δ^(13)C-Δ^(14)C探究黄土高原治沟造地区水库溶解性无机碳的迁移转化过程

Usingδ^(13)C-Δ^(14)C to Trace the Source of Dissolved Inorganic Carbon in Reservoirs in the Consolidated Area on the Loess Plateau

水库不断参与着陆地和水体生态系统的物质交换,其中溶解性无机碳(DIC)在全球和区域碳循环中起着重要作用。为揭示治沟造地活动后的水库DIC来源、迁移转化过程,对黄土高原治沟造地区新造农田附近的水库夏冬季水体理化参数、DIC含量进行了测定,并利用双碳同位素(δ^(13)C-Δ^(14)C)示踪水库夏冬季DIC的来源。研究表明,顾屯水库DIC在夏、冬季分别为(32.3±9.9)、(32.4±2.7)mg/L,差异较小;水库夏季水体的δ13C_(DIC)均值为-8.23‰±1.88‰,Δ^(14)C_(DIC)均值为-233.96‰±93.89‰,水库冬季水体δ13C_(DIC)均值为-9.56‰±1.05‰,Δ^(14)C_(DIC)均值为-315.99‰±96.06‰,冬季较夏季偏负;夏季水库的DIC主要来源为附近土壤,贡献率为47%;沉积物孔隙水、大气和入库水是次贡献来源;在冬季,入库泉水为主要来源,附近土壤贡献率略低,分别为35%、30%,冬季沉积物及其孔隙水为次贡献来源。在冬夏两季,附近土壤对水库DIC的贡献均不可忽视。

Reservoirs are constantly involved in material exchange between terrestrial and aquatic ecosystems,where dissolved inorganic carbon(DIC)plays an important role in global and regional carbon cycling.In order to reveal the source and the migration transformation process of DIC in reservoirs after consolidated activities,the physicochemical parameters and the DIC content of water in the Gutun reservoir near a newly-built cropland of the Loess Plateau were measured in summer and winter,and the source of DIC was traced by using dual carbon isotopes(δ^(13)C-Δ^(14)C).The results showed that the DIC content of the reservoir water was(30.3±5)and(32.4±2.7)mg/L in summer and winter,respectively,with small differences.The mean values ofδ13C_(DIC)andΔ^(14)C_(DIC)of the reservoir water were-8.23‰±1.88‰and-233.96‰±93.89‰in summer and-9.56‰±1.05‰and-315.99‰±96.06‰in winter,respectively,and the winter values were more negative than the summer values.In summer,the main source of DIC in the reservoir water was nearby soil,with a contribution of 47%,and sediment pore water,atmosphere and inlet water were secondary contributing sources;in winter,the main sources of DIC in the reservoir water were inlet spring water and the nearby soil,with contributions of 35%and 30%,respectively,and sediment and pore water was the secondary contributing source.In both winter and summer,the contribution of nearby soil to DIC of the reservoir water was not negligible.