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Discipline: Ecology Environmental and Earth Sciences
Subcategory: Geosciences and Earth Sciences
Amber Hill - University of Arkansas at Little Rock
Co-Author(s): Laura Ruhl, University of Arkansas at Little Rock, Little Rock, AR
Mining of lead and zinc from 1850s to 1960s in the Tri-State Mining District has led to severe environmental degradation in SW Missouri, SE Kansas, and NE Oklahoma. Piles of mining waste remain where contaminants wash into streams and poison humans, birds, and aquatic biota. The town of Picher, OK was evacuated when children had blood lead levels >10 µg/dl. The purpose of our study was to explore the effects of mining on sediment in waterways near Picher. Additionally, we determined how far contamination in sediment extended downstream from the mining region and the chemical behavior of contaminants in sediment. We conducted experiments where sediment from the mining district was mixed with leaching solutions to simulate various environmental conditions (using rainwater and deionized water). In the first experiment, deionized water was mixed with sediment from the streams in the mining region at a 10:1 liquid to solid ratio and reacted for 24 hrs. In the second experiment, sediment was mixed with synthetic rainwater (very dilute nitric and sulfuric acid water) at a 20:1 liquid to solid ratio and reacted for 20 hrs. Trace metal analysis of the leachate was conducted with an Inductively Coupled Plasma Mass Spectrometer (ICPMS) and an ion chromatograph (IC) for cations and anions. Samples leached in deionized water had higher concentrations of Na, K, Mg, and Ca. Cations leached off sediments were at higher concentrations at the mining site and decreased in the sediment downstream. Sulfate concentration in the leachate drastically increased at the mining site likely from oxidation of sulfide minerals mined at the site. A high concentration of nitrate was leached from the sediment at one site and may be due to farmland runoff. Elevated concentrations of Ca, Mg, and SO4 were present in the sediment closest to the mining region from the host rock of mined minerals. Metals (Cd, Zn, Pb, Ni) leached from sediment were elevated in the mining region and decreased downstream. Metals in sediment result from mining waste and could dissolve in water and be ingested by wildlife and humans. The decrease in concentrations downstream is due to dilution by sediment inputs from the Neosho and Spring Rivers. Our data will reveal the extent of contamination from mining activities and identify areas that need remediation. In the future, I would like to perform different leaching experiments and to analyze the sediment at more downstream sites.
Funder Acknowledgement(s): Arkansas Science and Technology Authority, Ronald E. McNair Scholars Program, LSAMP
Faculty Advisor: Janet Lanza,
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