Evaluation of a New Rapid Method for Determining Recreational Water Quality
thesisposted on 24.10.2013 by Thomas J. Vroman
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Evaluation of a New Rapid Method for Determining Recreational Water Quality Abstract For 25 years, the US Environmental Protection Agency (EPA) has relied on a standard test to determine the bacterial concentration in recreational waters. This test involves taking a water sample, filtering it, and incubating it for 24 hours in a Petri dish. This means that recreators and beach managers do not know the actual bacteria concentration of the water until the next day, resulting in overexposure to harmful bacteria. The EPA has allocated funding to stimulate research into developing a rapid method to determine the bacterial water concentration. One of the new methods being evaluated is called Immunomagnetic Separation, Adenosine Tri-phosphate Bioluminescence, or IMS/ATP for short. This method uses antibodies to select for specific bacteria, small iron beads to bind to these antibodies, and magnets to separate out the beads from the rest of the water. Once separated, the concentration of bacteria is estimated through the measurement of luminescence. This method can return results of bacterial concentration in water within two hours of sampling. For this study, this method was evaluated in the Chicago area waterways in the summer of 2009. The IMS/ATP analysis ran concurrent to the Chicago Health, Environmental Exposure, and Recreation Study, or CHEERS, which involved the collection of water samples and their analysis for bacteria and other microbes from 2007–2009. Researchers from CHEERS were trained by US Geological Survey (USGS) employees on how to run the IMS/ATP method, and results from IMS/ATP can be compared to the EPA standard methods, that were already being performed as part of CHEERS. This report can be viewed as an experimental method evaluation, evaluating accuracy, precision, and repeatability of a new method. The data show that the method performed well on repeatability and precision, but performed poorly on accuracy. Overall, the new IMS/ATP method did a poor job of predicting bacterial concentrations found by the EPA standard methods.