Chemical characteristics of atmospheric precipitation in spring and summer in Toyama, Japan

摘要

In order to understand the chemical characteristics of wet precipitation in Toyama, Japan, the rainwater samples were collected during 3 – 8, 2008, the pH value, electrical conductivity and major-water soluble ions were measured. The result showed that the average pH of rainwater was observed to be 6.39, ranging from 5.77 to 6.62, indicating the precipitation in Toyama had been acidified. The annual mean conductivity varied from 40.97µS·cm−1 to 69.64 µS·cm−1. The average conductivity was much higher than that at Waliguan Global Baseline Station but lower than that observed in the urban area of Beijing, suggesting that the chemical composition of precipitation at Toyama was influenced by regional anthropogenic activities. The concentrations of the water soluble ions in spring were higher than those of them in summer, the dominant water-soluble ions at the collection site were SO42− and NH4+, Using enrichment factors, it was shown that main contribution of Cl−, Na+ and K+ came from primary marine sources, while the contribution from anthropogenic and crustal sources was dominant for SO42−, NO3−, Ca2+ and Mg2+ in rainwater samples. Nss-Ca2+ and NH4+ were the primary neutralizing agents of rainwater acidity. Trajectory analysis showed that air mass originating from the Asian continent had generally higher the water-soluble inorganic ionic concentrations than those of originating from the Pacific Ocean.