Bioaccessibility of U, Th and Pb in solid wastes and soils from an abandoned uranium mine

Abstract

Bioaccessible U, Th, Pb and the U decay productsPb and Pb have been determined, using a modified Unified BARGE Method (UBM), in waste solids and soils from an abandoned uranium mine in South West England, UK. Maximum aqua regia extractable concentrations for U, Th and Pb were 16,200, 3.8 and 4750 μg g, respectively. U had highest activity concentrations near the mine shaft, where the decay productsPb and Pb had values of 235 and 180 Bq g, respectively. UBM extractions gave mean gastro-intestinal bioaccessibility factors (BAFs) for U and Pb in the waste solids of 0.05 and 0.03, respectively, whereas those for the soils were significantly higher at 0.24 and 0.17. The mean BAFs for the transient radionuclides, Pb andPb, were similar to those for stable Pb implying that the stable and radioactive Pb isotopes were attached to similar sites on the particles. The doses arising from the ingestion of particulate Pb due to soil pica behaviour were in the range 0.2-65 and< 0.1-6.2 μSv day for a 1-year old child or an adult (>17 years), respectively. The results suggest that the health risk posed by abandoned uranium mines, with waste rock and tailings, throughout the world should take account of the dose due to both bioaccessible radionuclides, as well as their stable counterparts.

Multiple environmental factors influence 238U, 232Th and 226Ra bioaccumulation in arbuscular mycorrhizal-associated plants

“…Soil chemistry characteristics may also underpin the correlation. It has been observed that U minerals at South Terras are Cu-phosphate and Cu-arsenate rich, such as metatorbernite and metazeunerite, and were present at depths of ~25 cm (Corkhill et al, 2017;Foulkes et al, 2017;Purvis et al, 2004), consistent with the rhizosphere soils analysed here. In addition to a close association between U, Cu and P in these soils, Cu and P showed similar chemical behaviour to U as determined by sequential extraction analysis (Corkhill et al, 2017).…”

“…South Terras and Needle's Eye are two ideal field locations for the characterisation of radionuclide transfer from soil into the understory vegetation of temperate woodland. While there has previously been substantial radiochemistry research at Needle's Eye and, to a lesser extent, South Terras (Basham et al, 1991;Corkhill et al, 2017;Foulkes et al, 2017;MacKenzie et al, 1991;Siddeeg et al, 2015), no previous study has investigated the radioecology of these sites. Both locations have soils with 238 U concentrations that greatly exceed the global average (UNSCEAR, 2000) and were similar to or exceeded values determined by a number of radioecology surveys (Blanco Rodriguez et al, 2010;Vera Tomé et al, 2003;Vera Tomé et al, 2002).…”

Spatial Mobility of U and Th in a U-enriched Area (Central Portugal)

“…However, the effect of naturally occurring radioactive material (NORM) and the impact of solid waste on human health are not understood [9]. There are abandoned mines in France [10], Poland [11], Portugal [12], the United Kingdom [13], and Spain [14], where workers and citizens are exposed to human health risks. In Portugal, more than 60 uranium mines were developed, including underground and/or open-pit mines.…”

Linking oral bioaccessibility and solid phase distribution of potentially toxic elements in extractive waste and soil from an abandoned mine site: Case study in Campello Monti, NW Italy

“…For example, Pelfrêne et al, (2012) quantified bioaccessible concentrations of Cd, Pb and Zn as 78%, 32%, and 58% respectively on smeltercontaminated agricultural soils in a coal mining area of northern France. Foulkes et al, (2017) applied the UBM method to measure bioaccessibility of Pb, Th, and U on solid wastes and soils from an abandoned uranium mine site in South West England. However, in Italy there is little to no attention towards inclusion of oral bioaccessibility in studies reporting HHRA (Kumpiene et al, 2017).…”