南京市不同园林植物根际土壤养分和重金属富集特征

Distribution of Soil Nutrients and Heavy Metals in Rhizosphere versus Non-rhizosphere Area of Different Landscape Plants in Nanjing

通过对南京市6种园林植物(金银木、紫荆、腊梅、丁香、木槿和海棠)根际与非根际土壤养分和重金属分布特征进行研究,探讨不同植物根际养分和重金属的富集的相关性和差异性。(1)不同园林植物根际和非根际土壤养分和重金属呈一致的变化规律,它们的主导控制因子也基本相同,其中不同园林植物根际土壤养分和重金属均高于非根际养分含量,而不同园林植物根际土壤pH均低于非根际。(2)不同园林植物根际土壤养分、重金属含量和有效态重金属含量均显著高于非根际,表现出显著的富集作用,而根际土壤pH则显著低于非根际,表现出显著的亏损作用,全磷在根际与非根际土壤中差异不显著(p>0.05)。(3)不同园林植物根际和非根际土壤重金属含量与有效态含量均存在极显著的正线性相关关系,二者能够用线性方程式体现,表明了不同园林植物根际和非根际土壤有效态重金属含量主要来自土壤重金属总含量。(4)相关性分析表明:对于根际土壤,土壤有机碳和全氮对土壤重金属全量影响较大;而对于非根际土壤,土壤有机碳和全氮土壤有效态重金属影响较大;而pH与土壤重金属含量基本呈显著或极显著的负相关关系;全磷对于土壤重金属含量基本没有影响。通过以上研究说明不同园林植物土壤养分和重金属含量在根际存在一定的富集,它们通过降低根际pH值可以提高根际养分,而有效态重金属较全量对植物根际微小的变化响应更为灵敏。

Six landscape plants, Lonicera maackii , Cercis chinensis , Chirnonanthus praecox , Syzygium aro- maticurn, Hibiscus syriacus, and Chaenorneles speciosa in Nanjing were selected. However, the distribution of soil nutrients and soil heavy metals in the rhizosphere and non rhizosphere areas of these six landscape plants in this region had been largely unknown. The results were as follows： （1）The soil nutrients and heavy metals of different landscape plants of rhizosphere and non-rhizosphere had the same change, also with the main control factors, and the content of soil nutrients and heavy metals in rhizosphere was higher than that of non-rhizosphere, while pH was lower than that of non-rhizosphere. （2）The soil nutrients and heavy metals of different landscape plants showed significant enrichment and pH showed significant loss, while soil total phosphorus in rhizosphere had no significant difference to non-rhizosphere soil （p〉0.05）. （3）The contents of available heavy metals extracted by TCLP correlated with total contents of heavy metals, which showed the total soil heavy metal was one of the important sources of the available soil heavy metal. （4）Correlation analysis showed that, as for the rhizosphere soil, soil organic carbon and total nitrogen had the larger influ- ence on soil heavy metals, as for the non-rhizosphere soil, soil organic carbon and total nitrogen had the lar- ger influence on soil available heavy metals, pH had the significant or extremely significant negative correla- tion relationship with soil heavy metals, while soil total phosphorus had no correlation relationship with soil heavy metals. It indicated that the rhizosphere enrichment effect occurred for different landscape plants, rhizosphere enrichment effect was found to increase soil nutrients by reducing soil pH, and the content of soil a- vailable heavy metals was more sensitive than that of soil heavy metals.