Effects of seasonality, transport route, and East Asian dust storms on chemical characteristics of ambient particle matter in southern urban coastal area, Taiwan

• Main Authors: Chi-Fu Yeh, 葉旗福
• Other Authors: Chon-Lin Lee
• Format: Others
• Language: en_US
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/ke6hbk

博士 === 國立中山大學 === 海洋環境及工程學系研究所 === 105 === The main goal of this dissertation was to investigate the effect of seasonality and transport route on chemical characteristics and marks of East Asian dust storms in ambient particulate matter. In first part, this study investigated seasonal variations and transport route in PM2.5 and PM2.5-10 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 PM2.5 and PM2.5-10 were determined by ICP and ICP-MS. Multiple approaches, backward trajectory analysis, enrichment factor (EFc), and principal component analysis (PCA), were used to identify the potential sources of the metallic elements. The annual mean concentrations of PM2.5 and PM2.5-10 were 34.9±20.6 and 20.8±11.3 μg m-3, respectively. Analysis of the temporal distribution revealed seasonal peaks for most of the trace elements in PM2.5 and PM2.5-10 during winter season and the major elements in PM2.5-10 during the autumn season. EFc results confirmed that the main contributors of Cu, As, Zn, Pb, Cd, and Se were anthropogenic sources in PM2.5 and PM2.5-10. PCA identified traffic emissions, coal, and heavy oil combustion from both local and neighboring areas, as the major anthropogenic sourcesin the sampling site. With backward trajectory analysis, northeast monsoon (winter) originated from China demonstrated different chemical characteristics from those of southwest monsoon (summer) from the Southeast Asian countries. It is noted that 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. In the mark study of East Asian dust storms, the variationsin particulate matter (PM) and in eighteen metallic elements in four different particle sizes in the air of southern Taiwan were investigated from February to March 2010. The variation inmean mass concentrations of PM2.5, PM2.5-10, PM10, and TSP between Asian dust storm (ADS) and non-dust storm (NDS) periods suggested that the dominant fractions were PM2.5-10 and PM2.5, respectively. The obvious differences in metallic element concentrations between ADS and NDS periods suggested that crustal elements (Fe, Mg, Sr, Co, Ba and Mn) can be used as dust storm indicators, in addition to Ca and Al. Both mass fractions and metallic concentration ratios indicated that the PM2.5-10 fraction can distinguish between ADS and NDS periods. An enrichment factor (EFc) demonstrated that most anthropogenic elements were significantly lower in ADS periods than in NDS periods. The EFc values for anthropogenic elements in coarse particles may be used as indicators of dust storm invasion as well. An association was found between the extent of dust storm effects on receptors and the residence time (duration) of the event, in addition to the transport pathway.