Important Source Of Organic Matter Research Articles

Source of arsenic pollution in southern Indus alluvial plain aquifers, Pakistan

Aquifers in Indus alluvial plain are naturally polluted by arsenic (As). Millions of population in Pakistan use groundwater for drinking is exposed to As ingested diseases. Present investigations were focused on the mobilization mechanism of As in the alluvial aquifers, in Matiari district of Pakistan, which is mainly covered by alluvial sediments of Holocene and Pleistocene age. These sediments are weathered from Himalayas and its neighboring regions and are primarily deposited by Indus River. About 94 samples of groundwater were collected from various localities of Matiari district. Physico-chemical data revealed that 60% of wells exceed 10 μg/L, WHO permissible standard for drinking water. Low nitrate and neutral to near neutral pH and negative Eh in most of the wells are indicative of reducing conditions in the aquifers. Ancient courses of Indus river and domestic and agricultural wastes could be an important source of organic matter. Microbiodegradation of organic matter has created reducing conditions in the aquifer, which trigger the reduction of sedimentary iron oxyhydroxides and the mobilize As in shallow aquifers of Matiari. A borehole was also drilled to decipher the lithological and geochemical characteristics of aquifer material. Elemental, petrographic and SEM-EDS data revealed that sediments are comprised of brown aquitard clay and well sorted grey fine sand. Arsenic in sand and clay samples ranged between 0.8 and 3.9 mg/kg and 0.3–3.2 mg/kg respectively. Dominant minerals in the aquifers sediments are phlogopite and biotite. Leaching of these minerals under reducing conditions is likely to provide higher concentration of As in the groundwater of the area.

Preservation and hydrocarbon generation potential of microalgal organic matter in product aggregates induced by Chlorella sp. MASCC-0008

Microalgae are one of the important sources of organic matter which, if preserved well in sediments, can generate hydrocarbons during burial diagenesis. However, the preservation mode of microalgal organic matter within product aggregates induced by marine microalgae has rarely been examined. Herein, a strain of eukaryotic marine microalgae, Chlorella sp. MASCC-0008, was used to conduct biomineralization experiments in an f/2 medium with a 0.02 mol/L Ca2+ ion concentration and various Mg2+ ion concentrations of 0.05, 0.06, 0.07 and 0.10 mol/L. It was found that the soluble organic matter of the microalgae contains amino acids and fulvic acids which can attract and absorb cations. With an increase in Mg2+ ion concentration in the experimental group with Chlorella sp., the aragonite content of the mineral precipitates increased whereas the calcite content decreased. In contrast, calcite was the sole mineral precipitated in the control experiments with no Chlorella sp.. Due to the porous structure of minerals, their organic matters were preferred to be preserved in aragonite aggregates compared to calcite aggregates. The TOC content of the minerals aggregates is the highest (0.45%) and the hydrocarbon generation potential (S1 + S2) of organic matter is the greatest (3.66 mg/g) in those precipitated in the medium with a Mg2+ ion concentration of 0.10 mol/L. Microalgal organic matter has significant hydrocarbon generation potential due to its effective preservation in the product aggregates formed by the microalgal biomineralization. Squalene is the most abundant alkene detected in the pyrolytic products. These results suggest that microalgae can induce precipitation of carbonate minerals, a process that facilitates the sequestration of organic matter within the product aggregates precipitated, thus potentially preserving this microalgal organic matter into the burial diagenetic realm where, if conditions are appropriate, hydrocarbons may be developed.

Use of δ13C and δ15N as Indicators to Evaluate the Influence of Sewage on Organic Matter in the Zhangjiang Mangrove–Estuary Ecosystem, Southeastern China

Organic matter in the productive mangrove–estuary ecosystem plays an important role in global climate changes. In recent years, the eutrophication in such areas caused by anthropogenic inputs of sewage has been revealed, highlighting the need to understand its influence on organic matter. In this study, δ13C and δ15N were used to reveal the effects of sewage on organic matters in the Zhangjiang mangrove–estuary ecosystem. Our results indicate that sewage contributed the most of the total particulate organic matter (41%) in the Zhangjiang estuary, while mangrove plants contributed most of the soil organic matter (45%) in the neighboring Yunxiao mangrove. Phytoplankton was another important source of organic matter, accounting for about 21.8% and 49.8% of the particulate and soil organic matter, respectively. Sewage was also a major source of dissolved inorganic nitrogen, providing 28.9%, 12.2%, and 100% of the total NO3−, NO2−, and NH4+ in the Zhangjiang estuary, respectively. This may be the major reason for the productive phytoplankton here, which contributed 21.8% and 49.8% of the total particulate and soil organic matter in the study area. Our results reveal the direct contribution and the potential effects of sewage on the contents and bioavailability of organic matter in mangrove–estuary ecosystems, providing new insights into understanding the response of coastal areas to the influence of human activities.

Characteristics of Organic Matter Composition and Oxidation Potential in Road Dust in Winter in Xi'an

Roads are the main places where urban people are exposed to atmospheric particulate matter from outdoor activities, and certain oxidatively active substances contained in road particulate matter are important components that induce the generation of reactive oxygen species (ROS), which in turn endanger human health. Here, we explored the characteristics of organic matter composition in water-soluble (WSM) and methanol-soluble fractions (MSM) of road dust in Xi'an and its oxidation potential (OP). Additionally, we investigated the organic fractions and their distribution based on parallel factor analysis (PARAFAC) and analyzed the correlation between organic matter types and OP. The results showed that the water-insoluble fraction of road dust in Xi'an contained more chromophoric organic matter with an average total concentration of (4.71±1.27)×104 R.U., which was 12 times higher than that of WSM[(3.96±1.10)×103 R.U.], of which low-oxidizing humic-like substances (HULIS) were the main organic matter (34.8%-43.7% of the total organic matter). The results of cluster analysis showed that the important sources of organic matter in road dust in Xi'an were fuel combustion and industrial production. The mean value of dust oxidative toxicity was (0.34±0.08) pmol·(min·μg)-1, with the water-insoluble fraction providing 70% of the total oxidative toxicity of dust particles, which was 2.4 times higher than the water-soluble fraction. The main precursors of oxidative toxicity of dust particles were metal elements, and special types of organic substances were also one of the important oxidative toxicity precursors, among which chromophore organic matter was the main cause of OP production in the WSM fraction (r=0.35, P<0.01), and protein-like organic matter and highly oxidized HULIS in WSM may have been the main two types of organic substances for OP production. However, there was no significant correlation between organic matter concentration in MSM and water-insoluble OP (OPTotal-OPWSM) (r=-0.04, P>0.1), so the oxidative toxicity of the water-insoluble particulate matter fraction was mainly generated from non-organic matter.

Variations of sediment organic phosphorus and organic carbon during the outbreak and decline of algal blooms in Lake Taihu, China

In this study, sediment organic phosphorus (OP) and organic carbon (OC) in Lake Taihu, China, as well as their relationships, were analyzed during the outbreak and decline of algal blooms (ABs) over a five-month field study. The results showed synchronous temporal changes in the sediment OP and OC contents with the development of ABs. In addition, there was a significant positive correlation between the sediment OP and OC (p < 0.01), suggesting simultaneous deposition and consumption during the ABs outbreak. The sediment OP and OC contents decreased significantly at the early and last stages of the ABs outbreak and increased at the peak of the ABs outbreak and during the ABs decline. These temporal variation patterns suggest that the sediment OC and OP contents did not consistently increase during the ABs outbreak, even though algae are an important source of organic matter in sediments. The depletion or enrichment of OC and OP in sediments may also depend on the scale of the ABs outbreak. The obtained results revealed significant differences in the sediment OC and OP contents between the months (p < 0.05). In addition, OP in the sediments was dominated by orthophosphate diester (phospholipids and DNA-P) and orthophosphate monoester during the ABs outbreak and decline, respectively. The active OC contents and proportions in the sediments in the ABs outbreak were significantly lower than those observed in the ABs decline period, demonstrating the significant impacts of the ABs outbreak and decline on the sediment OC and OP in Lake Taihu.

Overprinting of δ13Corg signatures in the sedimentary record linked to hydrocarbon migration: Evidence from Paleozoic drill cores from the Ordos Basin, China

Carbon isotopic compositions of organic matter (δ13Corg) provide critical information about changes in the global carbon cycle through Earth's history. However, several biotic and abiotic processes occurring after sediment deposition may overprint the original geochemical signals, complicating their paleoenvironmental interpretation. Here, we report multiple large and rapid δ13Corg swings (ranging from −30.8‰ to −23.3‰) from three Paleozoic drill cores in the Ordos Basin, Northwest China, which may reflect different organic contributions related to lithology. As a potentially important organic matter source, migrated hydrocarbons may substantially alter the original δ13Corg and total organic carbon contents (TOC), and their oxidation may contribute to forming 13C- and 18O-depelted carbonate cements in siliciclastic-dominated strata at depth. Cross-plots of δ13Corg and TOC from samples of the three drill cores all show similar hyperbolic trends that are well simulated using Rayleigh fractionation and a two-component mixing model, thus providing potential criteria for identifying the reservoir and the related hydrocarbon source in oil exploration. Our data call for a critical reassessment of the δ13Corg records of sedimentary rocks if hydrocarbon redistribution or mixing of organic sources is suspected to have occurred during the burial history.

Can spatial food web subsidies associated with river hydrology and lateral connectivity be detected using stable isotopes?

During and following lateral connections, aquatic organisms residing in the river channel may assimilate material from sources imported from oxbows, and oxbow residents may consume and assimilate material imported from the channel. Hydrology, lateral connectivity, and stable isotope ratios of fishes and mussels were analyzed for evidence of spatial food web subsidies between the active channel and oxbow lakes in the floodplain of the Guadalupe River, Texas. During surveys conducted between March 2016 and April 2017, fish, mussel, periphyton, seston, and riparian plant samples were collected in and around two oxbows and adjacent channel sites for analysis of stable isotope ratios. Biplots of δ13C and δ15N were graphed for basal sources and specimens of six common fish species, four sunfish species (Lepomis spp. combined), and two mussel species (Unionidae combined) captured from oxbows and the channel. Within each graph, polygons were drawn to indicate the space occupied by animals that could have assimilated feasible combinations of source materials originating from either oxbows or the river channel. Based on positions of animals within source polygons, riparian C4 grasses were not an important source of organic matter supporting biomass of fishes and mussels within the channel or oxbows. Overall, 84% of organisms had isotopic signatures consistent with assimilation of in situ sources, but also 76% of all organisms were inconclusive with regards to cross-habitat exchanges. Outliers that may have assimilated ex situ source material were observed for only 4% of 313 organisms from oxbows and 9% of 232 organisms from the channel, and some but not all of these cases followed high flow pulses that connected oxbows for extended periods. Several issues that compromise inferences from stable isotope analysis were identified, and estimation of spatial food web subsidies in fluvial systems could be enhanced by analyzing additional biomarkers, such as isotopic ratios of other elements and compound-specific stable isotopes, as well as additional sources, time-specific biotracers, and experimental approaches that directly track movement of sources and organisms in spatially structured food webs.

Multiple trophic pathways support fish on floodplains of California's Central Valley.

We used compound-specific isotope analysis of carbon isotopes in amino acids (AAs) to determine the biosynthetic source of AAs in fish from major tributaries to California's Sacramento-San Joaquin river delta (i.e., the Sacramento, Cosumnes and Mokelumne rivers). Using samples collected in winter and spring between 2016 and 2019, we confirmed that algae are a critical component of floodplain food webs in California's Central Valley. Results from bulk stable isotope analysis of carbon and nitrogen in producers and consumers were adequate to characterize a general trophic structure and identify potential upstream and downstream migration into our study site by American shad Alosa sapidissima and rainbow trout Oncorhynchus mykiss, respectively. However, owing to overlap and variability in source isotope compositions, our bulk data were unsuitable for conventional bulk isotope mixing models. Our results from compound-specific carbon isotope analysis of AAs clearly indicate that algae are important sources of organic matter to fish of conservation concern, such as Chinook salmon Oncorhynchus tshawytscha in California's Central Valley. However, algae were not the exclusive source of energy to metazoan food webs. We also revealed that other sources of AAs, such as bacteria, fungi and higher plants, contributed to fish as well. While consistent with the well-supported notion that algae are critical to aquatic food webs, our results highlight the possibility that detrital subsidies might intermittently support metazoan food webs.

Large differences in bacterial community composition of nearby shallow lakes surrounded by Nothofagus pumilio forest in Patagonia (Argentina)

Abstract Freshwater ecosystems are integrated in a terrestrial landscape, receiving continuously soil and plant-derived material. In Patagonia, the deciduous beech Nothofagus pumilio constitutes an important source of organic matter for aquatic environments. Here, I attempted to analyze bacterial communities, including genetic diversity and metabolic functioning, in four nearby lakes located under a N. pumilio forest (Chall-Huaco Mountain, Argentina). I combined fieldwork and experiments to assess physicochemical characteristics, bacterial community composition (BCC) and Carbon (C)-consumption. Physicochemical variables analyzed with NMDS showed a clear segregation of all the studied lakes. Similarly, BCC differed among lakes, maintaining its differences regardless of the seasons. Variables that significantly affected bacterial community structuring were dissolved P concentration and protein-like DOM component. The number of specialist operational taxonomic units was higher than that of generalists, but the latter doubled specialists in number of sequences. The last suggests that generalists may be responsible for the differences in BCC among lakes, and species sorting appears to be the main mechanism structuring the metacommunity. These results showed that even at a small geographic scale distinctive bacterial communities can be developed in lakes under the influence of N. pumilio forest.

Part A: Sanitization and use of sewage sludge in soil Technical Note 7 - Use of biosolids to recover degraded areas

Organic matter (OM) is fundamental in the rrecovery of degraded areas (RDA), particularly when concerning the soils’ chemical and physical properties. The biosolid obtained from sewage sludge is an important source of OM and nutrients. This technical note discusses the influence of both on RDA, as well as the potential for using biosolids for that purpose. OM acts as a reservoir of nutrients, which are gradually released; it improves the cation exchange capacity of the soil; and it can complex or chelate metals potentially toxic to plants. It is also highlighted its influence on the reduction of the specific mass of the soil, the formation of micro and macro aggregates, the improvement of soil stability, and the increase of soil specific surface. The practical aspects of biosolids use in RDA are discussed in the light of CONAMA Resolution 498/2020, mainly about the criteria for calculating the application doses. Two case studies are also presented.

Examining the production, export, and immediate fate of kelp detritus on open‐coast subtidal reefs in the Northeast Atlantic

AbstractKelp forests are highly productive coastal habitats and are emerging as important sources of organic matter for other ecosystems. Although their high rates of productivity and detritus release are expected to lead to substantial export of carbon, few studies have actually quantified rates of export or the persistence of detritus. We addressed this in eight subtidal kelp forests (Laminaria hyperborea) spanning the length (9° of latitude) of the United Kingdom. Specifically, we quantified detritus production, retention/export from source and adjacent habitats, and in situ decomposition rates. Detritus released via both dislodgment of whole plants and “May cast” shedding of old growth was highly variable between sites with greatest values recorded in our colder, northern sites. This was attributable to greater plant size biomass in northern regions, rather than plant density or dislodgement rates. On average, the annual production of kelp detritus was 4706 ± 700 g FW m−2 yr−1 or 301 g C m−2 yr−1. Low retention of detritus within the kelp forest and adjacent sedimentary habitats indicated very high rates of export (&gt; 98% across the study). A litterbag experiment showed detritus may take &gt; 4 months to decompose, suggesting great potential for long distance transport. Overall, our findings suggest that L. hyperborea forests export large amounts of detritus subsidies across their range, which can potentially shape the structure of distant benthic communities and constitute a relevant and largely overlooked flux in the coastal carbon cycle, which may represent an important component of natural carbon sequestration.

Spatial and vertical distribution of aerobic and anaerobic dark inorganic carbon fixation in coastal tropical lake sediments

The process of chemosynthesis can represent an important source of organic matter and energy across the benthic zone. However, its detailed vertical distribution and importance in relation to other microbial processes are still poorly investigated in inland aquatic ecosystems. Here, we determined the rates of dark inorganic carbon fixation (DCF) compared to heterotrophic bacterial production (BP) and oxygen consumption (SOC) across a depth profile of oxic to anoxic sediments in the littoral zone of nine tropical lakes located in one of the most important coastal conservation areas, the Jurubatiba Sandbank National Park (Rio de Janeiro, Brazil). Rates of DCF were highly variable (means of 0.1–1.2 mmol C m−2 d−1) among the studied lakes, with mostly production occurring below 10 mm of sediment in the anoxic zone. Although presenting a relatively low contribution in relation to BP and SOC, our study showed extensive microbial metabolism in the anaerobic sediment below the top centimeter, highlighting the importance of studying microbial processes across depth at fine scales. To our knowledge, it is the first study to show detailed vertical DCF rates in coastal tropical lake sediments, thus contributing to a better comprehension of the microbial role in the biogeochemical cycles of aquatic systems.

Source rock characteristics and sedimentary environment analysis of Lucaogou Formation in the eastern Jimusaer Sag, Junggar Basin

In recent years, shale oil has gradually become the focus of oil exploration. The source rocks of Lucaogou Formation in the east of Jimusaer Sag of the Junggar basin have great shale oil potential. However, there is still much controversy regarding the sedimentary environment of the source rocks which restrict shale oil exploration. In order to address this problem, 45 mudstone samples of Jx-1 well are selected for testing and analysis. The results show that the Permian Lucaogou Formation in the Jimusaer Sag is developed with high quality source rocks, and the organic matter type is mainly type II, and the source rocks are in mature stage. Both higher terrestrial plants and aquatic algae are important sources of organic matter in source rocks, but the source of organic matter is still dominated by lower aquatic organisms. The source rocks of Lucaogou Formation are mainly deposited in reducing environment, and the water salinity is high, which is conducive to the preservation of organic matter.

Impact of the Paleoclimate, Paleoenvironment, and Algae Bloom: Organic Matter Accumulation in the Lacustrine Lucaogou Formation of Jimsar Sag, Junggar Basin, NW China

Shale oil exploration has been a key area of onshore oil and gas exploration in China in recent years. In this study, organic geochemistry and element geochemistry are united to study the shale oil and source rock in the Lucaogou formation of Jimusar sag, in order to reveal the paleoclimate, paleoenvironment, source of organic matter, and factors affecting organic matter accumulation and shale oil generation. The shale oil in the study area is mainly accumulated in two strata with good reservoir properties and oiliness, known as the upper sweet spot and lower sweet spot. Indexes of biomarkers and sensitive elements revealed the warm and semi-arid paleoclimate during Lucaogou formation, and the water column was brackish to salty. Water stratification caused a suboxic to anoxic environment in the deep-water column and coincided with the anoxic photic zone phenomenon. Compared with the lower sweet spot, the more humid climate, deeper and fresher water, and stronger water stratification characterize the upper sweet spot during sedimentation. This made the photic zone with freshwater more suitable for the reproduction of algae in the upper sweet spot. Meanwhile, the organic matter was well-preserved in the anoxic zone. Volcanic ash caused algae bloom, which promoted primary productivity and ensured the supply of organic matter. The composition and distribution pattern of biomarkers prove that phytoplankton is the most important source of organic matter in the study area and the contribution of higher plants is insignificant. The relationship between parameters of paleoproductivity and the redox condition versus total organic carbon (TOC) suggests that compared with the preservation conditions, the input of organic carbon is the most important controlling factor of organic matter accumulation in the study area.

Water extractable organic matter and iron in relation to land use and seasonal changes

The soil carbon pool is an essential part of the global carbon cycle although it is sensitive to climatic changes and the local environment. Terrestrial areas are important sources of organic matter for aquatic ecosystems and the fluctuation of different soil minerals and elements is largely influenced by land use and season changes. We studied water-extractable organic matter (WEOM) properties including iron (Fe), water extractable organic carbon (WEOC) and spectral characteristics from forests and arable soils to evaluate the effects of land use and seasonal change on WEOM and Fe in terrestrial areas. We collected soil samples randomly from arable land (AR), broadleaf (BL) and aged needle leaf forests (NL) and extracted WEOM for analysis using rainwater. Results of WEOC and Fe showed similar trend seasonally and were higher in forest sample than in AR. WEOC was high in the upper layer while Fe was independent of the depth and higher in AR. On the other hand, specific ultra-violet absorbance at 254 nm (SUVA254) and a proxy for aromaticity significantly varied with both land use and season and was on average two times higher in arable land than forests during spring and summer. Humic-like components significantly varied between the studied sites seasonally while tyrosine-like was affected by season only. The relative abundance of both humic-like and tryptophan-like components were significantly affected by land use while [Fe]: [WEOC] ratio was also high in arable land and negatively correlated with humic-like components in forest sites. As observed from ratio and Fe oxidation rate constant, summer presented ideal conditions for WEOM interactions. The synchronized seasonal WEOC and Fe changes indicate an enhancement of Fe mobility by DOM whereas the differences observed between sites especially from the high humic- and protein-like components in NL and BL reflects the effect of land use.

Non‐target screening of leaf litter‐derived dissolved organic matter using liquid chromatography coupled to high‐resolution mass spectrometry (LC‐QTOF‐MS)

AbstractLeaf litter‐derived dissolved organic matter (DOM) is an important source of organic matter entering the mineral soil, but characterization of leaf litter DOM is often not detailed enough to understand DOM dynamics and processes at the molecular level. (Ultra‐) high‐resolution techniques such as Fourier transform ion cyclotron resonance mass spectrometry (FT‐ICR‐MS), Orbitrap mass spectrometry and quadrupole time‐of‐flight (QTOF) mass spectrometry have brought a new level of detail to (D)OM research by providing molecular formulae and information on molecular structures. We present a novel approach for leaf litter DOM characterization that includes non‐target screening using liquid chromatography (LC) coupled to high‐resolution QTOF‐MS. A method validation test showed that out of 26 spiked naturally occurring DOM molecules in a leaf litter DOM sample, 23 were found as features. After implementation of additional filtering to exclude certain combinations of heteroatoms (that are difficult to resolve even by the newest high‐resolution MS instruments), including molecular formulae with P atoms, 22 molecular formulae were correctly assigned. Although a large part of the annotated molecular formulae was unique for the respective litter sources, the molecular compound class distribution was similar for deciduous, coniferous and mixed leaf litter DOM. Most intense masses were detected in the 100–300 Da mass range, showing a bias of QTOF‐MS towards lower masses compared to FT‐ICR‐MS. The use of LC in combination with QTOF‐MS for leaf litter (D)OM characterization provides, together with Orbitrap‐MS, a more widely available and lower cost high‐resolution MS alternative to FT‐ICR‐MS. Novel approach to the characterization and analysis of leaf litter derived DOM. Non‐target screening using LC‐QTOF‐MS and the patRoon R package. Similar molecular compound class distribution for three leaf litter sources. High‐resolution DOM characterization alternative to FT‐ICR‐MS.Highlights Novel approach to the characterization and analysis of leaf litter‐derived DOM. Non‐target screening using LC‐QTOF‐MS and the patRoon R package. Similar molecular compound class distribution for three leaf litter sources. High‐resolution DOM characterization alternative to FT‐ICR‐MS.

Pore structure characteristics and its effect on adsorption capacity of Niutitang marine shale in Sangzhi block, southern China

Characteristics of shale pore structures may play an important role in natural gas accumulation and consequently estimating the original gas in place. To determine the pore structure characteristics of Niutitang marine shale in the Sangzhi block, we carried out [Formula: see text] adsorption-desorption (LP-[Formula: see text]GA), [Formula: see text] adsorption (LP-[Formula: see text]GA), and methane isothermal adsorption on shale samples to reveal the pore size distribution (PSD) and its impact on the adsorption capacity. Results indicate that the Niutitang Shale is in stages of maturity and overmaturity with good organic matter, and they also indicate well-developed interparticle, intraparticle, and organic pores. Quartz and clay are found to be the main minerals, and the high illite content means that the Niutitang Shale is experiencing the later stage of clay mineral transformation. Various-sized shale pores are well-developed, and most of them are narrow and slit-like. For pores with diameters of 2–300 nm measured with LP-[Formula: see text]GA, mesopores (2–50 nm) contribute most of the total specific surface area (SSA) and total pore volume (TPV) in comparison to macropores (50–300 nm). For micropores ([Formula: see text]) tested by LP-[Formula: see text]GA, the PSD appears to be multimodal; shale pores of 0.50–0.90 nm diameter contribute most of the SSA and TPV. [Formula: see text]-SSA and [Formula: see text]-SSA indicate positive correlations with their corresponding TPV. The total organic matter (TOC) has good correlation with the SSA and TPV of micropores. The Langmuir volume positively correlates with the total SSA. Additionally, the TOC content has a good correlation with the Langmuir volume, which is consistent with the observation of well-developed fossils of diatoms and organic pores. As an important source of organic matter, more diatoms mean more organic matter, larger TOC values and quartz content, larger SSA and TPV of micropores, and, of course, stronger shale adsorption capacity. The results provide important guidance for the exploration and development of shale gas existing in the Sangzhi block.

Evaluation of hydrothermal pretreatment for biological treatment of lignocellulosic feedstock (pepper plant and eggplant)

Plant residues are an important source of organic matter that can be degraded by aerobic or anaerobic biological processes. However, due to the presence of lignocellulosic material, these residues are not easily biodegradable. Greenhouse crops, such as pepper and eggplant, generate large amounts of this type of waste after harvesting. In this study, a hydrothermal pretreatment was applied at 120 °C and different times to evaluate the enhancement of C and N solubilization in these residues. The highest solubilization of C was obtained at 40 min, as no significant increases were observed at higher times (100% and 68% for pepper plant [PP] and eggplant [EP], respectively). The solubilization of N shows a linear behavior (PP r2 = 0.9670 and EP r2 = 0.9395). Aerobic and anaerobic biodegradability were also evaluated, with better results found for the anaerobic digestion of the pretreated substrates. The nutrients balance with anaerobic co-digestion of both pretreated substrates (50:50% wt) improved methane production by 1.4 and 1.8 with respect to the substrates individually.

ЭЛЕМЕНТЫ ТЕХНОЛОГИИ ВОСПРОИЗВОДСТВА ПОЧВЕННОГО ПЛОДОРОДИЯ

To increase productivity of arable land and the impact on reproduction of soil fertility while using a reasonable amount of human energy per hectare of arable land it is important to work systematicly with crop rotations and organic-mineral supply system, that suggests exposure on the whole agrobiological system. A technique that has a significant impact on soil fertility is the use of fertilizers - organic and mineral, as well as maintaining an optimal acidic soil regime through chemical reclamation. To obtain a sufficient amount of fresh organic matter in the soil, it is necessary to have a set of crops in the sowing structure that have the ability to create a large biomass as a result of normally occurring processes of photosynthesis. Perennial legumes and cereals, their mixtures are the most important source of organic matter for the soil and should have in the rotation of 33-40% of the occupied area of sowing. It is established that the presence of 17% of meadow clover in the structure of sowing stabilizes the state of humus, 33% - provides its expanded reproduction. Long-term studies of ISA - branch center FNAC VIM shows that on dark-gray forest soil the greatest quantity of organic matter (dry weight) forms a legume-grass mixture - 10.4-11.8 t/ha, grasses (grass mixture) with the use of mineral fertilizers - 10.2 t/ ha, red clover - 6.8-8.9 t/ha. Crop-root residues of maize grown for silage without application of fertilizers are 6.35 t/ ha, with mineral fertilizers - 7.62 t/ha of organic matter (dry weight). The amount of plant residues, including straw from winter wheat, reaches up to 7.8 t/ha with fertilizers, without fertilizers - 7.2 t/ha.

Litterfall and Nutrient Return in Eucalyptus dunnii Maiden in the Pampa Biome, Brazil

The objective of this study was to evaluate litterfall and nutrient return in a Eucalyptus dunnii Maiden stand in the Pampa Biome. Four plots were established and four litter collectors per plot were distributed systematically with an area of 0.5 m&amp;sup2; and four subplots used to collect large branches of &amp;gt; 0.5 cm diameter. The collections were carried out biweekly with monthly chemical analyzes over 12 months. The annual litterfall was 8.48 Mg ha-1, of which 59% was composed of leaves. In general, the leaves had the highest macronutrient contents except for Mg. The total macronutrient return was 215 kg ha-1, in the following order: Ca &amp;gt; N &amp;gt; K &amp;gt; Mg &amp;gt; S &amp;gt; P, with the leaves responsible for the return of 73% of the total. The litter represented an important source of organic matter and nutrients, and temperature is the climatic variable that best explains the pattern of production.