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The application of uranium series disequilibrium concepts to sediment yield determination
Author(s) -
Plater A. J.,
Dugdale R. E.,
Ivanovich M.
Publication year - 1988
Publication title -
earth surface processes and landforms
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.294
H-Index - 127
eISSN - 1096-9837
pISSN - 0197-9337
DOI - 10.1002/esp.3290130207
Subject(s) - uranium , protactinium , weathering , sediment , disequilibrium , geology , thorium , fluvial , hydrology (agriculture) , drainage basin , isotopes of uranium , yield (engineering) , geochemistry , mineralogy , environmental science , soil science , geomorphology , structural basin , geotechnical engineering , medicine , materials science , cartography , ophthalmology , geography , metallurgy
The determination of uranium series disequilibria in fluvial environments is proposed as a method of calculating catchment mass balances. The technique is based on two main principles. Firstly, 234 U is more mobile than 238 U, especially during the early stages of weathering. Secondly, uranium is far more mobile than either thorium or protactinium. Consequently, teaching during weathering results in the loss of the uranium found in the fresh rock, leaving the two immobile daughters behind. The ratio of uranium carried by sediment to that dissolved, U S / U W can, therefore, be determined from river water and sediment isotopic activity ratios. Fluxes of uranium can then be calculated from average concentrations in the water and the associated sediment, from which a sediment yield can be inferred. The Witham catchment in Lincolnshire has been used to test the proposed method. A U S / U W ratio of between 5 and 7 is determined and a sediment yield of 2.51 ± 2.12 tonnes yr −1 km −2 is proposed. Although some problems concerning environmental chemistry have arisen, the validity of the approach is confirmed by the close correspondence between the results obtained and those inferred by earlier workers using more conventional methods.