製紙工場周辺の臭気に関する調査研究 : 特に臭気強度と物質濃度について

Abstract

A field survey of the atmospheric odor around a kraft-paper mill has been started in the middle of 1974 and continued down to date; the information gathered before the end of 1980 was given in five reports, with the methodology employed. In the present report, the results of the measurements repeated six times over the period from 1981 to 1983 are described and further, some considerations as well. From examination of the results, it was found that (1) even at the monitoring stations contigous to the mill, the intensity is usually lower than step 3 (mildly perceptible; the fourth in the 6-step system), but, at some stations located 1.5km or more down-wind, it exceeds step 1 (the detection threshold) depending upon the weather conditions. (2) Odorants are principally hydrogen sulfide and methyl sulfide, and, at times, additionally methyl mercaptane and dimethyl disulfide, the concentrations of the former two being generally high when the latter two are present. (3) For the stations within 2km of the mill, 63 and 83% of them are at the steps below 1.5 and 2 respectively, revealing that the magnitude of the odor nuisance has been definitely reduced. Regarding the relationship between odor intensity and odorant concentration, the applicability of Stevens' and Weber-Fechner's formulae was tested, with the finding that the latter be preferable to the former; following this, some correction was made to the former by introducing a term, Δ, and, utilizing it, the back-ground concentration in the study area was estimated to be nealy 0.2-0.4ppb of hydrogen sulfide.