Phytoremediation Properties of Sweet Potato for Soils Contaminated by Heavy Metals in South Kazakhstan

Abstract

Industrial waste in the form of abandoned mine tailings from a former lead plant in South Kazakhstan amounts to about 2 million tons, and this has led to environmental pollution with heavy metals (HMs) in Shymkent city. The concentrations of Pb, Zn, and Cd in the mine tailings were 1354.50, 262.90, and 61.08 mg/kg, respectively. The contamination of the adjacent soils with Pb, Zn, and Cd ranged from 7.76 to 551.49, from 8.25 to 245.74, and from 5.40 to 19.23 mg/kg, respectively. In this study, the phytoremediation properties of sweet potato on soils contaminated with HMs adjacent to mine tailings were investigated. The phytoremediation efficiency of sweet potato was assessed in terms of its capacity to biotransfer and bioaccumulate HMs. The concentrations of Pb, Zn, and Cd in sweet potato in the experimental fields were 28.70–45.10, 70.0–94.20, and 1.19–1.80 mg/kg, respectively. It was determined that the pollution class of the studied soils according to Igeo was high pollution (5.28–8.80), and the potential risk of HM accumulation according to the ecological risk index proposed by Hakanson was moderate pollution.