Evaluating bioremediation: distinguishing fact from fiction.

Bioremediation options encompass diverse types of biochemical mechanisms that may lead to a target's mineralization, partial transformation, humification, or altered redox state (e.g. for metallic elements). Because these various mechanisms produce alternative fates of the targeted pollutants, it is often necessary to use diverse evaluation criteria to qualify a successful bioremediation. Too often target depletion from a treated matrix can be mistakenly ascribed to biological activity when in fact the depletion is caused by abiotic losses (e.g. volatilization, leaching, and stripping). Thus, effective, and therefore convincing, evaluation requires that experimental and engineering designs anticipate all possible routes of target depletion and that these routes be carefully monitored.