44 Environmental Geoscience (Posters)

Wednesday, 11 March 2026
9:00 AM - 12:00 PM
RCC, Lower Level Hall

Investigation of Pb, Cu, and Zn concentrations as determined by X-ray fluorescence spectroscopy in road sediment in Michigan City, IN: New insights into pollution near Lake Michigan

Paper number: 44-3
Program: Technical Sessions
Time: 9:00 AM – 9:00 AM

Authors

Abstract

Coal-derived pollution and general metal pollution are well-recognized issues in the Midwestern US linked to a long legacy of extensive industrial activity. Michigan City is located in northern Indiana and is typical of many small cities in the Midwest in scale and coal-fired power plant use. It is located in an environmentally sensitive setting along Lake Michigan. Road sediment is increasingly used to assess coal and metal pollution in communities throughout the US. Previous investigations of road sediment focused on Hg concentrations, finding elevated levels of Hg likely attributed to the NIPSCO coal-fired power plant. The study also found technogenic spherules consistent with coal and other industrial activity in the road sediment. The concentration of other toxic metals in Michigan City’s road sediment remains unknown. Samples of road sediment (n=42) from Michigan City were investigated in the present study using X-ray fluorescence spectroscopy to determine concentrations of metals. The XRF data suggest that low to moderate levels of metal pollution are present for zinc (Zn), lead (Pb), and copper (Cu). Concentrations of these pollutants are variable: Pb (10 to 95 ppm, Avg. = 28 ppm); Cu (15 to 828 ppm, Avg. 51 ppm); Zn (15 to 484 ppm, Avg. = 155 ppm). Average metal concentration to upper continental crust (UCC) value ratios are 1.65 for Pb, 1.82 for Cu, and 2.31 for Zn. Only weak positive correlations are observed between Pb, Cu, and Zn concentrations in this sample set, unlike in many other road sediment settings, where more pronounced correlations are found (e.g., Las Vegas, NV and Hamilton, OH). Previous work has also identified discrete Pb-rich and Cu-Zn bearing particles in road sediment samples, and the uneven mixing of these partially explains the lack of correlation. Pb, Cu, and Zn pollution is interpreted to be from industry, traffic, and coal combustion. This investigation provides new data for a growing research effort to understand the variability of metal pollutants captured in road sediment. It places local constraints on the potential input of Pb, Cu, and Zn into local aquatic systems in Northwestern Indiana, including Lake Michigan.

Geological Society of America Abstracts with Programs. Vol. 58, No. 1

doi: 10.1130/abs/2026SE-411612

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