Evaluation on quality and health risk of groundwater in a highly urbanized watershed, China

Abstract

Urbanizations and industrializations may accelerate the contamination and deterioration of groundwater quality. This study aimed to evaluate the quality and human health risk of shallow groundwater in Shenzhen, China where high levels of urbanization and industrialization are. The hydrochemistry characteristics, water quality levels and human health risks of main ions, nutrient elements, metals in 220 samples collected from Maozhou River Basin (MRB) located in the northwest of Shenzhen were investigated. It showed that chemical constituents of the groundwater were further complicated by seawater intrusion and urbanization expansion. Water quality evaluated by Fuzzy Comprehensive Method showed that 21.05 % of samples distributed around reservoirs were classified into grade II or better. Nearly 79% of samples distributed in the densely populated urban land were classified into grade III or worse, indicating pollution from anthropogenic factors cannot be ignored. For the river tidal reach where river stage fluctuated about 0.5 m to 1.5 m within a tidal cycle, the chemical composition of groundwater was influenced by frequent water exchange with the river. The carcinogenic and non-carcinogenic health risk for different age groups from high to low were children, adult women, adult men, adolescent women, and adolescent men, respectively.Approximately 39% of groundwater samples distributed around the densely populations area with health risk larger than 5×10 -5 were unacceptable for children. This investigation would be helpful for improving groundwater management and as a practical reference for sustainable groundwater exploitation in the MRB.