Long-term performance of a solar-powered small automatic rainwater collector and its application to acid deposition monitoring in the southeast mountainside of Mt. Fuji

The performance of a solar-powered small automatic rainwater collector was investigated, which was developed with an emphasis on small-size, lightweight, and inexpensive for use in a wet deposition monitoring network in a mountainous area. It was studied at Tarobo, which is located at the southeast mountainside (1300 m a.s.l.) on Mt. Fuji, during four years from July 2005 to September 2009. The rainfall amounts estimated by the automatic rainwater collector corresponded to those observed by a rain gauge verified by Japan Meteorological Agency. A comparison of the rainwater chemistry by the automatic rainwater collector with that by a commercially available wet-only sampler indicates that the automatic rainwater collector is available for use in wet deposition monitoring in mountainous areas. The mean annual wet deposition fluxes of H⁺, NH₄⁺, NO₃^-, and SO₄^2- at Tarobo were 48.9, 35.0, 38.0 and 69.4 meq/m²/y during three years from 2006 to 2008, respectively, and were higher than those at remote sites in Japan, particularly NO₃^- deposition. The concentration of acidic substances at Tarobo was nearly equal to those at remote sites in Japan, so it is expected for Tarobo to be in use for a remote site of an acid-deposition monitoring network in Japan because of easy access to Tarobo.