Plant-soil-contaminant specificity affects phytoremediation of TNT in soil

The objective of this study was evaluation of different forage and conservation crops for phytoremediation of trinitrotoluene (TNT) contaminated soils. Trinitrotoluene contamination levels were 100 mg/kg of soil. A crop species screening study was conducted in the greenhouse and growth chambers on two soil types with different organic matter contents. Under high soil organic matter conditions, adsorption or covalent binding to the soil organic matter appeared to be a dominant force of removal limiting TNT availability. However, in soils with lower organic matter content, all of the plant species treatments showed a significantly higher degree of TNT transformation compared to the unplanted control. Statistically significant differences in TNT transformation were also observed among the crop species in the study. Reed canarygrass (Phalaris arundinacea L.) and switchgrass (Panicum virgatum L.) were the most effective species in enhancing TNT transformation. Our data indicated that use of plants was effective for phytoremediation of TNT contaminated soils. Based on these observations, it could be concluded that plant-soil-contaminant interactions are very specific and this specificity determines the effectiveness of a phytoremediation scheme.