University Presentation Showcase: Graduate Poster Gallery



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Creation Date

Spring 2015


Master of Public Health


Environmental Health Science




Jason W. Marion

Mentor Department

Environmental Health Science


E.coli densities are used for determining water quality and illness risks for swimmers who utilize untreated recreational waters (e.g. lakes, rivers, oceans etc.). Existing approaches for measuring fecal indicator bacteria take 18-24 hours, which takes too long since water conditions may change during this timeframe thereby swimmers at increased risk. More rapid methods for water quality determination include lake-specific predictive models as well as expensive molecular methods. An alternative approach to be considered would be to use tryptophan fluorescence in real-time. Tryptophan is an essential amino acid released from digestion and has been used in wastewater management. In this study 30 samples from two recreational lakes were collected and evaluated for E.coli, transparency, nitrate and total phosphorous. Tryptophan was measured at 17 cm and 1 m depths in real-time with a handheld Turner Designs fluorometer. Spearman correlation analysis revealed significant positive associations between tryptophan levels and E.coli (Rho =0.5644; p = 0.0012) and an inverse relationship between water transparency (secchi depth) and tryptophan at 17 cm (Rho = -0.6033; p = 0.0004). Aggregated tryptophan levels were not associated (p > 0.05) with phosphorous or nitrates levels, although total phosphorous was positively associated with E.coli and nitrates. Presently, results are inconclusive at the lake-specific level and additional samples are being collected to increase sample size. In the aggregate (combining both lakes), tryptophan levels are indicative of fecal bacteria densities, which potentially could be used by health officials issuing swimming advisories and as well as routine monitoring beach water quality instantaneously.