The Study Of Repairing Potential Of Three Plants To PAHs、Cu、Cd Single And Compound Polluted Soil

Compound Pollution is a common phenomenon in soil pollution,the relevant heavy metals(HM)and persistent organics(such as polycyclic aromatic hydrocarbons,PAHs)compound polluted in soil have been reported constantly.Compared with the physical and chemical methods,phytoremediation has the advangtages such as low cost,no secondary pollution,etc.This experiment used sorghumxsudan grass,zea mays.L and ryegrass as repairing plants,and selected phe、phr、Cu、Cd as pollutants,through indoor pot experiment,which used single and compound designing,from the result of plants’growth,the physiological effect,the absorption and accumulation of heavy metals and phe、phr degradation,etc,we had researched the single and composite effect of PAHs,Cu and Cd to plants’ toxic effects and the potential of plants to repair PAHs、Cu、Cd polluted soil,and the results showed that:(1)sorghumxsudan grass can grow in phenanthrene and pyrene polluted soil ranging from 5 to 500 mg·kg-1,and apparently increase degradation efficiency of phenanthrene and pyrene.The average degradation rate of phenanthrene and pyrene is respectively 67.41%and 53.11%,14.30%and 9.34%higher than the compared group in plant-soil system.Urease and polyphenol oxidase activity in soil was meanwhile enhanced.(2)All test plants sorghumxsudan grass,Zea mays.L and ryegrass can grow in single contaminated substrate include Cu,Cd,and polycyclic aromatic hydrocarbons(PAHs)and in their compound contaminated circumstance.Substrate concentration in single contaminated system effects the plant biomass most.The effects of low-concentration of Cu-Cd and Cu-PAHs on plant is antagonism,while both the moderate and high concentration turned out to be synergy.The compound system of Cd-PAHs and Cu-Cd-PAHs effects were also synergy.Ryegrass has a higher tolerance degree on single and compound contamination of Cu、Cd and PAHs than that of sorghumxsudan grass and Zea mays.L.(3)Chlorophyll content of sorghumxsudan grass,Zea mays.L and ryegrass was greatly effected by single and conpound contanminated system of Cu,Cd,and PAHs.Among them,substrate concentration in single contaminated system effects the chlorophyll content most.Low-concentration compound system of Cu-Cd and Cu-PAHs can increase content of chlorophyll,while both high-concentration system can decrease it.(4)All test plants include sorghumxsudan grass,zea mays.L and ryegrass can accumulate Cu and Cd both in single and compound cantaminated system.And the capabilty for Cd is higher than that of Cu.Zea mays.L and ryegrass can accumulate more Cu and Cd in contaminated soil.Compared to the accumulation in compound system of Cu-Cd,the amount of Cu in single system was higher while the amount of Cd was lower.In general,low-concentration system of Cu-PAHs can increase accumulation of Cu by sorghumxsudan grass and zea mays.L,while the high-concentration can decrease the process.Ryegrass in stead did not show a similar rule and it suggested that the accumulation amount of Cu in compound system is higher than that in single one.Cd accumulation of All plants in compound system were lower than that in the single ones.Copper and cadmium accumulation in system of Cu-Cd-PAHs were lower than that inCu-Cd system.(5)All three plants hold a high degradation efficiency of phenanthrene and pyrene in different contaminated soil.And the degradation efficiency in low-concentration of Cu-Cd system was higher than that in single ones.Cd-PAHs、Cu-Cd-PAHs and high-concentration of Cu-PAHs can decrease degradation efficiency of PAHs by different plants.The result suggested that ryegrass can more efficiently degrade PAHs than sorghum and corn in the diversity contaminated systems.Though each of the test plant in our study—sorghum xsudan grass,zea mays.L and ryegrass is not hyperaccumulator,all can grow and strengthly tolerance both single and compound contamination of PAHs,Cu and Cd.And all can accumulate a large number of Cu and Cd,grow healthy,held a high biomass and degrade PAHs efficiently.Therefore,the three plants are potential in remediation of both single and compound contamination system of PAHs,Cu and Cd.Among them,ryegrass show a higher capability in accumulation,tolerance and degradation than sorghumxsudan grass and zea mays,is recommended to the most potential plant for soil remediation of PAHs,Cu and Cd.