Applied Geochemistry最新文献

{"title":"Sustainable removal of arsenic and mercury via integrated phytoremediation and biomass valorization of Eichhornia crassipes","authors":"Rashmi Ranjan Mandal,&nbsp;Deep Raj","doi":"10.1016/j.apgeochem.2026.106699","DOIUrl":"10.1016/j.apgeochem.2026.106699","url":null,"abstract":"<div><div>Phytoremediation using <em>Eichhornia crassipes</em> was assessed as a sustainable strategy for the removal and stabilization of arsenic (As) and mercury (Hg) from contaminated aquatic systems, followed by the conversion of harvested biomass into biochar to enhance long-term metal immobilization. The study assessed plant performance under two different contamination levels (1 and 5 mg L⁻¹) to understand concentration-dependent responses. At the lower concentration, <em>E. crassipes</em> achieved high removal efficiencies, arrive at 93 % As and 87 % Hg reduction within 30 days. However, the removal decreased significantly at 5 mg L⁻¹, with efficiencies dropping to 76 % for As and 52 % for Hg, indicating physiological limitations and reduced uptake capacity under higher metal stress. Morphological and spectroscopic study revealed significant structural alterations in plant tissues and showed the accumulation of As and Hg within cellular sections, validating the plant's role as an effective accumulator species. To ensure safe post-harvest handling and prevent secondary contamination, the metal-enriched biomass was subjected to pyrolysis. The resulting biochar showed strong retention of both metals, attributed to its carbonaceous structure and enhanced binding sites formed during thermal transformation. This stable biochar demonstrated clear potential for long-term immobilization and reduced metal mobility. Overall, the integrated process combining phytoremediation with biomass valorization offers an eco-friendly, cost-effective, and circular approach for mitigating toxic metal contamination in water bodies. The outcomes highlight the double benefit of pollutant removal and the production of a value-added material, improving the applicability of <em>E. crassipes</em> in sustainable environmental management.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"198 ","pages":"Article 106699"},"PeriodicalIF":3.4,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146024053","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Endolithic environments in hydrothermally altered volcanic rocks from a coastal spring in Baja California, México: Mineralogical interfaces and the search for preserved biosignatures","authors":"Enrique Iñiguez ,&nbsp;Vladimir Mendoza-Lavaniegos ,&nbsp;Thomas G. Kretzschmar","doi":"10.1016/j.apgeochem.2026.106700","DOIUrl":"10.1016/j.apgeochem.2026.106700","url":null,"abstract":"<div><div>Coastal hydrothermal systems provide valuable analog environments for investigating microbial‒mineral interactions and preserving biosignatures under extreme physicochemical gradients. At the Puertecitos intertidal spring in Baja California, México, we conducted an integrated mineralogical, geochemical, and structural analysis of a hydrothermally altered ignimbrite to characterize endolithic microbial habitats and their fossilization potential. Thin section petrography, SEM, XRD, FTIR, and μXRF revealed a vertically zoned substrate, including an unaltered ignimbrite, a weathered alteration fringe, a dark sulfide-rich transition, and a crystalline barite–quartz assemblage. Elemental mapping (Fe, S, Ba, Sr, and As) and principal component analysis highlighted distinct geochemical domains shaped by episodic hydrothermal fluid pulses and seawater mixing. Microtomography (μCT) revealed very low total and open porosities (0.29 % and 0.017 %, respectively) but unexpectedly high permeabilities attributed to interconnected microfractures. SEM imaging revealed abundant and morphologically diverse microbial biosignatures, which were predominantly preserved in the crystalline and transition zones through rapid silicification and barite precipitation. These microenvironments, which are structured by mineral precipitation and permeability anisotropy, provide localized redox gradients and nutrient sources that support the preservation of chemolithotrophic endolithic communities. Our results demonstrate that hydrothermal fluid dynamics, mineral precipitation, and rock microstructure govern the habitability and fossilization potential of volcanic substrates in geothermal settings (temperature ranges from 32.7 to 73.7 °C and pH 6.7–8.1). The Puertecitos system offers a compelling terrestrial analog for studying microbial survival, mineral-driven weathering, and biosignature preservation on early Earth and Mars, emphasizing the importance of mineralogical interfaces and hydrothermal processes in structuring habitable niches in extreme environments.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"198 ","pages":"Article 106700"},"PeriodicalIF":3.4,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146024058","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Predicting differentiated achondrite parent bodies through machine learning: Insights from major element","authors":"Zhao Yan ,&nbsp;Jin-Ting Kang ,&nbsp;Weibiao Hsu ,&nbsp;Fang Huang","doi":"10.1016/j.apgeochem.2026.106687","DOIUrl":"10.1016/j.apgeochem.2026.106687","url":null,"abstract":"<div><div>Rapid and accurate identification for parent bodies of achondrites is crucial for planetary science research. In this study, we examined the performance of machine learning algorithms using bulk rock major element compositions to classify the origins of achondrites derived from the Moon, Mars, and asteroid 4 Vesta. Literature data on lunar basalts and anorthosites, Martian meteorites, and HED meteorites potentially originating from Vesta, are compiled and cleaned. Multiple machine-learning models were applied including a Tabular Prior-data Fitted Network (TabPFN) and six classical models including Decision Tree, Gradient Boosting, Support Vector Machine, Random Forest, K-Nearest Neighbors, and Multilayer Perceptron. All models demonstrate robust classification performances achieving over 95 % accuracy for the Test Set. Particularly, the K-Nearest Neighbors and TabPFN models achieve an accuracy exceeding 99 %. This study presents a new, automated method in identifying the parent body of achondrites through bulk rock major element data. While these models perform well, further analysis of feature importance is needed to provide deeper insights into the underlying geochemical controls, ensuring the method complements traditional approaches such as petrography and isotope analysis. To facilitate the broader use by meteorite collectors, cosmochemistry community and enthusiasts, a web interface has been developed to quickly apply this technique: <span><span>https://geo-cosmo-chemistry.shinyapps.io/meteorites_classification/</span><svg><path></path></svg></span>.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"198 ","pages":"Article 106687"},"PeriodicalIF":3.4,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146024123","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Application of the Keeling plot approach in quantifying sediment organic matter sources using carbon isotopes and C/N ratios: An example from Xiaowan Reservoir, Lancang River basin, China","authors":"Mingwei Guo ,&nbsp;Shilu Wang ,&nbsp;Kevin M. Yeager ,&nbsp;Xiangfeng Han ,&nbsp;Yuchun Wang ,&nbsp;Shehong Li ,&nbsp;Yufei Bao ,&nbsp;Weiqi Lu ,&nbsp;Zhenjie Zhao ,&nbsp;Kun Liu ,&nbsp;Jiaxi Wu","doi":"10.1016/j.apgeochem.2026.106703","DOIUrl":"10.1016/j.apgeochem.2026.106703","url":null,"abstract":"<div><div>Partitioning autochthonous and allochthonous organic matter (OM) contributions to reservoir sediments is essential for accurately estimating the magnitude of carbon sequestration in reservoirs. The commonly used combination of C/N ratios and organic carbon isotopes (δ¹³C_OC) is often limited by poorly constrained end-member compositions, which hampers quantitative source apportionment. In this study, four sediment cores were collected from the Xiaowan Reservoir, a large and deep reservoir in the Lancang River basin, China. Total organic carbon (TOC), total nitrogen (TN), and δ¹³C_OC were measured to test the hypothesis that the Keeling plot approach can be used to localize the compositional values of sedimentary OM sources. To adapt the Keeling plot method to this multi-source system, a “dominant source” assumption was introduced. The resulting end-member compositions for terrestrial plant, algal, bacterial, and soil OM are consistent with previously reported values but exhibit substantially reduced uncertainty. Organic matter source apportionment using the MixSIAR Bayesian mixing model indicates that bacterial reworking represents the dominant contribution to sedimentary OM. The narrowed, site-specific end-member ranges derived from the Keeling plot approach demonstrate strong potential for resolving subtle spatial (horizontal) and temporal (vertical) variations in OM sources within reservoir sediments. Identifying appropriate sampling sites that satisfy the underlying assumptions of the method is therefore critical for its successful application.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"198 ","pages":"Article 106703"},"PeriodicalIF":3.4,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146074600","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Fluid chemistry and isotopes for interpreting the formation of geothermal systems in the southern Qinghai-Xizang Plateau","authors":"Xingze Li ,&nbsp;Yuankang Zhong ,&nbsp;Peng Zhou ,&nbsp;Gongxi Liu ,&nbsp;Hua Wu ,&nbsp;Ying Wang ,&nbsp;Xiaoyan Zhao ,&nbsp;Xingcheng Yuan ,&nbsp;Jinhang Huang ,&nbsp;Yunhui Zhang","doi":"10.1016/j.apgeochem.2026.106710","DOIUrl":"10.1016/j.apgeochem.2026.106710","url":null,"abstract":"<div><div>As a clean and renewable energy resource, geothermal energy significantly contributes to lowering carbon emissions and fostering sustainable development over the long term. This study investigates the genesis, hydrochemical evolution, and reservoir characteristics of geothermal waters in the Southern Qinghai−Xizang Plateau. 45 geothermal water samples were examined for their physicochemical properties, major ion concentrations, and stable isotope compositions (δD, δ¹⁸O). To categorize hydrochemical facies and identify the dominant geochemical processes, multivariate statistical techniques, including hierarchical cluster analysis (HCA), correlation analysis (CA), and principal component analysis (PCA) were applied. Two distinct hydrochemical clusters were identified: a Cl–Na type characterized by higher TDS and Cl⁻ concentrations, and an HCO₃–Na type with elevated bicarbonate levels. Isotopic data indicate meteoric recharge with significant oxygen isotope drift, and calculated recharge elevations suggest recharge primarily occurs between 2900 and 4533 m and 3767−4700 m, respectively. Water–rock interaction analysis reveals that silicate weathering, carbonate dissolution, cation exchange, and magmatic fluid input are the dominant processes shaping water chemistry. Geothermometric calculations using quartz and chalcedony solubility, combined with silica–enthalpy mixing models, indicate reservoir temperatures of 111–245 °C (Cl–Na type) and 102–224 °C (HCO₃–Na type), with circulation depths ranging from 1631 to 3692 m and 1492–3369 m, respectively. The genesis model proposed in this study suggests that both water types originate from deep thermal circulation systems with variable proportions of magmatic fluid input (Cluster 1: 10 %–26 %, average 19 %; Cluster 2: 6 %–28 %, average 15 %) and mixing with shallow cold groundwater. These findings provide a scientific basis for sustainable geothermal resource development and contribute to a better understanding of geothermal systems in complex tectonic settings of orogenic belts.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"198 ","pages":"Article 106710"},"PeriodicalIF":3.4,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146074670","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Impact of mixing pattern on oil-mineral aggregation and oil removal in coastal waters: A lab-scale study","authors":"T.R. Akshaya ,&nbsp;Ethayaraja Mani ,&nbsp;K. Murali ,&nbsp;Jan Schwarzbauer","doi":"10.1016/j.apgeochem.2025.106676","DOIUrl":"10.1016/j.apgeochem.2025.106676","url":null,"abstract":"<div><div>Ensuing an oil spill, oil-mineral aggregates (OMAs) are formed due to the aggregation of dispersed oil droplets with suspended sediment particles such as clay minerals. This process mainly occurs in coastal areas where suspended sediments interact with the oil droplets formed by the turbulent action of the waves. To better understand the effect of the mixing patterns on OMA formation, we study the formation and oil removal percentage (ORP) of OMAs under two mixing conditions: (1) orbital shaker and (2) magnetic stirrer, representing inward and outward directional flow patterns, respectively, at similar mixing energies. It impacts OMA formation by altering droplet-particle collision frequency and the balance between aggregation and shear-induced breakup. The experiments are conducted using bentonite and kaolinite clay at various concentrations. The kinetics of ORP are analysed using a logistic saturation curve, and the kinetic parameters are determined. The findings of the study indicate that the ORP is higher for mixing conditions of the orbital shaker, which causes the fluid to move along the container wall creating a swirling motion. The fastest removal occurred at a concentration of 1 g/L for kaolinite OMAs. The maximum ORP was observed to be 70 % for kaolinite and 65 % for bentonite. This work establishes a clear understanding of the effect of the mixing flow directionality on ORP and OMA formation under various concentrations. These findings provide valuable insights into the natural attenuation of dispersed oil in coastal environments and improve the mitigation of the impacts of oil spills.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"198 ","pages":"Article 106676"},"PeriodicalIF":3.4,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145923856","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Sulfides as metallogenic tracers of fluid evolution at the Baishizhang molybdenum deposit, South China","authors":"Yue Hou ,&nbsp;Huan Li ,&nbsp;Thomas J. Algeo ,&nbsp;Jianjun Liu ,&nbsp;Weidong Ren ,&nbsp;Mohammad Naseer ,&nbsp;Nuerkanati Madayipu","doi":"10.1016/j.apgeochem.2026.106729","DOIUrl":"10.1016/j.apgeochem.2026.106729","url":null,"abstract":"<div><div>The Baishizhang (BSZ) deposit is a large-scale molybdenum (Mo) deposit in the Nanling Range of South China, with sulfide mineralization representing its most economically significant stage. This study integrates petrographic observations, in situ geochemical analyses of multi-generation sphalerite (Sp-1 and Sp-2), pyrite (Py-1 and Py-2), and chalcopyrite (Ccp-1, Ccp-2 and Ccp-3), and multivariate statistical analyses in order to elucidate fluid evolution and metallogenic processes during the sulfide stage. Textural relationships and paragenetic associations indicate a progressive mineralization sequence, beginning with an early sulfide stage dominated by abundant Py-1 with minor Ccp-1, followed by extensive Sp-1 and Ccp-2 mineralization, and evolving into middle-late stages characterized by molybdenite mineralization with minor Sp-2, Py-2, and Ccp-3. Principal component analysis (PCA) and factor analysis (FA) confirmed the first-order control of crystallochemical effects on elemental incorporation into multi-generation sulfide precipitates, while partial least squares-discriminant analysis (PLS-DA) revealed the second-order influence of fluid sources and physicochemical conditions on their trace-element compositions. The combined signatures of sphalerite sulfur isotopes and pyrite Co/Ni ratios indicate a dominantly magmatic-hydrothermal origin for the early sulfide stage, followed by overprinting by reduced, Mo-rich hydrothermal fluids during the middle-late stages. Systematic variations in trace-element compositions of different sphalerite generations document the involvement of meteoric waters during the middle-late stages. Furthermore, the observed trace-element systematics of multiple generations of sphalerite, pyrite, and chalcopyrite suggest that the early sulfide stage developed under conditions of high <em>f</em>S₂, moderate temperature (∼257 °C), low <em>f</em>O₂, low pH, and low salinity. During the middle-late sulfide stages, <em>f</em>S₂, pH, and salinity increased, while temperature (∼180 °C) and <em>f</em>O₂ decreased. This study demonstrates that integrated analysis of multiple generations of sulfide minerals provides robust constraints on fluid evolution and metallogenic mechanisms in Mo mineralization systems, and it highlights the value of multivariate geochemical approaches in deciphering complex hydrothermal processes.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"199 ","pages":"Article 106729"},"PeriodicalIF":3.4,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146171462","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Contribution of dissolved organic carbon to total alkalinity in Enhanced Weathering experiments","authors":"Lukas Rieder ,&nbsp;Mathilde Hagens ,&nbsp;Reinaldy Poetra ,&nbsp;Alix Vidal ,&nbsp;Tullia Calogiuri ,&nbsp;Anna Neubeck ,&nbsp;Abhijeet Singh ,&nbsp;Thomas Corbett ,&nbsp;Harun Niron ,&nbsp;Sara Vicca ,&nbsp;Siegfried E. Vlaeminck ,&nbsp;Iris Janssens ,&nbsp;Tim Verdonck ,&nbsp;Ivan Janssens ,&nbsp;Xuming Li ,&nbsp;Jens S. Hammes ,&nbsp;Jens Hartmann","doi":"10.1016/j.apgeochem.2026.106685","DOIUrl":"10.1016/j.apgeochem.2026.106685","url":null,"abstract":"<div><div>Total Alkalinity (TA) is widely used as a proxy for captured CO₂ in enhanced weathering (EW) applications. However, organic anions can also contribute to TA. To improve carbon accounting in EW, which is often simplified to that TA equals carbonate alkalinity, their contribution should be taken into account.</div><div>In this study, we tested how dissolved organic carbon (DOC) contributes to non-carbonate alkalinity (A_NC) using microcosm experiments with artificial organo-mineral mixtures. We used different combinations of rock powder with straw, microbes and earthworm additions, under ambient air conditions. The microcosms were flow-through columns placed in a climate chamber at 25 °C, which were irrigated with groundwater at rates between 1200 and 3600 mm/yr. The concentrations of several low-molecular-weight organic acids (oxalate, citrate, acetate, gluconate) were quantified to assess which conjugate base anions impact the measured TA.</div><div>Results revealed a ratio of 3.5 mol DOC per A_NC equivalent. In the overall experiment the median contribution of A_NC to TA was around 5.5 %. A positive correlation between DOC and charge-balance error suggests that some organic acid anions remained deprotonated during TA titration. Acetate anions found in DOC-rich water samples further support a substantial contribution of organic anions to TA. To investigate the relevance of A_NC for natural EW systems, we also quantified A_NC contributions in natural waters and leachates from soil EW experiment mesocosms. Because DOC levels were lower, A_NC contributions were smaller, ranging from a median of 4.1 % in soil mesocosm leachates down to 0.9 % in Elbe estuary water samples. This A_NC contribution, despite seeming small, is relevant for carbon accounting in terrestrial EW practices, where TA is often assumed to be solely carbonate alkalinity.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"198 ","pages":"Article 106685"},"PeriodicalIF":3.4,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146024054","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The origin and evolution of waters in the Miocene formation of the Carpathian Foredeep","authors":"Marek Hajto ,&nbsp;Barbara Uliasz-Misiak ,&nbsp;Bogumiła Winid","doi":"10.1016/j.apgeochem.2026.106680","DOIUrl":"10.1016/j.apgeochem.2026.106680","url":null,"abstract":"<div><div>The autochthonous Miocene molasse sediments filling the Carpathian Foredeep (SE Poland) are rich in mineralised waters. This study aimed to determine the origin and hydrogeochemical evolution of these waters. The analysis of mineralisation, chemical composition, and selected hydrochemical indicators of groundwater was used to identify their genesis and the processes that influenced their composition over geological time.</div><div>More than 2000 water analyses from Miocene formations were compiled and verified according to hydrogeochemical standards. The analysed parameters included TDS, chloride, sulphate, bicarbonate, sodium, calcium, magnesium, and bromide. Waters were grouped by depth and geographic location to assess spatial and vertical variability, and key ion ratios were calculated.</div><div>Most of the waters occurring in Miocene formations are of the sodium–chloride type, typical of zones isolated from active circulation. Their mineralisation increases irregularly with depth. According to hydrochemical indicators, Miocene waters are primarily brines or chloride waters genetically related to seawater. However, variance in chemical composition indicates partial infiltration by meteoric waters. Waters at various depths may contain components of infiltration origin.</div><div>Ion exchange and the dissolution or precipitation of carbonate and sulphate minerals were the main factors shaping water chemistry, alongside seawater evaporation and halite dissolution. Although groundwater chemistry does not differ significantly between the eastern and western parts of the basin, deeper horizons (below 1000 m b.g.l.) show greater variation.</div><div>The complexity of processes affecting Miocene formation waters is reflected in the lack of clear correlations among parameters.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"198 ","pages":"Article 106680"},"PeriodicalIF":3.4,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146023992","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Impacts of snow nitrate photolysis and recycling on identification of oxidation information recorded in nitrate in Antarctica","authors":"Xiaolong Li ,&nbsp;Guitao Shi ,&nbsp;Yilan Li ,&nbsp;Danhe Wang ,&nbsp;Ye Hu ,&nbsp;Wendell W. Walters","doi":"10.1016/j.apgeochem.2026.106709","DOIUrl":"10.1016/j.apgeochem.2026.106709","url":null,"abstract":"<div><div>The oxygen isotopes of nitrate (NO₃⁻), specifically δ¹⁸O(NO₃⁻) and Δ¹⁷O(NO₃⁻), provide insights into the oxidation mechanisms responsible for NO₃⁻ formation and reflect the atmospheric oxidation capacity. However, these isotopic signatures can be altered by post-depositional processes. This study collected data on NO₃⁻ nitrogen and oxygen isotopes in various samples, including snowpits, ice cores, snowfall, and skin layer snow, from different Antarctic regions. We observed a linear relationship between δ¹⁸O(NO₃⁻) and Δ¹⁷O(NO₃⁻) at each site, suggesting that NO₃⁻ production involves a mixture of oxidants such as O₃/XO, OH, and HO₂/RO₂, with O₃ identified as a key contributor. The δ¹⁸O values of other oxidants, termed as the derived δ¹⁸O, were obtained from this linear relationship at each site, excluding O₃, and showed a decreasing trend from the coast to inland region in Antarctica. We found that these derived δ¹⁸O values exhibited significant linear correlations with the reciprocal of the snow accumulation rate and δ¹⁸O(H₂O), indicating the differences in NO₃⁻ photolysis and recycling processes within snowpack across various sites. Additionally, we estimated the average photolysis-driven loss fraction of NO₃⁻ and its oxygen exchange fraction with H₂O, and found that both processes are more intense on the East Antarctic plateau and weaker in coastal regions, largely controlled by snow accumulation rate. At low accumulation sites, the derived δ¹⁸O values are more affected by local δ¹⁸O(H₂O), leading to modifications of the atmospheric oxidation signals recorded in the ice core NO₃⁻.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"198 ","pages":"Article 106709"},"PeriodicalIF":3.4,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146074671","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}