Abstract
ABSTRACT As a continuing study on the enrichment of heavy metals in soil in the Okchon zone, this study was performed in order to investigate the hydrogeochemical characteristics and the potential contamination of surface water and groundwater in the middle Okchon zone, Korea, underlain by black shales and other metasedimentary rocks. Surface water and groundwater samples were collected from the Duk-Pyung, the Chu-Bu, the Bo-Eun, the I-Won and the Geum-Kwan areas, and in-situ measurement and chemical analysis of dissolved ions were performed. All water samples are characterized by the hydrogeochemical types of Ca 2+ -HCO3 − and Ca2+ -(Cl− + SO4 2-) due to the dissolution of calcite and Mg-carbonates and the oxidation of sulfide minerals originated from black shale and slates. The increase of the concentrations of Ca2+, Mg2+, HCO3 −, Na+ and SiO2 from surface water to groundwater indicates water-rock interaction such as the dissolution of carbonates and the weathering of silicates, which is supported by the results of hydrogeochemical modeling and the phase stabilities of related minerals. The high concentrations of K+, Cl− and NO3 − in groundwater are also observed, which may be due to the inflow of external contaminants to aquifer. From the results of statistical analysis, it can be concluded that the factors controling the hydrogeochemical characteristics of surface water and groundwater are the in-flow of external contaminants, the dissolution of carbonates, the weathering of silicates and the oxidation of sulfides. Heavy metal contamination of water samples was not observed and some groundwater samples showed the contamination of NO3 − over the limit of the drinking water standard.
Published Version
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