Lake Macatawa Sediment Analysis
Dr. Graham Peaslee
An EPA-funded toxicological study of Lake Macatawa sediment was performed jointly by Hope College and Grand Valley State University in 2003-2004. Fourteen of the fifteen sites studied showed no macroinvertebrate toxicity and were well within EPA acceptable limits for both organics and heavy metals. However, one site showed elevated levels of lead and polycyclic aromatic hydrocarbons (PAHs) – both above the EPA probable effect limits. This initially indicated a leaking underground gasoline storage tank or just a long history of fuel spills. An extensive study in 2005-2006 by Dan Tobert and Julissa Pabon at Hope College further examined the geographical extent of the lead and PAH sediment contamination. Now six years later, the same location was revisited to determine if the PAH and lead contamination has grown, decreased, or remained the same. A modified EPA solid-liquid extraction procedure for PAHs was employed and a Gas Chromatograph/Mass Spectrometer was used to identify and quantify PAHs extracted from sediment samples. Microwave assisted acid digestions and Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) were used to determine lead and other heavy metal concentrations in the sediment samples. By comparing these results to the data collected six years earlier along with the ratio between various PAHs, it was possibly to identify the source of pollutants to be pyrogenic and not petrogenic in origin.
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