Lead isotope ratios in bone ash of blesbok (Damaliscus pygargus phillipsi): A means of screening for the accumulation of contaminants from uraniferous rocks

Abstract

This study was done to determine whether blesbok (Damaliscus pygargus phillipsi) from the Krugersdorp Game Reserve (KGR) in Gauteng Province, South Africa have higher concentrations of ²³⁸U and higher ²⁰⁶Pb/²⁰⁴Pb and ²⁰⁷Pb/²⁰⁴Pb ratios in their bone ash than blesbok from a nearby control reserve that is not exposed to mine water and has no outcrops of uraniferous rocks. Eight blesbok females from the KGR and seven from the control site, all killed with a brain shot, were used. A Thermo X-series 2 quadrupole ICPMS was used to measure the concentrations of ²³⁸U and lead and a Nu Instruments NuPlasma HR MC-ICP-MS to measure the lead isotope ratios in the tibial ash from each animal. KGR blesbok had higher mean concentrations of ²³⁸U (P = 0.02) and ratios of ²⁰⁶Pb/²⁰⁴Pb and ²⁰⁷Pb/²⁰⁴Pb (P < 0.00001) than the control blesbok. The probability of rejecting the false null hypothesis of no difference in the ²⁰⁶Pb/²⁰⁴Pb or ²⁰⁷Pb/²⁰⁴Pb ratios between KGR and control reserve animals (the power of the test) was 0.999. The blesbok from the KGR accumulated contaminants from an uraniferous environment. The ²⁰⁶Pb/²⁰⁴Pb and ²⁰⁷Pb/²⁰⁴Pb ratios in tibial ash proved effective in confirming accumulation of contaminants from uraniferous rocks.

Keywords:

• Uranium
• lead isotope
• bone
• ash
• blesbok
• damaliscus pygargus phillipsi

Acknowledgments

The authors acknowledge the Mogale City Local Municipality who availed facilities at the Krugersdorp Game Reserve for the collection of specimens and provided logistic support throughout the research. We also acknowledge the Rhino and Lion Nature Reserve for allowing us to collect specimens to serve as controls. We further acknowledge the marksman from the South African Hunters and Game Conservation Association who professionally assisted with specimen off-take. We acknowledge Dr. Petrus le Roux and Dr. Christel Tinguely of the Department of Geological Sciences, University of Cape Town for the determination of the concentrations of ²³⁸U, lead and the lead isotope ratios in the bone ash. Mr. P. J. Hobbs of the Council for Scientific and Industrial Research kindly provided a map which the authors adapted and used as Figure 1.

Funding

The authors acknowledge the National Research Foundation of South Africa for partly funding the study.