Humified Organic Matter Research Articles

ESTIMATION OF POPULATION DYNAMICS OF MIXOTROPHIC-SYNTHETIC MICROFLORA OF SOUTHERN CHERNOZEMS UNDER VARIOUS METHODS OF SOIL TREATMENT IN DRY-STEPPE AGRICULTURAL LANDSCAPES

With the participation of various ecological groups of microorganisms, the processes of humification and mineralization of organic matter of vegetable or animal origin. This article presents data on the quantitative analysis of mixotrophic-synthetic microflora of chernozem soils depending on the types of treatment used. Depending on the type of treatment in the soil, various conditions of density, aeration, and moisture can form, which affect the activity of microbiological processes. Microorganisms of the mixotrophic-synthetic group have a powerful enzymatic apparatus, they participate not only in the mineralization of organic residues, but also in the synthesis of humic substances. In the work, the dynamics of the number of such microorganisms of the mixotrophic-synthetic group as microscopic fungi and actinomycetes is estimated. The experimental options included four types of soil cultivation: deep plowing, shallow plowing, flat-cut tillage and disking. A quantitative account of microorganisms showed that in all variants of the study there was a high degree of soil enrichment as actinomycetes and microscopic fungi. Mathematical data processing did not reveal significant differences between the experimental options.

The geneses of sedimentary organic matter with anomalous 13C-enriched isotopic composition in saline and freshwater lakes: A case study of lacustrine source rocks from Dongpu and Qikou sags, Bohai Bay Basin, eastern China

The carbon isotopic composition of sedimentary organic matter (δ13COM) is notably important for the genetic identification of source rock and its products. The sapropelic organic matter (mostly plankton with high hydrogen index) is generally depleted in 13C as compared to humic organic matter (mainly higher plants with lower hydrogen index). However, some lacustrine sediments contain sapropelic source rocks with anomalous 13C-enriched isotopic ratios, especially reported in freshwater lakes. The purpose of this study is to discuss the geneses of lacustrine sedimentary organic matter characterized by anomalous 13C-enriched ratios in saline and freshwater sediments. To this end, we integrate the detailed organic geochemical data (including Rock-Eval analysis data, total organic carbon contents, total organic carbon isotopic compositions, biomarkers, and trace element concentrations) of 64 saline lake sediments and 39 freshwater lake sediments obtained from the Paleogene Shahejie Formation of Dongpu sag and Qikou sag, separately, in Bohai Bay Basin of eastern China. Both sags exist samples with high hydrogen index values (HI > 400 mg/g) and high total organic carbon contents (TOC > 2%), but anomalous 13C-enriched isotopic ratios (up to −21.1‰). In Qikou sag, the δ13COM values of sapropelic kerogen correlate positively with TOC contents. The anomalous enrichment of 13C in organic matter is associated with extremely high productivity of algae, such as algae bloom. In Dongpu sag, the enrichment of 13C in organic matter is attributed to the significant increase of drought and salinity. High salinity and aridity climate may lead to the abundance of C4 plants and Chlorobium as well as the enrichment of 13C in plankton.

Physico-chemical and spectroscopic quality assessment of compost from date palm (Phoenix dactylifera L.) waste valorization

Organic matter (OM) is a vital component for a healthy soil, its lack arise a major problem for farmers who need to use commercialized fertilizers with high costs. Considering circular economy approach and for increasing OM availability, water soaked date palm waste was co-composted with goat manure in aerated windrow to produce a soil organic amendment. The OM biodegradation was mainly controlled based on biological parameters and spectroscopic techniques. The results showed a rapid temperature increase during the first week, and a relatively long compost maturity phase. The OM content reduction was of 36% and C/N ratio shifted from 60 to 20 at the process end. During the composting process, the specific ultraviolet absorbance SUVA254, SUVA269 and the SUVA280 values increase confirmed the OM and hydrophilic compounds degradation, as well as substrate content oxidation into aromatic compounds. The Fourier Transform Infrared Spectroscopy (FTIR) analyses of the different samples collected during the process exhibited both OM biodegradation and mineralization. The 3 absorption ratios 1650/2845, 1525/2925 and 2920/1640 confirmed an aromaticity increase by aromatic structures biosynthesis, such as humic-like and fulvic-like substances, with the decomposition/transformation of aliphatic components, polysaccharides, and alcohols. Fluorescence excitation-emission matrix (FEEM) spectroscopy coupled with parallel factor analysis (PARAFAC) evidenced the dissolved organic matter (DOM) humification. A four-component model was obtained, i.e. humic-like component (S1, S2 and S3) and fulvic-like component (S4). The produced compost didn't exhibit any phytotoxicity evidenced by cress seed germination index exceeding 80%. All the analyses confirmed the good quality of the compost issued from mixed date palm waste and goat manure.

Effects of biochars on the fate of antibiotics and their resistance genes during vermicomposting of dewatered sludge

It is currently still difficult to decrease the high contents of antibiotics and their corresponding antibiotic resistance genes (ARGs) in sludge vermicompost. To decrease the environmental risk of vermicompost as a bio-fertilizer, this study investigated the feasibility of biochar addition to decrease the levels of antibiotics and ARGs during vermicomposting of dewatered sludge. To achieve this, 1.25% and 5% of corncob and rice husk biochars, respectively, were added to sludge, which was then vermicomposted by Eisenia fetida for 60 days. The sludge blended with corncob biochar showed increased decomposition and humification of organic matter. Higher biochar concentration promoted both the number and diversity of bacteria, and differed dominant genera. The level of antibiotics significantly decreased as a result of biochar addition (P < 0.05), and tetracycline was completely removed. Relative to the control without addition of biochars, ermF and tetX genes significantly decreased with corncob biochar treatment (P < 0.05). Rice husk biochar (5%) could effectively decrease sul-1 and sul-2 genes in vermicompost (P < 0.05). However, the abundance of the intI-1 gene increased with biochar concentration. This study suggests that biochar addition can lessen the antibiotic and ARG pollution in sludge vermicompost, depending on the type and concentration of biochars.

Origin of hydrocarbon and non-hydrocarbon (H2S, CO2 and N2) components of natural gas accumulated in the Zechstein Main Dolomite (Ca2) strata in SW part of the Polish Permian Basin: stable isotope and hydrous pyrolysis studies

The genetic identification of natural gas accumulated in the Zechstein Main Dolomite (Ca2) strata in the SW part of the Polish Permian Basin (PPB) was determined by means of analytical and experimental methods of petroleum geochemistry including molecular and isotopic compositions, i.e. δ13C of C1–C5 hydrocarbon gases and CO2, δ2H of C1–C3 hydrocarbon gases and δ34S of H2S of natural gas and gases generated during hydrous pyrolysis (HP) experiments and δ15N of N2 of natural gas as well as results of geochemical analyses of organic matter of the Ca2 source rock samples including Rock-Eval (RE) pyrolysis and elemental and stable C isotope compositions of kerogen. Four HP experiments conducted on two composite samples from Ca2 strata with different (II and III) prevailing genetic type of kerogen each, led to production of thermogenic gas which was used for geochemical comparison with natural gases accumulated within Ca2 strata. Hydrocarbon gases of analysed accumulations belong to two different genetic groups: (i) including gases sourced from sapropelic organic matter (type II kerogen) dispersed in the Ca2 strata produced during either both microbial and thermogenic processes or solely thermogenic processes and (ii) comprising gases not genetically related to the Ca2 source rock, originated from humic organic matter (type III kerogen) of high maturity from deeper buried strata. CO2 related to Ca2 strata primarily was produced during thermal decarboxylation of kerogen and carbonate dissolution by acid fluids, while CO2 unrelated to Ca2 strata was generated from thermal decomposition of deeper buried carbonate formations. H2S has been generated during thermal decomposition of sulphur-containing organic matter and thermochemical sulphate reduction (TSR) processes. The coexistence of CO2 and H2S indicates that these components might have been produced together by TSR and less microbial sulphate reduction (MSR) processes. Molecular nitrogen in analysed natural gases was generated mainly during thermal decomposition of organic matter, but atmosphere-derived molecular nitrogen is presumably also present.

Research on efficient denitrification system based on banana peel waste in sequencing batch reactors: Performance, microbial behavior and dissolved organic matter evolution

Nitrate pollution presents a serious threat to the environment and public health. As an excellent heterotrophic denitrification carbon source, banana peel (a kind of agricultural waste) provides a feasible alternative to deal with the persistent high concentrations of nitrate pollution. Although the feasibility and economy of banana peel for denitrification have already been reported, the long-term stability and mechanism were still unclear. The coupling mechanism of organic matters and microorganism in the denitrification process was systematically investigated through a 17-cycle experiment. The results showed that significant NO3−-N removal load and rate of 164.42 mg/g and 4.69 mg/(L·h) after long-term tests could be obtained. Organic matter analysis and 16S rRNA sequencing showed that the evolution of organic matter was dominated by Anaerolineaceae (fermenting bacteria), and, in the final step, the humification of organic matter was realized. Moreover, the presence of Lentimicrobium (denitrifying bacteria) was indispensable for the continuous removal of high concentrations of nitrate. The main functional gene of nitrogen transformation in this reaction system was NirS (haem-containing). This lab-scale heterotrophic denitrification process could contribute to a better understanding of the carbon and nitrogen cycles in the biogeochemical cycles to some extent, and it also provides a reference for the construction of highly efficient nitrate degradation reactors, based on agricultural wastes.

Formation of Forest Biogeocenoses on Disturbed Lands of the Northern Caspian Region

Features, trends and the rates of formation of new forest biogeocenoses on anthropogenically disturbed lands, in particular, on an unused pond created on heavy loamy soils in the semi-desert of the Northern Caspian region are analyzed. At an early stage of spontaneous pond colonization by vegetation, the maximum influence on its development was exerted by the presence of a seed source 300 meters away – in the Arboretum of the Dzhanybek Research Station of the Institute of Forest Sciences (Russian Academy of Sciences) with 120 species of introduced tree and shrub plants. Initially 34 pioneer species colonized the lower parts of the unused pond, and 29 species survived by 2018. The formation of intrazonal willow-oleaster-poplar communities of a quasitugai type with a grass-wet-meadow association has been revealed. Their development was influenced by geographical isolation, self-regulation under rather unstable moisture conditions caused by occasional flooding by melt snow waters and bogging. A differentiation of the upper part of the soil-forming rock brought to the surface has occurred. The forest leaf litter has been formed from uncut moquette with a thickness of 1–2 cm, reaching currently quite substantial deposits of 0.953±0.196 kg/m2 , with the ash content reaching 13.85%. Ca prevails absolutely in the ash composition; while the amounts of Mg, Fe, and K are significantly lower. A humus horizon has been formed and the soil effervescence depth has changed. In the whole, for almost 40 years of vegetation colonization, the previously infertile substrate has acquired features of an immature soil, which is characterized by manifesttion of humus-accumulative process, gradual humification of organic matter and decarbonization of the material. In general, compact, diverse in structure, spontaneously arising self-developing forest biogeocenoses could significantly transform disturbed semi-desert territories. The peculiarities of their structure and the composition of emerging species make it possible to properly choose species preferred for landscaping.

Effects of combination of tillage with olive mill wastewater on soil organic carbon groups in arid soils

Soil fertility in arid areas is poor due to the climatic conditions, weak natural biomass and inappropriate agricultural practices. Soil fertility can be determined by asses the chemical composition of soil organic carbon (SOC) and soil organic matter (SOM) quantity in different systems of soil management. To identify efficient field management practices for enhanced soil fertility in arid regions, the impact of combination tillage with olive mill wastewater as compared to native vegetation were studied for more than 20 years of field experiment. Soil samples were collected from three field management treatments and three replicates for each treatment localized in Chaâl area in southern Tunisia. Field experiment includes uncultivated soil (NC) for more than 80 years (since 1936), with native vegetation, cultivated and tilled soil (CT1) and tilled soil with addition of 5 l.m−2 of olive mill wastewater (CT2). Soil properties were assessed and principal component analysis (PCA) was executed. In addition, structural functional carbon groups were investigated using MIR spectroscopy. The results showed that NC had the highest significant values of moisture content, soil organic matter, and exchangeable cations. This is likely to be due to the role of humified organic matter with colloidal properties. Significant reduction in pH and cation exchange capacity values were found in CT2 conversely to CT1. Olive mill wastewater mineralization provided soluble ions increasing electrical conductivity. MIR analyzes determined higher absorbance of aromatic/aliphatic C in NC and CT2 more than in CT1. Long-term using olive mill wastewater application improved soil carbon groups, which lead to the SOC stabilization for long-term sequestration in arid climates.

The long term effect of Olive Mill Wastewater (OMW) on organic matter humification in a semi-arid soil

This study investigates the performance of soil and OMW microfloras in OMW organic matter humification in soil. In order to highlight the role of OMW and soil microfloras in the processes of OMW organic matter humification, either OMW or soil was sterilized with autoclaving. The study was carried out in microcosms of 1l containing 500 g of raw or sterilized soil, to which was added 200 ml of raw or sterilized OMW. After 24 months of incubation, the amount of phenolic compounds in the different microcosms was statistically indifferent compared to the control. However, TG-DTA and FTIR analysis of soil humic acids showed that recalcitrant OMW phenolic compounds remain in soil humus in the microcosm: sterilized OMW + raw soil, even after 24 months. Results show that humic acids detected in presence of OMW microflora are loaded with proteins and carbonated compounds and deprived of phenolic compounds and aliphatics with long chain, while humic acids detected in absence of OMW microflora are loaded with phenolic compounds.

Change and spatial variability of soil organic matter humification after long-term tillage and olive mill wastewater application in arid regions

The changes of soil organic matter (SOM) humification induced by long-term combination of tillage and olive mill wastewater (OMW) application compared to natural and cultivated soil have been little investigated. This study aimed to compare effects of no cultivation with natural vegetation soil (NC), tillage (CT1) for 80 years and combination of tillage with OMW application (CT2) for 20 years on SOM humification degree. Fluorescence spectroscopy and UV-visible ratios (E4/E6 and CHA/CFA) were used to study soil humic acids (HAs). The SOM and humification distribution was determined for the whole field area using the Inverse Distance Weighting method. Results showed that SOM content, fluorescence emission area and E4/E6 and CHA/CFA ratios were higher in NC. Tillage reduced SOM amount, molecular size, aromatic condensation and humification degree as shown by the strong correlation between fluorescence area and CHA/CFA ratio in CT1 conversely to E4/E6. Contradictory results between fluorescence emission area and E4/E6 ratio found in NC and CT1 indicated that E4/E6 ratio was not a reliable indicator of SOM humification degree. The SOM amount, CHA/CFA ratio and emission fluorescence area increased conversely to E4/E6 ratio in CT2. This revealed a greatly humified organic matter and aromatic structure condensation with tillage and OMW application. Spatial distribution showed a progressive increase of SOM and CHA/CFA from north-west to south-east linked to the positive relationship between CHA/CFA ratio and SOM amount independent of soil management practices. Soil amended with OMW provided a favourable environment for the development of HAs which improved soil quality. The UV-visible ratio CHA/CFA with fluorescence emission area can be used as parameters to investigate SOM humification degree.

Вплив систематичного удобрення на біологічну активність сірого лісового грунту

The article presents the results of research on the biological activity of gray forest soil depending on the systematic use of organic and mineral fertilizers. It is established that effective reproduction of humus in gray forest soil is provided by organo-mineral (12 t of manure together with N80P60K80 application per 1 ha of crop rotation area) and organic (24 t/ha of manure), respectively 36,5 t/ha, and 35,6 t/ha. The application of only mineral fertilizers in the norm of N80P60K80 per 1 ha of crop rotation area resulted in a decrease in humus reserves by 9 % relative to the initial level (32,4 t/ha). The highest degree of humification of organic matter provided the option of applying organic fertilizers (60 t/ha) both separately – 36,0% and compatible with mineral – (60 t/ha manure + N80P60K80) – 34 %. Prolonged use of organic and mineral fertilizers in crop rotation significantly increased the total number of microorganisms in the soil. The result was increased decomposition of organic matter and increased release of CO2 from the soil. The areas with the highest biological activity and CO2 intensity were characterized by areas where the soil was systematically enriched with fresh organic matter. The intensity of biological processes in the organo-mineral system increased by 67 % relative to the variant without fertilizers and by 30 % relative to the variant with only N80P60K80. The use of organic and mineral fertilizers in one system stimulated the process of decomposition of fiber – at the level of 78,5 %, which in percentage terms exceeded the value of the indicators obtained for a purely mineral fertilizer system.

The characteristics of a relic steppe of Northeast Asia: refuges of the Pleistocene Mammoth steppe (an example from the Lower Kolyma area)

An ecosystem of a relic petrophytic steppe was studied in the Lower Kolyma River region. The soils of the steppe area significantly differed from those of the surrounding open larch forests in the following features: the presence of humus-accumulative horizons with a high content of roots; low moisture content; high heat supply; an extremely contrasting temperature regime; neutral reaction; decreased potential acidity; higher humification of organic matter; accumulation of exchangeable bases, soluble salts and organic nitrogen; and the presence of carbonate neoformations in the form of cutans on pebbly units. They also had a high microorganism saturation of the soil profile, a high share of actinomycetes in the microbial community, as is typical for arid soils, and a shift in the ratio of potential enzyme activities toward oxidoreductases, which reflects a deeper destruction of plant residues and more intensive humus formation. The petrophytic steppe had high bioproductivity. The growth rate of the aboveground phytomass (ANP) was closer to the true steppes of Central Asia than to the zonal tundras of the Arctic and Subarctic; such communities can serve as models for paleoreconstructions and study of the Late Pleistocene cold steppes - mammoth fauna large grazing mammals habitats.

Evaluation of the Maturity of the Compost Produced at the Compost Production Site of the NGO ENPRO in Lomé (Togo) Using the UV-Visible Spectroscopy

Composting is a method of recovery of household solid waste. But to be useful to agriculture the compost resulting from this process must be mature. The objective of this study is to evaluate the maturity of three types of composts produced on the garbage composting unit of the NGO ENPRO in Lome. Three types of compost (garbage, fruit waste, animal litter) were made in windrows for at least 3 months. The maturity of the composts was determined according to the basic chemical analysis, by UV-Visible spectroscopy. UV-visible spectroscopy performed on the three types of compost at the end of the 3rd and 4th months of composting shows a decrease in the E4/E6 ratio (465 nm/665 nm), Q2/Q6 (280 nm/664 nm) and Q4/Q6 (472 nm/664 nm) for two types of composts characteristic of increasing humification of organic matter. The data from the various elementary analyzes and particularly from UV-Visible spectroscopy show that composts N°1 and N°2 can be considered ripe after 3 months of composting. But the values of the various elementary analyzes clearly show that compost N° 3 is not yet ripe. UV-Visible spectroscopy is a relatively effective method for evaluating the maturity of compost.

Organic matter of tropical soil with coffee growthin CO2 enriched atmosphere

The increase of atmospheric CO2 should result in higher carbon fixation by plants of the C3 photosynthetic cycle, such as coffee. However, not much is known about the relationship between atmospheric CO2 increase, higher carbon fixation through photosynthesis and the potential carbon sequestration in soil. Based on the hypothesis that there will be greater stabilization of carbon in soil due to increase of atmospheric CO2 concentration, the study was carried a field coffee grown area with FACE (Free-Air Carbon dioxide Enrichment) system. The CO2 enrichment treatment maintained the concentration of this gas 200 ?mol mol-1 above the ambient value. The stocks of carbon and nitrogen in soil and some attributes related to the humification of organic matter were evaluated 43 months after the beginning of the experiment. In addition, the decomposition of residues of coffee plants (leaves) and the emission of N2O were also evaluated. The stocks of carbon and nitrogen in soil of at 0-5 cm layer were in average 18% higher (2.6 Mg ha-1 carbon and 0.2 Mg ha-1 nitrogen) in CO2 enrichment treatment. As the decomposition of vegetal remains was not affected by atmospheric CO2 enrichment, the increase of carbon and nitrogen in soil was due to the greater contribution of vegetal material, which resulted in a less humic organic matter. In the equilibrium between carbon soil stabilization and N2O emission, the enrichment of atmospheric CO2 in the coffee crop resulted in negative feedback for global warming due to the increased sequestration potential of carbon by soil.

Humic substances of differently matured composts produced from municipal solid wastes and biomass of energetic plants

Abstract The aim of the study was to assess the transformation of humic substances during composting of biomass of energetic plants and municipal solid waste. The type of the organic material to be composted and the type of technology used affect the course of the humic substances transformation and formation of compost maturity parameters. Compost produced from the mixture of energetic willow and hay biomass contained humic substances with higher share of low-molecular fractions and lower share of humic acids in total organic carbon than those produced from municipal solid wastes. Obtained results also showed that insoluble alkali fraction plays an important role in humification process by its convertion to a new humic substances. Share of humic and fulvic fractions in relation to the total organic carbon appears to be reliable indicator of composting as a process of enhancing organic matter humification.

Effect of bean dregs amendment on the organic matter degradation, humification, maturity and stability of pig manure composting

The purpose of this study was to effectively dispose of bean dregs (BD) using composting technology, which could provide a theoretical basis for the disposal of BD. Therefore, the influence of different quantities of bean dregs (BD) (0%, 5%, 10% and 15%, w/w with a dry base of pig manure (PM)) on the decomposition and humification of organic matter during PM-composting was investigated, and a 0% BD amendment was used as the control (CK). Wheat straw was used as a bulking agent. Compared to the CK, the BD amendment promoted the degradation of organic matter. The degree of organic matter degradation increased by 16.46–25.04% upon BD amendment. Furthermore, the BD amendment improved humification and increased indices of the humification ratio (HR), percentage of humic acids (PHA), degree of polymerization (DP) and the humification index (HI). Furthermore, Fourier transform infrared (FTIR) spectroscopy indicated that the aromatic structure was enhanced with the BD amendment, and excitation-emission matrix (EEM) fluorescence spectra showed increased humic-like substance production. Additionally, the dissolved organic carbon (DOC), germination index (GI), electrical conductivity (Ec) and carbon/nitrogen (C/N) influenced the maturity and stability of composting. Comparatively, a 10% BD addition showed the optimal performance among all PM-composting treatments.

Potential fate of wetland soil carbon in a deltaic coastal wetland subjected to high relative sea level rise

The fate of soil carbon in eroding coastal wetlands is of great concern, given the potential for a feedback loop from coastal wetland soil that would dramatically increase atmospheric CO2 concentrations. The biogeochemical transformations and overall fate of this soil carbon upon coastal erosion were investigated through geophysical and spectroscopic analysis of soil and associated dissolved organic matter. Bay water and core sections were collected across transects encompassing both intact and eroded, submerged, sections of a coastal marsh in Barataria Bay, Louisiana. We noted: i) a vertical increase in carbon content, humification of organic matter, and decrease in biotic degradation with depth at all sites; ii) an erosion and ultimate collapse of the top ~ 0–20 cm of the intact marsh’s edge into the bay water due to the undercutting caused by tidal/wave forces; iii) the loss of the stored carbon from the submerged site’s top 10 cm layer; and iv) leaching, dilution, abiotic, and biotic degradation of the marsh carbon due to the exposure to the bay water. This erosion and degradation of wetland soil carbon stores demonstrates the potential impact of rising sea levels on the future fate of coastal wetland carbon and atmospheric CO2 levels.

Stabilizate from Autoclaved Municipal Solid Waste as a Source of Valuable Humic Substances in a Waste Circular Economy

One of the solutions in unsorted municipal waste management is autoclaving, which maximize the amount of waste for recycling. After autoclaving, however, up to 30% of autoclaved waste, called organic remaining fraction (ORF) is still unstabilized and cannot be landfilled but must be subjected for further stabilization, e.g. in aerobic conditions. After this process waste meets standards for landfilling. However, as during aerobic stabilization humification of organic matter proceed, before landfilling humic substances (HS) could be recovered. High HS concentration in ORF means that before its landfilling HS can be recovered. The maximal recovering of valuable substances from waste is in line with the principles of sustainable development. Therefore, this study examined the humification of ORF from a full-scale mechanical-heat-treatment plant during composting in two-stage system (1st stage in 550 L reactor, 2nd stage in windrow). The rates of organics mineralization were 8.35–12.00 g OM/kg d.m. d. The rates of HS formation were lower, 3.31–3.92 mg/g OM d, and process proceeded most intensively up to 50 days. The maximum HS concentrations were 82–120 mg/g OM, similar to those in composts from different kinds of organic waste.Graphic

The pattern of change in the fertility of podzolic soils in the early stages of natural reforestation

The study identified the patterns of change in podzolic soils forming over different parent rocks at early stages of reforestation upon clear-cutting of pine stands. Soils of the first chronosequence, representing Albic Podzol, demonstrated an illuvial distribution of organic matter down the soil profile, with its maximum deposition in the forest litter. As more time passed since logging, mineral horizons gradually got enriched in organic matter, and a thin organo-mineral horizon with elevated carbon and nitrogen content formed under the forest litter by the age of 8 years. The second chronosequence, representing Entic Podzol, displayed a slight reduction in soil richness upon logging, due to intensive humification and mineralization of organic matter. The study found proof that logging using multifunctional machines helps preserve the living ground cover and the top organic horizons in a substantial part of the logging site. Natural reforestation in sites with soils relatively rich in organic matter proceeded through settlement of deciduous species, whereas sites on poor soils were naturally reforested by pine.

Interpretation of paleodepositional environment using biomarkers and carbon isotope (δ13C) in Talang Akar Formation, South Sumatra Basin, Indonesia

Talang Akar Formation is a proven hydrocarbon source rock in South Sumatra basin. The formation contains dominant shale at the top, with some sandstone interbeds. This study uses 3 crude oil sample and 10 well-cutting obtained from two well (SMT-1 & SMT-2) in Prabumulih oil field. We used biomarkers and carbon isotopes (δ13C) data to determine the paleodepositional environment of Talang Akar Formation. The biomarkers data were obtained from gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS) analysis of normal alkanes, isoprenoids, triterpene, and steranes. Carbon isotopes (δ13C) include saturated and aromatic fractions. The pristine (Pr) to phytane (Ph) ratio is a good indicator of the depositional environment. Higher values of Pr/Ph ratio i.e. ≥3.0 indicate oxidizing conditions i.e. terrestrial while lower values in the range of 1.0-3.0 suggests siliciclastic-dominated marine conditions. However, very low values i.e. ≤ 1.0 indicate reducing conditions or fresh and brackish water conditions. The results in this research show that Pr/Ph ratios range from 7.90-16.66, characteristic of high wax crude oils, primarily originated in fluviatile and deltaic environment containing a significant amount of terrestrial organic matter. Similarly, the resultant ratios of Pr/n-C17 and Ph/n-C18 in SMT-1 and SMT-2 wells range from 0.91-10.72 and 0.11-1.29 respectively, which reflect that most of kerogen was derived from humic source and tend towards an oxidative environment of deposition. Cross-plot of carbon-13 isotopes (δ13C) shows saturated versus aromatic fraction. The resultant plot indicate a deltaic to marginal marine environment for SMT-2 well and a more marine environment for SMT-1 well. The oil/source rock correlation analysis using biomarker data shows that the oils in Prabumulih field is correlated with the oils in source rock of Talang Akar Formation. This study concludes that the source rock contains abundant humic organic matter that was deposited in a transitional (Fluvio-deltaic) to marginal marine environment under oxic conditions.