不同降水条件下岩溶碳汇效应的同位素监测  

Isotope Monitoring of Karst Springs Carbon Sink Under Different Precipitation Conditions

作　　者：张月明 何迁 张乾柱[3] 冉静 王建东 朱超 ZHANG Yueming;HE Qian;ZHANG Qianzhu;RAN Jing;WANG Jiandong;ZHU Chao(Huai’an Hydraulic Survey and Design Research Institute Co.,Ltd.,Huai’an 223005,China;College of Architecture and Urban Planning,Chongqing Jiaotong University,Chongqing 400074,China;Chongqing Branch,Changjiang River Scientific Research In-stitute,Chongqing 400026,China)

机构地区：[1]淮安市水利勘测设计研究院有限公司,江苏淮安223005 [2]重庆交通大学建筑与城市规划学院,重庆400074 [3]长江水利委员会长江科学院重庆分院,重庆400026

出　　处：《三峡生态环境监测》2022年第4期82-89,共8页Ecology and Environmental Monitoring of Three Gorges

基　　金：岩溶环境重庆市重点实验室开放课题(Cqk202101);山东省地下水环境保护与修复工程技术研究中心(筹)开放基金项目(801KF-2021-10)。

摘　　要：为分析不同降水条件下岩溶泉水化学性质的变化特征及影响机制,本研究于2020年10月7日和2020年10月31日对重庆南山8个岩溶泉进行了对比监测。结果显示:相对于7日,31日各监测点的水温和溶解氧均表现为下降趋势,而pH均表现为上升趋势,但各监测点电导率、HCO_(3)^(-)浓度的变化特征却并不相同;各监测点溶解无机碳的稳定碳同位素(δ^(13)C_(DIC))均表现为31日偏正于7日,氘同位素(δD)和氧同位素(δ^(18)O)也均表现为31日偏正于7日,且各监测点氘盈余(d-excess)均表现为31日大于7日。这说明31日降水减少,增加了水岩接触时间,同时,泉水出露后在岩溶潭中滞留时间也随之增加,水体CO_(2)脱气作用加剧,进而使部分监测点的电导率及HCO_(3)^(-)浓度降低。To analyze the variation characteristics and influence mechanism of karst springs’chemical propersties under different precipitations,eight karst springs were monitored by isotopes measurement on 7^(th) and 31^(st) October,2020 at Nanshan,Chongqing.The results show that water temperature and dissolved oxygen on 31^(st) October were lower than those on 7^(th) October while the pH on 31^(st) October was higher than that on 7^(th) for all monitored sites.However,the variation characteristics of conductivity and HCO_(3)^(-)con⁃centration among the sites were different.The stable carbon isotopes of dissolved inorganic carbon(δ^(13)C_(DIC))at all the sites were higher on 31^(st) October than on 7^(th) October,and the conductivity and HCO_(3)^(-)concentration also increased at some monitor sites.TheδD,δ^(18)O and d-excess were higher on 31^(st) October than on 7^(th) October at all the sites.These features indicated that the decrease in pre⁃cipitation on 31^(st) October not only increased the contact time between water and rock,but also increased the retention time of the spring water in the pool.Then evaporation enhanced CO_(2)degassing of the water resulting in high δ^(13)C_(DIC),δD,δ^(18)O and d-excess but low conductivity and HCO_(3)^(-)concentration at some monitoring sites.

关 键 词：岩溶 碳循环 降水条件 同位素 脱气作用 

分 类 号：X142[环境科学与工程—环境科学]