Marine Chemistry最新文献

{"title":"Sulfur isotopic fractionation during hydrolysis of carbonyl sulfide","authors":"Yasmin Avidani ,&nbsp;Alon Angert ,&nbsp;Chen Davidson ,&nbsp;Xinyu Xia ,&nbsp;Yongli Gao ,&nbsp;Alon Amrani","doi":"10.1016/j.marchem.2024.104458","DOIUrl":"10.1016/j.marchem.2024.104458","url":null,"abstract":"<div><div>Carbonyl Sulfide (OCS) is the most abundant sulfur-containing gas in the atmosphere, and it is used as a proxy for terrestrial gross primary productivity (GPP). Oceans are the major source of OCS to the atmosphere, produced by photochemical and “dark” reactions. Hydrolysis to H₂S and CO₂ is the major removal process of OCS from the ocean's surface. Measuring the sulfur isotope values (δ³⁴S) and the isotopic fractionation (ε) associated with these major OCS sources and sinks could decrease the uncertainties in its fluxes. In the current study, we aim to determine the ε during the hydrolysis process of OCS (ε_h). We used a purge and trap system coupled to a GC/MC-ICPMS to measure δ³⁴S values during hydrolysis under different temperatures (4–40 °C), salinities (0.2–40 g/L), and pH (4–9), representing various natural environmental conditions. In addition, we use the quantum chemical method to calculate the equilibrium ε_h and compare it to the empirical results. Our results for the low salinity (S =0.2 g/L; pH 8.0) water show a temperature dependency of the ε_h from −3.9 ‰ ± 0.2 ‰ (4 °C,) to −2.2 ± 0.6 ‰ (40 °C). The higher fractionation at low temperatures has implication for ice-core data interpretation. However, in natural seawater at 4<span><math><msup><mrow></mrow><mo>°</mo></msup><mi>C</mi></math></span> and 22 °C (S = 40 g/L, pH 8.2) there was no such temperature dependency and the ε_h averaged −2.6 ± 0.3 ‰. Thus, it seems that salinity cancels the temperature effect close to the freezing temperature of water. Varying the pH between 4 and 9 (at 22 °C) did not result in any ε_h trend. Ab-initio calculations suggest that OCS hydrolysis is not controlled by equilibrium. The ε_h values we report will aid in quantifying the impact of OCS's hydrolysis on the observable sulfur isotopic signature of OCS in oceanic and in freshwater environments. This in turn will facilitate more accurate mass-balance calculations for the OCS budget from the ocean to the atmosphere.</div></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"267 ","pages":"Article 104458"},"PeriodicalIF":3.0,"publicationDate":"2024-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142357597","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Microplastics in wild Saccostrea cucullata oysters in Sri Lanka: Pollution status and risk assessment","authors":"K.P.G.K.P. Guruge ,&nbsp;K.M.S.N. Abeysinghe ,&nbsp;Tharindu Bandara ,&nbsp;P.B.T.P. Kumara","doi":"10.1016/j.marchem.2024.104457","DOIUrl":"10.1016/j.marchem.2024.104457","url":null,"abstract":"<div><div>Microplastics (MPs) have widely been reported in many marine organisms that cause significant environmental concern. Oysters are known to accumulate MPs through their filter-feeding mechanism yet studies focused on MPs pollution in oysters along with ecological risk assessment are scarce. In this study, we investigated MPs pollution in wild <em>Saccostrea cucullata</em> oysters and assessed the ecological risk of MPs pollution in oysters and their habitats along the southern and western coasts of Sri Lanka. Oyster MPs abundance varied from 0.63 to 2.20 particles g⁻¹ wet weight (ww), which showed a significant positive correlation with MPs abundances in surrounding surface seawater and surface sediment. The average MPs abundances in oysters, surface seawater and surface sediment showed significant spatial differences where high MPs abundances were reported in areas that had high anthropogenic activities. Size classification of MPs revealed that small size (100 μm-1 mm) blue fibres were dominant in oysters, surface seawater and surface sediment likely due to the high abundance of discarded fishing nets in studied areas. The abundance of various polymer types indicated that low-density polyethene polymers were most abundant (oysters, 45.74 %; surface seawater, 42.91 % and surface sediment, 39.62 %). Results of the ecological risk assessment indicated that MPs pollution in the environment was low (Level I). However, MPs pollution in oysters ranged from low to moderate risk levels (Level I-II), where moderate risk was reported in the areas with high MPs contamination. Therefore, our study highlights that mitigation of MPs pollution on the southern and western coast of Sri Lanka is important to alleviate the increasing ecological risk of MPs pollution in <em>Saccostrea cucullata</em>.</div></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"267 ","pages":"Article 104457"},"PeriodicalIF":3.0,"publicationDate":"2024-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142357598","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":"Tracking suspended particulate organic matter biochemistry from glacial meltwater runoff to coastal waters of an Antarctic fjord","authors":"Claudia Parodi ,&nbsp;Luis Cerpa ,&nbsp;Zhuoyi Zhu ,&nbsp;Jing Zhang ,&nbsp;Pablo Muniz ,&nbsp;Natalia Venturini","doi":"10.1016/j.marchem.2024.104455","DOIUrl":"10.1016/j.marchem.2024.104455","url":null,"abstract":"<div><div>Increased glacier melting runoff in Antarctica involves intensification of freshwater, nutrients, sediments and organic matter inputs from land to the sea, which is impacting coastal ecosystems. Basic environmental characteristics of water and biochemical composition of suspended particulate organic matter (POM) both in the proglacial melting runoff system (PROGLARS) of Collins Glacier and marine surface waters of Collins Bay was studied based on organic biopolymers and molecular level analysis of amino acids (AAs), to discern among sources and degradation state in the two environments. Hierarchical Clustering Analysis revealed that PROGLARS stations and marine stations form two distinct groups in terms of water physicochemical characteristics and suspended POM biochemical composition. These differences are the consequence of low restricted contribution of freshwater from Collins Glacier runoff into the coastal-marine environment. Our results evidenced low concentrations of terrestrial suspended POM in marine waters of Collins Bay mainly attributed to low meltwater inputs between the 1st and 7th of February 2018. In terms of macromolecular composition, the predominance of proteins, denote the labile nature of suspended POM in the two environments. Suspended POM in Collins Bay is labile, poorly degraded, representing a protein supplemented food resource, with high energetic value and easily assimilated by heterotrophic marine organism. AAs composition supported less degraded suspended POM derived from marine phytoplankton in surface waters of Collins Bay, whereas, great degradation of suspended POM in the proglacial runoff system of Collins Glacier. Changes in the biochemistry of suspended POM caused by glacial melting and retreat, may affect food features and availability, the productivity of ecosystems, and ultimately, the capacity of Antarctic fjords to act as carbon sinks and climate regulators. Considering low influence of Collins Glacier meltwater in coastal marine waters of Collins Bay, due to the relatively slow retreat of Collins Glacier and low development of its meltwater runoff system, the results of our work are relevant as baseline information for comparison with other Antarctic fjords. Further knowledge about meltwater runoff and suspended POM input dynamics in Antarctic coastal ecosystems, is critical, particularly in areas prone to undergo increased glacier melting in the following decades.</div></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"267 ","pages":"Article 104455"},"PeriodicalIF":3.0,"publicationDate":"2024-09-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142323957","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":"Spatial distribution of dissolved free amino acids in three Iberian Atlantic estuaries","authors":"Valentina Amaral ,&nbsp;Jesús Forja ,&nbsp;Barbara Steger-Mähnert ,&nbsp;Gerhard J. Herndl ,&nbsp;Cristina Romera-Castillo","doi":"10.1016/j.marchem.2024.104456","DOIUrl":"10.1016/j.marchem.2024.104456","url":null,"abstract":"<div><p>Rivers and estuaries are the main link between land and ocean, transferring significant amounts of dissolved organic carbon. These ecosystems receive large amount of dissolved organic matter (DOM) from diverse sources, both allochthonous and autochthonous. Within this pool, dissolved free amino acids (DFAA) represent the most labile fraction, offering valuable insights into DOM composition and diagenetic processes. Our study focused on three Iberian Atlantic estuaries—Guadalquivir, Guadiana, and Tinto-Odiel— that differ in hydrology, land use and DOM sources. We studied the longitudinal distribution of DFAA and their response to tidal cycles across these estuaries. Despite similar DFAA concentrations between estuaries (176.6 nM to 1770 nM) were found, variations in specific amino acids like glutamic acid, taurine, and aspartic acid pointed to a substantial influence of terrestrial inputs in Guadalquivir and Guadiana estuaries and an anthropogenic influence in Tinto-Odiel. Predominant amino acids—serine, glycine, ornithine, and asparagine —comprised more than 50 mol% of the estuarine DFAA pool. The dominance of serine, glycine, and ornithine indicated substantial DOM degradation, possibly associated with the loss of labile DOM during estuarine transport. Concurrently, asparagine prevalence was linked to allochthonous DOM input particularly associated with terrestrial runoff, lateral input, and anthropogenic activities at estuarine margins. Our results underscore the impact of tidal cycles on DFAA distribution and emphasize the potential of DFAA in unraveling estuarine DOM dynamics and their role as indicators of reactivity and composition in estuarine biogeochemistry.</p></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"267 ","pages":"Article 104456"},"PeriodicalIF":3.0,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142271942","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A comparative study of optical and size properties of dissolved organic matter in the lower Mississippi River and Pearl River","authors":"Zhengzhen Zhou ,&nbsp;Hui Lin ,&nbsp;Eurico J. D'Sa ,&nbsp;Laodong Guo","doi":"10.1016/j.marchem.2024.104453","DOIUrl":"10.1016/j.marchem.2024.104453","url":null,"abstract":"<div><p>Monthly water samples were collected from the lower Mississippi and Pearl Rivers between January 2009 and August 2011 to investigate the heterogeneity in the dynamic variations of dissolved organic carbon (DOC), colloidal organic carbon, chromophoric and fluorescence dissolved organic matter (CDOM and FDOM), PARAFAC-derived fluorescent components, and other optical properties including spectral slope, specific UV absorbance (SUVA), and fluorescence indices between the two contrasting river systems. The lower Mississippi River exhibits relatively lower concentrations of DOC (306 ± 41 μM C) and CDOM (27.9 ± 5.7 m⁻¹ at 254 nm), featuring lower aromaticity (indicated by SUVA₂₅₄) and apparent molecular weight (or higher spectral slope) with weak seasonal variability. The Pearl River, in contrast, has elevated levels of DOC (537 ± 212 μM C) and CDOM (66.4 ± 31.4 m⁻¹), characterized by higher aromaticity, higher molecular weight, and significant seasonality, primarily originating from soil-derived allochthonous sources. The abundance of the &gt;1 kDa colloidal DOC was, on average, 58 ± 3 % of the bulk DOC in the lower Mississippi River and 68 ± 6 % in the lower Pearl River. The &gt;1 kDa high-molecular weight DOM (HMW-DOM) consistently had lower spectral slope and biological index (BIX) values, but higher humification index (HIX) values compared to both bulk DOM and low-molecular-weight DOM (LMW-DOM) counterparts. These trends could be representative of other similar large and small rivers. Four PARAFAC-derived fluorescent components (three humic-like and one protein-like) were identified for both rivers. A positive correlation between discharge and terrestrial humic-like fluorescent components indicated their dominant allochthonous sources, while the protein-like component decreased with increasing discharge, consistent with its autochthonic source and a dilution effect during high flow seasons. The occurrence of large flood events during the sampling period contributed to large DOC pulses, with DOM of higher aromaticity and HMW-DOM. This has important implications for coastal ocean ecosystems, which are increasingly impacted by river flooding events under changing climate conditions. Our results also provide an improved understanding of DOM dynamics in two representative rivers and establish a baseline dataset for future studies to assess changes in sources and composition of DOM and their impacts on the coastal ocean in response to climate, hydrological, and anthropogenic influences.</p></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"267 ","pages":"Article 104453"},"PeriodicalIF":3.0,"publicationDate":"2024-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142243413","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":"Two-dimensional determination of dissolved manganese in sediment porewaters","authors":"Aurélia Mouret ,&nbsp;Constance Choquel ,&nbsp;Aubin Thibault de Chanvalon ,&nbsp;Florian Cesbron ,&nbsp;Thierry Jauffrais ,&nbsp;Didier Jézéquel ,&nbsp;Patrick Launeau ,&nbsp;Anthony Barbe ,&nbsp;Romain Levrard ,&nbsp;Alan Nicol ,&nbsp;Céline Charbonnier ,&nbsp;Edouard Metzger","doi":"10.1016/j.marchem.2024.104454","DOIUrl":"10.1016/j.marchem.2024.104454","url":null,"abstract":"<div><p>We present a new method for imaging dissolved manganese at millimeter scale by coupling DET (diffusive equilibrium in thin film) and colorimetric techniques. The method is an adaptation of the porphyrin approach for the measurement of dissolved Mn by substitution of Mn(II) and Mn(III) to Cd in the Cd(II)–POR complex. Optimization of the Cd-POR concentrations was required for transposition to 2D-DET. A commercial flatbed scanner and a hyperspectral camera were used for imaging. Using the hyperspectral camera, detection limit is about 5 μM and measuring range is up to 520 μM. The method was applied on the field in a tidal mudflat of the French Atlantic coast and in sediments inhabited by polychaetes. These first images allowed to precisely describe two-dimensional millimeter features such as burrows and highlighted the role of bioirrigation in benthic Mn fluxes. This new technique offers the possibility to investigate the reactivity of microenvironments towards dissolved Mn in two dimensions in a wide range of laboratory and <em>in situ</em> studies using a non-destructive tool.</p></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"267 ","pages":"Article 104454"},"PeriodicalIF":3.0,"publicationDate":"2024-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0304420324001051/pdfft?md5=d3dee2023242a4aa1fbe4587bffaa871&pid=1-s2.0-S0304420324001051-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142244156","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":"Vanadium redox speciation in the acid-extractable phase of Krka River estuary surface sediment","authors":"Lucija Knežević ,&nbsp;Nuša Cukrov ,&nbsp;Elvira Bura Nakić","doi":"10.1016/j.marchem.2024.104452","DOIUrl":"10.1016/j.marchem.2024.104452","url":null,"abstract":"<div><p>This study investigated the redox speciation and mobility of V in the acid-extractable fraction of surface sediments from the Krka River estuary using an optimized IC-UV/Vis analytical method. The separation of V(IV) and V(V) redox species was done using anion-exchange based chromatographic method, while pseudo-total V concentrations were measured using HR ICP-MS analytical instrumentation. Extracted V concentrations from the sediment fraction (pH = 5, HCl) and determined pseudo-total V concentrations were used to calculate the Enrichment Factor (EF) and Risk Assessment Code (RAC), indicating potential anthropogenic influence and environmental risk. A simple PHREEQC model was developed to asses V speciation in the oxic bottom seawater layer simulating possible remobilization of the leached sediment phase. The results of the study show that minor fraction of V is present in the acid-extractable phase across the surface sediment of Krka River estuary. Higher V mobility is mostly observed at locations rich with clay minerals, terrigenous input, and carbonates. Anthropogenic influence was linked to higher enrichment but lower mobility, suggesting binding to less mobile sediment phases (reducible, organic and residual fractions). The predominance of reduced V(IV) species in the acid-extractable sediment fraction indicates a potentially low V toxicity risk in the sediments of Krka River estuary, even in cases of high potential remobilization of V. However, the model predicted complete oxidation of V(IV) to V(V) upon remobilization into the oxic bottom water layer. This highlights the complexity of V behavior in natural estuarine systems, where the toxicity risks of possible V remobilization still remain unclear. Results of this study demonstrate the need for the strengthening efforts in speciation of V in the mobile sediment phase to obtain a cohesive outlook on its potential toxicity and biogeochemical cycling.</p></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"267 ","pages":"Article 104452"},"PeriodicalIF":3.0,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142271941","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":"Tidal scale dissolved inorganic and particulate organic carbon dynamics in a tropical estuary","authors":"Mohammad Atif Khan ,&nbsp;Sanjeev Kumar ,&nbsp;Rajdeep Roy ,&nbsp;Satya Prakash ,&nbsp;Aneesh A. Lotliker ,&nbsp;Sanjiba Kumar Baliarsingh","doi":"10.1016/j.marchem.2024.104451","DOIUrl":"10.1016/j.marchem.2024.104451","url":null,"abstract":"<div><p>Dissolved inorganic carbon (DIC) and particulate organic carbon (POC) dynamics in the world's estuaries have been studied extensively at monthly, seasonal, and annual time scales with particular focus on their concentrations and export fluxes to the coastal oceans. However, given the dynamic nature of the estuaries, the effect of tidal and diel cycles on the processes modulating DIC and POC dynamics remains obscure. To decipher the biogeochemical processes at tidal scale, DIC and POC concentrations and their carbon and nitrogen isotopic compositions were measured across the salinity gradient at every high and low tide for nine consecutive days (14–23 October 2019) in the Mahanadi estuary, a tropical estuary at the east coast of India. Showing contrasting differences across salinity gradient in DIC, POC and their isotopic compositions, DIC and POC were significantly different during high and low tide in the mixing zone only during spring duration. This showed the effect of spring-neap tidal cycle owing to water level fluctuations and mixing intensity in the estuarine mixing zone. Linear least-squares regression models indicated carbonate and/or silicate weathering by biogenic CO₂ to be the probable DIC source in the freshwater region of the estuary. Deviations of observed DIC concentrations and δ¹³C_DIC from the conservative mixing values suggested pronounced alteration of DIC source signature in the mixing zone. A process-based model approach aimed at delineating possible biogeochemical processes affecting DIC dynamics indicated calcite dissolution during low tide and calcite precipitation during high tide to be dominant processes in the mixing zone. Additionally, signatures of more than one simultaneous biogeochemical process modulating the DIC dynamics were also observed. POC pool in the mixing zone was largely influenced by its removal through rapid remineralization during both high and low tides. Graphical plots also showed that POC in the mixing zone and at the saline location was significantly affected by processes such as degradation, whereas it was only slightly affected in the freshwater region of the estuary. δ¹³C_POC, along with the C/N ratio of POM, indicated that C3 plants and/or their derived soil were the major source of POM in the freshwater, whereas the higher contribution of riverine POM and marine phytoplankton was observed in the mixing zone and saline location, respectively.</p></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"267 ","pages":"Article 104451"},"PeriodicalIF":3.0,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142229360","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A protocol for the synthesis of [35S]-labeled 3-dimethylsulfoniopropionate and dimethylsulfide from L-methionine for use in biogeochemical studies","authors":"Alexandra M. Smith ,&nbsp;Daniela A. del Valle ,&nbsp;Alison N. Rellinger ,&nbsp;Jeffrey W. Krause ,&nbsp;Ronald P. Kiene","doi":"10.1016/j.marchem.2024.104440","DOIUrl":"10.1016/j.marchem.2024.104440","url":null,"abstract":"<div><p>Radiotracers are highly sensitive tools for quantifying the rates of important biogeochemical processes and the fates of specific atoms and/or compounds within major global elemental cycles, especially those that are requisite for life. Important radiolabeled organosulfur compounds, like dimethylsulfide (DMS) and its precursor 3-dimethylsulfoniopropionate (DMSP), are not commercially available, but their well-documented use has been key in furthering our understanding of the marine sulfur cycle. [³⁵S]-DMSP obtained by chemical synthesis has been used extensively in radiotracer studies involving DMS and DMSP, but its synthesis has been restricted to 2 research groups. Presented here is a protocol for the chemical synthesis of [³⁵S]-DMSP from [³⁵S]-L-methionine, though the method could be used for other radiolabels (e.g. [¹⁴C], [³H]). The synthesis consists of 2 reaction steps, (1) the sequential oxidative deamination and decarboxylation of [³⁵S]-L-methionine to [³⁵S]-3-methylmercaptopropionate and (2) the methylation of [³⁵S]-methylmercaptopropionate to yield the product [³⁵S]-DMSP. The product is purified by liquid chromatography and two cation-resin exchanges. Average final [³⁵S]-DMSP yield was 5.34% (<em>n</em> = 16; range: 1.26% to 14.84%, excluding failures), although updated instrumentation could likely improve final yields. The objective of this work is to standardize the synthesis of [³⁵S]-DMSP to widen its availability and use among the community and hence facilitate increased understanding of the reduced sulfur and carbon cycles.</p></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"265 ","pages":"Article 104440"},"PeriodicalIF":3.0,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142097903","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":"Effect of temperature on the production and degradation of bromoform and other brominated methanes by marine microorganisms","authors":"Yuki Okuda,&nbsp;Hayato Yamashita,&nbsp;Shinya Hashimoto","doi":"10.1016/j.marchem.2024.104443","DOIUrl":"10.1016/j.marchem.2024.104443","url":null,"abstract":"&lt;div&gt;&lt;p&gt;Brominated methanes such as bromoform (CHBr&lt;sub&gt;3&lt;/sub&gt;) are known to be important carriers of bromine from the ocean to the atmosphere. Bromine released from brominated methanes by photolysis has been shown to catalyze ozone depletion. Marine phytoplankton has been reported as a source of CHBr&lt;sub&gt;3&lt;/sub&gt; and marine bacteria as a sink for CHBr&lt;sub&gt;3&lt;/sub&gt;. The effects of temperature on both CHBr&lt;sub&gt;3&lt;/sub&gt; production by phytoplankton and CHBr&lt;sub&gt;3&lt;/sub&gt; degradation by bacteria have yet to be investigated. We investigated the effects of temperature on CHBr&lt;sub&gt;3&lt;/sub&gt; production and CHBr&lt;sub&gt;3&lt;/sub&gt; degradation by marine microorganisms. The marine diatom &lt;em&gt;Ditylum brightwellii&lt;/em&gt; (CCMP358) was cultured at 15 °C, 20 °C, 24 °C, and 30 °C. The maximum CHBr&lt;sub&gt;3&lt;/sub&gt; production rate at 24 °C was 1.57–2.39 pmol (μg chlorophyll &lt;em&gt;a&lt;/em&gt;)&lt;sup&gt;−1&lt;/sup&gt; d&lt;sup&gt;−1&lt;/sup&gt;, several times higher than that at 15 °C (0.25–0.41 pmol (μg chlorophyll &lt;em&gt;a&lt;/em&gt;)&lt;sup&gt;−1&lt;/sup&gt; d&lt;sup&gt;−1&lt;/sup&gt;). Higher rates of CHBr&lt;sub&gt;3&lt;/sub&gt;, CHBr&lt;sub&gt;2&lt;/sub&gt;Cl, and CHBrCl&lt;sub&gt;2&lt;/sub&gt; production were observed in the late exponential phase (and stationary phase) than in the early exponential phase at each temperature. These results suggest that temperature affects the rate of CHBr&lt;sub&gt;3&lt;/sub&gt; production during plankton growth. We then cultured the marine α-proteobacterium &lt;em&gt;Phaeobacter gallaeciensis&lt;/em&gt; (JCM 21319) and the γ-proteobacterium &lt;em&gt;Pseudomonas&lt;/em&gt; sp. HKF-4 at 10 °C, 15 °C, 20 °C, and 25 °C for up to 15 days to analyze temperature effects on spiked &lt;sup&gt;13&lt;/sup&gt;CHBr&lt;sub&gt;3&lt;/sub&gt; degradation. The degradation rate of &lt;sup&gt;13&lt;/sup&gt;CHBr&lt;sub&gt;3&lt;/sub&gt; by &lt;em&gt;P. gallaeciensis&lt;/em&gt; increased with increasing temperature from 10 °C to 25 °C. The half-life of &lt;sup&gt;13&lt;/sup&gt;CHBr&lt;sub&gt;3&lt;/sub&gt; at 25 °C was about 1.1 d, which is about 6 times shorter than the half-life at 10 °C (about 6.9 d). On the other hand, the change in the half-life of the degradation of &lt;sup&gt;13&lt;/sup&gt;CHBr&lt;sub&gt;3&lt;/sub&gt; by HKF-1 was relatively small as the temperature increased from 10 °C (half-life: about 5.5 d) to 25 °C (half-life: about 1.8 d). Considering the rate of CHBr&lt;sub&gt;3&lt;/sub&gt; production and degradation at each temperature, we estimated how much of the CHBr&lt;sub&gt;3&lt;/sub&gt; produced by &lt;em&gt;D. brightwellii&lt;/em&gt; for 7 days was degraded by the coexisting bacteria and how much remained after 7 days at each temperature. When coexisting with &lt;em&gt;P. gallaeciensis&lt;/em&gt;, the residual CHBr&lt;sub&gt;3&lt;/sub&gt; concentration in the culture was relatively higher at 20–25 °C. Similarly, when coexisting with HKF-4, it was relatively higher at 20–25 °C. To estimate the impact of future warming on CHBr&lt;sub&gt;3&lt;/sub&gt; concentrations in the oceans, we assume a 5 °C increase in sea surface temperature, with two sea surface temperatures, 15 °C and 20 °C, changing to 20 °C and 25 °C, respectively. Under this assumption, the residual concentration of CHBr&lt;sub&gt;3&lt;/sub&gt; produced by &lt;em&gt;D. brightwellii&lt;/em&gt; in seawater would be “i","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"265 ","pages":"Article 104443"},"PeriodicalIF":3.0,"publicationDate":"2024-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142040860","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}