Applied Geochemistry最新文献

{"title":"Paleoenvironmental assessment of a lower Jurassic succession in the NW-German Basin employing DRIFTS","authors":"Tim Marten ,&nbsp;Yves Alain Brügger ,&nbsp;Guido Lars Bruno Wiesenberg ,&nbsp;Lorenz Schwark","doi":"10.1016/j.apgeochem.2025.106362","DOIUrl":"10.1016/j.apgeochem.2025.106362","url":null,"abstract":"<div><div>High-resolution reconstruction of paleoenvironmental conditions of sedimentation requires the qualitative and quantitative assessment of the major sediment-forming fractions, i.e., carbonate, clay, quartz and organic matter. Simultaneous determination of these sediment-forming fractions by cost-effective and rapid methodologies is difficult to achieve. Previously, either XRF-, XRD-, and microscopy-based methods, or combinations thereof have been employed, complemented by organic carbon analysis. We here present a simultaneous approximation of the most relevant sediment-forming constituents, carbonate, clay, and organic matter, as well as quartz and feldspar, if present in sufficient quantity, by Diffusive Infra-Red Fourier Transformation Spectroscopy (DRIFTS). The technique does not require elaborated sample preparation or large sample amounts and is conducted without analytical reagents, solvents or carrier gases, thereby allowing high sample through-put. As such, DRIFTS investigation is ideal for stratigraphically highly-resolved studies. We applied DRIFTS to a sediment succession of Pliensbachian/Toarcian age and differentiated six sedimentary facies intervals that previously had been established based on application of more sophisticated but also more cost- and time-affording methodologies like XRF, XRD and programmed pyrolysis. While having been applied previously to characterization of soils and kerogen concentrates, we here demonstrate applicability of the DRIFTS technique to analysis of pre-Quaternary and consolidated sedimentary sequences.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"184 ","pages":"Article 106362"},"PeriodicalIF":3.1,"publicationDate":"2025-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143684156","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":"Hydrochemistry and stable isotopes of the Ili River: Deciphering spatiotemporal moisture sources and climatic drivers in Central Asia's wet island","authors":"Haizhao Jing ,&nbsp;Hongbiao Gu ,&nbsp;Shuangshuang Lan ,&nbsp;Haibin Wei ,&nbsp;Jiyi Jiang ,&nbsp;He Wang ,&nbsp;Mingqian Li ,&nbsp;Baoming Chi","doi":"10.1016/j.apgeochem.2025.106345","DOIUrl":"10.1016/j.apgeochem.2025.106345","url":null,"abstract":"<div><div>The Ili Valley in northwestern China plays a vital role as a green oasis in the large-scale moisture cycle and water utilization in Central Asia's core. To clarify the distinctive hydrochemical characteristics and genesis that differentiate it from the neighboring arid areas, the first large-scale sampling of river water covering the entire Ili Valley was conducted. The results show that the hydrochemical and stable isotopic characteristics vary spatially and seasonally among the tributaries. Rock weathering mainly controls the major ion composition in river water, which gradually varies along the river due to evaporation and snowmelt. The δ²H and δ¹⁸O values range from −103.00‰ to −72.00‰ and −15.00‰ to −9.60‰, respectively. Contrary to what is expected, the δ²H &amp; δ¹⁸O in the Tekes &amp; Ili Rivers are enriched with altitude, showing an “inverse altitude effect\" influenced by topography and moisture sources; the Karsh River has lower δ¹⁸O values due to snowmelt; the Kunes River has a U-shaped trend of isotopic concentrations and high <em>d</em>-excess values by precipitation. Both the seasonal deviations in river waterlines (RWL¹ vs RWL²) and the backward trajectory by HYSPLIT 4.0 showed that the origin of spring moisture at low troposphere in the Ili Valley could be traced to the surrounding regions, the summer moisture mixed with frigid air from the Arctic Ocean, while sub-cloud evaporation and surface-groundwater interaction are also the factor internally within the basin. The findings complement the basin-scale hydrochemical monitoring data and help investigate the large-scale hydrological cycle.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"184 ","pages":"Article 106345"},"PeriodicalIF":3.1,"publicationDate":"2025-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143785976","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":"Groundwater arsenic and the role of secondary Fe/Mn hydroxides in a volcaniclastic aquifer, Guanacaste, Costa Rica","authors":"Henry Ericson ,&nbsp;Molly Klingner ,&nbsp;Julianna Martinez ,&nbsp;Ian Nolon ,&nbsp;Lila Olson ,&nbsp;Robin Potter ,&nbsp;Peter Ryan ,&nbsp;Kira Zalis Waldman ,&nbsp;Guillermo E. Alvarado","doi":"10.1016/j.apgeochem.2025.106359","DOIUrl":"10.1016/j.apgeochem.2025.106359","url":null,"abstract":"<div><div>Elevated arsenic (As) in the regional water supply from a volcaniclastic aquifer in Costa Rica is an example of the increasing problem of As-contaminated waters in aquifers throughout Latin America. In this study, potential sources of As were assessed by (1) measuring the solid-phase chemical composition of volcaniclastic aquifer sediments and intercalated paleosols, (2) analyzing As speciation and availability by sub-millimeter scale elemental mapping and targeted chemical extractions, and (3) mapping spatial trends of As in shallow drinking water wells, surficial hot springs, and deep wells producing geothermal waters. Iron-manganese hydroxides (Fe/Mn hydroxides) in this aquifer system contain 210–530 ppm As that sorbs to this solid phase when released by chemical weathering of As-bearing volcanic glass. Arsenic is primarily transferred from solid to aqueous state when groundwater conditions shift from oxidizing to reducing, likely driven by presence of organic matter or periods of water logging (e.g. rainy season or irrigation). The occurrence of isolated hot springs raises the possibility that arsenic in groundwater may result from mixing of low-As meteoric waters with localized high-As thermal waters (hot springs). However, experimental evidence for release of As upon reductive dissolution of Fe/Mn hydroxides in solid-phase aquifer sediments plus the homogeneous and widespread 10–60 ppb As content in drinking water wells indicate that Fe/Mn hydroxide breakdown is the primary cause of the widespread As contamination in the regional aquifer. Locally, natural upwelling of thermal waters may affect wells in close proximity to surficial hot springs, but minimal evidence of this was observed in this study. Given the high incidence of elevated As in groundwater in volcaniclastic aquifers in Latin America and similar environments globally, these results are applicable to understanding As speciation and source, in particular drawing attention to the significance of secondary Fe/Mn hydroxides in arsenic cycling in volcaniclastic aquifers.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"184 ","pages":"Article 106359"},"PeriodicalIF":3.1,"publicationDate":"2025-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143684157","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":"Specific conductance and water type as a proxy model for salinity and total dissolved solids measurements in the Upper Colorado River Basin","authors":"R. Blaine McCleskey ,&nbsp;Charles A. Cravotta III ,&nbsp;Matthew P. Miller ,&nbsp;Tanner W. Chapin ,&nbsp;Fred Tillman ,&nbsp;Gabrielle L. Keith","doi":"10.1016/j.apgeochem.2025.106358","DOIUrl":"10.1016/j.apgeochem.2025.106358","url":null,"abstract":"<div><div>Salinity levels in streams and tributaries of the Colorado River Basin have been a major concern for the United States and Mexico for over 50 years as the water is used by millions of people for domestic and industrial purposes. Recently, the United States Geological Survey expanded stream monitoring networks including the number of sites where continuous (15-min) specific conductance is measured in the Colorado River Headwaters and Gunnison River Basin located east of the Colorado-Utah state line (hereafter, UCOL). The purpose of this study is to apply a proxy method to determine salinity and total dissolved solids concentrations from specific conductance and major-ion water type that is applicable to monitoring sites in the UCOL. Within the UCOL, carbonate rich waters originate from high-elevation mountain regions in the eastern UCOL, calcium sulfate rich waters are mainly found in the western half of the UCOL including the Gunnison River Basin, and waters of variable composition are found along the lower reaches of the Colorado River and Eagle River. It was found that the chemistry of sites with variable composition changes seasonally and is impacted by both geogenic and anthropogenic processes, potentially including seasonal application of deicing road salt. The specific conductance – water type proxy can be used to reliably (±10 %) predict salinity and total dissolved solids at 66 monitoring sites in the UCOL. The method is rapid, can generate high-resolution measurements, is cost-effective, and greatly expands the utility of specific conductance measurements. Furthermore, the high-resolution estimates provide an accurate approach to determining long-term salinity loads as short-term events are accurately accounted for.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"184 ","pages":"Article 106358"},"PeriodicalIF":3.1,"publicationDate":"2025-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143643649","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":"Investigation on the performance and mechanism of Cr(VI) immobilization with improved amorphous iron polysulfide: Batch experiments and numerical simulation","authors":"Kelin Zhang ,&nbsp;Danqing Liu ,&nbsp;Jinhao Yu ,&nbsp;Changzhong Xu ,&nbsp;Yilian Li","doi":"10.1016/j.apgeochem.2025.106357","DOIUrl":"10.1016/j.apgeochem.2025.106357","url":null,"abstract":"<div><div>Amorphous iron sulfides (FeS_x), which are more powerful than crystalline FeS_x in reduction, are commonly found on the surfaces of many sulfidated nanoscale zero-valent iron (nZVI). However, due to the interference of nZVI, the reduction performance of FeS_x is still unknown. In this paper, we synthesized efficient amorphous iron polysulfide (AIPS) with FeSO₄ and CaS_x and checked its reduction ability using Cr(VI) as a model contaminant, and found that the reactivity and amorphous structure of AIPS were significantly affected by the titration rate of CaS_x during synthesis. The removal of Cr(VI) by AIPS synthesized at a titration time of 120 min was 81.9 mg/g, which was 10.6 times higher than that of AIPS synthesized within 6 min (7.7 mg/g). The improved AIPS can be applicable for Cr(VI) removal via simultaneous adsorption, reduction and precipitation at wide pH range and in the coexistence of ionic and natural organic matter (NOM). Using a reactive transport model, it can be found that FeS and FeS₂ in AIPS contribute 85.01 % and 14.99 % to the Cr(VI) reduction, respectively. FeS_x (x &gt; 2), also as a reaction by-product of the Cr(VI) reduction by FeS and FeS₂, hinders the reduction of Cr(VI).</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"184 ","pages":"Article 106357"},"PeriodicalIF":3.1,"publicationDate":"2025-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143643650","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":"Groundwater recharge sources analysis of coastal aquifer under the impact of cut-off walls: A case study of the Dagu River","authors":"Bo Zhang ,&nbsp;Haoran Wu ,&nbsp;Yang Liu ,&nbsp;Peihua Li ,&nbsp;Zhihong Zheng","doi":"10.1016/j.apgeochem.2025.106356","DOIUrl":"10.1016/j.apgeochem.2025.106356","url":null,"abstract":"<div><div>Water quality degradation due to seawater intrusion is a globally significant environmental and geological issue. Cut-off walls, besides mitigating seawater intrusion, can alter groundwater flow direction and rate. Re-analysis recharge sources in coastal aquifers with cut-off walls is crucial for hydrogeological research and water resource management. Our study focused on the Lower Dagu River, where cut-off walls were installed. We employed the M3-MIX method to analyze groundwater recharge sources. The qualitative assessment revealed a substantial reduction in regional hydraulic connections across the cut-off walls, although weak seasonal connections persist due to groundwater level fluctuations and wall heights. Using M3-MIX, we identified four recharge sources in the south area—three salt groundwater sources and one saline surface water source—with mixing ratios of 1.4 %, 44.3 %, 41.8 %, and 12.5 %, respectively. In the north area, three recharge sources were identified—a river water sample, a saline surface water sample, and a groundwater sample—with mixing ratios of 14.9 %, 26.8 %, and 58.3 %, respectively. Our findings underscore the impact of cut-off walls on recharge sources and highlight the importance of re-analysis these sources for effective exploitation and protection of coastal aquifer water resources.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"183 ","pages":"Article 106356"},"PeriodicalIF":3.1,"publicationDate":"2025-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143610388","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":"Best practices of utilizing principal component analysis in chemostratigraphic studies","authors":"Nikolaos A. Michael ,&nbsp;Mustafa A. Al Ibrahim ,&nbsp;Christian Scheibe ,&nbsp;Neil Craigie","doi":"10.1016/j.apgeochem.2025.106355","DOIUrl":"10.1016/j.apgeochem.2025.106355","url":null,"abstract":"<div><div>Principal Component Analysis (PCA) is a powerful tool and can be used to interpret the chemical composition of geological rock samples. However, what are the best practices when dealing with these data and workflows? A very important step to the analysis of PCA variables is the related eigenvector analysis to determine element-mineral links and relationships between elements and geological conditions (e.g. depositional environment, diagenesis, weathering). We present two examples to demonstrate the usefulness of the technique: one from carbonate sediments, the other from siliciclastics.</div><div>The second part of the paper focuses on the behavior of eigenvectors and principal components (PCs) with changing datasets. For this, 1000s of experiments were performed in different lithologies and subsets of data on carbonate, siliciclastic and mixed carbonate-siliciclastic sediments to understand the relative position of the elements in eigenvector space when the quantity of data is increased and decreased. This helped us deduce best practices for undertaking such analysis in the future.</div><div>From the experiments, we demonstrate that a stable model exists for PC1 and PC2 variables (i.e. the first and second most important sources of statistical variation) for only 100 samples. For higher orders of PCs (PC3-PC6) 1000s of samples are sometimes required for a stable model. This implies that it is not possible to expect the results of PCA analysis to be the same in each study with respect to higher orders of PCs. You can only transfer a geological interpretation from one study to the other if the eigenvectors from the reference dataset are applied to the next and only if the data are represented in the original study.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"186 ","pages":"Article 106355"},"PeriodicalIF":3.1,"publicationDate":"2025-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143853877","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":"A new 1,10-phenanthroline method for oxalate-extractable iron measurement","authors":"Yan Zhang ,&nbsp;Yi Liu","doi":"10.1016/j.apgeochem.2025.106354","DOIUrl":"10.1016/j.apgeochem.2025.106354","url":null,"abstract":"<div><div>Iron separation from different solid phases is essential for evaluating the environmental function of iron in sediments. Oxalate is a commonly used extractant that effectively extract iron(hydro)oxides in sediments by complexation. However, when using spectrophotometry method, excess oxalate will interfere the complexation of iron with 1,10-phenanthroline leading to the failure of iron measurement. In this study, we discovered an effective method for spectrophotometric analysis of iron samples with oxalate by adjusting the pH to 7–9, which changes the structure of the Fe-oxalate complexes and ensured the complexation of iron with 1,10-phenanthroline. Further exploration indicates that photolysis and heating also decompose Fe-oxalate complexes, but the performance is not as good as pH adjustment. The standard solution exhibits a strong linear relationship between absorbance (<em>Abs</em>) and concentration (<em>Con</em>): <em>Abs</em> = 0.1934 × <em>Con</em> + 0.1360, with a R² of 0.9997, accuracy of 97.1 %, and relative standard deviation of 1.4 %, which demonstrate the reliability of this method. Overall, the pretreatment is simple, and the influence of the organic solvent (oxalate) is diminished after pH adjustment. This method is expected to contribute to community by providing a new reliable, effective, less pre-treatment, economical, and sensitive testing approach and hopefully assist in the investigation on environmental function of iron minerals.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"183 ","pages":"Article 106354"},"PeriodicalIF":3.1,"publicationDate":"2025-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143628110","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":"Investigation of plutonium diffusion profiles in Opalinus Clay rock via TOF-SIMS and rL-SNMS","authors":"Felix Berg,&nbsp;Christopher Sirleaf,&nbsp;Janik Lohmann,&nbsp;Markus Breckheimer,&nbsp;Tobias Reich","doi":"10.1016/j.apgeochem.2025.106332","DOIUrl":"10.1016/j.apgeochem.2025.106332","url":null,"abstract":"<div><div>The capability of the combined approach of time-of-flight secondary ion mass spectrometry (TOF-SIMS) and resonant laser secondary neutral mass spectrometry (rL-SNMS) for the analysis of diffusion samples of <figure><img></figure> in Opalinus Clay (OPA) under aerobic conditions was investigated at the micrometer scale. The speciation of Pu in the diffusion reservoir with OPA pore water (pH 7.6) was determined as <span><math><msubsup><mrow><mtext>PuO</mtext></mrow><mrow><mtext>2</mtext></mrow><mrow><mtext>+</mtext></mrow></msubsup></math></span> using capillary electrophoresis coupled to inductively coupled plasma mass spectrometry (CE-ICP-MS). Using modern 3D printing techniques, a simple and easily scalable experimental setup was developed and adapted to the requirements of TOF-SIMS and rL-SNMS. Together, these techniques allowed for the observation of the pristine diffusion profile of Pu while retaining information about the heterogeneous clay rock. For the experiment with 35 days of in-diffusion, the modeling of an averaged diffusion profile of approximately 300<!--> <!-->µm length resulted in <span><math><msub><mrow><mi>D</mi></mrow><mrow><mi>a</mi></mrow></msub></math></span> = 3.2(4) × 10^-15 <!-->m² <!-->s^-1. TOF-SIMS and rL-SNMS mappings showed heterogeneous distributions of Pu inside the clay rock and correlations with the matrix elements Fe and Ca, pointing to pyrite and a cementing calcite phase as reactive mineral phases.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"183 ","pages":"Article 106332"},"PeriodicalIF":3.1,"publicationDate":"2025-03-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143610285","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Hydrochemical evolution of groundwater in a semi-arid environment verified through natural tracer and geochemical modelling, northwest Australia","authors":"Shawan Dogramaci ,&nbsp;Ilka Wallis ,&nbsp;Peter Cook ,&nbsp;Allan Kneeshaw","doi":"10.1016/j.apgeochem.2025.106337","DOIUrl":"10.1016/j.apgeochem.2025.106337","url":null,"abstract":"<div><div>The semi-arid Hamersly Basin in Australia is the hub for extensive mining, which requires the relocation of a significant volume of groundwater for dry mining operations. Understanding water balance components is crucial for managing and conserving water resources. This study adopts a joint approach using isotopic and hydrochemical techniques to identify and quantify water sources and recharge dynamics to explain the integral functioning of a typical floodplain aquifer.</div><div>The observed chloride and stable isotopes suggest a mixing of recharge from high-rainfall cyclonic events and highly evaporated low-rainfall events at a ratio of 60:1. The highly evaporated water from light rainfall events would remain in the soil profile until mixed with precipitation from high-rainfall events recharge the underlying aquifers. The recharge rates by multiple methods range from 0.3 mm/y to 14.4 mm/y. Groundwaters have a unique hydrochemical signature and are characterised by high alkalinity and dissolved oxygen. The total dissolved solutes (TDS) range from fresh to brackish, however, most of the groundwater tends to have a TDS &lt;1000 mg/L. The δ²H and δ¹⁸O concentrations of water samples vary over a narrow range despite a wide range of Cl concentrations. The data are consistent with salt concentration by evapotranspiration within the unsaturated zone, which becomes mixed with infiltration of rainfall from large cyclonic events. The hydrochemical pathway modelling for the major ion distribution shows that groundwater has evolved by evapo-concentration of rainfall prior to recharge in the unsaturated zone. This is followed by an increase in dissolved CO₂ and the precipitation of carbonate minerals. Although the initial dissolved CO₂ is acquired due to the decomposition of organic matter during passage through the unsaturated zone, the 10-fold higher CO₂ (pCO₂∼ −2.5) compared to atmospheric levels in the aquifer suggests the addition of further alkalinity due to aluminosilicate weathering. The negative correlation between δ³⁴S_SO4 and the SO₄/Cl ratio suggests the addition of sulphate to groundwater with relatively depleted δ³⁴S_SO4 values. The source of sulphate is likely to be the oxidation of pyrite from the bedrock, which is characterised by high arsenopyrite concentration. The results suggest that climatic conditions impart a unique signature on the groundwater quality. The method can be utilised to constrain water balance components such as recharge for floodplain aquifers globally.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"183 ","pages":"Article 106337"},"PeriodicalIF":3.1,"publicationDate":"2025-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143580468","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}