LIN Yun ^{1, 2}, CAO Feilong¹, WU Yazun^{1, 2}, REN Huaxin¹, JIA Fangjian¹

(1.Institute of Resources & Environment, Henan Polytechnic University, Jiaozuo, 454003, Henan province, China；
2.Collaborative Innovation Center of Coalbed Methane and Shale Gas for Central Plains Economic Region, Henan Province, Jiaozuo 454000, China;)

Abstract: In recent years, affected by mining activities and climatic changes, the groundwater chemical fields of most karst spring areas in the north of China have been changed, including the Xujiagou spring area in Hebi, but their evolution law and hydrogeochemical characteristics under current conditions are still unclear. In order to reveal hydrogeochemical characteristics and controlling factors of groundwater in the Xujiagou spring area, we studied this area systematically by using multiple methods such as mathematical statistics, ions ratio, Gibbs diagram, correlation analysis. The results showed that hydrochemical types of groundwater in the spring area were mainly HCO3-Ca·Mg and HCO3·SO4-Ca·Mg types. The main controlling factor of groundwater chemical evolution in the research area was rock weathering. Ca2+, Mg2+, SO42- and HCO3- in the groundwater mainly came from the weathering of carbonates (calcite (CaCO3) and dolomite (CaMg(CO3)2) and sulfate (CaSO4·2H2O). In addition, a certain part of SO42- came from the oxidization of pyrite. The dedolomitization caused the Mg2+ content in the groundwater was significantly higher in the dry season than in the wet season. The cation exchange reduced Na+ and K+ contents in the groundwater. The stable isotope characteristics showed that the karst groundwater was supplied mainly by rainfalls in exposed western areas, while the karst groundwater in the south area (near the Qihe river) was also affected by the seepage of river water. The karst groundwater showed a 18O drift phenomenon in the during the dry season. This study provided a scientific basis for the better development and protection of karst groundwater in spring areas of north China.

Key words: Karst groundwater; Hydrochemical characteristics; Ion ratios; Hydrogen and oxygen isotope; Xujiagou Spring area

EARTH AND ENVIRONMENT Vol.48, No.3, Tot No.335, 2020, Page 294-306