Chemical Geology最新文献

{"title":"Integrated physiological and metabolomic analysis reveals the cytochrome c oxidase gene ccoQ-mediated biotite dissolution by Pseudomonas pergaminensis F77","authors":"Qiyu Xiang ,&nbsp;Wen Dong ,&nbsp;Xinyi Zheng,&nbsp;Xiafang Sheng","doi":"10.1016/j.chemgeo.2025.123020","DOIUrl":"10.1016/j.chemgeo.2025.123020","url":null,"abstract":"<div><div>To date, the cytochrome <em>c</em> oxidase-synthesizing gene <em>ccoQ</em>-mediated mineral solubilization by bacteria was poorly characterized. Here, the impact of mineral-dissolving <em>Pseudomonas pergaminensis</em> F77 on iron (Fe) and aluminium (Al) release from biotite was evaluated and the relative expression of <em>ccoQ</em> in F77 was analyzed by real-time reverse transcription-quantitative PCR (RT–qPCR) during mineral dissolution process. Then, F77 and the F77∆<em>ccoQ</em> mutant constructed from F77 using homologous recombination were compared for <em>ccoQ</em>-mediated Fe and Al release from biotite and the underlying molecular mechanisms. The F77∆<em>ccoQ</em> decreased the Fe and Al concentrations in the medium by 11 %–49 % between 8 h and 12 h compared to F77. The F77∆<em>ccoQ</em> mutant significantly reduced the Fe²⁺ concentrations by 67 %–80 % between 6 h and 8 h and Fe³⁺ concentrations by 19 %–50 % between 10 h and 12 h compared with F77. Furthermore, significantly enhanced pH values and no significant change in the cell numbers were found in the presence of F77∆<em>ccoQ</em> compared to those in the presence of F77 between 4 h and 12 h. Comparative metabolomic analysis demonstrated downregulated extracellular metabolites (biotin, D-Altro-D-Manno-Heptose, and a variety of acidic metabolites involved in carbohydrate and amino acid metabolisms, cofactor and vitamin synthesis, and glycan biosynthesis) associated with biotite dissolution in the F77∆<em>ccoQ</em>. Furthermore, the expression levels of the metabolite-synthesizing related genes were downregulated in the F77∆<em>ccoQ</em> compared with those in F77. Our findings suggested that <em>ccoQ</em> in F77 facilitated mineral dissolution by upregulating the production of extracellular metabolites associated with mineral dissolution by F77.</div></div>","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":"694 ","pages":"Article 123020"},"PeriodicalIF":3.6,"publicationDate":"2025-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144903417","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Using UPb dating of Cenozoic seep carbonates to assess periods of hydrocarbon seepage in sedimentary basins","authors":"Stefano Giunti ,&nbsp;Catherine Mottram ,&nbsp;Marcello Natalicchio ,&nbsp;Luca Martire ,&nbsp;Glenn Chapman ,&nbsp;Francesco Dela Pierre ,&nbsp;Maciej J. Bojanowski","doi":"10.1016/j.chemgeo.2025.123016","DOIUrl":"10.1016/j.chemgeo.2025.123016","url":null,"abstract":"<div><div>Constraining the age of authigenic carbonate precipitation is crucial to track the timing of hydrocarbon migration in (paleo-) seep systems. The age of ancient seep carbonates is usually indirectly inferred using biostratigraphic proxies obtained from the surrounding sediments or from fossils preserved within the carbonates. <em>In-situ</em> carbonate U<img>Pb geochronology is an established method for tracing the timing of low temperature fluid flow processes. This method has the potential to provide important absolute ages for seepage events. Here, a combined approach using carbonate U<img>Pb geochronology and stable isotope analyses has been applied to seep carbonates from the Tertiary Piedmont Basin (NW Italy) to constrain the age of authigenic carbonate precipitation from different localities across the basin. The specimens record negative δ¹³C values (&gt; −44.3 ‰ Vienna PeeDee Belemnite) indicating anaerobic oxidation of methane as the main source of inorganic carbon. ²⁰⁶Pb/²³⁸U lower intercept ages range from 16.6 ± 5.1 to 3.8 ± 1.0 Ma, marking two distinct periods of seepage activity. Significant age differences between hydrocarbon-derived cements from the seep carbonates of the Tertiary Piedmont Basin and their surrounding sediments (ca. 12 Ma) demonstrate that the commonly used biostratigraphic approach can lead to incorrect conclusions regarding the timing of hydrocarbon migration and consequent carbonate precipitation. Such age discrepancies have important consequences when studying past mass extinction events or hyperthermal periods potentially linked with gas hydrate destabilization.</div></div>","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":"695 ","pages":"Article 123016"},"PeriodicalIF":3.6,"publicationDate":"2025-08-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144920677","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Volatility of mercury and related volatile metals at magmatic temperatures","authors":"Julien Boulliung ,&nbsp;Bernard J. Wood ,&nbsp;Tamsin A. Mather","doi":"10.1016/j.chemgeo.2025.123018","DOIUrl":"10.1016/j.chemgeo.2025.123018","url":null,"abstract":"<div><div>The volatilities of metals in igneous systems are important constraints in the contexts of magmatic degassing, ore deposition and the volatile budgets of the Earth and other planets. In order to develop a systematic understanding of such volatilities, we have made the first experimental measurements of the volatility of Hg from molten basalt at high temperatures and compared it directly with other volatile trace elements (i.e., Ag, As, Cd, Cr, Cs, Cu, Ga, Ge, In, Li, Pb, Rb, Sb, Sn, Tl and Zn). We placed 100 mg of crushed basalt, containing 93 ppm of Hg and ∼ 500 ppm of most of the other volatile metals in an alumina crucible which was sealed under vacuum inside a silica glass tube of volume ∼ 4.4 × 10⁻⁶ m³. After holding them at high temperature (1250, 1300 or 1400 °C) between 5 min and 24 h, samples were quenched in air. Analysis of the quenched glasses using a Direct Mercury Analyser shows that almost all Hg (&gt;99 %) is lost within the first few minutes, establishing a total pressure of Hg species of 150 Pa (calculated from the known mass of Hg in the system and the ampoule volume). Apparent steady-state concentrations of ∼40 ppb Hg at 1400 °C and ∼ 100 ppb Hg at 1300 °C are achieved after 1 and 6 h respectively. The oxidation state of Fe in the products, measured by XANES, indicates that Fe³⁺/(Fe³⁺+Fe²⁺) remains constant at ∼0.1 during the experiments. The behavior of elements other than Hg in the glasses were determined by Electron Microprobe and Laser Ablation ICP-MS. In our experiments we find that the fraction of each element lost to the atmosphere decreases in the following order: Hg&gt;&gt;Tl&gt;Cd&gt;In&gt;Zn*&gt;Li&gt;Cs&gt;Cu*&gt;As&gt;Ag&gt;Pb∼Sn∼Ga&gt;Ge∼Sb (with the position of asterisked elements uncertain and maximum possible volatilities adopted). These results show broad similarities to, but also important differences from volatilities estimated from field measurements of gas/aerosol compared to concentrations in lava. They also show important differences from volatilities obtained from open-system experiments and those estimated from the condensation temperatures of elements in the relatively reduced environment of a protoplanetary gas disc.</div></div>","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":"695 ","pages":"Article 123018"},"PeriodicalIF":3.6,"publicationDate":"2025-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144920678","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cadmium isotopic evidence for a collapse of primary productivity during the Hirnantian glaciation and mass extinction","authors":"Yaowen Wu ,&nbsp;Hui Tian ,&nbsp;Jie Li ,&nbsp;Jianfang Hu ,&nbsp;Yuejun Wang ,&nbsp;Chengshi Gan ,&nbsp;Haifeng Fan","doi":"10.1016/j.chemgeo.2025.123017","DOIUrl":"10.1016/j.chemgeo.2025.123017","url":null,"abstract":"<div><div>The Late Ordovician witnessed mass extinctions (LOME) and carbon cycle dynamics, such as Hirnantian glaciation and positive carbon isotope excursion (HICE). Model results suggested that both climatic cooling and HICE were driven by high primary productivity and increased organic carbon burial, which, however, is inconsistent with the decline in organic carbon burial revealed by sedimentary organic carbon data. The evolution of marine primary productivity is critical to reconcile these contradictions but is poorly understood. Cd isotope is widely used as a paleo-nutrient proxy for past nutrient utilization and primary productivity. Here, we present new Cd isotopic records paired with organic carbon isotope and major and trace elements covering the late Katian, Hirnantian, and early Rhuddanian stages (ca. 447-442 Ma). The seawater δ^114/110Cd values of 0.25 ‰ ± 0.13 ‰ during the late Katian and of 0.48 ‰ ± 0.16 ‰ during the early Rhuddanian, comparable to those of modern deep ocean (+ 0.25 ‰ to +0.45 ‰), may reflect near-modern nutrient utilization and productivity levels. In contrast, lower seawater δ^114/110Cd of 0.08 ‰ ± 0.07 ‰ during the Hirnantian glaciation may indicate a low primary productivity. Our new finding of low organic production and burial is consistent with geological records of low organic carbon burial rate and further supports that the Hirnantian glaciation and HICE may not be driven by increased organic carbon burial but require other factors. Low primary productivity may be caused by a collapse of primary producers, which may exert food and energy stress on marine ecosystems and likely contribute to LOME. Our work provides new insights into carbon cycle dynamics and LOME from the perspective of primary producers.</div></div>","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":"694 ","pages":"Article 123017"},"PeriodicalIF":3.6,"publicationDate":"2025-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144894887","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Role of permeability evolution induced by CO2 injection on CO2 storage and CH4 production in a low permeability reservoir","authors":"Danqing Liu ,&nbsp;Zexing Zhang ,&nbsp;Sen Yang ,&nbsp;Qi Yu ,&nbsp;Ramesh K. Agarwal ,&nbsp;Yilian Li","doi":"10.1016/j.chemgeo.2025.123014","DOIUrl":"10.1016/j.chemgeo.2025.123014","url":null,"abstract":"<div><div>CO₂-injection induced geochemical reactions exert important influence on CO₂ enhanced shale gas recovery by altering the shale porosity and permeability. This impact, however, has been seldomly quantified. To identify and quantify the role of CO₂-water-rock reactions in the evolution of shale permeability and its influence on CH₄ production and CO₂ sequestration, a multi-components reactive transport model for low permeability media (10⁻²² - 10⁻¹⁸ m²) is established by coupling the geochemical and geomechanical effects of CO₂ injection on rock porosity and permeability. The effect of CO₂ dissolution and induced geochemical reactions on CH₄ production and CO₂ storage is then explored with experiments and numerical simulations. A sensitivity analysis is conducted to identify the uncertainties induced by the inherent shale and engineering factors. Results show that a very limited variation in porosity and permeability (&lt;1 %) induced by the CO₂-water-rock reactions could cause significant perturbation in CH₄ production and CO₂ sequestration in shale by controlling the pressure perturbation in the reservoir and the CO₂ migration. These impacts dynamically change with the extent and degree of geochemical reactions (e.g. mineral dissolution/precipitation), with up to 17 % for CH₄ production and 24 % for CO₂ storage at the conditions considered in this study. High pressure-temperature (10–15 MPa, 40–80 °C), low matrix permeability (0.001–0.1 mD) and injection rate (0.05–0.2 kg/s) strengthen the influence by aggravating the degree of CO₂-water-shale reaction. While high injection rate and matrix permeability can enhance the impact by promoting CO₂ migration, they can also increase the leakage risk of CO₂. This study provides the development of a practical methodology for the CO₂ reactive transport modeling as well as the theoretical support for development of unconventional resources and CO₂ storage in low permeable reservoirs.</div></div>","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":"694 ","pages":"Article 123014"},"PeriodicalIF":3.6,"publicationDate":"2025-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144900808","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Direct U–Pb dating of vitrinite in coal","authors":"Beilei Sun ,&nbsp;Yuexing Feng ,&nbsp;Sandra Rodrigues ,&nbsp;Charlotte M. Allen ,&nbsp;Joan S. Esterle","doi":"10.1016/j.chemgeo.2025.123015","DOIUrl":"10.1016/j.chemgeo.2025.123015","url":null,"abstract":"<div><div>Uranium is often associated with organic matter forming U-organic matter complexes. Coal, as an organic rich material, is no exception but can it be dated using the uranium‑lead (U–Pb) method? We present U–Pb isotopic data, and trace elements concentrations directly measured on particles of the coal maceral vitrinite. Coal samples at three locations kilometers apart from the same Late Carboniferous bituminous coal seam in the Ningwu Coalfield, China were analyzed by Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS). The vitrinite reflectance of the three samples ranges from 0.69 % to 0.80 %, indicating that the coals experienced maximum paleotemperatures between 106 and 117 °C. The three samples each yielded similar lower intercept ages, and their combined dataset produced a consistent age of 116.5 ± 0.6 Ma (Lower Cretaceous), which is significantly younger than their depositional age (Late Carboniferous). Given that the U–Pb systematics in organic matter are not yet fully understood, particularly whether they behave similarly to or differently from those in minerals, we interpret the obtained age as representing the timing of coalification. The consistent age and coal rank that we obtained correspond to interpretations from previous studies about the timing of maximum paleotemperature and burial depth in the basin and the tectonic evolution of the North China Craton. We postulate that at 116 Ma, the uranium and lead associated with the organic matter became immobile when coalification was achieved, effectively locking the U–Pb system. These findings establish direct U–Pb dating of organic matter as a powerful and novel method for precisely constraining the timing of maximum thermal maturation and the absolute age of coalification in sedimentary basins.</div></div>","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":"694 ","pages":"Article 123015"},"PeriodicalIF":3.6,"publicationDate":"2025-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144901903","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Automated rare earth element data assessment in GeoArmadillo and application to the GEOROC and PetDB databases","authors":"David M. Ernst Styn ,&nbsp;Kerstin A. Lehnert ,&nbsp;Gerhard Wörner ,&nbsp;Marie K. Traun ,&nbsp;Malte Mues","doi":"10.1016/j.chemgeo.2025.123013","DOIUrl":"10.1016/j.chemgeo.2025.123013","url":null,"abstract":"<div><div>The amount of published geochemical data is continuously increasing due to the availability of advanced and highly efficient analytical tools. These data are made accessible through curated, domain-specific and interconnected synthesis databases. Such large data compilations bear great potential for leading-edge research in geochemistry and the application of compositional data of geoscientific samples in neighbouring fields. However, using data compiled from literature over many years also introduces pitfalls and uncertainties for data analysis. While the authors of the original data usually know their significance and limitations, “external” data users often find it challenging to assess the reliability of data, inherent uncertainties and, possibly, analytical artefacts. The group of rare earth elements (REEs) is widely used in geochemical research as tracers of chemical transport and differentiation, as well as geochemical fingerprinting. Therefore, we developed a data assessment method that can automatically screen geochemical data for suspicious REE patterns and anomalies. Our REE data assessment is based on REEs' geochemical behaviour in natural processes. Specifically, we address the “smoothness” of normalised REE patterns, identify unexpected outliers in REE plots, and various types of scatter.</div><div>We extensively tested our REE data assessment method on large datasets extracted from the GEOROC and PetDB geochemical databases. We identified distinct types of anomalous REE patterns that we relate to potential artefacts and data quality issues.</div></div>","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":"694 ","pages":"Article 123013"},"PeriodicalIF":3.6,"publicationDate":"2025-08-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144892216","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Isotopic resetting of CO2 in the presence of carbonate samples: Implications for oxygen- and clumped-isotope analyses","authors":"Philip Staudigel ,&nbsp;Miguel Bernecker ,&nbsp;Allison Curley ,&nbsp;Niels Meijer ,&nbsp;Lkhamsuren Bayarjargal ,&nbsp;Martin Dietzel ,&nbsp;Jens Fiebig","doi":"10.1016/j.chemgeo.2025.123012","DOIUrl":"10.1016/j.chemgeo.2025.123012","url":null,"abstract":"<div><div>Exchange between CO₂ and water-containing phases is a consistent problem during oxygen and clumped isotope analysis of carbonate-derived CO₂. Here, we have identified numerous natural and synthetic carbonates and carbonate-bearing materials that consistently reset the δ¹⁸O, ∆₄₇ and ∆₄₈ values of analyte CO₂ during acidification in a common acid bath and, thereby, contribute to preparation noise. From a mass-balance perspective, this resembles the isotopic exchange between CO₂ and a small water contaminant: indicating that certain samples cannot be effectively dried, even after several months in a vacuum drier. This effect can be replicated in off-line experiments, allowing for problematic samples to be unambiguously identified without endangering day-to-day lab operations. We further describe laboratory best-practices wherein the risk of this effect is effectively minimized, allowing for rapid identification of problematic samples: for example, the use of carbonate standards with extremely low ∆₄₇ values (e.g. ETH-1 and ETH-2) before an analytical sequence allows such issues to be rapidly identified. This highlights the importance of analyzing both carbonate and equilibrated CO₂ standard materials, as these effects could not otherwise be easily identified and eliminated. We present this report in expectation that it will assist other laboratories to improve data quality, as well as to start a conversation about the potential necessity for additional carbonate standards with “exotic” bulk and clumped isotope compositions.</div></div>","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":"694 ","pages":"Article 123012"},"PeriodicalIF":3.6,"publicationDate":"2025-08-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144865837","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Garnet dissolution–reprecipitation processes in leucogranitic magma and their profound geochemical consequences","authors":"Rui Wang, Li-E Gao, Lingsen Zeng, Lilong Yan, Linghao Zhao, Guyue Hu, Li Wang, Haitao Wang","doi":"10.1016/j.chemgeo.2025.123008","DOIUrl":"https://doi.org/10.1016/j.chemgeo.2025.123008","url":null,"abstract":"Syn-magmatic garnet-bearing and garnet-free leucogranites from the Tethyan Himalaya display pronounced differences in major element, trace element, and Sr<ce:glyph name=\"sbnd\"></ce:glyph>Nd isotope geochemistry, reflecting a complex magmatic evolution process. Compared with biotite-bearing leucogranites, the garnet-bearing leucogranites have (1) relatively higher SiO<ce:inf loc=\"post\">2</ce:inf>, FeO*, and MnO contents; lower Al<ce:inf loc=\"post\">2</ce:inf>O<ce:inf loc=\"post\">3</ce:inf>, CaO, P<ce:inf loc=\"post\">2</ce:inf>O<ce:inf loc=\"post\">5</ce:inf>, and TiO<ce:inf loc=\"post\">2</ce:inf> contents; and lower A/CNK values; (2) higher Y, Yb, Zr, Hf, and Th contents and lower Ba and Sr contents; (3) notably higher heavy rare earth element contents and more pronounced negative Eu anomalies; and (4) significantly higher <ce:sup loc=\"post\">87</ce:sup>Sr/<ce:sup loc=\"post\">86</ce:sup>Sr(t) ratios and ε<ce:inf loc=\"post\">Nd</ce:inf>(t) ratios. Furthermore, the garnets in the garnet-bearing leucogranites exhibit characteristics typical of magmatic origins. On the basis of field observations and geochemical data, we propose the following model: during migration and intrusion, high-temperature granitic magma that ultimately formed the biotite-bearing leucogranites, incorporated wall rocks, thereby releasing both material and ancient garnet crystals from the wall rocks into the magma. The assimilation of the wall rocks elevated the FeO*, MnO, and HREE contents and Sr<ce:glyph name=\"sbnd\"></ce:glyph>Nd isotopic compositions and ultimately promoted the crystallization of magmatic garnets and the formation of garnet-bearing leucogranites in the Kongbugang area. These observations provide new constraints on the mechanism responsible for the development of geochemical heterogeneities in granites and the mechanism responsible for the formation of magmatic garnets in S-type granites and highly fractionated I-type granites.","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":"28 1","pages":"123008"},"PeriodicalIF":3.9,"publicationDate":"2025-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144901767","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"How estuaries modulate the riverine fluxes of copper (Cu) and cadmium (Cd) to seawater","authors":"Pratyusha Chanda ,&nbsp;Sambuddha Misra ,&nbsp;Tarun K. Dalai ,&nbsp;Madeleine S. Bohlin ,&nbsp;Emily I. Stevenson ,&nbsp;Helen M. Williams","doi":"10.1016/j.chemgeo.2025.123011","DOIUrl":"10.1016/j.chemgeo.2025.123011","url":null,"abstract":"<div><div>The export of dissolved copper (Cu) and cadmium (Cd) to coastal ocean is important for sustaining marine biological productivity. Riverine input is the dominant source of Cu and Cd to seawater, which supplies about 830–1040 million moles/yr and 10–30 million moles/yr respectively. We demonstrate that estuarine processes may augment the riverine export fluxes by a maximum 20 % for Cu and 271 % for Cd. To understand the underlying mechanism of estuarine cycling of Cu and Cd, we studied the Ganga (Hooghly) River estuary, a monsoon-dominated tropical river characterized by a high sediment-to-water ratio, serving as a natural laboratory to investigate large-scale global estuarine processes. The remobilization of metals from exchangeable (Cd) and/or amorphous oxide (Cu) phases of the riverine suspended sediments are identified to be the primary processes contributing to their estuarine production. In addition, during the lean flow season, Cu input from shallow porewater discharge modulates dissolved Cu concentration in the high salinity zone. Steady state mass balance models reveal that the variation in dissolved Cu and Cd concentrations in the estuary is a function of dissolved inorganic complexation, which in turn is modulated by changes in pH, bicarbonate-ion concentrations and salinity (chlorinity). The key finding is that the dissolved Cu and Cd in the mid to high salinity range (4–13 ‰) exhibit a concentration “excess” relative to conservative river water-seawater mixing which is corroborated by a proportionate decrease in reactive solid phase concentration of the metals. The “excess” concentrations result in ∼46 % and ∼ 306 % rise in Cu and Cd export, relative to the riverine supply, to the Bay of Bengal. Overall, this study underscores the importance of estuarine processes in modulating net riverine metal fluxes to seawater.</div></div>","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":"694 ","pages":"Article 123011"},"PeriodicalIF":3.6,"publicationDate":"2025-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144865836","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}