Concentration of 210Po, 226Ra and 228Ac in non-siliceous environmental materials

The present interest concerns the possible anthropomorphic enhancement of naturally occurring radioactive material (NORM) in non-siliceous media, in particular, sediment from a river running alongside a crude oil facility and alluvial samples from the site of a now defunct minerals benefication plant. We use gamma spectrometry for 226 Ra and 228 Ac, and for 210 Po we use alpha spectrometry in association with a hydrochloric acid based radiochemical method for the extraction of 210 Po. Using 209 Po to monitor polonium extraction from samples we find the concentrations of 210 Po, 226 Ra and 228 Ac in river sediments to be in accord with typical background values (∼0.04 Bq g −1 dry), while for sub-surface soils located nearby we find the respective activity concentrations to accord with low background values (∼0.02 Bq g −1 dry). For alluvial material from the site of a defunct minerals benefications plant we have found 210 Po concentrations of ∼11 Bq g −1 (dry) in two of three samples and 30 Bq g −1 (dry) in the remaining sample; 226 Ra and 228 Ac were some several times these concentrations. In support of the methods we have adopted in present evaluations we find IAEA-300 Baltic Sea sediment reference material to contain 210 Po concentrations that are within the IAEA confidence interval for this material.