Dust influences on alpine glacier meltwater in Laohugou glacier basin of western Qilian Mountains

This work discusses the temporal variation of various physicochemical species in the meltwater runoff of Laohugou Glacier No.12 and their correlation with dust particles in summer 2012. During melting periods, large amount of dust particles are melted from ice and snow of the glacier and dispersed into the meltwater, then transporting, which is very important for the change of physicochemical characteristics of glacier meltwater. We find that, the volume-size distribution of dust particles in the meltwater of glacier No.12 is mainly composed by three parts, which is fine aerosol particles (with diameter of 0~3.0 μm, mainly PM 2.5), atmospheric dust (with diameter of 3.0~20 μm), and local dust particles (20~100 μm), respectively. Comparison of dust particles in the snowpack and meltwater runoff indicates that, large part of dust particles in the meltwater may have originated from dust of the snow and ice, and transported into the meltwater runoff. Moreover, the temporal variation of dust and major ions (especially crustal species such as Ca²⁺, Na⁺, Mg²⁺, K⁺, and Cl^-) is very similar with each other, showing great influence of dust particles to the chemical constituents of the glacier meltwater runoff. Particles concentration is relatively high in July, and decrease in August, which is well correlated with glacier melting velocity in this region. However, SO₄^2- and NO₃^- concentration show an increasing trend during June to September, which may be caused by anthropogenic species input. SPM and TDS also show a similar change trend with dust particles in the meltwater, implying significant influences of glacier dust particles to TDS in the glacier region of Laohugou in Qilian Mountains in central Asia.