Radionuclides in Louisiana Soils

Abstract

Concentrations of natural and man‐made radionuclides including 40K, 137Cs, and some of the decay products of 238U and 232Th were determined in soil. Samples were taken at a set of permanent radiation monitoring stations and from random points across the state of Louisiana. The concentrations of the radionuclides were found to be correlated with soil suborder: the lowest values found in the Udults of the northern portion of the state and the highest concentrations found in the Aquepts of the flood plains and the Hemists of the coastal marshes, suggesting that processes such as weathering, transport of solids, and dissolution may be fractionating these elements into soils of water environments. The concentration of K was found to vary from 3180 to 24 900 mg kg−1; U varied from 2.3 to 4.0 mg kg−1; and Th from 8.0 to 24.1 mg kg−1. Cesium‐137, the fission product, was found only in the top 15 to 20 cm of the soils with no statistically significant aerial distribution across Louisiana.

Distribution of natural radionuclides and 137Cs in soils of southwestern Ontario

“…The mean activity of 40 K is similar to values for soils in parent materials of Saskatchewan (de Jong et al 1994) but much greater than podzolic soils in the Hudson and James Bay Lowlands (VandenBygaart and Protz 1998). Assuming there is a drop in activity of approximately 67% in the decay of 232 Th to 208 Tl (Kiss et al 1988a) the average 232 Th values are also comparable to Saskatchewan levels (Kiss et al 1988a;de Jong et al 1994) and other areas of the world (Meriwether et al 1988;Baeza et al 1995). The activity of 226 Ra also had a high variability, however, the mean was comparable to lacustrine parent materials, but higher than till parent materials of soils in Saskatchewan (de Jong et al 1994).…”

“…The determination of 226 Ra at 186 keV (Chapman and Putnam 1984). is difficult to distinguish from the 235 U peak (Meriwether et al 1988). However, a correction factor of 0.58 can be applied to compensate for the 235 U, assuming 238 U and 235 U are present in their normal concentration and if there is equilibrium in the 238 U decay series (de Jong et al 1994).…”

Distribution of some natural gamma-emitting radionuclides in the soils of the coastal areas of Nigeria

“…This standard sample contains certified concentrations of 40 K, 226 Ra and 232 Th. The lower detection limits of 95% confidence level for 10 h of counting time and 200 g of standard sample weight were found to be 578. corresponding to characteristic gamma-ray energies of different radionuclides were identified and the areas under each of these photo peaks were carefully determined using a computer program after subtracting the background and Compton Effect contribution (Meriwether et al, 1988). The net area obtained for each radionuclide by the MCA is a measure of the activity concentration in the soil samples collected, which were each counted for 10 h.…”

Statistical Analysis of Gamma-emitting Radionuclide Concentrations for Three Fields in Southern Saskatchewan, Canada

“…This baseline information is necessary in order to evaluate any change induced by man in the future (Meriwether et al 1988). In addition, these data are required to trace the movement of radionuclides from the soil reservoir into environmental and biologic systems (Osburn 1965).…”