PARENT SESSION
WP5 - Riverine Discharge of Contaminants to Coastal Systems
Chair: Standley, Laurel1, 1 109 I Chestnut Crossing Drive, Newark, DE
2:10 PM to 5:30 PM - Wednesday, 20 November 2002
Room Ballroom D
(611) Improving the Use of Molecular Tracers in Apportioning Nonpoint Contaminant Sources.
Standley, Laurel*,1, 1 Stroud Water Research Center, Avondale, PA, US
ABSTRACT- Nonpoint sources currently contribute substantially to water quality degradation yet are difficult to assess in a defensible regulatory manner. For example, sources such as septic systems and sewage treatment plants, agricultural runoff, urban/suburban runoff, and wildlife contribute contaminants that include nutrients, pesticides, pharmaceuticals, personal care products, heavy metals, and pathogens to freshwater ecosystems. The use of molecular tracers to identify sources of contaminants is an emerging technique that links the presence of components unique to these sources with contaminants of concern. This quantitative link is essential for developing budgets for use in regulatory assessments of the predominant contributors to water quality degradation. In the work presented here, I investigated the fate of these tracers in surface waters to improve their utility in quantitative source apportionment. Tracers studied included fecal steroids (to track fecal matter sources such as human, agricultural manures, and wildlife), caffeine and fragrances (used to assist in separating human from agricultural and wildlife sources of fecal matter), and PAHs (used to track road runoff). Tracers were extracted using 90 mm Empore disks, silylated with MSTFA, and analyzed using gas chromatography (DB1701)/electron impact mass spectrometry (selected ion monitoring). Total rates of degradation for fragrances was approximately the same as for most PAH, e.g. - 0.01 to -0.02 per hour. Interestingly, caffeine decomposition was negligible over the 14 d exposure period.
Key words: molecular tracers, nonpoint source contamination, rivers, fate and transport