Submitted to: Symposium on the Fate and Chemistry of Modern Pesticides Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 3/30/2001
Publication Date: N/A
Technical Abstract: Karst topography represents soluble-bedrock terrain typified by sinkholes, losing streams, springs, and cave passages. Karst basins with significant losing streams represent a particularly vulnerable setting for ground water. Two losing stream karst basins were chosen for intensive water quality monitoring: Hunters Cave and devils Icebox Cave. Year-round monitoring was initiated in April, 1999 with the objective of character- izing the water quality status of the main cave streams relative to herbicide, nutrient, and coliform bacterial contamination. Hydrogeologic parameters, including dissolved 02, temperature, conductivity, and turbidity, are also continuously monitored. Water samples for contaminants entails grab samples under baseflow at regular intervals and runoff event sampling using automated sampling equipment. Bacterial coliform analyses included quantitation ot total and fecal coliforms on a quarterly basis. In the first year, at least one herbicide or metabolite was detected in 60% of the Hunters Cave samples and 72% of the Devils Icebox samples. Median conentrations of frequently detected compounds ranged from 2 to 117 ng L**-1 with hydroxyatrizine having the highest median concentration in both caves. Total nitrogen (N) and phosphorus (P) concentrations have toma generally been lower than more intensively row-cropped watersheds within the region. Fecal coliform bacteria were generally below 200 cfu 100 mL**-1 in both caves, except under high flow conditions during early summer when levels can exceed 10,000 cfu 100 mL**-1. To date, the data indicate that the water quality impairment is greater for Devils Icebox than for Hunters Cave.