Dorota Kaczor-Kurzawa , Irena Wysocka , Monika Chuchro
{"title":"The behavior of the rare earth elements and yttrium in groundwaters of the Holy Cross Mountains, SE Poland","authors":"Dorota Kaczor-Kurzawa , Irena Wysocka , Monika Chuchro","doi":"10.1016/j.gexplo.2024.107493","DOIUrl":null,"url":null,"abstract":"<div><p>In areas of contrasting geology, local but significant spatial changes in environmental conditions can occur suddenly and unexpectedly within aquifers, hampering accurate assessment of groundwater chemistry. Recently, the rare earth elements (REEs) have become extensively used in identifying geochemical processes in aqueous systems, due to their unique sensitivity to environmental changes. In this study, the REEs and Y (yttrium), combined with the chemical parameters of the main, minor and trace water components, and with the isotopic signatures of δ<sup>18</sup>O-H<sub>2</sub>O, δ<sup>2</sup>H-H<sub>2</sub>O, <sup>3</sup>H-H<sub>2</sub>O, δ<sup>34</sup>S-SO<sub>4</sub>, δ<sup>18</sup>O-SO<sub>4</sub>, were investigated in order to gain a better understanding of the geochemistry of the groundwaters in the Holy Cross Mountains, which possesses a diverse hydrogeological system. The waters studied are ‘young’, meteoric-derived, of acidic to slightly alkaline pH (4.95–7.75) and TDS values of 38.97–2713.91 mg/L. They represent predominantly the HCO<sub>3</sub>-Ca-Mg and less often the HCO<sub>3</sub>-Ca-SO<sub>4</sub>-(Mg) or SO<sub>4</sub>-Ca-(Mg) types. The dissolved (<0.45 μm) concentrations of the REEs (5.55 to 13,857.35 ng/L) and Y (4.43 to 2450.22 ng/L) in the waters studied are the result of host rock dissolution, and tend to increase significantly, by up to several orders of magnitude, via interactions between the rocks and acidic waters. Speciation calculation reveals that dissolved REE + Y in neutral and alkaline waters are transported mainly as bicarbonate (CO<sub>3</sub>)<sub>2</sub><sup>−</sup> and carbonate CO<sub>3</sub><sup>+</sup> complexes, while in a more acidic environment these elements occur preferably as free ions (REE<sup>3+</sup>+Y<sup>3+</sup>), and their abundance gradually increases along with decreasing pH value. The EUS (European Shale) normalized REE patterns of the waters studied show two distinct dominant types: (i) upwards-sloping with HREE-enrichment (LREEs<MREEs<HREEs), (ii) convex with MREE-enrichment (LREEs<MREEs>HREEs). The first pattern type reflects REE fractionation in alkaline and oxygenated waters, leading to preferential LREE adsorption onto mineral particles, accompanied by complexation of HREEs with carbonate and bicarbonate ions, while the second pattern type results from dissolution of the host rocks in more acidic conditions. The REE patterns in the waters studied are mostly different from the REE patterns characteristic of the host rocks, except for some water samples from carbonate aquifers. Ce and Eu anomalies were recorded in the waters studied. Some of the negative Ce and positive Eu anomalies were inherited from host rock dissolution, while other negative or positive Ce anomalies reflect oxygenic or more reducing conditions, respectively.</p></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":null,"pages":null},"PeriodicalIF":3.4000,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Geochemical Exploration","FirstCategoryId":"89","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0375674224001092","RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"GEOCHEMISTRY & GEOPHYSICS","Score":null,"Total":0}
引用次数: 0
Abstract
In areas of contrasting geology, local but significant spatial changes in environmental conditions can occur suddenly and unexpectedly within aquifers, hampering accurate assessment of groundwater chemistry. Recently, the rare earth elements (REEs) have become extensively used in identifying geochemical processes in aqueous systems, due to their unique sensitivity to environmental changes. In this study, the REEs and Y (yttrium), combined with the chemical parameters of the main, minor and trace water components, and with the isotopic signatures of δ18O-H2O, δ2H-H2O, 3H-H2O, δ34S-SO4, δ18O-SO4, were investigated in order to gain a better understanding of the geochemistry of the groundwaters in the Holy Cross Mountains, which possesses a diverse hydrogeological system. The waters studied are ‘young’, meteoric-derived, of acidic to slightly alkaline pH (4.95–7.75) and TDS values of 38.97–2713.91 mg/L. They represent predominantly the HCO3-Ca-Mg and less often the HCO3-Ca-SO4-(Mg) or SO4-Ca-(Mg) types. The dissolved (<0.45 μm) concentrations of the REEs (5.55 to 13,857.35 ng/L) and Y (4.43 to 2450.22 ng/L) in the waters studied are the result of host rock dissolution, and tend to increase significantly, by up to several orders of magnitude, via interactions between the rocks and acidic waters. Speciation calculation reveals that dissolved REE + Y in neutral and alkaline waters are transported mainly as bicarbonate (CO3)2− and carbonate CO3+ complexes, while in a more acidic environment these elements occur preferably as free ions (REE3++Y3+), and their abundance gradually increases along with decreasing pH value. The EUS (European Shale) normalized REE patterns of the waters studied show two distinct dominant types: (i) upwards-sloping with HREE-enrichment (LREEs<MREEs<HREEs), (ii) convex with MREE-enrichment (LREEs<MREEs>HREEs). The first pattern type reflects REE fractionation in alkaline and oxygenated waters, leading to preferential LREE adsorption onto mineral particles, accompanied by complexation of HREEs with carbonate and bicarbonate ions, while the second pattern type results from dissolution of the host rocks in more acidic conditions. The REE patterns in the waters studied are mostly different from the REE patterns characteristic of the host rocks, except for some water samples from carbonate aquifers. Ce and Eu anomalies were recorded in the waters studied. Some of the negative Ce and positive Eu anomalies were inherited from host rock dissolution, while other negative or positive Ce anomalies reflect oxygenic or more reducing conditions, respectively.
期刊介绍:
Journal of Geochemical Exploration is mostly dedicated to publication of original studies in exploration and environmental geochemistry and related topics.
Contributions considered of prevalent interest for the journal include researches based on the application of innovative methods to:
define the genesis and the evolution of mineral deposits including transfer of elements in large-scale mineralized areas.
analyze complex systems at the boundaries between bio-geochemistry, metal transport and mineral accumulation.
evaluate effects of historical mining activities on the surface environment.
trace pollutant sources and define their fate and transport models in the near-surface and surface environments involving solid, fluid and aerial matrices.
assess and quantify natural and technogenic radioactivity in the environment.
determine geochemical anomalies and set baseline reference values using compositional data analysis, multivariate statistics and geo-spatial analysis.
assess the impacts of anthropogenic contamination on ecosystems and human health at local and regional scale to prioritize and classify risks through deterministic and stochastic approaches.
Papers dedicated to the presentation of newly developed methods in analytical geochemistry to be applied in the field or in laboratory are also within the topics of interest for the journal.