Spatial variability of sediment size and lead concentrations on a mining-contaminated river bar in Big River, southeast Missouri

Authors: Madeline Behlke-Entwisle*, , Robert Pavlowsky , Missouri State University, Kelly Rose, Missouri State University, Marc Owen, Missouri State University
Topics: Geomorphology, Environment
Keywords: Lead contamination, sediment contamination, mining
Session Type: Poster
Day: 4/12/2018
Start / End Time: 8:00 AM / 9:40 AM
Room: Napoleon Foyer/Common St. Corridor, Sheraton, 3rd Floor
Presentation File: No File Uploaded

Assessment of sediment contamination and associated environmental risk requires an understanding of the spatial variability of toxicity within sedimentary environments. The purpose of this study is to examine the spatial distribution of lead (Pb) contamination across the surface of a vegetated bar (110 m long x 30 m wide) in the Big River channel at St. Francois State Park near Bonne Terre, Missouri. Underground mining for Pb began in the area in 1864 with globally important deep-shaft mining occurring in the Old Lead Belt mining district from approximately 1900 to 1972. Large volumes of mine tailings were released to the Big River, resulting in ecologically toxic Pb concentrations in channel sediment for almost 171 kilometers to its mouth on the Meramec River south of St. Louis, Missouri. Seventy-five surface (0-5 cm) samples of bar sediment were collected along 15 cross-channel transects, GPS-located, and analyzed for metals using X-ray fluorescence (XRF) and sieved grain-size. In addition, bar morphology units were mapped and characterized using pebble counts. Metal levels in the <2 mm sediment fraction were high with Pb concentrations averaging 1113 ppm, ranging from 362 to 2719 ppm, above the probable effects concentration (PEC) of 128 ppm Pb. Preliminary analyses show that higher concentrations tend to occur at the bar head and longitudinally down the center of the bar. Geographic patterns of sediment size and Pb concentrations will be analyzed at higher resolution to better understand the relationships among bar morphology, vegetation, and Pb contamination.

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