Composition and characterization of nitrogen species in aerosol over the costal area of the northern Taiwan

• Main Authors: Zeng-Beng Chang, 張仁賓
• Other Authors: Hung-Yu ,Chen
• Format: Others
• Language: zh-TW
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/84652500757156502251

碩士 === 國立臺灣海洋大學 === 海洋科學系 === 93 === Abstract In this study, 175 and 32 samples were collected by using high volume sampling techniques and cascade impactor sampling techniques to achieve total suspended particles and size-fractioned particles, respectively. All the samples were extracted with Mili-Q water and then quantified by ion-chromatographer and UV/Vis spectrophotometer to obtain the concentrations of major anions (chloride and sulfate) and inorganic species (ammonium, nitrite and nitrate), respectively. The results indicate that the total suspended particle show a clear seasonal variation in which the maximum concentration occurred in the winter-spring and the minimum in the summer months. This pattern has been likely related to the original sources of these particles. In general, the continental source is mainly derived from the mainland China and the sea salt source is from the marginal seas around this area. The particle size distributions with an average mean medium aerodynamic diameter of 3.42 �慆 suggest that the coarse particle (sea salt) contribute a major portion (about 57.6%) in the total. For anion species, the concentrations of chloride (~ 33.2 mg m-3) are higher than the concentrations of sulfate (~ 27.6 mg m-3). Beside, the particle size distributions between both anions varied to about 30 times which indicate that the continental source is one of the major factors to influence the contribution of particles. For nitrogen species, the average concentrations of ammonium, nitrite, nitrate and total inorganic nitrogen are 73.9 nmol m-3, 1.18 nmol m-3, 110 nmol m-3 and 185 nmol m-3, respectively. Nitrate is the most important part in the total inorganic nitrogen species and partitioned equally in the coarse and fine mode particles. Nonetheless, in the summer, nitrate is enriched in the coarse mode due to the marine source in the summer. Concentrations of ammonium are apparently higher in winter-spring months than in summer months. This is result in the oxidation condition of ammonium which is not completely oxidized and than transported southward by the east northern monsoon system from the mainland China.