Recent advances in the use of environmental radionuclides in soil erosion investigations

Full text: Although recent concern for the global environment has tended to highlight the threats caused by global warming and climate change, soil erosion and associated land degradation remain serious problems. There is an important need for reliable information to both quantify the problem and underpin the development of effective soil conservation strategies. Traditional approaches to documenting erosion rates are capable of meeting some of these needs, but they also possess a number of important limitations. The use of environmental radionuclides, and more particularly 137Cs has attracted increasing interest as a means of documenting rates and patterns of soil loss. The approach was first employed in the early 1970s, and since that time it has been refined and its application has become increasingly standardised. This paper reviews what are seen to be a number of important developments of the 137Cs technique in recent years, related to this refinement and standardisation. These developments have been coupled with an expansion in the application of the technique beyond the basic quantification of rates and patterns of soil loss. Two examples of new applications, involving the elucidation of erosion/crop productivity relationships and the validation and calibration of distributed soil erosion and sediment delivery models, are described. In addition, recent years have also seen an extension of the 137Cs technique to embrace the use of other radionuclides, both as an alternative and a complement to 137Cs. Recent developments in the use of excess 210Pb and 7Be in soil erosion investigations, to document both longer and shorter timescales than those possible with 137Cs are discussed. (author)