Vertical changes in sulfur isotopic ratio of water flowing through a forested catchment along the coast of the sea of Japan in central Japan–a buffer against seasonal transboundary air pollution

Acidic substances, specifically sulfur (S) compounds, derived from atmospheric deposition play a major role in the acidification of forest ecosystems. This study conducted field surveys to clarify buffering system against seasonal large S inputs forested catchment central Japan that has historically suffered transboundary air pollution. Results showed fluxes significantly increased winter due north-westerly winds Asian continent; were 1.1 and 0.3 kmolc ha−1 cold warm seasons, respectively, effects sea salt Despite seasonality within deposition, SO42– concentrations stream water (SW) found be relatively stable throughout year. Similarly, isotopic ratios (δ34S) rainwater clear variation, increasing 12‰ decreasing 2‰ summer, whereas δ34S value SW was year-round at ~9‰. Flux-weighted mean values for rainfall (RF), throughfall, stemflow, similar, i.e. 8.5, 9.5, 9.0, 9.0‰, respectively. Both RF soil solutions appear converge SW, suggesting is primary origin SW. The adsorption-desorption appears mainly buffer input prevent sudden acidification, small biological cycle suggested by litterfall. Possible disturbances this should carefully monitored under changing climate.