Promotion of pyrene removal from soils by Bidens maximowicziana

A pot experiment was conducted to investigate the potential of removal of pyrene from spiked soils planted with Bidens maximowicziana. The removal of pyrene from the spiked soils planted with B. maximowicziana was obviously higher than that from the unplanted soils. After 50 d, the removal ratio of pyrene in the planted soils was 79%, which was 28% higher than that of the unplanted soils. Pyrene was both accumulated at roots and shoots of B. maximowicziana. The RCFs (root concentration factors) were 1.64–2.20, whereas the SCFs (shoot concentration factors) were 0.8–1.1. Though the plant-enhanced removal of soil pyrene may be the result of plant-promoted microbial degradation, an amount of pyrene was still accumulated in plants. For example, 21.6 mg kg–1 was accumulated in plants when soil pyrene concentration was 121.3 mg kg–1. In addition, the soil dehydrogenase activity, microbial population and phenolic compounds were all improved in planted soils relative to unplanted soil. The increased microbial population and activities of the soil enzymes are presumed to be important for the removal of pyrene.