The Remediation of Phenanthrene and Pyrene in Soil by Sudan Grass(Sorghum vulgare L.)

The effects of Sudan grass(Sorghum vulgare L.)and the interaction between plants and microorganisms on the removal of phenanthrene and pyrene from soils were studied by pot experiment in a greenhouse.The results showed that Sudan grass grew normally,and soil-grass system could significantly remove phenanthrene and pyrene from soils at initial concentrations ranging from 0 to 322.06 mg·kg-1 for phenanthrene and 0 to 321.42 mg·kg-1 for pyrene.After 60-day plantation of Sundan grass,the removal rates of phenanthrene and pyrene were 73.07% ～83.92% and 63%～77.62% respectively,which were averagely 55.58% and 50.71% higher than those of the CK(1without plants and addition of 0.1% NaN3),and 72.71% and 66.57% higher than those of CK(2without plants but with addition of 0.1%NaN3),respectively.The results suggested that plantation of Sudan grass significantly promoted the microbial degradation of phenanthrene and pyrene.Furthermore,the measurements on the activities of soil urease and polyphenol oxidase also indicated that the enzymes activities decreased with the increase of soil PAHs levels,and the degradation rates of PAHs increased with the increase of soil enzyme activities at the same initial PAHs concentrations.The enzymes activity of the treatment with plantation of Sudan grass(TR3)was higher than those of the two control treatments(CK1 and CK2) at the same PAHs level,which showed plants growth could enhance the enzymes activity of soil,and promote the PAHs degradation by indigenous microorganisms.Thus the interaction between plants and microorganisms was proved to be the main way for PAHs degradation.