Pub Date : 2025-07-01Epub Date: 2025-06-18DOI: 10.1016/j.marchem.2025.104531
Rianne J.M. van Kaam, Martin Kölling, Marcus Elvert, Kai-Uwe Hinrichs, Matthias Zabel
Dust deposition to the ocean plays an indirect role in the carbon cycle due to stimulating the primary production by fertilisation. Additionally, it transports carbon to the ocean floor by acting as ballast for marine aggregates. Despite these recognized impacts, the direct influence of dust-seawater interactions on the carbon cycle remains poorly understood. Here, we study the effects of mineral dust on the dissolved organic carbon (DOC) concentration in seawater by performing sorption experiments through time series and stable carbon isotope analysis. We added two different amounts of dust to a solution of artificial seawater and 13C-labelled dissolved organic matter from Spirulina extract, creating a low and high dust-seawater ratio system. After 72 h, we observe a decrease in DOC for both systems, indicating the adsorption of DOC from the Spirulina extract onto dust particles. Analysis of the stable carbon isotope ratios of total organic carbon on the dust samples, before and after the sorption experiments, confirms these findings. Furthermore, our study shows that the net uptake of DOC on dust depends on the relative importance of adsorption, release and degradation of organic carbon. DOC release can become the dominant process based on the dust-seawater ratio and the initial organic carbon present on the dust, demonstrating that dust can act as both a sink and a source of organic carbon in the near-surface waters.
{"title":"Dust deposition directly affects the concentration of dissolved organic carbon in the ocean","authors":"Rianne J.M. van Kaam, Martin Kölling, Marcus Elvert, Kai-Uwe Hinrichs, Matthias Zabel","doi":"10.1016/j.marchem.2025.104531","DOIUrl":"10.1016/j.marchem.2025.104531","url":null,"abstract":"<div><div>Dust deposition to the ocean plays an indirect role in the carbon cycle due to stimulating the primary production by fertilisation. Additionally, it transports carbon to the ocean floor by acting as ballast for marine aggregates. Despite these recognized impacts, the direct influence of dust-seawater interactions on the carbon cycle remains poorly understood. Here, we study the effects of mineral dust on the dissolved organic carbon (DOC) concentration in seawater by performing sorption experiments through time series and stable carbon isotope analysis. We added two different amounts of dust to a solution of artificial seawater and <sup>13</sup>C-labelled dissolved organic matter from <em>Spirulina</em> extract, creating a low and high dust-seawater ratio system. After 72 h, we observe a decrease in DOC for both systems, indicating the adsorption of DOC from the <em>Spirulina</em> extract onto dust particles. Analysis of the stable carbon isotope ratios of total organic carbon on the dust samples, before and after the sorption experiments, confirms these findings. Furthermore, our study shows that the net uptake of DOC on dust depends on the relative importance of adsorption, release and degradation of organic carbon. DOC release can become the dominant process based on the dust-seawater ratio and the initial organic carbon present on the dust, demonstrating that dust can act as both a sink and a source of organic carbon in the near-surface waters.</div></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"271 ","pages":"Article 104531"},"PeriodicalIF":3.0,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144557449","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 : 2025-07-01Epub Date: 2025-06-26DOI: 10.1016/j.marchem.2025.104533
Qixian Chen , Yifan Li , Chen-Tung Arthur Chen , Zong-Pei Jiang , Wei-Jun Cai , Hongwen Pan , Yunwen Shen , Zesheng Ding , Yanan Di , Chenba Zhu , Nianzhi Jiao , Yiwen Pan
Diatoms play a pivotal role in the ocean, contributing approximately 40 % of marine primary production, with nearly half of the particulate organic carbon being exported. The recent discovery of a novel diatom-induced calcification pathway has attracted significant attention due to its implications for marine carbon, calcium, and silicon cycling. Despite its potential, the lack of a quantitative initiation threshold and comparative analysis with known calcifying organisms limit our ability to predict its ecological impact, particularly on carbon sequestration. This study addresses these gaps by cultivating the common diatom species, Skeletonema costatum, under simulated marine conditions to evaluate its CaCO3 precipitation potential and define the biogeochemical threshold for calcification. The experimental results showed that S. costatum can induce calcification across a range of environmental conditions, including varying dissolved inorganic carbon (DIC 1837 to 2709 μmol·kg−1), nitrogen sources (NH4+ or NO3−), and cell densities (104 to 105 cells·mL−1). Calcification was initiated when the aragonite saturation state (Ωarag) exceeded ∼8. The calcification rate exhibits a linear correlation with Ωarag in the bulk solution, categorizing it as a “biologically induced” process. Our findings highlight similarities between the calcification mechanisms of S. costatum and other calcifying organisms, revealing the common ality of environmental drivers. This study advances our understanding of diatom-induced calcification, offering insights into its role in the marine carbon cycle and potential contributions to carbon sequestration strategies.
{"title":"Diatom-induced calcification in coastal marine environments: Biomineralization threshold and mechanism","authors":"Qixian Chen , Yifan Li , Chen-Tung Arthur Chen , Zong-Pei Jiang , Wei-Jun Cai , Hongwen Pan , Yunwen Shen , Zesheng Ding , Yanan Di , Chenba Zhu , Nianzhi Jiao , Yiwen Pan","doi":"10.1016/j.marchem.2025.104533","DOIUrl":"10.1016/j.marchem.2025.104533","url":null,"abstract":"<div><div>Diatoms play a pivotal role in the ocean, contributing approximately 40 % of marine primary production, with nearly half of the particulate organic carbon being exported. The recent discovery of a novel diatom-induced calcification pathway has attracted significant attention due to its implications for marine carbon, calcium, and silicon cycling. Despite its potential, the lack of a quantitative initiation threshold and comparative analysis with known calcifying organisms limit our ability to predict its ecological impact, particularly on carbon sequestration. This study addresses these gaps by cultivating the common diatom species, <em>Skeletonema costatum</em>, under simulated marine conditions to evaluate its CaCO<sub>3</sub> precipitation potential and define the biogeochemical threshold for calcification. The experimental results showed that <em>S. costatum</em> can induce calcification across a range of environmental conditions, including varying dissolved inorganic carbon (DIC 1837 to 2709 μmol·kg<sup>−1</sup>), nitrogen sources (NH<sub>4</sub><sup>+</sup> or NO<sub>3</sub><sup>−</sup>), and cell densities (10<sup>4</sup> to 10<sup>5</sup> cells·mL<sup>−1</sup>). Calcification was initiated when the aragonite saturation state (Ω<sub>arag</sub>) exceeded ∼8. The calcification rate exhibits a linear correlation with Ω<sub>arag</sub> in the bulk solution, categorizing it as a “biologically induced” process. Our findings highlight similarities between the calcification mechanisms of <em>S. costatum</em> and other calcifying organisms, revealing the common ality of environmental drivers. This study advances our understanding of diatom-induced calcification, offering insights into its role in the marine carbon cycle and potential contributions to carbon sequestration strategies.</div></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"271 ","pages":"Article 104533"},"PeriodicalIF":3.0,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144524021","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 : 2025-05-01Epub Date: 2025-02-21DOI: 10.1016/j.marchem.2025.104508
E.L.S. Ortega, I. Reister, S.L. Danielson, A.M. Aguilar-Islas
The Copper River is a major source of freshwater to the Northern Gulf of Alaska (NGA) shelf with a seasonal cycle that reaches peak discharge in summer. This glacially-fed river also provides a large input of dissolved chemicals to the NGA, and because of its large particle load, it impacts the distribution of particle-reactive elements. Summertime sampling of shelf water properties was carried out within the Copper River plume region during two years: first during a period of upwelling-favorable winds and higher river discharge (4–7 July 2019) and later during lower river discharge and more typical downwelling conditions (11–13 July 2020). Although these wind conditions were observed in separate years, both can occur over the course of a single summer. We found that the export of most nutrients to surface shelf waters was enhanced under upwelling-favorable winds accompanied by higher river discharge compared to downwelling conditions and lower discharge. For example, greater cross-shelf plume transport in 2019 resulted in higher mid-shelf surface inventories for nitrate + nitrite (N + N), silicic acid (H4SiO4), phosphate (PO43−), dissolved Fe (dFe), and dissolved Cu (dCu) compared to 2020. Entrainment of relatively macronutrient-rich subsurface waters under upwelling conditions may also have contributed to the enhancement of these mid-shelf nutrient inventories. The observed high N:P ratios in plume waters were likely driven by the scavenging of P within particle-laden plume waters. Similarly, we observed lower than expected [dFe] (1.58 to 6.12 nM) in particle-laden plume waters, likely a result of enhanced scavenging combined with low concentrations of dissolved Fe-binding ligands. Although dNi and dZn have a river source, we observed lower concentrations in surface shelf waters under upwelling conditions, suggesting enhanced dilution by relatively micronutrient-poor subsurface waters. Results highlight the influence of sub-seasonal variations in atmospheric forcing on nutrient distributions and suggest that this forcing also impacts the location and timing of primary production hotspots during summer, adding to the ecological mosaic of the NGA across a range of temporal and spatial scales.
{"title":"Surface macro- and micro-nutrients within the Copper River plume region respond to along-shore winds","authors":"E.L.S. Ortega, I. Reister, S.L. Danielson, A.M. Aguilar-Islas","doi":"10.1016/j.marchem.2025.104508","DOIUrl":"10.1016/j.marchem.2025.104508","url":null,"abstract":"<div><div>The Copper River is a major source of freshwater to the Northern Gulf of Alaska (NGA) shelf with a seasonal cycle that reaches peak discharge in summer. This glacially-fed river also provides a large input of dissolved chemicals to the NGA, and because of its large particle load, it impacts the distribution of particle-reactive elements. Summertime sampling of shelf water properties was carried out within the Copper River plume region during two years: first during a period of upwelling-favorable winds and higher river discharge (4–7 July 2019) and later during lower river discharge and more typical downwelling conditions (11–13 July 2020). Although these wind conditions were observed in separate years, both can occur over the course of a single summer. We found that the export of most nutrients to surface shelf waters was enhanced under upwelling-favorable winds accompanied by higher river discharge compared to downwelling conditions and lower discharge. For example, greater cross-shelf plume transport in 2019 resulted in higher mid-shelf surface inventories for nitrate + nitrite (N + N), silicic acid (H<sub>4</sub>SiO<sub>4</sub>), phosphate (PO<sub>4</sub><sup>3−</sup>), dissolved Fe (dFe), and dissolved Cu (dCu) compared to 2020. Entrainment of relatively macronutrient-rich subsurface waters under upwelling conditions may also have contributed to the enhancement of these mid-shelf nutrient inventories. The observed high N:P ratios in plume waters were likely driven by the scavenging of P within particle-laden plume waters. Similarly, we observed lower than expected [dFe] (1.58 to 6.12 nM) in particle-laden plume waters, likely a result of enhanced scavenging combined with low concentrations of dissolved Fe-binding ligands. Although dNi and dZn have a river source, we observed lower concentrations in surface shelf waters under upwelling conditions, suggesting enhanced dilution by relatively micronutrient-poor subsurface waters. Results highlight the influence of sub-seasonal variations in atmospheric forcing on nutrient distributions and suggest that this forcing also impacts the location and timing of primary production hotspots during summer, adding to the ecological mosaic of the NGA across a range of temporal and spatial scales.</div></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"270 ","pages":"Article 104508"},"PeriodicalIF":3.0,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143510835","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 : 2025-05-01Epub Date: 2025-04-09DOI: 10.1016/j.marchem.2025.104516
Elisabetta Canuti , F. Artuso , A. Di Cicco
High-performance liquid chromatography (HPLC) is the gold standard for calibrating and validating satellite-derived Chlorophyll a (TChl a) concentration. Other phytoplankton pigments quantified by HPLC can provide taxonomic and functional insights into the composition and abundance of phytoplankton communities. This study assesses the uncertainties associated with HPLC measurements by comparing results from two analytical laboratories, one from the Joint Research Centre (JRC) and the other from the Italian National Agency for New Technologies, Energy, and Sustainable Economic Development (ENEA). These laboratories employed different analytical methods to examine natural water samples from the oligotrophic waters of the Western Mediterranean Sea, collected during the Sentinel 2017 campaign. Chlorophyll a concentrations in these samples ranged from 0.048 to 0.653 mg m−3 in the JRC dataset. The present study evaluated phytoplankton community composition using multiple techniques, including chemotaxonomic methods based on the analysis of biomarker pigments and CHEMTAX method (Mackey et al., 1996), alongside unsupervised machine learning approaches such as Hierarchical Clustering Analysis (HCA), Principal Components Analysis (PCA), and Network-Community Analysis (NCA). Significant differences in pigment quantification were observed between the two laboratories, particularly for chlorophylls c (85.5 % difference) and peridinin (56.6 % difference). However, differences in total TChl a quantification were within 6.1 %, indicating that both laboratories are capable of supporting satellite data validation and algorithm development (Hooker et al., 2000). The results highlighted both limitations and advantages of this comparative approach, related to different methods for estimating uncertainties, providing insights into the consistency and reliability of HPLC measurements in a challenging low concentration matrix.
高效液相色谱法（HPLC）是校准和验证卫星衍生叶绿素a （TChl a）浓度的金标准。其他浮游植物色素的定量可以为浮游植物群落的组成和丰度提供分类和功能方面的见解。本研究通过比较两个分析实验室（一个来自联合研究中心（JRC），另一个来自意大利国家新技术、能源和可持续经济发展机构（ENEA））的结果来评估与HPLC测量相关的不确定度。这些实验室采用了不同的分析方法来检查西地中海寡营养水域的天然水样，这些水样是在2017年哨兵行动期间收集的。在JRC数据集中，这些样品中的叶绿素a浓度范围为0.048至0.653 mg m - 3。本研究使用多种技术评估浮游植物群落组成，包括基于生物标记色素分析的化学分类方法和CHEMTAX方法（Mackey et al., 1996），以及无监督机器学习方法，如层次聚类分析（HCA）、主成分分析（PCA）和网络群落分析（NCA）。两个实验室在色素定量方面存在显著差异，特别是叶绿素c（差异85.5%）和橄榄素（差异56.6%）。然而，总TChl a量化的差异在6.1%以内，这表明两个实验室都有能力支持卫星数据验证和算法开发（Hooker et al., 2000）。结果强调了这种比较方法的局限性和优点，涉及到不同的方法来估计不确定度，为HPLC测量在具有挑战性的低浓度矩阵中的一致性和可靠性提供了见解。
{"title":"Comparative analysis of HPLC methods for measuring phytoplankton pigments in the Western Mediterranean Sea: A contribution to the satellite Cal/Val activities","authors":"Elisabetta Canuti , F. Artuso , A. Di Cicco","doi":"10.1016/j.marchem.2025.104516","DOIUrl":"10.1016/j.marchem.2025.104516","url":null,"abstract":"<div><div>High-performance liquid chromatography (HPLC) is the gold standard for calibrating and validating satellite-derived Chlorophyll <em>a</em> (TChl <em>a</em>) concentration. Other phytoplankton pigments quantified by HPLC can provide taxonomic and functional insights into the composition and abundance of phytoplankton communities. This study assesses the uncertainties associated with HPLC measurements by comparing results from two analytical laboratories, one from the Joint Research Centre (JRC) and the other from the Italian National Agency for New Technologies, Energy, and Sustainable Economic Development (ENEA). These laboratories employed different analytical methods to examine natural water samples from the oligotrophic waters of the Western Mediterranean Sea, collected during the Sentinel 2017 campaign. Chlorophyll <em>a</em> concentrations in these samples ranged from 0.048 to 0.653 mg m<sup>−3</sup> in the JRC dataset. The present study evaluated phytoplankton community composition using multiple techniques, including chemotaxonomic methods based on the analysis of biomarker pigments and CHEMTAX method (<span><span>Mackey et al., 1996</span></span>), alongside unsupervised machine learning approaches such as Hierarchical Clustering Analysis (HCA), Principal Components Analysis (PCA), and Network-Community Analysis (NCA). Significant differences in pigment quantification were observed between the two laboratories, particularly for chlorophylls <em>c</em> (85.5 % difference) and peridinin (56.6 % difference). However, differences in total TChl <em>a</em> quantification were within 6.1 %, indicating that both laboratories are capable of supporting satellite data validation and algorithm development (Hooker et al., 2000). The results highlighted both limitations and advantages of this comparative approach, related to different methods for estimating uncertainties, providing insights into the consistency and reliability of HPLC measurements in a challenging low concentration matrix.</div></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"270 ","pages":"Article 104516"},"PeriodicalIF":3.0,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143851334","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 : 2025-05-01Epub Date: 2025-02-21DOI: 10.1016/j.marchem.2025.104509
Matthew Corkill , Klaus Martin Meiners , Pat Wongpan , Pier van der Merwe , Layla Creac'h , Sandrin Feig , Talitha Nelson , Abigail Jessica Rose Smith , Ashley T. Townsend , Samantha Twiname , Delphine Lannuzel
Primary productivity by phytoplankton in the Southern Ocean can be limited by low iron concentrations. Iron limitation in the surface ocean around Antarctica may be alleviated by particle dissolution of dust from exposed rock, glacial flour, resuspended marine sediment, and sea ice. Ligands, which are ubiquitous in seawater, chelate some metals and keep them in solution. Ligands are thereby thought to increase metal solubility, including iron. Leaching studies of Antarctic particles from various sources are rare but important due to observed and predicted changes occurring around Antarctica, e.g., changes in sea ice and ice-free areas on the continent. Here, we quantified the solubility of iron in different particle types using vertical flow-through leaching experiments that simulated sinking through the water column and ran for 78 min of flow at 4 °C under trace metal-clean conditions. Both unaltered and ultraviolet-irradiated seawater leaching solution treatments were used to test the effect of organic ligands on iron dissolution, which was found to be non-significant. Sediment and dust released the most dissolved iron to seawater, followed by glacial flour, and then sea-ice particles (9.00 ± 9.92 × 10−2 and 3.18 ± 3.79 × 10−2, 1.97 ± 1.79 × 10−4, 1.37 ± 0.90 × 10−9 g DFe/100 g material, respectively). We discuss these laboratory results in relation to particle availability and how this may affect the supply of dissolved iron to Antarctic surface waters.
{"title":"Dissolved iron release by sediment and dust particles in Antarctic seawater greater than glacial flour and sea-ice particles","authors":"Matthew Corkill , Klaus Martin Meiners , Pat Wongpan , Pier van der Merwe , Layla Creac'h , Sandrin Feig , Talitha Nelson , Abigail Jessica Rose Smith , Ashley T. Townsend , Samantha Twiname , Delphine Lannuzel","doi":"10.1016/j.marchem.2025.104509","DOIUrl":"10.1016/j.marchem.2025.104509","url":null,"abstract":"<div><div>Primary productivity by phytoplankton in the Southern Ocean can be limited by low iron concentrations. Iron limitation in the surface ocean around Antarctica may be alleviated by particle dissolution of dust from exposed rock, glacial flour, resuspended marine sediment, and sea ice. Ligands, which are ubiquitous in seawater, chelate some metals and keep them in solution. Ligands are thereby thought to increase metal solubility, including iron. Leaching studies of Antarctic particles from various sources are rare but important due to observed and predicted changes occurring around Antarctica, e.g., changes in sea ice and ice-free areas on the continent. Here, we quantified the solubility of iron in different particle types using vertical flow-through leaching experiments that simulated sinking through the water column and ran for 78 min of flow at 4 °C under trace metal-clean conditions. Both unaltered and ultraviolet-irradiated seawater leaching solution treatments were used to test the effect of organic ligands on iron dissolution, which was found to be non-significant. Sediment and dust released the most dissolved iron to seawater, followed by glacial flour, and then sea-ice particles (9.00 ± 9.92 × 10<sup>−2</sup> and 3.18 ± 3.79 × 10<sup>−2</sup>, 1.97 ± 1.79 × 10<sup>−4</sup>, 1.37 ± 0.90 × 10<sup>−9</sup> g DFe/100 g material, respectively). We discuss these laboratory results in relation to particle availability and how this may affect the supply of dissolved iron to Antarctic surface waters.</div></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"270 ","pages":"Article 104509"},"PeriodicalIF":3.0,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143510834","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 : 2025-05-01Epub Date: 2025-03-20DOI: 10.1016/j.marchem.2025.104514
Nabila Abbad , Roland Redon , Benjamin Oursel , Christophe Lepoupon , Gaël Durrieu , Houssam Hajjoul , Stéphane Mounier
This study investigates the speciation of Samarium (III) in the presence of natural organic matter, standard humic and fulvic acids from the Suwannee River. Fluorescence quenching and Time-Resolved Laser Fluorescence Spectroscopy (TRLFS) were employed to analyze various samples, using logarithmic additions of Sm3+ and Cu2+. The 1 L:1 M and 1 L:1 M:H models were applied to account for pH effects, yielding pH-independent complexant parameters KSm and KCu as well as that revealed specific binding sites. A notably higher affinity was observed for humic acids with Sm3+ compared to Cu2+. The logarithms of the complexation constant for the Sm3+ were 5.4, 5.2 and 4.7 for SRNOM, SRHA and SRFA, respectively. Fluorescence quenching analyses identified two distinct fluorescent components related to dissolved organic matter, showing different affinities for Sm3+ and Cu2+ that varied with pH. Humic acids exhibited the highest complexation capacity for Sm3+, attributed to their structural properties, with complexation capacities of 4.77 10−4, 0.82 and 4.46 10−3 mol of Sm per g of SRNOM, SRHA and SRFA, respectively. Temporal deconvolution of fluorescence responses revealed a tri-exponential decay with three lifetimes (τ1, τ2 and τ3) remaining relatively constant during Sm3+ or Cu2+ titrations, confirming that the fluorescence quenching is primarily a static mechanism. Speciation modeling demonstrated a shift from humic-associated complexes in freshwater to carbonate complexes in seawater as salinity increases. These findings highlight the importance of accurately characterizing DOM complexation properties to understand the environmental behavior of trace metals, particularly in response to salinity and carbon concentration gradients in estuarine systems.
{"title":"Samarium (Sm3+) and copper (Cu2+) complexation property with dissolved organic matter","authors":"Nabila Abbad , Roland Redon , Benjamin Oursel , Christophe Lepoupon , Gaël Durrieu , Houssam Hajjoul , Stéphane Mounier","doi":"10.1016/j.marchem.2025.104514","DOIUrl":"10.1016/j.marchem.2025.104514","url":null,"abstract":"<div><div>This study investigates the speciation of Samarium (III) in the presence of natural organic matter, standard humic and fulvic acids from the Suwannee River. Fluorescence quenching and Time-Resolved Laser Fluorescence Spectroscopy (TRLFS) were employed to analyze various samples, using logarithmic additions of Sm<sup>3+</sup> and Cu<sup>2+</sup>. The 1 L:1 M and 1 L:1 M:H models were applied to account for pH effects, yielding pH-independent complexant parameters K<sub>Sm</sub> and K<sub>Cu</sub> as well as <span><math><msub><mi>C</mi><msub><mi>L</mi><mi>Sm</mi></msub></msub><mspace></mspace><mi>and</mi><mspace></mspace><msub><mi>C</mi><msub><mi>L</mi><mi>Cu</mi></msub></msub></math></span>that revealed specific binding sites. A notably higher affinity was observed for humic acids with Sm<sup>3+</sup> compared to Cu<sup>2+</sup>. The logarithms of the complexation constant for the Sm<sup>3+</sup> were 5.4, 5.2 and 4.7 for SRNOM, SRHA and SRFA, respectively. Fluorescence quenching analyses identified two distinct fluorescent components related to dissolved organic matter, showing different affinities for Sm<sup>3+</sup> and Cu<sup>2+</sup> that varied with pH. Humic acids exhibited the highest complexation capacity for Sm<sup>3+</sup>, attributed to their structural properties, with complexation capacities of 4.77 10<sup>−4</sup>, 0.82 and 4.46 10<sup>−3</sup> mol of Sm per g of SRNOM, SRHA and SRFA, respectively. Temporal deconvolution of fluorescence responses revealed a tri-exponential decay with three lifetimes (τ<sub>1</sub>, τ<sub>2</sub> and τ<sub>3</sub>) remaining relatively constant during Sm<sup>3+</sup> or Cu<sup>2+</sup> titrations, confirming that the fluorescence quenching is primarily a static mechanism. Speciation modeling demonstrated a shift from humic-associated complexes in freshwater to carbonate complexes in seawater as salinity increases. These findings highlight the importance of accurately characterizing DOM complexation properties to understand the environmental behavior of trace metals, particularly in response to salinity and carbon concentration gradients in estuarine systems.</div></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"270 ","pages":"Article 104514"},"PeriodicalIF":3.0,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143738842","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 : 2025-05-01Epub Date: 2025-03-19DOI: 10.1016/j.marchem.2025.104513
Saša Marcinek, Ana-Marija Cindrić, Dario Omanović
This work presents a detailed analysis of seasonal changes in copper (Cu) organic speciation and its bioavailability in the Krka River estuary, a highly stratified microtidal system characterized by low riverine input of dissolved organic matter (DOM) and trace metals but experiencing heightened anthropogenic Cu pressures during summer as a result of increased touristic activities. Total dissolved Cu concentrations ranged from 3.4 nmol L−1 in winter up to 25.8 nmol L−1 in summer, with substantial summer increase limited to water layer above the halocline. Two distinct ligand classes were identified in all samples, with conditional stability constants of logK’1 = 13.2 ± 0.5 and logK’2 = 11.2 ± 0.4. Dissolved organic carbon (DOC) and concentrations of both ligand classes were higher in summer than in winter, with strong indications of their in situ production driven by enhanced primary production and/or intensified microbial activity. In winter, despite the low DOC levels (avg 63.3 μmol L−1), DOM above the halocline showed pronounced terrestrial signature with higher density of Cu-binding sites compared to DOM in summer with nearly twice as high DOC levels (avg 113.5 μmol L−1). The results suggest that terrestrial humic substances (HS) dominated the ligand pool in these waters during winter (estimated 80 % of total ligand pool), possibly contributing to both ligand classes. While HS remained an important fraction of the ligand pool in the summer (estimated 30 % of total ligand pool), the terrestrial signature of DOM in this season was minimal, pointing to their production within the estuary. The summer increase in ligand concentrations above the halocline was accompanied by a reduction in their binding strengths (by approximately 0.5 log units) compared to winter, along with a decrease in DOM molecular weight, possibly influenced by solar irradiation. Seasonal anthropogenic Cu input was successfully buffered by the ambient ligand pool, keeping the concentration of free Cu-ions, its most bioavailable specie, well below documented toxicity levels for Cu (maximum of 2.54 pmol L−1). The seasonal DOM variations resulted in a ∼ two-fold increase in the Cu-binding capacity in summer (33 nmol L−1) compared to winter (17 nmol L−1). Despite the increased buffering capacity in summer, Cu levels are approaching this safety limit, which may increase its bioavailability to a concerning level, a risk much lower in winter when Cu inputs are minimal. These results underscore the critical role of DOM in mitigating seasonal anthropogenic Cu inputs, while also highlighting the need for further investigation into the long-term resilience of estuarine systems under shifting environmental and anthropogenic pressures.
{"title":"Influence of seasonal changes in organic matter pool on copper bioavailability in a stratified estuary","authors":"Saša Marcinek, Ana-Marija Cindrić, Dario Omanović","doi":"10.1016/j.marchem.2025.104513","DOIUrl":"10.1016/j.marchem.2025.104513","url":null,"abstract":"<div><div>This work presents a detailed analysis of seasonal changes in copper (Cu) organic speciation and its bioavailability in the Krka River estuary, a highly stratified microtidal system characterized by low riverine input of dissolved organic matter (DOM) and trace metals but experiencing heightened anthropogenic Cu pressures during summer as a result of increased touristic activities. Total dissolved Cu concentrations ranged from 3.4 nmol L<sup>−1</sup> in winter up to 25.8 nmol L<sup>−1</sup> in summer, with substantial summer increase limited to water layer above the halocline. Two distinct ligand classes were identified in all samples, with conditional stability constants of log<em>K</em>’<sub>1</sub> = 13.2 ± 0.5 and log<em>K</em>’<sub>2</sub> = 11.2 ± 0.4. Dissolved organic carbon (DOC) and concentrations of both ligand classes were higher in summer than in winter, with strong indications of their in situ production driven by enhanced primary production and/or intensified microbial activity. In winter, despite the low DOC levels (avg 63.3 μmol L<sup>−1</sup>), DOM above the halocline showed pronounced terrestrial signature with higher density of Cu-binding sites compared to DOM in summer with nearly twice as high DOC levels (avg 113.5 μmol L<sup>−1</sup>). The results suggest that terrestrial humic substances (HS) dominated the ligand pool in these waters during winter (estimated 80 % of total ligand pool), possibly contributing to both ligand classes. While HS remained an important fraction of the ligand pool in the summer (estimated 30 % of total ligand pool), the terrestrial signature of DOM in this season was minimal, pointing to their production within the estuary. The summer increase in ligand concentrations above the halocline was accompanied by a reduction in their binding strengths (by approximately 0.5 log units) compared to winter, along with a decrease in DOM molecular weight, possibly influenced by solar irradiation. Seasonal anthropogenic Cu input was successfully buffered by the ambient ligand pool, keeping the concentration of free Cu-ions, its most bioavailable specie, well below documented toxicity levels for Cu (maximum of 2.54 pmol L<sup>−1</sup>). The seasonal DOM variations resulted in a ∼ two-fold increase in the Cu-binding capacity in summer (33 nmol L<sup>−1</sup>) compared to winter (17 nmol L<sup>−1</sup>). Despite the increased buffering capacity in summer, Cu levels are approaching this safety limit, which may increase its bioavailability to a concerning level, a risk much lower in winter when Cu inputs are minimal. These results underscore the critical role of DOM in mitigating seasonal anthropogenic Cu inputs, while also highlighting the need for further investigation into the long-term resilience of estuarine systems under shifting environmental and anthropogenic pressures.</div></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"270 ","pages":"Article 104513"},"PeriodicalIF":3.0,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143682117","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 : 2025-05-01Epub Date: 2025-02-20DOI: 10.1016/j.marchem.2025.104500
Billie G.B. Benedict , Rebecca Zitoun , Keith A. Hunter , Sylvia G. Sander
A comprehensive study was conducted in a river estuary and marina in Auckland, New Zealand, to examine the in-situ speciation of copper (Cu) complexes across freshwater, estuarine, and marine environments using the diffusive gradient in thin films (DGT) technique. The study employed both open-pore (OP) and restrictive-pore (RP) diffusive gels of varying thicknesses to assess the effectiveness of DGT hydrogels and the role of the apparent diffusive boundary layer (ADBL) in determining the lability of Cu complexes in natural waters. The DGT findings were compared with results from competing ligand exchange–adsorptive stripping voltammetry (CLE-AdSV) and a speciation prediction model (WHAM/Model-VII). The study highlighted the critical importance of accounting for the ADBL, as its exclusion led to an average underestimation of Cu-complex lability by approximately 50 %. Given the minimal difference in outcomes between DGT-OP and DGT-RP, the use of standard DGT-OP is recommended. Further analysis revealed a strong correlation between DGT-labile Cu (CuDGT-lab), the weaker Cu-L2 complexes detected by CLE-AdSV, and the inorganic Cu species predicted by WHAM/Model-VII, the latter two based on discrete samples. A strong relationship was also noted between CuDGT-lab and the inorganic Cu measured by CLE-AdSV. The study provided compelling evidence that the in-situ ligand pool consists of a mixture of terrestrial humic substances and marine-derived organic ligands. These marine ligands form highly stable Cu-L1 complexes along the salinity gradient, which were mostly DGT-inert. The DGT results indicated that the lability of in-situ Cu complexes decreased with increasing salinity, with over 60 % of Cu in freshwater being DGT-labile. Overall, the study demonstrates that the DGT technique is a robust and straightforward method for environmental monitoring and risk assessment across diverse physico-chemical water conditions.
在新西兰奥克兰的河口和码头进行了一项综合研究，利用薄膜扩散梯度（DGT）技术检查淡水、河口和海洋环境中铜（Cu）配合物的原位形态。该研究采用不同厚度的开孔（OP）和限制孔（RP）扩散凝胶来评估DGT水凝胶的有效性，以及表观扩散边界层（ADBL）在确定天然水体中Cu配合物稳定性中的作用。DGT结果比较了竞争配体交换吸附溶出伏安法（cl - adsv）和物种形成预测模型（WHAM/ model - vii）的结果。该研究强调了考虑ADBL的重要性，因为它的排除导致对cu复合物稳定性的平均低估约50%。鉴于DGT-OP和DGT-RP之间的结果差异很小，建议使用标准DGT-OP。进一步分析表明，dgt -不稳定Cu （CuDGT-lab）、CLE-AdSV检测到的较弱Cu- l2配合物和WHAM/Model-VII预测的无机Cu物种之间存在很强的相关性，后两者基于离散样本。CuDGT-lab与CLE-AdSV测量的无机Cu之间也存在很强的关系。该研究提供了令人信服的证据，表明原位配体池由陆地腐殖质物质和海洋来源的有机配体组成。这些海洋配体沿盐度梯度形成高度稳定的Cu-L1配合物，这些配合物大多是dgt惰性的。DGT结果表明，原位Cu配合物的稳定性随着盐度的增加而降低，淡水中超过60%的Cu是DGT不稳定的。总体而言，该研究表明，DGT技术是一种强大而直接的方法，可用于各种物理化学水条件下的环境监测和风险评估。
{"title":"Comparative study of dissolved copper speciation using DGT and CLE-AdSV in a contaminated urban river estuary and marina","authors":"Billie G.B. Benedict , Rebecca Zitoun , Keith A. Hunter , Sylvia G. Sander","doi":"10.1016/j.marchem.2025.104500","DOIUrl":"10.1016/j.marchem.2025.104500","url":null,"abstract":"<div><div>A comprehensive study was conducted in a river estuary and marina in Auckland, New Zealand, to examine the <em>in-situ</em> speciation of copper (Cu) complexes across freshwater, estuarine, and marine environments using the diffusive gradient in thin films (DGT) technique. The study employed both open-pore (OP) and restrictive-pore (RP) diffusive gels of varying thicknesses to assess the effectiveness of DGT hydrogels and the role of the apparent diffusive boundary layer (ADBL) in determining the lability of Cu complexes in natural waters. The DGT findings were compared with results from competing ligand exchange–adsorptive stripping voltammetry (CLE-AdSV) and a speciation prediction model (WHAM/Model-VII). The study highlighted the critical importance of accounting for the ADBL, as its exclusion led to an average underestimation of Cu-complex lability by approximately 50 %. Given the minimal difference in outcomes between DGT-OP and DGT-RP, the use of standard DGT-OP is recommended. Further analysis revealed a strong correlation between DGT-labile Cu (CuDGT-lab), the weaker Cu-L<sub>2</sub> complexes detected by CLE-AdSV, and the inorganic Cu species predicted by WHAM/Model-VII, the latter two based on discrete samples. A strong relationship was also noted between Cu<sub>DGT-lab</sub> and the inorganic Cu measured by CLE-AdSV. The study provided compelling evidence that the <em>in-situ</em> ligand pool consists of a mixture of terrestrial humic substances and marine-derived organic ligands. These marine ligands form highly stable Cu-L<sub>1</sub> complexes along the salinity gradient, which were mostly DGT-inert. The DGT results indicated that the lability of <em>in-situ</em> Cu complexes decreased with increasing salinity, with over 60 % of Cu in freshwater being DGT-labile. Overall, the study demonstrates that the DGT technique is a robust and straightforward method for environmental monitoring and risk assessment across diverse physico-chemical water conditions.</div></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"270 ","pages":"Article 104500"},"PeriodicalIF":3.0,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143508084","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 : 2025-05-01Epub Date: 2025-03-11DOI: 10.1016/j.marchem.2025.104510
Ying Ping Lee , Kuo Hong Wong , Hajime Obata , Mohd Zaki Kamsah , Mohd Hisyam Rasidi
Mangrove forests are vital ecosystems that protect coastlines, sequester carbon, and support diverse food webs. Elucidation of the behaviors of nutrients, trace elements, and organic matters in these regions is crucial to understand the impact of human activities and the potential effects of climate change. In this study, we revealed the distributions and bioavailability of a trace metal, copper (Cu), and conducted the first study of Cu speciation in a mangrove region in Southeast Asia. Dissolved Cu (dCu) concentrations ranged from 0.3 to 2.3 nmol L−1 in the study region, which are relatively low compared to most other coastal regions globally. Two classes of Cu-binding organic ligands with average conditional stability constants, log K, of 15.5 and 13.2, respectively, were detected in mangrove waters. Complexing capacities of the ligands generally decrease in low salinity waters with low dCu concentrations. Concentrations of the stronger-binding class of organic ligand (L1) were higher than those of dCu, reducing the bioavailable Cu2+ concentration to less than femtomolar levels, potentially inducing Cu-limitation to microorganism growth. To further understand the biogeochemical processes of trace metals in mangrove regions, future studies should prioritize obtaining baseline data using standardized sampling and analytical techniques to ensure consistent and reliable results.
{"title":"Copper speciation in a tropical mangrove forest of Southeast Asia","authors":"Ying Ping Lee , Kuo Hong Wong , Hajime Obata , Mohd Zaki Kamsah , Mohd Hisyam Rasidi","doi":"10.1016/j.marchem.2025.104510","DOIUrl":"10.1016/j.marchem.2025.104510","url":null,"abstract":"<div><div>Mangrove forests are vital ecosystems that protect coastlines, sequester carbon, and support diverse food webs. Elucidation of the behaviors of nutrients, trace elements, and organic matters in these regions is crucial to understand the impact of human activities and the potential effects of climate change. In this study, we revealed the distributions and bioavailability of a trace metal, copper (Cu), and conducted the first study of Cu speciation in a mangrove region in Southeast Asia. Dissolved Cu (dCu) concentrations ranged from 0.3 to 2.3 nmol L<sup>−1</sup> in the study region, which are relatively low compared to most other coastal regions globally. Two classes of Cu-binding organic ligands with average conditional stability constants, log K, of 15.5 and 13.2, respectively, were detected in mangrove waters. Complexing capacities of the ligands generally decrease in low salinity waters with low dCu concentrations. Concentrations of the stronger-binding class of organic ligand (L<sub>1</sub>) were higher than those of dCu, reducing the bioavailable Cu<sup>2+</sup> concentration to less than femtomolar levels, potentially inducing Cu-limitation to microorganism growth. To further understand the biogeochemical processes of trace metals in mangrove regions, future studies should prioritize obtaining baseline data using standardized sampling and analytical techniques to ensure consistent and reliable results.</div></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"270 ","pages":"Article 104510"},"PeriodicalIF":3.0,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143628133","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 : 2025-05-01Epub Date: 2025-04-01DOI: 10.1016/j.marchem.2025.104515
Eva Ferreira , Bruno Lansard , Gaël Monvoisin , Evan Magette , Anthony Boever , Hanna Bridgham , Bruno Bombled , Jordon Scott Beckler , Martial Taillefert , Christophe Rabouille
The northern Gulf of Mexico (nGoM) experiences seasonal coastal hypoxia due to nutrient enrichment from the Mississippi-Atchafalaya River basin, leading to one of the world's largest hypoxic zones. In these shallow zones, benthic processes play an essential role in driving/maintaining deoxygenation and acidification of bottom waters. In this regard, this paper investigates carbonate dissolution processes in surface sediment of the nGoM during hypoxic conditions in summer 2022, as the main acidification feedback mechanism, with a specific focus on the effects of bottom water acidification. A strong linear relationship is observed between oxygen and pH, with a pH difference of 0.37 between the most oxygenated and the nearly anoxic station, reaching a value of 7.63. Using high-resolution techniques, this study combines pH and O₂ microprofiling (200 μm) with benthic measurements of carbonate system parameters (pH, DIC, TA, Ca2+) to assess carbonate dissolution at millimeter-scale resolution. The pH microprofiles reveal a significant decrease in the first 3 cm, with pore water pH reaching values of 6.90 at the most hypoxic station. Despite undersaturation with respect to aragonite and occasionally calcite, Ca2+ profiles indicate no significant carbonate dissolution, suggesting stability of calcium carbonate in these sediments during the summer. This lack of dissolution, likely influenced by the absence of aragonite, and possible inhibitory effects of dissolved organic carbon and orthophosphate, points to a limited buffering capacity in these sediments. These insights are essential for refining models predicting coastal acidification and hypoxia responses to environmental stressors in the nGoM and similar eutrophic systems.
由于密西西比-阿恰法拉亚河流域的营养物质富集，墨西哥湾北部经历了季节性的沿海缺氧，导致了世界上最大的缺氧区之一。在这些浅水区，底栖生物过程在驱动/维持底水脱氧和酸化方面起着至关重要的作用。因此，本文研究了2022年夏季低氧条件下nGoM表层沉积物中的碳酸盐溶解过程，作为主要的酸化反馈机制，重点研究了底水酸化的影响。氧与pH之间存在很强的线性关系，最富氧站与几乎缺氧站的pH值相差0.37，达到7.63。利用高分辨率技术，本研究将pH和O₂微谱（200 μm）与碳酸盐系统参数（pH， DIC， TA, Ca2+）的底栖测量相结合，以毫米级分辨率评估碳酸盐溶解。pH微剖面在前3 cm显著降低，最缺氧站孔隙水pH值达到6.90。尽管文石和方解石处于欠饱和状态，但Ca2+剖面显示没有明显的碳酸盐溶解，这表明这些沉积物中的碳酸钙在夏季具有稳定性。这种溶解的缺乏，可能受到文石缺乏的影响，以及溶解的有机碳和正磷酸盐可能的抑制作用，表明这些沉积物的缓冲能力有限。这些见解对于改进预测nGoM和类似富营养化系统中环境压力源的沿海酸化和缺氧反应的模型至关重要。
{"title":"Benthic biogeochemical processes and fluxes in the hypoxic and acidified northern Gulf of Mexico (nGoM), part I: Carbonate dissolution from in situ microprofiles","authors":"Eva Ferreira , Bruno Lansard , Gaël Monvoisin , Evan Magette , Anthony Boever , Hanna Bridgham , Bruno Bombled , Jordon Scott Beckler , Martial Taillefert , Christophe Rabouille","doi":"10.1016/j.marchem.2025.104515","DOIUrl":"10.1016/j.marchem.2025.104515","url":null,"abstract":"<div><div>The northern Gulf of Mexico (nGoM) experiences seasonal coastal hypoxia due to nutrient enrichment from the Mississippi-Atchafalaya River basin, leading to one of the world's largest hypoxic zones. In these shallow zones, benthic processes play an essential role in driving/maintaining deoxygenation and acidification of bottom waters. In this regard, this paper investigates carbonate dissolution processes in surface sediment of the nGoM during hypoxic conditions in summer 2022, as the main acidification feedback mechanism, with a specific focus on the effects of bottom water acidification. A strong linear relationship is observed between oxygen and pH, with a pH difference of 0.37 between the most oxygenated and the nearly anoxic station, reaching a value of 7.63. Using high-resolution techniques, this study combines pH and O₂ microprofiling (200 μm) with benthic measurements of carbonate system parameters (pH, DIC, TA, Ca<sup>2+</sup>) to assess carbonate dissolution at millimeter-scale resolution. The pH microprofiles reveal a significant decrease in the first 3 cm, with pore water pH reaching values of 6.90 at the most hypoxic station. Despite undersaturation with respect to aragonite and occasionally calcite, Ca<sup>2+</sup> profiles indicate no significant carbonate dissolution, suggesting stability of calcium carbonate in these sediments during the summer. This lack of dissolution, likely influenced by the absence of aragonite, and possible inhibitory effects of dissolved organic carbon and orthophosphate, points to a limited buffering capacity in these sediments. These insights are essential for refining models predicting coastal acidification and hypoxia responses to environmental stressors in the nGoM and similar eutrophic systems.</div></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"270 ","pages":"Article 104515"},"PeriodicalIF":3.0,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143808676","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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