环境同位素示踪的毛村地下河流域水流特征  

Water flow characteristics of Maocun underground river basin based on environmental isotopes

作　　者：郭永丽 吴佩艳 黄芬[1] 孙平安[1] 苗迎[1] 刘绍华[1] GUO Yongli;WU Peiyan;HUANG Fen;SUN Ping’an;MIAO Ying;LIU Shaohua(Institute of Karst Geology,CAGS/Key Laboratory of Karst Dynamics,MNR&GZAR,Guilin,Guangxi 541004,China)

机构地区：[1]中国地质科学院岩溶地质研究所/自然资源部、广西岩溶动力学重点实验室,广西桂林541004

出　　处：《中国岩溶》2022年第4期577-587,共11页Carsologica Sinica

基　　金：国家重点研发计划项目(2019YFC0507504,2021YFE0107100);广西自然科学基金项目(2021GXNSFBA075013,2018GXNSFDA050002,桂科AB22035010);国家重点研发计划项目(2020YFE0204700);基本科研业务费(2021001);中国地质调查项目(DD20221820)。

摘　　要：岩溶水文特征是岩溶区生态环境可持续发展的关键驱动力。文章利用环境同位素示踪剂反馈的水动力过程,解译毛村地下河流域的水流特征。其流域内水体δD和δ^(18)O范围均位于大气降水δD和δ^(18)O的范围内,大气降水是流域主要的补给来源;基于δ^(13)C_(DIC)利用质量守恒定律计算岩溶水体中DIC来源于碳酸盐岩溶解的平均值为52.13‰,可揭示相关的水—碳酸盐岩相互作用历程;流域内岩溶水点^(222)Rn和EC值对大气降水的响应特征表明降水的蓄积作用可驱动深层岩溶裂隙水运移,且具有较强的稀释作用;基于^(222)Rn的衰变特征,计算6月份地下河管道有效水流速度为2427.49 m·d^(−1);西南岩溶地下河水流与地表水流相似,且对降水响应敏感。综合毛村地下河流域的水文地质条件及其水文点SI、^(222)Rn、δ^(13)C_(DIC)和δ^(18)O间的相关关系,环境同位素可更好地示踪岩溶裂隙水流特征,揭示岩溶含水系统的空间结构特征及水流路径。水化学环境天然示踪剂可提供有关岩溶含水系统的重要信息,对水动力学方法具有重要的补充作用。Underground river basins in peak-cluster depressions are main water supply sources of villages in Guangxi.But there exist problems of groundwater exploitation,groundwater pollution and natural disasters in these areas due to a special geological structure.Besides,the karst hydrological process is critical driving force for the sustainable development of ecological environment in karst areas;therefore,understanding mechanism of hydrological process is the key to the problem of ecological environment.Hydrochemical characteristics are closely related to hydrodynamics in a karst groundwater system,and hydrochemical tracers have been successfully used to indicate recharging sources,flow paths and water flow velocities.Taking Maocun underground river basin in peak-cluster depression in Guilin,Guangxi as an example,we interpret water flow characteristics in the study area based on the hydrodynamic processes indicated by hydrochemical environmental tracers.Temporal and spatial variations of isotopes and their influence factors,especially those of stable environmental isotopes as natural tracers of water cycle,are suitable for indicating water flow characteristics and hydrodynamic processes in karst areas.Variation ranges ofδD andδ^(18)O of karst water samples fall in the ranges of local precipitation,indicating that precipitation is the main recharge source in the study area.Dissolved inorganic carbon(DIC)in karst water is approximately equal to HCO_(3)^(-),and the concentration of HCO_(3)^(-) is mainly affected by dissolution of carbonates and soil CO_(2).Based on isotopes ofδ^(13)C_(DIC)and the linear mass conservation,the average value of DIC from carbonates dissolution is 52.13‰,which can be used to interpret the water-carbonate interaction.In southwestern karst areas,karst is well developed with the characteristics of special dual structure.Surface water and shallow groundwater is well connected,the retention time of shallow groundwater is short,and hydrological processes are sensitive to precipitation or artif

关 键 词：环境同位素 毛村地下河流域 水流 空间结构 

分 类 号：X143[环境科学与工程—环境科学]