雅鲁藏布江流域枯水期化学风化及 CO2 消耗

基于雅鲁藏布江流域枯水期干支流地表径流、泉水、地下水以及降水样品,对主要离子、pH、TDS和CO_2消耗进行分析,研究枯水期水化学特征及成因,并分析流域化学风化速率及CO_2消耗通量。结果表明:流域水体总体呈现弱碱性,地表径流TDS均值约为世界河流的2.3倍,和长江流域相似,但远低于黄河流域。岩石风化是地表径流离子来源的主要影响因素。碳酸盐风化、硅酸盐风化和蒸发盐风化分别占离子来源的46.3%、28.6%和21.3%,碳酸盐风化速率和硅酸盐风化速率分别为1.43t/(km~2·a)和1.11t/(km~2·a),对应的CO_2消耗速率为0.80×10~5mol/(km~2·a)和0.55×10~5 mol/(km~2·a),枯水期化学风化速率和CO_2消耗速率较小。

Study on chemical weathering and consumption of CO2 during dry season in the Yarlung Zangbo River Basin

Based o n t he surface runoff, spring w ater, g r oundwater, and pr ecipitatio n samples obtained in the dry seaso n from the main t ributaries o f Yarlung Zangbo River basin, the main ions, pH , TDS and CO2 co nsumpt ion wer e analyzed. The hy dr ochemi2 cal char act eristics and causes w ere studied. T he chemical w eathering r ate and CO2 co nsumption flux in the basin w ere also ana2 lyzed. The results indicated that t he basin water w as mild alkaline as a who le. The mean T DS of surface runoff was appro x i2 mately 21 3 times compared t o the wo rldcs rivers. It w as similar to the Yang tze River Basin but far below the Yellow River Ba2 sin. Rock weathering was the main facto r affecting the ion sour ce of surface runoff. Carbonate weathering , silicate w eathering and evapor at e w eathering acco unted for 461 3% , 281 6% , and 211 3% o f the io n so ur ces, respect ively. The carbonate w eathering rate and silicate rat es w ere 11 43 t/ ( km2. a) , and 11 11 t/ ( km2 . a) , the correspo nding CO2 co nsumpt ion r ates wer e 01 80 @ 105 mol/ ( km2 . a) and 01 55 @ 105 mol/ ( km2 . a) , w hile the chemical w eathering and CO2 consumptio n r ates w ere found lower in dry season.