环毛蚓在高羊茅修复土壤菲污染过程中的作用

Roles of earthworm(Pheretima sp.) in Festuca arundinacea remedying of soils polluted by phenanthrene

为了解土壤动物在植物修复多环芳烃类化合物过程中的作用,采用盆栽试验法,对比研究了蚯蚓(Pheretima sp.)活动对高羊茅(Festuca arundinacea)修复土壤菲污染的影响效应以及各种生物、非生物因子在植物修复菲污染过程中的作用。结果显示,在20.05～322.06mg·kg-1菲污染水平范围内,与相同污染水平下无蚯蚓作用的菲污染土壤中生长的植株相比,蚯蚓活动促进修复植物高羊茅的生长:试验期间(72d),修复植物的单株生物量增加9.74%～21.53%,根冠比增加17.26%～21.44%。添加蚯蚓72d后,种植高羊茅的菲污染土壤中,菲的去除率高达61.70%～88.78%,其平均去除率(77.38%)比无蚯蚓活动的土壤-植物系统中的(68.36%)提高了9.02%,比无植物生长的对照组土壤(22.57%)提高54.81%。各种生物(如植物代谢、植物积累、动物积累、微生物降解、植物-微生物交互作用等)、非生物(如渗滤、吸附、光解、挥发等)因子中,植物-微生物交互作用对菲去除的平均贡献率(47.81%)最为突出,比无蚯蚓活动时(42.08%)提高5.73%。说明蚯蚓活动可强化土壤-植物系统对土壤菲污染的修复作用。

To evaluate the contribution of the soil macrofauna on the dissipation of polycyclic aromatic hydrocarbons （PAHs） in rhizosphere soil, a pot experiment was carried out to investigate effect of earthworm （Pheretima sp.） on Festuca arundinacea remedying soils polluted by phenanthrene （Phe） in, and role of biotic ＆ abiotic factors in the process of dissipation of Phe in soils was estimated. Results showed that earthworm activity promoted growth of Festuca arundinacea, whose biomass per plant was 9.74%-21.53% larger than those in the treatment without earthworm introduced in, and apparently increased its root/shoot ratio, which was 17.26%-21.44% greater than those in corresponding non-inoculated soils at initial concentrations of Phe ranging from 20.05 to 322.06 mg·kg^-1 seventy-two days after earthworm was introduced in. During the experiment, averagely 77.38% of Phe was removed from the soils planted grass, which was 9.02% greater than those without earthworm introduced in, and 54.81% greater than the loss in non-vegetated soils without earthworm. Among all possible pathways including both biotic factors （e.g., plant metabolism and accumulation, earthworm tissues accumulation, microbial degradation and plant-microbial interactions, etc） and abiotic factors （e.g., leaching, volatilization, photodegradation and irreversible sorption, etc）, the plant-microbial interaction was proved to be the primary means of Phe degradation, either with or without earthworm activity, and its contribution to the removal of Phe in planted soils accounted for up to 47.81% of the total removal, which was 5.73% higher than those in corresponding soils without earthworm. Besides the accumulation of Phe in grass was found to be reduced by incubation of earthworm in soils, thus the ecological risks of Phe could be relieved. The findings suggested a feasible way for the establishment of high-efficient phytoremediation of soil PAHs pollution by introducing earthworms into the soil-plant system.