Event: SETAC North America 32nd Annual Meeting, October 4, 2011
Title: Modeling Bioaccumulation Potential of Cs137 in Marine Food Web of NW Pacific, Canada
Authors: Prof. Frank Gobas, Simon Fraser Univ.; Prof. Juan Alava, SFU
Abstract: The Fukushima nuclear emergency […] emerged as a high priority looming threat due to the risk of radioactive contamination in the global ocean and biodiversity. […] we assessed the bioaccumulation potential of 137Cs by testing steady state and time-dependent bioaccumulation models in an offshore food web that included fish-eating, resident killer whales (Orcinus orca) as one of the major top predators of the marine ecosystems in British Columbia, Canada.
Steady State Bioaccumulation Model: “Concentrations of 137Cs predicted in the male killer whale were approximately three orders of magnitude higher relative to its major prey, Chinook salmon, and 13,000 times higher compared to phytoplankton.” Time-Dependent Bioaccumulation Model: “After 30 days of radioactive spillage, the 137Cs concentrations accumulate gradually over time in high trophic level organisms (salmon and killer whales), which exhibited low concentrations likely driven by slow intake rates, while it bioaccumulates at faster uptake rates in low trophic level, gill ventilating organisms (phytoplankton, zooplankton, benthic invertebrates and planktivorous fish), exhibiting concentration about one to two orders of magnitude greater than that in killer whales. At 9125 days (25 years), the predicted concentrations of 137Cs accumulate in a higher degree in killer whales, being >2 orders of magnitude greater than that predicted in Chinook salmon and 10,000 times higher relative to phytoplankton. The levels of 137Cs predicted in biota (shellfish and fish) exceeded well above the 137Cs action level for commercial food/beverage of 1000 Bq/kg established by the Canadian Guidelines for Consumption following a Nuclear Emergency (emphasis added).”