Year Established: 2013 Start Date: 2013-03-01 End Date: 2014-05-01
Total Federal Funds: $39,780 Total Non-Federal Funds: $80,174
Principal Investigators: Xiaobo Chao, James Cizdziel, AKM Hossain, Kristine Willett
Abstract: The Yazoo River Basin is the largest basin in Mississippi. Four large flood control reservoirs: Arkabutla Lake, Sardis Lake, Enid Lake and Grenada Lake, are located in this region, providing significant natural and recreational resources. The soils in this region are highly erodible, resulting in a large amount of sediment discharged into the water bodies. Sediments are normally associated with many pollutants and greatly affect water quality and aquatic lives. Mercury concentrations in water, sediment and fish in Enid Lake are relatively high, and a fish consumption advisory was issued by Mississippi Department of Environmental Quality (MDEQ) in 1995. In turn, the recreation values of this lake were reduced. More recently, to reduce the mercury levels, Total Daily Maximum Loads (TMDLs) were established for the lake watershed. However, the mercury loads due to atmospheric deposition and nonpoint sources were not included in the TMDL computation, mercury concentration data was quite old, and the processes of fate and transport of mercury in water bodies were not considered. Our proposed research will bring together a team of University of Mississippi scientists that with their expertise in analytical chemistry, hydraulic modeling and risk assessment will be able to update stake-holders as to the transport, fate and risks of mercury in Enid Lake. It is anticipated results from this study will be directly applicable to other large lake systems in Mississippi. Critical data needs that will be filled during the course of this proposal include: (1) Measurements of seasonal flow and suspended sediment concentrations; (2) mercury concentrations in lake water and sediment, and (3) muscle mercury concentrations in three species of fish (cat fish, largemouth bass and white crappie). The field data will provide us the unique opportunity to (1) Validate suspended sediment concentration estimated using remote sensing technology; (2) Calibrate and validate numerical models of flow, sediment and mercury in lake, and (3) Update environmental and fish consumption risk assessments. Our team is particularly well suited to do this project because National Center for Computational Hydroscience and Engineering (NCCHE) has developed a new remote sensing based technique using NASA's satellite imagery (Landsat Thematic Mapper) to estimate and map surface suspended sediment concentrations in large lakes and rivers. In addition, a numerical model will be developed based on CCHE3D, a three-dimensional free surface hydrodynamic, sediment and water quality model developed at the NCCHE to simulate the flow, sediment and mercury distributions in the lake. Total mercury in water and sediment will be simulated, and the major processes, including advection, diffusion, adsorption/desorption, bed release, atmosphere deposition, settling, etc., will be considered in the proposed model. This model will be calibrated and validated using field measurements and remote sensing data. The measured and computed mercury concentrations in water, sediment, and fish will be used for a potential risk assessment. This research is expected to improve our understanding of the transport mechanism of mercury by water and sediments in large lakes of Mississippi and provide more timely data on associated potential risks. The results of this proposed research can be used by decision makers to evaluate TMDLs for the watershed feeding into the lake.