新疆塔什库尔干断裂带温泉环境地球化学特征

Environmental Hydrogeochemical Characteristics of Hot Springs in Tashkurgan Fault Zone of Xinjiang,China

水文地球化学方法是研究温泉水成因和评价温泉水资源的有效手段。选用2018年9月在新疆塔什库尔干断裂带内采集的6个温泉水样,根据主量和微量元素浓度以及氢氧、锶同位素进行水化学特征分析,并利用WQI指数进行水质评估。结果表明:①温泉水整体呈碱性,矿化度平均值为1036.13 mg·L^(-1),水化学类型为HCO_(3)^(-)Ca、HCO_(3)^(-)Na、SO_(4)^(-)Na等3种,富集因子说明区域变质角闪岩、碱性片麻岩和侵入花岗岩对微量元素含量特征起控制作用;②温泉水的氢氧同位素组成均分布在大气降水线附近,指示补给来源主要为大气降水,补给高程为4.3~5.6 km,符合高原干旱—半干旱气候下的蒸发作用特征;循环深度为1.4~2.1 km,属于断裂带控热控水的循环型温泉;③主量元素水质评价结果表明本次采集的温泉水样均不适合直接作为生活饮用水和农业用水,F-浓度超标;微量元素水质评价结果表明WQI指数介于1类和3类之间,整体水质较为原始,但公格尔和马尔洋温泉水样出现局部B和As浓度空间分布高值,部分温泉水Li、Fe、F浓度及温度达到了医疗热泉标准,具有理疗和保健功效。

Hydrogeochemical method is effective for studying the genesis of hot spring water and evaluating hot spring water resources.Six hot spring water samples collected from the Tashkurgan fault zone in Xinjiang in September,2018 were selected.According to the concentration of major and trace elements,as well as H-O and Sr isotopes,the characteristics of hydrogeochemistry were analyzed,and the comprehensive water quality index(WQI)was used for water quality assessment.The results show that①the spring water is generally alkaline with an average TDS of 1036.13 mg·L^(-1);the chemical types of hot spring water are HCO_(3)^(-)Ca,HCO_(3)^(-)Na,and SO_(4)^(-)Na;the enrichment factor explains the control effect of regional metamorphic amphibolite,alkaline gneiss and intrusive granite on the characteristics of trace element content;②the H-O isotopic compositions of spring water all distribute near the precipitation line,indicating that the recharge source is mainly meteoric water,and the recharge altitude is 4.3-5.6 km,which is consistent with the characteristics of evaporation in the arid and semi-arid climate of the plateau;the circulation depth is 1.4-2.1 km,which belongs to the circulating hot spring controlling heat and water in fault zone;③the water quality evaluation of major element shows that the collected hot spring water samples are not suitable for drinking water and agricultural water,and the F-concentration in the hot spring exceeds the standard;the water quality evaluation of trace element shows that the water quality identification index between 1 and 3 classes,the overall water quality is relatively primitive,but the local spatial distributions of B and As concentrations of Gongge er and Ma eryang hot springs are high,Li,Fe and F concentrations and water temperature of part hot springs reach the standard for medical hot springs,have effect of physical therapy and health care.The research results provide data support for geothermal research in Tashkurgan fault zone,and are of great significance for sustainable development and protection of local hot spring resources.