Do site-specific radiocarbon measurements reflect localized distributions of 14C in biota inhabiting a wetland with point contamination sources?

Predicting exposure of wildlife in radionuclide contaminated wetland ecosystems

“…However, for trees, all predictions were consistently higher (up to a factor of 4) than measured data. Yankovich et al (2013a) reports that previous studies observed an exponential decrease in 14 C specific activity concentrations in vegetation with height above ground at this site, possibly the consequence of activity concentrations in air reducing with height as 14 CO 2 and 14 CH 3 disperse with distance from the source (i.e. the ground surface).…”

“…Four groups used the ERICA Tool, of which two used included default transfer parameters (concentration ratios, CRs) Hosseini et al, 2008) and two Table 3 Summary of organisms included in the scenario (Anderson et al, 1973;Brisbin et al, 1974b;Dapson and Kaplan, 1975;RAC, 2001 e Chapter 11;Stark et al, 2004;Stark unpublished data;Yankovich et al, 2013a used CRs from the IAEA technical report series (TRS) handbook on wildlife transfer (IAEA, 2014;Howard et al, 2013;Yankovich et al, 2013b). The handbook on wildlife transfer, referred to as the TRS in the subsequent text, was also used with RESRAD-Biota and K-Biota applications.…”

“…3) is a 0.102 km 2 wetland in the Atomic Energy of Canada Limited's Chalk River facility in Ontario, Canada (N46 02 0 40 00 , W77 24 0 40 00 ) that receives radionuclides, including 14 C, through groundwater transport from a waste management area situated approximately 400 m east of the swamp (Kim et al, 2011;Yankovich et al, 2008a). Past assessments indicated that the primary contributor to dose to biota is likely to be 14 C (Zach et al, 1998) from 14 C volatilised into the atmosphere rather than via direct transfer from groundwater (Yankovich et al, 2013a). A detailed survey of 14 C in soil to a depth of 5 cm and surface vegetation had been conducted.…”

“…A subset of locations was selected for detailed biota sampling to obtain a range of activity concentrations across Duke Swamp. Samples included in this study were of soil, air, vegetation, invertebrates, amphibians, reptiles, and rodents (Yankovich et al, 2013a, Table 3). …”

“…Within these programmes biota dose model inter-comparisons were performed for terrestrial Johansen et al, 2012), and freshwater lake ecosystems (Yankovich et al, 2010;IAEA, in press). These studies showed that model results can vary by up to three orders of magnitude in dose predictions Johansen et al, 2012), with most variation attributed to modelled uptake of radionuclides by organisms.…”