| With industrial development, more organic pollutants PAHs is brought into rivers, lakes, wetlands and other water bodies, the increasing concentration of PAHs is harm to the flora, fauna and the ecosystem of the water, even harm to human health, but the research on the PAHs is still in its infancy in China. PAHs contamination levels in water environmental, PAHs source, the contamination process and mechanism of PAHs in environmental, the features distribution, migration and transformation, the ecological risk assessment of PAHs inside regional are needed to be intensively studied.Plant and microbial remediation are two main ways to remove PAHs from the water bodies. Plants remediation associate with the different plants growth characteristics (including plant height, root intensity, capacity of pollutant absorption). The status of PAHs pollutants was investigated in the river inside Beijing area. A set of wetlands device was established in the laboratory, selected eight kinds of typical plants and researched PAHs removal mechanism, proposed a method to increase the removal, aims to provide a reasonable basis for the selection of wetland plants and match mode. The experiment will promote the research and control capability of PAHs, find out China’s rivers PAHs pollution actual situation, provide scientific basis and technical support for researching PAHs removal and management measures.Water quality survey results show that16kinds of PAHs, U.S. EPA priority control, were detected in9eastern suburbs rivers of Beijing, PAHs levels between216.2ng/L and1425.4ng/L, with an average of468.3ng/L. The PAHs content of Tonghui river and Ba river higher than that of Yuyuan tan. The river of urban district were polluted more severe than that of suburb; Wenyu river, Tonghui river, Ba river, which locate in the urban, the PAHs concentration of upstream was significantly higher than that of downstream; Beiyun river, Chaobai river, and White River, which were less affected by the urban, the PAHs concentration of upstream was lower than that of downstream; PAHs was mainly2and3rings PAHs, and the concentration of two rings naphthalene was highest. High molecular weight PAHs was mainly four rings, and rarely5and6ring. The source of PAHs was mainly high temperature combustion, as well as vehicle exhaust pollution by petroleum sources.Laboratory results show that different plants have different removal of PAHs, and the highest removal rate can reach30%-70%; When continuous influent water ways, ecological plant was average remove PAHs:Hydrilla verticillata (34.4%)> Arundo donax (33.2%)> Reed (28.7%)> Spinach (28.5%)> Wild rice (27.6%)> Water hyacinth (27.2%)> Iris (26.8%)> Renewable flowers (17.9%). When intermittent influent water, the average remove PAHs:Arundo donax plants (40.5%)> Wild rice (37.9%)> Iris (37.0%)> Reed (36.9%)> Renewable Flowers (34.6%)> Water hyacinth (33.9%)> spinach (31.2%)> Hydrilla verticillata (29.3%);2,3-ring PAHs was mainly absorbed and degraded, and degradation efficiency can reach70%.This study researches the status of PAHs polluted in the eastern suburbs rivers of Beijing, indicating that all rivers have been affected by PAHs pollutants, the results will provide a reliable basis and important scientific significance for the environmental risk assessment, environmental planning and environmental management of this area.Laboratory ecosystems experiments indicate that the source and composition of PAHs are distinctive, different plants have different PAHs removal effects of mechanism and degradation under different influent water ways. Different treatment measures was required to different actual status of pollution rivers, using mix and match between the plants to establish a diversity of ecosystem in eco-level space for treating rivers and purifying PAHs polluted. |
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