平朔矿区不同水体水化学特征及氟分布成因

为了探明采煤驱动下平朔矿区所在流域内不同水体水化学特征及氟分布成因，综合运用水化学图解、主成分分析和地球化学模拟等方法，对2020~2021年采集的468组地表水、地下水和矿井水样品进行分析.结果表明，地表水、地下水和矿井水均呈近中性至弱碱性；地表水和矿井水中优势阴离子为SO₄^2-，地下水中优势阴离子为HCO₃^-，Ca²⁺是所有水体中的优势阳离子.地表水和矿井水水化学类型以SO₄·HCO₃-Ca·Mg为主.地下水水化学类型主要为HCO₃-Ca·Mg，采煤区的浅层或深层地下水存在HCO₃·SO₄-Ca·Mg型.水体水化学主要受碳酸盐岩风化溶解、采煤活动以及含氟矿物的风化溶解影响，采煤和工农业等人类活动加速了不同水体间水化学转换，尤其是浅层地下水.水体ρ（F^-）介于0.10~1.76 mg·L^-1，其中，42%浅层地下水F^-浓度高于国家饮用水安全限值；时空分布上，西北至东南地下水中F^-浓度平均值呈增加趋势，3月和8月F^-浓度偏高.高氟浅层地下水化学呈现偏碱性和高Na⁺特征.F^-富集主要受采煤活动和含氟矿物风化溶解影响，水体中方解石饱和加速了含氟矿物的风化溶解.

Hydrochemical Characteristics and Fluorine Distribution and Causes of Different Water Bodies in Pingshuo Mining Area

This study was carried out to elucidate the hydrochemical characteristics, fluorine ion (F^-) distribution, and causes of formation in different water bodies driven by coal mining in the Pingshuo mining area. A total of 468 samples of surface water, groundwater, and mine water were collected in 2020-2021. Hydrochemical diagrams, principal component analysis, and geochemical simulation were comprehensively used for sample analysis. The results showed that the surface water, groundwater, and mine water were nearly neutral to slightly alkaline. The dominant anion of surface water and mine water was SO₄^2-, whereas the dominant anion in groundwater was HCO₃^-; Ca²⁺ was the dominant cation in all water bodies. The main hydrochemical types of surface water and mine water were SO₄·HCO₃-Ca·Mg. The main type of groundwater was HCO₃-Ca·Mg. HCO₃·SO₄-Ca·Mg type existed in shallow or deep groundwater of the coal mining area. The hydrochemistry of water bodies was mainly affected by the weathering and dissolution of carbonate rocks and silicate rocks, coal mining activities, as well as the weathering and dissolution of fluorine-bearing minerals. Human activities such as coal mining and industry and agriculture have accelerated the conversion of water chemistry between different water bodies, especially shallow groundwater. The concentration of F^- in the study area ranged from 0.10 to 1.76 mg·L^-1. The F^- concentration of 42% of the shallow groundwater exceeded the national permissible limit for drinking. In terms of spatial and temporal distribution, the average concentration of F^- in groundwater from northwest to southeast showed an increasing trend, and the concentration of F^- was higher in March and August. Alkalinity and high Na⁺ were the main hydrochemical environmental characteristics of shallow groundwater with high F^- concentration. F^- enrichment of water bodies in the study area was mainly controlled by coal mining activities and weathering dissolution of fluorine-bearing minerals accelerated by the saturation of calcite.