Marine Chemistry最新文献

{"title":"Dynamics of dissolved trace metals, rare earth elements and Pb isotopes across the eastern margins of the Mediterranean Sea","authors":"Tal Benaltabet ,&nbsp;Gil Lapid ,&nbsp;Ronen Alkalay ,&nbsp;Yishai Weinstein ,&nbsp;Tim Steffens ,&nbsp;Eric P. Achterberg ,&nbsp;Adi Torfstein","doi":"10.1016/j.marchem.2025.104519","DOIUrl":"10.1016/j.marchem.2025.104519","url":null,"abstract":"<div><div>Continental margins support marine primary productivity by transferring nutrients and micro-nutrients (trace metals) from the coast to the oceans. Yet, the mechanisms governing the delivery of trace metals across the land-sea continuum, and how they vary temporally, are still poorly constrained. Here, we report high spatial resolution depth profiles of dissolved trace metals (Al, Mn, Fe, Co, Ni, Cu, Zn, Cd, and Pb), rare earth elements (REEs), nutrients (PO₄, TON, and SiOH₄) and Pb isotopes from two transect cruises in the oligotrophic eastern Mediterranean Sea.</div><div>Varying anthropogenic inputs resulted in inter-cruise variations in Zn and Pb concentrations and Pb isotopes. In contrast, low temporal variability was registered for PO₄, SiOH₄, Cu, and Co. The isotopic composition of Pb in the eastern Mediterranean Sea (²⁰⁶Pb/²⁰⁷Pb = 1.161–1.173 and ²⁰⁸Pb/²⁰⁶Pb = 2.085–2.101) is controlled by advected Atlantic surface water and anthropogenic inputs delivered via continental runoff (terrestrial) or atmospheric shuttles. The deep-water inventory of Pb is partially controlled by historical anthropogenic sources. An enrichment in Zn and Cd (81 and 17 %, respectively) and a 50 % depletion in Pb relative to open-waters was observed in Intermediate Levantine Waters, in tandem with terrestrial Pb isotopic signatures, light REE depletion (shale-normalized Nd/Yb &lt; 0.22) and a strong Ce anomaly (Ce/Ce* &lt; 0.20). These are driven by intermediate nepheloid layers from the margins, which act as both a source and a sink for trace metals through release and scavenging, evident 300–500 km away from the shore. This study highlights the dynamic role of continental margins in modulating terrestrial and anthropogenic inputs to the oceans.</div></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"270 ","pages":"Article 104519"},"PeriodicalIF":3.0,"publicationDate":"2025-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143851335","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":"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 ,&nbsp;F. Artuso ,&nbsp;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⁻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 (<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":"2025-04-09","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}

{"title":"Variation in chemical composition of dissolved organic matter during the winter to spring transition in the northern Barents Sea","authors":"Maria G. Digernes ,&nbsp;Jeffrey A. Hawkes ,&nbsp;Oliver Müller ,&nbsp;Stephen G. Kohler ,&nbsp;Murat V. Ardelan","doi":"10.1016/j.marchem.2025.104517","DOIUrl":"10.1016/j.marchem.2025.104517","url":null,"abstract":"<div><div>Molecular characterization of dissolved organic matter (DOM) from the Arctic Ocean is scarce, especially during the winter, which is a crucial period for water mass mixing and carbon cycling. The northern Barents Sea extending into the Arctic Ocean is experiencing global warming at a rate 5–7 times faster than the global average, leading to drastic chemical, physical and ecosystem changes. We sampled a transect along this region during early winter (December), late winter (March) and spring (May) and analyzed seawater samples using high-resolution mass spectrometry. Our results show significant changes in DOM composition driven by biological seasonality and water circulation such as lateral and vertical water transport, whereas water masses did not exhibit significant correlations with DOM composition. Our mass spectrometry-based results indicate that ionizable DOM compounds in early winter contained a greater proportion of unsaturated compounds relative to late winter and spring, as shown by weighted average hydrogen to carbon atomic ratios (H/C_wa) (−0.029, Mann-Whitney <em>U</em> test, <em>p</em> &lt; 0.001). Higher DOM lability in late winter was associated with higher nitrogen containing formulas which could be a result of DOM products from viral processes. Deep waters in the Arctic Basin and on the Barents Sea shelf break show greater lability in spring suggesting an influence of water circulation from the biologically active shelf regions. In early winter, higher weighted average aromaticity index (AI_mod), double-bond equivalents (DBE) and relative intensities of CHO formulas over heteroatom (N, S)-containing formulas were observed, thus supporting the presence of DOM with higher recalcitrance. Early winter also exhibited a significantly higher number of terrigenous peaks (t-Peaks) (<em>p</em> &lt; 0.001), suggesting seasonal removal of these riverine markers. This DOC may be transported to deeper ocean layers during winter water mixing. Our findings bridge the gap in winter DOM molecular characterization, which allows for future assessments of potential changes in the Arctic DOM reactivity.</div></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"270 ","pages":"Article 104517"},"PeriodicalIF":3.0,"publicationDate":"2025-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143834757","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":"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 ,&nbsp;Bruno Lansard ,&nbsp;Gaël Monvoisin ,&nbsp;Evan Magette ,&nbsp;Anthony Boever ,&nbsp;Hanna Bridgham ,&nbsp;Bruno Bombled ,&nbsp;Jordon Scott Beckler ,&nbsp;Martial Taillefert ,&nbsp;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, 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.</div></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"270 ","pages":"Article 104515"},"PeriodicalIF":3.0,"publicationDate":"2025-04-01","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}

{"title":"Samarium (Sm3+) and copper (Cu2+) complexation property with dissolved organic matter","authors":"Nabila Abbad ,&nbsp;Roland Redon ,&nbsp;Benjamin Oursel ,&nbsp;Christophe Lepoupon ,&nbsp;Gaël Durrieu ,&nbsp;Houssam Hajjoul ,&nbsp;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 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 K_Sm and K_Cu 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 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.</div></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"270 ","pages":"Article 104514"},"PeriodicalIF":3.0,"publicationDate":"2025-03-20","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}

{"title":"Influence of seasonal changes in organic matter pool on copper bioavailability in a stratified estuary","authors":"Saša Marcinek,&nbsp;Ana-Marija Cindrić,&nbsp;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⁻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 log<em>K</em>’₁ = 13.2 ± 0.5 and log<em>K</em>’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.</div></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"270 ","pages":"Article 104513"},"PeriodicalIF":3.0,"publicationDate":"2025-03-19","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}

{"title":"Diatom-driven processes lead to the assimilation of elements from silicate minerals into their frustules","authors":"Tasuku Akagi,&nbsp;Sophia Welti,&nbsp;Rei Tajiri,&nbsp;Kazuhiko Shimada","doi":"10.1016/j.marchem.2025.104512","DOIUrl":"10.1016/j.marchem.2025.104512","url":null,"abstract":"<div><div>To examine whether diatoms dissolve silicate minerals and incorporate foreign metals into their frustules, culture experiments were performed using <em>Achnanthes kuwaitensis</em> Hendey, <em>Eucampia</em> sp. and <em>Coscinodiscus wailesii</em>. These comprised two comparative experiments: (i) an analysis of diatom activities (population, transparent exopolymer particles (TEP) secretion and the Al/Si of frustules) in the presence/absence of feldspar particles, and (ii) an examination of mineral surfaces in the presence/absence of diatoms. Although the presence/absence of silicate minerals did not incur marked differences in diatom population, TEP secretion increased in the presence of silicate particles. Further, it was observed that the girdles of <em>Coscinodiscus</em> frustules showed double Si peaks and the outer layers of the girdles had significantly higher Al/Si ratios than the inner layers when feldspar particles were present. In the diatom cultures, feldspar particles largely disappeared in extended cultivation, and those still present showed rounded or fractured edges, features that were not seen in the absence of diatoms. The presence of diatoms appeared to have more influence on silicate minerals than the presence of silicate minerals on diatom activities. The C/Si ratios of the rounded feldspar grain edges in the <em>Coscinodiscus</em> cultures were significantly higher than those of stepwise edges, that we interpret to indicate that diatoms secrete TEP to dissolve silicate minerals. Two observations substantiated this hypothesis: pH decreases around diatoms, and incorporation of the mineral particles in TEP coatings.</div><div>Nevertheless, the physiological advantage for diatoms to dissolve silicate minerals remains unclear. Given the difference in TEP secretion between two different feldspar minerals, we believe that diatoms actively dissolve silicates in order to incorporate silica. We thus propose a mechanism by which diatoms dissolve silicate minerals. This may explain the inclusion of foreign elements at levels, whose relative concentrations are similar to those in terrigenous matter, in diatom frustules.</div></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"270 ","pages":"Article 104512"},"PeriodicalIF":3.0,"publicationDate":"2025-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143760083","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":"Regression-based characterization of the marine carbonate system across shelf and nearshore waters of Queen Charlotte Sound","authors":"A.A. Hare ,&nbsp;W. Evans ,&nbsp;H.V. Dosser ,&nbsp;J.M. Jackson ,&nbsp;S.R. Alin ,&nbsp;C. Hannah ,&nbsp;T. Ross ,&nbsp;J.M. Klymak","doi":"10.1016/j.marchem.2025.104511","DOIUrl":"10.1016/j.marchem.2025.104511","url":null,"abstract":"<div><div>Marine carbonate system measurements are essential for understanding ocean acidification and CaCO₃ saturation states, and their response to oceanographic and anthropogenic processes. Acquiring such measurements in remote coastal areas is limited by challenges in the development and deployment of autonomous sensors for these parameters, and by the complexity and costs of directly measuring them. We address this challenge by extending an established method of estimating carbonate system parameters through proxy variables to the remote waters of Queen Charlotte Sound, British Columbia. Paired regressions are developed from bottle samples and common hydrographic measurements for both offshore and coastal waters that intersect in this region but retain distinct relationships between total alkalinity and salinity. Application of these regression models to regional autonomous glider data demonstrates that established features of this shelf system can be characterized from a carbonate system perspective along a contiguous transect from land to the shelf break, despite greater regression uncertainties in coastal water. These results also provide new insight into the dynamics of aragonite saturation on the shelf in relation to regional winds. This approach extends a tool to gain knowledge of the marine carbonate system to a coastal region of the northeast Pacific Ocean where hydrographic data used as proxies are more commonly available.</div></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"270 ","pages":"Article 104511"},"PeriodicalIF":3.0,"publicationDate":"2025-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143682113","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":"Copper speciation in a tropical mangrove forest of Southeast Asia","authors":"Ying Ping Lee ,&nbsp;Kuo Hong Wong ,&nbsp;Hajime Obata ,&nbsp;Mohd Zaki Kamsah ,&nbsp;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⁻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.</div></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"270 ","pages":"Article 104510"},"PeriodicalIF":3.0,"publicationDate":"2025-03-11","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}

{"title":"Surface macro- and micro-nutrients within the Copper River plume region respond to along-shore winds","authors":"E.L.S. Ortega,&nbsp;I. Reister,&nbsp;S.L. Danielson,&nbsp;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 (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.</div></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"270 ","pages":"Article 104508"},"PeriodicalIF":3.0,"publicationDate":"2025-02-21","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}