The seasonal variations of the chemical components in airborne aerosols in a mountainous area were investigated. Field observations were made at Happo at an altitude of 1,850m in the central mountainous region of Japan. Airborne aerosol was collected for 12hours or 24hours from May 1998 to September 1999 and the chemical components (Na+, Mg2+, K+, Ca2+, NH4+, Cl-, SO42-, NO3- and oxalic acid) in the aerosol were measured. In addition, gaseous pollutants, such as ozone and SO2 were monitored simultaneously. The concentrations of Na+ were much higher from autumn to spring than those in summer. Cl- increased in winter and the seasonal variation differed from Na+. The concentrations of Mg2+, K+ and Ca2+, especially Ca2+ increased in spring. It suggests that the increase in this Ca2+ concentration is based on the influence of Kosa aerosol (yellow sand) transported from continental Asia. The concentrations of SO42- and oxalic acid produced by photochemical reaction increased from spring to summer, and NH4+ which is the neutralization ingredient of sulfuric acid showed also the same seasonal variation. The concentration ratios of Cl-/Na+ were quite low compared with that of sea water. This is based on Cl- loss reaction. There was almost no influence of sea salt in the mountainous area, because most of K+, Ca2+ and SO42- were non-sea salt. The sulfate conversion ratio, i.e., SO42- -[S]/(SO2-[S] + SO42--[S]), was as high as 0.8 in summer. In summer and winter, when the concentration of SO42- was high, total equivalent concentration of anions (Cl-, NO3- and SO42-) was much higher than that of cations (Na+, NH4+, K+, Mg2+ and Ca2+), which suggests that a portion of the SO42- existed in the form of acidic aerosols such as H3SO4 and NH4HSO4. It suggests that a part of sulfuric acid produced by the photochemical reaction is transported to the mountainous area without being neutralized by alkali substances, such as NH3.

An analytical method for an insecticide Fipronil and its metabolite MB 46513 remaining in agricaitunil products has been established which uses GC-ECD and GC/MS for their determination and continuation, respectively. In this method, target compounds are extracted with acetone from agricultural products, concentated, and finally re-extracted with n-hexane. When the sample contains lipid in large quantity, it is first delipidated by partition with acetonitrile, cleaned up with Florisil column, and finally determined by GC-ECD. In the case of vegetables and fruits, which contain lipids in small quantity, the sample is cleaned up with a Florisil column and determined by GOECD. The detection limit of this method is 0.001 micro g/g for both of these kind of samples, the recovery of Fipronil is over 85%, and the C. V. of the recovery is less than 7%. For MB-46513. the recovery is over 63% and its C. V. is less than 9%. This method was applied to 17kinds of agricultural products and no Fipronil and MB46513 were detected.