长江源区各拉丹冬峰雪冰中微粒季节变化及其环境意义

分析了长江源区各拉丹冬峰冰川区不同海拔采集的3个雪坑SP1、SP2和SP3样品中δ18O、不溶微粒数量浓度及主要离子浓度,以探讨本研究区域雪冰微粒含量变化及其来源.结果显示,不同粒径微粒含量变化趋势一致,3个雪坑中细微粒含量分别占总微粒的88%、78%、86%.中微粒分别占10%、19%、11%;不同粒径微粒数量浓度之间的相关系数均达0.9以上(置信度可达99%),具有良好的相关性.雪冰中不溶微粒浓度同Ca2 、Mg2 、SO2-4一样,具有明显的季节波动.非季风期微粒浓度要高于季风期2～4倍.3个雪坑非季风期微粒通量分别占一个年层雪冰中微粒总通量的73.6%、92.3%、97%,即初春季节沙尘暴对于各拉丹冬雪冰中微粒沉降贡献远大于夏.秋季节.结合NCAR/NCEP再分析资料.应用HYSPLIT-4模式模拟的不同季节5 d后向气团轨迹图表明,各拉丹冬峰冰川I区雪冰中不溶性微粒可能来源于中亚、南亚和青藏高原本身,其中影响最大的可能是青藏高原自身的沙尘源区,同时冰川区裸露基岩对雪冰中不溶微粒含量亦有贡献.

Microparticle Variations in Snowpits from Mt.Geladaindong in the Source Region of Yangtze River and Its Environmental Significance

To study the variations of microparticles and their origins, microparticles concentrations, stable oxygen isotope (delta18 O) and major ion concentrations were analyzed in snow samples collected from Mt. Geladaindong in the source region of Yangtze River. The correlation coefficents of different size microparticles in three snowpits are above 0.9 (significant at the 99% level), respectively. Microparticle concentrations have distinct seasonal variations, about 2-4 times higher in non-monsoon season than those in monsoon season, and are consistent with variations of delta18 O, Ca2+, Mg2+ and SO4(2-). Microparticle fluxes in non-monsoon season in three snowpits are 73.6%, 92.3% & 97% of total annual fluxes, respectively. Air mass backward trajectories over Mt. Geladaindong region were analyzed using the HYSPLIT_4 model, and microparticles in Mt. Geladaindong snow were mostly influenced by dust aerosols from the northwestern Tibetan Plateau, South Asia. Coarse particles may come from the local rocks near glaciers. Research of seasonality of microparticle in snow could provide the information on modern environment processes, and is the base of further interpretation of ice core records.