Abstract
This paper presents the chemical characteristics of atmospheric pollutants measured at the Fu-Shan forest (620 m MSL) during two two-weeks field experiments held in the summer and winter of 1993. Chemical compositions of these atmospheric pollutants in solid, gaseous and liquid phases were analyzed. The deposition budget of Sand N compounds through dry and wet deposition pathways were particularly assessed. As a result, aerosol mass spectra were found to be bimodal, having the 50% cut size ＜ 1.0 μm and around 3.2μm for fine and coarse modes, respectively. In summer, fine and coarse modes were primarily composed of ammonium sulfate and nitrate, respectively. But, in winter the coarse mode was dominated by sea salts due to the influence of northeast monsoon flows. Our average HNO2 (~0.10 ppb) was appreciably higher than those observed in clean troposphere, whereas HNO3 was at a comparable level. Meanwhile, ammonia gas and particulate ammonium were at a lower concentration level compared with those generally observed on the continental grounds. The SO2 (＜1 ppb) was comparable with those frequently observed in the free troposphere, while SO42- was close to the lowest level typically obtained in urban areas. In addition, NO3- which is thought to be associated with local pollution was limited. Therefore, we believe that excessive sot, to a larger extent, was transported to the site via long-range transport, particularly in winter. With regard to the deposition budget, wet deposition pathway (＞ 90 %) was the most effective mechanism for delivering atmospheric S and N compounds to the Fu-Shan forest during the periods of our field experiments.
Highlights
The importance of atmospheric inputs onto an ecosystem depends on their net fluxes and duration of existence
"P2") at the Fu-Shan Forest, this paper focuses on investigating the exposure of the Fu-Shan forest to atmospheric pollutants, as well as on estimating deposition fluxes of above pollutants on this forest and, subsequently, determining relative contribution of various deposition path ways to total deposition budget
Inside the Station, a natural garden for plants, the first one of its kind in Taiwan, has been managed. This area is largely forested by chinkapin, red machilus, yellow basket willow, Chinese meliosma, litsea, narrow leafed oak, gold colored neolitsea and Pyrenaria shinkoensis (King and Hsia, 1997)
Summary
The importance of atmospheric inputs onto an ecosystem depends on their net fluxes and duration of existence. Inside the Station, a natural garden for plants, the first one of its kind in Taiwan, has been managed This area is largely forested by chinkapin, red machilus, yellow basket willow, Chinese meliosma, litsea, narrow leafed oak, gold colored neolitsea and Pyrenaria shinkoensis (King and Hsia, 1997). The Station is bathed in warm and humid weather conditions in summer, but experiences cool and wet northeast monsoon flows in winter. The temperature at this site ranges between 12 and 27 °C with a mean value of 19 °C (King and Hsia, 1997). In consideration of relatively clean air in the mountain environments, the samples were taken on a 48-hour basis during summer measurements, compared with 24-hour or less sampling time which is often adopted in urban areas. For c1-, N02, N03-, SOt, NH/, Na+ and K+_ Detailed analytical procedures are not given here since they are generally common
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