ナトリウムを指標とする環境大気汚染状況の追跡と予測(第2報)

Abstract

In a preceding paper we described the results of the field survey on the fall of Na-containing dust in an area around a kraft-paper mill and, based on the results, we presented a formula giving the fall at a station as a function of its distance from the mill, the data used being those obtained during the periods 1974-1976 and, in particular, 1977-1979. In the present communication we have dealt with the results of the survey over the period 1980-1982. In the passing, it may be mentioned that sampling procedure, analytical technique and like were just the same as before. The findings are such that (1), from 1981 onwards, the fall has decreased so conspicuously that the annual averages at stations range from 17.9 to 5.6 (×(10)^<-2>t/(km)^2・month) for the first year (1980), and from 10.2 to 4.6 and from 10.7 to 4.0 for the following two years, while, at the controls, they have been measured to be within the limits of 7.3 to 5.6,5.2 to 5.0 and 6.2 to 5.7,respectively; the diminution in the fall might be considered as evidence that the discharge from the mill has come to be managed effectively, and (2) the above-said formula, marked (3) in text, holds only for the first year, because, for the next two years, the fall is distributed almost evenly, except that in the immediate neighbourhood of the mill.