[Hydrochemical characteristics and evolution of runoff at Qiyi glacier, Qilian Mts].

Glacier ice, supraglacier stream water, ice-marginal stream water, proglacier stream water samples were collected at Qiyi glacier located in central part of Qilian Mountain 2006-06 - 2006-07. Major ions concentration, pH and EC were analyzed. The results indicate that pH varies from 8.05 to 8.79, and EC 32.4 - 134.4 microS cm(-1). The order of major ions concentration in differed water is: supraglacier stream water< ice-marginal stream water < proglacier stream water. Meanwhile, hydrochemical characteristics vary from HCO3(-) -Ca(2+) to (HCO3(-) + SO4(2-))-(Ca(2+) + Mg(2+)). Major ions,almost in all samples; HCO3(-) > SO4(2-) > Cl(-) > NO3(-), Ca(2+) > Mg(2+) > Na(+) > K(+) mainly comes from carbonate weathering,and some is from sulfate dissolution. Concentrations of Mg(2+) and K(+) increase quicker than Na(+) and Ca(2+) in proglacier stream and ice-margin stream that is inverse to their abundance in crust. The spatial characteristic of ions concentration is controlled by the process of water-rock and temporal change is hydrological factors.