贵德盆地高氟、高砷地下热水分布及水化学特征

The distribution and geochemistry of geothermal groundwater bearing F and as in the guide basin

贵德县是青海省地方病危害最严重的地区之一。通过区域地质、构造及水文地质调查,表明:赋存于贵德群中的承压自流热水是当地饮水型氟中毒和砷中毒的致病水体;深度多小于400m,分布明显受控于NNW向压扭性断裂和NWW向张扭性断裂,并形成了两个异常中心。异常区围绕NEE向张扭性断裂带呈椭圆形展布,南北宽约5km,东西长约10km;其氟离子含量0.32～4.57mg/L,砷元素含量0.112～0.318mg/L,随深度和温度呈增高趋势;水温在16.0～45.9℃,pH较高,一般大于8.0,多属TDS0.2～0.5g/L的HCO3.SO4.C1—Na型淡水。为该地区防病改水提供了水文地质依据。

Guide county is one of the most serious areas for endemic in Qinghai Province. The survey results of regional geology, tectonics, and hydrogeology show that the confined and artesian thermal water from the Guide Group is pathogenic reason for fluorosis and arseniasis. The confined aquifer with two abnormal centers has a buried depth less than 400 meter and its distribution is controlled clearly by the compression-shear fault with NNW striking and tension-shear fault with NEE striking. The abnormal area around the tension-shear fault with NEE striking spreads as an ellipse with a 5 kilometer width and a 10 kilometer length. Fluorin and arsenic concentrations vary between 0. 35-4. 57mg/L and 0. 112-0.318mg/L, respectively, and their concentrations increase with depth and temperature. Occurrence temperature ranges from 16.0℃ to 45.9℃, and pH is generally higher than 8.0. Thermal water with TDS of 0.2-0.5g/L is of HCO3 ·SO4 ·Cl--Na type. The present study provides hydrogeological evidences for preventing endemic and improving water quality.