喀什噶尔河流域平原区深层承压水咸化机理研究

Study on salinization mechanism of deep confined water in the plain of Kashgar River Basin

为了解新疆喀什噶尔河流域平原区深层承压水咸化情况,于2016年6—11月采集13组深层承压水样品进行水化学(K^+、Na^+、Ca^2+、Mg^2+、HCO3^-、CO3^2-、SO4^2-、Cl^-和TDS)及氢氧稳定同位素测试,运用数理统计、相关性分析、Piper三线图、矿物饱和指数法揭示研究区深层承压水咸化主要机理。结果表明:研究区深层承压水趋于咸化,淡水、微咸水、咸水的比例分别为46.1%、23.1%、30.8%;研究区深层承压水补给来源主要为大气降水,氢稳定同位素(δD)变化范围为-92.7‰^-58.2‰,平均值为-76.9‰,氧稳定同位素(δ18O)变化范围为-12.8‰^-7.8‰,平均值为-10.6‰;地下水氘盈余值(d)变化范围为-1.50‰~18.70‰,平均值为7.68‰。地下水的咸化受水岩相互作用影响,其中地下水阳离子交换作用明显,溶滤作用是地下水咸化的主要影响因素。

In order to understand the salinization of deep confined water in the plain of Kashgar River Basin of Xinjiang,13 groups of deep confined water samples were collected from June to November 2016 for hydrochemical properties including K^+,Na^+,Ca^2+,Mg^2+,HCO3^-、CO3^2-、SO4^2-,Cl^-,TDS,and hydrogen and oxygen stable isotopes tests.The mathematical statistics,correlation analysis,Piper diagram and mineral saturation index method were used to explore the main mechanism of deep confined water salinization.The results showed that the deep confined water tended to salinization.The proportion of fresh water,brackish water,and saltwater water samples in deep confined water were 46.1%,23.1%,and 30.8%,respectively.The main recharge source of deep confined water in the study area was atmospheric precipitation.The variation range of hydrogen stable isotopes(δD)was between-92.7‰and-58.2‰,with the average of-76.9‰,and the variation range of oxygen stable isotopes(δ18O)was between-12.8‰and-7.8‰,with an average of-10.6‰.The deuterium excess values(d)in groundwater ranged between-1.50‰and 18.70‰,with an average of 7.68‰.The salinization of deep confined water in the study area was affected by water-rock interaction,in which the cations exchange effect of groundwater was obvious.Lixiviation was the main factor influencing groundwater salinization.