Abstract

From July 1994 to March 1995, eighteen variables of physico-chemical factors including heavy metals, and of bacteria in the four reservoirs of Kyonggi-Do were investigated to examine the effects of acidic precipitation to bacterial population. The pH range in the study area is from 6.56 to 10.24, which also showed seasonal change extensively compared to other factors. The correlation analysis showed that pH has a significant positive correlation (mean 79%) with the microbial populations in Wangsong reservoir. By multiple regression analysis on all of the seasons and stations, good explanation was obtained for the variation in total direct count of bacteria (71% and 88%, respectively), and the plate count of heterotrophic bacteria (76% and 88%, respectively). In the surface water of Wansong reservoir, the variation of total count of bacteria was affected by the S/O (soluble sugar/total organic matter ratio) value and the pH, and that of the plate count of heterotrophic bacteria was explained as 63% by pH. However, in other stations they were explained by the NO₂, total organic matter (TOM), soluble sugar (SS), temperature, and dissolved oxygen as 21~91%. On the basis of the results, the bacterial populations on the media at pH 3.0, 4.0, 5.0, 6.0 and 7.0 were compared to determine the effects of acidic proceeding. All the colonies grew the best on the media of pH 7.0, but started to decrease from pH 5.0.

• Keywords: pH; population; environmental factors; multiple regression