Carbon Cycle Research Articles

Carbon Sequestration and Landscape Influences in Urban Greenspace Coverage Variability: A High-Resolution Remote Sensing Study in Luohe, China

Urbanization has significantly altered urban landscape patterns, leading to a continuous reduction in the proportion of green spaces. As critical carbon sinks in urban carbon cycles, urban green spaces play an indispensable role in mitigating climate change. This study aims to evaluate the carbon capture and storage potential of urban green spaces in Luohe, China, and identify the landscape factors influencing carbon sequestration. The research combines on-site data collection with high-resolution remote sensing, utilizing the i-Tree Eco model to estimate carbon sequestration rates across areas with varying levels of greenery. The study reveals that the carbon sequestration capacity of urban green spaces in Luohe City is 1.30 t·C·ha−1·yr−1. Among various vegetation indices, the Enhanced Vegetation Index (EVI) explains urban green space carbon sequestration most effectively through an exponential model (R2 = 0.65, AIC = 136.5). At the city-wide scale, areas with higher greening rates, better connectivity, and more complex edge morphology exhibit superior carbon sequestration efficiency. The explanatory power of key landscape indices on carbon sequestration is 78% across the study area, with variations of 71.5%, 62%, and 84.9% for low, medium, and high greening rate areas, respectively. Moreover, when greening rates reach a certain threshold, maintaining and optimizing the quality of existing green spaces becomes more critical than simply expanding the green area. These insights provide valuable guidance for urban planners and policymakers on enhancing the ecological functions of urban green spaces during urban development.

Impact of Agroforestry Practices on Soil Microbial Diversity and Nutrient Cycling in Atlantic Rainforest Cocoa Systems.

Microorganisms are critical indicators of soil quality due to their essential role in maintaining ecosystem services. However, anthropogenic activities can disrupt the vital metabolic functions of these microorganisms. Considering that soil biology is often underestimated and traditional assessment methods do not capture its complexity, molecular methods can be used to assess soil health more effectively. This study aimed to identify the changes in soil microbial diversity and activity under different cocoa agroforestry systems, specially focusing on taxa and functions associated to carbon and nitrogen cycling. Soils from three different cocoa agroforestry systems, including a newly established agroforestry with green fertilization (GF), rubber (Hevea brasiliensis)-cocoa intercropping (RC), and cocoa plantations under Cabruca (cultivated under the shave of native forest) (CAB) were analyzed and compared using metagenomic and metaproteomic approaches. Samples from surrounding native forest and pasture were used in the comparison, representing natural and anthropomorphic ecosystems. Metagenomic analysis revealed a significant increase in Proteobacteria and Basidiomycota and the genes associated with dissimilatory nitrate reduction in the RC and CAB areas. The green fertilization area showed increased nitrogen cycling activity, demonstrating the success of the practice. In addition, metaproteomic analyses detected enzymes such as dehydrogenases in RC and native forest soils, indicating higher metabolic activity in these soils. These findings underscore the importance of soil management strategies to enhance soil productivity, diversity, and overall soil health. Molecular tools are useful to demonstrate how changes in agricultural practices directly influence the microbial community, affecting soil health.

Biogenic silica dynamics in coastal wetland sediments: A key driver of silicon and carbon biogeochemical cycling

AbstractBiogenic silica (biogenic Si) is a bioactive component crucial for the biogeochemical cycling of Si in terrestrial and aquatic ecosystems. Its formation and dissolution dynamics are intricately linked to carbon (C) cycling. However, knowledge about the source, composition, and factors controlling the distribution of biogenic Si in coastal wetland sedimentary environments is still limited. To address this lack of knowledge, we introduced a suite of geometric models for biogenic Si biovolume calculation and investigated biogenic Si assemblages, along with biogenic Si and biogenic Si‐occluded C contents, in sediments from representative coastal wetlands along the west coast of Bohai Bay. Our analysis showed that sedimentary biogenic Si predominantly derived from phytoliths (78.1% ± 5.8%), diatoms (18.2% ± 4.8%), and sponge spicules (3.7% ± 2.9%). Notably, phytolith assemblages were primarily composed of forms derived from the Poaceae family. The biogenic Si‐occluded C content (0.035–1.870 g kg−1) within these wetland sediments was consistent across both sites, accounting for 0.97–5.71% of the total organic C pool. Structural equation modeling indicated that total organic C, pH, and amorphous aluminum oxides either directly or indirectly influenced the biogenic Si content in coastal wetlands sediments. These results demonstrate the critical role that biogenic Si plays in the Si biogeochemical cycle and provide valuable information that advances our understanding of the biogeochemical interactions between Si and C in coastal wetland ecosystems.

Metal–organic framework-based SERS chips enable in situ and sensitive detection of dissolved hydrogen sulfide in natural water: Towards a bring-back-chip mode for field analysis

Hydrogen sulfide (H2S) in natural water plays an important role in carbon and sulfur cycles in biosphere. Current detection protocol is complicated, which need to “bring back water” to lab followed by gas chromatograph analysis. In situ, field detection is still challenging. Herein, a portable, sensitive surface enhanced Raman scattering (SERS) chip was proposed for in situ H2S sampling and SERS signal stabilizing, enabling a “bring back chip” manner for lab analysis. The SERS chip was composed of single core-shell gold nanorod-ZIF-8 framework (Au NR@ZIF-8) nanoparticle. Relying on headspace adsorption, evaporated H2S was enriched in the ZIF-8 shell and then reacted with Au NR, resulting in the weakening of the Au-Br bond Raman peak (175 cm−1) and the appearance of the Au-S bond Raman peak (273 cm−1). The SERS signal reached equilibrium in 10 min. The detection range of H2S was 0.1–2000 μg/L and limit of detection was 0.098 μg/L. SERS signal was not interfered by normal volatile gases. Moreover, SERS signal of a reacted chip was stable at an ambient condition, allowing for in situ sampling and bring-back detection. The applicability of the chip was verified by dynamic H2S monitoring during artificial black-odor water evolution, and in-field quantitative analysis of H2S content in river water and sediment. Finally, the chip was sealed in a waterproof breathable membrane device, which realized the detection of vertical profiles of H2S in the river. This work provided a promising tool for field analysis of H2S in natural environments.

Single-colony MALDI mass spectrometry imaging reveals spatial differences in metabolite abundance between natural and cultured Trichodesmium morphotypes.

Trichodesmium, a globally significant N2-fixing marine cyanobacterium, forms extensive surface blooms in nutrient-poor ocean regions. These blooms consist of a dynamic assemblage of Trichodesmium species that form distinct colony morphotypes and are inhabited by diverse microorganisms. Trichodesmium colony morphotypes vary in ecological niche, nutrient uptake, and organic molecule release, differentially impacting ocean carbon and nitrogen biogeochemical cycles. Here, we assessed the poorly studied spatial abundance of metabolites within and between three morphologically distinct Trichodesmium colonies collected from the Red Sea. We also compared these results with two morphotypes of the cultivable Trichodesmium strain IMS101. Using matrix-assisted laser desorption/ionization (MALDI) mass spectrometry imaging (MSI) coupled with liquid extraction surface analysis (LESA) tandem mass spectrometry (MS2), we identified and localized a wide range of small metabolites associated with single-colony Trichodesmium morphotypes. Our untargeted MALDI-MSI approach revealed 80 unique features (metabolites) shared between Trichodesmium morphotypes. Discrimination analysis showed spatial variations in 57 shared metabolites, accounting for 62% of the observed variation between morphotypes. The greatest variations in metabolite abundance were observed between the cultured morphotypes compared to the natural colony morphotypes, suggesting substantial differences in metabolite production between the cultivable strain IMS101 and the naturally occurring colony morphotypes that the cultivable strain is meant to represent. This study highlights the variations in metabolite abundance between natural and cultured Trichodesmium morphotypes and provides valuable insights into metabolites common to morphologically distinct Trichodesmium colonies, offering a foundation for future targeted metabolomic investigations.IMPORTANCEThis work demonstrates that the application of spatial mass spectrometry imaging at single-colony resolution can successfully resolve metabolite differences between natural and cultured Trichodesmium morphotypes, shedding light on their distinct biochemical profiles. Understanding the morphological differences between Trichodesmium colonies is crucial because they impact nutrient uptake, organic molecule production, and carbon and nitrogen export, and subsequently influence ocean biogeochemical cycles. As such, our study serves as an important initial assessment of metabolite differences between distinct Trichodesmium colony types, identifying features that can serve as ideal candidates for future targeted metabolomic studies.

Long-Term Autotrophic Growth and Solar-to-Chemical Conversion in Shewanella Oneidensis MR-1 through Light-Driven Electron Transfer.

Members of the genus Shewanella are known for their versatile electron accepting routes, which allow them to couple decomposition of organic matter to reduction of various terminal electron acceptors for heterotrophic growth in diverse environments. Here, we report autotrophic growth of Shewanella oneidensis MR-1 with photoelectrons provided by illuminated biogenic CdS nanoparticles. This hybrid system enables photosynthetic oscillatory acetate production from CO2 for over five months, far exceeding other inorganic-biological hybrid system that can only sustain for hours or days. Biochemical, electrochemical and transcriptomic analyses reveal that the efficient electron uptake of S. oneidensis MR-1 from illuminated CdS nanoparticles supplies sufficient energy to stimulate the previously overlooked reductive glycine pathway for CO2 fixation. The continuous solar-to-chemical conversion is achieved by photon induced electric recycling in sulfur species. Overall, our findings demonstrate that this mineral-assisted photosynthesis, as a widely existing and unique model of light energy conversion, could support the sustained photoautotrophic growth of non-photosynthetic microorganisms in nutrient-lean environments and mediate the reversal of coupled carbon and sulfur cycling, consequently resulting in previously unknown environmental effects. In addition, the hybrid system provides a sustainable and flexible platform to develop a variety of solar products for carbon neutrality.

Long‐Term Autotrophic Growth and Solar‐to‐Chemical Conversion in Shewanella Oneidensis MR‐1 through Light‐Driven Electron Transfer

AbstractMembers of the genus Shewanella are known for their versatile electron accepting routes, which allow them to couple decomposition of organic matter to reduction of various terminal electron acceptors for heterotrophic growth in diverse environments. Here, we report autotrophic growth of Shewanella oneidensis MR‐1 with photoelectrons provided by illuminated biogenic CdS nanoparticles. This hybrid system enables photosynthetic oscillatory acetate production from CO2 for over five months, far exceeding other inorganic‐biological hybrid system that can only sustain for hours or days. Biochemical, electrochemical and transcriptomic analyses reveal that the efficient electron uptake of S. oneidensis MR‐1 from illuminated CdS nanoparticles supplies sufficient energy to stimulate the previously overlooked reductive glycine pathway for CO2 fixation. The continuous solar‐to‐chemical conversion is achieved by photon induced electric recycling in sulfur species. Overall, our findings demonstrate that this mineral‐assisted photosynthesis, as a widely existing and unique model of light energy conversion, could support the sustained photoautotrophic growth of non‐photosynthetic microorganisms in nutrient‐lean environments and mediate the reversal of coupled carbon and sulfur cycling, consequently resulting in previously unknown environmental effects. In addition, the hybrid system provides a sustainable and flexible platform to develop a variety of solar products for carbon neutrality.

The decline in tropical land carbon sink drives high atmospheric CO2 growth rate in 2023

Abstract Atmospheric CO2 growth rate (CGR), reflecting the carbon balance between anthropogenic emissions and net uptake from land and ocean, largely determines the magnitude and speed of global warming. CGR at Mauna Loa Baseline Observatory reached record high in 2023. Here we quantified major components of global carbon balance for 2023, by developing a framework which integrated fossil fuel CO2 emissions data, an atmospheric inversion from Global ObservatioN-based system for monitoring Greenhouse GAses (GONGGA) with two artificial intelligence (AI) models derived from dynamic global vegetation models. We attributed the record high CGR increase in 2023 compared to 2022 primarily to the large decline in land carbon sink (1803 ± 197 TgC year−1), with minor contributions from a small reduction in ocean carbon sink (184 TgC year−1) and a slight increase in fossil fuel emissions (24 TgC year−1). At least 78% of the global decline in land carbon sink was contributed by the decline in tropical sink, with GONGGA inversion (1354 TgC year−1) and AI simulations (1578 ± 666 TgC year−1) showing similar declines in the tropics. We further linked this tropical decline to the detrimental impact of El Niño-induced anomalous warming and drying on vegetation productivity in water-limited Sahel and southern Africa. Our successful attribution of CGR increase within the framework combining atmospheric inversion with AI simulations enabled near-real-time tracking of the global carbon budget which had a one-year reporting lag.

Integrating Livestock with Crops and Forestry for Sustainability

Global per capita consumption of animal protein is set to rise, particularly in developing economies, leading to a dramatic increase in meat consumption from 133 million tons in 1980 to 452 million tons by 2050. Notably, 86% of this increase, or 279 million tons, is expected to occur in developing countries. The expansion of animal-based agricultural systems, which cover 45% of the Earth's land area, presents significant challenges. These systems contribute substantially to agricultural emissions, including greenhouse gases such as nitrous oxide (N2O) and methane (CH4), and account for 8% of global water usage. The livestock sector is largely comprised of resource-constrained smallholders in developing nations. Environmental impacts arise from the lack of integration with other agricultural and forestry practices, disrupting the natural cycles of carbon, water, nitrogen, phosphorus, and sulfur. This disruption leads to increased emissions of N2O and CH4, water contamination, land degradation, and biodiversity loss. To address these challenges and support the United Nations' Sustainable Development Goals (SDGs) related to poverty reduction (SDG #1), hunger alleviation (SDG #2), clean water and sanitation (SDG #6), and climate action (SDG #13), it is essential to integrate livestock with crop and tree farming. Strategies to improve sustainability include incorporating pastures into crop rotations, using controlled grazing techniques, practicing agro-forestry such as alley cropping, and implementing systems like ley farming. Additional measures include precision feeding and protein matching to reduce enteric fermentation, repurposing emissions of CH4 and N2O, and effective manure management. Addressing greenhouse gas emissions through diverse approaches, reducing product wastage, minimizing antibiotic use, and restoring rangelands to enhance soil carbon storage are also critical for achieving sustainable livestock practices.

Aboveground Carbon Stock Estimation Based on Backpack LiDAR and UAV Multispectral Imagery at the Forest Sample Plot Scale

Aboveground carbon stocks (AGCs) in forests play an important role in understanding carbon cycle processes. The global forestry sector has been working to find fast and accurate methods to estimate forest AGCs and implement dynamic monitoring. The aim of this study was to explore the effects of backpack LiDAR and UAV multispectral imagery on AGC estimation for two tree species (Larix gmelinii and Betula platyphylla) and to emphasize the accuracy of the models used. We estimated the AGC of Larix gmelinii and B. platyphylla forests using multivariate stepwise linear regression and random forest regression models using backpack LiDAR data and multi-source remote sensing data, respectively, and compared them with measured data. This study revealed that (1) the diameter at breast height (DBH) extracted from backpack LiDAR and vegetation indices (RVI and GNDVI) extracted from UAV multispectral imagery proved to be extremely effective in modeling for estimating AGCs, significantly improving the accuracy of the model. (2) Random forest regression models estimated AGCs with higher precision (Xing’an larch R2 = 0.95, RMSE = 3.99; white birch R2 = 0.96, RMSE = 3.45) than multiple linear regression models (Xing’an larch R2 = 0.92, RMSE = 6.15; white birch R2 = 0.96, RMSE = 3.57). (3) After combining backpack LiDAR and UAV multispectral data, the estimation accuracy of AGCs for both tree species (Xing’an larch R2 = 0.95, white birch R2 = 0.96) improved by 2% compared to using backpack LiDAR alone (Xing’an larch R2 = 0.93, white birch R2 = 0.94).

Remarkable Enhancement of Bismuth Nanosphere Catalyst Activity for the Conversion of Electrocatalytic CO2 to Formate by Bromine Doping.

Driven by renewable energy, using electrocatalysis to reduce carbon dioxide (CO2) to chemicals is a key technology. It could dim global carbon emissions and promote the carbon cycle. Here, we reported an approach to prepare a Br-doped Bi nanosphere (Br-doped Bi NSP) catalyst for the preparation of formate by electrochemical conversion of CO2. The synthesized Br-doped Bi NSP catalyst manifests high selectivity toward HCOOH. At the applied potential of -0.9 V versus reversible hydrogen electrode, it could achieve a maximum FEHCOOH of 98%. It can remain constant, and the degradation is negligible in continuous electrolysis for 9 h. The excellent CO2 reduction performance is due to the electron richness at the surface of Br-doped Bi NSP induced by the electron transfer between Bi and Br. Density functional theory calculations and in situ attenuated total reflectance-Fourier transform infrared measurements were used to predict the underlying catalyst action's pathway. It can be concluded that the introduction of Br is advantageous to the *OCHO formation, which is conducive to the reduction of the determination step. This research could provide a meaningful view into anion-doping effects to enable effiective electrocatalytic material that selectively reduces carbon dioxide into valuable products.

Cultivation of Aurantiochytrium sp. Using Pickle Seasoning Liquid Waste and Application of the Raw Biomass for Fish Aquaculture

AbstractAurantiochytrium sp. strain L3W is a heterotrophic microorganism that produces docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), which are essential for the growth of marine fish. In this study, pickle seasoning liquid waste was used for culturing strain L3W and the raw biomass of strain L3W was then fed to red sea bream fingerlings (Pagus major) to confirm its usability as a source of DHA and EPA. The strain L3W was cultured on the three pickle seasoning liquid waste samples, Akimurasaki, Hiroshimana, Shisohijiki, diluted with sand-filtered seawater at initial pH values of 4 and 7 under unsterile conditions. The growth of strain L3W was highest at 3.71 g/L on Hiroshimana at an initial pH of 7 with DHA and EPA production at 71.4 and 6.8 mg/g-biomass, respectively. Preparing the raw biomass of strain L3W by the 200 L-scale cultivation using the American Type Culture Collection 790By+ medium because of the DHA and EPA contents close to that produced in the Hiroshimana medium with an initial pH of 7, the raw biomass was spiked to the diet at 3%, 5%, and 10%. The final DHA and EPA contents in the whole body were increased by 4.26 and 3.03 times, respectively, by adding the strain L3W biomass at 10%. These results confirmed the feasibility of a carbon cycling scenario in which the strain L3W is cultivated using liquid food waste with the resultant biomass is utilized as a source of DHA and EPA for fish aquaculture. Graphical Abstract

Zinc isotope perspective on global carbon cycling during the onset of the late Paleozoic icehouse

The onset of the late Paleozoic icehouse coincided with a large global carbon-cycle perturbation (represented by the mid-Tournaisian carbon isotope excursion [TICE]), although the underlying cause of this isotopic event remains uncertain. Zinc (Zn), an essential micronutrient for plankton, has an isotopic composition (δ66Zn) in seawater that is sensitive to subtle fluctuations in marine carbon (C) cycling. Here, we investigated C cycling during the TICE using paired carbonate δ66Zn-δ13C and organic δ13C records from two widely spaced sections in South China. These records reveal coupling between δ66Zn and δ13C over an ∼4 m.y. interval in the form of two positive excursions (Peaks I and II) separated by a negative shift (interpeak). Peak I is attributed to enhanced marine primary productivity (MPP), which was stimulated by increased micronutrient supply linked to enhanced silicate weathering and/or upwelling. The interpeak may record oxidation of remobilized organic matter from continental shelves exposed by glacio-eustatic sea-level fall, which, in turn, promoted MPP again and resulted in Peak II. Thus, the TICE records complex climate−carbon cycle feedbacks that may have led to large-scale organic carbon burial and driven stepwise cooling, marking the onset of a sustained late Paleozoic icehouse climate.

The Role of Fertilization on Soil Carbon Sequestration in Bibliometric Analysis

The soil carbon pool is the largest and most dynamic carbon reservoir in terrestrial ecosystems. Fertilization, an important component of agricultural management, is a significant factor influencing soil carbon sequestration. This study analyzed literature from the Web of Science from 2008 to 2024 using CiteSpace. The results revealed a steady increase in publications on this topic, with a significant surge in the recent four years. The analysis highlighted key collaborations among countries, institutions, and authors, and identified main journal sources and seminal works in the research on the role of fertilization in soil carbon sequestrations. Keyword analysis indicated that current research hotspots include ‘soil organic carbon dynamics and organic matter decomposition’, ‘microbial community dynamics and carbon cycling’, and ‘agricultural management practices on carbon sequestration’. In the context of climate change, future research is likely to focus on enhancing sustainable agricultural practices, promoting biochar and resource utilization, and utilizing microbial communities to optimize soil carbon sequestration. This study provides a comprehensive overview of the role of fertilization in soil carbon sequestration, providing important insights for improving soil carbon sequestration strategies.

The VII International Field Symposium was held in Yugra “West Siberian peatlands and the carbon cycle: past and present”

The VII International Field Symposium was held in Yugra “West Siberian peatlands and the carbon cycle: past and present”

Eutrophication and Dissolved Organic Matter Exacerbate the Diel Discrepancy of CO2 Emissions in China's Largest Urban Lake.

The large variability in the emissions of carbon dioxide (CO2) from urban lakes remains a challenge for partitioning these sources at meaningful spatial and temporal scales. Dissolved organic matter (DOM) governs the spatial and temporal variations in CO2, yet relationships of the CO2 concentration (cCO2) and emission flux (FCO2) with DOM in urban lakes have rarely been reported. In this study, we monitored levels of cCO2, FCO2, and the composition of DOM over a 24 h period at three sites during the dry and wet seasons in China's largest urban lake, Tangxun Lake. Our study found the ratio of day/night FCO2 (millimoles per square meter per day) decreased from the dry season (0.79; 7.68/9.68) to the wet season (0.25; 6.05/24.16), averaging 0.42 (6.77/15.97), implying that accounting for nighttime CO2 emissions can increase regional estimates by 70%. This study revealed that eutrophication affected diurnal CO2 emissions with greater algal growth enhancing daytime CO2 uptake and subsequently increasing nighttime CO2 emissions via DOM degradation (larger protein-like DOM fraction). We anticipate that the relative magnitude of FCO2 between day and night from lakes is likely to increase due to urbanization and climate change, underscoring the importance of treating urban lakes as a distinct group and integrating DOM dynamics into carbon cycling in future research.

Accurate Estimation of Gross Primary Production of Paddy Rice Cropland with UAV Imagery-Driven Leaf Biochemical Model

Accurate estimation of gross primary production (GPP) of paddy rice fields is essential for understanding cropland carbon cycles, yet remains challenging due to spatial heterogeneity. In this study, we integrated high-resolution unmanned aerial vehicle (UAV) imagery into a leaf biochemical properties-based model for improving GPP estimation. The key parameter, maximum carboxylation rate at the top of the canopy (Vcmax,025), was quantified using various spatial information representation methods, including mean (μref) and standard deviation (σref) of reflectance, gray-level co-occurrence matrix (GLCM)-based features, local binary pattern histogram (LBPH), and convolutional neural networks (CNNs). Our models were evaluated using a two-year eddy covariance (EC) system and UAV measurements. The result shows that incorporating spatial information can vastly improve the accuracy of Vcmax,025 and GPP estimation. CNN methods achieved the best Vcmax,025 estimation, with an R of 0.94, an RMSE of 19.44 μmol m−2 s−1, and an MdAPE of 11%, and further produced highly accurate GPP estimates, with an R of 0.92, an RMSE of 6.5 μmol m−2 s−1, and an MdAPE of 23%. The μref-GLCM texture features and μref-LBPH joint-driven models also gave promising results. However, σref contributed less to Vcmax,025 estimation. The Shapley value analysis revealed that the contribution of input features varied considerably across different models. The CNN model focused on nir and red-edge bands and paid much attention to the subregion with high spatial heterogeneity. The μref-LBPH joint-driven model mainly prioritized reflectance information. The μref-GLCM-based features joint-driven model emphasized the role of GLCM texture indices. As the first study to leverage the spatial information from high-resolution UAV imagery for GPP estimation, our work underscores the critical role of spatial information and provides new insight into monitoring the carbon cycle.

Seasonal variations of microbial communities and viral diversity in fishery-enhanced marine ranching sediments: insights into metabolic potentials and ecological interactions

BackgroundThe ecosystems of marine ranching have enhanced marine biodiversity and ecological balance and have promoted the natural recovery and enhancement of fishery resources. The microbial communities of these ecosystems, including bacteria, fungi, protists, and viruses, are the drivers of biogeochemical cycles. Although seasonal changes in microbial communities are critical for ecosystem functioning, the current understanding of microbial-driven metabolic properties and their viral communities in marine sediments remains limited. Here, we employed amplicon (16S and 18S) and metagenomic approaches aiming to reveal the seasonal patterns of microbial communities, bacterial-eukaryotic interactions, whole metabolic potential, and their coupling mechanisms with carbon (C), nitrogen (N), and sulfur (S) cycling in marine ranching sediments. Additionally, the characterization and diversity of viral communities in different seasons were explored in marine ranching sediments.ResultsThe current study demonstrated that seasonal variations dramatically affected the diversity of microbial communities in marine ranching sediments and the bacterial-eukaryotic interkingdom co-occurrence networks. Metabolic reconstruction of the 113 medium to high-quality metagenome-assembled genomes (MAGs) was conducted, and a total of 8 MAGs involved in key metabolic genes and pathways (methane oxidation - denitrification - S oxidation), suggesting a possible coupling effect between the C, N, and S cycles. In total, 338 viral operational taxonomic units (vOTUs) were identified, all possessing specific ecological characteristics in different seasons and primarily belonging to Caudoviricetes, revealing their widespread distribution and variety in marine sediment ecosystems. In addition, predicted virus-host linkages showed that high host specificity was observed, with few viruses associated with specific hosts.ConclusionsThis finding deepens our knowledge of element cycling and viral diversity in fisheries enrichment ecosystems, providing insights into microbial-virus interactions in marine sediments and their effects on biogeochemical cycling. These findings have potential applications in marine ranching management and ecological conservation.DRyDF7ykR-XALqAtu34uZtVideo

Ca3[C2O5]2[CO3] is a pyrocarbonate which can be formed at p, T-conditions prevalent in the Earth’s transition zone

Understanding the fate of subducted carbonates is a prerequisite for the elucidation of the Earth’s deep carbon cycle. Here we show that the concomitant presence of Ca[CO3] with CO2 in a subducting slab very likely results in the formation of an anhydrous mixed pyrocarbonate, Ca3C2O52CO3\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${{{{\\rm{Ca}}}}}_{3}{\\left[{{{{\\rm{C}}}}}_{2}{{{{\\rm{O}}}}}_{5}\\right]}_{2}\\left[{{{{\\rm{CO}}}}}_{3}\\right]$$\\end{document}, at moderate pressure ( ≈ 20 GPa) and temperature ( ≈ 1500 K) conditions. We show that at these conditions Ca3C2O52CO3\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${{{{\\rm{Ca}}}}}_{3}{\\left[{{{{\\rm{C}}}}}_{2}{{{{\\rm{O}}}}}_{5}\\right]}_{2}\\left[{{{{\\rm{CO}}}}}_{3}\\right]$$\\end{document} can be obtained by reacting Ca[CO3] with CO2 in a laser-heated diamond anvil cell. The crystal structure was obtained from synchrotron-based single crystal X-ray diffraction data. Density Functional Perturbation Theory calculations in combination with experimental Raman spectroscopy results unambiguously confirmed the structural model. The crystal structure of Ca3C2O52CO3\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${{{{\\rm{Ca}}}}}_{3}{\\left[{{{{\\rm{C}}}}}_{2}{{{{\\rm{O}}}}}_{5}\\right]}_{2}\\left[{{{{\\rm{CO}}}}}_{3}\\right]$$\\end{document} is characterized by the presence of CO32−\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\left[{{{{\\rm{CO}}}}}_{3}\\right]}^{2-}$$\\end{document}- and C2O52−\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\left[{{{{\\rm{C}}}}}_{2}{{{{\\rm{O}}}}}_{5}\\right]}^{2-}$$\\end{document}-groups. The results presented here imply that the formation of Ca3C2O52CO3\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${{{{\\rm{Ca}}}}}_{3}{\\left[{{{{\\rm{C}}}}}_{2}{{{{\\rm{O}}}}}_{5}\\right]}_{2}\\left[{{{{\\rm{CO}}}}}_{3}\\right]$$\\end{document} needs to be taken into account when constructing models of the deep carbon cycle of the Earth.

Root-Driven Soil Reduction in Wadden Sea Salt Marshes

The soil redox potential in wetlands such as peatlands or salt marshes exerts a strong control over microbial decomposition processes and consequently soil carbon cycling. Wetland plants can influence redox by supplying both terminal electron acceptors (i.e. oxygen) and electron donors (i.e. organic matter) to the soil system. However, quantitative insight into the importance of plant effects on wetland soil redox and associated plant traits are scarce. In a combined mesocosm and field study we investigated the impact of plants on soil reduction using IRIS (Indicator of Reduction in Soils) sticks. Vegetated plots were compared to non-vegetated plots along an elevational gradient in a salt marsh of the Wadden Sea and along an artificially created gradient in a tidal tank mesocosm experiment. Our findings from the mesocosm experiment demonstrated that vegetation both enhanced and suppressed soil reduction relative to non-vegetated control pots. The direction of the plant effect (i.e., net oxidizing or net reducing) was inversely correlated with background redox conditions. Insights from high-resolution oxygen profiling via planar optode imaging corroborated these findings. In the field study, vegetation consistently reduced the comparatively well-aerated Wadden Sea salt marsh soil. Reduction correlated positively with soil organic matter content and belowground biomass, indicating that greater availability of plant-derived electron donors, in the form of organic matter, increased soil reduction. Challenging the dominant paradigm that wetland plants primarily act as soil oxidizers, our study reveals their potential to exert a net reducing effect. The documented impact of these plant-induced changes in soil redox conditions suggests a previously overlooked role in shaping the stability of soil organic carbon stocks in wetland ecosystems with variable water tables.