Hsu Shih-Chieh, Liu Shaw Chen, Jeng Woei-Lih, Lin Fei-Jan, Huang Yi-Tang, Candice Lung Shih-Chun, Liu Tsun-Hsien, Tu Jien-Yi
Research Center for Environmental Changes, Academia Sinica, Taipei, Taiwan, ROC.
Sci Total Environ. 2005 Jul 15;347(1-3):111-21. doi: 10.1016/j.scitotenv.2004.12.021.
Along with windblown dust, large quantities of pollutants are annually brought out of continental China by the westerlies in winter and spring; thereafter, they are partly subjected to transport by northeastern monsoon winds to Taiwan. To characterize the heavy metal composition differences between long-range transported and local aerosols and to evaluate metal contributions from long-range transported aerosols during the northeastern monsoon season, both PM(10) and PM(2.5) aerosols collected from Taipei, Taiwan from February 2002 to March 2003 were analyzed for three selected heavy metals, namely Pb, Cd and Zn using ICP-MS. Monthly patterns show that Pb concentrations in winter (62 ng/m(3)) were over two times higher than those in the other seasons, which is attributed to long-range transport from areas under development in China. Low Cd/Pb (0.017) and Zn/Pb (1.82) ratios were measured in aerosols collected during the Asian dust period, in which the ambient aerosols consisted predominantly of long-range transported pollutants. By contrast, high Cd/Pb (0.030) and Zn/Pb (3.44) ratios were observed during the summer monsoon season, in which aerosols were dominated by local pollutant emissions. Cd/Pb and Zn/Pb ratios appear to be successfully applied to identify the pollutants originating principally from the long-range transport or from local emissions. In addition, by assuming that a significant fraction of heavy metals associated with coarse airborne dust have settled to the sea prior to reaching Taiwan in spring, a mechanism is suggested to explain why higher anthropogenic metal concentrations occurred in winter than those in dust-rich spring.
在冬季和春季，伴随着风尘，大量污染物被西风带出中国大陆；此后，其中一部分被东北季风输送至台湾。为了表征远距离传输气溶胶和本地气溶胶之间的重金属成分差异，并评估东北季风季节远距离传输气溶胶中的金属贡献，我们使用电感耦合等离子体质谱仪（ICP-MS）对2002年2月至2003年3月在台湾台北采集的PM10和PM2.5气溶胶中的三种选定重金属（即铅、镉和锌）进行了分析。月度模式表明，冬季铅浓度（62纳克/立方米）比其他季节高出两倍多，这归因于来自中国欠发达地区的远距离传输。在亚洲沙尘期采集的气溶胶中，测得的镉/铅（0.017）和锌/铅（1.82）比值较低，此时环境气溶胶主要由远距离传输的污染物组成。相比之下，在夏季风季节观察到较高的镉/铅（0.030）和锌/铅（3.44）比值，此时气溶胶以本地污染物排放为主。镉/铅和锌/铅比值似乎成功地用于识别主要源自远距离传输或本地排放的污染物。此外，通过假设与粗颗粒空气传播尘埃相关的很大一部分重金属在春季到达台湾之前已沉降到海中，我们提出了一种机制来解释为什么冬季人为金属浓度高于沙尘丰富的春季。
