Global Biogeochemical Cycles最新文献

{"title":"Modeling Carbon Emissions Driven by Land-Use Change: Uncertainty and Sensitivity Analysis of Dynamic Global Vegetation Models","authors":"Jianyong Dong,&nbsp;Shuting Zhao,&nbsp;Ximing Chen,&nbsp;Zhangcai Yin,&nbsp;Akihiko Ito","doi":"10.1029/2026GB009219","DOIUrl":"https://doi.org/10.1029/2026GB009219","url":null,"abstract":"<p>As a key component of the climate system, terrestrial carbon dynamics are commonly simulated using Dynamic Global Vegetation Models (DGVMs), which provide essential information for estimating the global carbon budget. However, substantial uncertainties persist in DGVM-based estimates of land-use change carbon emissions, and their process-level origins remain poorly constrained. Here, we harmonize DGVM-based net land-use emissions (E_NLUC) from 23 TRENDY2025 DGVMs using a transient, time-varying PFT-level land-cover correction that explicitly removes the loss of additional sink capacity (LASC), and apply a hierarchical Bayesian mixed-effects variance decomposition framework to characterize between-DGVM heterogeneity in fitted coefficients associated with land-use predictors. LASC correction reveals that uncorrected DGVMs artificially converge toward bookkeeping estimates, masking persistent structural deficiencies—most notably the limited representation of wood harvest, forest management, and other peat-related activities incorporated in bookkeeping models. Between-DGVM heterogeneity in fitted coefficients is greater for persistent regrowth area than for current deforestation, particularly at decadal-to-centennial timescales and in the tropics, where the fitted association with persistent regrowth area varies substantially among models. This uncertainty can propagate into residual land sink estimates, complicating the diagnosis of land–atmosphere carbon exchange. Our results highlight that improving the representation of secondary forest recovery, including sub-grid land-use processes and forest management, is critical for reducing uncertainties in land-use and land-use change emissions in next-generation DGVMs.</p>","PeriodicalId":12729,"journal":{"name":"Global Biogeochemical Cycles","volume":"40 10","pages":""},"PeriodicalIF":6.9,"publicationDate":"2026-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2026GB009219","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149145708","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":"Metabolic Dynamics of an Offshore Coral Reef in the Central Red Sea: Observations From Autonomous Sensors","authors":"Emily M. Hammermeister,&nbsp;Sarah E. Cryer,&nbsp;Vincent Saderne,&nbsp;Chiara Pisapia,&nbsp;Stathys Papadimitriou,&nbsp;Sara E. Fowell,&nbsp;Jake Ludgate,&nbsp;Allison Schaap,&nbsp;Socratis Loucaides,&nbsp;Maggie D. Johnson","doi":"10.1029/2025GB008960","DOIUrl":"https://doi.org/10.1029/2025GB008960","url":null,"abstract":"&lt;p&gt;Coral reefs are increasingly threatened by local and global stressors. Traditional visual reef monitoring methods are time-intensive and provide only a snapshot of reef condition. Recent efforts aim to measure reef metabolism, or the balance of net community production (NCP) and net community calcification (NCC), as coral reef carbonate budgets shift globally toward declining NCC and greater NCP influence. Resolving these metabolic changes requires comprehensive, high-resolution biogeochemical measurements unattainable by traditional sampling alone. This work reports the novel multi-month deployment of a high-resolution, autonomous total alkalinity (TA) sensor alongside pH, partial pressure of &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msub&gt;\u0000 &lt;mtext&gt;CO&lt;/mtext&gt;\u0000 &lt;mn&gt;2&lt;/mn&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${text{CO}}_{2}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;, and dissolved oxygen (DO) sensors at Cement Wreck, a central Red Sea offshore reef. Observations from the back reef and fore reef revealed strong diel variability and distinct reef-zone biogeochemical dynamics linked to contrasting benthic compositions. On the back reef, pH and DO were tightly coupled and closely matched a Redfield-based model &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mfenced&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msup&gt;\u0000 &lt;mi&gt;R&lt;/mi&gt;\u0000 &lt;mn&gt;2&lt;/mn&gt;\u0000 &lt;/msup&gt;\u0000 &lt;mo&gt;=&lt;/mo&gt;\u0000 &lt;mn&gt;0.943&lt;/mn&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/mfenced&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; $left({R}^{2}=0.943right)$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;, while the fore reef relationship was weaker &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mfenced&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msup&gt;\u0000 &lt;mi&gt;R&lt;/mi&gt;\u0000 &lt;mn&gt;2&lt;/mn&gt;\u0000 &lt;/msup&gt;\u0000 &lt;mo&gt;=&lt;/mo&gt;\u0000 &lt;mn&gt;0.145&lt;/mn&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/mfenced&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; $left({R}^{2}=0.145right)$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;. TA observations allowed characterization of the back reef carbonate system, with TA–DIC stoichiometry yielding a slope of 0.26, indicating NCP accounted for approximately 87% of observed carbonate system variability. Compared to global reefs, Cement Wreck exhibits high % NCP contribution. However, the observed 2023 TA–DIC slope closely matches those from Red Sea observations from 1997 to 2013, suggesting that while reefs around the world shift, Re","PeriodicalId":12729,"journal":{"name":"Global Biogeochemical Cycles","volume":"40 10","pages":""},"PeriodicalIF":6.9,"publicationDate":"2026-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2025GB008960","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149144885","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":"Seasonal Variations in Aerosol Trace Element Source Contributions and Deposition Fluxes to the North Pacific Subtropical Gyre","authors":"C. Kollman,&nbsp;C. M. Marsay,&nbsp;D. C. Ohnemus,&nbsp;M. Stephens,&nbsp;E. S. Bates,&nbsp;M. J. Ricci,&nbsp;C. S. Buck","doi":"10.1029/2025GB009003","DOIUrl":"https://doi.org/10.1029/2025GB009003","url":null,"abstract":"<p>Trace elements deposited in the marine environment affect ocean biogeochemistry in numerous, complex ways. This study quantifies seasonal aerosol trace element (TE) fluxes and evaluates their variability and potential sources over a 2-year period in the North Pacific subtropical gyre (NPSG). We established the Hawaii Aerosol Time Series (HATS), which includes weekly integrated total suspended aerosol particle collections alongside sampling the cosmogenic radionuclide ⁷Be. As a conservative tracer in the surface ocean, ⁷Be can be used to estimate seasonal depositional fluxes of a suite of trace elements (Al, Co, Cr, Cu, Fe, Mn, Ni, Pb, Ti, V, and Zn). An annually recurring bimodal pattern with two periods of increased dust deposition on the NPSG was observed in the spring and late summer/fall. The transport of Asian dust in the spring dominates the annual aerosol loading to the NPSG, with an average Fe flux of 2,312 nmol/m²/d in 2022 and 1680 nmol/m²/d in 2023. Changing molar ratios of Al:Ti indicate varying influence of aerosol sources over the year, particularly during the two periods of enhanced atmospheric loading. In the late summer and fall, local Hawaiian inputs may contribute important trace elements, such as Fe, Mn, and Co to the surface ocean. These flux patterns have important implications for surface ocean trace element availability and may influence microbial nutrient limitation, particularly for nitrogen-fixing organisms. The HATS dataset is a novel contribution to TE studies in the region, providing a valuable framework for understanding atmospheric inputs to the oligotrophic ocean and their biogeochemical impacts.</p>","PeriodicalId":12729,"journal":{"name":"Global Biogeochemical Cycles","volume":"40 10","pages":""},"PeriodicalIF":6.9,"publicationDate":"2026-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2025GB009003","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149145584","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":"Spatial Variability and Long-Term Trends in Winter Phytoplankton of the Warming Eastern Mediterranean Sea","authors":"Zhongwei Yuan,&nbsp;Alon Blachinsky,&nbsp;Tom Reich,&nbsp;Yoav Lehahn,&nbsp;Ilana Berman-Frank,&nbsp;Eric P. Achterberg,&nbsp;Thomas J. Browning","doi":"10.1029/2026GB009273","DOIUrl":"https://doi.org/10.1029/2026GB009273","url":null,"abstract":"<p>The Eastern Mediterranean Sea (EMS) is among the fastest-warming ocean regions, but the impacts of this warming on phytoplankton are unclear. Here, wintertime field observations were conducted across the EMS. These observations showed that small photosynthetic eukaryotes (&lt;20 μm) dominated phytoplankton communities, collectively accounting for &gt;60% of total chlorophyll <i>a</i> (Chl-a) despite severe nitrate- and phosphate-depleted conditions. Among the environmental variables examined, surface Chl-a concentration and phytoplankton community structure were most strongly correlated with sea surface temperature (SST; Mantel's <i>r</i> = 0.46 and 0.41, respectively), which itself was significantly correlated with surface nitrate (Spearman's <i>ρ</i> = −0.49), phosphate (<i>ρ</i> = −0.48), silicic acid (<i>ρ</i> = −0.38), and nitracline depth (<i>ρ</i> = 0.63), and thus integrated a broader hydrographic gradient associated with nutrient availability. Warmer, more stratified eastern waters had lower Chl-a concentrations, greater cyanobacterial contributions to total Chl-a, and reduced contributions from eukaryotic phytoplankton. Quantile-specific analysis of 20-year satellite records showed widespread surface warming. Warming was strongest at the upper SST quantiles (spatial average 0.06°C year⁻¹), which occurred mainly during summer and early autumn and was seasonally aligned with limited changes in lower Chl-a quantiles. In contrast, lower SST quantiles warmed more slowly (0.04°C year⁻¹) and occurred mainly during winter and early spring, but coincided with the most spatially extensive declines in upper Chl-a quantiles. Together, these results suggest that regional warming is accompanied by disproportionate Chl-a losses, which occurred during the period of higher Chl-a concentrations in winter–spring.</p>","PeriodicalId":12729,"journal":{"name":"Global Biogeochemical Cycles","volume":"40 10","pages":""},"PeriodicalIF":6.9,"publicationDate":"2026-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2026GB009273","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149072744","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":"Seasonal and Interannual Variations in Methane Emissions and Carbon and Hydrogen Isotopes From an Upland Ombrotrophic Peat Bog","authors":"Mounir Takriti,&nbsp;Alexander Chadwick,&nbsp;Robert J. Rose,&nbsp;Beverley Dodd,&nbsp;Simon Oakley,&nbsp;Peter M. Wynn,&nbsp;Niall P. McNamara,&nbsp;Susan E. Ward","doi":"10.1029/2026GB009107","DOIUrl":"https://doi.org/10.1029/2026GB009107","url":null,"abstract":"<p>Despite their importance for global CH₄ biogeochemistry, there is limited evidence on seasonal patterns in CH₄ stable isotope composition from peatlands. We conducted a 2.5-year study investigating seasonal changes in CH₄ fluxes and dual-stable isotopes (δ¹³C, δ²H) in an ombrotrophic peat bog in Northern England. We performed chamber flux measurements and incubation experiments to quantify CH₄ and CO₂ fluxes, CH₄ isotopes, and CH₄ production and oxidation potential. CH₄ fluxes varied significantly across seasons and years, with exceptionally high emissions (&gt;45,000 μmol m⁻² h⁻¹) recorded in summer 2016, contrasting with median fluxes of 10.6–91.8 μmol m⁻² h⁻¹. Fluxes correlated with soil temperature and soil solution DOC and color, but not with water table depth, which had limited variability. Laboratory CH₄ production potentials peaked below the water table at 30–40 cm depths, while oxidation potential decreased with depth. Carbon and hydrogen isotope δ-values ranged from −88.4‰ to −73.2‰ and −345.3‰ to −275.6‰, respectively and showed opposing trends as ẟ¹³C increased with CH₄ flux while ẟ²H decreased. This is consistent with increasing fluxes being driven by acetoclastic methanogenesis. Our results highlight that seasonal shifts in CH₄ emissions are accompanied by changes in isotopic signatures, even without major changes in water table or CH₄ oxidation. Incorporating temporal variability into isotope-based CH₄ source attribution may therefore improve constraints on peatland emissions in global CH₄ budgets.</p>","PeriodicalId":12729,"journal":{"name":"Global Biogeochemical Cycles","volume":"40 9","pages":""},"PeriodicalIF":6.9,"publicationDate":"2026-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2026GB009107","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149048590","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":"CO2 Emissions From Rivers Draining the Tibetan Plateau Reveal Substantial Increases Over the Past 20 Years","authors":"Julia Iwan,&nbsp;Lishan Ran,&nbsp;Ronny Lauerwald,&nbsp;Martin Berggren,&nbsp;Pierre Regnier,&nbsp;Torbern Tagesson,&nbsp;Marko Scholze,&nbsp;Antje Gärtner,&nbsp;Fandong Meng,&nbsp;Yongli Zhou,&nbsp;Xuhui Wang,&nbsp;Ling Huang,&nbsp;Liyang Xiong,&nbsp;Yanzi Yan","doi":"10.1029/2025GB009016","DOIUrl":"https://doi.org/10.1029/2025GB009016","url":null,"abstract":"<p>Inland water CO₂ emissions are a critical component of the global carbon cycle, yet their magnitude and long-term response to climate change remain poorly constrained, primarily because of uncertainties in the air–water CO₂ concentration gradient. This knowledge gap is particularly pronounced on the Tibetan Plateau, where thin air and exceptional climate sensitivity complicate accurate quantification. To improve estimates of the air–water CO₂ concentration gradient in this remote region, we developed an optimized, locally adapted model that explicitly accounts for the region's thin air and low atmospheric CO₂ partial pressure. Our results indicate that annual riverine CO₂ emissions from the Tibetan Plateau averaged ∼37 ± 3 Tg C yr⁻¹ during 2000–2019, nearly double the previous estimate of 18.60 Tg C yr⁻¹. Spatially, riverine CO₂ emissions exhibited a distinct pattern, with lower emissions across the central plateau and higher emissions in the southeastern region, largely driven by steeper channel gradients and enhanced gas transfer velocities. Over the study period, riverine CO₂ emissions increased significantly by ∼14%, corresponding to an average rate of 0.25 Tg C yr⁻². This increase was closely linked to the expansion of discharge-dependent river surface area. These findings suggest that projected climate-driven increases in river discharge are likely to further enhance CO₂ emissions from the Tibetan Plateau. The high riverine CO₂ emissions and their temporal increase identified in this study also indicate an increasing role of inland waters in the regional carbon cycle, undermining efforts toward carbon neutrality.</p>","PeriodicalId":12729,"journal":{"name":"Global Biogeochemical Cycles","volume":"40 9","pages":""},"PeriodicalIF":6.9,"publicationDate":"2026-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2025GB009016","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149048199","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":"Assessment of Modeling Tree Stem Methane Fluxes Using Gridded Environmental Data Sets","authors":"Pengfei Zhao,&nbsp;Guanghui Huang,&nbsp;Benjamin Poulter,&nbsp;Youjing Fu,&nbsp;Yang Qi,&nbsp;Xin Li,&nbsp;Zhen Zhang","doi":"10.1029/2026GB009258","DOIUrl":"https://doi.org/10.1029/2026GB009258","url":null,"abstract":"<p>Tree stems are increasingly recognized as important components of methane (CH₄) production and consumption, yet their contribution to the terrestrial CH₄ budget remains highly uncertain due to sparse observations and challenges in upscaling in situ measurements. Here, we model tree stem CH₄ (TSCH₄) fluxes across wetland and upland ecosystems using multi-source gridded environmental data. We compiled 13,547 TSCH₄ flux observations from 90 published studies, supplemented by in situ measurements from two sites in 2025. Feature importance analysis identified the key structural and environmental drivers of TSCH₄ fluxes in wetland and upland ecosystems. Random forest models were developed using five predictors selected through feature selection and evaluated with a combined 10-fold cross-validation for upland and wetland TSCH₄ fluxes separately. Results suggest that tree structural traits (e.g., sampling height, diameter at breast height) and subsurface soil variables (e.g., deep soil temperature and moisture (100–289 cm), and belowground biomass) are key predictors of TSCH₄ fluxes. The models show reasonable predictive skill, with a mean coefficient of determination (<i>R</i>²) of 0.65 and a root mean square error (RMSE) of 3.26 nmol CH₄ m⁻² s⁻¹ for wetlands, and a mean <i>R</i>² of 0.64 and an RMSE of 0.70 nmol CH₄ m⁻² s⁻¹ for uplands. The models capture the seasonal variability of TSCH₄ fluxes in both wetland and upland ecosystems, with higher and later peaks in wetlands. The models demonstrate the potential for upscaling TSCH₄ by linking in situ measurements with gridded environmental predictors, improving our understanding of the role of tree stems in the terrestrial CH₄ budget.</p>","PeriodicalId":12729,"journal":{"name":"Global Biogeochemical Cycles","volume":"40 9","pages":""},"PeriodicalIF":6.9,"publicationDate":"2026-09-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149047972","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":"Biomineral Formation in the Subtropical South Pacific: Insights From Major Ions and Carbonate Chemistry Along GEOTRACES Section GP21","authors":"Edel M. O'Sullivan,&nbsp;Kathleen J. Gosnell,&nbsp;Xue-Gang Chen,&nbsp;Louise Delaigue,&nbsp;Eric P. Achterberg,&nbsp;Te Liu,&nbsp;Juan Höfer,&nbsp;Zvi Steiner","doi":"10.1029/2026GB009232","DOIUrl":"https://doi.org/10.1029/2026GB009232","url":null,"abstract":"<p>The South Pacific Ocean (SPO) hosts diverse biogeographical environments including the productive Peru-Chile upwelling region and ultra-oligotrophic subtropical gyre; however, vast areas are understudied regarding the cycling of dissolved calcium (Ca) and strontium (Sr), and distribution of major biomineral-forming pelagic marine organisms. This study presents a high-resolution basin-scale analysis of dissolved Ca and Sr along the GEOTRACES GP21 transect to trace the production of calcium carbonate (CaCO₃) and celestine (SrSO₄). We used Optimum Multiparameter Analysis (OMPA) to correct for conservative water mass mixing, and quantify cumulative non-conservative behavior of Ca and Sr along isopycnals to infer basin-wide biomineral export production rates of CaCO₃ and SrSO₄. Our findings revealed distinct, yet spatially variable rates of change in Ca and Sr associated with different balances between biomineral production and export driven by regional productivity gradients. In the upwelling region, biomineral export associated with high primary production was largely offset by strong biological recycling through higher grazing and shallow biomineral dissolution, reducing export efficiency. In contrast, lower grazing rates in the oligotrophic gyre led to a higher export rate. We highlighted the potential contribution of Acantharia to particulate organic carbon export production in the nutrient-poor SPO oligotrophic gyre and underscored the need for their inclusion in global biogeochemical models. This work advances our understanding of pelagic CaCO₃ and SrSO₄ cycling and its implications for carbon production and sequestration in the sparsely sampled SPO.</p>","PeriodicalId":12729,"journal":{"name":"Global Biogeochemical Cycles","volume":"40 9","pages":""},"PeriodicalIF":6.9,"publicationDate":"2026-09-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2026GB009232","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149047973","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":"Coastal Nitrogen, Phosphorus, and Silicon Sources: Integrating Land, Sea, and Human Inputs","authors":"John A. Harrison,&nbsp;Arthur H. W. Beusen,&nbsp;Lex (A.F.) Bouwman,&nbsp;Junjie Wang,&nbsp;Xiaochen Liu","doi":"10.1029/2026GB009128","DOIUrl":"https://doi.org/10.1029/2026GB009128","url":null,"abstract":"<p>Land-based human activities have greatly increased inputs of nutrients (nitrogen [N] and phosphorus [P]) to the coastal zone, while also decreasing silicon (Si) export. Here we present a novel synthesis of N, P, and Si sources to coastal waters and use that data set to evaluate: (a) the amount, global spatial distribution, and proportion of N, P, and Si delivered to coastal waters attributable to land-based human activities, (b) the impact of land-based and anthropogenic nutrient inputs on N:P ratios and an index of coastal eutrophication potential (ICEP) relative to marine-derived sources, including implications for coastal nutrient mitigation efforts, and (c) critical uncertainties and unknowns that should be addressed in order to better inform future efforts to quantify and mitigate coastal nutrient inputs and their negative impacts. We show that although total global inputs of N, P, and Si from marine sources (net upwelling and net onwelling) to coastal waters are larger than land-based inputs, land-based nutrient sources exceed marine-derived sources along roughly half of the world's coastline. In addition, anthropogenic sources of N and P are greater than all natural (marine-derived plus land-derived) sources in a substantial number of coastal segments (COSCATs; 25% of COSCATs for N and 11% of COSCATs for P). Also, human impact on N has been greater than on P, causing a shift toward P limitation globally, and both N and P loading have increased more than Si loading, resulting in increased ICEP, an indicator of the likelihood of harmful algal bloom occurrence.</p>","PeriodicalId":12729,"journal":{"name":"Global Biogeochemical Cycles","volume":"40 9","pages":""},"PeriodicalIF":6.9,"publicationDate":"2026-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2026GB009128","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148994539","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":"Microbial Activation of Terrestrial Phytogenic Silica Cycling","authors":"Trang T. H. Nguyen,&nbsp;Minh N. Nguyen,&nbsp;Anh Q. Nguyen,&nbsp;Anh T. Q. Nguyen,&nbsp;Chau T. T. Ngo,&nbsp;Dung H. Thai,&nbsp;Duc N. Nguyen,&nbsp;Hue T. Nguyen,&nbsp;Huy V. Dao,&nbsp;Linh H. Duong,&nbsp;Ngan T. Nguyen,&nbsp;Phuong M. Nguyen,&nbsp;Tuan V. Tran,&nbsp;Van M. Dinh","doi":"10.1029/2026GB009140","DOIUrl":"https://doi.org/10.1029/2026GB009140","url":null,"abstract":"<p>Phytogenic silica (<i>p</i>Si) is a bio-reactive phase of the terrestrial silicon (Si) cycle; however, the mechanisms governing its fate and mobility remain elusive. Plants sequester Si to form <i>p</i>Si, which is inherently embedded within the organic matrix of their biomass, resulting in organic matter-associated <i>p</i>Si (<i>Op</i>Si). Following biomass decomposition, <i>Op</i>Si and <i>p</i>Si are released into soil pools where they may transition into colloidal phases that serve as pivotal drivers for the transport and biogeochemical transformation of associated elements. Here, we identify a previously unrecognized microbial-driven engine governing <i>Op</i>Si and <i>p</i>Si mobility. We hypothesized that bacteria release <i>Op</i>Si and <i>p</i>Si by enzymatically consuming the organic matrix and degrading the particle coatings. This process triggers a shift in interfacial reactivity that markedly increases the surface charge and colloidal mobility of <i>p</i>Si via electrostatic repulsion. To test this hypothesis, we utilized a model <i>Op</i>Si and <i>p</i>Si colloid pair prepared from rice straw and <i>Bacillus velezensis</i> to quantify evolving biophysical interactions. Micro-morphological and surface charge analyses confirmed the presence of an intact organic sheath shielding the <i>p</i>Si core. This organic shield maintains a low surface charge density on <i>Op</i>Si (i.e., 5.7 ± 0.5 site nm⁻²) and negligible bacterial repulsion, effectively keeping <i>p</i>Si stagnant. When the organic sheath is consumed by microbes, the exposure of the high-charge silica core causes the surface charge density to escalate dramatically, reaching 34.1 ± 0.7 site nm⁻² upon the complete conversion of <i>Op</i>Si to <i>p</i>Si. This microbially driven “activation” transforms stagnant <i>p</i>Si into a highly mobile phase, thereby increasing its mobility in the environment.</p>","PeriodicalId":12729,"journal":{"name":"Global Biogeochemical Cycles","volume":"40 9","pages":""},"PeriodicalIF":6.9,"publicationDate":"2026-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148994034","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}