Abstract: Kuitun River Basin in Xinjiang is an area where groundwater is seriously affected by arsenic. To find out the spatial distribution characteristics of arsenic in groundwater and the causes of abnormal arsenic content in the area, we collected 51 groups of surface water, underflow and confined groundwater samples in the study area in 2017, 16 groups of confined groundwater samples and 45 groups of borehole sediment samples in typical high-arsenic-content area in 2019. By test analysis and mathematical statistical analysis on the groundwater and sediment samples, we obtained the spatial distribution characteristics of high-arsenic groundwater in the study area and the influencing factors of abnormal arsenic content. Results manifest that in horizontal direction, arsenic concentration is correlated negatively with topography, increasing gradually from south to north; in vertical direction, high-arsenic groundwater is mainly distributed in aquifers greater than 80 meters deep. The spatial distribution of arsenic content in groundwater is related to natural geographical conditions such as paleogeographic environment, topography, closed geology, and arid climate. The causes of abnormal arsenic content in groundwater are concluded as: groundwater environment with high pH value, high HCO^-₃ concentration and low Eh; particle size, chromaticity, and local deposition environment of sediments; and human activities using arsenic-containing pesticides and fertilizers.

Key words: hydrochemistry environment, arsenic, spatial distribution, influence factors, Kuitun River