2020 Undergraduate Research Day

Importance of coarse sediment for assessing metal contamination from historical mining in Big River, SE Missouri

First place poster presentation winner in GGP - Geography, Geospatial Science, and Planning!

• Hannah Eades
• Faculty Advisor: Dr. Robert T. Pavlowsky
• Poster [.pdf]

From 1864-1972 numerous lead and zinc mines were in operation in the Old Lead Belt District, Southeast Missouri. As a result, metal-rich tailings were released into nearby streams and are still stored in channel deposits today. Typically, the <2 mm size fractions are evaluated for contamination in sediment assessments. However, mine tailings often can contain particle sizes from 2-16 mm. The purpose of this study is to analyze heavy metal concentrations and mass distribution among varying size fractions of channel bar deposits in the Big River in the Old Lead Belt in St. Francois County, Missouri. A total of 14 sediment samples were collected from two sites. Each sample was separated into six different size fractions and each fraction was analyzed by X-Ray Fluorescence (XRF) spectroscopy for metals. The coarser fractions (>2mm) were crushed prior to metal analysis. Fine gravel sediments were composed of >50% tailings and contained >2,000 ppm Pb. Fine sediment is typically transported away from the source of contamination relatively quickly, while larger size fractions are heavily contaminated and remain in the channel for longer. These coarse sediments may increase long-term environmental risk as they release metals into the channel by weathering, and dissolution.