Chemical Denudation Rates and Carbon Dioxide Sink in Koxkar Glacierised Region at the South Slope of Mt. Tianshan,China

Chemical denudation rates and carbon dioxide sink were from water samples from ice-melt water,precipitation and river water were collected daily from June 21st to September 10th in 2004 in the Koxkar glacier region,south slope of Mt. Tianshan,China. The law of conservation of mass was applied for calculating chemical denudation fluxes and transient carbon dioxide sink. It is found that:① There were average of 60. 7 kg.(km2.d) -1 and 60. 2 kg.(km2.d) -1 solutes supplied by precipitation and ice melt-water respectively which accounted for about 7. 7% and 7. 6% of the total solutes of bulk river water [791. 2 kg.(km2.d) -1 ]. Consequently,the rate of chemical denudation derived from the crustal flux was 558. 0 kg.(km2.d) -1 ,accounting for 70. 5%. ② Carbonation weathering was 308. 9 kg.(km2.d) -1 ,and heavier than that of the other chemical denudations. The crustal concentration of bicarbonates ( HCO 3-) is attributed chiefly to the carbonation of carbonates ( limestone and dolomite ) and aluminosilicates /silicates. A further important source of bicarbonates and sulphates is pyrite oxidation coupled with limestone /dolomite dissolution. The transient carbon dioxide sink can be estimated by ion balance law,which is 81. 0 kg.(km2.d) -1 ,accounting for 14. 2%. ③The chemical denudation rates was 641. 1 kg.(km2.d) -1 with relationship of specific conductivity to concentrations of dissolved carbonate in water,which is only 4. 4% less than that obtained from mass balance method without regard to carbon dioxide sink. The study also implied important to evaluate chemical denudation fluxes of poor data in western mountain area,China. However,because of without chemical analysis and ion partitioning,the transient CO2 drawdown cannot be established.