Trace element analyses in brackish waters are challenging for many elements at ppb/ppt levels and analytical methods. In this work, we compare two methods using inductively coupled plasma mass spectrometry (ICP-MS) for quantifying antimony (Sb). Results of a previous study along the salinity gradient in a macrotidal estuary (i.e., the Gironde Estuary, France) using isotopic dilution via single quadrupole ICP-MS are compared to reanalyzed aliquots of the same samples. Direct analyses of estuarine water samples via standard additions (N = 52) were performed with a QQQ-ICP-MS (new generation, iCAP TQ Thermo®) to determine dissolved (< 0.2 μm filtered and UV-irradiated replicates) Sb concentrations during two contrasting hydrological conditions (low vs high freshwater discharges). Despite following good analytical practices on both studies, the use of the new analytical device provides more robust results and highlighted a characteristic 121Sb isotopic interference in estuarine samples at S > 20, efficiently eliminated by the QQQ-ICP-MS performance. This means that Sb reactivity shows an additive, non-conservative behavior in the Gironde Estuary, with a more defined bell-shaped profile in low discharge compared to high discharge conditions. This approach allows to quantify for the first time in the literature Sb dissolved net fluxes from the Gironde Estuary to the Atlantic coast and provides an updated value for the seawater endmember. This study opens future applications of QQQ-ICP-MS for quantifying on a more routine basis dissolved trace elements in brackish waters, providing guidelines and good practices for field studies regarding Sb determination in estuarine systems.
{"title":"Reactivity and fluxes of antimony in a macrotidal estuarine salinity gradient: Insights from single and triple quadrupole ICP-MS performances","authors":"Teba Gil-Díaz , Frédérique Pougnet , Lionel Dutruch , Jörg Schäfer , Alexandra Coynel","doi":"10.1016/j.marchem.2024.104465","DOIUrl":"10.1016/j.marchem.2024.104465","url":null,"abstract":"<div><div>Trace element analyses in brackish waters are challenging for many elements at ppb/ppt levels and analytical methods. In this work, we compare two methods using inductively coupled plasma mass spectrometry (ICP-MS) for quantifying antimony (Sb). Results of a previous study along the salinity gradient in a macrotidal estuary (i.e., the Gironde Estuary, France) using isotopic dilution via single quadrupole ICP-MS are compared to reanalyzed aliquots of the same samples. Direct analyses of estuarine water samples via standard additions (<em>N</em> = 52) were performed with a QQQ-ICP-MS (new generation, iCAP TQ Thermo®) to determine dissolved (< 0.2 μm filtered and UV-irradiated replicates) Sb concentrations during two contrasting hydrological conditions (low vs high freshwater discharges). Despite following good analytical practices on both studies, the use of the new analytical device provides more robust results and highlighted a characteristic <sup>121</sup>Sb isotopic interference in estuarine samples at S > 20, efficiently eliminated by the QQQ-ICP-MS performance. This means that Sb reactivity shows an additive, non-conservative behavior in the Gironde Estuary, with a more defined bell-shaped profile in low discharge compared to high discharge conditions. This approach allows to quantify for the first time in the literature Sb dissolved net fluxes from the Gironde Estuary to the Atlantic coast and provides an updated value for the seawater endmember. This study opens future applications of QQQ-ICP-MS for quantifying on a more routine basis dissolved trace elements in brackish waters, providing guidelines and good practices for field studies regarding Sb determination in estuarine systems.</div></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"267 ","pages":"Article 104465"},"PeriodicalIF":3.0,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142656455","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-01DOI: 10.1016/j.marchem.2024.104468
Archana Singh , Anand Jain , Richa Singh , Keisham S. Singh , Biswajit Roy , Manish Tiwari , Divya David T. , Ashok Jagtap
Arctic fjords are hotspot for organic matter (OM) transformation and storage, however, the composition and sources of the particulate organic matter (POM) are still not completely understood. Further, due to the ongoing enhancement in the glacier melting, runoff, and precipitation, the coastal Arctic is expecting considerable increase in POM inputs. Therefore, we investigated the biochemical composition of the POM through the application of stable isotopes, C:N ratio, and biomolecules, across different regions and depths in Kongsfjorden (Svalbard) during the late-summer. We observed that Kongsfjorden-POM was characterized by low δ13C (−29.0 to −26.7 ‰) with similar values at different locations (inner to outer) of the fjord at each depth. However, C:N ratio showed increasing trend (5.7 to 10.9) from outer to inner fjord indicating marine to terrestrial transition. Monosaccharide distribution (such as fucose, galactose, arabinose, xylose, ribose, and rhamnose) and their diagnostic ratios supported the marine versus terrestrial gradient in the POM characteristics in the surface water across the fjord. Only the outermost station showed consistent biochemical distribution indicative of phytoplanktonic sources in the POM, while the rest of the fjord showed mixed signatures of marine and terrestrial sources. Higher abundance of mannuronic acid (26.6–50.8 mol%) at the middle and bottom depths highlighted possible macroalgal contribution to the POM. The stratified surface water had a relatively higher (0.5–2 ‰) δ13C and carbohydrates (40–65 μg/L) than the middle and bottom depths, with a strong positive correlation between δ13C and particulate carbohydrates, indicating a stratification-induced distribution of POM. The study showed the importance of non-phytoplanktonic OM sources, such as terrestrial, freshwater and macroalgae POM in the fjord water column, and the fate of labile (carbohydrates) fraction that predominates in stratified surface waters. Therefore, the future warm and wet Arctic will most likely lead to changes in the fate of the organic matter in the fjord water.
{"title":"Tracing marine and terrestrial biochemical signatures of particulate organic matter in an Arctic fjord (Kongsfjorden)","authors":"Archana Singh , Anand Jain , Richa Singh , Keisham S. Singh , Biswajit Roy , Manish Tiwari , Divya David T. , Ashok Jagtap","doi":"10.1016/j.marchem.2024.104468","DOIUrl":"10.1016/j.marchem.2024.104468","url":null,"abstract":"<div><div>Arctic fjords are hotspot for organic matter (OM) transformation and storage, however, the composition and sources of the particulate organic matter (POM) are still not completely understood. Further, due to the ongoing enhancement in the glacier melting, runoff, and precipitation, the coastal Arctic is expecting considerable increase in POM inputs. Therefore, we investigated the biochemical composition of the POM through the application of stable isotopes, C:N ratio, and biomolecules, across different regions and depths in Kongsfjorden (Svalbard) during the late-summer. We observed that Kongsfjorden-POM was characterized by low δ<sup>13</sup>C (−29.0 to −26.7 ‰) with similar values at different locations (inner to outer) of the fjord at each depth. However, C:N ratio showed increasing trend (5.7 to 10.9) from outer to inner fjord indicating marine to terrestrial transition. Monosaccharide distribution (such as fucose, galactose, arabinose, xylose, ribose, and rhamnose) and their diagnostic ratios supported the marine versus terrestrial gradient in the POM characteristics in the surface water across the fjord. Only the outermost station showed consistent biochemical distribution indicative of phytoplanktonic sources in the POM, while the rest of the fjord showed mixed signatures of marine and terrestrial sources. Higher abundance of mannuronic acid (26.6–50.8 mol%) at the middle and bottom depths highlighted possible macroalgal contribution to the POM. The stratified surface water had a relatively higher (0.5–2 ‰) δ<sup>13</sup>C and carbohydrates (40–65 μg/L) than the middle and bottom depths, with a strong positive correlation between δ<sup>13</sup>C and particulate carbohydrates, indicating a stratification-induced distribution of POM. The study showed the importance of non-phytoplanktonic OM sources, such as terrestrial, freshwater and macroalgae POM in the fjord water column, and the fate of labile (carbohydrates) fraction that predominates in stratified surface waters. Therefore, the future warm and wet Arctic will most likely lead to changes in the fate of the organic matter in the fjord water.</div></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"267 ","pages":"Article 104468"},"PeriodicalIF":3.0,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142656457","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-01DOI: 10.1016/j.marchem.2024.104466
Jessalyn E. Davis , Rebecca S. Robinson , Emily R. Estes , Veronique E. Oldham , Evan A. Solomon , Roger P. Kelly , Katherine E. Bell , Joseph A. Resing , Randelle M. Bundy
Transport processes along the river-ocean continuum influence delivery of nutrients, carbon and trace metals from terrestrial systems to the marine environment, impacting coastal primary productivity and water quality. Although trace metal transformations have been studied extensively in the Mississippi River Delta region of the Northern Gulf of Mexico, investigations of manganese (Mn) and the presence of ligand-stabilized, dissolved manganese (Mn(III)-L) and its role in the transformation of trace elements and organic matter during riverine transport and estuarine mixing have not been considered. This study examined the chemical speciation of dissolved and particulate Mn in the water column and sediment porewaters in the Mississippi River and Northern Gulf of Mexico in March of 2021 to explore transformations in Mn speciation along the river-ocean continuum and the impact of different processes on the distribution of Mn. Total dissolved Mn concentrations were highest in the Mississippi River and decreased offshore, while Mn(III)-L contributed most to the dissolved Mn pool in near-shore waters. Porewater profiles indicated that ligand stabilization prevented dissolved Mn(III) reduction below the depth of oxygen penetration and in the presence of equimolar dissolved iron(II). Dissolved Mn(III)-L was enriched in bottom waters at all Northern Gulf of Mexico stations, and diffusive flux modelling of porewater dissolved Mn suggested that reducing sediments were a source of dissolved Mn to the overlying water column in the form of both reduced Mn(II) and Mn(III)-L. A simple box model of the Mn cycle in the Northern Gulf of Mexico indicates that Mn(III)-L is required to balance the Mn budget in this region and is an integral, and previously unconsidered, piece of the Mn cycle in the Northern Gulf of Mexico. The presence of Mn(III)-L in this system likely has an outsized impact on trace element scavenging rates, oxidative capacity, and the carbon cycle that have not been previously appreciated.
{"title":"Dynamic manganese cycling in the northern Gulf of Mexico","authors":"Jessalyn E. Davis , Rebecca S. Robinson , Emily R. Estes , Veronique E. Oldham , Evan A. Solomon , Roger P. Kelly , Katherine E. Bell , Joseph A. Resing , Randelle M. Bundy","doi":"10.1016/j.marchem.2024.104466","DOIUrl":"10.1016/j.marchem.2024.104466","url":null,"abstract":"<div><div>Transport processes along the river-ocean continuum influence delivery of nutrients, carbon and trace metals from terrestrial systems to the marine environment, impacting coastal primary productivity and water quality. Although trace metal transformations have been studied extensively in the Mississippi River Delta region of the Northern Gulf of Mexico, investigations of manganese (Mn) and the presence of ligand-stabilized, dissolved manganese (Mn(III)-L) and its role in the transformation of trace elements and organic matter during riverine transport and estuarine mixing have not been considered. This study examined the chemical speciation of dissolved and particulate Mn in the water column and sediment porewaters in the Mississippi River and Northern Gulf of Mexico in March of 2021 to explore transformations in Mn speciation along the river-ocean continuum and the impact of different processes on the distribution of Mn. Total dissolved Mn concentrations were highest in the Mississippi River and decreased offshore, while Mn(III)-L contributed most to the dissolved Mn pool in near-shore waters. Porewater profiles indicated that ligand stabilization prevented dissolved Mn(III) reduction below the depth of oxygen penetration and in the presence of equimolar dissolved iron(II). Dissolved Mn(III)-L was enriched in bottom waters at all Northern Gulf of Mexico stations, and diffusive flux modelling of porewater dissolved Mn suggested that reducing sediments were a source of dissolved Mn to the overlying water column in the form of both reduced Mn(II) and Mn(III)-L. A simple box model of the Mn cycle in the Northern Gulf of Mexico indicates that Mn(III)-L is required to balance the Mn budget in this region and is an integral, and previously unconsidered, piece of the Mn cycle in the Northern Gulf of Mexico. The presence of Mn(III)-L in this system likely has an outsized impact on trace element scavenging rates, oxidative capacity, and the carbon cycle that have not been previously appreciated.</div></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"267 ","pages":"Article 104466"},"PeriodicalIF":3.0,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142703071","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-22DOI: 10.1016/j.marchem.2024.104463
Samantha Rush , Penny Vlahos , Chang-Ho Lee , Kitack Lee , Lauren J. Barrett
The Arctic Ocean's sea ice loss dynamically impacts carbon uptake potential, as assessed through measured carbonate parameters, such as total alkalinity. In the open ocean, boron (B) is the third largest contributor to alkalinity via borate and is usually accounted for through the conservative boron to salinity ratio (B/S), and not directly measured. Here, we present findings on non-conservative boron dynamics, that results in significant B/S deviations, observed in ice melt zone waters, snow, slush, brine, and annual sea ice (n = 169) in the Fram Strait entering the Central Arctic. These samples were collected during the onset of the melt season on the 2023 ARTofMELT expedition, covering a wide practical salinity range (2–59). Barring snow, the average B/S ratio across the study was 0.1321 ± 0.0032 mg kg−1 ‰−1, similar to the mean B/S ratio measured amongst several polar water masses near Iceland, as well as the accepted B/S for other ocean regions. Results indicate minor deviations from accepted B/S ratios (indicating conservative behavior) across the sample practical salinity range and reflect an uncertainty in the borate contribution to total alkalinity of less than 2.9 μmol kg−1 at in-situ temperatures. B fractionation appears to occur during sea ice formation, causing greater B in the sea ice reservoir whereas brine, slush, lead, and under-ice water reservoirs are depleted in B. As such, under-ice and lead, brine, and slush samples all had measured B/S ratios (0.1305 ± 0.0011, 0.1305 ± 0.0018, and 0.1304 ± 0.0017 mg kg−1 ‰−1, respectively) lower than the established ratio whereas the average sea ice B/S ratio (0.1331 ± 0.0035 mg kg−1 ‰−1) was closest to accepted values (0.1336 ± 0.0005 mg kg−1 ‰−1). Arctic open ocean samples also had a lower B/S ratio (0.1304 ± 0.0014 mg kg−1 ‰−1). Our findings, together with a previous Arctic B ice study, suggest that B (probably in the form of B(OH)4−) is incorporated into authigenic CaCO3 minerals, replacing CO32− within the mineral lattice during sea ice formation. This process consequentially lowers the B/S ratio in the open Arctic Ocean, compared to the established global ocean ratio. Nevertheless, the incorporation of B into the sea ice reservoir does not fully account for the deficit of B in the Arctic Ocean samples, suggesting further accounting of B Arctic pathways is necessary. In future climate scenarios involving increased sea ice melt, the transition from multiyear to annual sea ice, permafrost thaw, and increased riverine discharge, the behavior of B in the Arctic Ocean is expected to become more dynamic.
{"title":"Boron to salinity ratios in the Fram Strait entering the Central Arctic: The role of sea ice formation and future predictions","authors":"Samantha Rush , Penny Vlahos , Chang-Ho Lee , Kitack Lee , Lauren J. Barrett","doi":"10.1016/j.marchem.2024.104463","DOIUrl":"10.1016/j.marchem.2024.104463","url":null,"abstract":"<div><div>The Arctic Ocean's sea ice loss dynamically impacts carbon uptake potential, as assessed through measured carbonate parameters, such as total alkalinity. In the open ocean, boron (B) is the third largest contributor to alkalinity via borate and is usually accounted for through the conservative boron to salinity ratio (B/S), and not directly measured. Here, we present findings on non-conservative boron dynamics, that results in significant B/S deviations, observed in ice melt zone waters, snow, slush, brine, and annual sea ice (<em>n</em> = 169) in the Fram Strait entering the Central Arctic. These samples were collected during the onset of the melt season on the 2023 ARTofMELT expedition, covering a wide practical salinity range (2–59). Barring snow, the average B/S ratio across the study was 0.1321 ± 0.0032 mg kg<sup>−1</sup> ‰<sup>−1</sup>, similar to the mean B/S ratio measured amongst several polar water masses near Iceland, as well as the accepted B/S for other ocean regions. Results indicate minor deviations from accepted B/S ratios (indicating conservative behavior) across the sample practical salinity range and reflect an uncertainty in the borate contribution to total alkalinity of less than 2.9 μmol kg<sup>−1</sup> at in-situ temperatures. B fractionation appears to occur during sea ice formation, causing greater B in the sea ice reservoir whereas brine, slush, lead, and under-ice water reservoirs are depleted in B. As such, under-ice and lead, brine, and slush samples all had measured B/S ratios (0.1305 ± 0.0011, 0.1305 ± 0.0018, and 0.1304 ± 0.0017 mg kg<sup>−1</sup> ‰<sup>−1</sup>, respectively) lower than the established ratio whereas the average sea ice B/S ratio (0.1331 ± 0.0035 mg kg<sup>−1</sup> ‰<sup>−1</sup>) was closest to accepted values (0.1336 ± 0.0005 mg kg<sup>−1</sup> ‰<sup>−1</sup>). Arctic open ocean samples also had a lower B/S ratio (0.1304 ± 0.0014 mg kg<sup>−1</sup> ‰<sup>−1</sup>). Our findings, together with a previous Arctic B ice study, suggest that B (probably in the form of B(OH)<sub>4</sub><sup>−</sup>) is incorporated into authigenic CaCO<sub>3</sub> minerals, replacing CO<sub>3</sub><sup>2−</sup> within the mineral lattice during sea ice formation. This process consequentially lowers the B/S ratio in the open Arctic Ocean, compared to the established global ocean ratio. Nevertheless, the incorporation of B into the sea ice reservoir does not fully account for the deficit of B in the Arctic Ocean samples, suggesting further accounting of B Arctic pathways is necessary. In future climate scenarios involving increased sea ice melt, the transition from multiyear to annual sea ice, permafrost thaw, and increased riverine discharge, the behavior of B in the Arctic Ocean is expected to become more dynamic.</div></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"267 ","pages":"Article 104463"},"PeriodicalIF":3.0,"publicationDate":"2024-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142528416","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-22DOI: 10.1016/j.marchem.2024.104464
Alexey Kamyshny Jr , Debora Sela , Rotem Klein , Alexandra V. Turchyn , Gilad Antler , Holger Freund
Intertidal flats are highly productive coastal marine ecosystems which are affected by fast changes in environmental conditions and host dynamic biogeochemical cycles in their sediments. Bioturbation by burrowing organisms and roots of plants strongly affects speciation and cycling of redox-sensitive elements in intertidal sediments. In this work, we have studied the impact of sediment type and vegetation on the cycling of redox-sensitive elements including sulfur, iron, and manganese in sandy and muddy tidal flats sediments in the Jade Bay (North Sea) and adjacent area. The redox speciation of these elements was analyzed in the pore-waters and the total sediment. The isotopic compositions of sulfur species were measured in non-vegetated sediments and in sediments which are inhabited by various plants. In the cohesive sediments, which are not affected by vegetation, a decrease in sulfate concentration, coupled with the presence of relatively high concentrations of hydrogen sulfide in the pore-waters and the presence of sulfide minerals as well the isotopic compositions of sulfur species are consistent with fast rates of sulfate reduction in the sediments. In the cohesive sediments affected by roots of Salicornia stricta and sediments desiccation, a cryptic sulfur cycle, which is characterized by microbial sulfate reduction coupled to fast reoxidation of hydrogen sulfide by Fe(III) (hydr)oxides and, possibly, by oxygen is present. Below the roots penetration depth, speciation of redox-sensitive elements is similar to those in the baren sediments. In the cohesive sediments affected by the roots of Spartina anglica and Triglochin maritima, which have longer roots, a cryptic sulfur cycle was detected in the upper 30 cm of sediments. At the sites that are characterized by permeable surface sediments and alternating permeable and cohesive layers in the deeper sediments, the composition of the sediment has a similar or even more significant impact on the speciation of the redox-sensitive elements than penetration of relatively weak roots of Spartina anglica. These sediments are characterized by the formation of hydrogen sulfide and sulfide oxidation intermediates in the cohesive layers and their diffusion to (and oxidation at) the boundaries between cohesive and permeable sediments. We conclude that in the cohesive sediments, the penetration of roots and desiccation leads to the formation of overall oxidized conditions, while in the sediments with alternating layers, permeability may provide a more significant control for speciation of redox-sensitive elements.
潮间带滩涂是高产的沿海海洋生态系统，受到环境条件快速变化的影响，其沉积物中的生物地球化学循环充满活力。穴居生物和植物根系的生物扰动强烈影响着潮间带沉积物中氧化还原敏感元素的种类和循环。在这项工作中，我们研究了沉积物类型和植被对翡翠湾（北海）及邻近地区沙质和泥质潮滩沉积物中硫、铁和锰等氧化还原敏感元素循环的影响。分析了孔隙水和总沉积物中这些元素的氧化还原分型。在无植被沉积物和有各种植物栖息的沉积物中测量了硫的同位素组成。在未受植被影响的粘性沉积物中，硫酸盐浓度下降，孔隙水中硫化氢浓度相对较高，硫化物矿物的存在以及硫的同位素组成都表明沉积物中硫酸盐的还原速度很快。在受盐生植物根系和沉积物干燥影响的粘性沉积物中，存在一个隐秘的硫循环，其特点是微生物的硫酸盐还原与硫化氢被铁（III）（氢）氧化物（可能还有氧气）快速再氧化相结合。在根系渗透深度以下，对氧化还原敏感的元素种类与巴伦沉积物中的相似。在受根系较长的 Spartina anglica 和 Triglochin maritima 根系影响的粘性沉积物中，在上层 30 厘米的沉积物中检测到隐性硫循环。在表层沉积物具有渗透性、深层沉积物中的渗透层和粘合层交替出现的地点，沉积物的成分对氧化还原敏感元素的种类影响类似于或甚至大于根系相对较弱的红豆杉根系的渗透。这些沉积物的特点是：硫化氢和硫化物氧化中间产物在粘性层中形成，并扩散到粘性沉积物和渗透性沉积物之间的边界（并在边界处氧化）。我们的结论是，在粘性沉积物中，根系的渗透和干燥会导致整体氧化条件的形成，而在具有交替层的沉积物中，渗透性可能对氧化还原敏感元素的标本化提供更重要的控制。
{"title":"Biogeochemical sulfur transformations in the cohesive and permeable tidal flat sediments of Jade Bay (North Sea)","authors":"Alexey Kamyshny Jr , Debora Sela , Rotem Klein , Alexandra V. Turchyn , Gilad Antler , Holger Freund","doi":"10.1016/j.marchem.2024.104464","DOIUrl":"10.1016/j.marchem.2024.104464","url":null,"abstract":"<div><div>Intertidal flats are highly productive coastal marine ecosystems which are affected by fast changes in environmental conditions and host dynamic biogeochemical cycles in their sediments. Bioturbation by burrowing organisms and roots of plants strongly affects speciation and cycling of redox-sensitive elements in intertidal sediments. In this work, we have studied the impact of sediment type and vegetation on the cycling of redox-sensitive elements including sulfur, iron, and manganese in sandy and muddy tidal flats sediments in the Jade Bay (North Sea) and adjacent area. The redox speciation of these elements was analyzed in the pore-waters and the total sediment. The isotopic compositions of sulfur species were measured in non-vegetated sediments and in sediments which are inhabited by various plants. In the cohesive sediments, which are not affected by vegetation, a decrease in sulfate concentration, coupled with the presence of relatively high concentrations of hydrogen sulfide in the pore-waters and the presence of sulfide minerals as well the isotopic compositions of sulfur species are consistent with fast rates of sulfate reduction in the sediments. In the cohesive sediments affected by roots of <em>Salicornia stricta</em> and sediments desiccation, a cryptic sulfur cycle, which is characterized by microbial sulfate reduction coupled to fast reoxidation of hydrogen sulfide by Fe(III) (hydr)oxides and, possibly, by oxygen is present. Below the roots penetration depth, speciation of redox-sensitive elements is similar to those in the baren sediments. In the cohesive sediments affected by the roots of <em>Spartina anglica</em> and <em>Triglochin maritima</em>, which have longer roots, a cryptic sulfur cycle was detected in the upper 30 cm of sediments. At the sites that are characterized by permeable surface sediments and alternating permeable and cohesive layers in the deeper sediments, the composition of the sediment has a similar or even more significant impact on the speciation of the redox-sensitive elements than penetration of relatively weak roots of <em>Spartina anglica</em>. These sediments are characterized by the formation of hydrogen sulfide and sulfide oxidation intermediates in the cohesive layers and their diffusion to (and oxidation at) the boundaries between cohesive and permeable sediments. We conclude that in the cohesive sediments, the penetration of roots and desiccation leads to the formation of overall oxidized conditions, while in the sediments with alternating layers, permeability may provide a more significant control for speciation of redox-sensitive elements.</div></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"267 ","pages":"Article 104464"},"PeriodicalIF":3.0,"publicationDate":"2024-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142528415","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-14DOI: 10.1016/j.marchem.2024.104460
Ryan H. Glaubke , Amy J. Wagner , Elisabeth L. Sikes
{"title":"Corrigendum to “Characterizing the stable oxygen isotopic composition of the Southeast Indian Ocean” [Marine Chemistry 262 (2024) 104397]","authors":"Ryan H. Glaubke , Amy J. Wagner , Elisabeth L. Sikes","doi":"10.1016/j.marchem.2024.104460","DOIUrl":"10.1016/j.marchem.2024.104460","url":null,"abstract":"","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"267 ","pages":"Article 104460"},"PeriodicalIF":3.0,"publicationDate":"2024-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142432336","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-11DOI: 10.1016/j.marchem.2024.104461
Anja Reckhardt , Rena Meyer , Stephan L. Seibert , Janek Greskowiak , Magali Roberts , Simone Brick , Grace Abarike , Kojo Amoako , Hannelore Waska , Kai Schwalfenberg , Iris Schmiedinger , Oliver Wurl , Michael Ernst Böttcher , Gudrun Massmann , Katharina Pahnke
Intertidal sandy beach systems are considered complex biogeochemical reactors. At beach sites that are subject to high tidal and wave energy, seawater circulation can reach tens of meters deep into the subsurface and changing environmental conditions are assumed to lead to dynamic groundwater flow paths, saltwater-freshwater mixing zones, and a spatio-temporally variable groundwater biogeochemistry. Previous studies mainly focused on the upper meters of subterranean estuaries (STE), while the deep subsurface remained a black box. This study presents spatial (cross-shore) and temporal (∼ six-weekly, over 1.5 years) dynamics of the groundwater biogeochemistry that were observed down to 24 m below the ground surface (mbgs) of a sandy high-energy beach on Spiekeroog Island (Germany).
In addition to redox conditions along a cross-shore transect ranging from oxic to Fe oxide reducing/slightly sulfidic, we found a previously unknown, distinct vertical redox zonation as well. Temporal variations of the biogeochemistry within low salinity groundwater at the most landward station close to the dune base were mainly driven by storm flood related seawater infiltration. Around the high water line, the extent of the upper saline plume (USP) varied over time. Furthermore, temporal dynamics of the O2 saturation at 6 mbgs indicated a seasonally shifting depth of the oxycline at this location. In the lower intertidal zone, groundwater solute concentrations displayed a temporally variable zone of deep freshwater discharge.
Regarding the impact of the deep STE on the groundwater biogeochemistry of the discharge zone, our data revealed that nutrient, Mn, and Fe release along the deep flow paths through the USP towards the discharge zone was limited, likely due decreasing availability of labile organic matter and subsequent slowing down of metabolic processes with depth. High concentrations of metabolites in the upper ∼ 2 mbgs of the discharge zone were, therefore, rather attributed to the incorporation of labile organic matter during continuous and storm flood related sediment relocation and/or the contribution of older waters, e.g., the subtidal saltwater wedge.
{"title":"Spatial and temporal dynamics of groundwater biogeochemistry in the deep subsurface of a high-energy beach","authors":"Anja Reckhardt , Rena Meyer , Stephan L. Seibert , Janek Greskowiak , Magali Roberts , Simone Brick , Grace Abarike , Kojo Amoako , Hannelore Waska , Kai Schwalfenberg , Iris Schmiedinger , Oliver Wurl , Michael Ernst Böttcher , Gudrun Massmann , Katharina Pahnke","doi":"10.1016/j.marchem.2024.104461","DOIUrl":"10.1016/j.marchem.2024.104461","url":null,"abstract":"<div><div>Intertidal sandy beach systems are considered complex biogeochemical reactors. At beach sites that are subject to high tidal and wave energy, seawater circulation can reach tens of meters deep into the subsurface and changing environmental conditions are assumed to lead to dynamic groundwater flow paths, saltwater-freshwater mixing zones, and a spatio-temporally variable groundwater biogeochemistry. Previous studies mainly focused on the upper meters of subterranean estuaries (STE), while the deep subsurface remained a black box. This study presents spatial (cross-shore) and temporal (∼ six-weekly, over 1.5 years) dynamics of the groundwater biogeochemistry that were observed down to 24 m below the ground surface (mbgs) of a sandy high-energy beach on Spiekeroog Island (Germany).</div><div>In addition to redox conditions along a cross-shore transect ranging from oxic to Fe oxide reducing/slightly sulfidic, we found a previously unknown, distinct vertical redox zonation as well. Temporal variations of the biogeochemistry within low salinity groundwater at the most landward station close to the dune base were mainly driven by storm flood related seawater infiltration. Around the high water line, the extent of the upper saline plume (USP) varied over time. Furthermore, temporal dynamics of the O<sub>2</sub> saturation at 6 mbgs indicated a seasonally shifting depth of the oxycline at this location. In the lower intertidal zone, groundwater solute concentrations displayed a temporally variable zone of deep freshwater discharge.</div><div>Regarding the impact of the deep STE on the groundwater biogeochemistry of the discharge zone, our data revealed that nutrient, Mn, and Fe release along the deep flow paths through the USP towards the discharge zone was limited, likely due decreasing availability of labile organic matter and subsequent slowing down of metabolic processes with depth. High concentrations of metabolites in the upper ∼ 2 mbgs of the discharge zone were, therefore, rather attributed to the incorporation of labile organic matter during continuous and storm flood related sediment relocation and/or the contribution of older waters, e.g., the subtidal saltwater wedge.</div></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"267 ","pages":"Article 104461"},"PeriodicalIF":3.0,"publicationDate":"2024-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142446926","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-11DOI: 10.1016/j.marchem.2024.104462
Carolina Cantoni , Cinzia De Vittor , Jadran Faganeli , Michele Giani , Nives Kovač , Alenka Malej , Nives Ogrinc , Samo Tamše , Valentina Turk
Although the marginal seas represent only 7 % of the total area of the ocean, CO2 fluxes are important for the carbon budget, exposing them to the intense process of anthropogenic ocean acidification. The Adriatic Sea is currently a CO2 sink (−0.5 to −1 mol C m−2 y−1) with an annual flux comparable to the net sink rates in the NW Mediterranean. Based on a comparison of two winter cruises carried out in the 25-years interval between 1983 and 2008, an acidification rate of 0.003 pHT units y−1 was estimated in the northern Adriatic which is similar to the Mediterranean open waters (with recent estimations of −0.0028 ± 0.0003 pHT units y−1) and the surface coastal waters (−0.003 ± 0.001 and − 0.0044 ± 0.00006 pHT units y−1). The computed Revelle factor for the Adriatic Sea (approximately 10) indicates that the buffer capacity is rather high and that the waters do not appear to be particularly exposed to acidification. Total alkalinity (TA) in the Adriatic (2.6–2.7 mmol kg−1) is in the upper range of TA measured in the Mediterranean Sea. This is primarily due to the riverine inputs which transport carbonates dissolved from the Alpine dolomites and karstic watersheds. The Adriatic Sea is the second sub-basin (319 Gmol y−1), following the Aegean Sea (which receives the TA contribution from the Black Sea), that contribute to the riverine TA discharges into the Mediterranean Sea. About 60 % of the TA inflow into the Adriatic Sea is attributed to discharge from the Po River with a TA of ∼3 mmol kg−1 and TA decreases with increasing salinity. The north Adriatic dense water spreading and cascading is an efficient mechanism for exporting TA and DIC at depth, from the northern Adriatic towards the bottom of the South Adriatic Pit and possibly to the eastern Mediterranean. Saturation states indicate that the waters of the Adriatic are supersaturated throughout the year with respect to aragonite (ΩAr). However, the saturation state is considerably lower in the bottom water layers, due to the prevalence of the bottom layer and benthic remineralisation in the stratification period. Effects on calcifying organisms and phytoplankton are expected in the future.
虽然边缘海只占海洋总面积的 7%，但二氧化碳通量对碳预算非常重要，使其受到人为海洋酸化过程的严重影响。亚得里亚海目前是一个二氧化碳汇（-0.5 至 -1 摩尔 C m-2 y-1），其年通量与地中海西北部的净汇率相当。根据对 1983 年至 2008 年 25 年间两次冬季巡航的比较，估计亚得里亚海北部的酸化率为 0.003 pHT 单位年-1，与地中海开阔水域（最近的估计值为-0.0028 ± 0.0003 pHT 单位年-1）和沿岸表层水域（-0.003 ± 0.001 和 - 0.0044 ± 0.00006 pHT 单位年-1）相似。计算得出的亚得里亚海雷维尔因子（约 10）表明，亚得里亚海的缓冲能力相当高，水体似乎并不特别容易酸化。亚得里亚海的总碱度（TA）（2.6-2.7 mmol kg-1）处于地中海测得的总碱度的上限范围。这主要是由于从阿尔卑斯白云岩和喀斯特流域溶解的碳酸盐被河流输入所致。亚得里亚海是继爱琴海（接收来自黑海的 TA 量）之后，第二个向地中海排放河流 TA 量的子流域（319 Gmol y-1）。流入亚得里亚海的 TA 大约有 60% 来自波河，其 TA 为 3 mmol kg-1 左右，TA 随盐度增加而减少。北亚得里亚海稠密水域的扩散和层叠是将 TA 和 DIC 从亚得里亚海北部向南亚得里亚海海坑底部并可能向地中海东部深度输出的有效机制。饱和状态表明，亚得里亚海水域的文石（ΩAr）全年都处于过饱和状态。不过，底层水的饱和状态要低得多，这是由于底层水和底栖生物在分层期的再矿化现象普遍存在。预计未来会对钙化生物和浮游植物产生影响。
{"title":"Carbonate system and acidification of the Adriatic Sea","authors":"Carolina Cantoni , Cinzia De Vittor , Jadran Faganeli , Michele Giani , Nives Kovač , Alenka Malej , Nives Ogrinc , Samo Tamše , Valentina Turk","doi":"10.1016/j.marchem.2024.104462","DOIUrl":"10.1016/j.marchem.2024.104462","url":null,"abstract":"<div><div>Although the marginal seas represent only 7 % of the total area of the ocean, CO<sub>2</sub> fluxes are important for the carbon budget, exposing them to the intense process of anthropogenic ocean acidification. The Adriatic Sea is currently a CO<sub>2</sub> sink (−0.5 to −1 mol C m<sup>−2</sup> y<sup>−1</sup>) with an annual flux comparable to the net sink rates in the NW Mediterranean. Based on a comparison of two winter cruises carried out in the 25-years interval between 1983 and 2008, an acidification rate of 0.003 pH<sub>T</sub> units y<sup>−1</sup> was estimated in the northern Adriatic which is similar to the Mediterranean open waters (with recent estimations of −0.0028 ± 0.0003 pH<sub>T</sub> units y<sup>−1</sup>) and the surface coastal waters (−0.003 ± 0.001 and − 0.0044 ± 0.00006 pH<sub>T</sub> units y<sup>−1</sup>). The computed Revelle factor for the Adriatic Sea (approximately 10) indicates that the buffer capacity is rather high and that the waters do not appear to be particularly exposed to acidification. Total alkalinity (TA) in the Adriatic (2.6–2.7 mmol kg<sup>−1</sup>) is in the upper range of TA measured in the Mediterranean Sea. This is primarily due to the riverine inputs which transport carbonates dissolved from the Alpine dolomites and karstic watersheds. The Adriatic Sea is the second sub-basin (319 Gmol y<sup>−1</sup>), following the Aegean Sea (which receives the TA contribution from the Black Sea), that contribute to the riverine TA discharges into the Mediterranean Sea. About 60 % of the TA inflow into the Adriatic Sea is attributed to discharge from the Po River with a TA of ∼3 mmol kg<sup>−1</sup> and TA decreases with increasing salinity. The north Adriatic dense water spreading and cascading is an efficient mechanism for exporting TA and DIC at depth, from the northern Adriatic towards the bottom of the South Adriatic Pit and possibly to the eastern Mediterranean. Saturation states indicate that the waters of the Adriatic are supersaturated throughout the year with respect to aragonite (Ω<sub>Ar</sub>). However, the saturation state is considerably lower in the bottom water layers, due to the prevalence of the bottom layer and benthic remineralisation in the stratification period. Effects on calcifying organisms and phytoplankton are expected in the future.</div></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"267 ","pages":"Article 104462"},"PeriodicalIF":3.0,"publicationDate":"2024-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142528414","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-30DOI: 10.1016/j.marchem.2024.104459
Harsh Raj, Siby Kurian
Bomb-radiocarbon is a useful tracer to study ocean circulation and air-sea CO2 exchange processes. In the present study bomb radiocarbon distribution in dissolved inorganic carbon of the Northern Indian Ocean around late 2010s has been evaluated. In the late 2010s surface waters in the Northern Indian Ocean had ∆14C values ranging between 9 and 17 ‰ which is comparable or even higher than that of the contemporaneous atmospheric ∆14C values. Water column measurements showed that the bomb 14C inventory in the Arabian Sea and the Bay of Bengal has increased between 1990s and 2010s. During the same period, the eastern and western equatorial Indian Ocean showed either no change or a slight decline in the water column bomb 14C inventory. These bomb 14C inventory values were also used to estimate the air-sea CO2 exchange rate and net CO2 flux over the Northern Indian Ocean region. Bomb 14C-based estimate of net CO2 flux from the Arabian Sea is 75 ± 24 Tg C yr−1 and the Bay of Bengal is 1 ± 7 Tg C yr−1, which is comparable to the estimates reported by previous investigations in the region. The present observations show that the bomb 14C is being transferred to the deeper depths of the ocean, emphasizing the need for continued 14C measurements to gain further insights into subsurface processes in the region.
{"title":"Bomb-radiocarbon in the Northern Indian Ocean","authors":"Harsh Raj, Siby Kurian","doi":"10.1016/j.marchem.2024.104459","DOIUrl":"10.1016/j.marchem.2024.104459","url":null,"abstract":"<div><div>Bomb-radiocarbon is a useful tracer to study ocean circulation and air-sea CO<sub>2</sub> exchange processes. In the present study bomb radiocarbon distribution in dissolved inorganic carbon of the Northern Indian Ocean around late 2010s has been evaluated. In the late 2010s surface waters in the Northern Indian Ocean had ∆<sup>14</sup>C values ranging between 9 and 17 ‰ which is comparable or even higher than that of the contemporaneous atmospheric ∆<sup>14</sup>C values. Water column measurements showed that the bomb <sup>14</sup>C inventory in the Arabian Sea and the Bay of Bengal has increased between 1990s and 2010s. During the same period, the eastern and western equatorial Indian Ocean showed either no change or a slight decline in the water column bomb <sup>14</sup>C inventory. These bomb <sup>14</sup>C inventory values were also used to estimate the air-sea CO<sub>2</sub> exchange rate and net CO<sub>2</sub> flux over the Northern Indian Ocean region. Bomb <sup>14</sup>C-based estimate of net CO<sub>2</sub> flux from the Arabian Sea is 75 ± 24 Tg C yr<sup>−1</sup> and the Bay of Bengal is 1 ± 7 Tg C yr<sup>−1</sup>, which is comparable to the estimates reported by previous investigations in the region. The present observations show that the bomb <sup>14</sup>C is being transferred to the deeper depths of the ocean, emphasizing the need for continued <sup>14</sup>C measurements to gain further insights into subsurface processes in the region.</div></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"267 ","pages":"Article 104459"},"PeriodicalIF":3.0,"publicationDate":"2024-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142426468","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Carbonyl Sulfide (OCS) is the most abundant sulfur-containing gas in the atmosphere, and it is used as a proxy for terrestrial gross primary productivity (GPP). Oceans are the major source of OCS to the atmosphere, produced by photochemical and “dark” reactions. Hydrolysis to H2S and CO2 is the major removal process of OCS from the ocean's surface. Measuring the sulfur isotope values (δ34S) and the isotopic fractionation (ε) associated with these major OCS sources and sinks could decrease the uncertainties in its fluxes. In the current study, we aim to determine the ε during the hydrolysis process of OCS (εh). We used a purge and trap system coupled to a GC/MC-ICPMS to measure δ34S values during hydrolysis under different temperatures (4–40 °C), salinities (0.2–40 g/L), and pH (4–9), representing various natural environmental conditions. In addition, we use the quantum chemical method to calculate the equilibrium εh and compare it to the empirical results. Our results for the low salinity (S =0.2 g/L; pH 8.0) water show a temperature dependency of the εh from −3.9 ‰ ± 0.2 ‰ (4 °C,) to −2.2 ± 0.6 ‰ (40 °C). The higher fractionation at low temperatures has implication for ice-core data interpretation. However, in natural seawater at 4 and 22 °C (S = 40 g/L, pH 8.2) there was no such temperature dependency and the εh averaged −2.6 ± 0.3 ‰. Thus, it seems that salinity cancels the temperature effect close to the freezing temperature of water. Varying the pH between 4 and 9 (at 22 °C) did not result in any εh trend. Ab-initio calculations suggest that OCS hydrolysis is not controlled by equilibrium. The εh values we report will aid in quantifying the impact of OCS's hydrolysis on the observable sulfur isotopic signature of OCS in oceanic and in freshwater environments. This in turn will facilitate more accurate mass-balance calculations for the OCS budget from the ocean to the atmosphere.
{"title":"Sulfur isotopic fractionation during hydrolysis of carbonyl sulfide","authors":"Yasmin Avidani , Alon Angert , Chen Davidson , Xinyu Xia , Yongli Gao , Alon Amrani","doi":"10.1016/j.marchem.2024.104458","DOIUrl":"10.1016/j.marchem.2024.104458","url":null,"abstract":"<div><div>Carbonyl Sulfide (OCS) is the most abundant sulfur-containing gas in the atmosphere, and it is used as a proxy for terrestrial gross primary productivity (GPP). Oceans are the major source of OCS to the atmosphere, produced by photochemical and “dark” reactions. Hydrolysis to H<sub>2</sub>S and CO<sub>2</sub> is the major removal process of OCS from the ocean's surface. Measuring the sulfur isotope values (δ<sup>34</sup>S) and the isotopic fractionation (ε) associated with these major OCS sources and sinks could decrease the uncertainties in its fluxes. In the current study, we aim to determine the ε during the hydrolysis process of OCS (ε<sub>h</sub>). We used a purge and trap system coupled to a GC/MC-ICPMS to measure δ<sup>34</sup>S values during hydrolysis under different temperatures (4–40 °C), salinities (0.2–40 g/L), and pH (4–9), representing various natural environmental conditions. In addition, we use the quantum chemical method to calculate the equilibrium ε<sub>h</sub> and compare it to the empirical results. Our results for the low salinity (S =0.2 g/L; pH 8.0) water show a temperature dependency of the ε<sub>h</sub> from −3.9 ‰ ± 0.2 ‰ (4 °C,) to −2.2 ± 0.6 ‰ (40 °C). The higher fractionation at low temperatures has implication for ice-core data interpretation. However, in natural seawater at 4<span><math><msup><mrow></mrow><mo>°</mo></msup><mi>C</mi></math></span> and 22 °C (S = 40 g/L, pH 8.2) there was no such temperature dependency and the ε<sub>h</sub> averaged −2.6 ± 0.3 ‰. Thus, it seems that salinity cancels the temperature effect close to the freezing temperature of water. Varying the pH between 4 and 9 (at 22 °C) did not result in any ε<sub>h</sub> trend. Ab-initio calculations suggest that OCS hydrolysis is not controlled by equilibrium. The ε<sub>h</sub> values we report will aid in quantifying the impact of OCS's hydrolysis on the observable sulfur isotopic signature of OCS in oceanic and in freshwater environments. This in turn will facilitate more accurate mass-balance calculations for the OCS budget from the ocean to the atmosphere.</div></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"267 ","pages":"Article 104458"},"PeriodicalIF":3.0,"publicationDate":"2024-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142357597","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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