Uptake of Selected Organics and Metals by Terrestrial Vegetation and Insects at a Site in Arizona. C. H. Day, A. Ayers, S. B. Ellingson, L. Braddy, and S. L. Sager, Geraghty & Miller, 11000 Richmond, Ste. 350, Houston, TX; and 2840 Plaza Place, Ste. 350, Raleigh, NC 27612
As part of an investigation at a CERCLA site in Arizona, 27 potential sources of contamination (PSCs) were identified for study. A screening level ecological risk assessment was conducted for each PSC using generic plant uptake factors and conservative exposure parameters. Risk estimates were calculated for the indicator species using the hazard index (HI) approach. Results of the screening level assessment indicated that 4 of the 27 PSCs required further evaluation due to elevated HIs. The contaminants of potential concern (COPCs) are antimony, cadmium, lead, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and total petroleum hydrocarbons (TPH). A field sampling program at the 4 PSCs and a site-specific background location was conducted to collect the food sources (i.e., terrestrial vegetation and ground-level herbivorous and grainivorous insects) for the indicator species (round-tailed ground squirrel, western whiptail lizard, and desert cottontail). The samples have been analyzed for the COPCs and the results are being used to validate the screening level risk calculations. The site-specific soil-to-plant uptake factors will be compared to generic soil-to-plant uptake factors obtained from the scientific literature, with emphasis placed on studies done in similar arid environments. Contaminant-specific soil-to-insect bioaccumulation factors (BAFs) will be presented and compared to BAFs derived using published bioaccumulation models.