Relationship between biodegradation rate and percentage of a compound that becomes sequestered in soil

A study was conducted to determine whether the rate of biodegradation of phenanthrene determines the extent of its sequestration. Samples of a single soil type with different biodegradative activities were used. Various rates of biodegradation were obtained by use of different incubation temperatures, adding a bacterial culture or both. Much of the compound became biologically unavailable (sequestered) when the initial rates of biodegradation were slow, and little remained if the soil had high degradative activity. A portion of the compound remaining in soils with previously low activity was degraded if the soil samples were reinoculated and incubated under favorable conditions, but a significant amount of the compound was still microbiologically unavailable. The data show that the percentage of a compound that will be sequestered in a microbiologically unavailable form is determined by the initial rate of its biodegradation in soil.