TRACE-ELEMENT RATIOS: A USEFUL TECHNIQUE FOR DETERMINING SUSPENDED-SEDIMENT SOURCES?

Various sediment properties have been investigated for the purpose of determining sources of suspended sediment. A remaining research need is a comprehensive assessment of the efficacy of trace-element ratios for the determination of sediment sources in different terrestrial environments. In this study, 238 unique trace-element ratios were assessed to determine which, if any, were potentially useful for sediment-source determinations in six small basins in northeast Kansas, USA. Samples of surface soils (cropland and grassland), channel banks, and reservoir bottom sediments were collected, analyzed for 23 trace elements, and compared. Of the 238 trace-element ratios assessed, only the Co/Pb ratio was substantially and consistently different between the channel banks and surface soils for all six basins. For three of four reservoirs for which data were available, sediment-source estimates provided by Co/Pb ratios were in close agreement with those using cesium-137. Additional research is required to ascertain whether or not use of the Co/Pb ratio as a tracer is widely applicable or restricted to specific environments.