Applied Geochemistry最新文献

{"title":"Transference of potentially toxic elements from soils to plants in a derelict Pb–Zn mining area (San Quintín mine, South-Central Spain)","authors":"José Ignacio Barquero ,&nbsp;Jesús Peco ,&nbsp;Jaime Villena ,&nbsp;Juan A. Campos ,&nbsp;José A. Amorós ,&nbsp;José María Esbrí ,&nbsp;Francisco J. García-Navarro ,&nbsp;Marta María Moreno ,&nbsp;Pablo Higueras","doi":"10.1016/j.apgeochem.2025.106637","DOIUrl":"10.1016/j.apgeochem.2025.106637","url":null,"abstract":"<div><h3>Background and aims</h3><div>Abandoned mining areas represent critical environmental pollution hotspots due to the persistence of waste materials enriched in potentially toxic elements (PTEs). This study evaluates the transfer of PTEs from contaminated soils to six plant species in the vicinity of the San Quintín Pb–Zn mine (Ciudad Real, Spain), a site impacted by over a century of mining activity.</div></div><div><h3>Methods</h3><div>The studied species include the tree <em>Quercus ilex</em>, the shrubs <em>Retama sphaerocarpa</em> and <em>Scrophularia canina</em>, and the annual herbaceous species <em>Spergularia rubra</em>, <em>Rumex bucephalophorus</em>, and <em>Hirschfeldia incana</em>. Soil and plant tissue samples were analysed using X-ray fluorescence and atomic absorption spectrometry to determine concentrations of Zn, Pb, Hg, Cu, and other PTEs.</div></div><div><h3>Results</h3><div>Results revealed a high heterogeneity in the bioaccumulation of elements such as Zn, Pb, Hg, and Cu among the studied species, with <em>Spergularia rubra</em> and <em>Rumex bucephalophorus</em> emerging as effective bioindicators of soil contamination. The presence of acid mine drainage (AMD) significantly reduced soil pH (average ≈ 5.7), enhancing PTE solubility (e.g., Zn²⁺ release) and facilitating their uptake by plants (Bravo et al., 2017). Specific correlations between soil and plant concentrations were identified, and atmospheric uptake was found to significantly influence Hg accumulation in plant tissues.</div></div><div><h3>Conclusions</h3><div>This study revealed high PTE contamination and spatial heterogeneity in the San Quintín mining area, with concentration ranges (mg kg⁻¹) of 13–806 for Sb, 70–57,270 for Pb, 68–48,460 for Zn, 18–1680 for Cu, and 3–1920 for Hg, as the most significant elements. Species such as <em>Spergularia rubra</em> and <em>Rumex bucephalophorus</em> exhibited strong metal accumulation, with average concentrations (mg kg⁻¹) of 1460 and 552 for Pb, 1232 and 927 for Zn, 36 and 22 for Cu, and 28 and 9 for Hg, respectively, and the average Pb BAC for <em>S. rubra</em> of 0.15, significantly higher than that of other species. These results indicate the potential of these two species for bioindication and phytoremediation. Furthermore, Hg accumulation in <em>S. rubra</em> follows a logarithmic trend (R² = 0.98), confirming that atmospheric uptake by leaves supposes an important contribution to bioaccumulation of the element in plants. These results indicate the potential of both species for bioindication and phytoremediation. Mercury uptake was influenced not only by the edaphic compartment but also by atmospheric deposition and plant foliar traits. Overall, these findings provide a better understanding of PTE dynamics within the soil–plant system and support phytoremediation strategies in degraded mining environments.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"196 ","pages":"Article 106637"},"PeriodicalIF":3.4,"publicationDate":"2025-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145681776","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 insights on the Pb isotopic compositions of drinking water lead pipes in the United States","authors":"George D. Kamenov ,&nbsp;Sean Scott","doi":"10.1016/j.apgeochem.2025.106639","DOIUrl":"10.1016/j.apgeochem.2025.106639","url":null,"abstract":"<div><div>Compilation of high-precision Pb isotope data for Pb pipes can be used to identify human exposure to Pb from lead service lines (LSLs) in the USA. Furthermore, as the Pb used in LSLs was most likely obtained from the same ore deposits as lead used in other objects and materials, the Pb pipe data should provide information about the overall isotopic composition of the U.S. industrial Pb. This work presents new MC-ICP-MS Pb isotope data for 50 Pb pipes, all harvested from the state of Wisconsin. The new data show virtually identical isotopic compositions as the previously published MC-ICP-MS data for USA Pb pipes, indicating that most likely no specific geographical variations can be expected in LSLs Pb isotopes in the USA. Furthermore, the Pb pipe isotope data encompass almost the whole isotope range observed in major domestic and international Pb ore deposits. Therefore, the Pb pipe data should be representative of the Pb isotope range of industrial Pb in the USA. The compiled data reveal the existence of two major Pb isotope clusters. Cluster I is composed of lead obtained from various Pb deposits, including imported lead. Cluster II is composed exclusively of domestic lead obtained from the Mississippi Valley Type ore deposits, and potentially is unique to USA industrial Pb isotope signal. Comparison of the Pb pipe data to USA MC-ICP-MS human blood Pb reveals that most individuals, not exposed to Pb from LSLs, do not fall within the two isotope clusters. Therefore, the identified clusters, in addition to the overall Pb isotope linear trend, can potentially be used in large-scale epidemiological studies to decipher if human Pb exposure in a given region is from LSLs or other sources.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"196 ","pages":"Article 106639"},"PeriodicalIF":3.4,"publicationDate":"2025-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145616754","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":"Modes of occurrence of critical elements in coals from the Guanbanwusu mine, Inner Mongolia, China: A novel stratigraphy-constrained sliding-window correlation approach","authors":"Wei Zhu ,&nbsp;Wei Liu ,&nbsp;Na Xu ,&nbsp;Robert B. Finkelman","doi":"10.1016/j.apgeochem.2025.106638","DOIUrl":"10.1016/j.apgeochem.2025.106638","url":null,"abstract":"<div><div>Critical metals such as rare earth elements and yttrium (REY), lithium, gallium, and germanium are essential to modern technologies, but face increasing supply uncertainties. Numerous studies have shown that coal is a promising alternative source for these critical metals. Understanding modes of occurrence of these elements is critical for efficient recovery from coal and its by-products. Traditional statistical analyses, performed on bulk mine datasets, overlook stratigraphic variability, limiting insight into elemental associations. To address this limitation, a sliding-window correlation analysis combined with stratigraphically-constrained Synthetic Minority Over-Sampling Technique was applied to investigate the modes of occurrence of critical elements in coal from the Guanbanwusu mine, Inner Mongolia, China, with specific consideration of vertical stratigraphy. The results reveal significant vertical heterogeneity in modes of occurrence of elements. Lithium exhibits strong correlations with kaolinite and chlorite across most coal benches but shows localized associations with inertinite in the lower part (benches G18-G12 and G8-G1). Gallium and germanium are primarily hosted in goyazite, with variable associations with boehmite, chlorite, and kaolinite. Rare earth elements and yttrium predominantly occur in goyazite, with affinity varying vertically: in upper benches, goyazite shows a stronger affinity for light REY, whereas in lower benches, it is enriched in both light REY and middle REY. In contrast, inertinite exhibits an opposite REY affinity compared to goyazite and chlorite. These trends demonstrate that the modes of occurrence of critical elements are not uniform throughout coal benches but are influenced by localized geochemical conditions and mineralogical variations.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"196 ","pages":"Article 106638"},"PeriodicalIF":3.4,"publicationDate":"2025-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145616824","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":"Dynamics of phosphorus pools in drainage ditch sediments within an agricultural catchment","authors":"Christiane Nagel,&nbsp;Harald Neidhardt,&nbsp;Yvonne Oelmann","doi":"10.1016/j.apgeochem.2025.106633","DOIUrl":"10.1016/j.apgeochem.2025.106633","url":null,"abstract":"<div><div>Hydrological dynamics in drainage ditch sediments may impact phosphorus (P) retention and its potential (re-)release to connected waters. We aimed at understanding the fate of P in drainage ditch sediments under dynamic environmental conditions (i.e., drying-rewetting cycles) by examining P pool transformations through an isotopic labelling and incubation experiment. Fresh sediment samples were labeled with ¹⁸O-enriched inorganic P (P_i), followed by a 24-week incubation under different environmental conditions. The sediment material was incubated at three different hydrological regimes, short-pulsed logged (weekly cycles drying-rewetting), long-pulsed logged (biweekly cycles drying-rewetting), and permanently water-logged (consistently water saturated), and two different temperatures (20 °C and 5 °C). Samples were taken at specific times (24 h after labelling, early phase, intermediate phase, late phase). A five-step sequential extraction scheme was combined with δ¹⁸O analysis of P_i (δ¹⁸OP_i) to follow changes in the operationally defined P pools. First, few P pools showed significant changes, but time-resolved results revealed a dynamic interplay between redox conditions, microbial activity and P dynamics. A subsequent decline in microbial P concentrations along with decreasing alkalinity suggested cell death and reduced microbial activity, likely caused by hydrological stress. However, extracellular acid phosphatase activity remained stable. This suggests that while microbial populations were affected, their enzymatic functions persisted, revealing microbial dynamics and stress responses under drying-rewetting conditions. The δ¹⁸O_Pi values in surface-adsorbed pools retained traces of the original P_i label after 24 weeks, allowing tracking of long-term P transformations and distinguishing biological and geochemical reactions. Our results further reflected dynamic transformations of P_i into organic P and vice-versa, which was largely influenced by the hydrological regime and raised the re-mobilization potential of P_i in the long term. This relationship should be integrated into management strategies aimed at mitigating P losses from agricultural catchments, particularly under changing climatic conditions. Future studies should consider pronounced dynamics within P pools that can only be observed through close temporal monitoring, which may not be evident in simple before-and-after comparisons.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"196 ","pages":"Article 106633"},"PeriodicalIF":3.4,"publicationDate":"2025-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145570968","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 characterization and potential impact of coal mine drainage on river water quality at selected coal mines in the Livingstonia Coalfield, Malawi","authors":"Amidu A. Makwinja ,&nbsp;Frances Chikanda ,&nbsp;George J. Maneya ,&nbsp;Ryosuke Kikuchi ,&nbsp;Walubita Mufalo ,&nbsp;Akizumi Ishida ,&nbsp;Tsubasa Otake","doi":"10.1016/j.apgeochem.2025.106636","DOIUrl":"10.1016/j.apgeochem.2025.106636","url":null,"abstract":"<div><div>Coal mining can have significant environmental impacts caused by acid mine drainage (AMD). To further our understanding of the environmental impacts of coal mining, a study was conducted in the Livingstonia Coalfield at the Kaziwiziwi and Mchenga coal mines in Malawi. Mine drainage, river water, and rock samples were analyzed to determine their geochemical characteristics and assess potential environmental impacts. Results of onsite measurements and chemical analyses showed that mine drainage at both sites is moderately acidic to neutral (pH = 4.46–7.02) with Fe²⁺ and SO₄²⁻ concentrations of 0.30–3.75 and 92.7–593 ppm, respectively. The presence of Fe and SO₄ ions is indicative of FeS₂ oxidation, which is responsible for AMD. At Kaziwiziwi, AMD was identified at the tailings pond, whereas at Mchenga it occurs in an abandoned underground mine. The underground drainage from the Kaziwiziwi active mine has high concentrations of Ca²⁺, Mg²⁺, and HCO₃⁻, indicating the natural neutralization of AMD by mixing with alkaline groundwater. River water has a circumneutral pH and low trace element concentrations (&lt;1 ppm), suggesting minimal AMD. However, the rock samples, particularly mudstone, have acid-generating potential and are a long-term AMD risk. Stable S isotopic analysis indicates that sulfate ions in the AMD are derived from the mudstone, suggesting this rock type is a major source of AMD. Geochemical mixing modeling predicts that fluctuations in river water pH and increased concentrations of dissolved metals (e.g., Mn) will occur when mixed with AMD, thereby highlighting the need for monitoring and mitigation strategies.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"196 ","pages":"Article 106636"},"PeriodicalIF":3.4,"publicationDate":"2025-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145616755","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 geochemical gene of pollution risk (PRG01) for assessing heavy metal pollution based on the relative relationship between elements","authors":"Jiaxin Huang ,&nbsp;Shengchao Xu ,&nbsp;Ningqiang Liu ,&nbsp;Taotao Yan ,&nbsp;Qingjie Gong","doi":"10.1016/j.apgeochem.2025.106634","DOIUrl":"10.1016/j.apgeochem.2025.106634","url":null,"abstract":"<div><div>Traditional assessments of heavy metal pollution in soils are often carried out on pollution indices and national standards. However, these methods focus on only elemental concentrations, without considering the relative relationship among elements. Here, we propose a geochemical gene of pollution risk (PRG01) and its risk similarity (<em>R</em>_Risk), which are based on the relative relationship between concentrations of heavy metals (Hg, Pb, Cd, Cr, and As) and their contrast elements (Ti, La, Zr, Th, U, and Nb). Through risk similarity, the pollution risk of heavy metals of samples can be classified into six levels, including the safety level (<em>R</em>_Risk&lt;20 %) and the risk level 1 to 5 (corresponding <em>R</em>_Risk values range from 20 % to 100 %). The geochemical gene of PRG01 and its risk similarity were applied in the Dashanbao area of Yunnan province of China and compared with the national standard GB15618-2018 on the pollution risk assessment of heavy metals in agricultural soils. The results indicate that samples with <em>R</em>_Risk&lt;20 % (or in safety level) belong to the non-intervention level (background or screening levels), while samples with <em>R</em>_Risk≥40 % are at the non-background level (screening or intervention levels). Therefore, the PRG01 technique can be used as a novel approach and its risk similarity can be viewed as an integrated index for assessing the pollution risk of heavy metals (i.e., Hg, Pb, Cd, Cr, and As) in agricultural soils. The assessment index of risk similarity of PRG01 can not only circumvent the limitation of a one-size-fits-all approach but also compensate for the limitation of GB15618-2018 in assessing soil samples when agricultural land use type and pH data are missing.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"195 ","pages":"Article 106634"},"PeriodicalIF":3.4,"publicationDate":"2025-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145577394","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":"Unraveling stress-mediated fluid-fault interactions in 2021–2022 seismic sequence: Insights from unsupervised machine learning and multiparametric hydrochemical anomalies in Xianshuihe fault zone","authors":"Yucong Yan ,&nbsp;Zheming Shi ,&nbsp;Xiaocheng Zhou ,&nbsp;Guangcai Wang ,&nbsp;Zuochen Zhang ,&nbsp;Yunfei Bai ,&nbsp;Zhaojun Zeng ,&nbsp;Bingyu Yao ,&nbsp;Yuwen Wang ,&nbsp;Miao He ,&nbsp;Jiao Tian ,&nbsp;Ruibin Li ,&nbsp;Han Yan","doi":"10.1016/j.apgeochem.2025.106635","DOIUrl":"10.1016/j.apgeochem.2025.106635","url":null,"abstract":"<div><div>Earthquake-related hydrochemical changes in thermal springs have been widely observed, yet the temporal dynamics and controlling mechanisms of pre- and post-seismic hydrochemical changes remains poorly constrained. By employing unsupervised machine learning (SOM-KM), this study investigates earthquake-induced changes of major elements, trace elements, and hydrogen-oxygen isotopes by high-frequency monitoring data in two thermal springs (XXX and LTG) along the Xianshuihe fault zone during the 2021–2022 Ms ≥ 6.0 earthquake sequence. The result shows that: the XXX spring (Moxi segment) exhibited consistent co-seismic dilution of major ions (Na⁺, K⁺, Cl⁻, HCO₃⁻) and trace elements, attributed to shallow fracture opening under low normal stress (200–400 MPa), thereby facilitating meteoric water recharge (81–89 % mixing ratio). Conversely, the LTG spring (Kangding segment) showed enrichment of deep-sourced constituents of pre-seismic major elements (Na⁺, K⁺, Cl⁻, HCO₃⁻) surges during the 2021 Luxian <em>M</em>s6.0 earthquake, and post-seismic trace element fluctuation in 2022 Ms ≥ 6.0 earthquake sequence, driven by high stress (400–600 MPa) enhancing deep fracture dilation, fluid ascent, and water-rock interaction (obvious δ¹⁸O drift). Cross-analysis of hydrogeochemical signatures with geological and geophysical evidence demonstrates that earthquake-induced hyrochemical anomalies are governed by (1) regional tectonics stress; (2) fault-segment heterogeneity; (3) fluid pathway reorganization and water-rock interaction dynamics. This work advances the understanding of fault-zone fluid response mechanisms to seismicity and offers novel insights into crustal fluid-tectonic interactions during earthquake cycles.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"196 ","pages":"Article 106635"},"PeriodicalIF":3.4,"publicationDate":"2025-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145570969","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 salinity gradient on sediment microbial communities and the functions of carbon, nitrogen, and sulfur cycling in coastal zone","authors":"Dahai Wang ,&nbsp;Chuanshun Zhi ,&nbsp;Xiaonong Hu ,&nbsp;Zhen Wu ,&nbsp;Wei Song ,&nbsp;Jian Wang ,&nbsp;Xianrui Huang ,&nbsp;Fan Yang ,&nbsp;Yufei Jiao ,&nbsp;Yuxi Li","doi":"10.1016/j.apgeochem.2025.106609","DOIUrl":"10.1016/j.apgeochem.2025.106609","url":null,"abstract":"<div><div>Coastal sediments, located at the terrestrial–marine interfaces and subject to strong salinity gradients, harbor distinct microbial communities that play indispensable roles in sustaining carbon, nitrogen, and sulfur cycling, yet the responses to salinization remain insufficiently understood. This study aims to characterize microbial community structures within coastal sediments by employing high-throughput sequencing of the 16S rRNA gene. Furthermore, we utilized the FAPROTAX and PICRUSt2 prediction tools to elucidate microbial functions and biogeochemical cycling processes in these sediment ecosystems. The results revealed that increasing salinity significantly increased microbial α-diversity and promoted the expansion of salt-tolerant microbial populations. The salinity-driven increase in microbial network complexity was accompanied by more pronounced competitive interactions. Salinity variations also significantly altered the microbial functions associated with carbon, nitrogen, and sulfur cycling in the sediments. In low-salinity environments, the ability to decompose complex carbon sources was higher, while in high-salinity environments, microbial communities relied more on chitin degradation, starch degradation, and reductive acetogenesis to cope with the high-salinity, low-oxygen conditions. In the nitrogen cycle, mild salinization promoted denitrification, but in the later stages of salinization, high salinity suppressed denitrification, while nitrogen fixation was enhanced in high-salinity environments. The sulfur cycle, both sulfur oxidation and reduction processes were active in medium-salinity sediments, whereas sulfur oxidation was more pronounced and sulfur reduction was diminished in high-salinity sediments, particularly sulfide oxidation and thiosulfate oxidation were enhanced, while dissimilatory sulfate reduction was weakened. This study reveals the effects of salinity gradients on sediment microbial communities and their functions, providing theoretical support for future ecological restoration and environmental management.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"196 ","pages":"Article 106609"},"PeriodicalIF":3.4,"publicationDate":"2025-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145555195","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":"Strontium isotopes and Rb/Sr tracers in surface soils for locating subsurface lithium pegmatites","authors":"Grace A. Hall ,&nbsp;Gordon D.Z. Williams ,&nbsp;Mona-Liza C. Sirbescu ,&nbsp;P. Louis Lu ,&nbsp;Gary S. Dwyer ,&nbsp;Daniel D. Richter ,&nbsp;Avner Vengosh","doi":"10.1016/j.apgeochem.2025.106631","DOIUrl":"10.1016/j.apgeochem.2025.106631","url":null,"abstract":"<div><div>Lithium-cesium-tantalum (LCT) pegmatites are a major source of global Li production. They typically occur as dike swarms intruded into metamorphic country rocks. The subsurface locations of these dikes can be difficult to identify from the surface. One common approach is to investigate geochemical anomalies in overlying soils and use these as indicators for the occurrence of subsurface pegmatite dikes. However, even with these methods, economically valuable pegmatites can be difficult to identify, and additional techniques can be beneficial for optimizing geological exploration. Here we present a new methodology for detecting subsurface pegmatites through the analysis of Rb/Sr and strontium isotope (⁸⁷Sr/⁸⁶Sr) variations in relatively shallow soils overlying LCT pegmatites. During their formation, pegmatites become enriched in Rb and depleted in Sr, resulting in distinctly high Rb/Sr ratios (typically ≫10), and with time, the decay of ⁸⁷Rb leads to high ⁸⁷Sr/⁸⁶Sr ratios (typically ≫1.0) far exceeding those of common regional host rocks (typically with Rb/Sr &lt; 10 and ⁸⁷Sr/⁸⁶Sr &lt; ∼0.75). Since soils primarily inherit the ⁸⁷Sr/⁸⁶Sr values of their underlying parent rocks, we propose using these distinctive geochemical fingerprints in site-specific soil geochemical surveys to detect subsurface LCT pegmatites. We demonstrate the potential and utility of this methodology using surface soils around and overlying buried LCT pegmatites in the Late Paleozoic Tin Spodumene Belt in North Carolina and the Proterozoic Animikie Red Ace in Wisconsin, USA. Soils directly overlying the LCT pegmatites inherit distinctly elevated Rb/Sr (∼10–120) and ⁸⁷Sr/⁸⁶Sr (∼1.0–6.8) ratios compared to background soils away from the buried LCT pegmatites (⁸⁷Sr/⁸⁶Sr ∼0.74–0.77, Rb/Sr ∼0.76–3.9), which can be used to identify and reconstruct the location of subsurface LCT pegmatite dikes. The common and uniquely elevated Rb/Sr and ⁸⁷Sr/⁸⁶Sr signatures of global pegmatites suggest that this method can be widely and globally applied to soils derived from LCT pegmatites.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"195 ","pages":"Article 106631"},"PeriodicalIF":3.4,"publicationDate":"2025-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145577392","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 cadmium isotope compositions in sediments from the eastern and western new Britain Trench: Implications for source tracing and marine geochemical cycling","authors":"Qiang Dong ,&nbsp;Cailing Xiao ,&nbsp;Yong Liang ,&nbsp;Jingqian Xie ,&nbsp;Min Luo ,&nbsp;Yanwei Liu ,&nbsp;Yingying Guo ,&nbsp;Yingming Li ,&nbsp;Yongguang Yin ,&nbsp;Yong Cai ,&nbsp;Guibin Jiang","doi":"10.1016/j.apgeochem.2025.106632","DOIUrl":"10.1016/j.apgeochem.2025.106632","url":null,"abstract":"<div><div>Trench sediments are recognized as a major sink in the marine cadmium (Cd) budget, however, the sources and biogeochemical cycling of Cd in hadal environments remain poorly constrained. This study investigated Cd concentrations and isotope compositions (δ^114/110Cd) in surface sediments (1553–8931 m water depth) from the western and eastern New Britain Trench. Cd concentrations ranged from 105 to 245 μg kg⁻¹, with δ^114/110Cd from −0.26 ‰ to −1.34 ‰, significantly lighter than deep seawater. Isotope tracing reveals that detrital Cd (in the crystalline mineral matrix) accounts for 34–84 % in the western and 64–87 % in the eastern transect. The δ^114/110Cd_non-detrital in shallow sediments differed markedly between western (−0.39 ‰) and eastern (−2.18 ‰) trenches, suggesting distinct sources. Terrigenous inputs, relatively enriched heavy Cd isotopes, dominate in the west, while biogenic particles sinking are likely dominant source in the east. Sedimentary δ^114/110Cd increased in the eastern transect with depth due to stepwise scavenging of light isotopes, whereas in the western transect it first decreased and then increased, reflecting variations in sediment components and redox conditions. These findings underscore the combined effects of source heterogeneity and depositional processes on Cd isotopes composition in trench sediments, offering new insights into deep-ocean metal cycling.</div></div>","PeriodicalId":8064,"journal":{"name":"Applied Geochemistry","volume":"195 ","pages":"Article 106632"},"PeriodicalIF":3.4,"publicationDate":"2025-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145577442","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}