Chemical Characteristics of Atmospheric Aerosolsat Coastal Areas

• Main Authors: Pei-Chuan Chen, 陳佩娟
• Other Authors: none
• Format: Others
• Language: en_US
• Published: 2003
• Online Access: http://ndltd.ncl.edu.tw/handle/21516178491852504067

碩士 === 朝陽科技大學 === 環境工程與管理系碩士班 === 91 === Atmospheric aerosols were collected from November 2000 to January 2002 in Gao-mai. In order to compare the chemical characteristics of aerosols at coastal and inland area, atmospheric aerosols were also collected during June 2001 to January 2002 (5th-8th) in Wufeng. High volume samplers, micro-orifice uniform deposit impactor (MOUDI) and dry deposition sampling devices were used for aerosol sampling in this study. The water-soluble ions were analyzed by ion chromatography (IC). The meteorological information of Shalu weather monitoring station were collected and included for discussion. The concentrations of TSP, Mg2+ and Ca2+ at coastal area (140, 0.736 and 2.84 μg/m3) were higher than those at inland area (124, 0.396, 1.94 and μg/m3). The concentrations of SO42- and NO3- at inland area (13.5 and 13.1 μg/m3) were higher than those at coastal area (9.76 and 8.21 μg/m3). The concentrations of TSP, Mg2+ and Ca2+ at the two sampling sits were higher at daytime than those at nighttime. The concentrations of NO3- at the two sampling sits were higher at nighttime than those at daytime. The concentrations of TSP, NO3- and SO42- increased as relative humidity increased. The dry deposition fluxes of TSP, Mg2+, Ca2+ and SO42- at coastal area (728, 1.64, 8.62 and 3.59 mg/m2-day) were higher than those at inland area (100, 0.608, 5.51 and 1.97 mg/m2-day). However, the concentration of NO3- at inland area (4.24 mg/m2-day) was higher than that at coastal area (4.02 mg/m2-day). The dry deposition fluxes of particulate and ions increased with wind speed. Size distribution of particulate mainly distributed in coarse mode at coastal area, and distributed in fine mode at inland area. At the two sampling sites, size distribution of SO42- mainly distributed in fine mode, and Mg2+ and Ca2+ mainly distributed in coarse mode. NO3- mainly distributed in coarse mode in summer and fall, and mainly distributed in fine mode in spring and winter. The ratio of nss-SO42-/SO42- was 72-95%, which suggests that most SO42-does not originate from seawater. Chlorine loss at inland area (74.3%) was higher than that at coastal area (38.1%), and is higher at nighttime than at daytime. Fine mode particles at coastal and inland area (85.8% and 89.0%) had higher chlorine losses than those of coarse particles (40.8% and 84.2%). It can be explained that fine particles had higher specific area, providing more reaction sites. High relative humidity caused high chlorine loss. Principle factor analysis showed that high wind speed in summer caused high correlation of Na+, Cl-, Mg2+, Ca2+, K+ and TSP (factor 1). This factor was recognized as sea-salt emission source. Factor 2 was correlated with SO42-, NO3- and NH4+, which were recognized as secondary aerosol. In winter, east-north wind would bring the agricultural air pollution to the coastal sampling site.