The Biochar-Enhanced Phytoextraction of Heavy-Metal-Polluted Tropical Soils by Thorny Amaranth (Amaranthus spinosus)

Abstract

It was suggested that some tropical plants were able to lower toxic metal concentrations in soils. The phytoextraction potential of thorny amaranth (Amaranthus spinosus) in tropical soils treated with biochar was investigated. Soil samples high in heavy metals were taken from a 22-years old experimental field treated with industrial waste at 0-60 Mg ha-1. Soil samples were evaluated with thorny amaranth for 4 weeks. Planting was also conducted in 0-10 Mg ha-1-biochar-treated soil samples. The soil heavy metals increased with the industrial waste levels but were decreased by plant and/or biochar treatments. The plant growth as well as root and shoot dry-weights were lowered by the high soil Cu and Zn but attenuated in the presence of biochar. The accumulation of Cu and Zn in plant roots and shoots and their translocation factors were also lowered by soil Cu and Zn but were increased by biochar. The accumulation of Cu and Zn were higher in plant shoots than those in roots in good correlations with their concentrations in soils. The thorny amaranth was a good Cu and Zn phytoextractor in heavy-metal-polluted tropical soils and performed better in the presence of biochar.