Marine Chemistry最新文献

{"title":"Distributions of zirconium, hafnium, and niobium in the Indian Ocean: Influence of lithogenic sources on incompatible elements","authors":"Ryuta Ueki,&nbsp;Linjie Zheng,&nbsp;Shotaro Takano,&nbsp;Yoshiki Sohrin","doi":"10.1016/j.marchem.2024.104365","DOIUrl":"10.1016/j.marchem.2024.104365","url":null,"abstract":"<div><p>Zirconium (Zr), hafnium (Hf), and niobium (Nb) are incompatible elements concentrated on the granitic continent. They are trace elements at the pmol/kg level in seawater and are considered potential tracers for water masses. However, data on the distribution of the three elements in modern oceans are limited, particularly in the Indian Ocean. Here, we report the first basin-scale sectional distributions of the three elements at 11 stations from 62°S to 17°N in the Indian Ocean and Indian sector of the Southern Ocean. Unfiltered and filtered seawater samples were stored in low-density polyethylene (LDPE) bottles for approximately 12 years and used to determine the concentrations of the total dissolvable (td) and dissolved (d) fractions, respectively. We found that the absorption percentages on the bottle wall were &lt;10% for Zr, Hf, and Nb. The concentration ranges of dZr, dHf, and dNb in the Indian Ocean and Indian sector of the Southern Ocean were 8–348, 0.06–1.06, and 1.3–4.3 pmol/kg, respectively. The labile particulate (lp) concentration was obtained as the difference between td and d, which was less than the detection limit in most samples. The concentrations of dZr, dHf, and dNb in surface water were high in the Bay of Bengal and Arabian Sea, and the concentrations of Zr and Hf in the deep waters of the Indian Ocean were higher than those in the deep waters of the North Pacific Ocean in a similar manner with dAl. These results indicate that the Indian Ocean has strong influences of lithogenic sources for Al, Zr, and Hf. The dZr/dHf mole ratio characterized water masses in the Indian Ocean and increased in the following order: Atlantic Ocean &lt; Indian Ocean &lt; Pacific Ocean due to the preferential removal of dHf over dZr during thermohaline circulation and the local input of dZr and dHf in the Indian Ocean. Thus, we propose that the dZr/dHf ratio is a potential tracer for global ocean circulation.</p></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"260 ","pages":"Article 104365"},"PeriodicalIF":3.0,"publicationDate":"2024-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0304420324000161/pdfft?md5=92afd9a4a3380757b101d4418e8974ae&pid=1-s2.0-S0304420324000161-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139949474","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":"Dissolved zinc in the western Bering Sea and near Kamchatka Strait: A coastal source and transport to the subarctic Pacific","authors":"Kuo Hong Wong ,&nbsp;Hajime Obata ,&nbsp;Taejin Kim ,&nbsp;Hirofumi Tazoe ,&nbsp;Asami S. Mashio ,&nbsp;Hiroshi Hasegawa ,&nbsp;Jun Nishioka","doi":"10.1016/j.marchem.2024.104375","DOIUrl":"10.1016/j.marchem.2024.104375","url":null,"abstract":"<div><p>Dissolved zinc (dZn) is an important micronutrient for phytoplankton in the ocean. In high nutrient low chlorophyll (HNLC) regions like the western Bering Sea basin, Zn deficiency might induce shifts in phytoplankton community species. In this study, we presented the first dZn distribution data in the western Bering Sea and near Kamchatka Strait and investigated the biogeochemical cycles of Zn in these regions. Although dZn and silicate (Si) show similar distribution patterns in the global ocean, there is an excess of dZn relative to Si in the intermediate waters of our study region, similar to that previously observed in the subarctic Pacific. The uptake and subsequent regeneration patterns of dZn, Si, and phosphate (PO₄) in the study region reveal that excess dZn in the subarctic Pacific is not derived from biogenic processes, because the uptake and regeneration ratios of dZn to phosphate (PO₄) cannot account for the additional dZn supplied. Instead, our analyses indicate that a significant proportion of dZn in the region originates from the non-reductive release from shelf sediments. dZn concentrations were elevated in coastal regions at the same isopycnal where excess dZn was observed in the subarctic Pacific, suggesting that some of these sediment-derived dZn were transported to the subarctic Pacific.</p></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"260 ","pages":"Article 104375"},"PeriodicalIF":3.0,"publicationDate":"2024-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140127159","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":"Low-blank method for the offline batch analysis of the low concentration of dissolved lead in natural waters and its application to natural waters, including the tropical Northwest Pacific Ocean","authors":"Shuo Jiang ,&nbsp;Jing Zhang ,&nbsp;Zheng Bo Liu ,&nbsp;Han Su","doi":"10.1016/j.marchem.2024.104374","DOIUrl":"https://doi.org/10.1016/j.marchem.2024.104374","url":null,"abstract":"<div><p>In this study, Presep® PolyChelate resin was utilized for the offline batch extraction process and then combined with the isotope dilution method for the analysis of low concentrations of dissolved lead (Pb) in freshwater and seawater. The application of Presep® PolyChelate resin further lowered the procedural blank by reducing the amount of resin beads and buffer solution that were added with an 8-fold preconcentration. The adsorption and elution times were shortened to 2 d and 30 min, respectively, and &gt; 85% recovery was achieved. The total procedural blank and detection limit were 0.2 ± 0.1 pmol/kg and 0.2 pmol/kg, respectively. The accuracy of this method was also verified using GEOTRACES intercalibration SAFe seawaters, with concentrations of 48.0 ± 0.5 pmol/kg (<em>n</em> = 3) and 27.0 ± 0.7 pmol/kg (n = 3) observed for SAFE S and D2, respectively. Full-depth profiles of dissolved Pb concentrations collected during the 2016 tropical Northwest Pacific Ocean cruise were analyzed. The dissolved Pb concentration increased from 30 pmol/kg at the surface to 50 pmol/kg at the subsurface and it then decreased to 8–9 pmol/kg in the bottom waters.</p></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"260 ","pages":"Article 104374"},"PeriodicalIF":3.0,"publicationDate":"2024-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140122886","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":"Dynamic distribution and photochemical-microbial coupling degradation of dissolved organic matter in a large river-Influenced Bay","authors":"Mingzheng Zhang ,&nbsp;Xinke Wang ,&nbsp;Shengkang Liang ,&nbsp;Haoyang Ma ,&nbsp;Yanqun Yang ,&nbsp;Hongguan Li ,&nbsp;Shanshan Li ,&nbsp;Xihua Yu","doi":"10.1016/j.marchem.2024.104366","DOIUrl":"10.1016/j.marchem.2024.104366","url":null,"abstract":"<div><p>A large river-influenced offshore area is the junction where land and open sea meet, which is important in the biogeochemical processes of dissolved organic matter (DOM). Because hydrodynamic and biogeochemical processes are complex, processes such as the photochemical and microbial degradation of DOM are poorly understood. In this study, to further understand the degradation mechanisms of DOM from different sources, water was sampled from three cruises during autumn 2018 and spring and summer 2019 in Laizhou Bay (LZB), as this bay is greatly influenced by the Yellow River. Field incubation experiments examining the riverine, mixed, and marine DOM photochemical and microbial degradation processes alone or in combination were conducted onboard. Due to the dual influence of the Yellow River input and phytoplankton autogenous production, dissolved organic carbon (DOC) and chromophoric DOM (CDOM) show relatively conservative mixing behaviour with maximum values in summer, and the S₂₇₅_–₂₉₅ gradually increases from the river to nearshore. In addition, it is indicated that higher primary productivity from large nutrient inputs in areas with moderate salinity during the summer is often accompanied by higher bioavailability DOM based on field investigation results. Various sources of DOM have different sensitivities to photochemical and microbial degradation due to their components and properties. Riverine DOM is susceptible to photochemical degradation, while marine DOM is more susceptible to microbial degradation. Moreover, the low-molecular-weight organic matter produced by photochemical degradation effectively promotes the microbial degradation of DOM from riverine sources, whereas photodegradation from mixed and marine sources do not significantly increase the biodegradation efficiency due to the low content of aromatic substances. Furthermore, photoammonification and bioammonification of autochthonous and allochthonous DOM may be the potential processes driving ammonia regeneration.</p></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"260 ","pages":"Article 104366"},"PeriodicalIF":3.0,"publicationDate":"2024-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139949421","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":"On-chip label-free sorting and enrichment of microplastic particles by using deterministic lateral displacement","authors":"Kai Zhao ,&nbsp;Jianhong Dong ,&nbsp;Dejian Kong ,&nbsp;Junzhu Yao ,&nbsp;Yiming Yao ,&nbsp;Junsheng Wang","doi":"10.1016/j.marchem.2024.104364","DOIUrl":"https://doi.org/10.1016/j.marchem.2024.104364","url":null,"abstract":"<div><p>A novel deterministic lateral displacement (DLD) method employing a pressure-driven flow for the continuous size-based separation of microplastic particles is presented in this paper. To induce the DLD effect, arrays of triangular posts were designed to enhance the sorting resolution and reduce the particles clogging. For the particles with a diameter larger than the critical diameter (<span><math><msub><mi>D</mi><mi>c</mi></msub></math></span>) in the DLD device, they move in bump mode with collision to microposts. While, the particles flow in zigzag mode if their sizes are below the <span><math><msub><mi>D</mi><mi>c</mi></msub></math></span> value. The DLD microfluidic chip enables simplified fabrication process and shows property of label-free and high throughput. Numerical studies were conducted to discuss the <span><math><msub><mi>D</mi><mi>c</mi></msub></math></span> values in the microchannel with horizontally symmetrical and asymmetrical posts, where <span><math><msub><mi>D</mi><mi>c</mi></msub></math></span> was found smaller in the asymmetric horizontal flow, enabling higher separation sensitivity and resolution. Experiments were conducted to demonstrate the separation of 10 μm and 15 μm polystyrene microplastic particles, and different types of polystyrene and polyethylene microplastic particles by adjusting the flow rates. In order to achieve successful separation, the flow rates between the sheath flow and the sample solution were well matched. In this way, the proposed DLD microfluidic chip with horizontally asymmetrical triangular posts shows property of label-free, high throughput, capability to analyze microplastic particle selectively and sensitively, possibility of sorting nanoplastic particles.</p></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"260 ","pages":"Article 104364"},"PeriodicalIF":3.0,"publicationDate":"2024-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139915009","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":"Recommendations for best practice for iron speciation by competitive ligand exchange adsorptive cathodic stripping voltammetry with salicylaldoxime","authors":"Léo Mahieu ,&nbsp;Dario Omanović ,&nbsp;Hannah Whitby ,&nbsp;Kristen N. Buck ,&nbsp;Salvatore Caprara ,&nbsp;Pascal Salaün","doi":"10.1016/j.marchem.2023.104348","DOIUrl":"10.1016/j.marchem.2023.104348","url":null,"abstract":"<div><p><span><span>The method of competitive ligand exchange followed by adsorptive </span>cathodic stripping voltammetry (CLE-AdCSV) allows for the determination of dissolved iron (DFe) organic speciation parameters, i.e., ligand concentration (L</span>_Fe) and conditional stability constant (log <span><math><msubsup><mi>K</mi><mrow><mi>Fe</mi><mo>′</mo><mi>L</mi></mrow><mtext>cond</mtext></msubsup></math></span><span>). Investigation of DFe organic speciation by CLE-AdCSV has been conducted in a wide range of marine systems, but aspects of its application pose challenges that have yet to be explicitly addressed. Here, we present a set of observations and recommendations to work toward establishing best practice for DFe organic speciation measurements using the added ligand salicylaldoxime (SA). We detail conditioning procedures to ensure a stable AdCSV signal and discuss the processes at play during conditioning. We also present step-by-step guidelines to simplify CLE-AdCSV data treatment and interpretation using the softwares ECDSoft and ProMCC and a custom spreadsheet. We validate our application and interpretation methodology with the model siderophore<span> deferoxamine B (DFO-B) in a natural seawater sample. The reproducibility of our application and interpretation methodology was evaluated by running duplicate titrations on 19 samples, many of which had been refrozen prior to the duplicate analysis. Nevertheless, 50% of the duplicate analyses agreed within 10% of their relative standard deviation (RSD), and up to 80% within 25% RSD, for both L</span></span>_Fe and log <span><math><msubsup><mi>K</mi><mrow><mi>Fe</mi><mo>′</mo><mi>L</mi></mrow><mtext>cond</mtext></msubsup></math></span>. Finally, we compared the sequential addition and equilibration of DFe and SA with overnight equilibration after simultaneous addition of DFe and SA on 24 samples. We found a rather good agreement between both procedures, with 60% of samples within 25% RSD for L_Fe (and 43% of samples for log <span><math><msubsup><mi>K</mi><mrow><mi>Fe</mi><mo>′</mo><mi>L</mi></mrow><mtext>cond</mtext></msubsup></math></span>), and it was not possible to predict differences in L_Fe or log <span><math><msubsup><mi>K</mi><mrow><mi>Fe</mi><mo>′</mo><mi>L</mi></mrow><mtext>cond</mtext></msubsup></math></span> based on the method applied, suggesting specific association/dissociation kinetics for different ligand assemblages. Further investigation of the equilibration kinetics against SA may be helpful as a potential way to distinguish natural ligand assemblages.</p></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"259 ","pages":"Article 104348"},"PeriodicalIF":3.0,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139092324","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":"Trace and rare earth element systematics of cold-seep carbonates from the Krishna-Godavari basin: A comparison between isotopically distinct carbonate deposits","authors":"Muralidhar Kocherla ,&nbsp;Durbar Ray ,&nbsp;M. Satyanarayanan ,&nbsp;H.M. João ,&nbsp;Christo Sojan","doi":"10.1016/j.marchem.2024.104363","DOIUrl":"https://doi.org/10.1016/j.marchem.2024.104363","url":null,"abstract":"<div><p>Mineralogical and isotopically distinct authigenic carbonates from the zones of methane oxidation and methanogenesis in the cold-seep environment, from the Krishna-Godavari basin are investigated for major, trace, and rare earth element compositions. For this study, the elemental compositions of the ¹³C-depleted carbonate phase (δ¹³C &lt; −45‰) developed under the influence of anaerobic methane oxidation in the shallow parts (&lt;115mbfs) of a sediment core, are compared with those in isotopically heavier siderite (δ¹³C &gt; +5‰) from the zone of microbial methanogenesis at the deeper sediment depths (115-197mbfs). Results showed both types of cold-seep carbonate in two geochemical regimes have a comparable range of concentrations of redox-sensitive (e.g. V, Cr, Co, Ni, Zn) and refractory elements (e.g. Sc, Cs, Ga, Zr, Hf, Ta, Th), indicating limited impacts of mineralogy and their genetic processes on the distribution of these elements. In contrast, the degree of enrichments of elements like Si, Al, Sr, Y, HREE, and U in those isotopically discrete seep carbonates were distinctly different. Such compositional variability in two types of authigenic carbonates is described in terms of their diverse formation mechanisms, mineralogical controls, and variable contributions of terrigenous materials.</p></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"259 ","pages":"Article 104363"},"PeriodicalIF":3.0,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139737541","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":"Detection of impurities in m-cresol purple with Soft Independent Modeling of Class Analogy for the quality control of spectrophotometric pH measurements in seawater","authors":"Michael B. Fong ,&nbsp;Yuichiro Takeshita ,&nbsp;Regina A. Easley ,&nbsp;Jason F. Waters","doi":"10.1016/j.marchem.2024.104362","DOIUrl":"https://doi.org/10.1016/j.marchem.2024.104362","url":null,"abstract":"<div><p>Accurate spectrophotometric pH measurements in seawater are critical to documenting long-term changes in ocean acidity and carbon chemistry, and for calibration of autonomous pH sensors. The recent development of purified indicator dyes greatly improved the accuracy of spectrophotometric pH measurements by removing interfering impurities that cause biases in pH that can grow over the seawater pH range to &gt; 0.01 above pH 8. However, some batches of purified indicators still contain significant residual impurities that lead to unacceptably large biases in pH for oceanic and estuarine <em>climate quality</em> measurements. While high-performance liquid chromatography (HPLC) is the standard method for verifying dye purity, alternative approaches that are simple to implement and require less specialized equipment are desirable. We developed a model to detect impurities in the pH indicator <em>m-</em>cresol purple (<em>m</em>CP) using a variant of the classification technique Soft Independent Modeling of Class Analogy (SIMCA). The classification model was trained with pure <em>m</em>CP spectra (350 nm to 750 nm at 1 nm resolution) at pH 12 and tested on independent samples of unpurified and purified <em>m</em>CP with varying levels of impurities (determined by HPLC) and measured on two different spectrophotometers. All the dyes identified as pure by the SIMCA model were sufficiently low in residual impurities that their apparent biases in pH were &lt; 0.002 in buffered artificial seawater solutions at a salinity of 35 and over a pH range of 7.2 to 8.2. Other methods that can also detect residual impurities relevant to <em>climate quality</em> measurements include estimating the impurity absorption at 434 nm and assessing the apparent pH biases relative to a reference purified dye in buffered solutions or natural seawater. Laboratories that produce and distribute purified <em>m</em>CP should apply the SIMCA method or other suitable methods to verify that residual impurities do not significantly bias pH measurements. To apply the SIMCA method, users should download the data and model developed in this work and measure a small number of instrument standardization and model validation samples. This method represents a key step in the development of a measurement quality framework necessary to attain the uncertainty goals articulated by the Global Ocean Acidification Observing Network (GOA-ON) for <em>climate quality</em> measurements (i.e., ±0.003 in pH).</p></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"259 ","pages":"Article 104362"},"PeriodicalIF":3.0,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139726559","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":"Regeneration of sedimentary phosphorus and iron in a large seasonally hypoxic estuary deciphered by 224Ra/228Th disequilibria","authors":"Zhongliang Lin ,&nbsp;Yilin Cheng ,&nbsp;Ergang Lian ,&nbsp;Tong Wu ,&nbsp;Lin Wei ,&nbsp;Xiangming Shi ,&nbsp;Xinyu Jiang ,&nbsp;Liuting Yuan ,&nbsp;Shouye Yang ,&nbsp;Pinghe Cai","doi":"10.1016/j.marchem.2024.104354","DOIUrl":"10.1016/j.marchem.2024.104354","url":null,"abstract":"<div><p>Using a ²²⁴Ra/²²⁸<span><span>Th disequilibrium approach, we demonstrate in this study that benthic fluxes of </span>dissolved inorganic phosphorus<span><span> (DIP) in the seasonally hypoxic Yangtze River Estuary were largely manipulated by two counteracting processes: the decomposition of sedimentary organic matter and adsorption of DIP onto iron (Fe) oxides. The decomposition rate of sedimentary organic matter rose exponentially with bottom water dissolved oxygen (DO) concentration multiplied by the amplification factor of sediment surface area (ξ), a variable used to describe the intensity of bio-irrigation and physical reworking in the sediment deposit. In the summer of 2020, the Yangtze River catchment encountered the largest flood event in the past 20 years. As a result of enhanced physical reworking of the seabed, </span>dissolved inorganic carbon (DIC) flux increased by approximately 4-fold as compared to the summer of 2019 (657 vs. 154 mmol m</span></span>⁻² d⁻¹). DIP flux exhibited similar inter-annual variations to DIC flux, indicating that changes in the decomposition rate of sedimentary organic matter were the main cause of the inter-annual differences in DIP flux (1.5 mmol m⁻² d⁻¹ in 2020 vs. 0.3 mmol m⁻² d⁻¹ in 2019). On the other hand, benthic dissolved Fe fluxes declined exponentially with rising DO concentration because of re-oxidation of Fe²⁺<span> in porewater into Fe oxides. As a consequence, approximately 90% of DIP sourced from the decomposition of sedimentary organic matter was retained within the sediment when the bottom water was well oxygenated (DO &gt;125 μmol l</span>⁻¹). Our results imply that regeneration of sedimentary P and Fe may be efficient only within a very narrow redox window where DO concentrations are below a threshold value of ∼60 μmol l⁻¹, but bio-irrigation or physical reworking is still active.</p></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"259 ","pages":"Article 104354"},"PeriodicalIF":3.0,"publicationDate":"2024-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139495115","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":"Exploration of the nitrification process in surface sediment of a hypereutrophic intertidal zone via hydroxylamine monitoring","authors":"Ami Natori ,&nbsp;Yuuki Sanada ,&nbsp;Shogo Sugahara ,&nbsp;Seiichi Nohara ,&nbsp;Yasushi Seike ,&nbsp;Yukiko Senga","doi":"10.1016/j.marchem.2024.104353","DOIUrl":"10.1016/j.marchem.2024.104353","url":null,"abstract":"<div><p><span>Hydroxylamine is considered an indicator of nitrification, as it is both produced and consumed during the ammonium (NH</span>₄⁺<span>) oxidation process. In this study, to explore the site of active nitrification and elucidate the factors controlling nitrification, hydroxylamine concentrations in the seawater<span><span> and porewater of the hypereutrophic Yatsu </span>tidal flat, eastern Japan, were measured using the iodine oxidation method with a Sep-Pak C</span></span>₁₈ cartridge. The concentrations over approximately 2 years indicated that nitrification was more active in the surface sediment than in seawater. This would support denitrification in the surface sediment via active nitrification–denitrification, which removes N. In addition, multiple linear regression analysis indicated that the concentration in porewater was positively correlated with the seawater parameters of nitrate (NO₃⁻) concentration, NH₄⁺ concentration, and temperature, while among porewater parameters, it was negatively correlated with the phosphate (PO₄³⁻) concentration and positively correlated with the NH₄⁺ concentration. These relationships between hydroxylamine concentration and environmental factors suggest that porewater nitrification increases with higher temperature and NH₄⁺<span> supply from seawater and porewater, as well as under oxic conditions. Our results demonstrate that hydroxylamine is a useful indicator of sediment nitrification in the hypereutrophic intertidal zone.</span></p></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"259 ","pages":"Article 104353"},"PeriodicalIF":3.0,"publicationDate":"2024-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139495221","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}