滇东黔西典型岩溶流域地下水中锶富集特征及成因分析

Characteristics and genesis of strontium enrichment in groundwater of typical karst basins in Eastern Yunnan and Western Guizhou

滇东黔西岔河岩溶流域地下水和地表水中锶超常富集,研究富锶地下水的分布特征和成因机理,可以为天然富锶矿泉水的开发利用提供支撑.通过对含水介质中锶元素含量、地下水分布和水化学特征的分析,结合氢氧同位素和^(87)Sr/^(86)Sr比值、离子比例系数和Piper三线图、Gibbs图解等方法,研究了地下水中Sr的来源和成因.结果表明,永宁镇组(T_(1)yn)和关岭组(T_(2)g)岩石中锶含量较高,是地下水中锶的主要来源层位.研究区地表水和地下水均以大气降雨补给为主,水化学类型主要为HCO_(3)-Ca和HCO_(3)-Ca·Mg型,优势阴阳离子为HCO_(3)^(-)、Ca^(2+)和Mg^(2+).地表水和地下水水化学均受岩石风化作用的控制,溶滤作用、阳离子交换作用和人类活动综合影响了区内水体的组分特征.水-岩作用是锶在地下水中富集的主要途径,方解石的风化溶解是地下水中Sr的主要来源,白云石和石膏也有一定的贡献;阳离子交换作用不利于锶在地下水中的富集,人类活动有利于锶从碳酸盐岩中释放,但作用均较有限.

Strontium(Sr)in groundwater and surface water of Chahe karst basin in Western Guizhou and eastern Yunnan is extremely enriched.The study on the distribution characteristics and genetic mechanism of Sr-rich groundwater can provide support for the development and utilization of natural Sr-rich mineral water.Based on the analysis of strontium content in aquifer,groundwater distribution and hydro-chemical characteristics,combined with hydrogen and oxygen isotopes,^(87)Sr/^(86)Sr ratio,ion proportion coefficient,Piper diagram and Gibbs diagram,the source and genesis of Sr in groundwater were studied.The results show that both the Yongningzhen Formation(T_(1)yn)and the Guanling Formation(T_(2)g)have high Sr content and are the main source of Sr in groundwater.The surface water and groundwater in the study area are mainly supplied by rainfall,the hydro-chemical types of surface water and groundwater are HCO_(3)-Ca and HCO_(3)-Ca·Mg,and the dominant cations are HCO_(3)^(-),Ca^(2+)and Mg^(2+).The hydro-chemical characteristics of surface water and groundwater are mainly controlled by rock weathering,and the solute composition of water in the area is affected by lixiviation,cation exchange and human activities.Water-rock interaction is the main way of Sr enrichment in groundwater,the weathering dissolution of limestone is the main source of Sr in groundwater,and the dissolution of dolomite and gypsum also contributes.Cation exchange is not conducive to the enrichment of Sr in groundwater,while human activities is conducive to the release of Sr from carbonate rocks,but both have limited effects.