新疆玛纳斯河流域地下水砷氟分布及共富集成因

Distribution and coenrichment of arsenic and fluorine in the groundwater of the Manas River Basin in Xinjiang

砷(As)、氟(F)污染水体及其共存问题是环境领域的热点问题,长期暴露其中对公众的身体健康存在巨大威胁。以新疆玛纳斯河流域为研究区,分析高As、高F地下水的水化学及空间分布特征,结合地质条件、赋存环境和人类活动的影响进一步阐明地下水As和F的来源、迁移与富集的水文地球化学过程。结果表明:研究区地下水整体为弱碱性、还原环境的淡水,地下水As、F质量浓度变化范围分别为1.13~41.35μg·L^(-1)、0.06~8.02 mg·L^(-1),高As、高F地下水水样占总水样的62.9%、45.7%,砷氟共富集占总水样的37.1%。砷氟共富集地下水主要分布在平原区北部靠近沙漠边缘,水化学类型主要为HCO_(3)·Cl型和HCO_(3)·SO_(4)·Cl型。研究区南部山区高As、高F岩层是地下水As、F的原生来源,区域地质构造与水文地质条件是影响地下水砷氟富集的重要因素。玛纳斯河流域高As地下水具有高pH值、低γSO_(4)^(2-)/γCl^(-)比、低Eh等特征,说明弱碱性的还原环境有利于地下水中As富集;高F地下水具有高pH值、高HCO_(3)^(-)、高Na^(+)和低Ca^(2+)等特征,说明高Na^(+)和低Ca^(2+)的碱性环境有利于地下水中F富集。

Arsenic(As)and fluoride(F)pollution in water bodies,along with their coexistence,are critical environmental concerns,with long-term exposure posing a significant threat to public health.This study focuses on the Manas River Basin as the research area,analyzing the hydrochemical,and spatial distribution characteristics of groundwater with high As and F content.Furthermore,the study aims to elucidate the hydrogeochemical processes related to the origin,migration,and enrichment of As,and F in groundwater,considering geological conditions,occurrence environments,and the influence of human activities.The results show that the groundwater in the study area exhibits an alkaline-reducing environment.The mass concentrations of As and F in groundwater range from 1.13 to 41.35μg·L^(−1)and from 0.06 to 8.02 mg·L^(−1),respectively.Groundwater samples with high As and F content constituted 62.9%and 45.7%of the total samples,respectively,while samples with a coenrichment of As and F accounted for 37.1%of the total samples.As-F coenriched groundwater is mainly distributed in the northern plain region,near the edge of the desert,with the dominant hydrochemical types being HCO_(3)·Cl and HCO_(3)·SO_(4)·Cl.The primary sources of As and F in groundwater are high-content rock strata found in the southern mountainous area of the Manas River Basin.The high pH value,low SO_(4)^(2−)/Cl^(−)molar ratio,and low Eh of the high-As-content groundwater in the Manas River Basin indicate that a weak alkaline-reducing environment facilitates As enrichment in groundwater.Conversely,groundwater with high F content is characterized by high pH,HCO_(3)^(−),and Na^(+)levels,as well as low Ca^(2+),indicating that an alkaline environment with high Na^(+)and low Ca^(2+)content favors F enrichment in groundwater.