粉尘颗粒物对祁连山老虎沟冰川融水理化性质的影响

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

基于2012年消融期6-9月在祁连山老虎沟12号冰川采集冰川融水径流样品,分析探讨冰川融水中粉尘颗粒物对融水理化性质的影响。结果表明,粉尘特征在消融期的变化很好地反映了冰川消融过程,融水中粉尘浓度和粒径众数在冰川强烈消融期的7月份表现为最高。粉尘体积粒径分布主要包括大气气溶胶超细颗粒（0-3.0μm,主要为PM 2.5）,大气粉尘颗粒（3.0-20μm）,以及局地源的粗颗粒（20-100μm） ;对雪冰消融释放的粉尘部分（3.0-20μm）粒径分布正态拟合结果说明,融水中粉尘颗粒物有很大部分来源于积雪中的粉尘运移所致。同时,融水中化学离子相对组成及其浓度消融期变化都与粉尘有较好的一致性,意味着粉尘对融水化学要素有重要影响。此外,pH值和电导率（EC）消融期的变化也反映了粉尘对融水物理指标的影响。在粉尘浓度较高时,融水pH值和电导率也表现出高值;融水径流中的悬移质颗粒物 （SPM） 浓度和溶解质固体（TDS）浓度具有较为一致的变化过程。

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 physicoehemieal 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 （20-100μm）, 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 Ca^2＋, Na^＋ , Mg^2＋ , 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, SO24-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.