Abstract
The potential of Manihot esculenta Crantz (cassava) to phytoextract Hg and Au from Hg- and Au-containing biosolids and mine tailings was successfully demonstrated for the first time. Removal of Hg by a hyperaccumulating plant species offers new options to clean up Hg-contaminated sites and at the same time harvest trace amounts of Au. Pre-rooted cassava cuttings with 5–7 nodes were grown in different combinations of biosolids-amended mine tailings to evaluate the best combination that will support optimum plant growth. The 75% biosolids – 25% mine tailings combination produced the best growth in cassava. Plant cuttings were also grown in hydroponics solutions amended with Hg and/or Au to determine root uptake of the two metals. Metals uptake was found to be greatest in the fibrous roots, accumulating up to 12.59gkg−1Hg and 18.99mgkg−1Au. Given its ease of cultivation and harvesting as well as the high accumulation of Hg and Au in its roots, cassava can be considered asa suitable candidate for Hg remediation and Au recovery from biosolids and mine tailings containing these metals.
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