Effects Of Growth And Elemental Absorption Of Several Garden Woody Plants Under The Lead And Cadmium Pollution Soil

The pollution of Pb and Cd in urban green land soil is serious.With the advantage of low-cost,high biomass,high heavy metal accumulation,do not enter the food chain and have a certain ornamental value,the garden woody plants have a broad prospects to restore the heavy metal contaminated soil.In this study,five garden woods named Sweetenia macrophylla,Ilex rotunda,Ficus microcarpa,Acacia confusa and Ormosia pinnata were used as materials.The effects of different pollution conditions on plant growth,nutrient absorption,heavy metal content and repairing consequent were studied by setting single and complex Pb and Cd contaminated soils with different concentration.It provides the theoretical basis for the restoration technology of heavy metal contaminated soil in urban green land.The main results were as follows:(1)Ficus microcarpa,Acacia confusa and Ormosia pinnata could still grow normally under the pollution of Pb and Cd,which exhibited a certain tolerance.Plant height,ground diameter,biomass,root length and root surface area were inhibited to varying degrees under the condition of Pb and Cd pollution.The degree of inhibition was related to plant characteristics,varieties,heavy metal species,content and pollution time.The biomass distribution of Ficus microcarpa was mainly distributed in the roots,but the biomass distribution of the other plants were on the opposite.(2)Single Pb and Cd pollution inhibited the storage of nitrogen,phosphorus and potassium of Acacia confusa,while the complex pollution inhibited the storage of nitrogen and potassium of Ficus microcarpa,Acacia confusa and Ormosia pinnata.Ficus microcarpa can accumulate and store the phosphorus and potassium in the root under Pb,Cd pollution conditions while the other plants accumulate and store the nitrogen,phosphorus and potassium in the shoot.(3)The Pb and Cd content and accumulation amount of the tested plants wereincreased with the increase of Pb and Cd concentrations of the soil.The ability of plants to absorb and accumulate Pb was greater than Cd.The distribution of Pb and Cd in the tested plants mainly showed roots>stem>leaves.The accumulation of Pb and Cd in Acacia confusa under the complex pollution were mainly concentrated in its shoots,and the transfer coefficient was mainly expressed as Pb>Cd,while the other plants were on the opposite.Root is the main organ to enriched the heavy metals.The enrichment effect of Cd is greater than that of Pb.(4)All of five tested plants were not Pb and Cd super-enriched plants.However,the absorption and accumulation of heavy metals is stronger than that of other woody plants in other studies.The comprehensive evaluation result of principal component analysis showed that,Ficus microcarpa had a best repair effect in a single Pb contaminated soil,Ilex rotunda had a best repair effect in a single Cd contaminated soiland,Ficus microcarpa had a best repair effect in a complex contaminated soil.Ormosia pinnata were the worst repairing effect plants under the Pb,Cd single and complex contaminated soil.