雅鲁藏布江流域水化学特征及碳汇计算

Hydrochemical characteristics and carbon sink calculation in Yarlung Zangbo River Basin

河流是连接海陆两大生态系统的主要通道,也是碳循环的主要参与者之一。以雅鲁藏布江流域为研究对象,采用水化学与元素地球化学方法对雅鲁藏布江流域的水化学特征和碳汇过程进行研究。结果显示:①雅鲁藏布江流域河水总溶解固体(TDS)均值为205.3 mg/L,高于世界河流平均水平;河水中阴离子以HCO_(3)^(-)为主,阳离子以Ca^(2+)为主。②质量平衡模型表明,流域水化学组成以碳酸盐岩风化为主,平均贡献率为56%,硅酸盐岩和蒸发盐岩平均贡献率分别为23%和17%;大气降水输入对河水主要离子的贡献仅为3%。③流域内岩石风化速率为42.03 t/(km^(2)·a),约为世界河流平均岩石风化速率的2倍。受径流流量的影响,丰水期岩石风化速率(72.00 t/(km^(2)·a))远大于枯水期(12.06 t/(km^(2)·a))。④流域内岩石风化CO_(2)消耗速率为407.13×10^(3)mol/(km^(2)·a),远高于世界河流平均水平。其中,碳酸盐岩风化CO_(2)消耗速率平均为232.29×10^(3)mol/(km^(2)·a),硅酸盐岩风化CO_(2)消耗速率平均为174.84×10^(3)mol/(km_(2)·a)。

Rivers are the main channels connecting the ocean ecosystem and the inland ecosystem,and are also the major participants in the carbon cycle.The hydrochemical characteristics and carbon sink process in the Yarlung Zangbo River Basin were studied by the hydrochemical and elemental geochemical methods.The results showed that:①The average value of Total Dissolved Solid(TDS)of the Yarlung Zangbo River was 205.3 mg/L,which was higher than the average value of world s rivers;the HCO_(3)^(-)and Ca^(2+)were the most abundant anion and cation of the river water respectively.②The mass balance model indicated that the chemical composition of the basin water was dominated by the weathering of carbonate rock with an average contribution of 56%,and by weathering of silicate rock and evaporated rock with an average contribution of 23%and 17%respectively;atmospheric precipitation input contributed to the main ion composition only by 3%.③The weathering rate of rock in the basin was 42.03 t/(km^(2)·a),which was approximately twice of the average weathering rate of rock in the world s rivers.The rate of rock weathering in the flood season(72.00 t/(km^(2)·a))was much more influenced by the runoff than in the dry season(12.06 t/(km^(2)·a)).④The rate of CO_(2)consumption from rock weathering in the basin was 407.13×10^(3)mol/(km^(2)·a),which was much higher than the average of the world s rivers.Among these,the average CO_(2)consumption rate of carbonate weathering was 232.29×10^(3)mol/(km^(2)·a),and the average CO_(2)consumption rate of silicate rock weathering was 174.84×10^(3)mol/(km^(2)·a).