Hydrogeochemical characteristics of karst groundwater in the northern part of the city of Bijie
YUAN Jianfei;DENG Guoshi;XU Fen;TANG Yeqi;LI Pengyue;Chengdu Center of China Geology Survey;School of Environmental Studies,China University of Geosciences;
There are abundant karst groundwater resources in the southwestern China,which is the main water sources for local people. Chemical components and hydrogen and oxygen isotopic data of the groundwater in the Haizijie country and its adjacent regions of the city of Bijie are combined to determine the recharge source of the karst groundwater,identify the origin of major components in the groundwater,and distinguish the water-rock interaction processes. Chemical components analyses show that most of the groundwater is of HCO_3~-Ca,HCO_3·SO_4-Ca and HCO_3~-Ca·Mg type. The hydrogen and oxygen isotopic data demonstrates that the groundwater in the study area receives recharge from modern precipitation. The major chemical components of most groundwater are Ca~(2+),Mg~(2+),HCO_3~- and SO_4~(2-),which are the results of dissolution and precipitation of dolomite,calcite,gypsum and halite. Some water samples have high concentrations of SO_4~(2-)and NO-3,which can be interpreted by the influence of sewage,agriculture and mining activities. The results are instructive for improving the management and utilization of groundwater resources for local government.