Trends of Atmospheric Halocarbons in Urban Area around the Time of Regulation on Ozone Depleting Substances
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概要
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In Saitama Prefecture, monitoring of halocarbons has continued since 1990 as a part of the measures for ozone layer protection. Sample airs were obtained from two urban sites, a suburb site and a mountain site twice every month, and chlorofluorocarbons, hydrochlorofluorocarbons, hydrofluorocarbon and other chlorinated organic compounds were analyzed. The samples were obtained also from the sky and vertical distribution was determined.<BR>Although the atmospheric concentrations of chlorofluorocarbons were clearly high in 1991 as compared with background areas, the concentrations decreased and the features of their variations changed around the time of complete phase-out of chlorofluorocarbon production in 1995. Especially the concentration of 1, 1, 1-trichloroethane decreased rapidly to 1/30 of the peak time, and the influence ofnearby sources decreased. These changes were considered to be the result of regulations on ozone depleting substances, and it was noted that the effect of measures appeared in urban environmental concentrations earlier and more notably than background areas. However, decreased concentration of dichlorodifluoromethane (CFC12) was slight even in urban areas, and it is suggested owing to its concentration characteristics that discharge of CFC12 to the atmosphere has also occurred recently. Further surveillance and measures are needed. The conver sion of these substances was carried out in response to regulations. Concentration rises and large concentration variations of hydrochlorofluorocarbons and hydrofluorocarbon because discharge to the atmosphere were seen, and it was considered that the increase in alternative use of trichloroethylene caused the concentration rise in washing solvent fireld. Although the environmental influence of trichloroethylene was feared, the concentration decreased after 1998.
- 社団法人 大気環境学会の論文
社団法人 大気環境学会 | 論文
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