内蒙古河套平原浅层高铁高氟地下水分布与成因

为了查明内蒙古河套平原高铁高氟地下水的分布与形成原因,通过实地调查、监测、资料分析和试验测试等方法手段,详细研究了地下水中铁、氟的分布、地球化学特征及其来源。结果表明:高铁水主要分布在平原中部的冲湖积平原,地势低洼和地下水的排泄地带含量最高;高氟水主要以条带状分布在山前的冲洪积扇地带;在调查研究区12510.83 km2的范围内,深度在10~40 m的浅层地下水中,分布有高铁水9310.66 km2,高氟水2308.35 km2,分别占调查研究区总面积的74.40%和18.45%;研究认为,河套平原高铁高氟地下水的形成主要是由自然地质环境所致,是不同地质环境条件下环境水文地球化学作用的结果;地下水中的铁主要来源于由黄河携带来的大量的第四系沉积物,而溶出的主要原因是地下氧化还原条件的变化;地下水中的氟主要来源于平原周边的山区,气候、地质构造、水文地质和水化学条件是氟富集的主要因素;研究表明河套平原高铁水与高氟水不存在正相关关系。

Distribution and Causes of High-iron and High-fluoride Shallow Groundwater in the Hetao Plain of Inner Mongolia

Distribution, geochemical characteristics of high-iron and high-fluoride groundwater and source of iron and fluoride in the Hetao Plain of Inner Mongolia was discussed in detail based on such means as field investigation, monitoring, data analysis and experiment test in order to find out distribution and formation cause of high-iron and high-fluoride groundwater. The results show that high-iron groundwater is mainly distributed in the alluvial and lacustrine plain areas in the middle part of the plain, and high-iron groundwater presents high content in low-lying areas and groundwater discharge zone in plane level; High-fluorine groundwater is mainly in zoning distribution in the piedmont alluvial fan zone. With the scope of 12510.83 km2 of the research area, there are 9310.66 km2 high-iron groundwater and 2308.35 km2 high-fluoride groundwater in shallow groundwater of 10~40 m in depth, which respectively takes 74.40% and 18.45% of the total research area. Researches indicate that the main formation cause for high-iron groundwater and high-fluoride groundwater is its natural geological environment, resulted from environmental hydrogeochemical action under different geo-environmental conditions. The iron in the groundwater mainly comes from plenty of quaternary sediments brought by the Yellow River while the major cause for dissolution is the changes of the redox conditions; the fluorine in the groundwater mainly comes from the mountainous area near the plain, and climate, geological structure, hydrogeololgy and hydrochemical conditions are the main factors of fluorine concentration. Researches show that there is no positive correlation relationship between high-iron groundwater and high-fluorine groundwater in the Hetao Plain.