Marine Chemistry最新文献

{"title":"Copper speciation and its relationship with dissolved organic matter in a hypersaline coastal lagoon","authors":"Maria Sol Hernández-Conesa ,&nbsp;Juan Santos-Echeandía ,&nbsp;Patricia Bernárdez ,&nbsp;Xosé Antón Álvarez-Salgado ,&nbsp;Mar Nieto-Cid ,&nbsp;Paula Sánchez-Marín","doi":"10.1016/j.marchem.2025.104581","DOIUrl":"10.1016/j.marchem.2025.104581","url":null,"abstract":"<div><div>The Mar Menor (SE Iberian Peninsula) is the largest hypersaline coastal lagoon in Europe. This ecosystem is severely affected by anthropogenic impacts, causing the entry of metals and other contaminants. It is well known that total metal concentrations are not good predictors of their bioavailability, and its chemical speciation should be considered. Copper (Cu) is a metal of environmental concern whose speciation is largely controlled by natural organic ligands. The present work aims at studying the chemical speciation of dissolved Cu in the lagoon and its relationship with dissolved organic matter (DOM). For this purpose, 36 water samples were taken in different locations of the lagoon during six environmental surveys in 2021 and 2022. The chemical speciation of dissolved Cu was studied using cathodic stripping voltammetry (CLE-AdCSV), using salicylaldoxime as competing ligand. DOM was characterized by means of elemental composition (C and N), and optical properties (fluorescence and absorbance) in the same samples. Dissolved Cu speciation could be explained by a one ligand model, with ligand concentrations (L_Cu) ranging between 15.89 and 90.82 nM; and conditional stability constants (<span><math><msub><mrow><mi>log</mi><mspace></mspace><mi>K</mi><mo>´</mo></mrow><mrow><msup><mrow><mi>Cu</mi></mrow><mrow><mn>2</mn><mo>+</mo></mrow></msup></mrow></msub></math></span>) varying between 11.36 and 12.92. L_Cu positively and significantly correlated with dissolved organic carbon (DOC) concentration, absorption at 254 nm, and humic-like fluorescence intensity, suggesting that humic materials were the main ligands controlling Cu speciation in this area. In addition, the significant positive correlation found between DOC-normalized L_Cu and the aromaticity index SUVA₂₅₄ indicates that DOM aromaticity can be a good proxy of the metal binding ability of humic DOM. Despite the very high DOC concentrations present in Mar Menor, Cu complexation was similar to that found in other coastal areas with lower DOC, which may be explained by the hypersaline nature of the lagoon.</div></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"273 ","pages":"Article 104581"},"PeriodicalIF":2.5,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145614216","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":"pHT measurements of TRIS buffer solutions in an artificial seawater matrix in the salinity range 5–40 and temperature range 5–40 °C. Part 1: Measurements and data fitting","authors":"Gaëlle Capitaine ,&nbsp;Rieke Schäfer ,&nbsp;Frank Bastkowski ,&nbsp;Daniela Stoica ,&nbsp;Olivier Pellegrino ,&nbsp;Raquel Quendera ,&nbsp;Eric P. Achterberg ,&nbsp;Thibaut Wagener ,&nbsp;Simon L. Clegg ,&nbsp;Steffen Seitz ,&nbsp;Paola Fisicaro","doi":"10.1016/j.marchem.2025.104551","DOIUrl":"10.1016/j.marchem.2025.104551","url":null,"abstract":"<div><div>Spectrophotometric measurements of seawater total pH (<span><math><mi>p</mi><msub><mi>H</mi><mi>T</mi></msub></math></span>) contribute to the knowledge of the oceanic carbonate system, and hence to the assessment of the ocean carbon cycle and the monitoring of ocean acidification. Spectrophotometric measurements rely on the characterization of the indicator dye's second dissociation constant, obtained from measurements on solutions of known <span><math><mi>p</mi><msub><mi>H</mi><mi>T</mi></msub></math></span>. Therefore, Harned cell potentiometric measurements were performed on equimolal TRIS buffers (i.e. buffers containing equal molalities of 2-amino-2-(hydroxymethyl)-1,3-propanediol (TRIS, CAS reference number 77–86-1) and TRIS hydrochloride (TRIS.HCl)), made in an artificial seawater (ASW) matrix. Buffer solutions were prepared in an ASW matrix of nominal practical salinities from 5 to 40, and Harned cell measurements were performed on these solutions at temperatures from 5 °C to 40 °C. This provides, for the first time, <span><math><mi>p</mi><msub><mi>H</mi><mi>T</mi></msub></math></span> values of ASW/TRIS buffers that are consistent for the entire ranges of salinity relevant for oceanographic measurements, and for a wide range of temperature. The work presented includes a comparison of results from three National Metrology Institutes to assess reproducibility, and provides a function allowing the calculation of equimolal ASW/TRIS buffers <span><math><mi>p</mi><msub><mi>H</mi><mi>T</mi></msub></math></span> as a function of salinity, temperature and TRIS buffer molality. This function can be used to derive <span><math><mi>p</mi><msub><mi>H</mi><mi>T</mi></msub></math></span> values for zero TRIS molality, thus representing a pure ASW (i.e. a chemical environment unaffected by the presence of TRIS and TRIS.HCl), and referring to a true <span><math><mi>p</mi><msub><mi>H</mi><mi>T</mi></msub></math></span> scale. These values are needed for the characterization of the second dissociation constant of the dye with perspective of traceability to the International System of units.</div></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"273 ","pages":"Article 104551"},"PeriodicalIF":2.5,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144933633","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":"Desorption dynamics of black carbon in a subtropical estuary","authors":"Qinghua Zhang ,&nbsp;Weifeng Yang ,&nbsp;Ziming Fang ,&nbsp;Zeheng Lin ,&nbsp;Minfang Zheng ,&nbsp;Mengya Chen","doi":"10.1016/j.marchem.2025.104576","DOIUrl":"10.1016/j.marchem.2025.104576","url":null,"abstract":"<div><div>The geochemical behavior of black carbon (BC) in the estuary system controls the magnitude of riverine BC into coastal seas and thus the budget of BC in the ocean. However, the poor understanding of BC behavior in estuaries prevents us from well quantifying the riverine BC export. Here, eight cruises were conducted in the Jiulong River estuary to delineate the behavior of dissolved black carbon (DBC) determined using the benzenepolycarboxylic acid (BPCA) method, as well as its influence on riverine DBC estimation. DBC showed a range of 1.16–7.88 μmol L⁻¹. On an estuarine scale, DBC correlated negatively with salinity in all cruises (<em>p</em> &lt; 0.05), revealing a dominant dilution effect of seawater during the transport of riverine DBC to the Taiwan Strait. Notably, the continuous addition behavior of DBC was identified in the low salinity zones based on high-solution samplings, attributing to the desorption of soluble BC from particulate matter. Simulation analysis indicated that the desorption followed a pseudo-first-order kinetic law. The kinetic constants varied from 0.053 h⁻¹ to 0.84 h⁻¹ with the maximum in summer. Incorporating desorbed DBC, the annual export rate of riverine DBC was 1.1 Gg yr⁻¹, about 26 % higher than 0.9 Gg yr⁻¹ estimated based on the traditional algorithm (i.e., without addition). The first examination of DBC desorption kinetics provided insights into the behavior of BC in the estuary and the riverine DBC magnitude into the ocean.</div></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"273 ","pages":"Article 104576"},"PeriodicalIF":2.5,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145465957","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":"Factors influencing the variability of stable isotopes of carbon, nitrogen, and sulfur in benthic macrofauna from Admiralty Bay, maritime Antarctic","authors":"Agnieszka Jędruch ,&nbsp;Marcelina Ziółkowska ,&nbsp;Natalia Bulik ,&nbsp;Piotr Paneth ,&nbsp;Ewa Korejwo ,&nbsp;Dominika Saniewska","doi":"10.1016/j.marchem.2025.104564","DOIUrl":"10.1016/j.marchem.2025.104564","url":null,"abstract":"<div><div>This study examines benthic macrofauna from Admiralty Bay, maritime Antarctic, using triple stable isotope approach (<em>δ</em>¹³C, <em>δ</em>¹⁵N, and <em>δ</em>³⁴S) to assess the impact of melting glaciers and human activity on trophic interactions in this unique ecosystem. Four species – the limpet <em>Nacella concinna</em>, the sea urchin <em>Sterechinus neumayeri</em>, the starfish <em>Odontaster validus</em>, and the brittle star <em>Ophionotus victoriae</em> – were analyzed to characterize their isotopic composition and trophic niches. The results indicate that diet and feeding strategies were the main drivers of <em>δ</em>¹³C, <em>δ</em>¹⁵N, and <em>δ</em>³⁴S variability, demonstrating the utility of a multi-isotope approach for revealing diet composition, trophic plasticity, and benthic–pelagic coupling in polar benthic communities. Elevated <em>δ</em>¹³C values, typical of benthic primary producers, and depleted <em>δ</em>³⁴S values, indicative of sulfur derived from sediments, confirmed a strong reliance of benthic macrofauna on benthic food sources. In contrast, decrease in <em>δ</em>¹³C together with higher and typically marine <em>δ</em>³⁴S, can indicate higher contribution of pelagic diet sources. Spatial isotopic patterns further revealed areas influenced by glacial melt and shifting ice conditions, where consumers were relatively enriched in <em>δ</em>¹³C and <em>δ</em>¹⁵N compared to sites with rather open-ocean conditions. Notably, <em>δ</em>³⁴S emerged as a possible early indicator of human-related disturbance, with depletion reflecting increased anthropogenic sulfur inputs and reduced oxygen conditions in benthic habitats linked to nutrient enrichment. Concurrent to ³⁴S-depletion enrichment in ¹⁵N supports the role of nitrogen inputs from human activities. These findings demonstrate that stable isotopic tracers, particularly when incorporating sulfur alongside carbon and nitrogen, provide a powerful tool to detect and interpret ecological responses to both natural and anthropogenic drivers, offering insights into local ecosystem shifts and their broader implications for Antarctic food webs under climate change and growing human pressure.</div></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"273 ","pages":"Article 104564"},"PeriodicalIF":2.5,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145096873","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":"The impacts of chemical composition on bacterial processing of dissolved organic matter in the deep Arctic Ocean","authors":"N. Sylvestre,&nbsp;C. Guéguen","doi":"10.1016/j.marchem.2025.104579","DOIUrl":"10.1016/j.marchem.2025.104579","url":null,"abstract":"<div><div>The cycling of dissolved organic matter (DOM) in the ocean plays a central role in carbon dynamics, influencing the ocean's ability to sequester carbon and regulate climate. However, the microbial processes that govern the transformation and persistence of DOM across different water masses remain poorly understood. In this study, we explore how a single bacterial community processes DOM from four distinct water masses (<em>i.e</em>, Pacific winter water, Atlantic halocline, Atlantic water - Barents Sea Strait branch, and deep temperature minimum) in the Canada Basin of the Arctic Ocean, using a combination of optical and molecular techniques to reveal the microbial mechanisms behind DOM reactivity and persistence. Although all water masses contained the same fluorescent components, each underwent unique processing by the microbial community after 20 days of laboratory-controlled incubation. This suggests that the composition of specific fluorescent components likely varies between different water layers, with an increase in these features by the end of the incubation. The number of common molecular features measured with a trapped ion mobility spectrometer coupled with a time-of-flight mass spectrometer (TIMS-TOF) and an electrospray ionization source (positive ionization mode) was higher in contiguous water masses, likely due to water mass mixing resulting in the formation of the Atlantic halocline. Spearman's rank correlations between fluorescence characteristics and TIMS-TOF features established connections between fluorescent characteristics and molecular formulas. Twenty-two distinct molecular features were related to the four humic-like. None of them were associated with tyrosine-like, revealing the distinct molecular-optical linkages between humic- and protein-like DOM. Overall, our findings indicate that the DOM reactivity depends on its optical and molecular composition. The mechanistic understanding of the factors that control the persistence of DOM in the ocean is essential for predicting the ocean's role in the global carbon cycle.</div></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"273 ","pages":"Article 104579"},"PeriodicalIF":2.5,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145568616","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":"Advancing the characterization of organic Cu(II)-binding ligands in Arctic Ocean waters: Integration of IMAC, SPE, HRMS, and fluorescence techniques","authors":"Louis Criqui,&nbsp;Céline Guéguen","doi":"10.1016/j.marchem.2025.104578","DOIUrl":"10.1016/j.marchem.2025.104578","url":null,"abstract":"<div><div>The availability and toxicity of dissolved copper (Cu) in the ocean are largely determined by its complexation with organic ligands, but the structure and origin of these ligands are still largely unknown. In this work, standard and marine Cu(II) complexing ligands were isolated using immobilized metal affinity chromatography (IMAC) and solid phase extraction (SPE), and characterized using high-resolution mass spectrometry (HRMS) and excitation-emission matrix (EEM) fluorescence to obtain information on the size distribution, molecular composition, and fluorescing properties of organic Cu(II)-binding molecules in the Arctic Ocean. We first investigated the retention performance of model ligands and found that N-containing ligands were preferentially isolated on the IMAC-SPE column. Application to Arctic Ocean dissolved organic matter (DOM) showed that the organic ligands accounted for up to 3 % of the DOM, consistent with previous studies. Robust correlations of HMRS peak intensities with EEM signals were used to expand chemical characterization of 511 molecular formulas in the IMAC-SPE and SPE extracts. The pairing based on the molecular classification associated with fluorescence signatures showed that 52 % Spearman correlations were linked to humic-like components. The necessity of multiple molecular annotation methods, like HRMS/fluorescence correlation or van Krevelen class attribution, was demonstrated to yield a better molecular identification. The combination of IMAC, SPE, HRMS, and EEM appears to be a promising approach for the characterization of organic Cu(II)-binding ligands in waters.</div></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"273 ","pages":"Article 104578"},"PeriodicalIF":2.5,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145516650","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":"Ferrioxamine X1 mediated iron interaction with FoxA receptor in marine Pseudomonas stutzeri: An in silico approach","authors":"Pratika Singh ,&nbsp;Parli Venkateswaran Bhaskar ,&nbsp;Alok Kumar Sinha ,&nbsp;Vitthal T. Barvkar ,&nbsp;Sarat Chandra Tripathy","doi":"10.1016/j.marchem.2025.104563","DOIUrl":"10.1016/j.marchem.2025.104563","url":null,"abstract":"<div><div>The low iron concentrations in the Equatorial Indian Ocean (EIO) create a challenging environment for microbial life, requiring microorganisms to adapt. One strategy involves the production of siderophores, organic compounds that bind to Fe³⁺ ions and facilitate their uptake through specific receptors. Multiple siderophores may improve the bioavailability of iron due to the varied structures of siderophores and receptors. Since a single receptor may bind multiple siderophores, it is imperative to understand the molecular mechanisms underlying the interaction between siderophores and their receptors. This study used an <em>in silico</em> approach to explore these interactions. <em>Pseudomonas stutzeri</em> ATCC 17588, isolated from the EIO, was optimized for siderophore production under various growth conditions and analyzed using LC-qTOF-MS. The tertiary structure of the FoxA receptor and its interaction with the ferrioxamine X₁-Fe³⁺ complex were examined through molecular docking. <em>P. stutzeri</em> ATCC 17588 produced multiple siderophores, including ferrioxamine X₁, with optimal production at 10 nM iron concentration, pH 8.5, and 25 °C. The interaction energies between ferrioxamine X₁-Fe³⁺ and the FoxA receptor were − 40.81 kcal/mol and − 9.3 kJ/mol, respectively, suggesting stable complexes. The predicted FoxA structure, validated through various analyses, revealed helices interspersed with strands. Hydrophobic interactions, involving residues such as Gln287, Arg792, and Glu180, were primarily responsible for the binding of ferrioxamine X₁-Fe³⁺ to the FoxA receptor. This study sheds light on the role of ferrioxamine X₁ in iron acquisition by <em>P. stutzeri</em> in the iron-limited EIO and enhances our understanding of microbial metal-ligand interactions in marine ecosystems.</div></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"273 ","pages":"Article 104563"},"PeriodicalIF":2.5,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145096872","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":"Sedimentation and metal accumulation in the Gulf of Urabá – Colombian Caribbean: A 150-year record of natural processes and human impacts","authors":"Pedro Pablo Vallejo-Toro ,&nbsp;Javier Alcántara-Carrió ,&nbsp;Diana María Agudelo-Echavarría ,&nbsp;Jaime Palacio-Baena","doi":"10.1016/j.marchem.2025.104548","DOIUrl":"10.1016/j.marchem.2025.104548","url":null,"abstract":"<div><div>Natural and human factors control the sediment accumulation rates and metal deposition in estuaries. This study analyzes the changes in sedimentation rates and metal accumulation in the Gulf of Urabá (southern Colombian Caribbean) over the last 150 years. The sedimentation rates of three cores (C1, C2, and C3) were determined using the constant flux (CF) model based on the ²¹⁰Pb isotope, averaging 0.14 cm/y, 0.22 cm/y and 0.10 cm/y, respectively. The temporal distribution of both major (Al, Fe, Ca, Mn) and minor (Zn, Cr, Cu, Ni) metals revealed important historical events, including the relocation of the main tributary mouth, intensive land use changes, and extreme climatic events. In agreement with previous studies in the area, moderate contamination and metal enrichment were found based on three geochemical indices (enrichment factor, anthropogenic factor and geo-accumulation index) considering global crust reference values. However, a lack of or minimal pollution was evident when considering the local background metal concentrations, which were determined in the bottom core sediments (2583 y BP). Therefore, this study evidences the relevance of using local background to determine metal pollution in surface sediments and cores. Despite high freshwater inputs and sediment supply, as well as anthropogenic activities in the gulf, sedimentation rates and metal accumulation are low compared to other marine environments worldwide, due to the presence of a salt wedge intrusion. The salt wedge creates a density difference, causing the clay fraction of the sediments, along with associated pollutants, to remain suspended for extended periods. As a result, sedimentation is hindered, and these materials are transported out of the gulf. Consequently, fine and medium silt dominate sedimentation and metal accumulation dynamics in the estuary.</div></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"272 ","pages":"Article 104548"},"PeriodicalIF":2.5,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144749472","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":"Unsaturated aliphatic and sulfur-containing organic matter as surfactants in the surface microlayer","authors":"N.R. Coffey ,&nbsp;F.E. Agblemanyo ,&nbsp;A.M. McKenna ,&nbsp;A.S. Wozniak","doi":"10.1016/j.marchem.2025.104547","DOIUrl":"10.1016/j.marchem.2025.104547","url":null,"abstract":"<div><div>The surface microlayer (SML) is a 10s–100s μm thick layer which mediates fluxes across the air-sea interface. Organic matter (OM) enrichments at the SML are known to influence SML physical properties and air-sea exchanges, but the role of detailed molecular level OM composition in influencing those processes hasn't been fully explored. SML and subsurface (SUB, 8–15 cm) water at four stations encompassing different influences (marine/fluvial/salt marsh) on the Delaware Bay system were sampled and examined for relationships between SML/SUB OM composition and surface tension. Samples collected December 2018–October 2019 show SML dissolved organic carbon (DOC) enrichments of 0.87 to 4.42 times the SUB concentration. Excitation-emission matrix spectroscopy (EEMs) and negative electrospray ionization (-ESI) Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR MS) show marine samples have higher contributions from photobleached material and higher relative abundances of CHON compounds relative to inner bay sites, respectively. Principal component analyses further reveal consistent differences in SML OM composition relative to SUB. The SML contains higher abundances of compounds with H/C &gt; 1.7 and O/C &lt; 0.2, including sulfur-containing compounds - compositions suggestive of surfactant-like molecules, able to depress surface tension at the air-sea interface. Surface tension depressions were significantly correlated with unsaturated aliphatic and sulfur-containing compounds identified from FT-ICR MS data, yet showed no relationship with DOC abundances or enrichments, highlighting the need for compositional assessments for understanding OM influences on SML properties and air-sea exchanges. The sources and structures of SML surfactant molecules should be a focus of future work.</div></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"272 ","pages":"Article 104547"},"PeriodicalIF":3.0,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144703845","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":"Particulate iron seasonality between winter and spring in the open Southern Atlantic Ocean is primarily driven by non-biological processes","authors":"Antoine Ringard ,&nbsp;Hélène Planquette ,&nbsp;Thato Mtshali ,&nbsp;Alakendra Roychoudhury ,&nbsp;Eva Bucciarelli","doi":"10.1016/j.marchem.2025.104552","DOIUrl":"10.1016/j.marchem.2025.104552","url":null,"abstract":"<div><div>In the open Southern Ocean, primary productivity is mainly driven by limiting concentrations of iron. However, limited available iron data during winter leave a gap in our understanding of how seasonality affects the iron cycle, and primary productivity. In this context, two cruises followed the same transect in the Atlantic sector of the Southern Ocean, from the SubTropical zone to the Antarctic zone, during spring and winter. This study aims to determine whether particulate iron concentrations showed seasonal changes, and to identify the processes driving these variations. Particulate iron ranged between 0.04–0.99 nM and 0.04–1.17 nM during spring and winter, respectively, with the lowest concentrations measured in surface waters. Overall, seasonality did not consistently affect total pFe distributions, and when differences existed, total pFe concentrations were higher in winter than in spring. Our findings indicate that biogenic particulate iron is higher in spring than in winter, and represents only a minor component of total pFe in surface waters during both seasons. Therefore, biological processes do not account for the observed seasonal changes in total pFe concentrations. At certain stations, higher pFe concentrations in winter relative to spring appear to be related to episodic external inputs of lithogenic particles, such as iron-rich dust deposition and inputs from the ACC. The authigenic fraction is the primary contributor to total pFe. These particles seem to be formed through the precipitation of dissolved iron derived from the dissolution of lithogenic particles or hydrothermal activity.</div></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"272 ","pages":"Article 104552"},"PeriodicalIF":2.5,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144864876","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}