Interactions between subsurface microbial assemblages and mixed organic and inorganic contaminant systems

Abstract

Metals are introduced into aquatic environments as results of mining and refining of ores and other human activities, such as combustion of fossil fuels, spraying of pesticides, and disposal of domestic and industrial wastes. Synthetic chelating agents have been used for nuclear decontamination, waste processing, and detergent industry because they react with radionuclides and heavy metal ions and form stable water-soluble complexes. Co-disposal of synthetic chelating agents with radionuclides and/or heavy metals at some landfill sites for energy and industrial wastes have caused increase in organic-inorganic mixtures transport in the subsurface environment. The extensive presence and the possible persistence of these waste mixtures in those environments underlines the need to study their effects on aquatic microbial assemblages. To remediate a contaminated aquifer, the microorganisms must not be severely inhibited by the chemical pollutants. In this research, the effects of selected chemical contaminants (organic and inorganic species) on ground water bacteria and a mixture of model organic and inorganic chemicals (i.e., imidazole and copper) on surface and subsurface bacteria were determined. Adaptation of microorganisms to in situ contaminants may be the prerequisite for microbial degradation to occur. In addition, some environmental factors such as concentrations of inorganic nutrients may limit ormore » affect biodegradation of subsurface organic pollutants. Microbial degradative activity in ground water of a chemical waste landfill site in Georgia and in ground water samples from California were the focus of this study. Effects of inorganic nutrients on microbial degradation of toluene, p-cresol, and phenol in ground waters were evaluated. 14 refs., 3 figs., 1 tab.« less