Heavy Metal Uptake from Abandoned Mine Waste Materials Amended with Biosolids.

The abandoned Pb and Zn mines in the Tri-State Mining District of Kansas, Missouri, and Oklahoma have left a legacy of environmental contamination.  In 2006, researchers at Kansas State University added amendments (compost, lime, bentonite) to two sites at Galena, KS, part of the District, to see if they would change microbial properties.  One site, called Site A, was 10 km outside of Galena, and the other site, Site B, was in Galena.  Biosolids have never been applied to the mine waste materials to see if they would reduce availability of heavy metals.  Therefore, in 2014 we sampled the plots established in 2006 and set up a greenhouse study with sudex [Sorghum bicolor (L.) Moench x S. Sudanese (P.) Staph.] to determine the effect of biosolids.  Plants grew with and without biosolids, and roots, shoots, and grain were harvested 110 days after planting.  Because differences in concentrations of Pb, Zn, and Cd due to the original treatments established in 2006 were not evident, concentrations were averaged together.  Here we report root and grain concentration only.  Concentrations (mean + standard error) of Pb in the roots at Site A with and without biosolids were 1196.8+77.1 and 1504.7+112.3 mg/kg, respectively; for Site B they were 585.0+22.7 and 715.1+25.5 mg/kg, respectively.  Concentrations of Zn in the roots at Site A with and without biosolids were 7771.7+692.4 and 5174.8+448.7 mg/kg, respectively; for Site B they were 3230.7+404.6 and 5045.6+774.7 mg/kg, respectively.  Concentrations of Cd in the roots at Site A with and without biosolids were 42.6+3.4 and 56.4+3.4 mg/kg, respectively; for Site B they were 18.7+1.8 and 42.0+8.6 mg/kg, respectively.  Only the plants grown with biosolids produced grain.  Concentrations (mean + SE) of Pb in grain at Site A and Site B were 3.8+1.0 and 1.8+0.3, respectively.  Concentrations of Zn in grain at Site A and Site B were 116.4+8.4 and 57.0+2.6, respectively.  Concentrations of Cd in grain at Site A and Site B were 2.2+0.1 and 0.7+0.2, respectively.  The results showed that biosolids reduced the uptake of Pb, Zn, and Cd from the mine waste materials.