Temporal Variation in dry Deposition of Proton to a Japanese Cedar Forest. Evaluation of Annual and Seasonal Variations in Deposition Estimated Using an Inferential Method.:Evaluation of Annual and Seasonal Variations in Deposition Estimated Using an Infe

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To evaluate the temporal variation of atmospheric deposition of H+, three-year field measurements were conducted during the period from April 1997 through March 2000 in a Japanese cedar (Cryptomeria japonica) forest, located in Gunma Prefecture, Japan. On the basis of the meteorological and atmospheric concentration data, the dry deposition of SO2, HNO3, NO2 and HC1 were estimated using an inferential method. The estimated annual dry deposition of H+ ranged from 61 mmol m-2 yr-1 to 83 mmol m-2 yr-1. Compared with the uncertainty of estimates, the annual variation in deposition of H+ was not significant. The observed annual wet deposition of H+ ranged from 28 mmol m-2 yr-1 to 43 mmol m-2 yr-1. Therefore, approximately twice as much H+ was constantly loaded to the studied forest by dry deposition than by wet deposition. The dry deposition of H+ in the warm season was slightly greater than that in the cold season. The magnitude of the seasonal variation of dry deposition was relatively smaller than that of wet deposition of H+ However, the contribution of each gas to the dry deposition of H+ indicated a clear seasonal change. Although HCl was the dominant contributor in the cold season, the contribution of HNO3 and SO2 increased in summer.
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