Fate of dissolved toluene during steady infiltration through unsaturated soil .1. Method emphasizing chloroform as a volatile, sorptive, and recalcitrant tracer

Chloroform can be used as a volatile, sorptive, and recalcitrant tracer compound relative to volatile and transformable organic compounds, such as toluene, in aerobic unsaturated soil column experiments. Chloroform concentrations <4 mg/L did not affect the rate of toluene oxidation and chloroform itself was not transformed aerobically. In the current experiments, chloroform was applied at lower concentrations than the degradable compound. Chloroform was used to estimate the column mass balance without degradation so that mass loss for the degradable compound in the column could be confidently attributed to transformation. Consistent numbers of viable heterotrophic microorganisms in soil samples from column experiments with and without chloroform added suggest that the added chloroform did not have a negative effect on the soil microorganism population.