成都经济区近地表大气尘地球化学基线

成都经济区近地表大气尘中重金属元素含量空间分布显示，经济区中东部高于西部，北部高于中南部，重工业城市高于综合性城市和旅游城市，工矿影响区元素含量总体偏高，人口密集的平原区高于山区。通过标准极限方法确定了近地表大气尘中元素的“极限浓度”，以低于“极限浓度”值统计确定了地球化学基线值：As为28.6mg/kg 、Hg 0.63mg/kg 、Cd 2.94mg/kg、Cr 110mg/kg、Pb 281mg/kg、Ni 32mg/kg、Zn 535mg/kg。近地表大气尘中元素地球化学基线与区域地质背景和矿产开发有关，矿业活动、工业活动及居民生活是造成近地表大气尘中人为扰动元素含量偏高的主要原因。

The geochemical baseline of near-ground air dust in Chengdu economic region

The heavy metals distribution of near-ground air dust in Chengdu economic region shows that the content of heavy metals in the middle-east part is higher than that in the west part, and that in the heavy industry city is higher than that in the comprehensive city and tourist city. The heavy metal content is totally high in industry and mine influencing areas, and that in the plain terrain of dense population is higher than that in the mountain area. The standard limit method was used to determine the element limiting concentration in near-ground air dust, and the statistics of values below the limiting concentration value was employed to determine the geochemical baseline values, and the values obtained are as follows: As 28.6mg/kg, Hg 0.63mg/kg, Cd 2.94 mg/kg, Cr 110 mg/kg, Pb 281 mg/kg, Ni 32 mg/kg and Zn 535 mg/kg. Elements in geochemical baseline of near-ground air dust are related to regional geological background and mineral development. Mining activity, industrial activity and residents' lives constitute the main factors responsible for the relatively high content of artificial disturbance elements of near-ground air dust.