Applied Geochemistry最新文献

{"title":"Variability of fracture surface roughness in crystalline host rocks: implications for transport model simplifications","authors":"Wenyu Zhou ,&nbsp;Johannes Kulenkampff ,&nbsp;Daniel Jara Heredia ,&nbsp;Thorsten Schäfer ,&nbsp;Cornelius Fischer","doi":"10.1016/j.apgeochem.2025.106401","DOIUrl":"10.1016/j.apgeochem.2025.106401","url":null,"abstract":"<div><div>Variability in fracture geometry and its complex surface characteristics are major contributors to solute transport and retention effects in rocks such as granite. Understanding the effects of cross-scale fracture geometry on solute transport modeling is critical for reliable quantitative predictions in applications such as geothermal energy use and nuclear repository safety. Here, we systematically investigated the sensitivity of fracture surface topography variability to the flow field and solute transport behavior. Specifically, we investigated the role of multiscale fracture surface roughness in solute transport modeling. As a starting point, our study utilized a 3D fracture geometry derived from CT scans and employed COMSOL Multiphysics software for solute transport modeling. By introducing increasingly lower spatially resolved geometries, while maintaining a constant high resolution mesh for simulation calculations, we investigated the consequences for transport on surfaces composed of superimposed building blocks of different sizes and shapes. The results indicate that fracture geometry simplifications with reduced spatial frequency information of well-defined, specific domains do not have a clear trend to alter the BTCs tailing. Instead, this type of model simplification can cause both increased and decreased tracer residence times, leading to misleading interpretations. We explain this by a complex superposition of surface building blocks of different sizes, such as single crystal surface pits, grain boundaries between crystals, and fracture curvature. For model sensitivity analyses, we suggest the use of concentration difference and acceleration maps to identify local transport heterogeneities introduced by geometric simplifications. In addition, we conclude that power spectral density (PSD) analysis provides a means of defining a range of surface spatial frequencies that helps to avoid oversimplification in geometric models of reactive transport.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"186 ","pages":"Article 106401"},"PeriodicalIF":3.1,"publicationDate":"2025-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143870648","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 responses of minerals during the dissolution of basalt for geological storage of CO2","authors":"Jun-Hwan Bang,&nbsp;Taehee Kim,&nbsp;Soo-Chun Chae,&nbsp;Kyungsun Song","doi":"10.1016/j.apgeochem.2025.106402","DOIUrl":"10.1016/j.apgeochem.2025.106402","url":null,"abstract":"<div><div>Dissolution experiments involving basalt grains (grain size: 0.841–1.190 mm) were conducted under CO₂-saturated conditions to investigate mineralogical changes and fluid chemistry dynamics relevant to geological CO₂ storage. The experiments were initially performed at 35 °C (up to 137 days) and subsequently at 50 °C (up to 210 days). Mineralogical analyses were conducted using scanning electron microscopy with backscattered electron imaging (SEM-BSE), electron probe microanalysis (EPMA), and X-ray diffraction (XRD). The initial dissolution stage was characterized by rapid olivine dissolution, causing substantial early release of magnesium (Mg) and iron (Fe). Labradorite dissolution became increasingly significant after the temperature increase to 50 °C, enhancing mobilization of calcium (Ca), magnesium (Mg), and aluminum (Al). SEM-BSE analyses revealed distinctive dissolution textures on olivine grains, characterized by pronounced Mg depletion and Fe enrichment. Fluid chemistry results reflected these mineralogical changes, indicating rapid initial Mg release, sustained mobilization of silicon (Si) and Fe from ongoing olivine dissolution, and elevated Ca and Al concentrations after temperature elevation due to increased dissolution of plagioclase (labradorite) and, to a lesser extent, augite. Secondary silica precipitation occurred during later reaction stages, inferred from decreasing dissolved Si concentrations. These findings emphasize temperature- and mineral-specific dissolution behaviors, providing critical insights for optimizing basalt-hosted CO₂ sequestration.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"186 ","pages":"Article 106402"},"PeriodicalIF":3.1,"publicationDate":"2025-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143853878","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":"Amendment effectiveness and seasonal variations in a lead contaminated acidic wetland","authors":"Matthew R. Noerpel ,&nbsp;Anna M. Wade ,&nbsp;Aaron R. Betts ,&nbsp;Jennifer Goetz ,&nbsp;Robert Ford ,&nbsp;Amy Krause ,&nbsp;Michael Zeolla ,&nbsp;Diana Cutt ,&nbsp;Stephanie M. Wilson ,&nbsp;Todd P. Luxton","doi":"10.1016/j.apgeochem.2025.106396","DOIUrl":"10.1016/j.apgeochem.2025.106396","url":null,"abstract":"<div><div>Three in-situ lead (Pb) soil amendment treatment methods were tested over 26 months in a naturally acidic contaminated wetland with the intent of sequestering high levels of Pb contamination as stable mineral forms. Two of the treatments used Apatite II, a phosphate-based amendment, to promote the formation of pyromorphite. The apatite amendment was surface applied one method and physically mixed to the surface soils in the other. A sulfate-rich compost-based mixture was used for the third treatment, with the goal to promote the formation of galena. Amendment effectiveness was evaluated by comparison of Pb porewater concentrations between treatments, and by changes in the speciation of sediment Pb as determined by X-ray absorption spectroscopy (XAS). Results show that in the two years following application, the three treatments did not make a significant impact on Pb mobility and speciation. Dissolved Pb concentrations did not decrease significantly in the treatment plots in comparison to the control plots. Furthermore, speciation analysis did not show evidence of pyromorphite formation in the phosphate-amended plots. Galena was found in the third treatment with sulfate-rich compost, however the significance of this was limited by sample size and the presence of galena in other areas of the wetland. There was a seasonal variation in the Pb speciation, with galena and Pb-cysteine being more prevalent at the end of the wet season and less prevalent at the end of the dry season, indicating that while the induced formation of reduced Pb-sulfur species is possible, there are challenges to maintaining those species without concurrent control of soil water saturation. This study shows that effective amendment treatments must account for site-specific characteristics such as pH and redox dynamics, and use appropriate preservation methods for accurate speciation results.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"185 ","pages":"Article 106396"},"PeriodicalIF":3.1,"publicationDate":"2025-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143839031","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":"Geochemical and isotopic (oxygen, hydrogen, sulfur) indicators constraining the origin and contribution ratios of dissolved sulfate in shallow aquifers from the lower Yellow River floodplain, northern China","authors":"Han Geng ,&nbsp;Chunli Su ,&nbsp;Weijiang Liu ,&nbsp;Junxia Li ,&nbsp;Xianjun Xie ,&nbsp;Huijian Shi ,&nbsp;Zhantao Han","doi":"10.1016/j.apgeochem.2025.106388","DOIUrl":"10.1016/j.apgeochem.2025.106388","url":null,"abstract":"<div><div>Sulfate (SO₄²⁻) contamination of groundwater is becoming a major public health threat in the lower Yellow River floodplain of southwest Shandong Province. In this study, 72 shallow groundwater samples, 18 surface water samples and 21 industrial wastewater samples (including 4 mine drainage samples used to analyze the effects of coal mining activities) were collected to investigate the origins of sulfate in the water environment. Hydrochemical and isotopic data of SO₄²⁻ (δ³⁴S and δ¹⁸O) and H₂O (δD and δ¹⁸O) as well as stable isotope mixing models in R (SIMMR) were integrated to identify the sulfate sources and the proportions of each source in different watersheds. The results showed that chemical fertilizer is the dominant source of sulfate in surface water in most of the area, while manure and atmospheric deposition are the main sources of sulfate in groundwater. The contributions of evaporites dissolution to sulfate are most significant in surface water and groundwater in Jiaxiang and southern Yuncheng counties. In areas with intensive industrial activities, the contribution of industrial sewage to water bodies is also considerable. The groundwater in Juye and Jiaxiang Counties in the downstream of Zhuzhaoxin River is worst affected by mine drainage. The hydrogeological setting and anthropogenic activities jointly controlled the sulfate in the water. The research not only provide useful methodology and clues for similar studies in other sulfate contaminated areas, but also exemplify the vital importance of hydrogeochemical and isotopic monitoring for the sustainable management of water resources.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"185 ","pages":"Article 106388"},"PeriodicalIF":3.1,"publicationDate":"2025-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143828809","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":"Isotope geochemical study of the origin and formation mechanism of carbonate minerals in geothermal wells and surrounding hot spring waters in the western Unzen area","authors":"Akira Ueda ,&nbsp;Heejun Yang ,&nbsp;Yukiko Hoshino ,&nbsp;Sakurako Satake ,&nbsp;Dongyang Mao ,&nbsp;Amane Terai","doi":"10.1016/j.apgeochem.2025.106384","DOIUrl":"10.1016/j.apgeochem.2025.106384","url":null,"abstract":"<div><div>In areas of volcanic and geothermal activity, caprock and other impermeable layers regulate the flow direction of geothermal fluids. However, it is unclear how this impermeable layer was formed or at what depth. This impermeable layer is partly formed by carbonate minerals. In the Unzen area, the temperature logging results of geothermal wells showed that high temperature fluids move as lateral flow. In this study, we focused on the carbonate minerals in the area and determined the origin of the fluids from their isotope compositions. This study explores the formation mechanisms of carbonate layers through reactions between CO₂-rich water and rocks within a volcanic geothermal system. Samples were collected from two geothermal wells and adjacent hot spring water in the western Unzen area for chemical and isotope analysis. The UZ-7 well, located near Mt. Unzen, features carbonate mineral layers at depths of approximately −300 m and −600 m. The isotope compositions of carbon and oxygen within these layers indicate a magmatic origin for the carbon, with the fluid mixture consisting of meteoric water, magmatic fluid, and fossil seawater. Deep fluids in the western Unzen region likely undergo vapor–brine separation at about −600 m elevation, where vapor escapes as fumarole gas and hot spring water in the Unzen hot spring area. The brine, approximately 240 °C, then flows westward, emerging at Obama hot spring. This lateral movement and heating of surrounding strata to about 150 °C at depths of −300 m and −600 m facilitate extensive calcite precipitation (up to 100 m thick) through rock interactions nearing chemical equilibrium. This process also results in significant kaolinite and chlorite deposition, potentially forming two impermeable caprock layers. The UZ-4 well, situated 2 km west of UZ-7, also exhibits carbonate layers, albeit on a reduced scale, likely due to insufficient rock reactions from progressively cooler brine temperatures.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"185 ","pages":"Article 106384"},"PeriodicalIF":3.1,"publicationDate":"2025-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143826357","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":"Deciphering colloidal transport of copper in partially remediated mine tailings by single particle analysis and transmission electron microscopy","authors":"Joel Kroeker ,&nbsp;Michael Schindler ,&nbsp;Richard Oliveira ,&nbsp;Feiyue Wang","doi":"10.1016/j.apgeochem.2025.106361","DOIUrl":"10.1016/j.apgeochem.2025.106361","url":null,"abstract":"<div><div>Abandoned mine tailings are an environmental and financial liability worldwide and require often extensive reclamation efforts. A combination of single particle analysis and transmission electron microscopy, along with bulk chemical analysis, ultracentrifugation and ultrafiltration, are used to decipher the chemical, mineralogical and colloidal composition of an abandoned gold mine tailings at the Nopiming Provincial Park, Manitoba, Canada. The tailings are the result of the discharge of chalcopyrite-rich mine waste and were in recent years partially reclaimed through capping of two ponds with dolomite- and organic-rich soils. The surficial layers at the fully and partially affected sites have higher pH, inorganic and organic carbon content than the underlying tailings, whereas the surficial tailings at the unaffected site are more acidic and depleted in Cu relative to the reduced zone occurring at greater depth. The speciation of Cu in extracted acidic leachates is characterized by Cu²⁺ and CuSO₄ species, whereas Cu-organic complexes only play a role in weak acidic leachates extracted from the fully affected site and the reduced layer at the unaffected site. Studies of the colloidal fraction indicate that many colloids are coated by organic- or silica-rich layers, which in combination with the pH control their zeta potential and aggregation. The number of particles per time interval and the relative standard deviation of the Cu concentration per particle increase at a higher rate with increasing concentration of Cu in the colloidal fraction. These correlations are explained with a greater increase in the proportions of colloids containing trace (e.g. biomass-based colloids) and minor (clay mineral-based colloids) amounts of Cu relative to colloids where Cu is a major element (Cu-sulfate bearing colloids). A comparison of the mineralogical and chemical composition of the tailings and their colloidal fractions indicates that the formation of Cu-bearing colloids is favored in partly neutralized tailings of weak acidic pH and in the absence of efflorescent salts.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"184 ","pages":"Article 106361"},"PeriodicalIF":3.1,"publicationDate":"2025-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143815985","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":"Water compositional evolution around a historic asbestos mine, Troodos mountains, Cyprus","authors":"Aled D. Evans ,&nbsp;Dave Craw ,&nbsp;Joanna L. Shannon ,&nbsp;Joseph Hattersley ,&nbsp;Lewis J.C. Grant ,&nbsp;Rosalind M. Coggon ,&nbsp;Damon A.H. Teagle","doi":"10.1016/j.apgeochem.2025.106387","DOIUrl":"10.1016/j.apgeochem.2025.106387","url":null,"abstract":"<div><div>The historic Amiantos chrysotile asbestos mine (closed 1988) in the Troodos mountains, is hosted in serpentinites that constitute the Artemis Diapir. Host rocks were extensively sheared and brecciated during Pleistocene-Holocene diapiric uplift, enabling penetration of meteoric waters. Veins of serpentine minerals, especially fibrous chrysotile, have formed throughout this uplift history with accompanying carbonates, and carbonate surface precipitates that form at spring sites. The Artemis Diapir is juxtaposed by faults against less-permeable partially serpentinised peridotites of the Olympus Diapir that forms the highest elevation (1952 m) of the Troodos Mountains. Streams and shallow groundwater draining the Artemis Diapir have high concentrations of Mg²⁺ and dissolved inorganic carbon (DIC), minor Ca²⁺, and pH 8–10. In addition, these waters have high concentrations of Na⁺, K⁺, Cl⁻, SO₄²⁻ and trace elements Cs, Ba, Br, B, and Li sourced from the dissolution of mineral inclusions in the host serpentinites. These dissolved constituents overprint low levels of marine aerosols that occur in local meteoric precipitation. Passage of surficial waters through asbestos mine tailings have locally enhanced dissolution of these elements because of even higher permeability and small particle size that resulted from mine-related comminution. All surficial waters are strongly supersaturated with respect to chrysotile (log Q/K = 3–9) and carbonate minerals, especially magnesite (log Q/K = 1–2). Evaporative carbonate precipitates form episodically on stream beds and tailings surfaces during dry seasons. Erosion of mine tailings and friable host rocks by rain events in the steep mountain environment contributes detrital chrysotile asbestos to stream sediments, with potential for aeolian remobilization. The relatively high abundance of carbonates already in the rocks and mine residues, combined with carbonate and chrysotile supersaturation in surficial waters, limits the efficacy of these materials for CO₂ capture through enhanced weathering and mineral carbonation.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"185 ","pages":"Article 106387"},"PeriodicalIF":3.1,"publicationDate":"2025-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143828810","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":"New perspectives on water chemistry classification of travertine/tufa","authors":"Qunwei Dai ,&nbsp;Ting Zhang ,&nbsp;Dejun An ,&nbsp;Jingwen He ,&nbsp;Jie Cui ,&nbsp;Qiongfang Li ,&nbsp;Ronglin Xu ,&nbsp;Faqin Dong ,&nbsp;Zheng Dang ,&nbsp;Qianxi Song","doi":"10.1016/j.apgeochem.2025.106386","DOIUrl":"10.1016/j.apgeochem.2025.106386","url":null,"abstract":"<div><div>If travertine/tufa is a solidified carrier of information records, karst water is the most important transport carrier of such information. In this study, we investigate the water chemistry of partial travertine/tufa around the world. Based on the better linear relationship between Ca²⁺ and HCO₃⁻, the classification view of Ca²⁺-biased and HCO₃⁻-biased types is proposed. Ca²⁺-biased is defined as a high Ca²⁺ concentration compared to the theoretical value of the chemical formula for Ca(HCO₃)₂, while HCO₃⁻-biased is defined as a high HCO₃⁻ concentration compared to the theoretical value of the chemical formula for Ca(HCO₃)₂. By comparing the concentrations of Ca²⁺ and HCO₃⁻ in hot and cold spring travertine/tufa around the world, the relationship between Ca²⁺-biased and HCO₃⁻-biased type is described, providing reference for the classification research of travertine/tufa.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"184 ","pages":"Article 106386"},"PeriodicalIF":3.1,"publicationDate":"2025-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143799875","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":"Combining sequential Gaussian co-simulation and Monte Carlo dropout-based deep learning models for geochemical anomaly detection and uncertainty assessment","authors":"Dazheng Huang ,&nbsp;Renguang Zuo ,&nbsp;Jian Wang ,&nbsp;Raimon Tolosana-Delgado","doi":"10.1016/j.apgeochem.2025.106385","DOIUrl":"10.1016/j.apgeochem.2025.106385","url":null,"abstract":"<div><div>Geochemical anomaly detection is crucial for guiding mineral exploration toward prospective mineral deposits. However, this task is inherently challenging due to uncertainties arising from sparse sampling, spatial variability of geochemical patterns, model limitations. To evaluate the uncertainties associated with spatial variability and model limitations, this study proposes an innovative approach that combines sequential Gaussian co-simulation (SGCS) with Monte Carlo (MC) Dropout-based Convolutional Neural Networks (CNNs) for geochemical anomaly detection and uncertainty quantification. The SGCS method generates multiple realizations of geochemical data, facilitating the quantification of uncertainty in geochemical patterns by considering potential distributions at unsampled locations. These realizations are utilized to augment the training dataset for CNNs, thereby enhancing the model's robustness in anomaly detection. The MC Dropout technique is integrated into the CNN model to evaluate prediction uncertainties, providing critical insights for decision-making under uncertainty. The proposed methodology was applied to the northwestern part of Sichuan Province, China, a region known for gold mineralization. Results indicate that all known gold deposits fall within areas where the anomaly probability exceeds 0.843. By integrating predicted probabilities with associated uncertainties, the spatial distribution of a confidence index is derived, offering a structured guide for subsequent exploration. This integrated framework enhances anomaly detection accuracy and provides robust uncertainty estimates, ultimately enabling more efficient and informed exploration strategies in high-uncertainty environments.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"184 ","pages":"Article 106385"},"PeriodicalIF":3.1,"publicationDate":"2025-04-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143799874","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":"Contrasting effects of ecological restoration and sewage input on the carbonate system variability in an urban river on the Loess Plateau","authors":"Jiajia Dang ,&nbsp;Hong Yang ,&nbsp;Yunxiao Li ,&nbsp;Yunxiu Ma ,&nbsp;Xiao Wang ,&nbsp;Xiao Huang ,&nbsp;Fenwu Liu","doi":"10.1016/j.apgeochem.2025.106382","DOIUrl":"10.1016/j.apgeochem.2025.106382","url":null,"abstract":"<div><div>Intensive human disturbances have led to complex internal variations in the riverine CO₂ system, especially in the urbanized rivers in semi-arid areas. This study examines the factors controlling carbonate system in a river draining an urban ecological restoration area on the Loess Plateau, North China, where riverine dissolved inorganic carbon (DIC) and CO₂ partial pressure (<em>p</em>CO₂) exhibited pronounced variations influenced by land use changes. The most notable changes included a decrease in DIC (24.0 mg L⁻¹) and <em>p</em>CO₂ (280 μatm) in the urban restored area with damming, driven by strong aquatic photosynthesis, and a sharp increase in DIC (55.7 mg L⁻¹) and <em>p</em>CO₂ (6,222 μatm) in the urban downstream, attributed to sewage input. In contrast, in the upstream of the urban restored area, DIC (33.8 mg L⁻¹) and <em>p</em>CO₂ (723 μatm) were mainly controlled by carbonate weathering. Overall, this river acted as a strong atmospheric CO₂ source, with an average CO₂ emission of 450.1 mmol m⁻² d⁻¹, slightly higher than the global riverine average (359.4 mmol m⁻² d⁻¹), and exhibited pronounced spatial variability. A CO₂ sink (−11.2 mmol m⁻² d⁻¹) developed in the urban restoration area, whereas sewage input at urban downstream transformed the river into a strong CO₂ source (1,668.5 mmol m⁻² d⁻¹), highlighting the impact of anthropogenic perturbations on riverine CO₂ source - sink dynamics. Therefore, enhancing urban ecological restoration while effectively reducing CO₂ emission from sewage is crucial for achieving CO₂ neutrality in urban rivers, particularly in arid and semi-arid climates.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"184 ","pages":"Article 106382"},"PeriodicalIF":3.1,"publicationDate":"2025-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143785944","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}