MP13 Aquatic Ecotoxicology
Monday, 14 November 2005: 8:00 AM - 6:30 PM in Exhibit Hall

(MOU-1117-831687) Laboratory and Field Studies to Quantify Responses of Daphnids to Combined PAH and UV Light Exposure.

Mount, D¹, Diamond, S¹, Erickson, R¹, Heinis, L¹, Highland, T¹, Hockett, J¹, Jenson, C¹, Prihoda, K¹, ¹ U.S. EPA/ORD, Duluth, MN, USA

ABSTRACT- Hazard from photo-activation of PAHs has been well documented for several aquatic organisms. Far less certain is the degree to which risk actually occurs in the field. This presentation outlines a series of laboratory and field experiments conducted to better understand the dosimetry and effects of simultaneous UV and PAH exposure in the cladoceran, Daphnia magna. In the laboratory, pyrene was used as a model PAH for establishing basic exposure-response relationships. Simultaneous exposures to pyrene and artificially-produced UV light were used to determine the relationship between aggregate UV/PAH exposure and time to mortality. Age-specific exposures indicated that 1-2d old neonates had slightly higher sensitivity than did organisms 4d and older. Chronic testing showed very little effect of UV/PAH exposure on reproduction in treatments where adult survival was not also affected. In situ exposures at a PAH-contaminated site were also conducted, with simultaneous exposure to a range of sunlight intensities. Both PAH and UV exposure varied both daily and seasonally. Exposure-dependent mortality was observed in excess of that attributable to UV exposure alone. We discuss these findings in the context of assessing risk from photo-activation at PAH-contaminated sites. This abstract does not necessarily reflect EPA policy.

Key words: PAH, ultraviolet light, photo-activation, daphnid