ライグラスと緑膿菌の複合処理による銅・鉛・カドミウム汚染土壌の改良・バイオレメディエーションの検討

Modification-bioremediation of copper, lead, and cadmium-contaminated soil by combined ryegrass (Lolium multiflorum Lam.) and Pseudomonas aeruginosa treatment.

• Guang-Yu Shi
• Ying-Jia Yan
• Zhi-Qiang Yu
• Lu Zhang
• Yuan-Yuan Cheng
• Wei-Lin Shi

抄録

本研究の主な目的は、ライグラス(Lolium multiflorum Lam.)を用いた複合重金属汚染土壌に対する緑膿菌による浄化効果の強化とそのメカニズムを検討することであった。その結果、複合重金属汚染は植物の生育を顕著に抑制する効果があり(P<0.01)、45日後にはライグラスの茎葉のバイオマスは28.2%減少し、根のバイオマスは34.7%減少した。また、土壌中のカタラーゼ活性は29.3％、ウレアーゼ活性は75.7％と著しく上昇し、土壌中の残留重金属の割合は減少したが、酸抽出可能な重金属は顕著に増加した。そのため、ライグラスの土壌中の重金属に対する吸収・蓄積性はある程度改善され、ライグラス中のCu, Pb, Cdの生物濃縮係数はそれぞれ35.9%, 55.6%, 283.5%増加した。外来微生物により、ライグラスの新梢ではCu, Pb, Cdの蓄積が著しく増加したが、根ではPbの蓄積が16.3%増加しただけで、Cu, Cdともに減少した。また，P. aeruginosaを接種した系では，植物中のCuとCdの移行係数は顕著に増加したが，Pbの移行係数は減少した。

The principal objective of this study was to investigate the strengthened remediation effect and relevant mechanism of P. aeruginosa on ryegrass (Lolium multiflorum Lam.) for soil contaminated by Cu-Pb-Cd compound heavy metals. The results showed that the complex heavy metals' contamination had remarkable inhibiting effect on the growth of plants (P < 0.01), and the biomass of ryegrass's stem and leaves declined by 28.2%, while that of roots decreased by 34.7% after 45 days. The inoculation of P. aeruginosa promoted the growth of ryegrass in polluted soil, in which the biomass recovered to the same level of that in normal plant; the activity of both catalase and urease in the soil also increased strikingly (by 29.3% and 75.7%, respectively); the ratio of residual heavy metals in the soil decreased, while the acid extractable heavy metals increased notably. Therefore, the absorption and accumulation of ryegrass to the heavy metals in soil were improved to some extent; the bioconcentration factor of Cu, Pb, and Cd in ryegrass increased by 35.9%, 55.6%, and 283.5%, respectively. The exterior microorganism allowed the accumulation of Cu, Pb, and Cd in shoots of ryegrass increasing remarkably, while in roots, only the accumulation of Pb increased by 16.3%, and that of both Cu and Cd decreased. Besides, in the P. aeruginosa-inoculated system, the transfer factor of Cu and Cd in plants increased strikingly, while that of Pb decreased.