Marine Chemistry最新文献

{"title":"Revisit of ballast hypothesis in the Bay of Bengal","authors":"V.V.S.S. Sarma","doi":"10.1016/j.marchem.2024.104422","DOIUrl":"https://doi.org/10.1016/j.marchem.2024.104422","url":null,"abstract":"<div><p>The ballast hypothesis involving rapid sinking of organic carbon in association with riverine mineral particles is proposed in the Bay of Bengal (BoB) in 1991. The ballast hypothesis was used intensively to explain several biogeochemical processes, such as low primary production, weak oxygen minimum zone (OMZ), low bacterial respiration rates and lack of denitrification in the BoB. In contrast, the recent measurements indicated that high primary production, intense OMZ with occurrence of denitrification in the sinking particles but not in the water column. Hence the ballast hypothesis is re-visited using the recent experiments conducted on sinking particle flux using sediment traps, ²³⁴Thorium based particulate organic carbon export, particle back scatter, water column biogeochemistry, stable isotopic composition of carbon and nitrogen of sinking particles and surface sediment of shelf region. The isotopic data suggests the sinking organic matter is mainly contributed by in-situ production supported by dissolved organic nitrogen (DON). The amount of organic matter decomposed within the water column was higher in the north and decreased towards southern BoB and it is consistent with the spatial pattern of rate of sinking particle flux suggesting against ballast hypothesis of removal of organic matter to the sediment with weaker modifications in the water column. The higher organic carbon trapped in the middle and deep than shallow traps was observed and it is attributed to cross-shelf transport of sedimentary organic carbon as evidenced from the back-scatter of particles and isotopic composition carbon and nitrogen of shelf sediments. Variations in the river discharge did not show impact on the magnitude of sinking carbon fluxes indicating that river discharge is not a drive force for higher sinking carbon fluxes to deep BoB than hitherto hypothesized as ballast effect.</p></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"265 ","pages":"Article 104422"},"PeriodicalIF":3.0,"publicationDate":"2024-06-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141328909","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}

{"title":"Latitudinal variations of iron chemical speciation in the euphotic zone of the central Pacific Ocean","authors":"Mitsuhide Sato,&nbsp;Yohei Wakuta,&nbsp;Shigenobu Takeda","doi":"10.1016/j.marchem.2024.104413","DOIUrl":"https://doi.org/10.1016/j.marchem.2024.104413","url":null,"abstract":"<div><p>The concentrations of dissolved iron (DFe), iron-binding ligands (L_Fe), and electroactive humic-like substances (eHS) were revealed in the upper 200 m along the 170°W latitudinal transect of the central Pacific Ocean in summer, which was weakly influenced by terrestrial input. DFe was largely depleted throughout the transect, except in the Bering Sea, and below 100 m in the North Pacific Subarctic Gyre. The concentration of L_Fe was lowest within the subtropical gyres and was lower in the Southern Hemisphere, which is consistent with the results from the Atlantic Ocean. The vertical distribution of L_Fe was relatively constant in the subtropical regions, whereas in the subarctic regions the subsurface maximum appeared around or over the subsurface chlorophyll maximum at some stations. The higher concentration of L_Fe in the subarctic regions coincides with a lower stability constant, which suggests a higher contribution of weaker ligands, including humic and exopolymeric substances. The horizontal and vertical distribution patterns of eHS were largely similar to those of L_Fe, supporting their significant contribution to iron-binding capacity in the upper 200 m, particularly in the subarctic regions. However, the eHS concentration was only weakly correlated with that of the fluorescently determined humic-like substances, demonstrating the substantially different chemical properties of the two humic-like substances. The strong positive correlation between the concentrations of eHS and chlorophyll <em>a</em> and <em>Synechococcus</em> strongly suggests their biological origins. However, further research is required to examine whether eHS are directly produced by phytoplankton or released via relevant biological processes, such as grazing, bacterial composition, and viral lysis.</p></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"265 ","pages":"Article 104413"},"PeriodicalIF":3.0,"publicationDate":"2024-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141303234","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}

{"title":"Distributions of cadmium, nickel, zinc, copper, and iron in the western South Pacific Ocean: Local sources of the nutrient-type trace metals","authors":"L. Zheng ,&nbsp;T. Minami ,&nbsp;S. Takano ,&nbsp;Y. Sohrin","doi":"10.1016/j.marchem.2024.104411","DOIUrl":"10.1016/j.marchem.2024.104411","url":null,"abstract":"<div><p>This study presents comprehensive sectional distributions of five nutrient-type trace metals (Cd, Ni, Zn, Cu, and Fe) within the total dissolvable (td), dissolved (d), and labile particulate (lp) fractions along the GEOTRACES transect GP19 (∼170°W). Among these trace metals, only dCd exhibits a strong correlation with phosphate, albeit with a notable deviation at around ∼100 m depth for stations situated between 50°S and 0°S. This divergence indicates that the distribution of dCd is primarily influenced by ocean circulation and biogeochemical cycling in the western South Pacific Ocean. Conversely, dNi, dZn, and dCu concentrations increase independently of phosphate in waters exceeding 1500 m depth. These variations can partly be attributed to reversible scavenging, benthic release from sediments in the Fiji Basins and the Southwest Pacific Basin, and/or water mass mixing. While a moderate correlation exists between dFe and PO₄ throughout the water column, the slope of the regression line is less than half of the Fe/P ratio observed in phytoplankton, suggesting substantial scavenging of dFe. Furthermore, the distribution of dFe is influenced by local sources such as intense weathering on tropical-subtropical lands and hydrothermal activities.</p></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"263 ","pages":"Article 104411"},"PeriodicalIF":3.0,"publicationDate":"2024-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0304420324000628/pdfft?md5=21d4e5c331091c0b4519edc73ef8ed7e&pid=1-s2.0-S0304420324000628-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141132057","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}

{"title":"Biogenic and lithogenic silicon along the GEOTRACES south West Indian Ocean section (SWINGS-GS02) and the islands mass effect on regional Si biogeochemical cycle","authors":"Valentin Deteix ,&nbsp;Edwin Cotard ,&nbsp;Sandrine Caquineau ,&nbsp;William M. Landing ,&nbsp;Frédéric Planchon ,&nbsp;Thomas Ryan-Keogh ,&nbsp;Damien Cardinal","doi":"10.1016/j.marchem.2024.104412","DOIUrl":"https://doi.org/10.1016/j.marchem.2024.104412","url":null,"abstract":"<div><p>The distribution and cycling of biogenic silica (BSi) and lithogenic silicon (LSi) in the ocean play crucial roles in the global silicon cycle and marine ecosystem dynamics. This is especially the case in the Southern Ocean where diatoms constitute the predominant phytoplankton and participate in a major way to the biological carbon pump. This study presents an assessment of BSi and LSi concentrations along the GEOTRACES South West Indian Ocean Section (SWINGS, late austral summer 2021), where several and contrasting regions were encountered: oligotrophic Mozambique basin, HNLC (High Nutrient Low Chlorophyll) areas and regions fertilized by the Subantarctic islands. Suspended particles were sampled from Niskin bottles and <em>in situ</em> pumps, along with scanning electron microscope (SEM) observations and specific pigments measurements to support BSi and LSi analyses. With samples coming from a contrasting study area prone to diverse continental influences, our BSi and LSi results showed a reproducibility of 13 ± 7%, in the same range as the established protocol. BSi concentrations show a north-south gradient with maxima encountered in the Antarctic Zone, and contrasted results between HNLC open ocean areas and naturally fertilized regions in the vicinity of the Subantarctic islands. Some open ocean stations have unusually high BSi (<em>e.g.</em> &gt; 5 μmol L⁻¹) likely resulting from fertilization by aerosols, upwelling or island mass effect when they are downstream of the islands. Coupling of BSi with SEM observations and pigments measurements respectively showed diatoms were the most representative of the carrying phase of BSi and suggested silicification changes, induced either by heavily silicified diatoms or by micronutrient limitation in HNLC regions. BSi is often dominated by the smallest size fraction (0.45–5 μm) which represent 47 ± 23% of the total BSi based on 29 measurements on size fractionated samples. LSi results highlighted atmospheric inputs at the surface and nepheloid layers in the water column, which makes LSi overall a good indicator of the origin of lithogenic materials. SEM observations supported these results, enabling characterization of the diversity of lithogenic materials in the vicinity of the Subantarctic islands, more specifically volcanic ash around Heard Island, and within the nepheloid layers.</p></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"263 ","pages":"Article 104412"},"PeriodicalIF":3.0,"publicationDate":"2024-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141249513","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}

{"title":"A hydrothermal plume on the Southwest Indian Ridge revealed by a multi-proxy approach: Impact on iron and manganese distributions (GEOTRACES GS02)","authors":"Corentin Baudet ,&nbsp;Eva Bucciarelli ,&nbsp;Géraldine Sarthou ,&nbsp;Cédric Boulart ,&nbsp;Ewan Pelleter ,&nbsp;Millie Goddard-Dwyer ,&nbsp;Hannah Whitby ,&nbsp;Rui Zhang ,&nbsp;Ingrid Obernosterer ,&nbsp;David Gonzalez-Santana ,&nbsp;Morgane Léon ,&nbsp;Pieter van Beek ,&nbsp;Virginie Sanial ,&nbsp;Catherine Jeandel ,&nbsp;Frédéric Vivier ,&nbsp;Maria-Elena Vorrath ,&nbsp;Wen-Hsuan Liao ,&nbsp;Yoan Germain ,&nbsp;Hélène Planquette","doi":"10.1016/j.marchem.2024.104401","DOIUrl":"https://doi.org/10.1016/j.marchem.2024.104401","url":null,"abstract":"<div><p>Iron (Fe) and manganese (Mn) are crucial micronutrients that limit oceanic primary productivity in the Southern Ocean. It has been recently suggested that hydrothermal activity may be an important source of oceanic dissolved iron, yet, this contribution is still not fully understood and only one active hydrothermal site has been reported on the Southwest Indian Ridge (SWIR), south of 40°S.</p><p>Using a multi-proxy approach, this study demonstrates the occurrence of hydrothermal venting on the SWIR in the near vicinity of the location 44°51.690 S, 36°10.460 E, which is likely to be a low or moderately high temperature fluid. Indeed, we report high values of dissolved methane to manganese ratios (up to 11.1 ± 1.2 mol mol⁻¹), low particulate iron (pFe) and manganese (pMn) concentrations (with maximum values of 0.7 nmol L⁻¹ and 0.06 nmol L⁻¹, respectively) associated with the presence of few oxyhydroxides, as well as high ²²³Radium (Ra) and ²²⁴Ra activities near the seafloor. The Fe and Mn data revealed a significant enrichment at depths influenced by hydrothermal circulation on the seafloor, within the Upper Circumpolar Deep Water. Dissolved Fe (dFe) and dissolved Mn (dMn) concentrations were enriched by 3- and 7-fold, respectively, and pFe and pMn by 2- and 1.5-fold, respectively, compared to a reference station located outside the SWIR. They were however lower than concentrations reported so far near high temperature vents, suggesting a weaker influence of this hydrothermal system on deep Fe and Mn reservoirs. We show that a large fraction of the dFe could be stabilized by organic complexation with humic substances (eHS, estimated 27–60% of dFe). High prokaryotic abundance related to the proximity of the hydrothermal vent suggests that other Fe-complexing ligands of biological origin might also stabilize Fe in its dissolved form. Collectively, these measurements integrated within the concept of a “multi-proxy approach”, helped painting a more detailed picture of the complex interactions and processes in this region of the SWIR. Although the system is a source of both dFe and dMn to the deep ocean, the low current velocities and the bathymetry likely limit the fertilization of surface water by dFe and dMn along this section of the SWIR.</p></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"265 ","pages":"Article 104401"},"PeriodicalIF":3.0,"publicationDate":"2024-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0304420324000525/pdfft?md5=381b461ab0a22124ecaec78631add07d&pid=1-s2.0-S0304420324000525-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141307939","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}

{"title":"Distribution of dissolved aluminum and dissolved iron in Kongsfjorden: A glacial fjord in the Arctic","authors":"Zhan Shen ,&nbsp;Ruifeng Zhang ,&nbsp;Jingling Ren ,&nbsp;Chris Marsay ,&nbsp;Zhuoyi Zhu ,&nbsp;Ying Wu ,&nbsp;Jing Zhang ,&nbsp;Seth John","doi":"10.1016/j.marchem.2024.104399","DOIUrl":"10.1016/j.marchem.2024.104399","url":null,"abstract":"<div><p>Iron plays a pivotal role in marine primary production and the carbon cycle. Glaciers have been recognized as a regional iron source to the ocean. Understanding both the endmember values and the transport processes of glacial iron passing through coastal waters to the ocean is essential to comprehend the fate and flux of iron derived from glaciers to the ocean. Fjords are typical coastal pathways in polar marine environments, connecting glacial meltwater to the open ocean. To better estimate iron transport from glacial meltwater to the ocean, we examined dissolved iron (dFe), dissolved aluminum (dAl), iron stable isotopes (δ⁵⁶Fe), and other biochemical parameters, including dissolved organic carbon, total suspended matter, and chlorophyll <em>a</em> in an Arctic fjord system, Kongsfjorden, Svalbard. In surface Kongsfjorden, low dFe levels averaging 5.23 ± 0.43 nM were detected in the inflow along the southern bank of the outer fjord, while elevated dFe concentrations were observed in both the inner and middle fjord regions (10.74 ± 5.22 nM), as well as in the outflow along the northern bank of the outer fjord (9.37 ± 2.85 nM). The association of dFe distribution with circulation patterns, in addition to the correlation between dFe and salinity, emphasizes that both glacial input and circulation regulate dFe distribution in Kongsfjorden. dFe and dAl endmember values from glacial meltwater were estimated as 82 ± 21 nM and 1089 ± 200.7 nM, respectively. The summer flux of glacier-derived dissolved iron and aluminum in Kongsfjorden were calculated to be 4.6–19 Mg/summer and 29 ± 5.4 Mg/summer, respectively. A short residence time for dFe in the Surface Water of Kongsfjorden was estimated at approximately a few days to a week, while dAl exhibited nearly conservative behavior, suggesting a possible application as a tracer for glacier input. The average δ⁵⁶Fe value in Kongsfjorden surface water was 0.08 ± 0.19‰, and our extrapolated glacial δ⁵⁶Fe input fingerprint ranged from 0.1‰ to 0.3‰ as iron traveled from the glacier towards the ocean. Our results emphasize the transport pattern of glacier-derived iron towards the ocean through Arctic fjord systems.</p></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"263 ","pages":"Article 104399"},"PeriodicalIF":3.0,"publicationDate":"2024-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141051647","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}

{"title":"Mechanisms controlling acidification resilience in the Yangtze River estuary: An index from buffering capacity","authors":"Qinyu Liu ,&nbsp;Junyang Wang ,&nbsp;Yanyi Miao ,&nbsp;Dewang Li ,&nbsp;Bin Wang ,&nbsp;Haiyan Jin ,&nbsp;Jianfang Chen","doi":"10.1016/j.marchem.2024.104400","DOIUrl":"10.1016/j.marchem.2024.104400","url":null,"abstract":"<div><p>Ocean acidification poses a substantial threat to global marine ecosystems, estuaries are more vulnerable to ocean acidification compared to open oceans due to their weaker buffering capacity. This study examined the carbonate parameters off the Yangtze River estuary (YRE) during summer 2019 and investigated seasonal variations in total alkalinity (TA) and dissolved inorganic carbon (DIC) transport in the lower Yangtze River in 2019. Monthly DIC (1566–2164 μmol/kg) and TA (1471–2128 μmol/kg) in the Yangtze River were negatively correlated with water discharge. Buffer factor (β_DIC) was calculated and used to evaluate the buffering capacity, which ranged from 65 to 256 μmol/kg and increased seaward along the YRE. Conservative mixing models indicated that the estuary had a minimum buffer zone (MBZ) at salinity of 2–9 during the high discharge periods. And the salinity of the MBZ was positively correlated with the riverine DIC:TA ratio. The construction of the Three Gorges Dam has resulted in a decrease in the Yangtze River's DIC:TA ratio, leading to the migration of the estuarine MBZ towards lower salinity regions. The effect of anthropogenic CO₂ invasion on estuarine buffering capacity was opposite to that of dam construction, leading to the migration of the estuarine MBZ towards higher salinity regions. Biological influences on the buffering capacity in the YRE were also quite considerable. Net autotrophy slightly enhanced the buffering capacity of the estuarine surface water, while net heterotrophy significantly weakened the buffering capacity of the estuarine bottom water. Eutrophication could intensify the biological influences on the buffering capacity. Globally, mid-latitude estuaries, such as the YRE, generally exhibit the strongest buffering capacity, while estuaries in Arctic regions tend to have the weakest buffering capacity.</p></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"263 ","pages":"Article 104400"},"PeriodicalIF":3.0,"publicationDate":"2024-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141053968","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}

{"title":"Microplastics reduce trace metal bioavailability in Thalassiosira weissflogii by impairing physiological functions","authors":"Yanting Du ,&nbsp;Qianyan Huang ,&nbsp;Shunxing Li ,&nbsp;Minggang Cai ,&nbsp;Fengjiao Liu ,&nbsp;Xuguang Huang ,&nbsp;Luxiu Lin ,&nbsp;Fengying Zheng ,&nbsp;Weijun Chen ,&nbsp;Ying Yang","doi":"10.1016/j.marchem.2024.104402","DOIUrl":"https://doi.org/10.1016/j.marchem.2024.104402","url":null,"abstract":"<div><p>Microplastics (MPs) have been recognized globally as a new environmental pollutant and can be transported in water environments all over the world. Diatoms contribute about 20% of marine primary productivity and play an important role in global carbon sequestration, climate regulation, and the biogeochemical cycling of biogenic elements. Understanding the impact of MPs on the primary biomass productivity of phytoplankton is crucial for assessing ecosystem resilience and maintaining essential ecosystem services. Here the relationships between phytoplankton physiological indicators and trace metal uptake were investigated to delineate how polystyrene microplastics (PS-MPs) affect the primary biomass productivity and alter the dynamics of trace metal sinks in marine ecosystems. We innovatively proposed that the influence of MPs on phytoplankton was not only shading effects on algae and causing oxidative damage, but also limiting the accumulation of trace metals in algae. The accumulation of Mn, Fe and Ni in algae is positively correlated with the content of chlorophyll <em>a</em> (Mn: <em>r</em> = 0.824; Fe: <em>r</em> = 0.697; Ni: <em>r</em> = 0.822), photosynthetic activity (Mn: <em>r</em> = 0.631; Fe: <em>r</em> = 0.467; Ni: <em>r</em> = 0.816) and β-carotene (Mn: <em>r</em> = 0.773; Fe: <em>r</em> = 0.307; Ni: <em>r</em> = 0.786), but negatively correlated with superoxide dismutase activity (Mn: <em>r</em> = −0.714; Fe: <em>r</em> = −0.730; Ni: <em>r</em> = −0.908). This provides a new perspective to reveal the influence mechanisms of MPs on primary biomass and trace metal sinks.</p></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"263 ","pages":"Article 104402"},"PeriodicalIF":3.0,"publicationDate":"2024-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140950059","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}

{"title":"Simultaneous determination of picomolar level of dissolved silver with other key trace metals in seawater samples using solid phase extraction and isotope dilution methods","authors":"Kuo Hong Wong ,&nbsp;Keisuke Nishitani ,&nbsp;Hajime Obata ,&nbsp;Hideki Fukuda ,&nbsp;Hiroshi Ogawa ,&nbsp;Farah Akmal Idrus ,&nbsp;Fatimah A'tirah binti Mohamad ,&nbsp;Asami S. Mashio ,&nbsp;Hiroshi Hasegawa","doi":"10.1016/j.marchem.2024.104396","DOIUrl":"https://doi.org/10.1016/j.marchem.2024.104396","url":null,"abstract":"<div><p>Simultaneous determination of dissolved silver (dAg) with other key GEOTRACES trace metals is difficult because dAg in seawater tends to form negatively charged chloride species that result in only 75% recovery efficiency with commonly used NOBIAS PA-1 chelating resins. In this study, we developed a method using solid phase extraction coupled with isotope dilution that enables full quantification (97.9 ± 2.1%) of dAg along with other major trace metals including cadmium (Cd), copper (Cu), manganese (Mn), nickel (Ni), and lead (Pb) (recovery efficiency = 100% to 102%) in seawater samples. Seawater samples were first spiked with Ag-109 and allowed to reach isotopic equilibrium before extraction using NOBIAS PA-1 chelating resin. Then, dAg isotope ratios (Ag-109/Ag-107) before and after solid phase extraction were determined and used to quantify dAg. Determination of dAg with dissolved Cd, Cu. Mn, Ni, and Pb in reference seawater material CASS-6 resulted in deviations of between 1.0% and 8.8% from the consensus values, which are well within the standard error of measurement. We then successfully determined the concentrations of dissolved Cd (0.05–0.2 nM), Cu (0.5–13 nM), Mn (10–140 nM), Ni (2–12 nM), Pb (5–110 nM), and Ag (10–40 pM) in Otsuchi Bay, Japan and its surrounding rivers. Evaluation of the behavior of dAg under a salinity gradient using estuarine samples collected from Samunsam River, Malaysia shows increasing dAg concentration with salinity (R² = 0.68), which suggests release of sedimental Ag under high ambient chloride concentrations. Our new method enables rapid and simultaneous measurements of dAg with other key GEOTRACES trace metals in a single analysis, which is expected to expedite analysis and increase availability of oceanic dAg data globally.</p></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"262 ","pages":"Article 104396"},"PeriodicalIF":3.0,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140893619","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}

{"title":"Characterizing the stable oxygen isotopic composition of the southeast Indian Ocean","authors":"Ryan H. Glaubke ,&nbsp;Amy J. Wagner ,&nbsp;Elisabeth L. Sikes","doi":"10.1016/j.marchem.2024.104397","DOIUrl":"https://doi.org/10.1016/j.marchem.2024.104397","url":null,"abstract":"<div><p>New seawater stable oxygen isotope (δ¹⁸O) samples were collected from the southeast Indian Ocean as part of the Coring to Reconstruct Ocean Circulation and Carbon dioxide Across 2 Seas (CROCCA-2S) expedition in November – December of 2018. These data fill a gap in the δ¹⁸O sampling coverage of the southern Indian basin, providing new insights into the hydrologic and oceanographic processes influencing the δ¹⁸O distribution of the region and its relationship to salinity in the upper ocean. Our surface ocean data (&lt;100 m)—in combination with decades of observations from the broader south Indian Ocean—show distinct δ¹⁸O – salinity characteristics on either side of ∼85°E. The balance between evaporation and precipitation yields a strong, robust δ¹⁸O – salinity relationship west of 85°E (δ¹⁸O = 0.50(±0.01) * S – 17.2(±0.22)). However, within the mesoscale eddy field initiated by the Leeuwin Current further east (∼85–120°E), our observations fall along a mixing line between the southwest Indian Ocean and data collected from the Australian coastal margin, illustrating for the first time how the unique eastern boundary system of the south Indian Ocean drives regional-scale variability in the δ¹⁸O – salinity relationship of the surface ocean. A comparison between our observations in the shallow subsurface (100–1000 m) and those from neighboring surveys reinforces this upper ocean connection across the Indo-Australian basin. Antarctic Intermediate Water from the Indian Ocean can be isotopically distinguished from the more regional Tasman Intermediate Water occupying the South Australian Bight, suggesting exchange between the two regions is most prevalent at surface and mode water depths. In deeper waters (&gt; ∼1500 m), we observe a notable 0.87‰ spread in δ¹⁸O. This variability may represent interactions between distinct deep water masses in the region, although additional data are needed to confirm. Overall, our data provide a new look at the hydrography and isotopic chemistry of the southeast Indian Ocean, emphasizing the impact of the region's mesoscale eddy field and its interconnectivity with neighboring basins.</p></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"262 ","pages":"Article 104397"},"PeriodicalIF":3.0,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140880015","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}