| The development of modern industry lead to increased environmental pollution,especially heavy metal pollution of farmland soil has attracted attention of the society.In this paper,the effect of plant growth probiotics and AMF on phytoremediation of heavy metal contaminated soil was studied by pot and field experiments.The 300 acres of repair experimental base was established in the wild with shrubs,Photinia,Phnom Penh boxwood,golden privet,spring and other garden plants as the main body.The results will provide the basis for restoration and rational use of heavy metal pollution of farmland.The Cu and Pb contaminated soils were selected as experimental materials to explore the effects of soil bacterial strain Y4-4(Pantoea sp.)and arbuscular mycorrhizal fungi(AMF)for the growth-promoting of plant bermuda grass(Cynodondactylon(Linn.)Pers)and plant uptake and transport Cu and Pb in the soil.The results showed that plant biomass with application of Y4-4 bacterial manure increased 21.4～38.7%compare with non-application of Y4-4.The concentration of Cu and Pb decreased 6.6%and 53.3%in the plant’s overground,respectively.The concentration of Cu increased 14.3%and the concentration of Pb decreased 24.5%in the the plant’s underground,respectively.Total Cu and Pb accumulation increased 45.8%-189%and 25.4%～162%in the bermuda grass based on the results of plant biomass and heavy metal content.The biomass and plant total biomass significant increase in the overground of bermuda grass after application of AMF compare with non-application.The concentration of Cu and Pb decreased 28.6%and 51.3%in the plant’s overground,respectively.The concentration of Cu increased 5.6%and the concentration of Pb decreased 28.2%in the the plant’s underground,respectively.However,accumulation amount of Cu and Pb in the plant significant increase 229%and 152%,respectively.The results showed that two strains that selected in the study had obvious plant growth-promoting effect and improved significantly biomass of plants and accumulation of heavy metals in heavy metal contaminated soil.The bacterial manure of strains Y4-4 and AMF were prepared in the study.The results of carrier selection of strain Y4-4 showed that live bacteria numbers of bacterial manure formulae 1,2,3,4 and 6 are more than 108 cfu/g after incubation of 30,60,90,120,150 d at room temperature.The bacterial manure of formula 2 with the maximum biological activity had not pollution and consistent with the standard in《microbial fertilizer》NY227-94。The carrier of AMF bacterial manure is main sand,zeolite-based with spores of 532 per gram.Mycorrhizal infection rate in adsurgens,peacock grass and other plants was higher than 70%after 60 days with application of the carrier.The effects of bacteral manure Y4-4 and AMF for plant growth,nutrients,absorption and accumulation of heavy metals and heavy metals content in soil were determined in the Cu,Pb contaminated farmland after 2 years of field experiment.The results showed that the concentration of heavy metals had not significant change after application of bacterial manure.Total heavy metals accumulation slight increased in the plant as a result of plant growth-promoting effect.Heavy metal content did not decrease in heavy metal contaminated soil due to repair time shortage and plant uptake mainly the effective state of heavy metal ions in the soil.However,the result showed that bacterial manure of Y4-4 and AMF had certain application value in plant-microorganism combined repair of heavy metal contaminated soil.Sampling survey of heavy metal pollution in farmland soil was carried out in 300 acres farmland of Jurong and Zhangjiagang.The results showed that Cu and Pb were mainly heavy metals in Jurong and Zhangjiagang farmlands,respectively.Cu content range was 45.8～1305.3 mg/kg with an average of 313.7 mg/kg in Jurong farmland and Pb content range was 15.2～99.2 mg/kg with an average of 48.0 mg/kg in Zhangjiagang farmland.Plant-microbe combined repair test was carried out for three years by application of bacteral manure in heavy metal contaminated soil located in Jurong and Zhangjiagang.Willow bush,safflower Loropetalum,Phnom Penh boxwood and other 18 kinds of green economy seedlings were selected in the field experiment.The results showed that Cu content range in leaves and stalk of 18 kinds of plants was 3.5～31.2 mg/kg with an average of 11.1 mg/kg and 3.0～45.3 mg/kg with an average of 12.1 mg/kg in Cu contaminated soil of Jurong,respectively.Pb content range in leaves and stalk of 5 kinds of plants was 3.2～10.1 mg/kg with an average of 6.9 mg/kg and 3.9～10.7 mg/kg with an average of 7.1 mg/kg in Pb contaminated soil of Zhangjiagang,respectively.The total amount of heavy metals in the overground part of each plant was compared.The results showed that Ligustrum with 54.2g Cu/acre was the highest Cu accumulation,next in turn,bamboo willow,beech trees,azalea and chinese rose with 40.7 g Cu/acre,28.6 g Cu/acre,14.8 g Cu/acre and 13.6 g Cu/acre in the Cu contaminated soil,respectively.Cassia with 32.7g Pb/acre was the highest Pb accumulation,next in turn,bamboo willow,shrub willow and Photinia with 18.6 g Pb/acre,11.6 g Pb/acre and 10.9 g Pb/acre in the Pb contaminated soil,respectively.The average of Cu content was 305.5 mg/kg in Cu contaminated soil of Jurong and the average of Pb content was 42.8 mg/kg in Pb contaminated soil of Zhangjiagang by bioremediation experiment for three years.However,the concentration of heavy metal had no significant different compared with that of three years ago.The results of economic effect analysis of various plants showed that the top five plants per acre income in three years is beech trees,azaleas,crape myrtle,saffron Loropetalum,shrub willow,which economic output increased 1.6～2.8 times compare with rice and wheat rotation in south of Jiangsu area.Thus,using economic plants instead of cropsis is a sensible strategy with efficient and rational use of heavy metal pollution of farmland,and obtain higher economic returns... |
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