鄱阳湖流域岩石化学风化特征及CO2消耗量估算

摘要

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. 09×10^9 · 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. 94×10^9 · mol · a^-1. Compared the data from the two methods, the results of the CO2 consumption are considered between 4. 5×10^10 · mol · a^-1 and 7. 4×10^10· mol · a^-1.%岩石风化过程中所产生的碳汇是全球碳循环的重要组成部分，该领域受到研究全球变化科学家们的普遍关注。文中通过对鄱阳湖流域河水系统的样品采集和化学成分分析，研究了河水化学成分来源及流域岩石风化所产生的碳汇效应。以大气降水、蒸发岩、硅酸岩和碳酸盐岩为4个端员，计算出它们对河水中溶解质的贡献率分别为10．4％、21．9％、30．0％和37．8％。修水、赣江、抚河、信江和饶河各流域的化学风化速率分别为27．22、50．50、70．30、64．62和63．94t·km^-2·a^-1，剥蚀率为11．34、21．04、29．29、26．92和26．64m·ka^-1。采用两种模型对流域内化学风化作用CO2消耗量进行计算：其一是根据离子来源分析所得的数据，求得鄱阳湖、修水、赣江、抚河、信江和饶河流域CO2消耗量为：74．39、4．92、41．06、4．49、4．85和4．09×10^9· mol · a^-1，硅酸岩风化贡献率分别占34．3％、76．6％、28．9％、60．4％、58．8％和32．8％；其二是利用GEM-C02模型计算出各流域CO2消耗量分别为45.08、4．23、28．26、3．14、6．76和3．94×10^9· mol · a^-1。对比两种模型所得数据，认为鄱阳湖流域风化CO2消耗量应为（4．5～7．4）×10^10· mol · a^-1．