Distribution Of Organic Matter Research Articles

Climate-controlled organic matter accumulation as recorded in the Upper Jurassic Argiles de Châtillon Formation, a shallow-marine counterpart of the Kimmeridge Clay Formation

AbstractMudstones from the Argiles de Châtillon Formation exposed in the Boulonnais region of Northern France represent a proximal lateral equivalent of the organic-rich Kimmeridge Clay Formation. The Argiles de Châtillon Formation is composed of two subunits that straddle the Kimmeridgian–Tithonian boundary. Each subunit contains an organic-rich interval. The two conspicuous organic-rich intervals have been linked to either periods of high sea level or greenhouse warming. Here, we use palynology to further understand climate and environmental mechanisms that drove organic matter enrichment. We use bulk organic carbon isotope records (δ13Corg) to correlate the Boulonnais sections with those of the Kimmeridge Clay Formation. The palynological results suggest that the stratigraphically lower organic-rich interval (Kimmeridgian) was deposited under suboxic to anoxic stratified conditions. A large-scale climate shift from cooler/humid to warmer/arid conditions marked the Kimmeridgian–Tithonian boundary, influencing organic matter enrichment in the stratigraphically higher organic-rich interval (Tithonian). In contrast with the lower organic-rich interval, there are no indications of stratified conditions for the higher organic-rich interval. Within this thicker organic-rich interval, cyclic variations in amorphous organic matter distribution, total organic carbon and δ13Corgtrends on a 2 m scale are observed. They co-occur with fluctuations of the palynological assemblages, indicative of more humid versus arid climate conditions, likely alternating on a ∼100 kyr eccentricity timescale. Our results show that under the most humid phases of these overall arid climate conditions, sulfurization of carbohydrates was the dominant control on organic matter preservation. This climate-controlled process that drives organic matter enrichment in the Tithonian can be recognized on a basin-wide scale.

Palynomorph composition and palynofacies analysis of the Cenomanian Bahariya Formation in the north Western Desert of Egypt: Depositional palaeoenvironment and sequence stratigraphic implications

Abstract This study investigates the Bahariya Formation using 39 rock-cutting samples from the Abu Gharadig Basin in the north Western Desert, Egypt. An approach combining palynomorph composition and palynofacies analysis with lithological composition and geophysical gamma ray log values is used to assess biostratigraphic age constraints, prevalent depositional palaeoenvironments, and relative sea level changes. A moderately diverse assemblage comprised mainly of terrestrial palynomorphs versus minor content of marine palynomorphs is identified. Marker spore and pollen taxa are used to name three interval zones of early Cenomanian, and early-middle Cenomanian ages. Quantitative distribution of particulate organic matter using cluster analysis reveals two palynofacies assemblages: an older assemblage dominated by phytoclasts (mainly wood particles); and a younger assemblage characterised by moderate abundances of amorphous organic matter and phytoclasts. Palynofacies analysis suggests deposition of the Bahariya Formation in fluvio-deltaic to inner neritic shelf environments. Based on the pronounced stratigraphic variations in the particulate organic matter composition, including terrestrial:marine palynomorph ratio, lithological and gamma-ray log data, three complete transgressive-regressive sequences and one incomplete sequence and their systems tracts are defined. The transgressive-regressive trends reflect 3rd order sequences. Additionally, successive changes in relative sea level indicate a continuous rise at the topmost part of the succession.

Assessing the sources and dynamics of organic matter in a high human impact bay in the northern Beibu Gulf: Insights from stable isotopes and optical properties

Severe human activities in coastal areas have greatly impacted the sources and biogeochemical behaviors of organic matter (OM), including particulate OM (POM) and dissolved OM (DOM). However, few studies have incorporated the indices of POM and DOM to address this issue. Here, a dataset of the combination of stable isotopes of carbon and nitrogen in POM and the optical properties of DOM was presented in Xi Bay, a semi-enclosed bay with a highly developing industrial port in Beibu Gulf, South China, to reveal the origin, distribution, and fate of OM during the rainy season. In the upper bay, depleted δ13C suggested that particulate organic carbon (POC) mainly originated from terrestrial sources. However, the negative relationship between chromophoric DOM (CDOM) and particulate nitrogen (PN) suggested that bacterial-mediated decomposition of POM may be the primary source of CDOM. The negative correlation between humic-like fluorescent components (C1 and C2) and salinity suggested that those two components were mainly affected by terrestrial input. The significant correlation between the protein-like component (C3) and Chl a suggested that C3 was mainly derived from phytoplankton production in the upper bay. In the lower bay, the increase of δ13C values indicated an increased contribution of marine POC. The high levels of CDOM may be due to the decomposition of marine (fresh) POM. However, the low levels of C1 and C2 might be affected by dilution with seawater, and the increased levels of the protein-like C3 were due to enhanced primary production. In addition, the enhancement of δ15N values in both the upper and lower bays indicated serious nitrogen pollution in the bay. This study highlights that biological production fueled by excess nutrients is the dominant OM dynamic process in the bay with high human impact in Beibu Gulf.

Sources, distribution and decomposition of soil organic matter based on an effective biomarker in the pastoral areas of Zoige Plateau, China

The degradation of organic matter in soils plays an important role in the carbon cycle. Lignin is the main source of soil organics and it can be used to trace the source, distribution and turnover of organic matter. In this study the distribution and degradation of lignin were investigated to identify the source and degradation of soil organic matter during the succession of China's Zoige Plateau. Lignin monomers were determined by gas chromatography-mass spectrometry with alkaline CuO oxidation and the soils' δ13C and δ15N contents were interpreted to explore the turnover rate of lignin and organic matter. The main source of organics was identified as C3 non-woody angiosperm tissues. Lignin in the topsoil (0–30 cm) was derived from litter and roots, and it then migrated vertically to the deep soil (30–80 cm). Correlations of δ13C/δ15N with the soil's elemental composition showed that the organics degraded more quickly in meadow soil than in bog soil. The soil communities in the meadow and bog soils were generally similar, but there were certain differences in the dominant microbial phyla at different depths. The meadow soil's effectiveness as a carbon sink was gradually weakened, while that of the bog soil strengthened with depth. These results provide a scientific basis for accurately assessing the carbon sink capacity of the soils in Zoige Plateau.

Botryoidal quartz as an abiotic signature in Palaeoarchean cherts of the Pilbara Supergroup, Western Australia

Chemically oscillating reactions (COR) are abiotic processes that generate self-repeating circularly concentric morphologies during decarboxylation of organic acids. The geometry and millimetre to centimetre size dimensions of laminated quartz botryoids recorded in the Palaeoarchean Apex and Strelley Pool chert horizons in Western Australia simulate the self-similar fractal patterns arising in vitro from COR using classical and modified reactants of the Belousov-Zhabotinsky (B-Z) reaction. The botryoidal patterns akin to those developed by the COR include circular concentric laminae, open-book features, microbialite- and stromatolite-like laminations, wavy and domal structures, and rosettes. The mineral composition and organic matter (OM) distribution of these objects indicates an origin from the early diagenetic decarboxylation of carboxylic acids. Pore-water alkalinity decrease is likely due to the decomposition of OM, the generation of carbonic acid, and the cessation of chemical wave diffusion. The chemical waves developed from primary circular oxidation spots, under solubility equilibrium with respect to silica could trigger diagenetic precipitation of quartz. The presence of Fe2+-bearing hematite in various botryoidal geometries in the Apex chert is an analogue of ferroin-derived Fe in B-Z solutions, whereas the presence of Fe and Zn sulphides in the Strelley Pool quartz botryoids is akin to sulphur redox intermediates in B-Z experiments. Correlated microscopy and Raman spectral analysis corroborate that the metamorphosed OM associated with these Palaeoarchean botryoids is indigenous and syngenetic with the host chert. OM in botryoidal quartz displays circular concentric laminations as well as gradients of its density. Accordingly, an abiotic model of COR for the diagenetic growth of the studied Apex and Strelley Pool quartz botryoids is proposed. Comparisons with the chemical compositions, geometric morphology and range of size dimensions of self-similar patterns have been the criteria for development of this model expression. The explored ancient botryoids can thus represent abiotic sedimentological signatures of carbon cycling.

Spatial Variability of the Organic Matter in the Soil in Cassava Cultivation Under Differentiated Management

The management of soil organic matter (SOM) is fundamental in agriculture for soil conservation and crop yields. However, in addition the soil being dynamics, it is heterogeneous, therefore, understanding the spatial variability of SOM is essential. The main objective of this study was to evaluate the spatial variability of SOM in a cassava cultivation under different management, seeking to classify its spatial dependence by geostatistics. A filed experiment was conducted out on soil classified as oxisol with four different management systems: irrigation (micro sprinkler, drip and no irrigation), spacing (1.0 × 0.8 m, 1.0 × 1.0 m and 1.0 × 1.5 m), weed control (manual control and no control) and acidity correction (limestone and withouth limestone), totaling 36 experimental plots. To determine the SOM, the wet oxidation method was used, and the semivariograms were generated by the GS+® software. The effect of the different management systems on the spatial variability of the SOM was evaluated at a depth of 0.0-0.2 m. The theoretical semivariogram model that best fitted the study was the Gaussian model, with a well-defined level, also expressing the condition of data stationarity. The spatial dependence was classified as strong and, through the thematic map generated from the kriging, it was possible to observe the variability in the SOM content for different management zones. The use of geostatistics techniques provided important information for understanding the spatial distribution of soil organic matter.

Characterization of the organic matter produced by Atlantic Rainforest plants and its influence in the surface sediments deposited in a protected subtropical Estuarine–Lagoon system

The aim of the present study was to characterize the distribution and sources of terrigenous organic matter (OM) in surface sediments of a subtropical estuarine–lagoon​ system surrounded by the Atlantic Rainforest. n-Alkanes and their isotopic composition were evaluated in 20 surface sediment samples, as well as in leaves from nine representative plant species collected from the Cananéia–Iguape Estuarine–Lagoon​ System (CIELS; Brazil). According to the calculated n-alkanes indices, the analyzed plants could be grouped as monocotyledonous (aquatic productivity index [Paq] > 0.1; carbon preference index [CPI] < 6), dicotyledonous (Paq < 0.1; CPI > 10), mangrove (average chain length [ACL23−33] < 29; ratio of n-C31 over n-C29 concentration [Norm31] < 0.1) and riparian (ACL23−33 > 29; Norm31 > 0.2) vegetation. δ13C n-alkane values were higher (> −26‰) in the C4 aquatic macrophyte analyzed (Spartina alterniflora), with intermediate values (−30 to −27‰) for the pteridophyte (Pteridium aquilinum), and lower values for the C3 species (< −31‰). In sediment, total n-alkanes, total organic carbon, and total nitrogen concentrations ranged from 510 to 10,000 ng g−1 in dry sediment, 0.15 to 6.37% and not detected to 0.74%, respectively, being governed by the mud composition. ACL23−33 and the Norm31 values ranged from 29.0 to 30.4 and 0.39 to 0.57, respectively. Paq and CPI values ranged from 0.06 to 0.25 and 4.2 to 6.6, respectively. These indexes showed that the main terrigenous OM source to CIELS sediment was the riparian vegetation, coming from the rivers that discharge into the system. The n-alkanes δ13C composition, ranging from −36.0 ± 0.0 to −24.8 ± 0.3‰, also showed contributions of macrophytes input to the deposited OM. The influence of mangrove trees is not dominant but increases in the CIELS eastern region, where this kind of vegetation is more developed.

Mechanism of organic matter accumulation in black shale of the Datangpo Formation: Insights from paleo-environmental variation during the Cryogenian non-glaciation

Mechanism of organic matter (OM) accumulation in the Cryogenian Datangpo Formation of the Nanhua Basin is poorly understood, restricting shale-gas exploration in these non-glacial deposits. To understand mechanism of OM accumulation, we carried out high-resolution analyses of geological and geochemical data from shales of the lower three members (I.II.III) of the Datangpo Formation across the basin. The results show that OM distribution in the basin is heterogeneous: (1) stratigraphically, total organic carbon (TOC) concentrations vary from moderate values in Member I, peaks in Member II, to lowest values in Member III; and (2) spatially, TOC concentrations in Member I increase with increasing depositional water depths, whereas they are high and low throughout Member II and Member III across the basin, respectively. The heterogeneity of OM accumulation in shales is interpreted to be controlled by complex paleo-environmental variations in water-mass exchange, paleoclimate, seawater redox state, and hydrothermal activities. Specifically, (1) ferruginous-euxinic conditions, intensive hydrothermal activities, and pronounced water-mass exchange between the basin and the open ocean favored OM accumulation in Member I; (2) expanded euxinic conditions, dramatic chemical weathering, and reduced water-mass exchange resulted in OM enrichment in Member II; and (3) less extensive anoxic conditions, reduced chemical weathering, and stagnant water-mass exchange led to OM depletion in Member III. This integrated conceptual model for OM accumulation in shales of the Datangpo Formation shows the influences of both primary productivity and redox conditions in the Nanhua Basin.

Water Solubility Distribution of Organic Matter Accounts for the Discrepancy in Hygroscopicity among Sub- and Supersaturated Humidity Regimes.

Water uptake properties of organic matter (OM) are critical for aerosol direct and indirect effects. OM contains various chemical species that have a wide range of water solubility. However, the role of water solubility on water uptake by OM has poorly been investigated. We experimentally retrieved water solubility distributions of water-soluble OM (WSOM) from combustion of mosquito coil and tropical peat using the 1-octanol-water partitioning method. In addition, hygroscopic growth and cloud condensation nuclei (CCN) activity of solubility-segregated WSOM were measured. The dominant fraction of WSOM from mosquito coil smoldering was highly soluble (water solubility (S) > 10-2 g cm-3), while that from peat combustion contained ∼40% of less-soluble species (S < 10-3 g cm-3). The difference in water solubility distributions induced changes in the roles of less water-soluble fractions (S < 10-3 g cm-3) on CCN activity. Namely, the less water-soluble fraction from mosquito coil combustion fully dissolved at the point of critical supersaturation, while that for tropical peat smoldering was limited by water solubility. The present result suggests that water solubility distributions of OM, rather than its bulk chemical property, need to be quantified for understanding the water uptake process.

Distribution and Accumulation of Heavy Metals in Marine Sediment from Marudu Bay, Sabah

This study aims to analyse the distribution and factors that control the accumulation of heavy metals in marine sediment from Marudu Bay, Sabah. The sediment samples originated from the various types of rocks, namely ultrabasic rock, basic rock, and chert of ophiolite sequence, and sedimentary rock of the Kudat Formation. A total of 20 sediment core samples were systematically sliced for physico-chemical analysis such as pH value, organic matter (OM), and particle size distribution (PSD). Seven heavy metals are analysed in this research, namely cobalt (Co), chromium (Cr), copper (Cu), manganese (Mn), nickel (Ni), vanadium (V), and zinc (Zn) which is measured using the ICP-OES instrument. Descriptive statistics were used to study the distribution and accumulation of heavy metals from two main stations, namely Sg Karang Station (ST) and Kg Tampakan Station (SK). The results from both stations showed various levels of heavy metal concentration. The average concentration of Mn is between 2.19 mg/kg - 94.77 mg/kg and followed by Cr (0.87 mg/kg - 21.11 mg/kg). For Ni, Zn, Cu, V, and Co, the concentration range were between 0.28 mg/kg - 11.48 mg/kg, 0.94 mg/kg - 6.95 mg/kg, 0.55 mg/kg - 6.01 mg/kg, 0.64 mg/kg - 3.77 mg/kg, and 0.02 mg/kg - 0.85 mg/kg respectively. The result of correlation analysis showed the significant negative relationship between pH with Co, Cr, Ni, Mn, and Zn indicated the increasing concentration in acidic condition. A strong negative correlation between percentage of sand and Co, Cr, Mn, and Ni indicated the decreasing concentration in coarse sediment particle size. However, there was a strong positive correlation between percentage of sand and V due to the association in the carbonate minerals. The Kruskal-Wallis tests showed there were no significant means difference of the percentage of heavy metals based on sample depth and the distance from the shoreline except for V and Mn.

Pore systems and organic petrology of cretaceous Mowry and Niobrara source-rock reservoirs, Powder River Basin, Wyoming, USA

The Powder River Basin (PRB) is a world-class oil province, in large part thanks to contributions from premier source rocks, Cretaceous Mowry and Niobrara shales. Both formations are also unconventional reservoirs. A critical aspect of evaluating production potential and finding sweet spots is the nature of the pore systems in these fine-grained source-rock reservoirs. Variation by stratigraphic interval is important for selecting optimum target zones for horizontal wells. Understanding variation in pore type, size, and connectivity and relationships with mineralogy and fabric help in determining prospectivity in different parts of the basin. Deciphering controls on pore-system development helps predict intervals and locations of optimum reservoir quality.Imaging of Niobrara and Mowry samples from a range of thermal maturities provided observations and data on pore systems, organic matter (OM) types and associations with mineralogy and fabric, wettability, and microporosity associated with both diagenetic and detrital clays. Imaging techniques included scanning electron microscopy, organic petrography and correlative scanning electron microscopy, and mapping of mineralogy through energy dispersive spectroscopy.Mean solid bitumen (BRo) and vitrinite reflectance (VRo) values indicate all samples are in the oil window with values ranging from 0.52 to 1.15%. Organic fluorescence is prominent in amorphous OM, solid bitumen and some vitrinite in the early oil window. The fluorescence is extinguished at higher thermal maturity. Carbonate pellets (in Niobrara) mainly contain migrated solid bitumen and residual live oil and little or no terrigenous OM (vitrinite and inertinite). However, terrigenous OM is common in siliceous/argillaceous laminae in both formations, where it occurs with amorphous OM, some of which has converted in situ to a solid bitumen petroleum residue.One key finding is the widespread presence of migrated OM at very early oil window maturity. Distribution of such OM and associated wettability alteration is fabric-controlled, at all levels of thermal maturity studied. Clay morphology and abundance and supporting rigid mineral grain framework strongly influence pore development, preservation, and connectivity in both formations. Carbonate content is a good proxy for reservoir quality in Niobrara intervals due to association of porous solid bitumen with calcareous fecal pellets. High recrystallized microquartz content is associated with the best reservoir intervals in the Mowry.

Arctic Nearshore Sediment Dynamics—An Example from Herschel Island—Qikiqtaruk, Canada

Increasing arctic coastal erosion rates imply a greater release of sediments and organic matter into the coastal zone. With 213 sediment samples taken around Herschel Island—Qikiqtaruk, Canadian Beaufort Sea, we aimed to gain new insights on sediment dynamics and geochemical properties of a shallow arctic nearshore zone. Spatial characteristics of nearshore sediment texture (moderately to poorly sorted silt) are dictated by hydrodynamic processes, but ice-related processes also play a role. We determined organic matter (OM) distribution and inferred the origin and quality of organic carbon by C/N ratios and stable carbon isotopes δ13C. The carbon content was higher offshore and in sheltered areas (mean: 1.0 wt.%., S.D.: 0.9) and the C/N ratios also showed a similar spatial pattern (mean: 11.1, S.D.: 3.1), while the δ13C (mean: −26.4‰ VPDB, S.D.: 0.4) distribution was more complex. We compared the geochemical parameters of our study with terrestrial and marine samples from other studies using a bootstrap approach. Sediments of the current study contained 6.5 times and 1.8 times less total organic carbon than undisturbed and disturbed terrestrial sediments, respectively. Therefore, degradation of OM and separation of carbon pools take place on land and continue in the nearshore zone, where OM is leached, mineralized, or transported beyond the study area.

Molecular tracers for characterization and distribution of organic matter in a freshwater lake system from the Lesser Himalaya

Molecular tracers for characterization and distribution of organic matter in a freshwater lake system from the Lesser Himalaya

Application of Hyperspectral Technology Combined with Genetic Algorithm to Optimize Convolution Long- and Short-Memory Hybrid Neural Network Model in Soil Moisture and Organic Matter

A method of soil moisture and organic matter content detection based on hyperspectral technology is proposed. A total of 800 different soil samples and hyperspectral data were collected in the laboratory and from the field. A hyperspectral database was established. After wavelet denoising and principal component analysis (PCA) preprocessing, the convolutional neural network (CNN) module was first used to extract the wavelength features of the data. Then, the long- and short-memory neural network (LSTM) module was used to extract the feature bands and nearby hidden state vectors. At the same time, the genetic algorithm (GA) was used to optimize the hyperparametric weight and bias value of the LSTM training network. At the initial stage, the data were normalized, and all features were analyzed by grey correlation degree to extract important features and to reduce the computational complexity of the data. Then, the GA-optimized CNN-LSTM hybrid neural network (GA-CNN-LSTM) algorithm model proposed in this paper was used to predict soil moisture and organic matter. The prediction performance was compared with CNN, support vector regression (SVR), and CNN-LSTM hybrid neural network model without GA optimization. The GA-CNN-LSTM algorithm was superior to other models in all indicators. The highest accuracy rates of 94.5% and 92.9% were obtained for soil moisture and organic matter, respectively. This method can be applied to portable hyperspectrometers and unmanned aerial vehicles to realize large-scale monitoring of moisture and organic matter distribution and to provide a basis for rational irrigation and fertilization in the future.

Nano and sub-nano scale distribution of organic carbon species on soil particles revealed by Cs-STEM EELS

Understanding the heterogeneous distribution of soil organic matter (SOM) on soil particles is essential for predicting the stability of organic carbon (C) in soil, but direct visualization of the microscopic distribution of organic C in soil is still challenging due to the complexity of soil particles. In this study, a paddy soil was fractionated and spherical aberration corrected scanning transmission electron microscopy (Cs-STEM) coupled with electron energy loss spectroscopy (EELS) was employed to analyze the microscopic distribution of organic C species on clay-sized soil particles (<2000 nm) from the different size fractions (800–2000 nm, 100–800 nm and 0–100 nm) at the nano and sub-nano scale. The EELS results demonstrated that the relative abundance of both phenolic and aliphatic C was quite independent of the particle size fractions, while aromatic and carboxyl carbon demonstrated the largest variations between fractions. With the decrease in soil particle size from 800 to 2000 nm to 0–100 nm, the median abundance of carboxyl (oxidized) C increased from 23% to 35%, and aromatic (reduced) C decreased accordingly from 40% to 16%. The statistical analysis demonstrated that the local organic C concentration was the major factor accounting for the variations in oxidized and reduced C species in soil particles, in which selective sorption of the organic C abundant of acidic functional groups by reactive minerals was responsible for the enrichment of oxidized C in small clay size soil particles. Overall, the results of this study contribute to an improved understanding of the chemical diversity of SOM in organo-mineral interfaces and provide insights in the microscopic C stabilization mechanisms in natural soils.

Sequence stratigraphic control on the variations of organic matter in Eocene lacustrine shales within the Dongying Depression, Eastern China

• A third-order sequence is identified in Eocene shales in the Dongying Depression. • The abundance, type and preservation of organic matter (OM) are intimately related to the sequence development. • Sequence development affects OM accumulation, resulting in differential OM distribution within the Eocene sequence stratigraphic framework. Eocene organic-rich shales in the Dongying Depression, Eastern China, are well preserved and ideal for examining stratigraphic controls on the variations of organic matter (OM). This study concerns the Eocene sedimentary succession in the Dongying Depression and recognizes a third-order sequence based on the stacking patterns of lithofacies, mineralogical changes, and geochemical proxies. The total organic carbon content, Rock-Eval parameters S1 and S2 values, and the chloroform bitumen “A” content are low in the lowstand systems tracts, reaching their maxima within the transgressive systems tracts and gradually decreasing within the highstand systems tracts. The paleoclimate index and ratios of quartz/feldspar, Sr/Ca, TiO 2 /Al 2 O 3 , Cr/Al, Ni/V, Th/U, Zn/Al, and Ni/Al indicate that OM accumulation was influenced by primary productivity, sedimentation rate (SR), and redox conditions, which are intimately related to the sequence development under the influence of tectonics, climate, sediment supply, and relative lake-level fluctuations. The OM distribution is related to the sequence stratigraphy in three ways: (1) climate and relative lake-level fluctuations affected the primary productivity and OM production via algae blooms and terrestrial OM input; (2) relative lake-level fluctuations and sediment supply were influenced by tectonics and climate, causing a change in SR and OM deposition; and (3) relative lake-level fluctuations under different climatic conditions affected the development of anoxic bottom-water favoring OM preservation.

Effects of straw mulching combined with nitrogen application on soil organic matter content and atrazine digestion

To explore the response of atrazine (AT) degradation rate, soil organic matter (SOM) distribution and the relationship between them to straw mulching and nitrogen application, field experiments were conducted to study the distribution of SOM content and AT degradation rate under different straw returning modes combined with nitrogen fertilization in 2 years in Hetao Irrigation District. No (N0), low (NL), medium (NM), and high (NH) levels of N fertilization were incorporated into the soil combined with the surface coverage straw (Treatment BN0, BNL, BNM, BNH, respectively) and the deeply buried straw (Treatment SN0, SNL, SNM, SNH, respectively). The traditional cultivation was used as a control treatment (Treatment CK). The results showed that SOM content of Treatment B was accumulated in 0~20 cm soil layer. The largest SOM content of Treatments B in 0~20 cm soil layer was found in BNH treatment, with an average increase of 14.2% and 24.1% significantly when compared with those in CK and SNH (P < 0.05), respectively. The SOM content of Treatments B increased with the increase of nitrogen application and decreased with the deepening of soil depth. The SOM content of Treatment S was accumulated in the soil layer (20~40 cm and 40~60 cm) near the inter-layer. With the increase of nitrogen application and depth of soil layer, the SOM content increased firstly and then decreased. SNM had the largest SOM content in the soil layer of 20~40 cm and 40~60 cm, with an average increase of 82.6% and 67.7% when compared with Treatment CK (P < 0.05). In the soil layer over 60 cm, there was no significant difference in SOM content of different straw returning methods under the same nitrogen level (P > 0.05). Straw returning methods and nitrogen application level significantly affected AT digestion rate and digestion half-life, with significant differences among treatments (P < 0.05). It found that treatment SNM had the highest digestion rate and the shortest half-life of AT. Compared with Treatment CK, the digestion rate of Treatment SNM was increased by 5.3% on average, and the half-life was shortened by 3.9 days on average. Single regression and stepwise regression analysis of the half-life of AT degradation and SOM content in different soil layers (0~20 cm and 20~40 cm) showed that the degradation of AT was greatly affected by SOM content of 20~40 cm soil layer. Based on the comprehensive analysis, the effect of straw deep burial combined with medium nitrogen application rate (Treatment SNM) was best, which could achieve the goal of increasing SOM content and shortening the half-life of AT digestion. The research provided a technical support for straw resource utilization, alleviated AT pollution and improved farmland ecological environment in Hetao Irrigated District.

Organic Matter Distribution and Characteristics among Rock Formations in Malaysia: Implications on Hydrocarbon Generation Potential

Numerous studies have been done to determine the hydrocarbon potential of Malaysia’s formations and basins due to the need to identify more conventional or unconventional hydrocarbon resources. Due to the fact that none of these investigations were carried out with any prior knowledge in the relevant regions with hydrocarbon potential, some of them did not, however, yield the expected results. This study aims to provide researchers with all the necessary information about potential hydrocarbon-producing areas in Malaysia and the various lithologies connected to them by analyzing all earlier studies carried out in Malaysia. This was accomplished by determining patterns in the distribution of organic matter and characteristics of the formations in Malaysia. Total Organic Carbon (TOC), Generic Potential (GP), Vitrinite Reflectance (Ro), and Hydrocarbon Yield (S2) were the most important hydrocarbon generation potential indicators discussed. A heat map was created using a statistical weight ranking with a weight of 45% for the TOC value and 30%, 15%, and 10% for the GP, S2, and Ro values, respectively. According to the data, the Bintulu, Pinangah, Begrih, Liang, and Tanjong formations have the highest potential to generate hydrocarbons in Malaysia, while the Kroh, Setap, Kalabakan, Temburong, and Belaga have the least potential. Majority of formations with high hydrocarbon potential are tertiary in age and consist primarily of coal and carbonaceous shale formations. The most promising formations are mostly immature, with type II or type III kerogen quality. It is recommended that critical exploration activities be focused on the tertiary-aged formations, particularly those in East Malaysia, in order to increase Malaysia’s hydrocarbon production.

Trends in organic matter deposition in the Cretaceous of the eastern Mediterranean: Revisiting and updating the chronology and facies of the Eratosthenes Seamount deposits

In this study we revisited the Cretaceous of the Eratosthenes Seamount (ESM) from IODP LEG 160 Hole 967E, updating the chronology, depositional environment, and paleobathymetry of the ESM. Our goal was also to address the spatio-temporal distribution of organic matter and, by comparison with the eastern margins of the Levant Basin, discuss basin-wide controls on its deposition and preservation.The investigated core has a relatively continuous Cretaceous succession from the Aptian to the Danian. By identifying the Pα Zone we conclude that the base of the Paleocene is included in the 967E section. A total of 17 ages were identified, with low sedimentation rates of 0.04–2.37 cm/kyr. Petrographic analysis revealed pronounced differences, from micritic pellets, benthic foraminifera, algae, and mollusks in the bottom part of the core, to deep water facies in the uppermost Cretaceous. Paleobathymetry ranged between 0.5 and 5 m in the Aptian to 300–600 m in the Maastrichtian.Both high productivity and OMZ conditions prevailed during the Cenomanian–Turonian, as well as elsewhere in the eastern Mediterranean. While the low core recovery might affect reliable interpretation, we present two alternative explanations for the high vs. low organic content of the Campanian–Maastrichtian in the eastern Levant Basin vs. the ESM: (1) Location relative to upwelling cells; (2) Relative bathymetry, with the ESM representing a paleohigh for much of the Cretaceous, similar to the organic-poor anticline deposits in the eastern Levant, where the massive intervals of organic-rich carbonates accumulated only in the synclines of the Syrian Arc deformational belt.

Calibrated petrophysical model for elevated organic matter intervals and mineralogical variability in the Agrio Formation, Neuquén Basin, Argentina

Organic carbon-bearing mudstone units of variable lithologies exhibit complex internal heterogeneities in total organic carbon (TOC) enrichment and mineralogy related to stratigraphic and geographic variability. Elevated organic matter-bearing intervals within unconventional reservoirs are commonly contained within these thick (100's of meters), low TOC mudstone units, but poorly delineated. The Cretaceous Agrio Formation is a mixed siliciclastic-carbonate mudstone, known source rock unit, and an emerging unconventional play in the hydrocarbon-rich Neuquén Basin of Argentina with internal and geographic heterogeneity. Source rock intervals within the formation have been identified from a detailed outcrop study; however, the variability of hydrocarbon source rock quality and mineralogy of the unconventional reservoir target intervals in the subsurface is relatively unconstrained. A published petrophysical model for a bimodal clay-silica system was modified to predict intervals of elevated organic matter and ternary clay-silica-carbonate mineralogical compositional trends for distinguishing mudstone complexity in the Agrio Formation. This study uniquely distinguishes carbonate-rich from silica-rich mudstone log response across the paleodepositional profile of the system. The calibrated petrophysical model utilized cuttings programmed pyrolysis and mineralogical XRD data applied to wireline well logs from the southern Mendoza and central Neuquén provinces. Predicted logs were used to correlate elevated organic matter distribution, mineralogical composition, and assess stratigraphic and geographic heterogeneity. Thirteen log-derived elevated organic matter-bearing intervals (wireline TOC >1.25 wt%) were identified using the modified petrophysical model, expanding on the previously interpreted five outcrop source intervals in the Agrio Formation. Organic richness thickness and abundance increases in the northern Neuquén to southern Mendoza province within the study area. The new petrophysical workflow can be applied to improve unconventional target decisions for hydrocarbon exploration efficiency in mudstones worldwide.