CHARACTERIZATION OF LEAD, ZINC, AND CADMIUM IN JOPLIN, MISSOURI, USING SEQUENTIAL EXTRACTIONS

Heavy metal contamination can pose a serious threat to aquatic biota, soil microbes, plants, and through bioaccumulation, even has the potential to threaten human health. Direct exposure to contaminated sediments and soils can equally result in negative health effects. Joplin, MO, a historic mining town and part of the Tri-State Mining District, had extensive mining operation for over 150 years. Mine waste drainage and chat pile runoff distributed lead, zinc, and cadmium over the region in dangerous concentrations. The area has been remediated several times, but complete remediation could take decades due to lack of funding. Turkey Creek, adjacent to where an old lead smelter used to be, is an ample site to collect sediments for sequential extractions to assess bioavailability of heavy metals. Sediment samples were collected in portions of the creek that ran through the center of town and were sent to a commercial lab to find total metal concentration. Several samples reported high concentrations of all three metals with great variability between samples. Lead and cadmium’s acute toxicity makes samples that reported high concentrations of the two metals especially significant. However, concentration alone is not a proper proxy for toxicity. Toxicity is evaluated based on how readily available the contaminants are for biological uptake. In order to assess this, sequential extractions are performed to know what amount of the heavy metals are in bioavailable fractions of sediment. These amounts have been compared to the total metal concentration for each respective sample to quantify typical ratios of bioavailable fractions to total concentrations of these metals. Magnetic susceptibility, size fractionation, and loss on ignition methods will be employed to further characterize our sediment samples. This study will provide the first data on metal fractionation in the Joplin area. Additionally, GIS software is used to determine what areas may have greater risk to biota due to higher quantities of the metals in bioavailable fractions of sediment.