Carbonate Buildups Research Articles

Exploring Dry Reforming of CH4 to Syngas Using High Entropy Materials: A Novel Emerging Approach

The high global warming potential of natural gas methane necessitates its conversion to valuable products, typically achieved through syngas production, with dry reforming of methane and integrating carbon capture followed by dry reforming of methane standing out among different technologies for methane valorization. However, persistent challenges such as the reverse water gas shift reaction, coke formation, and sintering associated with methane dry reforming have redirected scientific focus toward multi‐metallic catalysts with supports or promoters. High entropy materials have gained attention as promising catalysts because their flexible composition allows fine‐tuning of lattice oxygen reactivity and catalytic activity. Entropy plays a key role in catalysis, and recent research focuses on the enthalpy‐entropy relationship that influences reaction pathways. Alongside entropy, core effects like lattice distortion, sluggish diffusion, and cocktail effects improve catalytic performance by synergistic effects, prevent carbon buildup, and maintain stability at high temperatures, enabling efficient methane conversion. These advancements in high entropy materials drive interest in using entropy‐stabilized systems to address the challenges of methane dry reforming. This review summarizes the recent progress in dry reforming of methane and integrating carbon capture followed by dry reforming of methane using high entropy materials.

Effective application of geological process modeling for unravelling carbonate build-up complexity: A case study from the EX-Carbonate build-up in central Luconia Province, Malaysia

In the dynamic field of carbonate reservoir Exploration, the need for specialized models is vital, assisting as a key tool to facilitate interdisciplinary collaboration and enhance strategies for predicting reservoir behavior. This study examines the use of geological process (GPM), a standard tool to simulate forward stratigraphic modelling, particularly focusing on the Central Luconia Province in the South China Sea. Central Luconia Province stands out for its extensive carbonate build-ups and is recognized as a prolific hydrocarbon reservoir. Forward Stratigraphic Modelling (FSM) leads to a paradigmatic change in geological modeling. Unlike geostatistical models controlled by geometrical parameters, FSM relies on mathematical representations of the physical rules determining erosion, transport, and sedimentation in carbonate growth. This tool, supported by various researchers, has proven its ability in quantitative sedimentary system analysis across diverse temporal and spatial scales. This study located in EX Field showcases the ability of stratigraphic forward modeling in replicating sedimentary complexities and resulting stratigraphic architecture of the EX isolated carbonate platform. The methodology links parameters from existing literature with multiscale data. Additionally, carbonate production laws, contingent on water depth, play a pivotal role in the meticulous modeling process. This work illustrates the efficacy of geological process modelling as a transformative approach for unraveling the complexities of carbonate systems, particularly in regions with prolific hydrocarbon reservoirs like Central Luconia. The incorporation of literature-derived parameters and multiscale data serves as evidence of the model's ability to offer nuanced understandings of the dynamic evolution of carbonate platforms, thereby advancing our understanding of reservoir prediction and future management strategies.

Genesis of honeycomb buildups in the Permian Zechstein Group, Southern North Sea

Seismic interpretation has revealed a hitherto unreported honeycomb pattern of carbonate buildups within the Orchard Platform (Southern North Sea). The Z2 Stassfurt Halite Fm. onlaps the southern margin of the Orchard Platform and is also found infilling Z2 intra-platform lagoons to form salt lakes. Post Z2 evaporation, the deeper Z3 water column drowned the Orchard Platform inhibiting the platform recovery attempted by the Z3 Plattendolomit Fm. The palaeobathymetric variability of the drowned Orchard Platform was sufficient to bring parts of the seafloor into the photic zone allowing for the sporadic growth of the Z3 Plattendolomit Fm. However, the palaeobathymetric lows remained beneath the photic zone ensuring an incomplete regeneration of the Orchard Platform with the creation of a high-frequency network of intra-platform lagoons which mimic the polygonal texture of a honeycomb. Whilst previously accepted as collapse structures or karst systems, this study correlates the development of the honeycomb buildups to variations in seafloor palaeobathymetry which in turn mimic the structural lineaments of the Zechstein subcrop. Syn-depositional instability in the Zechstein subcrop caused the topsets of the Z2 salt lakes to become warped. The warped halite provided seed points for Z3 Plattendolomit Fm. growth which allowed for linear ridges of carbonate to traverse the Z2 salt lakes and eventually connect with the honeycomb buildups. Deposition in the Mesozoic lead to loading of the Zechstein. Halite-filled Z3 lagoons accommodated this loading, which caused a pinching effect on the Z3 honeycomb buildups. The sedimentological understanding provided by this study not only de-risks frontier exploration but also provides insight into carbonate growth in restricted platform recovery scenarios.

Changes in microbial physiology and carbon-use efficiency upon improving soil habitat conditions in conservation farming systems

The interplay between soil microbial anabolism and metabolism has recently been postulated as an important lever for carbon sequestration in soils. Theoretical considerations suggest that high microbial growth rates and a high carbon-use efficiency (CUE) are associated with increased soil organic carbon (SOC) build-up in arable soils. Nature-oriented conservation agricultural practices are believed to facilitate this microbial-driven process of SOC accrual; a practical validation of this postulation is however missing. Against this background, we evaluated the effect of agricultural management and site-specific soil chemical and physical properties on microbial physiology (i.e., respiration, bacterial and fungal growth rates, and microbial biomass turnover) and CUE by an on-farm comparison of conventional farming, conservation farming and unmanaged reference soil systems (i.e., adjacent field margins) at twenty-one sites across three soil depths. We show that a change in agricultural management towards soil health regeneration has a significant impact on microbial physiology. Bacterial growth, respiration and microbial biomass turnover increased from conventional farming towards conservation farming systems to reference soils. The opposite trend however was found for fungal growth and microbial CUE, with highest values observed in conventional farming systems. This clearly contradicts the prevailing idea that higher microbial CUE in conservation farming systems may be associated with higher SOC contents. Our results further show that soil physical and chemical parameters such as soil pH, texture and dissolved carbon compounds strongly predict microbial CUE. In line with these results, functional pore domains showed specific optima for microbial growth and CUE. For example, a high share of small pore domains hampered fungal growth and reduced microbial CUE but facilitated microbial biomass turnover at the same time. Thus, we suggest that – superimposed upon agricultural management effects – habitat structural conditions and microbial carbon limitation mainly shape microbial physiology and CUE in arable soil systems.

Novel low-temperature and high-flux hydrogen plasma source for extreme-ultraviolet lithography applications

Inside extreme-ultraviolet (EUV) lithography machines, a hydrogen plasma is generated by ionization of the background gas by EUV photons. This plasma is essential for preventing carbon build-up on the optics, but it might affect functional performance and the lifetime of other elements inside the machine. The interaction of scanner materials and components with hydrogen plasma is investigated in controlled experiments using laboratory (off-line) setups, where the properties of EUV-generated plasmas are mimicked. Here, we present a novel experimental setup at TNO, where a low-temperature hydrogen plasma is generated by means of electron-impact ionization using a high-current, high-pressure electron beam (e-beam) gun. We show that the produced ion flux, peak ion energies, and radical-to-ion ratio are similar to that of the EUV-generated plasma. Since the e-gun has the option of operating the e-gun in the pulsed mode, it is possible to reproduce the time-dependent behavior of the scanner plasma as well. Moreover, as shown by Luo et al. [RSC Adv. 10, 8385 (2020)], electrons that impinge on surfaces mimic EUV photons in the generation of secondary electrons, which often drive radiation-induced processes (e.g., surface oxidation, reduction, and growth of carbon). We conclude that e-beam generated hydrogen plasma is a very promising technology for cost-effective lifetime testing of materials and optics, as compared to setups with EUV sources.

Sedimentary build-ups of pre-salt isolated carbonate platforms and formation of deep-water giant oil fields in Santos Basin, Brazil

In response to the problems of unclear distribution of deep-water pre-salt carbonate reservoirs and formation conditions of large oil fields in the Santos passive continental margin basin, based on comprehensive utilization of geological, seismic, and core data, and reconstruction of Early Cretaceous prototype basin and lithofacies paleogeography, it is proposed for the first time that the construction of pre-salt carbonate build-ups was controlled by two types of isolated platforms: inter-depression fault-uplift and intra-depression fault-high. The inter-depression fault-uplift isolated platforms are distributed on the present-day pre-salt uplifted zones between depressions, and are built on half- and fault-horst blocks that were inherited and developed in the early intra-continental and inter-continental rift stages. The late intra-continental rift coquinas of the ITP Formation and the early inter-continental rift microbial limestones of the BVE Formation are continuously constructed; intra-depression fault-high isolated platforms are distributed in the current pre-salt depression zones, built on the uplifted zones formed by volcanic rock build-ups in the early prototype stage of intra-continental rifts, and only the BVE microbial limestones are developed. Both types of limestones formed into mound-shoal bodies, that have the characteristics of large reservoir thickness and good physical properties. Based on the dissection of large pre-salt oil fields discovered in the Santos Basin, it has been found that both types of platforms could form large-scale combined structural-stratigraphic traps, surrounded by high-quality lacustrine and lagoon source rocks at the periphery, and efficiently sealed by thick high-quality evaporite rocks above, forming the optimal combination of source, reservoir and cap in the form of “lower generation, middle storage, and upper cap”, with a high degree of oil and gas enrichment. It has been found that the large oil fields are all bottom water massive oil fields with a unified pressure system, and they are all filled to the spill-point. The future exploration is recommended to focus on the inter-depression fault-uplift isolated platforms in the western uplift zone and the southern section of eastern uplift zones, as well as intra-depression fault-high isolated platforms in the central depression zone. The result not only provides an important basis for the advanced selection of potential play fairways, bidding of new blocks, and deployment of awarded exploration blocks in the Santos Basin, but also provides a reference for the global selection of deep-water exploration blocks in passive continental margin basins.

Fungal necromass contribution to carbon sequestration in global croplands: A meta-analysis of driving factors and conservation practices

Fungal necromass carbon (FNC) contributes significantly to the build-up of soil organic carbon (SOC) by supplying abundant recalcitrant polymeric melanin present in the fungal cell wall. However, the influence of a wide range of conservation practices and associated factors on FNC accumulation and contribution to SOC in global croplands remains unexplored. Here, a meta-analysis was performed using 873 observations across three continents, together with structural equation modeling, to evaluate conservation practices and factors responsible for the enhancement of FNC and SOC. FNC content (8.39 g kg−1) of North American soils was highest compared to FNC content of Asian and European soils. The structural equation models showed a significant (p < 0.05) positive influence of microbial biomass carbon (MBC), soil pH, and clay contents on the accumulation of FNC. Soil C/N ratio and climate factors, however, had only minor influences on FNC accumulation. Notably, the main driver of FNC was MBC, which is mainly influenced by the soil total N and geographic factors in the study areas. Typical 5 cropland practices had significant effect size (p < 0.05) on FNC, leading to an increase of 12 % to 26 %, and the FNC content was greatest under straw amendment (26 %). Fungal necromass accumulation efficiency ranged from 23 % to 45 % depending on cropland practices: non- and reduced tillage was the most efficient (45 %), followed by crop coverage (32 %), straw amendment (30 %), and manure application (27 %), while N fertilization had the lowest efficiency (23 %). We conclude that FNC contributes to over a quarter of SOC, highlighting its major role in enhancing C sequestration worldwide. Conservation practices, particularly non-tillage or reduced tillage, are important to enhance C sequestration from FNC in croplands.

Microbial Ecology of an Arctic Travertine Geothermal Spring: Implications for Biosignature Preservation and Astrobiology.

Jotun springs in Svalbard, Norway, is a rare warm environment in the Arctic that actively forms travertine. In this study, we assessed the microbial ecology of Jotun's active (aquatic) spring and dry spring transects. We evaluated the microbial preservation potential and mode, as well as the astrobiological relevance of the travertines to marginal carbonates mapped at Jezero Crater on Mars (the Mars 2020 landing site). Our results revealed that microbial communities exhibited spatial dynamics controlled by temperature, fluid availability, and geochemistry. Amorphous carbonates and silica precipitated within biofilm and on the surface of filamentous microorganisms. The water discharged at the source is warm, with near neutral pH, and undersaturated in silica. Hence, silicification possibly occurred through cooling, dehydration, and partially by a microbial presence or activities that promote silica precipitation. CO2 degassing and possible microbial contributions induced calcite precipitation and travertine formation. Jotun revealed that warm systems that are not very productive in carbonate formation may still produce significant carbonate buildups and provide settings favorable for fossilization through silicification and calcification. Our findings suggest that the potential for amorphous silica precipitation may be essential for Jezero Crater's marginal carbonates because it significantly increases the preservation potential of putative martian organisms.

Impact of stress regime change on the permeability of a naturally fractured carbonate buildup (Latemar, the Dolomites, northern Italy)

Abstract. Changing stress regimes control fracture network geometry and influence porosity and permeability in carbonate reservoirs. Using outcrop data analysis and a displacement-based linear elastic finite-element method, we investigate the impact of stress regime change on fracture network permeability. The model is based on fracture networks, specifically fracture substructures. The Latemar, predominantly affected by subsidence deformation and Alpine compression, is taken as an outcrop analogue for an isolated (Mesozoic) carbonate buildup with fracture-dominated permeability. We apply a novel strategy involving two compressive boundary loading conditions constrained by the study area's NW–SE and N–S stress directions. Stress-dependent heterogeneous apertures and effective permeability were computed in the 2D domain by (i) using the local stress state within the fracture substructure and (ii) running a single-phase flow analysis considering the fracture apertures in each fracture substructure. Our results show that the impact of the modelled far-field stresses at (i) subsidence deformation from the NW–SE and (ii) Alpine deformation from N–S increased the overall fracture aperture and permeability. In each case, increasing permeability is associated with open fractures parallel to the orientation of the loading stages and with fracture densities. The anisotropy of permeability is increased by the density and connectedness of the fracture network and affected by shear dilation. The two far-field stresses simultaneously acting within the selected fracture substructure at a different magnitude and orientation do not necessarily cancel each other out in the mechanical deformation modelling. These stresses affect the overall aperture and permeability distributions and the flow patterns. These effects – potentially ignored in simpler stress-dependent permeability – can result in significant inaccuracies in permeability estimation.

Permaculture Management of Arable Soil Increases Soil Microbial Abundance, Nutrients, and Carbon Stocks Compared to Conventional Agriculture

Conventional agricultural practices severely deplete the soil of essential organic matter and nutrients, increasing its vulnerability to disease, drought, and flooding. Permaculture is a form of agroecology adopting a whole ecosystem approach to create a set of principles and design frameworks for enriching soil fertility, but there is little scientific evidence of its efficiency. This study compares two permaculture managed sites with a conventional arable site to investigate the effect of permaculture management on soil fertility. We used phospholipid fatty acid analysis to estimate microbial abundance and diversity and related these to measured soil nutrients and carbon stocks. The potential of permaculture management to mitigate soil greenhouse gas emissions was assessed during a laboratory soil incubation and measurement of greenhouse gases via gas chromatography. Overall, the permaculture managed allotments had three times higher microbial biomass, one and a half times higher nitrogen, and four times higher carbon content than the arable site. Permaculture soils had larger carbon dioxide and nitrous oxide fluxes compared to arable soil, but all sites had a mean negative flux in methane. Permaculture management by use of organic amendments and no-dig practices provides a constant slow release of nutrients and build-up of organic matter and carbon and consequently promotes greater bacterial and fungal biomass within the soil.

Transitional surface Pt carbide formation during carbon nanotube growth

By correlating structural information with catalytic activity, it is possible to determine the active structure of a catalyst. However, this is far from straightforward and the active structure remains debated even in the well-studied reaction of graphitic carbon formation using noble metal catalysts such as platinum (Pt). One major hindrance is that static observations do not provide access to transitional catalyst states. Here we prove the formation of transitional surface Pt carbide several layers deep as well as a Pt-carbon composite phase during the growth process of carbon nanotubes using atomic-resolution gas in situ transmission electron microscopy combined with density functional theory. Knowledge of the active structure of noble metal Pt is of great interest due to its usage in heterogeneous catalysis. Most importantly, it opens up new avenues to suppress catalyst coking. The unwanted build-up of carbon is the major source of catalyst deactivation in important industrial reactions including propane dehydrogenation, with major financial and environmental consequences.

Magmatism along the Nansha Trough on the southern continental margin of the South China Sea: Recent evidence from along-strike seismic profile

The Nansha Trough (NT) is part of the southern continental margin boundary of the South China Sea (SCS). It has undergone complex tectonic superposition and evolutionary processes involving the subduction demise of the Proto-SCS and subsequent spreading of the SCS. This study provides the first systematic identification and analysis of igneous bodies and seamounts along the NT, based on a multi-channel seismic profile (NDL1) recently acquired along it. The seamounts within the trough are of magmatic origin and the carbonate build-ups observed at the summits of some seamounts exhibit a substantial thickness. Igneous bodies within the trough are consistently associated with high P-wave anomalies. Furthermore, at the eastern and western sides, there are distinct gravity-magnetic-anomaly patterns. On the eastern side, Yinqing Seamount, Nanle Hill and volcanic mounds show high gravity and strong negative magnetic anomalies. In contrast, on the western side, Jinghong Seamount, Yangshu Hill and intrusive bodies show less pronounced magnetic anomalies. This difference may be related to differences in magmatic periods. Unlike the extensive post-spreading magmatism in the SCS's northern margin and deep basin, the most widespread magmatic activity in the NT occurred at ca. 16 Ma before decreasing during the Miocene. This decrease may be closely related to subduction cessation in the Proto-SCS and the collision between the Nansha Block and Borneo. The identification and analysis of NT igneous bodies and their evolutionary processes help delineate the southern boundary of magmatism at the SCS margin. They also provide crucial information for constraining the magmatic processes of Proto-SCS subduction termination and SCS spreading evolution.

Living and decaying roots as regulators of soil aggregation and organic matter formation—from the rhizosphere to the detritusphere

In dryland ecosystems, typically characterized by sparse vegetation and nutrient scarcity, pioneer plants exert a critical role in the build-up of soil carbon (C). Continuous root-derived C inputs, including rhizodeposition and structural root litter, create hotspots of increased microbial activity and nutrient availability where biogeochemical processes, such as soil aggregation and the accumulation and stabilization of organic matter (OM), are promoted. Our study aims to disentangle the effects of root C inputs on soil aggregate formation, microbial community structures, and on the fate of OM—both before and after plant death, i.e., during the transition from rhizosphere to detritusphere. This was realized in a two-phase incubation approach, tracing the natural and undisturbed transition from growth to subsequent decomposition of a pioneer plant-root system (Helenium aromaticum) in a semi-arid topsoil and subsoil. We quantified water-stable aggregates, investigated the fate and composition of OM separated into particulate and mineral-associated OM fractions (POM and MAOM), and observed successional changes in the root-associated microbiome. Our results underscore the significance of roots as vectors for macroaggregation within the rhizosphere in both topsoil and subsoil, associated with a particularly strong increase in fungal abundance in the subsoil. In topsoil, we identified root legacy effects in the detritusphere, as root-induced macroaggregation persisted after plant death, a phenomenon not observed in subsoil. These root legacy effects were accompanied by a clear succession towards gram + bacteria, which appeared to outcompete fungi during root decomposition. The increased availability of decaying litter surfaces further facilitated the protection of particulate OM via the occlusion into aggregates. Overall, to gain a holistic understanding of plant-microbe-soil interactions, we emphasize the need for more studies that span over the full temporal dimension from living to dying plants in intact soil systems.

Investigation of the effect of antioxidant on carbon deposition of compression ignition engine for carbon emissions reduction

The study aimed to assess carbon deposition tendencies in mustard biodiesel with varying oxidation levels by examining residual carbon and existent gum content. Gas chromatography–mass spectrometry (GC-MS) and infrared spectrometry were used to analyze the chemical components of residual carbon and existent gum in mustard biodiesel and an antioxidant before and after oxidation. The research investigated carbon deposition on the exhaust valve of a compression ignition engine using mustard biodiesel blended with clove oil as an antioxidant. The engine ran for 100 h on each fuel sample: diesel (D100), biodiesel blended fuel (B30), and clove oil (3000 ppm). After completing 100 h on each sample, engine exhaust was analyzed for carbon deposition using Scanning Electron Microscopy (SEM) and Energy Dispersive Microscopy (EDX).The findings revealed increased carbon deposition when using biodiesel blended fuel compared to diesel fuel. However, the addition of an antioxidant to the biodiesel blend resulted in reduced carbon deposition. This suggests that the use of antioxidants effectively mitigated carbon buildup in the engine’s exhaust when using biodiesel blends. The aim of this study is to enhance engine performance, increase engine life, and reduce pollution in the environment.

Geologically younger ecosystems are more dependent on soil biodiversity for supporting function

Soil biodiversity contains the metabolic toolbox supporting organic matter decomposition and nutrient cycling in the soil. However, as soil develops over millions of years, the buildup of plant cover, soil carbon and microbial biomass may relax the dependence of soil functions on soil biodiversity. To test this hypothesis, we evaluate the within-site soil biodiversity and function relationships across 87 globally distributed ecosystems ranging in soil age from centuries to millennia. We found that within-site soil biodiversity and function relationship is negatively correlated with soil age, suggesting a stronger dependence of ecosystem functioning on soil biodiversity in geologically younger than older ecosystems. We further show that increases in plant cover, soil carbon and microbial biomass as ecosystems develop, particularly in wetter conditions, lessen the critical need of soil biodiversity to sustain function. Our work highlights the importance of soil biodiversity for supporting function in drier and geologically younger ecosystems with low microbial biomass.

Productivity and profitability of rice (Oryza sativa) influenced by customized fertilizers under rice-wheat cropping system

A field experiment was conducted at Agronomy Research Farm, Acharya Narendra Deva University of Agriculture and Technology, Kumarganj, Ayodhya, Uttar Pradesh, on silty loam soil during 2016–17 and 2017–18 to study the productivity and profitability of rice (Oryza sativa L.) influenced by customized fertilizers in rice-wheat cropping system. The experiment comprised of 6 nutrient management practices, viz. T1, control; T2, recommended dose of fertilizer (RDF); T3, Soil test-based recommendation (STR); T4, Indo-Gulf customized fertilizer; T5, TCL customized fertilizer and T6, Farmer’s practice. The experiment was laid out in a randomized block design with 4 replications. Results revealed that soil test-based recommendation showed significantly higher grain yield (4.88 t/ha), straw yield (7.53 t/ha) of rice, maximum number of effective tillers (438.6/m2), higher length of panicle (25.05 cm), maximum number of grains/panicles (135.10) and test weight (23.81g) over farmer’s practice and RDF, while it was at par with TCL customized fertilizer and Indo-Gulf customized fertilizer. The higher buildup of organic soil carbon (0.43%) and available N (174.11 kg/ha), P (18.98 kg/ha), S (14.88 ppm), DTPA-Zn (0.65 ppm) and B (0.55 ppm) in was maintained or slightly increased in soil test-based recommendation and customized fertilizers applied plots. While higher availability of K (259.80 kg/ha) was found in RDF. The higher net returns (32.58 × 103 `/ha) per rupee investment and B:C ratio (0.82) was also recorded in Soil test-based recommendation followed by Indo-Gulf customized fertilizer and TCL customized fertilizer.

Seismic sequence stratigraphy of Late Albian-Early Turonian successions in SW Iran: Implication for reservoir characterizations and potential for improved reservoir quality prediction

The Late Albian-Early Turonian succession on the Arabian Platform stands out as one of the world's richest hydrocarbon provinces. This study delves into the Seismic Sequence Stratigraphy (SSS) of these successions to unravel reservoir characterization and characterized potential hydrocarbon plays. Utilizing data from five exploration wells, including well logs, selected core data, biostratigraphical information, and chemostratigraphy analysis, alongside a comprehensive 3D seismic volume, enabled the identification of four 3rd-order sequences and multiple 4th-order sequences within the studied successions. Sequence-1 (DS-I), dating back to the Late Albian age, features mudstone and bioclast wackestone in an open marine environment. DS-I is a key sequence, notably witnessing the disappearance of siliciclastic input from west to east in the study area. DS-II (Early Cenomanian) and DS-III (Mid-Cenomanian) were deposited on carbonate platforms with grain-supported facies in shoal and lagoonal depositional environments.A distinct regional unconformity at the Turonian base, evident on seismic sections, aligns with depleted δ18O values on the Cenomanian-Turonian Boundary. The maximum flooding surfaces of DS-I and DS-II are characterized by continuous reflectors with negative amplitude. Furthermore, the lateral grading of reservoir facies and their intercalation with non-reservoir facies within 4th-order sequences suggest that reservoir facies heterogeneity is strongly influenced by depositional processes at this scale. Potential reservoirs, particularly in the Highstand System Tract (HST) of each 3rd sequence, are highlighted, with DC-III's HST standing out, hosting patch reef facies resulting from local tectonic activities and carbonate build-up movements.

Crustal carbonate build-up as a driver for Earth’s oxygenation

Oxygenation of Earth’s atmosphere and oceans played a pivotal role in the evolution of the surface environment and life. It is thought that the rise in oxygen over Earth’s history was driven by an increasing availability of the photosynthetic limiting nutrient phosphate combined with declining oxygen-consuming inputs from the mantle and crust. However, it has been difficult to assess whether these processes alone can explain Earth’s oxygenation history. Here we develop a theoretical framework for the long-term global oxygen, phosphorus and carbon cycles, incorporating potential trajectories for the emergence of continents, the degassing of mantle volatiles and the resulting increase in the size of the crustal carbonate reservoir. We find that we can adequately simulate the Earth’s oxygenation trajectory in both the atmosphere and oceans, alongside reasonable reconstructions of planetary temperature, atmospheric carbon dioxide concentration, phosphorus burial records and carbon isotope ratios. Importantly, this is only possible when we include the accumulation of carbonates in the crust, which permits ever-increasing carbon recycling rates through weathering and degassing. This carbonate build-up is a missing factor in models of Earth’s coupled climate, nutrient and oxygen evolution and is important for reconstructing Earth’s history and potential exoplanet biogeochemistry.

Microfacies and palaeoenvironments of late Cisuralian and Guadalupian (Early to Middle Permian) alatoconchid-bearing limestone in Loei fold belt, Indochina Terrane

This study presents the first record of Early Permian alatoconchid bivalves from Thailand, the Erawan section, in the north of Loei fold belt with prolific fusulines in association with gastropods, and brachiopods. Fusuline taxa are dominated by Pseudofusulina sp. with Darvasites sp., Staffella cf. labanalensis, Staffella sp., Nankinella sp., Neofusulinella sp., Schubertella sp., Pamirina darvasica, Pseudoendothyra sp. and others, indicating an Artinskian age. Fusuline wackestone with common, well-preserved smaller foraminifers, Pseudovermiporella sp. and ostracods indicates a restricted lagoon environment with low to moderate water circulation. These fossils, along with well-preserved, articulated alatoconchids in life-position, suggest the autochthonous nature of the deposits in an intertidal environment.In the central part of the fold belt, the Pak Chong section exhibits intervals of alatoconchid biostromes and coquinites. Carbonate build-ups of the alatoconchid biostromes with gregarious bivalves, in life-position embedded in a micritic wackestone matrix, suggest their preferred life habit and environment. The bivalve coquinites containing packed bivalve shells and fragments, however, indicate a high-energy event. This rock fabric along with common fusuline storm sheets suggests occasional storm events in a restricted, with moderate water circulation to open lagoon environment. Fusulines are predominated by staffellids and others including Staffella sphaerica, Staffella sp., Sphaerulina croatica, Pisolina subsphaerica, Nankinella sp., Neoschwagerina simplex, Presumatrina sp., Afghanella sp. and others, indicating a Wordian (Middle Permian) age.In the southern portion of the fold belt along the Thai-Cambodian border, the Khao Taa Ngog section contains limestone with alatoconchid shells with massive rugose corals which formed local carbonate build-ups in high-energy open platform environments. Poorly-sorted bioclasts with common fusuline tests, shell fragments and coated grains suggest an open marine, lagoon, back reef environment. The occurrence of a fusuline assemblage including Neoschwagerina sp., Yabeina sp., Lepidolina sp., Codonofusiella sp., Verbeekina verbeeki and Chusenella sp. indicates the Capitanian (late Middle Permian) age.

Sorghum and cowpea intercropping response to woody residue amendments in Sahelian agro-ecosystems of Burkina Faso

In West African agro-ecosystems, soils are inherently low in soil organic carbon decreasing the capacity of soils to sustain crop productivity. Woody Residues instead of being burnt or exported out of the cropping systems, can be managed to optimize soil organic carbon build-up, nutrient cycling and crop productivity. The aim of this study was to determine the effect of woody residue amendments from Piliostigma reticulatum (D.C.) Hochst associated with sorghum-cowpea intercropping on the soil residual property and crop productivity. The investigation was carried out in two experimental sites in the Sudano-Sahelian (Gampela and Kulungu) area of Burkina Faso (West Africa). The experimental design was organized into four replicates consisting of two treatments of woody residue amendments: amended (WR+) and unamended (WR-) soils. The results for both sites showed an overall significant increase in numbers (+ 35%) and biomass (+ 64%) of cowpea nodules. The root and aerial biomasses at the flowering stage of cowpeas were significantly improved in amended soils (WR+) by 26% and 44%, respectively compared to unamended soils (WR-). In addition, the WR+ treatment increase significantly cowpea and sorghum yields by 41% and 25%, respectively, as well as water use efficiency (+ 40% and + 26%, respectively) compared to the WR- treatment. Moreover, our results exhibited a strong correlation (r = 0,95) between cowpea nodular biomass and sorghum grain yields, reflecting more contribution of cowpea ecosystem services (facilitation and complementarity) for associated sorghum productivity. However, despite favorable soil conditions (soil water and organic carbon content) that occurred by WR input, it was not sufficient to improve soil residual total nitrogen and available phosphorus. The woody residue management associated with cereal-legume intercropping is a promising option to sustain crop productivity in Sahelian agro-ecosystems.