Journal of Geophysical Research: Biogeosciences最新文献

{"title":"Pollen Mineralization Fuels Biogeochemical Cycling and Microbial Community Succession in Lake Superior","authors":"Jake D. Zunker,&nbsp;Kathryn M. Schreiner,&nbsp;Andrew W. Wood,&nbsp;Britta L. Larson,&nbsp;Chan Lan Chun,&nbsp;Keagan Bailey,&nbsp;Elizabeth C. Minor,&nbsp;Eva Hendrickson,&nbsp;Christopher T. Filstrup","doi":"10.1029/2025JG009473","DOIUrl":"https://doi.org/10.1029/2025JG009473","url":null,"abstract":"<p>Pollen is a terrigenous particulate regarded as recalcitrant organic matter (OM) in aquatic ecosystems, seasonally introducing undetermined quantities of terrigenous OM to inland lakes. The role of pollen as a carbon and nutrient delivery mechanism for large aquatic ecosystems remains an understudied component of biogeochemical cycling. Here, we examined the effects of pollen mineralization on carbon and nutrient availability to evaluate its potential as an unquantified seasonal source and driver of microbial community succession in Laurentian Great Lake (LGL) Superior. Pollen was added to water collected from LGL Superior and incubated in the dark at 4°C for 60 days. Water samples were measured for dissolved and particulate fractions of carbon (C), nitrogen (N), and phosphorus (P) alongside ultraviolet-visible spectroscopy. Microbial community succession was assessed through metagenomic sequencing and abundance estimates at selected times. Results show immediate, significant increases in dissolved chemical fractions, with 21.0% of the initial weight of pollen C, 28.1% N, and 40.1% P chemically leaching. Extrapolated lake-wide, pollen leaching resembles a potential loading of up to 0.30 Tg C yr⁻¹, 17.3 Gg N yr⁻¹, and 1.64 Gg P yr⁻¹. Subsequent increases in estimated prokaryotic abundance and decreases in dissolved nutrients were accompanied by shifts in microbial community composition expressing increases of 5% amino acid and 10% carbohydrate metabolism over the experimental duration. These results suggest pollen contains labile OM fractions that are a substantial source of bioavailable carbon and nutrients that can fuel microbial succession and seasonal dynamics in large lakes.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"131 8","pages":""},"PeriodicalIF":3.7,"publicationDate":"2026-08-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2025JG009473","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148784397","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Long-Term Change in the Concentration-Discharge Relationship Suggests Controls on Watershed Exports of Dissolved Organic Carbon From Forested Headwater Streams","authors":"Christopher T. Solomon,&nbsp;Emily S. Bernhardt,&nbsp;Charles T. Driscoll,&nbsp;Mark B. Green,&nbsp;William H. McDowell","doi":"10.1029/2026JG009756","DOIUrl":"https://doi.org/10.1029/2026JG009756","url":null,"abstract":"<p>Dissolved organic carbon (DOC) export from watersheds by streams is an important and changing component of the global carbon cycle. We examined controls on DOC export by quantifying changes in the DOC concentration-discharge relationship between 1992 and 2022 for nine forested headwater catchments at the Hubbard Brook Experimental Forest (northeastern United States), which historically received high atmospheric acid deposition. We observed an increase in the intercept of the log-log concentration-discharge relationship and a weaker increase in the slope of that relationship, along with seasonal and watershed-level differences. The intercept, which indicates the average stream DOC concentration at a given discharge, was inversely related to the ionic strength of the soil solution as predicted by electrolyte solubility theory. This relationship varied between the two watersheds where soil solution chemistry data were available in response to soil pH. The intercept was not strongly related to annual precipitation or air temperature. DOC export ranged from 13 to 156 kg C ha⁻¹ y⁻¹ among study watersheds and years, and was correlated with annual precipitation and discharge. Historical data suggest that DOC export has increased over the past 50 years, likely due to both increases in precipitation and runoff and increases in the intercept and slope of the concentration-discharge relationship. Our results suggest the potential for long-term legacy effects of acidification on DOC solubility and stream DOC concentrations in acid-impacted watersheds, despite reductions in acid deposition, as mineral weathering slowly replenishes the ionic strength and buffering capacity of soil solutions.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"131 8","pages":""},"PeriodicalIF":3.7,"publicationDate":"2026-08-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2026JG009756","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148784427","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Bridging Single-Tree Processes and Regional-Scale Patterns to Explain Vegetation Drought Resistance and Resilience in a Sierra Nevada Headwater Catchment","authors":"Annie Tucker,&nbsp;Marc Dumont,&nbsp;Joel Singley,&nbsp;Nathan Lenssen,&nbsp;Russell Callahan,&nbsp;Adrienne Marshall,&nbsp;Luke Jacobsen,&nbsp;Kamini Singha","doi":"10.1029/2025JG009585","DOIUrl":"https://doi.org/10.1029/2025JG009585","url":null,"abstract":"<p>Droughts have been extensively studied at small to large scales, yet limited work has integrated the mountain-range and tree-level perspectives to explain tree drought response at the intra-catchment scale where management decisions are made. Here, we investigated tree response to drought in terms of resistance—the ability of a forest to continue transpiring during drought—and resilience—the ability to rebound post-drought. We estimated resistance and resilience using Landsat-derived normalized difference vegetation index (NDVI) over a 0.5 km² catchment of the Southern Sierra Critical Zone Observatory. At the catchment-wide scale, we fitted generalized additive models with eight remotely sensed predictors to explain 51% of the variance in resistance and 59% in resilience. Topography and baseline greenness were the strongest predictors and exhibited opposite effects on resistance versus resilience, underscoring the need to distinguish their drivers. Aspect and snow depth were significant for resilience only, further highlighting that resistance and resilience are governed using partially distinct processes. Slope and elevation effects contradicted regional-scale patterns, whereas canopy height effects were consistent across scales. Remote sensing revealed spatial patterns of drought response, while in situ ecohydrological, meteorological, and geophysical (electrical resistivity) data from six stations offered process-based insights into the conditions underlying them: valley-bottom hydrologic refugia, inferred reliance on internal sapwood water stores, and consistently low atmospheric demand were all associated with locations that experienced greater drought resistance. This work demonstrates that forest vulnerability emerges from coupled, scale-dependent interactions among hydrology, vegetation structure, and topography.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"131 8","pages":""},"PeriodicalIF":3.7,"publicationDate":"2026-08-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2025JG009585","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148784060","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Riverine Biogeochemical Exports From Major Watersheds to the Northwest Patagonian Estuarine Network","authors":"Sage Fox,&nbsp;Jorge León-Muñoz,&nbsp;Brian Reid,&nbsp;Anna Astorga-Roine,&nbsp;Rodrigo Aguayo,&nbsp;Paulo Moreno-Meynard,&nbsp;Lydia Blanchet,&nbsp;David E. Butman","doi":"10.1029/2025JG009482","DOIUrl":"https://doi.org/10.1029/2025JG009482","url":null,"abstract":"<p>River discharge considerably influences marine ecosystems through hydrological and biogeochemical drivers. Measuring baseline variability of riverine inputs, and their relation to anthropogenic land-use impacts and global climate stressors affecting watersheds is therefore crucial for managing coastal marine ecosystems. This is particularly relevant in the relatively undisturbed Northwest Patagonia region (NWP; 41°S–46.5°S), where an extensive estuarine system influenced by high river runoff supports much of Chile's aquaculture economy (est. $6+ billion USD). Combining an unprecedented weekly citizen-monitoring effort and daily streamflow data with a weighted-regression modeling approach, we estimated inputs of macronutrients, dissolved iron, dissolved silica, and total suspended solids as well as characterized dissolved carbon concentrations from the five largest watersheds to the NWP marine environment. We used these estimates to evaluate export magnitude, seasonality, synchrony, and potential influence on marine ecosystems. Our results suggest that large rivers have a net dilution effect on total nitrogen and phosphorus, with freshwater concentrations substantially lower than those reported for NWP fjords and comparable coastal temperate rainforest rivers globally. Conversely, freshwater concentrations of dissolved silica and iron were markedly higher than those in marine waters and other coastal temperate rainforest rivers. Collectively, these results suggest a potential regulating function of large watersheds to marine ecosystems in Northwest Patagonia, with implications for harmful algal blooms and for managing external inputs from aquaculture and changing watershed land-use. Our findings provide one of the first comprehensive regional baselines for major watersheds in reference conditions linked to temperate fjord ecosystems.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"131 8","pages":""},"PeriodicalIF":3.7,"publicationDate":"2026-08-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2025JG009482","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148784061","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"From Stable to Labile: Forest Expansion Drives Changes in Alpine Soil Carbon Fractions","authors":"Chandra Man Rai,&nbsp;Anna B. Miller,&nbsp;Karen H. Beard,&nbsp;Andrew Kulmatiski,&nbsp;Jeanette M. Norton,&nbsp;Yong Zhou","doi":"10.1029/2026JG009751","DOIUrl":"https://doi.org/10.1029/2026JG009751","url":null,"abstract":"<p>Forests are expected to continue to expand into alpine ecosystems as temperatures increase. While forest expansion typically increases aboveground carbon storage, the consequences for belowground soil carbon storage and stability remain unclear. To address this, we combined a field-based study in the eastern Himalaya of Bhutan with a meta-analysis examining how forest expansion influences alpine soil organic carbon (SOC) and its fractions. We sampled 120 surface soils (0–15 cm) and excavated 20 soil pits (0–100 cm) across a forest-ecotone-alpine gradient on Chelela Mountain in western Bhutan. We quantified total SOC, particulate organic carbon (POC), mineral-associated organic carbon (MAOC), and MAOC:POC ratio. Locally, forest expansion was associated with higher total SOC, especially in the ecotonal transition zone and in deeper soil layers. Ecotone soils had the greatest SOC, driven largely by MAOC, linked to greater root biomass and higher clay and silt content, whereas POC peaked in the mature forest soils. Although alpine soils stored less total SOC because of shallower soils, they contained a higher proportion of stable carbon, reflected in the highest MAOC:POC ratios. Globally, forest expansion did not significantly change SOC or POC, but significantly reduced MAOC (−28.4%) and the MAOC:POC ratio (−18.3%). These responses varied across ecosystems, where broadleaf expansion decreased SOC via reduced POC, while coniferous and shrub expansion reduced MAOC:POC ratios. Collectively, these findings suggest that forest expansion may shift soil carbon storage from stable mineral-associated forms to more labile particulate fractions, potentially reducing the long-term stability of carbon stored in alpine ecosystems.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"131 8","pages":""},"PeriodicalIF":3.7,"publicationDate":"2026-08-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148783986","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Nonlinear Interactions Between Solar-Induced Fluorescence, Atmospheric Demand, and Soil Moisture Constrain Ecosystem Evapotranspiration Estimation","authors":"Subhrasita Behera,&nbsp;Debsunder Dutta","doi":"10.1029/2026JG009892","DOIUrl":"https://doi.org/10.1029/2026JG009892","url":null,"abstract":"<p>Evapotranspiration (ET) links the terrestrial water and carbon cycles, yet its accurate estimation remains limited by simplified representations of plant-atmosphere interactions. Solar-induced chlorophyll fluorescence (SIF) has emerged as a promising physiological constraint on ET through its link to stomatal conductance, but current SIF-based semi-mechanistic models assume fixed, linear relationships that limit their applicability under variable environmental conditions. Here, we evaluate a widely used SIF-driven semi-mechanistic ET model against eddy covariance observations from 31 flux tower sites spanning eight plant functional types, and employ an interpretable machine learning (ML) framework with SHAP (SHapley Additive exPlanations) analysis to identify where these formulations become limiting. The performance gap widens markedly under environmental stress, with the semi-mechanistic model showing reduced skill under low soil moisture (<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msup>\u0000 <mi>R</mi>\u0000 <mn>2</mn>\u0000 </msup>\u0000 </mrow>\u0000 <annotation> ${R}^{2}$</annotation>\u0000 </semantics></math> = 0.53 vs. 0.70 for ML) and high vapor pressure deficit (VPD) (<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msup>\u0000 <mi>R</mi>\u0000 <mn>2</mn>\u0000 </msup>\u0000 </mrow>\u0000 <annotation> ${R}^{2}$</annotation>\u0000 </semantics></math> = 0.45 vs. 0.65), indicating that fixed conductance formulations fail where nonlinear physiological regulation intensifies. SHAP diagnostics reveal that SIF and VPD are the dominant predictors of ET but their influence is conditional, with SIF-ET coupling modulated by soil water content and VPD exhibiting threshold-dependent behavior. PM-ML analysis confirms that this limitation lies in the linear conductance formulation based on SIF, and global-scale validation confirms these patterns across vegetated land. These results demonstrate that nonlinear coupling between photosynthetic activity, atmospheric demand, and soil water availability represents a first-order control on ecosystem ET that current semi-mechanistic formulations cannot adequately capture, and that interaction-aware parameterizations of stomatal conductance are needed to reduce biases across ecosystems.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"131 8","pages":""},"PeriodicalIF":3.7,"publicationDate":"2026-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148783539","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Global Grassland Patterns and Changes Revealed by Spatial Distribution of Poaceae Pollen","authors":"Lai-Zheng Jiao,&nbsp;Wen-Ping Yuan,&nbsp;David K. Ferguson,&nbsp;Wen-Li Chen,&nbsp;Yu-Fei Wang,&nbsp;Yi-Feng Yao","doi":"10.1029/2026JG010063","DOIUrl":"https://doi.org/10.1029/2026JG010063","url":null,"abstract":"<p>Grasslands are among the most important terrestrial ecosystems on Earth. Grasslands dominated by Poaceae are essential carbon pools and play a vital role in maintaining biodiversity, absorbing atmospheric CO₂ and delivering ecosystem services. Understanding the past, current and future distributions of grasslands is important for coping with grassland degradation, developing reasonable ecological protection strategies and predicting ecosystem functions. The abundant data on Poaceae pollen abundance (PA) from global surface sediments provide valuable insights into simulating current grassland distribution patterns and forecasting their future trajectories under climate change. We created a data set containing 16,372 records with both characteristic variables (including vascular plant richness, bioclimatic, soil and elevation variables) and Poaceae PA and used a random forest model to simulate the spatial distribution of Poaceae PA. Results show a significant difference in the distribution of Poaceae PA across continents, with regions of higher abundance (e.g., ∼10% in temperate regions and ∼40% in tropical regions) closely aligned with the distribution of grasslands. Furthermore, we project the distribution of grass PA under four future climate scenarios (SSP126, 245, 370, 585) and the changes of grasslands. We find that the grassland coverage will likely increase at the end of this century. In particular, the temperate grasslands in the Northern Hemisphere are expected to expand northwards based on all the scenarios, whereas the Amazon savannas will also expand, thus encroaching on rainforests. Our findings offer a new perspective for understanding the changes in grasslands and their future development for both the scientific community and policy-makers.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"131 8","pages":""},"PeriodicalIF":3.7,"publicationDate":"2026-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148754102","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Analysis of Arsenic, Cadmium, Chromium, and Lead Levels: Interplay of Climate, Soil, and Human Factors in Urban Gardens","authors":"Leah Kocian,&nbsp;Binayak P. Mohanty,&nbsp;Azita Sharif","doi":"10.1029/2025JG009448","DOIUrl":"https://doi.org/10.1029/2025JG009448","url":null,"abstract":"<p>Understanding the spatial distribution of heavy metals in urban gardens is essential for mitigating contamination risks and supporting safe urban agriculture. This study examines factors influencing heavy metal concentrations in garden soil across San Antonio, Dallas, and Houston. A total of 215 soil samples, collected at the surface and down to 30 cm, were analyzed using Inductively Coupled Plasma–Mass Spectrometry for nine heavy metals, including arsenic (<i>As</i>), chromium (<i>Cr</i>), cadmium (<i>Cd</i>), and lead (<i>Pb</i>), which are elements of environmental and health concern due to their potential toxicity and, in some cases, carcinogenic properties. Over half (55%) of the samples exceeded the Environmental Protection Agency residential soil threshold for <i>As</i> (0.68 ppm). To identify key drivers, we applied both multivariate linear regression and a generalized mixed graphical network model. While regression highlights independent relationships between variables, the network model comprehensively captures nonlinearly interconnected relationships across variables. It revealed strong links between <i>As</i> and total soil carbon, <i>Cd</i> and clay content, <i>Pb</i> and distance to city center, and <i>Cr</i> and proximity to Superfund sites. A random forest model, informed by the top predictors from the network analysis, achieved its best performance for <i>As</i> (<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msup>\u0000 <mi>R</mi>\u0000 <mn>2</mn>\u0000 </msup>\u0000 <mo>=</mo>\u0000 <mn>0.54</mn>\u0000 </mrow>\u0000 <annotation> ${R}^{2}=0.54$</annotation>\u0000 </semantics></math>). A combined network model including all four metals emphasized distance to the city center and clay percentage as the most influential factors. The highest average concentrations occurred in gardens within five miles of the city center and in soils with &lt;15% clay. These findings highlight the major drivers of metal concentrations in urban garden soils within the study region.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"131 8","pages":""},"PeriodicalIF":3.7,"publicationDate":"2026-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2025JG009448","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148753527","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Siderophores Reshape Microbial Fe(III) Reduction and Arsenic Release From Iron (Oxyhydr)Oxides","authors":"Si Meng Li,&nbsp;Wei Xiu,&nbsp;Xi Yang Xu,&nbsp;Jin Xing Xie,&nbsp;Zhi Xin Fang,&nbsp;Di Zhang,&nbsp;Jonathan R. Lloyd,&nbsp;Andreas Kappler,&nbsp;Hua Ming Guo","doi":"10.1029/2026JG009686","DOIUrl":"https://doi.org/10.1029/2026JG009686","url":null,"abstract":"<p>High-arsenic (As) groundwater is a global environmental concern, with As release largely governed by microbial reductive dissolution of Fe(III) (oxyhydr)oxides. Dissolved organic matter (DOM) rich in Fe-complexing ligands can modify these reactions, yet its influence on Fe(III) (oxyhydr)oxides transformation and associated As mobility remains poorly constrained. Here, we investigated the microbial reduction of As-bearing goethite by <i>Shewanella oneidensis</i> MR-1 in the presence of the hydroxamate siderophore desferrioxamine B (DFOB), used as a model strong Fe-complexing organic ligand, Luria–Bertani rather than a compositional analogue of bulk DOM. Results showed that DFOB markedly enhanced microbial Fe(III) reduction, increasing initial reduction rates by up to 70% and total Fe(II) production by 24% relative to MR-1-only controls. This acceleration stemmed from DFOB-facilitated Fe(III) complexation and improved electron-transfer interactions between MR-1 and goethite. Arsenic release occurred in all treatments and was positively correlated with the amount of reacted Fe (dissolved plus reduced Fe), indicating coupled Fe-As redox cycling. Despite stimulating Fe(III) reduction, DFOB did not promote additional As release, with MR-1-DFOB treatments exhibiting As mobilization similar to MR-1-only controls. This constrained As release was likely associated with DFOB-mediated redistribution of biogenic Fe(II) into solid-associated Fe pools and secondary Fe-rich phases, including locally observed nano-magnetite, minor siderite, and possibly poorly crystalline Fe phases, which may have contributed to As retention through adsorption and coprecipitation. These results reveal that DOM rich in Fe-complexing ligands, such as siderophores, can promote the formation of As-sequestering Fe-mineral phases, uncovering an unrecognized control on Fe-As interactions that may shape groundwater As mobilization.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"131 8","pages":""},"PeriodicalIF":3.7,"publicationDate":"2026-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148753232","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Dynamic Interplay Between Biogenic Fe(III) (Oxyhydr)Oxides and Microbial Reduction Pathways Governs Arsenic Mobilization","authors":"Si Meng Li,&nbsp;Wen Jie Yuan,&nbsp;Wei Xiu,&nbsp;Xiao Nuo Yu,&nbsp;Di Zhang,&nbsp;Tian Tian Ke,&nbsp;Zhi Xin Fang,&nbsp;Guang Yao Liu,&nbsp;David A. Polya,&nbsp;Jonathan R. Lloyd,&nbsp;Hua Ming Guo","doi":"10.1029/2026JG009874","DOIUrl":"https://doi.org/10.1029/2026JG009874","url":null,"abstract":"<p>Microbial reductive dissolution of As-bearing Fe(III) (oxyhydr)oxides is a primary mechanism of arsenic (As) mobilization in reducing aquifers; however, the relative contributions of mineral bioreactivity and microbial metabolic pathways remain insufficiently quantified. Here, we compared Fe(III)-reducing bacteria (<i>Shewanella oneidensis</i> MR-1 and <i>Geobacter sulfurreducens</i>) with a bacterium capable of both As(V) and Fe(III) reduction (<i>Clostridium</i> sp. anHT01, isolated from a high As aquifer sediment from Inner Mongolia) to elucidate Fe and As release kinetics from As(V)-bearing biogenic ferrihydrite-goethite (Bio-GF) and lepidocrocite (Bio-Lp) under bicarbonate-buffered reducing conditions. Biogenic mineralogy primarily governed the extent of Fe(III) reduction, with Bio-GF exhibiting higher bioreactivity than Bio-Lp, but did not dictate net As mobilization. In contrast, microbial metabolic pathways controlled the temporal relationship between Fe reduction and As release. Systems with active As(V) reduction exhibited delayed Fe(III) reduction yet rapid As(III) release, resulting in elevated As_released/Fe_released ratios and net As mobilization during the Fe-reduction lag phase. Secondary Fe(II) minerals modulated As partitioning and retention but did not govern the onset of As mobilization. Together, these results demonstrate that As mobilization during microbial reduction of biogenic Fe(III) (oxyhydr)oxides is jointly governed by mineral bioreactivity and microbially mediated Fe-As release relationships, providing a mechanistic basis for improving the prediction of As behavior in reducing aquifer systems.</p>","PeriodicalId":16003,"journal":{"name":"Journal of Geophysical Research: Biogeosciences","volume":"131 8","pages":""},"PeriodicalIF":3.7,"publicationDate":"2026-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148753233","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}