Global Biogeochemical Cycles最新文献

{"title":"Lateral Coastal Blue Carbon Export Fuels a Deep-Ocean Carbon Sink in an Oligotrophic Warm Pool","authors":"Hsueh-Han Hsieh,&nbsp;Yung-Yen Shih,&nbsp;Chun-Hoe Chow,&nbsp;Tzu-Chieh Chung,&nbsp;Syun-Han Wu,&nbsp;Vicente G. Abedneko,&nbsp;Chin-Hsin Liao,&nbsp;Tse-Min Lee,&nbsp;Jingjing Zhang,&nbsp;Jianfang Chen,&nbsp;Laodong Guo,&nbsp;Hernando P. Bacosa,&nbsp;Chin-Chang Hung","doi":"10.1029/2025GB009034","DOIUrl":"https://doi.org/10.1029/2025GB009034","url":null,"abstract":"<p>Coastal blue carbon (CBC) ecosystems export organic matter offshore, but their contribution to deep-ocean carbon sequestration remains insufficiently quantified. We measured depth-resolved particulate organic carbon (POC) fluxes, δ¹³C signatures, and environmental DNA (eDNA) from sediment traps deployed at 150, 500, and 1,000 m in the western North Pacific warm pool. POC fluxes at 1,000 m were two- to four-fold higher than predicted by classical attenuation models, indicating efficient deep-water transfer driven by both vertical export and lateral inputs. eDNA from sinking particles revealed macroalgae, mangrove, and seagrass taxa throughout the mesopelagic and bathypelagic layers, demonstrating long-distance transport of CBC material. δ¹³C values showed predominantly marine-derived POC, but with measurable CBC contributions persisting at depth. These observations identify a previously underappreciated pathway linking coastal vegetation to deep-ocean carbon storage in oligotrophic gyre systems. They also highlight the need for ground-truth biological carbon pump (BCP) measurements, particularly for oceanic island countries with small land areas yet large exclusive economic zones (EEZs), where accurate carbon accounting depends on in situ validation of model-based estimates.</p>","PeriodicalId":12729,"journal":{"name":"Global Biogeochemical Cycles","volume":"40 7","pages":""},"PeriodicalIF":6.9,"publicationDate":"2026-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2025GB009034","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148615882","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Nitrous Oxide Emissions Across Sub-Saharan Africa: Meta-Analysis and Data-Driven Modeling","authors":"P. Agredazywczuk,&nbsp;T. Ouma,&nbsp;M. Barthel,&nbsp;A. Otinga,&nbsp;R. Njoroge,&nbsp;K. Butterbach-Bahl,&nbsp;R. Daelman,&nbsp;J. E. Hickman,&nbsp;W. Ibrahim,&nbsp;M. Laub,&nbsp;S. Leitner,&nbsp;A. Shumba,&nbsp;K. L. Tully,&nbsp;S. Wachiye,&nbsp;J. Zheng,&nbsp;M. Bauters,&nbsp;R. Kiese,&nbsp;R. Cardinael,&nbsp;C. Andres,&nbsp;R. Balokah,&nbsp;K. S. Lourenço,&nbsp;K. L. Ouattara,&nbsp;J. Six,&nbsp;E. Harris","doi":"10.1029/2026GB009141","DOIUrl":"https://doi.org/10.1029/2026GB009141","url":null,"abstract":"&lt;p&gt;Food security and avoiding land use change in Sub-Saharan Africa (SSA) requires increasing agricultural productivity, necessitating greater fertilizer use. This may increase soil nitrous oxide (&lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msub&gt;\u0000 &lt;mi&gt;N&lt;/mi&gt;\u0000 &lt;mn&gt;2&lt;/mn&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${mathrm{N}}_{2}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;O) emissions, a potent greenhouse gas. This study used Machine learning (ML) models to predict &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msub&gt;\u0000 &lt;mi&gt;N&lt;/mi&gt;\u0000 &lt;mn&gt;2&lt;/mn&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${mathrm{N}}_{2}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;O emissions under future climatic and fertilizer scenarios across SSA. Three models were trained (Random Forest (RF), XGBoost (XGB), and feedforward neural networks (FNN)) on existing forest, grassland, and cropland &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msub&gt;\u0000 &lt;mi&gt;N&lt;/mi&gt;\u0000 &lt;mn&gt;2&lt;/mn&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${mathrm{N}}_{2}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;O measurements. The analysis identified the main drivers influencing &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msub&gt;\u0000 &lt;mi&gt;N&lt;/mi&gt;\u0000 &lt;mn&gt;2&lt;/mn&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${mathrm{N}}_{2}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;O emissions: temperature, soil moisture, rainfall, and fertilizer (cropland). SSA &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msub&gt;\u0000 &lt;mi&gt;N&lt;/mi&gt;\u0000 &lt;mn&gt;2&lt;/mn&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${mathrm{N}}_{2}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;O emissions totaled 253–538 Gg N &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msup&gt;\u0000 &lt;mtext&gt;yr&lt;/mtext&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;−&lt;/mo&gt;\u0000 &lt;mn&gt;1&lt;/mn&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/msup&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${text{yr}}^{-1}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; (1 Gg = &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msup&gt;\u0000 &lt;mn&gt;10&lt;/mn&gt;\u0000 &lt;mn&gt;9&lt;/mn&gt;\u0000 &lt;/msup&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${10}","PeriodicalId":12729,"journal":{"name":"Global Biogeochemical Cycles","volume":"40 7","pages":""},"PeriodicalIF":6.9,"publicationDate":"2026-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2026GB009141","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148615606","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Deep Learning Reconstruction of Daily Soil CO2 Efflux Reveals Biogeochemical Insights and Reduces Annual Estimate Uncertainty Despite Limitated Daily Predictability","authors":"Valerie Smykalov,&nbsp;Ben Bond-Lamberty,&nbsp;Rodrigo Vargas,&nbsp;Li Li","doi":"10.1029/2025GB008899","DOIUrl":"https://doi.org/10.1029/2025GB008899","url":null,"abstract":"<p>Soil CO₂ efflux is commonly measured monthly or seasonally, leaving daily dynamics poorly resolved and contributing to global estimation uncertainty. We trained a single Long Short-Term Memory (LSTM) model to predict daily soil CO₂ efflux across 82 globally distributed sites in COSORE, with 0.2%–46.9% daily data coverage from 2003 to 2020. Despite using far fewer sites than are typically used to train a single deep learning model, with observations biased toward temperate mesic sites, the LSTM model performed well at approximately one-third of sites, reconstructed nearly 2 decades of daily efflux, and outperformed commonly used approaches for estimating daily efflux when applied to the same data set. Performance was weakest at pronounced peaks and troughs and at non-temperate sites with &lt;1.5 years of observations and irregular data patterns. Nevertheless, annual efflux from reconstructed daily data had &lt;40% error even at underperforming sites, substantially improving estimates derived from monthly and seasonal sampling (maximum errors of 95% and 136%, respectively). Temperature sensitivity (<i>Q</i>₁₀) estimated from reconstructed daily predictions closely matched estimates from daily observations, whereas <i>Q</i>₁₀ values derived from monthly or seasonal observations deviated substantially, suggesting that coarse temporal sampling may contribute to uncertainty in reported <i>Q</i>₁₀ values. Consistent daily reconstructions further enabled trend analyses for well-performing, predominantly temperate sites and showed increasing soil CO₂ efflux at most sites from 2003 to 2020, with more variable summer trends. Despite limitations, these results demonstrate the potential of LSTM models to reconstruct daily soil CO₂ efflux and reduce estimation uncertainties from sparse observations.</p>","PeriodicalId":12729,"journal":{"name":"Global Biogeochemical Cycles","volume":"40 7","pages":""},"PeriodicalIF":6.9,"publicationDate":"2026-07-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2025GB008899","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148615662","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Global Patterns on Nutrient Release During Leaf Litter Decomposition in Blue Carbon Ecosystems","authors":"Xiaoguang Ouyang,&nbsp;Erik Kristensen,&nbsp;Martin Zimmer,&nbsp;Carol Thornber,&nbsp;Zhifeng Yang,&nbsp;Shing Yip Lee","doi":"10.1029/2025GB009005","DOIUrl":"https://doi.org/10.1029/2025GB009005","url":null,"abstract":"<p>Nutrient release during litter decomposition is the mineralization of organically bound nutrients into inorganic and soluble forms. However, it remains unknown whether warming increases macro-nutrient release during leaf litter decomposition. Through a global meta-analysis, we incorporated the relationships between nutrient release rate constants (<i>k</i>_NP) and leaf litter decomposition rate constants in coastal blue carbon ecosystems (BCE) into numerical models to forecast nutrient release. Average <i>k</i>_NP ranged from 0.006 to 0.035 d⁻¹ for nitrogen and 0.003–0.019 d⁻¹ for phosphorus with lower values in temperate than (sub)tropical zones. Our findings suggest that nutrient release during leaf litter decomposition will increase with rising temperatures under two scenarios: the IPCC representative concentration pathway 8.5 and the IPCC 1.5–4°C warming compared with the pre-industrial period. Leaf litter nutrient release in mangrove forests and tidal marshes is more sensitive to warming than that in seagrass beds. Leaf litter processing and consumption by benthic fauna during decomposition will lead to lower nutrient release in 2100 compared to 2050 due to global warming. We conclude that warming will intensify, while decreased macrobenthos activity will reduce, leaf litter nutrient release.</p>","PeriodicalId":12729,"journal":{"name":"Global Biogeochemical Cycles","volume":"40 7","pages":""},"PeriodicalIF":6.9,"publicationDate":"2026-07-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148615660","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Decadal Shifts Towards Higher Riverine Silicon Relative to Nitrogen and Phosphorus Across High Latitudes","authors":"Joanna C. Carey,&nbsp;Nicholas J. Lyon,&nbsp;Keira Johnson,&nbsp;Pamela L. Sullivan,&nbsp;Sidney A. Bush,&nbsp;Lienne R. Sethna,&nbsp;Ruth Heindel,&nbsp;Pirkko Kortelainen,&nbsp;Hjalmar Laudon,&nbsp;Diane M. McKnight,&nbsp;Amanda Poste,&nbsp;Antti Raike,&nbsp;Kathi Jo Jankowski","doi":"10.1029/2025GB008926","DOIUrl":"https://doi.org/10.1029/2025GB008926","url":null,"abstract":"<p>High-latitude systems are warming faster than the global average, altering the rates of silicon (Si) mobilization from terrestrial to aquatic systems. Dissolved Si (DSi) concentration and its ratio with other nutrients exert strong controls on algae blooms in fresh and marine receiving waters, especially in high-latitude regions where diatoms often dominate riverine and coastal autotroph communities. Here we present an examination of decadal scale changes in river DSi concentrations, loads, and nutrient ratios in 70 high-latitude rivers (&gt;58°) across North America, Europe, Asia, and Antarctica. We examined monthly and annual changes in DSi, dissolved inorganic nitrogen (DIN), and dissolved inorganic phosphorus (DIP) concentrations and yields using sequential breakpoint analysis (i.e., SiZer) that allows for variable trend identification within a single time series. Except for the Antarctic streams, we found a predominant trend of increasing DSi relative to DIN and DIP for both annual concentrations and yields, driven primarily by declines in DIN and DIP rather than increases in DSi. Contrary to expectations, we found little evidence that changes in discharge or shifts in seasonality (i.e., month-specific trends) drove these altered interannual nutrient dynamics. However, interannual changes in DSi concentrations were associated with hydroclimatic variability (precipitation, evapotranspiration, snow cover, air temperature) and DIP availability. Taken together, our analysis identifies large-scale shifts in exports of Si, N, and P in high-latitude rivers, with implications for algae productivity and composition in the highly productive waters of high-latitude ecosystems.</p>","PeriodicalId":12729,"journal":{"name":"Global Biogeochemical Cycles","volume":"40 7","pages":""},"PeriodicalIF":6.9,"publicationDate":"2026-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2025GB008926","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148467665","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Landscape-Scale Regulation of Sediment Nitrogen Cycling and N2O Production in Small Artificial Lakes Across an Urbanization Gradient","authors":"Wei Li,&nbsp;Tingting Liu,&nbsp;Xiaofeng Wang,&nbsp;Zhang Yuewei,&nbsp;Honglin Chen,&nbsp;Xingui Bai,&nbsp;Yuan Zeng,&nbsp;Zuolin Xiao,&nbsp;Yixin He","doi":"10.1029/2026GB009091","DOIUrl":"https://doi.org/10.1029/2026GB009091","url":null,"abstract":"<p>Small artificial lakes are ubiquitous in human-dominated landscapes, yet the responses of their sediment nitrogen (N) cycling and N₂O production to land use change remain poorly constrained. We investigated sediment N pools, microbial biomass, transformation rates (nitrification, denitrification, nitritation, and ammonification) and N₂O production potential across 54 small artificial lakes spanning an urbanization gradient of in Chongqing metropolitan, China. We further explored the effects of landscape composition across multiple spatial scales on N cycling in lake sediments. Results revealed that sediment N transformation rates and N₂O production potential showed a consistent increase from forest to agricultural and urban landscapes. Watershed integrated land-use index within multi-scale buffer zones (50–2,000 m) exhibited significant positive correlations with N transformation rates and N₂O production potential in sediments. This signifies intensified urban landscape substantially accelerate these processes by increasing N substrate abundance and bioavailability, as well as microbial biomass. These landscape controls are particularly scale-dependent, with nearshore land-use patterns within an ∼800 m buffer zone explaining the most spatial variability in N cycling rates and N₂O production. Furthermore, landscape changes alter not only the magnitude but also the structure of sediment N cycling networks, resulting in imbalanced, disproportionately enhanced denitrification and N₂O production potential in urbanized lakes. Our results demonstrate a landscape–sediment–microbe cascade governing N cycling and N₂O generation in small artificial lakes, highlighting their role as heterogeneous biogeochemical reactors. Incorporating scale-dependent landscape controls and sediment processes is essential for improving N cycling modeling and prediction in rapidly urbanizing watersheds.</p>","PeriodicalId":12729,"journal":{"name":"Global Biogeochemical Cycles","volume":"40 7","pages":""},"PeriodicalIF":6.9,"publicationDate":"2026-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148467664","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Additive Dominance and Context-Dependent Nonlinearities in Soil Greenhouse Gas Responses to Concurrent Global Change","authors":"Bangjing Ding,&nbsp;Di Xu,&nbsp;Shuo Wang,&nbsp;Wenzhi Liu","doi":"10.1029/2026GB009164","DOIUrl":"https://doi.org/10.1029/2026GB009164","url":null,"abstract":"<p>Multiple global change factors (GCFs) often co-occur, yet their interactive effects on soil greenhouse gas (GHG) emissions worldwide remain poorly understood. Here, we conducted a global meta-analysis to assess pairwise effects of five GCFs (elevated CO₂, nitrogen addition, warming, increased precipitation, and decreased precipitation) on soil CO₂, CH₄, and N₂O emissions. We found that individual GCFs significantly increased CO₂ and N₂O emissions but had negligible effects on CH₄ emissions. Similarly, pairwise combinations of GCFs enhanced CO₂ and N₂O emissions, whereas CH₄ responses were weak and directionally inconsistent. Across all GCF combinations, additive interactions (69.7%–82.5%) predominated overall, while synergistic and antagonistic interactions were less frequent and context-dependent. Notably, N₂O exhibited the highest proportion of both synergistic (13.1%) and antagonistic (17.2%) effects compared to CO₂ and CH₄, indicating stronger nonlinear responses to concurrent GCFs. Moreover, roughly 50% of the multifactor responses for N₂O emissions in wetlands and croplands were non-additive, underscoring that ecosystem-specific context strongly modulates interaction outcomes. Climatic and ecosystem characteristics, particularly precipitation, modulated interactive effects. These findings highlight that predicting future soil GHG dynamics under concurrent global change requires accounting not only for generally dominant additive effects but also for the context-dependent nonlinear interactions that ultimately constrain Earth system projections.</p>","PeriodicalId":12729,"journal":{"name":"Global Biogeochemical Cycles","volume":"40 7","pages":""},"PeriodicalIF":6.9,"publicationDate":"2026-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148467208","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Inundation and Sediment Supply Predict Annual but Not Centennial Carbon Accumulation in Tidal Wetlands Across Land-Use Types","authors":"Katrina L. Poppe,&nbsp;John M. Rybczyk,&nbsp;Christopher N. Janousek,&nbsp;Scott D. Bridgham,&nbsp;Craig Cornu,&nbsp;Trevor Williams,&nbsp;Heida L. Diefenderfer,&nbsp;Amy B. Borde,&nbsp;Heather Perillat,&nbsp;Laura S. Brophy,&nbsp;Erin K. Peck,&nbsp;Jude Apple,&nbsp;Sara H. Knox","doi":"10.1029/2025GB008832","DOIUrl":"https://doi.org/10.1029/2025GB008832","url":null,"abstract":"<p>Despite growing interest in the contributions of tidal wetlands to natural climate solutions, data remain scarce on how land use affects their carbon accumulation rates (CAR). Additionally, environmental factors driving the large observed variability in CAR among sites are poorly understood. To address these knowledge gaps, we measured short-term (∼1 year) and long-term (∼100 years) CAR using feldspar marker horizons, ²¹⁰Pb profiles, and surface elevation tables from 39 sites in seven estuaries in Oregon and Washington, USA. Sites varied in wetland type (tidal marsh, tidal swamp, nontidal pasture), land-use history (reference, restored, and disturbed), and salinity (fresh to polyhaline). Across both timescales, CAR was lowest in disturbed pastures and highest in restored marshes, reflecting patterns in sediment accretion rates. Short-term CAR exceeded long-term CAR by approximately 50% on average and was only weakly correlated with long-term CAR, with differences among hydrogeomorphic setting. Short-term CAR was well predicted by summer inundation frequency and relative sediment load, together explaining 60% of variance, whereas long-term CAR was poorly predicted by contemporary environmental conditions. These findings highlight the importance of aligning predictor and response timescales when modeling blue carbon dynamics, and reinforce the climate mitigation potential of tidal wetland restoration.</p>","PeriodicalId":12729,"journal":{"name":"Global Biogeochemical Cycles","volume":"40 7","pages":""},"PeriodicalIF":6.9,"publicationDate":"2026-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2025GB008832","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148324918","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Land Carbon Sink Distribution in Northern Eurasia Is Driven by Climate Change","authors":"I. Melnikova,&nbsp;T. Yokohata,&nbsp;D. Schepaschenko,&nbsp;S. Sitch,&nbsp;S. Maksyutov","doi":"10.1029/2025GB008971","DOIUrl":"https://doi.org/10.1029/2025GB008971","url":null,"abstract":"<p>Boreal forests are a major contributor to the global land carbon sink under rising CO₂ concentrations and a changing climate. Carbon sink estimates for Northern Eurasia from forest inventories, flux mapping, and remote sensing have moved toward convergence over the past decade, although substantial differences remain. Several bottom-up and top-down estimates exceed Russia's national greenhouse gas inventory values. Here, we combine data from four independent sources—machine-learning-based FLUXCOM, atmospheric inversion models, the TRENDY ensemble of dynamic global vegetation models, and CMIP6 Earth System Models—to assess the spatial and temporal characteristics of the Northern Eurasian net carbon sink and discuss the differences. Our multi-approach assessment yields a regional estimate of 0.47 ± 0.20 GtC year⁻¹ for the 2001–2015 period, which accounts for one-third of the global land carbon sink. CMIP6 model estimates are broadly consistent with those from other approaches, lending confidence to their future projections, although regional differences persist across individual models. We find a pronounced spatial flux gradient from south to north and west to east along a mean temperature gradient, with stronger carbon sinks in the warmer southern regions and weaker sinks in the cooler northeastern regions. Despite rapid warming in the northern parts of Northern Eurasia, CO₂- and warming-induced carbon sink enhancement contributes little to the overall regional sink due to its initially low net productivity. These results underscore the importance of forest productivity in shaping the terrestrial carbon sink and provide a multi-perspective view of its evolution under continued anthropogenic forcing.</p>","PeriodicalId":12729,"journal":{"name":"Global Biogeochemical Cycles","volume":"40 7","pages":""},"PeriodicalIF":6.9,"publicationDate":"2026-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2025GB008971","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148322385","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Global Patterns of Oceanic Nitrogen Fixation Over the Past Two Decades","authors":"Deyong Sun,&nbsp;Wenbin Huang,&nbsp;Zixu Ye,&nbsp;Shengqiang Wang,&nbsp;Hailong Zhang","doi":"10.1029/2026GB009279","DOIUrl":"https://doi.org/10.1029/2026GB009279","url":null,"abstract":"<p>Oceanic nitrogen fixation is a major external source of bioavailable nitrogen, sustaining marine primary production and regulating the global carbon cycle. However, its long-term variability and climate-driven mechanisms remain poorly constrained because observations are sparse. Here, we develop a global, high-resolution (0.25° × 0.25°), long-term (1997–2024) data set of marine N₂ fixation rates by establishing an ensemble machine-learning model with in situ measurements and other multi-source data. The reconstructed data set reveals pronounced spatial heterogeneity, with elevated rates concentrated in oligotrophic tropical and subtropical oceans (30°S–30°N), particularly in the northern Indian Ocean and the western Pacific-Maritime Continent region, where rates frequently exceed 160 μmol N m⁻² d⁻¹. Globally, N₂ fixation shows a weak but persistent increasing trend (∼2.8 × 10⁻² μmol N m⁻² d⁻¹ month⁻¹), with weak background changes superimposed by localized hotspots of increases and decreases. Basin-scale analysis reveals heterogeneous trends, with the strongest increases in the equatorial Atlantic and North Atlantic, and weak declines in the northern Indian Ocean and South Atlantic. Climate-mode attribution indicates regionally heterogeneous controls, with Western Hemisphere Warm Pool (WHWP), North Pacific Index (NP), and Niño 3.4 Index (Niño 3.4) emerging as dominant drivers across major oceanic subregions. WHWP dominates most Northern Hemisphere basins and the equatorial Atlantic, Niño 3.4 dominates the equatorial Pacific, and NP dominates the South Pacific and South Atlantic. This study provides a long-term global N₂ fixation data set and quantitative evidence for its sensitivity to major climate modes, improving understanding of climate-driven regulation of the oceanic nitrogen cycle.</p>","PeriodicalId":12729,"journal":{"name":"Global Biogeochemical Cycles","volume":"40 6","pages":""},"PeriodicalIF":6.9,"publicationDate":"2026-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148324677","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}