Geochemical mapping of Pb- and Zn-contaminated streambed sediments in southwest Missouri, USA
Purpose: Four locations in southwest Missouri, USA, purportedly contaminated with mining wastes, Joplin, Aurora, Springfield, and the James River, were investigated for lead and zinc content using spatial distribution and statistical analyses. Lead (Pb) and zinc (Zn) concentrations in streambed sediment samples were compared spatially against a regional background concentration map to determine both the contamination level and dispersion of these metals.
Materials and methods: Streambed sediment data were retrieved from USGS Geochemical Databases (N = 1,019) with which sediment geochemical maps were constructed. Publically available metal content data for each of four historic mining sites were also retrieved from separate studies. The Pb and Zn concentrations at each of the historic mining sites were compared against background concentrations using geochemical mapping interpolation (inverse distance weighted (IDW) method), box plot diagrams, Pearson correlation, and rationing.
Results and discussion: Pb and Zn were present in a large range of concentrations in the regional background concentration data (concentrations up to 3,460 mg kg-1 Pb and 14,027 mg kg-1 Zn) with a median of 22.0 and 53.0 mg kg-1, respectively. Concentrations of Pb and Zn in Joplin and Aurora were significantly higher, while the concentrations of Pb and Zn at the two sites near Springfield were closer to regional background concentrations. The metal content maps and association among metals both indicate that mining wastes are the main source of contamination.
Conclusions: Even though mining ceased over 40 years ago and remediation has been applied to the area, some streambed sediments in the area contain potentially toxic concentrations of Pb and Zn, especially around the cities of Joplin and Aurora. The background geochemical maps of the area were instrumental for identifying the sources and extent of these metals in sediments in this area.
Geography, Geology, and Planning
lead, metal contamination, Missouri, stream sediment, Tri-State Mining District, zinc
Gutiérrez, Mélida, Shuo-Sheng Wu, and Jessica L. Peebles. "Geochemical mapping of Pb-and Zn-contaminated streambed sediments in southwest Missouri, USA." Journal of soils and sediments 15, no. 1 (2015): 189-197.
Journal of soils and sediments