title: Exposing water samples to ultraviolet light improves fluorometry for detecting human fecal contamination.
abstract: Fluorometry identifies human fecal contamination by detecting optical brighteners in environmental waters. Because optical brighteners are sensitive to sunlight, we determined if we could improve fluorometry by exposing water samples to ultraviolet (UV) light to differentiate between optical brighteners and other fluorescing organic compounds. Optical brighteners were likely present when the relative percentage difference in fluorometric value of the water before and after UV light exposure was >30% (glass cuvettes, 30 min exposure) or >15% (polymethacrylate cuvettes, 5 min exposure). In a blind study, we correctly identified the presence or absence of optical brighteners in 178 of 180 (99%) of the samples tested with a more expensive field fluorometer and in 175 of 180 (97%) of the samples tested with a less expensive handheld fluorometer. In the field, the method correctly identified two negative and three positive locations for human fecal contamination. When combined with counts of fecal bacteria, the new fluorometric method may be a simple, quick, and easy way to identify human fecal contamination in environmental waters.
authors.affiliation: Department of Crop and Soil Sciences, 3111 Plant Sciences, University of Georgia, Athens, GA 30602-7272, USA. pghartel@uga.edu
authors.forename: Peter G
authors.initials: PG
authors.lastname: Hartel
authors.forename: Charles
authors.initials: C
authors.lastname: Hagedorn
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: McDonald
authors.forename: Jared A
authors.initials: JA
authors.lastname: Fisher
authors.forename: Michael A
authors.initials: MA
authors.lastname: Saluta
authors.forename: Jerold W
authors.initials: JW
authors.lastname: Dickerson
authors.forename: Lisa C
authors.initials: LC
authors.lastname: Gentit
authors.forename: Steven L
authors.initials: SL
authors.lastname: Smith
authors.forename: Nehru S
authors.initials: NS
authors.lastname: Mantripragada
authors.forename: Kerry J
authors.initials: KJ
authors.lastname: Ritter
authors.forename: Carolyn N
authors.initials: CN
authors.lastname: Belcher
mesh_terms: D005243:Feces / Q000382:microbiology*; D005470:Fluorometry / Q000379:methods*; D005618:Fresh Water / Q000382:microbiology; D006801:Humans; D014466:Ultraviolet Rays; D014873:Water Pollutants / Q000032:analysis*
chemical_list: D014873:Water Pollutants