The potential for gamma-emitting radionuclides to contribute to an understanding of erosion processes in Southern Africa

Several early studies have pointed to the fact that 137Cs could be detected in soils and sediments in Southern Africa (e.g. Kulander & Stromquist, 1989; Owens & Walling, 1996). Despite the relatively low southern hemisphere fallout of this predominantly nuclear weapons-testing derived isotope, few studies have continued to explore the potential for 137Cs and other gamma-emitting radionuclides to be used for understanding erosion processes and erosion history. For the last 9 years, we have been evaluating the potential for 137Cs and 210Pb to be used for constructing chronologies in a range of depositional environments including dryland and permanently flooded reservoirs and hillslope fan and floodout deposits. We have explored the potential for short-lived cosmogenic and other long-lived primordial nuclides to act as sediment fingerprints to aid in reconstructing changes in sediment sources in the same range of depositional environments. This paper will review the evidence to date and evaluate the potential, and limitations, of a range of gamma-emitting radionuclides to be used for understanding and managing erosion and land degradation problems in Southern Africa