South-Central Section - 49th Annual Meeting (19–20 March 2015)

Paper No. 25
Presentation Time: 4:30 PM-7:00 PM

MINING INFLUENCE ON LEAD PROFILES IN HISTORICAL FLOODPLAIN DEPOSITS ALONG THE BIG RIVER


KEPPEL, Alison, Springfield, MO 65897, PAVLOWSKY, Robert, Geography, Geology and Planning, Missouri State University, Springfield, MO 15806-2429 and OWEN, Marc, Ozarks Environmental and Water Resources Institute, Missouri State University, Springfield, MO 65897, Keppel814@live.missouristate.edu

Prior to being weathered or eroded, floodplains are able to collect contaminated sediment over a long amount of time. Sedimentologic and geochemical analyses of floodplain deposits demonstrate the long-term hazard of contamination in watersheds due to historical mining. This experiment analyzes the fluctuation of lead profiles and contamination levels among 17 floodplain cores collected from a variety of elevations and ages of deposition along the Big River in southeastern Missouri. The lengths of the cores varied from 100 to 140 cm long. The Big River drains the Old Lead Belt, which from 1900 to 1972 was a global leader in the manufacturing of lead. Lead, textural, organic carbon, and cesium studies were used to conclude stratigraphic relationships. Initial results reveal that floodplain deposits formed over the past 100 years are contaminated with lead concentrations >3,000 ppm. Low terraces <1 m above historical units are usually not contaminated. Lead concentrations in recently deposited sediments (within the last 40 years) have decreased to about 1,000 ppm due to the termination of the mines.