Historical Trace Metal Profile of Lake Michigan Sediment
Dr. Graham Peaslee, Hope College
Trace metals occur naturally in the environment, but elevated levels of trace metals can indicate anthropogenic influence. By analyzing lake sediment cores as a function of depth, historical anthropogenic effects in the surrounding watershed can be determined. Multiple ~50 cm cores were taken from a 65 m depth contour in southeastern Lake Michigan and were separated into centimeter segments and dried, then a subset of cores were radiodated using 210Pb and 137Cs. Three separate analytical techniques (Particle-Induced X-ray Emission Spectrometry - PIXE, Scanning Electron Microscopy- Energy Dispersive Spectrometry – SEM/EDS and Inductively-Coupled Plasma Optical Emission Spectroscopy - ICP-OES) were used to measure metals on several full cores, and a trace metal profile was assembled as a function of depth and date. The resulting metal profiles will be used to identify trace metals in the lake sediment as well as their origins. Additionally the comparison between the three different analytical techniques of PIXE, SEM-EDS and ICP-OES will give insights on the limits of detection and the acid-elution factors that are routinely used in sediment metal analyses.
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