Applied Geochemistry最新文献

{"title":"Natural kaolin minerals with varying iron contents reduced cattle's enteric methane generation in vitro","authors":"Md. Rashidul Islam ,&nbsp;Ravi Naidu ,&nbsp;Bhabananda Biswas","doi":"10.1016/j.apgeochem.2025.106459","DOIUrl":"10.1016/j.apgeochem.2025.106459","url":null,"abstract":"<div><div>Kaolin, a dominant mineral group in geophagic soil, often contains iron impurities that incur purification costs. Valorizing kaolin for livestock applications like ruminant methane (CH₄) suppression without purification is promising but not well studied. This study used two kaolin clay samples collected from a Western Australia deposit, and tested their inclusion in a basal diet for CH₄ inhibition in an <em>in vitro</em> animal model using viable cattle rumen fluid and paunch. Physicochemical characterization showed that one clay sample (Kao) had kaolinite as the dominant mineral species and a trace of halloysite, while another one had additional minerals and impurities such as iron oxides and illite/mica (KaoFe). Regardless of the CH₄ produced by the basal diet, an approximately 5 % inclusion of clays significantly reduced enteric CH_4, with reductions of 23 % (Kao) and 37 % (KaoFe) compared to the control. On average, the <em>in vitro</em> digestibility (IVD), coefficient of fermentation efficiency (CFE), microbial crude protein (mCP), and ammonia nitrogen (NH₃–N) were 64 %, 77 %, 144 g/kg DM, and 21 g/kg DM, respectively. These results showed no significant differences between clay-treated and control groups, which indicates the clay's non-toxic nature in the rumen. Biochemical and physicochemical parameters and their correlations suggest that clay inclusion in the basal diet increased hydrogen sinkers, such as propionic acid and CH₄ inhibitory ions, such as Al³⁺, Si⁴⁺, Fe²⁺/Fe³⁺, and K⁺. And the inclusion of the KaoFe sample contributed to more of these. Given that the cattle naturally ingest soil minerals through geophagy with good palatability, this study emphasizes the potential valorization of natural kaolin clays as feed supplements. It advances a cost-effective and biocompatible feed additive for rumen CH₄ abatement without adversely affecting the digestive system.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"189 ","pages":"Article 106459"},"PeriodicalIF":3.1,"publicationDate":"2025-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144203181","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":"Precise U–Pb chronology of tooth enamels of index fossils of Miocene fauna","authors":"Pu Zhang ,&nbsp;Yangfan Li ,&nbsp;Guoqi Liu ,&nbsp;Zhe Zhang","doi":"10.1016/j.apgeochem.2025.106457","DOIUrl":"10.1016/j.apgeochem.2025.106457","url":null,"abstract":"<div><div>Five fossil beds containing fossil specimens of <em>Hipparion chiai,</em> which is the most widespread index fossil in Late Miocene strata in northern China, were identified. The biological apatite (carbonated hydroxyapatite) in the teeth fossils of <em>Hipparion chiai</em> has a high μ value (initial ²³⁸U/²⁰⁴Pb_i) and limited Th content. The fossilized tooth enamels remain relatively unchanged due to their resistance to diagenetic alterations. Here, for the first time, we precisely dated six fossil teeth of <em>Hipparion chiai</em> from the Wangdafuliang section in Fugu, Shaanxi Province, using <strong>the</strong> LA-ICP-MS U–Pb geochronology method. The U–Pb dates obtained from the six fossil teeth of <em>Hipparion chiai</em> range from 6.87 ± 0.13 Ma to 7.71 ± 0.39 Ma (2 s), with an average of 7.26 Ma. <strong>The a</strong>ges of the tooth enamels of a <em>Samotherium</em> sp. and a <em>Rhinocerotidae</em> (genus and species unidentified) are consistent with the ages of the tooth enamels of the <em>Hipparion chiai</em>. The analytical method developed for this study provides a new benchmark for dating Neogene fossils.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"189 ","pages":"Article 106457"},"PeriodicalIF":3.1,"publicationDate":"2025-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144166203","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":"Comparing open versus closed system weathering experiments using lithium isotopes","authors":"Philip A.E. Pogge von Strandmann ,&nbsp;Xiaoqing He ,&nbsp;Ying Zhou ,&nbsp;David J. Wilson","doi":"10.1016/j.apgeochem.2025.106458","DOIUrl":"10.1016/j.apgeochem.2025.106458","url":null,"abstract":"<div><div>Chemical weathering of silicate rocks represents a critical part of the carbon cycle, and also a potential method for the artificial drawdown of atmospheric CO₂ (“enhanced weathering”). However, weathering and particularly the resulting secondary minerals (especially clays) have proven hard to measure and quantify. Here we use lithium isotopes to examine and compare two different types of laboratory weathering experiments, using the same initial water and rock, in order to determine their similarities and differences. Specifically, we compare “open system” experiments, where the reacting water drips through the rock powder, with “closed system” experiments, where the reacting water and rock are in contact in a closed beaker. The results (elemental ratios, mobility calculations, saturation indices) suggest that closed experiments, with their longer water-rock interactions times, exhibit more secondary minerals formation. This finding is confirmed by their higher “equilibrium” solution δ⁷Li values (δ⁷Li = 35.7 versus 29.5 ‰, respectively). The determination of their observed fractionation factors (α = 0.983 ± 0.004 and 0.977 ± 0.003 for the open and closed experiments, respectively) and partition coefficients between water and secondary minerals yields a test case, to determine whether the amount of clays that form during weathering can be calculated solely from Li isotope ratios, giving values similar to the amount of basalt dissolved. Based on potassium concentration (here the most mobile element), 1.9–3.2 g of rock was dissolved. Based on the Li isotopes, 1.6–2.0 g of clay was precipitated during the month-long experiment. This result agrees with other estimates from isotope systems, which suggest that clay formation is rapid, which in turn has consequences for weathering processes, and especially for the efficiency of enhanced weathering.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"189 ","pages":"Article 106458"},"PeriodicalIF":3.1,"publicationDate":"2025-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144166202","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":"Fugitive dust from exposed tailings at an inactive gold mine in Québec, Canada, using the Pas-DD dust capture method","authors":"E.J. Berryman ,&nbsp;A. Cleaver ,&nbsp;J.P. Coumans ,&nbsp;N.R. Zagrtdenov ,&nbsp;C. Martineau ,&nbsp;N.J. Fenton ,&nbsp;P. Huntsman","doi":"10.1016/j.apgeochem.2025.106449","DOIUrl":"10.1016/j.apgeochem.2025.106449","url":null,"abstract":"&lt;div&gt;&lt;div&gt;Fugitive mine dust (i.e., particulate emissions) is a ubiquitous waste stream at all mine sites, including active, inactive, and abandoned. Although dust emissions can reasonably be expected to diminish after the cessation of mining activities, any waste products left uncovered have the potential to continue to emit dust to the near-mine environment. In this study, we capture and characterize dust using the Pas-DD dustfall method around the inactive gold-mine site of Joutel in the Abitibi-Témiscamingue region of Québec. The site has been inactive for 30 years, during which time the tailings storage area has been left mostly uncovered, with previously unknown amounts of dust entering the near-mine environment. The quantity of dust captured by our samplers was generally low and did not exceed 0.5 mg/dm&lt;sup&gt;2&lt;/sup&gt;day. Areas of the bottom ∼2 mm of the polyurethane foam (PUF) disks used as a sampling substrate in the Pas-DD method partially degraded following deployment for 284–285 days in the field, resulting in a mass loss of up to 0.57 mg/dm&lt;sup&gt;2&lt;/sup&gt;day. The low dust deposition rates and variable amounts of PUF degradation precluded net mass flux of the PUF disks providing meaningful insight into spatial variability of dust deposition. In contrast, element deposition rates and quantitative mineralogy of the dust are not impacted by PUF degradation and were the most useful datasets in this low-dust setting, allowing us to distinguish background environmental dust from local anthropogenic dust sources, including the tailings as well as other activities in the area. The major (average &gt; 5 vol%) minerals in the dust are: muscovite (21 ± 6 vol%), quartz (22 ± 16 vol%), feldspars (18 ± 4 vol%), chlorite (13 ± 3 vol%), and olivine or serpentine (5 ± 3 vol%). All of these minerals except olivine or serpentine were also common in the tailings, in similar abundance except for reduced muscovite (3.9 ± 0.6 vol% muscovite, 27 ± 7 vol% quartz, 19 ± 3 vol% feldspars, 10 ± 5 vol% chlorite). The tailings also had iron (hydr)oxides (21 ± 8 vol%) and sometimes pyrite (14 ± 19 vol%) as major minerals. The minerals that were identified as being derived mainly from the tailings site are iron (hydr)oxides, ankerite, and pyrite whereas olivine or serpentine, amphibole, calcite, and dolomite originate primarily from the background Abitibi Greenstone Belt environment. Dust with the highest proportion of tailings-sourced minerals was captured downwind of the site and decreased in abundance with distance, pointing to wind as the primary control on dust dispersion from the tailings, with other activity in the forest near the site or along the roads producing discreet dust-generating events. The captured dust contained distinctly less Fe and As than the tailings, reflecting the much lower proportion of iron (hydr)oxides and pyrite in the dust compared to the tailings. Differences in the relative proportion of minerals in the dust compared to the tailings reflec","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"189 ","pages":"Article 106449"},"PeriodicalIF":3.1,"publicationDate":"2025-05-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144166106","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":"Rock weathering characteristics and carbon sink in the Liujiang Basin, North China","authors":"Xiangbin Zeng ,&nbsp;Zhaoliang Song ,&nbsp;Zhixue Xing ,&nbsp;Jing Meng ,&nbsp;Xijun Wang ,&nbsp;Shuyan Liu ,&nbsp;Delin Song ,&nbsp;Zimin Li ,&nbsp;Jianwu Li ,&nbsp;Aiquan Shi ,&nbsp;Jiahao Qin ,&nbsp;Changxun Yu ,&nbsp;Tony Vancov ,&nbsp;Yuntao Wu ,&nbsp;Hailong Wang","doi":"10.1016/j.apgeochem.2025.106435","DOIUrl":"10.1016/j.apgeochem.2025.106435","url":null,"abstract":"<div><div>Global greenhouse gas emissions are on the rise, exacerbating warming. Rock weathering significantly influences the carbon cycle and climate. There are differences in the consumption of atmospheric CO₂ during the weathering process of different rocks. The Liujiang Basin, typical strata from various geological periods in North China, holds significant representative importance in assessing rock weathering and carbon sink. In this regard, we collected two sample series during both high-water and low-water periods and assessed the chemical weathering rates based on the chemical and isotopic compositions of the water, as well as a forward modeling strategy which is based on mass balance. The forward modeling analysis illustrated that rock weathering contributed the most to the total cations (81.62 %–97.13 %, with an average of 92.89 %), with carbonate rock weathering contributing the most (23.80 %–77.12 %, with an average of 54.61 %), followed by silicate rock weathering (3.27 %–61.19 %, with an average of 21.17 %) and evaporite dissolution (5.93 %–26.52 %, with an average of 17.11 %). The Sr concentrations in the river water ranged from 0.63 to 21.34 μmol L⁻¹, while Sr isotope ratios (⁸⁷Sr/⁸⁶Sr) had a 101 % variation scale. The δ¹³C values ranged from −14.73 to −7.06 ‰. Quantitative analysis further illustrated that atmospheric precipitation, carbonate, and evaporite inputs collectively accounted for 64.15 % (42.12 %–97.61 %) of total dissolved Sr, while silicate rocks accounted for 35.85 % (2.39 %–57.88 %). Overall, the silicate and carbonate weathering rates in the Liujiang Basin were 6.35 t km⁻²·a⁻¹ and 22.20 t km⁻²·a⁻¹, respectively. The atmospheric CO₂ consumption flux from silicate and carbonate weathering was 2.27 × 10⁵ mol km⁻²·a⁻¹ and 2.56 × 10⁵ mol km⁻²·a⁻¹, respectively. Considering plant biomass management, the carbon sinks of silicate and carbonate rocks in the Liujiang Basin can increase by about 27 % and 4 %. The rock weathering CO₂ consumption flux in the Liujiang Basin matches or exceeds other major Chinese rivers, highlighting the importance of small watersheds in carbon sequestration.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"189 ","pages":"Article 106435"},"PeriodicalIF":3.1,"publicationDate":"2025-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144139002","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":"Dissolved organic matter sources in urban outfall water before and during rainfall, indicated via its fluorescence fingerprinting","authors":"Haojie Yin ,&nbsp;Tao Huang ,&nbsp;Bo Wang ,&nbsp;Yingying Zhang ,&nbsp;Jiawei Hu ,&nbsp;Linlin Zhu ,&nbsp;Kaining Chen","doi":"10.1016/j.apgeochem.2025.106447","DOIUrl":"10.1016/j.apgeochem.2025.106447","url":null,"abstract":"<div><div>Pollution source identification is the key foundation of urban river water quality management. In this study, fluorescence fingerprinting was employed to analyze changes in dissolved organic matter (DOM) sources in urban river outfalls P1–P3 in Hefei City, China, before and during a rainfall event. The water quality of the outfalls varied before and during rainfall, with an apparent dilution in P2 and a combined effect of urban non-point runoff and dilution in P3. The fluorescent components of the DOM in the outfall water were fulvic acid-like substances C1, terrestrial humic-like substances C2, and tryptophan-like substances C3. The dominant C1 in P1 was diluted by rainfall runoff, decreasing the total fluorescence intensity (F_T) of the DOM. The increased F_T and proportion of C1 + C2 in P2 during early rainfall indicated runoff inputs, whereas those in P3 increased and decreased thereafter, suggesting that rainfall led to an influx of domestic sewage. Fluorescence fingerprinting analysis indicated that the DOM in P1 originated primarily from rainwater and domestic wastewater treatment plant (WWTP) effluent. The DOM in P2 originated from domestic WWTP effluent pre-rainfall, rainwater, and domestic WWTP effluent during early rainfall and urban non-point runoff during later rainfall, whereas that in P3 originated from domestic sewage before and during early rainfall and urban non-point runoff during later rainfall. Identifying sources of pollution provides a basis for urban outfall and river water quality management before and during rainfall events.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"189 ","pages":"Article 106447"},"PeriodicalIF":3.1,"publicationDate":"2025-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144154962","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":"Igneous intrusion effect on the geochemistry of Late Miocene Onnagawa mudstone: implication on the atypical hydrocarbon generation of Akita Basin, Japan","authors":"Barry Majeed Hartono,&nbsp;Shun Chiyonobu,&nbsp;Takuto Ando","doi":"10.1016/j.apgeochem.2025.106448","DOIUrl":"10.1016/j.apgeochem.2025.106448","url":null,"abstract":"<div><div>This study investigated the physio-chemical changes in organic matter, from micro-to macromolecular scale, due to rapid heating from igneous intrusion, particularly if intrusion emplacement occurred syn-contemporaneously with the organic matter deposition. The Neogene siliceous mudstone of the Onnagawa Formation in the Akita Basin is a suitable interval for this study, as subvolcanic and volcanic rocks were found within the formation. Hence, eight cutting samples of the formation from the Yabase well were subjected to Rock-Eval pyrolysis analysis, while three samples near the intrusion body and one unintruded sample were then selected for further biomarker analysis. Generally, kerogen, represented by Tmax, and biomarker proxies respond to the extreme thermal stress from intrusion. While the background Tmax is very low in our well (Tmax&lt;430 °C), this parameter is significantly elevated in the intrusion zone, accompanied by an increasing production index (PI) alongside with reduced TOC and hydrogen index (HI). In contrast, slight changes, including reversal trend, in several maturity-related saturate biomarker ratios, such as C₂₃ tricyclic terpanes (TT) βα/αα, C₂₄ tetracyclic terpanes/C₂₃ TT, Ts/(Ts + Tm), C₂₉ and C₃₀ moretanes/hopanes, C₃₁–C₃₅ homohopanes (HH) 22S/(22S + 22R), and C₂₉ steranes 20S/(20S + 20R) were observed near the intrusion proximity. These phenomena are related to three major factors, which are kerogen-related generation, failed isomerization, and thermal degradation. Rapid heating from intrusion is insufficient to exhibit isomerization reaction, while kerogen, which is more thermally resistant, absorbs the heat and generates bitumen, including more immature isomers. Furthermore, this generated bitumen correlates with the produced oils in the area, which also inherit low maturity characteristics. Thus, it becomes evident that igneous intrusion could activate the atypical petroleum system in one basin, despite the source rock being deposited concurrently with or immediately after the intrusion event.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"189 ","pages":"Article 106448"},"PeriodicalIF":3.1,"publicationDate":"2025-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144195068","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 influence of thermo-mineral and seawater on the mineralogy and chemistry of residual smectitic soils from Alentejo, Portugal: a case study","authors":"A. Valente,&nbsp;F. Rocha,&nbsp;S. Andrejkovicová,&nbsp;D. Terroso,&nbsp;C. Sequeira,&nbsp;E. Ferreira da Silva","doi":"10.1016/j.apgeochem.2025.106446","DOIUrl":"10.1016/j.apgeochem.2025.106446","url":null,"abstract":"<div><div>Peloid is a natural product developed during the maturation process between a clay material and water and is used in health and wellness centres due to its mineralogical, physiochemical and biological properties. However, the potential therapeutic value of clays in Portugal has not been fully investigated. Therefore, the main objective of this research is to identify the effects of two mineralized waters: thermo-mineral water (sulphurous and hydroxylated water abundant in chloride ions, sodium and calcium) and seawater, on three residual soils from Alentejo, from a morphological, mineralogical and chemical perspective. The peloids morphology is more homogeneous than the residual soils, and the particle size decreases during the maturation process. Thermo-mineral water enriched the peloids in smectite (58–76 %), while seawater newly formed Na-minerals (decreasing smectite contents to 39–54 %). Smectite is essentially montmorillonite, although there is nontronite and beidelite. The residual soils and peloids have a silicilastic composition (32.23–52.85 %), between 14.22 and 20.53 % of Al₂O₃, and besides smectite, the mineralogical composition is composed of salts (only in seawater peloids), feldspars, iron oxides, carbonates, and quartz. Morphology and mineralogy enhance the influence of waters in peloids properties and suggest that this samples have potential therapeutic value. Furthermore, physical-chemical, rheological, thermal and biological analysis are needed to support these findings.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"188 ","pages":"Article 106446"},"PeriodicalIF":3.1,"publicationDate":"2025-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144131290","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":"Differentiation of groundwater flow patterns in multiple karst systems in a covered karst basin in China through hydrochemistry, stable isotopes, and 222Rn","authors":"Liqiong Wei ,&nbsp;Fang Guo ,&nbsp;Guanghui Jiang ,&nbsp;Fan Liu ,&nbsp;Zhijie Li","doi":"10.1016/j.apgeochem.2025.106436","DOIUrl":"10.1016/j.apgeochem.2025.106436","url":null,"abstract":"<div><div>Groundwater in covered karst basins is abundant, but the thick soil cover and the lack of distinct surface karst features complicate the understanding of subsurface flow. This study integrates physicochemical parameters, stable hydrogen and oxygen isotopes, and the radon isotope (²²²Rn) to characterize groundwater flow within local, intermediate, and regional karst water systems in a covered basin in South China. The aims are to distinguish differences among these systems, examine radon concentration variations at their outlets, and assess the potential of ²²²Rn in identifying groundwater flow characteristics. Groundwater in the regional karst system is characterized by the most extensive water-rock interaction, extended flow paths and residence time, minimal anthropogenic influence, and slow, fracture-dominated flow in the final stages of flow paths. In contrast, local and intermediate karst systems are more responsive to external changes, with rapid conduit flow primarily occurring in their terminal sections. Owing to the short residence time and flow paths, radon is rapidly transported to the discharge points, resulting in higher concentrations in groundwater from local karst systems compared to intermediate and regional systems, which have longer residence time. Similar to hydrochemical and isotopic trends, radon concentrations in local and intermediate systems fluctuate more than in regional systems, suggesting rapid flow in the terminal sections of both. Radon activity can qualitatively identify flow characteristics in karst aquifers. The integration of hydrogeochemical, stable isotopes, and ²²²Rn data provides a comprehensive understanding of flow patterns linked to aquifer structures and insights into radon behavior in karst water systems.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"188 ","pages":"Article 106436"},"PeriodicalIF":3.1,"publicationDate":"2025-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144131287","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":"Distribution and leachability of heavy metals from lead-zinc tailings with different degrees of chemical weathering in the Qinling Mountains","authors":"Shentao Hu ,&nbsp;Xiaohu Xiong ,&nbsp;Xuan Li ,&nbsp;Meixia Wang ,&nbsp;Dongdong Xu ,&nbsp;Weijian Zhou","doi":"10.1016/j.apgeochem.2025.106434","DOIUrl":"10.1016/j.apgeochem.2025.106434","url":null,"abstract":"<div><div>The Qinling Mountains in Shaanxi Province are one of China's most significant ecological reserves, but many lead-zinc tailings have been produced during decades of mining development. The heavy metals in these lead-zinc tailings pose a severe pollution risk to the surrounding areas. However, the vertical distribution, leaching behaviour and ecological risk of heavy metals in these tailings remain unclear. A lead-zinc tailings profile from the southeast foot of the Qinling Mountains was studied. The particle size, chemical composition, mineralogy, micromorphology, Nemerow pollution index and leaching behaviour were analysed. The results showed that the lead-zinc tailings profile had an intermediate chemical weathering layer (depth 0–70 cm) and an incipient chemical weathering layer (depth 70–100 cm). Quartz and muscovite were the main minerals. The intermediate chemical weathering layer was more enriched in Cr and Pb, while the incipient chemical weathering layer was more enriched in Cd and Zn. The final leaching concentrations of Cr, Cd, Zn and Pb in the incipient and intermediate chemical weathering layers after 50 days were very similar, at 0.27–0.36, 0.60–0.81, 6.93–9.03 and 7.81–10.47 mg L⁻¹, respectively. However, the average leaching efficiency was the reverse. Calcite and chemical weathering intensity may have been connected to this. The lead-zinc tailings were highly polluted, with Pb, Zn, Cd and As being the main pollutant elements. In summary, this study provides new insights for controlling heavy metal migration and mitigating environmental hazards in existing lead-zinc tailings ponds in the Qinling Mountains.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"189 ","pages":"Article 106434"},"PeriodicalIF":3.1,"publicationDate":"2025-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144203286","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}