Hydrochemical Characteristics of High-fluorine Groundwater in the Plain of the Yarkant River Basin, Northwest China

¹ College of Water Conservancy and Civil Engineering, Xinjiang Agricultural University, Urumqi, 830052, P.R.China
² Xinjiang Hydrology and Water Resources Engineering Research Center, Urumqi, 830052, P.R.China
³ Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100049, P.R.China

^* Corresponding author: zjzhoujl@163.com (JL Zhou)
^** Correspondence to: yinzhu_zhou@qq.com (YZ Zhou)

Abstract

Study on regional distribution of high-fluorine groundwater will help to understand migration and transformation of fluorine, and provide the theoretical basis of low-fluorine groundwater exploration in high-fluorine groundwater areas. In this study, 74 shallow groundwater samples collected from plain area of the Yarkant River Basin in Xinjiang were analyzed. Results showed that the type I (low-fluorine groundwater, F^-<1mg/L) was distributed in the piedmont plain, the type II (high-fluorine groundwater, 1mg/L≤F^-<2mg/L) was distributed in the central and northeastern part of the basin, and the type III (high-fluorine groundwater F^-≥2mg/L) was continuously distributed along the flow direction of river water in the western part of the basin. The average concentration of groundwater fluorine was 1.26 mg/L, with an exceeding standard rate of 48.65%. Groundwater cations were dominated by Ca²⁺ and Mg²⁺ and anions were dominated by SO_4^2- and Cl^-. High-fluorine groundwater occurred under neutral to weak alkaline environment with pH ranged between 6.61 and 7.99, which is favorable for the dissolution of fluorine-bearing minerals. Average concentration of total dissolved solids (TDS) in type I, type II and type III groundwater were 1657 mg/L, 3522 mg/L and 3724 mg/L, respectively. High-fluoride groundwater generally had high TDS concentrations.