Some Ecological Factors in the Degradation of 2, 4-Dichlorophenol in Waters from Aquatic Environments

Abstract

The relationships between the degradation of 2, 4-dichlorophenol (DCP) and the changes in the density of DCP-degraders were examined in water samples from aquatic enviroments. In most of the water samples, the rapid degradation of 1 μg DCP-C·ml^-1 or 0.1, μg DCP-C·ml^-1 was observed, after a lag period lasting for more than a week, when DCP-degraders had increased to 10⁴-10⁵ cells·ml^-1 or 10³-10⁴ cells·ml^-1, respectively. However, in the water sample from the spring Masugata-no-ike, the degradation of 0.1 μg DCP-C·ml^-1 was not observed for 42 day incubation, although DCP-degraders had increased to 104 cells·ml^-1 at 35-day incubation. When both nitrogen and phosphorus were added to the water sample, the rapid degradation of DCP was observed. These results suggested that the sufficient increase in the density of DCP-degraders was a prerequisite condition for the degradation of DCP, but ecological factors such as mineral nutrients might limit the expression of the ability of DCP-degraders even when their densities were high.