许家沟泉域岩溶地下水δ^(13)C_(DIC)特征及碳汇效应

Characteristics ofδ^(13)C_(DIC)of karst groundwater and carbon sink effect in Xujiagou spring area

为确定许家沟泉域水岩相互作用过程中的碳汇效应,选取22个采样点分期采样进行水化学和同位素分析,利用同位素技术和水化学方法对泉域内碳同位素特征和岩溶碳汇效应进行了研究。结果表明:丰水期岩溶地下水δ^(13)C为-12.16‰~-7.11‰,平均-9.93‰,岩溶作用所形成的溶解无机碳主要来源于土壤CO_(2),枯水期岩溶地下水δ^(13)C为-11.03‰~-2.88‰,平均-8.00‰,溶解无机碳来源于大气CO_(2)较明显,赋存环境在丰水期对地下水中CO_(2)来源的影响较大;碳酸参与碳汇效应平均贡献率丰水期为46.37%,枯水期为32.14%。不同季节,不同赋存环境下碳酸参与碳汇效应的贡献率不同,丰水期深埋区最大,裸露区最小,分别为54.76%和39.90%;而枯水期则反之,裸露区为35.25%,深埋区为14.67%。

In order to determine the carbon sink effect in the process of water-rock interaction in Xujiagou spring area,22 sampling points were selected for hydrochemistry and isotope analysis,and the carbon isotope characteristics and karst carbon sink effect in the spring area were studied by using isotope technology and hydrochemistry.The results show that:Karstic groundwaterδ^(13)C in the wet season is-12.16‰~-7.11‰,with an average of-9.93‰.Dissolved inorganic carbon formed by karstic processes mainly comes from soil CO_(2).Karstic groundwaterδ^(13)C in the dry season is-11.03‰~-2.88‰,with an average of-8.00‰.It is obvious that dissolved inorganic carbon comes from atmospheric CO_(2),and the occurrence of the environment has a great influence on the source of CO_(2)in groundwater during the wet season.The average contribution rate of carbonic acid to carbon sink effect is 46.37%in the wet season and 32.14%in the dry season.In different seasons,the contribution rate of carbonic acid to the carbon sink effect is different under different occurrence environments.The deep-buried area is the largest in the wet season and the bare area is the smallest,54.76%and 39.90%respectively;while in the dry season,the reverse is 35.25%in the bare area.The deep buried area is 14.67%.