PIXE Spectroscopy for Lake Macatawa Watershed Sediment Characterization
Dr. Graham Peaslee, Hope College
Dr. Paul DeYoung, Hope College
This research project focuses on the non-point source sedimentation and hypereutrophication problems plaguing Lake Macatawa. Excess nutrients, such as phosphates and the sediment particles to which they are attached, flow into the lake from the surrounding watershed increasing both the lake’s turbidity and its nutrient imbalance. The goal of this study is to identify sediment signatures representative of unique locations within the watershed by analyzing the elemental composition of the sediment that is present in the Lake Macatawa watershed. This analysis would aid in the determination of sediment provenance and effectively allow for the modeling of this non-point source pollution as multiple point sources of the sediments and their adsorbed nutrients. This is accomplished partly by characterizing dried, homogenized sediment samples by Particle Induced X-Ray Emission (PIXE) spectrometry. A method has been developed to measure eighteen different elemental concentrations in sediment samples collected from a variety of sampling sites. These concentrations are compared site to site and rain event to rain event to find trends in the changes of concentrations of the metals that will help characterize the sediment source. When the sediment elemental composition is compared with other analytical methods such as phosphate analysis, the ability to discriminate between different locations is enhanced.
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