Development of a rapid 14C-based field method for assessing potential biodegradation of organic compounds in soil and sediment samples

The objective of this investigation was to develop and implement a biodegradation assay that could be completed within hours in a mobile field laboratory. We sought to identify portable instruments that could function as alternatives to a standard beta-scintillation counter which, itself, is not readily transportable to a field setting. A beta-scintillation type survey meter responded linearly and with 29% efficiency in the laboratory when calibrated with standard 14C-bicarbonate solutions spotted and dried onto copper disks. Efficacy of the beta-probe/copper disk procedure in quantifying microbial mineralization activity was examined in laboratory incubations of sediment amended with both 14C-p-hydroxybenzoate and -naphthalene. The procedure was implemented in a field setting in which four field samples were processed in a mobile laboratory. Six percent of the 14C naphthalene was mineralized in 2 12 h by naphthalene-contaminated samples, while no activity was detected in samples from adjacent uncontaminated locations.