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EVALUATION OF A DAPHNIA BIOMONITOR FOR REAL-TIME DRINKING WATER SOURCE TESTING
Citation:
VonderHaar, S. S., E. R. Krishna, AND R C. Haught*. EVALUATION OF A DAPHNIA BIOMONITOR FOR REAL-TIME DRINKING WATER SOURCE TESTING. Presented at 22nd Annual SETAC Conference, Baltimore, MD, 11/11-15/2001.
Description:
The quality of drinking water sources has come under closer scrutiny in recent years. Issues ranging from ecological to public health, to national security are under consideration. With advances in electronic and computer technology, biomonitors are being developed that can assess the toxicity of water samples by monitoring living organism behavior. The USEPA funded a study to determine if the bbe-Daphnia-Toximeter (a real-time biomonitor) is a useful and reliable tool for determining the real-time quality of drinking water sources. The instrument was brought into operation at the USEPA T&E Facility in Cincinnati, OH beginning 10/2000. The primary objectives of the tests are to: 1) evaluate the discriminatory ability of the bbe-Daphnia-Toximeter, and 2) evaluate the reproducibility of the results. Test waters have included reconstituted hard water and a rural surface water. Tests conducted to date have evaluated the following: controls, pH adjustment, exposure to cadmium--as cadmium nitrate--at 3 concentrations (2.5, 0.5 and 0.1ppm), and varying periods (2-4 hrs) of chemical exposure. An internal video camera records daphnia behavior during the testing period. The software in the unit is used to monitor the activity of each organism and evaluates their status continually. The bbe-Daphnia-Toximeter has the capacity to monitor 8 behavioral parameters including an integrated parameter called the toxicity index, which provides an ovewrall status of the daphnia during testing. Overall sensitivity of the daphnia as determined by the biomonitor was heightened in natural water as compared to reconstituted water. A trend toward a dose response to cadmium was observed in all waters tested. A synergistic effect of pH and cadmium exposure was observed. Additionally, responses were noted that are related to biofilm growth as well as the holding time of natural water.