Phytoremediation for co-contaminated soils of benzo[a]pyrene (B[a]P) and heavy metals using ornamental plant Tagetes patula.

Pot-culture experiments were conducted to investigate the single effect of benzo[a]pyrene (B[a]P) and the joint effect of metal-B[a]P on the growth of Tagetes patula and its uptake, accumulation and dissipation of heavy metals and B[a]P. Results showed that the low concentration of B[a]P (≤10 mg kg(-1)) could facilitate plant growth and resulted in an increase in biomass at the rate of 10.0-49.7% relative to the control. There were significantly positive correlations between the concentrations of B[a]P accumulated in tissues of the plants and soil B[a]P (P<0.001). However, the occurrence of Cd, Cu and Pb had inhibitive effects on plant growth and B[a]P uptake and accumulation on the whole. T. patula still exhibited a steady feature of Cd-hyperaccumulator under combined contaminated soils. By contrast, the effectiveness of Cu and Pb absorption in the plants was very weak. Plant-promoted biodegradation of B[a]P was the dominant contribution, 79.2-92.4% and 78.2-92.9% of dissipation of B[a]P came from plant-biodegradation under single B[a]P and metal-B[a]P contaminated soils, respectively. Therefore, T. patula might be useful for phytoremediation of B[a]P and B[a]P-Cd contaminated sites.