Atmospheric peroxyacyl nitrates in urban/remote sites and the lower troposphere around Japan

The methods of sampling, carrying and keeping, and the instruments for meas uring atmospheric peroxyacetyl nitrate (PAN) and peroxypropionyl nitrate (P PN), were developed for field studies and had been used for the surveys on four remote islands and in the troposphere since 1991. PAN and PPN were det ected in most of over 500 samples. Mean concentrations of PAN and PPN in th e islands and in the lower troposphere (altitude; 400-4500 m) from the Yell ow Sea to the Japan Sea are 0.1-0.4 ppb (10(-9), v/v) and 0.01-0.03 ppb, re spectively. Good correlation between PAN and PPN at each point was observed , and PPN was found to be 5-9% of PAN. In addition, PAN in the urban area h ad been monitored continuously at Ichihara close to metropolitan Tokyo sinc e 1985. The yearly means of PAN there were constantly around 0.4 ppb for te n years. The ratios of PANs to NOx* or NOx+ (which were detected by chemilu minescence type or Griess-Saltzman type of NOx analyzers) were found to be mostly, 1% in the urban air, 15-20% on the remote islands, and 15-60% in th e lower troposphere (occasionally exceed 80% in the upper 2500 m altitude). PANs in the remote area were confirmed to be relatively more important, co mpared with in the urban area. The higher ratios in aircraft surveys were p artly related to the atmospheric temperature in the sampling area.