Global Biogeochemical Cycles最新文献

{"title":"Incubation Experiments Characterize Turbid Glacier Plumes as a Major Source of Mn and Co, and a Minor Source of Fe and Si, to Seawater","authors":"Xunchi Zhu,&nbsp;Mark J. Hopwood,&nbsp;Katja Laufer-Meiser,&nbsp;Eric P. Achterberg","doi":"10.1029/2024GB008144","DOIUrl":"https://doi.org/10.1029/2024GB008144","url":null,"abstract":"<p>Glaciers are a source of fine-ground rock flour to proglacial and coastal marine environments. In these environments, suspended rock flour may affect light and (micro)nutrient availability to primary producers. Due to high loads of glacier rock flour, the particulate metal load of glacier runoff typically exceeds the dissolved metal load. As glacier rock flour is deposited in downstream environments, short-term exchange between particulate and dissolved metal phases may have a moderating influence on dissolved metal concentrations. Here we compare the behavior of iron (Fe), manganese (Mn), cobalt (Co) and silica (Si) following the addition of different glacier-derived sediments into seawater under conditions of varying sediment load (20–500 mg L⁻¹), time (0.5 hr–21 days), temperature (4–11°C) and light exposure (dark/2,500 Lux). Despite a moderately high labile Fe content across all particle types (0.28–3.50 mg Fe g⁻¹ of dry sediment), only 0.27–7.13 μg Fe g⁻¹ was released into seawater, with less efficient release as sediment load increased. Conversely, Si, Mn, and Co exhibited a more constant rate of release, which was less sensitive to sediment load. Dissolved Si release was equivalent to 17% ± 22% of particulate amorphous Si after 1–2 weeks. Dissolved Mn concentrations in most incubations exceeded dissolved Fe concentrations within 1 hr despite labile Mn content being 12-fold lower than labile Fe content. Our results show the potential for glacier-derived particles to be a large source of Mn and Co to marine waters and add to the growing evidence that Mn may be the bio-essential metal most affected by glacier-associated sources.</p>","PeriodicalId":12729,"journal":{"name":"Global Biogeochemical Cycles","volume":"38 10","pages":""},"PeriodicalIF":5.4,"publicationDate":"2024-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024GB008144","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142404686","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":"Bacterial Community Structure Modulates Soil Phosphorus Turnover at Early Stages of Primary Succession","authors":"Yuhan Wang,&nbsp;Haijian Bing,&nbsp;Daryl L. Moorhead,&nbsp;Enqing Hou,&nbsp;Yanhong Wu,&nbsp;Jipeng Wang,&nbsp;Chengjiao Duan,&nbsp;Qingliang Cui,&nbsp;Zhiqin Zhang,&nbsp;He Zhu,&nbsp;Tianyi Qiu,&nbsp;Zhongmin Dai,&nbsp;Wenfeng Tan,&nbsp;Min Huang,&nbsp;Hans Lambers,&nbsp;Peter B. Reich,&nbsp;Linchuan Fang","doi":"10.1029/2024GB008174","DOIUrl":"https://doi.org/10.1029/2024GB008174","url":null,"abstract":"<p>Microbes are the drivers of soil phosphorus (P) cycling in terrestrial ecosystems; however, the role of soil microbes in mediating P cycling in P-rich soils during primary succession remains uncertain. This study examined the impacts of bacterial community structure (diversity and composition) and its functional potential (absolute abundances of P-cycling functional genes) on soil P cycling along a 130-year glacial chronosequence on the eastern Tibetan Plateau. Bacterial community structure was a better predictor of soil P fractions than P-cycling genes along the chronosequence. After glacier retreat, the solubilization of inorganic P and the mineralization of organic P were significantly enhanced by increased bacterial diversity, changed interspecific interactions, and abundant species involved in soil P mineralization, thereby increasing P availability. Although 84% of P-cycling genes were associated with organic P mineralization, these genes were more closely associated with soil organic carbon than with organic P. Bacterial carbon demand probably determined soil P turnover, indicating the dominant role of organic matter decomposition processes in P-rich alpine soils. Moreover, the significant decrease in the complexity of the bacterial co-occurrence network and the taxa-gene-P network at the later stage indicates a declining dominance of the bacterial community in driving soil P cycling with succession. Our results reveal that bacteria with a complex community structure have a prominent potential for biogeochemical P cycling in P-rich soils during the early stages of primary succession.</p>","PeriodicalId":12729,"journal":{"name":"Global Biogeochemical Cycles","volume":"38 10","pages":""},"PeriodicalIF":5.4,"publicationDate":"2024-10-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142404367","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":"The Global Biogeochemical Cycle of Rhenium","authors":"L. Ghazi,&nbsp;K. E. Grant,&nbsp;A. Chappaz,&nbsp;M. Danish,&nbsp;B. Peucker-Ehrenbrink,&nbsp;J. C. Pett-Ridge","doi":"10.1029/2024GB008254","DOIUrl":"https://doi.org/10.1029/2024GB008254","url":null,"abstract":"<p>This paper is the first comprehensive synthesis of what is currently known about the different natural and anthropogenic fluxes of rhenium (Re) on Earth's surface. We highlight the significant role of anthropogenic mobilization of Re, which is an important consideration in utilizing Re in the context of a biogeochemical tracer or proxy. The largest natural flux of Re derives from chemical weathering and riverine transport to the ocean (dissolved = 62 × 10⁶ g yr⁻¹ and particulate = 5 × 10⁶ g yr⁻¹). This review reports a new global average [Re] of 16 ± 2 pmol L⁻¹, or 10 ± 1 pmol L⁻¹ for the inferred pre-anthropogenic concentration without human impact, for rivers draining to the ocean. Human activity via mining (including secondary mobilization), coal combustion, and petroleum combustion mobilize approximately 560 × 10⁶ g yr⁻¹ Re, which is more than any natural flux of Re. There are several poorly constrained fluxes of Re that merit further research, including: submarine groundwater discharge, precipitation (terrestrial and oceanic), magma degassing, and hydrothermal activity. The mechanisms and the main host phases responsible for releasing (sources) or sequestrating (sinks) these fluxes remain poorly understood. This study also highlights the use of dissolved [Re] concentrations as a tracer of oxidation of petrogenic organic carbon, and stable Re isotopes as proxies for changes in global redox conditions.</p>","PeriodicalId":12729,"journal":{"name":"Global Biogeochemical Cycles","volume":"38 10","pages":""},"PeriodicalIF":5.4,"publicationDate":"2024-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142404469","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":"Soil Carbon Accumulation Under Afforestation Is Driven by Contrasting Responses of Particulate and Mineral-Associated Organic Carbon","authors":"Deping Zhai,&nbsp;Yiyue Wang,&nbsp;Chang Liao,&nbsp;Xiuxian Men,&nbsp;Chi Wang,&nbsp;Xiaoli Cheng","doi":"10.1029/2024GB008116","DOIUrl":"https://doi.org/10.1029/2024GB008116","url":null,"abstract":"<p>Afforestation is widely believed to sequester carbon (C) in soil. However, the effect of afforestation on soil organic C (SOC) accumulation is still debated due to the contrasting features of particulate and mineral-associated organic C (POC and MAOC). We conducted a field investigation of 144 paired sampling sites by comparing afforested and non-afforested lands to investigate the POC and MAOC dynamics after afforestation across the Danjiangkou basin in subtropical China, where forests are dominated by <i>Platycladus orientalis</i>, <i>Quercus variabilis</i> and <i>Pinus massoniana</i>. The average contents of SOC, POC, and MAOC were significantly increased by afforestation; however, POC and MAOC responded differently to afforestation type. All afforestation types promoted the POC content, and MAOC also showed positive responses to afforestation except that afforestation with <i>P</i>. <i>massoniana</i> from shrubland significantly reduced the MAOC content. With increasing SOC content, the POC grew at a faster rate than MAOC at high SOC levels. Afforestation hindered the growth rate of POC, while it promoted the growth rate of MAOC as SOC accrued, which potentially obscured the distinct patterns of C accumulation triggered by afforestation. The variation partitioning suggests that, under afforestation, microbial traits had a higher contribution to both POC and MAOM variations compared with non-afforested land. These results suggest that the robust buildup of microbial biomass due to increased plant C input following afforestation could contribute to soil C accumulation by promoting microbial necromass.</p>","PeriodicalId":12729,"journal":{"name":"Global Biogeochemical Cycles","volume":"38 10","pages":""},"PeriodicalIF":5.4,"publicationDate":"2024-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142404472","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 Estimates of Particulate Organic Carbon Concentration From the Surface Ocean to the Base of the Mesopelagic","authors":"James Fox,&nbsp;Michael J. Behrenfeld,&nbsp;Kimberly H. Halsey,&nbsp;Jason R. Graff","doi":"10.1029/2024GB008149","DOIUrl":"https://doi.org/10.1029/2024GB008149","url":null,"abstract":"<p>The gravitational settling of organic particles from the surface to the deep ocean is an important export pathway and one of the largest components of the ocean carbon pump. The strength and efficiency of the gravitational pump are often measured using metrics reliant on reference depths and empirical formulations that parameterize the relationship between depth and the flux or concentration of particulate organic carbon (POC). Here, BGC-Argo profiles were used to identify the isolume where POC concentration, [POC], starts to decline, revealing attenuation trends below this isolume that are remarkably consistent across the global ocean. We developed a simple empirical approach that uses observations from the first optical depth to predict [POC] from the surface ocean to the base of the mesopelagic (1,000 m), allowing assessments of spatial and temporal variability in gravitational pump efficiencies. We find that rates of [POC] attenuation are high in areas of high biomass and low in areas of low biomass, supporting the view that bloom events sometimes result in a relatively weak deep biological pump that is characterized by low transfer efficiency to the base of the mesopelagic. Our isolume-based attenuation model was applied to satellite data to yield the first remote sensing-based estimate of integrated global POC stock of 3.02 Pg C over the top 1,000 m, with an uncertainty of 0.69 Pg C. Of this total stock, approximately 1.02 Pg was located above the reference isolume where [POC] begins to attenuate.</p>","PeriodicalId":12729,"journal":{"name":"Global Biogeochemical Cycles","volume":"38 10","pages":""},"PeriodicalIF":5.4,"publicationDate":"2024-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024GB008149","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142404417","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":"Gradients of Deposition and In Situ Production Drive Global Glacier Organic Matter Composition","authors":"Amy D. Holt,&nbsp;Amy M. McKenna,&nbsp;Anne M. Kellerman,&nbsp;Tom I. Battin,&nbsp;Jason B. Fellman,&nbsp;Eran Hood,&nbsp;Hannes Peter,&nbsp;Martina Schön,&nbsp;Vincent De Staercke,&nbsp;Michail Styllas,&nbsp;Matteo Tolosano,&nbsp;Robert G. M. Spencer","doi":"10.1029/2024GB008212","DOIUrl":"https://doi.org/10.1029/2024GB008212","url":null,"abstract":"<p>Runoff from rapidly melting mountain glaciers is a dominant source of riverine organic carbon in many high-latitude and high-elevation regions. Glacier dissolved organic carbon is highly bioavailable, and its composition likely reflects internal (e.g., autotrophic production) and external (i.e., atmospheric deposition) sources. However, the balance of these sources across Earth's glaciers is poorly understood, despite implications for the mineralization and assimilation of glacier organic carbon within recipient ecosystems. We assessed the molecular-level composition of dissolved organic matter from 136 mountain glacier outflows from 11 regions covering six continents using ultrahigh resolution 21 T mass spectrometry. We found substantial diversity in organic matter composition with coherent and predictable (80% accuracy) regional patterns. Employing stable and radiocarbon isotopic analyses, we demonstrate that these patterns are inherently linked to atmospheric deposition and in situ production. In remote regions like Greenland and New Zealand, the glacier organic matter pool appears to be dominated by in situ production. However, downwind of industrial centers (e.g., Alaska and Nepal), fossil fuel combustion byproducts likely underpin organic matter composition, resulting in older and more aromatic material being exported downstream. These findings highlight that the glacier carbon cycle is spatially distinct, with ramifications for predicting the dynamics and fate of glacier organic carbon concurrent with continued retreat and anthropogenic perturbation.</p>","PeriodicalId":12729,"journal":{"name":"Global Biogeochemical Cycles","volume":"38 9","pages":""},"PeriodicalIF":5.4,"publicationDate":"2024-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142273084","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":"Simultaneous Hot and Dry Extreme-Events Increase Wetland Methane Emissions: An Assessment of Compound Extreme-Event Impacts Using Ameriflux and FLUXNET-CH4 Site Data Sets","authors":"T. J. R. Lippmann,&nbsp;Y. van der Velde,&nbsp;K. Naudts,&nbsp;G. Hensgens,&nbsp;J. E. Vonk,&nbsp;H. Dolman","doi":"10.1029/2024GB008201","DOIUrl":"https://doi.org/10.1029/2024GB008201","url":null,"abstract":"<p>Wetlands are the largest natural source of global atmospheric methane (CH₄). Despite advances to our understanding of changes in temperature and precipitation extremes, their impacts on carbon-rich ecosystems such as wetlands, remain significantly understudied. Here, we quantify the impacts of extreme temperature, precipitation, and dry events on wetland CH₄ dynamics by investigating the effects of both compound and discrete extreme-events. We use long-term climate data to identify extreme-events and 45 eddy covariance sites data sets sourced from the FLUXNET-CH₄ database and Ameriflux project to assess impacts on wetland CH₄ emissions. These findings reveal that compound hot + dry extreme-events lead to large increases in daily CH₄ emissions. However, per event, discrete dry-only extreme-events cause the largest total decrease in CH₄ emissions, due to their long duration. Despite dry-only extreme-events leading to an overall reduction in CH₄ emissions, enhanced fluxes are often observed for the first days of dry-only extreme-events. These effects differ depending on wetland type, where marsh sites tend to be sensitive to most types of extreme-events. Lagged impacts are significant for at least the 12 months following several types of extreme-events. These findings have implications for understanding how extreme-event impacts may evolve in the context of climate change, where changes in the frequency and intensity of temperature and precipitation extreme-events are already observed. With increasing occurrences of enhanced CH₄ fluxes in response to hot-only extreme-events and hot + wet extreme-events and fewer occurrences of reduced CH₄ fluxes during cold-only extreme-events, the impact of wetland CH₄ emissions on climate warming may be increasing.</p>","PeriodicalId":12729,"journal":{"name":"Global Biogeochemical Cycles","volume":"38 9","pages":""},"PeriodicalIF":5.4,"publicationDate":"2024-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024GB008201","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142233119","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 Changing Biological Carbon Pump of the South Atlantic Ocean","authors":"L. Delaigue,&nbsp;O. Sulpis,&nbsp;G.-J. Reichart,&nbsp;M. P. Humphreys","doi":"10.1029/2024GB008202","DOIUrl":"https://doi.org/10.1029/2024GB008202","url":null,"abstract":"<p>Global marine anthropogenic CO₂ inventories have traditionally emphasized the North Atlantic's role in the carbon cycle, while Southern hemisphere processes are less understood. The South Subtropical Convergence (SSTC) in the South Atlantic, a juncture of distinct nutrient-rich waters, offers a valuable study area for discerning the potential impacts of climate change on the ocean's biological carbon pump (C_soft). Using discrete observations from GLODAPv2.2022 and BGC-Argo at 40°S in the Atlantic Ocean from 1972 to 2023, an increase in dissolved inorganic carbon (DIC) of +1.44 ± 0.11 μmol kg⁻¹ yr⁻¹ in surface waters was observed. While anthropogenic CO₂ played a role, variations in the contribution of C_soft were observed. Discrepancies emerged in assessing C_soft based on the tracers employed: when using AOU, C_soft(AOU) recorded an increase of +0.20 ± 0.03 μmol kg⁻¹ yr⁻¹, while using nitrate as the reference, C_soft(NO3) displayed an increase of +0.85 ± 0.07 μmol kg⁻¹ yr⁻¹. Key processes such as water mass composition shifts, changes in oxygenation, remineralization in the Southern Ocean, and the challenges they pose in accurately representing the evolving C_soft are discussed. These findings highlight that while global studies primarily attribute DIC increase to anthropogenic CO₂, observations at 40°S reveal an intensified biological carbon pump, showing that regional DIC changes are more complex than previously thought and emphasizing the need for better parameterizations to compute the BCP in the marine carbon budget.</p>","PeriodicalId":12729,"journal":{"name":"Global Biogeochemical Cycles","volume":"38 9","pages":""},"PeriodicalIF":5.4,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024GB008202","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142174138","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":"Effects of Mesozooplankton Growth and Reproduction on Plankton and Organic Carbon Dynamics in a Marine Biogeochemical Model","authors":"Corentin Clerc,&nbsp;Laurent Bopp,&nbsp;Fabio Benedetti,&nbsp;Nielja Knecht,&nbsp;Meike Vogt,&nbsp;Olivier Aumont","doi":"10.1029/2024GB008153","DOIUrl":"https://doi.org/10.1029/2024GB008153","url":null,"abstract":"<p>Marine mesozooplankton play an important role for marine ecosystem functioning and global biogeochemical cycles. Their size structure, varying spatially and temporally, heavily impacts biogeochemical processes and ecosystem services. Mesozooplankton exhibit size changes throughout their life cycle, affecting metabolic rates and functional traits. Despite this variability, many models oversimplify mesozooplankton as a single, unchanging size class, potentially biasing carbon flux estimates. Here, we include mesozooplankton ontogenetic growth and reproduction into a 3-dimensional global ocean biogeochemical model, PISCES-MOG, and investigate the subsequent effects on simulated mesozooplankton phenology, plankton distribution, and organic carbon export. Utilizing an ensemble of statistical predictive models calibrated with a global set of observations, we generated monthly climatologies of mesozooplankton biomass to evaluate the simulations of PISCES-MOG. Our analyses reveal that the model and observation-based biomass distributions are consistent (<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mi>r</mi>\u0000 <mi>pearson</mi>\u0000 </msub>\u0000 </mrow>\u0000 <annotation> ${mathrm{r}}_{mathit{pearson}}$</annotation>\u0000 </semantics></math> = 0.40, total epipelagic biomass: 137 TgC from observations vs. 232 TgC in the model), with similar seasonality (later bloom as latitude increases poleward). Including ontogenetic growth in the model induced cohort dynamics and variable seasonal dynamics across mesozooplankton size classes and altered the relative contribution of carbon cycling pathways. Younger and smaller mesozooplankton transitioned to microzooplankton in PISCES-MOG, resulting in a change in particle size distribution, characterized by a decrease in large particulate organic carbon (POC) and an increase in small POC generation. Consequently, carbon export from the surface was reduced by 10%. This study underscores the importance of accounting for ontogenetic growth and reproduction in models, highlighting the interconnectedness between mesozooplankton size, phenology, and their effects on marine carbon cycling.</p>","PeriodicalId":12729,"journal":{"name":"Global Biogeochemical Cycles","volume":"38 9","pages":""},"PeriodicalIF":5.4,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024GB008153","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142165682","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":"Indian Ocean Acidification and Its Driving Mechanisms Over the Last Four Decades (1980–2019)","authors":"Kunal Chakraborty,&nbsp;A. P. Joshi,&nbsp;Prasanna Kanti Ghoshal,&nbsp;Balaji Baduru,&nbsp;Vinu Valsala,&nbsp;V. V. S. S. Sarma,&nbsp;Nicolas Metzl,&nbsp;Marion Gehlen,&nbsp;Frédéric Chevallier,&nbsp;Claire Lo Monaco","doi":"10.1029/2024GB008139","DOIUrl":"https://doi.org/10.1029/2024GB008139","url":null,"abstract":"<p>This paper aims to study the changes in the Indian Ocean seawater pH in response to the changes in sea-surface temperature, sea-surface salinity, dissolved inorganic carbon (DIC), and total alkalinity (ALK) over the period 1980–2019 and its driving mechanisms using a high-resolution regional model outputs. The analysis indicates that the rate of change of declining pH in the Arabian Sea (AS), the Bay of Bengal (BoB), and the Equatorial Indian Ocean (EIO) is −0.014 <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>±</mo>\u0000 </mrow>\u0000 <annotation> $pm $</annotation>\u0000 </semantics></math> 0.002, −0.014 <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>±</mo>\u0000 </mrow>\u0000 <annotation> $pm $</annotation>\u0000 </semantics></math> 0.001, and −0.015 <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>±</mo>\u0000 </mrow>\u0000 <annotation> $pm $</annotation>\u0000 </semantics></math> 0.001 unit dec⁻¹, respectively. Both in AS and BoB (EIO), the highest (lowest) decadal DIC trend is found during 2000–2009. The surface acidification rate has accelerated throughout the IO region during 2010–2019 compared to the previous decades. Further, our analysis indicates that El Ninõ and positive Indian Ocean Dipole events lead to an enhancement of the Indian Ocean acidification. The increasing anthropogenic CO₂ uptake by the ocean dominantly controls 80% (94.5% and 85.7%) of the net pH trend (1980–2019) in AS (BoB and EIO), whereas ocean warming controls 14.4% (13.4% and 7.0%) of pH trends in AS (BoB and EIO). The changes in ALK contribute to enhancing the pH trend of AS by 5.0%. ALK dominates after DIC in the EIO and, similar to the AS, contributes to increasing the negative pH trend by 10.7%. In contrast, it has a buffering effect in the BoB, suppressing the pH trend by −5.4%.</p>","PeriodicalId":12729,"journal":{"name":"Global Biogeochemical Cycles","volume":"38 9","pages":""},"PeriodicalIF":5.4,"publicationDate":"2024-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142152318","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}