东江流域化学风化对大气CO2的吸收

对东江化学径流进行分析,使用质量平衡法和扣除法估算了流域化学风化对大气CO2的吸收通量.结果表明,东江水体的总溶解性固体(TDS)含量均值(59.88 mg·L-1)远低于世界河流均值(100 mg·L-1);离子组成以Ca2、Na+和HCO3-为主,可溶性Si次之,径流对总溶解固体的稀释效应由于受人类活动影响表现得并不明显.东江化学径流组成主要源自硅酸盐矿物的化学风化过程的贡献(72.46％～81.54％),其次为海盐贡献(17.65％～26.05％),碳酸盐矿物的贡献很少(0.81％ ～3.87％)；大气CO2是流域内岩石化学风化的主要侵蚀介质,但H2SO4和HNO3的作用也不可忽视；东江流域岩石化学风化过程对大气CO2的消耗通量(3.02～3.08) x105 mol·km-2·a-1高于全球平均值,是全球岩石风化碳汇的一个重要组成部分.

Chemical weathering and CO2 consumption in the Dongjiang River Basin

Chemical runoff of Dongjiang River was investigated, and the mass balance approach and deduction methods were used to estimate the uptake of atmospheric CO₂ through rock chemical weathering. We conclude that the concentration of total dissolved solids in the Dongjiang River (59.88 mg·L^-1) is far lower than the averages of rivers worldwide (100 mg·L^-1) and the chemical composition of the river is dominated with Ca²⁺, Na⁺ and HCO₃^-, followed by dissolved Si. The dilution effect of the surface runoff on riverine total dissolved solids is not obvious due to human activities. Chemical runoff of the Dongjiang River is mainly derived from the chemical weathering of silicate mineral (72.46%~81.54%), followed by sea salt (17.65%~26.05%), while the contribution from the chemical weathering of carbonate minerals (0.81%~3.87%) is insignificant. Atmospheric CO₂ is the main aggressive medium in the rocks chemical weathering within the basin. The CO₂ consumption flux (3.02×10⁵~3.08×10⁵ mol·km^-2·a^-1) of chemical weathering processes in the Dongjiang River Basin is higher than that of the global average, which constitutes an important component of CO₂ consumption in the global rocks chemical weathering.