Based on conservative, reasonably thorough and careful evaluation of scientific studies described in this report, there is no doubt that chemical wastes in soil can be, and often are, in a state of reduced bioavailability. An analysis of the literature on bioremediation research concludes that bioremediation of chemical wastes in soils and sediments is rarely 100 percent efficient, due at least in part to the reduced bioavailability of the chemical. Reduced bioavailability simply means that a chemical wastes diminished effective concentration is proportionately balanced by a lingering reservoir of the chemical waste in soil and sediments. This lingering reservoir remains in the soil habitat regardless of which combinations of conceptual or actual sequestration mechanisms (e.g., complexation into bound residues, diffusion into soil pores, NAPL partitioning) apply.

Funded by the U.S. Environmental Protection Agency under contract number T28006: QT-DC-99-003260 to Cornell University -- p. ii. "October 2003"--Page 4 of cover. "EPA 600-R-03-076."--Page 4 of cover. Includes bibliographical references (pages 105-122).