Title: Human impacts on subsurface microbiological processes

Background
Subsurface microbiological processes are of considerable interest to environmental engineers and scientists. These processes involve both the metabolic activities of bacteria and the interactions between bacteria and the soil grains. The metabolic activities of subsurface bacteria are extremely important in maintaining the nutrient cycles in topsoil, and they define the rate and extent of biodegradation of subsurface contaminants, such as petroleum hydrocarbons and chlorinated solvents. The interactions between bacteria and soil grains are important in providing bacterial access to soil-bound nutrients and energy sources. These interactions are also the dominant mechanism for the removal of pathogenic organisms from waste streams, such as septic tank effluents, and are important in maintaining the microbiological quality of drinking water from groundwater aquifers.

Purpose
The purpose of this project is to explore the effects of anthropogenic contaminants on these microbiological processes. Two sets of experiments will be conducted. The first will examine the effects of anthropogenic contaminants on the metabolic activity of bacteria, and the second will examine the effects of contaminants on the transport of bacteria through an aquifer sand.

Research Objectives
The main objective of this research is to investigate the relationship between the aqueous concentration of the contaminants and their effects on the microbiological processes. Understanding the effects of concentration is extremely important in determining the potential for alteration of subsurface microbiological processes. These concentration effects are used in risk assessment analyses for developing remediation goals and they are also used when defining or refining water quality standards.

Educational and Scientific Impact
The experiments will expose the participants to a range of laboratory and data analysis techniques for measuring metabolic activities of bacteria and monitoring the transport of bacteria through laboratory columns. The results of these laboratory experiments can be extrapolated to the field-scale to demonstrate the potential magnitude of the effects anthropogenic contaminants can have on microbiological processes. Most importantly, the experimental results will provide additional scientific data in this field, especially in the area of bacterial transport, where there is little understanding of contaminant concentration effects.

Web Links
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Readings and References
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