Abstract
This study analyzed the hydrochemical characteristics and microbial communities of karst water in Samcheok, Korea, and compared water quality results to identify the seasonal characteristics and hydrogeological connectivity of the study areas of Hamaengbang-ri, Gyogok-ri, Yeosam-ri, and the downtown area of Samcheok. Field survey and water quality analysis were performed in July 2019, February 2020, and April 2020. Hydrochemical analysis of karst water (groundwater and surface water) showed that most samples were comprised of Ca-HCO3 and that water–rock interactions were a dominant factor compared to precipitation and evaporation (crystallization). For seasonal characteristics, water–rock interactions appeared more active in the dry season than in the rainy season. Calcite weathering was dominant in the dry season, whereas dolomite weathering dominated the rainy season. Moreover, the saturation indexes for the dry and rainy seasons were less than and greater than 0, respectively, corresponding to an unsaturation (oversaturation) state; thus, white precipitate distributed in the study areas was deposited in the rainy season. Finally, as a result of analyzing the hydraulic characteristics between regions, hydrogeological similarities were identified between Hamaengbang-ri and Yeosam-ri, and between Gyogok-ri and downtown Samcheok, which suggested hydrogeological connectivity between each of the pairs.
Highlights
Karst areas refer to regions where there are limestones or dolomites in large volumes on an exposed erosion reference surface allowing various karst terrains to form on the surface and underground because of the groundwater system developed by the corrosion of the rock body [1,2]
The temperature of groundwater ranged from 10.5 ◦ C to 16.3 ◦ C, which showed a smaller variation according to season and weather than that of surface water (4.4–27.1 ◦ C)
Carbonate rocks are dominant in the study areas, the pH mean values of groundwater were slightly acidic (6.5) and those of surface water were slightly alkaline (7.4–8.1)
Summary
Karst areas refer to regions where there are limestones or dolomites in large volumes on an exposed erosion reference surface allowing various karst terrains to form on the surface and underground because of the groundwater system developed by the corrosion of the rock body [1,2]. Carbonate rocks account for 20% of the Earth’s land, and the aquifers of karst areas provide 25% of drinking water worldwide. For this reason, research on karst water is extremely crucial [2,3,4,5,6]. Agricultural activities in typical karst features such as doline tend to cause overexploitation of groundwater, thereby accelerating the decline of water table and the formation of sinkholes. In this regard, the role of water is especially important in several studies on karst topography. Dissolved inorganic carbon (DIC) concentrations in karst areas depend mainly on the
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