UNCERTAINTY AND RESEARCH NEEDS IN THE AREA OF THE BIOLOGICAL RESTORATION OF CONTAMINATED SEDIMENTS

摘要

A large array of microbial processes are taking place in aerobic or subsurface anaerobic sediments, where they are responsible for the turnover of naturally occurring organic matter and the N, P, S geochemical cycles (Kafkewitz and Togna, 1998). Oxidizing conditions generally exist only at the top few centimeters of surface sediments, providing a limited zone where oxygen is available as electron acceptor for aerobic biotransformation of organic and inorganic chemical compounds. Beneath the aerobic zone, sediments are typically dominated by a single electron acceptor process such as sulfate-reduction in marine sediments or methanogenesis in freshwater sediments. Bacteria and eukaryotic organisms are coexisting in such matrices, by strictly interacting and cooperating through complex and often not fully elucidated mechanisms. The microbial population might be responsible for the biodegradation/biotransformation of several chlorinated priority pollutants, such polychlorinated-biphenyls, -dibenzodioxins, -dibenzofurans, -phenols and -benzenes, as well as some hydrocarbons, in particular under anaerobic conditions. Under sulfidogenic conditions, it might be also responsible for the precipitation/immobilization of some toxic heavy metals (Lloyd and Lovley, 2001). These microbial