27 Environmental Geochemistry and Health (Posters)

We invite presentations on the environmental fate of contaminants and their impact on human and environmental health. Transdisciplinary contributions are encouraged, especially those examining the rock-soil-water-human nexus at all scales with strong public outreach or societal impact.

Sunday, 19 October 2025
8:00 AM - 5:30 PM
HBGCC, Hall 1

Mercury and other metal pollution in road sediment in Gary, Indiana: Providing contexts for community environmental geohealth

Paper number: 27-10
Program: Technical Sessions
Time: 8:00 AM – 8:00 AM

Authors

Abstract

Road sediment is an environmental medium that can be utilized to investigate pollution in a given area and to quantify the concentration and distribution of pollutants. Although previously studied, open questions regarding Hg, Cd, and other metals in Gary road sediment exist. This study focused on high-resolution inductively coupled mass spectrometry (HR-ICP-MS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM)  techniques to investigate Hg, Cd, and other metals in Gary road sediment. Powder X-ray diffraction (PXRD) data shows that dominant minerals include quartz, calcite, and dolomite, all of which are geogenic. Analysis of road sediment collected in 2016 via HR-ICP-MS shows Hg concentrations vary from 1.61 to 54.56 ppm. Additional HR-ICP-MS analysis of road sediment samples collected in 2025 show Hg concentrations vary from below detection limit to 2.55 ppm, and Cd concentrations from 0.11 to 4.06 ppm. Hg concentrations are approximately 2 to 4 orders of magnitude larger than those observed in road sediment from nearby Michigan City, Indiana (1.5 ppb to 28.5 ppb). The 2025 road sediment samples also have V (31.35 to 418.21 ppm), and Cr (60.57 to 674.55 ppm) concentrations above UCC and show a positive correlation (r2 =0.90). SEM analysis identifies anthropogenic spherules with diameters from 0.12 µm to 928 µm (the largest of which appears to be an outlier), with an average of 1.92 µm. SEM data also provides examples of corroded steel fragments with Cr and Zn content. Transmission electron microscopy (TEM) investigations indicate the prevalence of technogenic spherules, with diameters varying from 0.04 µm to 0.83 µm. Technogenic spherules, overall, have the potential to remobilize and resuspend, leading to possible exposures for the human population and broader environment. No discrete phases of Hg were found via SEM or TEM, and therefore, it is likely that Hg occurs in elemental or organometallic form(s) and is interpreted as pollution likely from coal burning and steel manufacturing. Hg is a historically understudied pollutant in road sediment, and these are the first detailed Hg findings for road sediment in Gary, Indiana. This investigation further illustrates the utility of road sediment for community environmental geohealth studies.

Geological Society of America Abstracts with Programs. Vol. 57, No. 6

doi: 10.1130/abs/2025AM-413033

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