青海瓦里关大气气溶胶元素富集特征及其来源

ENRICHMENT CHARACTERRISTICS AND ORIGIN OF ATMOSPHERIC AEROSOL ELEMENTS AT MT. WALIGUAN

利用中子活化及PIXE和可见光灰度仪 ,对青海瓦里关大气本底基准监测站的大气气溶胶样品进行了测量。通过元素相对浓度、富集因子和主因子分析等数据统计分析 ,并结合同期的气团后退轨迹分布资料 ,讨论了瓦里关大气气溶胶元素的组成及来源。结果表明 ,位于青藏高原偏远地区的瓦里关大气气溶胶以土壤及地壳等自然来源为主 ,因子分析的方差百分数给出瓦里关气溶胶中自然源的贡献率平均在 70 %以上。燃煤、交通及冶炼等人为源也占有一定比例。大气黑碳气溶胶的观测也表明人类活动影响的存在。

Samples of atmospheric aerosol were collected at Mt. Waliguan (CGAWBO/GAW). The filter samples were analyzed by NAA (neutron activation analysis), PIXE (pro ton induced x-ray emission). The concentrations of 42 trace elements combined w i th the measurements of black carbon were determined. Based on the statistical an alysis of element concentrations, enrichment factors and the principal factor an alysis, combined with the corresponding back trajectory, the elemental compositi ons and the sources of aerosol over Waliguan are discussed. The results indicate that the natural sources identified as major contributors to the aerosol over M t.Waliguan are the soil and crust. The factor analysis shows that the contributi ng rate of these sources accounts for approximately 70% or more of the aerosol. However, anthropogenic origins, such as coal burning, automobile and industrial emissions form a certain proportion of aerosol. The measurement results of the b lack carbon at Waliguan indicate that there exist influences from human activiti es. It is estimated that the pollutants mainly come from the more developed area s in the Qinghai Province and the Hexi Corridor. Both local influences, such as the elements of soil in the adjoining area, and long-range transport of aeroso ls can affect, in varying degrees, the composition of the background aerosol ove r Mt Waliguan.