Marine Chemistry最新文献

{"title":"QUODcarb: A Bayesian solver for over-determined datasets of seawater carbon dioxide system chemistry","authors":"Marina Fennell,&nbsp;François Primeau","doi":"10.1016/j.marchem.2024.104470","DOIUrl":"10.1016/j.marchem.2024.104470","url":null,"abstract":"<div><div>We present QUODcarb, a new solver for the CO₂-system in seawater, designed to handle any combination of system parameter measurements, whether exactly- or over-determined. QUODcarb, which stands for <strong>Q</strong>uantifying <strong>U</strong>ncertainty in an <strong>O</strong>ver-<strong>D</strong>etermined marine <strong>carb</strong>onate system, is formulated in terms of a Bayesian estimation problem. By combining prior thermodynamic information on the acid/base chemistry of CO₂ in seawater with measured parameters and their uncertainties, QUODcarb yields a probability distribution for the true CO₂-system state of a water parcel from which estimates of all system parameters with associated uncertainties can be obtained. By providing a single best estimate for the true CO₂-system state, QUODcarb enables a simplified, more accurate internal consistency analysis of the marine CO₂ system.</div><div>To demonstrate QUODcarb's utility, we analyze the GOMECC-3 dataset, that includes measurements of five CO₂-system parameters. A key finding is that by analyzing these high-quality, over-determined measurements with QUODcarb, we can achieve the GOA-ON 1 % uncertainty goal for carbonate ion concentration, even when accounting for the propagated uncertainty in the dissociation constants – a level of accuracy unattainable with exactly determined calculations. Using a single internal consistency metric, we rank 26 alternative measurement combinations, finding that (pH, <span><math><mi>p</mi><msub><mi>CO</mi><mn>2</mn></msub></math></span>) performs worst, while the combination with all five measurements performs best. Furthermore, the internally-consistent thermodynamic state estimates constrained by all five measurements fall within the range expected by the assumed measurement uncertainties for over 98 % of samples, with only minor adjustments to the dissociation constants, all of which remain within the reported uncertainties for their parameterized formulas.</div></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"268 ","pages":"Article 104470"},"PeriodicalIF":3.0,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143178132","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":"Spatiotemporal variability in benthic-pelagic coupling on the Oregon-Washington shelf","authors":"Anna Hughes ,&nbsp;Clare E. Reimers,&nbsp;Kristen E. Fogaren,&nbsp;Yvan Alleau","doi":"10.1016/j.marchem.2024.104473","DOIUrl":"10.1016/j.marchem.2024.104473","url":null,"abstract":"<div><div>Continental shelf sediments are sinks for dissolved oxygen (DO) and sources of many major and minor nutrients required for oceanic surface primary production resulting in a strong coupling between benthic and pelagic biogeochemical cycling. In this study, we present paired benthic flux and bottom water biogeochemical data collected from two Oregon shelf sites sampled approximately quarter-annually between 2017 and 2019, and from nine other shelf sites, located off central Oregon to southern Washington, and sampled in either July or September 2022. The benthic fluxes were determined using a novel set-up for <em>ex situ</em> core incubations. When fluxes were normalized to the respective measured sediment DO flux, ratios aligned well with ratios of past flux estimates from the region which were determined using <em>in situ</em> benthic chambers; however, the <em>ex situ</em> flux magnitudes are generally lower. Our findings demonstrate sediments acting as net sinks for DO and nitrate, and sources for phosphate, silicate, and ammonium. Shelf-wide estimates of the relative contribution of sediment-remineralized phosphate and silicate to surface waters on the Oregon shelf, indicate that shelf sediments supplied at least 5 ± 7 % and 37 ± 7 % of the available phosphate and silicate during recent summer upwelling seasons, with similar, respective estimates of 2 ± 9 % and 35 ± 11 % during the spring. Remineralization ratios of C:N:P:O₂ corroborate increased denitrification during the summer and weak denitrification during the winter due to a more oxygenated water column in support of previous studies. A multi-tracer water mass analysis also exhibited an increased water-column nitrate deficit during the summer and fall. Benthic denitrification rates, estimated from benthic fluxes, were between 0.2 and 1.8 mmol N m^-2 day^-1 and in the range of past assessments during the upwelling season. A simple model, applied to further constrain the contributions to bottom water fixed nitrogen (N) loss under assumptions of benthic boundary layer height and residence time, showed that although sediment denitrification could readily account for total bottom water N losses during the summer, additional water-column denitrification is indicated by the strength of early fall deficits at some stations. Constraining water-column and benthic contributions to fixed N deficits is important for understanding how N-limited primary productivity in this region will respond to projected ocean deoxygenation under anticipated global warming. These results demonstrate the interplay of sediment and water-column remineralization processes across the OR-WA shelf. As in most shallow marine systems, the two are integral to the ecosystem dynamics and responses to environmental change.</div></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"268 ","pages":"Article 104473"},"PeriodicalIF":3.0,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142759097","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":"Distribution, emission, and cycling processes of carbon monoxide in the tropical open ocean","authors":"Xuan Ji ,&nbsp;Ming-Liang Zhao ,&nbsp;Jie Ni ,&nbsp;Gao-Bin Xu ,&nbsp;Jing Zhang ,&nbsp;Gui-Peng Yang","doi":"10.1016/j.marchem.2024.104482","DOIUrl":"10.1016/j.marchem.2024.104482","url":null,"abstract":"<div><div>The carbon monoxide (CO) cycle in the marine mixed layer determines its emissions to the atmosphere and subsequently affects atmospheric chemistry and climate change. However, the contributions of oceanic CO transformation pathways and their impacting factors remain inadequately understood. Therefore, we investigated the distribution and cycle processes of CO in the Eastern Indian Ocean (EIO) and developed a CO budget model for the mixed layer. Surface seawater CO concentrations presented a diurnal variation due to periodic variations in solar radiation and rapid microbial consumption. The spatial distribution of CO in seawater was dominated by chromophoric dissolved organic matter (CDOM) and solar radiation. The EIO was a source of atmospheric CO and its daily CO emissions produced increases in the CO mixing ratio and hydroxyl radical consumption rate in the overlying atmosphere by 74.03 pptv and 6.48 pptv d⁻¹, respectively. Additionally, the budget model findings indicated that photoproduction (CDOM plus particulate organic matter), dark production, and phytoplankton emission accounted for about 67 %, 30 %, and 3 % of total CO production. The microbial consumption (94 %) and sea-air exchange (6 %) were the primary and secondary sink for CO within the mixed layer, respectively. Moreover, the photo-mineralization of dissolved organic carbon was estimated using CO as a proxy for CO₂ photoproduction. This study deepens our understanding of the oceanic CO cycle and the impact of photo-mineralization on the carbon cycle and is vital for refining global oceanic CO source-sink budgets and modelling studies.</div></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"268 ","pages":"Article 104482"},"PeriodicalIF":3.0,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143178167","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":"Corrigendum to “Spatiotemporal variability in benthic-pelagic coupling on the Oregon-Washington Shelf” [Marine Chemistry Volume 268 (2025) Article number 104473]","authors":"Anna Hughes,&nbsp;Clare E. Reimers,&nbsp;Kristen E. Fogaren ,&nbsp;Yvan Alleau","doi":"10.1016/j.marchem.2024.104485","DOIUrl":"10.1016/j.marchem.2024.104485","url":null,"abstract":"","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"268 ","pages":"Article 104485"},"PeriodicalIF":3.0,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143178133","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":"Examining nickel limitation on urea utilization by phytoplankton communities in the subtropical Pacific Ocean","authors":"Mitsuhide Sato ,&nbsp;Shigenobu Takeda","doi":"10.1016/j.marchem.2024.104484","DOIUrl":"10.1016/j.marchem.2024.104484","url":null,"abstract":"<div><div>To test the possibility of nickel (Ni) limitation and nickel‑nitrogen (Ni-N) colimitation on phytoplankton growth, seven urea/Ni enrichment experiments were conducted in the subtropical and subarctic Pacific Ocean. Effects of additions of urea, nickel, and combination of urea and nickel were examined by monitoring the growth of the whole phytoplankton community and three different phytoplankton populations, <em>Synechococcus</em>, <em>Prochlorococcus</em>, and eukaryotes. In all the experiments in the subtropical regions, urea addition significantly increased the total chlorophyll <em>a</em> concentration as compared to the unamended control after two days of incubation, confirming widespread nitrogen limitation and high accessibility of the urea‑nitrogen to phytoplankton in the subtropical Pacific. In contrast, Ni addition did not affect the total chlorophyll <em>a</em> concentration, whether it was added alone or in combination with urea. To elucidate population-level responses to urea and/or Ni addition, cellular and population chlorophyll content and carbon content were estimated using flow cytometric parameters. <em>Synechococcus</em> and <em>Prochlorococcus</em> mainly responded to the urea enrichment. The addition of Ni alone did not show a significant effect on the chlorophyll or carbon content of any phytoplankton population in most of the experiments. Ni-N colimitation was evident only for <em>Synechococcus</em>, and not for <em>Prochlorococcus</em> or eukaryotic phytoplankton. Ni-N colimitation was evident in the urea drawdown rates only for one experiment out of the six experiments. In contrast, in the subarctic region, urea drawdown decreased with Ni addition, although the reason for this was unclear. The present study demonstrates that Ni bioavailability in the subtropical Pacific can evoke Ni-N colimitation in the pico-sized cyanobacteria <em>Synechococcus</em>, but it does not seem to affect phytoplankton biomass at the community level.</div></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"268 ","pages":"Article 104484"},"PeriodicalIF":3.0,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143178169","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":"Biogeochemical cycling of dissolved Cu along the East Australian Current","authors":"Prayna P.P. Maharaj ,&nbsp;Pamela M. Barrett ,&nbsp;Michael J. Ellwood","doi":"10.1016/j.marchem.2024.104481","DOIUrl":"10.1016/j.marchem.2024.104481","url":null,"abstract":"<div><div>Copper (Cu) is an important micronutrient that is involved in multiple metabolic processes in marine phytoplankton. However, Cu concentrations that exceed an organism-specific tolerance level can be toxic. The measurement of stable Cu isotopic composition in seawater is an effective tool to better understand the biogeochemical cycling of this micronutrient in the marine environment. Here, we report the dissolved Cu (dCu) concentration and isotope composition of waters of the East Australian Current (EAC), the western boundary current in the south Pacific. The voyage was undertaken in 2018 during the austral spring as GEOTRACES process study GPpr13 consisting of a north-south transect categorised by the transition from warm, salty subtropical (ST) waters to the cold, fresh subantarctic (SA) waters in the Pacific sector of the Southern Ocean. The average dCu isotope composition (δ⁶⁵dCu) of the upper water column increased by ∼0.3 ‰ from north to south. The northern EAC stations generally had isotopically lighter dCu in surface waters, with mixed layer δ⁶⁵dCu values ranging from 0.25 ‰ to 0.31 ‰. Mixed layer δ⁶⁵dCu values ranged from 0.20 ‰ to 0.47 ‰ at the southern extension of the EAC and from 0.54 ‰ to 0.63 ‰ in the subantarctic zone. Generally, δ⁶⁵dCu profiles showed significant variability in the upper water column (200 m). The δ⁶⁵dCu composition was heavier at depths of chlorophyll <em>a</em> maxima, particularly for the high productivity stations, which can be attributed to either biological uptake and/or scavenging. A heavier surface δ⁶⁵dCu isotopic signature relative to deeper waters was also observed at stations with low chlorophyll <em>a</em> concentrations due to strong organic complexation of the heavy isotope in the upper water column. The deep ocean (≥2000 m) δ⁶⁵dCu at one of the subantarctic stations (station 10) was considerably lighter (0.25 ± 0.06 ‰), indicating a possible benthic supply of isotopically light Cu. This study provides a high-resolution δ⁶⁵Cu dataset, affording new insights into the biogeochemical cycling of Cu in the ocean.</div></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"268 ","pages":"Article 104481"},"PeriodicalIF":3.0,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143177296","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":"Boron to salinity ratios in the Fram Strait entering the Central Arctic: The role of sea ice formation and future predictions","authors":"Samantha Rush ,&nbsp;Penny Vlahos ,&nbsp;Chang-Ho Lee ,&nbsp;Kitack Lee ,&nbsp;Lauren J. Barrett","doi":"10.1016/j.marchem.2024.104463","DOIUrl":"10.1016/j.marchem.2024.104463","url":null,"abstract":"<div><div>The Arctic Ocean's sea ice loss dynamically impacts carbon uptake potential, as assessed through measured carbonate parameters, such as total alkalinity. In the open ocean, boron (B) is the third largest contributor to alkalinity via borate and is usually accounted for through the conservative boron to salinity ratio (B/S), and not directly measured. Here, we present findings on non-conservative boron dynamics, that results in significant B/S deviations, observed in ice melt zone waters, snow, slush, brine, and annual sea ice (<em>n</em> = 169) in the Fram Strait entering the Central Arctic. These samples were collected during the onset of the melt season on the 2023 ARTofMELT expedition, covering a wide practical salinity range (2–59). Barring snow, the average B/S ratio across the study was 0.1321 ± 0.0032 mg kg⁻¹ ‰⁻¹, similar to the mean B/S ratio measured amongst several polar water masses near Iceland, as well as the accepted B/S for other ocean regions. Results indicate minor deviations from accepted B/S ratios (indicating conservative behavior) across the sample practical salinity range and reflect an uncertainty in the borate contribution to total alkalinity of less than 2.9 μmol kg⁻¹ at in-situ temperatures. B fractionation appears to occur during sea ice formation, causing greater B in the sea ice reservoir whereas brine, slush, lead, and under-ice water reservoirs are depleted in B. As such, under-ice and lead, brine, and slush samples all had measured B/S ratios (0.1305 ± 0.0011, 0.1305 ± 0.0018, and 0.1304 ± 0.0017 mg kg⁻¹ ‰⁻¹, respectively) lower than the established ratio whereas the average sea ice B/S ratio (0.1331 ± 0.0035 mg kg⁻¹ ‰⁻¹) was closest to accepted values (0.1336 ± 0.0005 mg kg⁻¹ ‰⁻¹). Arctic open ocean samples also had a lower B/S ratio (0.1304 ± 0.0014 mg kg⁻¹ ‰⁻¹). Our findings, together with a previous Arctic B ice study, suggest that B (probably in the form of B(OH)₄⁻) is incorporated into authigenic CaCO₃ minerals, replacing CO₃²⁻ within the mineral lattice during sea ice formation. This process consequentially lowers the B/S ratio in the open Arctic Ocean, compared to the established global ocean ratio. Nevertheless, the incorporation of B into the sea ice reservoir does not fully account for the deficit of B in the Arctic Ocean samples, suggesting further accounting of B Arctic pathways is necessary. In future climate scenarios involving increased sea ice melt, the transition from multiyear to annual sea ice, permafrost thaw, and increased riverine discharge, the behavior of B in the Arctic Ocean is expected to become more dynamic.</div></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"267 ","pages":"Article 104463"},"PeriodicalIF":3.0,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142528416","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":"Spatial and temporal dynamics of groundwater biogeochemistry in the deep subsurface of a high-energy beach","authors":"Anja Reckhardt ,&nbsp;Rena Meyer ,&nbsp;Stephan L. Seibert ,&nbsp;Janek Greskowiak ,&nbsp;Magali Roberts ,&nbsp;Simone Brick ,&nbsp;Grace Abarike ,&nbsp;Kojo Amoako ,&nbsp;Hannelore Waska ,&nbsp;Kai Schwalfenberg ,&nbsp;Iris Schmiedinger ,&nbsp;Oliver Wurl ,&nbsp;Michael Ernst Böttcher ,&nbsp;Gudrun Massmann ,&nbsp;Katharina Pahnke","doi":"10.1016/j.marchem.2024.104461","DOIUrl":"10.1016/j.marchem.2024.104461","url":null,"abstract":"<div><div>Intertidal sandy beach systems are considered complex biogeochemical reactors. At beach sites that are subject to high tidal and wave energy, seawater circulation can reach tens of meters deep into the subsurface and changing environmental conditions are assumed to lead to dynamic groundwater flow paths, saltwater-freshwater mixing zones, and a spatio-temporally variable groundwater biogeochemistry. Previous studies mainly focused on the upper meters of subterranean estuaries (STE), while the deep subsurface remained a black box. This study presents spatial (cross-shore) and temporal (∼ six-weekly, over 1.5 years) dynamics of the groundwater biogeochemistry that were observed down to 24 m below the ground surface (mbgs) of a sandy high-energy beach on Spiekeroog Island (Germany).</div><div>In addition to redox conditions along a cross-shore transect ranging from oxic to Fe oxide reducing/slightly sulfidic, we found a previously unknown, distinct vertical redox zonation as well. Temporal variations of the biogeochemistry within low salinity groundwater at the most landward station close to the dune base were mainly driven by storm flood related seawater infiltration. Around the high water line, the extent of the upper saline plume (USP) varied over time. Furthermore, temporal dynamics of the O₂ saturation at 6 mbgs indicated a seasonally shifting depth of the oxycline at this location. In the lower intertidal zone, groundwater solute concentrations displayed a temporally variable zone of deep freshwater discharge.</div><div>Regarding the impact of the deep STE on the groundwater biogeochemistry of the discharge zone, our data revealed that nutrient, Mn, and Fe release along the deep flow paths through the USP towards the discharge zone was limited, likely due decreasing availability of labile organic matter and subsequent slowing down of metabolic processes with depth. High concentrations of metabolites in the upper ∼ 2 mbgs of the discharge zone were, therefore, rather attributed to the incorporation of labile organic matter during continuous and storm flood related sediment relocation and/or the contribution of older waters, e.g., the subtidal saltwater wedge.</div></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"267 ","pages":"Article 104461"},"PeriodicalIF":3.0,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142446926","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":"Nitrous oxide variability along an estuary influenced by agricultural land use (Guadalquivir estuary, SW Spain)","authors":"J. Sánchez-Rodríguez ,&nbsp;A. Sierra ,&nbsp;S. Moreno ,&nbsp;J. Forja ,&nbsp;T. Ortega","doi":"10.1016/j.marchem.2024.104467","DOIUrl":"10.1016/j.marchem.2024.104467","url":null,"abstract":"<div><div>The Guadalquivir Estuary is the largest estuary in the southwest basin of the Iberian Peninsula, which is subject to strong anthropogenic influence such as the damming or the multitude of crop fields on its margins. Nitrous Oxide (N₂O) variability is analysed considering the influence of temperature, salinity, water-atmosphere fluxes, benthic fluxes, reactivity and lateral inputs. N₂O increases along the salinity gradient, with values ranging from 5.9 to 103.3 nmol L⁻¹. Thus, values of N₂O concentration are very close to equilibrium with the atmosphere at the mouth, while in the inner zone the fluxes to the atmosphere are higher, showing the greatest variability of N₂O in the estuary (74.26 ± 7.41 μmol m⁻² d⁻¹). Sediments act as a source of N₂O to the water column, with benthic fluxes presenting a wide range from 2 to 20 μmol m⁻² d⁻¹. Denitrification processes in the sediments may be important in the inner part of the estuary, where negative benthic fluxes of nitrate have been observed. Production rates of N₂O in the water column are estimated from incubation experiments, resulting in higher production with temperature, and lower with salinity. Lateral inputs are calculated by balance of the different processes characterized and seems to be an important factor influencing N₂O variability in the inner zone of the estuary.</div></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"267 ","pages":"Article 104467"},"PeriodicalIF":3.0,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142656456","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":"2024-11-01","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}