Global Biogeochemical Cycles最新文献

{"title":"Drivers and Patterns of Sediment Organic Carbon in European Regional Seas","authors":"Christian Lønborg,&nbsp;Anna Elizabeth Løvgren Graversen,&nbsp;Anna Maria Addamo,&nbsp;Jorge Assis,&nbsp;Michael Timothy Burrows,&nbsp;Eleanor Stewart,&nbsp;Helen Lillis,&nbsp;Mark John Costello,&nbsp;Dorte Krause-Jensen","doi":"10.1029/2026GB009100","DOIUrl":"https://doi.org/10.1029/2026GB009100","url":null,"abstract":"<p>Mapping organic carbon (OC) stores in marine sediments is a management priority to potentially minimize the anthropogenic release of organic carbon from the seabed. Sediment OC content shows high regional variability, shaped by a complex interplay of physical, chemical, biological and anthropogenic factors. In this study, we present an assessment of the drivers and patterns of sediment OC across European regional seas, with a particular focus on the role of large-scale habitats, substratum characteristics, and environmental conditions. To investigate these relationships, we integrated data sets encompassing sediment OC, benthic habitats, sediment substrata and 11 environmental variables. Applying machine learning techniques, we identified wave exposure (estimated from wave fetch), light availability, seafloor geomorphic features, and maximum bottom water temperature as the most important environmental predictors of sediment OC content across European regional seas. While the model captured broad spatial patterns in sediment OC, it did not resolve local scale variability, making it better suited for regional assessments than for site-specific predictions. Overall, the highest OC contents were found in sediments underlying vegetated habitats such as <i>Posidonia</i> <i>oceanica</i> and other seagrass meadows as well as in mud, and mixed sediment substrata. OC hotspots were generally located in inshore areas with low wave fetch and temperature; these include areas of the Baltic Sea, North Sea, Adriatic Sea, Barents Sea, and the Black Sea. Our data-driven approach provides a robust foundation for identifying OC-rich sediments, which are critical for conservation planning and assessing anthropogenic impacts on marine OC.</p>","PeriodicalId":12729,"journal":{"name":"Global Biogeochemical Cycles","volume":"40 8","pages":""},"PeriodicalIF":6.9,"publicationDate":"2026-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2026GB009100","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148784036","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":"High-Resolution Particle Imaging Reveals the Importance of Phytodetrital Aggregate Flux and Mesopelagic Grazing for Carbon Storage in the Southern Ocean","authors":"S. H. O’Daly,&nbsp;G. M. M. Hennon,&nbsp;T. B. Kelly,&nbsp;R. Kiko,&nbsp;R. M. Lekanoff,&nbsp;J. L. Pretty,&nbsp;S.-M. Schröder,&nbsp;A. M. P. McDonnell","doi":"10.1029/2025GB008685","DOIUrl":"https://doi.org/10.1029/2025GB008685","url":null,"abstract":"<p>The biological, chemical, and physical processes in the mesopelagic zone that impact carbon flux to the deep ocean are poorly understood, particularly in the Southern Ocean, despite their importance to deep ocean carbon storage. Using a CTD-mounted underwater imaging system, the Underwater Vision Profiler 5, we observed distributions of large marine particles across two basin-scale global ocean ship-based hydrographic investigations program repeat hydrography transects in the Pacific and African sectors of the Southern Ocean. Utilizing deep learning features and unsupervised clustering, 2.6 million images of particles were classified by type into 46 detrital categories within four supercategories (e.g., fluffy aggregates, dense aggregates, fibers, feces) and 61 living categories within four supercategories (e.g., crustaceans, rhizarians, gelatinous zooplankton, <i>Trichodesmium</i>). Different frontal zones generally have distinct patterns in particles, which illuminate different flux pathways. We observed a “Fluffy Aggregate Flux Pathway”, where high fluffy aggregate abundance was observed from the surface to 3,000 m at the same time as elevated surface chlorophyll <i>a</i>. We also observed a “Zooplankton Mediated Flux Pathway,” where grazers were located primarily in the lower mesopelagic zone, and feces and dense aggregates were in high abundance in the abyssopelagic zone. These results highlight two export pathways in the Southern Ocean, both of which contribute to long-term carbon storage at depth.</p>","PeriodicalId":12729,"journal":{"name":"Global Biogeochemical Cycles","volume":"40 8","pages":""},"PeriodicalIF":6.9,"publicationDate":"2026-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2025GB008685","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148753867","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":"Declining Contribution of Nitrogen Deposition to the Interannual Variability of Terrestrial Gross Primary Productivity","authors":"Shiliang Chen,&nbsp;Bin Chen,&nbsp;Shaoqiang Wang,&nbsp;Li Zhang,&nbsp;Jiageng Ma,&nbsp;Zhenhai Liu,&nbsp;Jinghua Chen","doi":"10.1029/2026GB009129","DOIUrl":"https://doi.org/10.1029/2026GB009129","url":null,"abstract":"<p>Global nitrogen deposition has steadily increased since the 1980s, peaking around 2015 before stabilizing. However, atmospheric chemical transport models often underestimate its magnitude, limiting accurate assessments of its impacts on terrestrial gross primary productivity (GPP). In this study, we elucidated the drivers of interannual GPP variability and quantified the contribution of nitrogen deposition from 1980 to 2020 using the latest global nitrogen deposition data set, the TRENDY GPP products, and an interpretable machine learning framework (SHAP). Our findings revealed a consistent expansion in global GPP over the past four decades, averaging 156.95 ± 6.4 Pg C yr⁻¹. As nitrogen deposition has recently stabilized, its contribution to global GPP has shifted from a stimulatory effect to a source of negative fluctuations. This transition is attributable to the declining sensitivity of GPP to nitrogen deposition, potentially driven by increasing vegetation water stress. Climatic factors, primarily temperature and precipitation, dominate interannual GPP fluctuations across plant functional types (PFTs), and nitrogen deposition explains 8.7 ± 2.9% of global variability. Notably, nitrogen enrichment stimulated GPP in grasslands and croplands but had an inhibitory effect on tropical forests. Moreover, the nonlinear response of GPP to nitrogen deposition exhibited distinct optimal thresholds across PFTs, with the global vegetation optimum identified at 12.5 kg N ha⁻¹ yr⁻¹. Crucially, the direct effect of nitrogen deposition on GPP outweighed its synergistic interactions with climate and CO₂ concentrations, suggesting that nitrogen availability independently modulates terrestrial carbon sinks. This study underscores the biome-specific sensitivities to nitrogen loading and highlights the necessity of incorporating nitrogen-saturation thresholds into predictions of ecosystem feedback to global change.</p>","PeriodicalId":12729,"journal":{"name":"Global Biogeochemical Cycles","volume":"40 8","pages":""},"PeriodicalIF":6.9,"publicationDate":"2026-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148754092","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":"Interhemispheric Asymmetry in Air-Sea CO2 flux Trends Across Eastern Boundary Current Systems Under a High Warming Scenario","authors":"Priyanka Banerjee,&nbsp;S. Prasanna Kumar","doi":"10.1029/2025GB008860","DOIUrl":"https://doi.org/10.1029/2025GB008860","url":null,"abstract":"<p>Eastern boundary current systems (EBCSs) transport cold, carbon-rich polar waters toward the equator. Wind-driven coastal upwelling within EBCSs fuels intense biological activity, modulating upper ocean pH, middepth oxygen levels, and carbon cycling. While past studies have primarily examined upwelling dynamics and productivity responses to climate change, the future of carbon uptake in EBCSs remains poorly understood. Using results from multiple Earth system models from the Coupled Model Intercomparison Project Phase 6 (CMIP6), we show that during 2015–2100 the Southern Hemisphere EBCSs are projected to experience significantly greater positive trends in air-sea CO₂ flux (F_CO2), implying stronger uptake or reduced outgassing of CO₂, compared to their Northern Hemisphere counterparts. Such asymmetry arises from weakening of EBCSs owing to greater poleward shifts of the subtropical gyres over the Southern Hemisphere compared to the Northern Hemisphere. These changes enhance the poleward advection of warm tropical waters while suppressing the supply of carbon-rich waters from high latitudes by the EBCSs, thereby increasing (reducing) upper ocean CO₂ uptake (outgassing) in the EBCSs despite complex upwelling trends. Across the CMIP6 models, there exists a consistent link between the magnitude of poleward shifts of the subtropical gyres and the magnitude of positive F_CO2 trends in the EBCSs. Our findings reveal a robust interhemispheric contrast in carbon uptake, offering new insights into how large-scale circulation shifts influence both global and regional carbon budgets.</p>","PeriodicalId":12729,"journal":{"name":"Global Biogeochemical Cycles","volume":"40 8","pages":""},"PeriodicalIF":6.9,"publicationDate":"2026-08-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148753625","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":"CbPM Estimates of Net Primary Production in the North Atlantic From Profiling Floats and Satellites Diverge Seasonally Due To Fluorescence and Vertical Extrapolation Effects","authors":"Nina Buzby,&nbsp;Andrea J. Fassbender,&nbsp;Alison R. Gray,&nbsp;Marin Cornec,&nbsp;Jacki Long,&nbsp;Ellen Park","doi":"10.1029/2025GB008952","DOIUrl":"https://doi.org/10.1029/2025GB008952","url":null,"abstract":"<p>Marine net primary production (NPP), defined as the difference between gross production and phytoplankton respiration, is often estimated using algorithms applied to remote sensing data. While assumptions are needed to extend surface satellite observations through depth, some NPP algorithms, like the Carbon-based Productivity Model (CbPM), have been adapted to vertically resolved data collected by autonomous profiling floats. Such applications eliminate the need for vertical extrapolation but introduce challenges related to float measurements of fluorescence rather than chlorophyll-<i>a</i> (Chl-<i>a</i>; required CbPM input). This study analyzes over a decade of float observations from the North Atlantic to estimate NPP using CbPM and quantify its sensitivity to different input parameters: (a) fluorescence versus Chl-<i>a</i>, (b) vertically extrapolated versus depth-resolved information, and (c) in situ versus remote observations of the first optical depth—the impacts of which vary seasonally and regionally. In higher latitude waters, converting float fluorescence to Chl-<i>a</i> using a novel correction based on satellite data produces significantly smaller NPP estimates at seasonal and annual timescales. In contrast, extrapolation and platform-related differences largely compensate when integrated vertically and annually, such that cumulative annual depth-integrated NPP (iNPP) estimates computed with fluorescence-corrected float measurements are statistically indistinguishable from those extrapolated from satellite observations. These effects are reversed in the subtropics: discrepancies due to fluorescence compensate vertically and annually, whereas annual iNPP estimates from depth-resolved float measurements significantly outweigh those of satellites. Seasonal changes to the sign, timing, and vertical structure of NPP discrepancies suggest persistent sub-seasonal disagreement between platforms, highlighting knowledge gaps in understanding NPP.</p>","PeriodicalId":12729,"journal":{"name":"Global Biogeochemical Cycles","volume":"40 8","pages":""},"PeriodicalIF":6.9,"publicationDate":"2026-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2025GB008952","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148753177","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":"Responses of Riverine Dissolved Organic Carbon to Global Warming and Permafrost Thaw on the Tibetan Plateau","authors":"Yiru Pan,&nbsp;Yi Zhao,&nbsp;Shang Tian,&nbsp;Yichu Wang,&nbsp;Li Yuan,&nbsp;Dongfeng Li","doi":"10.1029/2026GB009157","DOIUrl":"https://doi.org/10.1029/2026GB009157","url":null,"abstract":"<p>Riverine dissolved organic carbon (DOC) plays a vital role in the global carbon cycle, but its spatiotemporal dynamics and controlling mechanisms in alpine permafrost regions remain unclear. Here, by integrating a comprehensive in situ DOC data set, multi-source environmental variables, and machine learning approaches, we reconstruct the riverine DOC concentration (<i>C</i>_DOC) and flux (<i>F</i>_DOC) at five headwater rivers on the eastern Tibetan Plateau (TP) from 2000 to 2024 and investigate their spatiotemporal patterns. Results show that the mean <i>C</i>_DOC across the five rivers is 3.27 ± 0.96 mg/L but remains highly heterogeneous, with higher values observed in the permafrost-dominated headwaters of the Yellow (4.31 ± 0.78 mg/L) and Yangtze Rivers (3.39 ± 0.86 mg/L). The permafrost coverage, soil organic carbon content, and vegetation type shape this spatial pattern. The southeastern rivers (Mekong and Salween Rivers) exhibit declining <i>C</i>_DOC over the past 25 years, primarily driven by soil moisture reduction under climate warming. In contrast, significant <i>C</i>_DOC increases are detected in Yellow (+0.073 mg L⁻¹ decade⁻¹) and Yangtze headwaters (+0.029 mg L⁻¹ decade⁻¹), due to the enhanced vegetation conditions associated with climate warming and permafrost thaw. Total <i>F</i>_DOC at the outlets of major rivers increases markedly, reaching approximately 1.37 Tg yr⁻¹ in response to the rising river discharge. This study presents the spatiotemporal dynamics of DOC across TP rivers, elucidates the underlying mechanisms, and provides a basis for land-river carbon transfer and regional carbon budget assessments in high-elevation permafrost environments.</p>","PeriodicalId":12729,"journal":{"name":"Global Biogeochemical Cycles","volume":"40 8","pages":""},"PeriodicalIF":6.9,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148647704","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":"Compound Effects of Warming and Wetting Enhance Soil Respiration on the Earth's Third Pole","authors":"Tongqing Shen,&nbsp;Junliang Jin,&nbsp;Xiaohua Wei,&nbsp;Qin Ju,&nbsp;Guoqing Wang,&nbsp;Yanli Liu,&nbsp;Hui Lin,&nbsp;Shixuan Lyu,&nbsp;Meirong Sun,&nbsp;Changjun Zhu,&nbsp;Jianyun Zhang","doi":"10.1029/2026GB009376","DOIUrl":"https://doi.org/10.1029/2026GB009376","url":null,"abstract":"<p>The temperature sensitivity (<i>Q</i>₁₀) of soil respiration (<i>Rs</i>) is one of the major determinants of carbon emissions from <i>Rs</i>. Identifying the controlling factors of <i>Q</i>₁₀ can contribute to quantifying the response of <i>Rs</i> to climate change and assessing potential carbon emission risks. The Tibetan Plateau (TP), known as the Earth's third pole, plays a pivotal role in the global climate and carbon cycle system. However, the controlling factors of <i>Q</i>₁₀ and its responses to future climate change in this region are not well understood. Here, we introduce a method for calculating <i>Q</i>₁₀ from cumulative carbon emission data on <i>Rs</i>, which allows substantially expanding the available data set. Building on this, we integrate various statistical analyses with explainable machine learning techniques to examine the controlling factors regulating <i>Q</i>₁₀ on the TP. Our analyses consistently show that precipitation and soil potential of Hydrogen are the two most important factors regulating <i>Q</i>₁₀. Precipitation is the dominant factor regulating <i>Q</i>₁₀ across nearly 70% of the plateau, while pH's dominance is about 30%, highlighting the primary role of precipitation as a regulator of <i>Q</i>₁₀ on the TP. Future precipitation increases (wetting) on the TP are predicted to markedly boost the warming-induced increase in <i>Rs</i>, with this effect being particularly pronounced in arid areas. Our findings clearly demonstrate that under future warming and wetting on the TP, the compound effects of precipitation and temperature would enhance <i>Rs</i>, consequently accelerating the soil organic carbon release.</p>","PeriodicalId":12729,"journal":{"name":"Global Biogeochemical Cycles","volume":"40 8","pages":""},"PeriodicalIF":6.9,"publicationDate":"2026-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148617341","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":"Global Carbon Investment in Terrestrial Biological Nitrogen Fixation","authors":"Duncan N. L. Menge,&nbsp;Carla R. Reis Ely,&nbsp;Steven S. Perakis,&nbsp;Sian Kou-Giesbrecht,&nbsp;Cory C. Cleveland,&nbsp;Sasha C. Reed,&nbsp;Benton N. Taylor,&nbsp;Sarah A. Batterman,&nbsp;Timothy E. Crews,&nbsp;Katherine A. Dynarski,&nbsp;Jennifer L. Funk,&nbsp;Maga Gei,&nbsp;Kevin L. Griffin,&nbsp;Michael J. Gundale,&nbsp;David F. Herridge,&nbsp;Sarah E. Jovan,&nbsp;Mark B. Peoples,&nbsp;Johannes Piipponen,&nbsp;Emilio Rodríguez-Caballero,&nbsp;Verity G. Salmon,&nbsp;Fiona M. Soper,&nbsp;Anika P. Staccone,&nbsp;Bettina Weber,&nbsp;Amelia A. Wolf,&nbsp;Nina Wurzburger","doi":"10.1029/2026GB009098","DOIUrl":"https://doi.org/10.1029/2026GB009098","url":null,"abstract":"<p>Biological nitrogen (N) fixation (BNF) provides the N needed to produce proteins and other biological building blocks, helping feed humanity and mitigate climate change. Due to its high energetic cost compared to other forms of N acquisition, biotic investment in BNF indicates N limitation. Globally gridded BNF flux data provide an opportunity to determine the energetic investment in BNF across ecosystems, which would help reconcile conflicting indicators of N limitation. Here, we use a new BNF synthesis to quantify the relative importance of BNF in different N-fixing niches, in different biomes, and across the globe by calculating the fraction of net primary productivity (NPP) invested in BNF and the fraction of plant N acquisition provided by BNF. Larger fractions of non-agricultural NPP were invested in BNF in less-productive, higher-latitude biomes. This pattern was driven by biocrusts and mosses. Similarly, non-agricultural symbiotic N-fixing plants invested relatively more of their own NPP in BNF in less-productive, higher-latitude biomes. This symbiotic plant pattern was driven by shrubs and herbs, overriding the opposite pattern in trees. Symbiotic plants also acquired a higher fraction of their N from BNF at higher latitudes and in less productive biomes. Investments in symbiotic BNF were 10× higher in agricultural (2.9% of NPP) versus natural (0.29%) biomes, providing 26% versus 3.1% of ecosystem-scale plant N acquisition. These results support the paradigm of strong N limitation at higher latitudes, help understand the rarity of N-fixing trees at higher latitudes, underscore the dominance of human activity, and inform terrestrial biosphere models.</p>","PeriodicalId":12729,"journal":{"name":"Global Biogeochemical Cycles","volume":"40 8","pages":""},"PeriodicalIF":6.9,"publicationDate":"2026-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2026GB009098","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148617111","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":"The Global Biogeochemical Cycle of Antimony","authors":"Yuanzhi Yao,&nbsp;Feng Wang,&nbsp;Jipeng Xu,&nbsp;Qisheng Zeng,&nbsp;Lijun Hou,&nbsp;Rui Li","doi":"10.1029/2025GB009056","DOIUrl":"https://doi.org/10.1029/2025GB009056","url":null,"abstract":"<p>Antimony (Sb) has emerged as a global environmental concern due to its increasing anthropogenic release and its potential toxicity. This review synthesizes the global Sb biogeochemical cycle, quantifying both natural fluxes and profound anthropogenic perturbations. Natural Sb cycling is driven by rock weathering, atmospheric emissions (2.1 Gg·yr⁻¹), natural deposition, terrestrial vegetation turnover (∼5.64 Gg·yr⁻¹), and riverine export to oceans (37.4 ± 7.8 Gg·yr⁻¹). In the ocean, hydrothermal vents add ∼3.5 ± 2.4 Gg·yr⁻¹, while outputs occur via sediment burial and oceanic lithosphere subduction. Human activities now dominate the cycle, contributing ∼72% of total atmospheric inputs, and the total Sb emission (7.6 Gg·yr⁻¹) increased by 260% compared with the natural emission alone. Mining is the largest disturbance, releasing ∼48.68 Gg·yr⁻¹ into rivers and accumulating ∼66.8 Gg·yr⁻¹ in surrounding soils. Urban wastewater discharges and atmospheric deposition via runoff further contribute to aquatic systems. An estimated total marine input of ∼43.5 Gg·yr⁻¹ slightly exceeds outputs (∼40.5 Gg·yr⁻¹), indicating a human-induced imbalance in the global Sb cycle. Significant uncertainties remain due to scarce emission factors and regional variability, highlighting the need for more precise data to inform sustainable resource management and pollution control strategies.</p>","PeriodicalId":12729,"journal":{"name":"Global Biogeochemical Cycles","volume":"40 7","pages":""},"PeriodicalIF":6.9,"publicationDate":"2026-07-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148616039","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":"Special Collection on Fjords as Aquatic Critical Zones on the Front Lines of Global Change","authors":"Thomas S. Bianchi,&nbsp;Alexander B. Michaud,&nbsp;Candida Savage,&nbsp;Craig Smeaton,&nbsp;Laura M. Wehrmann","doi":"10.1029/2026GB009314","DOIUrl":"https://doi.org/10.1029/2026GB009314","url":null,"abstract":"<p>In this special collection, new studies reveal that fjords serve as vital estuarine transition zones between terrestrial ecosystems and the open ocean. Primarily found at high latitudes, fjords are highly sensitive to climate change, which fundamentally reshapes their land and marine inputs. As glaciers retreat, the influx of freshwater, nutrients, and sediments shifts, altering the chemical and biological makeup of fjord waters. While glaciers currently drive the upwelling of nutrient-rich waters that support primary productivity, glacial retreat onto land may increase stratification and shift ecosystems toward microbial dominance. Fjords also play a critical role in the global climate system as disproportionate hotspots for organic carbon burial. However, warming and melting permafrost threaten to remobilize this stored carbon, potentially changing fjords from carbon sinks into sources of CO₂ emissions. Because of these complex and interacting stressors, fjords are increasingly viewed as “Aquatic Critical Zones” that require urgent interdisciplinary research and management.</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/10.1029/2026GB009314","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148615883","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}