Ra-226 concentrations in blueberries Vaccinium angustifolium Ait. Near an inactive uranium tailings site in Elliot Lake, Ontario, Canada

Abstract

Ra-226 concentrations were measured in blueberries (Vaccinium angustifolium Ait., late low blueberry) growing around the Stanrock uranium tailings area near Elliot Lake, Ontario, Canada. Elevated levels of total Ra-226 ranging between 20–290 mBq g⁻¹ (dry weight) were observed in samples collected within 500 m from the tailings. Highest levels, ∼285 mBq g⁻¹, were observed in a sample collected on a tailings spill. For sites located more than 500 m away in the upwind direction, and those situated at distances greater than 1 km downwind from the waste pile, the total Ra-226 concentrations approached background levels which were measured as 2–6 mBq g⁻¹. Approximately 17% of the total Ra-226 measured was removable by washing the samples with distilled water. Wind dispersal of the tailings material and its deposition in the form of dust on blueberries was believed to be responsible for the external contamination. Based on the ICRP recommended dose limits for oral intake of Ra-226, it was calculated that approximately 160 kg a⁻¹, 3350 kg a⁻¹ and 47 kg a⁻¹ of washed blueberries (wet weight) from inside (less than 500 m) and outside (greater than 1 km downwind) the influenced zone, and from the tailings spill site (where the highest Ra-226 levels in blueberries were measured), respectively, would need to be consumed before the individual annual limit for the general public was exceeded.