Utilization rates of benzene and toluene from a BTEX-contaminated aquifer

A method for determining biodegradation kinetics of petroleum derived hydrocarbons in natural water samples was developed and applied to samples from a BTEX-contaminated aquifer. It is a modification of standard methods in which C-14-labeled substrates are incubated in natural samples and (CO2)-C-14 is measured to determine total utilization. As with other methods, this modification allows measurement of utilization and uptake, but it measures the remaining substrate and polar metabolic intermediates formed during biodegradation. The fate of the isotopic tracer is determined by mass balance. This method was applied to groundwater samples collected from a BTEX-contaminated aquifer in Port Hueneme, CA under the SERDP-CU030 project. Samples were collected just below the water table and used to determine the effects of a vertical groundwater circulation well on turnover rates of the contaminants by natural microbial assemblages.