广东省信宜-廉江地区地热水中氟的富集过程

Fluoride enrichment in geothermal waters in Xinyi-Lianjiang region,Guangdong

为查明信宜-廉江地区地热水中氟的富集过程,于2018年4月采集地热水、河水和井水样品23组,采用Piper三线图、Gibbs图和同位素分析来探究高氟地热水的化学特征和分布规律,结合饱和指数、离子比例系数和相关性分析等方法揭示了高氟地热水的富集过程.结果显示,超过65%样品F^-含量大于1 mg·L^-1,热水样品中超过83%的样品F-含量大于1 mg·L^-1,高氟水的水化学类型主要为HCO3-Na型,高氟水表现出富钠、贫钙、弱碱性的特点;氢氧同位素数据表明地热水主要来源于大气降水,高氟水循环路径相对较长;水岩作用和含氟矿物的溶解是地热水中氟的主要来源,含钙矿物的溶解沉淀,吸附解吸作用和阳离子交换作用是地热水氟富集的主要影响因素.

To investigate the enrichment of fluoride in geothermal water in Xinyi-Lianjiang region, a total number of 23 sets of water samples were collected including geothermal water, river water and groundwater. Piper diagrams, Gibbs chart and isotopes analysis were applied to explore the chemical characteristics and distribution of high fluoride geothermal water. And the enrichment of fluoride in geothermal water was revealed with Saturation index, ion ratio analysis and correlation analysis methods. The results indicated that more than 65% of the samples had a fluoride content above 1 mg·L^-1, and more than 83% of the samples was the hot water samples have a fluoride content above 1 mg·L^-1, and the geothermal water containing high fluoride was dominated by the hydrochemical type of HCO3-Na. High fluoride groundwater showed high concentrations of Na^+, low concentration of Ca^2+ and weakly alkaline. The hydrogen and oxygen isotope data indicated that geothermal water was mainly derived from precipitation, and the longer circulation paths existed in high fluoride water. The major fluoride of the geothermal water came from water rock action and dissolution of fluoride-containing minerals. And dissolved sedimentation of calcium-containing minerals, adsorption-desorption and cation exchange were the main influencing factors of fluoride enrichment in geothermal water.