Using unsupported lead-210 measurements to investigate soil erosion and sediment delivery in a small Zambian catchment
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Date
2002
Authors
Sichingabula, Henry
Walling, D.E.
Collins, A.L.
Journal Title
Journal ISSN
Volume Title
Publisher
Elsevier
Abstract
Traditional techniques used to assemble information on rates of erosion and soil redistribution possess many important
limitations. As a result, the use of environmental radionuclides, and more particularly 137Cs measurements, has attracted
increasing attention in recent years as a means of obtaining spatially distributed information on rates of erosion and deposition.
The application of the 137Cs approach is, however, hampered in some areas of the world where 137Cs inventories are low and
the low concentrations of 137Cs found in soils and sediments cause problems for laboratory analysis. These problems will
increase as time progresses due to the radioactive decay of the existing inventory, most of which was deposited as fallout ca. 40
years ago. This contribution explores the potential for using another fallout radionuclide, namely unsupported 210Pb, as an
alternative to 137Cs, in the small (63 km2) Upper Kaleya catchment in southern Zambia where 137Cs inventories are already very
low. The approach employed with unsupported 210Pb is similar to that used for 137Cs, although the essentially constant fallout of
unsupported 210Pb through time means that the resulting estimates of erosion and soil redistribution rates reflect a longer period
of time (ca. 100 years rather than ca. 40 years). The estimates of erosion and deposition rates derived from the unsupported
210Pb measurements are used to construct typical sediment budgets for the three main land-use types in the Upper Kaleya
catchment, namely, commercial cultivation, communal cultivation and bush grazing. The results obtained from the unsupported
210Pb are compared with equivalent results based on 137Cs measurements provided by a previous investigation undertaken in
the study catchment. The two sets of results are highly consistent. The study reported confirms the viability of using
unsupported 210Pb as an alternative to 137Cs in this environment and demonstrates that conjunctive use of both radionuclides
can provide additional information on the erosional history of a study area.
Description
Journal Article
Keywords
Soil redistribution--Zambia , Environmental radionuclides--Zambia