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. ...

Natural organic matter properties in Swedish agricultural streams

NASA Astrophysics Data System (ADS)

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

2016-04-01

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

Origin, composition and quality of suspended particulate organic matter in relation to freshwater inflow in a South Texas estuary

NASA Astrophysics Data System (ADS)

Lebreton, Benoit; Beseres Pollack, Jennifer; Blomberg, Brittany; Palmer, Terence A.; Adams, Leslie; Guillou, Gaël; Montagna, Paul A.

2016-03-01

South Texas has a semi-arid climate with a large interannual variability of freshwater inflows. This study sought to define how changes in freshwater inflow affect the composition, quantity and quality of suspended particulate organic matter (SPOM) in a South Texas estuary: the Mission-Aransas estuary. The study was implemented 1.5 months after a large rain event in September 2010 and continued for 10 months of drought conditions. The composition of SPOM originating from rivers, the Gulf of Mexico and the estuary were determined using stable isotopes (δ13C, δ15N and δ34S). The quantity and quality of SPOM were assessed using organic carbon content, chlorophyll a concentrations and C/chl a ratios. Our results demonstrated that autochthonous phytoplankton was the dominant component of SPOM in the Mission-Aransas estuary during droughts. Benthic organic matter from local primary producers (i.e., seagrass, salt marsh plants, benthic microalgae) did not influence SPOM composition, either as fresh material or as detritus. A comparison with a positive estuary (i.e., Sabine-Neches estuary, TX) indicates that decreases in freshwater inflow may lead to decreases of terrestrial organic matter inputs and to increase the ratio of autochtonous phytoplanktonic material in SPOM.

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

PubMed Central

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

2015-01-01

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

Defining the quality of soil organic matter

EPA Science Inventory

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

Diel fluctuations in natural organic matter quality in an oligotrophic cave system

NASA Astrophysics Data System (ADS)

Brown, T.; Engel, A. S.; Pfiffner, S. M.

2016-12-01

Transformations of natural organic matter (NOM) and effects of photochemical degradation on dissolved organic matter (DOM) quality in recharge can be readily studied in cave systems with hydrologic connections between the surface and subsurface. Specifically, diel controls on photodegradation, fresh NOM production, and microbial C cycling were examined from recharge to resurgence of an oligotrophic cave stream in Kentucky. We used NOM isolation and spectroscopic analysis to concentrate and characterize DOM, and lipid profiling to evaluate microbial community structure. A hydrophilic fraction of DOM was isolated from bulk waters in the field using diethylaminoethyl (DEAE) weak anion exchange column chromatography, and isolates were characterized with FTIR spectroscopy to identify differences in macromolecular structure between surface and subsurface (downstream) DOM. Lipids from colloidal NOM (retained on 0.2 µm filter) and stream sediments were extracted using a modified Bligh Dyer method, segregated into classes, and converted to fatty acid methyl esters (FAME) for quantification and identification by GC-MS. During a late summer, low flow, 24-hour sampling event, the quality of surface water DOM recharged at night was 40% richer in aliphatic esters, 30% richer in phenols and alkanes, and elevated in polysaccharides compared with DOM recharged during daylight. IR absorptivity in nocturnal DOM isolates was an order of magnitude lower in the cave stream, with recalcitrant DOM interpreted from bands of aliphatic esters, alkanes, and organo-silicates. Phospholipid fatty acid (PLFA) profiles indicated that the abundance of polyunsaturated PLFA associated with algae, fungi, and higher plants decreased along the flowpath. Cave microbes exhibited elevated trans:cis ratios relative to surface communities, and the ratio increased at night. This suggested that downstream microbial communities existed in a state of reduced activity without inputs of photosynthates at night.

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

PubMed

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

2015-10-01

As two major forest types in the subtropics, broadleaved evergreen and broadleaved deciduous forests have long interested ecologists. However, little is known about their belowground ecosystems despite their ecological importance in driving biogeochemical cycling. Here, we used Illumina MiSeq sequencing targeting 16S rRNA gene and a microarray named GeoChip targeting functional genes to analyse microbial communities in broadleaved evergreen and deciduous forest soils of Shennongjia Mountain of Central China, a region known as 'The Oriental Botanic Garden' for its extraordinarily rich biodiversity. We observed higher plant diversity and relatively richer nutrients in the broadleaved evergreen forest than the deciduous forest. In odds to our expectation that plant communities shaped soil microbial communities, we found that soil organic matter quantity and quality, but not plant community parameters, were the best predictors of microbial communities. Actinobacteria, a copiotrophic phylum, was more abundant in the broadleaved evergreen forest, while Verrucomicrobia, an oligotrophic phylum, was more abundant in the broadleaved deciduous forest. The density of the correlation network of microbial OTUs was higher in the broadleaved deciduous forest but its modularity was smaller, reflecting lower resistance to environment changes. In addition, keystone OTUs of the broadleaved deciduous forest were mainly oligotrophic. Microbial functional genes associated with recalcitrant carbon degradation were also more abundant in the broadleaved deciduous forests, resulting in low accumulation of organic matters. Collectively, these findings revealed the important role of soil organic matter in shaping microbial taxonomic and functional traits. © 2015 John Wiley & Sons Ltd.

soil organic matter fractionation

NASA Astrophysics Data System (ADS)

Osat, Maryam; Heidari, Ahmad

2010-05-01

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

Decomposition and organic matter quality in continental peatlands: The ghost of permafrost past

USGS Publications Warehouse

Turetsky, M.R.

2004-01-01

Permafrost patterning in boreal peatlands contributes to landscape heterogeneity, as peat plateaus, palsas, and localized permafrost mounds are interspersed among unfrozen bogs and fens. The degradation of localized permafrost in peatlands alters local topography, hydrology, thermal regimes, and plant communities, and creates unique peatland features called "internal lawns." I used laboratory incubations to quantify carbon dioxide (CO 2) production in peat formed under different permafrost regimes (with permafrost, without permafrost, melted permafrost), and explored the relationships among proximate organic matter fractions, nutrient concentrations, and decomposition. Peat within each feature (internal lawn, bog, permafrost mound) is more chemically similar than peat collected within the same province (Alberta, Saskatchewan) or within depth intervals (surface, deep). Internal lawn peat produces more CO2 than the other peatland types. Across peatland features, acid-insoluble material (AIM) and AIM/nitrogen are significant predictors of decomposition. However, within each peatland feature, soluble proximate fractions are better predictors of CO2 production. Permafrost stability in peatlands influences plant and soil environments, which control litter inputs, organic matter quality, and decomposition rates. Spatial patterns of permafrost, as well as ecosystem processes within various permafrost features, should be considered when assessing the fate of soil carbon in northern ecosystems. ?? 2004 Springer Science+Business Media, Inc.

Quality Matters[TM] Accessibility Survey: Institutional Practices and Policies for Online Courses

ERIC Educational Resources Information Center

Frey, Barbara A.; King, Denise K.

2011-01-01

Quality Matters (QM) is a professional organization that offers a faculty-centered, peer review process to certify the quality of online and blended courses. The purpose of this white paper is to share the results of a Quality Matters accessibility benchmarking study administered to 84 subscriber institutions. The primary goal of the survey was to…

Natural organic matter properties in Swedish agricultural streams

NASA Astrophysics Data System (ADS)

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

2017-04-01

The following paper shows natural organic matter (NOM) properties of stream water samples collected from 8 agricultural streams and 12 agricultural observational fields in Sweden. The catchments and observational fields cover a broad range of environmental (climate, soil type), land use and water quality (nutrient and concentrations, pH, alkalinity) characteristics. Stream water samples collected every two weeks within an ongoing Swedish Monitoring Programme for Agriculture have been analysed for total/dissolved organic carbon, absorbance and fluorescence spectroscopy. A number of quantitative and qualitative spectroscopic parameters was calculated to help to distinguish between terrestrially-derived, refractory organic material and autochthonous, labile material indicative of biogeochemical transformations of terrestrial NOM and recent biological production. The study provides insights into organic matter properties and carbon budgets in agricultural streams and improves understanding of how agricultural catchments transform natural and anthropogenic fluxes of organic matter and nutrients. The insights from the grab sampling are supported by high-frequency turbidity, fulvic-like and tryptophan-like fluorescence measurements with in situ optical sensor.

Advanced solid-state NMR spectroscopy of natural organic matter.

PubMed

Mao, Jingdong; Cao, Xiaoyan; Olk, Dan C; Chu, Wenying; Schmidt-Rohr, Klaus

2017-05-01

Solid-state NMR is essential for the characterization of natural organic matter (NOM) and is gaining importance in geosciences and environmental sciences. This review is intended to highlight advanced solid-state NMR techniques, especially a systematic approach to NOM characterization, and their applications to the study of NOM. We discuss some basics of how to acquire high-quality and quantitative solid-state 13 C NMR spectra, and address some common technical mistakes that lead to unreliable spectra of NOM. The identification of specific functional groups in NOM, primarily based on 13 C spectral-editing techniques, is described and the theoretical background of some recently-developed spectral-editing techniques is provided. Applications of solid-state NMR to investigating nitrogen (N) in NOM are described, focusing on limitations of the widely used 15 N CP/MAS experiment and the potential of improved advanced NMR techniques for characterizing N forms in NOM. Then techniques used for identifying proximities, heterogeneities and domains are reviewed, and some examples provided. In addition, NMR techniques for studying segmental dynamics in NOM are reviewed. We also briefly discuss applications of solid-state NMR to NOM from various sources, including soil organic matter, aquatic organic matter, organic matter in atmospheric particulate matter, carbonaceous meteoritic organic matter, and fossil fuels. Finally, examples of NMR-based structural models and an outlook are provided. Copyright © 2016 Elsevier B.V. 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.

Soil Organic Matter Quality of an Oxisol Affected by Plant Residues and Crop Sequence under No-Tillage

NASA Astrophysics Data System (ADS)

Cora, Jose; Marcelo, Adolfo

2013-04-01

Plant residues are considered the primarily resource for soil organic matter (SOM) formation and the amounts and properties of plant litter are important controlling factors for the SOM quality. We determined the amounts, quality and decomposition rate of plant residues and the effects of summer and winter crop sequences on soil organic C (TOC) content, both particulate organic C (POC) and mineral-associated organic C (MOC) pools and humic substances in a Brazilian Rhodic Eutrudox soil under a no-tillage system. The organic C analysis in specifics pools used in this study was effective and should be adopted in tropical climates to evaluate the soil quality and the sustainability of various cropping systems. Continuous growth of soybean (Glycine max L. Merrill) on summer provided higher contents of soil POC and continuous growth of maize (Zea mays L.) provided higher soil humic acid and MOC contents. Summer soybean-maize rotation provided the higher plant diversity, which likely improved the soil microbial activity and the soil organic C consumption. The winter sunn hemp (Crotalaria juncea L.), pigeon pea (Cajanus cajan (L.) Millsp), oilseed radish (Raphanus sativus L.) and pearl millet (Pennisetum americanum (L.) Leeke) enhanced the soil MOC, a finding that is attributable to the higher N content of the crop residue. Sunn hemp and pigeon pea provided the higher soil POC content. Sunn hemp showed better performance and positive effects on the SOM quality, making it a suitable winter crop choice for tropical conditions with a warm and dry winter.

Seasonal variation in the quality of dissolved and particulate organic matter exchanged between a salt marsh and its adjacent estuary

NASA Astrophysics Data System (ADS)

Osburn, Christopher L.; Mikan, Molly P.; Etheridge, J. Randall; Burchell, Michael R.; Birgand, François

2015-07-01

Fluorescence was used to examine the quality of dissolved and particulate organic matter (DOM and POM) exchanging between a tidal creek in a created salt marsh and its adjacent estuary in eastern North Carolina, USA. Samples from the creek were collected hourly over four tidal cycles in May, July, August, and October 2011. Absorbance and fluorescence of chromophoric DOM (CDOM) and of base-extracted POM (BEPOM) served as the tracers for organic matter quality while dissolved organic carbon (DOC) and base-extracted particulate organic carbon (BEPOC) were used to compute fluxes. Fluorescence was modeled using parallel factor analysis (PARAFAC) and principle components analysis (PCA) of the PARAFAC results. Of nine PARAFAC components (C) modeled, C3 represented recalcitrant DOM and C4 represented fresher soil-derived source DOM. Component 1 represented detrital POM, and C6 represented planktonic POM. Based on mass balance, recalcitrant DOC export was 86 g C m-2 yr-1 and labile DOC export was 49 g C m-2 yr-1; no planktonic DOC was exported. The marsh also exported 41 g C m-2 yr-1 of detrital terrestrial POC, which likely originated from lands adjacent to the North River estuary. Planktonic POC export from the marsh was 6 g C m-2 yr-1. Assuming the exported organic matter was oxidized to CO2 and scaled up to global salt marsh area, respiration of salt marsh DOC and POC transported to estuaries could amount to a global CO2 flux of 11 Tg C yr-1, roughly 4% of the recently estimated CO2 release for marshes and estuaries globally.

Dust inputs and bacteria influence dissolved organic matter in clear alpine lakes.

PubMed

Mladenov, N; Sommaruga, R; Morales-Baquero, R; Laurion, I; Camarero, L; Diéguez, M C; Camacho, A; Delgado, A; Torres, O; Chen, Z; Felip, M; Reche, I

2011-07-26

Remote lakes are usually unaffected by direct human influence, yet they receive inputs of atmospheric pollutants, dust, and other aerosols, both inorganic and organic. In remote, alpine lakes, these atmospheric inputs may influence the pool of dissolved organic matter, a critical constituent for the biogeochemical functioning of aquatic ecosystems. Here, to assess this influence, we evaluate factors related to aerosol deposition, climate, catchment properties, and microbial constituents in a global dataset of 86 alpine and polar lakes. We show significant latitudinal trends in dissolved organic matter quantity and quality, and uncover new evidence that this geographic pattern is influenced by dust deposition, flux of incident ultraviolet radiation, and bacterial processing. Our results suggest that changes in land use and climate that result in increasing dust flux, ultraviolet radiation, and air temperature may act to shift the optical quality of dissolved organic matter in clear, alpine lakes. © 2011 Macmillan Publishers Limited. All rights reserved.

Development and application of a soil organic matter-based soil quality index in mineralized terrane of the Western US

Treesearch

S. W. Blecker; L. L. Stillings; M. C. Amacher; J. A. Ippolito; N. M. DeCrappeo

2012-01-01

Soil quality indices provide a means of distilling large amounts of data into a single metric that evaluates the soil's ability to carry out key ecosystem functions. Primarily developed in agroecosytems, then forested ecosystems, an index using the relation between soil organic matter and other key soil properties in more semi-arid systems of the Western US...

Effect of different kinds of crop residues on aggregate-protected soil organic matter fractions.

NASA Astrophysics Data System (ADS)

Huisz, A.

2009-04-01

Organic matter content of soils determines many important soil properties, such as soil structure, fertility and water-management. To improve its fertility and quality, returning different kinds of organic matter to soil has a long historical tradition. Ameliorating of soil and enhancing its fertility by enhancing its carbon stock with organic matter incorporation (like farmyard manure, crop residues or green manure) are general practices, but the extent of the amelioration depends much on several factors such as quantity, quality of the used organic matters. Quality of soil organic matters is affected by their chemical build-up, which differs by their origin (i.e. plant species); and their decomposability is affected by particle-size, protection by soil aggregates and the extent of their association to mineral surfaces. In our paper we investigated the effect of three different kinds of organic matter incorporation on aggregate-protected organic matter fractions: (1) Maize stem (M), (2) Wheat straw (W), and (3) Maize stem & Wheat straw (MW). Our samples were originated from Keszthely, Western Hungary, where the texture of the investigated soil is Sandy loam, the type of soil is Eutric Cambisol (soil type FAO), or Alfisol (soil type USDA). SOM fractions might be isolated and measured by physical fractionation of soil (Cambardella and Elliott (1992), Jensen et al. (1992)). Firstly, microaggregates were separated according to their particle-size with physical fractionation (i.e. wet sieving) (Six et al. (2000a)). Each sample was pre-treated by capillary wetting and was sieved for 2 min in an analytic sieve shaker machine with the following aperture sizes: 2 mm, 250 μm, 53 μm. Therefore 4 fractions were resulted: (1) the >2000 μm large macro-, (2) the 250-2000 μm small macro-, (3) the 53-250 μm microaggregates, and (4) the

Urban infrastructure influences dissolved organic matter quality and bacterial metabolism in an urban stream network

EPA Science Inventory

Urban streams are degraded by a suite of factors, including burial beneath urban infrastructure (i.e., roads, parking lots) that eliminates light and reduces direct organic matter inputs to streams, with likely consequences for organic matter metabolism by microbes and carbon lim...

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.

Effect of catchment land use and soil type on the concentration, quality, and bacterial degradation of riverine dissolved organic matter.

PubMed

Autio, Iida; Soinne, Helena; Helin, Janne; Asmala, Eero; Hoikkala, Laura

2016-04-01

We studied the effects of catchment characteristics (soil type and land use) on the concentration and quality of dissolved organic matter (DOM) in river water and on the bacterial degradation of terrestrial DOM. The share of organic soil was the strongest predictor of high concentrations of dissolved organic carbon, nitrogen, and phosphorus (DOC, DON, and DOP, respectively), and was linked to DOM quality. Soil type was more important than land use in determining the concentration and quality of riverine DOM. On average, 5-9 % of the DOC and 45 % of the DON were degraded by the bacterial communities within 2-3 months. Simultaneously, the proportion of humic-like compounds in the DOM pool increased. Bioavailable DON accounted for approximately one-third of the total bioavailable dissolved nitrogen, and thus, terrestrial DON can markedly contribute to the coastal plankton dynamics and support the heterotrophic food web.

Long-term dynamics of organic matter and elements exported as coarse particulates from two Caribbean montane watersheds

Treesearch

T. Heartsill Scalley; F.N. Scatena; S. Moya; A.E. Lugo

2012-01-01

In heterotrophic streams the retention and export of coarse particulate organic matter and associated elements are fundamental biogeochemical processes that influence water quality, food webs and the structural complexity of forested headwater streams. Nevertheless, few studies have documented the quantity and quality of exported organic matter over multiple years and...

Variation of organic matter quantity and quality in streams at Critical Zone Observatory watersheds

USGS Publications Warehouse

Miller, Matthew P.; Boyer, Elizabeth W.; McKnight, Diane M.; Brown, Michael G.; Gabor, Rachel S.; Hunsaker, Carolyn T.; Iavorivska , Lidiia; Inamdar, Shreeram; Kaplan, Louis A.; Johnson, Dale W.; Lin, Henry; McDowell, William H.; Perdrial, Julia N.

2016-01-01

The quantity and chemical composition of dissolved organic matter (DOM) in surface waters influence ecosystem processes and anthropogenic use of freshwater. However, despite the importance of understanding spatial and temporal patterns in DOM, measures of DOM quality are not routinely included as part of large-scale ecosystem monitoring programs and variations in analytical procedures can introduce artifacts. In this study, we used consistent sampling and analytical methods to meet the objective of defining variability in DOM quantity and quality and other measures of water quality in streamflow issuing from small forested watersheds located within five Critical Zone Observatory sites representing contrasting environmental conditions. Results show distinct separations among sites as a function of water quality constituents. Relationships among rates of atmospheric deposition, water quality conditions, and stream DOM quantity and quality are consistent with the notion that areas with relatively high rates of atmospheric nitrogen and sulfur deposition and high concentrations of divalent cations result in selective transport of DOM derived from microbial sources, including in-stream microbial phototrophs. We suggest that the critical zone as a whole strongly influences the origin, composition, and fate of DOM in streams. This study highlights the value of consistent DOM characterization methods included as part of long-term monitoring programs for improving our understanding of interactions among ecosystem processes as controls on DOM biogeochemistry.

Land-based salmon aquacultures change the quality and bacterial degradation of riverine dissolved organic matter

PubMed Central

Kamjunke, Norbert; Nimptsch, Jorge; Harir, Mourad; Herzsprung, Peter; Schmitt-Kopplin, Philippe; Neu, Thomas R.; Graeber, Daniel; Osorio, Sebastian; Valenzuela, Jose; Carlos Reyes, Juan; Woelfl, Stefan; Hertkorn, Norbert

2017-01-01

Aquacultures are of great economic importance worldwide but pollute pristine headwater streams, lakes, and estuaries. However, there are no in-depth studies of the consequences of aquacultures on dissolved organic matter (DOM) composition and structure. We performed a detailed molecular level characterization of aquaculture DOM quality and its bacterial degradation using four salmon aquacultures in Chile. Fluorescence measurements, ultrahigh-resolution mass spectrometry, and nuclear magnetic resonance spectroscopy of the DOM revealed specific and extensive molecular alterations caused by aquacultures. Aquacultures released large quantities of readily bioavailable metabolites (primarily carbohydrates and peptides/proteins, and lipids), causing the organic matter downstream of all the investigated aquacultures to deviate strongly from the highly processed, polydisperse and molecularly heterogeneous DOM found in pristine rivers. However, the upstream individual catchment DOM signatures remained distinguishable at the downstream sites. The benthic algal biovolume decreased and the bacterial biovolume and production increased downstream of the aquacultures, shifting stream ecosystems to a more heterotrophic state and thus impairing the ecosystem health. The bacterial DOM degradation rates explain the attenuation of aquaculture DOM within the subsequent stream reaches. This knowledge may aid the development of improved waste processing facilities and may help to define emission thresholds to protect sensitive stream ecosystems. PMID:28256613

Land-based salmon aquacultures change the quality and bacterial degradation of riverine dissolved organic matter

NASA Astrophysics Data System (ADS)

Kamjunke, Norbert; Nimptsch, Jorge; Harir, Mourad; Herzsprung, Peter; Schmitt-Kopplin, Philippe; Neu, Thomas R.; Graeber, Daniel; Osorio, Sebastian; Valenzuela, Jose; Carlos Reyes, Juan; Woelfl, Stefan; Hertkorn, Norbert

2017-03-01

Aquacultures are of great economic importance worldwide but pollute pristine headwater streams, lakes, and estuaries. However, there are no in-depth studies of the consequences of aquacultures on dissolved organic matter (DOM) composition and structure. We performed a detailed molecular level characterization of aquaculture DOM quality and its bacterial degradation using four salmon aquacultures in Chile. Fluorescence measurements, ultrahigh-resolution mass spectrometry, and nuclear magnetic resonance spectroscopy of the DOM revealed specific and extensive molecular alterations caused by aquacultures. Aquacultures released large quantities of readily bioavailable metabolites (primarily carbohydrates and peptides/proteins, and lipids), causing the organic matter downstream of all the investigated aquacultures to deviate strongly from the highly processed, polydisperse and molecularly heterogeneous DOM found in pristine rivers. However, the upstream individual catchment DOM signatures remained distinguishable at the downstream sites. The benthic algal biovolume decreased and the bacterial biovolume and production increased downstream of the aquacultures, shifting stream ecosystems to a more heterotrophic state and thus impairing the ecosystem health. The bacterial DOM degradation rates explain the attenuation of aquaculture DOM within the subsequent stream reaches. This knowledge may aid the development of improved waste processing facilities and may help to define emission thresholds to protect sensitive stream ecosystems.

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.

Effects of quantity, quality, and contact time of dissolved organic matter on bioconcentration of benzo[a]pyrene in the nematode Caenorhabditis elegans

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

Haitzer, M.; Hoess, S.; Burnison, B.K.

1999-03-01

Quantity and quality of dissolved organic matter (DOM) and the time allowed for DOM to interact with organic contaminants can influence their bioavailability. The authors studied the effect of natural aquatic DOM that had been in contact with benzo[a]pyrene (B[a]P) for 1 to 12 d on the bioconcentration of B[a]P in the nematode Caenorhabditis elegans. Dissolved organic matter quality and quantity was varied by using DOM from three different sources, each in three different concentrations. A model, based on the assumption that only freely dissolved B[a]P is bioavailable, was employed to estimate biologically determined partition coefficients [K{sub p}(biol.)]. Expressing themore » data for each combination of DOM source and contact time in a single K{sub p} (biol.) value allowed a direct comparison of the effects of different DOM qualities and contact times. The results show that the effect of DOM from a specific source was dependent on DOM quantity, but they also observed a distinct effect of DOM quality (represented by different sampling locations) on the bioconcentration of B[a]P. Contact time had no significant influence for the effects of two DOM sources on the bioconcentration of B[a]P. However, the third DOM source was significantly more effective with increased contact time, leading to lower B[a]P bioconcentration in the nematodes.« less

Applications of Fluorescence Spectroscopy for dissolved organic matter characterization in wastewater treatment plants

NASA Astrophysics Data System (ADS)

Goffin, Angélique; Guérin, Sabrina; Rocher, Vincent; Varrault, Gilles

2016-04-01

Dissolved organic matter (DOM) influences wastewater treatment plants efficiency (WTTP): variations in its quality and quantity can induce a foaming phenomenon and a fouling event inside biofiltration processes. Moreover, in order to manage denitrification step (control and optimization of the nitrate recirculation), it is important to be able to estimate biodegradable organic matter quantity before biological treatment. But the current methods used to characterize organic matter quality, like biological oxygen demand are laborious, time consuming and sometimes not applicable to directly monitor organic matter in situ. In the context of MOCOPEE research program (www.mocopee.com), this study aims to assess the use of optical techniques, such as UV-Visible absorbance and more specifically fluorescence spectroscopy in order to monitor and to optimize process efficiency in WWTP. Fluorescence excitation-emission matrix (EEM) spectroscopy was employed to prospect the possibility of using this technology online and in real time to characterize dissolved organic matter in different effluents of the WWTP Seine Centre (240,000 m3/day) in Paris, France. 35 sewage water influent samples were collected on 10 days at different hours. Data treatment were performed by two methods: peak picking and parallel factor analysis (PARAFAC). An evolution of DOM quality (position of excitation - emission peaks) and quantity (intensity of fluorescence) was observed between the different treatment steps (influent, primary treatment, biological treatment, effluent). Correlations were found between fluorescence indicators and different water quality key parameters in the sewage influents. We developed different multivariate linear regression models in order to predict a variety of water quality parameters by fluorescence intensity at specific excitation-emission wavelengths. For example dissolved biological oxygen demand (r2=0,900; p<0,0001) and ammonium concentration (r2=0,898; p<0

Organic matter controls of iron incorporation in growing sea ice

NASA Astrophysics Data System (ADS)

Janssens, Julie; Meiners, Klaus M.; Townsend, Ashley T.; Lannuzel, Delphine

2018-03-01

This study presents the first laboratory-controlled sea-ice growth experiment conducted under trace metal clean conditions. The role played by organic matter, in the incorporation of iron (Fe) into sea ice was investigated by means of laboratory ice-growth experiments using a titanium cold-finger apparatus. Experiments were also conducted to understand the role of extracellular polymeric substances (EPS) in the enrichment of ammonium in sea ice. Sea ice was grown from several seawater solutions containing different quantities and qualities of particulate Fe (PFe), dissolved Fe (DFe) and organic matter. Sea ice and seawater were analyzed for particulate organic carbon and nitrogen, macro-nutrients, extracellular EPS, PFe and DFe, and particulate aluminium. The experiments showed that biogenic PFe is preferentially incorporated into sea ice compared to lithogenic PFe. Furthermore, sea ice grown from ultra-violet (UV) and non-UV treated seawaters exhibits contrasting incorporation rates of organic matter and Fe. Whereas the effects of UV-treatments were not always significant, we do find indications that the type or organic matter controls the enrichment of Fe in forming sea ice.. Specifically, we come to the conclusion that the incorporation of DFe is favored by the presence of organic ligands in the source solution.

Chromophoric Dissolved Organic Matter in Southwestern Greenland Lakes

NASA Astrophysics Data System (ADS)

Osburn, C. L.; Giles, M. E.; Underwood, G. J. C.

2014-12-01

Dissolved organic matter (DOM) is an important property of Arctic lake ecosystems, originating from allochthonous inputs from catchments and autochthonous production by plankton in the water column. Little is known about the quality of DOM in Arctic lakes that lack substantial inputs from catchments and such lakes are abundant in southwestern Greenland. Colored dissolved organic matter (CDOM), the fraction that absorbs ultraviolet (UV) and visible light, is the controlling factor for the optical properties of many surface waters and as well informs on the quality of DOM. We examined the quality of CDOM in 21 lakes in southwestern Greenland, from the ice sheet to the coast, as part of a larger study examining the role of DOM in regulating microbial communities in these lakes. DOM was size fractioned and absorbance and fluorescence was measured on each size fraction, as well as on bulk DOM. The specific ultraviolet absorbance (SUVA) at 254 nm (SUVA254), computed by normalizing absorption (a254) to dissolved organic carbon (DOC) concentration, provided an estimate of the aromatic carbon content of DOM. SUVA values were generally <2, indicating low aromatic content. Parallel factor analysis (PARAFAC) of CDOM fluorescence was used to determine the relative abundance of allochthonous and autochthonous DOM in all size fractions. Younger lakes near the ice sheet and lakes near the coast had lower amounts of CDOM and appeared more microbial in quality. However, lakes centrally located between the ice sheet and the coast had the highest CDOM concentrations and exhibited strong humic fluorescence. Overall distinct differences in CDOM quality were observed between lake locations and among DOM size fractions.

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.

Storage and export of organic matter in a headwater stream: responses to long-term detrital manipulations

Treesearch

Sue L. Eggert; J. Bruce Wallace; Judy L. Meyer; Jackson R. Webster

2012-01-01

Riparian habitats provide organic matter inputs that influence stream biota and ecosystem processes in forested watersheds. Over a 13-yr period, we examined the effects of litter exclusion, small- and large-wood removal, and the addition of leaf species of varying detrital quality on organic matter standing crop and export of organic and inorganic particles in a high-...

Northern Gulf of Mexico estuarine coloured dissolved organic matter derived from MODIS data

EPA Science Inventory

Coloured dissolved organic matter (CDOM) is relevant for water quality management and may become an important measure to complement future water quality assessment programmes. An approach to derive CDOM using the Moderate Resolution Imaging Spectroradiometer (MODIS) was developed...

The Effect of paper mill waste and sewage sludge amendments on soil organic matter

NASA Astrophysics Data System (ADS)

Méndez, Ana; Barriga, Sandra; Guerrero, Francisca; Gascó, Gabriel

2013-04-01

In general, Mediterranean soils have low organic matter content, due to the climate characteristics of this region and inadequate land management. Traditionally, organic wastes such as manure are used as amendment in order to improve the soil quality, increasing soil fertility by the accumulation of nitrogen, phosphorus and other plant nutrients in the soil. In the last decade, other anthropogenic organic wastes such as sewage sludge or paper waste materials have been studied as soil amendments to improve physical, chemical and biological properties of soils. The objective of the present work was to study the influence of waste from a paper mill and sewage sludge amendments on soil organic matter. For this reason, soil organic matter evolution was studied using thermogravimetric analysis (TGA), the derivative (dTG) and differential thermal analysis (DTA). Thermal analytical techniques have the advantage of using full samples without pre-treatments and have been extensively used to study the evolution of organic matter in soils, to evaluate composting process or to study the evolution of organic matter of growing media.

Stream Dissolved Organic Matter Quantity and Quality Along a Wetland-Cropland Catchment Gradient

NASA Astrophysics Data System (ADS)

McDonough, O.; Hosen, J. D.; Lang, M. W.; Oesterling, R.; Palmer, M.

2012-12-01

Wetlands may be critical sources of dissolved organic matter (DOM) to stream networks. Yet, more than half of wetlands in the continental United States have been lost since European settlement, with the majority of loss attributed to agriculture. The degree to which agricultural loss of wetlands impacts stream DOM is largely unknown and may have important ecological implications. Using twenty headwater catchments on the Delmarva Peninsula (Maryland, USA), we investigated the seasonal influence of wetland and cropland coverage on downstream DOM quantity and quality. In addition to quantifying bulk downstream dissolved organic carbon (DOC) concentration, we used a suite of DOM UV-absorbance metrics and parallel factor analysis (PARAFAC) modeling of excitation-emission fluorescence spectra (EEMs) to characterize DOM composition. Percent bioavailable DOC (%BDOC) was measured during the Spring sampling using a 28-day incubation. Percent wetland coverage and % cropland within the watersheds were significantly negatively correlated (r = -0.93, p < 0.001). Results show that % wetland coverage was positively correlated with stream DOM concentration, molecular weight, aromaticity, humic-like fluorescence, and allochthonous origin. Conversely, increased wetland coverage was negatively correlated with stream DOM protein-like fluorescence. Percent BDOC decreased with DOM humic-like fluorescence and increased with protein-like fluorescence. We observed minimal seasonal interaction between % wetland coverage and DOM concentration and composition across Spring, Fall, and Winter sampling seasons. However, principal component analysis suggested more pronounced seasonal differences exist in stream DOM. This study highlights the influence of wetlands on downstream DOM in agriculturally impacted landscapes where loss of wetlands to cultivation may significantly alter stream DOM quantity and quality.

NITROGEN DEPOSITION AND ORGANIC MATTER MANIPULATIONS AFFECT GROSS AND NET NITROGEN TRANSFORMATIONS IN TWO TEMPERATE FORESTS SOILS

EPA Science Inventory

Soil nitrogen transformations are intricately linked to carbon transformations. We utilized two existing organic matter manipulation sites in western Oregon, USA and Hungary to investigate these linkages. Our questions were: 1) Does the quantity and quality of organic matter af...

Seasonal Variation in the Quality of Dissolved and Particulate Organic Matter Exchanged Between a Salt Marsh and Its Adjacent Estuary

NASA Astrophysics Data System (ADS)

Osburn, C. L.; Mikan, M.; Etheridge, J. R.; Burchell, M. R.; Birgand, F.

2015-12-01

Salt marshes are transitional ecosystems between terrestrial and marine environments. Along with mangroves and other vegetated coastal habitats, salt marshes rank among the most productive ecosystems on Earth, with critical global importance for the planet's carbon cycle. Fluorescence was used to examine the quality of dissolved and particulate organic matter (DOM and POM) exchanging between a tidal creek in a created salt marsh and its adjacent estuary in eastern North Carolina, USA. Samples from the creek were collected hourly over four tidal cycles in May, July, August, and October of 2011. Absorbance and fluorescence of chromophoric DOM (CDOM) and of base-extracted POM (BEPOM) served as the tracers for organic matter quality while dissolved organic carbon (DOC) and base-extracted particulate organic carbon (BEPOC) were used to compute fluxes. Fluorescence was modeled using parallel factor analysis (PARAFAC) and principle components analysis (PCA) of the PARAFAC results. Of nine PARAFAC components modeled, we used multiple linear regression to identify tracers for recalcitrant DOM; labile soil-derived source DOM; detrital POM; and planktonic POM. Based on mass balance, recalcitrant DOC export was 86 g C m-2 yr-1 and labile DOC export was 49 g C m-2 yr-1. The marsh also exported 41 g C m-2 yr-1 of detrital terrestrial POC, which likely originated from lands adjacent to the North River estuary. Planktonic POC export from the marsh was 6 g C m-2 yr-1. Using the DOM and POM quality results obtained via fluorescence measurements and scaling up to global salt marsh area, we estimated that the potential release of CO2 from the respiration of salt marsh DOC and POC transported to estuaries could be 11 Tg C yr-1, roughly 4% of the recently estimated CO2 release for marshes and estuaries globally.

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.

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.

The dissolved organic matter as a potential soil quality indicator in arable soils of Hungary.

PubMed

Filep, Tibor; Draskovits, Eszter; Szabó, József; Koós, Sándor; László, Péter; Szalai, Zoltán

2015-07-01

Although several authors have suggested that the labile fraction of soils could be a potential soil quality indicator, the possibilities and limitations of using the dissolved organic matter (DOM) fraction for this purpose have not yet been investigated. The objective of this study was to evaluate the hypothesis that DOM is an adequate indicator of soil quality. To test this, the soil quality indices (SQI) of 190 arable soils from a Hungarian dataset were estimated, and these values were compared to DOM parameters (DOC and SUVA254). A clear difference in soil quality was found between the soil types, with low soil quality for arenosols (average SQI 0.5) and significantly higher values for gleysols, vertisols, regosols, solonetzes and chernozems. The SQI-DOC relationship could be described by non-linear regression, while a linear connection was observed between SQI and SUVA. The regression equations obtained for the dataset showed only one relatively weak significant correlation between the variables, for DOC (R (2) = 0.157(***); n = 190), while non-significant relationships were found for the DOC and SUVA254 values. However, an envelope curve operated with the datasets showed the robust potential of DOC to indicate soil quality changes, with a high R (2) value for the envelope curve regression equation. The limitations to using the DOM fraction of soils as a quality indicator are due to the contradictory processes which take place in soils in many cases.

Riverine transport of terrestrial organic matter to the North Catalan margin, NW Mediterranean Sea

NASA Astrophysics Data System (ADS)

Sanchez-Vidal, Anna; Higueras, Marina; Martí, Eugènia; Liquete, Camino; Calafat, Antoni; Kerhervé, Philippe; Canals, Miquel

2013-11-01

Rivers are the primary pathway for organic matter transport from the terrestrial to the marine environment and, thus, river fluxes are critical in regulating the quantity of terrestrial organic matter that reaches the coastal ecosystems. Hydrodynamic processes typical of the coastal zone can lead to the transport of terrestrial organic matter across the continental shelf and beyond. Such organic matter can eventually reach the deep margin and basin ecosystems. Riverine inputs of organic matter to the sea can be a significant food source to marine ecosystems contributing to carbon cycling in these ecosystems. In order to assess the marine carbon cycle it is essential to know the biogeochemical characteristics and temporal dynamics of the fluvial organic matter input discharged by rivers to the coastal zone. In this study we present a one and a half year long (November 2008 to May 2010) assessment on organic carbon (OC) and nitrogen (N) inputs from the three main rivers discharging into the North Catalan margin (Tordera, Ter and Fluvià, from south to north). Furthermore, we investigate the characteristics of the particulate organic matter discharged by these rivers by means of stable isotopic (δ13C and δ15N) and grain size analyses. We found that the hydrological regime of the rivers is a relevant factor in regulating the quantity and mediating the quality of organic matter inputs to the North Catalan margin. Overall, the three main rivers discharging into the study area deliver 1266 and 159 tonnes of terrestrial OC and N per year, respectively, to the coastal zone. Most of the OC and N load is transported during floods, which indicates that the Mediterranean climate of the area, with a strong seasonal contrast in precipitation, determines the timing of the main inputs of OC and N to the sea. Therefore, the annual OC and N load experiences a high temporal variability associated to the number and magnitude of floods with in each hydrological year. In addition, we

Benthic foraminiferal and organic matter compounds as proxies of environmental quality in a tropical coastal lagoon: The Itaipu lagoon (Brazil).

PubMed

Raposo, Débora; Clemente, Iara; Figueiredo, Marcos; Vilar, Amanda; Lorini, Maria Lucia; Frontalini, Fabrizio; Martins, Virgínia; Belart, Pierre; Fontana, Luiz; Habib, Renan; Laut, Lazaro

2018-04-01

Lagoons in the southeast coast of Brazil have experienced eutrophication due to the exponential increase of human population and sewage discharges. Living benthic foraminifera have demonstrated to be good bioindicators of such impacts. This study aims to evaluate the organic matter accumulation effects on the foraminiferal distribution in the Itaipu lagoon (Brazil). On the basis of the biotic and abiotic analyses, three sectors are identified. The Sector I, an inner area, is characterized by high dissolved oxygen values and foraminiferal species with preference for marine conditions, demonstrating the sea influence. The Sector II, in the mangrove margins, is associated to sandy sediment and biopolymers and mainly represented by euryhaline species. The Sector III is marked by low density or absence of living foraminifera and corresponds to a low quality organic matter enriched area (North, Southwest and Centre). Copyright © 2018 Elsevier Ltd. All rights reserved.

Interstellar organic matter in meteorites

NASA Technical Reports Server (NTRS)

Yang, J.; Epstein, S.

1983-01-01

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

Tracing sources of organic matter in adjacent urban streams having different degrees of channel modification.

PubMed

Duan, Shuiwang; Amon, Rainer M W; Brinkmeyer, Robin L

2014-07-01

Urbanization and stream-channel modifications affect organic matter concentrations and quality in streams, by altering allochthonous organic matter input and in-stream transformation. This study uses multiple tracers (δ(13)C, δ(15)N, C/N ratio, and chlorophyll-a) to track sources of organic matter in two highly urbanized bayous in Houston (Texas, USA). Wastewater treatment plants (WWTPs) are located in headwaters of both bayous and contribute more than 75% to water flow. Low isotopic relatedness to natural end-members and enriched δ(15)N values suggest the influence of WWTPs on the composition of all organic matter fractions. The two bayous differ in degree of channel improvement resulting in different responses to hydrological conditions. During high flow conditions, the influence of terrestrial organic matter and sediment resuspension was much more pronounced in the Buffalo Bayou than in the concrete-lined White Oak Bayou. Particulate organic matter (POM) in White Oak Bayou had similar values of enriched δ(15)N in all subsegments, whereas in Buffalo Bayou, the degree of δ(15)N enrichment was less in the subsegments of the lower watershed. The difference in riparian zone contributions and interactions with sediments/soils was likely responsible for the compositional differences between the two bayous. Phytoplankton inputs were significantly higher in the bayous, especially in slow-flowing sections, relative to the reference sites, and elevated phytoplankton inputs accounted for the observed stable C isotope differences between FPOM and high molecular weight dissolved organic matter (HMW DOM). Relative to POM, HMW DOM in the bayous was similar to WWTP effluents and showed minor longitudinal variability in both streams suggesting that WWTPs contribute much of the DOM in the systems. Urbanization has a major influence on organic matter sources and quality in these urban water bodies and these changes seem further enhanced by stream channel modifications

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

NASA Astrophysics Data System (ADS)

Mollenhauer, G.; Winterfeld, M.; Hefter, J.; Bodenstab, L.; Morgenstern, A.; Eulenburg, A.; Heim, B.; Koch, B.; Schefuss, E.; Moerth, C. M.; Rethemeyer, J.

2016-12-01

Arctic rivers are known to export large quantities of carbon by discharge of dissolved and particulate organic carbon (DOC, POC), and in a warming and progressively moister Arctic, these exports may increase resulting in a reduction of arctic continental carbon stocks. These rivers have highly variable discharge rates with a pronounced maximum during the spring freshet associated with highest concentrations of DOC and POC. Most studies investigating the isotopic composition and quality of carbon exported by Arctic rivers rely on samples taken in summer during base flow, which is due to the logistical challenges associated with sampling in the remote Arctic permafrost regions. Here we present a record of δ13C and Δ14C of DOC and POC collected between late May during the freshet and late August 2014 in the Lena River Delta. POC Δ14C shows an initial trend towards older values in the spring samples, which is reversed in summer, associated with a shift towards more depleted δ13C values. We interpret this aging trend as reflecting progressive thawing throughout the ice-free season, resulting in mobilization of progressively older carbon from deeper thawed layers. The summer reversal indicates admixture of aquatic organic matter. DOC Δ14C, in contrast, remains at relatively modern levels with rather constant δ13C values throughout the sampling period. We furthermore analysed the biomarker composition of Lena Delta particulate OM collected in spring and summer. From spring to summer, we observe trends in abundance of individual leaf-wax derived biomarkers indicating higher abundance of algal biomass in the summer particles. Trends in soil microbial biomarkers and compound-specific δD of leaf-wax lipids suggest a shift in sources towards higher contributions from the southern catchment in summer. DOC composition investigated with FT-ICR-MS changes from spring with higher abundances of compounds with high H/C and low O/C ratios to late summer, when fewer compounds

Effects of augmentation of coarse particulate organic matter on metabolism and nutrient retention in hyporheic sediments

Treesearch

C.L. Crenshaw; H.M. Valett; J.R. Webster

2002-01-01

1. Metabolic and biogeochemical processes in hyporheic zones may depend on inputs of coarse particulate organic matter. Our research focused on how differing quantity and quality of organic matter affects metabolism and nutrient retention in the hyporheic zone of a first-order Appalachian stream. 2. Sixteen plots were established on a tributary of Hugh White Creek, NC...

Seasonal changes of organic matter quality and quantity at the outlet of a forested karst system (La Roche Saint Alban, French Alps)

NASA Astrophysics Data System (ADS)

Tissier, Grégory; Perrette, Yves; Dzikowski, Marc; Poulenard, Jérome; Hobléa, Fabien; Malet, Emmanuel; Fanget, Bernard

2013-03-01

SummaryBecause of its impact on water quality, organic matter (OM) in karst groundwater has been widely studied. The present article describes a method for monitoring OM in karst aquifers characterized by quick responses to rainfall. This method combines weekly manual sampling and continuous monitoring to provide, qualitative and quantitative information about OM flow. Weekly samples were analyzed for Total Organic Carbon (TOC) content and spectrofluorescence, while continuous monitoring was carried out at the main spring, using a field fluorimeter (310/400-700 nm and 280/300-600 nm) to quantify chromophoric organic matter (COM). The type and quantity of COM were defined by decomposing Excitation Emission Matrices (EEMs) and by applying a 2D fluorescence decomposition method. Continuous monitoring data showed that the dominant COM was humic-like (HL). We found three types of relationship between HL and discharge and between HL and TOC, showing that caution must be exercised when using field fluorimeter measurements to quantify TOC. Each relationship was characterized by global differences in OM content and by the presence of different percentages of non-chromophoric organic matter. These three relationships are associated with changes in hydrology and microorganism activity during the year. We used these relationships to estimate the annual OM flow (about 15 kg/ha/year) and thereby quantify OM flow during the year. Our results show the importance of the non-chromophoric organic matter in such estimation. That work illustrates the need to couple qualitative and quantitative monitoring of OM in karst spring to improve the global comprehension of karst system and of the sources implies in the OM flow.

The Impact of Quality Matters Professional Development on Teaching across Delivery Formats

ERIC Educational Resources Information Center

Kearns, Lorna R.; Mancilla, Rae

2017-01-01

This study explored the impact of professional development workshops for online course design on faculty's pedagogical practices in online, face-to-face (f2f), and blended instructional modes. It specifically focused on trainings offered by the Quality Matters (QM) organization on a rubric for assessing quality in online course development. A…

The soil organic carbon content of anthropogenically altered organic soils effects the dissolved organic matter quality, but not the dissolved organic carbon concentrations

NASA Astrophysics Data System (ADS)

Frank, Stefan; Tiemeyer, Bärbel; Bechtold, Michel; Lücke, Andreas; Bol, Roland

2016-04-01

Dissolved organic carbon (DOC) is an important link between terrestrial and aquatic ecosystems. This is especially true for peatlands which usually show high concentrations of DOC due to the high stocks of soil organic carbon (SOC). Most previous studies found that DOC concentrations in the soil solution depend on the SOC content. Thus, one would expect low DOC concentrations in peatlands which have anthropogenically been altered by mixing with sand. Here, we want to show the effect of SOC and groundwater level on the quantity and quality of the dissolved organic matter (DOM). Three sampling sites were installed in a strongly disturbed bog. Two sites differ in SOC (Site A: 48%, Site B: 9%) but show the same mean annual groundwater level of 15 and 18 cm below ground, respectively. The SOC content of site C (11%) is similar to Site B, but the groundwater level is much lower (-31 cm) than at the other two sites. All sites have a similar depth of the organic horizon (30 cm) and the same land-use (low-intensity sheep grazing). Over two years, the soil solution was sampled bi-weekly in three depths (15, 30 and 60 cm) and three replicates. All samples were analyzed for DOC and selected samples for dissolved organic nitrogen (DON) and delta-13C and delta-15N. Despite differences in SOC and groundwater level, DOC concentrations did not differ significantly (A: 192 ± 62 mg/L, B: 163 ± 55 mg/L and C: 191 ± 97 mg/L). At all sites, DOC concentrations exceed typical values for peatlands by far and emphasize the relevance even of strongly disturbed organic soils for DOC losses. Individual DOC concentrations were controlled by the temperature and the groundwater level over the preceding weeks. Differences in DOM quality were clearer. At site B with a low SOC content, the DOC:DON ratio of the soil solution equals the soil's C:N ratio, but the DOC:DON ratio is much higher than the C:N ratio at site A. In all cases, the DOC:DON ratio strongly correlates with delta-13C. There is no

Mapping Soil Organic Matter with Hyperspectral Imaging

NASA Astrophysics Data System (ADS)

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

2014-05-01

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

Additives aided composting of green waste: effects on organic matter degradation, compost maturity, and quality of the finished compost.

PubMed

Gabhane, Jagdish; William, S P M Prince; Bidyadhar, Rajnikant; Bhilawe, Priya; Anand, Duraisamy; Vaidya, Atul N; Wate, Satish R

2012-06-01

The effect of various additives such as fly ash, phosphogypsum, jaggery, lime, and polyethylene glycol on green waste composting was investigated through assessing their influence on microbial growth, enzymatic activities, organic matter degradation, bulk density, quality of finished compost including gradation test, heavy metal analysis, etc. A perusal of results showed that addition of jaggery and polyethylene glycol were helpful to facilitate composting process as they significantly influenced the growth of microbes and cellulase activity. The quality of finished compost prepared from jaggery and polyethylene glycol added treatments were superior to other composts, wherein reduction in C/N ratio was more than 8% in jaggery treatment. All other parameters of compost quality including gradation test also favored jaggery and polyethylene glycol as the best additives for green waste composting. Copyright © 2012 Elsevier Ltd. All rights reserved.

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

INTERLABORATORY COMPARISON STUDIES FOR CHARACTERIZATION OF ORGANIC COMPOUNDS IN PARTICULATE MATTER

EPA Science Inventory

A working group of investigators, who are characterizing and quantifying the organic compounds in particulate matter (PM) as part of the US EPA's PM 2.5 research program and related studies, was established three years ago to advance the quality and comparability of data on the...

Analysis of the effects of natural organic matter in zinc beneficiation

USDA-ARS?s Scientific Manuscript database

In this study, we present the analysis of the effects of Natural Organic Matter (NOM) in zinc beneficiation from abandoned mine tailings using bioleaching technologies. We used standardized Suwannee River Humic Acid (SRHA) as the NOM source to analyze the importance of the quality of the process wat...

Absorption and fluorescence properties of chromophoric dissolved organic matter: implications for the monitoring of water quality in a large subtropical reservoir.

PubMed

Liu, Xiaohan; Zhang, Yunlin; Shi, Kun; Zhu, Guangwei; Xu, Hai; Zhu, Mengyuan

2014-12-01

The development of techniques for real-time monitoring of water quality is of great importance for effectively managing inland water resources. In this study, we first analyzed the absorption and fluorescence properties in a large subtropical reservoir and then used a chromophoric dissolved organic matter (CDOM) fluorescence monitoring sensor to predict several water quality parameters including the total nitrogen (TN), total phosphorus (TP), chemical oxygen demand (COD), dissolved organic carbon (DOC), and CDOM fluorescence parallel factor analysis (PARAFAC) components in the reservoir. The CDOM absorption coefficient at 254 nm (a(254)), the humic-like component (C1), and the tryptophan-like component (C3) decreased significantly along a gradient from the northwest to the lake center, northeast, southwest, and southeast region in the reservoir. However, no significant spatial difference was found for the tyrosine-like component (C2), which contributed only four marked peaks. A highly significant linear correlation was found between the a(254) and CDOM concentration measured using the CDOM fluorescence sensor (r(2) = 0.865, n = 76, p < 0.001), indicating that CDOM concentrations could act as a proxy for the CDOM absorption coefficient measured in the laboratory. Significant correlations were also found between the CDOM concentration and TN, TP, COD, DOC, and the maximum fluorescence intensity of C1, suggesting that the real-time monitoring of CDOM concentrations could be used to predict these water quality parameters and trace the humic-like fluorescence substance in clear aquatic ecosystems with DOC <2 mg/L and total suspended matter (TSM) concentrations <15 mg/L. These results demonstrate that the CDOM fluorescence sensor is a useful tool for on-line water quality monitoring if the empirical relationship between the CDOM concentration measured using the CDOM fluorescence sensor and the water quality parameters is calibrated and validated.

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.

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

USGS Publications Warehouse

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

2015-01-01

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

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

PubMed

Smernik, Ronald J; Kookana, Rai S

2015-01-01

Sorption of non-ionic organic compounds to soil is usually expressed as the carbon-normalized partition coefficient (KOC), because it is assumed that the main factor that influences the amount sorbed is the organic carbon content of the soil. However, KOC can vary by a factor of at least ten across a range of soils. We investigated two potential causes of variation in diuron KOC - organic matter-mineral interactions and organic matter chemistry - for a diverse set of 34 soils from Sri Lanka, representing a wide range of soil types. Treatment with hydrofluoric acid (HF-treatment) was used to concentrate soil organic matter. HF-treatment increased KOC for the majority of soils (average factor 2.4). We attribute this increase to the blocking of organic matter sorption sites in the whole soils by minerals. There was no significant correlation between KOC for the whole soils and KOC for the HF-treated soils, indicating that the importance of organic matter-mineral interactions varied greatly amongst these soils. There was as much variation in KOC across the HF-treated soils as there was across the whole soils, indicating that the nature of soil organic matter is also an important contributor to KOC variability. Organic matter chemistry, determined by solid-state (13)C nuclear magnetic resonance (NMR) spectroscopy, was correlated with KOC for the HF-treated soils. In particular, KOC increased with the aromatic C content (R=0.64, p=1×10(-6)), and decreased with O-alkyl C (R=-0.32, p=0.03) and alkyl C (R=-0.41, p=0.004) content. Copyright © 2014 Elsevier Ltd. All rights reserved.

Sea cucumbers reduce chromophoric dissolved organic matter in aquaculture tanks.

PubMed

Sadeghi-Nassaj, Seyed Mohammad; Catalá, Teresa S; Álvarez, Pedro A; Reche, Isabel

2018-01-01

Mono-specific aquaculture effluents contain high concentrations of nutrients and organic matter, which affect negatively the water quality of the recipient ecosystems. A fundamental feature of water quality is its transparency. The fraction of dissolved organic matter that absorbs light is named chromophoric dissolved organic matter (CDOM). A sustainable alternative to mono-specific aquaculture is the multitrophic aquaculture that includes species trophically complementary named "extractive" species that uptake the waste byproducts. Sea cucumbers are recognized as efficient extractive species due to the consumption of particulate organic matter (POM). However, the effects of sea cucumbers on CDOM are still unknown. During more than one year, we monitored CDOM in two big-volume tanks with different trophic structure. One of the tanks (-holothurian) only contained around 810 individuals of Anemonia sulcata , whereas the other tank (+holothurian) also included 90 individuals of Holothuria tubulosa and Holothuria forskali . We routinely analyzed CDOM absorption spectra and determined quantitative (absorption coefficients at 325 nm) and qualitative (spectral slopes) optical parameters in the inlet waters, within the tanks, and in their corresponding effluents. To confirm the time-series results, we also performed three experiments. Each experiment consisted of two treatments: +holothurians (+H) and -holothurians (-H). We set up three +H tanks with 80 individuals of A. sulcata and 10 individuals of H. tubulosa in each tank and four -H tanks that contained only 80 individuals of A. sulcata . In the time-series, absorption coefficients at 325 nm ( a 325 ) and spectral slopes from 275 to 295 nm ( S 275-295 ) were significantly lower in the effluent of the +holothurian tank (average: 0.33 m -1 and 16 µm -1 , respectively) than in the effluent of the -holothurian tank (average: 0.69 m -1 and 34 µm -1 , respectively), the former being similar to those found in the inlet

Molybdenum isotope fractionation during adsorption to organic matter

USGS Publications Warehouse

King, Elizabeth K.; Perakis, Steven; Pett-Ridge, Julie C.

2018-01-01

Organic matter is of emerging interest as a control on molybdenum (Mo) biogeochemistry, and information on isotope fractionation during adsorption to organic matter can improve interpretations of Mo isotope variations in natural settings. Molybdenum isotope fractionation was investigated during adsorption onto insolubilized humic acid (IHA), a surrogate for organic matter, as a function of time (2–170 h) and pH (2–7). For the time series experiment performed at pH 4.2, the average Mo isotope fractionation between the solution and the IHA (Δ98Mosolution-IHA) was 1.39‰ (± 0.16‰, 2σ, based on 98Mo/95Mo relative to the NIST 3134 standard) at steady state. For the pH series experiment, Mo adsorption decreased as pH increased from 2.0 to 6.9, and the Δ98Mosolution-IHA increased from 0.82‰ to 1.79‰. We also evaluated natural Mo isotope patterns in precipitation, foliage, organic horizon, surface mineral soil, and bedrock from 12 forested sites in the Oregon Coast Range. The average Mo isotope offset observed between precipitation and organic (O) horizon soil was 2.1‰, with light Mo isotopes adsorbing preferentially to organic matter. Fractionation during adsorption to organic matter is similar in magnitude and direction to prior observations of Mo fractionation during adsorption to Fe- and Mn- (oxyhydr)oxides. Our finding that organic matter influences Mo isotope composition has important implications for the role of organic matter as a driver of trace metal retention and isotopic fractionation.

Molybdenum isotope fractionation during adsorption to organic matter

NASA Astrophysics Data System (ADS)

King, E. K.; Perakis, S. S.; Pett-Ridge, J. C.

2018-02-01

Organic matter is of emerging interest as a control on molybdenum (Mo) biogeochemistry, and information on isotope fractionation during adsorption to organic matter can improve interpretations of Mo isotope variations in natural settings. Molybdenum isotope fractionation was investigated during adsorption onto insolubilized humic acid (IHA), a surrogate for organic matter, as a function of time (2-170 h) and pH (2-7). For the time series experiment performed at pH 4.2, the average Mo isotope fractionation between the solution and the IHA (Δ98Mosolution-IHA) was 1.39‰ (±0.16‰, 2σ, based on 98Mo/95Mo relative to the NIST 3134 standard) at steady state. For the pH series experiment, Mo adsorption decreased as pH increased from 2.0 to 6.9, and the Δ98Mosolution-IHA increased from 0.82‰ to 1.79‰. We also evaluated natural Mo isotope patterns in precipitation, foliage, organic horizon, surface mineral soil, and bedrock from 12 forested sites in the Oregon Coast Range. The average Mo isotope offset observed between precipitation and organic (O) horizon soil was 2.1‰, with light Mo isotopes adsorbing preferentially to organic matter. Fractionation during adsorption to organic matter is similar in magnitude and direction to prior observations of Mo fractionation during adsorption to Fe- and Mn- (oxyhydr)oxides. Our finding that organic matter influences Mo isotope composition has important implications for the role of organic matter as a driver of trace metal retention and isotopic fractionation.

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

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.

The role of Juncus effusus litter quality and nutrient availability on organic matter decomposition in restored cutover bogs

NASA Astrophysics Data System (ADS)

Agethen, Svenja; Knorr, Klaus-Holger

2017-04-01

More than 90% of peatlands in Europe are degraded by drainage and subsequent land use. However, beneficial effects of functioning peatlands, most of all carbon storage, have long been recognized but remain difficult to recover. Fragmentation and a surrounding of intensively used agricultural catchments with excess nutrients in air and waters further affects the recovery of sites. Under such conditions, highly competitive species such as Juncus effusus colonize restored peatlands instead of peat forming Sphagnum. While the specific stoichiometry and chemical composition makes Sphagnum litter recalcitrant in decomposition and hence, effective in carbon sequestration, we know little about dynamics involving Juncus, although this species provides organic matter in high quantity and of rather labile quality. To better understand decomposition in context of litter quality and nutrient availability, we incubated different peat types for 70 days; I) recent, II) weakly degraded fossil, and III) earthyfied nutrient rich fossil peat, amended with two 13C pulse-labelled Juncus litter types (excessively fertilized "F", and nutrient poor "NF" plants grown for three years watered with MilliQ only), respectively. We determined anaerobic decomposition rates, compared potential rates extrapolated from pure materials with measured rates of the mixtures, and tracked the 13C in the solid, liquid, and gaseous phase. To characterize the biogeochemical conditions, inorganic and organic electron acceptors, hydrogen and organic acids, and total enzyme activity were monitored. For characterization of dissolved organic matter we used UV-Vis and fluorescence spectroscopy (parallel factor analysis), and for solid organic matter elemental analysis and FTIR spectroscopy. There were two main structural differences between litter types: "F" litter and its leachates contained more proteinaceous components, the C/N ratio was 20 in contrast to 60 of the "NF" litter. However, humic components and

Spectral mapping of soil organic matter

NASA Technical Reports Server (NTRS)

Kristof, S. J.; Baumgardner, M. F.; Johannsen, C. J.

1974-01-01

Multispectral remote sensing data were examined for use in the mapping of soil organic matter content. Computer-implemented pattern recognition techniques were used to analyze data collected in May 1969 and May 1970 by an airborne multispectral scanner over a 40-km flightline. Two fields within the flightline were selected for intensive study. Approximately 400 surface soil samples from these fields were obtained for organic matter analysis. The analytical data were used as training sets for computer-implemented analysis of the spectral data. It was found that within the geographical limitations included in this study, multispectral data and automatic data processing techniques could be used very effectively to delineate and map surface soils areas containing different levels of soil organic matter.

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...

Dissolved organic matter in the Florida everglades: Implications for ecosystem restoration

USGS Publications Warehouse

Aiken, G.R.; Gilmour, C.C.; Krabbenhoft, D.P.; Orem, W.

2011-01-01

Dissolved organic matter (DOM) in the Florida Everglades controls a number of environmental processes important for ecosystem function including the absorption of light, mineral dissolution/precipitation, transport of hydrophobic compounds (e.g., pesticides), and the transport and reactivity of metals, such as mercury. Proposed attempts to return the Everglades to more natural flow conditions will result in changes to the present transport of DOM from the Everglades Agricultural Area and the northern conservation areas to Florida Bay. In part, the restoration plan calls for increasing water flow throughout the Everglades by removing some of the manmade barriers to flow in place today. The land- and water-use practices associated with the plan will likely result in changes in the quality, quantity, and reactivity of DOM throughout the greater Everglades ecosystem. The authors discuss the factors controlling DOM concentrations and chemistry, present distribution of DOM throughout the Everglades, the potential effects of DOM on key water-quality issues, and the potential utility of dissolved organic matter as an indicator of success of restoration efforts. Copyright ?? 2011 Taylor & Francis Group, LLC.

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.

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

REFERENCE MATERIALS AND QUALITY ASSURANCE FOR THE CHARACTERIZATION OF ORGANIC COMPOUNDS IN PARTICULATE MATTER

EPA Science Inventory

One of the first environmental matrix Standard Reference Materials (SRMs) developed by the National Institute of Standards and Technology (NIST) for determination of organic species was SRM 1649 Urban Dust, ambient total suspended particulate matter (PM) collected in Washington D...

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

EPA Science Inventory

Organic molecular markers were measured in airborne particulate matter (PM₁₀) from the City of Philadelphia North Broad Street air quality monitoring site to identify the seasonal abundances of key tracer compounds together with their dominant sources. Daily PM_10...

Biologically Active Organic Matter in Soils of European Russia

NASA Astrophysics Data System (ADS)

Semenov, V. M.; Kogut, B. M.; Zinyakova, N. B.; Masyutenko, N. P.; Malyukova, L. S.; Lebedeva, T. N.; Tulina, A. S.

2018-04-01

Experimental and literature data on the contents and stocks of active organic matter in 200 soil samples from the forest-tundra, southern-taiga, deciduous-forest, forest-steppe, dry-steppe, semidesert, and subtropical zones have been generalized. Natural lands, agrocenoses, treatments of long-term field experiments (bare fallow, unfertilized and fertilized crop rotations, perennial plantations), and different layers of soil profile are presented. Sphagnum peat and humus-peat soil in the tundra and forest-tundra zones are characterized by a very high content of active organic matter (300-600 mg C/100 g). Among the zonal soils, the content of active organic matter increases from the medium (75-150 mg C/100 g) to the high (150-300 mg C/100 g) level when going from soddy-podzolic soil to gray forest and dark-gray forest soils and then to leached chernozem. In the series from typical chernozem to ordinary and southern chernozem and chestnut and brown semidesert soils, a decrease in the content of active organic matter to the low (35-75 mg C/100 g) and very low (<35 mg C/100 g) levels is observed. Acid brown forest soil in the subtropical zone is characterized by a medium supply with active organic matter. Most arable soils are mainly characterized by low or very low contents of active organic matter. In the upper layers of soils, active organic matter makes up 1.2-11.1% of total Corg. The profile distribution of active organic matter in the studied soils coincides with that of Corg: their contents appreciably decrease with depth, except for brown semidesert soil. The stocks of active organic matter vary from 0.4 to 5.4 t/ha in the layer of 0-20 cm and from 1.0 to 12.4/ha in the layer of 0-50 cm of different soil types.

Sea cucumbers reduce chromophoric dissolved organic matter in aquaculture tanks

PubMed Central

Sadeghi-Nassaj, Seyed Mohammad; Catalá, Teresa S.; Álvarez, Pedro A.

2018-01-01

Background Mono-specific aquaculture effluents contain high concentrations of nutrients and organic matter, which affect negatively the water quality of the recipient ecosystems. A fundamental feature of water quality is its transparency. The fraction of dissolved organic matter that absorbs light is named chromophoric dissolved organic matter (CDOM). A sustainable alternative to mono-specific aquaculture is the multitrophic aquaculture that includes species trophically complementary named “extractive” species that uptake the waste byproducts. Sea cucumbers are recognized as efficient extractive species due to the consumption of particulate organic matter (POM). However, the effects of sea cucumbers on CDOM are still unknown. Methods During more than one year, we monitored CDOM in two big-volume tanks with different trophic structure. One of the tanks (−holothurian) only contained around 810 individuals of Anemonia sulcata, whereas the other tank (+holothurian) also included 90 individuals of Holothuria tubulosa and Holothuria forskali. We routinely analyzed CDOM absorption spectra and determined quantitative (absorption coefficients at 325 nm) and qualitative (spectral slopes) optical parameters in the inlet waters, within the tanks, and in their corresponding effluents. To confirm the time-series results, we also performed three experiments. Each experiment consisted of two treatments: +holothurians (+H) and –holothurians (−H). We set up three +H tanks with 80 individuals of A. sulcata and 10 individuals of H. tubulosa in each tank and four –H tanks that contained only 80 individuals of A. sulcata. Results In the time-series, absorption coefficients at 325 nm (a325) and spectral slopes from 275 to 295 nm (S275−295) were significantly lower in the effluent of the +holothurian tank (average: 0.33 m−1 and 16 µm−1, respectively) than in the effluent of the −holothurian tank (average: 0.69 m−1 and 34 µm−1, respectively), the former being

The use of amino acid indices for assessing organic matter quality and microbial abundance in deep-sea Antarctic sediments of IODP Expedition 318

USGS Publications Warehouse

Carr, Stephanie A; Mills, Christopher T.; Mandernack, Kevin W

2016-01-01

The Adélie Basin, located offshore of the Wilkes Land margin, experiences unusually high sedimentation rates (~ 2 cm yr− 1) for the Antarctic coast. This study sought to compare depthwise changes in organic matter (OM) quantity and quality with changes in microbial biomass with depth at this high-deposition site and an offshore continental margin site. Sediments from both sites were collected during the International Ocean Drilling (IODP) Program Expedition 318. Viable microbial biomass was estimated from concentrations of bacterial-derived phospholipid fatty acids, while OM quality was assessed using four different amino acid degradation proxies. Concentrations of total hydrolysable amino acids (THAA) measured from the continental margin suggest an oligotrophic environment, with THAA concentrations representing only 2% of total organic carbon with relative proportions of non-protein amino acids β-alanine and γ-aminobutyric acid as high as 40%. In contrast, THAA concentrations from the near-shore Adélie Basin represent 40%–60% of total organic carbon. Concentrations of β-alanine and γ-aminobutyric acid were often below the detection limit and suggest that the OM of the basin as labile. DI values in surface sediments at the Adélie and margin sites were measured to be + 0.78 and − 0.76, reflecting labile and more recalcitrant OM, respectively. Greater DI values in deeper and more anoxic portions of both cores correlated positively with increased relative concentrations of phenylalanine plus tyrosine and may represent a change of redox conditions, rather than OM quality. This suggests that DI values calculated along chemical profiles should be interpreted with caution. THAA concentrations, the percentage of organic carbon (CAA%) and total nitrogen (NAA%) represented by amino acids at both sites demonstrated a significant positive correlation with bacterial abundance estimates. These data suggest that the selective degradation of amino acids, as

Dissolved organic carbon and chromophoric dissolved organic matter properties of rivers in the USA

NASA Astrophysics Data System (ADS)

Spencer, Robert G. M.; Butler, Kenna D.; Aiken, George R.

2012-09-01

Dissolved organic carbon (DOC) concentration and chromophoric dissolved organic matter (CDOM) parameters were measured over a range of discharge in 30 U.S. rivers, covering a diverse assortment of fluvial ecosystems in terms of watershed size and landscape drained. Relationships between CDOM absorption at a range of wavelengths (a254, a350, a440) and DOC in the 30 watersheds were found to correlate strongly and positively for the majority of U.S. rivers. However, four rivers (Colorado, Colombia, Rio Grande and St. Lawrence) exhibited statistically weak relationships between CDOM absorption and DOC. These four rivers are atypical, as they either drain from the Great Lakes or experience significant impoundment of water within their watersheds, and they exhibited values for dissolved organic matter (DOM) parameters indicative of autochthonous or anthropogenic sources or photochemically degraded allochthonous DOM and thus a decoupling between CDOM and DOC. CDOM quality parameters in the 30 rivers were found to be strongly correlated to DOM compositional metrics derived via XAD fractionation, highlighting the potential for examining DOM biochemical quality from CDOM measurements. This study establishes the ability to derive DOC concentration from CDOM absorption for the majority of U.S. rivers, describes characteristics of riverine systems where such an approach is not valid, and emphasizes the possibility of examining DOM composition and thus biogeochemical function via CDOM parameters. Therefore, the usefulness of CDOM measurements, both laboratory-based analyses and in situ instrumentation, for improving spatial and temporal resolution of DOC fluxes and DOM dynamics in future studies is considerable in a range of biogeochemical studies.

Dissolved organic carbon and chromophoric dissolved organic matter properties of rivers in the USA

USGS Publications Warehouse

Spencer, Robert G.M.; Butler, Kenna D.; Aiken, George R.

2012-01-01

Dissolved organic carbon (DOC) concentration and chromophoric dissolved organic matter (CDOM) parameters were measured over a range of discharge in 30 U.S. rivers, covering a diverse assortment of fluvial ecosystems in terms of watershed size and landscape drained. Relationships between CDOM absorption at a range of wavelengths (a254, a350, a440) and DOC in the 30 watersheds were found to correlate strongly and positively for the majority of U.S. rivers. However, four rivers (Colorado, Colombia, Rio Grande and St. Lawrence) exhibited statistically weak relationships between CDOM absorption and DOC. These four rivers are atypical, as they either drain from the Great Lakes or experience significant impoundment of water within their watersheds, and they exhibited values for dissolved organic matter (DOM) parameters indicative of autochthonous or anthropogenic sources or photochemically degraded allochthonous DOM and thus a decoupling between CDOM and DOC. CDOM quality parameters in the 30 rivers were found to be strongly correlated to DOM compositional metrics derived via XAD fractionation, highlighting the potential for examining DOM biochemical quality from CDOM measurements. This study establishes the ability to derive DOC concentration from CDOM absorption for the majority of U.S. rivers, describes characteristics of riverine systems where such an approach is not valid, and emphasizes the possibility of examining DOM composition and thus biogeochemical function via CDOM parameters. Therefore, the usefulness of CDOM measurements, both laboratory-based analyses and in situ instrumentation, for improving spatial and temporal resolution of DOC fluxes and DOM dynamics in future studies is considerable in a range of biogeochemical studies.

Characterization of chromophoric dissolved organic matter and relationships among PARAFAC components and water quality parameters in Heilongjiang, China.

PubMed

Cui, Hongyang; Shi, Jianhong; Qiu, Linlin; Zhao, Yue; Wei, Zimin; Wang, Xinglei; Jia, Liming; Li, Jiming

2016-05-01

Chromophoric dissolved organic matter (CDOM) is an important optically active substance that can transports nutrients and pollutants from terrestrial to aquatic systems. Additionally, it is used as a measure of water quality. To investigate the source and composition of CDOM, we used chemical and fluorescent analyses to characterize CDOM in Heilongjiang. The composition of CDOM can be investigated by excitation-emission matrix (EEM) fluorescence and parallel factor analysis (PARAFAC). PARAFAC identified four individual components that were attributed to microbial humic-like (C1) and terrestrial humic-like (C2-4) in water samples collected from the Heilongjiang River. The relationships between the maximum fluorescence intensities of the four PARAFAC components and the water quality parameters indicate that the dynamic of the four components is related to nutrients in the Heilongjiang River. The relationships between the fluorescence component C3 and the biochemical oxygen demand (BOD5) indicates that component C3 makes a great contribution to BOD5 and it can be used as a carbon source for microbes in the Heilongjiang River. Furthermore, the relationships between component C3, the particulate organic carbon (POC), and the chemical oxygen demand (CODMn) show that component C3 and POC make great contributions to BOD5 and CODMn. The use of these indexes along with PARAFAC results would be of help to characterize the co-variation between the CDOM and water quality parameters in the Heilongjiang River.

Burning transformations: Fire history effects on organic matter processing from hillslopes to streams

NASA Astrophysics Data System (ADS)

Barnes, R. T.; Gilbertson, A.; Maxwell, K.

2017-12-01

Disturbance strongly regulates material and energy flows, changing ecosystem pattern and process. An increase in the size and severity of fire, particularly in the Intermountain West, over the last several decades is expected to continue due to a warming climate. Predicting how fire will alter the net ecosystem carbon balance requires us to understand how carbon is stored, processed, and transferred. Here we present results from paired watersheds focused on five 2002 severe fires in Colorado to examine how organic matter is processed along the hillslope and within the stream. Comparing soil samples and water extractable organic matter (WEOM) between burned and unburned sites illustrates the impact of fire: burned soils have 50% organic matter (OM) content as unburned soils, regardless of geomorphic position. While a smaller pool, soil OM (SOM) in burned sites is more susceptible to microbial degradation (p<0.001 for 4 of 6 sites), especially in systems with slower vegetative recovery. This is explained, in part, to the water extractable organic matter (WEOM) from unburned soils having a higher C:N than burned sites (p<0.02). This shift in SOM quality is likely due to differing OM inputs (e.g. grasses and forbes vs. trees in burned vs. unburned sites). Comparing results from intact soil column experiments to soil extractions and stream samples, suggests that the majority of this soil derived WEOM does not make it to the stream, potentially getting sorbed deeper in the mineral rich, organic poor, portion of the soil. Interestingly, the systematic shifts in OM amounts and quality (as measured by SUVA, E2:E3, and fluorescence) within the terrestrial system in response to fire, are not seen in stream exports. As such, while there are significant relationships (p<0.05) between stream DOM quality, DOM bioavailability, and stream metabolism, burned watersheds are not exporting DOM that is more bioavailable. In addition, despite different terrestrial OM pools, burned and

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.

The influence of algal organic matter produced by Microcystis aeruginosa on coagulation-ultrafiltration treatment of natural organic matter.

PubMed

Xu, Jie; Zhao, Yanxia; Gao, Baoyu; Han, Songlin; Zhao, Qian; Liu, Xiaoli

2018-04-01

Cyanobacterial bloom causes the release of algal organic matter (AOM), which inevitably affects the treatment processes of natural organic matter (NOM). This study works on treating micro-polluted surface water (SW) by emerging coagulant, namely titanium sulfate (Ti(SO 4 ) 2 ), followed by Low Pressure Ultrafiltration (LPUF) technology. In particular, we explored the respective influence of extracellular organic matter (EOM) and intracellular organic matter (IOM) on synergetic EOM-NOM/IOM-NOM removal, functional mechanisms and subsequent filtration performance. Results show that the IOM inclusion in surface water body facilitated synergic IOM-NOM composite pollutants removal by Ti(SO 4 ) 2 , wherein loosely-aggregated flocs were produced, resulting in floc cake layer with rich porosity and permeability during LPUF. On the contrary, the surface water invaded by EOM pollutants increased Ti(SO 4 ) 2 coagulation burden, with substantially deteriorated both UV 254 -represented and dissolved organic matter (DOC) removal. Corresponded with the weak Ti(SO 4 ) 2 coagulation for EOM-NOM removal was the resultant serious membrane fouling during LPUF procedure, wherein dense cake layer was formed due to the compact structure of flocs. Although the IOM enhanced NOM removal with reduced Ti(SO 4 ) 2 dose and yielded mitigated membrane fouling, larger percentage of irreversible fouling was seen than NOM and EOM-NOM cases, which was most likely due to the substances with small molecular weight, such as microcystin, adhering in membrane pores. This research would provide theoretical basis for dose selection and process design during AOM-NOM water treatment. Copyright © 2018 Elsevier Ltd. All rights reserved.

Self-organization of dissolved organic matter to micelle-like microparticles in river water.

PubMed

Kerner, Martin; Hohenberg, Heinz; Ertl, Siegmund; Reckermann, Marcus; Spitzy, Alejandro

2003-03-13

In aquatic systems, the concept of the 'microbial loop' is invoked to describe the conversion of dissolved organic matter to particulate organic matter by bacteria. This process mediates the transfer of energy and matter from dissolved organic matter to higher trophic levels, and therefore controls (together with primary production) the productivity of aquatic systems. Here we report experiments on laboratory incubations of sterile filtered river water in which we find that up to 25% of the dissolved organic carbon (DOC) aggregates abiotically to particles of diameter 0.4-0.8 micrometres, at rates similar to bacterial growth. Diffusion drives aggregation of low- to high-molecular-mass DOC and further to larger micelle-like microparticles. The chemical composition of these microparticles suggests their potential use as food by planktonic bacterivores. This pathway is apparent from differences in the stable carbon isotope compositions of picoplankton and the microparticles. A large fraction of dissolved organic matter might therefore be channelled through microparticles directly to higher trophic levels--bypassing the microbial loop--suggesting that current concepts of carbon conversion in aquatic systems require revision.

The removal characteristics of natural organic matter in the recycling of drinking water treatment sludge: Role of solubilized organics.

PubMed

Zhou, Zhiwei; Yang, Yanling; Li, Xing; Ji, Siyang; Zhang, Hao; Wang, Shuai; Zeng, Qingping; Han, Xinghang

2016-01-01

To clarify the role of solubilized organics derived from drinking water treatment sludge (DWTS) in the elimination of natural organic matter (NOM) in the DWTS recycling process, a probe sonoreactor at a frequency of 25 kHz was used to solubilize the organics at varied specific energies. The coagulation behavior related to NOM removal in recycling the sonicated DWTS with and without solubilized organics was evaluated, and the effect on organic fractionations in coagulated water was determined. The study results could provide useful implications in designing DWTS recycling processes that avoid the enrichment of organic matter. Our results indicate that DWTS was disrupted through a low release of soluble chemical oxygen demand (SCOD) and proteins, which could deteriorate the coagulated water quality under the specific energy of 37.87-1212.1 kW h/kg TS. The optimal coagulation behavior for NOM removal was achieved by recycling the sonicated DWTS without solubilized organics at 151.5 kW h/kg TS specific energy. Recycling the sonicated DWTS could increase the enrichment potential of weakly hydrophobic acid, hydrophilic matter, and <3 kDa fractions; the enrichment risks could be reduced by discharging the solubilized organics. Fluorescent characteristic analysis indicated that when recycling the sonicated DWTS without solubilized organics, the removal of humic-like substances was limited, whereas removal of protein-like substances was enhanced, lowering the enrichment potential of protein-like substances. Copyright © 2015. Published by Elsevier B.V.

Numerical simulation of organic waste aerobic biodegradation: a new way to correlate respiration kinetics and organic matter fractionation.

PubMed

Denes, Jeremy; Tremier, Anne; Menasseri-Aubry, Safya; Walter, Christian; Gratteau, Laurette; Barrington, Suzelle

2015-02-01

Composting wastes permits the reuse of organic matter (OM) as agricultural amendments. The fate of OM during composting and the subsequent degradation of composts in soils largely depend on waste OM quality. The proposed study aimed at developing a model to predict the evolution in organic matter quality during the aerobic degradation of organic waste, based on the quantification of the various OM fractions contained in the wastes. The model was calibrated from data gathered during the monitoring of four organic wastes (two non-treated wastes and their digestates) exposed to respirometric tests. The model was successfully fitted for all four wastes and permitted to predict respiration kinetics, expressed as CO2 production rates, and the evolution of OM fractions. The calibrated model demonstrated that hydrolysis rates of OM fractions were similar for all four wastes whereas the parameters related to microbial activity (eg. growth and death rates) were specific to each substrate. These later parameters have been estimated by calibration on respirometric data, thus demonstrating that coupling analyses of OM fractions in initial wastes and respirometric tests permit the simulation of the biodegradation of various type of waste. The biodegradation model presented in this paper could thereafter be integrated in a composting model by implementing mass and heat balance equations. Copyright © 2014 Elsevier Ltd. All rights reserved.

Natural organic matter (NOM) adsorption to multi-walled carbon nanotubes: effect of NOM characteristics and water quality parameters.

PubMed

Hyung, Hoon; Kim, Jae-Hong

2008-06-15

The effect of natural organic matter (NOM) characteristics and water quality parameters on NOM adsorption to multiwalled carbon nanotubes (MWNT) was investigated. Isotherm experiment results were fitted well with a modified Freundlich isotherm model that took into account the heterogeneous nature of NOM. The preferential adsorption of the higher molecular weight fraction of NOM was observed by size exclusion chromatographic analysis. Experiments performed with various NOM samples suggested that the degree of NOM adsorption varied greatly depending on the type of NOM and was proportional to the aromatic carbon content of NOM. The NOM adsorption to MWNT was also dependent on water quality parameters: adsorption increased as pH decreased and ionic strength increased. As a result of NOM adsorption to MWNT, a fraction of MWNT formed a stable suspension in water and the concentration of MWNT suspension depended on the amount of NOM adsorbed per unit mass of MWNT. The amount of MWNT suspended in water was also affected by ionic strength and pH. The findings in this study suggested that the fate and transport of MWNT in natural systems would be largely influenced by NOM characteristics and water quality parameters.

Hydrologic control of dissolved organic matter concentration and quality in a semiarid artificially drained agricultural catchment

NASA Astrophysics Data System (ADS)

Bellmore, Rebecca A.; Harrison, John A.; Needoba, Joseph A.; Brooks, Erin S.; Kent Keller, C.

2015-10-01

Agricultural practices have altered watershed-scale dissolved organic matter (DOM) dynamics, including in-stream concentration, biodegradability, and total catchment export. However, mechanisms responsible for these changes are not clear, and field-scale processes are rarely directly linked to the magnitude and quality of DOM that is transported to surface water. In a small (12 ha) agricultural catchment in eastern Washington State, we tested the hypothesis that hydrologic connectivity in a catchment is the dominant control over the concentration and quality of DOM exported to surface water via artificial subsurface drainage. Concentrations of dissolved organic carbon (DOC) and humic-like components of DOM decreased while the Fluorescence Index and Freshness Index increased with depth through the soil profile. In drain discharge, these characteristics were significantly correlated with drain flow across seasons and years, with drain DOM resembling deep sources during low-flow and shallow sources during high flow, suggesting that DOM from shallow sources bypasses removal processes when hydrologic connectivity in the catchment is greatest. Assuming changes in streamflow projected for the Palouse River (which contains the study catchment) under the A1B climate scenario (rapid growth, dependence on fossil fuel, and renewable energy sources) apply to the study catchment, we project greater interannual variability in annual DOC export in the future, with significant increases in the driest years. This study highlights the variability in DOM inputs from agricultural soil to surface water on daily to interannual time scales, pointing to the need for a more nuanced understanding of agricultural impacts on DOM dynamics in surface water.

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...

Features of distribution and quality of organic matter in the bottom sediments of the Great Peter Bay (Sea of Japan)

NASA Astrophysics Data System (ADS)

Nesterova, Olga; Tregubova, Valentina; Semal, Victoria; Vasenev, Ivan

2017-04-01

The nature and distribution of organic carbon in marine waters depends on: 1) biological productivity and revenue of the autochthonous organic matter to the bottom; 2) sediment grain-size composition and conditions of dumping, which in turn depends of hydrothermic regime, topography, speed River mist and received major erosion products; 3) living conditions of the benthos (the quantity consumed of OM, gas regime of habitats, physiological capacity of heterotrophs). Autochthonous OM of phytoplankton plays a dominant role in the processes of formation of humus in aquatic conditions. Bottom sediments at different distance from the shoreline to depths from 0.5 up to 480 m of the Sea of Japan, which are formed in various conditions of facies, were selected as the objects of study. There is no clear relationships to the amount of organic matter in bottom sediments on the characteristics of the distribution and nature of living matter in the oceans and seas. This is because the process of sedimentation and fossilization of organic matter on the seabed and the ocean floor depends on many factors (currents, depth). Humus of studied bottom sediments in composition can be attributed mainly to the humic type. Nonhydrolyzing rest is 70-90%. This is characteristic of bottom sediments formed in facial types of small bays, internal coastal shelf bights and the underwater slope. At a fraction of the carbon of humic acids in organic matter, ranging from 4 to 80% of the amount of humic and fulvic acids. Fulvic acids content is much less. This is due to more favourable conservation situation of humic acids in precipitation with high content of organic matter, whereas fulvic acids in aquatic environments are more labile and almost not dumped. Despite the fact humic acids are not the most stable component (s), however, with increased content of humic acids, the mobility of organic matter and removing it from the bottom sediments are reduced. Internal shelf facies of the Great Peter Bay

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

NASA Astrophysics Data System (ADS)

Mead, Ralph N.; Goñi, Miguel A.

2008-06-01

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

Impacts of Changing Precipitation on Natural Organic Matter and Microorganisms in Lakes and Reservoirs

EPA Science Inventory

Changes in watershed hydrology affect runoff of natural organic matter and contaminants that can in turn have important effects on water quality in lakes. We analyzed data obtain at lakes, reservoirs, and nearby riverine tributaries in Wisconsin (Lake Michigan), the Poconos, and ...

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

Effects of watershed history on dissolved organic matter characteristics in headwater streams

Treesearch

Youhei Yamashita; Brian D. Kloeppel; Jennifer Knoepp; Gregory L. Zausen; Rudolf Jaffe'

2011-01-01

Dissolved organic matter (DOM) is recognized as a major component in the global carbon cycle and is an important driver in aquatic ecosystem function. Climate, land use, and forest cover changes all impact stream DOM and alter biogeochemical cycles in terrestrial environments. We determined the temporal variation in DOM quantity and quality in headwater streams at a...

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.

Organic matter quantity and quality, metals availability and foraminiferal assemblages as environmental proxy applied to the Bizerte Lagoon (Tunisia).

PubMed

Martins, Maria Virgínia Alves; Helali, Mohamed Amine; Zaaboub, Noureddine; Boukef-BenOmrane, Imen; Frontalini, Fabrizio; Reis, Darlly; Portela, Helena; Clemente, Iara Martins Matos Moreira; Nogueira, Leandro; Pereira, Egberto; Miranda, Paulo; El Bour, Monia; Aleya, Lotfi

2016-04-15

This study analyzes the benthic trophic state of Bizerte Lagoon (Tunisia) based on the total organic matter and the bioavailability of biopolymeric carbon including proteins (PTN), carbohydrates (CHO), lipids (LIP), chlorophyll a, as well as bacteria counts. The overall simultaneously extracted metals (SEM), and acid volatile sulfides (AVS) as well as the SEM/AVS ratio indicative of the toxicity of the sediments also were analyzed aiming to study their impact in the dimension, composition and structure of both dead and living benthic foraminiferal assemblages. In the studied sites TOC content is relatively high and the PTN/CHO values indicate that they can be considered as meso-eutrophic environments. The CHO/TOC and C/N values suggest that the OM which accumulated on the sediments surface has mainly natural origin despite the introduction of municipal and industrial effluents in the lagoon and the large bacterial pool. The living assemblages of benthic foraminifera of Bizerte Lagoon are quite different to other Mediterranean transitional systems studied until now. They are composed of typical lagoonal species but also include several marine and opportunistic species including significant numbers of bolivinids, buliminids, Nonionella/Nonionoides spp. and Cassidulina/Globocassidulina spp. These assemblages seem to benefitfrom the physicochemical parameters and the sediment stability. They may however face environmental stress in the lagoon related to the AVS production as a result of the organic matter degradation and toxicity in some areas due to the available concentrations of metals. Nonetheless statistical results evidence that the structure and dimension of assemblages are being controlled mostly by OM quantity and quality related mainly to the availability of PTN, CHO and chlorophyll a. Results of this work support the importance of considering OM quantity and quality in studies of environmental impact in coastal systems. Copyright © 2016 Elsevier Ltd. All

[Effects of the different land use on soil labile organic matter and carbon management index in Junyun Mountain].

PubMed

Xu, Peng; Jiang, Chang-Sheng; Hao, Qing-Ju; Zhu, Tao

2013-10-01

The impacts of different land use on soil organic matter (SOM), soil labile organic matter (SLOM) and their efficiency ratios (ER), and soil carbon management index (CMI) were studied in this study. Subtropical evergreen broad-leaved forest (abbreviation: forest) , sloping farmland, orchard and abandoned land were selected and soils at the depths of 0-10, 10-20, 20-30, 30-40, 40-50 and 50-60 cm were sampled in the spring of 2011 to determine the contents of soil organic matter and labile organic matter. The results showed that the contents of soil organic matter and soil labile organic matter both decreased with the increase of soil depth under all four land use types; however, forest and orchard enriched SOM and SLOM contents in the 0-10 cm and 0-20 cm soil layers, respectively, while the contents of SOM and SLOM decreased evenly in sloping farmland and abandoned land. In the whole soil layer (0-60 cm) , the order of SOM and SLOM contents was abandoned land > forest > orchard > sloping farmland, indicating that at the conversion from forest into orchard or sloping farmland, SOM was reduced by 21.56% (P >0.05) and 55.90% (P <0.05), respectively, and at the conversion from sloping farmland into abandoned land, the low SLOM, middle SLOM and high SLOM increased by 144.2% (P<0.05) , 153.3% (P <0.05) and 242.7% (P <0.05), respectively. There was no significant difference in low ER, middle ER and high ER among the four land uses as suggested by ANOVA which showed that SRs were not sensible to the change of land use. All three CMis were in the order of abandoned land > forest > orchard > sloping farmland, revealing that forest reclamation resulted in the reduction of soil organic carbon storage and the decline of soil quality, and the abandonment of sloping farmland would increase soil carbon sink and improve soil quality. Three kinds of SLOM were all positively correlated with soil total nitrogen, available phosphorus and available potassium, while negatively correlated

Relationship between dissolved organic matter quality and microbial community composition across polar glacial environments.

PubMed

Smith, H J; Dieser, M; McKnight, D M; SanClements, M D; Foreman, C M

2018-05-14

Vast expanses of Earth's surface are covered by ice, with microorganisms in these systems affecting local and global biogeochemical cycles. We examined microbial assemblages from habitats fed by glacial meltwater within the McMurdo Dry Valleys, Antarctica, and on the west Greenland Ice Sheet, (GrIS) evaluating potential physicochemical factors explaining trends in community structure. Microbial assemblages present in the different Antarctic dry valley habitats were dominated by Sphingobacteria and Flavobacteria, while Gammaproteobacteria and Sphingobacteria prevailed in west GrIS supraglacial environments. Microbial assemblages clustered by location (Canada Glacier, Cotton Glacier, west GrIS) and were separated by habitat type (i.e. ice, cryoconite holes, supraglacial lakes, sediment, and stream water). Community dissimilarities were strongly correlated with dissolved organic matter (DOM) quality. Microbial meltwater assemblages were most closely associated with different protein-like components of the DOM pool. Microbes in environments with mineral particles (i.e. stream sediments, cryoconite holes) were linked to DOM containing more humic-like fluorescence. Our results demonstrate the establishment of distinct microbial communities within ephemeral glacial meltwater habitats, with DOM-microbe interactions playing an integral role in shaping communities on local and polar spatial scales.

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...

Dissolved Organic Matter (DOM) Export from Watersheds to Coastal Oceans

NASA Astrophysics Data System (ADS)

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

2016-02-01

Dissolved organic matter (DOM) from terrestrial plants and soils is transported by surface waters and groundwaters to coastal ocean waters. Along the way, photochemical and biological degradation can remove DOM, and in situ processes such as phytoplankton leaching and sediment sources can add to the DOM in the river water. Wetlands, especially coastal wetlands can add significant amounts of DOM that is carried by rivers and is exported through estuaries to coastal systems. We will present observational data from a variety of coastal systems (San Francisco Bay, Boston Harbor, Chesapeake Bay, Hudson River, the Mississippi River, and a small salt marsh in the Gulf of Mexico). High resolution measurements of chromophoric dissolved organic matter (CDOM) can be correlated with dissolved organic carbon (DOC) so can be used to estimate DOC in specific systems and seasons. Gradients in CDOM/DOC combined with water fluxes can be used to estimate DOC fluxes from a variety of coastal watersheds to coastal systems. Influences of land use, system size, residence time, DOM quality, and photochemical and biological degradation will be discussed. The significance of coastal wetlands in the land-to-ocean export of DOC will be emphasized.

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.

Fungal–bacterial dynamics and their contribution to terrigenous carbon turnover in relation to organic matter quality

PubMed Central

Fabian, Jenny; Zlatanovic, Sanja; Mutz, Michael; Premke, Katrin

2017-01-01

Ecological functions of fungal and bacterial decomposers vary with environmental conditions. However, the response of these decomposers to particulate organic matter (POM) quality, which varies widely in aquatic ecosystems, remains poorly understood. Here we investigated how POM pools of substrates of different qualities determine the relative contributions of aquatic fungi and bacteria to terrigenous carbon (C) turnover. To this end, surface sediments were incubated with different POM pools of algae and/or leaf litter. 13C stable-isotope measurements of C mineralization were combined with phospholipid analysis to link the metabolic activities and substrate preferences of fungal and bacterial heterotrophs to dynamics in their abundance. We found that the presence of labile POM greatly affected the dominance of bacteria over fungi within the degrader communities and stimulated the decomposition of beech litter primarily through an increase in metabolic activity. Our data indicated that fungi primarily contribute to terrigenous C turnover by providing litter C for the microbial loop, whereas bacteria determine whether the supplied C substrate is assimilated into biomass or recycled back into the atmosphere in relation to phosphate availability. Thus, this study provides a better understanding of the role of fungi and bacteria in terrestrial–aquatic C cycling in relation to environmental conditions. PMID:27983721

Organic speciation of size-segregated atmospheric particulate matter

NASA Astrophysics Data System (ADS)

Tremblay, Raphael

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

Stabilization of polar soils organic matter: insights from 13-C NMR and ESR spectroscopy

NASA Astrophysics Data System (ADS)

Abakumov, Evgeny

2017-04-01

Polar soils play a key role in the global carbon balance, as they contain maximum stocks of soil organic matter (SOM) within the whole pedosphere. Low temperature and severe conditions provides the accumulation of large amounts of organic matter in permafrost soils over thousands of years. The quality and composition of organic matter of polar soils is underestimated. In order to better understand the implication of permafrost SOM to greenhouse gas emissions, an accurate knowledge of its spatial distribution, both in terms of quantity and quality (i.e. biodegradability, chemical composition and humification degree) is needed. The chemical composition of SOM determines its decomposability and, therefore, it determines the rate at which carbon may be transferred from soils to the atmosphere under warming conditions. Biodegradability of SOM has been related to humification degree, as more advanced stages in the humification process imply a depletion of the labile molecules, as well as an increase in the bulk aromaticity, which provides a higher stability of the SOM. Soils from Antarctic and different sectors of Arctic biome were investigated by 13-C NMR and electron spin resonance spectroscopy. It was shown, that the characteristic feature of polar soils humic acids is the dominance of aliphatic compounds on the aromatic one. This is related to the humification precursors component composition, namely to dominance of the remnants of lower plants, especially in Antarctic and low period of biological activity, which regulates the humification rate. Humic acids of Antarctic and various Arctic soils show the portion of aromatic components not more than 30 %. ESR spectroscopy shown that the concentration of free radicals is proportional to the humic acids stabilization degree. Less humified organic materials show the highest portion of free radical content, while the most developed soils and buried organic layers show decreased contents of free radicals. The database on

Investigation of water-soluble organic matter extracted from shales during leaching experiments

NASA Astrophysics Data System (ADS)

Zhu, Yaling; Vieth-Hillebrand, Andrea; Wilke, Franziska D. H.; Horsfield, Brian

2017-04-01

The huge volumes and unknown composition of flowback and produced waters cause major public concerns about the environmental and social compatibility of hydraulic fracturing and the exploitation of gas from unconventional reservoirs. Flowback and produced waters contain not only residues of fracking additives but also chemical species that are dissolved from the shales themselves during fluid-rock interaction. Knowledge of the composition, size and structure of dissolved organic carbon (DOC) as well as the main controls on the release of DOC are a prerequisite for a better understanding of these interactions and its effects on composition of flowback and produced water. Black shales from four different geological settings and covering a maturity range Ro = 0.3-2.6% were extracted with deionized water. The DOC yields were found to decrease rapidly with increasing diagenesis and remain low throughout catagenesis. Four DOC fractions have been qualitatively and quantitatively characterized using size-exclusion chromatography. The concentrations of individual low molecular weight organic acids (LMWOA) decrease with increasing maturity of the samples except for acetate extracted from the overmature Posidonia shale, which was influenced by hydrothermal brines. The oxygen content of the shale organic matter also shows a significant influence on the release of organic acids, which is indicated by the positive trend between oxygen index (OI) and the concentrations of formate and acetate. Based on our experiments, both the properties of the organic matter source and the thermal maturation progress of the shale organic matter significantly influence the amount and quality of extracted organic compounds during the leaching experiments.

Simultaneous organic matter removal and nitrification of an inert self-supporting immersed media to upgrade aerated lagoons.

PubMed

Boutet, E; Baillargeon, S; Patry, B; Lessard, P

2018-01-01

A pilot study was performed to evaluate the potential of an inert self-supported immersed fixed film media to upgrade aerated lagoons. Simultaneous organic matter removal and nitrification was assessed under different loading rates and temperatures (near 0 °C) using 12 laboratory-scale reactors operated in parallel. Test results showed that both the temperature and the load have an influence on organic matter effluent concentrations. Effluent quality seemed related to the observed biofilm thickness. Thicker biofilm is believed to have contributed to biomass detachment and increased particulate organic matter concentrations in the effluent. Simultaneous organic removal and nitrification was obtained at loads above 5 g CBOD 5 /m 2 ·d. The highest nitrification rate at 0.4 °C was obtained for the smallest load, which showed a nitrification limitation close to freezing point.

Changes in the quality of chromophoric dissolved organic matter leached from senescent leaf litter during the early decomposition.

PubMed

Nishimura, Satoshi; Maie, Nagamitsu; Baba, Mitsuhisa; Sudo, Takahiro; Sugiura, Toshihiro; Shima, Eikichi

2012-01-01

Chromophoric dissolved organic matter (CDOM) leached from leaf litter is a major source of humus in mineral soil of forest ecosystems. While their functions and refractoriness depend on the physicochemical structure, there is little information on the quality of CDOM, especially for that leached in the very early stages of litter decomposition when a large amount of dissolved organic matter (DOM) is leached. This study aimed to better understand the variations/changes in the composition of CDOM leached from senescent leaf litter from two tree species during the early stage of decomposition. Leaf litter from a conifer tree (Japanese cedar, D. Don) and a deciduous broad-leaved tree (Konara oak, Thunb.) were incubated in columns using simulated rainfall events periodically for a total of 300 d at 20°C. The quality of CDOM was investigated based on the fluorescence properties by using a combination of excitation-emission matrix fluorescence (EEM) and parallel factor analysis (PARAFAC). In addition, the phenolic composition of DOM was investigated at a molecular level by thermally assisted hydrolysis and methylation-gas chromatography-mass spectrometry (THM-GC-MS) in the presence of tetramethylammonium hydroxide (TMAH). The EEM was statistically decomposed into eight fluorescence components (two tannin/peptide-like peaks, one protein-like peak, and five humic-like peaks). A significant contribution of tannin/peptide-like peaks was observed at the beginning of incubation, but these peaks decreased quickly and humic-like peaks increased within 1 mo of incubation. The composition of humic-like peaks was different between tree species and changed over the incubation period. Since tannin-derived phenolic compounds were detected in the DOM collected after 254 d of incubation on THM-GC-MS, it was suggested that tannins partially changed its structure, forming various humic-like peaks during the early decomposition. Copyright © by the American Society of Agronomy, Crop

Relative humidity-dependent viscosity of secondary organic material from toluene photo-oxidation and possible implications for organic particulate matter over megacities

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

Song, Mijung; Liu, Pengfei F.; Hanna, Sarah J.

To improve predictions of air quality, visibility, and climate change, knowledge of the viscosities and diffusion rates within organic particulate matter consisting of secondary organic material (SOM) is required. Most qualitative and quantitative measurements of viscosity and diffusion rates within organic particulate matter have focused on SOM particles generated from biogenic volatile organic compounds (VOCs) such as α-pinene and isoprene. In this study, we quantify the relative humidity (RH)-dependent viscosities at 295±1K of SOM produced by photo-oxidation of toluene, an anthropogenic VOC. The viscosities of toluene-derived SOM were 2 × 10 ₋1 to ~6 ×10 6Pa s from 30 tomore » 90%RH, and greater than ~2 × 10 8 Pa s (similar to or greater than the viscosity of tar pitch) for RH ≤ 17%. These viscosities correspond to Stokes–Einstein-equivalent diffusion coefficients for large organic molecules of ~2 ×10 ₋15cm 2s ₋1 for 30 % RH, and lower than ~3 × 10 ₋17cm 2s ₋1 for RH ≤ 17 %. Based on these estimated diffusion coefficients, the mixing time of large organic molecules within 200 nm toluene-derived SOM particles is 0.1–5 h for 30% RH, and higher than ~100 h for RH ≤ 17%. As a starting point for understanding the mixing times of large organic molecules in organic particulate matter over cities, we applied the mixing times determined for toluene-derived SOM particles to the world's top 15 most populous megacities. If the organic particulate matter in these megacities is similar to the toluene-derived SOM in this study, in Istanbul, Tokyo, Shanghai, and São Paulo, mixing times in organic particulate matter during certain periods of the year may be very short, and the particles may be well-mixed. On the other hand, the mixing times of large organic molecules in organic particulate matter in Beijing, Mexico City, Cairo, and Karachi may be long and the particles may not be well-mixed in the afternoon (15:00–17:00 LT) during certain times of

ORGANIC MATTER MANIPULATIONS HAVE LITTLE EFFECT ON GROSS AND NET NITROGEN TRANSFORMATIONS IN TWO TEMPERATE FOREST MINERAL SOILS IN THE USA AND CENTRAL EUROPE

EPA Science Inventory

Soil nitrogen transformations are intricately linked to carbon transformations. We utilized two existing organic matter manipulation sites in western Oregon, USA and Hungary to investigate these linkages. Our questions were: 1) Does the quantity and quality of organic matter af...

Particulate organic matter predicts bacterial productivity in a river dominated estuary

NASA Astrophysics Data System (ADS)

Crump, B. C.

2015-12-01

Estuaries act as coastal filters for organic and inorganic fluvial materials in which microbial, biogeochemical, and ecological processes combine to transform organic matter and nutrients prior to export to the coastal ocean. The function of this estuarine 'bioreactor' is linked to the residence times of those materials and to rates of microbial heterotrophic activity. Our ability to forecast the impact of global change on estuarine bioreactor function requires an understanding of the basic controls on microbial community activity and diversity. In the Columbia River estuary, the microbial community undergoes a dramatic seasonal shift in species composition during which a spring bacterioplankton community, dominated by Flavobacteriaceae and Oceanospirillales, is replaced by a summer community, dominated by Rhodobacteraceae and several common marine taxa. This annual shift occurs in July, following the spring freshet, when river flow and river chlorophyll concentration decrease and when estuarine water residence time increases. Analysis of a large dataset from 17 research cruises (1990-2014) showed that the composition of particulate organic matter in the estuary changes after the freshet with decreasing organic carbon and nitrogen content, and increasing contribution of marine and autochthonous estuarine organic matter (based on PO13C and pigment ratios). Bacterial production rates (measured as leucine or thymidine incorporation rates) in the estuary respond to this change, and correlate strongly with labile particulate nitrogen concentration and temperature during individual sampling campaigns, and with the concentration of chlorophyll in the Columbia River across all seasons. Regression models suggest that the concentration of labile particulate nitrogen and the rate of bacterial production can be predicted from sensor measurements of turbidity, salinity, and temperature in the estuary and chlorophyll in the river. These results suggest that the quality of

Hydrological Controls on Dissolved Organic Matter Quality and Export in a Coastal River System in Southeastern USA

NASA Astrophysics Data System (ADS)

Bhattacharya, R.; Osburn, C. L.

2017-12-01

Dissolved organic matter (DOM) exported from river catchments can influence the biogeochemical processes in coastal environments with implications for water quality and carbon budget. High flow conditions are responsible for most DOM export ("pulses") from watersheds, and these events reduce DOM transformation and production by "shunting" DOM from river networks into coastal waters: the Pulse-Shunt Concept (PSC). Subsequently, the source and quality of DOM is also expected to change as a function of river flow. Here, we used stream dissolved organic carbon concentrations ([DOC]) along with DOM optical properties, such as absorbance at 350 nm (a350) and fluorescence excitation and emission matrices modeled by parallel factor analysis (PARAFAC), to characterize DOM source, quality and fluxes under variable flow conditions for the Neuse River, a coastal river system in the southeastern US. Observations were made at a flow gauged station above head of tide periodically between Aug 2011 and Feb 2013, which captured low flow periods in summer and several high flow events including Hurricane Irene. [DOC] and a350 were correlated and varied positively with river flow, implying that a large portion of the DOM was colored, humic and flow-mobilized. During high flow conditions, PARAFAC results demonstrated the higher influx of terrestrial humic DOM, and lower in-stream phytoplankton production or microbial degradation. However, during low flow, DOM transformation and production increased in response to higher residence times and elevated productivity. Further, 70% of the DOC was exported by above average flows, where 3-4 fold increases in DOC fluxes were observed during episodic events, consistent with PSC. These results imply that storms dramatically affects DOM export to coastal waters, whereby high river flow caused by episodic events primarily shunt terrestrial DOM to coastal waters, whereas low flow promotes in-stream DOM transformation and amendment with microbial DOM.

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

High dimensional reflectance analysis of soil organic matter

NASA Technical Reports Server (NTRS)

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

1992-01-01

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

Organic and inorganic matter in Louisiana coastal waters: Vermilion, Atchafalaya, Terrebonne, Barataria, and Mississippi regions.

PubMed

Schaeffer, Blake A; Conmy, Robyn N; Aukamp, Jessica; Craven, George; Ferer, Erin J

2011-02-01

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 Mississippi River locations, in 2007-2008. The range of CDOM was 0.092 m⁻¹ at Barataria in June 2008 to 11.225 m⁻¹ at Mississippi in February 2008. An indicator of organic matter quality was predicted by the spectral slope of absorption coefficients from 350 to 412nm which was between 0.0087 m⁻¹ at Mississippi in May 2008 and 0.0261 m⁻¹ at Barataria in June 2008. CDOM was the dominant component of light attenuation at Terrebonne and Barataria. Detritus and CDOM were the primary components of light attenuation at Vermilion, Atchafalaya, and Mississippi. DOC ranged between 65 and 1235 μM. PIM ranged between 1.1 and 426.3 mg L⁻¹ and POM was between 0.3 and 49.6 mg L⁻¹. Published by Elsevier Ltd.

Adsorption of natural dissolved organic matter at the oxide/water interface

USGS Publications Warehouse

Davis, James A.

1982-01-01

Natural organic matter is readily adsorbed by alumina and kaolinite in the pH range of natural waters. Adsorption occurs by complex formation between surface hydroxyls and the acidic functional groups of the organic matter. Oxides with relatively acidic surface hydroxyls, e.g. silica, do not react strongly with the organic matter. Under conditions typical for natural waters, almost complete surface coverage by adsorbed organic matter may be expected for alumina, hydrous iron oxides and the edge sites of aluminosilicates. Potentiometric titration and electrophoresis indicate that most of the acidic functional groups of the adsorbed organic matter are neutralized by protons from solution. The organic coating is expected to have a great influence on subsequent adsorption of inorganic cations and anions.

Soil particulate organic matter dynamics after conservation reserve program land is converted to cropland

USDA-ARS?s Scientific Manuscript database

The objective of this project is to compare the soil C quality in Conservation Reserve Program (CRP) vs. land under Sorghum cropping or rangeland in the Southern High Plains. Whole soils as well as light fraction particulate organic matter (lfPOM) was assessed using diffuse reflectance Fourier trans...

Fluorescence spectroscopic analysis of organic matter fractions: the current status and a tutorial case study

USDA-ARS?s Scientific Manuscript database

Incorporation of animal manures into soils is a key nutrient management strategy for sustainable agricultural systems by supplying plant nutrients and maintaining soil quality. Dissolved organic matter (DOM) released from manures affects many soil chemical processes due to its reactivity with soil ...

Changes in dissolved organic matter quality in a peatland and forest headwater stream as a function of seasonality and hydrologic conditions

NASA Astrophysics Data System (ADS)

Broder, Tanja; Knorr, Klaus-Holger; Biester, Harald

2017-04-01

Peatlands and peaty riparian zones are major sources of dissolved organic matter (DOM), but are poorly understood in terms of export dynamics and controls thereof. Thereby quality of DOM affects function and behavior of DOM in aquatic ecosystems, but DOM quality can also help to track DOM sources and their export dynamics under specific hydrologic preconditions. The objective of this study was to elucidate controls on temporal variability in DOM concentration and quality in stream water draining a bog and a forested peaty riparian zone, particularly considering drought and storm flow events. DOM quality was monitored using spectrofluorometric indices for aromaticity (SUVA254), apparent molecular size (SR) and precursor organic material (FI), as well as PARAFAC modeling of excitation emission matrices (EEMs). Indices for DOM quality exhibited major changes due to different hydrologic conditions, but patterns were also dependent on season. Stream water at the forested site with mineral, peaty soils generally exhibited higher variability in DOM concentrations and quality compared to the outflow of an ombrotrophic bog, where DOM was less susceptible to changes in hydrologic conditions. During snowmelt and spring events, near-surface protein-like DOM pools were exported. A microbial DOM fraction originating from groundwater and deep peat layers was increasing during drought, while a strongly microbially altered DOM fraction was also exported by discharge events with dry preconditions at the forested site. This might be due to accelerated microbial activity in the peaty riparian zone of the forested site under these preconditions. Our study demonstrated that DOM export dynamics are not only a passive mixing of different hydrological sources, but monitoring studies have to consider that DOM quality depends on hydrologic preconditions and season. Moreover, the forested peaty riparian zone generated the most variability in headwater DOM quantity and quality, as could be

The Case Against Charge Transfer Interactions in Dissolved Organic Matter Photophysics.

PubMed

McKay, Garrett; Korak, Julie A; Erickson, Paul R; Latch, Douglas E; McNeill, Kristopher; Rosario-Ortiz, Fernando L

2018-01-16

The optical properties of dissolved organic matter influence chemical and biological processes in all aquatic ecosystems. Dissolved organic matter optical properties have been attributed to a charge-transfer model in which donor-acceptor complexes play a primary role. This model was evaluated by measuring the absorbance and fluorescence response of organic matter isolates to changes in solvent temperature, viscosity, and polarity, which affect the position and intensity of spectra for known donor-acceptor complexes of organic molecules. Absorbance and fluorescence spectral shape were largely unaffected by these changes, indicating that the distribution of absorbing and emitting species was unchanged. Overall, these results call into question the wide applicability of the charge-transfer model for explaining organic matter optical properties and suggest that future research should explore other models for dissolved organic matter photophysics.

Global Warming Potential from early phase decomposition of soil organic matter amendments

NASA Astrophysics Data System (ADS)

Mayer, A.; Silver, W. L.

2015-12-01

Organic matter amendments to soil are widely used as a method of enhancing nutrient availability for crops or grassland. Amendments such as composted manure or greenwaste also have the co-benefits of potentially increasing soil carbon (C) stocks (DeLonge et al., 2013) and diverting organic waste from landfills or manure lagoons. However, application of organic matter amendments can also stimulate emissions of greenhouse gases (GHGs). In this study we determined how the chemical quality of organic matter amendments affected soil C and N content and GHG emissions during early stage decomposition. California grassland soils were amended with six different amendments of varying C and N content including three composts and three feedstocks (goat and horse bedding and cattle manure). Amendments and soils were incubated in the laboratory for 7 weeks; GHG fluxes were measured weekly. The three feedstocks emitted significantly more GHGs than the composted materials. With the exception of cow manure, N content of the amendment was linearly correlated with global warming potential emitted (R2= 0.66, P <0.0001). C:N ratios were not a significant predictor of GHG emissions. Cow manure stimulated a net loss of C (or C equivalents) in the mineral soil, as expected. However, greenwaste compost also surprisingly resulted in net C losses, while goat bedding, horse bedding, and the other compost were either C neutral or a slight net C sink at the end of the incubation. Ongoing analyses are examining the fate of the C incorporated from the amendment to the soil as occluded or free light fraction, as well as N mineralization rates. Our data suggest that N content of organic matter amendments is a good predictor of initial GHG emissions. The study also indicates that composting greenwaste with N-rich bedding and manure can result in lower GHG emissions and C sequestration compared to the individual uncomposted components.

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.

soil organic matter pools and quality are sensitive to global climate change in tropical forests from India

NASA Astrophysics Data System (ADS)

Mani, Shanmugam; Merino, Agustín; García-Oliva, Felipe; Riotte, Jean; Sukumar, Raman

2016-04-01

Soil organic carbon (SOC) storage and quality are some of the most important factors determining ecological process in tropical forests, which are especially sensitive to global climate change (GCC). In India, the GCC scenarios expect increasing of drought period and wildfire, which may affect the SOC, and therefore the capacity of forest for C sequestration. The aim of the study was to evaluate the amount of soil C and its quality in the mineral soil across precipitation gradient with different factors (vegetation, pH, soil texture and bedrock composition) for generate SOC predictions under GCC. Six soil samples were collected (top 10 cm depth) from 19 1-ha permanent plots in the Mudumalai Wildlife Sanctuary of southern India, which are characterised by four types of forest vegetation (i.e. dry thorn, dry deciduous, moist deciduous and semi-evergreen forest) distributed along to rainfall gradient. The driest sites are dominated by sandy soils, while the soil clay proportion increased in the wet sites. Total organic C (Leco CN analyser), and the SOM quality was assessed by Differential Scanning Calorimetry (DSC) and Solid-state 13CCP-MAS NMR analyses. Soil organic C was positively correlated with precipitation (R2 = 0.502, p<0.01) and with soil clay content (R2 =0.15, p<0.05), and negatively with soil sand content (R2=0.308, p<0.001) and with pH (R2=0.529, p<0.01); while the C/N was only found positive correlation with clay (R2= 0.350, p<0.01). The driest sites (dry thorn forest) has the lowest proportion of thermal combustion of recalcitrant organic matter (Q2,375-475 °C) than the other sites (p<0.05) and this SOC fraction correlated positively with rainfall (R2=0.27, p=0.01). The Q2 model with best fit included rainfall, pH, sand, clay, C and C/N (R2=0.52, p=0.01). Principal component analysis explains 77% of total variance. The sites on the fist component are distributed along the rainfall gradient. These results suggest that the 50% of variance was explained

Terrestrial litter inputs as determinants of food quality of organic matter in a forest stream

Treesearch

J.L. Meyer; C. Hax; J.B. Wallace; S.L. Eggert; J.R. Webster

2000-01-01

Inputs of leaf litter and other organic matter from the catchment exceed autochthonous production and provide an important food resource in most streams (WEBSTER & MEYER 1997, ANDERSON & SEDELL 1979). An experimental long-term exclusion of terrestrial litter inputs to a forested headwater stream (WALLACE et al. 1997) provided an opportunity to determine if the...

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

NASA Technical Reports Server (NTRS)

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

2003-01-01

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

Solid-state 13C NMR experiments reveal effects of aggregate size on the chemical composition of particulate organic matter in grazed steppe soils

NASA Astrophysics Data System (ADS)

Steffens, M.; Kölbl, A.; Kögel-Knabner, I.

2009-04-01

Grazing is one of the most important factors that may reduce soil organic matter (SOM) stocks and subsequently deteriorate aggregate stability in grassland topsoils. Land use management and grazing reduction are assumed to increase the input of OM, improve the soil aggregation and change species composition of vegetation (changes depth of OM input). Many studies have evaluated the impact of grazing cessation on SOM quantity. But until today little is known about the impact of grazing cessation on the chemical quality of SOM in density fractions, aggregate size classes and different horizons. The central aim of this study was to analyse the quality of SOM fractions in differently sized aggregates and horizons as affected by increased inputs of organic matter due to grazing exclusion. We applied a combined aggregate size, density and particle size fractionation procedure to sandy steppe topsoils with different organic matter inputs due to different grazing intensities (continuously grazed = Cg, winter grazing = Wg, ungrazed since 1999 = Ug99, ungrazed since 1979 = Ug79). Three different particulate organic matter (POM; free POM, in aggregate occluded POM and small in aggregate occluded POM) and seven mineral-associated organic matter fractions were separated for each of three aggregate size classes (coarse = 2000-6300 m, medium = 630-2000 m and fine =

The Case Against Charge Transfer Interactions in Dissolved Organic Matter Optical Properties

NASA Astrophysics Data System (ADS)

McKay, G.; Korak, J.; Erickson, P. R.; Latch, D. E.; McNeill, K.; Rosario-Ortiz, F.

2017-12-01

The optical properties of dissolved organic matter influence chemical and biological processes in all aquatic ecosystems. Organic matter optical properties have been used by scientists and engineers for decades for remote sensing, in situ monitoring, and characterizing laboratory samples to track dissolved organic carbon concentration and character. However, there is still a lack of understanding of the origin of organic matter optical properties, which could conflict with other empirical fluorescence interpretation methods (e.g. PARAFAC). Organic matter optical properties have been attributed to a charge-transfer model in which donor-acceptor complexes play a primary role. This model was evaluated by measuring the absorbance and fluorescence response of organic matter isolates to perturbations in solvent temperature, viscosity, and polarity, which affect the position and intensity of spectra for known donor-acceptor complexes of organic molecules. Absorbance and fluorescence spectral shape were unaffected by these perturbations, indicating that the distribution of absorbing and emitting species was unchanged. These results call into question the wide applicability of the charge-transfer model for explaining organic matter optical properties and suggest that future research should explore other models for organic matter photophysics.

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.

Students Matter: Quality Measurements in Online Courses

ERIC Educational Resources Information Center

Unal, Zafer; Unal, Aslihan

2016-01-01

Quality Matters (QM) is a peer review process designed to certify the quality of online courses and online components. It has generated widespread interest and received national recognition for its peer-based approach to quality assurance and continuous improvement in online education. While the entire QM online course design process is…

Interstellar chemistry recorded in organic matter from primitive meteorites.

PubMed

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

2006-05-05

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

Water quality monitoring in a bathing area of Civitavecchia (Latium, Italy) using Chromophoric Dissolved Organic Matter (CDOM) as a tracer of faecal contamination

NASA Astrophysics Data System (ADS)

Madonia, Alice; Bonamano, Simone; Caruso, Gabriella; Stefani', Chiara; Consalvi, Natalizia; Piermattei, Viviana; Zappalà, Giuseppe; Marcelli, Marco

2017-04-01

Coastal urban bathing areas are often affected by events of faecal contamination, caused by the discharge of untreated wastewaters during the bathing season that can increase the risk for public health. Monitoring the quality of recreational waters is still closely linked to time-consuming seawater sampling and laboratory analysis, not allowing promptly management interventions. To face this issue, the European environmental policies strongly promote the development of coastal observing systems, above all in the Southern European Seas (SES). Chromophoric Dissolved Organic Matter (CDOM) has been increasingly used as a tracer of bacterial loads, since wastewaters are characterized by a large amount of organic compounds. The aim of this work was to study the relation between CDOM and Escherichia coli abundance, giving relevance to bacterial physiological state detected using both the standard culture method and the innovative fluorescent antibody technique. Attention has been paid also on the expression of extracellular enzymatic activity by the total microbial community to explore the role of bacteria in the decomposition processes of dissolved organic matter. Data were collected during summer 2015 and 2016 in a bathing area of Civitavecchia at increasing distances from the discharge point. The results confirm the usefulness of CDOM measurements as a proxy of faecal pollution in bathing areas. In this perspective, the low-cost stand-alone systems equipped with CDOM fluorescence sensors developed by the Laboratory of Experimental Oceanology and Marine Ecology (Tuscia University) (Marcelli et al., 2014) could allow the continous monitoring of water quality, increasing the capabilities of the Civitavecchia Coastal Environmental Monitoring System (C-CEMS) in the analysis of pollution events. Thanks to the integration of in situ fixed stations, high-resolution satellites imagery and numerical models, C-CEMS provides a management tool to support the stakeholders for timely

Lime and phosphogypsum impacts on soil organic matter pools in a tropical Oxisol under long-term no-till conditions

USDA-ARS?s Scientific Manuscript database

Improving soil organic matter (SOM) quality in tropical acid soils is important for increasing the sustainability of agricultural ecosystems. This research evaluated the effect of the surface application of lime and phosphogypsum on the quality and amount of SOM in a long-term crop rotation under no...

Differential natural organic matter fouling of ceramic versus polymeric ultrafiltration membranes.

PubMed

Lee, Seung-Jin; Kim, Jae-Hong

2014-01-01

Ceramic ultrafiltration membranes has drawn increasing attention in drinking water treatment sectors as an alternative to traditional polymeric counterparts, yet only limited information has been made available about the characteristics of ceramic membrane fouling by natural organic matter. The effects of solution chemistry including ionic strength, divalent ion concentration and pH on the flux behavior were comparatively evaluated for ceramic and polymeric ultrafiltration of synthetic water containing model natural organic matter. Filtration characteristics were further probed via resistance-in-series model analysis, fouling visualization using quantum dots, batch adsorption test, contact angle measurement, solute-membrane surface adhesion force measurement, and quantitative comparison of fouling characteristics between ceramic and polymeric membranes. The results collectively suggested that the effects of solution chemistry on fouling behavior of ceramic membranes were generally similar to polymeric counterparts in terms of trends, while the extent varied significantly depending on water quality parameters. Lower fouling tendency and enhanced cleaning efficiency were observed with the ceramic membrane, further promoting the potential for ceramic membrane application to surface water treatment. Copyright © 2013 Elsevier Ltd. All rights reserved.

Do soils loose phosphorus with dissolved organic matter?

NASA Astrophysics Data System (ADS)

Kaiser, K.; Brödlin, D.; Hagedorn, F.

2014-12-01

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

Glacier inputs influence organic matter composition and prokaryotic distribution in a high Arctic fjord (Kongsfjorden, Svalbard)

NASA Astrophysics Data System (ADS)

Bourgeois, Solveig; Kerhervé, Philippe; Calleja, Maria Ll.; Many, Gaël; Morata, Nathalie

2016-12-01

With climate change, the strong seasonality and tight pelagic-benthic coupling in the Arctic is expected to change in the next few decades. It is currently unclear how the benthos will be affected by changes of environmental conditions such as supplies of organic matter (OM) from the water column. In the last decade, Kongsfjorden (79°N), a high Arctic fjord in Svalbard influenced by several glaciers and Atlantic water inflow, has been a site of great interest owing to its high sensitivity to climate change, evidenced by a reduction in ice cover and an increase in melting freshwater. To investigate how spatial and seasonal changes in vertical fluxes can impact the benthic compartment of Kongsfjorden, we studied the organic matter characteristics (in terms of quantity and quality) and prokaryotic distribution in sediments from 3 stations along a transect extending from the glacier into the outer fjord in 4 different seasons (spring, summer, autumn and winter) in 2012-2013. The biochemical parameters used to describe the sedimentary organic matter were organic carbon (OC), total nitrogen, bulk stable isotope ratios, pigments (chorophyll-a and phaeopigments) and biopolymeric carbon (BPC), which is the sum of the main macromolecules, i.e. lipids, proteins and carbohydrates. Prokaryotic abundance and distribution were estimated by 4‧,6-diamidino-2-phenylindole (DAPI) staining. This study identifies a well-marked quantitative gradient of biogenic compounds throughout all seasons and also highlights a discrepancy between the quantity and quality of sedimentary organic matter within the fjord. The sediments near the glacier were organic-poor (< 0.3%OC), however the high primary productivity in the water column displayed during spring was reflected in summer sediments, and exhibited higher freshness of material at the inner station compared to the outer basin (means C-chlorophyll-a/OC 5 and 1.5%, respectively). However, sediments at the glacier front were depleted in BPC

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.

Distinguishing the influence of soil organic matter quality from that of environmental constraints in controlling soil heterotrophic respiration along a continental network of sites

NASA Astrophysics Data System (ADS)

Pare, D.; Bernier, P. Y.; Trofymow, J. A.; Moore, T. R.

2011-12-01

The forest soils of Canada contain large amounts of carbon and its dynamics is one of the key areas of uncertainty in the carbon balance of North America. While estimates of total soil carbon stocks are available, the relative role of soil organic matter (SOM) quality from that of environmental conditions in maintaining these C reservoirs is poorly known. Soil organic matter (SOM) quality was evaluated with the use of both acid hydrolysis and lab incubation at several temperatures for 15 sites part of the Fluxnet Canada network that represent the major ecological forest groups in Canada and included as well two peatland sites. The mineralizable fraction of soil total C (TOC) varied fivefold across sites and soil layers (4 to 25%). To the opposite acid hydrolysable C was a constant fraction of total organic C (TOC) representing 23 and 37% of TOC in the forest floor and top mineral soil (0-20cm) respectively. Total soil carbon pools were highly correlated with pools of recalcitrant C but weakly to labile pools, especially in the mineral soils. These results indicated that soils accumulating a thick organic layer, such as black spruce and peatland soils, are also accumulating potentially labile C that could be mineralised given favourable environmental conditions. However, this relationship is barely significant for the mineral soils where greater C accumulation indicated in essence more accumulation into recalcitrant pools. Mineralized C was correlated with cellulose concentration in the forest floor (R=0.68) and not with acid-hydrolizable C in either soil horizons suggesting that this fraction in non-relevant to C dynamics. Estimates soil heterotrophic respiration (Rh-lab) using incubation derived equation and field soil hourly temperatures were compared with the size of the soil potentially mineralizable C pool (labile C). The difference between these two figures was large for soil having a large portion of their C reserves in the organic layer but was small for

Quality Matters Rubric Potential for Enhancing Online Foreign Language Education

ERIC Educational Resources Information Center

Al Zumor, Abdul Wahed Q.

2015-01-01

Quality Matters Program is designed to certify the quality of online courses in colleges and universities across and beyond the U.S. The Quality Matters Rubric (QMR) consists of eight general standards and 41 specific standards which are used to evaluate and design online and blended courses. The purpose of this study is to highlight the QMR…

Organic geochemical analysis of sedimentary organic matter associated with uranium

USGS Publications Warehouse

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

1986-01-01

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

Comparison of biochar, zeolite and their mixture amendment for aiding organic matter transformation and nitrogen conservation during pig manure composting.

PubMed

Wang, Quan; Awasthi, Mukesh Kumar; Ren, Xiuna; Zhao, Junchao; Li, Ronghua; Wang, Zhen; Chen, Hongyu; Wang, Meijing; Zhang, Zengqiang

2017-12-01

The aim of this work was to compare the impact of biochar, zeolite and their mixture on nitrogen conservation and organic matter transformation during pig manure (PM) composting. Four treatments were set-up from PM mixed with wheat straw and then applied 10% biochar (B), 10% zeolite (Z) and 10% biochar+10% zeolite (B+Z) into composting mixtures (dry weight basis), while treatment without additives applied used as control. Results indicated that adding B, Z and B+Z could obviously (p<0.05) improve the organic matter degradation and decrease the nitrogen loss. And combined addition of B and Z further promoted the organic matter humification and reduced the heavy metals mobility. Meanwhile the highest mitigation of ammonia (63.40%) and nitrogen dioxide (78.13%) emissions was observed in B+Z added treatment. Comparison of organic matter transformation, nitrogen conservation and compost quality indicated that the combined use of biochar and zeolite could be more useful for PM composting. Copyright © 2017 Elsevier Ltd. 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

Organic matter variations in transgressive and regressive shales

USGS Publications Warehouse

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

1991-01-01

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

Effect of land use and soil organic matter quality on the structure and function of microbial communities in pastoral soils: Implications for disease suppression

PubMed Central

O’Callaghan, Maureen; Condron, Leo M.; Kowalchuk, George A.; Van Nostrand, Joy D.; Zhou, Jizhong; Wakelin, Steven A.

2018-01-01

Cropping soils vary in extent of natural suppression of soil-borne plant diseases. However, it is unknown whether similar variation occurs across pastoral agricultural systems. We examined soil microbial community properties known to be associated with disease suppression across 50 pastoral fields varying in management intensity. The composition and abundance of the disease-suppressive community were assessed from both taxonomic and functional perspectives. Pseudomonas bacteria were selected as a general taxonomic indicator of disease suppressive potential, while genes associated with the biosynthesis of a suite of secondary metabolites provided functional markers (GeoChip 5.0 microarray analysis). The composition of both the Pseudomonas communities and disease suppressive functional genes were responsive to land use. Underlying soil properties explained 37% of the variation in Pseudomonas community structure and up to 61% of the variation in the abundance of disease suppressive functional genes. Notably, measures of soil organic matter quality, C:P ratio, and aromaticity of the dissolved organic matter content (carbon recalcitrance), influenced both the taxonomic and functional disease suppressive potential of the pasture soils. Our results suggest that key components of the soil microbial community may be managed on-farm to enhance disease suppression and plant productivity. PMID:29734390

Effect of land use and soil organic matter quality on the structure and function of microbial communities in pastoral soils: Implications for disease suppression.

PubMed

Dignam, Bryony E A; O'Callaghan, Maureen; Condron, Leo M; Kowalchuk, George A; Van Nostrand, Joy D; Zhou, Jizhong; Wakelin, Steven A

2018-01-01

Cropping soils vary in extent of natural suppression of soil-borne plant diseases. However, it is unknown whether similar variation occurs across pastoral agricultural systems. We examined soil microbial community properties known to be associated with disease suppression across 50 pastoral fields varying in management intensity. The composition and abundance of the disease-suppressive community were assessed from both taxonomic and functional perspectives. Pseudomonas bacteria were selected as a general taxonomic indicator of disease suppressive potential, while genes associated with the biosynthesis of a suite of secondary metabolites provided functional markers (GeoChip 5.0 microarray analysis). The composition of both the Pseudomonas communities and disease suppressive functional genes were responsive to land use. Underlying soil properties explained 37% of the variation in Pseudomonas community structure and up to 61% of the variation in the abundance of disease suppressive functional genes. Notably, measures of soil organic matter quality, C:P ratio, and aromaticity of the dissolved organic matter content (carbon recalcitrance), influenced both the taxonomic and functional disease suppressive potential of the pasture soils. Our results suggest that key components of the soil microbial community may be managed on-farm to enhance disease suppression and plant productivity.

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

Spectral band selection for classification of soil organic matter content

NASA Technical Reports Server (NTRS)

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

1989-01-01

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

Microbiological Insights of the Cycling of Chloroperoxidase-Reacted Organic Matter

NASA Astrophysics Data System (ADS)

Krzmarzick, M. J.; Boothe, M.; Lim, M. L.; Wang, X.; Brooks, M.

2016-12-01

Chloroperoxidase (CPO) enzymes from fungi are one mechanism in which organic matter is halogenated in terrestrial soils. In microcosm experiments, 17 groups of bacteria were found to substantially become enriched upon CPO-reacted organic matter amendment (CPO-OM). Though some enriched groups were organohalide-respiring bacteria, most were not related to any cultured isolates of bacteria and were either loosely linked to organohalide-degrading cultures or not at all. The large diversity of uncultured bacteria that is enriched from this substrate raises new questions regarding the pathways and mechanisms of the turnover of natural organochlorides. Upon changes in organic matter source material, salinity, temperature, and fermentable substrate, large changes in the CPO-OM enrichment culture occurred due to salinity, temperature, and fermentable substrate, though organic matter source material had a minimal effect. Thus, changes in geophysical conditions, not organic matter (pine forest vs oak forest), dominate the selection of bacteria implicated in the turnover of natural organochlorides. In related experiments, the CPO-OM enrichment culture expresses increased activity towards the dechlorination of chlorinated ethenes, indicating a direct connection between natural organochloride turnover and anthropogenic organochloride degradation and bioremediation, and could partly explain the heterogeneity of natural bioremediation potential at contaminated sites.

Assessing Transformations of Algal Organic Matter in the Long-Term: Impacts of Humification-Like Processes

PubMed Central

Leloup, Maud; Pallier, Virginie; Nicolau, Rudy; Feuillade-Cathalifaud, Geneviève

2015-01-01

Algae and cyanobacteria are important contributors to the natural organic matter (NOM) of eutrophic water resources. The objective of this work is to increase knowledge on the modifications of algal organic matter (AOM) properties in the long term to anticipate blooms footprint in such aquatic environments. The production of AOM from an alga (Euglena gracilis) and a cyanobacteria (Microcystis aeruginosa) was followed up and characterized during the stationary phase and after one year and four months of cultivation, in batch experiments. Specific UV absorbance (SUVA) index, organic matter fractionation according to hydrophobicity and apparent molecular weight were combined to assess the evolution of AOM. A comparison between humic substances (HS) mainly derived from allochthonous origins and AOM characteristics was performed to hypothesize impacts of AOM transformation processes on the water quality of eutrophic water resources. Each AOM fraction underwent a specific evolution pattern, depending on its composition. Impacts of humification-like processes were predominant over release of biopolymers due to cells decay and led to an increase in the hydrophobic compounds part and molecular weights over time. However, the hydrophilic fraction remained the major fraction whatever the growth stage. Organic compounds generated by maturation of these precursors corresponded to large and aliphatic structures. PMID:26251898

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

NASA Astrophysics Data System (ADS)

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

2010-12-01

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

Organic matter and heavy metals content modeling in sewage sludge treated with reed bed system

NASA Astrophysics Data System (ADS)

Boruszko, Dariusz; Dąbrowski, Wojciech; Malinowski, Paweł

2017-11-01

The long process of sludge stabilization (7-15 years) remarkably reduces the organic matter content and causes the process of sludge humifaction. This paper presents the results of using low-cost methods of sludge treatment in the wastewater treatment plant located in Zambrow, Podlaskie Province. The results of studies on the organic matter and heavy metals content in sewage sludge after treatment in a reed bed system are presented. The aim of the research was to evaluate and model organic matter and heavy metals concentrations during sewage stabilization in reed bed lagoons. The lowest concentration, below 1.3 mg/kg DM of the examined seven heavy metals was mercury (Hg). The highest concentration, exceeding 1300 mg/kg DM was zinc (Zn). The obtained results for the heavy metals in sewage sludge from the reed bed lagoons in Zambrow show that the average content of the analyzed heavy metals is approximately 1620 mg/kg DM. The results of the study demonstrate a high efficiency of low-cost methods used in Zambrów WWTP in terms of the quality of the processed sludge. Sewage sludge from the lowest layer of the reed lagoon (12-14 years of dewatering and transformation) is characterized by the lowest organic matter and heavy metals content. The higher a sediment layer lies, i.e. the shorter the time of processing, the higher is the heavy metals content. This indicates a great role of reeds in the accumulation of these compounds.

Mercury and Dissolved Organic Matter Dynamics During Snowmelt in the Upper Provo River, Utah, USA

NASA Astrophysics Data System (ADS)

Packer, B. N.; Carling, G. T.; Nelson, S.; Aanderud, Z.; Shepherd Barkdull, N.; Gabor, R. S.

2017-12-01

Mercury (Hg) is deposited to mountains by atmospheric deposition and mobilized during snowmelt runoff, leading to Hg contamination in otherwise pristine watersheds. Mercury is typically transported with dissolved organic matter (DOM) from soils to streams and lakes. This study focused on Hg and DOM dynamics in the snowmelt-dominated upper Provo River watershed, northern Utah, USA. We sampled Hg, dissolved organic carbon (DOC) concentrations, and DOM fluorescence in river water, snowpack, and ephemeral streams over four years from 2014-2017 to investigate Hg transport mechanisms. During the snowmelt season (April through June), Hg concentrations typically increased from 1 to 8 ng/L showing a strong positive correlation with DOC. The dissolved Hg fraction was dominant in the river, averaging 75% of total Hg concentrations, suggesting that DOC is more important for transport than suspended particulate matter. Ephemeral channels, which represent shallow flow paths with strong interactions with soils, had the highest Hg (>10 ng/L) and DOC (>10 mg/L) concentrations, suggesting a soil water source of Hg and organic matter. Fluorescence spectroscopy results showed important changes in DOM type and quality during the snowmelt season and the soil water flow paths are activated. Changes in DOM characteristics during snowmelt improve the understanding of Hg dynamics with organic matter and elucidate transport pathways from the soil surface, ephemeral channels and groundwater to the Provo River. This study has implications for understanding Hg sources and transport mechanisms in mountain watersheds.

Fluorescence characteristics and biodegradability of dissolved organic matter in forest and wetland soils from coastal temperate watersheds in southeast Alaska

Treesearch

Jason B. Fellman; David V. D' Amore; Eran Hood; Richard D. Boone

2008-01-01

Understanding how the concentration and chemical quality of dissolved organic matter (DOM) varies in soils is critical because DOM influences an array of biological, chemical, and physical processes. We used PARAFAC modeling of excitation-emission fluorescence spectroscopy, specific UV absorbance (SUVA254) and biodegradable dissolved organic...

Quality of soluble organic C, N, and P produced by different types and species of litter: root litter versus leaf litter

USDA-ARS?s Scientific Manuscript database

In forested ecosystems, the quality of dissolved organic matter (DOM) produced by freshly senesced litter may differ by litter type and species, and these differences may influence the amount of DOM that is respired versus that which may either contribute to soil organic matter accumulation or be le...

On Examining the Transport and Transformation of Dissolved Organic Matter in The Albemarle-Pamlico Estuarine System, NC USA

NASA Astrophysics Data System (ADS)

Miller, R. L.; Buonassissi, C. J.; Brown, M. M.; Reed, R. E.

2016-02-01

The Albemarle-Pamlico Estuarine System (APES) in eastern North Carolina is the second largest estuary and largest lagoonal system in the United States. Variation in the amount of dissolved organic matter (DOM) delivered to the APES was examined for the Neuse and Tar/Pamlico River estuaries, two major components of the APES, using absorption spectra of Chromophoric Dissolved Organic Matter (CDOM). The quality of DOM and transformations that occur during down estuary transport were assessed using the spectral parameters SUVA254, SUVA350, S275-295, S350-400, and Sr calculated from CDOM spectra. We present results from several field campaigns that obtained surface samples during different stages of river discharge, including samples taken following Hurricane Irene (2011), and discuss the utility of using these newer optical indices of DOM quality for examining DOM dynamics in river dominated coastal waters.

Impact of organic matter source and quality on living benthic foraminiferal distribution on a river-dominated continental margin: A study of the Portuguese margin

NASA Astrophysics Data System (ADS)

Dessandier, Pierre-Antoine; Bonnin, Jérôme; Kim, Jung-Hyun; Bichon, Sabrina; Deflandre, Bruno; Grémare, Antoine; Sinninghe Damsté, Jaap S.

2016-06-01

Living (rose Bengal stained) benthic foraminifera were investigated on surface sediments from 23 stations from the river-dominated northwestern Portuguese margin. Samples were collected in March 2011, following the period of the maximum rainfall over the Iberian Peninsula, between 20 and 2000 m water depth along five cross-margin transects. Four of them are located off the Douro, Mondego, Tagus, and Sado Rivers and one off the Estremadura coast. The major objectives of this study are (1) to assess the impact of organic matter of various origin and quality on the benthic foraminifera and (2) to investigate the spatial differences of faunal distribution from coastal waters to the deep sea under river influences. To do this, sedimentological and biogeochemical characteristics of the sediments were identified by measuring grain size, oxygen penetration depth, total organic carbon (TOC) content, stable carbon isotopic composition of TOC (δ13CTOC) and concentration of pigments and amino acids. Based on the principal component and cluster analyses of the environmental data, three major geographical groups are identified: (1) deep stations, (2) coastal and middle slope stations, and (3) shelf stations under river influence. At the deepest stations, species are associated with high organic matter (OM) quantity but low OM quality, where Uvigerina mediterranea, Hoeglundina elegans, and agglutinated species such as Reophax scorpiurus or Bigenerina nodosaria are dominant. All stations off the Sado River, which is the most affected area by the anthropogenic influence, are also characterized by high quantity but low quality of OM with the minimum faunal density and diversity within the study area. Middle slope stations are associated with low OM content and coarse sediments (Q50) with the predominance of N. scaphum. Shallow shelf stations close to the Douro and Tagus River mouths show a dominance of taxa (e.g., Ammonia beccarii, Bulimina aculeata, Eggerelloides scaber, Nonion

Evolution of soil organic matter changes using pyrolysis and metabolic indices: a comparison between organic and mineral fertilization.

PubMed

Marinari, S; Masciandaro, G; Ceccanti, B; Grego, S

2007-09-01

The aim of this study was to evaluate chemical and biochemical changes of organic matter in fertilized (ammonium nitrate) and amended (vermicompost and manure) soils using pyrolysis and metabolic indices. The metabolic potential [dehydrogenase (DH-ase)/water soluble organic carbon (WSOC)], the metabolic quotient (qCO2) and the microbial quotient (Cmic:Corg) were calculated as indices of soil organic matter evolution. Pyrolysis-gas chromatography (Py-GC) was used to study structural changes in the organic matter. Carbon forms and microbial biomass have been measured by dichromate oxidation and fumigation-extraction methods, respectively. Dehydrogenase activity has been tested using INT (p-Iodonitrotetrazolium violet) as substrate. The results showed that organic amendment increased soil microbial biomass and its activity which were strictly related to pyrolytic mineralization and humification indices (N/O, B/E3). Mineral fertilization caused a greater alteration of native soil organic matter than the organic amendments, in that a high release of WSOC and relatively large amounts of aliphatic pyrolytic products, were observed. Therefore, the pyrolysis and metabolic indices provided similar and complementary information on soil organic matter changes after mineral and organic fertilization.

Changes in postharvest quality of Swiss chard grown using 3 organic preharvest treatments.

PubMed

Daiss, N; Lobo, M G; Gonzalez, M

2008-08-01

Using storage conditions recommended for conventional chard (4 degrees C, 90% RH and 7 d), the chard treated with some organic preharvest treatments [effective microorganisms, a fermented mixture of effective microorganisms with organic matter (EM-Bokashi + EM), and an auxiliary soil product] lost considerable water (> 2%) and weight (> 25%). These results indicate that organic methods tested produce a vegetable that can not sustain its quality when commercialized through the conventional supply chain. Nevertheless, respiration, color, pH, and titratable acidity practically remained constant during conservation. Ascorbic acid content was constant in chard treated with the different preharvest treatments and collected at 8 wk after sowing (normal harvest). However, the ascorbic acid content of the control chard decreased 60% after 7 d of storage. This vitamin diminished (35%) in chard collected after 19 wk after sowing (late harvest) during the postharvest conservation. The greatest difference in chard quality was registered between sampling dates since chard collected during the late harvest had higher levels of dry matter, sugars, acids, proteins, and ascorbic acid than chard collected during the normal harvest.

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

NASA Astrophysics Data System (ADS)

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

2014-12-01

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

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

Qualitative changes of riverine dissolved organic matter at low salinities due to flocculation

NASA Astrophysics Data System (ADS)

Asmala, Eero; Bowers, David G.; Autio, Riitta; Kaartokallio, Hermanni; Thomas, David N.

2014-10-01

The flocculation of dissolved organic matter (DOM) was studied along transects through three boreal estuaries. Besides the bulk concentration parameters, a suite of DOM quality parameters were investigated, including colored DOM (CDOM), fluorescent DOM, and the molecular weight of DOM as well as associated dissolved iron concentrations. We observed significant deviations from conservative mixing at low salinities (<2) in the estuarine samples of dissolved organic carbon (DOC), UV absorption (a(CDOM254)), and humic-like fluorescence. The maximum deviation from conservative mixing for DOC concentration was -16%, at salinities between 1 and 2. An associated laboratory experiment was conducted where an artificial salinity gradient between 0 and 6 was created. The experiment confirmed the findings from the estuarine transects, since part of the DOC and dissolved iron pools were transformed to particulate fraction (>0.2 µm) and thereby removing them from the dissolved phase. We also measured flocculation of CDOM, especially in the UV region of the absorption spectrum. Protein-like fluorescence of DOM decreased, while humic-like fluorescence increased because of salt-induced flocculation. Additionally, there was a decrease in molecular weight of DOM. Consequently, the quantity and quality of the remaining DOM pool was significantly changed after influenced to flocculation. Based on these results, we constructed a mechanistic, two-component flocculation model. Our findings underline the importance of the coastal filter, where riverine organic matter is flocculated and exported to the sediments.

A Prototype Sensor for In Situ Sensing of Fine Particulate Matter and Volatile Organic Compounds

PubMed Central

Ng, Chee-Loon; Kai, Fuu-Ming; Tee, Ming-Hui; Tan, Nicholas; Hemond, Harold F.

2018-01-01

Air pollution exposure causes seven million deaths per year, according to the World Health Organization. Possessing knowledge of air quality and sources of air pollution is crucial for managing air pollution and providing early warning so that a swift counteractive response can be carried out. An optical prototype sensor (AtmOptic) capable of scattering and absorbance measurements has been developed to target in situ sensing of fine particulate matter (PM2.5) and volatile organic compounds (VOCs). For particulate matter testing, a test chamber was constructed and the emission of PM2.5 from incense burning inside the chamber was measured using the AtmOptic. The weight of PM2.5 particles was collected and measured with a filter to determine their concentration and the sensor signal-to-concentration correlation. The results of the AtmOptic were also compared and found to trend well with the Dylos DC 1100 Pro air quality monitor. The absorbance spectrum of VOCs emitted from various laboratory chemicals and household products as well as a two chemical mixtures were recorded. The quantification was demonstrated, using toluene as an example, by calibrating the AtmOptic with compressed gas standards containing VOCs at different concentrations. The results demonstrated the sensor capabilities in measuring PM2.5 and volatile organic compounds. PMID:29346281

A Prototype Sensor for In Situ Sensing of Fine Particulate Matter and Volatile Organic Compounds.

PubMed

Ng, Chee-Loon; Kai, Fuu-Ming; Tee, Ming-Hui; Tan, Nicholas; Hemond, Harold F

2018-01-18

Air pollution exposure causes seven million deaths per year, according to the World Health Organization. Possessing knowledge of air quality and sources of air pollution is crucial for managing air pollution and providing early warning so that a swift counteractive response can be carried out. An optical prototype sensor (AtmOptic) capable of scattering and absorbance measurements has been developed to target in situ sensing of fine particulate matter (PM2.5) and volatile organic compounds (VOCs). For particulate matter testing, a test chamber was constructed and the emission of PM2.5 from incense burning inside the chamber was measured using the AtmOptic. The weight of PM2.5 particles was collected and measured with a filter to determine their concentration and the sensor signal-to-concentration correlation. The results of the AtmOptic were also compared and found to trend well with the Dylos DC 1100 Pro air quality monitor. The absorbance spectrum of VOCs emitted from various laboratory chemicals and household products as well as a two chemical mixtures were recorded. The quantification was demonstrated, using toluene as an example, by calibrating the AtmOptic with compressed gas standards containing VOCs at different concentrations. The results demonstrated the sensor capabilities in measuring PM2.5 and volatile organic compounds.

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...

Soil Organic Matter Content Effects on Dermal Pesticide ...

EPA Pesticide Factsheets

Agricultural landscapes serve as active amphibian breeding grounds despite their seemingly poor habitat value. Activity of adults and dispersal of metamorphs to and from agricultural ponds occurs in most species from spring through late summer or early fall, a time that coincides with pesticide applications on farm fields and crops. In terrestrial landscapes, dermal contact with contaminated soil and plant matter may lead to bioconcentration as well as lethal and sublethal effects in amphibians.Although the physiological structure of the amphibian dermis may facilitate pesticide uptake, soil properties may ultimately dictate bioavailability of pesticides in terrestrial habitats. The organic matter fraction of soil readily binds to pesticides, potentially decreasing the availability of pesticides adhering to biological matter. Soil partition coefficient organic carbon content and soil-specific Koc values may be important to indicating pesticide bioavailability and potential bioconcentration in amphibians. Our study was designed to evaluate dermal uptake of five pesticide active ingredients on either high or low organic matter soils. We predicted that amphibian body burdens would be a function of soil carbon content or Koc. with greater bioconcentration in individuals exposed to pesticides on sa

Bacterial biomarkers thermally released from dissolved organic matter

USGS Publications Warehouse

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

2006-01-01

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

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.

Inhibition of Alkaline Flocculation by Algal Organic Matter for Chlorella vulgaris

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

Vandamme, Dries; Beuckels, Annelies; Vadelius, Eric

2016-01-01

Alkaline flocculation is a promising strategy for the concentration of microalgae for bulk biomass production. However, previous studies have shown that biological changes during the cultivation negatively affect flocculation efficiency. The influence of changes in cell properties and in the quality and composition of algal organic matter (AOM) were studied using Chlorella vulgaris as a model species. In batch cultivation, flocculation was increasingly inhibited over time and mainly influenced by changes in medium composition, rather than biological changes at the cell surface. Total carbohydrate content of the organic matter fraction sized bigger than 3 kDa increased over time and thismore » fraction was shown to be mainly responsible for the inhibition of alkaline flocculation. The monosaccharide identification of this fraction mainly showed the presence of neutral and anionic monosaccharides. An addition of 30–50 mg L -1 alginic acid, as a model for anionic carbohydrate polymers containing uronic acids, resulted in a complete inhibition of flocculation. Furthermore, these results suggest that inhibition of alkaline flocculation was caused by interaction of anionic polysaccharides leading to an increased flocculant demand over time.« less

Development and application of a soil organic matter-based soil quality index in mineralized terrane of the Western US

USGS Publications Warehouse

Blecker, S.W.; Stillings, Lisa L.; Amacher, M.C.; Ippolito, J.A.; DeCrappeo, N.M.

2013-01-01

Soil quality indices provide a means of distilling large amounts of data into a single metric that evaluates the soil’s ability to carry out key ecosystem functions. Primarily developed in agroecosytems, then forested ecosystems, an index using the relation between soil organic matter and other key soil properties in more semi-arid systems of the Western US impacted by different geologic mineralization was developed. Three different sites in two different mineralization types, acid sulfate and Cu/Mo porphyry in California and Nevada, were studied. Soil samples were collected from undisturbed soils in both mineralized and nearby unmineralized terrane as well as waste rock and tailings. Eight different microbial parameters (carbon substrate utilization, microbial biomass-C, mineralized-C, mineralized-N and enzyme activities of acid phosphatase, alkaline phosphatase, arylsulfatase, and fluorescein diacetate) along with a number of physicochemical parameters were measured. Multiple linear regression models between these parameters and both total organic carbon and total nitrogen were developed, using the ratio of predicted to measured values as the soil quality index. In most instances, pooling unmineralized and mineralized soil data within a given study site resulted in lower model correlations. Enzyme activity was a consistent explanatory variable in the models across the study sites. Though similar indicators were significant in models across different mineralization types, pooling data across sites inhibited model differentiation of undisturbed and disturbed sites. This procedure could be used to monitor recovery of disturbed systems in mineralized terrane and help link scientific and management disciplines.

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.

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

NASA Astrophysics Data System (ADS)

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

2017-12-01

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

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.

Soil Water Content Sensor Response to Organic Matter Content under Laboratory Conditions

PubMed Central

Fares, Ali; Awal, Ripendra; Bayabil, Haimanote K.

2016-01-01

Studies show that the performance of soil water content monitoring (SWCM) sensors is affected by soil physical and chemical properties. However, the effect of organic matter on SWCM sensor responses remains less understood. Therefore, the objectives of this study are to (i) assess the effect of organic matter on the accuracy and precision of SWCM sensors using a commercially available soil water content monitoring sensor; and (ii) account for the organic matter effect on the sensor’s accuracy. Sand columns with seven rates of oven-dried sawdust (2%, 4%, 6%, 8%, 10%, 12% and 18% v/v, used as an organic matter amendment), thoroughly mixed with quartz sand, and a control without sawdust were prepared by packing quartz sand in two-liter glass containers. Sand was purposely chosen because of the absence of any organic matter or salinity, and also because sand has a relatively low cation exchange capacity that will not interfere with the treatment effect of the current work. Sensor readings (raw counts) were monitored at seven water content levels (0, 0.02, 0.04, 0.08, 0.12, 0.18, 0.24, and 0.30 cm3 cm−3) by uniformly adding the corresponding volumes of deionized water in addition to the oven-dry one. Sensor readings were significantly (p < 0.05) affected by the organic matter level and water content. Sensor readings were strongly correlated with the organic matter level (R2 = 0.92). In addition, the default calibration equation underestimated the water content readings at the lower water content range (<0.05 cm3 cm−3), while it overestimated the water content at the higher water content range (>0.05 cm3 cm−3). A new polynomial calibration equation that uses raw count and organic matter content as covariates improved the accuracy of the sensor (RMSE = 0.01 cm3 cm−3). Overall, findings of this study highlight the need to account for the effect of soil organic matter content to improve the accuracy and precision of the tested sensor under different soils and

Soil Water Content Sensor Response to Organic Matter Content under Laboratory Conditions.

PubMed

Fares, Ali; Awal, Ripendra; Bayabil, Haimanote K

2016-08-05

Studies show that the performance of soil water content monitoring (SWCM) sensors is affected by soil physical and chemical properties. However, the effect of organic matter on SWCM sensor responses remains less understood. Therefore, the objectives of this study are to (i) assess the effect of organic matter on the accuracy and precision of SWCM sensors using a commercially available soil water content monitoring sensor; and (ii) account for the organic matter effect on the sensor's accuracy. Sand columns with seven rates of oven-dried sawdust (2%, 4%, 6%, 8%, 10%, 12% and 18% v/v, used as an organic matter amendment), thoroughly mixed with quartz sand, and a control without sawdust were prepared by packing quartz sand in two-liter glass containers. Sand was purposely chosen because of the absence of any organic matter or salinity, and also because sand has a relatively low cation exchange capacity that will not interfere with the treatment effect of the current work. Sensor readings (raw counts) were monitored at seven water content levels (0, 0.02, 0.04, 0.08, 0.12, 0.18, 0.24, and 0.30 cm³ cm(-3)) by uniformly adding the corresponding volumes of deionized water in addition to the oven-dry one. Sensor readings were significantly (p < 0.05) affected by the organic matter level and water content. Sensor readings were strongly correlated with the organic matter level (R² = 0.92). In addition, the default calibration equation underestimated the water content readings at the lower water content range (<0.05 cm³ cm(-3)), while it overestimated the water content at the higher water content range (>0.05 cm³ cm(-3)). A new polynomial calibration equation that uses raw count and organic matter content as covariates improved the accuracy of the sensor (RMSE = 0.01 cm³ cm(-3)). Overall, findings of this study highlight the need to account for the effect of soil organic matter content to improve the accuracy and precision of the tested sensor under different soils and

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.

Insights into the nature of cometary organic matter from terrestrial analogues

NASA Astrophysics Data System (ADS)

Court, Richard W.; Sephton, Mark A.

2012-04-01

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

Dynamics of organic matter and microbial populations in amended soil: a multidisciplinary approach

NASA Astrophysics Data System (ADS)

Gigliotti, Giovanni; Pezzolla, Daniela; Zadra, Claudia; Albertini, Emidio; Marconi, Gianpiero; Turchetti, Benedetta; Buzzini, Pietro

2013-04-01

The application of organic amendments to soils, such as pig slurry, sewage sludge and compost is considered a tool for improving soil fertility and enhancing C stock. The addition of these different organic materials allows a good supply of nutrients for plants but also contributes to C sequestration, affects the microbial activity and the transformation of soil organic matter (SOM). Moreover, the addition of organic amendment has gained importance as a source of greenhouse gas (GHG) emissions and then as a cause of the "Global Warming". Therefore, it is important to investigate the factors controlling the SOM mineralization in order to improve soil C sequestration and decreasing at the same time the GHG emissions. The quality of organic matter added to the soil will play an important role in these dynamics, affecting the microbial activity and the changes in microbial community structure. A laboratory, multidisciplinary experiment was carried out to test the effect of the amendment by anaerobic digested livestock-derived organic materials on labile organic matter evolution and on dynamics of microbial population, this latter both in terms of consistence of microbial biomass, as well as in terms of microbial biodiversity. Different approaches were used to study the microbial community structure: chemical (CO2 fluxes, WEOC, C-biomass, PLFA), microbiological (microbial enumeration) and molecular (DNA extraction and Roche 454, Next Generation Sequencing, NGS). The application of fresh digestate, derived from the anaerobic treatment of animal wastes, affected the short-term dynamics of microbial community, as reflected by the increase of CO2 emissions immediately after the amendment compared to the control soil. This is probably due to the addition of easily available C added with the digestate, demonstrating that this organic material was only partially stabilized by the anaerobic process. In fact, the digestate contained a high amounts of available C, which led to

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

Pre-biotic organic matter from comets and asteroids

NASA Technical Reports Server (NTRS)

Anders, Edward

1989-01-01

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

Mapping forest soil organic matter on New Jersey's coastal plain

Treesearch

Brian J. Clough; Edwin J. Green; Richard B. Lathrop

2012-01-01

Managing forest soil organic matter (SOM) stocks is a vital strategy for reducing the impact of anthropogenic carbon dioxide emissions. However, the SOM pool is highly variable, and developing accurate estimates to guide management decisions has remained a difficult task. We present the results of a spatial model designed to map soil organic matter for all forested...

Toward a Simple Framework for Understanding the Influence of Litter Quality on Vertical and Horizontal Patterns of Soil Organic Matter Pools

NASA Astrophysics Data System (ADS)

Craig, M.; Phillips, R.

2016-12-01

Decades of research have revealed that plant litter quality fundamentally influences soil organic matter (SOM) properties. Yet we lack the predictive frameworks necessary to up-scale our understanding of these dynamics in biodiverse systems. Given that ectomycorrhizal (EM) and arbuscular mycorrhizal (AM) plants are thought to differ in their litter quality, we ask whether this dichotomy represents a framework for understanding litter quality effects on SOM in temperate forests. To do this, we sampled soils from 250 spatially referenced locations within a 25-Ha plot where 28,000 trees had been georeferenced, and analyzed spatial patterns of plant and SOM properties. We then examined the extent to which the dominance of AM- versus EM-trees relates to 1) the quality of litter inputs to forest soils and 2) the horizontal and vertical distribution of SOM fractions. We found that leaf litters produced by EM-associated trees were generally of lower quality, having a lower concentration of soluble compounds and higher C:N. Concomitant with this, we observed higher soil C:N under EM trees. Interestingly, this reflected greater N storage in AM-dominated soils rather than greater C storage in EM-dominated soils. These patterns were driven by the storage of SOM in N-rich fractions in AM-dominated soils. Specifically, trees with high litter quality were associated with greater amounts of deep and mineral-associated SOM; pools that are generally considered stable. Our results support the recent contention that high-quality plant inputs should lead to the formation of stable SOM and suggest that the AM-EM framework may provide a way forward for representing litter quality effects on SOM in earth system models.

Effects of ozonation pretreatment on natural organic matter and wastewater derived organic matter - Possible implications on the formation of ozonation by-products.

PubMed

Papageorgiou, Alexandros; Stylianou, Stylianos K; Kaffes, Pavlos; Zouboulis, Anastasios I; Voutsa, Dimitra

2017-03-01

The aim of this study was to investigate possible implications of natural and wastewater derived organic matter in river water that is subsequently used following treatment for drinking purposes. River water was subjected to lab-scale ozonation experiments under different ozone doses (0.1, 0.4, 0.8, 1.0 and 2.0 mgO 3 /mgC) and contact times (1, 3, 5, 8 and 10 min). Mixtures of river water with humic acids or wastewaters (sewage wastewater and secondary effluents) at different proportions were also ozonated. Dissolved organic carbon and biodegradable dissolved organic carbon concentrations as well as spectroscopic characteristics (UV absorbance and fluorescence intensities) of different types of dissolved organic matter and possible changes due to the ozonation treatment are presented. River water, humic substances and wastewater exhibited distinct spectroscopic characteristics that could serve for pollution source tracing. Wastewater impacted surface water results in higher formation of carbonyl compounds. However, the formation yield (μg/mgC) of wastewaters was lower than that of surface water possibly due to different composition of wastewater derived organic matter and the presence of scavengers, which may limit the oxidative efficiency of ozone. Copyright © 2016 Elsevier Ltd. All rights reserved.

Quantities and qualities of physical and chemical fractions of soil organic matter under a rye cover crop

USDA-ARS?s Scientific Manuscript database

To detect the effects of a rye cover crop on labile soil carbon, the light fraction, large particulate organic matter (POM), small POM, and two NaOH-extractable humic fractions were extracted from three depths of a corn soil in central Iowa having an overwinter rye cover crop treatment and a contro...

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.

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.

Escherichia coli Behavior in the Presence of Organic Matter Released by Algae Exposed to Water Treatment Chemicals

PubMed Central

Bouteleux, C.; Saby, S.; Tozza, D.; Cavard, J.; Lahoussine, V.; Hartemann, P.; Mathieu, L.

2005-01-01

When exposed to oxidation, algae release dissolved organic matter with significant carbohydrate (52%) and biodegradable (55 to 74%) fractions. This study examined whether algal organic matter (AOM) added in drinking water can compromise water biological stability by supporting bacterial survival. Escherichia coli (1.3 × 105 cells ml−1) was inoculated in sterile dechlorinated tap water supplemented with various qualities of organic substrate, such as the organic matter coming from chlorinated algae, ozonated algae, and acetate (model molecule) to add 0.2 ± 0.1 mg of biodegradable dissolved organic carbon (BDOC) liter−1. Despite equivalent levels of BDOC, E. coli behavior depended on the source of the added organic matter. The addition of AOM from chlorinated algae led to an E. coli growth equivalent to that in nonsupplemented tap water; the addition of AOM from ozonated algae allowed a 4- to 12-fold increase in E. coli proliferation compared to nonsupplemented tap water. Under our experimental conditions, 0.1 mg of algal BDOC was sufficient to support E. coli growth, whereas the 0.7 mg of BDOC liter−1 initially present in drinking water and an additional 0.2 mg of BDOC acetate liter−1 were not sufficient. Better maintenance of E. coli cultivability was also observed when AOM was added; cultivability was even increased after addition of AOM from ozonated algae. AOM, likely to be present in treatment plants during algal blooms, and thus potentially in the treated water may compromise water biological stability. PMID:15691924

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.

Interstellar and Solar System Organic Matter Preserved in Interplanetary Dust

NASA Technical Reports Server (NTRS)

Messenger, Scott; Nakamura-Messenger, Keiko

2015-01-01

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

Caracterisation of anthropogenic contribution to the coastal fluorescent organic matter

NASA Astrophysics Data System (ADS)

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

2015-04-01

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

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

NASA Astrophysics Data System (ADS)

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

2014-05-01

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

Production of Dissolved Organic Matter During Doliolid Feeding

NASA Astrophysics Data System (ADS)

Castellane, N. J.; Paffenhofer, G. A.; Stubbins, A.

2016-02-01

The biological carbon pump (BCP) draws carbon dioxide out of the atmosphere and buries it at the seafloor. The efficiency of the BCP is determined in part by the sinking rates of particulate organic carbon (POC) from ocean surface waters. Zooplankton can package POC into fecal pellets with higher sinking rates than their food source (e.g. phytoplankton), increasing the efficiency of the BCP. However, dissolved organic carbon (DOC) is also produced as zooplankton ingest and egest food, reducing the efficiency of BCP. The pelagic tunicate Dolioletta gegenbauri (doliolid) is a gelatinous zooplankton found at high concentrations in shelf waters, including our study site: the South Atlantic Bight. Doliolids are efficient grazers capable of stripping large quantities of phytoplankton from the water column. To determine the balance between pellet formation and DOC production during feeding, doliolids (6-7 mm gonozooids) were placed in natural seawater amended with a live phytoplankton food source and incubated on a plankton wheel. Dissolved organic matter (DOM) released directly to the water as well as the water soluble fraction of pellet organic matter were quantified and optically characterized. Colored dissolved organic matter (CDOM) absorbance and fluorescence spectra revealed that doliolid feeding produces DOM with optical properties that are commonly indicative of newly produced, highly biolabile DOM of microbial origin. Based upon these optical characteristics, doliolid-produced DOM is expected to be highly bio-labile in the environment and therefore rapidly degraded by surface ocean microbes shunting phytoplankton-derived organic carbon out of the BCP and back to dissolved inorganic carbon.

Temperature response of litter and soil organic matter decomposition is determined by chemical composition of organic material.

PubMed

Erhagen, Björn; Öquist, Mats; Sparrman, Tobias; Haei, Mahsa; Ilstedt, Ulrik; Hedenström, Mattias; Schleucher, Jürgen; Nilsson, Mats B

2013-12-01

The global soil carbon pool is approximately three times larger than the contemporary atmospheric pool, therefore even minor changes to its integrity may have major implications for atmospheric CO2 concentrations. While theory predicts that the chemical composition of organic matter should constitute a master control on the temperature response of its decomposition, this relationship has not yet been fully demonstrated. We used laboratory incubations of forest soil organic matter (SOM) and fresh litter material together with NMR spectroscopy to make this connection between organic chemical composition and temperature sensitivity of decomposition. Temperature response of decomposition in both fresh litter and SOM was directly related to the chemical composition of the constituent organic matter, explaining 90% and 70% of the variance in Q10 in litter and SOM, respectively. The Q10 of litter decreased with increasing proportions of aromatic and O-aromatic compounds, and increased with increased contents of alkyl- and O-alkyl carbons. In contrast, in SOM, decomposition was affected only by carbonyl compounds. To reveal why a certain group of organic chemical compounds affected the temperature sensitivity of organic matter decomposition in litter and SOM, a more detailed characterization of the (13) C aromatic region using Heteronuclear Single Quantum Coherence (HSQC) was conducted. The results revealed considerable differences in the aromatic region between litter and SOM. This suggests that the correlation between chemical composition of organic matter and the temperature response of decomposition differed between litter and SOM. The temperature response of soil decomposition processes can thus be described by the chemical composition of its constituent organic matter, this paves the way for improved ecosystem modeling of biosphere feedbacks under a changing climate. © 2013 John Wiley & Sons Ltd.

Fruit and Soil Quality of Organic and Conventional Strawberry Agroecosystems

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

Reganold, John P.; Andrews, Preston K.; Reeve, Jennifer

2010-01-01

Background: Sale of organic foods is one of the fastest growing market segments within the global food industry. People often buy organic food because they believe organic farms produce more nutritious and better tasting food from healthier soils. Here we tested if there are significant differences in fruit and soil quality from 13 pairs of commercial organic and conventional strawberry agroecosystems in California. Methodology/Principal Findings: At multiple sampling times for two years, we evaluated three varieties of strawberries for mineral elements, shelf life, phytochemical composition, and organoleptic properties. We also analyzed traditional soil properties and soil DNA using microarray technology.more » We found that the organic farms had strawberries with longer shelf life, greater dry matter, and higher antioxidant activity and concentrations of ascorbic acid and phenolic compounds, but lower concentrations of phosphorus and potassium. In one variety, sensory panels judged organic strawberries to be sweeter and have better flavor, overall acceptance, and appearance than their conventional counterparts. We also found the organically farmed soils to have more total carbon and nitrogen, greater microbial biomass and activity, and higher concentrations of micronutrients. Organically farmed soils also exhibited greater numbers of endemic genes and greater functional gene abundance and diversity for several biogeochemical processes, such as nitrogen fixation and pesticide degradation. Conclusions/Significance: Our findings show that the organic strawberry farms produced higher quality fruit and that their higher quality soils may have greater microbial functional capability and resilience to stress. These findings justify additional investigations aimed at detecting and quantifying such effects and their interactions.« less

Particulate organic matter quality influences nitrate retention and denitrification in stream sediments: evidence from a carbon burial experiment

USGS Publications Warehouse

Stelzer, Robert S.; Scott, J. Thad; Bartsch, Lynn; Parr, Thomas B.

2014-01-01

Organic carbon supply is linked to nitrogen transformation in ecosystems. However, the role of organic carbon quality in nitrogen processing is not as well understood. We determined how the quality of particulate organic carbon (POC) influenced nitrogen transformation in stream sediments by burying identical quantities of varying quality POC (northern red oak (Quercus rubra) leaves, red maple (Acer rubrum) leaves, red maple wood) in stream mesocosms and measuring the effects on nitrogen retention and denitrification compared to a control of combusted sand. We also determined how POC quality affected the quantity and quality of dissolved organic carbon (DOC) and dissolved oxygen concentration in groundwater. Nitrate and total dissolved nitrogen (TDN) retention were assessed by comparing solute concentrations and fluxes along groundwater flow paths in the mesocosms. Denitrification was measured by in situ changes in N2 concentrations (using MIMS) and by acetylene block incubations. POC quality was measured by C:N and lignin:N ratios and DOC quality was assessed by fluorescence excitation emission matrix spectroscopy. POC quality had strong effects on nitrogen processing. Leaf treatments had much higher nitrate retention, TDN retention and denitrification rates than the wood and control treatments and red maple leaf burial resulted in higher nitrate and TDN retention rates than burial of red oak leaves. Leaf, but not wood, burial drove pore water to severe hypoxia and leaf treatments had higher DOC production and different DOC chemical composition than the wood and control treatments. We think that POC quality affected nitrogen processing in the sediments by influencing the quantity and quality of DOC and redox conditions. Our results suggest that the type of organic carbon inputs can affect the rates of nitrogen transformation in stream ecosystems.

Granular activated carbon for removal of organic matter and turbidity from secondary wastewater.

PubMed

Hatt, J W; Germain, E; Judd, S J

2013-01-01

A range of commercial granular activated carbon (GAC) media have been assessed as pretreatment technologies for a downstream microfiltration (MF) process. Media were assessed on the basis of reduction in both organic matter and turbidity, since these are known to cause fouling in MF membranes. Isotherm adsorption analysis through jar testing with supplementary column trials revealed a wide variation between the different adsorbent materials with regard to organics removal and adsorption kinetics. Comparison with previous work using powdered activated carbon (PAC) revealed that for organic removal above 60% the use of GAC media incurs a significantly lower carbon usage rate than PAC. All GACs tested achieved a minimum of 80% turbidity removal. This combination of turbidity and organic removal suggests that GAC would be expected to provide a significant reduction in fouling of a downstream MF process with improved product water quality.

Rapid and Accurate Evaluation of the Quality of Commercial Organic Fertilizers Using Near Infrared Spectroscopy

PubMed Central

Wang, Chang; Huang, Chichao; Qian, Jian; Xiao, Jian; Li, Huan; Wen, Yongli; He, Xinhua; Ran, Wei; Shen, Qirong; Yu, Guanghui

2014-01-01

The composting industry has been growing rapidly in China because of a boom in the animal industry. Therefore, a rapid and accurate assessment of the quality of commercial organic fertilizers is of the utmost importance. In this study, a novel technique that combines near infrared (NIR) spectroscopy with partial least squares (PLS) analysis is developed for rapidly and accurately assessing commercial organic fertilizers quality. A total of 104 commercial organic fertilizers were collected from full-scale compost factories in Jiangsu Province, east China. In general, the NIR-PLS technique showed accurate predictions of the total organic matter, water soluble organic nitrogen, pH, and germination index; less accurate results of the moisture, total nitrogen, and electrical conductivity; and the least accurate results for water soluble organic carbon. Our results suggested the combined NIR-PLS technique could be applied as a valuable tool to rapidly and accurately assess the quality of commercial organic fertilizers. PMID:24586313

Rapid and accurate evaluation of the quality of commercial organic fertilizers using near infrared spectroscopy.

PubMed

Wang, Chang; Huang, Chichao; Qian, Jian; Xiao, Jian; Li, Huan; Wen, Yongli; He, Xinhua; Ran, Wei; Shen, Qirong; Yu, Guanghui

2014-01-01

The composting industry has been growing rapidly in China because of a boom in the animal industry. Therefore, a rapid and accurate assessment of the quality of commercial organic fertilizers is of the utmost importance. In this study, a novel technique that combines near infrared (NIR) spectroscopy with partial least squares (PLS) analysis is developed for rapidly and accurately assessing commercial organic fertilizers quality. A total of 104 commercial organic fertilizers were collected from full-scale compost factories in Jiangsu Province, east China. In general, the NIR-PLS technique showed accurate predictions of the total organic matter, water soluble organic nitrogen, pH, and germination index; less accurate results of the moisture, total nitrogen, and electrical conductivity; and the least accurate results for water soluble organic carbon. Our results suggested the combined NIR-PLS technique could be applied as a valuable tool to rapidly and accurately assess the quality of commercial organic fertilizers.

Compositional Characteristics of Dissolved Organic Matter released from the sediment of Han river in Korea.

NASA Astrophysics Data System (ADS)

Oh, H.; Choi, J. H.

2017-12-01

The dissolved organic matter (DOM) has variable characteristics depending on the sources. The DOM of a river is affected by rain water, windborne material, surface and groundwater flow, and sediments. In particular, sediments are sources and sinks of nutrients and pollutants in aquatic ecosystems by supplying large amounts of organic matter. The DOM which absorbs ultraviolet and visible light is called colored dissolved organic matter (CDOM). CDOM is responsible for the optical properties of natural waters in several biogeochemical and photochemical processes and absorbs UV-A (315-400 nm) and UV-B (280-315), which are harmful to aquatic ecosystems (Helms et al., 2008). In this study, we investigated the quantity and quality of DOM and CDOM released from the sediments of Han river which was impacted by anthropogenic activities and hydrologic alternation of 4 Major River Restoration Project. The target area of this study is Gangchenbo (GC), Yeojubo (YJ), and Ipobo(IP) of the Han River, Korea. Sediments and water samples were taken on July and August of 2016 and were incubated at 20° up to 7 days. Absorbance was measured with UV-visible spectrophotometer (Libra S32 PC, Biochrom). Fluorescence intensity determined with Fluorescence EEMs (F-7000, Hitachi). Absorbance and fluorescence intensity were used to calculate Specific Ultraviolet Absorbance (SUVA254), Humification index (HIX), Biological index (BIX), Spectral slope (SR) and component analysis. The DOC concentration increased after 3 days of incubation. According to the SUVA254 analysis, the microbial activity is highest in the initial overlying water of IP. HIX have range of 1.35-4.08, and decrease poly aromatic structures of organic matter during incubation. From the results of the BIX, autochthonous organic matter was released from the sediments. In all sites, Humic-like DOM, Microbial humic-like DOM and Protein-like DOM increased significantly between Day 0 and 3(except Humic-like, Microbial humic-like DOM in

Building Systemwide Improvement Capability: Does an Organization's Strategy for Quality Improvement Matter?

PubMed

Babich, Lauren P; Charns, Martin P; McIntosh, Nathalie; Lerner, Barbara; Burgess, James F; Stolzmann, Kelly L; VanDeusen Lukas, Carol

2016-01-01

Health care organizations have used different strategies to implement quality improvement (QI) programs but with only mixed success in implementing and spreading QI organization-wide. This suggests that certain organizational strategies may be more successful than others in developing an organization's improvement capability. To investigate this, our study examined how the primary focus of grant-funded QI efforts relates to (1) key measures of grant success and (2) organization-level measures of success in QI and organizational learning. Using a mixed-methods design, we conducted one-way analyses of variance to relate Veterans Affairs administrative survey data to data collected as part of a 3.5-year evaluation of 29 health care organization grant recipients. We then analyzed qualitative evidence from the evaluation to explain our results. We found that hospitals that focused on developing organizational infrastructure to support QI implementation compared with those that focused on training or conducting projects rated highest (at α = .05) on all 4 evaluation measures of grant success and all 3 systemwide survey measures of QI and organizational learning success. This study adds to the literature on developing organizational improvement capability and has practical implications for health care leaders. Focusing on either projects or staff training in isolation has limited value. Organizations are more likely to achieve systemwide transformation of improvement capability if their strategy emphasizes developing or strengthening organizational systems, structures, or processes to support direct improvement efforts.

Temperature sensitivity of organic-matter decay in tidal marshes

USGS Publications Warehouse

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

2014-01-01

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

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.

A stoichiometric organic matter decomposition model in a chemostat culture.

PubMed

Kong, Jude D; Salceanu, Paul; Wang, Hao

2018-02-01

Biodegradation, the disintegration of organic matter by microorganism, is essential for the cycling of environmental organic matter. Understanding and predicting the dynamics of this biodegradation have increasingly gained attention from the industries and government regulators. Since changes in environmental organic matter are strenuous to measure, mathematical models are essential in understanding and predicting the dynamics of organic matters. Empirical evidence suggests that grazers' preying activity on microorganism helps to facilitate biodegradation. In this paper, we formulate and investigate a stoichiometry-based organic matter decomposition model in a chemostat culture that incorporates the dynamics of grazers. We determine the criteria for the uniform persistence and extinction of the species and chemicals. Our results show that (1) if at the unique internal steady state, the per capita growth rate of bacteria is greater than the sum of the bacteria's death and dilution rates, then the bacteria will persist uniformly; (2) if in addition to this, (a) the grazers' per capita growth rate is greater than the sum of the dilution rate and grazers' death rate, and (b) the death rate of bacteria is less than some threshold, then the grazers will persist uniformly. These conditions can be achieved simultaneously if there are sufficient resources in the feed bottle. As opposed to the microcosm decomposition models' results, in a chemostat culture, chemicals always persist. Besides the transcritical bifurcation observed in microcosm models, our chemostat model exhibits Hopf bifurcation and Rosenzweig's paradox of enrichment phenomenon. Our sensitivity analysis suggests that the most effective way to facilitate degradation is to decrease the dilution rate.

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

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

Elemental composition and functional groups in soil labile organic matter fractions

USDA-ARS?s Scientific Manuscript database

Labile organic matter fractions are major components involved in nutrient cycle in soil. In this chapter, we examine three labile organic matter fraction: light fraction (LF), humic acid (HA) and fulvic acid (HA) in Alabama cotton soils (ultisol) amended with chemical fertilizer (NH4NO3) and poult...

Organic matter preserved in 3-billion-year-old mudstones at Gale crater, Mars

NASA Astrophysics Data System (ADS)

Eigenbrode, Jennifer L.; Summons, Roger E.; Steele, Andrew; Freissinet, Caroline; Millan, Maëva; Navarro-González, Rafael; Sutter, Brad; McAdam, Amy C.; Franz, Heather B.; Glavin, Daniel P.; Archer, Paul D.; Mahaffy, Paul R.; Conrad, Pamela G.; Hurowitz, Joel A.; Grotzinger, John P.; Gupta, Sanjeev; Ming, Doug W.; Sumner, Dawn Y.; Szopa, Cyril; Malespin, Charles; Buch, Arnaud; Coll, Patrice

2018-06-01

Establishing the presence and state of organic matter, including its possible biosignatures, in martian materials has been an elusive quest, despite limited reports of the existence of organic matter on Mars. We report the in situ detection of organic matter preserved in lacustrine mudstones at the base of the ~3.5-billion-year-old Murray formation at Pahrump Hills, Gale crater, by the Sample Analysis at Mars instrument suite onboard the Curiosity rover. Diverse pyrolysis products, including thiophenic, aromatic, and aliphatic compounds released at high temperatures (500° to 820°C), were directly detected by evolved gas analysis. Thiophenes were also observed by gas chromatography–mass spectrometry. Their presence suggests that sulfurization aided organic matter preservation. At least 50 nanomoles of organic carbon persists, probably as macromolecules containing 5% carbon as organic sulfur molecules.

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.

The use of a MODIS band-ratio algorithm versus a new hybrid approach for estimating colored dissolved organic matter (CDOM)

EPA Science Inventory

Satellite remote sensing offers synoptic and frequent monitoring of optical water quality parameters, such as chlorophyll-a, turbidity, and colored dissolved organic matter (CDOM). While traditional satellite algorithms were developed for the open ocean, these algorithms often do...

Soil microbial diversity and activity linked to crop yield and quality in a dryland organic wheat production system

USDA-ARS?s Scientific Manuscript database

One of the primary goals of organic agriculture is increasing soil quality through the enhancement of soil biological diversity and activity. Greater soil microbial activity and diversity increase soil organic matter turnover and contribute to soil fertility, one of the main challenges associated wi...

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

Marine methane paradox explained by bacterial degradation of dissolved organic matter

NASA Astrophysics Data System (ADS)

Repeta, Daniel J.; Ferrón, Sara; Sosa, Oscar A.; Johnson, Carl G.; Repeta, Lucas D.; Acker, Marianne; Delong, Edward F.; Karl, David M.

2016-12-01

Biogenic methane is widely thought to be a product of archaeal methanogenesis, an anaerobic process that is inhibited or outcompeted by the presence of oxygen and sulfate. Yet a large fraction of marine methane delivered to the atmosphere is produced in high-sulfate, fully oxygenated surface waters that have methane concentrations above atmospheric equilibrium values, an unexplained phenomenon referred to as the marine methane paradox. Here we use nuclear magnetic resonance spectroscopy to show that polysaccharide esters of three phosphonic acids are important constituents of dissolved organic matter in seawater from the North Pacific. In seawater and pure culture incubations, bacterial degradation of these dissolved organic matter phosphonates in the presence of oxygen releases methane, ethylene and propylene gas. Moreover, we found that in mutants of a methane-producing marine bacterium, Pseudomonas stutzeri, disrupted in the C-P lyase phosphonate degradation pathway, methanogenesis was also disabled, indicating that the C-P lyase pathway can catalyse methane production from marine dissolved organic matter. Finally, the carbon stable isotope ratio of methane emitted during our incubations agrees well with anomalous isotopic characteristics of seawater methane. We estimate that daily cycling of only about 0.25% of the organic matter phosphonate inventory would support the entire atmospheric methane flux at our study site. We conclude that aerobic bacterial degradation of phosphonate esters in dissolved organic matter may explain the marine methane paradox.

Test procedure for determining organic matter content in soils : UV-VIS method.

DOT National Transportation Integrated Search

2010-11-01

The Texas Department of Transportation has been having problems with organic matter in soils that they : stabilize for use as subgrade layers in road construction. The organic matter reduces the effectiveness of : common soil additives (lime/cement) ...

Tracing organic matter sources in a tropical lagoon of the Caribbean Sea

NASA Astrophysics Data System (ADS)

Alonso-Hernández, Carlos M.; Garcia-Moya, Alejandro; Tolosa, Imma; Diaz-Asencio, Misael; Corcho-Alvarado, Jose Antonio; Morera-Gomez, Yasser; Fanelli, Emanuela

2017-09-01

The natural protected lagoon of Guanaroca, located between Cienfuegos Bay and the Arimao River, Cuba, has been heavily impacted by human-induced environmental changes over the past century. Sources of organic matter in the Guanaroca lagoon and concentrations of radioisotopes (210Pb, 226Ra, 137Cs and 239,240Pu), as tracers of anthropogenic impacts, were investigated in a 78 cm sediment core. Variations in total organic carbon (TOC), total nitrogen (TN), stable isotopic composition (δ13C and δ15N) and ratio of total organic carbon to total nitrogen (C/N) were analysed. On such a basis, environmental changes in the lagoon were revealed. Down core variation patterns of the parameters representing sources of organic matter were predominantly related to the impacts of human activities. Up to the nineteenth century, the principal sources of organic matter to sediments (more than 80%) were a mixing of terrestrial vascular plants ( 48%) and freshwater phytoplankton ( 8%), with minimal contribution from the marine component ( 16%). In the period 1900-1980, due to the strong influence of human activities in the catchment area, the water exchange capacity of the lagoon declined substantially, as indicated by the relatively high proportion of organic matter originated from human activities (58%). Since 1980, as a result of management actions in the protected area, the lagoon has regained gradually its capability to exchange freshwater, showing sources of organic matter similar to the natural conditions recorded previous to 1900, although an indication of human impact (treated sewage contributed for 26% to the organic matter in sediments) was still observed and further management measures would be required.

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.

The origin of organic matter in the Martian meteorite ALH84001.

PubMed

Becker, L; Popp, B; Rust, T; Bada, J L

1999-01-01

Stable carbon isotope measurements of the organic matter associated with the carbonate globules and the bulk matrix material in the ALH84001 Martian meteorite indicate that two distinct sources are present in the sample. The delta 13C values for the organic matter associated with the carbonate globules averaged -26% and is attributed to terrestrial contamination. In contrast, the delta 13C values for the organic matter associated with the bulk matrix material yielded a value of -15%. The only common carbon sources on the Earth that yield similar delta 13C values, other then some diagenetically altered marine carbonates, are C4 plants. A delta 13C value of -15%, on the other hand, is consistent with a kerogen-like component, the most ubiquitous form of organic matter found in carbonaceous chondrites such as the Murchison meteorite. Examination of the carbonate globules and bulk matrix material using laser desorption mass spectrometry (LDMS) indicates the presence of a high molecular weight organic component which appears to be extraterrestrial in origin, possibly derived from the exogenous delivery of meteoritic or cometary debris to the surface of Mars.

The origin of organic matter in the Martian meteorite ALH84001.

PubMed

Becker, L; Popp, B; Rust, T; Bada, J L

1999-03-30

Stable carbon isotope measurements of the organic matter associated with the carbonate globules and the bulk matrix material in the ALH84001 Martian meteorite indicate that two distinct sources are present in the sample. The delta 13C values for the organic matter associated with the carbonate globules averaged -26% and is attributed to terrestrial contamination. In contrast, the delta 13C values for the organic matter associated with the bulk matrix material yielded a value of -15%. The only common sources of carbon on the Earth that yield similar delta 13C values, other then some diagenetically altered marine carbonates, are C4 plants. A delta 13C value of -15%, on the other hand, is consistent with a kerogen-like component, the most ubiquitous form of organic matter found in carbonaceous chondrites such as the Murchison meteorite. Examination of the carbonate globules and bulk matrix material using laser desorption mass spectrometry (LDMS) indicates the presence of a high molecular weight organic component which appears to be extraterrestrial in origin, possibly derived from the exogenous delivery, of meteoritic or cometary debris to the surface of Mars.

Organic matter and the geotechnical properties of submarine sediments

NASA Astrophysics Data System (ADS)

Keller, George H.

1982-09-01

Continental slope deposits off Peru and Oregon where coastal upwelling is a pronounced oceanographic process possess significant concentrations of organic carbon. Geotechnical properties are altered to varying degrees by the organic matter. Organic matter absorbs water and causes clay-size particles to aggregate forming an open fabric. This causes unusually high water contents and plasticity and exceptionally low wet bulk densities. Some of these deposits show notable increases in shear strength, sensitivity and degree of apparent overconsolidation. Owing to the unique geotechnical properties, sediment stability characteristics are considered to be poor in situations of excess pore pressures. Failure appears to take the form of a fluidized flow somewhat similar to the quick clays of Scandinavia.

Fire Effects on Soil and Dissolved Organic Matter in a Southern Appalachian Hardwood Forest: Movement of Fire-Altered Organic Matter Across the Terrestrial-Aquatic Interface Following the Great Smoky Mountains National Park Fire of 2016

NASA Astrophysics Data System (ADS)

Matosziuk, L.; Gallo, A.; Hatten, J. A.; Heckman, K. A.; Nave, L. E.; Sanclements, M.; Strahm, B. D.; Weiglein, T.

2017-12-01

Wildfire can dramatically affect the quantity and quality of soil organic matter (SOM), producing thermally altered organic material such as pyrogenic carbon (PyC) and polyaromatic hydrocarbons (PAHs). The movement of this thermally altered material through terrestrial and aquatic ecosystems can differ from that of unburned SOM, with far-reaching consequences for soil carbon cycling and water quality. Unfortunately, due to the rapid ecological changes following fire and the lack of robust pre-fire controls, the cycling of fire-altered carbon is still poorly understood. In December 2016, the Chimney Tops 2 fire in Great Smoky Mountains National Park burned over co-located terrestrial and aquatic NEON sites. We have leveraged the wealth of pre-fire data at these sites (chemical, physical, and microbial characterization of soils, continuous measurements of both soil and stream samples, and five soil cores up to 110 cm in depth) to conduct a thorough study of the movement of fire-altered organic matter through terrestrial and aquatic ecosystems. Stream samples have been collected weekly beginning 5 weeks post-fire. Grab samples of soil were taken at discrete time points in the first two months after the fire. Eight weeks post-fire, a second set of cores was taken and resin lysimeters installed at three different depths. A third set of cores and grab samples will be taken 8-12 months after the fire. In addition to routine soil characterization techniques, solid samples from cores and grab samples at all time points will be analyzed for PyC and PAHs. To determine the effect of fire on dissolved organic matter (DOM), hot water extracts of these soil samples, as well as the stream samples and lysimeter samples, will also be analyzed for PyC and PAHs. Selected samples will be analyzed by 1D- and 2D-NMR to further characterize the chemical composition of DOM. This extensive investigation of the quantity and quality of fire-altered organic material at discrete time points

Linking groundwater dissolved organic matter to sedimentary organic matter from a fluvio-lacustrine aquifer at Jianghan Plain, China by EEM-PARAFAC and hydrochemical analyses.

PubMed

Huang, Shuang-bing; Wang, Yan-xin; Ma, Teng; Tong, Lei; Wang, Yan-yan; Liu, Chang-rong; Zhao, Long

2015-10-01

The sources of dissolved organic matter (DOM) in groundwater are important to groundwater chemistry and quality. This study examined similarities in the nature of DOM and investigated the link between groundwater DOM (GDOM) and sedimentary organic matter (SOM) from a lacustrine-alluvial aquifer at Jianghan Plain. Sediment, groundwater and surface water samples were employed for SOM extraction, optical and/or chemical characterization, and subsequent fluorescence excitation-emission matrix (EEM) and parallel factor analyses (PARAFAC). Spectroscopic properties of bulk DOM pools showed that indices indicative of GDOM (e.g., biological source properties, humification level, aromaticity and molecule mobility) varied within the ranges of those of two extracted end-members of SOM: humic-like materials and microbe-associated materials. The coexistence of PARAFAC compositions and the sustaining internal relationship between GDOM and extracted SOM indicate a similar source. The results from principal component analyses with selected spectroscopic indices showed that GDOM exhibited a transition trend regarding its nature: from refractory high-humification DOM to intermediate humification DOM and then to microbe-associated DOM, with decreasing molecular weight. Correlations of spectroscopic indices with physicochemical parameters of the groundwater suggested that GDOM was released from SOM and was modified by microbial diagenetic processes. The current study demonstrated the associations of GDOM with SOM from a spectroscopic viewpoint and provided new evidence supporting SOM as the source of GDOM. Copyright © 2015 Elsevier B.V. All rights reserved.

Enzymatic biofilm digestion in soil aggregates facilitates the release of particulate organic matter by sonication

NASA Astrophysics Data System (ADS)

Büks, Frederick; Kaupenjohann, Martin

2016-10-01

The stability of soil aggregates against shearing and compressive forces as well as water-caused dispersion is an integral marker of soil quality. High stability results in less compaction and erosion and has been linked to enhanced water retention, dynamic water transport and aeration regimes, increased rooting depth, and protection of soil organic matter (SOM) against microbial degradation. In turn, particulate organic matter is supposed to support soil aggregate stabilization. For decades the importance of biofilm extracellular polymeric substances (EPSs) regarding particulate organic matter (POM) occlusion and aggregate stability has been canonical because of its distribution, geometric structure and ability to link primary particles. However, experimental proof is still missing. This lack is mainly due to methodological reasons. Thus, the objective of this work is to develop a method of enzymatic biofilm detachment for studying the effects of EPSs on POM occlusion. The method combines an enzymatic pre-treatment with different activities of α-glucosidase, β-galactosidase, DNAse and lipase with a subsequent sequential ultrasonic treatment for disaggregation and density fractionation of soils. POM releases of treated samples were compared to an enzyme-free control. To test the efficacy of biofilm detachment the ratio of bacterial DNA from suspended cells and the remaining biofilm after enzymatic treatment were measured by quantitative real-time PCR. Although the enzyme treatment was not sufficient for total biofilm removal, our results indicate that EPSs may attach POM within soil aggregates. The tendency to additional POM release with increased application of enzymes was attributed to a slight loss in aggregate stability. This suggests that an effect of agricultural practices on soil microbial populations could influence POM occlusion/aggregate stability and thereby carbon cycle/soil quality.

SOM quality and phosphorus fractionation to evaluate degradation organic matter: implications for the restoration of soils after fire

NASA Astrophysics Data System (ADS)

Merino, Agustin; Fonturbel, Maria T.; Omil, Beatriz; Chávez-Vergara, Bruno; Fernandez, Cristina; Garcia-Oliva, Felipe; Vega, Jose A.

2016-04-01

The design of emergency treatment for the rehabilitation of fire-affected soils requires a quick diagnosis to assess the degree of degradation. For its implication in the erosion and subsequent evolution, the quality of soil organic matter (OM) plays a particularly important role. This paper presents a methodology that combines the visual recognition of the severity of soil burning with the use of simple analytical techniques to assess the degree of degradation of OM. The content and quality of the OM was evaluated in litter and mineral soils using thermogravimetry-differential scanning calorimetry (DSC-TG) spectroscopy, and the results were contrasted with 13C CP-MAS NMR. The types of methodologies were texted to assess the thermal analysis: a) the direct calculation of the Q areas related to three degrees of thermal stabilities: Q1 (200-375 °C; labil OM); Q2 (375-475 °C, recalcitrant OM); and Q3 (475-550 °C). b) deconvolution of DSC curves and calculation of each peak was expressed as a fraction of the total DSC curve area. Additionally, a P fractionation was done following the Hedley sequential extraction method. The severity levels visually showed different degrees of SOM degradation. Although the fire caused important SOM losses in moderate severities, changes in the quality of OM only occurred at higher severities. Besides, the labile organic P fraction decreased and the occluded inorganic P fraction increased in the high severity soils. These changes affect the OM processes such as hydrophobicity and erosion largely responsible for soil degradation post-fire. The strong correlations between the thermal parameters and NMR regions and derived measurements such as hydrophobicity and aromaticity show the usefulness of this technique as rapid diagnosis to assess the soil degradation.The marked loss of polysaccharide and transition to highly thermic-resistant compounds, visible in deconvoluted thermograms, which would explain the changes in microbial activity

Effect of organic matter on CO(2) hydrate phase equilibrium in phyllosilicate suspensions.

PubMed

Park, Taehyung; Kyung, Daeseung; Lee, Woojin

2014-06-17

In this study, we examined various CO2 hydrate phase equilibria under diverse, heterogeneous conditions, to provide basic knowledge for successful ocean CO2 sequestration in offshore marine sediments. We investigated the effect of geochemical factors on CO2 hydrate phase equilibrium. The three-phase (liquid-hydrate-vapor) equilibrium of CO2 hydrate in the presence of (i) organic matter (glycine, glucose, and urea), (ii) phyllosilicates [illite, kaolinite, and Na-montmorillonite (Na-MMT)], and (iii) mixtures of them was measured in the ranges of 274.5-277.0 K and 14-22 bar. Organic matter inhibited the phase equilibrium of CO2 hydrate by association with water molecules. The inhibition effect decreased in the order: urea < glycine < glucose. Illite and kaolinite (unexpandable clays) barely affected the CO2 hydrate phase equilibrium, while Na-MMT (expandable clay) affected the phase equilibrium because of its interlayer cations. The CO2 hydrate equilibrium conditions, in the illite and kaolinite suspensions with organic matter, were very similar to those in the aqueous organic matter solutions. However, the equilibrium condition in the Na-MMT suspension with organic matter changed because of reduction of its inhibition effect by intercalated organic matter associated with cations in the Na-MMT interlayer.

Non-invasive localization of organic matter in soil aggregates using SR-μCT

NASA Astrophysics Data System (ADS)

Peth, Stephan; Mordhorst, Anneka; Chenu, Claire; Uteau Puschmann, Daniel; Garnier, Patricia; Nunan, Naoise; Pot, Valerie; Beckmann, Felix; Ogurreck, Malte

2014-05-01

Knowledge of the location of soil organic matter (SOM) and its spatial association to soil structure is an important step in improving modeling approaches for simulating organic matter turnover processes. Advanced models for carbon mineralization are able to account for the 3D distribution of SOM which is assumed to influence mineralisation. However, their application is still limited by the fact that no method exists to non-invasively determine the 3D spatial distribution of SOM in structured soils. SR-based X-ray microtomography (SR-µCT) is an advanced and promising tool in gaining knowledge on the 3-dimensional organization of soil phases (minerals, organic matter, water, air) which on a voxel level could be implemented into spatially explicit models. However, since the contrast of linear attenuation coefficients of soil organic matter on the one hand and mineral components and water on the other hand are relatively low, especially when materials are finely dispersed, organic matter within the soil pore space is often not resolved in ordinary X-ray absorption contrast imaging. To circumvent this problem we have developed a staining procedure for organic matter using Osmium-tetroxide since Osmium is an element with an absorption edge at a higher X-ray energy level. Osmium is known from transmission electron microscopy analysis (TEM) to stain organic matter specifically and irreversibly while having an absorption edge at approximately 74 keV. We report on the application of a novel Osmium vapor staining method to analyze differences in organic matter content and identify small scale spatial distribution of SOM in soil aggregates. To achieve this we have taken soil aggregate samples (6-8 mm across) obtained from arable soils differing in soil management. Aggregate samples were investigated by synchrotron-based X-ray microtomography (SR-µCT) after staining the sample with Osmium-tetroxide (OsO4) vapor. We utilized the monochromatic X-ray beam to locate osmium

Evidence for Changes in 81PIWild 2 Organic Matter Since Collection and Comparison of 82PIWild 2 and IDP Organic Matter to Access the Thermal Effects of Aerogel Capture

NASA Technical Reports Server (NTRS)

Wirick, S.; Flynn, G. J.; Keller, L.; Messenger, Nakamura; Sandford, S. A.; Zolensky, M. E.; Peltzer, C.; Jacobsen, C.

2009-01-01

NASA s Stardust spacecraft collected cometary material during its passage through the dust coma of comet 81P/Wild 2 on January 2nd, 2004 and delivered this material to Earth on January 15th 2006. The first fragment we analyzed during the preliminary examination was partially vaporized by the X-ray beam. The carbonaceous material that survived was re-analysis approx.2 months later and the carbon spectrum for this material had significantly changed from what we first observed.. We have observed similar changes to the carbonaceous matter in some interplanetary dust particles ( IDPs). Some of the 81P/Wild 2 organic matter volatilized upon impact with the aerogel as observed using IR spectroscopy where IR spectra were collected several mms away from sample tracks [1]. The time-temperature profile experienced by any particular 81P/Wild 2 grain during aerogel capture is not known, although Brownlee, et al. suggest that fine-grained materials, <1 micron in size, fragmented and then partially vaporized during collection, while particles much larger then 1 micron in size were captured intact [2]. Nearly all organic matter is subject to thermal alteration. To assess the heating and alteration experienced by the 81P/Wild 2 organic matter during capture we are comparing 81P/Wild2 organic matter with IDP organic matter where we have evidence of heating in the IDP [3,4].

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

USGS Publications Warehouse

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

1992-01-01

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

Effect of organic matter properties, clay mineral type and thermal maturity on gas adsorption in organic-rich shale systems

USGS Publications Warehouse

Zhang, Tongwei; Ellis, Geoffrey S.; Ruppel, Stephen C.; Milliken, Kitty; Lewan, Mike; Sun, Xun; Baez, Luis; Beeney, Ken; Sonnenberg, Steve

2013-01-01

A series of CH4 adsorption experiments on natural organic-rich shales, isolated kerogen, clay-rich rocks, and artificially matured Woodford Shale samples were conducted under dry conditions. Our results indicate that physisorption is a dominant process for CH4 sorption, both on organic-rich shales and clay minerals. The Brunauer–Emmett–Teller (BET) surface area of the investigated samples is linearly correlated with the CH4 sorption capacity in both organic-rich shales and clay-rich rocks. The presence of organic matter is a primary control on gas adsorption in shale-gas systems, and the gas-sorption capacity is determined by total organic carbon (TOC) content, organic-matter type, and thermal maturity. A large number of nanopores, in the 2–50 nm size range, were created during organic-matter thermal decomposition, and they significantly contributed to the surface area. Consequently, methane-sorption capacity increases with increasing thermal maturity due to the presence of nanopores produced during organic-matter decomposition. Furthermore, CH4 sorption on clay minerals is mainly controlled by the type of clay mineral present. In terms of relative CH4 sorption capacity: montmorillonite ≫ illite – smectite mixed layer > kaolinite > chlorite > illite. The effect of rock properties (organic matter content, type, maturity, and clay minerals) on CH4 adsorption can be quantified with the heat of adsorption and the standard entropy, which are determined from adsorption isotherms at different temperatures. For clay-mineral rich rocks, the heat of adsorption (q) ranges from 9.4 to 16.6 kJ/mol. These values are considerably smaller than those for CH4 adsorption on kerogen (21.9–28 kJ/mol) and organic-rich shales (15.1–18.4 kJ/mol). The standard entropy (Δs°) ranges from -64.8 to -79.5 J/mol/K for clay minerals, -68.1 to -111.3 J/mol/K for kerogen, and -76.0 to -84.6 J/mol/K for organic-rich shales. The affinity of CH4 molecules for sorption on organic matter

Lability of Secondary Organic Particulate Matter

DOE PAGES

Liu, Pengfei; Li, Yong Jie; Wang, Yan; ...

2016-10-24

Accurate simulations of the consenctrations of atmospheric organic particulate matter (PM) are needed for predicting energy flow in the Earth’s climate system. In the past, simulations of organic PM widely assume equilibrium partitioning of semivolatile organic compounds (SVOCs) between the PM and surrounding vapor. Herein, we test this assumption by measuring evaporation rates and associated vapor mass concentration of organic films representative of atmospheric PM. For films representing anthropogenic PM, evaporation rates and vapor mass concentrations increased above a threshold relative humidity (RH), indicating equilibrium partitioning above a transition RH but not below. In contrast for films representing biogenic PM,more » no threshold was observed, indicating equilibrium partitioning at all RHs. The results suggest that the mass lability of atmospheric organic PM can differ in consequential ways among Earth’s natural biomes, polluted regions, and regions of land-use change, and these differences need to be considered when simulating atmospheric organic PM.« less

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

PubMed

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

2015-01-01

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

Priming of native soil organic matter by pyrogenic organic matter

NASA Astrophysics Data System (ADS)

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

2015-04-01

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

Organic matter preserved in 3-billion-year-old mudstones at Gale crater, Mars.

PubMed

Eigenbrode, Jennifer L; Summons, Roger E; Steele, Andrew; Freissinet, Caroline; Millan, Maëva; Navarro-González, Rafael; Sutter, Brad; McAdam, Amy C; Franz, Heather B; Glavin, Daniel P; Archer, Paul D; Mahaffy, Paul R; Conrad, Pamela G; Hurowitz, Joel A; Grotzinger, John P; Gupta, Sanjeev; Ming, Doug W; Sumner, Dawn Y; Szopa, Cyril; Malespin, Charles; Buch, Arnaud; Coll, Patrice

2018-06-08

Establishing the presence and state of organic matter, including its possible biosignatures, in martian materials has been an elusive quest, despite limited reports of the existence of organic matter on Mars. We report the in situ detection of organic matter preserved in lacustrine mudstones at the base of the ~3.5-billion-year-old Murray formation at Pahrump Hills, Gale crater, by the Sample Analysis at Mars instrument suite onboard the Curiosity rover. Diverse pyrolysis products, including thiophenic, aromatic, and aliphatic compounds released at high temperatures (500° to 820°C), were directly detected by evolved gas analysis. Thiophenes were also observed by gas chromatography-mass spectrometry. Their presence suggests that sulfurization aided organic matter preservation. At least 50 nanomoles of organic carbon persists, probably as macromolecules containing 5% carbon as organic sulfur molecules. Copyright © 2018 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

The organic matter of the different ages fallow Luvisols

NASA Astrophysics Data System (ADS)

Giniyatullin, K. G.; Valeeva, A. A.; Smirnova, E. V.; Okunev, R. V.; Latipova, L. I.

2018-01-01

The study of the change in the humus state of the fallow Luvisols of different ages under the influence of weeds and meadow vegetation was carried out in dynamics (after 5 years). It is shown that both under weedy and meadow vegetation there is a statistically significant accumulation of organic matter in the upper part of the long-arable horizon. Based on the study of composition and spectral properties of soil organic matter in fallow soils of different ages concluded that the significant qualitative change of the humus state of fallow soils requires significant time, measured at least decades.

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

Soil Organic Matter and Soil Productivity: Searching for the Missing Link

Treesearch

Felipe G. Sanchez

1998-01-01

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...

Ideas on the emergence of life by a quantity-to-quality transition of the abiotic matter

NASA Astrophysics Data System (ADS)

Kolb, Vera M.

2005-09-01

We review and re-examine the idea that life emerged by a quantity-to-quality transition of the abiotic matter. This idea was originally proposed by the dialectical materialists, who are the proponents of the materialistic approach to the Hegel's laws of dialectics. We propose in this paper that the universal feature of the quantity-to-quality transitions is a change in the organization of the system. We also discuss Jean-Paul Sartre's view on the application of the laws of dialectics to the nature and to the origins of life.

Assessing the Impact of Land Management on Organic Matter Composition in Peat Soils

NASA Astrophysics Data System (ADS)

Savage, A.; Holden, J.; Wainwright, J.

2010-05-01

Peatlands are seen as important stores of terrestrial carbon, accounting for up to one-third of global soil carbon stocks. In some cases peatlands are shown to be emitters of carbon, in other cases carbon sinks depending on the site conditions and nature of degradation. However, carbon budget calculations carried out to date have a number of uncertainties associated with them and the composition of the carbon is generally not considered when determining carbon budgets. Carbon cycling in peat is driven by four key factors (Laiho, 2006):, environmental conditions (e.g. temperature, water table level), substrate quality (e.g. how recalcitrant the peat is), nutrients (e.g. nitrogen required to synthesis the carbon stocks) and microbial community (e.g. are the microbes present able to utilise the available substrate). Land management is also recognised as an additional driver, but the impacts of many types of management are poorly understood. Among the four drivers listed by Laiho (2006) substrate quality is seen as the most significant. To date, little work has been carried out to characterise the quality of organic matter in peat soils; rather crude estimates have been made as to the quantity of carbon that is stored in peatlands, yet without understanding the composition of the peat, limitations are imposed on calculations of rates of carbon loss from peatlands. This work seeks to examine how variations in the chemical composition of organic matter in peat varies with land use. The method published by Wieder and Starr (1998) was followed to determine eight fractions: soluble fats and waxes, hot water soluble, hollocellulose, cellulose, soluble phenolics, acid insoluble carbohydrates, water soluble carbohydrates and lignin. Samples were taken from burnt, grazed, drained, afforested and undisturbed sites at the Moor House UNESCO Biosphere Reserve in Northern England. The method was used to identify if differences were present in the recalcitrance of the peat and linked

Evaluating the ameliorative effect of natural dissolved organic matter (DOM) quality on copper toxicity to Daphnia magna: improving the BLM.

PubMed

Al-Reasi, Hassan A; Smith, D Scott; Wood, Chris M

2012-03-01

Various quality predictors of seven different natural dissolved organic matter (DOM) and humic substances were evaluated for their influence on protection of Daphnia magna neonates against copper (Cu) toxicity. Protection was examined at 3 and 6 mg l(-1) of dissolved organic carbon (DOC) of each DOM isolate added to moderately hard, dechlorinated water. Other water chemistry parameters (pH, concentrations of DOC, calcium, magnesium and sodium) were kept relatively constant. Predictors included absorbance ratios Abs(254/365) (index of molecular weight) and Abs-octanol(254)/Abs-water(254) (index of lipophilicity), specific absorption coefficient (SAC(340); index of aromaticity), and fluorescence index (FI; index of source). In addition, the fluorescent components (humic-like, fulvic-like, tryptophan-like, and tyrosine-like) of the isolates were quantified by parallel factor analysis (PARAFAC). Up to 4-fold source-dependent differences in protection were observed amongst the different DOMs. Significant correlations in toxicity amelioration were found with Abs(254/365), Abs-octanol(254)/Abs-water(254), SAC(340), and with the humic-like fluorescent component. The relationships with FI were not significant and there were no relationships with the tryptophan-like or tyrosine-like fluorescent components at 3 mg C l(-1), whereas a negative correlation was seen with the fulvic-like component. In general, the results indicate that larger, optically dark, more lipophilic, more aromatic DOMs of terrigenous origin, with higher humic-like content, are more protective against Cu toxicity. A method for incorporating SAC(340) as a DOM quality indicator into the Biotic Ligand Model is presented; this may increase the accuracy for predicting Cu toxicity in natural waters.

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

USGS Publications Warehouse

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

1986-01-01

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

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.

Removing organic matter from sulfate-rich wastewater via sulfidogenic and methanogenic pathways.

PubMed

Vilela, Rogerio Silveira; Damianovic, Márcia Helena Rissato Zamariolli; Foresti, Eugenio

2014-01-01

The simultaneous organic matter removal and sulfate reduction in synthetic sulfate-rich wastewater was evaluated for various chemical oxygen demand (COD)/sulfate ratios applied in a horizontal-flow anaerobic immobilized sludge (HAIS) reactor. At higher COD/sulfate ratios (12.5 and 7.5), the removal of organic matter was stable, likely due to methanogenesis. A combination of sulfate reduction and methanogenesis was clearly established at COD/sulfate ratios of 3.0 and 1.9. At a COD/sulfate ratio of 1.0, the organic matter removal was likely influenced by methanogenesis inhibition. The quantity of sulfate removed at a COD/sulfate ratio of 1.0 was identical to that obtained at a ratio of 1.9, indicating a lack of available electron donors for sulfidogenesis. The sulfate reduction and organic matter removal were not maximized at the same COD/sulfate ratio; therefore, competitive inhibition must be the predominant mechanism in establishing an electron flow.

Characterisation of dissolved organic matter in stormwater using high-performance size exclusion chromatography.

PubMed

Huang, Huiping; Chow, Christopher W K; Jin, Bo

2016-04-01

Understanding the complexity of dissolved organic matter (DOM) in stormwater has drawn a lot of interest, since DOM from stormwater causes not only environmental impacts, but also worsens downstream aquatic quality associated with water supply and treatability. This study introduced and employed high-performance size exclusion chromatography (HPSEC) coupled with an ultraviolet-visible (UV-vis) diode array detector to assess changes in stormwater-associated DOM characteristics. Stormwater DOM was also analysed in relation to storm event characteristics, water quality and spectroscopic analysis. Statistical tools were used to determine the correlations within DOM and water quality measurements. Results showed that dissolved organic carbon (DOC) and UV absorbance at 254 nm (UV254) as conventional DOM parameters were found to be correlated well to the changes in stormwater quality during each of the three storm events studied. Both detector wavelengths (210 and 254 nm) and their ratio (A210/A254) were found to provide additional information on the physiochemical properties of stormwater-associated DOM. This study indicated that A210/A254 is an important parameter which could be used to estimate the DOM proportions of functional groups and conjugated carbon species. This study provided also an understanding of stormwater quality constituents through assessing variability and sensitivity for various parameters, and the additional information of rainfall characteristics on runoff quality data for a better understanding of parameter correlations and influences. Copyright © 2015. Published by Elsevier B.V.

Plutonium Immobilization and Mobilization by Soil Organic Matter

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

Santschi, Peter H.; Schwehr, Kathleen A.; Xu, Chen

The human and environmental risks associated with Pu disposal, remediation, and nuclear accidents scenarios stems mainly from the very long half-lives of several of its isotopes. The SRS, holding one-third of the nation’s Pu inventory, has a long-term stewardship commitment to investigation of Pu behavior in the groundwater and downgradient vast wetlands. Pu is believed to be essentially immobile due to its low solubility and high particle reactivity to mineral phase or natural organic matter (NOM). For example, in sediments collected from a region of SRS, close to a wetland and a groundwater plume, 239,240Pu concentrations suggest immobilization by NOMmore » compounds, as Pu correlate with NOM contents. Micro-SXRF data indicate, however, that Pu does not correlate with Fe. However, previous studies reported Pu can be transported several kilometers in surface water systems, in the form of a colloidal organic matter carrier, through wind/water interactions. The role of NOM in both immobilizing or re-mobilizing Pu thus has been demonstrated. Our results indicate that more Pu (IV) than (V) was bound to soil colloidal organic matter (COM), amended at far-field concentrations. Contrary to expectations, the presence of NOM in the F-Area soil did not enhance Pu fixation to the organic-rich soil, when compared to the organic-poor soil or the mineral phase from the same soil source, due to the formation of COM-bound Pu. Most importantly, Pu uptake by organic-rich soil decreased with increasing pH because more NOM in the colloidal size desorbed from the particulate fraction at elevated pH, resulting in greater amounts of Pu associated with the COM fraction. This is in contrast to previous observations with low-NOM sediments or minerals, which showed increased Pu uptake with increasing pH levels. This demonstrates that despite Pu immobilization by NOM, COM can convert Pu into a more mobile form. Sediment Pu concentrations in the SRS F-Area wetland were correlated to total

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 dynamics and stable isotopes for tracing sources of suspended sediment

NASA Astrophysics Data System (ADS)

Schindler Wildhaber, Y.; Liechti, R.; Alewell, C.

2012-01-01

Suspended sediment (SS) and organic matter in rivers can harm brown trout Salmo trutta by impact on health and fitness of free swimming fish and siltation of the riverbed. The later results in a decrease of hydraulic conductivity and therefore smaller oxygen supply to the salmonid embryos. Additionally, oxygen demand within riverbeds will increase as the pool of organic matter increases. We assessed the temporal and spatial dynamics of sediment, carbon (C) and nitrogen (N) during the brown trout spawning season and used C isotopes as well as the C/N atomic ratio to distinguish autochthonous and allochthonous sources of organic matter in SS loads. The visual basic program IsoSource with 13Ctot and 15N as input isotopes was used to quantify the sources of SS in respect of time and space. Organic matter fractions in the infiltrated and suspended sediment were highest during low flow periods with small sediment loads and lowest during high flow periods with high sediment loads. Peak values in nitrate and dissolved organic C were measured during high flow and precipitation probably due to leaching from pasture and arable land. The organic matter was of allochthonous sources as indicated by the C/N atomic ratio and δ13Corg. Organic matter in SS increased from up- to downstream due to pasture and arable land. The fraction of SS originating from upper watershed riverbed sediment increased at all sites during high flow. Its mean fraction decreased from up- to downstream. During base flow conditions, the major sources of SS are pasture and arable land. The later increased during rainy and warmer periods probably due to snow melting and erosion processes. These modeling results support the measured increased DOC and NO3 concentrations during high flow.

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

USDA-ARS?s Scientific Manuscript database

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

Characterization of Natural Organic Matter by FeCl3 Coagulation

NASA Astrophysics Data System (ADS)

Cahyonugroho, O. H.; Hidayah, E. N.

2018-01-01

Natural organic matter (NOM) is heterogenous mixture of organic compounds that enter the water from various decomposition and metabolic reactions, including animal, plant, domestic and industrial wastes. NOM refers to group of carbon-based compounds that are found in surface water and ground water. The aim of the study is to assess organic matter characteristics in Jagir River as drinking water source and to characterize the organic components that could be removed during coagulation. Coagulation is the common water treatment process can be used to remove NOM with FeCl3 coagulant in various dosage. NOM surrogates, including total organic carbon (TOC), ultraviolet absorbance at 254 nm (UV254) and specific UV absorbance (SUVA) were chosen to assess the organic removal. Results of jar test experiments showed that NOM can be removed about 40% of NOM surrogates with 200 mg/L FeCl3. About 60% removal of total organic fraction, which is mainly humic substances, as detected by size exclusion chromatography (SEC).

Colored dissolved organic matter dynamics and anthropogenic influences in a major transboundary river and its coastal wetland

PubMed Central

Zeri, Christina; Dimitriou, Elias; Ding, Yan; Jaffé, Rudolf; Anagnostou, Emmanouil; Pitta, Elli; Mentzafou, Angeliki

2015-01-01

Abstract Most transboundary rivers and their wetlands are subject to considerable anthropogenic pressures associated with multiple and often conflicting uses. In the Eastern Mediterranean such systems are also particularly vulnerable to climate change, posing additional challenges for integrated water resources management. Comprehensive measurements of the optical signature of colored dissolved organic matter (CDOM) were combined with measurements of river discharges and water physicochemical and biogeochemical properties, to assess carbon dynamics, water quality, and anthropogenic influences in a major transboundary system of the Eastern Mediterranean, the Evros (or, Марица or, Meriç) river and its Ramsar protected coastal wetland. Measurements were performed over three years, in seasons characterized by different hydrologic conditions and along transects extending more than 70 km from the freshwater end‐member to two kilometers offshore in the Aegean Sea. Changes in precipitation, anthropogenic dissolved organic matter (DOM) inputs from the polluted Ergene tributary, and the irregular operation of a dam were key factors driving water quality, salinity regimes, and biogeochemical properties in the Evros delta and coastal waters. Marsh outwelling affected coastal carbon quality, but the influence of wetlands was often masked by anthropogenic DOM contributions. A distinctive five‐peak CDOM fluorescence signature was characteristic of upstream anthropogenic inputs and clearly tracked the influence of freshwater discharges on water quality. Monitoring of this CDOM fluorescence footprint could have direct applications to programs focusing on water quality and environmental assessment in this and other transboundary rivers where management of water resources remains largely ineffective. PMID:27656002

Preservation of organic matter on Mars by sulfur

NASA Astrophysics Data System (ADS)

Eigenbrode, J. L.; Steele, A.; Summons, R. E.; McAdam, A.; Sutter, B.; Franz, H. B.; Freissinet, C.; Millan, M.; Glavin, D. P.; Szopa, C.; Conrad, P. G.; Mahaffy, P. R.

2016-12-01

Deltaic-lacustrine mudstones at Pahrump Hills, Gale Crater, Mars yielded a variety of sulfur-containing volatiles upon heating to 500-860°C, as detected by the Sample Analysis at Mars (SAM) instrument onboard the Curiosity rover. The detection of organosulfur compounds comprising thiophenes, dimethylsulfide and thiols by gas chromatography-mass spectrometry and evolved gas analyses, together with aromatic and other hydrocarbon molecules with distributions specific to the sample (i.e., not from the SAM background) indicate that some or all of these organic fragments released at high temperatures are indigenous to the mudstones. The organosulfur compounds are most likely derived from sulfur organics in the sediments. However, there is a possibility that sulfurization of some organic fragments occurred in the oven. On Earth, sulfurization of organic matter is a key process that aids preservation over geological time-scales. This is because it reduces reactive functional groups and adds cross links between small unstable molecules thereby converting them into recalcitrant macromolecules. Sulfurization of organic materials prior to deposition and during early diagenesis may have been a key mechanism responsible for organic matter preservation in the Murray formation mudstones. Sulfur-bearing organics have also been observed in carbonaceous meteorites and there is indication of their presence in the Tissint martian meteorite. A quantitative assessment of organosulfur compounds relative to their non-organic counterparts will be presented for the Murray formation mudstones analyzed by SAM and meteorites analyzed in the laboratory under similar analytical conditions.

Dissolved organic matter in the unsaturated zone: the view from the cave

NASA Astrophysics Data System (ADS)

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

2017-12-01

Soil organic matter content is typically a few percent of the total soil composition. Diffuse recharge can mobilise some of this soil-derived organic matter. While soil pore water dissolved organic matter (DOM) concentrations are up to 100 ppm, the resulting groundwater dissolved organic matter concentration is typically less than 2ppm. Dissolved organic matter transported from the soil can be both biodegraded and sorbed to minerals, and the relative importance of these two processes in the unsaturated zone is poorly understood. Caves in karstified limestone uniquely provide direct access to water percolating from the soil to the groundwater. Cave percolation waters can be analysed for their DOM concentration and character. This provides insights into the extent and type of biological and chemical processing of DOM during transport from the soil to the groundwater. We determine the concentration and characteristics of DOM in cave percolation waters using liquid chromatography (LC-OCD) and optical spectrophotometry (fluorescence and absorbance). We sample DOM from multiple caves in SE Australia (Cathedral Cave, Wellington; South Glory and Harrie Wood Caves, Yarrangobilly), permitting comparison of unsaturated zone DOM properties at different depths (up to 30m below land surface) and different climate zones (montane and temperate). We use caves with long-term hydrological monitoring programs so that DOM in waters of contrasting residence times can be compared. Additionally, we compare these cave percolation water DOM characteristics to those from local and regional groundwater, sampled from nearby wells. Our results will help improve our understanding of how DOM is processed from soil to groundwater, and is also relevant to speleothem scientists interested in using organic matter preserved in speleothems as a paleoclimate or paleoenvironmental proxy.

Sorption of benzimidazole anthelmintics to dissolved organic matter surrogates and sewage sludge.

PubMed

Kim, Hyo-Jung; Lee, Dong Soo; Kwon, Jung-Hwan

2010-06-01

The sorption coefficients of four rarely studied zwitterionic pharmaceuticals (benzimidazoles: fenbendazole, albendazole, thiabendazole and flubendazole) and four metabolites of fenbendazole to various dissolved organic matter surrogates (humic acid, sodium dodecyl sulfate micelle, hydroxypropyl-beta-cyclodextrin and liposomes made of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC), and sewage sludge) were measured to extend the available sorption coefficients and eventually to evaluate their environmental fate in soil and water environment. For the entire range of dissolved organic matters, the more hydrophobic fenbendazole and albendazole had higher sorption coefficients than thiabendazole and flubendazole, indicating that the traditional hypothesis of hydrophobic interaction holds for zwitterionic benzimidazole anthelmintics. However, the sorption coefficients of a given benzimidazole to selected dissolved organic matters (DOMs) varied within an order of magnitude. The measured K(oc) values decreased in the order of fenbendazole, albendazole, thiabendazole and flubendazole for sewage sludge and hydroxypropyl-beta-cyclodextrin whereas the orders were different for the other DOM surrogates, implying the hydrophilic nature of sewage sludge. This was also supported by the (N+O)/C elemental ratio of the sewage sludge sample used in this study. The correlations between log K(oc) and log K(ow) were weak (r(2)=0.28-0.64) and the magnitude of the sorption coefficients to the hydrophilic organic matters (hydroxypropyl-beta-cyclodextrin and sewage sludge) were similar to or slightly smaller than those for the hydrophobic organic matters (humic acids and liposome). This suggests that specific hydrophilic interactions also play a significant role in the sorption of moderately hydrophobic benzimidazoles to organic matters. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

Soil Organic Matter Dynamics in the Rothamsted Long-term Experiments

NASA Astrophysics Data System (ADS)

MacDonald, A.; Poulton, P.

2009-04-01

Soil science research at Rothamsted dates from 1843 when John Bennet Lawes and Joseph Henry Gilbert started the first of a series of what became long-term field experiments. The main object of these experiments was to examine the effect of inorganic and organic fertilisers and manures on crop yield and soil fertility. These "Classical Field Experiments" included studies on winter wheat (Broadbalk 1843), spring barley (Hoos Barley 1852) and permanent grassland (Park Grass 1856). Additional experiments were established in the 20th century to examine the value of ley-arable cropping, including the Highfield and Fosters Ley-arable experiments (1948) and the Woburn Ley-arable experiment (1938). More recently, the effects of incorporating organic manures and cereal straw have been examined. Early results quickly showed the benefits of inorganic N and P fertilisers on crop production, but the effects of contrasting land uses and management practices on soil properties emerged more slowly. Measurements of soil organic carbon (C) and nitrogen (N) in soils taken at intervals from the long-term experiments indicate that the rate of soil organic matter (SOM) accumulation is controlled largely by the balance between the rate of organic matter inputs and its oxidation rate, and that these are strongly influenced by land use and management, soil texture (especially clay content) and climate. A recent examination of soil organic C data from two long-term grassland experiments in the UK (including Park Grass) indicates that any changes observed in soil organic C under long-term grasslands over the past 40 years are more likely to be due to changes in land use and management rather than climate change. Data from the Rothamsted Long-term experiments have been used to develop and test biogeochemical models of C and N dynamics. In particular, the Roth-C model has successfully simulated soil C dynamics in the long-term experiments at Rothamsted and elsewhere. This model uses several

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.

Dry matter yields and quality of forages derived from grass species and organic production methods (year 111).

PubMed

Pholsen, S; Rodchum, P; Higgs, D E B

2014-07-01

This third year work was carried on at Khon Kaen University during the 2008-2009 to investigate dry matter yields of grass, grass plus legumes, grown on Korat soil series (Oxic Paleustults). The experiment consisted of twelve-treatment combinations of a 3x4 factorial arranged in a Randomized Complete Block Design (RCBD) with four replications. The results showed that Dry Matter Yields (DMY) of Ruzi and Guinea grass were similar with mean values of 6,585 and 6,130 kg ha(-1) whilst Napier gave the lowest (884 kg ha(-1)). With grass plus legume, grass species and production methods gave highly significant dry matter yields where Guinea and Ruzi gave dry matter yields of 7,165 and 7,181 kg ha(-1), respectively and Napier was the least (2,790 kg ha(-1)). The production methods with the use of cattle manure gave the highest DMY (grass alone) of 10,267 kg ha(-1) followed by Wynn and Verano with values of 6,064 and 3,623 kg ha(-1), respectively. Guinea plus cattle manure gave the highest DMY of 14,599 kg ha(-1) whilst Ruzi gave 12,977 kg ha(-1). Guinea plus Wynn gave DMY of 7,082 kg ha(-1). Ruzi plus Verano gave DMY of 6,501 kg ha(-1). Forage qualities of crude protein were highest with those grown with grass plus legumes. Some prospects in improving production were discussed.

The impact of silver nanoparticles on the co-composting of sewage sludge and agricultural waste: Evolutions of organic matter and nitrogen.

PubMed

Zhang, Lihua; Zeng, Guangming; Dong, Haoran; Chen, Yaoning; Zhang, Jiachao; Yan, Ming; Zhu, Yuan; Yuan, Yujie; Xie, Yankai; Huang, Zhenzhen

2017-04-01

This study evaluated the influence of silver nanoparticles (AgNPs) on evolutions of organic matter and nitrogen during co-composting of sewage sludge and agricultural waste. Two co-composting piles were conducted, one was treated without AgNPs (pile 1) and the other with AgNPs (pile 2). Results showed that the AgNPs affected the quality of final composts. Less organic matter (OM) losses were determined in pile 2 (57.96%) than pile 1 (61.66%). 27.22% and 30.1% of the initial total organic matter (TOC) was decomposed in pile 1 and pile 2, respectively. The final water soluble carbon (WSC) concentration in pile 2 was 23559.27mg/kg DW compost which was significantly lower than pile 1 (25642.75mg/kg DW compost). Changes of different forms of nitrogen in the two piles showed that AgNPs could reduce the losses of TN but increase the losses of mineral N. Copyright © 2017 Elsevier Ltd. All rights reserved.

Microbial and long-range terrestrial contributions of organic matter to Antarctica

NASA Astrophysics Data System (ADS)

Antony, R.; Grannas, A. M.; Priest, A. S.; Sleighter, R. L.; Meloth, T.; Hatcher, P.

2012-12-01

Composition and cycling of dissolved organic matter in glacial systems is important because of its great significance to global carbon dynamics, snow photochemistry, and air-snow exchange processes. But, due to the trace nature of specific organic components in Polar ice sheets, detecting and studying these species in molecular level detail has been an analytical challenge. Electrospray ionization coupled with Fourier transform ion cyclotron resonance mass spectrometry (ESI FT-ICR MS) enabled the elucidation of molecular level details of natural organic matter in snow samples collected along a coast to inland transect from the Princesses Elizabeth Land, East Antarctica. Thousands of distinct molecular species comprising of different compound classes were identified providing clues to the nature and sources of organic carbon in Antarctic snow. The major biochemical classes of compounds detected were lignins, tannins, carbohydrates, proteins, amino sugars, lipids, unsaturated hydrocarbons and condensed aromatics. Specifically, lignin molecules comprising up to 50% and compounds derived from algal and microbial biomass comprising up to 45% of the total assigned formulas dominated the organic carbon pool. The identification of a variety of lignin compounds demonstrates substantial input of vascular plant-derived materials to the identified molecular species, presumably from long range atmospheric transport and deposition. The detection of proteins, lipids and amino sugars suggests that a large proportion of the identified supraglacial organic matter likely originates from in situ microbial activity. This corroborates well with the presence of significant numbers of bacteria, picoplankton and microalgae in these samples. These results suggest that organic matter in the supraglacial environments have both a microbial and terrestrial provenance.

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

Characterizing Dissolved Organic Matter (DOM) Isolated From Specific Allochthonous and Autochthonous Sources in a North-Temperate Stream Ecosystem

NASA Astrophysics Data System (ADS)

Wong, J. C.; Williams, D.

2009-05-01

Detrital energy in temperate headwater streams is mainly derived from the annual input of leaf litter from the surrounding landscape. Presumably, its decomposition and other sources of autochthonous organic matter will change dissolved organic carbon (DOC) concentrations and dissolved organic matter (DOM) quality. To investigate this, DOM was leached from two allochthonous sources: white birch (Betula papyrifera) and white cedar (Thuja occidentalis); and one autochthonous source, streambed biofilm, for a period of 7 days on 3 separate occasions in fall 2007. As a second treatment, microorganisms from the water column were filtered out. Deciduous leaf litter was responsible for high, short-term increases to DOC concentrations whereas the amounts leached from conifer needles were relatively constant in each month. Using UV spectroscopy, changes to DOM characteristics like aromaticity, spectral slopes, and molecular weight were mainly determined by source and indicated a preferential use of the labile DOM pool by the microorganisms. Excitation-emission matrices (EEMs) collected using fluorescence spectroscopy suggested that cedar litter was an important source of protein-like fluorescence and that the nature of the fluorescing DOM components changed in the presence of microorganisms. This study demonstrates that simultaneous examination of DOC concentrations and DOM quality will allow a better understanding of the carbon dynamics that connect terrestrial with aquatic ecosystems.

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

NASA Technical Reports Server (NTRS)

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

2001-01-01

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

Anthropogenic N deposition increases soil organic matter accumulation without altering its biochemical composition.

PubMed

Zak, Donald R; Freedman, Zachary B; Upchurch, Rima A; Steffens, Markus; Kögel-Knabner, Ingrid

2017-02-01

Accumulating evidence indicates that future rates of atmospheric N deposition have the potential to increase soil C storage by reducing the decay of plant litter and soil organic matter (SOM). Although the microbial mechanism underlying this response is not well understood, a decline in decay could alter the amount, as well as biochemical composition of SOM. Here, we used size-density fractionation and solid-state 13 C-NMR spectroscopy to explore the extent to which declines in microbial decay in a long-term (ca. 20 yrs.) N deposition experiment have altered the biochemical composition of forest floor, bulk mineral soil, as well as free and occluded particulate organic matter. Significant amounts of organic matter have accumulated in occluded particulate organic matter (~20%; oPOM); however, experimental N deposition had not altered the abundance of carboxyl, aryl, alkyl, or O/N-alkyl C in forest floor, bulk mineral soil, or any soil fraction. These observations suggest that biochemically equivalent organic matter has accumulated in oPOM at a greater rate under experimental N deposition, relative to the ambient treatment. Although we do not understand the process by which experimental N deposition has fostered the occlusion of organic matter by mineral soil particles, our results highlight the importance of interactions among the products of microbial decay and the chemical and physical properties of silt and clay particles that occlude organic matter from microbial attack. Because oPOM can reside in soils for decades to centuries, organic matter accumulating under future rates of anthropogenic N deposition could remain in soil for long periods of time. If temperate forest soils in the Northern Hemisphere respond like those in our experiment, then unabated deposition of anthropogenic N from the atmosphere has the potential to foster greater soil C storage, especially in fine-texture forest soils. © 2016 John Wiley & Sons Ltd.

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

USGS Publications Warehouse

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

2007-01-01

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

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

PubMed

Herckes, Pierre; Leenheer, Jerry A; Collett, Jeffrey L

2007-01-15

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

Using In-Situ Optical Sensors to Understand the Biogeochemistry of Dissolved Organic Matter Across a Stream Network

NASA Astrophysics Data System (ADS)

Wymore, Adam S.; Potter, Jody; Rodríguez-Cardona, Bianca; McDowell, William H.

2018-04-01

The advent of high-frequency in situ optical sensors provides new opportunities to study the biogeochemistry of dissolved organic matter (DOM) in aquatic ecosystems. We used fDOM (fluorescent dissolved organic matter) to examine the spatial and temporal variability in dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) across a heterogeneous stream network that varies in NO3- concentration. Across the ten study streams fDOM explained twice the variability in the concentration of DOC (r2 = 0.82) compared to DON (r2 = 0.39), which suggests that the N-rich fraction of DOM is either more variable in its sources or more bioreactive than the more stable C-rich fraction. Among sites, DON molar fluorescence was approximately 3x more variable than DOC molar fluorescence and was correlated with changes in inorganic N, indicating that DON is both more variable in composition as well as highly responsive to changes in inorganic N. Laboratory results also indicate that the fDOM sensors we used perform as well as the excitation-emission wavelength pair generally referred to as the "tryptophan-like" peak when measured under laboratory conditions. However, since neither the field sensor not the laboratory measurements explained a large percentage of variation in DON concentrations, challenges still remain for monitoring the ambient pool of dissolved organic nitrogen. Sensor networks provide new insights into the potential reactivity of DOM and the variability in DOC and DON biogeochemistry across sites. These insights are needed to build spatially explicit models describing organic matter dynamics and water quality.

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

EPA Science Inventory

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

Long-term citrus organic farming strategy results in soil organic matter recovery

NASA Astrophysics Data System (ADS)

Novara, Agata; Pereira, Paulo; Barone, Ettore; Giménez Morera, Antonio; Keesstra, Saskia; Gristina, Luciano; Jordán, Antonio; Parras-Alcantara, Luis; Cerdà, Artemi

2017-04-01

.: The significance of soils and soil science towards realization of the United Nations Sustainable Development Goals, SOIL, 2, 111-128, doi:10.5194/soil-2-111-2016, 2016. Keesstra, S.D., Geissen, V., van Schaik, L., Mosse., K., Piiranen, S., 2012. Soil as a filter for groundwater quality. Current Opinions in Environmental Sustainability 4, 507-516. doi:10.1016/j.cosust.2012.10.007 Laudicina, V. A., A. Novara, V. Barbera, M. Egli, and L. Badalucco. 2015. Long-Term Tillage and Cropping System Effects on Chemical and Biochemical Characteristics of Soil Organic Matter in a Mediterranean Semiarid Environment. Land Degradation and Development 26 (1): 45-53. doi:10.1002/ldr.2293. Mol, G., Keesstra, S.D., 2012. Editorial: Soil science in a changing world. Current Opinions in Environmental Sustainability 4: 473-477. Novara, A., L. Gristina, M. B. Bodì, and A. Cerdà. 2011. The Impact of Fire on Redistribution of Soil Organic Matter on a Mediterranean Hillslope Under Maquia Vegetation Type. Land Degradation and Development 22 (6): 530-536. doi:10.1002/ldr.1027. Parras-Alcántara, L., B. Lozano-García, E. C. Brevik, and A. Cerdá. 2015. Soil Organic Carbon Stocks Assessment in Mediterranean Natural Areas: A Comparison of Entire Soil Profiles and Soil Control Sections. Journal of Environmental Management 155: 219-228. doi:10.1016/j.jenvman.2015.03.039. Parras-Alcántara, L., B. Lozano-García, S. Keesstra, A. Cerdà, and E. C. Brevik. 2016. Long-Term Effects of Soil Management on Ecosystem Services and Soil Loss Estimation in Olive Grove Top Soils. Science of the Total Environment. doi:10.1016/j.scitotenv.2016.07.016.

Turnover of intra- and extra-aggregate organic matter at the silt-size scale

Treesearch

I. Virto; C. Moni; C. Swanston; C. Chenu

2010-01-01

Temperate silty soils are especially sensitive to organic matter losses associated to some agricultural management systems. Long-term preservation of organic C in these soils has been demonstrated to occur mainly in the silt- and clay-size fractions, although our knowledge about the mechanisms through which it happens remains unclear. Although organic matter in such...

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

ERIC Educational Resources Information Center

Clarkson, W. W.; And Others

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

78 FR 23524 - Approval and Promulgation of Air Quality Implementation Plans; Indiana; Particulate Matter...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-04-19

... Promulgation of Air Quality Implementation Plans; Indiana; Particulate Matter Ambient Air Quality Standards... revise the Indiana State Implementation Plan (SIP) for particulate matter under the Clean Air Act. This submission contains the 24-hour fine particle National Ambient Air Quality Standards (NAAQS) promulgated by...

Effect of biochar amendment on compost organic matter composition following aerobic composting of manure.

PubMed

Hagemann, Nikolas; Subdiaga, Edisson; Orsetti, Silvia; de la Rosa, José María; Knicker, Heike; Schmidt, Hans-Peter; Kappler, Andreas; Behrens, Sebastian

2018-02-01

Biochar, a material defined as charred organic matter applied in agriculture, is suggested as a beneficial additive and bulking agent in composting. Biochar addition to the composting feedstock was shown to reduce greenhouse gas emissions and nutrient leaching during the composting process, and to result in a fertilizer and plant growth medium that is superior to non-amended composts. However, the impact of biochar on the quality and carbon speciation of the organic matter in bulk compost has so far not been the focus of systematic analyses, although these parameters are key to determine the long-term stability and carbon sequestration potential of biochar-amended composts in soil. In this study, we used different spectroscopic techniques to compare the organic carbon speciation of manure compost amended with three different biochars. A non-biochar-amended compost served as control. Based on Fourier-transformed infrared (FTIR) and 13 C nuclear magnetic resonance (NMR) spectroscopy we did not observe any differences in carbon speciation of the bulk compost independent of biochar type, despite a change in the FTIR absorbance ratio 2925cm -1 /1034cm -1 , that is suggested as an indicator for compost maturity. Specific UV absorbance (SUVA) and emission-excitation matrixes (EEM) revealed minor differences in the extractable carbon fractions, which only accounted for ~2-3% of total organic carbon. Increased total organic carbon content of biochar-amended composts was only due to the addition of biochar-C and not enhanced preservation of compost feedstock-C. Our results suggest that biochars do not alter the carbon speciation in compost organic matter under conditions optimized for aerobic decomposition of compost feedstock. Considering the effects of biochar on compost nutrient retention, mitigation of greenhouse gas emissions and carbon sequestration, biochar addition during aerobic composting of manure might be an attractive strategy to produce a sustainable, slow

Molecular characterization of macrophyte-derived dissolved organic matters and their implications for lakes

USDA-ARS?s Scientific Manuscript database

Chemical properties of whole organic matter (OM) and its dissolved organic matter (DOM) fraction from six dominant macrophytes in Lake Dianchi were comparatively characterized, and their environmental implications were discussed. Significant differences in chemical composition of the OM samples were...

Organic Matter Decomposition following Harvesting and Site Preparation of a Forested Wetland

Treesearch

Carl C. Trettin; M. Davidian; M.F. Jurgensen; R. Lea

1996-01-01

Organic matter accumulation is an important process that affects ecosystem function in many northern wetlands. The cotton strip assay (CSA)was used to measure the effect of harvesting and two different site preparation treatments, bedding and trenching, on organic matter decomposition in a forested wetland. A Latin square experimental design was used to determine the...

Explaining the apparent resiliency of loblolly pine plantation to organic matter removal

Treesearch

Jeff A. Hatten; Eric B. Surce; Zakiya Leggett; Jason Mack; Scott D. Roberts; Janet Dewey; Brian Strahm

2015-01-01

We utilized 15-year measurements from an organic matter manipulation experiment in a loblolly pine plantation in the Upper Coastal Plain of Alabama to examine the apparent resiliency of a loblolly pine stand to organic matter removal. Treatments included complete removal of harvest residues and forest floor (removed), doubling of harvest residues and forest floor (...

The surface area of soil organic matter

USGS Publications Warehouse

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

1990-01-01

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

Rare earth elements and neodymium isotopes in sedimentary organic matter

NASA Astrophysics Data System (ADS)

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

2014-09-01

We report rare earth element (REE) and neodymium (Nd) isotope data for the organic fraction of sediments collected from various depositional environments, i.e. rivers (n = 25), estuaries (n = 18), open-ocean settings (n = 15), and cold seeps (n = 12). Sedimentary organic matter (SOM) was extracted using a mixed hydrogen peroxide/nitric acid solution (20%-H2O2-0.02 M-HNO3), after removal of carbonate and oxy-hydroxide phases with dilute hydrochloric acid (0.25 M-HCl). A series of experimental tests indicate that extraction of sedimentary organic compounds using H2O2 may be complicated occasionally by partial dissolution of sulphide minerals and residual carbonates. However, this contamination is expected to be minor for REE because measured concentrations in H2O2 leachates are about two-orders of magnitude higher than in the above mentioned phases. The mean REE concentrations determined in the H2O2 leachates for samples from rivers, estuaries, coastal seas and open-ocean settings yield relatively similar levels, with ΣREE = 109 ± 86 ppm (mean ± s; n = 58). The organic fractions leached from cold seep sediments display even higher concentration levels (285 ± 150 ppm; mean ± s; n = 12). The H2O2 leachates for most sediments exhibit remarkably similar shale-normalized REE patterns, all characterized by a mid-REE enrichment compared to the other REE. This suggests that the distribution of REE in leached sedimentary organic phases is controlled primarily by biogeochemical processes, rather than by the composition of the source from which they derive (e.g. pore, river or sea-water). The Nd isotopic compositions for organic phases leached from river sediments are very similar to those for the corresponding detrital fractions. In contrast, the SOM extracted from marine sediments display εNd values that typically range between the εNd signatures for terrestrial organic matter (inferred from the analysis of the sedimentary detrital fractions) and marine organic matter

Vertical distribution of bacterial community is associated with the degree of soil organic matter decomposition in the active layer of moist acidic tundra.

PubMed

Kim, Hye Min; Lee, Min Jin; Jung, Ji Young; Hwang, Chung Yeon; Kim, Mincheol; Ro, Hee-Myong; Chun, Jongsik; Lee, Yoo Kyung

2016-11-01

The increasing temperature in Arctic tundra deepens the active layer, which is the upper layer of permafrost soil that experiences repeated thawing and freezing. The increasing of soil temperature and the deepening of active layer seem to affect soil microbial communities. Therefore, information on soil microbial communities at various soil depths is essential to understand their potential responses to climate change in the active layer soil. We investigated the community structure of soil bacteria in the active layer from moist acidic tundra in Council, Alaska. We also interpreted their relationship with some relevant soil physicochemical characteristics along soil depth with a fine scale (5 cm depth interval). The bacterial community structure was found to change along soil depth. The relative abundances of Acidobacteria, Gammaproteobacteria, Planctomycetes, and candidate phylum WPS-2 rapidly decreased with soil depth, while those of Bacteroidetes, Chloroflexi, Gemmatimonadetes, and candidate AD3 rapidly increased. A structural shift was also found in the soil bacterial communities around 20 cm depth, where two organic (upper Oi and lower Oa) horizons are subdivided. The quality and the decomposition degree of organic matter might have influenced the bacterial community structure. Besides the organic matter quality, the vertical distribution of bacterial communities was also found to be related to soil pH and total phosphorus content. This study showed the vertical change of bacterial community in the active layer with a fine scale resolution and the possible influence of the quality of soil organic matter on shaping bacterial community structure.

Seasonal changes in the chemical quality and biodegradability of dissolved organic matter exported from soils to streams in coastal temperate rainforest watersheds

Treesearch

Jason B. Fellman; Eran Hood; David V. D' Amore; Richard T. Edwards; Dan White

2009-01-01

The composition and biodegradability of streamwater dissolved organic matter (DOM) varies with source material and degree of transformation. We combined PARAFAC modeling of fluorescence excitation-emission spectroscopy and biodegradable dissolved organic carbon (BDOC) incubations to investigate seasonal changes in the lability of DOM along a soil-stream continuum in...

Final Technical Report: Mercury Release from Organic Matter (OM) and OM-Coated Mineral Surfaces

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

Nagy, Kathryn L.

2015-08-18

Chemical reactions between mercury, a neurotoxin, and sulfur, an essential nutrient, in the environment control to a large extent the distribution and amount of mercury available for uptake by living organisms. The largest reservoir of sulfur in soils is in living, decaying, and dissolved natural organic matter. The decaying and dissolved organic matter can also coat the surfaces of minerals in the soil. Mercury (as a divalent cation) can bind to the sulfur species in the organic matter as well as to the bare mineral surfaces, but the extent of binding and release of this mercury is not well understood.more » The goals of the research were to investigate fundamental relationships among mercury, natural organic matter, and selected minerals to better understand specifically the fate and transport of mercury in contaminated soils downstream from the Y-12 plant along East Fork Poplar Creek, Tennessee, and more generally in any contaminated soil. The research focused on (1) experiments to quantify the uptake and release of mercury from two clay minerals in the soil, kaolinite and vermiculite, in the presence and absence of dissolved organic matter; (2) release of mercury from cinnabar under oxic and anoxic conditions; (3) characterization of the forms of mercury in the soil using synchrotron X-ray absorption spectroscopic techniques; and, (4) determination of molecular forms of mercury in the presence of natural organic matter. We also leveraged funding from the National Science Foundation to (5) evaluate published approaches for determining sulfur speciation in natural organic matter by fitting X-ray Absorption Near Edge Structure (XANES) spectra obtained at the sulfur K-edge and apply optimized fitting schemes to new measurements of sulfur speciation in a suite of dissolved organic matter samples from the International Humic Substances Society. Lastly, in collaboration with researchers at the University of Colorado and the U.S. Geological Survey in Boulder

High-molecular-weight organic matter in the particles of comet 67P/Churyumov-Gerasimenko.

PubMed

Fray, Nicolas; Bardyn, Anaïs; Cottin, Hervé; Altwegg, Kathrin; Baklouti, Donia; Briois, Christelle; Colangeli, Luigi; Engrand, Cécile; Fischer, Henning; Glasmachers, Albrecht; Grün, Eberhard; Haerendel, Gerhard; Henkel, Hartmut; Höfner, Herwig; Hornung, Klaus; Jessberger, Elmar K; Koch, Andreas; Krüger, Harald; Langevin, Yves; Lehto, Harry; Lehto, Kirsi; Le Roy, Léna; Merouane, Sihane; Modica, Paola; Orthous-Daunay, François-Régis; Paquette, John; Raulin, François; Rynö, Jouni; Schulz, Rita; Silén, Johan; Siljeström, Sandra; Steiger, Wolfgang; Stenzel, Oliver; Stephan, Thomas; Thirkell, Laurent; Thomas, Roger; Torkar, Klaus; Varmuza, Kurt; Wanczek, Karl-Peter; Zaprudin, Boris; Kissel, Jochen; Hilchenbach, Martin

2016-10-06

The presence of solid carbonaceous matter in cometary dust was established by the detection of elements such as carbon, hydrogen, oxygen and nitrogen in particles from comet 1P/Halley. Such matter is generally thought to have originated in the interstellar medium, but it might have formed in the solar nebula-the cloud of gas and dust that was left over after the Sun formed. This solid carbonaceous material cannot be observed from Earth, so it has eluded unambiguous characterization. Many gaseous organic molecules, however, have been observed; they come mostly from the sublimation of ices at the surface or in the subsurface of cometary nuclei. These ices could have been formed from material inherited from the interstellar medium that suffered little processing in the solar nebula. Here we report the in situ detection of solid organic matter in the dust particles emitted by comet 67P/Churyumov-Gerasimenko; the carbon in this organic material is bound in very large macromolecular compounds, analogous to the insoluble organic matter found in the carbonaceous chondrite meteorites. The organic matter in meteorites might have formed in the interstellar medium and/or the solar nebula, but was almost certainly modified in the meteorites' parent bodies. We conclude that the observed cometary carbonaceous solid matter could have the same origin as the meteoritic insoluble organic matter, but suffered less modification before and/or after being incorporated into the comet.

The composition and degradability of upland dissolved organic matter

NASA Astrophysics Data System (ADS)

Moody, Catherine; Worrall, Fred; Clay, Gareth

2016-04-01

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

Characterizing Variability In Ohio River Natural Organic Matter

EPA Science Inventory

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

Photodegradation of Pyrogenic Dissolved Organic Matter (Biochar Leachates)

NASA Astrophysics Data System (ADS)

Bostick, K. W.; Zimmerman, A. R.; Hatcher, P.; Mitra, S.; Wozniak, A. S.

2017-12-01

A large portion of soil organic matter has been suggested to be pyrogenic (e.g., charred biomass or soot). While pyrogenic organic matter has been regarded as relatively stable in the environment, significant losses of pyrogenic organic carbon can occur via degradation and solubilization. Pyrogenic dissolved organic matter (py-DOM) could be an important intermediate in global C cycling, however its geochemical fate is still unknown. In the current study, the mineralization and transformation of py-DOM were explored through a series of photodegradation experiments. A biochar prepared by pyrolyzing oak wood at 400 °C was leached for a period of 48 hours. This leachate was exposed to light simulating the irradiance and spectra of natural sunlight from 295 to 365 nm. Photodegraded leachate was subsampled during a period of 20 days and analyzed for TOC, DIC and TN. Additionally, solid phase (PPL) extracts of leachate DOM were oxidized in hot nitric acid and analyzed via HPLC for benzenepolycarboxylic acids (BPCAs). In previous studies, the proportion of aromatically condensed py-DOM (as indicated carboxyl substitution in BPCA) in biochar leachates was found to increase with parent char pyrolysis temperature. Thus, to explore the influence of py-DOM type on photodegradation, losses of C, N, and condensed aromatic C were examined in leachates of an oak biochar thermal series (pyrolyzed at 400, 525, 650 °C). The resulting rates of photo-degradative losses in py-C and condensed aromatics in these leachates can be used to estimate the stability/longevity of py-DOM in aquatic systems, potential for py-DOM export from terrestrial systems, and negative effects to aquatic ecosystems.

Molecular fractionation of dissolved organic matter with metal salts.

PubMed

Riedel, Thomas; Biester, Harald; Dittmar, Thorsten

2012-04-17

Coagulation of dissolved organic matter (DOM) by hydrolyzing metals is an important environmental process with particular relevance, e.g., for the cycling of organic matter in metal-rich aquatic systems or the flocculation of organic matter in wastewater treatment plants. Often, a nonremovable fraction of DOM remains in solution even at low DOM/metal ratios. Because coagulation by metals results from interactions with functional groups, we hypothesize that noncoagulating fractions have a distinct molecular composition. To test the hypothesis, we analyzed peat-derived dissolved organic matter remaining in solution after mixing with salts of Ca, Al, and Fe using 15 T Electrospray Ionization Fourier-Transform Ion Cyclotron Resonance Mass Spectrometry (ESI-FT-ICR-MS). Addition of metals resulted in a net removal of DOM. Also a reduction of molecular diversity was observed, as the number of peaks from the ESI-FT-ICR-MS spectra decreased. At DOM/metal ratios of ∼9 Ca did not show any preference for distinct molecular fractions, while Fe and Al removed preferentially the most oxidized compounds (O/C ratio >0.4) of the peat leachate. Lowering DOM/metal ratios to ∼1 resulted in further removal of less oxidized as well as more aromatic compounds ("black carbon"). Molecular composition in the residual solution after coagulation was more saturated, less polar, and less oxidized compared to the original peat leachate and exhibited a surprising similarity with DOM of marine origin. By identifying more than 9200 molecular formulas we can show that structural properties (saturation and aromaticity) and oxygen content of individual DOM molecules play an important role in coagulation with metals. We conclude that polyvalent cations not only alter the net mobility but also the very molecular composition of DOM in aquatic environments.

Quality and Safety Matter

NASA Astrophysics Data System (ADS)

Manha, William D.

2010-09-01

,(the presenter) 0 injuries, 0 deaths 3. March 18, 1980,(USSR) Vostok 8A92M booster pad explosion, 48 deaths. 4. August 22, 2003,(Brazil) -Alcantara VLS -1, V03. Solid rocket ignited on pad, 21 deaths 5. Summer of 2006(USA) a payload organization inquired about requirements to fly a satellite with a new “safe” SpaceDev hybrid propulsion system using a solid polymer as the fuel and nitrous oxide as the oxidizer. The extensive titanium/nitrous oxide materials compatibility testing that was required discouraged the payload organization from further exploration of using the Shuttle as the launch vehicle. 6. July 26, 2007(USA) SpaceShipTwo nitrous oxide explosion, 3 seriously injured, 3 deaths The above listed catastrophic failures resulted in 210 deaths, but there were none on the Apollo SM explosion because of compliance with CalOSHA. This is an applied lesson learned of the Shuttle. Safety was not jeopardized without extensive materials compatibility testing. On the other hand, the nitrous oxide was erroneously identified as safe for launch from Shuttle or ISS which resulted in a catastrophic explosion and resulted in 3 major injuries, and 3 deaths. This is a testimony of a survivor of a catastrophic failure where safety rules were followed and the application of the lesson learned which confirmed safety and quality, as expressed by Von Braun, PERFECTION and SAFETY do MATTER!

Beneficial effect of mixture of additives amendment on enzymatic activities, organic matter degradation and humification during biosolids co-composting.

PubMed

Awasthi, Mukesh Kumar; Wang, Quan; Chen, Hongyu; Awasthi, Sanjeev Kumar; Wang, Meijing; Ren, Xiuna; Zhao, Junchao; Zhang, Zengqiang

2018-01-01

The objective of this study was to identify the effect of mixture of additives to improve the enzymatic activities, organic matter humification and diminished the bioavailability of heavy metals (HMs) during biosolids co-composting. In this study, zeolite (Z) (10%, 15% and 30%) with 1%lime (L) (dry weight basis of biosolids) was blended into the mixture of biosolids and wheat straw, respectively. The without any amendment and 1%lime applied treatments were run for comparison (Control). The Z+L addition resulted rapid organic matter degradation and humification with maximum enzymatic activities. In addition, higher dosage of Z+1%L amendment reduced the bioavailability of HMs (Cu and Zn) and improved the end product quality as compared to control and 1%L applied treatments. However, the 30%Z+1%L applied treatment showed maximum humification and low bioavailability of HMs but considering the economic feasibility and compost quality results, the treatment with 10%Z+1%L is recommended for biosolids co-composting. Copyright © 2017 Elsevier Ltd. All rights reserved.

Molecular weight distribution of organic matter by ozonation and biofiltration.

PubMed

Lin, Yen-Hui

2012-01-01

Molecular weight (MW) distribution of organic matter by ozonation and biofiltration was evaluated using gel chromatography. The MW distribution of organic matter by Sephadex G-25 was observed from groups 2 (MW = 1,029-7,031 g/mol) and 3 (MW = 303-1,029 g/mol) shifted to groups 2, 3 and 4 (MW < 303 g/mol) under ozone doses of 0.1 and 0.4 mg O₃/mg total organic carbon (TOC). The shift in MW increases as ozone dosage increases. Biofiltration effectively degraded the organic molecule of group 2; however, the biofiltration only slightly degraded the organic molecule of group 4. Increased ozone dose destroyed functional groups C═C in phenolic and C-O in alcoholic compounds and increased UV-insensitive biodegradable organic carbon for subsequent biofiltration. Biofiltration effectively degraded organic compounds of alcohols and alkenes at an ozone dose of 0.1 mg O₃/mg TOC. Experimental approaches in this study can be applied to evaluate and diagnose the function of a full-scale process combining ozonation and biofiltration in drinking water treatment plants.

Characterisation of the biodegradability of post-treated digestates via the chemical accessibility and complexity of organic matter.

PubMed

Maynaud, Géraldine; Druilhe, Céline; Daumoin, Mylène; Jimenez, Julie; Patureau, Dominique; Torrijos, Michel; Pourcher, Anne-Marie; Wéry, Nathalie

2017-05-01

The stability of digestate organic matter is a key parameter for its use in agriculture. Here, the organic matter stability was compared between 14 post-treated digestates and the relationship between organic matter complexity and biodegradability was highlighted. Respirometric activity and CH 4 yields in batch tests showed a positive linear correlation between both types of biodegradability (R 2 =0.8). The accessibility and complexity of organic matter were assessed using chemical extractions combined with fluorescence spectroscopy, and biodegradability was mostly anti-correlated with complexity of organic matter. Post-treatments presented a significant effect on the biodegradability and complexity of organic matter. Biodegradability was low for composted digestates which comprised slowly accessible complex molecules. Inversely, solid fractions obtained after phase separation contained a substantial part of remaining biodegradable organic matter with a significant easily accessible fraction comprising simpler molecules. Understanding the effect of post-treatment on the biodegradability of digestates should help to optimize their valorization. Copyright © 2017 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

Production of fluorescent dissolved organic matter in Arctic Ocean sediments.

PubMed

Chen, Meilian; Kim, Ji-Hoon; Nam, Seung-Il; Niessen, Frank; Hong, Wei-Li; Kang, Moo-Hee; Hur, Jin

2016-12-16

Little is known about the production of fluorescent dissolved organic matter (FDOM) in the anoxic oceanic sediments. In this study, sediment pore waters were sampled from four different sites in the Chukchi-East Siberian Seas area to examine the bulk dissolved organic carbon (DOC) and their optical properties. The production of FDOM, coupled with the increase of nutrients, was observed above the sulfate-methane-transition-zone (SMTZ). The presence of FDOM was concurrent with sulfate reduction and increased alkalinity (R 2  > 0.96, p < 0.0001), suggesting a link to organic matter degradation. This inference was supported by the positive correlation (R 2  > 0.95, p < 0.0001) between the net production of FDOM and the modeled degradation rates of particulate organic carbon sulfate reduction. The production of FDOM was more pronounced in a shallow shelf site S1 with a total net production ranging from 17.9 to 62.3 RU for different FDOM components above the SMTZ depth of ca. 4.1 mbsf, which presumably underwent more accumulation of particulate organic matter than the other three deeper sites. The sediments were generally found to be the sources of CDOM and FDOM to the overlying water column, unearthing a channel of generally bio-refractory and pre-aged DOM to the oceans.

Production of fluorescent dissolved organic matter in Arctic Ocean sediments

NASA Astrophysics Data System (ADS)

Chen, Meilian; Kim, Ji-Hoon; Nam, Seung-Il; Niessen, Frank; Hong, Wei-Li; Kang, Moo-Hee; Hur, Jin

2016-12-01

Little is known about the production of fluorescent dissolved organic matter (FDOM) in the anoxic oceanic sediments. In this study, sediment pore waters were sampled from four different sites in the Chukchi-East Siberian Seas area to examine the bulk dissolved organic carbon (DOC) and their optical properties. The production of FDOM, coupled with the increase of nutrients, was observed above the sulfate-methane-transition-zone (SMTZ). The presence of FDOM was concurrent with sulfate reduction and increased alkalinity (R2 > 0.96, p < 0.0001), suggesting a link to organic matter degradation. This inference was supported by the positive correlation (R2 > 0.95, p < 0.0001) between the net production of FDOM and the modeled degradation rates of particulate organic carbon sulfate reduction. The production of FDOM was more pronounced in a shallow shelf site S1 with a total net production ranging from 17.9 to 62.3 RU for different FDOM components above the SMTZ depth of ca. 4.1 mbsf, which presumably underwent more accumulation of particulate organic matter than the other three deeper sites. The sediments were generally found to be the sources of CDOM and FDOM to the overlying water column, unearthing a channel of generally bio-refractory and pre-aged DOM to the oceans.

Production of fluorescent dissolved organic matter in Arctic Ocean sediments

PubMed Central

Chen, Meilian; Kim, Ji-Hoon; Nam, Seung-Il; Niessen, Frank; Hong, Wei-Li; Kang, Moo-Hee; Hur, Jin

2016-01-01

Little is known about the production of fluorescent dissolved organic matter (FDOM) in the anoxic oceanic sediments. In this study, sediment pore waters were sampled from four different sites in the Chukchi-East Siberian Seas area to examine the bulk dissolved organic carbon (DOC) and their optical properties. The production of FDOM, coupled with the increase of nutrients, was observed above the sulfate-methane-transition-zone (SMTZ). The presence of FDOM was concurrent with sulfate reduction and increased alkalinity (R2 > 0.96, p < 0.0001), suggesting a link to organic matter degradation. This inference was supported by the positive correlation (R2 > 0.95, p < 0.0001) between the net production of FDOM and the modeled degradation rates of particulate organic carbon sulfate reduction. The production of FDOM was more pronounced in a shallow shelf site S1 with a total net production ranging from 17.9 to 62.3 RU for different FDOM components above the SMTZ depth of ca. 4.1 mbsf, which presumably underwent more accumulation of particulate organic matter than the other three deeper sites. The sediments were generally found to be the sources of CDOM and FDOM to the overlying water column, unearthing a channel of generally bio-refractory and pre-aged DOM to the oceans. PMID:27982085

Influence of particle and surface quality on the vitrinite reflectance of dispersed organic matter: Comparative exercise using data from the qualifying system for reflectance analysis working group of ICCP

USGS Publications Warehouse

Borrego, A.G.; Araujo, C.V.; Balke, A.; Cardott, B.; Cook, A.C.; David, P.; Flores, D.; Hamor-Vido, M.; Hiltmann, W.; Kalkreuth, W.; Koch, J.; Kommeren, C.J.; Kus, J.; Ligouis, B.; Marques, M.; Mendonca, Filho J.G.; Misz, M.; Oliveira, L.; Pickel, W.; Reimer, K.; Ranasinghe, P.; Suarez-Ruiz, I.; Vieth, A.

2006-01-01

The development of a qualifying system for reflectance analysis has been the scope of a working group within the International Committee for Coal and Organic Petrology (ICCP) since 1999, when J. Koch presented a system to qualify vitrinite particles according to their size, proximity to bright components and homogeneity of the surface. After some years of work aimed at improving the classification system using photomicrographs, it was decided to run a round robin exercise on microscopy samples. The classification system tested consists of three qualifiers ranging from excellent to low quality vitrinites with an additional option for unsuitable vitrinites. This paper reports on the results obtained by 22 analysts who were asked to measure random reflectance readings on vitrinite particles assigning to each reading a qualifier. Four samples containing different organic matter types and a variety of vitrinite occurrences have been analysed. Results indicated that the reflectance of particles classified as excellent, good or poor compared to the total average reflectance did not show trends to be systematically lower or higher for the four samples analysed. The differences in reflectance between the qualifiers for any given sample were lower than the scatter of vitrinite reflectance among participants. Overall, satisfactory results were obtained in determining the reflectance of vitrinite in the four samples analysed. This was so for samples having abundant and easy to identify vitrinites (higher plant-derived organic matter) as well as for samples with scarce and difficult to identify particles (samples with dominant marine-derived organic matter). The highest discrepancies were found for the organic-rich oil shales where the selection of the vitrinite population to measure proved to be particularly difficult. Special instructions should be provided for the analysis of this sort of samples. The certainty of identification of the vitrinite associated with the vitrinite

Organic matter chlorination rates in different boreal soils: the role of soil organic matter content.

PubMed

Gustavsson, Malin; Karlsson, Susanne; Oberg, Gunilla; Sandén, Per; Svensson, Teresia; Valinia, Salar; Thiry, Yves; Bastviken, David

2012-02-07

Transformation of chloride (Cl(-)) to organic chlorine (Cl(org)) occurs naturally in soil but it is poorly understood how and why transformation rates vary among environments. There are still few measurements of chlorination rates in soils, even though formation of Cl(org) has been known for two decades. In the present study, we compare organic matter (OM) chlorination rates, measured by (36)Cl tracer experiments, in soils from eleven different locations (coniferous forest soils, pasture soils and agricultural soils) and discuss how various environmental factors effect chlorination. Chlorination rates were highest in the forest soils and strong correlations were seen with environmental variables such as soil OM content and Cl(-) concentration. Data presented support the hypothesis that OM levels give the framework for the soil chlorine cycling and that chlorination in more organic soils over time leads to a larger Cl(org) pool and in turn to a high internal supply of Cl(-) upon dechlorination. This provides unexpected indications that pore water Cl(-) levels may be controlled by supply from dechlorination processes and can explain why soil Cl(-) locally can be more closely related to soil OM content and the amount organically bound chlorine than to Cl(-) deposition.

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.

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

Methylmercury production in estuarine sediments: role of organic matter

PubMed Central

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

2013-01-01

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

Pleistocene to Holocene contrasts in organic matter production and preservation on the California continental margin

USGS Publications Warehouse

Dean, W.E.; Gardner, J.V.

1998-01-01

Organic matter in sediments from cores collected from the upper continental slope (200-2700 m) off California and southern Oregon shows marked differences in concentration and marine character between the last glacial interval (ca. 24-10 ka) and either Holocene time or last interstadial (oxygen isotope stage 3, ca. 60-24 ka). In general, sediments deposited during Holocene time and stage 3 contain higher amounts of marine organic matter than those deposited during the last glacial interval, and this contrast is greatest in cores collected off southern California. The most profound differences in stage 3 sediments are between predominantly bioturbated sediments and occasional interbeds of laminated sediments. The sediments are from cores collected within the present oxygen minimum zone on the upper continental slope from as far north as the Oregon-California border to as far south as Point Conception. These upper Pleistocene laminated sediments contain more abundant hydrogen-rich (type II) marine algal organic matter than even surface sediments that have large amounts of nonrefractory organic matter. The stable carbon-isotopic composition of the organic matter does not change with time between bioturbated and laminated sediments, indicating that the greater abundance of type II organic matter in the laminated sediments is not due to a change in source but rather represents a greater degree of production and preservation of marine organic matter. The presence of abundant, well-preserved organic matter supports the theory that the oxygen minimum zone in the northeastern Pacific Ocean was more intense, and possibly anoxic, during late Pleistocene time as a result of increased coastal upwelling that enhanced algal productivity.

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...

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)).

Effects of different forms of plant-derived organic matter on nitrous oxide emissions.

PubMed

Qiu, Qingyan; Wu, Lanfang; Ouyang, Zhu; Li, Binbin; Xu, Yanyan

2016-07-13

To investigate the impact of different forms of plant-derived organic matter on nitrous oxide (N2O) emissions, an incubation experiment with the same rate of total nitrogen (N) application was carried out at 25 °C for 250 days. Soils were incorporated with maize-derived organic matter (i.e., maize residue-derived dissolved organic matter and maize residues with different C/N ratios) and an inorganic N fertilizer (urea). The pattern and magnitude of nitrous oxide (N2O) emissions were affected by the form of N applied. Single application of maize-derived organic matter resulted in a higher N2O emission than single application of the inorganic N fertilizer or combined application of the inorganic N fertilizer and maize-derived organic matter. The positive effect of maize residue-derived dissolved organic matter (DOM) addition on N2O emissions was relatively short-lived and mainly occurred at the early stage following DOM addition. In contrast, the positive effect induced by maize residue addition was more pronounced and lasted for a longer period. Single application of maize residues resulted in a substantial decrease in soil nitric nitrogen (NO3(-)-N), but it did not affect the production of N2O. No significant relationship between N2O emission and NO3(-)-N and ammonium nitrogen (NH4(+)-N) suggested that the availability of soil N was not limiting the production of N2O in our study. The key factors affecting soil N2O emission were the soil dissolved organic carbon (DOC) content and metabolism quotient (qCO2). Both of them could explain 87% of the variation in cumulative N2O emission. The C/N ratio of maize-derived organic matter was a poor predictor of N2O emission when the soil was not limited by easily available C and the available N content met the microbial N demands for nitrification and denitrification. The results suggested that the magnitude of N2O emission was determined by the impact of organic amendments on soil C availability and microbial activity

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

NASA Astrophysics Data System (ADS)

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

2015-06-01

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

Is organic matter alone sufficient to predict isoproturon sorption in calcareous soils?

PubMed

El Arfaoui, Achouak; Sayen, Stéphanie; Paris, Michaël; Keziou, Amor; Couderchet, Michel; Guillon, Emmanuel

2012-08-15

Eleven soils collected from Champagne-Ardenne area (France) were used to investigate isoproturon sorption in laboratory conditions. Our results identified the organic matter (OM) and the ratio of calcite content to OM content (Rt) as the main two parameters governing isoproturon retention in soils. While organic matter favored pesticide sorption, calcite had an antagonistic effect since it limited isoproturon retention. The Rt ratio of calcite content to organic matter content in soils appeared to be a parameter that should be considered in predictive models in addition to OM in regions presenting calcareous soils. Adsorption of isoproturon as a function of Rt and OM was successfully described through a simple empirical model. Copyright © 2012 Elsevier B.V. All rights reserved.

Characterization of dissolved organic matter in an urbanized estuary located in Northeastern Brazil.

PubMed

Arguelho, Maria de Lara Palmeira de Macedo; Alves, José do Patrocínio Hora; Monteiro, Adnívia Santos Costa; Garcia, Carlos Alexandre Borges

2017-06-01

The Sal River estuary, which is located in the state of Sergipe, Northeastern Brazil, stands out as an urban estuary, anthropogenically impacted by untreated and treated wastewater discharge. Synchronous fluorescence spectroscopy and measurement of dissolved organic carbon (DOC) were used for characterization of dissolved organic matter (DOM) in the estuarine water. Dissolved organic carbon concentrations ranged from 7.5 to 19.0 mg L -1 and, in general, the highest values were recorded during dry season. For both seasons (dry and rainy), DOC presented an inverse linear relationship with salinity, which indicates a conservative dilution of organic matter coming into the estuary. During rainy season, anthropogenic organic constituents and humic substances from land-based sources predominated in DOM composition, carried by river flow. Whereas during the dry season, it has been observed a significant increase of products generated by microbial degradation of anthropogenic organic matter. The relationships between fluorescence intensity and salinity suggest a conservative behavior during rainy season and a non-conservative behavior during dry season, with addition of fluorescent organic matter into the intermediate zone of the estuary. Photodegradation by action of sunlight caused a decrease in fluorescence intensity of humic and tryptophan-like constituents and the release of photoproducts, resulting in an increase in fluorescence intensity of protein-like constituents.

Peer reviewed: Characterizing aquatic dissolved organic matter

USGS Publications Warehouse

Leenheer, Jerry A.; Croué, Jean-Philippe

2003-01-01

Whether it causes aesthetic concerns such as color, taste, and odor; leads to the binding and transport of organic and inorganic contaminants; produces undesirable disinfection byproducts; provides sources and sinks for carbon; or mediates photochemical processes, the nature and properties of dissolved organic matter (DOM) in water are topics of significant environmental interest. DOM is also a major reactant in and product of biogeochemical processes in which the material serves as a carbon and energy source for biota and controls levels of dissolved oxygen, nitrogen, phosphorus, sulfur, numerous trace metals, and acidity.

Photoproduction of Carbon Monoxide from Natural Organic Matter

EPA Science Inventory

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

Banana leaf and glucose mineralization and soil organic matter in microhabitats of banana plantations under long-term pesticide use.

PubMed

Blume, Elena; Reichert, José Miguel

2015-06-01

Soil organic matter (SOM) and microbial activity are key components of soil quality and sustainability. In the humid tropics of Costa Rica 3 pesticide regimes were studied-fungicide (low input); fungicide and herbicide (medium input); and fungicide, herbicide, and nematicide (high input)-under continuous banana cultivation for 5 yr (young) or 20 yr (old) in 3 microhabitats-nematicide ring around plants, litter pile of harvested banana, and bare area between litter pile and nematicide ring. Soil samples were incubated sequentially in the laboratory: unamended, amended with glucose, and amended with ground banana leaves. Soil organic matter varied with microhabitat, being greatest in the litter pile, where microbes had the greatest basal respiration with ground banana leaf, whereas microbes in the nematicide ring had the greatest respiration with glucose. These results suggest that soil microbes adapt to specific microhabitats. Young banana plantations had similar SOM compared with old plantations, but the former had greater basal microbial respiration in unamended and in glucose-amended soil and greater first-order mineralization rates in glucose-amended soil, thus indicating soil biological quality decline over time. High pesticide input did not decrease microbial activity or mineralization rate in surface soil. In conclusion, microbial activity in tropical volcanic soil is highly adaptable to organic and inorganic inputs. © 2015 SETAC.

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

NASA Astrophysics Data System (ADS)

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

2010-12-01

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

Isotopic analysis of cometary organic matter

NASA Technical Reports Server (NTRS)

Kerridge, John F.

1991-01-01

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

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

USGS Publications Warehouse

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

2004-01-01

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

Dissolved Organic Matter Composition and Export from U.S. Rivers

NASA Astrophysics Data System (ADS)

Aiken, G.; Butman, D. E.; Spencer, R. G.; Raymond, P.

2012-12-01

Dissolved organic matter (DOM) chemistry and flux are potentially useful indicators of watershed characteristics, climate influences on watershed hydrology and soils, and changes associated with water and land resource management. Organic source materials, watershed geochemistry, oxidative processes and hydrology strongly influence the nature and reactivity of DOM in aquatic systems. The molecules that comprise DOM, in turn, control a number of environmental processes important for ecosystem function including light penetration and photochemistry, microbial activity, mineral dissolution/precipitation, and the transport and reactivity of hydrophobic compounds and metals. In particular, aromatic molecules derived from higher plants exert strong controls on aquatic photochemistry, and on the transport and biogeochemistry of metals. Assessment of DOM composition and transport, therefore, can provide a basis for understanding watershed processes and biogeochemistry of rivers and streams. Here we present results of a multi-year study designed to assess the seasonal and spatial variability of DOM quantity and quality for 15 large North American river basins. Samples were collected from the mouths of the rivers using a sampling program designed to capture hydrologic and seasonal variability of DOM export. DOM concentrations and composition, based on DOM fractionation on XAD resins, chromophoric dissolved organic matter (CDOM) parameters (ultraviolet /visible absorption and fluorescence spectroscopy), specific compound analyses, and DO14C content varied greatly both between sites and seasonally within a given site. DOM in these rivers exhibited a wide range of concentration and carbon specific ultra-violet absorbance at 254 nm (SUVA254), an optical measurement that is an indicator of DOM aromatic carbon content. In almost all systems, CDOM optical parameters correlated strongly with DOC concentration and hydrophobic organic acid (HPOA) content (aquatic humic substances). In

Massive Organic Matter Fall Processing and Organic Enrichment in Deep Sea Sediments: the Role of Fall Type

NASA Astrophysics Data System (ADS)

Hannides, A. K.; Smith, C. R.; Baco-Taylor, A. R.

2005-12-01

startling levels of 80-100. Comparison of falls of different ages but similar masses reveals that kelp falls result in rapid (<3 months) enrichment peaks, while wood falls only generate significant signals on the order of years. Comparison of organic enrichment patterns with pore water sulfide distributions suggests a role of MOM type or quality in stimulating increases in sedimentary organic matter decomposition rates.

Particulate Organic Matter Affects Soil Nitrogen Mineralization under Two Crop Rotation Systems

PubMed Central

Bu, Rongyan; Lu, Jianwei; Ren, Tao; Liu, Bo; Li, Xiaokun; Cong, Rihuan

2015-01-01

Changes in the quantity and/or quality of soil labile organic matter between and after different types of cultivation system could play a dominant role in soil nitrogen (N) mineralization. The quantity and quality of particulate organic matter (POM) and potentially mineralizable-N (PMN) contents were measured in soils from 16 paired rice-rapeseed (RR)/cotton-rapeseed (CR) rotations sites in Hubei province, central China. Then four paired soils encompassing low (10th percentile), intermediate (25th and 75th percentiles), and high (90th percentile) levels of soil PMN were selected to further study the effects of POM on soil N mineralization by quantifying the net N mineralization in original soils and soils from which POM was removed. Both soil POM carbon (POM-C) and N (POM-N) contents were 45.8% and 55.8% higher under the RR rotation compared to the CR rotation, respectively. The PMN contents were highly correlated with the POM contents. The PMN and microbial biomass N (MBN) contents concurrently and significantly decreased when POM was removed. The reduction rate of PMN was positively correlated with changes in MBN after the removal of POM. The reduction rates of PMN and MBN after POM removal are lower under RR rotations (38.0% and 16.3%, respectively) than CR rotations (45.6% and 19.5%, respectively). Furthermore, infrared spectroscopy indicated that compounds with low-bioavailability accumulated (e.g., aromatic recalcitrant materials) in the soil POM fraction under the RR rotation but not under the CR rotation. The results of the present study demonstrated that POM plays a vital role in soil N mineralization under different rotation systems. The discrepancy between POM content and composition resulting from different crop rotation systems caused differences in N mineralization in soils. PMID:26647157

Particulate Organic Matter Affects Soil Nitrogen Mineralization under Two Crop Rotation Systems.

PubMed

Bu, Rongyan; Lu, Jianwei; Ren, Tao; Liu, Bo; Li, Xiaokun; Cong, Rihuan

2015-01-01

Changes in the quantity and/or quality of soil labile organic matter between and after different types of cultivation system could play a dominant role in soil nitrogen (N) mineralization. The quantity and quality of particulate organic matter (POM) and potentially mineralizable-N (PMN) contents were measured in soils from 16 paired rice-rapeseed (RR)/cotton-rapeseed (CR) rotations sites in Hubei province, central China. Then four paired soils encompassing low (10th percentile), intermediate (25th and 75th percentiles), and high (90th percentile) levels of soil PMN were selected to further study the effects of POM on soil N mineralization by quantifying the net N mineralization in original soils and soils from which POM was removed. Both soil POM carbon (POM-C) and N (POM-N) contents were 45.8% and 55.8% higher under the RR rotation compared to the CR rotation, respectively. The PMN contents were highly correlated with the POM contents. The PMN and microbial biomass N (MBN) contents concurrently and significantly decreased when POM was removed. The reduction rate of PMN was positively correlated with changes in MBN after the removal of POM. The reduction rates of PMN and MBN after POM removal are lower under RR rotations (38.0% and 16.3%, respectively) than CR rotations (45.6% and 19.5%, respectively). Furthermore, infrared spectroscopy indicated that compounds with low-bioavailability accumulated (e.g., aromatic recalcitrant materials) in the soil POM fraction under the RR rotation but not under the CR rotation. The results of the present study demonstrated that POM plays a vital role in soil N mineralization under different rotation systems. The discrepancy between POM content and composition resulting from different crop rotation systems caused differences in N mineralization in soils.

Photodissolution of soil organic matter

USGS Publications Warehouse

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

2012-01-01

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

Mobilization of dissolved organic matter from soils and sediments impacted by thermal processes

NASA Astrophysics Data System (ADS)

Rosario-Ortiz, F.; Webster, J.; Retuta, A.; Borch, T.; Young, R. B.

2016-12-01

The frequency and intensity of wildfires has increased in recent decades and this trend is expected to continue for the foreseeable future. Global climate change is predicted to result in the persistence of warmer and drier conditions, leading to an increase in fire frequency, fire season duration, and fire-impacted area. This trend has specifically been observable in the Western United States. The impacts on forested watersheds and the high quality drinking water these forests provide are still relatively uncharacterized and elucidation is needed to adapt treatment strategies as wildfire frequency increases. One main concern is an increase in the mobilization of dissolved organic matter (DOM). Furthermore, there is paucity of information regarding how an altered landscape from wildland fires affects the physical and chemical properties of the DOM, which may adjust the mechanisms that control DOM release and ultimately lead to changes in treatment efficacy. Investigating these parameters may help to explain why this concentration has been observed to increase. Because DOM supplies the precursors for disinfection byproduct formation during drinking water treatment, such differences could affect drinking water quality and public health. In this work, we studied the effect of heating soils and litter on the mobilization of DOM. To do this, soils and litter from two geographical areas, a conifer forest the western U.S. and a deciduous forest collected from the eastern U.S., were collected and heated to 225 and 350 °C for 2 hours. The material was then suspended in water for 24 hours prior to filtration. Leachate water quality was assessed by testing for two parameters including dissolved organic carbon (DOC) concentration and optical properties (absorbance and fluorescence). The water samples were also extracted with C18 solid-phase extraction cartridges, eluted, and analyzed using Fourier transform ion cyclotron resonance mass spectrometry, a high resolution mass

PHOTOCHEMICAL TRANSFORMATIONS OF DISSOLVED ORGANIC MATTER IN A BLACKWATER RIVER

EPA Science Inventory

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

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...

Effect of organic matters on CO2 hydrate phase equilibrium conditions in Na-montmorillonite clay

NASA Astrophysics Data System (ADS)

Park, T.; Kyung, D.; Lee, W.

2013-12-01

Formation of gas hydrates provides an attractive idea for storing greenhouse gases in a long-term stable geological formation. Since the phase equilibrium conditions of gas hydrates indicate the stability of hydrates, estimation of the phase equilibrium conditions of gas hydrates in marine geological conditions is necessary. In this study, we have identified the effects of organic matters (glycine, glucose, and urea) and solid surface (montmorillonite (MMT)) on the three-phase (liquid-hydrate-vapor) equilibrium conditions of CO2 hydrate. CO2 phase equilibrium experiments were conducted using 0.5mol% organic matter solutions with and without 10g soil mineral were experimentally conducted. Addition of organic matters shifted the phase equilibrium conditions of CO2 hydrate to the higher pressure or lower pressure region because of higher competition of water molecules due to the dissolved organic matters. Presence of MMT also leaded to the higher equilibrium pressure due to the interaction of cations with water molecules. By addition of organic matters to the clay suspension, the hydrate phase equilibrium conditions were less inhibited compared to those of MMT and organic matters independently. The diminished magnitudes by addition of organic matters to the clay suspension (MMT > MMT+urea > MMT+glycine > MMT+glucose > DIW) were different to the order of inhibition degree without MMT (Glucose > glycine > urea > DIW). X-ray diffraction (XRD), scanning electron microscope (SEM), and ion chromatography (IC) analysis were conducted to support the hypothesis that the organic matters interact with cations in MMT interlayer space, and leads to the less inhibition of phase equilibrium conditions. The present study provides basic information for the formation and dissociation of CO2 hydrates in the geological formation when sequestering CO2 as a form of CO2 hydrate.

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

NASA Astrophysics Data System (ADS)

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

2012-04-01

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

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

USGS Publications Warehouse

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

1991-01-01

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

Nanoscale Structure Of Organic Matter Explain Its Recalcitrance To Degradation

NASA Astrophysics Data System (ADS)

Spagnol, M.; Salati, S.; Papa, G.; Tambone, F.; Adani, F.

2009-04-01

-Joyner-Halenda) equation were applied respectively to measure specific surface area and mesoporosity. Macromolecular composition of OM was investigated by using CP MAS 13NMR and wet chemical analyses. Results obtained showed how OM evolved increasing microporosity and decreasing meso porosity. This was the result of the preservation of recalcitrant OM versus degradation of the more labile fraction, suggesting that the more recalcitrant fraction was characterized by high microporosity. Another confirmation of these results comes from the analysis of the same OM after the removing of the labile fraction by acid hydrolysis to discover the core-OM, which was characterized by a higher microposrosity with respect the bulk OM. In conclusion it can be showed that not only the chemical composition but, also, the physical structure of organic matter defined its recalcitrance. References Adani, F.; Spagnol, M.; Genevini, P. Biogeochemistry 2006, 78, 85-96. Himmel, M.E.; Ding S.Y.; Johnson, D.K.; Adney, W.S.; Nimlos, M.R.; Brady, J.W.; Foust, T.D. Sci. 2007, 315, 804-807. Chesson, A. In Driven by nature Plant Litter Quality and Decomposition. Cadisch, G.; Giller, K.E. Eds.; CAB International: Wallinford, UK 1997, pp 47-66. Zimmerman, A.R.; Goyne, K.W.; Chorover, J, Komarneni, S.; Brantley, S.L. Org Geochem. 2004, 35, 355-375.

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

USGS Publications Warehouse

Leenheer, Jerry A.; Rostad, Colleen E.

2004-01-01

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

Quality of dissolved organic matter affects planktonic but not biofilm bacterial production in streams.

PubMed

Kamjunke, Norbert; Herzsprung, Peter; Neu, Thomas R

2015-02-15

Streams and rivers are important sites of organic carbon mineralization which is dependent on the land use within river catchments. Here we tested whether planktonic and epilithic biofilm bacteria differ in their response to the quality of dissolved organic carbon (DOC). Thus, planktonic and biofilm bacterial production was compared with patterns of DOC along a land-use gradient in the Bode catchment area (Germany). The freshness index of DOC was positively related to the proportion of agricultural area in the catchment. The humification index correlated with the proportion of forest area. Abundance and production of planktonic bacteria were lower in headwaters than at downstream sites. Planktonic production was weakly correlated to the total concentration of DOC but more strongly to quality-measures as revealed by spectra indexes, i.e. positively to the freshness index and negatively to the humification index. In contrast to planktonic bacteria, abundance and production of biofilm bacteria were independent of DOC quality. This finding may be explained by the association of biofilm bacteria with benthic algae and an extracellular matrix which represent additional substrate sources. The data show that planktonic bacteria seem to be regulated at a landscape scale controlled by land use, whereas biofilm bacteria are regulated at a biofilm matrix scale controlled by autochthonous production. Thus, the effects of catchment-scale land use changes on ecosystem processes are likely lower in small streams dominated by biofilm bacteria than in larger streams dominated by planktonic bacteria. Copyright © 2014 Elsevier B.V. All rights reserved.

Experimental Study of Soil Organic Matter Loss From Cultivated Field Plots In The Venezuelan Andes.

NASA Astrophysics Data System (ADS)

Bellanger, B.; Huon, S.; Velasquez, F.; Vallès, V.; Girardin A, C.; Mariotti, A. B.

The question of discriminating sources of organic matter in suspended particles of stream flows can be addressed by using total organic carbon (TOC) concentration and stable isotope (13C, 15N) measurements when constant fluxes of organic matter supply can be assumed. However, little is known on the dynamics of organic matter release during soil erosion and on the temporal stability of its isotopic signature. In this study, we have monitored soil organic carbon loss and water runoff using natural rainfall events on three experimental field plots with different vegetation cover (bare soil, maize and coffee fields), set up on natural slopes of a tropical mountainous watershed in NW Venezuela (09°13'32'' ­ 09°10'00''N, 70°13'49'' ­ 70°18'34''W). Runoff and soil loss are markedly superior for the bare field plot than for the coffee field plot: by a factor 15 ­ 36, respectively, for the five-month experiment, and by a factor 30 ­ 120, respectively, during a single rainfall event experiment. Since runoff and soil organic matter loss are closely linked during most of the flow (at the time scales of this study), TOC concentration in suspended matter is constant. Furthermore, stable isotope compositions reflect those of top-soil organic matter from which they originate.

Overestimation of Crop Root Biomass in Field Experiments Due to Extraneous Organic Matter

PubMed Central

Hirte, Juliane; Leifeld, Jens; Abiven, Samuel; Oberholzer, Hans-Rudolf; Hammelehle, Andreas; Mayer, Jochen

2017-01-01

Root biomass is one of the most relevant root parameters for studies of plant response to environmental change, soil carbon modeling or estimations of soil carbon sequestration. A major source of error in root biomass quantification of agricultural crops in the field is the presence of extraneous organic matter in soil: dead roots from previous crops, weed roots, incorporated above ground plant residues and organic soil amendments, or remnants of soil fauna. Using the isotopic difference between recent maize root biomass and predominantly C3-derived extraneous organic matter, we determined the proportions of maize root biomass carbon of total carbon in root samples from the Swiss long-term field trial “DOK.” We additionally evaluated the effects of agricultural management (bio-organic and conventional), sampling depth (0–0.25, 0.25–0.5, 0.5–0.75 m) and position (within and between maize rows), and root size class (coarse and fine roots) as defined by sieve mesh size (2 and 0.5 mm) on those proportions, and quantified the success rate of manual exclusion of extraneous organic matter from root samples. Only 60% of the root mass that we retrieved from field soil cores was actual maize root biomass from the current season. While the proportions of maize root biomass carbon were not affected by agricultural management, they increased consistently with soil depth, were higher within than between maize rows, and were higher in coarse (>2 mm) than in fine (≤2 and >0.5) root samples. The success rate of manual exclusion of extraneous organic matter from root samples was related to agricultural management and, at best, about 60%. We assume that the composition of extraneous organic matter is strongly influenced by agricultural management and soil depth and governs the effect size of the investigated factors. Extraneous organic matter may result in severe overestimation of recovered root biomass and has, therefore, large implications for soil carbon modeling and

Overestimation of Crop Root Biomass in Field Experiments Due to Extraneous Organic Matter.

PubMed

Hirte, Juliane; Leifeld, Jens; Abiven, Samuel; Oberholzer, Hans-Rudolf; Hammelehle, Andreas; Mayer, Jochen

2017-01-01

Root biomass is one of the most relevant root parameters for studies of plant response to environmental change, soil carbon modeling or estimations of soil carbon sequestration. A major source of error in root biomass quantification of agricultural crops in the field is the presence of extraneous organic matter in soil: dead roots from previous crops, weed roots, incorporated above ground plant residues and organic soil amendments, or remnants of soil fauna. Using the isotopic difference between recent maize root biomass and predominantly C3-derived extraneous organic matter, we determined the proportions of maize root biomass carbon of total carbon in root samples from the Swiss long-term field trial "DOK." We additionally evaluated the effects of agricultural management (bio-organic and conventional), sampling depth (0-0.25, 0.25-0.5, 0.5-0.75 m) and position (within and between maize rows), and root size class (coarse and fine roots) as defined by sieve mesh size (2 and 0.5 mm) on those proportions, and quantified the success rate of manual exclusion of extraneous organic matter from root samples. Only 60% of the root mass that we retrieved from field soil cores was actual maize root biomass from the current season. While the proportions of maize root biomass carbon were not affected by agricultural management, they increased consistently with soil depth, were higher within than between maize rows, and were higher in coarse (>2 mm) than in fine (≤2 and >0.5) root samples. The success rate of manual exclusion of extraneous organic matter from root samples was related to agricultural management and, at best, about 60%. We assume that the composition of extraneous organic matter is strongly influenced by agricultural management and soil depth and governs the effect size of the investigated factors. Extraneous organic matter may result in severe overestimation of recovered root biomass and has, therefore, large implications for soil carbon modeling and estimations

Nitrogen Isotopic Composition of Organic Matter in a Pristine Collection IDP

NASA Technical Reports Server (NTRS)

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

2012-01-01

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

The role of aquatic fungi in transformations of organic matter mediated by nutrients

Treesearch

Cynthia J. Tant; Amy D. Rosemond; Andrew S. Mehring; Kevin A. Kuehn; John M. Davis

2015-01-01

1. We assessed the key role of aquatic fungi in modifying coarse particulate organic matter (CPOM) by affecting its breakdown rate, nutrient concentration and conversion to fine particulate organic matter (FPOM). Overall, we hypothesised that fungal-mediated conditioning and breakdown of CPOM would be accelerated when nutrient concentrations are increased and tested...

Xiphinema americanum as Affected by Soil Organic Matter and Porosity.

PubMed

Ponchillia, P E

1972-07-01

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

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

EPA Science Inventory

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

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

Black Carbon in Estuarine and Coastal Ocean Dissolved Organic Matter

NASA Technical Reports Server (NTRS)

Mannino, Antonio; Harvey, H. Rodger

2003-01-01

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

Isotopic composition of hydrogen in insoluble organic matter from cherts

NASA Technical Reports Server (NTRS)

Krishnamurthy, R. V.; Epstein, S.

1991-01-01

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

The roles of organic matter in the formation of uranium deposits in sedimentary rocks

USGS Publications Warehouse

Spirakis, C.S.

1996-01-01

Because reduced uranium species have a much smaller solubility than oxidized uranium species and because of the strong association of organic matter (a powerful reductant) with many uranium ores, reduction has long been considered to be the precipitation mechanism for many types of uranium deposits. Organic matter may also be involved in the alterations in and around tabular uranium deposits, including dolomite precipitation, formation of silicified layers, iron-titanium oxide destruction, dissolution of quartz grains, and precipitation of clay minerals. The diagenetic processes that produced these alterations also consumed organic matter. Consequently, those tabular deposits that underwent the more advanced stages of diagenesis, including methanogenesis and organic acid generation, display the greatest range of alterations and contain the smallest amount of organic matter. Because of certain similarities between tabular uranium deposits and Precambrian unconformity-related deposits, some of the same processes might have been involved in the genesis of Precambrian unconformity-related deposits. Hydrologic studies place important constraints on genetic models of various types of uranium deposits. In roll-front deposits, oxidized waters carried uranium to reductants (organic matter and pyrite derived from sulfate reduction by organic matter). After these reductants were oxidized at any point in the host sandstone, uranium minerals were reoxidized and transported further down the flow path to react with additional reductants. In this manner, the uranium ore migrated through the sandstone at a rate slower than the mineralizing ground water. In the case of tabular uranium deposits, the recharge of surface water into the ground water during flooding of lakes carried soluble humic material to the water table or to an interface where humate precipitated in tabular layers. These humate layers then established the chemical conditions for mineralization and related

A mixing-model approach to quantifying sources of organic matter to salt marsh sediments

NASA Astrophysics Data System (ADS)

Bowles, K. M.; Meile, C. D.

2010-12-01

Salt marshes are highly productive ecosystems, where autochthonous production controls an intricate exchange of carbon and energy among organisms. The major sources of organic carbon to these systems include 1) autochthonous production by vascular plant matter, 2) import of allochthonous plant material, and 3) phytoplankton biomass. Quantifying the relative contribution of organic matter sources to a salt marsh is important for understanding the fate and transformation of organic carbon in these systems, which also impacts the timing and magnitude of carbon export to the coastal ocean. A common approach to quantify organic matter source contributions to mixtures is the use of linear mixing models. To estimate the relative contributions of endmember materials to total organic matter in the sediment, the problem is formulated as a constrained linear least-square problem. However, the type of data that is utilized in such mixing models, the uncertainties in endmember compositions and the temporal dynamics of non-conservative entitites can have varying affects on the results. Making use of a comprehensive data set that encompasses several endmember characteristics - including a yearlong degradation experiment - we study the impact of these factors on estimates of the origin of sedimentary organic carbon in a saltmarsh located in the SE United States. We first evaluate the sensitivity of linear mixing models to the type of data employed by analyzing a series of mixing models that utilize various combinations of parameters (i.e. endmember characteristics such as δ13COC, C/N ratios or lignin content). Next, we assess the importance of using more than the minimum number of parameters required to estimate endmember contributions to the total organic matter pool. Then, we quantify the impact of data uncertainty on the outcome of the analysis using Monte Carlo simulations and accounting for the uncertainty in endmember characteristics. Finally, as biogeochemical processes

Progress of organic matter degradation and maturity of compost produced in a large-scale composting facility.

PubMed

Nakasaki, Kiyohiko; Marui, Taketoshi

2011-06-01

To monitor the progress of organic matter degradation in a large-scale composting facility, the percentage of organic matter degradation was determined by measuring CO(2) evolution during recomposting of compost samples withdrawn from the facility. The percentage of organic matter degradation was calculated as the ratio of the amount of CO(2) evolved from compost raw material to that evolved from each sample during recomposting in the laboratory composting apparatus. It was assumed that the difference in the cumulative emission of CO(2) between the compost raw material and a sample corresponds to the amount of CO( 2) evolved from the sample in the composting facility. Using this method, the changes in organic matter degradation during composting in practical large-scale composting facilities were estimated and it was found that the percentage of organic matter degradation increased more vigorously in the earlier stages than in the later stages of composting. The percentage of organic matter degradation finally reached 78 and 55% for the compost produced from garbage-animal manure mixture and distillery waste (shochu residue), respectively. It was thus ascertained that organic matter degradation progressed well in both composting facilities. Furthermore, by performing a plant growth assay, it was observed that the compost products of both the facilities did not inhibit seed germination and thus were useful in promoting plant growth.

Biochemical activity and chemical-structural properties of soil organic matter after 17 years of amendments with olive-mill pomace co-compost.

PubMed

Aranda, V; Macci, C; Peruzzi, E; Masciandaro, G

2015-01-01

This study evaluates soil fertility, biochemical activity and the soil's ability to stabilize organic matter after application of composted olive-mill pomace. This organic amendment was applied in two different olive groves in southern Spain having different soil typologies (carbonated and silicic). Olive grove soils after 17 years of organic management with application of olive-mill pomace co-compost were of higher quality than those with conventional management where no co-compost had been applied. The main chemical parameters studied (total organic carbon, total nitrogen, available phosphorus, exchangeable bases, cation exchange capacity, total extractable carbon (TEC), and humic-to-fulvic acids ratio), significantly increased in soils treated with the organic amendment. In particular, the more resistant pool of organic matter (TEC) enhanced by about six and eight fold in carbonated and silicic soils, respectively. Moreover, the amended silicic soils showed the most significant increases in enzyme activities linked to C and P cycles (β-glucosidase twenty-five fold higher and phosphatase seven fold higher). Organic management in both soils induced higher organic matter mineralization, as shown by the higher pyrrole/phenol index (increasing 40% and 150% in carbonated and silicic soils, respectively), and lower furfural/pyrrole index (decreasing 27% and 71% in carbonated and silicic soils, respectively). As a result of mineralization, organic matter incorporated was also more stable as suggested by the trend of the aliphatic/aromatic index (decreasing 36% and 30% in carbonated and silicic soils, respectively). Therefore, management system and soil type are key factors in increasing long-term C stability or sequestration in soils. Thus application of olive-oil extraction by-products to soils could lead to important mid-to -long-term agro-environmental benefits, and be a valuable alternative use for one of the most widespread polluting wastes in the Mediterranean