Chemical Geology最新文献

{"title":"A model explaining the anomalous enrichment of Pt in phosphatized crusts: The influence of phosphates and organic acids","authors":"Zhengkun Li ,&nbsp;Xiaoming Sun ,&nbsp;Dengfeng Li ,&nbsp;Yongjia Liang","doi":"10.1016/j.chemgeo.2025.122673","DOIUrl":"10.1016/j.chemgeo.2025.122673","url":null,"abstract":"<div><div>Numerous studies have reported a remarkable enrichment of platinum (Pt) in phosphatized ferromanganese crusts, with concentrations several times higher than in non-phosphatized crusts. Understanding the mechanism behind this extraordinary Pt enrichment requires investigating the influence of anoxic water layers, which are rich in various ions, on the accumulation and preservation of Pt in ferromanganese minerals during phosphorization events. This study combines adsorption/desorption experiments, Fourier transform infrared (FTIR) spectrum analysis, transmission electron microscope (TEM) observations, and X-ray absorption fine structure (XAFS) analysis using feroxyhyte (δ-FeOOH) and vernadite (δ-MnO2) as representative ferromanganese minerals in Fe<img>Mn crusts to examine the fixation and reactivation of Pt during phosphorization events. Our research findings reveal that changes in the ionic composition of water layers during phosphorization events have a significant impact on the adsorption and preservation of Pt by ferromanganese minerals. Fe²⁺, Mn²⁺, and phosphate ions were found to strongly inhibit the adsorption of Pt by feroxyhyte. On the other hand, citric acid enhances Pt adsorption by creating additional adsorption sites at the edges of vernadite through dissolution. Regarding Pt preservation, phosphate ions can lead to a substantial release of Pt adsorbed in feroxyhyte, while only a small amount of Pt in vernadite can be released by phosphate. FTIR analysis indicates that phosphate can reactivate Pt in feroxyhyte by competing for surface hydroxyl groups. XAFS analysis further reveals that phosphate ions weaken the bonding between Pt and vernadite, although not to an extent that causes significant Pt release.</div></div>","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":"678 ","pages":"Article 122673"},"PeriodicalIF":3.6,"publicationDate":"2025-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143369702","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":"Clay Li isotopes reveal contrasting responses of chemical weathering intensity to hydroclimate changes in South Asia","authors":"Jingrui Li ,&nbsp;Xuefa Shi ,&nbsp;Shengfa Liu ,&nbsp;Hui Zhang ,&nbsp;Zhaowei Jing ,&nbsp;Xiaoming Miao ,&nbsp;Kaikai Wu ,&nbsp;Rui Jiang ,&nbsp;Somkiat Khokiattiwong ,&nbsp;Narumol Kornkanitnan","doi":"10.1016/j.chemgeo.2025.122652","DOIUrl":"10.1016/j.chemgeo.2025.122652","url":null,"abstract":"<div><div>Weathering processes in orogenic belts play a pivotal role in Earth's climate regulation. However, the link between silicate weathering and hydroclimatic fluctuations remains elusive. Here, we investigate the lithium‑neodymium isotopic compositions (δ⁷Li, εNd) and clay mineralogy of sediments in the northeastern Bay of Bengal to determine if the δ⁷Li can be used as a reliable tracer of the chemical weathering intensity and to assess how weathering responses to hydroclimate changes. δ⁷Li and εNd values range from −2.4 ‰ to 0.4 ‰ and − 12.5 to −8.9, respectively, with clay mineralogy dominated by illite (57 % on average). A decline in δ⁷Li since 13.5 ka, averaging −1.3 ‰, compared to −0.7 ‰ between 25 ka and 13.5 ka, indicates intensified weathering aligned with monsoon variations. Prominent millennial-scale δ⁷Li fluctuations (2.8 ‰ in maximum) during the last deglaciation, showing lower values during the cold events (Younger Drys and Heinrich stadial 1), imply a different mechanism of weathering response to hydroclimate changes. Shift of high mountain- versus floodplain-dominated weathering regimes and hydrology induced changes in water-rock interaction time or water residence time, are suggested to be responsible for δ⁷Li changes at glacial-interglacial scale and millennial scale, respectively. Our study provides key evidence for weathering response to short-term climate change, and highlights the carbon sink role of silicate weathering in floodplains at short-term scales and the potential of Li isotopes in reconstructing past hydroclimate changes.</div></div>","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":"678 ","pages":"Article 122652"},"PeriodicalIF":3.6,"publicationDate":"2025-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143207238","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 oxygen (δ18O, δ17O) and hydrogen (δ2H) isotopes in the Northern Limb of the Bushveld Igneous Complex to assess the extent of footwall contamination","authors":"Sharlotte C. Mkhonto ,&nbsp;Matthew I. Leybourne ,&nbsp;Derek Knaack ,&nbsp;Pedro J. Jugo ,&nbsp;Daniel Layton-Matthews ,&nbsp;Danie F. Grobler","doi":"10.1016/j.chemgeo.2025.122665","DOIUrl":"10.1016/j.chemgeo.2025.122665","url":null,"abstract":"<div><div>The Platreef in the Northern Limb is in the same stratigraphic position as the Critical Zone (i.e. Merensky Reef) in the Eastern and Western limbs of the Bushveld Igneous Complex (BIC). However, in some areas, the Platreef is in direct contact with Archean granitic gneisses and Transvaal Supergroup metasedimentary rocks. Although there is significant evidence of assimilation of Transvaal Supergroup metasedimentary rocks in the southern parts of the Platreef, there is no consensus on the extent of contamination and if contamination is proximal or distal to the Pt, Pd, Au mineralized zone/Merensky Reef equivalent. For this study, we report δ’¹⁸O, Δ’¹⁷O, and δ²H values of samples from the downdip portion of the Flatreef (part of the Platreef) on Turfspruit. The results show that δ’¹⁸O values range from ∼4 to 7 ‰ in intervals with little to no evidence of assimilation and can reach up to 17 ‰ in intervals with evidence of pervasive assimilation. The δ’¹⁸O values in areas with no evidence of assimilation are similar to previously reported values in the Eastern and Western limbs of the BIC. The Δ’¹⁷O values range from −0.200 to 0.050 ‰ throughout the stratigraphy. Most of the positive Δ’¹⁷O values are associated with intervals showing evidence of assimilation. The δ²H values (which range from −92 to −30 ‰) show no correlation between intervals with pervasive assimilation and those with little to no contamination. Samples from the Turfspruit area of the Northern Limb have δ’¹⁸O values of -5.53 to 17.14 ‰ which shows the extent of footwall assimilation of the Transvaal metasedimentary rocks. The triple oxygen isotope values show that the Northern Limb of the BIC records two separate episodes of crustal contamination: (1) a proximal contamination by local footwall lithologies; and (2) a deeper, more pervasive (with respect to the entire BIC) contamination, prior to injection of the BIC magmas into the middle/upper crust.</div></div>","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":"678 ","pages":"Article 122665"},"PeriodicalIF":3.6,"publicationDate":"2025-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143377007","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Fluorapatite fingerprints on magmatic-hydrothermal fluid evolution of the Lianyunshan Nb-Ta-Sn deposit, NE Hunan (South China)","authors":"Nuerkanati Madayipu ,&nbsp;Huan Li ,&nbsp;Thomas J. Algeo ,&nbsp;Safiyanu Muhammad Elatikpo ,&nbsp;Han Zheng ,&nbsp;Biao Liu ,&nbsp;Da-Peng Zhu ,&nbsp;Nuo Li ,&nbsp;Victor Ikechukwu Vincent","doi":"10.1016/j.chemgeo.2025.122669","DOIUrl":"10.1016/j.chemgeo.2025.122669","url":null,"abstract":"<div><div>The textures and compositions of apatite grains have been reported for many types of economic and non-economic deposits, but apatites in hydrothermal Nb<img>Ta (rare-metal) deposits have received scant attention to date. Apatite is common in magmatic–pegmatites and metasedimentary cover rocks of the Lianyunshan Complex (LYSC) of northeastern Hunan Province in South China, potentially providing insights into Nb<img>Ta metallogenic systems. Here, we present integrated textural, major- and trace-elemental, and in situ U-Pb-Sr isotopic data for hydrothermal apatite grains from the metasedimentary (schist)–magmatic (muscovite monzogranite)–pegmatite systems of the LYSC, to investigate its crystallization and mineralization processes in detail. Four types of fluorapatite (S-ap1 and S-ap2 in schist, G-ap in muscovite monzogranite, and P-ap in pegmatite) are recognized. The first three types crystallized in a magmatic-hydrothermal (transitional-stage) setting at ∼132–129 Ma, whereas the P-ap crystallized during a late-stage hydrothermal Nb<img>Ta mineralization event at ∼123 Ma. All four types show similar and low Cl content (&lt; 0.01 wt%) and high F content (2.70–4.49 wt%), suggesting their precipitation from a melt derived through partial melting of crustal material rich in F-bearing minerals. Relatively homogeneous (⁸⁷Sr/⁸⁶Sr)_i ratios are shown by the S-ap1 and S-ap2 grains (0.75067 ± 0.00010), contrasting with higher and variable values in the G-ap (0.75242 to 0.75943, mean 0.75610) and P-ap grains (0.75350–0.75776, mean 0.75533). The Sr isotope signatures of the LYSC appear to be inherited from Lengjiaxi Group metasedimentary strata. Our study highlights application of integrated petrographic-geochemical analyses of fluorapatites to trace the nature of ore-forming fluids in hydrothermal Nb<img>Ta (rare-metal) deposits of metasedimentary–magmatic–pegmatite systems.</div></div>","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":"678 ","pages":"Article 122669"},"PeriodicalIF":3.6,"publicationDate":"2025-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143378317","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":"Magmatic tempo within the Paleoproterozoic ophiolitic mélange, Northern Kongling Complex, Yangtze Craton: Dynamics of a Paleoproterozoic subduction zone","authors":"Hao Deng ,&nbsp;Chao Chen ,&nbsp;Di Wang ,&nbsp;Songbai Peng ,&nbsp;Wensong Lang ,&nbsp;He Zhang ,&nbsp;Ziyu Dong","doi":"10.1016/j.chemgeo.2025.122666","DOIUrl":"10.1016/j.chemgeo.2025.122666","url":null,"abstract":"<div><div>Paleoproterozoic ophiolitic mélanges, which are rare worldwide, provide significant insights into the structures of ancient orogens and the onset of modern plate tectonics. Here, we report a spatially and temporally linked arc magmatic association comprising circa 2.1–2.0 Ga EMORB-affinity gabbros and diabases, arc-affinity basalts, hornblendites, high-Mg andesites, and granites from the Paleoproterozoic Shuiyuesi ophiolitic mélange in the Northern Kongling Complex, Yangtze Craton. Structural analyses reveal that the mélange is characterized by a series of imbricated NEE-trending reverse faults and late-stage NNW-trending normal faults. Zircon U<img>Pb dating indicates that mafic rocks within the mélange belt primarily formed at ca. 2.1 Ga and metamorphosed at ca. 2.0 Ga, while granites mainly formed at ca. 2.0 Ga. The gabbros and diabases are characterized by enriched LREE patterns without negative Nb and Zr anomalies, displaying an EMORB-like geochemical affinity. In contrast, the arc-affinity basalts exhibit slightly enriched LREE patterns with negative Nb and Zr anomalies. The hornblendites and high-Mg andesites have higher MgO, Ni and Cr contents and display more fractionated REE patterns and larger negative Nb and Zr anomalies compared to the arc-affinity basalts. We propose that tholeiitic EMORB-affinity gabbros and diabases, arc-affinity basalts and calc-alkaline high‑magnesium andesites record a geological transition from subduction initiation to mature island arc magmatism. Granites are characterized by highly fractionated REE patterns, negative zircon εHf(t) values (−6.3 to −19.3) with Archean Hf isotope T_DM1 ages. We suggest that they formed through the partial melting of thickened Archean crusts during a <em>syn</em>-collision stage. Together with the existing studies, the Shuiyuesi mélange preserves an intact record of subduction-related and syn-collision magmatism and high-pressure metamorphism, indicating that modern-style plate tectonics characterized by cold and deep subduction has been operated since at least 2.1–2.0 Ga during Paleoproterozoic.</div></div>","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":"678 ","pages":"Article 122666"},"PeriodicalIF":3.6,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143207233","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":"Corrigendum to “Chemical variability in volcanic gas plumes and fumaroles along the East African Rift System: New insights from the Western Branch” [Chemical Geology 596 (2022) 120811]","authors":"G. Boudoire ,&nbsp;G. Giuffrida ,&nbsp;M. Liuzzo ,&nbsp;N. Bobrowski ,&nbsp;S. Calabrese ,&nbsp;J. Kuhn ,&nbsp;J.-C. Kazadi Mwepu ,&nbsp;F. Grassa ,&nbsp;S. Caliro ,&nbsp;A.L. Rizzo ,&nbsp;F. Italiano ,&nbsp;M. Yalire ,&nbsp;K. Karume ,&nbsp;A. Muhindo Syavulisembo ,&nbsp;D. Tedesco","doi":"10.1016/j.chemgeo.2025.122643","DOIUrl":"10.1016/j.chemgeo.2025.122643","url":null,"abstract":"","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":"678 ","pages":"Article 122643"},"PeriodicalIF":3.6,"publicationDate":"2025-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143102402","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":"Calibrating elemental salinity proxies in Holocene sedimentary environments","authors":"Mariano Remírez ,&nbsp;Geoffrey J. Gilleaudeau ,&nbsp;Randolph McBride ,&nbsp;Chelsea Pederson ,&nbsp;Carrie M. Miller ,&nbsp;Davin J. Wallace ,&nbsp;Lucía Guerra ,&nbsp;Eduardo Piovano ,&nbsp;Joonas J. Virtasalo ,&nbsp;Erin Culver-Miller ,&nbsp;Isaac Bondzie-Selby ,&nbsp;Chaowen Wang ,&nbsp;Thomas J. Algeo","doi":"10.1016/j.chemgeo.2025.122664","DOIUrl":"10.1016/j.chemgeo.2025.122664","url":null,"abstract":"<div><div>Most information regarding salinity in deep-time paleoenvironments is derived from fossil assemblages and paleogeographic configurations, although salinity interpretations based on fossils can be problematic due to, for instance, the unknown salinity tolerances of extinct clades. Although recently developed elemental salinity proxies (i.e., B/Ga, Sr/Ba, and S/TOC) for shales and mudstones have indicated that some ancient seas may have been less saline than previously assumed, the calibrations of these proxies in modern environments and the limits of their application to deep-time systems require further testing. In this contribution, we compare watermass salinity with elemental salinity proxies in modern and Holocene sedimentary environments representing a wide range of salinity conditions―from freshwater to marine―in North America (Lake Superior, Chesapeake Bay, and Gulf of Mexico), northern Europe (Baltic Sea), and Argentina (Laguna Mar Chiquita). Our results show agreement between observed watermass salinity and interpretations based on sedimentary salinity proxies with a single exception: two marine sites on the inner continental shelf of the Gulf of Mexico yielded B/Ga ratios indicative of freshwater to brackish conditions. The anomalously low boron concentrations at these sites may be related to upward diffusion of freshwater from underlying coastal plain facies deposited during the Last Glacial Maximum. In contrast, the Sr/Ba proxy accurately records the terrestrial-to-marine transition at these sites. Paradoxically, Sr/Ba in lake sediments shows wide ranges related to differences in sediment sources and lake-water chemistry, which highlights the necessity of accurately understanding lake dynamics before interpreting sedimentary salinity proxies. Finally, we tested the influence of clay-mineral assemblages on sediment B/Ga, demonstrating that clay mineralogy is generally not a first-order control on salinity interpretations. Our results strongly support the general robustness of elemental proxies for paleosalinity reconstruction while highlighting the need to take potential confounding factors into consideration.</div></div>","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":"678 ","pages":"Article 122664"},"PeriodicalIF":3.6,"publicationDate":"2025-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143207239","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":"Quantitative insight into Cr(VI) adsorption and reduction by ferrihydrite-humic acid co-precipitates: Development of multistep kinetic model integrating synergistic/antagonistic factors","authors":"Jingjie Chang ,&nbsp;Hui Wang ,&nbsp;Kai Qiao ,&nbsp;Jinqi Zhu ,&nbsp;Yikang Chen ,&nbsp;Jia Zhang ,&nbsp;Qiang Xue ,&nbsp;Huanzhen Zhang ,&nbsp;Honghan Chen ,&nbsp;Beidou Xi","doi":"10.1016/j.chemgeo.2025.122659","DOIUrl":"10.1016/j.chemgeo.2025.122659","url":null,"abstract":"<div><div>Ubiquitous amorphous ferrihydrite (Fh) and humic substances (HSs) combining into co-precipitates fundamentally alters the processes by which they reduce the mobility and toxicity of Cr(VI) contaminants in groundwater and soil. However, the kinetic characteristics of the interactions between Fh–humic acid (HA) co-precipitates and Cr(VI) remain poorly understood. In this study, the kinetics of Cr(VI) adsorption and reduction by Fh–HA co-precipitates were examined under mildly acidic experimental conditions (pH 4–5). Compared to Fh and HA in their pure phases, Cr(VI) adsorption by Fh in co-precipitates was inhibited (antagonistic adsorption), whereas Cr(VI) reduction by HA in co-precipitates was enhanced (synergistic reduction). A successful multistep kinetic model was developed to simulate this complex reaction process involving both adsorption and reduction and effectively overcome the limitations of classical kinetics. The antagonistic adsorption effect ranged between 2 %–11 % mainly because of HA competing for adsorption sites on Fh, whereas the synergistic reduction effect varied between 116 %–518 % mainly because the highly reductive active components within the HA molecules preferentially bind to Fh during co-precipitate formation (molecular fractionation). Both the antagonistic adsorption and synergistic reduction effects are influenced by the structural types of the Fh–HA co-precipitates, being particularly pronounced in Fh-like co-precipitates characterized by a low C/Fe ratio. Our findings provide a comprehensive perspective for quantitatively assessing the role of Fh–HS co-precipitates regarding Cr(VI) contamination in groundwater, contributing to its evaluation, management, and remediation.</div></div>","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":"678 ","pages":"Article 122659"},"PeriodicalIF":3.6,"publicationDate":"2025-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143207237","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":"Seas to lakes and vice-versa: A test of facies versus elemental salinity proxies","authors":"Mariano N. Remírez ,&nbsp;Ernesto Schwarz ,&nbsp;Geoffrey J. Gilleaudeau ,&nbsp;Gonzalo D. Veiga ,&nbsp;Thomas J. Algeo","doi":"10.1016/j.chemgeo.2025.122663","DOIUrl":"10.1016/j.chemgeo.2025.122663","url":null,"abstract":"<div><div>Recognizing marine-to-lacustrine (M-L) and lacustrine-to-marine (L-M) transitions can be difficult in stratigraphic successions, particularly in those composed of fine-grained sediments containing few fossils. Here, we test the utility of elemental salinity proxies (i.e., B/Ga and excess B) to assist in constraining the timing of such transitions in mixed marine-lacustrine strata of the Cretaceous (Valanginian-Hauterivian) Agrio Formation in Argentina. A combination of salinity and redox proxy data reveal that initial isolation of the Neuquén Basin watermass from seawater exchange resulted in transient hypersalinity and deepwater anoxia, followed by long-term freshening of the evolving lacustrine system. Subsequently, reconnection with the global ocean was marked by a large salinity increase prior to the appearance of marine fossils and transgressive surfaces. Our findings demonstrate the utility of elemental salinity proxies in identifying M-L and L-M transitions in fossil-poor, fine-grained successions, and they highlight the importance of using geochemical proxies in combination with sedimentological and paleontological information to understand salinity transitions in paleodepositional systems.</div></div>","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":"678 ","pages":"Article 122663"},"PeriodicalIF":3.6,"publicationDate":"2025-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143378318","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":"Water-air-CO2-flux changes after damming rivers loaded with suspended basaltic particles","authors":"T. Linke ,&nbsp;E.S. Eiriksdottir ,&nbsp;G.N. Petersen ,&nbsp;S.R. Gislason","doi":"10.1016/j.chemgeo.2025.122662","DOIUrl":"10.1016/j.chemgeo.2025.122662","url":null,"abstract":"<div><div>Contributions of CO₂ emissions from reservoirs to the atmosphere are continuously increasing with rising energy demand. Therefore, it is important to quantify the emissions and define the rate determining mechanism of CO₂ fluxes in man-made reservoirs. Here we present results from two reservoirs in Iceland over a total time span of 16 years. The partial pressure of CO₂ within the Hálslón reservoir, fed by glacier meltwater loaded with suspended basaltic particles, was considerably less than the CO₂ pressure of the atmosphere during the years 2008–2013. The specific CO₂ uptake from the atmosphere into Hálslón was estimated at 121 ± 67.9 g_CO2 m⁻² yr during the 6 months ice-free period or 5000 t annually. The uptake rate was governed by the CO₂ gradient across the water-air-interphase and windspeed but less by temperature. However, temperature will affect water-rock interactions and sub-zero temperature can result in ice cover, terminating water-air interactions. Atmospheric CO₂ concentration dictates the maximum upper limit of the CO₂ influx rate at fixed wind speed.</div><div>The downstream mixing of Hálslón reservoir water with the CO₂ emitting Lagarfljót reservoir lowered the CO₂ emissions from Lagarfljót from 5335 t CO₂ yr⁻¹ to 1670 t CO₂ yr⁻¹ after the damming. This study shows that dissolution of basalt in glacier melt waters leads to direct CO₂ uptake from the atmosphere, which can potentially be utilised for future carbon removal from the atmosphere.</div></div>","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":"678 ","pages":"Article 122662"},"PeriodicalIF":3.6,"publicationDate":"2025-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143103219","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}