Effect of Inorganic Nutrients on the Acclimation Period Preceding Mineralization of Organic Chemicals in Lake Water

摘要

Biodegradation of many synthetic organic chemicals does not appear to proceed immediately after the first introduction of the compounds into surface waters, ground-water, soils, or sediments, and loss of the chemical is evident only after an acclimation period. The acclimation period may reflect the time for a small population of mineralizing microorganisms to increase to a size that is adequate to cause detectable mineralization. According to this hypothesis, the length of the acclimation period depends on the rate of growth of the microorganisms that are responsible for degrading the chemical. The addition of phosphate, nitrate, or sulfate (each at 10 mM) decreased the acclimation period for the mineralization of low concentrations of p-nitrophenol (PNP) in lake water. Added phosphate shortened the acclimation period for biodegradation of 2 ng to 2 micrograms of PNP per ml in various lake water samples and of 2,4-dichlorophenoxyacetate at 100 ng/ml. Added P enhanced the rate of growth of PNP-mineralizing microorganisms in waters containing 2 ng or 2 micrograms of PNP per ml. We suggest that the effect of P on the acclimation period results from an increase in the growth rate of the initially small population of microorganisms able to mineralize the synthetic chemicals. Reprints. (EDC)