达索普冰芯中Pb记录反映的大气污染及其同位素证据

The Record of Lead Pollution and its Isotopic Evidence in Dasuopu Ice Core

利用电感耦合等离子体质谱仪（ICP-MS）及相关的超净化技术，对希夏邦马峰达索普冰芯上部40m的样品中超痕量金属元素Ph的含量进行测试的结果显示，Pb的含量自冰芯下部至上部呈显著增长趋势Pb同位素分析表明，2066Pb＋207Pb自冰芯下部至上部增长，而208Pb则呈下降趋势Pb同位素的这种富U铅、贫Th铅的组成演化特征显示，这种增加主要来自人类活动而非自然源，这与研究区相邻的多数发展中国家工业化进程加快，含Pb燃料释放的Pb增加是一致的。

The trace lead concentration and its isotopic composition in the upper 40 m of Dasuopu ice core has been directly measured by ICP-MS at Pg· g-1 level. The lead concentrations profile in the ice core show an increase in most recent decades and an abrupt increasing tendency in the recent years.Isotopic evidence shows that the abundance of U degenerated leads (206Pb+207Pb) increase and the abundance of Th degenerated lead(208Pb) decrease with lead concentration. We believe that the increase of lead concentration results from superposition of various increasing lead sources characterized by rich U degenerated lead, and natural lead sources can not interpret this phenomenon. Anthropogenic lead accounts for a large part of Pb budget in the ice core, especially, in the recent two decades the anthropogenic lead becomes overwhelming. Burning leaded gasoline is the major source of pollutant lead in atmosphere.The record of lead concentration in the Dasuopu ice core indicates that the situation of atmosphere over the surrounding counties goes from bad to worst. The Pb deposited in the Dasuopu Glacier is probably supplied by the Indian summer monsoon, which climbed over the pass at the head of the glacier, so the use of leaded gasoline in south Asian counties may be a major source of lead in atmosphere over this region.