A dual site study of the rainwater chemistry within the Western Pacific region |
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Authors: | K M Wai S H Wang P A Tanner N H Lin |
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Institution: | (1) Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong S.A.R., People’s Republic of China;(2) Department of Atmospheric Science, National Central University, Chung-Li, Taiwan |
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Abstract: | The two-year (1999–2000) rainwater chemistry at two monitoring sites in nearby coastal areas Taiwan (TW) and Hong Kong (HK)]
within the Western Pacific region has been studied. The volume weighted average pH values for the entire sampling period in
TW and HK were 4.6 and 4.2, respectively. Sea salt Na+ and Cl− were the most abundant species in the TW samples but and H+ were the most abundant in the HK samples. The sea salt and concentrations at TW were higher than those at HK both in the cold and warm seasons. Chloride depletion was minimal in the
rainwater samples at both sites. Non seasalt- was associated with . Under the influence of the East Asian Winter Monsoon, the back-trajectory studies revealed that elevated anthropogenic species
concentrations were associated with trajectories (1) very near to the continental boundary layer of Mainland China; or (2)
along the coastline of Eastern China where large cities/industrial areas are located or (3) passing through the region of
stagnant air over Northern/Eastern China. The lowest anthropogenic and crustal species concentrations measured in HK are associated
with the summer monsoon and are attributed not only to the clean marine air masses but also to the relatively low SO2, NO
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and NH3 emissions from the South/ South East Asian countries, as well as infrequent biomass burning activities and wet scavenging
at sources during the summer months. Approaching tropical cyclones led to the lowest pH values (4.2 in TW and 3.8 in HK) amongst
the other weather categories. The findings here have been compared with other studies within East Asia and elsewhere. |
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Keywords: | Acid rain Asia Cyclone Rainwater composition Weather systems |
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