Monthly-mean chemistry of bulk deposition from May 1990 to April 1993 iin TOEF, Japan. Monthly mean values are calculated based on volume-weighted averege using the precipitation amount of each sample. Note that original data are also available in JaLTER metacat. The data are published in Shibata, H., and T. Sakuma (1994) Acid Deposition at Forest Regions in North-Western Part of Tomakomai, Jpn. J. Soil Sci. Plant Nutr., 65: 313-320. (in Japanese with English Summary); Shibata. H., Satoh, F., Tanaka, Y. and Sakuma, T. (1995) The role of organic horizons and canopy to modify the chemistry of acidic deposition in some forest ecosystems. Water, Air, and Soil Pollution 85: 1119-1124.; Shibata, H. and T. Sakuma (1996) Canopy Modification of Precipitation Chemistry in Deciduous and Coniferous Forests Affected by Acidic Deposition. Soil Science and Plant Nutrition 42: 1-10.; Shibata, H., M. Kirikae, Y. Tanaka, T. Sakuma and R. Hatano (1998) Proton Budgets of Forest Ecosystems on Volcanogenous Regosols in Hokkaido, northern Japan, Water, Air, and Soil Pollution 105: 63-72.; Shibata, H., F. Satoh, K. Sasa, M. Ozawa, N. Usui, O. Nagata. Y. Hayakawa and R. Hatano (2001) Importance of Internal Proton Production for the Proton Budget in Japanese Forested Ecosystems. Water, Air, and Soil Pollution 130: 685-690.