TEMPERATURE AND HUMIDITY DEPENDENCE ON AEROSOL COMPOSITION IN THE NORTHERN KYUSHU, JAPAN

Aerosol samples were collected continuously from October 1990 to Febru ary 1992 at a rural site in the northern Kyushu and characteristics of aerosol composition are investigated. The seasonal variation of parti culate SO42- concentration is not significant, but it decreased during the rainy sampling conditions. On the other hand, particulate NO3- an d Cl- concentrations decreased in summer. The hourly and seasonal vari ations of NO3- are related to a photochemical reaction and gas/particl e equivalent for nitrate. Under the conditions of high atmospheric tem perature the dissociation of particulate NH4NO3 to its precursor HNO3 and NH3 is enhanced and dissociated HNO3 is readily removed from the a tmosphere through the surface deposition process. Gaseous nitric conce ntration (HNO3) is estimated from the data of particulate NH4+, NO3-, SO42-, Na+, Cl- and ambient temperature. The estimated HNO3 concentrat ion is well correlated with the ambient temperature having the regress ion function of In(HNO3)(2) = 68.3 - 20,100/T. This relationship coinc ides with the theoretical equation for the dissociation equilibrium of NH4NO3. Copyright (C) 1996 Elsevier Science Ltd