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 trace r compound relative to volatile and transformable organic compounds, s uch as toluene, in aerobic unsaturated soil column experiments. Chloro form concentrations <4 mg/L did not affect the rate of toluene oxidati on and chloroform itself was not transformed aerobically. In the curre nt experiments, chloroform was applied at lower concentrations than th e degradable compound. Chloroform was used to estimate the column mass balance without degradation so that mass loss for the degradable comp ound in the column could be confidently attributed to transformation. Consistent numbers of viable heterotrophic microorganisms in soil samp les from column experiments with and without chloroform added suggest that the added chloroform did not have a negative effect on the soil m icroorganism population.