抄録
The pH and major ions in the precipitations collected on a weekly basis from November 1991 to October 1992 were determined in Sakata of Yamagata-ken on the northeastern coast of the Sea of Japan. Their concentrations in 49 samples were separated into two groups and shown with the rainfall-weighted average : (A) group was contributed by sea-salt transported by seasonal wind from November to March and (B) group was from other months free from sea-salt. The following are the results obtained :
(1) The pH values of both (A) and (B) groups were 4.6 and 4.5, respectively, and the concentrations of nss-SO42-, NO3-, nss-Ca2+, nss-Mg2+ and K+ were found to be almost equal for both groups.
(2) The best variable ions with H+ were found by the regression program to be : (H++nss-Ca2++NH4+)=0.93 (nss-SO42-+NO3-)+3.6, r=0.94. The equivalent ratio of NO3- to SO42- was 0.52 in both (A) and (B) groups.
(3) The ratios of SO42- to alkalinity (CaCO3) in the mountain streams and the well waters (Fig. 1) were between 0.19 and 0.33. These ratios were lower than those of the average qualities of river waters from Japan and world.
