| In recent years,with the rapid development of industry and agriculture,heavy metal pollution is getting worse,leading to soil and ecological environment deterioration,causing serious damage to the human beings and economic sustainable development,thus study on the remediation of heavy metal contaminated soil,especially on phytoremediation technology is particularly urgent.Lolium perenne L.is a good herb with strong tillering ability,rapid growth and wide adaptability,and has been studied extensively in remediation of heavy metals pollution.Cinnamomum camphora?L.?Persl is a common guardening and economic tree species in southern China,and some preliminary reports have been done on the accumulation of mining pollution by Cinnamomum camphora,but there are few reports about its application in phytoremediation of contaminated soil.In this study,Lolium perenne and Cinnamomum camphora were selected as the test materials,and 5 treatments were set up using indoor pot experiment,that is,fresh soil+Lolium perenne/Cinnamomum camphora?CK?,fresh soil+Lolium perenne/Cinnamomum camphora+1 mg·kg-1 cadimium?Cd1?,the cadmium contaminated soil+Lolium perenne/Cinnamomum camphora+10 mg·kg-1cadimium?Cd2?,the cadmium contaminated soil+Lolium perenne/Cinnamomum camphora+30 mg·kg-1 cadimium?Cd3?,cadmium contaminated soil+Lolium perenne/Cinnamomum camphora+30 mg·kg-1 cadimium+10 mg indole acetic acid·kg-1 dry soil?Cd3+IAA?.The changes of physiological and biochemical properties of Lolium perenne and Cinnamomum camphora and soil microbial activity are analyzed,and their enrichment ability of Cd and their potential for phytoremediation and field feasibility on the remediation of heavy metal contaminated soil are explored.The main results are as follows:?1?The absorption and accumulation characteristics of cadmium in Lolium perenne and the residue of cadmium in soil:the cadmium removal rates of Cd1,Cd2,Cd3 and Cd3+IAA are 12.0%?13.7%?16.7%and 7.53%,respectively.The cadmium content of Lolium perenne increased with the increase of cadmium concentration,the distribution characteristics of cadmium in tissues are:Cd contents aboveground>Cd contents belowground.The addition of IAA can significantly promote the accumulation of cadmium in Lolium perenne aboveground,while reducing the accumulation of Cd in the root.Therefore,presumably Lolium perenne can enrich cadmium,the addition of IAA can alleviate the toxicity of cadmium,improve Lolium perenne tolerance to cadmium and enhance the transference of cadmium from belowground to aboveground,so IAA can improve the remediation of Lolium perenne on cadmium contaminated soil.?2?The absorption and accumulation characteristics of cadmium in Cinnamomum camphora and the residue of cadmium in soil:The cadmium removal rate s of Cd1,Cd2,Cd3 and Cd3+IAA are 16.0%,9.6%,10.7%and 25.93%,respectively.The cadmium content in leaves of Cinnamomum camphor increased gradually with the increase of cadmium concentration,and the addition of IAA can promote the enrichment of Cd.The cadmium content of Cinnamomum camphora leaves in CK,Cd1,Cd2,Cd3,Cd3+IAA are 0.3 mg·kg-1,0.92 mg·kg-1,3.21 mg·kg-1,17.65 mg·kg-1,respectively,while the cadmium content in the treatment added with IAA is 29.84 mg·kg-1,indicating that IAA can play an important role in the enrichment of Cd.?3?High concentration of Cd can significantly reduce the ryegrass biomass of roots and aboveground parts.Different concentrations of cadmium pollution have less effect on chlorophyll synthesis of perennial ryegrass and Cinnamomum camphora leaves,and cadmium pollution stress can increase the peroxidase?POD?activity and malondialdehyde content,and promote osmotic regulation substances to adapt to the impact of adverse environment.The addition of IAA can alleviate the toxicity of cadmium to perennial ryegrass and Cinnamomum camphora.The soil basal respirations in the treatments added with Cd are higher than that in the control.High concentration of Cd can weaken the soil urease activity and the FDA hydrolysis activity,and increase the catalase activity.The addition of IAA can improve enzyme activity and alleviate cadmium stress on plants.?4?Through the comparison of the accumulation of cadmium in Lolium perenne to that in Cinnamomum camphora under the stress of cadmium pollution,better enrichment effect of Lolium perenne under cadmium pollution,and larger biomass of Cinnamomum camphora are found.Cadmium pollution has no impact on the growth of Cinnamomum camphora throughout the incubation period,showing that Cinnamomum camphora have strong tolerance to cadmium pollution and potential remediation effect.This study explored the effect of cadmium on the physiological and biochemical characteristics of Lolium perenne and Cinnamomum camphora leaf and soil microbial activity,of,and clarify the accumulation effect of Lolium perenne and Cinnamomum camphora on cadmium.The addition of IAA can significantly promote the enrichment of cadmium in Lolium perenne and Cinnamomum camphora.and Cinnamomum camphora can be applied to the remediation of contaminated soil in the future,which has great application prospect. |
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