, indicating that ammonium salt solutions derived from the fertilizers extracted cations and variably charged organic matter from soil mineral exchange sites. Desorption of organic matter and divalent cations from organomineral sites by ammonia-based fertilizers may be implicated in soil acidification. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

Community structure and trophic ecology of megabenthic fauna from the deep basins in the Interior Sea of Chiloé, Chile (41-43° S)

NASA Astrophysics Data System (ADS)

Zapata-Hernández, Germán; Sellanes, Javier; Thiel, Martin; Henríquez, Camila; Hernández, Sebastián; Fernández, Julio C. C.; Hajdu, Eduardo

2016-11-01

Estuarine environments are complex ecological systems, which depend on multiple inputs of organic sources that could support their benthic communities. The deep-water megabenthic communities of the Interior Sea of Chiloé (ISCh, northern part of the fjord region of Chile) were studied to characterize their taxonomic composition and to trace the energy pathways supporting them by using stable isotope analysis (SIA). Megabenthic and demersal organisms as well as sunken macroalgal debris and terrestrial organic matter (TOM: wood, leaves, branches) were obtained by bottom trawling along an estuarine gradient covering 100-460 m water depth. Additionally, particulate organic matter (POM) and the sedimentary organic matter (SOM) were sampled and carbon (δ13C) and nitrogen (δ15N) isotope ratios were determined for all these organisms and potential food sources. A total of 140 taxa were obtained, including invertebrates (e.g. polychaetes, mollusks, crustaceans and echinoderms) bony fishes, rays and sharks. Based on the stable isotope values it was possible to infer a strong dependence on primary production derived from phytoplankton which is exported to the benthos. A potentially important contribution from sunken macroalgae to megabenthic consumers was established only for some invertebrates, such as the irregular echinoid Tripylaster philippii and the decapod Eurypodius latreillii. The trophic structure metrics suggest a similar isotopic niche width, trophic diversity and species packaging in the food webs among the major basins in the ISCh. It is thus concluded that the benthic food webs are supported principally by surface primary production, but macroalgal subsidies could be exploited by selected invertebrate taxa (e.g. detritivores) and terrestrial carbon pathways are important for certain specialized taxa (e.g. Xylophaga dorsalis).

New Exploration on What is Life?

NASA Astrophysics Data System (ADS)

Perkins, D. K.

2006-12-01

Astrobiologists are seeking other life in the universe and we have found over 200 other stars with planets orbiting them. Yet the very definition of life evades us. Where does it begin or end? We cannot yet bind it to fixed parameters. We have also located over 150 organic molecules in space. As well the remarkable discovery has been made that a light spectrum taken through the interstellar dust toward the centre of our galaxy has characteristics similar or identical to the “light fingerprint”, the spectra of particular types of terrestrial bacteria. Charles Birch, Emeritus professor of biology at Sydney University, has discerned that “matter appears to be life-like, rather than life being matter-like”. (Birch, 1999) In the work of the Russian biophysicist, Victor G. Gorshkov, he discusses the “role of the biota” in regulating through genetic programming the environment and eco-systems. (Gorschkov, 2000) In his work on the Gaia hypothesis, James Lovelock, discusses the perception of the dynamic adaptive cybernetic processes that substantiate the functioning of the entire collective global “organism”, utilizing what we call the biota as well as all diverse ecosystems to achieve its organic creative synergism. Yet with all the complexity of our current sciences we have yet to truly understand or find a conclusive definition for life. What role do magnetic fields such as those produced by spinning black holes or magnetars have in the generation of life in cosmos? What in fact is life? A complex geometry uttering the universe or an emergent property of organisms? What is alive? What is now being studying in complexity theory is how all forms seem to essentially arise “spontaneously”, to emerge from the void state as unique mathematical identities. What can this tell us about the nature of life itself?

Late Quaternary paleohydrology deduced from new marine sediment cores taken on the proximal Amazon continental margin

NASA Astrophysics Data System (ADS)

Nace, T.; Baker, P. A.; Dwyer, G. S.; Hollander, D. J.; Silva, C. G.

2010-12-01

Throughout the late Quaternary the Amazon Basin has been influenced by abrupt North-South climate forcing and has undergone several large climate variations as recorded in previously reported speleothem records. Despite its importance in the global carbon cycle there are few continuous, high-resolution records of the Amazon Basin that date back to and beyond the last glacial period. In this study, we report the first results of a marine geological expedition to the Amazon continental shelf and fan region. During this expedition we collected eight ~30 meter piston cores along with gravity, box and multicores. At both sites we undertook complementary multibeam and high resolution seismic reflection profiling. Analyses will be presented from two sets of box/gravity/piston cores. One core (32m) is from a high sedimentation site on the northern flank of the main submarine canyon within the Amazon Fan complex at 1700m water depth. The other core (30m) is located on a seamount to the south of the Amazon Fan complex at 3100m water depth. A mixed assemblage of foraminifera is used for 14C dating to obtain an age model and bulk organic geochemistry is analyzed to determine percent organic carbon, C/N ratios, δ13C and δ15N. The cores were continuously measured shipboard for magnetic susceptibility and gamma density using a GEOTEK logger. These findings uncover the contribution of pelagic and terrestrial organic matter, whether the terrigenous carbon is derived from C3 versus C4 vegetation, and whether the marine organic matter is composed of phytoplankton or marine algae.

Reduction in the exchange of coastal dissolved organic matter and microgels by inputs of extra riverine organic matter.

PubMed

Shiu, Ruei-Feng; Lee, Chon-Lin; Chin, Wei-Chun

2017-12-15

Rivers drive large amounts of terrestrial and riverine organic matter into oceans. These organic materials may alter the self-assembly of marine dissolved organic matter (DOM) polymers into microgels and can even affect the behavior of existing natural microgels. We used Suwannee River humic acid, fulvic acid, and natural organic matter as a model of riverine organic matter (ROM) to investigate the impacts of ROM input on DOM polymer and microgel conversion. Our results indicated that the release of extra ROM, even at low concentrations (0.1-10 mg L -1 ), into the marine organic matter pool decreased the size of self-assembled DOM polymers (from 4-5 μm to < 1 μm) and dispersed the existing natural microgels into smaller particles (from 4-5 μm to 2-3 μm). The particle size of the microgel phase was also less sensitive than that of the DOM polymers to external changes (addition of ROM). This size reduction in DOM aggregation and existing microgels may be closely tied to the surface chemistry of the organic matter, such as negative surface charge stabilization and Ca 2+ cross-linking bridges. These findings reveal that ROM inputs may therefore impede the self-assembly of DOM polymers into particulate organic matter and reduce the sedimentation flux of organic carbon and other elements from surface water to the deep ocean, thereby disturbing the biological pump, the downward transportation of nutrients, and the marine organic carbon cycle. Copyright © 2017 Elsevier Ltd. All rights reserved.

Solving a meiotic LEGO puzzle: transverse filaments and the assembly of the synaptonemal complex in Caenorhabditis elegans.

PubMed

Hawley, R Scott

2011-10-01

The structure of the meiosis-specific synaptonemal complex, which is perhaps the central visible characteristic of meiotic prophase, has been a matter of intense interest for decades. Although a general picture of the interactions between the transverse filament proteins that create this structure has emerged from studies in a variety of organisms, a recent analysis of synaptonemal complex structure in Caenorhabditis elegans by Schild-Prüfert et al. (2011) has provided the clearest picture of the structure of the architecture of a synaptonemal complex to date. Although the transverse filaments of the worm synaptonemal complex are assembled differently then those observed in yeast, mammalian, and Drosophila synaptonemal complexes, a comparison of the four assemblies shows that achieving the overall basic structure of the synaptonemal complex is far more crucial than conserving the structures of the individual transverse filaments.

Use of Amynthas gracilis (Oligochaeta, Megascolecidae) and Bougainvillea litter for rehabilitation of overexploited soils, in Campeche, Yucatan Peninsula, Mexico.

NASA Astrophysics Data System (ADS)

Huerta, Esperanza; Alonso Gongora, Erick

2014-05-01

Yucatan peninsula is one of the recent emerged lands in Mexico; where more of the soils have low organic matter content, and/or the organic horizon is thin (2-5cm). The industry of material extraction for construction purposes is well developed in Yucatan Peninsula, due to the fact of the calcareous material that can be obtained by the maternal rock. Therefore, the material extraction promotes the desertification of the areas, and soil erosion. Bougainvillea sp is a tropical and subtropical woody, evergreen, shrubby vine (Kobayashi et al. 2007), it has a wide range of distribution and it roots are superficial, what allows the plant to inhabit soils with a thin layer of soil organic matter. Earthworms as ecosystem engineers (Jones et al. 1994) can modify their environment, forming borrows and incorporation organic matter into the soil. The aim of this study was to rehabilitate soils without organic matter horizon by the use of earthworms and Bougainvillea litter. The study was developed at mesocosmos level in the laboratory of soils at El Colegio de la Frontera Sur, Unidad Campeche, Mexico. Individual of anecic earthworms were collected and reproduced previously, anecic worms can better incorporate organic matter in to the soil than epigeics or endogeics worms, in Mexican tropical terrestrial ecosystems, anecic worms are almost absent or scarce. In this study we used the exotic earthworm Amynthas gracilis (native in Taiwan),that used to inhabit banana plantations with low technology in southeast Mexico, as exotic has a wide range of tolerance to different amounts of soil organic matter and pH. Four treatments with 4 replicas were established: a) calcareous soil without organic matter horizon+earthworms+litter, b) calcareous soil with organic matter horizon+ earthworms+litter, c) calcareous soil without organic matter horizon+litter, d) calcareous soil with organic matter horizon+litter. After 60 days of study, we observed how earthworms developed successfully in treatments with and without organic matter horizon. Higher amount of litter was incorporated into the soil in those treatments with earthworms. Soil invertebrates populated those treatments with organic matter and earthworms. This study shows that Bougainvillea sp and A. gracilis can be a good combination for rehabilitation of soils without organic matter layer in tropics. Further studies are required in order to observe same results at the field level.

Anthropogenic aerosols as a source of ancient dissolved organic matter in glaciers

USGS Publications Warehouse

Stubbins, Aron; Hood, Eran; Raymond, Peter A.; Aiken, George R.; Sleighter, Rachel L.; Hernes, Peter J.; Butman, David; Hatcher, Patrick G.; Striegl, Robert G.; Schuster, Paul F.; Abdulla, Hussain A.N.; Vermilyea, Andrew W.; Scott, Durelle T.; Spencer, Robert G.M.

2012-01-01

Glacier-derived dissolved organic matter represents a quantitatively significant source of ancient, yet highly bioavailable carbon to downstream ecosystems. This finding runs counter to logical perceptions of age–reactivity relationships, in which the least reactive material withstands degradation the longest and is therefore the oldest. The remnants of ancient peatlands and forests overrun by glaciers have been invoked as the source of this organic matter. Here, we examine the radiocarbon age and chemical composition of dissolved organic matter in snow, glacier surface water, ice and glacier outflow samples from Alaska to determine the origin of the organic matter. Low levels of compounds derived from vascular plants indicate that the organic matter does not originate from forests or peatlands. Instead, we show that the organic matter on the surface of the glaciers is radiocarbon depleted, consistent with an anthropogenic aerosol source. Fluorescence spectrophotometry measurements reveal the presence of protein-like compounds of microbial or aerosol origin. In addition, ultrahigh-resolution mass spectrometry measurements document the presence of combustion products found in anthropogenic aerosols. Based on the presence of these compounds, we suggest that aerosols derived from fossil fuel burning are a source of pre-aged organic matter to glacier surfaces. Furthermore, we show that the molecular signature of the organic matter is conserved in snow, glacier water and outflow, suggesting that the anthropogenic carbon is exported relatively unchanged in glacier outflows.

Distribution and source of organic matter in surface sediment from the muddy deposit along the Zhejiang coast, East China Sea.

PubMed

Xu, Gang; Liu, Jian; Hu, Gang; Jonell, Tara N; Chen, Lilei

2017-10-15

To constrain organic matter compositions and origins, elemental (TOC, TN, C/N) and stable carbon (δ 13 C) and nitrogen isotope (δ 15 N) compositions are measured for surface sediments collected from muddy deposit along the Zhejiang coast, East China Sea. The results showed that the TOC, TN, C/N, δ 13 C, and δ 15 N were 0.19-0.67%, 0.03-0.09%, 6.76-9.22, -23.43 to -20.26‰, and 3.93-5.27‰, respectively. The δ 13 C values showed that the mixing inputs of terrigenous and marine organic matter generally dominated sedimentary organic matter in the west part, and the sedimentary organic matters were mainly influenced by the marine organic matter in the east part of the study area. A stable carbon isotope two end member mixing model estimates ~38% terrestrial -derived and ~62% marine-derived inputs to sedimentary organic matter. Microbial mineralization strongly controls δ 15 N values, and therefore cannot be used to identify the provenance of organic matter for the Zhenjiang coast. Copyright © 2017. Published by Elsevier Ltd.

Insight into dissolved organic matter fractions in Lake Wivenhoe during and after a major flood.

PubMed

Aryal, Rupak; Grinham, Alistair; Beecham, Simon

2016-03-01

Dissolved organic matter is an important component of biogeochemical processes in aquatic environments. Dissolved organic matter may consist of a myriad of different fractions and resultant processing pathways. In early January 2011, heavy rainfall occurred across South East Queensland, Australia causing significant catchment inflow into Lake Wivenhoe, which is the largest water supply reservoir for the city of Brisbane, Australia. The horizontal and vertical distributions of dissolved organic matter fractions in the lake during the flood period were investigated and then compared with stratified conditions with no catchment inflows. The results clearly demonstrate a large variation in dissolved organic matter fractions associated with inflow conditions compared with stratified conditions. During inflows, dissolved organic matter concentrations in the reservoir were fivefold lower than during stratified conditions. Within the dissolved organic matter fractions during inflow, the hydrophobic and humic acid fractions were almost half those recorded during the stratified period whilst low molecular weight neutrals were higher during the flood period compared to during the stratified period. Information on dissolved organic matter and the spatial and vertical variations in its constituents' concentrations across the lake can be very useful for catchment and lake management and for selecting appropriate water treatment processes.

The nature of organic records in impact excavated rocks on Mars

NASA Astrophysics Data System (ADS)

Montgomery, W.; Bromiley, G. D.; Sephton, M. A.

2016-08-01

Impact ejected rocks are targets for life detection missions to Mars. The Martian subsurface is more favourable to organic preservation than the surface owing to an attenuation of radiation and physical separation from oxidising materials with increasing depth. Impact events bring materials to the surface where they may be accessed without complicated drilling procedures. On Earth, different assemblages of organic matter types are derived from varying depositional environments. Here we assess whether these different types of organic materials can survive impact events without corruption. We subjected four terrestrial organic matter types to elevated pressures and temperatures in piston-cylinder experiments followed by chemical characterisation using whole-rock pyrolysis-gas chromatography-mass spectrometry. Our data reveal that long chain hydrocarbon-dominated organic matter (types I and II; mainly microbial or algal) are unresistant to pressure whereas aromatic hydrocarbon-dominated organic matter types (types III and IV; mainly land plant, metamorphosed or degraded, displaying some superficial chemical similarities to abiotic meteoritic organic matter) are relatively resistant. This suggests that the impact excavated record of potential biology on Mars will be unavoidably biased, with microbial organic matter underrepresented while metamorphosed, degraded or abiotic meteoritic organic matter types will be selectively preserved.

The nature of organic records in impact excavated rocks on Mars.

PubMed

Montgomery, W; Bromiley, G D; Sephton, M A

2016-08-05

Impact ejected rocks are targets for life detection missions to Mars. The Martian subsurface is more favourable to organic preservation than the surface owing to an attenuation of radiation and physical separation from oxidising materials with increasing depth. Impact events bring materials to the surface where they may be accessed without complicated drilling procedures. On Earth, different assemblages of organic matter types are derived from varying depositional environments. Here we assess whether these different types of organic materials can survive impact events without corruption. We subjected four terrestrial organic matter types to elevated pressures and temperatures in piston-cylinder experiments followed by chemical characterisation using whole-rock pyrolysis-gas chromatography-mass spectrometry. Our data reveal that long chain hydrocarbon-dominated organic matter (types I and II; mainly microbial or algal) are unresistant to pressure whereas aromatic hydrocarbon-dominated organic matter types (types III and IV; mainly land plant, metamorphosed or degraded, displaying some superficial chemical similarities to abiotic meteoritic organic matter) are relatively resistant. This suggests that the impact excavated record of potential biology on Mars will be unavoidably biased, with microbial organic matter underrepresented while metamorphosed, degraded or abiotic meteoritic organic matter types will be selectively preserved.

The nature of organic records in impact excavated rocks on Mars

PubMed Central

Montgomery, W.; Bromiley, G. D.; Sephton, M. A.

2016-01-01

Impact ejected rocks are targets for life detection missions to Mars. The Martian subsurface is more favourable to organic preservation than the surface owing to an attenuation of radiation and physical separation from oxidising materials with increasing depth. Impact events bring materials to the surface where they may be accessed without complicated drilling procedures. On Earth, different assemblages of organic matter types are derived from varying depositional environments. Here we assess whether these different types of organic materials can survive impact events without corruption. We subjected four terrestrial organic matter types to elevated pressures and temperatures in piston-cylinder experiments followed by chemical characterisation using whole-rock pyrolysis-gas chromatography-mass spectrometry. Our data reveal that long chain hydrocarbon-dominated organic matter (types I and II; mainly microbial or algal) are unresistant to pressure whereas aromatic hydrocarbon-dominated organic matter types (types III and IV; mainly land plant, metamorphosed or degraded, displaying some superficial chemical similarities to abiotic meteoritic organic matter) are relatively resistant. This suggests that the impact excavated record of potential biology on Mars will be unavoidably biased, with microbial organic matter underrepresented while metamorphosed, degraded or abiotic meteoritic organic matter types will be selectively preserved. PMID:27492071

Identification of organic compounds in landfill leachate treated by advanced oxidation processes.

PubMed

Scandelai, Ana Paula Jambers; Sloboda Rigobello, Eliane; Oliveira, Beatriz Lopes Corso de; Tavares, Célia Regina Granhen

2017-11-27

Landfill leachates are considered to be complex effluents of a variable composition containing many biorecalcitrant and highly toxic compounds. Considering the shortage of studies concerning the treatment of landfill leachates using ozone, as well as its combination with catalysts, the aim of this paper was to identify the organic compounds in this effluent treated with advanced oxidation processes (AOPs) of ozonation (O 3 ), and heterogeneous catalytic ozonation with TiO 2 (O 3 /TiO 2 ) and with ZnO (O 3 /ZnO). In addition, this study sought to assess the efficiency of the removal of the organic matter present in the leachate. For the pre- and post-AOPs, the leachate was characterized through physicochemical parameters and identification of organic compounds using gas chromatography coupled to the mass spectrometry (GC-MS). The three processes studied (O 3 , O 3 /TiO 2 , and O 3 /ZnO) presented color removal, turbidity, BOD above 95%, and lower COD removals (19%, 24%, and 33%, respectively). All AOPs studied promoted a similar reduction of organic compounds from leachate, some of which with toxic and carcinogenic potential, such as p-cresol, bisphenol A, atrazine, and hexazinone. In addition, upon the removal of organic matter and organic compounds, the heterogeneous catalytic ozonation processes proved more efficient than the process carried out only with ozone.

Radioastronomical Searches for Instellar Biomolecules

NASA Technical Reports Server (NTRS)

Kuan, Y.-J.; Huang, H.-C.; Charnley, S. B.; Markwick, A.; Botta, O.; Ehrenfreund, P.; Kisiel, Z.; Butner, H. M.

2003-01-01

Impacts of comets and asteroids could have delivered large amounts of organic matter to the early Earth. to retain a significant interstellar signature; observations of recent bright comets indicate that they have a molecular inventory consistent with their ices being largely unmodified interstellar material. Many simple organic molecules with biochemical significance observed in circumstellar envelopes and in molecular clouds, similar to that from which the Solar System formed, may have acted as the precursors of the more complex organics found in meteorites. Therefore, there is potentially a strong link between interstellar organics and prebiotic chemical evolution. Radioastronomical observations, particularly at millimeter wavelengths, allow us to determine the chemical composition and characteristics of the molecular inventory in interstellar space. Here we report some of our recent results from extensive astronomical searches for astrobiologically-important interstellar organics.

Soil organic matter content effects on dermal pesticide bioconcentration in American toads (Bufo americanus).

PubMed

Van Meter, Robin J; Glinski, Donna A; Henderson, W Matthew; Purucker, S Thomas

2016-11-01

Pesticides have been implicated as a major factor in global amphibian declines and may pose great risk to terrestrial phase amphibians moving to and from breeding ponds on agricultural landscapes. Dermal uptake from soil is known to occur in amphibians, but predicting pesticide availability and bioconcentration across soil types is not well understood. The present study was designed to compare uptake of 5 current-use pesticides (imidacloprid, atrazine, triadimefon, fipronil, and pendimethalin) in American toads (Bufo americanus) from exposure on soils with significant organic matter content differences (14.1% = high organic matter and 3.1% = low organic matter). We placed toads on high- or low-organic matter soil after applying individual current-use pesticides on the soil surface for an 8-h exposure duration. Whole body tissue homogenates and soils were extracted and analyzed using liquid chromatography-mass spectrometry to determine pesticide tissue and soil concentration, as well as bioconcentration factor in toads. Tissue concentrations were greater on the low-organic matter soil than the high-organic matter soil across all pesticides (average ± standard error; 1.23 ± 0.35 ppm and 0.78 ± 0.23 ppm, respectively), and bioconcentration was significantly higher for toads on the low-organic matter soil (analysis of covariance p = 0.002). Soil organic matter is known to play a significant role in the mobility of pesticides and bioavailability to living organisms. Agricultural soils typically have relatively lower organic matter content and serve as a functional habitat for amphibians. The potential for pesticide accumulation in amphibians moving throughout agricultural landscapes may be greater and should be considered in conservation and policy efforts. Environ Toxicol Chem 2016;35:2734-2741. © 2016 SETAC. © 2016 SETAC.

Formularity: Software for Automated Formula Assignment of Natural and Other Organic Matter from Ultrahigh-Resolution Mass Spectra

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tolić, Nikola; Liu, Yina; Liyu, Andrey

Ultrahigh-resolution mass spectrometry, such as Fourier transform ion-cyclotron resonance mass spectrometry (FT-ICR MS), can resolve thousands of molecular ions in complex organic matrices. A Compound Identification Algorithm (CIA) was previously developed for automated elemental formula assignment for natural organic matter (NOM). In this work we describe a user friendly interface for CIA, titled Formularity, which includes an additional functionality to perform search of formulas based on an Isotopic Pattern Algorithm (IPA). While CIA assigns elemental formulas for compounds containing C, H, O, N, S, and P, IPA is capable of assigning formulas for compounds containing other elements. We used halogenatedmore » organic compounds (HOC), a chemical class that is ubiquitous in nature as well as anthropogenic systems, as an example to demonstrate the capability of Formularity with IPA. A HOC standard mix was used to evaluate the identification confidence of IPA. The HOC spike in NOM and tap water were used to assess HOC identification in natural and anthropogenic matrices. Strategies for reconciliation of CIA and IPA assignments are discussed. Software and sample databases with documentation are freely available from the PNNL OMICS software repository https://omics.pnl.gov/software/formularity.« less

Heavy metal stabilization in contaminated road-derived sediments.

PubMed

Rijkenberg, Micha J A; Depree, Craig V

2010-02-01

There is increasing interest in the stabilization of heavy metals in road-derived sediments (RDS), to enable environmentally responsible reuse applications and circumvent the need for costly landfill disposal. To reduce the mobility of heavy metals (i.e. Cu, Pb and Zn) the effectiveness of amendments using phosphate, compost and fly ash addition were investigated using batch leaching experiments. In general, phosphate amendments of RDS were found to be ineffective at stabilizing heavy metals, despite being used successfully in soils. Phosphate amendment resulted in enhanced concentrations of dissolved organic carbon (DOC), which increased the solubilisation of heavy metals via complexation. Amendment with humified organic matter (compost) successfully stabilized Cu and Pb in high DOC leaching RDS with an optimum loading of 15-20% (w/w). Compost, however, was ineffective at stabilizing Zn. Increasing the pH by amending RDS/compost blends with 2.5-15% (w/w) coal fly ash resulted in the stabilization of Zn, Cu and Pb. However, above a pH of approximately 7.5 and 8 enhanced leaching of organic matter resulted in an increase in leached Cu and Pb, respectively. Accordingly, the optimum level of fly ash amendment for the RDS/compost blends was estimated to be ca. 10%. Boosted regression trees analysis (BRT) of the data revealed that DOC accounted for 56% and 65% of the Cu and Pb leaching, respectively, whereas pH only accounted for ca. 18% of Cu and Pb leaching. RDS sample characteristics (i.e. metal concentrations, size fractionation and organic matter content) were more important at reconciling the leaching concentrations of copper Cu (27%) than Pb (16%). The most important parameter explaining Zn leaching was pH. Overall, the choice of a suitable stabilization agent/s depends on the composition of RDS with respect to the amount of organic matter present, and the sorption chemistry of the heavy metal of interest. Copyright 2009 Elsevier B.V. All rights reserved.

Metals in Devonian kerogenous marine strata at Gibellini and Bisoni properties in southern Fish Creek Range, Eureka County, Nevada

USGS Publications Warehouse

Desborough, George A.; Poole, F.G.; Hose, R.K.; Radtke, A.S.

1979-01-01

A kerogen-rich sequence of siliceous mudstone, siltstone, and chert as much as 60 m thick on ridge 7129 in the southern Fish Creek Range, referred to as Gibellini facies of the Woodruff Formation, has been evaluated on the surface and in drill holes principally for its potential resources of vanadium, zinc, selenium, molybdenum, and syncrude oil content. The strata are part of a strongly deformed allochthonous mass of eugeosynclinal Devonian marine rocks that overlie deformed allochthonous Mississippian siliceous rocks and relatively undeformed autochthonous Mississippian Antler flysch at this locality. The vanadium in fresh black rocks obtained from drill holes and fresh exposures in trenches and roadcuts occurs chiefly in organic matter. Concentrations of vanadium oxide (V2O5) in unoxidized samples range from 3,000 to 7,000 ppm. In oxidized and bleached rock that is prevalent at the surface, concentrations of vanadium oxide range from 6,000 to 8,000 ppm, suggesting a tendency toward enrichment due to surficial weathering and ground-water movement. Zinc occurs in sphalerite, and selenium occurs in organic matter; molybdenum appears to occur both in molybdenite and in organic matter. Concentrations of zinc in unoxidized rock range from 4,000 to 18,000 ppm, whereas in oxidized rock they range from 30 to 100 ppm, showing strong depletion due to weathering. Concentrations of selenium in unoxidized rock range from 30 to 200 ppm, whereas in oxidized rock they range from 200 to 400 ppm, indicating some enrichment upon weathering. Concentrations of molybdenum in unoxidized rock range from 70 to 960 ppm, whereas in oxidized rock they range from 30 to 80 ppm, indicating strong depletion upon weathering. Most fresh black rock is low-grade oil shale, and yields as much as 12 gallons/short ton of syncrude oil. Metahewettite is the principal vanadium mineral in the oxidized zone, but it also occurs sparsely as small nodules and fillings of microfractures in unweathered strata. In fresh rock, bluish-white opaline-like silica (chalcedonic quartz) fills microfractures, and is believed to have originated by diagenetic mobilization of opaline silica from radiolarian tests and sponge spicules. As revealed by microscopic study, the Gibellini facies originally consisted of siliceous muds, slimes, and oozes high in organic constituents. The organic matter is amorphous flaky and stringy sapropel, and probably includes remains of bacteria, phytoplankton, zooplankton, and minor higher plants. Recognizable organic remnants include radiolarian tests, sponge spicules, conodonts, brachiopod shells, algae, and humic debris. Diagnostic radiolarians indicate a Late Devonian age for the Gibellini facies of the Woodruff Formation. Some pyrite is disseminated through the rock and may be primary (syngenetic) but significant pyrite and marcasite occur in chalcedonic quartz veinlets and appear to be diagenetic. In fresh rock, black solid bitumen and liquid oil fill voids and microfractures. These early phase hydrocarbons probably were released during diagenesis from complex nonhydrocarbon molecular structures originating from living organisms, and formed without any major thermal degradation of the kerogen. Gas chromatographic analysis of the saturated hydrocarbon fraction indicates a very complex mixture dominated by branched and cyclic compounds. Conodont and palynomorph color alteration, vitrinite reflectance, and other organic geochemical data suggest that the organic matter in the rock is thermally immature and has not been subjected to temperatures greater than 60?C since deposition in Devonian time. All of these characteristics are consistent with the interpretation of a relatively low temperature and a shallow-burial history for the Gibellini facies on ridge 7129.

Supramolecular chemistry: from molecular information towards self-organization and complex matter

NASA Astrophysics Data System (ADS)

Lehn, Jean-Marie

2004-03-01

Molecular chemistry has developed a wide range of very powerful procedures for constructing ever more sophisticated molecules from atoms linked by covalent bonds. Beyond molecular chemistry lies supramolecular chemistry, which aims at developing highly complex chemical systems from components interacting via non-covalent intermolecular forces. By the appropriate manipulation of these interactions, supramolecular chemistry became progressively the chemistry of molecular information, involving the storage of information at the molecular level, in the structural features, and its retrieval, transfer, and processing at the supramolecular level, through molecular recognition processes operating via specific interactional algorithms. This has paved the way towards apprehending chemistry also as an information science. Numerous receptors capable of recognizing, i.e. selectively binding, specific substrates have been developed, based on the molecular information stored in the interacting species. Suitably functionalized receptors may perform supramolecular catalysis and selective transport processes. In combination with polymolecular organization, recognition opens ways towards the design of molecular and supramolecular devices based on functional (photoactive, electroactive, ionoactive, etc) components. A step beyond preorganization consists in the design of systems undergoing self-organization, i.e. systems capable of spontaneously generating well-defined supramolecular architectures by self-assembly from their components. Self-organization processes, directed by the molecular information stored in the components and read out at the supramolecular level through specific interactions, represent the operation of programmed chemical systems. They have been implemented for the generation of a variety of discrete functional architectures of either organic or inorganic nature. Self-organization processes also give access to advanced supramolecular materials, such as supramolecular polymers and liquid crystals, and provide an original approach to nanoscience and nanotechnology. In particular, the spontaneous but controlled generation of well-defined, functional supramolecular architectures of nanometric size through self-organization represents a means of performing programmed engineering and processing of nanomaterials. Supramolecular chemistry is intrinsically a dynamic chemistry, in view of the lability of the interactions connecting the molecular components of a supramolecular entity and the resulting ability of supramolecular species to exchange their constituents. The same holds for molecular chemistry when a molecular entity contains covalent bonds that may form and break reversibly, so as to make possible a continuous change in constitution and structure by reorganization and exchange of building blocks. This behaviour defines a constitutional dynamic chemistry that allows self-organization by selection as well as by design at both the molecular and supramolecular levels. Whereas self-organization by design strives to achieve full control over the output molecular or supramolecular entity by explicit programming, self-organization by selection operates on dynamic constitutional diversity in response to either internal or external factors to achieve adaptation in a Darwinistic fashion. The merging of the features, information and programmability, dynamics and reversibility, constitution and structural diversity, points towards the emergence of adaptative and evolutionary chemistry. Together with the corresponding fields of physics and biology, it constitutes a science of informed matter, of organized, adaptative complex matter. This article was originally published in 2003 by the Israel Academy of Sciences and Humanities in the framework of its Albert Einstein Memorial Lectures series. Reprinted by permission of the Israel Academy of Sciences and Humanities.

Effect of a seasonal diffuse pollution migration on natural organic matter behavior in a stratified dam reservoir.

PubMed

Yu, Soon Ju; Lee, Jae Yil; Ha, Sung Ryong

2010-01-01

This article aims to describe the influence of diffuse pollution on the temporal and spatial characteristics of natural organic matter (NOM) in a stratified dam reservoir, the Daecheong Dam, on the basis of intensive observation results and the dynamic water quality simulation using CE-QUAL-W2. Turbidity is regarded as a comprehensive representation of allochothonous organic matter from diffuse sources in storm season because the turbidity concentration showed reasonable significance in a statistical correlation with the UV absorbance at 254 nm and total phosphorus. CE-QUAL-W2 simulation results showed good consistency with the observed data in terms of dissolved organic matter (DOM) including refractory dissolved organic carbon (RDOC) and labile DOC and also well explained the internal movement of constituents and stratification phenomenon in the reservoir. Instead turbidity and NOM were related well in the upper region of the reservoir according to flow distance, gradually as changing to dissolved form of organic matter, RDOM affected organic matter concentration of reservoir water quality compared to turbidity. To control the increase of soluble organic matters in the dam reservoir, appropriate dam water discharge gate operation provided effective measurement. Because of the gate operation let avoid the accumulation of organic matter within a dam reservoir by shorten of turbid regime retention time.

Seasonal and spatial variability of the OM/OC mass ratios and high regional correlation between oxalic acid and zinc in Chinese urban organic aerosols

NASA Astrophysics Data System (ADS)

Xing, L.; Fu, T.-M.; Cao, J. J.; Lee, S. C.; Wang, G. H.; Ho, K. F.; Cheng, M.-C.; You, C.-F.; Wang, T. J.

2013-04-01

We calculated the organic matter to organic carbon mass ratios (OM/OC mass ratios) in PM2.5 collected from 14 Chinese cities during summer and winter of 2003 and analyzed the causes for their seasonal and spatial variability. The OM/OC mass ratios were calculated two ways. Using a mass balance method, the calculated OM/OC mass ratios averaged 1.92 ± 0.39 year-round, with no significant seasonal or spatial variation. The second calculation was based on chemical species analyses of the organic compounds extracted from the PM2.5 samples using dichloromethane/methanol and water. The calculated OM/OC mass ratio in summer was relatively high (1.75 ± 0.13) and spatially-invariant due to vigorous photochemistry and secondary organic aerosol (OA) production throughout the country. The calculated OM/OC mass ratio in winter (1.59 ± 0.18) was significantly lower than that in summer, with lower values in northern cities (1.51 ± 0.07) than in southern cities (1.65 ± 0.15). This likely reflects the wider usage of coal for heating purposes in northern China in winter, in contrast to the larger contributions from biofuel and biomass burning in southern China in winter. On average, organic matter constituted 36% and 34% of Chinese urban PM2.5 mass in summer and winter, respectively. We report, for the first time, a high regional correlation between Zn and oxalic acid in Chinese urban aerosols in summer. This is consistent with the formation of stable Zn oxalate complex in the aerosol phase previously proposed by Furukawa and Takahashi (2011). We found that many other dicarboxylic acids were also highly correlated with Zn in the summer Chinese urban aerosol samples, suggesting that they may also form stable organic complexes with Zn. Such formation may have profound implications for the atmospheric abundance and hygroscopic properties of aerosol dicarboxylic acids.

Light absorption properties of colored dissolved organic matter (CDOM) in adjacent waters of the Changjiang Estuary during a flood season: implication for DOC estimation

NASA Astrophysics Data System (ADS)

Liu, Yangyang; Shen, Fang; Li, Xiuzhen

2014-11-01

Light absorption properties of colored dissolved organic matter (CDOM) in adjacent waters of the Changjiang Estuary were investigated during the summer of 2013. CDOM absorption showed a substantial portion of the total absorption and clearly dominant among most investigation stations. It generally decreased from the northwest to the southeast, which controlled by physical mixing of fresh water and seawater as was indicated by a conservative behaviour of CDOM. CDOM absorption sharply increased during phytoplankton blooms. Similarly, dissolved organic carbon (DOC) also peaked during blooms period. However, DOC exhibited a more complex behavior relative to a simple conservative mixing, possibly attributed to multiple origins of DOC. CDOM absorption and DOC co-varied to some degree, implying a potential way of DOC estimation from CDOM absorption. However, more detailed information such as CDOM and DOC composition and more validation data were required to obtain a stable CDOM - DOC pattern. Lastly, empirical algorithms with limited data were developed to retrieve CDOM absorption. Further validation of the algorithms were needed when they were to be commonly applied.

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.

Distribution of pyrethroid insecticides in secondary wastewater effluent

PubMed Central

Parry, Emily; Young, Thomas M.

2014-01-01

Although the freely dissolved form of hydrophobic organic chemicals may best predict aquatic toxicity, differentiating between dissolved and particle bound forms is challenging at environmentally relevant concentrations for compounds with low toxicity thresholds such as pyrethroid insecticides. We investigated the distribution of pyrethroids among three forms: freely dissolved, complexed with dissolved organic carbon (DOC), and sorbed to suspended particulate matter, during a yearlong study at a secondary wastewater treatment plant. Effluent was fractionated by laboratory centrifugation to determine if sorption was driven by particle size. Linear distribution coefficients were estimated for pyrethroid sorption to suspended particulate matter (Kid) and dissolved organic carbon (Kidoc) at environmentally relevant pyrethroid concentrations. Resulting Kid values were higher than those reported for other environmental solids, and variation between sampling events correlated well with available particle surface area. Fractionation results suggest that no more than 40% of the pyrethroid remaining in secondary effluent could be removed by extending settling periods. Less than 6%of the total pyrethroid load in wastewater effluent was present in the dissolved form across all sampling events and chemicals. PMID:23939863

Vanadium Chloroperoxidases: The Missing Link in the Formation of Chlorinated Compounds and Chloroform in the Terrestrial Environment?

PubMed

Wever, Ron; Barnett, Phil

2017-08-17

It is well established that the majority of chlorinated organic substances found in the terrestrial environment are produced naturally. The presence of these compounds in soils is not limited to a single ecosystem. Natural chlorination is also a widespread phenomenon in grasslands and agricultural soils typical for unforested areas. These chlorinated compounds are formed from chlorination of natural organic matter consisting of very complex chemical structures, such as lignin. Chlorination of several lignin model compounds results in the intermediate formation of trichloroacetyl-containing compounds, which are also found in soils. These decay, in general, through a haloform-type reaction mechanism to CHCl 3 . Upon release into the atmosphere, CHCl 3 will produce chlorine radicals through photolysis, which will, in turn, lead to natural depletion of ozone. There is evidence that fungal chloroperoxidases able to produce HOCl are involved in the chlorination of natural organic matter. The objective of this review is to clarify the role and source of the various chloroperoxidases involved in the natural formation of CHCl 3 . © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Performance evaluation of the UV/H2O2 process on selected nitrogenous organic compounds: reductions of organic contents vs. corresponding C-, N-DBPs formations.

PubMed

Chen, Huei-Wen; Chen, Chia-Yang; Wang, Gen-Shuh

2011-10-01

The presence of various organic contaminants in water sources is of concern due to their direct threats to human health and potential to react with disinfectants to form carcinogenic byproducts including trihalomethanes, haloacetic acids and nitrosamines in finished water. This study applied both medium-pressure and low-pressure ultraviolet light coupled with hydrogen peroxide (UV/H2O2) to evaluate its efficacy for degradation of selected nitrogenous organic compounds and corresponding disinfection byproduct (DBP) formation. Six organic compounds were chosen as target precursors based on their nitrogen contents and molecular structures. The results showed that higher oxidation capacity resulted in better reduction of organic matters and DBP formation potentials (DBPFPs). However, insufficient contact time and oxidant doses could lead to a rise of DBPFPs in the early stages of UV/H2O2 reactions. A greater percentage removal was achieved for organic carbon than organic nitrogen after UV/H2O2 treatment, especially for compounds with complicated structure such as diltiazem. During the UV/H2O2 treatment, the intermediate products include tertiary amine, dimethyl amine (DMA) or DMA-like structures, which are N-nitrosodimethylamine (NDMA) precursors after chlorination or chloramination. Furthermore, it was observed that using dissolved organic nitrogen and DMA to predict NDMAFP could lead to biased conclusions because of the complex nature of nitrogenous matters in aqueous environments. Copyright © 2011 Elsevier Ltd. All rights reserved.

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.

Organic matter content of soil after logging of fir and redwood forests

Treesearch

Philip B. Durgin

1980-01-01

Organic matter in soil controls a variety of soil properties. A study in Humboldt County, California, evaluated changes in percentages of organic matter in soil as a function of time after timber harvest and soil depth in fir and redwood forests. To assess organic matter content, samples were taken from cutblocks of various ages in soil to depths of 1.33 m. Results...

Electron transfer properties of peat organic matter: from electrochemical analysis to redox processes in peatlands

NASA Astrophysics Data System (ADS)

Sander, Michael; Getzinger, Gordon; Walpen, Nicolas

2017-04-01

Peat organic matter contains redox-active functional groups that can accept and/or donate electrons from and to biotic and abiotic reaction partners present in peatlands. Several studies have provided evidence that electron accepting quinone moieties in the peat organic matter may act as terminal electron acceptors for anaerobic microbial respiration. This respiration pathway may competitively suppress methanogenesis and thereby lead to excess carbon dioxide to methane formation in peatlands. Electron donating phenolic moieties in peat organic matter have long been considered to inhibit microbial and enzymatic activities in peatlands, thereby contributing to carbon stabilization and accumulation in these systems. Phenols are expected to be comparatively stable in anoxic parts of the peats as phenoloxidases, a class of enzymes capable of oxidatively degrading phenols, require molecular oxygen as co-substrate. Despite the general recognition of the importance of redox-active moieties in peat organic matter, the abundance, redox properties and reactivities of these moieties remain poorly studied and understood, in large part due to analytical challenges. This contribution will, in a first part, summarize recent advances in our research group on the analytical chemistry of redox-active moieties in peat organic matter. We will show how mediated electrochemical analysis can be used to quantify the capacities of electron accepting and donating moieties in both dissolved and particulate peat organic matter. We will link these capacities to the physicochemical properties of peat organic matter and provide evidence for quinones and phenols as major electron accepting and donating moieties, respectively. The second part of this contribution will highlight how these electroanalytical techniques can be utilized to advance a more fundamental understanding of electron transfer processes involving peat organic matter. These processes include the redox cycling (i.e., repeated reduction and re-oxidation) of peat organic matter under alternating anoxic-oxic conditions as well as the oxidation of phenolic moieties in peat organic matter by phenol oxidases in the presence of molecular oxygen. Overall, this contribution will attempt to link molecular-level insights into the redox properties of peat organic matter to larger scale redox processes that are important to carbon cycling in peatlands.

Non-Destructive High-Resolution Organic Matter Record on Lake Sediment using Steady-State Solid Phase Fluorescence: Organic Matter Quality and Quantity Assessment.

NASA Astrophysics Data System (ADS)

Quiers, M.; Perrette, Y.; Etienne, D.; Develle, A. L.; Jacq, K.

2017-12-01

The use of organic proxies increases in paleoenvironmental reconstructions from natural archives. Major advances have been achieved by the development of new highly informative molecular proxies usually linked to specific compounds. While studies focused on targeted compounds, offering a high information degree, advances on bulk organic matter are limited. However, this bulk is the main contributor to carbon cycle and has been shown to be a driver of many mineral or organic compounds transfer and record. Development of target proxies need complementary information on bulk organic matter to understand biases link to controlling factors or analytical methods, and provide a robust interpretation. Fluorescence methods have often been employed to characterize and quantify organic matter. However, these technics are mainly developed for liquid samples, inducing material and resolution loss when working on natural archives (either stalagmite or sediments). High-resolution solid phase fluorescence (SPF) was developed on speleothems. This method allows now to analyse organic matter quality and quantity if procedure to constrain the optical density are adopted. In fact, a calibration method using liquid phase fluorescence (LPF) was developed for speleothem, allowing to quantify organic carbon at high-resolution. We report here an application of such a procedure SPF/LPF measurements on lake sediments. In order to avoid sediment matrix effects on the fluorescence signal, a calibration using LPF measurements was realised. First results using this method provided organic matter quality record of different organic matter compounds (humic-like, protein-like and chlorophylle-like compounds) at high resolution for the sediment core. High resolution organic matter fluxes are obtained in a second time, applying pragmatic chemometrics model (non linear models, partial least square models) on high resolution fluorescence data. SPF method can be considered as a promising tool for high resolution record on organic matter quality and quantity. Potential application of this method will be evocated (lake ecosystem dynamic, changes in trophic levels)

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...

Toxicity of natural mixtures of organic pollutants in temperate and polar marine phytoplankton.

PubMed

Echeveste, Pedro; Galbán-Malagón, Cristóbal; Dachs, Jordi; Berrojalbiz, Naiara; Agustí, Susana

2016-11-15

Semivolatile and persistent organic pollutants (POPs) undergo atmospheric transport before being deposited to the oceans, where they partition to phytoplankton organic matter. The goal of this study was to determine the toxicity of naturally occurring complex mixtures of organic pollutants to temperate and polar phytoplankton communities from the Mediterranean Sea, the North East (NE) Atlantic, and Southern Oceans. The cell abundance of the different phytoplankton groups, chlorophyll a concentrations, viability of the cells, and growth and decay constants were monitored in response to addition of a range of concentrations of mixtures of organic pollutants obtained from seawater extracts. Almost all of the phytoplankton groups were significantly affected by the complex mixtures of non-polar and polar organic pollutants, with toxicity being greater for these mixtures than for single POPs or simple POP mixtures. Cocktails' toxicity arose at concentrations as low as tenfold the field oceanic levels, probably due to a higher chemical activity of the mixture than of simple POPs mixtures. Overall, smaller cells were the most affected, although Mediterranean picophytoplankton was significantly more tolerant to non-polar POPs than picophytoplankton from the Atlantic Ocean or the Bellingshausen Sea microphytoplankton. Copyright © 2016 Elsevier B.V. All rights reserved.

From which soil metal fractions Fe, Mn, Zn and Cu are taken up by olive trees (Olea europaea L., cv. 'Chondrolia Chalkidikis') in organic groves?

PubMed

Chatzistathis, T; Papaioannou, A; Gasparatos, D; Molassiotis, A

2017-12-01

Organic farming has been proposed as an alternative agricultural system to help solve environmental problems, like the sustainable management of soil micronutrients, without inputs of chemical fertilizers. The purposes of this study were: i) to assess Fe, Mn, Zn and Cu bioavailability through the determination of sequentially extracted chemical forms (fractions) and their correlation with foliar micronutrient concentrations in mature organic olive (cv. 'Chondrolia Chalkidikis') groves; ii) to determine the soil depth and the available forms (fractions) by which the 4 metals are taken up by olive trees. DTPA extractable (from the soil layers 0-20, 20-40 and 40-60 cm) and foliar micronutrient concentrations were determined in two organic olive groves. Using the Tessier fractionation, five fractions, for all the metals, were found: exchangeable, bound to carbonates (acid-soluble), bound to Fe-Mn oxides (reducible), organic (oxidizable), as well as residual form. Our results indicated that Fe was taken up by the olive trees as organic complex, mainly from the soil layer 40-60 cm. Manganese was taken up from the exchangeable fraction (0-20 cm); Zinc was taken up as organic complex from the layers 0-20 and 40-60 cm, as well as in the exchangeable form from the upper 20 cm. Copper was taken up from the soil layers 0-20 and 40-60 cm as soluble organic complex, and as exchangeable ion from the upper 20 cm. Our data reveal the crucial role of organic matter to sustain metal (Fe, Zn and Cu) uptake -as soluble complexes-by olive trees, in mature organic groves grown on calcareous soils; it is also expected that these data will constitute a thorough insight and useful tool towards a successful nutrient and organic C management for organic olive groves, since no serious nutritional deficiencies were found. Copyright © 2017 Elsevier Ltd. All rights reserved.

Dynamic modeling the composting process of the mixture of poultry manure and wheat straw.

PubMed

Petric, Ivan; Mustafić, Nesib

2015-09-15

Due to lack of understanding of the complex nature of the composting process, there is a need to provide a valuable tool that can help to improve the prediction of the process performance but also its optimization. Therefore, the main objective of this study is to develop a comprehensive mathematical model of the composting process based on microbial kinetics. The model incorporates two different microbial populations that metabolize the organic matter in two different substrates. The model was validated by comparison of the model and experimental data obtained from the composting process of the mixture of poultry manure and wheat straw. Comparison of simulation results and experimental data for five dynamic state variables (organic matter conversion, oxygen concentration, carbon dioxide concentration, substrate temperature and moisture content) showed that the model has very good predictions of the process performance. According to simulation results, the optimum values for air flow rate and ambient air temperature are 0.43 l min(-1) kg(-1)OM and 28 °C, respectively. On the basis of sensitivity analysis, the maximum organic matter conversion is the most sensitive among the three objective functions. Among the twelve examined parameters, μmax,1 is the most influencing parameter and X1 is the least influencing parameter. Copyright © 2015 Elsevier Ltd. All rights reserved.

Determination of the speciation and bioavailability of samarium to Chlamydomonas reinhardtii in the presence of natural organic matter.

PubMed

Rowell, Justine-Anne; Fillion, Marc-Alexandre; Smith, Scott; Wilkinson, Kevin J

2018-06-01

As technological interest and environmental emissions of the rare earth elements increase, it is becoming more important to assess their potential environmental impact. Samarium (Sm) is a lanthanide of intermediate molar mass that is used in numerous high-technology applications including wind turbines, solar panels, and electric vehicles. The present study relates the speciation of Sm determined in the presence of natural organic matter (NOM) to its bioavailability to the unicellular green alga Chlamydomonas reinhardtii. The free ion concentration was determined using a cation exchange resin (ion exchange technique) in dynamic mode and compared with thermodynamic modeling. Short-term biouptake experiments were performed in the presence of 4 types of NOM: Suwannee River fulvic acids, Pahokee Peat fulvic acids, Suwannee River humic acids, and a Luther Marsh dissolved organic matter isolate (90-95% humic acids). It was clearly shown that even a small amount of NOM (0.5 mg C L -1 ) resulted in a significant decrease (10 times) in the Sm internalization fluxes. Furthermore, complexation with humic acids (and the corresponding reduction in Sm bioavailability) was stronger than that with fulvic acids. The results showed that the experimentally measured (free) Sm was a better predictor of Sm internalization than either the total concentrations or the free ion concentrations obtained using thermodynamic modeling. Environ Toxicol Chem 2018;37:1623-1631. © 2018 SETAC. © 2018 SETAC.

The influence of large wood accumulations on riparian seed bank diversity

NASA Astrophysics Data System (ADS)

Osei, N. A.

2012-04-01

Little is known about the structure and complexity of seed bank within the riparian corridor and the how large wood accumulations contribute to riparian seed bank diversity. This study aimed to examine and quantify seed bank assemblage and diversity along the undisturbed riparian corridor of the Highland Water, a second order lowland stream draining the New Forest. Seed bank samples were collected from five riparian corridor microhabitats namely mid-channel bars, floodplains, bare banks, banks adjacent large wood accumulations and within large wood accumulations that differed in their hydrologic connectivity with the river. Descriptive statistics and ordination methods applied to the floristic and sediment data sets indicates that sediment organic matter content, species richness and proportions of functional types distinctly differed among the riparian microhabitats types but there was no difference in viable seed densities. Banks adjacent large wood accumulations were the most floristically diverse and rich in organic matter with mid-channel bars exhibiting the reverse. This was due to the ability of large wood accumulations to buffer varying magnitudes of physical gradients and sort seeds and sediments, therefore altering the character of bare banks. This study not only strengthen the evidence that riparian corridors exhibit elevated spatial sediment and vegetation heterogeneity but also demonstrates the importance of large wood accumulation as habitat modifiers, ecosystem engineers and conservation sink for moisture, organic matter and seeds, resources essential for riparian vegetation conservation, recovery and restoration efforts.

Microbiome characterization of MFCs used for the treatment of swine manure.

PubMed

Vilajeliu-Pons, Anna; Puig, Sebastià; Pous, Narcís; Salcedo-Dávila, Inmaculada; Bañeras, Lluís; Balaguer, Maria Dolors; Colprim, Jesús

2015-05-15

Conventional swine manure treatment is performed by anaerobic digestion, but nitrogen is not treated. Microbial Fuel Cells (MFCs) allow organic matter and nitrogen removal with concomitant electricity production. MFC microbiomes treating industrial wastewaters as swine manure have not been characterized. In this study, a multidisciplinary approach allowed microbiome relation with nutrient removal capacity and electricity production. Two different MFC configurations (C-1 and C-2) were used to treat swine manure. In C-1, the nitrification and denitrification processes took place in different compartments, while in C-2, simultaneous nitrification-denitrification occurred in the cathode. Clostridium disporicum and Geobacter sulfurreducens were identified in the anode compartments of both systems. C. disporicum was related to the degradation of complex organic matter compounds and G. sulfurreducens to electricity production. Different nitrifying bacteria populations were identified in both systems because of the different operational conditions. The highest microbial diversity was detected in cathode compartments of both configurations, including members of Bacteroidetes, Chloroflexiaceae and Proteobacteria. These communities allowed similar removal rates of organic matter (2.02-2.09 kg COD m(-3)d(-1)) and nitrogen (0.11-0.16 kg Nm(-3)d(-1)) in both systems. However, they differed in the generation of electric energy (20 and 2 mW m(-3) in C-1 and C-2, respectively). Copyright © 2015 Elsevier B.V. All rights reserved.

Visible light photodegradation of phenanthrene catalyzed by Fe(III)-smectite: role of soil organic matter.

PubMed

Jia, Hanzhong; Li, Li; Fan, Xiaoyun; Liu, Mingdeng; Deng, Wenye; Wang, Chuanyi

2013-07-15

In the present study, phenanthrene is employed as a model to explore the roles played by three soil organic matter (SOM) fractions, i.e., dissolved organic matter (DOM), humic acid (HA), and fulvic acid (FA), in its photodegradation with assistance of Fe(III)-smectite under visible-light. Slight decrease in phenanthrene photodegradation rate was observed in the presence of DOM, which is explained in terms of oxidative-radical competition between DOM and target phenanthrene molecules due to the high electron-donor capacity of phenolic moieties in DOM. On the other hand, a critic content is observed with FA (0.70mg/g) and HA (0.65mg/g). Before reaching the critic content, the removal of phenanthrene is accelerated; while after that, the photodegradation rate is suppressed. The acceleration of phenanthrene degradation can be attributed to the photosensitization of FA and HA. Due to the strong interaction between phenanthrene and the phenyl rings, however, the retention of phenanthrene on SOM-Fe(III)-smectite in the presence of high content of HA or FA is enhanced, thus slowing down its photodegradation. Those observations provide valuable insights into the transformation and fate of PAHs in the natural soil environment and open a window for using clay-humic substances complexes for remediation of contaminated soil. Copyright © 2013 Elsevier B.V. All rights reserved.

Selective Leaching of Dissolved Organic Matter From Alpine Permafrost Soils on the Qinghai-Tibetan Plateau

NASA Astrophysics Data System (ADS)

Wang, Yinghui; Xu, Yunping; Spencer, Robert G. M.; Zito, Phoebe; Kellerman, Anne; Podgorski, David; Xiao, Wenjie; Wei, Dandan; Rashid, Harunur; Yang, Yuanhe

2018-03-01

Ongoing global temperature rise has caused significant thaw and degradation of permafrost soils on the Qinghai-Tibetan Plateau (QTP). Leaching of organic matter from permafrost soils to aquatic systems is highly complex and difficult to reproduce in a laboratory setting. We collected samples from natural seeps of active and permafrost layers in an alpine swamp meadow on the QTP to shed light on the composition of mobilized dissolved organic matter (DOM) by combining optical measurements, ultrahigh-resolution Fourier transform ion cyclotron resonance mass spectrometry, radiocarbon (14C), and solid-state 13C nuclear magnetic resonance spectroscopy. Our results show that even though the active layer soils contain large amounts of proteins and carbohydrates, there is a selective release of aromatic components, whereas in the deep permafrost layer, carbohydrate and protein components are preferentially leached during the thawing process. Given these different chemical characteristics of mobilized DOM, we hypothesize that photomineralization contributes significantly to the loss of DOM that is leached from the seasonally thawed surface layer. However, with continued warming, biodegradation will become more important since biolabile materials such as protein and carbohydrate are preferentially released from deep-layer permafrost soils. This transition in DOM leachate source and associated chemical composition has ramifications for downstream fluvial networks on the QTP particularly in terms of processing of carbon and associated fluxes.

The structure and origin of dissolved organic matter studied by UV-vis spectroscopy and fluorescence spectroscopy in lake in arid and semi-arid region.

PubMed

Guo, Xu-jing; Xi, Bei-dou; Yu, Hui-bin; Ma, Wen-chao; He, Xiao-song

2011-01-01

To develop a proper indicator which could predict water quality and trace pollution sources is critically important for the management of sustainable aquatic ecosystem. In our study, seven water samples collected from Wuliangsuhai Lake in Inner Mongolia were used. UV-visible spectra and synchronous fluorescence spectra were applied to investigate the humification degree and aromatic structure of dissolved organic matter (DOM) extracted from water samples. The results showed that both samples from W1 site and W3 site display lower humification degree and less aromatic structure, where industrial wastewater and domestic sewage, and reclaimed water of farmland irrigation, were accepted respectively. After computing the values of SUVA(254), A(280), A(250/365), A(253/203) and A(226-400), we reached the conclusion that they have a consistent trend (W4> W6> W5> W2> W7> W1> W3). Fluorescence index (f(450/500)) was always utilised to interpret the origin of organic matter in a complex aquatic environment system. Values of f(450/500) are closer to 1.60, indicating that humic substances derived from terrestrial sources and biological sources. Our study demonstrated that reclaimed water of farmland irrigation, industrial wastewater and domestic sewage will definitely influence the humification degree and amount of the aromatic structure of DOM.

Light-driven dynamic Archimedes spirals and periodic oscillatory patterns of topological solitons in anisotropic soft matter

DOE PAGES

Martinez, Angel; Smalyukh, Ivan I.

2015-02-12

Oscillatory and excitable systems very commonly exhibit formation of dynamic non-equilibrium patterns. For example, rotating spiral patterns are observed in biological, chemical, and physical systems ranging from organization of slime mold cells to Belousov-Zhabotinsky reactions, and to crystal growth from nuclei with screw dislocations. Here we describe spontaneous formation of spiral waves and a large variety of other dynamic patterns in anisotropic soft matter driven by low-intensity light. The unstructured ambient or microscope light illumination of thin liquid crystal films in contact with a self-assembled azobenzene monolayer causes spontaneous formation, rich spatial organization, and dynamics of twisted domains and topologicalmore » solitons accompanied by the dynamic patterning of azobenzene group orientations within the monolayer. Linearly polarized incident light interacts with the twisted liquid crystalline domains, mimicking their dynamics and yielding patterns in the polarization state of transmitted light, which can be transformed to similar dynamic patterns in its intensity and interference color. This shows that the delicate light-soft-matter interaction can yield complex self-patterning of both. Finally, we uncover underpinning physical mechanisms and discuss potential uses.« less

Metatranscriptomic Analysis Reveals Unexpectedly Diverse Microbial Metabolism in a Biogeochemical Hot Spot in an Alluvial Aquifer

DOE PAGES

Jewell, Talia N. M.; Karaoz, Ulas; Bill, Markus; ...

2017-01-25

Organic matter deposits in alluvial aquifers have been shown to result in the formation of naturally reduced zones (NRZs), which can modulate aquifer redox status and influence the speciation and mobility of metals, affecting groundwater geochemistry. In this study, we sought to better understand how natural organic matter fuels microbial communities within anoxic biogeochemical hot spots (NRZs) in a shallow alluvial aquifer at the Rifle (CO) site. We conducted a 20-day microcosm experiment in which NRZ sediments, which were enriched in buried woody plant material, served as the sole source of electron donors and microorganisms. The microcosms were constructed andmore » incubated under anaerobic conditions in serum bottles with an initial N 2 headspace and were sampled every 5 days for metagenome and metatranscriptome profiles in combination with biogeochemical measurements. Biogeochemical data indicated that the decomposition of native organic matter occurred in different phases, beginning with mineralization of dissolved organic matter (DOM) to CO 2 during the first week of incubation, followed by a pulse of acetogenesis that dominated carbon flux after 2 weeks. A pulse of methanogenesis co-occurred with acetogenesis, but only accounted for a small fraction of carbon flux. The depletion of DOM over time was strongly correlated with increases in expression of many genes associated with heterotrophy (e.g., amino acid, fatty acid, and carbohydrate metabolism) belonging to a Hydrogenophaga strain that accounted for a relatively large percentage (~8%) of the metatranscriptome. This Hydrogenophaga strain also expressed genes indicative of chemolithoautotrophy, including CO 2 fixation, H 2 oxidation, S-compound oxidation, and denitrification. The pulse of acetogenesis appears to have been collectively catalyzed by a number of different organisms and metabolisms, most prominently pyruvate:ferredoxin oxidoreductase. Unexpected genes were identified among the most highly expressed (>98th percentile) transcripts, including acetone carboxylase and cell-wall-associated hydrolases with unknown substrates (numerous lesser expressed cell-wall-associated hydrolases targeted peptidoglycan). Many of the most highly expressed hydrolases belonged to a Ca. Bathyarchaeota strain and may have been associated with recycling of bacterial biomass. Overall, these results highlight the complex nature of organic matter transformation in NRZs and the microbial metabolic pathways that interact to mediate redox status and elemental cycling.« less

Metatranscriptomic Analysis Reveals Unexpectedly Diverse Microbial Metabolism in a Biogeochemical Hot Spot in an Alluvial Aquifer

PubMed Central

Jewell, Talia N. M.; Karaoz, Ulas; Bill, Markus; Chakraborty, Romy; Brodie, Eoin L.; Williams, Kenneth H.; Beller, Harry R.

2017-01-01

Organic matter deposits in alluvial aquifers have been shown to result in the formation of naturally reduced zones (NRZs), which can modulate aquifer redox status and influence the speciation and mobility of metals, affecting groundwater geochemistry. In this study, we sought to better understand how natural organic matter fuels microbial communities within anoxic biogeochemical hot spots (NRZs) in a shallow alluvial aquifer at the Rifle (CO) site. We conducted a 20-day microcosm experiment in which NRZ sediments, which were enriched in buried woody plant material, served as the sole source of electron donors and microorganisms. The microcosms were constructed and incubated under anaerobic conditions in serum bottles with an initial N2 headspace and were sampled every 5 days for metagenome and metatranscriptome profiles in combination with biogeochemical measurements. Biogeochemical data indicated that the decomposition of native organic matter occurred in different phases, beginning with mineralization of dissolved organic matter (DOM) to CO2 during the first week of incubation, followed by a pulse of acetogenesis that dominated carbon flux after 2 weeks. A pulse of methanogenesis co-occurred with acetogenesis, but only accounted for a small fraction of carbon flux. The depletion of DOM over time was strongly correlated with increases in expression of many genes associated with heterotrophy (e.g., amino acid, fatty acid, and carbohydrate metabolism) belonging to a Hydrogenophaga strain that accounted for a relatively large percentage (~8%) of the metatranscriptome. This Hydrogenophaga strain also expressed genes indicative of chemolithoautotrophy, including CO2 fixation, H2 oxidation, S-compound oxidation, and denitrification. The pulse of acetogenesis appears to have been collectively catalyzed by a number of different organisms and metabolisms, most prominently pyruvate:ferredoxin oxidoreductase. Unexpected genes were identified among the most highly expressed (>98th percentile) transcripts, including acetone carboxylase and cell-wall-associated hydrolases with unknown substrates (numerous lesser expressed cell-wall-associated hydrolases targeted peptidoglycan). Many of the most highly expressed hydrolases belonged to a Ca. Bathyarchaeota strain and may have been associated with recycling of bacterial biomass. Overall, these results highlight the complex nature of organic matter transformation in NRZs and the microbial metabolic pathways that interact to mediate redox status and elemental cycling. PMID:28179898

Metatranscriptomic Analysis Reveals Unexpectedly Diverse Microbial Metabolism in a Biogeochemical Hot Spot in an Alluvial Aquifer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jewell, Talia N. M.; Karaoz, Ulas; Bill, Markus

Organic matter deposits in alluvial aquifers have been shown to result in the formation of naturally reduced zones (NRZs), which can modulate aquifer redox status and influence the speciation and mobility of metals, affecting groundwater geochemistry. In this study, we sought to better understand how natural organic matter fuels microbial communities within anoxic biogeochemical hot spots (NRZs) in a shallow alluvial aquifer at the Rifle (CO) site. We conducted a 20-day microcosm experiment in which NRZ sediments, which were enriched in buried woody plant material, served as the sole source of electron donors and microorganisms. The microcosms were constructed andmore » incubated under anaerobic conditions in serum bottles with an initial N 2 headspace and were sampled every 5 days for metagenome and metatranscriptome profiles in combination with biogeochemical measurements. Biogeochemical data indicated that the decomposition of native organic matter occurred in different phases, beginning with mineralization of dissolved organic matter (DOM) to CO 2 during the first week of incubation, followed by a pulse of acetogenesis that dominated carbon flux after 2 weeks. A pulse of methanogenesis co-occurred with acetogenesis, but only accounted for a small fraction of carbon flux. The depletion of DOM over time was strongly correlated with increases in expression of many genes associated with heterotrophy (e.g., amino acid, fatty acid, and carbohydrate metabolism) belonging to a Hydrogenophaga strain that accounted for a relatively large percentage (~8%) of the metatranscriptome. This Hydrogenophaga strain also expressed genes indicative of chemolithoautotrophy, including CO 2 fixation, H 2 oxidation, S-compound oxidation, and denitrification. The pulse of acetogenesis appears to have been collectively catalyzed by a number of different organisms and metabolisms, most prominently pyruvate:ferredoxin oxidoreductase. Unexpected genes were identified among the most highly expressed (>98th percentile) transcripts, including acetone carboxylase and cell-wall-associated hydrolases with unknown substrates (numerous lesser expressed cell-wall-associated hydrolases targeted peptidoglycan). Many of the most highly expressed hydrolases belonged to a Ca. Bathyarchaeota strain and may have been associated with recycling of bacterial biomass. Overall, these results highlight the complex nature of organic matter transformation in NRZs and the microbial metabolic pathways that interact to mediate redox status and elemental cycling.« less

Variation of preserving organic matter bound in interlayer of montmorillonite induced by microbial metabolic process.

PubMed

Zhao, Yulian; Dong, Faqin; Dai, Qunwei; Li, Gang; Ma, Jie

2017-07-25

This paper aimed to investigate the variation of preserving organic matter bound in the interlayer space of montmorillonite (Mt) induced by a microbe metabolic process. We selected Bacillus pumilus as the common soil native bacteria. The alteration of d 001 value, functional group, and C,N organic matter contents caused by bacteria were analyzed by XRD, FTIR, and elementary analyzer, respectively. XRD results showed that the d 001 value of montmorillonite increased with the concentration decreasing and decreased with the culture time increasing after interacting with bacteria indicating the interlayer space of montmorillonite was connected with the organic matter. The findings of long-term interaction by resetting culture conditions implied that the montmorillonite buffered the organic matter when the nutrition was enough and released again when the nutrition was lacking. The results of the elementary analyzer declared the content of organic matter was according to the d 001 value of montmorillonite and N organic matter which played a major impact. FTIR results confirmed that the Si-O stretching vibrations of Mt were affected by the functional group of organic matter. Our results showed that the montmorillonite under the influence of soil bacteria has a strong buffering capacity for preserving organic matter into the interlayer space in a short-term. It might provide critical implications for understanding the evolution process and the preservation of fertilization which was in the over-fertilization or less-fertilization conditions on farmland.

Structural stability of coprecipitated natural organic matter and ferric iron under reducing conditions

USGS Publications Warehouse

Henneberry, Yumiko K.; Kraus, Tamara E.C.; Nico, Peter S.; Horwath, William R.

2012-01-01

The objective was to assess the interaction of Fe coprecipitated with dissolved organic matter (DOM) and its effect on Fe (hydr)oxide crystallinity and DOM retention under abiotic reducing conditions. A Fe-based coagulant was reacted with DOM from an agricultural drain and the resulting precipitate (floc) was exposed to S(-II) and Fe(II). Solution concentrations of Fe(II/III) and DOM were monitored, floc crystallinity was determined using X-ray diffraction, and the composition and distribution of functional groups were assessed using scanning transmission X-ray microscopy (STXM) and near edge X-ray absorption fine structure (NEXAFS) spectroscopy. Results indicate coprecipitation of Fe(III) with DOM forms a non-crystalline floc that withstands crystallization regardless of change in pH, Fe:DOM ratio and type of reductant added. There was no evidence that exposure to reducing conditions led to release of DOM from the floc, indicating that coprecipitation with complex natural DOM in aquatic environments may stabilize Fe (hydr)oxides against crystallization upon reaction with reduced species and lead to long term sequestration of the DOM. STXM analysis identified spatially distinct regions with remarkable functional group purity, contrary to the model of DOM as a relatively uniform complex polymer lacking identifiable organic compounds. Polysaccharide-like OM was strongly and directly correlated with the presence of Fe but showed different Fe binding strength depending on the presence of carboxylic acid functional groups, whereas amide and aromatic functional groups were inversely correlated with Fe content.

Emergent Vortex Patterns in Systems of Self-Propelled, Chiral Particles

NASA Astrophysics Data System (ADS)

Huber, Lorenz; Denk, Jonas; Reithmann, Emanuel; Frey, Erwin

Self-organization of FtsZ polymers is vital for Z-ring assembly during bacterial cell division, and has been studied using reconstituted in vitro model systems. Employing Brownian dynamics simulations and a Boltzmann approach, we model FtsZ polymers as active particles moving along chiral circular paths. With both theoretical approaches we find self-organization into vortex structures and characterize different states in parameter states. Our work demonstrates that these patterns are robust and are generic for active chiral matter. Moreover, we show that the dynamics at the onset of pattern formation is described by a generalized complex Ginzburg-Landau equation.

Activations in gray and white matter are modulated by uni-manual responses during within and inter-hemispheric transfer: effects of response hand and right-handedness.

PubMed

Diwadkar, Vaibhav A; Bellani, Marcella; Chowdury, Asadur; Savazzi, Silvia; Perlini, Cinzia; Marinelli, Veronica; Zoccatelli, Giada; Alessandrini, Franco; Ciceri, Elisa; Rambaldelli, Gianluca; Ruggieri, Mirella; Carlo Altamura, A; Marzi, Carlo A; Brambilla, Paolo

2017-08-14

Because the visual cortices are contra-laterally organized, inter-hemispheric transfer tasks have been used to behaviorally probe how information briefly presented to one hemisphere of the visual cortex is integrated with responses resulting from the ipsi- or contra-lateral motor cortex. By forcing rapid information exchange across diverse regions, these tasks robustly activate not only gray matter regions, but also white matter tracts. It is likely that the response hand itself (dominant or non-dominant) modulates gray and white matter activations during within and inter-hemispheric transfer. Yet the role of uni-manual responses and/or right hand dominance in modulating brain activations during such basic tasks is unclear. Here we investigated how uni-manual responses with either hand modulated activations during a basic visuo-motor task (the established Poffenberger paradigm) alternating between inter- and within-hemispheric transfer conditions. In a large sample of strongly right-handed adults (n = 49), we used a factorial combination of transfer condition [Inter vs. Within] and response hand [Dominant(Right) vs. Non-Dominant (Left)] to discover fMRI-based activations in gray matter, and in narrowly defined white matter tracts. These tracts were identified using a priori probabilistic white matter atlases. Uni-manual responses with the right hand strongly modulated activations in gray matter, and notably in white matter. Furthermore, when responding with the left hand, activations during inter-hemispheric transfer were strongly predicted by the degree of right-hand dominance, with increased right-handedness predicting decreased fMRI activation. Finally, increasing age within the middle-aged sample was associated with a decrease in activations. These results provide novel evidence of complex relationships between uni-manual responses in right-handed subjects, and activations during within- and inter-hemispheric transfer suggest that the organization of the motor system exerts sophisticated functional effects. Moreover, our evidence of activation in white matter tracts is consistent with prior studies, confirming fMRI-detectable white matter activations which are systematically modulated by experimental condition.

Organic Donor-Acceptor Complexes as Novel Organic Semiconductors.

PubMed

Zhang, Jing; Xu, Wei; Sheng, Peng; Zhao, Guangyao; Zhu, Daoben

2017-07-18

Organic donor-acceptor (DA) complexes have attracted wide attention in recent decades, resulting in the rapid development of organic binary system electronics. The design and synthesis of organic DA complexes with a variety of component structures have mainly focused on metallicity (or even superconductivity), emission, or ferroelectricity studies. Further efforts have been made in high-performance electronic investigations. The chemical versatility of organic semiconductors provides DA complexes with a great number of possibilities for semiconducting applications. Organic DA complexes extend the semiconductor family and promote charge separation and transport in organic field-effect transistors (OFETs) and organic photovoltaics (OPVs). In OFETs, the organic complex serves as an active layer across extraordinary charge pathways, ensuring the efficient transport of induced charges. Although an increasing number of organic semiconductors have been reported to exhibit good p- or n-type properties (mobilities higher than 1 or even 10 cm 2 V -1 s -1 ), critical scientific challenges remain in utilizing the advantages of existing semiconductor materials for more and wider applications while maintaining less complicated synthetic or device fabrication processes. DA complex materials have revealed new insight: their unique molecular packing and structure-property relationships. The combination of donors and acceptors could offer practical advantages compared with their unimolecular materials. First, growing crystals of DA complexes with densely packed structures will reduce impurities and traps from the self-assembly process. Second, complexes based on the original structural components could form superior mixture stacking, which can facilitate charge transport depending on the driving force in the coassembly process. Third, the effective use of organic semiconductors can lead to tunable band structures, allowing the operation mode (p- or n-type) of the transistor to be systematically controlled by changing the components. Finally, theoretical calculations based on cocrystals with unique stacking could widen our understanding of structure-property relationships and in turn help us design high-performance semiconductors based on DA complexes. In this Account, we focus on discussing organic DA complexes as a new class of semiconducting materials, including their design, growth methods, packing modes, charge-transport properties, and structure-property relationships. We have also fabricated and investigated devices based on these binary crystals. This interdisciplinary work combines techniques from the fields of self-assembly, crystallography, condensed-matter physics, and theoretical chemistry. Researchers have designed new complex systems, including donor and acceptor compounds that self-assemble in feasible ways into highly ordered cocrystals. We demonstrate that using this crystallization method can easily realize ambipolar or unipolar transport. To further improve device performance, we propose several design strategies, such as using new kinds of donors and acceptors, modulating the energy alignment of the donor (ionization potential, IP) and acceptor (electron affinity, EA) components, and extending the π-conjugated backbones. In addition, we have found that when we use molecular "doping" (2:1 cocrystallization), the charge-transport nature of organic semiconductors can be switched from hole-transport-dominated to electron-transport-dominated. We expect that the formation of cocrystals through the complexation of organic donor and acceptor species will serve as a new strategy to develop semiconductors for organic electronics with superior performances over their corresponding individual components.

Coping with the Bounds: Speculations on Nonlinearity in Military Affairs

DTIC Science & Technology

2003-08-01

organizing criticality, cellular automata, solitons, and so on–because they all globally share this property . Nonlinearity reflects the science of the...Why does it matter? One rea- son for emphasizing nonlinearity is that it constitutes the well-established mathematical property underlying and making...have some hints as to what those principles might be.3 Complex adaptive systems, or cas, contain seven basic attributes. These consist of four properties

Modeling of the structure-specific kinetics of abiotic, dark reduction of Hg(II) complexed by O/N and S functional groups in humic acids while accounting for time-dependent structural rearrangement

USDA-ARS?s Scientific Manuscript database

Redox transformations involving electron transfer from natural organic matter (NOM) are important for the mercury (Hg) biogeochemical cycle. In the water column light drives the reduction of Hg(II) to Hg(0), whereas in soils and sediments dark reduction of Hg(II) is of greater importance. The object...

Fluorescence-based proxies for lignin in freshwater dissolved organic matter

USGS Publications Warehouse

Hernes, Peter J.; Bergamaschi, Brian A.; Eckard, Robert S.; Spencer, Robert G.M.

2009-01-01

Lignin phenols have proven to be powerful biomarkers in environmental studies; however, the complexity of lignin analysis limits the number of samples and thus spatial and temporal resolution in any given study. In contrast, spectrophotometric characterization of dissolved organic matter (DOM) is rapid, noninvasive, relatively inexpensive, requires small sample volumes, and can even be measured in situ to capture fine-scale temporal and spatial detail of DOM cycling. Here we present a series of cross-validated Partial Least Squares models that use fluorescence properties of DOM to explain up to 91% of lignin compositional and concentration variability in samples collected seasonally over 2 years in the Sacramento River/San Joaquin River Delta in California, United States. These models were subsequently used to predict lignin composition and concentration from fluorescence measurements collected during a diurnal study in the San Joaquin River. While modeled lignin composition remained largely unchanged over the diurnal cycle, changes in modeled lignin concentrations were much greater than expected and indicate that the sensitivity of fluorescence-based proxies for lignin may prove invaluable as a tool for selecting the most informative samples for detailed lignin characterization. With adequate calibration, similar models could be used to significantly expand our ability to study sources and processing of DOM in complex surface water systems.

Applied Technology on Influence of Humic Substances on Fertilizer, Water-use Efficiency and Soil Health

NASA Astrophysics Data System (ADS)

Seyedbagheri, Mir

2017-04-01

In continuation of over 35 years of on-farm studies on soil organic matter from different humates (functional carbon) and compost, I have documented quantitative improvements in soil health and water-use efficiency. The ability of soil organic matter to bind water has become an important theme for research in past years. Research trials were established to evaluate the efficacy of different commercial functional carbon products derived from Leonardite (highly oxidized lignite) in crop production. In each of these trials, functional carbon (Humic and Fulvic acids) products were used in a randomized complete block design. The use of humic substances creates strong organo-mineral complexes (aggregation), chelation, as well as enhanced buffering capacities. We evaluated data from 3 fields and compared the results. Our observation and field demonstrations indicated there was a marked increase in water retention. Data from humic acid (HA) trials showed that different cropping systems responded differently to different products in relation to yield and quality. The functional carbon products used in the study seemed to enhance fertilizer and water-use efficiency by increasing complexation, chelation and buffering. The consistent use of good quality functional carbons in our replicated plots resulted in a yield increase from 6% to 30% over several decades.

Dissolved Organic Matter Quality in a Shallow Aquifer of Bangladesh: Implications for Arsenic Mobility.

PubMed

Mladenov, Natalie; Zheng, Yan; Simone, Bailey; Bilinski, Theresa M; McKnight, Diane M; Nemergut, Diana; Radloff, Kathleen A; Rahman, M Moshiur; Ahmed, Kazi Matin

2015-09-15

In some high arsenic (As) groundwater systems, correlations are observed between dissolved organic matter (DOM) and As concentrations, but in other systems, such relationships are absent. The role of labile DOM as the main driver of microbial reductive dissolution is not sufficient to explain the variation in DOM-As relationships. Other processes that may also influence As mobility include complexation of As by dissolved humic substances, and competitive sorption and electron shuttling reactions mediated by humics. To evaluate such humic DOM influences, we characterized the optical properties of filtered surface water (n = 10) and groundwater (n = 24) samples spanning an age gradient in Araihazar, Bangladesh. Further, we analyzed large volume fulvic acid (FA) isolates (n = 6) for optical properties, C and N content, and (13)C NMR spectroscopic distribution. Old groundwater (>30 years old) contained primarily sediment-derived DOM and had significantly higher (p < 0.001) dissolved As concentration than groundwater that was younger than 5 years old. Younger groundwater had DOM spectroscopic signatures similar to surface water DOM and characteristic of a sewage pollution influence. Associations between dissolved As, iron (Fe), and FA concentration and fluorescence properties of isolated FA in this field study suggest that aromatic, terrestrially derived FAs promote As-Fe-FA complexation reactions that may enhance As mobility.

The impact of sea-level rise on organic matter decay rates in Chesapeake Bay brackish tidal marshes

USGS Publications Warehouse

Kirwanm, M.L.; Langley, J.A.; Guntenspergen, Gleen R.; Megonigal, J.P.

2013-01-01

The balance between organic matter production and decay determines how fast coastal wetlands accumulate soil organic matter. Despite the importance of soil organic matter accumulation rates in influencing marsh elevation and resistance to sea-level rise, relatively little is known about how decomposition rates will respond to sea-level rise. Here, we estimate the sensitivity of decomposition to flooding by measuring rates of decay in 87 bags filled with milled sedge peat, including soil organic matter, roots and rhizomes. Experiments were located in field-based mesocosms along 3 mesohaline tributaries of the Chesapeake Bay. Mesocosm elevations were manipulated to influence the duration of tidal inundation. Although we found no significant influence of inundation on decay rate when bags from all study sites were analyzed together, decay rates at two of the sites increased with greater flooding. These findings suggest that flooding may enhance organic matter decay rates even in water-logged soils, but that the overall influence of flooding is minor. Our experiments suggest that sea-level rise will not accelerate rates of peat accumulation by slowing the rate of soil organic matter decay. Consequently, marshes will require enhanced organic matter productivity or mineral sediment deposition to survive accelerating sea-level rise.

The impact of sea-level rise on organic matter decay rates in Chesapeake Bay brackish tidal marshes

NASA Astrophysics Data System (ADS)

Kirwan, M. L.; Langley, J. A.; Guntenspergen, G. R.; Megonigal, J. P.

2013-03-01

The balance between organic matter production and decay determines how fast coastal wetlands accumulate soil organic matter. Despite the importance of soil organic matter accumulation rates in influencing marsh elevation and resistance to sea-level rise, relatively little is known about how decomposition rates will respond to sea-level rise. Here, we estimate the sensitivity of decomposition to flooding by measuring rates of decay in 87 bags filled with milled sedge peat, including soil organic matter, roots and rhizomes. Experiments were located in field-based mesocosms along 3 mesohaline tributaries of the Chesapeake Bay. Mesocosm elevations were manipulated to influence the duration of tidal inundation. Although we found no significant influence of inundation on decay rate when bags from all study sites were analyzed together, decay rates at two of the sites increased with greater flooding. These findings suggest that flooding may enhance organic matter decay rates even in water-logged soils, but that the overall influence of flooding is minor. Our experiments suggest that sea-level rise will not accelerate rates of peat accumulation by slowing the rate of soil organic matter decay. Consequently, marshes will require enhanced organic matter productivity or mineral sediment deposition to survive accelerating sea-level rise.

The impact of sea-level rise on organic matter decay rates in Chesapeake Bay brackish tidal marshes

NASA Astrophysics Data System (ADS)

Kirwan, M. L.; Langley, J. A.; Guntenspergen, G. R.; Megonigal, J. P.

2012-10-01

The balance between organic matter production and decay determines how fast coastal wetlands accumulate soil organic matter. Despite the importance of soil organic matter accumulation rates in influencing marsh elevation and resistance to sea-level rise, relatively little is known about how decomposition rates will respond to sea-level rise. Here, we estimate the sensitivity of decomposition to flooding by measuring rates of decay in 87 bags filled with milled sedge peat, including soil organic matter, roots and rhizomes. Experiments were located in field-based mesocosms along 3 mesohaline tributaries of the Chesapeake Bay. Mesocosm elevations were manipulated to influence the duration of tidal inundation. Although we found no significant influence of inundation on decay rate when bags from all study sites were analyzed together, decay rates at two of the sites increased with greater flooding. These findings suggest that flooding may enhance organic matter decay rates even in water-logged soils, but that the overall influence of flooding is minor. Our experiments suggest that sea-level rise will not accelerate rates of peat accumulation by slowing the rate of soil organic matter decay. Consequently, marshes will require enhanced organic matter productivity or mineral sediment deposition to survive accelerating sea-level rise.

40 CFR 503.41 - Special definitions.

Code of Federal Regulations, 2012 CFR

2012-07-01

... device in which organic matter and inorganic matter in sewage sludge are combusted in a bed of particles... combustion of organic matter and inorganic matter in sewage sludge by high temperatures in an enclosed device... accordance with 40 CFR 51.100 (ii). (p) Total hydrocarbons means the organic compounds in the exit gas from a...

40 CFR 503.41 - Special definitions.

Code of Federal Regulations, 2011 CFR

2011-07-01

... device in which organic matter and inorganic matter in sewage sludge are combusted in a bed of particles... combustion of organic matter and inorganic matter in sewage sludge by high temperatures in an enclosed device... accordance with 40 CFR 51.100 (ii). (p) Total hydrocarbons means the organic compounds in the exit gas from a...

40 CFR 503.41 - Special definitions.

Code of Federal Regulations, 2014 CFR

2014-07-01

... device in which organic matter and inorganic matter in sewage sludge are combusted in a bed of particles... combustion of organic matter and inorganic matter in sewage sludge by high temperatures in an enclosed device... accordance with 40 CFR 51.100 (ii). (p) Total hydrocarbons means the organic compounds in the exit gas from a...

40 CFR 503.41 - Special definitions.

Code of Federal Regulations, 2013 CFR

2013-07-01

... device in which organic matter and inorganic matter in sewage sludge are combusted in a bed of particles... combustion of organic matter and inorganic matter in sewage sludge by high temperatures in an enclosed device... accordance with 40 CFR 51.100 (ii). (p) Total hydrocarbons means the organic compounds in the exit gas from a...

Analysis of organic grain coatings in primitive interplanetary dust particles: Implications for the origin of Solar System organic matter

NASA Astrophysics Data System (ADS)

Flynn, George

Analysis of organic grain coatings in primitive interplanetary dust particles: Implications for the origin of Solar System organic matter Chondritic, porous interplanetary dust particles (CP IDPs), the most primitive samples of extraterrestrial material available for laboratory analysis [1], are unequilibrated aggregates of mostly submicron, anhydrous grains of a diverse mineralogy. They contain organic matter not produced by parent body aqueous processing [2], some carrying H and N isotopic anomalies consistent with molecular cloud or outer Solar System material [3]. Scanning Transmission X-Ray Microscope (STXM) imaging at the C K-edge shows the individual grains in 10 micron aggregate CP IDPs are coated by a layer of carbonaceous material 100 nm thick. This structure implies a three-step formation sequence. First, individual grains condensed from the cooling nebular gas. Then complex, refractory organic molecules covered the surfaces of the grains either by deposition, formation in-situ, or a combination of both processes. Finally, the grains collided and stuck together forming the first dust-size material in the Solar System. Ultramicrotome sections, 70 to 100 nm thick were cut from several CP IDPs, embedded in elemental S to avoid exposure to C-based embedding media. X-ray Absorption Near Edge Structure (XANES) spectra were derived from image stacks obtained using a STXM. "Cluster analysis" was used to compare the C-XANES spectra from each of the pixels in an image stack and identify pixels exhibiting similar spectra. When applied to a CP IDP, cluster analysis identifies most carbonaceous grain coatings in a particle as having similar C-XANES spectra. Two processes are commonly suggested in the literature for production of organic grain coatings. The similarity in thickness and C-XANES spectra of the coatings on different minerals in the same IDP indicates the first, mineral specific catalysis, was not the process that produced these organic rims. Our results are consistent with this primitive organic matter being produced by the alternative process of condensation of C-bearing ices onto the grain surfaces and production of refractory organic matter by UV or other ionizing radiation bombardment of the ices [4]. The processes by which primitive grains aggregate to form the first dust of our Solar System are not well understood. Collision experiments indicate that bare rocky grains bounce apart at collision speeds ¡30 to 50 m/s and shatter at larger speeds [5]. However, experiments indicate grains coated with organic matter stick quite easily, even at speeds up to 5 m/s -an order of magnitude higher than the speed at which silicate grains accrete [6]. Thus the organic grain coatings we identified likely played a critical role in dust aggregation in the early Solar System. References: [1] Ishii, H. et al. Science 2009. [2] Flynn, G. J. et al. (2003) Geochim. Cosmochim. Acta, 67, 4791-4806. [3] Keller L. P. et al. GCA (2004) Geochim. Cosmochim. Acta, 68, 2577-2589. [4] Bernstein, M. P. et al. (1995) Astrophys. J., 454, 327-344. [5] Hartmann, W. K. (1978) Icarus, 33, 50-61. [6] Kudo, T. et al. (2002) Meteoritics Planet. Sci., 37, 1975-1983.

40 CFR 63.4351 - How do I demonstrate initial compliance?

Code of Federal Regulations, 2013 CFR

2013-07-01

... the organic HAP emissions reductions by applying the volatile organic matter collection and recovery... cumulative amount of volatile organic matter recovered by the solvent recovery system for the compliance... of the mass of volatile organic matter recovered. (ii) For each solvent recovery system, determine...

40 CFR 63.3961 - How do I demonstrate initial compliance?

Code of Federal Regulations, 2012 CFR

2012-07-01

... balances, calculate the organic HAP emission reduction by applying the volatile organic matter collection... device that indicates the cumulative amount of volatile organic matter recovered by the solvent recovery....0 percent of the mass of volatile organic matter recovered. (2) For each solvent recovery system...

40 CFR 63.3961 - How do I demonstrate initial compliance?

Code of Federal Regulations, 2014 CFR

2014-07-01

... balances, calculate the organic HAP emission reduction by applying the volatile organic matter collection... device that indicates the cumulative amount of volatile organic matter recovered by the solvent recovery....0 percent of the mass of volatile organic matter recovered. (2) For each solvent recovery system...

40 CFR 63.4351 - How do I demonstrate initial compliance?

Code of Federal Regulations, 2014 CFR

2014-07-01

... the organic HAP emissions reductions by applying the volatile organic matter collection and recovery... cumulative amount of volatile organic matter recovered by the solvent recovery system for the compliance... of the mass of volatile organic matter recovered. (ii) For each solvent recovery system, determine...

40 CFR 63.4351 - How do I demonstrate initial compliance?

Code of Federal Regulations, 2012 CFR

2012-07-01

... the organic HAP emissions reductions by applying the volatile organic matter collection and recovery... cumulative amount of volatile organic matter recovered by the solvent recovery system for the compliance... of the mass of volatile organic matter recovered. (ii) For each solvent recovery system, determine...

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...

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...