Influence of Arbuscular Mycorrhiza and Rhizobium on Phytoremediation by Alfalfa of an Agricultural Soil Contaminated with Weathered PCBs: A Field Study

Abstract

A field experiment was conducted to study the effects of inoculation with the arbuscular mycorrhizal fungus Glomus caledonium and/or Rhizobium meliloti on phytoremediation of an agricultural soil contaminated with weathered PCBs by alfalfa grown for 180 days. Planting alfalfa (P), alfalfa inoculated with G. caledonium (P+AM), alfalfa inoculated with R. meliloti (P+R), and alfalfa co-inoculated with R. meliloti and G. caledonium (P+AM+R) decreased significantly initial soil PCB concentrations by 8.1, 12.0, 33.8, and 43.5%, respectively. Inoculation with R. meliloti and/or G. caledonium (P+AM+R) increased the yield of alfalfa, and the accumulation of PCBs in the shoots. Soil microbial counts and the carbon utilization ability of the soil microbial community increased when alfalfa was inoculated with R. meliloti and/or G. caledonium. Results of this field study suggest that synergistic interactions between AMF and Rhizobium may have great potential to enhance phytoremediation by alfalfa of an agricultural soil contaminated with weathered PCBs.

KEY WORDS:

• contaminated soil
• polychlorinated biphenyls
• phytoremediation
• alfalfa
• Rhizobia
• Arbuscular mycorrhizal fungi

ACKNOWLEDGMENTS

This work was supported by grants from the Knowledge Innovation Program of the Chinese Academy of Sciences (KZCX2-YW-404 and CXTD-Z2005-4), the National Natural Science Foundation of China (40701080 and 40621001), the National Basic Research Program (973) of China (2002CB410809) and the Natural Science Foundation of Jiangsu Province (BK2005166).

Notes

^aRatio of soil PCB mass removal content to PCB initial content in soil in quadrat.

^bRatio of total PCB mass in alfalfa to that in the estimated 1630 kg of soil per quadrat.