Journal of Geochemical Exploration最新文献

{"title":"Hydrochemical processes and water balance trends based on stable isotopes of typical alpine lakes in the Qinghai-Tibet Plateau","authors":"Changchang Fu ,&nbsp;Xiangquan Li ,&nbsp;Xu Cheng ,&nbsp;Cong Liu ,&nbsp;Zhanxue Bai ,&nbsp;Jinqiu Li","doi":"10.1016/j.gexplo.2024.107663","DOIUrl":"10.1016/j.gexplo.2024.107663","url":null,"abstract":"<div><div>Due to the warming climate, the hydrological cycle of the Qinghai-Tibet Plateau (QTP) is accelerating, leading to continuous growth of alpine lakes. In case of overflow, this can pose significant risks to downstream water quality and resources. However, there is a lack of comprehensive investigations on the chemical composition and water balance of lakes in QTP. This study examines the evolutionary mechanisms of alpine lakes in the Yanhu Lake Basin (YHB) located in central QTP. It investigates stable isotopes (<em>δ</em>¹⁸O and δD), hydrochemistry, and utilizes the isotope balance model to determine the evaporation to inflow (E/I) ratio of lake water. The findings reveal that lake water exhibits a Cl<img>Na hydrochemical type with enrichment in total dissolved solids (TDS), boron (B), and lithium (Li) elements. On the δD- <em>δ</em>¹⁸O plot, lake water falls below the Local Meteoric Water Line (LMWL) towards rightward direction with a slope of 4.75 and an intercept of 11.83, indicating pronounced evaporation characteristics. The presence of more positive isotope signals and ratios among major ions suggests that evaporation processes primarily govern lake water's hydrochemistry. The modeled E/I ratio ranges from 0.19 to 0.65 across YHB, implying a positive lake water balance which contributes to consistent expansion in surface area. This highlights the need for local government to enhance monitoring efforts, closely observe fluctuations in Yanhu Lake's water level, expedite implementation of lake water diversion projects, and conduct comprehensive assessment on their potential impact on local ecological environment.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"270 ","pages":"Article 107663"},"PeriodicalIF":3.4,"publicationDate":"2024-12-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143164548","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Appraising the porphyry Cu fertility using apatite trace elements: A machine learning method","authors":"Qianbin Liang ,&nbsp;Guoxiong Chen ,&nbsp;Lei Luo ,&nbsp;Xiaowen Huang ,&nbsp;Hao Hu","doi":"10.1016/j.gexplo.2024.107664","DOIUrl":"10.1016/j.gexplo.2024.107664","url":null,"abstract":"<div><div>Apatite chemical composition has often been invoked for appraising the magmatic copper (Cu) fertility, because trace elements in apatite hold important clues for tracing magma composition, oxidation states, and crystallization processes. However, low-dimensional Cu fertility discriminants developed on apatite trace elements suffer from significant limitations and uncertainties in practice. Here, machine learning (ML) models including random forests and support vector machines were trained using high-dimensional apatite composition dataset (spanning 20 trace elements) for discriminating ore-bearing magmas from ore-barren magmas. The results suggest that the ML models obtained a higher accuracy (96 %) for identifying the given apatites from ore-bearing samples compared to that of traditional discriminant diagrams (56 %). The feature importance analysis suggests that <em>δ</em>Eu and Sr are the most significant proxy for distinguishing ore-bearing and ore-barren samples when using high-dimensional ML models. In general, apatites from ore-bearing intrusion have higher <em>δ</em>Eu and Sr concentration, lower Pb concentration, and elevated Sr/Y ratio than ore-barren samples. Specifically, the elevated <em>δ</em>Eu and Sr concentration indicate a relatively higher oxidation state and water content in parental magmas, which could have promoted sulfate formation and Cu release and transport. Moreover, the elevated Sr/Y observed in apatite from ore-bearing samples imply the adakite-like composition of the ore-productive magmas, while lower Pb concentration suggests strong fluid participation during magmas evolution. The trained ML model was applied to apatites from the Tampakan district of the Philippines, providing new insights on Cu fertility of pre-, syn- and post-ore intrusions. The general applicability of this model demonstrates that ML-based discriminants developed on mineral trace element data provide new powerful tools for appraising the porphyry Cu fertility.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"270 ","pages":"Article 107664"},"PeriodicalIF":3.4,"publicationDate":"2024-12-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143164549","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Neoproterozoic WSn mineralization in the western Jiangnan Orogen, South China: Insights from the Fanjingshan S-type granites","authors":"Jin-Cheng Luo ,&nbsp;Jiawei Zhang ,&nbsp;Xujie Shu ,&nbsp;Yanwen Tang ,&nbsp;Yaran Dai ,&nbsp;Weipeng Liu ,&nbsp;Xiaocui Chen ,&nbsp;Tingting Zhang","doi":"10.1016/j.gexplo.2024.107660","DOIUrl":"10.1016/j.gexplo.2024.107660","url":null,"abstract":"<div><div>The Jiangnan Orogen boasts abundant Neoproterozoic granitoids alongside locally significant W<img>Sn mineralization in South China. However, the factors governing the relationships between granites and the W<img>Sn mineralization remain elusive. Notably, Neoproterozoic W<img>Sn mineralization locally occurred within the western margin of the Jiangnan Orogen, encompassing important deposits like the Jiumao and Baotan deposits. The W-Sn-bearing tourmaline muscovite (Taoshulin) granite intruded into Neoproterozoic Fanjingshan Group, comprising low-degree metamorphosed sedimentary rocks that locally contain granitic gravel (two-mica granite). These granites in this study have high SiO₂ (73.6–77.4 wt%), Al₂O₃ (12.8–15.1 wt%), Na₂O (3.16–5.25 wt%) and high A/CNK values (1.28–1.47), which display co-variation trends. They have extremely low rare earth element (REE) concentrations (&lt; 35 ppm) and exhibit REE patterns characterized by strong negative Eu anomalies (&lt; 0.28), implying highly fractional crystallization. Zircon and apatite LA-ICP-MS U<img>Pb dating reveal that the emplacement of the Taoshulin tourmaline muscovite granite occurred <em>ca.</em> 830 Ma, similar to the U<img>Pb age (835 ± 7 Ma) of cassiterite, establishing the clear temporal-genetic relationship between granites and W<img>Sn mineralization. The zircon U<img>Pb age of 849 ± 9 Ma and the apatite U<img>Pb age of 852 ± 7 Ma obtained from the two-mica granite likely indicate <em>ca.</em> 850 Ma granitic magmatism event. These two-episode granites exhibit negative ε_Hf(t) values (+0.9 to −8.0), corresponding to two-stage Hf model ages of 1.7 to 2.2 Ga, indicating their derivation from Paleoproterozoic metasedimentary basement rocks. It is noteworthy that the W-Sn-bearing granite has high tetrad effect (TE_1,3 = 1.16–1.24) and very low Nb/Ta ratios (mostly ≤ 4) that may have resulted from magmatic-hydrothermal alteration. Moreover, the <em>ca.</em> 830 Ma W-Sn-bearing granite is characterized by a notable concentration of high F, distinctively negative Eu anomalies, and non-chondritic REE behavior in apatite. Hence, the W<img>Sn mineralization in the Fanjingshan region was probably constrained by various factors, including source materials, magmatic processes and magmatic-hydrothermal processes. Our findings highlight the pivotal role played by Neoproterozoic muscovite tourmaline granites as host for W<img>Sn mineralization in the Fanjingshan region. In summary, this study emphasizes the significance of the <em>ca.</em> 830 Ma highly differentiated S-type granites holding significant potential for the exploration of critical metals such as W, Sn, Nb, and Ta in the western part of the Jiangnan Orogen and in geologically analogous regions across the globe.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"270 ","pages":"Article 107660"},"PeriodicalIF":3.4,"publicationDate":"2024-12-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143164547","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Spatial distributions, potential sources, and ecological risks of heavy metals in stream sediments in Zambia","authors":"Hongwei Sun ,&nbsp;Junping Ren ,&nbsp;Jie Wang ,&nbsp;Jianzhong Yu ,&nbsp;Libo Zuo ,&nbsp;Xingyuan Wu ,&nbsp;Chipilauka Mukofu ,&nbsp;Alphet Phaskani Dokowe ,&nbsp;Shuping Cao ,&nbsp;Xujiang Cheng","doi":"10.1016/j.gexplo.2024.107659","DOIUrl":"10.1016/j.gexplo.2024.107659","url":null,"abstract":"<div><div>The ecological risk assessment and source identification of heavy metals (HMs) are significant for resource utilization and food security. This study aims to assess the spatial distributions, potential sources, and ecological risks of HMs in stream sediments in Zambia. Using 735 samples collected from stream sediments across the country and methods such as inductively coupled plasma mass spectrometry (ICP-MS), atomic fluorescence spectrometry (AFS), and X-ray fluorescence spectrometry (XRFS), this study determined the concentrations of the seven HMs, i.e., arsenic (As), chromium (Cr), copper (Cu), mercury (Hg), nickel (Ni), lead (Pb), and zinc (Zn). The spatial distributions of these HMs were determined using a Geographic Information System (GIS), and their ecological risks were accessed based on the analytical results of their potential sources. Additionally, this study explored the relationships between mining activities and regions with high heavy metal (HM) concentrations based on the statistical analysis of the HM concentrations and geology of the study area. The results indicate the stream sediments in Zambia exhibit average As, Cr, Cu, Hg, Ni, Pb, and Zn concentrations of 1.49 × 10⁻⁶, 19.34 × 10⁻⁶, 12.12 × 10⁻⁶, 12.70 × 10⁻⁹, 7.13 × 10⁻⁶, 12.52 × 10⁻⁶, and 16.30 × 10⁻⁶, respectively. The analytical results of the geoaccumulation index (<em>I</em>_geo) and potential ecological risk index (PERI) reveal the presence of relatively high As and Cu concentrations, especially in Copperbelt and North-Western provinces and areas surrounding Lusaka—the capital of Zambia. The HM contamination in stream sediments in Zambia is primarily caused by Cu and gold (Au) mining. This study exemplifies how to determine potential sources and ecological risks of HMs in stream sediments, holding important implications for nation-scale environmental contamination prevention and land utilization planning.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"270 ","pages":"Article 107659"},"PeriodicalIF":3.4,"publicationDate":"2024-12-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143164046","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Geology of the Nguba Group-hosted Lonshi copper deposit in the Democratic Republic of Congo and exploration implications","authors":"Kevin Igor Azeuda Ndonfack ,&nbsp;Zhiming Yang ,&nbsp;Jinlin Zhang ,&nbsp;Yuling Xie ,&nbsp;Wu Cao","doi":"10.1016/j.gexplo.2024.107661","DOIUrl":"10.1016/j.gexplo.2024.107661","url":null,"abstract":"<div><div>Lonshi is a newly discovered copper deposit located in the southeastern region of the Central African Copperbelt in the Democratic Republic of Congo. The deposit is hosted in the Nguba Group of the Katanga Supergroup. This paper analyzes the lithostratigraphy, controlling structures, ore host rock, and mineralization characteristics of the Lonshi deposit. The lithostratigraphy of the Lonshi area is comprised of the Mwashya sandstone of the Roan Group; conglomerate, dolostone, shale, mudstone, and siltstone of the Nguba Group; and conglomerate, pink dolostone, and siltstone of the Kundelungu Group. Geological structures identified within the mining zone encompass N-S and W-E trending folds, NW-trending fault, E-W sinistral shears, and various fractures and veins. The Lonshi deposit exemplifies a characteristic of hydrothermal stratiform mineralization, comprising two main orebodies situated within the Mwale conglomerate (lower orebody) and the underlying Lonshi dolostone (upper orebody). The ore was deposited during three mineralization stages, wherein the first hydrothermal stratigraphically-controlled stage deposited chalcocite 1, bornite, chalcopyrite, and pyrite. The structurally controlled stage 2 is subdivided into chalcocite 2 and bornite of stage 2a, and chalcopyrite, bornite, and native copper of stage 2b. Supergene alteration defining stage 3 resulted in the deposition of chalcocite 3, malachite, cuprite, azurite, and native copper 2. The gangue minerals associated with copper sulfide minerals consist of ankerite, feldspar, quartz, muscovite/sericite, kaersutite, barite, and illite. The sulfide minerals display zonation both vertically and laterally, transitioning from chalcocite to bornite to chalcopyrite to pyrite±sphalerite. Copper sulfide minerals occur as fine- to coarse-grained disseminations within the Nguba conglomerate andshow a replacement texture. The mineralizing fluids at the Lonshi deposit were likely enriched in Fe, Ca, Mg, Si, S, and Cu, with additional Mg contributed from the ore-hosting dolostone and Co and K from the ore-hosting conglomerate.</div><div>The Nguba Group at the Lonshi copper deposit shows distinct lithologies composed of black- to light-gray conglomerates and dolostone, which provide valuable insights for the discovery of new deposits. The observed mineral zoning, hydrothermal alteration, and multi-stage mineralizing events suggest favorable conditions for copper deposition. Targeting similar stratigraphic settings and alteration signatures in the vicinity of the Lonshi mine and in the Nguba Group could enhance the likelihood of discovering new deposits, particularly in areas exhibiting similar geological characteristics and structural features.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"270 ","pages":"Article 107661"},"PeriodicalIF":3.4,"publicationDate":"2024-12-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143164545","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Delineation of geochemical anomalies through empirical cumulative distribution function for mineral exploration","authors":"Shahed Shahrestani,&nbsp;Ioan Sanislav","doi":"10.1016/j.gexplo.2024.107662","DOIUrl":"10.1016/j.gexplo.2024.107662","url":null,"abstract":"<div><div>In this paper, a statistical outlier detection technique based on empirical cumulative distribution functions (ECOD) is applied to a multivariate geochemical dataset from southeastern Iran, which is known for its porphyry and vein-type copper mineral occurrences. The ECOD method assumes that outlier samples are situated in both the left and right tails of the cumulative distribution functions, and it determines whether the outliers are located in the right or left tails using the concept of skewness. Anomaly maps produced by the ECOD method are compared with those generated by the local outlier factor (LOF) method. Both ECOD and LOF are applied to two subsets, including 4 and 12 trace elements. The anomaly maps are evaluated by comparing the number of delineated known mineral deposits and using ROC curves. The result revealed that LOF was outperformed by ECOD in the delineation of known Cu mineralization and in the identification of zones containing mineralized samples collected during the anomaly checking stage. The ECOD anomaly map is also compared with results from the k-means clustering method, and the superiority of ECOD over k-means clustering is demonstrated. The implementation of ECOD on clr-transformed multivariate geochemical data shows promise but assumes statistical independence among features, often unmet in geochemical exploration. To address this, we transformed clr data into new principal and independent feature spaces using principal component analysis (PCA) and independent component analysis (ICA), enhancing anomaly detection efficiency. ECOD_ICA outperformed ECOD_PCA, successfully classifying all mineralized samples and 15 of 18 Cu mineral occurrences in the highest score class (Q4), as confirmed by ROC analysis. However, the reliance of the ECOD method on univariate tail probabilities limits its ability to detect multivariate anomalies arising from complex inter-element relationships. Strong correlations in geochemical datasets can lead to false positives, necessitating dimension reduction techniques. While PCA and ICA help manage these correlations, they may obscure meaningful signals. The ECOD outlier detection method is also sensitive to the skewness of the dimensions, so a careful feature selection stage is recommended before applying it. The method is less sensitive to the number of dimensions, which enhances its robustness. Additionally, the absence of hyperparameter tuning makes ECOD a reliable and efficient outlier detection method.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"270 ","pages":"Article 107662"},"PeriodicalIF":3.4,"publicationDate":"2024-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143164044","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"The source of lithium in connate fluids: Evidence from the geothermal reservoir at Soultz-sous-Forêts, Upper Rhine Graben, France","authors":"Michèle Jungmann ,&nbsp;Benjamin F. Walter ,&nbsp;Elisabeth Eiche ,&nbsp;R. Johannes Giebel ,&nbsp;Jochen Kolb","doi":"10.1016/j.gexplo.2024.107641","DOIUrl":"10.1016/j.gexplo.2024.107641","url":null,"abstract":"<div><div>Geothermal brines in the Upper Rhine Graben have been used as a spa or for salt production since Roman times. Heat and power are generated in geothermal power plants since 2007. Recently, their elevated Li-content has additionally attracted economic interest. This increased interest is in contrast with our understanding of the geological-hydrothermal evolution. We use petrology, major and trace element mineral chemistry and mass balance calculation from drill cores that intersect granitic geothermal reservoir rocks at Soultz-sous-Forêts between Strasbourg and Karlsruhe to shed light on fluid-rock interaction in a reservoir that is actively used for heat and power generation. The alkali feldspar and the two-mica granite in the reservoir have a typical plagioclase, K-feldspar, quartz, biotite and muscovite assemblage with some accessories of titanite, apatite and zircon. Two hydrothermal alteration events are distinguished: (1) albitization of the feldspars; (2) distal replacement of feldspars by sericite and calcite, of biotite by chlorite and titanite; and proximal to hydrothermal veins replacement of the feldspars by sericite and kaolinite. Event 2 feldspar alteration quantitatively releases Pb and Ba to the fluid, whereas Rb, Cs, Sr and Zn show different behaviour depending on whole-rock and mineral composition. Event 2 biotite-chlorite alteration releases Li, Rb, Cs, Sr, Ba, Zn and Pb to the fluid. Mass balance calculation indicates that Si, Fe, Ca, K, Rb, Sr, Zn and Pb contents of the Soultz-sous-Forêts geothermal brine may be explained by fluid-rock interaction in the reservoir. However, the reservoir rock volume that needs to be leached in order to reach recent brine composition varies by several orders of magnitude between the different elements. Many of the elements may be leached during hydrothermal alteration, however in particular Li and Cs require unrealistic fluid-rock ratios of &gt;1/300. These considerations indicate that Na, Ca, Li, Cs and Ba need an additional external source. Based on this, we propose a model where Middle Triassic bittern brines already enriched in Li, Rb, and Cs reacted with the reservoir rocks during hydrothermal event 2 and subsequently mixed with Jurassic-Cretaceous marine water that dissolved evaporites during downward migration. This agrees with Jurassic-Cretaceous illite ages from various sites in the Black Forest and indicates a complex ∼150 m.y. hydrothermal evolution for the brines. There is likely no single source of Li, and it is likely derived from complex fluid-rock interaction with the sedimentary (evaporite) and, less importantly, the crystalline strata of the Upper Rhine Graben. Critical for Li-resource development is the complex hydrothermal history of connate fluids that interacted with sedimentary strata and the preservation in deep-seated reservoirs.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"270 ","pages":"Article 107641"},"PeriodicalIF":3.4,"publicationDate":"2024-11-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143164045","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Fluoride in geothermal water: Occurrence, origin, migration and environmental impact","authors":"Xuelian Huang ,&nbsp;Shuai Wang ,&nbsp;Sijia Wang ,&nbsp;Zhicai Xiao ,&nbsp;Min Zhang ,&nbsp;Hongyan Zhang ,&nbsp;Shihua Qi","doi":"10.1016/j.gexplo.2024.107640","DOIUrl":"10.1016/j.gexplo.2024.107640","url":null,"abstract":"<div><div>Geothermal water, a vital renewable energy source extensively harnessed for heating and power generation, is marred by a prevalent issue – high fluoride content. The environmental impact of geothermal fluoride has been recognized globally. The natural discharge of geothermal water, coupled with its widespread exploitation, instigates the translocation of geothermal fluoride toward shallow and surface water ecosystems, culminating in escalating fluoride concentrations, thereby posing potential threats to both ecosystems and human health. Nevertheless, despite the pivotal significance of fluoride in geothermal water, a comprehensive understanding of its origins, migratory dynamics, ecological consequences, and ameliorative methodologies remains to be studied. This review provides a comprehensive examination of fluoride's global occurrence and distribution in geothermal waters, emphasizing the contrast between volcanic and non-volcanic geothermal systems. It analyzes the various sources of fluoride in these waters and elucidates the mechanisms driving its mobilization. In volcanic geothermal systems, fluoride primarily derives from magmatic volatiles, while in non-volcanic systems, it mainly results from the dissolution of minerals. Temperature is a key factor influencing fluoride concentration in geothermal waters, with alkaline conditions and low calcium levels contributing to higher fluoride enrichment. The review details how fluoride concentrations change as geothermal fluids migrate from deeper to shallower layers. Based on the enrichment characteristics of fluorides, this paper explores the potential applications of geothermal fluorides. It also examines the environmental impacts of geothermal fluoride, presents various treatment methods, and provides a summary of current research both domestically and internationally, while proposing directions for future studies. This study is instrumental in formulating judicious fluoride management policies and establishing sustainable strategies for the development of geothermal resources.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"270 ","pages":"Article 107640"},"PeriodicalIF":3.4,"publicationDate":"2024-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143164544","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Regional ANN model for estimating missing daily suspended sediment load in complex, heterogeneous catchments","authors":"Mohd Yawar Ali Khan","doi":"10.1016/j.gexplo.2024.107643","DOIUrl":"10.1016/j.gexplo.2024.107643","url":null,"abstract":"<div><div>To reduce the costs associated with monitoring suspended sediment load (SSL) in rivers, creating more cost-effective and easily measurable indirect estimation methodologies that rely on interactions with other variables is necessary. This work introduces a new method to assess the capability of regional models to expand ungauged SSL to gauging locations in a diverse region with little in situ data and complex hydrography. The estimates were derived using discharge (Q) data, utilizing models based on artificial neural network (ANN) feedforward backpropagation (FFBP) techniques for the Ramganga River Basin. This work confirms the practical capacity and utility of ANN for simulating intricate nonlinear dynamics in natural river systems in the context of the Himalayas. The modelling method is based on the daily Q and SSL data collected from 2007 to 2009. The initial phase involved developing and training the ANN utilizing the FFBP Algorithm within the Matlab (MATLAB R2015a). The networks were optimized utilizing the process of enumeration. The optimal network was subsequently employed to forecast the SSL values, which are ungauged parameters, at the Moradabad (MBD) gauging site. The second stage involves validating the predicted (ungauged) SSL values of MBD by utilizing them to estimate the SSL values of Dabri (DBI) gauged sites. The predicted values obtained from the model are contrasted with the authentic observed values of SSL at DBI. The R² value for the optimal network was found to be 0.998, accompanied by an MSE of 0.00112. The study offers valuable insights into the modelling of ANN and emphasizes the significance of comprehending a river basin and its influencing components to simulate the SSL effectively. This study demonstrates that the proposed methodology allows for highly efficient regional streamflow estimation in ungauged basins, even in diverse geographical areas.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"269 ","pages":"Article 107643"},"PeriodicalIF":3.4,"publicationDate":"2024-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142720834","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Two decades of heavy metal fluctuations in wastewater sludge in Lithuania with evolving trends and implications for treatment efficiency","authors":"Piotr Jachimowicz ,&nbsp;Algirdas Radzevičius ,&nbsp;Petra Wojnarová ,&nbsp;Raimondas Šadzevičius ,&nbsp;Bartłomiej Horoszko ,&nbsp;Midona Dapkienė ,&nbsp;Maja Radziemska ,&nbsp;Barbara Klik","doi":"10.1016/j.gexplo.2024.107642","DOIUrl":"10.1016/j.gexplo.2024.107642","url":null,"abstract":"<div><div>This study evaluates the temporal trends and seasonal variations in heavy metal concentrations within sewage sludge from the Kaunas wastewater treatment plant in Lithuania between 2000 and 2022. It integrates two decades of data with detailed seasonal analyses for 2021 and 2022, providing a comprehensive view of both long-term trends and short-term fluctuations. Monthly wastewater and sludge samples were collected, and concentrations of Cr, Zn, Hg, Cd, Ni, Cu, and Pb were analyzed using atomic absorption spectrometry. Statistical evaluations of temporal and seasonal data were conducted to identify trends and correlations between metal concentrations and external factors. Significant declines were observed in Cr, Pb, and Hg levels, highlighting the effectiveness of regulatory measures and treatment improvements. However, Zn and Cu concentrations remain elevated, posing challenges for sludge management and reuse. Seasonal spikes in Zn and Cr, particularly in May–July and October–December, were linked to industrial activities and stormwater runoff. The study also explores Lithuania's recent regulatory changes that permit higher Zn concentrations in sludge for agricultural use, reflecting evolving sludge management strategies.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"269 ","pages":"Article 107642"},"PeriodicalIF":3.4,"publicationDate":"2024-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142719981","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}