Influence of Soil and Sediment pH and Redox Conditions on Degradation of Toxic Organics

by R. D. DeLaune, Louisiana State Univ, Baton Rouge, United States,
J. H. Pardue, Louisiana State Univ, Baton Rouge, United States,

Document Type: Proceeding Paper

Part of: Symposium on Ground Water


The presence of toxic organics in soil and sediments has raised concern over persistence and bioaccumulation. In the absence of oxygen, microbial degradation of toxic organics proceeds by the ability of organisms to use alternate electron acceptors such as nitrate, sulfate, iron and manganese oxides, and CO2. Redox (oxidation-reduction potential) and pH conditions in soil have been shown to influence rates of toxic organic degradation. Sediment pH and redox potential significantly affect PCB mineralization. Naphthalene and benzo(a)pyrene degradation are also influenced by soil redox conditions. The optimal soil redox conditions for degradation of various classes of organics are summarized. Excess concentrations of the electron acceptor nitrate enhanced naphthalene mineralization in soil. Sediment pH and redox conditions are two parameters which can be managed to enhance degradation of toxic organics in contaminated soil or sediment and would be important in evaluating persistence in restrictive subsurface environments.

Subject Headings: Soil pollution | Soil properties | Sediment | pH | Chemical degradation | Toxicity | Nitrates | Oxygen

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