Chemical characterization of heavy-metal contaminated soil in southeast Kansas

Abstract

A tri-state mining region, including parts of Missouri, Oklahoma, and Kansas, was the site of intense lead and zinc mining and smelting activity until the 1950's. A study was initiated to characterize the heavy-metal contamination of soils in this area. Water-soluble, an index of plantavailable, total, and sequentially extractable metals; organic, and total carbon; and saturated paste pH were determined for mine tailings and soil samples. Mine tailings contained 81 to 89 mg kg−1 total Cd, 1 150 to 1 370 mg kg−1 total Pb, and 11 400 to 13 700 mg kg−1 total Zn. Total concentrations in soil samples were 15 to 86 mg kg−1 Cd, 35 to 1 620 mg kg−1 Pb, and 99 to 18 500 mg kg−1 Zn; and, DTPA extractable concentrations ranged from 0.6 to 10 mg kg−1 Cd, 7.8 to 68 mg kg−1 Pb, and 33 to 715 mg kg−1 Zn. Samples were sequentially extracted to approximate the proportions of the metals in the sulfide, carbonate, organic, sorbed, and exchangeable fractions. For Zn and Cd, concentrations were greatest in the sulfide fraction followed by carbonate, organic, sorbed, and exchangeable. Lead followed the same pattern, except higher concentrations were observed in the sorbed than the organic fractions.