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

Duke Swamp is a wetland ecosystem that receives 14C via a groundwater pathway originating from a waste management area on Atomic Energy Canada Limited's Chalk River Laboratories site. This groundwater reaches the surface of the swamp, resulting in relatively high 14C levels over an area of 146 m2. The objective of this study was to quantify 14C concentrations in flora and fauna inhabiting areas of Duke Swamp over the gradient of 14C activity concentrations in moss to determine whether 14C specific activities in receptor biota reflect the localized nature of the groundwater source in the swamp. Representative receptor plants and animals, and corresponding air and soil samples were collected at six sites in Duke Swamp with 14C specific activities in air that ranged from 1140 to 45,900 Bq/kg C. In general, it was found that specific activities of 14C in biota tissues reflected those measured in environmental media collected from the same sampling site. The findings demonstrate that mosses could be used in monitoring programs to ensure protection of biota in areas with elevated 14C, negating the need to capture and euthanize higher organisms.