Study on phytoremediation of phenanthrene-contaminated soil with alfalfa (Medicago sativa L.)
苜蓿对多环芳烃菲污染土壤的修复作用研究

Pot experiment was used to investigate phytoremediation of phenanthrene-contaminated soil with alfalfa(Medicago sativa L.). Results indicated that phenanthrene had inhibitive effect on alfalfa growth, and higher phenanthrene concentration seriously prevent alfalfa growth. When the concentration was 445.22mg/kg, the shoot and root biomasses were only 57.31% and 31.20% of control respectively. Alfalfa significantly promoted phenanthrene degradation in the soil. After 60 days, 85.68%~91.40% and 75.25%~86.61% of spiked phenanthrene disappeared from the rhizosphere and non-rhizosphere soils respectively. And the average removal ratio of phenanthrene in rhizosphere soils was 6.33% higher than that in non-rhizoshpere soils. The residual concentration of phenanthrene in the rhizosphere was lower than that in the non-rhizosphere but the dehydrogenase activity was on the contrary. With phenanthrene concentration increase the removal ratio and dehydrogenase activity decreased. A positive correlation was observed between the soil dehydrogenase activity and the removal ratio of phenanthrene in both the rhizosphere and non-rhizosphere soils. Therefore the presence of alfalfa roots was effective in promating the phytoremediation of phenanthrene.