A Study on Seasonal Variations in Metallic Elements of Ambient Coarse and Fine Particulates

• Main Authors: Ching-Heng Hsieh, 謝慶衡
• Other Authors: 鄭曼婷
• Format: Others
• Language: zh-TW
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/38014339876900959065

碩士 === 國立中興大學 === 環境工程學系所 === 101 === In this study, atmospheric particulates were collected from 2007~2010 in Taichung urban area. The purpose of this study was to investigate the seasonal variations in metallic elements of particulate matters. PM2.5 and PM2.5-10 were sampled by using dichotomous samplers. The samples were further analyzed to determine the concentration of 22 elements (Al, Fe, Na, Mg, K, Ca, Sr, Ba, Ti, Mn, Co, Ni, Cu, Zn, Mo, Cd, Sb, Pb, V, Cr, As and Se) by using inductively coupled plasma mass spectrometry (ICP-MS). The results showed that the toatal concentration of metallic elements in PM2.5 and in PM2.5-10 were 5.1 %, 3.6 %, 4.1 %, 4.9 % and 15.4 %, 13.1 %, 13.6 %, 16.2 %, in Spring, Summer, Autumn and Winter, respectively. Based on the analysis of enrichment factors, the crustal elements were Al, Ti, Mg, Fe, K, Sr and Ca in PM2.5-10, while the anthropogenic elements such as Cu, As, Zn, Mo, Pb, Se, Cd and Sb were found mainly in PM2.5. The results of the analysis by using principal component factor analysis (PCA) and cluster analysis (CA), showed that the possible sources of pollution were mineral dust, traffic emission, oil-fired burner , in all season. Seasonal variations for all metallic elements were not the same. Especially the contents of Sb and Ni in summer were higher than those in the others seasons, however, the contests of other elements were lowest in summer. The possible sources of Sb may come from diesel vehicles, incinerator or brake pads, while the sources of Ni may be from the combustion of heavy duty oil, steel plants or incinerator. Totally 10 Asian dust storms occurred during the sampling period. The dust storms brought not only crustal elements (Al, Fe, Mg, K, Ca, Sr and Ti), which were found significantly increased (P<0.05), but also anthropogenic elements (Cu, Zn, Pb, As and Se) which were also found significantly increased (P<0.05). In those storm events, there were three Asian dust storms passing over the ocean for longer time as compared with other dust storm paths which passed over the industrial areas. As the result the contents of Na and Mg for the three dust storms increased. Our results further showed that t the contents of anthropogenic elements in PM2.5 between local PM2.5 episodes and normal days were not significantly different. The reason for the episodic events is due to the lower wind speed, however the pollution sources still need further investigation.