Abstract:

 Carbon sink produced during rock weathering is an important part of global carbon cycle. Therefore, more and more attention has been paid to this field by the scientists who focus on the global warming. In this work, the source of ion of the rivers and carbon sink produced by rock weathering in Poyang Lake drainage basin are studied based on the systematic sample collection and chemical composition analysis of river water samples from this area. Taking precipitation, evaporation rock, silicate rock and carbonate rock as four endmember components, we have calculated their contribution rates to the total dissolved mass(TDS) of Poyang Lake water system, which are 10.4%, 21.9%, 30.0% and 37.8% respectively. The chemical weathering rates of the basin of Xiushui River, Ganjiang River, Fuhe River, Xinjiang River and Raohe River are 27.22, 5050, 7030, 64.62 and 63.94  t·km-2·a-1, respectively, while the erosion rates in these areas are 1134, 2104, 29.29, 26.92 and 26.64 mm · ka-1. Two models were used to calculate the quantity of CO₂ consumption during chemical weathering in the drainage area. One method is based on the result of ionic source analysis. In the basin of Poyang Lake, Xiushui, Ganjiang River, Xinjiang River and Raohe River, the CO₂ consumptions are 74.39, 4.92, 4106, 4.49, 4.85, 4.09×109 mol · a-1, and the contribution of silicate weathering rates are 34.3%, 76.6%, 28.9%, 604%, 58.8% and 32.8%. The other method is using GEMCO₂ model to calculate chemical weathering rate in drainage areas respectively. The CO₂ consumption are 45.08, 4.23, 23.26, 3.14, 6.76 and 3.94×109 mol · a-1. Compared the data from  the two methods, the results of the CO₂ consumption are considered between 4.5×1010 mol · a-1 and 7.4×1010 mol · a-1.

Key words:  , CO2 consumption； chemical weathering； weathering rate； Poyang Lake Basin