Abstract

The affinity of bomb-derived ¹³⁷Cs and naturally-occurring fallout ²¹⁰Pb for soil and sediment particles makes them valuable sediment tracers for investigating water-induced soil redistribution on cultivated land. Although ¹³⁷Cs measurements on soil cores have been successfully used to study soil redistribution rates in many areas of the world, the applicability of the approach may be limited in areas where significant amounts of Chernobyl-derived fallout were received or where bomb-derived ¹³⁷Cs fallout inventories are low. The similar behaviour of fallout ²¹⁰Pb in soils makes it an alternative to ¹³⁷Cs for soil erosion investigations in areas where ¹³⁷Cs measurements prove to be inapplicable. Furthermore, the combined use of the two radionuclides may provide additional information on the erosional history of an area. There have, however, been few attempts to validate erosion rates estimated from ²¹⁰Pb measurements and, more particularly, the various assumptions associated with the available conversion models, or to compare the erosional behaviour of the two radionuclides. In this paper, relationships between ¹³⁷Cs and ²¹⁰Pb loss and measured soil loss from nine experimental plots located in Southern Italy were investigated over a three year period. The results confirm the general validity of the assumptions associated with existing mass balance models used for deriving estimates of soil redistribution rates from ¹³⁷Cs and ²¹⁰Pb measurements, and provide important insights into some differences between the erosional behaviour of the two radionuclides.

Keywords: soil erosion rates, ²¹⁰Pb, ¹³⁷Cs, fallout radionuclides, sediment yield, Italy