Accumulation Of Organic Matter Research Articles

Paleosurface studies of the remains of a building in the Mikhailovsky Cordon settlement

Pedoarchaeological study of the remains of a building on the territory of the Old Slavic site (the settlement of Mik-hailovsky Cordon — the Slavic Borshevo Culture of the late 1st mil. AD) in the Voronezh region were carried out in order to obtain new data on the layout of the settlement, the type of housing building, life sustainability, economy, and residen-tial use. The main purpose of soil research was the identification of the nature of the use of the building and the recon-struction of the economic activities in the adjacent territory. The determination of organic and mineral forms of phos-phates, urease activity, and the quantity of microorganisms of various trophic groups in the ‘natopt’ (trampled soil) at the bottom of the pit and in the soil outside of the building was carried out. It has been established that the most pro-nounced traces of economic activity have been preserved in the soils to the west of the building where the summer stove was located. In this area, the content of phosphates reached 2 mg P2O5/g soil. The soil to the northeast of the construction pit is characterized by the accumulation of organic matter, which is confirmed not only by a high content of organic phosphorus, but also by rather high quantity of saprotrophic bacteria, indicating organic contamination of the soil, which suggests the ingress of organic substrates into the soil (manure, feces, household waste). The values of many indicators of anthropogenic activity inside the building turned out to be unexpectedly low. As such, the low content of phosphates, saprotrophic bacteria and keratinophilic fungi in the analysed ‘natopt’ in the building at the bottom of the pit indicate a low intensity, or periodic use of the premises.

Soil microbiota resilience in a two-decade long-term experiment comparing an organic and a conventional cropping system

The effect of conventional and organic management in agriculture impacts not only economic and food quality aspects but potentially all biological components of the environment where these activities occur, including soil microorganisms. While there is generally positive appreciation for organic agriculture's role in organic matter accumulation, its beneficial effects on soil microbiota are a matter of debate, mostly due to the varying conditions in which the comparisons are made. To minimize the impact of distant locations, soils were sampled from nearby fields managed separately with the same rotation schemes for 18 years with conventional low-impact and organic agriculture methods. Samples from six different crops were compared using metabarcoding and metabolomic fingerprinting. The major differences were found between late summer and spring, whereas the variations between the beginning and the end of the spring were neither large nor significant. Some significant differences were found between the microbiota of organic vs. conventional management, particularly between r- and k-strategist microorganisms. While other studies found very little differences between microbiota of differently managed soils after shorter time periods, this work highlights that nearly two decades of separate management are necessary to induce significant variations in the microbiota. This suggests a strong resilience of soil populations and the need for very long-term strategies in agriculture to effect significant changes in soil quality.

Electrodeposition of organic corrosion inhibitor prepared from eucalyptus robusta leaves

Eucalyptus Robusta leaves were used as raw material to develop a steel corrosion inhibitor. A straightforward approach was employed to extract organic molecules from Eucalyptus Robusta leaves, which were applied as a protective coating on steel surfaces to inhibit corrosion. The solution containing the organic inhibitor was electrodeposited onto the surfaces of ASTM A36 steel samples, and an investigation into the parameters of charge (positive or negative), voltage (5 or 20 V), and time (5 and 30 min) was conducted through a 23 factorial experiment. Electrodeposited wet and dry samples had their open circuit voltage (OCP) measured in an acid solution and compared with the OCP of samples in which the inhibitor was deposited by simple immersion (deposited samples) and samples without inhibitor (blank samples). All the samples that had contact with the inhibitor increased their OCP values, showing the effectiveness of the deposition of the inhibitor. Nevertheless, the electrodeposition process carried out for 30 min and with a positive charge (anodic) proved to be the most effective in increasing the OCP value. Optical and scanning electron microscopy analyses revealed that the inhibitor solution effectively formed a thin, uniform, compact film on the metal surface. However, occasional deposition anomalies resulted in the formation of protrusions with organic material accumulation. Electrochemical Impedance Spectroscopy and Tafel curves were used to evaluate the effectiveness of the organic inhibitors. Accelerated corrosion tests in an HCl solution indicated reduced corrosion and the formation of distinct corrosion products for samples with an inhibitor compared to a sample without an inhibitor.

Nickel's behaviour in marine sediments under aerobic to anaerobic diagenetic conditions

In the marine environment, nickel distributions are linked to the biogeochemical cycling of both organic matter and manganese. Thus, Ni and its isotopes have the potential to be used to reconstruct changes of bioproductivity and oxygenation in paleoenvironments. However, their utility relies on an understanding of the behaviour of Ni in modern marine environments. Here we investigate the distribution of Ni under a range of oxidation-reduction conditions, with organic carbon (Corg) burial rates that range from approximately 0.08 to 8.4 mmol m−2 d−1, none of the sites show deep (> 5 cm) penetration of dissolved oxygen into the sediment. We present Ni concentrations for sediments and pore fluids, as well as Ni isotope compositions from pore fluids, from the California and Mexico continental margins. The sites are sufficiently reducing that solid-phase Mn concentrations are typically <1000 ppm, but two of the stations, where oxygenated bottom water bathes the underlying sediment, have near-surface sediment Mn concentrations that reach up to 2.3%.Dissolved Ni is lower in pore fluids for stations with high solid phase Corg compared to those stations with oxygenated bottom water and high solid phase Mn concentrations. The calculated benthic fluxes of Ni at all stations are small relative to their burial rates, which implies a high Ni burial efficiency (> 85%). Pore fluid δ60Ni values range from approximately −0.39 to +2.36 ‰, with the higher δ60Ni values occurring at the Corg-rich station, and the lower values at the Mn-rich stations. At the station with the highest Corg content, the distribution of solid-phase Ni as a function of Corg content is consistent with the strong association of Ni with Corg seen at open-ocean upwelling margins globally. In contrast, the other stations investigated here clearly do not show such an association. Our data offer support for the notion that Ni accumulation within sediments is linked to organic matter accumulation in regions of high photic zone productivity and where the sediments are reducing. However, at the sites in our study where Mn oxidation-reduction reactions occur near the sediment-water boundary, any simple relationship between Ni and Corg burial is obfuscated. With a sufficiently deep oxygen penetration depth and the formation of a solid-phase Mn oxide layer, Ni burial within the sediment can be highly efficient. Importantly, Ni is well preserved in sediments deposited under the full range of conditions studied here. This observation of high Ni preservation is an important constraint if Ni is to be used as a proxy to reconstruct paleoenvironmental conditions.

Soil Carbon and Nitrogen Stocks and Their Influencing Factors in Different-Aged Stands of Sand-Fixing Caragana korshinskii in the Mu Us Desert of Northwest China

Establishing artificial sand-fixing shrubs is a key measure to curb dune flow and drive changes in the soil stocks and cycling of carbon and nitrogen. But our understanding of these dynamics across years of sand-fixing afforestation and the factors influencing them remains inadequate, making it hard to accurately assess its capacity to sequester carbon. To fill that knowledge gap, this study investigated soil organic carbon (SOC) and soil total nitrogen (STN) stocks in Mu Us Desert under artificial sand-fixing shrub stands of different ages (10, 30, 50, and 70 years old) vis-à-vis a mobile sand dune, to determine whether Caragana korshinskii afforestation improved stock characteristics and whether SOC and STN stocks were correlated during the restoration processes. The results showed that the pattern observed is consistent with an increase over time in the stocks of both SOC and STN. At 10, 30, 50, and 70 years, these stocks were found to be 1.8, 2.3, 3.2, and 5.5 times higher for SOC, and 1.3, 1.6, 2.1, and 2.7 times higher for STN, respectively, than those of the control (mobile sand) dune. Stocks of SOC and STN mainly increased significantly in the 0–10 cm soil layer. The SOC stock was correlated positively with the STN stock as well as the C:N ratio. The slope of the regression for the C:N ratio against stand age was positive, increasing slightly faster with afforestation age. Additionally, our findings suggest that during the establishment of artificial stands of shrubs, the size of the STN stock did not expand as fast as the SOC stock, resulting in an asynchronous N supply and demand that likely limits the accumulation of soil organic matter. This research provides important evidence for the sustainable development of desertified ecosystems.

Opaline silica precipitations in the Permian Fengcheng Formation indicate hot spring environments in north Mahu Sag, NW China

The Permian Fengcheng Formation represents a series of deposits formed in an alkaline saline lake, characterized by high proportions of cherts, located in the Northwestern Junggar Basin in China. While discussions on silica-rich hot springs as sources of silica for brine and subsequent chert deposition have been extensively conducted for Quaternary and Mesozoic-Cenozoic alkaline saline lakes worldwide, investigations into Paleozoic alkaline saline lakes are scarce due to challenges associated with identifying evidences of hot spring environments. In this study, we present detailed SEM-EDS analyses and examine silica isotope compositions as well as oxygen isotope compositions to discuss hydrothermal-associated silica precipitation processes. Our findings suggest that migrating silica-rich hot springs along deep-rooted faults released silica into the brine, leading to chert deposition during cooling periods and induction of thermophilic microorganism degradation. Microorganism-associated siliceous precipitates primarily consist of opal-A spheres adhered by extracellular polymeric substances (EPS), while numerous microorganism spheres have undergone silicification. Opal-A spheres within these structures were partially transformed into well-crystallized quartz through multiple stages of dissolution-precipitation processes during prolonged burial history. Furthermore, our results indicate that deep-rooted fault-related hot springs can occur both in marginal and subaqueous areas within alkaline saline lakes, with chert formations observed in shallow-marginal saline lake settings as well as deeper regions. The findings of this study provide valuable insights into the paleoenvironmental conditions, which can be further explored in investigating the accumulation of organic matter in chert-rich successions formed within an alkaline saline lake.

Prediction of net primary productivity in the middle-to-high latitudes of Eurasia based on snow and soil temperature

Net primary productivity (NPP) is the net accumulation of organic matter by vegetation through photosynthesis and serves as a key indicator for exploring vegetation responses to climate change. Considering the remote and local impacts of soil heat capacities on vegetation growth through pathways of atmospheric circulation and land–atmosphere interaction, this paper develops a statistical prediction model for NPP from April to June (AMJ) across the middle-to-high latitudes of Eurasia. The model introduces two physically meaningful predictors: the snow water equivalent (SWE) from February to March (FM) over central Europe and the FM local soil temperature (ST). The positive phase of FM SWE triggers anomalous eastward-propagating Rossby waves, leading to an anomalous low-pressure system and cooling in the middle-to-high latitudes of Eurasia. This effect persists into spring through snow feedback to the atmosphere and affects subsequent NPP changes. The ST is closely related to the AMJ temperature and precipitation. With positive ST anomalies, the AMJ temperature and precipitation exhibit an east–west dipole anomaly distribution in this region. The single-factor prediction scheme using ST as the predictor is much better than using SWE as the predictor. Independent validation results from 2009 to 2014 demonstrate that the ST scheme alone has good predictive performance for the spatial distribution and interannual variability of NPP. The predictive skills of the multi-factor prediction schemes can be improved by about 13 % if the ST predictor is included. The findings confirm that local ST is a predictor that must be included for NPP prediction.摘要净初级生产力 (NPP) 是植被通过光合作用积累机物质的净效益, 是探索植被对气候变化响应的关键指标. 考虑到陆面热力异常通过陆气相互作用和大尺度环流对植被生长的影响, 本文研制了欧亚中高纬地区4–6月NPP预测模型. 该模型引入了两个具有明确物理意义的预测因子: 欧洲中部2–3月的雪水当量 (SWE) 和2–3月局地土壤温度 (ST). SWE的正异常会触发异常东传的Rossby波, 导致下游出现位势高度负异常并引起降温. 通过雪和温度的正反馈, 这种异常低温持续到春季并使得NPP下降. ST与随后季节的温度和降水密切相关, 当ST出现正异常时, 该地区的4–6月温度和降水呈现出东西向偶极子异常分布.对比各方案的预测效果发现, ST比SWE有更好的预测能力. 2009–2014年独立后报结果显示, ST方案对NPP的空间分布和年际变率都有很好的预测效果. 交叉检验的结果显示, 多因子方案中引入ST后能提高模型13 %的预测技巧.

Controlling Factors of Organic Matter Enrichment in Marine–Continental Transitional Shale: A Case Study of the Upper Permian Longtan Formation, Northern Guizhou, China

The marine–continental transitional shale of the Upper Permian Longtan Formation in northern Guizhou is an important source rock in the upper Yangtze region of China, and it holds significant potential for the exploration of shale gas. To investigate the correlation between sedimentary conditions and the accumulation of organic matters in marine–continental transitional shale, this paper performed an extensive analysis using organic geochemical testing, organic petrology examination, a cross-section polisher–scanning electron microscope (CP-SEM), and geochemical analysis. The Jinsha and Dafang drilling cores were selected as the research subjects. The results showed that the TOC of the Longtan Formation in the study area was relatively high, and the TOC content of the tidal flat–lagoon environment (average of 8.37%) was significantly higher than that of the delta samples (average of 2.77%). The high content of Al2O3 (average of 17.41% in DC-1, average of 16.53% in JC-1) indicated strong terrigenous detrital input. The proxies indicated that the Longtan Formation shale in northern Guizhou was deposited in a climate that was both warm and humid, with oxic–dysoxic sedimentary water characterized by high biological productivity and a rapid sedimentation rate. The organic-rich shales during the marine and continental transitional phases were affected by various factors, including the paleo-climate, water redox properties, paleo-productivity, sedimentation rate, and other variables, which directly or indirectly impacted the availability, burial, and preservation of organic matter.

Balanceando el nitrógeno en la portera del predio

Uruguay's dairy can potentially enhance milk productivity competitively, but intensification risks elevating nitrogen (N) surplus, heightening environmental concerns. This study quantified farm-gate N inputs and outputs, calculating N surplus (input-output) and N use efficiency (NUE=output/input) for 17 commercial modal dairy systems identified in the 2014 and 2019 national surveys and 6 prospective intensified systems based on experimental pastoral farmlets achieving near-maximal rainfed productivity. Current dairy systems maintained N surplus at 71 kg N ha-1 between 2014 and 2019 (range: 44-97 kg N ha-1) while improving NUE from 28.3 to 30.5% (range: 20-35%). Intensification increased N surplus without necessarily reducing NUE. Our analyses highlight three aspects: (i) comparatively low N surplus of current Uruguayan dairy, (ii) nonlinear links between N surplus and stocking rate, feed intake, milk productivity and operating profit, and (iii) inequality between dairy systems in their contribution to national dairy N surplus reflects mainly disparity in farm size. These insights underscore the crucial need for understanding the actual fate of N surpluses: nitrate leaching, ammonia volatilisation, N2 denitrification, or N accumulation in soil organic matter. This is an unavoidable requisite for designing management practices and policies able to effectively optimise the economic and environmental sustainability of Uruguayan dairy.

Towards a Greener Future: Scaling Up Agroforestry for Global Sustainability

The current world faces several challenges, including climate change, an exponentially increasing population, the loss of biodiversity and environmental concerns which necessities the adoption of the sustainable nature-based solutions such as agroforestry. Agroforestry is the intricate integration of trees, crops, and livestock on the same piece of land management unit that helps to restore the ecosystem, improve soil health, thus combating the environmental degradation. Moreover, agroforestry has also emerged as a potential tool that bridges the ecological preservation, while increasing or at least maintaining the productivity of the whole agroecosystem. Agroforestry is a contemporary food system that relies primarily on natural inputs, leading to the creation of more sustainable and resilient landscapes. Simultaneously, agroforestry systems reduce the soil erosion, and increases the accumulation of organic matter, hence established a closed nutrient cycling which sustain the agricultural production for longer duration. Simultaneously, agroforestry systems are effective in enhancing food security, diversifying farm income and strengthening the resilience of community to climate change thus empower the farmers and provide an opportunity to combat poverty. However, there are numerous constraints including clear land tenure rights, market infrastructure and linkage, and lack of the traditional knowledge which influenced the adoption of agroforestry systems at global level. This immediately need to be addressed by implementing flexible legislation (such as National Agroforestry Policy 2014 adopted by India), capacity building and community involvement, value chain development and payment for ecosystem services. Overall, it is crucial to adopt low-carbon perennial agroecological practices like agroforestry in order to increase the CO2 abatement rate, improve the food, nutritional and livelihood security of smallholder farmers and contribute to a more environmental friendly and sustainable future.

Late Triassic to Early Jurassic carbon isotope chemostratigraphy and organo-facies evolution in a distal to proximal transect of the North German Basin

AbstractThroughout the Latest Triassic and the Early Jurassic, major changes in paleogeography, climate and eustatic sea-level impacted on the development of shelf depositional environments. Secular trends in environmental conditions were punctuated by transient perturbations that occurred in relation to large-scale volcanic events, such as the emplacement of the Central Atlantic Magmatic Province at the Triassic/Jurassic boundary and the Karoo–Ferrar Large Igneous Province in the early Toarcian. We here present bulk organic (HAWK programmed pyrolysis) and organic carbon isotope (δ13Corg) data for three drill cores recovering Latest Triassic and Early Jurassic strata (Rhaetian to Toarcian). Study sites are located in the northeastern part of the Central European Epicontinental Sea and were positioned along a distal–proximal transect of the North German Basin. This allows discussing the differential response of depositional settings and organo-facies toward secular and transient environmental change. Biostratigraphically anchored trends in δ13Corg values allow the precise correlation along the transect, as well as with distant sites. At all North German locations, diagnostic secular trends in δ13Corg are punctuated by transient negative carbon isotope excursions, reflecting perturbations of the global carbon cycle at the Triassic/Jurassic boundary and in the early Toarcian. Stratigraphic gaps occurred during sea-level lowstands and are most pronounced at shallow proximal sites. Programmed pyrolysis data indicate spatiotemporal organo-facies trends that on a temporal scale occurred in response to sea-level and climate trends, while spatial patterns were governed by basin morphology and paleobathymetry. Substantial marine organic matter accumulations occurred at high sea level during the Toarcian only, and were most continuous at distal sites. Graphical Abstract

The Lithofacies of Sandstones Interbedded with Shales: Implication for Organic Matter Accumulation of Triassic Deep Lacustrine Setting, Southern Ordos Basin

The Lithofacies of Sandstones Interbedded with Shales: Implication for Organic Matter Accumulation of Triassic Deep Lacustrine Setting, Southern Ordos Basin

The relationship between total organic carbon and bottom water redox state in North American black shales

It is clear from modern analogue studies that O2-deficient conditions favor preservation of organic matter (OM) in fine-grained sedimentary rocks (black shales). It is also clear that appreciable productivity and OM flux to the sediment are required to establish and maintain these conditions. However, debates regarding redox controls on OM accumulation in black shales have mainly focused on oxic versus anoxic conditions, and the implications of different anoxic redox states remain unexplored. Here, we present detailed multi-proxy sedimentary geochemical studies of major Paleozoic and Mesozoic North American black shale units to elucidate their depositional redox conditions. This is the first broad-scale study to use a consistent geochemical methodology and to incorporate data from Fe-speciation – presently the only redox proxy able to clearly distinguish anoxic depositional conditions as ferruginous (H2S-limited) or euxinic (H2S-replete, Fe-limited). These data are coupled with total organic carbon (TOC), programmed pyrolysis, and redox-sensitive trace element proxies, with almost all measurements analyzed using the same geochemical methodology. Consistent with expectations based on previous geochemical and paleontological/ichnological studies, these analyses demonstrate that the study units were almost exclusively deposited under anoxic bottom waters. These analyses also demonstrate that there is wide variance in the prevalence of euxinic versus ferruginous conditions, with many North American black shale units deposited under predominantly ferruginous or oscillatory conditions. TOC is significantly higher under euxinic bottom waters in analyses of both preserved (present day) TOC and reconstructed initial TOC values, although sediments deposited under both redox states do have economically viable TOC content. While this correlation does not reveal the mechanism behind higher organic enrichment in euxinic environments, which may be different in different basins, it does open new research avenues regarding resource exploration and the biogeochemistry of ancient reducing environments.

Source rock assessment and organic matter characterization of the Oligocene upper Shahejie and Dongying formations in the Nanpu depression of the saline lacustrine Bohai Bay basin, China: Geochemical, palynological, and mineralogical perspectives

The Bohai Bay Basin, located in eastern China, is a significant petroliferous, non-marine rift basin, underwent intricate tectonic activities throughout the Cenozoic. The Nanpu Depression in the Huanghua sub-basin in the northern part of the basin was controlled by Paleogene rifting and increased subsidence. These geological processes resulted in the deposition of the Shahejie and Dongying formations, which exhibited varying quantities and qualities of organic matter. Eighty drill cuttings samples of the Paleogene First Member (Es1) and the overlying Third (Ed3) and Second (Ed2) members of the Shahejie and Dongying formations, respectively, were investigated. An integrated approach including organic and inorganic geochemistry, palynology, and mineralogy was employed to assess the paleoredox and marine incursion conditions, source rock quality and levels of thermal maturity, and factors that governed organic matter accumulation. Results indicated that the Es1 Member was deposited under anoxic conditions, resulting in the accumulation of organic matter-rich mudstones in the Nanpu Depression. Abundant pollen grains and acritarchs were found in the Es1 Member yielded along with minor occurrences of dinoflagellate cysts, freshwater algae, and spores. Terrestrial palynomorph composition provided evidence of increased terrestrial runoff, while the high abundance of acritarchs, accompanied by some dinoflagellate cysts, confirmed episodes of marine incursion and deposition under hypersaline conditions in the lacustrine Bohai Bay Basin. The Ed2 Member exhibited poor to fair amounts of organic matter and a limited potential of hydrocarbon generation with a variety of kerogen Types, including IV, III, II/III, and II. The Ed3 Member shows fair to good organic matter richness and hydrocarbon potential of kerogen Types III, II/III, and II. The Es1 Member emerged as the most promising source rock within the studied interval, boasting good to excellent organic matter richness, and fair to good hydrocarbon generation potential of kerogen Types III and II/III. Evaluating the thermal maturity of organic matter, based on Tmax and VRo-Eq% and related cross-plots, revealed that the Shahejie and Dongying formations are still in the immature to the early stage of the oil window. The mineralogical composition of the Es1 Member primarily consists of clay and quartz with some carbonate and accessory minerals, such as epigenetic halite, dolomite, and plagioclase. Weak correlations observed between the total organic carbon (TOC) and mineral components indicated that the availability of organic matter was primarily controlled by enhanced production and preservation rather than limited dilution under saline lacustrine, oxygen-deprived, and well-stratified water column conditions. Regional investigations of the Es1 Member confirmed the widespread anoxia and deposition of organic-rich source rocks in the Bohai Bay Basin during the Oligocene.

Organic Matter Accumulation and Hydrology as Drivers of Greenhouse Gas Dynamics in Newly Developed Artificial Channels.

Artificial channels, common features of inland waters, have been suggested as significant contributors to methane (CH4) and carbon dioxide (CO2) dynamics and emissions; however, the magnitude and drivers of their CH4 and CO2 emissions (diffusive and ebullitive) remain unclear. They are characterized by reduced flow compared to the donor river, which results in suspended organic matter (OM) accumulation. We propose that in such systems hydrological controls will be reduced and OM accumulation will control emissions by promoting methane production and outgassing. Here, we monitored summertime CH4 and CO2 concentrations and emissions on six newly constructed river-fed artificial channels, from bare riparian mineral soil to lotic channels, under two distinct flow regimes. Chamber-based fluxes were complemented with hydrology, total fluxes (diffusion + ebullition), and suspended OM accumulation assessments. During the first 6 weeks after the flooding, inflowing riverine water dominated the emissions over in-channel contributions. Afterwards, a substantial accumulation of riverine suspended OM (≥50% of the channel's volume) boosted in-channel methane production and led to widespread ebullition 10× higher than diffusive fluxes, regardless of the flow regime. Our finding suggests ebullition as a dominant pathway in these anthropogenic systems, and thus, their impact on regional methane emissions might have been largely underestimated.

Alkyl Lipid Distributions and Compound‐Specific 14C Isotope Compositions in Diverse Sedimentary Archives in Sub‐Antarctic South Georgia: Deconvolving (Past and Present) Marine and Terrestrial Sources and Revealing Localized Export Dynamics in Response to Environmental Change

AbstractAlkyl lipid distributions in terrestrial, lacustrine and marine sedimentary archives on sub‐Antarctic South Georgia are investigated to identify source endmembers and evaluate their variation in response to Holocene environmental changes. To understand organic matter exchange processes along the land‐ocean continuum, we combine lipid compositional data with compound‐specific 14C data in representative sedimentary records. These data provide additional source information and temporal constraints on exchange processes that operate at the landscape level. The alkane, alkanoic acid and alkanol distributions are distinct between terrestrial and marine sources, between vascular and primarily non‐vascular plants, and according to the level of degradation. Compound‐specific 14C ages of alkanes, alkanoic acids and alkanols reveal the complexity of the carbon pools associated with these carbon sources. We find that terrigenous compounds in lacustrine and marine sediments are generally older than those produced by aquatic sources, reflecting intermediate storage in peat/soil prior to deposition. Nonetheless, the pre‐depositional age of terrigenous alkyl lipids differs in the different settings although they are located in close proximity under the same climatic conditions. Overall, the 14C data reflect changes in the balance of accumulation and erosion of organic matter in the terrestrial catchments of the investigated sites in response to prevailing environmental conditions. Petrogenic OC ranges from 0% to 7% and 4%–37% in catchments with minor glacier presence and to up to 67%–76% in the large tidewater glacier catchment. Long‐term biospheric OC turnover seems to have been remarkably constant throughout most of the Holocene and higher than in analog settings in the northern hemisphere.

Mechanisms of terrestrial organic matter accumulation across the Paleocene-Eocene thermal maximum in the Jianghan Basin, Central China

Marine settings provide major carbon sinks for organic carbon, and act as a key reservoir that can sequester excess carbon during times of high CO2 and global warming. Organic carbon burial in lake sediments also plays an important, but perhaps less appreciated, role in the global carbon cycle. However, the fate of organic carbon burial during times of increasing CO2 and rapid global warming in lacustrine settings is still unclear. This study investigates organic carbon accumulation and its mechanism during the globally significant Paleocene-Eocene Thermal Maximum (PETM, ∼56 Ma) hyperthermal event in the Jianghan Basin, China, based on organic and element geochemistry data. The PETM is identified in our studied rocks based on their broad age constraints and the presence of a 4.3‰ negative excursion in organic carbon isotope. Our study shows that organic carbon accumulation during the PETM in the Jianghan Basin might be mainly controlled by preservation conditions and sediment accumulation rates (SAR), which responded to changing hydrology/climate. A hot and humid climate during the PETM could lead to an increase in terrestrial input and SAR, which might dilute the overall organic matter concentration. Also, enhanced rainfall could contribute to the ventilation of the lake water and expedite the oxidation of organic matter, thus, contributing to relatively low organic matter concentration in the Jianghan Basin. In contrast, an arid and relatively low oxygen environment during the post-PETM interval of our studied section created conditions conducive to the retention of organic matter, resulting in high organic matter content. An examination of other terrestrial PETM records reveals that the poor preservation condition of the organic matter and higher SAR might also have been the primary factors for the low organic matter concentrations in PETM terrestrial sections at other subtropical and mid-latitude locations. Compared to marine settings, terrestrial settings may exhibit lower efficiency in sequestering excess CO2 from the atmosphere through organic carbon burial during the PETM.

Soil organic carbon and nutrient characteristics of Anogeissus groves in old Opara forest reserve, Nigeria.

Forest-savanna transition zones of West Africa are uniquely characterized by forest groves, forest patches, or forest islands, the importance of which for sustainable resource management and their potential for carbon sequestration and nutrient cycling is often underrated. Our study conducted a comparative analysis of the soil organic carbon and nutrient characteristics of the Anogeissus groves in the old Opara forest reserve and their adjoining arable lands. We established 30 sampling frames of 100m × 100m plots with 15 frames per land use type. For each sampling frame, six observation points were randomly selected, and composite soil samples were collected at soil depths of 0-20cm and 20-50cm per observation point. Our results showed Anogeissus groves and their adjoining arable lands to exist on similar landscapes while the groves have enriched soil morphological characteristics (e.g., soil color), higher soil organic carbon (SOC), and better nutrient characteristics. There were strong positive relationships between SOC, effective cation exchange capacity, total nitrogen, calcium, magnesium and calcium, zinc, electrical conductivity, and copper. The significant soil organic matter accumulation in the groves accounts for the overall improved soil characteristics over the adjoining arable lands. Preserving the groves and similar Africanecosystems may be important in climate regulation, resources and biodiversity conservation, and ethnopharmacology for rural communities. Thus, a question arises: should more land be set aside for ecological conservation or for agricultural productivity?

Geochemical Modeling and Hydrocarbon Generation Potentiality of Source Rocks of the Oligocene to Miocene Succession in the Temsah Area, Eastern Nile Delta, Egypt

Geochemical investigation of the Temsah-4 well (T-4) in Temsah gas fields at the eastern offshore Nile Delta differentiate into two categories of OM (organic matter) which are kerogen types II and III within the boreholes penetrated Oligocene-Miocene source rocks. The geochemical and lithological characteristics of the OM-bearing formations in the investigated borehole recognized four thick organic matter-rich intervals (OMRI) in well T-4. The OMRI considers a part of formations that are believed to be considered a real source rock that comprises approximately 66.68% of the Wakar, 65.17% of Sidi-Salem, and 100% of Qantara Fms in the T-4 well. They comprised intervals depths of 3120m-3150m and 3300m-3559.4m belonging to Wakar Fm, from 3580m- 3870m belonging to Sidi-Salem Fm and from 3977m- 4170m belonging to Qantara Fm. The geochemical data reveals that Wakar Fm in the T-4 well considers immature source rock. While mature OMRI within Sidi-Salem and Qantara Fms in the T-4 well represented as effective mature source rocks. Construction of a TOC map in two dimensions throughout the studied areas shows a trend of increasing the quantity of OM eastward during the deposition of Sidi-Salem and Wakar Fms. The improvements of the richness (relatively high TOC) toward the eastward suggested a favorable condition for preservation and accumulation of OM toward the east than the west drilled boreholes. Based on the relative hydrocarbon potential (RHP) the suggested expulsion threshold depths appear to be shallower at 3700m in T-4. Burial history diagrams of studied T-4 wells based on geochemical results postulate that Tineh Fm enters the early mature stage at 2.8Ma. The maturity continues till the recent periods to enter the Qantara and most of Sidi-Salem Fms the same main-oil window at the T-4 area.

Using Beerkan Procedure to Estimate Hydraulic Soil Properties under Long Term Agroecosystems Experiments

The BEST (Beerkan Estimation of Soil Transfer parameters) method was used to compare the hydraulic properties of the soils in two Long-term Agroecosystem Experiments (LTAEs) located at the FIELDLAB experimental site of the University of Perugia (central Italy). The LTAE “NewSmoca” consists of a biennial maize-durum wheat crop rotation under integrated low-input cropping systems with (i) inversion soil tillage (INT) or (ii) no-tillage (INT+) and (iii) under an organic cropping system with inversion soil tillage (ORG). ORG and INT+ involve the use of autumn-sown cover crops (before the maize cycle). Pure stand durum wheat was grown in INT and INT+, while a faba bean–wheat temporary intercropping was implemented in ORG. The LTAE “Crop Rotation” consists of different crop rotations and residue management, a continuous soft winter wheat and biennial rotations of soft winter wheat with maize or faba bean. Each rotation is combined with two modes of crop residue management: removal or burial. For INT+, despite the high-bulk density (&gt;1.50 g/cm3), we found that conductivity, sorptivity and available water are comparable to those of INT, probably due to a more structured and efficient micropore system. ORG soils show the highest conductivity, sorptivity and available water content values, probably due to the recent spring tillage occurring in the wheat inter-row with the faba bean incorporation into the soil. For LTAE Rotation, the residue burial seems to influence the capacity-based indicators positively. However, the differences in the removal treatment are minor, and this could be due to the inversion soil tillage, which limits the progressive accumulation of organic matter.