Global Biogeochemical Cycles最新文献

{"title":"The Role of Coastal Yedoma Deposits and Continental Shelf Sediments in the Arctic Ocean Silicon Cycle","authors":"Nicholas E. Ray,&nbsp;Jannik Martens,&nbsp;Marco Ajmar,&nbsp;Tommaso Tesi,&nbsp;Evgeniy Yakushev,&nbsp;Ivan Gangnus,&nbsp;Jens Strauss,&nbsp;Lutz Schirrmeister,&nbsp;Igor Semiletov,&nbsp;Birgit Wild","doi":"10.1029/2023GB007746","DOIUrl":"https://doi.org/10.1029/2023GB007746","url":null,"abstract":"<p>The availability of silicon (Si) in the ocean plays an important role in regulating biogeochemical and ecological processes. The Si budget of the Arctic Ocean appears balanced, with inputs equivalent to outputs, though it is unclear how a changing climate might aggravate this balance. In this study, we focus on Si cycling in Arctic coastal areas and continental shelf sediments to better constrain the Arctic Ocean Si budget. We provide the first estimate of amorphous Si (ASi) loading from erosion of coastal Yedoma deposits (30–90 Gmol yr⁻¹), demonstrating comparable rates to particulate Si loading from rivers (10–90 Gmol yr⁻¹). We found a positive relationship between surface sediment ASi and organic matter content on continental shelves. Combining these values with published Arctic shelf sediment properties and burial rates we estimate 70 Gmol Si yr⁻¹ is buried on Arctic continental shelves, equivalent to 4.5% of all Si inputs to the Arctic Ocean. Sediment dissolved Si fluxes increased with distance from river mouths along cruise transects of shelf regions influenced by major rivers in the Laptev and East Siberian seas. On an annual basis, we estimate that Arctic shelf sediments recycle approximately up to twice as much DSi (680 Gmol Si) as is loaded from rivers (340–500 Gmol Si).</p>","PeriodicalId":12729,"journal":{"name":"Global Biogeochemical Cycles","volume":"38 1","pages":""},"PeriodicalIF":5.2,"publicationDate":"2024-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2023GB007746","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139406836","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":"Coral Reef Carbonate Chemistry Reveals Interannual, Seasonal, and Spatial Impacts on Ocean Acidification Off Florida","authors":"A. M. Palacio-Castro,&nbsp;I. C. Enochs,&nbsp;N. Besemer,&nbsp;A. Boyd,&nbsp;M. Jankulak,&nbsp;G. Kolodziej,&nbsp;H. K. Hirsh,&nbsp;A. E. Webb,&nbsp;E. K. Towle,&nbsp;C. Kelble,&nbsp;I. Smith,&nbsp;D. P. Manzello","doi":"10.1029/2023GB007789","DOIUrl":"https://doi.org/10.1029/2023GB007789","url":null,"abstract":"<p>Ocean acidification (OA) threatens coral reef persistence by decreasing calcification and accelerating the dissolution of reef frameworks. The carbonate chemistry of coastal areas where many reefs exist is strongly influenced by the metabolic activity of the underlying benthic community, contributing to high spatiotemporal variability. While characterizing this variability is difficult, it has important implications for the progression of OA and the persistence of the ecosystems. Here, we characterized the carbonate chemistry at 38 permanent stations located along 10 inshore-offshore transects spanning 250 km of the Florida Coral Reef (FCR), which encompass four major biogeographic regions (Biscayne Bay, Upper Keys, Middle Keys, and Lower Keys) and four shelf zones (inshore, mid-channel, offshore, and oceanic). Data have been collected since 2010, with approximately bi-monthly periodicity starting in 2015. Increasing OA, driven by increasing DIC, was detected in the mid-channel, offshore, and oceanic zones in every biogeographic region. In the inshore zone, however, increasing TA counteracted any measurable OA trend. Strong seasonal variability occurred at inshore sites and included periods of both exacerbated and mitigated OA. Seasonality was region-dependent, with greater variability in the Lower and Middle Keys. Elevated pH and aragonite saturation states (Ω_Ar) were observed in the Upper and Middle Keys, which could favor reef habitat persistence in these regions. Offshore reefs in the FCR could be more susceptible to global OA by experiencing open-ocean-like water chemistry conditions. By contrast, higher seasonal variability at inshore reefs could offer a temporary OA refuge during periods of enhanced primary production.</p>","PeriodicalId":12729,"journal":{"name":"Global Biogeochemical Cycles","volume":"37 12","pages":""},"PeriodicalIF":5.2,"publicationDate":"2023-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2023GB007789","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139047281","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":"Climatic Changes in North Atlantic O2 Amplified by Temperature Sensitivity of Phytoplankton Growth","authors":"A. Margolskee,&nbsp;T. Ito,&nbsp;M. Long,&nbsp;C. Deutsch","doi":"10.1029/2023GB007930","DOIUrl":"10.1029/2023GB007930","url":null,"abstract":"<p>Ocean warming is associated with a decline in the global oxygen (O₂) inventory, but the ratio of O₂ loss to heat gain is poorly understood. We analyzed historical variability in temperature (<i>T</i>), O₂, and nitrate <math>\u0000 <semantics>\u0000 <mrow>\u0000 <mfenced>\u0000 <mrow>\u0000 <mi>N</mi>\u0000 <msubsup>\u0000 <mi>O</mi>\u0000 <mn>3</mn>\u0000 <mo>−</mo>\u0000 </msubsup>\u0000 </mrow>\u0000 </mfenced>\u0000 </mrow>\u0000 <annotation> $left(mathrm{N}{mathrm{O}}_{3}^{-}right)$</annotation>\u0000 </semantics></math> in hydrographic observations and model simulations of the North Atlantic, a relatively well-sampled region that is important for deep ocean ventilation. Multidecadal fluctuations of O₂ concentrations in subpolar thermocline waters (100–700 m) are correlated with changes in their heat content, with a slope 35% steeper than that expected from thermal solubility. Variations of O₂ in excess of the solubility effect are correlated with observed decadal changes in <math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>N</mi>\u0000 <msubsup>\u0000 <mi>O</mi>\u0000 <mn>3</mn>\u0000 <mo>−</mo>\u0000 </msubsup>\u0000 </mrow>\u0000 <annotation> $mathrm{N}{mathrm{O}}_{3}^{-}$</annotation>\u0000 </semantics></math> in the surface layer (0–50 m), which declines by ∼1 mmol N m⁻³ per degree of temperature anomaly. Enhanced biologically mediated drawdown of nutrients from the photic zone and associated respiration in deeper water account for the additional depletion of thermocline O₂ during warm years. In model simulations, increased nutrient consumption in warm periods is driven by an early start of the phytoplankton growing season and faster phytoplankton growth rates at higher temperatures. Our results highlight a role for phytoplankton <i>T</i>-dependent growth rates in amplifying ocean O₂ loss.</p>","PeriodicalId":12729,"journal":{"name":"Global Biogeochemical Cycles","volume":"37 12","pages":""},"PeriodicalIF":5.2,"publicationDate":"2023-12-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2023GB007930","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139029916","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":"Neutral Tropical African CO2 Exchange Estimated From Aircraft and Satellite Observations","authors":"Benjamin Gaubert,&nbsp;Britton B. Stephens,&nbsp;David F. Baker,&nbsp;Sourish Basu,&nbsp;Michael Bertolacci,&nbsp;Kevin W. Bowman,&nbsp;Rebecca Buchholz,&nbsp;Abhishek Chatterjee,&nbsp;Frédéric Chevallier,&nbsp;Róisín Commane,&nbsp;Noel Cressie,&nbsp;Feng Deng,&nbsp;Nicole Jacobs,&nbsp;Matthew S. Johnson,&nbsp;Shamil S. Maksyutov,&nbsp;Kathryn McKain,&nbsp;Junjie Liu,&nbsp;Zhiqiang Liu,&nbsp;Eric Morgan,&nbsp;Chris O’Dell,&nbsp;Sajeev Philip,&nbsp;Eric Ray,&nbsp;David Schimel,&nbsp;Andrew Schuh,&nbsp;Thomas E. Taylor,&nbsp;Brad Weir,&nbsp;Dave van Wees,&nbsp;Steven C. Wofsy,&nbsp;Andrew Zammit-Mangion,&nbsp;Ning Zeng","doi":"10.1029/2023GB007804","DOIUrl":"10.1029/2023GB007804","url":null,"abstract":"<p>Tropical lands play an important role in the global carbon cycle yet their contribution remains uncertain owing to sparse observations. Satellite observations of atmospheric carbon dioxide (CO₂) have greatly increased spatial coverage over tropical regions, providing the potential for improved estimates of terrestrial fluxes. Despite this advancement, the spread among satellite-based and in-situ atmospheric CO₂ flux inversions over northern tropical Africa (NTA), spanning 0–24°N, remains large. Satellite-based estimates of an annual source of 0.8–1.45 PgC yr⁻¹ challenge our understanding of tropical and global carbon cycling. Here, we compare posterior mole fractions from the suite of inversions participating in the Orbiting Carbon Observatory 2 (OCO-2) Version 10 Model Intercomparison Project (v10 MIP) with independent in-situ airborne observations made over the tropical Atlantic Ocean by the National Aeronautics and Space Administration (NASA) Atmospheric Tomography (ATom) mission during four seasons. We develop emergent constraints on tropical African CO₂ fluxes using flux-concentration relationships defined by the model suite. We find an annual flux of 0.14 ± 0.39 PgC yr⁻¹ (mean and standard deviation) for NTA, 2016–2018. The satellite-based flux bias suggests a potential positive concentration bias in OCO-2 B10 and earlier version retrievals over land in NTA during the dry season. Nevertheless, the OCO-2 observations provide improved flux estimates relative to the in situ observing network at other times of year, indicating stronger uptake in NTA during the wet season than the in-situ inversion estimates.</p>","PeriodicalId":12729,"journal":{"name":"Global Biogeochemical Cycles","volume":"37 12","pages":""},"PeriodicalIF":5.2,"publicationDate":"2023-12-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138987208","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":"Water Stress Dominates 21st-Century Tropical Land Carbon Uptake","authors":"Paul A. Levine,&nbsp;A. Anthony Bloom,&nbsp;Kevin W. Bowman,&nbsp;John T. Reager,&nbsp;John R. Worden,&nbsp;Junjie Liu,&nbsp;Nicholas C. Parazoo,&nbsp;Victoria Meyer,&nbsp;Alexandra G. Konings,&nbsp;Marcos Longo","doi":"10.1029/2023GB007702","DOIUrl":"10.1029/2023GB007702","url":null,"abstract":"<p>Water stress regulates land-atmosphere carbon dioxide (CO₂) exchanges in the tropics; however, its role remains poorly characterized due to the confounding roles of radiation, temperature and canopy dynamics. In particular, uncertainty stems from the relative roles of plant-available water (supply) and atmospheric water vapor deficit (demand) as mechanistic drivers of photosynthetic carbon (C) uptake variability. Using satellite measurements of gravity, CO₂ and fluorescence to constrain a mechanistic carbon-water cycle model from 2001 to 2018, we found that the interannual variability (IAV) of water stress on photosynthetic C uptake was 52% greater than the combined effects of other factors. Surprisingly, the dominance of water stress on C uptake IAV was greater in the wet tropics (94%) than in the dry tropics (26%). Plant-available water supply and atmospheric demand both contributed to the IAV of water stress on photosynthetic C uptake across the tropics, but the IAV of demand effects was 21% greater than the IAV of supply effects (33% greater in the wet tropics and 6% greater in the dry tropics). We found that the IAV of water stress on C uptake was 24% greater than the IAV of the combination of other factors in the net land-atmosphere C sink in the whole tropics, 26% greater in the wet tropics, and 7% greater in the dry tropics. Given the recent trends in tropical precipitation and atmospheric humidity, our findings indicate that water stress——from both supply and demand——will likely dominate the climate response of land C sink across tropical ecosystems in the coming decades.</p>","PeriodicalId":12729,"journal":{"name":"Global Biogeochemical Cycles","volume":"37 12","pages":""},"PeriodicalIF":5.2,"publicationDate":"2023-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2023GB007702","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138822405","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":"Isotope Constraints on Nitrate Exchanges Between Precipitation and Forest Canopy","authors":"Xue-Yan Liu,&nbsp;Mei-Na Liu,&nbsp;Wan-Xiao Qin,&nbsp;Wei Song","doi":"10.1029/2023GB007920","DOIUrl":"https://doi.org/10.1029/2023GB007920","url":null,"abstract":"&lt;p&gt;Atmospheric nitrogen (N) deposition is a key process influencing plant-soil N processes and associated functions of forest ecosystems. However, the N deposition into soils based on open-field precipitation observations remains inaccurate due to the unconstrained precipitation-canopy N exchanges, which prevents a better evaluation of N deposition effects on forest N cycles and functions. Nitrate (&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msup&gt;\u0000 &lt;msub&gt;\u0000 &lt;mtext&gt;NO&lt;/mtext&gt;\u0000 &lt;mn&gt;3&lt;/mn&gt;\u0000 &lt;/msub&gt;\u0000 &lt;mo&gt;−&lt;/mo&gt;\u0000 &lt;/msup&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${{text{NO}}_{3}}^{-}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;) is a major form of reactive N. Based on a data synthesis of fluxes and isotopes (&lt;sup&gt;15&lt;/sup&gt;N, &lt;sup&gt;17&lt;/sup&gt;O, &lt;sup&gt;18&lt;/sup&gt;O) of atmospheric &lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msup&gt;\u0000 &lt;msub&gt;\u0000 &lt;mtext&gt;NO&lt;/mtext&gt;\u0000 &lt;mn&gt;3&lt;/mn&gt;\u0000 &lt;/msub&gt;\u0000 &lt;mo&gt;−&lt;/mo&gt;\u0000 &lt;/msup&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${{text{NO}}_{3}}^{-}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; inputs in forests, here we constructed a new method to quantify fractions and fluxes of throughfall &lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msup&gt;\u0000 &lt;msub&gt;\u0000 &lt;mtext&gt;NO&lt;/mtext&gt;\u0000 &lt;mn&gt;3&lt;/mn&gt;\u0000 &lt;/msub&gt;\u0000 &lt;mo&gt;−&lt;/mo&gt;\u0000 &lt;/msup&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${{text{NO}}_{3}}^{-}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; (&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;t&lt;/mi&gt;\u0000 &lt;mo&gt;-&lt;/mo&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;msup&gt;\u0000 &lt;msub&gt;\u0000 &lt;mtext&gt;NO&lt;/mtext&gt;\u0000 &lt;mn&gt;3&lt;/mn&gt;\u0000 &lt;/msub&gt;\u0000 &lt;mo&gt;−&lt;/mo&gt;\u0000 &lt;/msup&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; $mathrm{t}mbox{-}{{text{NO}}_{3}}^{-}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;) contributors (nitrification (&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;n&lt;/mi&gt;\u0000 &lt;mo&gt;-&lt;/mo&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;msup&gt;\u0000 &lt;msub&gt;\u0000 &lt;mtext&gt;NO&lt;/mtext&gt;\u0000 &lt;mn&gt;3&lt;/mn&gt;\u0000 &lt;/msub&gt;\u0000 &lt;mo&gt;−&lt;/mo&gt;\u0000 &lt;/msup&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; $mathrm{n}mbox{-}{{text{NO}}_{3}}^{-}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;) and particulates (&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mrow&gt;\u0000 ","PeriodicalId":12729,"journal":{"name":"Global Biogeochemical Cycles","volume":"37 12","pages":""},"PeriodicalIF":5.2,"publicationDate":"2023-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138678900","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":"Authigenic Iron Is a Significant Component of Oceanic Labile Particulate Iron Inventories","authors":"Laura E. Sofen,&nbsp;Olga A. Antipova,&nbsp;Kristen N. Buck,&nbsp;Salvatore Caprara,&nbsp;Lauren Chacho,&nbsp;Rodney J. Johnson,&nbsp;Gabriella Kim,&nbsp;Peter Morton,&nbsp;Daniel C. Ohnemus,&nbsp;Sara Rauschenberg,&nbsp;Peter N. Sedwick,&nbsp;Alessandro Tagliabue,&nbsp;Benjamin S. Twining","doi":"10.1029/2023GB007837","DOIUrl":"10.1029/2023GB007837","url":null,"abstract":"<p>Particulate phases transport trace metals (TM) and thereby exert a major control on TM distribution in the ocean. Particulate TMs can be classified by their origin as lithogenic (crustal material), biogenic (cellular), or authigenic (formed in situ), but distinguishing these fractions analytically in field samples is a challenge often addressed using operational definitions and assumptions. These different phases require accurate characterization because they have distinct roles in the biogeochemical iron cycle. Particles collected from the upper 2,000 m of the northwest subtropical Atlantic Ocean over four seasonal cruises throughout 2019 were digested with a chemical leach to operationally distinguish labile particulate material from refractory lithogenics. Direct measurements of cellular iron (Fe) were used to calculate the biogenic contribution to the labile Fe fraction, and any remaining labile material was defined as authigenic. Total particulate Fe (PFe) inventories varied &lt;15% between seasons despite strong seasonality in dust inputs. Across seasons, the total PFe inventory (±1SD) was composed of 73 ± 13% lithogenic, 18 ± 7% authigenic, and 10 ± 8% biogenic Fe above the deep chlorophyll maximum (DCM), and 69 ± 8% lithogenic, 30 ± 8% authigenic, and 1.1 ± 0.5% biogenic Fe below the DCM. Data from three other ocean regions further reveal the importance of the authigenic fraction across broad productivity and Fe gradients, comprising ca. 20%–27% of total PFe.</p>","PeriodicalId":12729,"journal":{"name":"Global Biogeochemical Cycles","volume":"37 12","pages":""},"PeriodicalIF":5.2,"publicationDate":"2023-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2023GB007837","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138630932","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":"A Comprehensive Assessment of Anthropogenic and Natural Sources and Sinks of Australasia's Carbon Budget","authors":"Yohanna Villalobos,&nbsp;Josep G. Canadell,&nbsp;Elizabeth D. Keller,&nbsp;Peter R. Briggs,&nbsp;Beata Bukosa,&nbsp;Donna L. Giltrap,&nbsp;Ian Harman,&nbsp;Timothy W. Hilton,&nbsp;Miko U. F. Kirschbaum,&nbsp;Ronny Lauerwald,&nbsp;Liyin L. Liang,&nbsp;Taylor Maavara,&nbsp;Sara E. Mikaloff-Fletcher,&nbsp;Peter J. Rayner,&nbsp;Laure Resplandy,&nbsp;Judith Rosentreter,&nbsp;Eva-Marie Metz,&nbsp;Oscar Serrano,&nbsp;Benjamin Smith","doi":"10.1029/2023GB007845","DOIUrl":"https://doi.org/10.1029/2023GB007845","url":null,"abstract":"<p>Regional carbon budget assessments attribute and track changes in carbon sources and sinks and support the development and monitoring the efficacy of climate policies. We present a comprehensive assessment of the natural and anthropogenic carbon (C-CO₂) fluxes for Australasia as a whole, as well as for Australia and New Zealand individually, for the period from 2010 to 2019, using two approaches: bottom-up methods that integrate flux estimates from land-surface models, data-driven models, and inventory estimates; and top-down atmospheric inversions based on satellite and in situ measurements. Our bottom-up decadal assessment suggests that Australasia's net carbon balance was close to carbon neutral (−0.4 ± 77.0 TgC yr⁻¹). However, substantial uncertainties remain in this estimate, primarily driven by the large spread between our regional terrestrial biosphere simulations and predictions from global ecosystem models. Within Australasia, Australia was a net source of 38.2 ± 75.8 TgC yr⁻¹, and New Zealand was a net CO₂ sink of −38.6 ± 13.4 TgC yr⁻¹. The top-down approach using atmospheric CO₂ inversions indicates that fluxes derived from the latest satellite retrievals are consistent within the range of uncertainties with Australia's bottom-up budget. For New Zealand, the best agreement was found with a national scale flux inversion estimate based on in situ measurements, which provide better constrained of fluxes than satellite flux inversions. This study marks an important step toward a more comprehensive understanding of the net CO₂ balance in both countries, facilitating the improvement of carbon accounting approaches and strategies to reduce emissions.</p>","PeriodicalId":12729,"journal":{"name":"Global Biogeochemical Cycles","volume":"37 12","pages":""},"PeriodicalIF":5.2,"publicationDate":"2023-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2023GB007845","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138550438","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":"Transport of Anthropogenic Carbon From the Antarctic Shelf to Deep Southern Ocean Triggers Acidification","authors":"Shuang Zhang,&nbsp;Yingxu Wu,&nbsp;Wei-Jun Cai,&nbsp;Wenju Cai,&nbsp;Richard A. Feely,&nbsp;Zhaomin Wang,&nbsp;Toste Tanhua,&nbsp;Yanmin Wang,&nbsp;Chengyan Liu,&nbsp;Xichen Li,&nbsp;Qinghua Yang,&nbsp;Minghu Ding,&nbsp;Zhongsheng Xu,&nbsp;Rodrigo Kerr,&nbsp;Yiming Luo,&nbsp;Xiao Cheng,&nbsp;Liqi Chen,&nbsp;Di Qi","doi":"10.1029/2023GB007921","DOIUrl":"https://doi.org/10.1029/2023GB007921","url":null,"abstract":"<p>Flow of dense shelf water provide an efficient mechanism for pumping CO₂ to the deep ocean along the continental shelf slope, particularly around the Antarctic bottom water (AABW) formation areas where much of the global bottom water is formed. However, the contribution of the formation of AABW to sequestering anthropogenic carbon (<i>C</i>_ant) and its consequences remain unclear. Here, we show prominent transport of <i>C</i>_ant (25.0 ± 4.7 Tg C yr⁻¹) into the deep ocean (&gt;2,000 m) in four AABW formation regions around Antarctica based on an integrated observational data set (1974–2018). This maintains a lower <i>C</i>_ant in the upper waters than that of other open oceans to sustain a stronger CO₂ uptake capacity (16.9 ± 3.8 Tg C yr⁻¹). Nevertheless, the accumulation of <i>C</i>_ant can further trigger acidification of AABW at a rate of −0.0006 ± 0.0001 pH unit yr⁻¹. Our findings elucidate the prominent role of AABW in controlling the Southern Ocean carbon uptake and storage to mitigate climate change, whereas its side effects (e.g., acidification) could also spread to other ocean basins via the global ocean conveyor belt.</p>","PeriodicalId":12729,"journal":{"name":"Global Biogeochemical Cycles","volume":"37 12","pages":""},"PeriodicalIF":5.2,"publicationDate":"2023-12-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138502720","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":"Isoprene Production and Its Driving Factors in the Northwest Pacific Ocean","authors":"Jian Wang,&nbsp;Hong-Hai Zhang,&nbsp;Dennis Booge,&nbsp;Yue-Qi Zhang,&nbsp;Xiao-Jun Li,&nbsp;Ying-Cui Wu,&nbsp;Jia-Wei Zhang,&nbsp;Zhao-Hui Chen","doi":"10.1029/2023GB007841","DOIUrl":"https://doi.org/10.1029/2023GB007841","url":null,"abstract":"<p>Marine isoprene plays a crucial role in the formation of secondary organic aerosol within the remote marine boundary layer. Due to scarce field measurements of oceanic isoprene and limited laboratory-based studies of isoprene production, assessing the importance of marine isoprene on atmospheric chemistry and climate is challenging. Calculating in-field isoprene production rates is a crucial step to predict marine isoprene concentrations and the subsequent emissions to the atmosphere. The distribution, sources, and dominant environmental factors of isoprene were determined in the Northwest Pacific Ocean in 2019. The nutrient enrichment in the Kuroshio Oyashio Extension (KOE) surface seawater, driven by the upwelling and atmospheric deposition, promoted the growth of phytoplankton and elevated the isoprene concentration. This was confirmed by observed responses of isoprene to nutrients and aerosol dust additions in a ship-based incubation experiment, where the isoprene concentrations increased by 70% (<i>t</i> = 4.417, <i>p</i> &lt; 0.001) and 35% (<i>t</i> = 2.387, <i>p</i> &lt; 0.05), respectively. Biogenic isoprene production rates in the deck incubation experiments were positively related to chlorophyll <i>a</i>, temperature, and solar radiation, with an average production of 7.33 ± 4.27 pmol L⁻¹ day⁻¹. Photochemical degradation of dissolved organic matter was likely an abiotic source of isoprene, contributing to approximately 14% of the total production. Driven by high isoprene production and extreme physical disturbance, the KOE showed very high emissions of isoprene of 46.0 ± 13.0 nmol m⁻² day⁻¹, which led to a significant influence on the oxidative capacity of the local atmosphere.</p>","PeriodicalId":12729,"journal":{"name":"Global Biogeochemical Cycles","volume":"37 12","pages":""},"PeriodicalIF":5.2,"publicationDate":"2023-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138485258","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}