Changes In Composition Of Organic Matter Research Articles

Diagenetic changes in Lake Superior sediments as seen from FTIR and 2D correlation spectroscopy

Isotopic and elemental analysis, Fourier transform infrared spectroscopy (FTIR), principal components analysis (PCA) and two dimensional (2D) correlation analysis, where core depth was used as perturbation, were used to study the diagenesis of organic matter (OM) in Lake Superior sediments. Changes in OM composition were examined at five lake stations over a depth range of 0–10cm. PCA results show that depth-related changes among sites are similar, leading to an increased contribution from inorganic (and possibly refractory aromatic organic) components at each site, and a loss of contribution from other organic components. Synchronous spectra reveal that aliphatic esters and carbohydrates are degraded significantly with increasing depth, leading to an increased contribution from clay/biogenic silica/inactive carbohydrates. Asynchronous spectra show that, in general, carboxyl groups, including aliphatic ester and amide in protein, are degraded first, followed by a group of carbohydrates and then aromatic compounds and/or the SiO framework in clay and biogenic silica. Site dependent compositional variation occurs and appears to be influenced by topography and geology, e.g. the delivery of a larger load of terrestrial inorganic silicate minerals to certain sites and re-suspension/re-deposition, leading to less intensive down core variation at mid-lake central and eastern basin sites. The study demonstrates the usefulness of FTIR coupled with PCA and 2D correlation approaches for exploring structural changes in sedimentary material during diagenesis.

The Podzol Hydrosequence of Itaguaré (São Paulo, Brazil). 2. Soil Organic Matter Chemistry by Pyrolysis‐Gas Chromatography/Mass Spectrometry

A Late Pleistocene to Holocene hydrosequence of podzols in the coastal plain of São Paulo (Brazil), of which the macromorphology was described previously, was investigated by pyrolysis‐gas chromatography/mass spectrometry (GC/MS). Differences in chemical composition of organic matter (OM) coincided very well with the morphological interpretation of these profiles with respect to drainage conditions, origin of OM, and decomposition. OM in B‐horizons of poorly‐drained profiles has a signature of dissolved organic matter (DOM), while that of well‐drained profiles indicates root‐derived material. Bands that, according to their morphology, were attributed to DOM have different signature within the profiles, reflecting DOM origin. The EB horizons of poorly‐drained profiles show a selective decay of B‐horizon material, resulting in a relative accumulation of aliphatics in poorly drained profiles. In the EB horizons of the well‐drained profiles, however, significant amounts of microbial products were accumulated and poly‐aromatic compounds were the most stable. This has not been described for temperate podzols. Factor analysis suggests that local differences in vegetation are responsible for about 50% of the total chemical variation in pyrolysates, whereas source, transport, and decomposition in the profile account for the other half. The results underline that OM composition of podzol horizons is strongly dependent on hydrological conditions, resulting in divergent soil organic matter (SOM) properties between soils from different landscape contexts. Nonetheless, there is a comprehensible relation between SOM fingerprints of horizons within one profile. Finally, changes in OM composition at horizon transitions provide insight into the podzolization process.

Spectrofluorimetric study of dissolved organic matter in River Salaca (Latvia) basin waters

Dissolved organic matter (DOM) in surface waters influences mineral weathering, nutrient cycling, aggregation of particulate matter and photochemical reactions in waters and aquatic communities. In this study, the effectiveness of UV and fluorescence measurements in distinguishing the origin of DOM and processes within the river basin were analyzed using the River Salaca basin as an example. The basin of River Salaca is characterized by low anthropogenic pressure, however, the water color during the last few decades has increased (an effect known as brownification). As tools to study the composition of dissolved organic substances in waters of the River Salaca and its tributaries the use of UV and fluorescence spectroscopy was evaluated. The use of the fluorescence index (a ratio of the emission intensity at a wavelength of 450 nm to that at 500 nm) allowed us to distinguish sources of aquatic DOM, characterize processes in the water body basin and to follow the changes in organic matter composition. Synchronous scan fluorescence spectrometry was more informative than excitation emission spectra and, provided information on the basic structural features of DOM.

Ozonation of Municipal Secondary Effluent; Removal of Hazardous Micropollutants and Related Changes of Organic Matter Composition

AbstractThe major part of the regulated priority substances and family of compounds defined in the European Water Framework Directive and some other organic micropollutants were tracked in a municipal biotreated secondary effluent. Micropollutants detected in the effluent were subjected to different ozone doses related to different oxidation extents. Ozone confirmed its efficiency in terms of micropollutant reduction when applied to a municipal biotreated effluent. Accordingly, it achieved reductions exceeding 70% for 91% of the pollutants detected at high ozone dose. Organic matter transformation was also investigated by both controlling evolution of surrogates - including chemical oxygen demand, dissolved organic carbon, UV

Natural and Anthropogenic Mercury Distribution in Marine Sediments from Hudson Bay, Canada

Twelve marine sediment cores from Hudson Bay, Canada, were collected to investigate the response of sub-Arctic marine sediments to atmospherically transported anthropogenic mercury (Hg). Modeling by a two-layer sediment mixing model suggests that the historical Hg deposition to most of the sediment cores reflects the known history of atmospheric Hg deposition in North America, with an onset of increasing anthropogenic Hg emissions in the late 1800s and early 1900s and a reduction of Hg deposition in the mid- to late-1900s. However, although anthropogenic Hg has contributed to a ubiquitous increase in Hg concentrations in sediments over the industrial era, the most elevated industrial-era sedimentary Hg concentrations only marginally exceed the upper preindustrial sedimentary Hg concentrations. Analysis of delta13C and relationship between Hg and organic matter capture suggests that the response of Hudson Bay sediments to changes in atmospheric Hg emissions is largely controlled by the particle flux in the system and that natural changes in organic matter composition and dynamics can cause variation in sedimentary Hg concentrations at least to the same extent as those caused by increasing anthropogenic Hg emissions.

Huangpu River water treatment by microfiltration with ozone pretreatment

With the promulgation of more stringent regulations to guarantee the quality of drinking water, low pressure membrane processes are nowadays considered for surface water treatment. But these membranes are sensitive to fouling. In this study ozone is introduced to pretreatment for membrane filtration to get a high quality permeate and improve membrane performance. The organic matter characteristics, such as AMWD of organic matter, hydrophilic/hydrophobic fractions were studied with ozone oxidation. Results show that for Huangpu River water, ozone oxidation offers high percentage of UV absorbance removal than DOC removal. Highest removal of DOC and UV254 of 10% and 71% respectively were observed. The dominant organic matter oxidized by ozone was 2–7.0kDa in terms of molecule distribution investigation. Ozone oxidizes more hydrophobic fraction to hydrophilic one. Changes of organic matter composition improved membrane flux. There is the optimal dosage with ozone of 1.5mgO3/L made membrane flux maximum during 0.5–3.0mgO3/L ozone dosage. Ozone oxidization provided degradation of macromolecule organic matter, which is responsible to membrane fouling, to small molecule organic substance. Study about the chemical cleaning of the fouled membrane also supports the point that membrane fouling is produced by the organic substance with high molecule weight.

Palynofacies as useful tool to study origins and transfers of particulate organic matter in recent terrestrial environments: Synopsis and prospects

Palynofacies analysis is based on transmitted light microscope study of organic constituents isolated and concentrated by acid and basic digestions. Published results of studies of present-day terrestrial environments show that two complementary approaches successfully characterize particulate organic matter (OM) from palynofacies analyses. The first method is based on the identification and the quantification of some typical particles ( optical markers) according to their origin (i.e. aquatic or terrestrial), their nature (i.e. biogenic, anthropogenic, fossil), and/or their formation (i.e. biodegradation, combustion, oxidation). The second approach is based on the use of binary or ternary diagrams in order to define petrographical signatures from the relative proportions of significant organic constituents. This approach can be used for tracking i) changes in OM composition during humification in soil profiles, ii) transport of reworked terrestrial particles, iii) diagenesis of peaty deposits, or iv) weathering of geological substratum. The more advanced approach is based on the use of some predefined optical markers and their optical signatures to establish the relation between the OM compositions ( palynofacies) and their depositional environments. In addition, this kind of study aims to define a modern frame of reference that can be applied in paleoenvironmental reconstructions. This paper combines a bibliographic review with previously unpublished data from palynofacies analyses. The aim is to present some applied examples illustrating (1) the main approaches developed for characterization of the particulate OM in surficial deposits, and (2) the study of OM transfers in terrestrial geosystems.

Changes in organic matter composition during composting of two digested sewage sludges

Changes in the chemical and chemical–structural composition of the organic matter of two different sewage sludges (aerobic and anaerobic) mixed with sawdust (1:1 and 1:3, v/v) during composting were determined by monitoring chemical and microbiological parameters as well as by pyrolysis-gas chromatography. Composting was carried out in periodically turned outdoor piles, which were sampled for analysis 1, 30, 60 and 90 days after the beginning of the composting process. Both volatile organic matter and the water soluble C fraction decreased during composting, indicating that the more labile C fractions are mineralized during the process. Microbial activity as measured by microbial respiration (CO 2 evolved from compost samples during incubation) also decreased with composting, reflecting the more stable character of the resulting compost. No major differences were observed between the four composts studied as regards their chemical–structural characteristics. The acetonitrile, acetic acid and phenol pyrolytic fragment tended to increase with composting. Although the final composts were more aromatic in nature than the starting materials, a low degree of humification was observed in all four composts studied, as determined by their high proportion of polysaccharides and alkyl compounds. For this reason, the relationship between pyrolytic fragments, such as benzene/toluene or benzene + toluene/pyrrol + phenols, which are used as indices of humification for soil organic matter, are not of use for such poorly evolved sludge composts; instead, ratios that involve carbohydrate derivatives and aromatic compounds, such as furfural + acetic/benzene + toluene or acetic/toluene, are more sensitive indices for reflecting the transformations of these materials during composting. Both the chemical and microbiological parameters and pyrolytic analysis provided valuable information concerning the nature of the compost’s organic matter and its changes during the composting process.

Changes in surface reactivity and organic matter composition of clay subfractions with duration of fertilizer deprivation

SummaryPreservation of organic matter in soils depends on the chemical structure of organic compounds and on the surface properties of the mineral matrix. We tested the effect of mineral surface reactivity on organic matter decomposition by (i) investigating changes of organic matter composition in clay subfractions of an illitic Haplic Chernozem along a time series of fertilizer deprivation and (ii) simultaneously characterizing the reactivity of mineral surfaces. The soil was subjected to fertilizer deprivation for 18, 44 and 98 years, respectively. Mineral surface properties were characterized by selective dissolution of pedogenic oxides. The number of hydroxyls released after exposure to sodium fluoride was taken as an index for mineral surface reactivity. Organic soil constituents were determined by 13C cross‐polarization magic‐angle spinning nuclear magnetic resonance (13C CPMAS NMR).Clay subfractions had different mineral surface properties. The coarse fractions have more reactive surfaces and contain more organic carbon than the fine clay fractions. Mineral surface properties are constant over time and are not affected by fertilizer deprivation. Surface reactivity is a function of iron oxide density and controls carbon concentrations in the clay subfractions. Within the time frame of our investigation, alkyl C and aromatic C responded to the duration of fertilizer deprivation, but were indifferent to mineral surface reactivity. O–alkyl C seems to be protected by interactions with pedogenic oxides.

Chemical composition of organic matter in extremely acid, lignite-containing lake sediments impacted by fly ash contamination.

In the Lusatian lignite mining district of eastern Germany, extremely acid lakes developed during ground water rising after exploitation of lignite in open-cast mines. The reasons of plant colonization (Juncus bulbosus L.) of some lakes exhibiting moderate pH values while others remain extremely acid and unvegetated are unknown. Alkalinity gain may be achieved by addition of alkaline materials and/or decomposition of organic matter. Our objective was to examine fly ash deposition and the resulting changes in organic matter composition in the uppermost 0 to 5 cm of the sediment sampled from vegetated and unvegetated lakes. Bulk soil and particle size fractions were analyzed for elemental composition, magnetic susceptibility, and chemical structure of the organic matter by 13C solid-state nuclear magnetic resonance (NMR) spectroscopy. The lignite content of the samples was estimated by 14C activity measurements. The pH values decreased with increasing depth and the changes in pH were found to be correlated with changes in magnetic susceptibility. Carbon and nitrogen contents were found to decrease with increasing depth. The C to N ratios are consistent with the (i) the presence of decomposing plant residues and/or microbial material such as algae in the upper 0 to 5 cm of the sediment and (ii) the dominance of lignite in the layers below this depth as confirmed by 14C activity measurements. The structural analyses of the particle size separates from the 0- to 5-cm depth were consistent with the presence of organic matter derived from plant material. This study confirms that fly ash is an important source of alkalinity in the upper 0 to 5 cm of the sediment that enhanced plant growth and led to enrichment of the sediment with organic matter derived from plant material.

Chemical Composition of Organic Matter in Extremely Acid, Lignite-Containing Lake Sediments Impacted by Fly Ash Contamination

In the Lusatian lignite mining district of eastern Germany, extremely acid lakes developed during ground water rising after exploitation of lignite in open-cast mines. The reasons of plant colonization (Juncus bulbosus L.) of some lakes exhibiting moderate pH values while others remain extremely acid and unvegetated are unknown. Alkalinity gain may be achieved by addition of alkaline materials and/or decomposition of organic matter. Our objective was to examine fly ash deposition and the resulting changes in organic matter composition in the uppermost 0 to 5 cm of the sediment sampled from vegetated and unvegetated lakes. Bulk soil and particle size fractions were analyzed for elemental composition, magnetic susceptibility, and chemical structure of the organic matter by 13C solid-state nuclear magnetic resonance (NMR) spectroscopy. The lignite content of the samples was estimated by 14C activity measurements. The pH values decreased with increasing depth and the changes in pH were found to be correlated with changes in magnetic susceptibility. Carbon and nitrogen contents were found to decrease with increasing depth. The C to N ratios are consistent with the (i) the presence of decomposing plant residues and/or microbial material such as algae in the upper 0 to 5 cm of the sediment and (ii) the dominance of lignite in the layers below this depth as confirmed by 14C activity measurements. The structural analyses of the particle size separates from the 0- to 5-cm depth were consistent with the presence of organic matter derived from plant material. This study confirms that fly ash is an important source of alkalinity in the upper 0 to 5 cm of the sediment that enhanced plant growth and led to enrichment of the sediment with organic matter derived from plant material.

Improvement of 13C and 15N CPMAS NMR spectra of bulk soils, particle size fractions and organic material by treatment with 10% hydrofluoric acid

SummaryThe small organic matter content of mineral soils makes it difficult to obtain 13C and 15N nuclear magnetic resonance (NMR) spectra with acceptable signal‐to‐noise ratios. Subjecting such samples to hydrofluoric acid removes mineral matter and leads to a relative increase in organic material. The effect of treatment with 10% hydrofluoric acid on bulk chemical composition and resolution of solid‐state 13C NMR spectra was investigated with six soils, some associated particle size fractions, plant litter and compost. The treatment enhanced the signal‐to‐noise ratio of the solid‐state 13C NMR spectra. The improvement in spectrum quality was greatest in the clay fraction of soil contaminated with coal ash. The removal of paramagnetic compounds associated with the ash may be the main reason for the improvement. Based on total C, total N, C/N ratio and intensity distribution of the solid‐state 13C NMR spectra, no changes in organic matter composition could be detected, except for a possible loss of carbohydrates. After treatment with HF, solid‐state 15N NMR spectra of particle size fractions were obtained and indicated that the observable nitrogen is present mostly as peptides and free amino groups. Extraction with hydrofluoric acid is recommended as a routine treatment prior to solid‐state 13C and 15N NMR on soil containing little C or N and soil samples containing paramagnetic compounds from natural or anthropogenic sources.

Organic matter changes immediately after a wildfire in an atlantic forest soil and comparison with laboratory soil heating

The quantity, chemical composition and mineralization kinetics of the organic matter of an acid Humic Cambisol, developed over granite, under Pinus sylvestris L. were determined in 0–5 and 5–10 cm samples collected immediately after a high-intensity wildfire, and compared with those of an unaffected site nearby. Organic matter was characterized by different chemical fractionation methods, and the C mineralization was determined by aerobic incubation. A similar unburnt soil located in the same area was heated at the laboratory at 150, 220, 350 and 490°C to measure the losses of C content; the samples heated at 220 and 350°C were selected to determine chemical changes in organic matter composition. Surface and subsurface soil layers lost about 50% of their C content during wildfire. The C mineralized decreased in the surface layer; however, the percentage of total C mineralized increased in both layers. The cumulative CO 2C mineralized fitted a double exponential first-order kinetic model, but the fire affected the kinetic parameters, increasing both the labile pool of the potentially mineralizable C and the mineralization rate constants of the recalcitrant and labile pools. Cellulose + hemicelluloses declined significantly after the burning, whereas lipids did not vary. The fire decreased the amount of unhumified organic matter and the alkali-soluble compounds, particularly humic acids, but there was a net increase of humin. The organic matter bound to Fe and especially to A1 was much higher after the burning. In the soil heated under laboratory conditions the changes observed at 150°C were very low, whereas at 490°C almost all the organic matter disappeared. The changes exhibited by the samples heated at 220°C were the most similar to those observed in the samples from the wildfire. At 220 and 350°C the humification and metal complexation percentages of the organic matter increased, similar to the trend observed in the samples from the wildfire.

Changes in organic matter composition of forest soil treated with a large amount of urea to promote ammonia fungi and the abilities of these fungi to decompose organic matter

Organic matter composition (lignin, holocellulose, 50% (v/v) methanol extract, water-soluble carbohydrate (WSC) and phenolics (WSP), petroleum ether extract, and ash) of A0 layer soil treated with 700 g/m2 of urea to promote ammonia fungi was investigated in a Japanese red pine (Pinus densiflora) forest. Nine species of fungi were found during the study period of 18 months after the treatment. Of these, seven species belong to the ammonia fungi. WSC content of the treated soil was lower than that of the control. Methanol extract content increased initially after the treatment, then decreased to below the control level. There were no consistent differences in other components between the treated plot and the control. The abilities to decompose cellulose, lignin, chitin, protein and lipid in 18 strains in 10 species of the ammonia fungi were also screened. Cellulose was not lysed byPseudombrophila deerata, Hebeloma spp. andLaccaria bicolor. Strong lignolytic activity was shown byLyophyllum tylicolor, Coprinus echinosporus andP. deerata. Chitin was decomposed byAmblyosporium botrytis, L. tylicolor, C. echinosporus andHebeloma vinosophyllum. All strains possessed proteolytic and lipolytic activities. Supply of glucose to the culture media resulted in weaker enzyme activities except for lignolytic ability.

Decomposition of faecal matter and somatic tissue of Mytilus galloprovincialis: changes in organic matter composition and microbial succession

Variations in the biochemical composition of pseudo-faeces and faeces egested by Mytilus galloprovincialis (Lamarck) and in detritus derived from the somatic tissue of mussels during the decomposition process were investigated by means of two intensive experiments. During the degradation process, the biochemical composition of pseudo-faeces and faeces showed a clear increase in protein content related to the microbial colonization. Changes also occurred in the biochemical composition of particulate organic matter (POM) in the surrounding water due to faecal matter decomposition, heterotrophic utilization and conversion of particulate carbohydrates and proteins to the dissolved pool. The study of production and heterotrophic utilization of the POM derived from the somatic tissue of M. galloprovincialis collected in the Gulf of Tigullio, Italy in 1990 indicates that this kind of material is rapidly decomposable and largely available for benthic consumers. Bacteria utilized selectively the different compounds, and proteins proved to be the most suitable substrate for bacterial growth. The input of organic detritus into the experimental system resulted in an enhancement of bacterial activity and consequently of the RNA/DNA ratio. Bacterial DNA accounted on average for 17% of particulate DNA. During decomposition processes, nutrient release was about ten times higher than the value calculated from individual excretion rates, indicating that mussel beds may be important sites for nutrient regeneration. Carbon conversion efficiency for bacteria growing on faecal matter was, on average, 17.2%. The potential importance of faecal output and bacterial production as a carbon resource for benthic communities near mussel culture areas is discussed.

A 13C‐NMR study on the formation of soil organic matter from grass residues

AbstractThe development of C‐distribution on functional groups in soil organic matter (SOM) was investigated in whole soil samples and organomineral particle‐size fractions from the 34‐year‐old pot experiment Hu3‐Loamy marl at Rostock. CPMAS‐13C‐NMR spectra of grass roots and whole soil samples indicated the enrichment of carboxyl‐C, aliphatic C and aromatic C in SOM, Only minor changes were observed in the SOM‐C distribution on functional groups between 13th and 34th experimental year. The investigation of organomineral clay and silt‐size fractions showed a specific retention of aliphatics in clay. The most obvious changes in organic matter composition in size‐fractions were the increase of carbohydrate‐C and decrease of aromatic C.

The effects of the season and of water chemistry on the decomposition of Nymphaea alba L.; Weight loss and pyrolysis mass spectrometry of the particulate matter

Dynamics in loss of mass and changes in organic matter composition of decomposing leaves of Nymphaea alba L. were studied in the ambient water of an alkaline eutrophic oxbow lake and an acid moorland pool. These aspects were also studied in the laboratory, in open flow-through aquaria fed with media differing in pH, alkalinity and nitrogen and/or phosphorus concentrations. The loss in weight of the decomposing leaves was studied using litter bags. The organic matter composition of the particulate residues was characterized by Curie-point pyrolysis mass spectrometry. Higher weight-loss rates and faster changes in organic matter composition were observed in the warmer period of the year and under more eutrophic and/or alkaline conditions. In acid environments, the loss of structural carbohydrates from the decomposing plant material was small. In eutrophic and/or alkaline environments, lignin accumulated in the particulate residues, while cellulose and hemicellulose were apparently mineralized.