Atmospheric deposition of acidifying components to a Japanese cedar forest

One-year field measurements were conducted in a Japanese cedar (Cryptomeria japonica) forest, located in Gunma Prefecture, Japan. On the basis of them meteorological and atmospheric concentration data, the dry deposition of S O2, HNO3, NO2 and HCl was estimated using the inferential method. The annua l dry deposition of H+ was estimated at 721 eq ha(-1)yr(-1), which was 40% larger than the measured annual wet deposition of H+ (514 eq ha(-1)yr(-1)). Therefore, dry deposition is an important pathway for the atmospheric inpu t of H+ to the forest in the study site. The contribution of each gas to th e dry deposition of H+ was as follows: SO2, 25%; HNO3, 32%; NO2, 10%; and H Cl, 33%. The extremely high contribution of HCl appeared to be caused by th e high emission intensity of HCl due to waste incineration in the site regi on. The differences between estimated deposition and throughfall and stemfl ow measurements indicated that about 80% of the total deposition of H+ was taken up by the canopy.