Numerous evidence continues to support the declining availability of contaminants residing in soil for a long period of time. These evidence point to sequestration, a phenomenon often measured by the absence of lethality of the toxic chemicals, a view often presented in the evaluation of health and ecological significance. Because these assumptions are relevant to human health and public policy, it is important to evaluate the long-term safety of """"""""sequestered"""""""" chemicals. Our specific goal is to determine whether chemicals that have been sequestered in soil over time no longer pose any significant risk of exposure to human and other bioreceptors. Our first objective is to obtain soils in which sequestration of chemicals have taken place. Our second objective is to identify specific environmental factors such as temperature, pH, moisture regimen, organic matter, presence of polymer producing bacteria that may influence the release of sequestered chemicals. Our third objective is to determine the magnitude of influence of each factor on chemical that have been sequestered in soils. Changes in environmental conditions and the extent to which they may influence the release of sequestered contaminants are unknown. For example, many microbial consortia are able to produce extracellular polymers in aquatic habitats. It remains to be determined whether such polymer-producing microbial consortia may produce similar effect in soil environment. Different microorganisms isolated and used in soil will provide sufficient data to quantify the extent to which they may influence contaminant release. Our fourth objective is to quantify the extent by which specific microorganism will alter of sequestered organic contaminant as a function of microbial density. Different microorganisms able to stimulate the release of sequestered contaminants will be studier further and their products isolated. The long term goal is to provide sufficient evidence to prove that chemical sequestration is indeed a safe and naturally occurring process that will permanently trap environmental contaminants and prevent future exposure to human or bioreceptors. This funding is important because current innovative technologies such as bioremediation may not remove all of the contaminants from soil. Secondly, this finding may contribute to the effort in establishing the scientific basis for determining environmentally acceptable endpoints in soils.
