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水坝拦截引起的生物地球化学影响越来越引起人们的重视。本文以我国西南喀斯特地区新建的洪家渡水库为例,详细分析了该水库入库水体、出库水体和水库坝前水体的溶解无机碳含量(D IC)及其同位素组成(1δ3CD IC)特征。结果表明:河流经水库作用后水体无机碳体系发生显著变化。洪家渡水库入库水体D IC和1δ3CD IC值的年均分别为2.14 mmol/L和-6.6‰,库区表层水体为2.12 mmol/L和-6.5‰,出库水体为2.22mmol/L及-8.6‰。总体上,入库水体D IC含量低于出库水体,而溶解无机碳同位素组成却比出库水体偏正。就全年平均而言,出库水体的D IC浓度比入库水体和库区表层水体中分别高出3.7%和4.7%;同时,其D IC的同位素组成相对更偏负,出库水体中δ13CD IC值比入库水体和库区表层水体分别偏负30.3%和32.3%。在垂直剖面上,水体中D IC含量随着深度的增加而增高,1δ3CD IC值随水深的增加而偏负。由于水库为底层泄水,使得出库水体中D IC含量增高,而δ13CD IC值偏负。河流受水坝拦截后,水化学特征发生显著改变,逐渐向湖沼型方向演化。
The biogeochemical influence caused by dam interception has drawn more and more attention. Taking Hongjiadu newly built reservoir in Southwest Karst area of China as an example, the characteristics of dissolved inorganic carbon (D IC) and its isotopic composition (1 δ3CD IC) in the water body, the reservoir body and the reservoir before the dam are analyzed in detail. . The results show that there is a significant change of inorganic carbon in the water after the reservoir has been operated by the reservoir. The average annual values of D IC and 1δ3CD IC of Hongjiadu reservoir were 2.14 mmol / L and -6.6 ‰, respectively. The surface water bodies in the reservoir area were 2.12 mmol / L and -6.5 ‰, -8.6 ‰. In general, the D IC content of the inflowing water body is lower than that of the discharged water body, while the dissolved inorganic carbon isotope composition is more positive than that of the discharged water body. For the whole year, the concentration of D IC in outflowing water body was 3.7% and 4.7% higher than that in the surface water of entering water body and reservoir area, respectively. Meanwhile, the isotopic composition of D IC was relatively more negative, The δ13CD IC value is 30.3% and 32.3% lower than that of the surface water in the reservoir and the reservoir. In the vertical section, the content of D IC in water increases with depth, and the value of 1δ3CD IC decreases with the increase of water depth. Due to the reservoir drainage for the bottom, making the D IC content of the reservoir water increased, while the δ13CD IC value negative. After the river was intercepted by the dam, the chemical characteristics of the water changed significantly and gradually evolved into the direction of the lake marsh.