黄河源区阿尼玛卿山耶和龙冰川积雪中不溶微粒组成特征及环境意义

Composition characteristics and its environmental implication of insoluble microparticles in snow cover on Yehelong Glacier,Mt. Anyemaqen,source region of the Yellow River

2005年9月下旬,在黄河源区阿尼玛卿山耶和龙冰川平衡线附近挖取了6个雪坑,固定层厚采集了89个雪冰样品,分析了样品的δ18O值及不溶微粒的浓度、粒径,研究了耶和龙冰川中不溶微粒的时空分布特征及环境意义。结果表明:雪冰样品中不溶微粒浓度平均值为1.1×10^(5)个·mL^(-1),PM_(10)占到总粒子的99%;以微粒数浓度为权重计算的平均粒径分布在1.1~1.8μm之间,说明耶和龙冰川积雪中不溶微粒以细粒子为主;不溶微粒的粒度谱分布不符合正态分布规律,粒子浓度的众数出现在小粒径;微粒源区输入和大气环流强度是控制积雪中不溶微粒特征的主要因素。源区输入和风场强度均较大时,积雪中不溶微粒浓度及粒径均较大;源区输入较弱而风场强度较大时,积雪中微粒浓度有所增加,粒径增加更加显著。结合HYSPLIT-4模式研究发现,在耶和龙冰川积雪中不溶微粒的浓度及粒径随雪坑深度的变化可以反映气团强度的季节变化,夏季降水增加使微粒的季节变化更加显著。西风携带的塔克拉玛干沙漠和中亚干旱区尘埃是耶和龙冰川春、秋季节积雪中不溶微粒的重要来源。

In order to study the spatial and temporal distribution characteristics of the insoluble microparticles in snow cover and its environmental implication,six snowpits were dug near the equilibrium line altitude(ELA)and 89 snow samples were collected at Yehelong Glacier,Mt.Anyemaqen by the end of September 2005.Insoluble microparticles concentration and oxygen isotope were analyzed.The results indicated that the mean number concentration of particles(0.56<r<400μm)is 1.1×10^(5) mL^(-1),particles less than 10μm accounts for 99%.Mean number-weighted sizes were among 1.1~1.8μm which suggested the snow contained more fine particles.The concentration and size of insoluble microparticles both were lowest at the middle part of the snow pits,were highest near the dust layer at the lower part,were somewhere in between at the upper part.The number-size distribution of insoluble microparticles in snow cover displayed abnormal distribution.The intensity of the dust source and atmospheric circulation was the main factors that control the characteristics of the insoluble microparticles in snow cover.The concentration and size of microparticles increased when the dust source and atmospheric circulation strengthened,and vice versa.It only when the atmospheric circulation strengthened,the size increased even faster than the concentration of the particle.Combining with HYSPLIT-4 model,the research shows that the variation of size and concentration of particles over the depth of the snowpit could reflect the seasonal change of atmospheric circulation.Westly wind which went through Taklimakan Desert and arid regions of Central Asia brings more small particles to Yehelong Glacier in spring and autumn.