Department of Earth and Planetary Science, University of California, Berkeley, USA.
Environ Sci Technol. 2010 Dec 1;44(23):8911-6. doi: 10.1021/es101450t. Epub 2010 Oct 29.
During the last two decades, expanding industrial activity in east Asia has led to increased production of airborne pollutants that can be transported to North America. Previous efforts to detect this trans-Pacific pollution have relied upon remote sensing and remote sample locations. We tested whether Pb isotope ratios in airborne particles can be used to directly evaluate the Asian contribution to airborne particles of anthropogenic origin in western North America, using a time series of samples from a pair of sites upwind and downwind of the San Francisco Bay Area. Our results for airborne Pb at these sites indicate a median value of 29% Asian origin, based on mixing relations between distinct regional sample groups. This trans-Pacific Pb is present in small quantities but serves as a tracer for airborne particles within the growing Asian industrial plume. We then applied this analysis to archived samples from urban sites in central California. Taken together, our results suggest that the analysis of Pb isotopes can reveal the distribution of airborne particles affected by Asian industrial pollution at urban sites in northern California. Under suitable circumstances, this analysis can improve understanding of the global transport of pollution, independent of transport models.
在过去的二十年中，东亚地区工业活动的扩张导致了空气中污染物的大量产生，这些污染物可以被输送到北美地区。此前，人们曾试图通过遥感和远程采样地点来检测这种跨太平洋污染。我们通过对来自旧金山湾区上风和下风两个地点的一系列样本进行测试，以检验空气中颗粒物质中的 Pb 同位素比值是否可以用于直接评估亚洲对北美西部人为源空气中颗粒物质的贡献。我们的研究结果表明，根据不同区域样本组之间的混合关系，这些地点的空气中 Pb 的中位数值为 29%来自亚洲。这种跨太平洋 Pb 虽然含量很少，但可以作为亚洲工业羽流中空气中颗粒物质的示踪剂。然后，我们将此分析应用于加利福尼亚州中部城市站点的存档样本。总的来说，我们的研究结果表明，Pb 同位素分析可以揭示受亚洲工业污染影响的空气中颗粒物质在加利福尼亚州北部城市的分布情况。在适当的情况下，这种分析可以在不依赖于传输模型的情况下，提高对全球污染传输的认识。
