Hydrochemical Denudation and Transient Carbon Dioxide Drawdown in the Highly Glacierized, Shrinking Koxkar Basin, China.

This study considered solute fluxes and the transient CO₂ drawdown process in the highly glacierized Koxkar basin in Central Eurasia, around 70.20% of which is covered by present-day ice. From 27 June to 30 September 2011, the total runoff depth was 671.70 mm, which yielded crustal solute fluxes of 213.65 ± 10.05 kg·(km²·d)⁻¹ that accounted for 53.59% of the total solute flux of the river water. The solute fluxes derived directly from ice meltwater and precipitation were 70.02 ± 4.68 and 16.57 ± 1.13 kg·(km²·d)⁻¹, respectively, which accounted for 17.57% and 4.16% of the total solute flux. The carbonation and hydrolysis of carbonate and feldspar minerals occurred because of the presence of H⁺, supplied by sulfide oxidation or CO₂ drawdown. While the H⁺ yielded by sulfide oxidation was insufficient for hydrochemical reactions, atmospheric CO₂ dissolved in the water generated H⁺ that drove follow-up reactions. The total transient drawdown of CO₂ was 804.83 t C, which generated 39.61% of the total HCO₃- and 24.68% of the river water solute. Transient drawdown of CO₂ in the glacier region indicated that change of glacial area and volume could influence atmospheric CO₂ concentration and be important in the long-term global CO₂ cycle. [ABSTRACT FROM AUTHOR]