Marine Chemistry最新文献

{"title":"Nickel and its isotope in response to differential manganese minerals accumulation in Northwest Pacific sediments","authors":"Hengchao Xu ,&nbsp;Xiaotong Peng ,&nbsp;Shui-Jiong Wang ,&nbsp;Shuangquan Liu ,&nbsp;Jiwei Li ,&nbsp;Hao Yang","doi":"10.1016/j.marchem.2025.104554","DOIUrl":"10.1016/j.marchem.2025.104554","url":null,"abstract":"<div><div>Nickel (Ni) is a biologically essential element in marine systems, yet its oceanic sources and sinks remain incompletely quantified. Micro manganese nodules (MMNs) and particles (MMPs) in marine sediment are major authigenic phase that scavenge critical metals though adsorption or incorporation. The accumulation of these minerals depends strongly on the seawater conditions and diagenetic processes within the sediments. Despite their significance, the influence of different manganese phase on the cycling of polymetallic elements-particularly Ni and its isotopes-has received little attention. This study analyzed MMPs bearing sediments, MMNs, and MMN bearing sediments from the Northwest Pacific Ocean to characterize their geochemical and Ni isotopic signatures. In core JL190, MMNs display Mn/Fe ratio and trace element patterns typical of suboxic-oxic diagenesis. Across all three cores, Ni concentrations track Mn accumulation closely, as shown by strong Mn/Al–Ni/Al correlations. However, core TS01-B10 from the Mariana Trench, which contains diatom-rich clay, yields weaker correlations than the two Philippine Sea cores. Despite these differences, bulk sediment δ⁶⁰Ni values remain light (0.01–0.79 ‰, median 0.27 ‰), consistent with most pelagic sediments. In core B10, declining δ⁶⁰Ni alongside rising Mn/Al ratios imply preferential adsorption of lighter Ni isotopes. In contrast, JL189 show simultaneous increase in Mn/Al and δ⁶⁰Ni, suggesting porewater exchange and isotope fractionation on existing Mn oxides. The heavier Ni isotopic signature in diagenetic MMNs relative to bulk sediments likely reflects prolonged porewater interaction, preserving the porwater's isotopic signature. These results provide the first δ⁶⁰Ni data for MMNs and elucidate their role as Ni carriers. These findings highlight the importance of authigenic Mn oxides in influencing the benthic flux of heavier Ni isotopes, which contributes to balancing the oceanic Ni budget.</div></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"273 ","pages":"Article 104554"},"PeriodicalIF":2.5,"publicationDate":"2025-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145010744","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":"MNPs in marine environment: Sources, distribution, trophic transfer, toxicity, fate and the remediating role of epiplastic syntrophic microbial consortia (Biofilms)","authors":"Smarto Basak ,&nbsp;Amit Kumar Dixit ,&nbsp;Ranjit Kumar Dey ,&nbsp;Gajji Babu","doi":"10.1016/j.marchem.2025.104553","DOIUrl":"10.1016/j.marchem.2025.104553","url":null,"abstract":"<div><div>This review focuses on plastic pollution, which has emerged as an urgent environmental issue with microplastics (MiPs) and nanoplastics (NaPs) being widespread contaminants in marine ecosystem. These particles pose serious ecological and public health risks due to their ability to bioaccumulate and vertically transfer through the food chain rapidly. Ingestion of MiPs and NaPs (MNPs) causes harmful physiological and reproductive effects, threatening the stability and integrity of marine food chains. This review summarizes the sources, distribution, trophic transfer, toxicity and fate of MNPs involving the marine ecosystem. Microbial communities have displayed potential as remediating agent for MNPs; though the processes involved in NaP degradation remain poorly understood, highlighting the need for further research. The distinctive properties of NaPs complicate their interactions with microbial communities, pointing to the necessity for focused studies on their biodegradation pathways. This review advocates for a holistic strategy that employs epiplastic syntrophic microbial consortia (Biofilm) as bioremediating agents, as their interactions may enhance breakdown of MNPs in marine setting. Future research should aim to clarify the relationships between microbial consortia and NaPs, identifying ideal conditions that foster microbial growth and activity on these NaPs. This review will be helpful for innovating effective management strategies to reduce the impacts of these established pollutants; ultimately, increasing our understanding of MNPs in marine environment, which is critical for shaping policies that safeguards the future of marine ecosystem and public health. Tackling plastic pollution requires a collaborative approach across all scientific fields, emphasizing the gravity of this global challenge.</div></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"273 ","pages":"Article 104553"},"PeriodicalIF":2.5,"publicationDate":"2025-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144933632","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":"2025-08-26","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":"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":"2025-08-15","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}

{"title":"Responses of the dynamics of particulate organic matter to different track typhoons in coastal waters","authors":"Chunqing Chen ,&nbsp;Qibin Lao ,&nbsp;Xin Zhou ,&nbsp;Shangjun Cai ,&nbsp;Sihai Liu ,&nbsp;Fajin Chen","doi":"10.1016/j.marchem.2025.104550","DOIUrl":"10.1016/j.marchem.2025.104550","url":null,"abstract":"<div><div>The impact of typhoons on marine biogeochemical processes depends on their intensity, track, and speed. However, how particulate organic matter (POM) dynamics respond to typhoons with distinct tracks remains poorly understood. This study investigated physicochemical parameters and stable isotopes of POM (δ¹³C-POC and δ¹⁵N-PN) through continuous observations (one cruise before the typhoon and four cruises after the typhoon, with a 5-day interval) in Zhanjiang Bay following two distinct track typhoons. During Typhoon Lionrock (landfall on the left side of the bay), onshore-wind stress drove high-salinity seawater intrusion, forming a strong salinity front in the bay that suppressed phytoplankton growth (Chl-<em>a</em> decreased by 80 %). In contrast, Typhoon Chaba (landfall on the right side of the bay) generated offshore-wind stress that resulted in weaker water mixing, while abundant terrestrial nutrient input promoted phytoplankton growth (Chl-<em>a</em> increased by two times in the 2nd and 4th cruises after the typhoon). Nevertheless, positive apparent oxygen utilization (AOU) values in the water column were observed after both typhoons, indicating strong decomposition of POM in Zhanjiang Bay. The strongest decomposition (over 80 %) for the two typhoons all occurred after 3 days of the typhoon landfall, and gradually decreased after 8 days of the typhoon landfall. The POM degraded after Typhoon Lionrock mainly originated from resuspended old POM, while from fresh POM (phytoplankton) after Typhoon Chaba. Additionally, the decomposition degree (56 %) induced by Lionrock was stronger than that induced by Chaba (44 %), suggesting that the typhoon landing on the left side of the bay are not conducive to marine carbon burial.</div></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"272 ","pages":"Article 104550"},"PeriodicalIF":2.5,"publicationDate":"2025-08-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144842111","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":"2025-07-25","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":"Dynamics of ocean acidity, CO2 fluxes and metabolic rates on a shallow reef of Weizhou Island: a buoy-based observational study","authors":"Xu Dong ,&nbsp;Baohong Chen ,&nbsp;Jianjia Wang ,&nbsp;Xinqing Zheng","doi":"10.1016/j.marchem.2025.104549","DOIUrl":"10.1016/j.marchem.2025.104549","url":null,"abstract":"<div><div>The metabolic processes of calcification and production serve as crucial indicators of how environmental changes impact reef health. Previous studies suggest that Net Ecosystem Production (NEP) primarily drives Net Ecosystem Calcification (NEC) in the short-term. However, the functional relationship between these two carbon metabolisms remains poorly understood. We employed a mooring buoy approach to obtain simultaneous, high-frequency data of seawater pH, aragonite saturation state, CO₂ fluxes, and carbon metabolic rates over a coral reef on Weizhou Island for 37 consecutive days. Our findings revealed a strong linear correlation between NEC and NEP across both diel cycles and day-to-day timescales—this relationship held even when analyzing nighttime periods alone. This indicates an intrinsic link between carbon metabolisms that can operate independently of light. Furthermore, we observed predominantly negative daily NEC and NEP values, indicating persistent net CaCO₃ dissolution and net heterotrophy across the studied reef for over weeks. Our results suggest that CaCO₃ dissolution is more likely to occur in waters with heterotrophic conditions, implying that heterotrophy contributes to CaCO₃ dissolution. This tight coupling could be explained by reef sediment dissolution through the Carbonate Critical Threshold (CCT) mechanism. Our study highlights the significance of ambient respiration in driving reef ecosystem-scale CaCO₃ dissolution, especially in reefs with low live hard coral coverage. This process releases alkalinity into the seawater, helping to neutralize respiration-induced acidification. Additionally, we identified a higher rate of respiratory CO₂ release as the primary driver of CO₂ emissions from the studied reef.</div></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"272 ","pages":"Article 104549"},"PeriodicalIF":2.5,"publicationDate":"2025-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144722316","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":"2025-07-20","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":"Investigation of open ocean ammonium aerosol sources in the North Pacific Ocean (Oahu, Hawaii)","authors":"Alexandra B. MacFarland ,&nbsp;Wendell W. Walters ,&nbsp;Katye E. Altieri ,&nbsp;Meredith G. Hastings","doi":"10.1016/j.marchem.2025.104545","DOIUrl":"10.1016/j.marchem.2025.104545","url":null,"abstract":"<div><div>Anthropogenic nitrogen (N) deposition entering the ocean from the atmosphere has increased over time. Ammonia (NH₃), a precursor to ammonium (NH₄⁺), is released into the atmosphere via both natural sources (e.g., ammonification, biomass burning, waste products, surface ocean emissions) and anthropogenic sources (e.g., agriculture, industry, sewage, vehicle emissions). Studies disagree on the quantity of anthropogenic N deposition to the ocean, as well as the consequences this excess N poses to the biogeochemistry of the open ocean, particularly in the Pacific Ocean. Understanding the current role that the open ocean is playing in the N cycle and budget is essential to determine the sources of N (e.g., internal or external, recycled or excess) and to further distinguish the relationships between atmospheric and oceanic N. Therefore, in the current study, ion concentrations and ammonium isotope values (δ¹⁵N-NH₄⁺) were measured for aerosol samples collected on the coast of Oahu, Hawaii from 2021 to 2022 (<em>n</em> = 67). This location was chosen based on low anthropogenic activity, access to the open ocean, and the premise of a dominant marine signal. Particulate NH₄⁺ concentrations ([NH₄⁺]) averaged 3.7 ± 7.3 ng/m³, with no distinct seasonality (<em>p</em> &gt; 0.05). The δ¹⁵N-NH₄⁺ values also did not exhibit distinct seasonality (<em>p</em> &gt; 0.05), but did fall into three unique clusters (using a K-means clustering analysis): cluster one = 19.0 ± 3.9 ‰ (<em>n</em> = 8), cluster two = 4.1 ± 2.3 ‰ (<em>n</em> = 31), and cluster three = −3.3 ± 2.4 ‰ (<em>n</em> = 13). Cluster three was best explained as an ocean emissions signature, which was determined via a phase partitioning model that incorporated N isotope fractionation associated with NH₃ conversion to NH₄⁺. Cluster one had higher than average [NH₄⁺] along with air mass origins from two seabird sanctuaries and was hypothesized to be a seabird emission signature. Cluster two was considered a mix of these two sources (67 % marine, 33 % seabird emissions). 6 % of aerosol inorganic N (NH₄⁺ + nitrate; annual dry inorganic <em>N</em> = 5.5 ng/m³) is from [NH₄⁺], with 35 % resulting from seabird emissions. The annual inorganic N (IN; NO₃⁻ + NH₄⁺) dry deposition value for this site was 1.2 ± 1.1 Tg N·y⁻¹.</div></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"272 ","pages":"Article 104545"},"PeriodicalIF":2.5,"publicationDate":"2025-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144767061","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 assessment of preservation methods for major nutrients in polar seawater","authors":"Mi Seon Kim ,&nbsp;Man Sik Choi ,&nbsp;Tae Siek Rhee","doi":"10.1016/j.marchem.2025.104546","DOIUrl":"10.1016/j.marchem.2025.104546","url":null,"abstract":"<div><div>Major nutrients—nitrate, phosphate, and silicate—are fundamental building blocks of marine biomass. To understand the flow of material and energy in the ecosystem, it is essential to accurately quantify nutrients concentrations. When shipboard analysis is not possible, seawater samples must be preserved without altering their contents. In this study, we investigated a range of commonly used preservation methods, including filtration, chemical poisoning with HgCl₂, and freezing at −20 °C or − 80 °C without pre-treatment, all aimed at minimizing biological activities. We also evaluated the effects of sample storage periods and thawing periods required before analysis in freezing treatments to determine their impact on nutrients contents. Using four different statistical methods, we assessed a total of 19 experiments to identify the most effective preservation method. Comparison between filtered and untreated seawater samples showed no detectable effect on the preservation by filtration. Deviations from shipboard measurement were detected in samples stored in a freezer, even at −80 °C. On the other hand, the nutrient content in the poisoned samples remained virtually intact. The deficiency in nutrient content observed during prolonged freezing and thawing or storage in a refrigerator at 4 °C, compared to shipboard measurements, aligns with the Redfield relationship reported in the Arctic Ocean, suggesting that biological activities occurred either within brine channels during freezing, during refrigerated storage, or both, likely due to viable cold-adapted microbes. Although our findings are based on polar seawater samples, potential biological activities during storage and post-treatment should be carefully examined in the other oceanic regions.</div></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"272 ","pages":"Article 104546"},"PeriodicalIF":3.0,"publicationDate":"2025-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144703844","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}