Effects of Seasonality and Transport Route on Chemical Characteristics of PM_2.5 and PM_2.5-10 in the East Asian Pacific Rim Region

This study investigated seasonal variation and transport routes of PM_2.5 and PM_2.5-10 associated metallic elements in the western coastal area of southern Taiwan. Particle sampling was conducted from March 2009 to February 2010. Sixteen metallic elements in PM_2.5 and PM_2.5-10 samples were determined by ICP-AES and ICP-MS. Multiple approaches, backward trajectory analysis, enrichment factors (EF_c), and principle component analysis (PCA), were used to identify the potential sources of the metallic elements. Analysis of the temporal distribution revealed seasonal peaks for most of the trace elements in PM_2.5 and PM_2.5-10 during winter season and the major elements in PM_2.5-10 during the autumn season. The EF_c confirmed that the main contributors of Cu, As, Zn, Pb, Cd, and Se were anthropogenic sources. PCA suggested traffic emissions, coal, and heavy oil combustion from both local and neighboring areas, as the major anthropogenic contributors at the sampling site. Backward trajectory analysis, demonstrated different chemical characteristics between the northeast (winter originating in China) and southwest monsoon (summer, from the Southeast Asia). Even in the same season, route-dependent effects of long-range transport in metallic concentrations and total excess cancer risk (ECR) of health-related metals were observed.