富氡地热水中δ^(34)S_(so4)^(2-)、δ^(13)C_(DIC)同位素特征及其意义——以息烽温泉为例  

Characteristics of δ^(34)S_(so_(4)^(2-)) and δ^(13)C_(DIC) isotopes in radon-rich geothermal water and their significance——Xifeng hot spring as an example

作　　者：张中欣 罗腾 陈正山[3] 陈刚 杨晨 肖吉 ZHANG Zhongxin;LUO Teng;CHENG Zhengshan;CHEN Gang;YANG Chen;XIAO Ji(Shandong Geological Exploration Institute of China Chemical Geology and Mine Bureau,Jinan,250013,China;Sichuan Zhide Geotechnical Engineering Co.,Ltd.,Chengdu,610041,China;School of Resources and Environmental Engineering,Guizhou University,Guiyang,550025,China)

机构地区：[1]中化地质矿山总局山东地质勘查院,济南250013 [2]四川志德岩土工程有限责任公司,成都610041 [3]贵州大学资源与环境工程学院,贵阳550025

出　　处：《环境化学》2022年第2期643-652,共10页Environmental Chemistry

基　　金：贵州省地勘基金(2017-02号);贵州省地矿局地质科研项目(黔地矿科合[2019]20)资助。

摘　　要：贵州息烽温泉被誉为“亚洲第一氡泉”,富含多种有益元素。选取息烽地热水和与其有关的地表径流水及岩溶泉水为研究对象,利用水文地球化学、δ^(34)S_(SO_(4)^(2-))、δ^(13)C_(HCO_(3)^(-))同位素等方法对区内富氡地热水中硫、碳元素来源及水-岩作用过程进行研究。结果显示,地热水水化学类型为HCO_(3)·SO_(4)−Ca·Mg型,pH呈弱碱性,其阴离子主要为HCO_(3)^(−)和SO_(4)^(2−),阳离子主要Ca^(2+)和Mg^(2+),阴离子浓度变化范围为86—191.01 mg·L^(−1),阳离子浓度变化范围为20.7—57.4 mg·L^(−1)。地热水中δ^(13)C_(HCO_(3)^(−))值为−4.85‰—−9.12‰,计算得出CO_(2)的δ^(13)C_(CO_(2))值集中在−10.34‰—−13.99‰间,其参与水-岩反应的CO_(2)为幔源和土壤混合成因。δ^(34)S_(SO_(4)^(2-))值为25.41‰—27.53‰,与区内寒武系娄山关岩组中石膏中的δ^(34)S_(SO_(4)^(2-))值(26.73‰—29.57‰)一致。结合地热水中的阴阳离子含量、δ^(34)S_(SO_(4)^(2-))值和δ^(13)C_(HCO3)^(-)值的分析,可以认为大气降水入渗寒武系娄山关组碳酸盐岩地层发生的水岩反应主要为石膏的溶解,其次CO_(2)进入含水层与围岩发生水岩作用生成HCO_(3)^(−)。Guizhou Xifeng hot spring is known as“the No.1 Radon spring in Asia”and is rich in various beneficial elements.A number of methodologies such as hydrogeochemical analysis and δ^(34)S_(so_(4)^(2-)),δ^(13)C_(HCO_(3)^(-))isotope are applied to reveal the source of sulfur and carbon in the radon-rich hot water,related surface water and karst spring in the area.The process of water-rock interaction is also studied.The results show that the hydro-chemical type of the geothermal water is HCO_(3)^(−)·SO_(4)^(2−)−Ca·Mg with a weakly alkaline pH.The anions are mainly HCO_(3)^(−) and SO_(4)^(2−),the cations are mainly Ca^(2+) and Mg^(2+).And the anion concentration frange rom 86—191.01 mg·L^(−1)while the cation concentration varie from 20.7—57.4 mg·L^(−1).The δ^(13)C_(HCO_(3)^(−))value in geothermal water is−4.85‰—−9.12‰,and the calculated δ^(13)C_(CO_(2))value of CO_(2) is between−10.34‰—−13.99‰.The CO_(2) involved in the water-rock interaction is caused by the mixing of mantle source and soil.The value of δ^(34)S_(SO_(4)^(2−)) value is 25.41‰—27.53‰,which is consistent with the δ^(34)S_(SO_(4)^(2−))value(26.73‰—29.57‰)in gypsum in the Cambrian Loushan guan Formation.Combined with the analysis of the anion and cation content in the geothermal water,δ^(34)S_(SO_(4)^(2−))value and δ^(13)C_(HCO_(3)^(−))value,it could be considered that,during the infiltration process of rainwater enters the carbonate formation of the Cambrian Lushanguan Formation,the water-rock reaction is mainly gypsum dissolution.Secondly,CO_(2) enters the aquifer and interacts with the surrounding rock to produce HCO_(3)^(−).

关 键 词：δ^(34)S_(SO_(4)^(2-)) δ^(13)C_(HCO_(3)^(-))水-岩作用 富氡地热水 贵州息烽 

分 类 号：P314.1[天文地球—固体地球物理学]