Submitted to: ASB Bulletin
Publication Type: Abstract Only
Publication Acceptance Date: March 15, 2000
Publication Date: N/A
Technical Abstract: The capacity of wetland systems to capture sediments and build up areas of deposition has been documented. The purpose of this study was to determine the rates of sediment deposition using the Cesium-137 (Cs-137) technique in a wetland site adjacent to a small first-order stream that drains an agricultural area. The soils of the site consist of histosols buried by sediments from the agricultural area. Samples of deposited sediments in th riparian zone were collected in 5 cm increments, and the concentration of Cs-137 was used to determine the 1954 and 1964 deposition layers. Sediment deposition rates for the 1964 to 1999 period ranged from 0.3 to 0.6 cm/yr; while deposition rates for the period from 1954 to 1964 ranged from 1.0 to 2.0 cm/yr. Changes in rates of deposition between the two periods probably reflect changes in agricultural practices in the watershed. The marked decrease in the rate of mineral soil deposition relative to that of carbon in the ecosystem was reflected in high carbon enrichment within the top layer (ca. 5 cm) of the mineral sediment. Deposition rates for mineral sediments decreased with distance from the stream channel.