Abstract
The rainfall-weighted means of Zn and Cu in precipitations collected from Sakata city of Yamagata-ken, and Mizushima industrial area and environs and Okayama city of Okayama-ken were distributed in the range of 70-73 μg·l-1 and 1.9-3.0 μg·l-1, respectively, and 39-51 μg·l-1 and 1.0-1.2 μg·l-1, respectively, in the sparsely populated area above the Takahashi River Basin. Almost precipitations showed the pH acidified lower than 5.6, and positive correlations were observed between the concentrations of hydrogen ion and those of Zn and Cu in precipitations collected from Sakata city.
Owing to the high concentrations of Zn in precipitations, the Cu/Zn ratios were distributed in the range of 0.024-0.042 and agreed approximately with those for plant and animal materials.
The concentrations of Zn and Cu in precipitations from Sakata city were found to be slightly high in the winter season from November to March, but these seasonal variations were not found for Okayama city and Takahashi River Basin. On the other hand, positive correlations were observed among 6 sampling sites for Zn and Cu in precipitations collected from Okayama city and Takahashi River Basin.
