Phytoremediation efficiency of a PAH-contaminated industrial soil using ryegrass, white clover, and celery as mono- and mixed cultures
2011
Meng, Liang | Qiao, Min | Arp, Hans Peter H.
Purpose Phytoremediation has been recognized as a promising technology for the remediation of polycyclic aromatic hydrocarbon (PAH)-contaminated soils. However, little is known about how plant species and cropping patterns affect the process of phytoremediation removing PAHs. Therefore, the aim of this study was to investigate further the effects of monocultures or mixed cultures of different plant species on PAH phytoremediation. Materials and methods Soils were sampled from a coke plant in Beijing, and ryegrass, white clover, and celery were selected as the model plants. Pot experiment was conducted in a greenhouse using these plants as mono-, two-, and three-species mixed cultures for 75 days. At the end of the experiment, the soil and plant samples were collected for PAH analysis. Moreover, the lipid content and fresh biomass of plants were also determined. Results and discussion The average remaining percentage of PAHs in mixtures (48%) was significantly lower than those in monocultures (55%) and nonplanted soils (70%). In all treatments, plant-promoted biodegradation accounted for almost 99% plant-enhanced PAH losses, but plant uptake only contributed less than 2%. Between individual PAHs, 2-4-ring PAHs were generally more affected by plant uptake, especially for celery and mixed cultures, while 3-6-ring PAHs were impacted the most by biodegradation which was most enhanced in the presence of multispecies mixtures. Conclusions Our results suggest that certain multispecies mixtures facilitate the phytoremediation of PAH-contaminated soils over monocultures. Moreover, plant-promoted biodegradation was the major pathway for PAH phytoremediation, whereas plant uptake was the minor one. Both of these pathways were dependent on plant species, cropping pattern, and PAH size.
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