Wet deposition of ammonium and atmospheric distribution of ammonia and particulate ammonium in Japan

Compilation of data on ammonia emission flux, ammonia and particulate ammon ium distribution, and ammonium wet deposition is urgently needed by modelle rs, if our understanding of chemical mechanisms in the atmosphere and trans boundary air pollution is to be improved. We conducted several kinds of fie ld surveys to obtain information on the distribution and deposition of redu ced nitrogen compounds. Total ammonium (gas + particulate) concentrations r emained nearly constant at around 350 neq m(-3) in a suburban area, Fukuoka (F). The non-sea-salt sulfate concentrations at F and Goto (G), a remote J apanese island, were well correlated with each other (correlation coefficie nt 0.63), although the concentrations at G were lower than those at F. The variations in non-sea-salt sulfate and particulate ammonium concentrations, wind fields in the East Asian region and backward trajectory analysis indi cated long-range transport of air pollutants from the Asian continent to Go to. The level of wet deposition ammonium in Japan is similar to that in mos t of central and eastern Europe. The largest deposition flux of ammonium wa s found in the Tokyo metropolitan area and indicates ammonia emission from urban human activities.