Long-Term Trends in the Chemical Composition of Precipitation over the Japanese Archipelago

Long-term trends in the chemical composition of precipitation over the Japanese archipelago were presented. On the basis of the wet deposition monitoring data collected between 1970s and 2010s, we analyzed (i) long-term trend and seasonal variation of the non sea-salt sulfate to nitrate (NO3-/nssSO(4)(2-)) ratio in precipitation at three monitoring sites, (ii) changes in the horizontal distribution of the NO3-/nssSO(4)(2-)) ratio over the past eight years, and (iii) influence of changes in the emissions of sulfur dioxide and nitrogen oxides in East Asia on the precipitation quality in the Japanese archipelago.