Perspective on Remediation and Natural Recovery of Contaminated Sediments

摘要

Sediments include material, particularly clays and organic matter, that control sediment cohesiveness. Cohesive sediments have large surface area-to-volume ratios, a net negative charge on their surface and exchangeable cations (1). Thus cohesive sediments adsorb both organic and inorganic contaminants strongly. Indeed the bulk of the contaminant load in watersheds is usually adsorbed to cohesive sediments that act as a transporting system for contaminants (2, 3). The contaminants in sediments, therefore, include a wide variety of organic compounds and metals adsorbed to the cohesive material (4). Metals in sediments cannot be destroyed but can be transformed by bioprocesses often to less available forms. The important organic contaminants belong to the high molecular weight organic classes, especially polychlorinated biphenyls (PCBs), highly chlorinated pesticides, dioxin/dibenzofurans and polynuclear aromatic hydrocarbons (PAHs) from widely used multicomponent aroclors, pesticides, and creosotes. These organics partition strongly to and persist in sediments (4, 5, 6). In addition, less widely used chlorinated organics such as hexachlorobenzene and trichlorobenzenes can be important contaminants at specific sites (4, 7).