Radionuclides and toxic elements transfer from the Princess Dump to the surrounding vegetation in Roodepoort South Africa : potential radiological and toxicological impact on humans

Abstract

South Africa is a mining country, and one of the leading gold mining countries in the world. Mining activities tend to bring other minerals and elements to the surface in addition to the desired mineral. In gold mining, one of these metals is Uranium which is both toxic and radioactive. Uranium decay to form other radioactive daughters and the radioactivity may be high enough to cause some health concerns to the public residing next to where this waste material is being dumped. In this study, soil and vegetation samples were collected from the Princess Gold mine dump in Roodepoort, South Africa, to evaluate the transfer of radionuclides and toxic elements from the mine dump to the vegetation at and around the dump. The samples were analyzed and the data was then used to estimate the potential radiological and toxicological impact of the mine dump to the community located next to it. The concentration of all essential elements in plant leaves of three species, A. pycnatha, E. globu/us and Hyparrhenia spp. were within the normal levels found in the species. The concentrations of toxic elements were slightly elevated, especially that of uranium and lead. There is a transfer of radionuclides and toxic elements from the mine dump to the plants and the transfer rates vary from species to species and from one sampling point to the other. The potential toxicological impact of both essential and toxic elements was estimated using default transfer parameters from the IAEA and the essential elements were within acceptable limits in leafy vegetables grown in home gardens while the concentration of uranium and lead were high, 1.88 and 0.144 µg/g, respectively. The MTL in food for the two metals are 0.3 and 0.005 [!g/g respectively. The potential exposure of the population from ingestion of meat and milk from cattle feeding on pasture contaminated by radionuclides from the mine dump, as well as the consumption of sheep feeding in the same pasture was estimated. The study showed that consumption of milk and meat from such cattle will lead to a dose of 3.6 ± 2.0 mSv/a and 2.6 ± 1.6 mSv/a respectively. The dose received from consumption of leafy vegetables grown in contaminated soil was insignificant for people above the age of 1 year and 278 µSv/a for those below 1 year.