東京都府中市における大気降下物中のフッ化物イオン(<特集>地球環境の中に見る地球環境化学)

概要

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The atmospheric deposition of fluoride (F^-) was observed at Fuchu, in a Tokyo suburb, from February 1992 through November 1994. Dry and wet depositions of F" were in the range of 8.6-57 and 9.9-214 μg m^<-2> day^<-1>, with the weighted mean values of 26 and 76 μg m^<-2> day^<-1>, respectively. Weighted mean value for total (dry + wet) deposition of F^- was 102 μg m^<-2> day^<-1>. Dry fall-out amounted to 27% of the total F^- deposition, which was in the same range as other observed elements derived from soils. However, chemical analysis indicated neither soil particles nor sea salt to be a major source of F^- deposition. This result suggests contributions other than these two; probably a fossil fuel combustion source. In the case of dry deposition, an increase in F^- deposition during the spring period resulted in higher F^-/nss-SO_4^<2-> (nss = non sea salt) than that for the remainder of the time. Such periodical changes in F^-/nss-SO_4^<2-> was not obtained with wet deposition, because the wet depositions of F" and nss-SO_4^<2-> depended largely on the amount of rainfall. A stationary source emitting fluoride to atmosphere was not observed near the sampling site. Therefore, transportation of suspended particles rich in fluoride was suggested as a possible mechanism to increase the F^-/nss-SO_4^<2-> of dry deposition in the spring.
日本地球化学会の論文
1995-12-25