Phytoremediation has been used as an emerging technology for remediation of soil contamination with polycyclic aromatic hydrocarbons(PAHs),ubiquitous persistent environmental pollutants derived from natural and anthropogenic processes,in the last decade.In this study,a pot experiment was conducted to investigate the potential of phytoremediation of pyrene from spiked soils planted with white clover(Trifolium repens)in the greenhouse with a series of pyrene concentrations ranging from 4.22 to 365.38 mg kg-1.The results showed that growth of white clover on pyrenecontaminated soils was not affected.The removal of pyrene from the spiked soils planted with white clover was obviously higher than that from the unplanted soils.At the end of the experiment(60 d),the average removal ratio of pyrene in the spiked soils with white clover was 77%,which was 31%and 57%higher than those of the controls with or without micobes, respectively.Both roots and shoots of white clover took up pyrene from the spiked soils and pyrene uptake increased with the soil pyrene concentration.However,the plant-enhanced dissipation of soil pyrene may be the result of plant-promoted microbial degradation and direct uptake and accumulation of pyrene by white clover were only a small part of the pyrene dissipation.Bioconcentration factors of pyrene(BCFs,ratio of pyrene,on a dry weight basis,in the plant to that in the soil)tended to decrease with increase in the residual soil pyrene concentration.Therefore,removal of pyrene in the contaminated soils was feasible using white clove.
As a new class of xenogenous nanoparticle, quantum dots （QDs） possess the potential to co-exist with Cu^2＋ in human liver. The combined toxicity is thus concerned. Considering QDs and Cu^2＋ are known ROS （reactive oxygen species） inducer, we investigated the combined oxidative stress and corresponding protective strategy using human hepatic L02 cells. The results demonstrated that the presence of a small amount of MPA-CdTe QDs （2 μg/mL） in a Cu^2＋ solution （2.5-20 μg/mL） resulted in a higher toxicity with up to 8-fold cell viability decrease, which was accompanied by cell morphology changes. The combined toxicity was then confirmed as ROS associated oxidative stress with up to 300% and 35% increase of the intracellular ROS level and glutathione S-transferase （GST） activity, respectively. N-acetylcysteine （NAC） can also provide almost complete protection against the induced toxicity. Therefore, the ROS associated oxidant injury might be responsible for the QDs-Cu^2＋/Cu^2＋ induced toxicity and could be balanced through cytoprotective antioxidant enzyme GST.
Yuxia Zhao,Kuangfei Lin,Wei Zhang,Lili Liu State Environmental Protection Key Laboratory of Environmental Risk Assessment and Control on Chemical Process,Shanghai 200237,China
