Uptake of selected organics and metals by terrestrial vegetation and insects at a site in Arizona

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 risk 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, PCBS, and total petroleum hydrocarbons. A field sampling program is underway to collect the food sources (i.e., terrestrial vegetation and ground-level herbivorous insects) for the indicator species. The samples will be analyzed for the COPCs and the results 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 with BAFs derived using published bioaccumulation models.