Primordial radionuclides in Canadian background sites: secular equilibrium and isotopic differences

Using short-lived nuclides of the U- and Th-series to probe the kinetics of colloid migration in forested soils

“…These latter are maximum values, due to the few percent of 228 Th that are possibly lost during the ashing step. Sheppard et al (2008) have reported a similar 228 Th excess over 232 Th (average ( 232 Th/ 228 Th) = 0.25) in a broad range of plant species. However, in this latter case, the mean ( 228 Ra/ 228 Th) ratio around 12 easily explains such 228 Th excess from 228 Ra ingrowth, unlike the present study.…”

Lichens and Particulate Matter: Inter-relations and Biomonitoring with Lichens

“…Uğur et al (2003) 210 Po activity and Pb and Fe content in lichens around coal-fired power plants, attributed to the emissions produced in the process of combustion of fossil fuels. Sheppard et al (2008) determined the activity ratio 210 Po/ 210 Pb for Canadian background sites indicating unity (1.0) in soils and lichens, whereas annual plant tissue diverged to an extent of 0.6. Lichens and mosses attained as expected, exceptionally high plant/soil concentration ratios (CRs) for 210 Pb,210 Po, and 226 Ra, as cryptogams retain atmospheric particles rather effectively.…”

Gold and Uranium

“…Meriwether et al [30] measured U in soils of Louisiana, the state that has the lowest average radiation exposure rate in the United States, based on the activity of 214 Bi, one of the members of the 238 U decay series, in order to estimate U concentrations, which ranged [31] measured U in topsoil from seven sites across Canada by neutron activation-delayed neutron counting (DNC), with a detection limit of 0.1 mg kg À1 . The uranium concentrations in these soils ranged between 0.4 and 2.6 mg kg À1 .…”