Estimation of weathering rates and CO2 drawdown based on solute load: Significance of granulites and gneisses dominated weathering in the Kaveri River basin, Southern India
Estimation of weathering rates and CO2 drawdown based on solute load: Significance of granulites and gneisses dominated weathering in the Kaveri River basin, Southern India
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DOI：
10.1016/j.gca.2013.08.002
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发表时间：
2013-11
影响因子：
5
通讯作者：
J. Pattanaik;S. Balakrishnan;R. Bhutani;P. Singh
中科院分区：
文献类型：
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作者：
J. Pattanaik;S. Balakrishnan;R. Bhutani;P. Singh
溶质负荷的卡韦里河（印度南部）及其支流排水不同的前寒武纪的地形在前季风和季风期间确定。利用这些河流的年平均流量、总流域面积和经大气输入校正的主要离子浓度，估算了化学风化速率、不同离子种类向海洋的年通量和CO2消耗速率。在季风期间收集的所有河流样品中，重金属离子是最主要的离子（占阴离子总量的27-79%），其次是Ca 2+，而在季风前的水样中，Na+是最主要的离子（meq/l）。采用两种方法来估计流域中硅酸盐和碳酸盐的风化速率。穆苏里硅酸盐风化速率为9.44± 0.29t/km 2/a，碳酸盐风化速率为1.46± 0.16t/km 2/a。超过90%的总离子预算是来自风化的硅酸盐在Kaveri盆地。盆地硅酸盐风化CO2消耗速率FCO 2sil为3.83±0.12× 105 mol/km 2/a（上限），与喜马拉雅河上游相当。Kaveri盆地碳酸盐岩风化（FCO 2carb）的CO2消耗速率为0.15±0.03× 105 mol/km 2/a。硅酸盐风化和碳酸盐风化CO2消耗速率的下限分别为FCO 2sil = 3.24× 1005 mol/km 2/a和FCO 2carb = 0.13× 105 mol/km 2/a。Kaveri盆地硅酸盐风化作用封存的CO2为25.41（±0.82）× 109 mol/a，占全球CO2下降量的0.21（±0.01）%。这可能是由于热带气候条件、西南和东北季风期间的高降雨量以及Kaveri盆地硅酸盐岩的优势。
The solute load of the Kaveri River (South India) and its tributaries draining diverse Precambrian terrains during pre-monsoon and monsoon periods was determined. Using average annual flow, total drainage area and atmospheric input corrected major ion concentrations of these rivers chemical weathering rates, annual fluxes of different ionic species to the ocean and CO 2 consumption rates were estimated. Bicarbonate is the most dominant ion (27–79% of anion budget) in all the river samples collected during monsoon period followed by Ca 2+, whereas, in case of pre-monsoon water samples Na+ is the most dominant ion (in meq/l). Two approaches were adopted to estimate silicate and carbonate weathering rates in the drainage basin. At Musuri silicate weathering rate (SWR) is 9.44±0.29 tons/km 2/a and carbonate weathering rate (CWR) is 1.46±0.16 tons/km 2/a. More than 90% of the total ionic budget is derived from weathering of silicates in the Kaveri basin. CO 2 consumption rate in the basin for silicate weathering F CO 2 sil is 3.83±0.12× 10 5 mol/km 2/a (upper limit), which is comparable with the Himalayan rivers at upper reaches. For carbonate weathering (F CO 2 carb) CO 2 consumption rate is 0.15±0.03× 10 5 mol/km 2/a in the Kaveri basin. The lower limit of CO 2 consumption rate corrected for H 2 SO 4 during silicate and carbonate weathering is F CO 2 sil is 3.24× 100 5 mol/km 2/a and F CO 2 carb 0.13× 10 5 mol/km 2/a respectively. CO 2 sequestered due to silicate weathering in the Kaveri basin is 25.41 (±0.82)× 10 9 mol/a which represents 0.21 (±0.01)% of global CO 2 drawdown. This may be due to tropical climatic condition, high rainfall during both SW and NE monsoon and predominance of silicate rocks in the Kaveri basin.