秭归岩溶流域锶的分布特征与富集规律

Distribution and enrichment of strontium in the Zigui karst watershed

为探究岩溶地区水流系统控制下地下水中锶的分布现状及富集规律,本文以秭归茅坪河与九畹溪两个岩溶小流域为研究对象,于2016—2018年期间针对研究区典型泉点、典型断面地表水以及主要含水岩组的岩样进行了采集,共分析了415组水样数据,93组岩矿分析数据。研究结果表明:区域上锶多富集在以潮坪-潟湖沉积相沉积的嘉陵江组、娄山关组、灯影组地层中,且多以天青石、菱锶矿等矿物等形态存在;富锶地下水水化学类型主要为SO_(4)型和Cl型;在水流系统结构上,包气带以上地层中富锶矿物较少,主要受淋虑作用影响,浅循环地下水中的天青石与菱锶矿均未达到饱和,在少数深循环地下水流中趋于达到饱和状态;封闭还原且富含石膏、天青石的环境下有利于地下水中锶的富集。

In order to explore the distribution and enrichment of strontium in groundwater under the control of water flow system in karst area,the Maoping river and Jiuwanxi karst watershed in Zigui were taken as the study case,and 415 groups of water samples and 93 groups of rock samples were collected from typical springs,typical surface water and main water-bearing rocks during 2016-2018.The analytical results indicate that strontium is mainly enriched in the strata of the Jialingjiang Formation,Loushanguan Formation and Dengying Formation deposited in tidal flat and lagoon sedimentary facies,and mostly exists in the form of celestite,strontianite and other minerals.The water type of Sr-rich groundwater is mainly SO_(4) type,Cl type,and SO_(4)-HCO_(3) type.In the water flow system,,the strontium-rich minerals are less in strata above vadose zone,mainly affected by leaching;both celestite and strontianite are not saturated in shallow groundwater,but they tend to be saturated in a few deep groundwater.The closed reduction environment rich in gypsum and celestite is conducive to the enrichment of strontium in groundwater.