Response of the microflora in outdoor experimental streams to pentachlorophenol: environmental factors

The 2nd year of a 2-year study of the fate of pentachlorophenol in outdoor artificial streams focused on details of microbial degradation by a combination of in situ and laboratory measurements. Replicate streams were dosed continuously at pentachlorophenol concentrations of 0, 48, and 144 μg/L, respectively, for an 88-d period during the summer of 1983. Pentachlorophenol was degraded both aerobically and anaerobically. Aerobic degradation was more rapid than anaerobic degradation. Mineralization of pentachlorophenol was concommitant with pentachlorophenol disappearance under aerobic conditions, but lagged behind loss of the parent molecule under anaerobic conditions. Biodegradation in the streams, or in specific stream compartments such as the sediment or water column, was characterized by an adaptation period (3–5 weeks for the stream as a whole, and reproducible from the previous year), which was inversely dependent on the concentration of pentachlorophenol and microbial biomass. The adaptation in the ...