Phytoremediation of contaminated soil with cobalt and chromium

• We study the potential use of five plants to extract Co and Cr out of polluted soils.
• Plant roots exhibited higher Co and Cr accumulation than shoots.
• Co accumulation ranged in the order: Sunflower > cotton > panikum > Napier grass > squash.
• Enrichment coefficient (EC) of Co and Cr was affected by soil type.
• Highest translocation factors of Co and Cr were always recorded in fine texture soil.

A phytoremediation trial was made to study the use of different plant species to extract Co and Cr out of contaminated soils. Five plant species tested in this study namely, Panikum (Panicum antidotal), Napier grass (Pennisetum purpureum), Squash (Cucurbita pepo), Cotton (Gossypium hirsutum) and Sunflower (Helianthus annuus) were grown on two different polluted soil types (Mostorud Clayey soil, irrigated with contaminated water for more than 30 years and El-Gabal EL-Asfar sandy loam soil, subjected to sewage effluent irrigation for more than 50 years) in a complete randomized block experimental design. Calculation of recovery percentage based on Co and Cr removed from the soil by whole plant after cultivation ranged between 13.8 and 43.7% and 17.0 to 41.6% of total initial Co and Cr, respectively. However, the percentage of Co and Cr removed by plant shoots from the total Co and Cr -removed by whole plant varied between 30.7 and 43.1% and 29.9 to 36.5% of the removed Co and Cr, respectively, whereas the lowest values were observed in case of Panikum for Co and Cr. As expected plant roots exhibited higher Co and Cr accumulation than in shoots by 1.32–2.25 and 1.7–2.34 folds, respectively. Sunflower roots showed the highest Co and Cr accumulation followed by Panikum and Napier grass then cotton and the least Squash roots. It is worth to mention, that roots tend to accumulate 56.9 to 69.3% and 41.2 to 70.1% of Co and Cr accumulated in plant biomass respectively.