| Polycyclic aromatic hydrocarbons (PAHs) is not included in the Stockholm convention, but it has all the typical characteristics of the persistent organic pollutants. Qingyuan Long Tang is one of the main e-waste dismantling area in China and even in the world. Because of its rugged processing method, and that the policy and legal system is not well organized, it results in a large number of polluted compounds assessed to the environment. And now the scope of POPs are gradually expanding owing to its transfer property. So do the PAHs. Polycyclic aromatic hydrocarbons which widely exists in the atmosphere, water, sediment, soil and biology, is serious harm to human health. The plant rhizosphere can produce many secretions, and plant roots is also the main place for the microbial growth. Soil is an important tending towards of PAHs, the growth of the surrounding plants and the joint action between soil and microbes will be a research focus in the environmental remediation in the future. The PAHs in the e-waste dismantling area of Longtang zhen, qingyuan city, guangdong province as the research object in the study.We examine its levels, distribution and composition in plants and soils surrounding the e-waste burning site. In order to explore the influenced factors of polycyclic aromatic hydrocarbons concentration distribution surrounding the burning site, and take the preliminary analysis of the origin and the information of PAHs, and using the PAHs content changes and differences of distribution between plants and soils for the phytoremediation of ecological environment, especially providing the scientific argument for the PAHs rhizoremediation.We selected11kinds of different plants and their rhizosphere and non rhizosphere soils, plant root and stem leaf plants belong to a group of samples, a total of22soils (eleven rhizosphere soils and eleven non rhizosphere soils in qingyuan electronic waste area) content of PAHs were determined, results showed that PAHs content ranged from133to626ng/g in rhizosphere soils, and59.8to816ng/g in non-rhizosphere soils. On the composition, rhizosphere soils and non rhizosphere soils were mainly4rings compounds, accounted for nearly50%of the total PAHs content and the trend of the concentration distribution were very similar. About the analysis of sources on the PAHs, the non rhizosphere soils of variation coefficient were greater than the rhizosphere soils. It certificated that PAHs in non rhizosphere soils was mainly affected by source and it was strongly influenced by the TOC, and its’main source was the electronic waste incineration of point source pollution, and rhizosphere soils come mainly from the degradation of rhizosphere activities, as well as the pollution of atmospheric sedimentation were attached to the surface.At the same time the study taked22plants samples (including11kinds of plant stem leaf in plants and roots) for PAHs content determination, it showed that the total content of the plant shoots ranged from96.1to389ng/g, and the scope of plant roots ranged from144to605ng/g. On composition of plant tissues was given priority to with3ring compounds, the content of total PAHs was54.1%and63.2%respectively, and its content distribution trend was very similar. The content of Polymer PAHs, such as InD, DiB and BghiP, in plant tissues were0. This is the reason that the PAHs in high molecular compound was difficult to transfer in the soil granular structure and be absorbed by plant. The analysis of sources on PAHs in plant roots of variation coefficient was greater than the plant stem. It proved that pollutants in roots were mainly affected by source, i.e., the electronic waste incineration point. In the plant shoots, owing to the outside air, and the pollutants transport to shoot parts after the rhizosphere effect thus its source was more complicated.Based on the comparison of different study, we found that the degradation mechanisms of PAHs in monocotyledon and dicotyledon plants was different. The efficiency of PAHs degradation in monocot rhizosphere was higher than that in dicotyledon rhizosphere. The ability of rhizosphere PAHs degradation was low in straight-root plants. And the plant had a two-way transport function of PAHs, PAHs in rhizosphere soil and plant stem leaves related to a certain extent, their sources of pollution had similarities. There was no relationship of PAHs in plant roots, rhizosphere soils and non-rhizosphere soils, it showed that the compound source change drastically and the restoration of plant on soils mainly concentrated in the root activity. |
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