2009 Annual Report 1a.Objectives (from AD-416) Assess sedimentation issues in reservoirs in the Mid-South and elsewhere through the delineation and characterization of sediment deposits. Some emphasis will be placed on dating ancient sediments in older lakes, such as oxbow lakes. Also, the transfer of compounds from agricultural activities to reservoirs will be examined. 1b.Approach (from AD-416) Cores of reservoir sediments will be collected. Laboratory analyses will be performed to identify sedimentation rates, chemical characteristics, and textural characteristics of stored sediments. Where needed, high-resolution acoustic profiling will be used to enhance the quality of data collected from reservoirs. Local and regional trends in reservoir sedimentation will be defined where possible. 3.Progress Report Sediments stored in lakes represent a valuable archive that can be used to recover information on the erosion history on watersheds. The fate of chemicals derived from pesticides used in watersheds deposited with sediments and stored within reservoirs is not completely known. One focus area for reservoir sedimentation research has been attempting to increase the current level of knowledge on the fate of these chemicals. Studies are in progress to determine if sediment cores from open-water and surrounding wetlands preserve a historic record of the ability of riparian wetlands to permanently sequester non-point source contaminants. Sediment cores have been collected from oxbow lakes and bordering wetlands in two lake-wetland systems in the Mississippi Delta region (Sky Lake and Hampton Lake). Rates of sediment accumulation were determined using 210Pb and 137Cs to establish dates of deposition for depths of interest. Element analyses have been performed on 1-cm intervals covering more than a century of sediment accumulation. Elevated concentrations of elements such as As, Co, Cu, Ni and Pb have been found in sediments deposited 70 or more years ago in open-water sediments, but not in adjacent wetland cores. If these elements were initially scavenged from water entering the wetlands, the sequestration was temporary. If the elevated concentrations in the open water sediments are from anthropogenic sources, they are likely adsorbed to solid surfaces or associated with organic material. To test this possibility, sediment samples from zones with high and with background element concentrations have been subjected to sequential extractions using a variety of solutions designed to separate elements associated with different sediment fractions. Concentrations measured from these experiments are currently under evaluation. This work was presented at the 2008 annual Geological Society of America meeting in Houston, TX, and at the 2008 annual Mississippi Water Resources conference in Jackson, MS. Monitoring activities were performed through at least quarterly calls with the cooperators. This work contributes to NP211: Problem Area 4--Integrated Soil Erosion and Sedimentation Technologies.