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The Legacy of Slag: Assessing the Environmental Impacts of Historical Iron Smelting in the Shenandoah Valley of Virginia

Session: 37th Annual Undergraduate Research Exhibition Sponsored by Sigma Gamma Epsilon (Posters)

Presenting Author:

Kylie Sheridan

Authors:

Sheridan, Kylie B.¹, Hinkle, Margaret Anne G.², Uffelman, Erich S.³

(1) Earth and Environmental Geoscience, Washington and Lee University, Lexington, Virginia, USA, (2) Earth and Environmental Geoscience, Washington and Lee University, Lexington, Virginia, USA, (3) Department of Chemistry and Biochemistry, Washington and Lee University, Lexington, Virginia, USA,

Abstract:

Slag, a silica-rich byproduct of ore smelting, was often discarded near historical iron furnaces throughout the Shenandoah Valley of Virginia. Smelting operations can contribute to soil and water contamination through metal-rich aerosols, leachate from smelter waste, and the weathering of slag. Slag heaps, in particular, are hypothesized to serve as chronic sources of metal contamination. This study employed a comparative sampling design across three historical furnace sites in the Shenandoah Valley. At each site, samples of slag, iron ore, soil, and surface water (where applicable) were collected to assess the extent of potential contamination in the area. Portable X-ray fluorescence (PXRF) reveals that while Ca, Fe, Mn, Sr, and Si are consistently present within the slag, the ratio of Ca to Fe to Mn is markedly variable, and some (but not all) samples contain detectable levels of contaminants of interest, such as Cr, Zn, Pb, Ti, and Y. Pb and Zn were also detected in certain samples of iron ore and charcoal, respectively. Scanning electron microscopy paired with energy dispersive X-ray spectroscopy (SEM-EDS) reveals distinct slag particles (10–50μm) within the topsoils. Ti tends to be relegated to small (5–20μm) discrete particles, while Fe and Mn exist as heterogeneous particles with varying sizes and densities. Pb tends to be spatially associated with Fe-rich deposits, collecting in the vesicles of small slag particles that remain in the soil. These results indicate that discarded slag may be a persistent source of contaminants to soils within the vicinity of historical iron furnaces in Virginia. To further assess the role of slag in soil contamination and the potential for contaminant leaching, sequential extractions of both slag and soil will be discussed.