Analysis on the Dominant Factors of Groundwater Contamination in Balasu Area in Northern Shaanxi Province of China

This study investigated groundwater contamination in the Balasu Area in northern Shaanxi Province, one of largest energy resource centers in China. Groundwater samples collected from 128 locations in the Balasu area were analyzed and evaluated to establish the local groundwater quality zonings. Results indicate that groundwater in the Balasu area is contaminated, and the dominant contaminants in the groundwater are NO₃ ^-1 and NO₂ ^-. The concentration of NO₃ ^-1 was detected at 0.19~2.2 mg/L and 26.50~127.00 mg/L in the samples collected up-gradient and down-gradient through Jiumaowan. Concentration of NO₂ ^- was detected at 0.0 mg/L and 0.12 mg/L, respectively from the same samples. Zones I through IV, from non-polluted to seriously polluted, were identified for groundwater quality in the Balasu area. The analysis results indicate that the dominant factors of groundwater contamination in Balasu area are the township´s daily wastewater discharge and the agriculture fertilization. The contamination caused by factories and mines is not obvious at present. Meanwhile, the low content of metal and heavy metal ions in groundwater at present can be used as the background value in the future research on the groundwater contamination.