Pub Date : 2025-01-01DOI: 10.1016/j.marchem.2024.104471
Dora Crmarić, Saša Marcinek, Ana-Marija Cindrić, Dario Omanović, Elvira Bura-Nakić
An adapted solid-phase extraction method was used for Cu redox speciation in the dissolved fraction in the stratified Krka River estuary in March and July 2023 at a “clean” and a “polluted” site, while anodic stripping voltammetry in differential pulse mode was used for Cu determination in the Cu(I), Cu(II) and CuT fractions. Overall, [Cu(I)]/[CuT] was significant in the Krka River estuary and varied between 20.7 and 88.7 %. At the “clean” site E1, the surface maximum of [Cu(I)]/[CuT] was observed in March. This was assumed to be related to the biological activity of the freshwater biota, as the temperature rose in March (compared to the previous winter months) and the salinity was low. On the other hand, at E1 in July, the maximum of [Cu(I)]/[CuT] was observed at the halocline and corresponded to the highest biological production thus we hypothesised it to be the result of Cu(I) complexation with ligands of biological origin. The minimum of [Cu(I)]/[CuT] was observed at the surface at E1 in July where terrestrial humic-like substances were present with higher affinity for Cu(II) than for Cu(I). At the “polluted site” E2 high [Cu(I)]/[CuT] values were observed at both the surface and the halocline in March. However, [Cu(I)]/[CuT] maximum was observed at the halocline at E2 in July and was associated with the highest biological production, as also observed at E1 in July. Nevertheless, the stabilisation of Cu(I) by chloride should not be disregarded as it maintained relatively high [Cu(I)]/[CuT] in the seawater layer at both stations in March and July. The fluctuations in [Cu(I)]/[CuT] occurred during the day at the surface at E2 in July, with the minimum of [Cu(I)]/[CuT] observed in the early morning, followed by an increase in [Cu(I)]/[CuT] during the day, indicating the importance of photochemical reactions in the Cu(I) formation and stabilisation.
{"title":"Redox speciation of copper in the estuarine environment: Towards better understanding of copper water chemistry","authors":"Dora Crmarić, Saša Marcinek, Ana-Marija Cindrić, Dario Omanović, Elvira Bura-Nakić","doi":"10.1016/j.marchem.2024.104471","DOIUrl":"10.1016/j.marchem.2024.104471","url":null,"abstract":"<div><div>An adapted solid-phase extraction method was used for Cu redox speciation in the dissolved fraction in the stratified Krka River estuary in March and July 2023 at a “clean” and a “polluted” site, while anodic stripping voltammetry in differential pulse mode was used for Cu determination in the Cu(I), Cu(II) and Cu<sub>T</sub> fractions. Overall, [Cu(I)]/[Cu<sub>T</sub>] was significant in the Krka River estuary and varied between 20.7 and 88.7 %. At the “clean” site E1, the surface maximum of [Cu(I)]/[Cu<sub>T</sub>] was observed in March. This was assumed to be related to the biological activity of the freshwater biota, as the temperature rose in March (compared to the previous winter months) and the salinity was low. On the other hand, at E1 in July, the maximum of [Cu(I)]/[Cu<sub>T</sub>] was observed at the halocline and corresponded to the highest biological production thus we hypothesised it to be the result of Cu(I) complexation with ligands of biological origin. The minimum of [Cu(I)]/[Cu<sub>T</sub>] was observed at the surface at E1 in July where terrestrial humic-like substances were present with higher affinity for Cu(II) than for Cu(I). At the “polluted site” E2 high [Cu(I)]/[Cu<sub>T</sub>] values were observed at both the surface and the halocline in March. However, [Cu(I)]/[Cu<sub>T</sub>] maximum was observed at the halocline at E2 in July and was associated with the highest biological production, as also observed at E1 in July. Nevertheless, the stabilisation of Cu(I) by chloride should not be disregarded as it maintained relatively high [Cu(I)]/[Cu<sub>T</sub>] in the seawater layer at both stations in March and July. The fluctuations in [Cu(I)]/[Cu<sub>T</sub>] occurred during the day at the surface at E2 in July, with the minimum of [Cu(I)]/[Cu<sub>T</sub>] observed in the early morning, followed by an increase in [Cu(I)]/[Cu<sub>T</sub>] during the day, indicating the importance of photochemical reactions in the Cu(I) formation and stabilisation.</div></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"268 ","pages":"Article 104471"},"PeriodicalIF":3.0,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143177276","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}
Pub Date : 2025-01-01DOI: 10.1016/j.marchem.2024.104470
Marina Fennell, François Primeau
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 Quantifying Uncertainty in an Over-Determined marine carbonate 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.
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, ) 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.
{"title":"QUODcarb: A Bayesian solver for over-determined datasets of seawater carbon dioxide system chemistry","authors":"Marina Fennell, 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 CO<sub>2</sub>-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 CO<sub>2</sub> in seawater with measured parameters and their uncertainties, QUODcarb yields a probability distribution for the true CO<sub>2</sub>-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 CO<sub>2</sub>-system state, QUODcarb enables a simplified, more accurate internal consistency analysis of the marine CO<sub>2</sub> system.</div><div>To demonstrate QUODcarb's utility, we analyze the GOMECC-3 dataset, that includes measurements of five CO<sub>2</sub>-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}
Pub Date : 2025-01-01DOI: 10.1016/j.marchem.2024.104482
Xuan Ji , Ming-Liang Zhao , Jie Ni , Gao-Bin Xu , Jing Zhang , Gui-Peng Yang
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.
{"title":"Distribution, emission, and cycling processes of carbon monoxide in the tropical open ocean","authors":"Xuan Ji , Ming-Liang Zhao , Jie Ni , Gao-Bin Xu , Jing Zhang , 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<sup>−1</sup>, 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 CO<sub>2</sub> 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}
Pub Date : 2025-01-01DOI: 10.1016/j.marchem.2024.104485
Anna Hughes, Clare E. Reimers, Kristen E. Fogaren , Yvan Alleau
{"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, Clare E. Reimers, Kristen E. Fogaren , 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}
Pub Date : 2025-01-01DOI: 10.1016/j.marchem.2024.104484
Mitsuhide Sato , Shigenobu Takeda
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, Synechococcus, Prochlorococcus, and eukaryotes. In all the experiments in the subtropical regions, urea addition significantly increased the total chlorophyll a 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 a 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. Synechococcus and Prochlorococcus 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 Synechococcus, and not for Prochlorococcus 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 Synechococcus, but it does not seem to affect phytoplankton biomass at the community level.
{"title":"Examining nickel limitation on urea utilization by phytoplankton communities in the subtropical Pacific Ocean","authors":"Mitsuhide Sato , 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}
Pub Date : 2025-01-01DOI: 10.1016/j.marchem.2024.104481
Prayna P.P. Maharaj , Pamela M. Barrett , Michael J. Ellwood
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 a 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 a 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.
{"title":"Biogeochemical cycling of dissolved Cu along the East Australian Current","authors":"Prayna P.P. Maharaj , Pamela M. Barrett , 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 (δ<sup>65</sup>dCu) 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 δ<sup>65</sup>dCu values ranging from 0.25 ‰ to 0.31 ‰. Mixed layer δ<sup>65</sup>dCu 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, δ<sup>65</sup>dCu profiles showed significant variability in the upper water column (200 m). The δ<sup>65</sup>dCu 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 δ<sup>65</sup>dCu 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) δ<sup>65</sup>dCu 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 δ<sup>65</sup>Cu 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}
Pub Date : 2024-11-26DOI: 10.1016/j.marchem.2024.104473
Anna Hughes , Clare E. Reimers, Kristen E. Fogaren, Yvan Alleau
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 ex situ 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 in situ benthic chambers; however, the ex situ 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.
大陆架沉积物是溶解氧（DO）的汇，也是海洋表面初级生产所需的许多主要和次要营养物质的来源，导致底栖生物和远洋生物地球化学循环之间的强烈耦合。在这项研究中，我们提供了配对的底栖生物通量和底水生物地球化学数据，这些数据收集于2017年至2019年期间大约每季度取样一次的两个俄勒冈州大陆架地点，以及位于俄勒冈州中部至华盛顿州南部的其他九个大陆架地点，并于2022年7月或9月取样。底栖生物通量是用一种新的装置来确定的，用于非原位核心孵育。当通量归一化到各自测量的沉积物DO通量时，比率与该地区过去使用原位底栖生物室确定的通量估计比率吻合得很好；然而，非原位通量通常较低。我们的研究结果表明，沉积物是DO和硝酸盐的净汇，也是磷酸盐、硅酸盐和铵的来源。对俄勒冈大陆架表层水沉积物再矿化磷酸盐和硅酸盐相对贡献的估计表明，在最近的夏季上升流季节，大陆架沉积物提供了至少5±7%和37±7%的可用磷酸盐和硅酸盐，在春季分别为2±9%和35±11%。C:N:P:O2的再矿化比率证实了夏季反硝化作用增加，冬季反硝化作用减弱，这是由于水柱含氧量较高，支持了先前的研究。多示踪水质量分析也显示夏季和秋季水柱硝酸盐亏缺增加。根据底栖生物通量估算的底栖生物反硝化速率在0.2至1.8 mmol N m-2 day-1之间，在上升流季节的过去评估范围内。采用一个简单的模型，在假定底栖边界层高度和停留时间的情况下，进一步限制了对底水固定氮(N)损失的贡献，结果表明，尽管沉积物反硝化可以很容易地解释夏季底水的总氮损失，但在一些站点，早期秋季赤字的强度表明了额外的水柱反硝化作用。限制水柱和底栖生物对固定氮赤字的贡献对于了解该地区氮限制初级生产力在预期的全球变暖下如何响应预测的海洋脱氧非常重要。这些结果证明了沉积物和水柱再矿化过程在整个OR-WA大陆架上的相互作用。与大多数浅海系统一样，这两者是生态系统动态和对环境变化的反应的组成部分。
{"title":"Spatiotemporal variability in benthic-pelagic coupling on the Oregon-Washington shelf","authors":"Anna Hughes , Clare E. Reimers, Kristen E. Fogaren, 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:O<sub>2</sub> 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<sup>-2</sup> day<sup>-1</sup> 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":"2024-11-26","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}
Pub Date : 2024-11-01DOI: 10.1016/j.marchem.2024.104467
J. Sánchez-Rodríguez , A. Sierra , S. Moreno , J. Forja , T. Ortega
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.
{"title":"Nitrous oxide variability along an estuary influenced by agricultural land use (Guadalquivir estuary, SW Spain)","authors":"J. Sánchez-Rodríguez , A. Sierra , S. Moreno , J. Forja , 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 (N<sub>2</sub>O) variability is analysed considering the influence of temperature, salinity, water-atmosphere fluxes, benthic fluxes, reactivity and lateral inputs. N<sub>2</sub>O increases along the salinity gradient, with values ranging from 5.9 to 103.3 nmol L<sup>−1</sup>. Thus, values of N<sub>2</sub>O 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 N<sub>2</sub>O in the estuary (74.26 ± 7.41 μmol m<sup>−2</sup> d<sup>−1</sup>). Sediments act as a source of N<sub>2</sub>O to the water column, with benthic fluxes presenting a wide range from 2 to 20 μmol m<sup>−2</sup> d<sup>−1</sup>. 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 N<sub>2</sub>O 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 N<sub>2</sub>O 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}
Pub Date : 2024-11-01DOI: 10.1016/j.marchem.2024.104472
Rodrigo Kerr , Thiago Monteiro , Iole Beatriz M. Orselli , Virginia Maria Tavano , Carlos Rafael B. Mendes
Hydrographic properties and carbon dioxide partial pressure (pCO2) were measured through underway survey of surface waters during spring 2014, mainly along the Surface Haline Front in the continental shelf-break domain in the southwestern South Atlantic Ocean margin. Additionally, discrete seawater surface samples were collected along the ship track to identify the phytoplankton community and measure seawater chemical properties. This study aims to identify the drivers of the marine CO2‑carbonate chemistry and the role played by the phytoplankton composition on changes in the surface marine carbonate properties and the sea-air CO2 exchanges in two biogeochemical provinces (i.e., South Brazil Bight – SBB, and Southern Brazilian Shelf – SBS) governed by the dynamics of the Brazil Current system in the South Atlantic Ocean. The water masses identified on the surface of the region were Tropical Water (mostly present at offshore regions), Subtropical Shelf Water (mostly present over the continental shelf and slope), and Plata Plume Water (present in the south coastal domain of the SBS). On average, the study area behaved as a weak net CO2 outgassing zone of 1.2 ± 2.3 mmol m−2 d−1 during the spring, despite some subregions behaving as CO2 ingassing zones. The CO2 uptake verified in the SBB was related with mesoscale activity bringing cold waters in the region while CO2 uptake in the continental shelf domain of SBS was associated with the presence of cooler and fresher Plata Plume Water. Changes in total alkalinity and dissolved inorganic carbon at surface were mainly governed by CaCO3 production in SBB and seawater dilution in SBS, although other processes may also have influenced on their spatial variability. The dominant phytoplankton groups were haptophytes (31 %), Trichodesmium (21 %), and picocyanobateria (28 %), corresponding to Synechococcus (17 %) and Prochlorococcus (11 %). The dominance of the diatom group was associated with a decrease in sea surface pCO2 (mainly at coastal zones at southern areas), although the sea-air CO2 exchanges were regulated by cooling process due the presence of Plata Plume Water in that region. Changes in surface pH were related to high concentration of Trichodesmium slicks at offshore zones with the highest microalgae concentration, leading to pH drops of up to 0.4. Trichodesmium slicks likely allowed the development of haptophytes in offshore oligotrophic waters due to its role on N2 fixation. An increase of ∼20 % in the dominance of haptophytes contribution was verified in that situation, which was likely in a post-bloom development stage, since an increased dissolved inorganic carbon content was observed, associated with a prevalence of net respiration processes.
{"title":"Sea-air CO2 exchanges, pCO2 drivers and phytoplankton communities in the southwestern South Atlantic Ocean during spring","authors":"Rodrigo Kerr , Thiago Monteiro , Iole Beatriz M. Orselli , Virginia Maria Tavano , Carlos Rafael B. Mendes","doi":"10.1016/j.marchem.2024.104472","DOIUrl":"10.1016/j.marchem.2024.104472","url":null,"abstract":"<div><div>Hydrographic properties and carbon dioxide partial pressure (<em>p</em>CO<sub>2</sub>) were measured through underway survey of surface waters during spring 2014, mainly along the Surface Haline Front in the continental shelf-break domain in the southwestern South Atlantic Ocean margin. Additionally, discrete seawater surface samples were collected along the ship track to identify the phytoplankton community and measure seawater chemical properties. This study aims to identify the drivers of the marine CO<sub>2</sub>‑carbonate chemistry and the role played by the phytoplankton composition on changes in the surface marine carbonate properties and the sea-air CO<sub>2</sub> exchanges in two biogeochemical provinces (i.e., South Brazil Bight – SBB, and Southern Brazilian Shelf – SBS) governed by the dynamics of the Brazil Current system in the South Atlantic Ocean. The water masses identified on the surface of the region were Tropical Water (mostly present at offshore regions), Subtropical Shelf Water (mostly present over the continental shelf and slope), and Plata Plume Water (present in the south coastal domain of the SBS). On average, the study area behaved as a weak net CO<sub>2</sub> outgassing zone of 1.2 ± 2.3 mmol m<sup>−2</sup> d<sup>−1</sup> during the spring, despite some subregions behaving as CO<sub>2</sub> ingassing zones. The CO<sub>2</sub> uptake verified in the SBB was related with mesoscale activity bringing cold waters in the region while CO<sub>2</sub> uptake in the continental shelf domain of SBS was associated with the presence of cooler and fresher Plata Plume Water. Changes in total alkalinity and dissolved inorganic carbon at surface were mainly governed by CaCO<sub>3</sub> production in SBB and seawater dilution in SBS, although other processes may also have influenced on their spatial variability. The dominant phytoplankton groups were haptophytes (31 %), <em>Trichodesmium</em> (21 %), and picocyanobateria (28 %), corresponding to <em>Synechococcus</em> (17 %) and <em>Prochlorococcus</em> (11 %). The dominance of the diatom group was associated with a decrease in sea surface <em>p</em>CO<sub>2</sub> (mainly at coastal zones at southern areas), although the sea-air CO<sub>2</sub> exchanges were regulated by cooling process due the presence of Plata Plume Water in that region. Changes in surface pH were related to high concentration of <em>Trichodesmium</em> slicks at offshore zones with the highest microalgae concentration, leading to pH drops of up to 0.4. <em>Trichodesmium</em> slicks likely allowed the development of haptophytes in offshore oligotrophic waters due to its role on N<sub>2</sub> fixation. An increase of ∼20 % in the dominance of haptophytes contribution was verified in that situation, which was likely in a post-bloom development stage, since an increased dissolved inorganic carbon content was observed, associated with a prevalence of net respiration processes.</div></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"267 ","pages":"Article 104472"},"PeriodicalIF":3.0,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142722482","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}
Pub Date : 2024-11-01DOI: 10.1016/j.marchem.2024.104469
Shou-En Tsao , Po-Yen Shen , Chun-Mao Tseng
The partial pressure of CO2 (pCO2) and associated CO2 air-sea flux exhibit highly heterogeneous temporal and spatial patterns in ocean margins. In this study, we analyzed a three-year time-series of data sampled during 2011–2014 along the Kuroshio Current within the East China Sea (ECS) to investigate the seasonal pattern of carbonate chemistry and CO2 air-sea fluxes. Annually, the Kuroshio within the ECS operates as a net CO2 sink at approximately 1.3 mol C m−2 yr−1, less than estimates over the ECS shelf (∼1.8 mol C m−2 yr−1). The thermal control of pCO2 makes the Kuroshio a strong CO2 sink in winter, with a transition to net-neutral, or a weak CO2 source in summer. On an interannual basis, however, the seasonal CO2 air-sea fluxes in the Kuroshio may undergo shifts if warming conditions continue.
大洋边缘的二氧化碳分压（pCO2）和相关的二氧化碳海气通量呈现出高度异质性的时空模式。在本研究中，我们分析了 2011-2014 年中国东海（ECS）黑潮沿岸三年的时间序列数据，研究了碳酸盐化学和二氧化碳海气通量的季节模式。每年，东海海域内黑潮的二氧化碳净吸收汇约为 1.3 mol C m-2 yr-1，低于东海大陆架的估计值（1.8 mol C m-2 yr-1）。对 pCO2 的热控制使黑潮在冬季成为一个强大的二氧化碳汇，在夏季过渡到净中性或弱二氧化碳源。不过，如果气候继续变暖，黑潮的季节性二氧化碳海气通量可能会发生变化。
{"title":"Seasonal variation of CO2 air-sea flux and effects of warming in the Kuroshio Current of the East China Sea","authors":"Shou-En Tsao , Po-Yen Shen , Chun-Mao Tseng","doi":"10.1016/j.marchem.2024.104469","DOIUrl":"10.1016/j.marchem.2024.104469","url":null,"abstract":"<div><div>The partial pressure of CO<sub>2</sub> (<em>p</em>CO<sub>2</sub>) and associated CO<sub>2</sub> air-sea flux exhibit highly heterogeneous temporal and spatial patterns in ocean margins. In this study, we analyzed a three-year time-series of data sampled during 2011–2014 along the Kuroshio Current within the East China Sea (ECS) to investigate the seasonal pattern of carbonate chemistry and CO<sub>2</sub> air-sea fluxes. Annually, the Kuroshio within the ECS operates as a net CO<sub>2</sub> sink at approximately 1.3 mol C m<sup>−2</sup> yr<sup>−1</sup>, less than estimates over the ECS shelf (∼1.8 mol C m<sup>−2</sup> yr<sup>−1</sup>). The thermal control of <em>p</em>CO<sub>2</sub> makes the Kuroshio a strong CO<sub>2</sub> sink in winter, with a transition to net-neutral, or a weak CO<sub>2</sub> source in summer. On an interannual basis, however, the seasonal CO<sub>2</sub> air-sea fluxes in the Kuroshio may undergo shifts if warming conditions continue.</div></div>","PeriodicalId":18219,"journal":{"name":"Marine Chemistry","volume":"267 ","pages":"Article 104469"},"PeriodicalIF":3.0,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142656458","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}
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