Hydrochemical Characteristics and Formation Mechanism of Groundwater in West Zoucheng City, Shandong Province, China

The groundwater in the western part of Zoucheng is an important water source for domestic, industrial and agricultural use in Zoucheng. Understanding its hydrochemical characteristics and formation mechanism is of great significance to the sustainable development and utilization of groundwater. In this study, 36 water samples were collected during wet and dry seasons, and the hydrochemical components K + , Na + , Ca 2+ , Mg 2+ , Cl - , SO 4 2- , HCO 3 - , NO 3 - , F - , TH and TDS were analyzed. Graphic method, correlation analysis and principal component analysis were applied to explore the hydrochemical characteristics and evolution mechanism of groundwater in the study area. The results show that: (1) The orders of the anion and cation concentrations of karst groundwater and pore groundwater are Ca 2+ >Na + >Mg 2+ >K + and HCO 3 - >SO 4 2- >Cl - >NO 3 - >F - . (2) On the whole, the water quality from different sources follows a specific order: karst groundwater > pore groundwater > surface water; also, water quality in the dry season is better than that in the wet season from all three sources. (3) The water chemistry types of groundwater are complex and changeable. Compared with dry seasons, HCO 3 and SO 4 type water increases in wet seasons, while the Cl type and Mg type water decreases. Na type in pore groundwater is significantly more than that in karst groundwater. (4) The chemical formation of karst groundwater and pore groundwater in dry and wet seasons are mainly affected by water-rock interactions and human activities.