Remediation potential of native grasses in heavy metal-contaminated industrial soils

Increased concentrations of heavy metals in soil due to industrial activities have harmful effects on the environment and human health. We studied the potential of native grasses to remediate heavy metal-contaminated soils from industrial sites in Mozambique. The ICP-OES analysis revealed the presence of Al, As, Cd, Co, Cr, Mo, Ni, Pb and Zn in soils, roots and shoots of the most abundant species. The concentrations of As and Cr in the soil severely exceeded the reference values for South Africa. The grasses Cynodon dactylon, Panicum maximum and Urochloa mosambicensis showed bioaccumulation, bioconcentration and translocation factors greater than one, being considered potential for Ni and Zn phytoextraction. Eragrostis sp. showed a bioconcentration factor greater than one and a translocation factor less than one for Cr and Zn, being considered a potential phytostabiliser. Chloris virgata showed a translocation factor greater than one for nine heavy metals. All grasses showed potential for phytoremediation for one or a group of metals, and could be used in future industrial soil restoration programs. Controlled bioassays with Chloris virgata suggest its potential for remediating soils contaminated with 10 and 50 mg kg−1 Cr through phytoextraction, for 10 mg kg−1 Cd phytoextraction and 50 mg kg−1 phytostabilisation.