QUANTITATIVE ASSESSMENT OF GROUNDWATER QUALITY USING A BIOLOGICAL INDICATOR - SOME PRELIMINARY-OBSERVATIONS

The genotoxicity of groundwater was evaluated, using a novel applicati on of the SOS microplate assay (SOSMA), Organic residues were extracte d from groundwater samples from Maryland, Pennsylvania, and Delaware b y using C-18 bonded silica solid phase extraction tubes. Total organic carbon content (TOC) of water samples was also determined. The genoto xicity of the extracts was determined by the SOSMA. Relative activity (RA) as determined by the SOSMA is a quantitative measure of genotoxic ity based on a comparison-to the activity of the mutagen, 4-nitroquino line oxide. Low levels of RA (about 2 x background) were detected in w aters from sites within these states. There was considerable temporal and spatial variation in the observed RA, but no definite patterns wer e observed in the variation. Between sampling sites there was a positi ve correlation between RA and TOC; however, this relationship appeared to be reversed occasionally within a sampling site. The extraction an d bioassay methods provide an easy and relatively inexpensive means of determining water quality.