Comparative Assessment of Mono-Cropping and Co-Cropping of Three Phytoremediation halophytes in Mitigating Polymetallic Mining Pollution in M’Dhilla Area

Abstract

Soil pollution emerging from mining activities is a worldwide environmental concern. Finding biological solutions to this problem is of paramount importance in reducing metal toxicity and limiting its spread. In this context, halophytes-assisted phytoremediation has been widely considered as a promising alternative to remediate both salt-affected and heavy metal-contaminated soils. In this study, three halophytes Sesuvium portulacastrum, Carpobrotus edulis and Mesembryanthemum cordifolium have been evaluated for their metal phytoextraction potential performed on a mining soil collected from the mining phosphate basin of Gafsa. A 7-month greenhouse pot experiment was conducted under two cultivation systems: mono-cropping and co-cropping. The effect of co-cropping on the phytoextraction efficiency was highlighted and the associated phytoremediation indexes were assessed. Results showed that the crude collected soil revealed strong Cd and Sr contamination, moderate Cr and Ni levels, and low Cu and Zn concentrations. Compared to mono-cropping, co-cropping enhanced Cd uptake efficiency achieving a ~ 40% reduction in initial soil Cd level. For both cropping systems, the extraction efficiencies of the other metals were less than 1% of their initial values. Fe and Mn levels remained nearly unchanged across cultivation systems. The decline in pollution indices and metal concentrations confirmed the phytoremediation potential of the investigated species in co-cropping. This approach shows promise for in-situ remediation of mining-affected soils.