HR: 14:40h
AN: H23J-05    [Abstracts]
TI: Determining Relative Contributions of Eroded Landscape Sediment and Bank Sediment to the Suspended Load of Streams and Wetlands Using 7Be and 210Pbxs
AU: * Wilson, C
EM: CWILSON@msa-oxford.ars.usda.gov
AF: USDA - ARS National Sedimentation Laboratory, 598 McElroy Dr., Oxford, MS 38655
AU: Matisoff, G
EM: gerald.matisoff@case.edu
AF: Department of Geological Sciences Case Western Reserve University, 10900 Euclid Ave., Cleveland, OH 44106
AU: Whiting, P
EM: peter.whiting@case.edu
AF: Department of Geological Sciences Case Western Reserve University, 10900 Euclid Ave., Cleveland, OH 44106
AU: Kuhnle, R
EM: rkuhnle@msa-oxford.ars.usda.gov
AF: USDA - ARS National Sedimentation Laboratory, 598 McElroy Dr., Oxford, MS 38655
AB: The naturally occurring radionuclides, ⁷Be and ²¹⁰Pb_xs, have been used individually as tracers of sediment particles throughout watersheds. However, use of the two radionuclides together enables eliciting information regarding the major contributors of fine sediment to the suspended load of a stream or wetland. We report on a study that uses these radionuclides to quantify the relative proportion of eroded surface soils, bank material and resuspended bed sediment in the fine suspended sediment load of the Goodwin Creek, MS, and Old Woman Creek, OH watersheds. The eroded surface soil has a unique radionuclide signature relative to the bed sediments in Old Woman Creek and the bank material along Goodwin Creek that allows for the quantification of the relative proportions of the different sediments in the sediment load. In Old Woman Creek, the different signatures are controlled by the differential decay of the two radionuclides. In Goodwin Creek, the different signatures are due to different erosion processes controlling the sediment delivery to streams, namely sheet erosion and bank collapse. The eroded surface soils will have higher activities of the ⁷Be and ²¹⁰Pb_xs than bed/bank sediments. The fine suspended sediment, which is a mixture of eroded surface soils and resuspended bed sediment or collapsed bank sediment, will have an intermediate radionuclide signature quantified in terms of the relative proportion from both sediments. A simple two-end member mixing model is used to determine the relative proportions of both sediments to the total fine sediment load.
DE: 1040 Radiogenic isotope geochemistry
DE: 1856 River channels (0483, 0744)
DE: 1862 Sediment transport (4558)
DE: 1890 Wetlands (0497)
SC: Hydrology [H]
MN: Fall Meeting 2005