Spatial-temporal Variation in Groundwater Quality and the Contamination Source Analysis in Shihezi-Changji Area

Abstract

To analyze spatial-temporal variation in groundwater quality and contamination sources in the Shihezi-Changji area in Xinjiang, a Bayesian water quality evaluation model based on Shannon entropy, Spearman rank correlation coefficient, principal component analysis, and an absolute principal component scores-multiple linear regression receptor model (APCS-MLR) were comprehensively used in this study. Groundwater samples in 23 in-situ wells were collected from 2016 to 2021 for quality analysis. The results showed that ① groundwater quality was generally good, with most samples having a phreatic water quality of Class Ⅰ and Class Ⅱ and most confined groundwater quality being of Class Ⅰ. ② Temporally, 2016 and 2017 were the key time nodes of water quality variation in phreatic water and confined groundwater, respectively. Class Ⅳ and Class Ⅴ groundwater was observed only before the key time nodes, whereas after those time nodes the groundwater quality fluctuated within Class Ⅰ to Class Ⅲ. ③ Spatially, the order of phreatic water quality in descending order was Shihezi City, Hutubi county, Manas county, and Changji City, whereas that of confined groundwater quality was:Shihezi City and Changji City, Hutubi county, and Manas county. ④ The spatial-temporal variations in groundwater quality and that in major related indices were basically similar and highly heterogeneous. ⑤ Phreatic water quality was mainly affected by leaching (67.30%), leaching-migration (10.89%), and agricultural-domestic pollution (9.44%); by contrast, unconfined groundwater quality was mainly affected by leaching-enrichment (52.08%), agricultural-domestic pollution (16.06%), and ion exchange under an alkaline environment (12.64%). Although groundwater quality was improved over the years, more attention should be paid to groundwater salinization in the 149 Regiment in northern Manas County.