Gamma-emitting radionuclides and metallic elements in urban dusts and sediments, Coventry, UK: implications of dosages for dispersal and disposal

Gully pot sediments and pavement and road gutter dusts have been collected from the city of Coventry in the West Midlands, UK. These samples have been subjected to metallic element analysis and the activity of a number of gamma-emitting radionuclides have been measured in order to assess whether they exceed published trigger or action levels, and whether their disposal or dispersal may have implications for receiving landfills and/or water courses. Results indicate above-background levels of metallic elements in dusts and sediments with Cu and Zn exceeding ICRCL action levels in some cases. The highest activities of some radionuclides are found in road gutter and street dusts and the lowest activities are found in gully pot sediments. Road dusts are more likely to be recirculated into the ambient air by passing traffic and could potentially pose a risk to pedestrians. The effective dose rates calculated for these dusts and sediments indicate that some samples approach and even exceed the 1 mSv y(-1) limit to members of the public recommended by ICRP (1991). Some individual nuclides exceed their clearance levels laid down in the revised basic safety standards of the 19936 Radioactive Substances Act, 1993 (DoETR, 1999), by as much as 2.5 times. This is especially true of Pb-210(un) and Be-7, two fallout nuclides, and also of K-40.