基于地衣植物监测法的我国西南高山地区大气铅污染研究

Atmospheric Pb pollution in the alpine area of southwest China based on the lichens(Usnea longissima) analysis

通过对我国西南（云南、四川）13个高山地区地衣植物—长松萝（Usnea longissima）中铅（Pb）含量及其稳定同位素组成（^208Pb/^206Pb和^207Pb/^206Pb）的测定与分析,并且与土壤Pb含量进行对比,探讨了该地区大气Pb污染及其来源特征.结果表明,各地区长松萝中Pb的含量范围为1.5-64.5mg/kg,在临近城市及有色金属产区含量较高,与土壤中Pb含量（7.6-113.9mg/kg）空间变化一致;不同采样区长松萝与土壤中Pb含量呈典型正相关关系（r=0.919,P〈0.01）,长松萝Pb含量反映了区域大气Pb污染程度差异.长松萝中^208Pb/^206Pb和^207Pb/^206Pb同位素比值范围分别为2.099-2.123和0.852-0.874.通过与主要潜在污染源Pb同位素对比分析,认为我国西南高山地区大气Pb污染主要源自该地区铅锌矿冶炼释放,并且还可能受到来自缅甸含铅汽油源的影响.

Concentrations and the isotopic compositions of Pb（^208Pb/^206 Pb and ^207Pb/^206Pb） in the Usnea longissima from 13 regions in the alpine area of southwest China were analyzed. Atmospheric Pb pollution and the potential sources were discussed based on the chemical data as well as the Pb concentrations in the soils. Mean Pb concentrations varied between 1.5 and 64.5mg/kg in the Usnea longissima samples, which all showed high values in the regions near the city and non-ferrous metal production area, similar to the spatial variations of Pb concentrations in the soils. Concentrations of Pb in the Usnea longissima and soil showed positive correlation（r=0.919, P〈0.01）, implying the Pb concentrations in the Usnea longissima indicate the atmospheric Pb pollution levels. The ^208Pb/^206 Pb and ^207Pb/^206 Pb ratios were 2.099-2.123 and 0.852-0.874 in the Usnea longissima, respectively. Combining the results of Pb isotopic compositions in the Usnea longissima and in potential sources, we deduced that atmospheric Pb pollution in the alpine area of southwest China should primarily be attributed to regional emissions from non-ferrous metal production industries and may also influenced by the emission from leaded gasoline used in Myanmar.