Uptake of polycyclic aromatic hydrocarbons by Trifolium pretense L. from water in the presence of a nonionic surfactant

A greenhouse study examined plant uptake of phenanthrene and pyrene, as representatives of polycyclic aromatic hydrocarbons (PAHs), from an aqueous solution containing a nonionic surfactant Tween 80. The uptake was conducted with 1.0 mg l(-1) phenanthrene and 0.12 mg l(-1) pyrene under a wide range of Tween 80 concentrations (0-105.6 mg l(-1)). Tween 80 at the test concentrations did not show any apparent phytotoxity toward the growth of red clover (Trifolium pretense L.). At concentrations generally lower than 13.2 mg l(-1), Tween 80 enhanced the plant uptake based on the concentrations and PCFs (plant concentration factors) of these two PAHs. When present at higher concentrations, Tween 80 inhibited the uptake of both PAH compounds by the tested plant. The maximal plant uptake was observed at 6.6 mg l(-1) Tween 80, in which PAH concentrations and PCFs were 18-115% higher than those in Tween 80-free controls. The total mass removal (off-take) of phenanthrene and pyrene by root or shoot increased initially and decreased thereafter with the increase in Tween 80 concentrations. Although shoot biomass was evidently larger than root, the off-take was much higher in root than shoot because of the larger root concentrations of these chemicals. Results from this study show promises for the potential efficacy of enhanced phytoremediation in PAH contaminated sites using surfactant amendment.