北方典型岩溶泉域地下水水文地球化学特征分析——以鹤壁许家沟泉域为例

近年来,受采矿活动、气候变化等因素影响,包括鹤壁许家沟泉域在内的北方多数岩溶泉域水化学场发生了改变,但其演变规律及现状条件下的水文地球化学特征仍不明晰。为揭示现状条件下许家沟泉域地下水水文地球化学特征及其控制因素,本文在调查取样分析的基础上,采用数理统计、离子比例系数、Gibbs图及相关性分析等方法进行了研究。结果表明:泉域内岩溶地下水水化学类型主要为HCO_3-Ca·Mg和HCO_3·SO_4-Ca·Mg型。地下水主要水化学组分演化过程的主控因素是岩石风化作用,地下水中的Ca~(2+)、Mg~(2+)、SO_4~(2-)和HCO_3~-主要来源于含方解石(CaCO_3)、白云石(CaMg(CO_3)_2)的碳酸盐岩以及硫酸盐岩(CaSO_4·2H_2O)的溶解,一部分SO_4~(2-)来自黄铁矿氧化。脱白云石化作用致使泉域枯水期地下水中Mg~(2+)明显高于丰水期。阳离子吸附交替使地下水中Na~+、K~+含量降低。稳定同位素特征表明,泉域岩溶地下水主要接受西部裸露区大气降雨的入渗补给,泉域南部岩溶地下水还受淇河河水渗漏的影响,枯水期岩溶地下水中δ~(18)O存在漂移现象。研究成果为泉域内岩溶地下水的合理开发与保护提供了依据。

Hydrogeochemical Characteristics of Groundwater in Typical Karst Spring Areas of North China-A Case Study in the Xujiagou Spring Area, Hebi

In recent years, affected by mining activities and climatic changes, the groundwater chemical fields of most karst spring areas in the north of China have been changed, including the Xujiagou spring area in Hebi, but their evolution law and hydrogeochemical characteristics under current conditions are still unclear. In order to reveal hydrogeochemical characteristics and controlling factors of groundwater in the Xujiagou spring area, we studied this area systematically by using multiple methods such as mathematical statistics, ions ratio, Gibbs diagram, correlation analysis. The results showed that hydrochemical types of groundwater in the spring area were mainly HCO₃-Ca·Mg and HCO₃·SO₄-Ca·Mg types. The main controlling factor of groundwater chemical evolution in the research area was rock weathering. Ca²⁺, Mg²⁺, SO₄^2- and HCO₃^- in the groundwater mainly came from the weathering of carbonates (calcite (CaCO₃) and dolomite (CaMg(CO₃)₂) and sulfate (CaSO₄·2H₂O). In addition, a certain part of SO₄^2- came from the oxidization of pyrite. The dedolomitization caused the Mg²⁺ content in the groundwater was significantly higher in the dry season than in the wet season. The cation exchange reduced Na⁺ and K⁺ contents in the groundwater. The stable isotope characteristics showed that the karst groundwater was supplied mainly by rainfalls in exposed western areas, while the karst groundwater in the south area (near the Qihe river) was also affected by the seepage of river water. The karst groundwater showed a ¹⁸O drift phenomenon in the during the dry season. This study provided a scientific basis for the better development and protection of karst groundwater in spring areas of north China.