Chemical Geology最新文献

{"title":"TEMPORARY REMOVAL: The sedimentary geochemistry and paleoenvironments project phase 2 data release: An open data resource for the study of Earth's environmental history","authors":"Úna C. Farrell, Hunter C. Olson, Maya O. Thompson, Michelle L. Abshire, Oyeleye O. Adeboye, Anne-Sofie C. Ahm, Lewis J. Alcott, Thomas J. Algeo, Ross P. Anderson, Arif H. Ansari, Lucas Pinto Heckert Bastos, Kohen W. Bauer, Brian Beaty, Justin E. Birdwell, Fred T. Bowyer, Jochen J. Brocks, Tessa Brunoir, James F. Busch, Donald E. Canfield, Fabrício A. Caxito, Chao Chang, Meng Cheng, Jean N.R. Clemente, David R. Cordie, Peter W. Crockford, Huan Cui, Celeste M. Cunningham, Tais W. Dahl, Janaina Rodrigues de Paula, Carol M. Dehler, Lucas Del Mouro, Keith Dewing, Dermeval Aparecido do Carmo, Stephen Q. Dornbos, Nadja Drabon, Julie A. Dumoulin, Omabehere Innocent Ejeh, Emily Ellefson, Maya Elrick, Joseph F. Emmings, Bokanda Ekoko Eric, Hao Fang, Gabriella Fazio, Henrique A. Fernandes, Katherine L. French, Robert R. Gaines, Richard M. Gaschnig, Timothy M. Gibson, Geoffrey J. Gilleaudeau, Karin Goldberg, Zheng Gong, Amy P.I. Hagen, Galen P. Halverson, Kalev Hantsoo, Emma R. Haxen, Miles A. Henderson, João P.T.M. Hippertt, Malcolm S.W. Hodgskiss, Paul F. Hoffman, Edward C. Huang, Benjamin W. Johnson, Pavel B. Kabanov, Junyao Kang, C. Brenhin Keller, Brian Kendall, Julien Kimmig, Sara R. Kimmig, Michael A. Kipp, Andrew H. Knoll, Timmu Kreitsmann, Anurag A. Kulkarni, Alexandra Kunert, Marcus Kunzmann, Jiankang Lai, Richard O. Lease, Chao Li, Sen Li, Alex G. Lipp, Yang Liu, David K. Loydell, Xinze Lu, Katie M. Maloney, Kaarel Mänd, Alexie E.G. Millikin, N. Tanner Mills, Kento Motomura, Chiza N. Mwinde, Lyle L. Nelson, Nora M. Nieminski, Brennan O'Connell, Edel O'Sullivan, Juliana Okubo, Jaden K. Olah, Frantz Ossa Ossa, Chadlin M. Ostrander, Kärt Paiste, Camille A. Partin, Egberto Pereira, Shanan E. Peters, Tiffany Playter, Susannah M. Porter, Simon W. Poulton, Sara B. Pruss, Zhen Qiu, Daven P. Quinn, Mariano Remírez, Sebastian Richiano, Sylvain Richoz, Kathryn I. Rico, Samantha R. Ritzer, Zachary Roney, Alan D. Rooney, William C. Rose, Elias J. Rugen, Swapan K. Sahoo, Shane D. Schoepfer, Judith A. Sclafani, Nathan D. Sheldon, Yanan Shen, Graham A. Shields, Pulkit Singh, Arvind Kumar Singh, Sarah P. Slotznick, Emily F. Smith, Haijun Song, Sam C. Spinks, Richard G. Stockey, Justin V. Strauss, Eva E. Stüeken, Zongyuan Sun, Dongjie Tang, Lidya G. Tarhan, Danielle Thomson, Nicholas J. Tosca, Rosalie Tostevin, Chenyi Tu, Maoli N. Vizcaíno, Yuxuan Wang, Changle Wang, Xiaomei Wang, Lucas Veríssimo Warren, Lucy C. Webb, Philip R. Wilby, Christina R. Woltz, Rachel Wood, Yuyang Wu, Xiuqing Yang, Inessa A. Yurchenko, Junpeng Zhang, Jessica H. Whiteside, Benjamin C. Gill, Akshay K. Mehra, Kimberly V. Lau, Noah Planavsky, David T. Johnston, Erik A. Sperling","doi":"10.1016/j.chemgeo.2025.123148","DOIUrl":"https://doi.org/10.1016/j.chemgeo.2025.123148","url":null,"abstract":"","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":"375 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2025-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145532066","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":"Nitrogen solubility in Fe-bearing bridgmanite and its implications for nitrogen segregation in Earth's deep magma ocean","authors":"Ko Fukuyama ,&nbsp;Hiroyuki Kagi ,&nbsp;Tetsuo Irifune ,&nbsp;Toru Shinmei ,&nbsp;Yuki Inoue ,&nbsp;Junji Yamamoto ,&nbsp;Johan Villeneuve ,&nbsp;Evelyn Füri","doi":"10.1016/j.chemgeo.2025.123154","DOIUrl":"10.1016/j.chemgeo.2025.123154","url":null,"abstract":"<div><div>Nitrogen is abundant on Earth's surface, comprising 78 vol% of the atmosphere. However, its relative abundance in the bulk silicate Earth, normalized to carbonaceous chondrites, is depleted by about one order of magnitude compared to other volatile elements. The deep Earth, particularly the lower mantle, where the behavior of nitrogen remains poorly understood, has been considered as a strong candidate for solving the so-called “missing” nitrogen problem.</div><div>Here, we experimentally investigated the effect of iron content on nitrogen solubility in bridgmanite, which constitutes 75 wt% of the lower mantle. High-pressure experiments were conducted using a multi-anvil apparatus at 28 GPa and 1400–1600 °C under redox conditions corresponding to those in the lower mantle.</div><div>Nitrogen solubility in the Fe-bearing bridgmanite increased from 2.1 ± 0.3 ppm to 6.9 ± 1.5 ppm with increasing FeO content from 1.9 wt% to 7.7 wt% at 1500 °C. Based on the temperature dependence of nitrogen solubility in MgSiO₃-bridgmanite, nitrogen solubilities in pyrolitic bridgmanite were estimated to be 9.2 ± 1.9 ppm (μg/g) at 1700 °C. The estimated nitrogen storage capacity of pyrolitic bridgmanite along a mantle geotherm is 3.6 ± 0.8 ppm in the bulk Earth, equivalent to 5.5 ± 1.2 PAN (PAN: mass of present atmospheric nitrogen). These results suggest that bridgmanite alone is insufficient to account for the “missing” nitrogen in the present-day bulk Earth, as its nitrogen storage capacity is lower than required to match chondritic volatile abundances. Instead, bridgmanite may have played a key role in segregating nitrogen into the deep mantle during the solidification of the magma ocean.</div></div>","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":"699 ","pages":"Article 123154"},"PeriodicalIF":3.6,"publicationDate":"2025-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145553674","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":"Decoupling between silicate and phosphate mineral weathering in the granitic periglacial weathering-limited landscape of the Loch Vale watershed, Rocky Mountain National Park, Colorado, USA","authors":"Jason R. Price ,&nbsp;Suzanne Bricker ,&nbsp;Emerson Andelt ,&nbsp;James Kinnison","doi":"10.1016/j.chemgeo.2025.123150","DOIUrl":"10.1016/j.chemgeo.2025.123150","url":null,"abstract":"<div><div>The sole source of phosphorus (P⁵⁺) to natural waters and ecosystems is from bedrock chemical weathering. Phosphorus influences atmospheric CO₂ and global climate through its relationship with marine photosynthetic productivity. Solute-based watershed mass-balance methods were used to determine that bedrock fluorapatite dissolution released 48 ± 2 mol P⁵⁺ ha⁻¹ yr⁻¹ from the granitic periglacial Loch Vale watershed (LVW) in Colorado, USA during the 1984–2008 measurement period. This solute-based P⁵⁺ flux is one of the highest reported in the literature despite LVW bedrock P₂O₅ concentrations being ∼0.07 wt%. Frost-cracking in a weathering-limited landscape was responsible for enhanced fluorapatite dissolution. Extrapolating the area-normalized flux to all high-elevation crystalline and volcanic ecoregions of the Southern Rocky Mountains yields a total P⁵⁺ flux of ∼9 Gg yr⁻¹ which is comparable with the Greenland Ice Sheet.</div><div>Combining the LVW P⁵⁺ flux with the labile P⁵⁺ concentrations of outlet lake sediment provided a sediment yield rate of ∼190 tons km⁻² yr⁻¹. This value compares favorably with Southern Rocky Mountain granitic watershed cosmogenic nuclide-determined sediment yield rates reported in the literature. Thus, the primary disposition of P⁵⁺ is loss from the LVW adsorbed to sediment.</div><div>Biogeochemical models predicting P⁵⁺ fluxes routinely assume positive correlations between bedrock P⁵⁺ concentrations and terrestrial P⁵⁺ fluxes, and/or phosphate and silicate mineral weathering, with neither being true for the LVW. Because anthropogenic climate change may result in altered P⁵⁺ supplies to ecosystems and agriculture, biogeochemical models should be parameterized to include the P⁵⁺ dynamics of granitic weathering-limited periglacial landscapes.</div></div>","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":"699 ","pages":"Article 123150"},"PeriodicalIF":3.6,"publicationDate":"2025-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145553676","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":"The physical properties of Alexandrian Roman glass: Industrial optimization in the first world market","authors":"Pascal Richet ,&nbsp;Kai-Uwe Hess","doi":"10.1016/j.chemgeo.2025.123146","DOIUrl":"10.1016/j.chemgeo.2025.123146","url":null,"abstract":"<div><div>The viscosity and thermal expansion of samples from a well-preserved Roman glass ingot from the late 2nd-early 3rd century Embiez-Ouest 1 shipwreck have been measured over wide temperature ranges to determine how this material was originally produced and how to preserve it now. Measurements of the viscous and volume relaxation indicate that the annealing range of this glass ranges between 750 and 780 K and exemplifies the fact that relaxation kinetics depend not only on temperature but also on the structural state of the glass. As investigated by differential scanning calorimetry, a very slow cooling rate of about 0.4 K/day has been determined from the glass originally produced, which agrees with the size of up to 20 tons of the tank furnaces dug out in the Egyptian Wâdî Natrûn area. In terms of both chemical composition and properties, Embiez Ouest 1 glass is strikingly similar to modern window glasses. Relying on abundant natron and shell-bearing siliceous sands, this early successful industrial optimization relied on chemical compositions close to the eutectic of the Na₂O-CaO-SiO₂ system, which made mass production possible to such an extent that it gave rise to the first industrial world market.</div></div>","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":"699 ","pages":"Article 123146"},"PeriodicalIF":3.6,"publicationDate":"2025-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145536000","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 insights into iron and sulfur cycling in acid sulfate soils: Implications of seasonal redox fluctuations","authors":"Sarah Conrad ,&nbsp;Katerina Rodiouchkina ,&nbsp;Federico Alvarellos ,&nbsp;Björn Öhlander ,&nbsp;Lena Alakangas","doi":"10.1016/j.chemgeo.2025.123151","DOIUrl":"10.1016/j.chemgeo.2025.123151","url":null,"abstract":"<div><div>Acid sulfate soils (AS-soils), common in coastal, estuarine, and mining-impacted areas, form under reducing conditions and can cause severe environmental degradation by releasing acidity and mobilizing heavy, trace, and toxic metals when sulfide minerals oxidize under changing hydrological conditions. AS-soils exhibit redox gradients that govern iron (Fe) and sulfur (S) cycling, affecting their mobility, mineral forms, and isotopic compositions. This study combines Fe/S ratios, δ⁵⁶Fe and δ³⁴S isotope systematics, sequential extractions, and groundwater monitoring to assess redox-driven processes in two AS-soil profiles from northern Sweden. In reduced zones, negative δ⁵⁶Fe and δ³⁴S values signal microbial Fe(III) and sulfate reduction, producing Fe(II) and sulfides. In oxidized zones, secondary Fe (oxy)hydroxides and sulfates form, inheriting isotopic signals from precursor sulfides. Groundwater δ⁵⁶Fe enrichment reflects Fe oxidation, while high δ³⁴S values (up to +45.2 ‰) indicate ongoing sulfate reduction. Groundwater Fe/S ratios (0.07–8.24) reveal redox interactions but are unreliable as sole redox indicators. Sequential extractions show that redox-sensitive pools—water-soluble, exchangeable, and organic-bound phases—exhibit strong isotope fractionation and drive short-term cycling, despite their small mass. Isotopic signals from different Fe phases within each profile likely offset each other when measured in bulk (∼0.06–0.11 ‰), diluting any clear redox-related patterns. Similarly, δ³⁴S values trace a shift from oxidized to stable sulfide-bound forms across depths and redox zones. The results emphasize the value of combining isotopic and phase-specific analyses to unravel redox heterogeneity, trace element fluxes, and identify acidification-prone zones. Environmentally, maintaining saturated conditions, encouraging reducing environments, and monitoring reactive Fe and S fractions can help limit the mobilization of heavy, trace, and toxic metals in AS-soils under shifting hydrology.</div></div>","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":"698 ","pages":"Article 123151"},"PeriodicalIF":3.6,"publicationDate":"2025-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145531207","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":"Copper isotopic compositions of surface sediment in the Yangtze Estuary and East China Sea Shelf","authors":"Daqian Zhang ,&nbsp;Jincun Liu ,&nbsp;Lian Zhou ,&nbsp;Qian Wang ,&nbsp;Lanping Feng ,&nbsp;Jinhua Liu ,&nbsp;Yating Hu ,&nbsp;Thomas J. Algeo","doi":"10.1016/j.chemgeo.2025.123149","DOIUrl":"10.1016/j.chemgeo.2025.123149","url":null,"abstract":"<div><div>Estuaries represent an important interface between rivers and oceans within which copper (Cu) can be sequestered or isotopically fractionated. However, the geochemical behavior of Cu isotopes in estuaries and adjacent continental shelves has not been adequately considered in previous assessments of the marine Cu cycle. Here, we use bulk-sample and sequential-extraction Cu isotope data in surface sediments of the Yangtze Estuary (YE), mixing zone (MZ), and adjacent East China Sea Shelf (ECSS) to reveal mechanism(s) of Cu isotopic fractionation in estuaries and their influence on the marine Cu cycle. Our results show that Cu is present mainly in clay minerals and iron oxides, and that variations in physicochemical conditions at the land-sea interface can lead to surface-sediment Cu isotope fractionation, yielding bulk-sample δ⁶⁵Cu values ranging from −0.07 to +0.30 ‰ (relative to NIST 976). The negative correlation of δ⁶⁵Cu with Al/Si in the YE and ECSS reflect adsorption of isotopically light Cu by clay minerals. Although the relationship of δ⁶⁵Cu to Al/Si is statistically insignificant in the MZ, this zone has higher clay-mineral content and lower bulk-sample δ⁶⁵Cu values than the YE. These results reflect the redistribution and fractionation of Cu among clay minerals during re-suspension of surface sediments in the MZ. We identify two pools of Cu in the surface sediments: a labile pool (including the exchangeable, reducible, oxidizable fractions) that is extractable using weak acidic leach, and a refractory pool (residual fraction). For the reducible copper fraction (Cu_ox), negative correlations between its amount (<em>f</em> Cu_ox) and isotopic composition (δ⁶⁵Cu_ox) in the YE, MZ and ECSS reflect desorption of isotopically light Cu from iron oxides. Additionally, the Cu isotopic values of the labile pool (+0.12 ± 0.04 ‰, <em>n</em> = 12, 2SD) are consistent with missing isotopically light Cu (∼ + 0.1 ‰) in our oceanic Cu mass balance model. These considerations suggest that re-suspension of estuarine surface sediment promotes release of isotopically light Cu to seawater. Thus, partial dissolution of terrigenous substances (including clays, iron oxides and organic matter) entering the ocean through estuaries is one of the main reasons for isotopically light Cu in surface seawater. Our results provide new insights into the marine biogeochemical cycle of Cu.</div></div>","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":"698 ","pages":"Article 123149"},"PeriodicalIF":3.6,"publicationDate":"2025-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145531300","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":"Impact of fungal exposure on structural and chemical alterations in ferrihydrite-goethite associations: Implications for metal mobility and environmental risks","authors":"Zuzana Goneková ,&nbsp;Marcel B. Miglierini ,&nbsp;Marek Bujdoš ,&nbsp;Július Dekan ,&nbsp;Edmund Dobročka ,&nbsp;Martin Urík","doi":"10.1016/j.chemgeo.2025.123145","DOIUrl":"10.1016/j.chemgeo.2025.123145","url":null,"abstract":"<div><div>The precipitation of ochreous materials at abandoned mining sites plays a key role in immobilizing hazardous metals and metalloids from mine drainage waters due to their high sorption capacity and surface reactivity. However, their stability may be compromised by interactions with filamentous fungi, a metal-tolerant microbial group capable of altering their chemical and structural properties. Such changes can increase contaminant mobility, posing ecological risks. Therefore, this study aims to investigate the elemental and structural characteristics of ochreous sediments and evaluates the impact of fungal bioleaching by fungus <em>Aspergillus niger</em>. Using Mössbauer spectroscopy, three ferric iron forms were identified, indicating a highly disordered ferrihydrite (outer layer of crystallite), ferrihydrite with lower degree of distortion (core) and a goethite-like phase. Fungal exposure resulted in nanoscale structural changes, particularly in less ordered ferric sites. Bioleaching led to significant iron extraction, leading to the release of hazardous elements, particularly arsenic, antimony, nickel, copper, and manganese. Simultaneously, structural transformations occurred, including the dissolution of goethite-like phases and less ordered ferric iron sites within ferrihydrite. These findings enable us to propose a structural model of ferrihydrite-goethite associations, suggesting that the spatial structure of each phase, rather than the inherent structural stability of the crystallites, plays a significant role in their mineralogical and chemical resilience and leachability.</div></div>","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":"698 ","pages":"Article 123145"},"PeriodicalIF":3.6,"publicationDate":"2025-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145478228","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":"Magnesium isotopic evidence for intensified continental chemical weathering during the Smithian-Spathian transition","authors":"Xingyu Ma ,&nbsp;Kangjun Huang ,&nbsp;Yan Chen ,&nbsp;Yadong Sun ,&nbsp;Ying Zhou ,&nbsp;Graham A. Shields ,&nbsp;Fang Huang ,&nbsp;Genming Luo","doi":"10.1016/j.chemgeo.2025.123133","DOIUrl":"10.1016/j.chemgeo.2025.123133","url":null,"abstract":"<div><div>The Smithian-Spathian (S-S) transition (∼249.7 to 248.7 Ma) of the Early Triassic was marked by profound paleoenvironmental upheavals, including a pronounced temperature decline following the hyperthermal event in the late Smithian, a major positive excursion in carbonate carbon isotope composition (δ¹³C_carb), and a significant biotic crisis. Yet, the mechanisms and causal linkages underlying these coeval phenomena remain elusive. In this study, we present high-temporal-resolution magnesium isotope data from siliciclastic residues within carbonate rocks (δ²⁶Mg_residue), a well-established proxy for continental chemical weathering intensity, across the S-S boundary in the Waili and Jiarong sections in South China. Our results document a distinct positive δ²⁶Mg_residue shift in the lowermost Spathian in both sections, signifying intensified continental chemical weathering. This isotopic shift broadly coincides with the positive δ¹³C_carb excursion and the recovery of terrestrial ecosystems but postdates the late Smithian thermal maximum. We interpret this temporal sequence to suggest that the recovery of terrestrial ecosystems, particularly the expansion of vascular land plants, acted as a primary driver of enhanced continental chemical weathering. The resulting increase in continental chemical weathering likely amplified nutrient flux to the ocean, potentially promoting local marine anoxia and climate cooling observed in the earliest Spathian. These findings underscore the critical role of terrestrial-marine coupling in modulating Early Triassic biogeochemical feedbacks and global climate evolution.</div></div>","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":"698 ","pages":"Article 123133"},"PeriodicalIF":3.6,"publicationDate":"2025-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145485564","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":"Influence of phosphate on hexavalent chromium immobilization by ferrihydrite under light irradiation","authors":"Chaorong Chen ,&nbsp;Sailan Wang ,&nbsp;Yixuan Yang ,&nbsp;Gaofeng Wang ,&nbsp;Jing Liu ,&nbsp;Qingze Chen ,&nbsp;Fei Ge ,&nbsp;Runliang Zhu","doi":"10.1016/j.chemgeo.2025.123144","DOIUrl":"10.1016/j.chemgeo.2025.123144","url":null,"abstract":"<div><div>Ferrihydrite is an important geosorbent and catalyst that is ubiquitous in natural environments, and plays a critical role in regulating the speciation and migration of hexavalent chromium (Cr(VI)). Phosphate has a strong affinity for ferrihydrite surfaces, but it remains unclear how phosphate influences the immobilization of Cr(VI) by ferrihydrite in sunlight-influenced surface environments. Herein, the surface interactions of ferrihydrite and Cr(VI) in the presence of phosphate were studied under mercury lamp irradiation. Results showed that mercury lamp irradiation significantly attenuated the inhibitory effect of phosphate on Cr(VI) removal by ferrihydrite compared to that under dark conditions. X-ray photoelectron spectroscopic (XPS) analysis revealed that Cr(III) was the predominant chromium species immobilized on ferrihydrite surfaces. Specifically, the reduction of Cr(VI) produced CrPO₄ precipitates, whereas the released Fe(III) can also co-adsorb with phosphate (i.e., FePO₄) onto ferrihydrite surfaces. The reduction of Cr(VI) mediated by the generated Fe(II) species and photoelectrons effectively reduces the electrostatic repulsion between Cr(VI) and phosphate, thereby enhancing the immobilization of these two ions on ferrihydrite. Energy dispersive X-ray spectrometer (EDS) results provide direct quantitative evidence that mercury lamp irradiation substantially enhances the immobilization of Cr(VI) and phosphate by ferrihydrite. The above-described results account for the effect of phosphate on the light-induced coupling process of ferrihydrite reductive dissolution and Cr(VI) reductive immobilization, advancing our understanding of the geochemical cycle of Cr(VI) pollution in sunlight-influenced surface environments.</div></div>","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":"698 ","pages":"Article 123144"},"PeriodicalIF":3.6,"publicationDate":"2025-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145485562","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":"Testing selenite gypsum crystals from caves for reconstructing the stable isotope composition of paleo-aquifers","authors":"Fernando Gázquez ,&nbsp;Xuefeng Wang ,&nbsp;Wuhui Duan ,&nbsp;Paolo Forti ,&nbsp;Stein-Erik Lauritzen ,&nbsp;José María Calaforra","doi":"10.1016/j.chemgeo.2025.123134","DOIUrl":"10.1016/j.chemgeo.2025.123134","url":null,"abstract":"<div><div>Selenite is a variety of gypsum (CaSO₄·2H₂O) that typically forms large, transparent prismatic crystals. In recent decades, meter-sized selenite crystals have been found in several caves worldwide. These gypsum speleothems formed underwater, in highly stable, epithermal or low-temperature aquifers. Here we investigate the U-Th ages of decimeter-sized selenite crystals from Cueva de los Cristales (Naica mine, northern Mexico) and the Giant Geode of Pulpí (Almería, southeastern Spain). Furthermore, the hydrogen and oxygen isotope compositions of gypsum hydration water measured along the crystal growth axes were used to reconstruct the isotopic evolution of the Naica and Pulpí paleo-aquifers. Extremely low uranium concentrations (&lt;2 ppb in Pulpí and &lt; 0.1 ppb in Naica) make obtaining reliable age models challenging. However, repeated independent measurements of each sample and using large sample sizes can yield reliable and accurate ages. A Naica crystal that grew over the last 31 ± 6 kyr recorded a stepwise change in the isotope composition of paleo-aquifer water, likely reflecting a shift in recharge isotopic composition (rainfall) due to Glacial–Holocene climate change in northern Mexico. A crystal from the Giant Geode of Pulpí that began growing at 191 ± 26 kyr recorded relatively constant δ²H groundwater values, likely reflecting stable climatic conditions during its formation. We critically discuss the caveats of using selenite gypsum crystals from caves as paleohydrological archives and conclude that, despite the challenges, they have strong potential for reconstructing the isotopic composition of paleo-aquifers and past rainfall.</div></div>","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":"698 ","pages":"Article 123134"},"PeriodicalIF":3.6,"publicationDate":"2025-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145462065","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}