Inorganic Constituents in Snow Accompanied by Winter Wind and their Origin in the Hokuriku Districts

The ion constituents contained in fresh snow immediately after snowfall were examined at 5-10 km intervals over 50 km from the coast of Hakui city in Ishikawa Prefecture leeward of the northwestern seasonal wind to the plain in Toyama city in Toyama Prefecture. The concentrations of sodium ions and sea-salt sulfate ions that originated from the Sea of Japan decreased exponentially from Hakui city in Ishikawa Prefecture to Toyama city. The concentration of non sea-salt sulfate ions, which probably originate from human activities, also decreased exponentially, but it was lower than the concentration of sea-salt sulfate ions until 25 km from Hakui city and higher in the farther regions. We considered that this was due to additive effects of non sea-salt sulfate ions transported from a distance and local sulfate ions. The concentration of non sea-salt sulfate ions transported from the Asian Continent was estimated in each sampling station. Its contribution was 0.98 of the total at the coast of Hakui city and 0.65 at Toyama city, respectively, and showed a pattern similar to those of sodium ions and sea-salt sulfate ions. The concentrations of ammonium ions and non sea-salt calcium ions were slightly higher in the plain in Toyama than on the coast of Hakui city, suggesting that they mostly originated from the sampling regions in this study. The concentration of nitrate ions was almost constant in the regions from the coast to the inland areas, suggesting also that they mostly originated from the sampling regions.