高寒区典型流域地下水化学特征、影响因素及健康风险

为深入理解高寒区地下水化学演化并科学指导地下水资源管理,以典型高寒区流域格尔木河流域为研究对象,对其2019年地下水化学特征及其影响因素进行了分析,基于熵值水质指数、Durov图和钠吸附比对融雪期、丰水期和枯水期地下水水质进行了评价,并利用健康风险评估模型对地下水NO^-₃和F^-的潜在健康风险进行了评估。结果表明:3个时期地下水化学类型变化不大,山区潜水以HCO^-₃型为主,平原区潜水以Cl^-型为主,而承压水以HCO^-₃型为主,高离子浓度的地下水分布在平原溢出带；潜水化学成分融雪期主要受春耕施肥的影响,枯水期受工业废水、生活污水排放的影响,丰水期受水岩作用的影响；流域大部分潜水不适合灌溉,细土平原溢出带少数潜水不适合饮用；F^-对人体健康的非致癌风险大于NO^-₃并已危及儿童,此外,两者对人体健康的非致癌风险枯水期比其他时期更严重。减少生活污水和工农业废水排放等人为输入是当前流域地下水水质保护的关键举措。

Chemical characteristics, influencing factors and human health risks of groundwater in a typical alpine watershed

In order to deeply understand the chemical evolution of groundwater and scientifically guide the groundwater resource management in the alpine region, this study took the Golmud River Watershed as the typical alpine watershed, investigated the groundwater chemistry and explored the influencing factors in 2019. Meanwhile, the groundwater quality in the snowmelt, wet season and dry season was evaluated using the entropy water quality index, Durov diagram and sodium sorption ratio, and potential risks posed by nitrate and fluoride in the groundwater to human health were assessed using the mathematical model of health risk assessment. Hydro chemical results showed that chemical type of groundwater had little change with periods but varied greatly in space: HCO^-₃ type for phreatic groundwater in the mountain area, Cl^- type for phreatic groundwater in the plain area and HCO^-₃ type for confined groundwater in the plain area. The high ion concentrations of groundwater occurred mainly in the overflow zone of plain. Phreatic groundwater chemistry was mainly affected by the fertilizer use of spring tillage during the snowmelt season, by the industrial wastewater and domestic sewage discharge during the dry season, and by the water-rock interaction during the wet season. The results of water quality assessment indicated that shallow groundwater was not mostly suitable for irrigation in the watershed, and some was not suitable for drinking in the plain. The health risk evaluation found that the non-carcinogenic risk of fluoride was greater than that of nitrate to human health, and has already endangered children, and the non-carcinogenic risks of fluoride and nitrate were severer to human health during the dry period than other periods. Therefore, it is currently urgent to reduce the anthropogenic input such as domestic sewage, industrial discharge and agricultural discharge to protect the groundwater quality in the watershed.