植物修复重金属-有机物复合污染河道疏浚底泥的研究

Phytoremediation of Heavy Metal-Organic Complex in Dredged Sewage River Sediment

针对目前国内普遍存在的排污河道污染问题,通过盆栽试验研究了玉米、印度芥菜、超积累油菜、紫花苜 蓿在施用不同配比的排污河道疏浚底泥上对重金属-有机物复合污染的修复情况及超积累的机理．结果表明,随着 底泥配比的增加,植物发芽率的抑止程度也增加;适应底泥中高浓度复合污染的植物,底泥施用能促进其生长,提 高植物体内的叶绿素含量．植物体内积累的重金属Zn、Pb、Cd以生长在底泥与土壤比为2:1的印度芥菜为最大,分 别为1 521 mg／kg、453 mg／kg和11．7 mg/kg;Cu、Ni积累量以生长于底泥中的玉米为最大,分别为128 mg／kg和 89．1 mg／kg．在本实验条件下,底泥中有机物以种植玉米的底泥为最大,为76．89％．通过环境扫描电子显微镜及配 套的能谱分析发现,重金属在植物体内的聚集存在;经X荧光光谱仪和X射线衍射仪分析,确证了配合体之间及重 金属和配合体相互形成架桥而聚集成团,形成重金属结合物积累在植物体内,且在植物根部发现积累了Cu的有机 氯化物．种植前后底泥的X射线衍射对比表明,种植后重金属的晶格结构和存在形态发生了变化．

In order to solve the problem of ubiquitous polluted sewage rivers in China, pot experiment was conducted to study phytoremediation efficiency of maize, Indian mustard, oilseed rape and Medicogo sativa L in cleaning heavy metal-organic contaminated sediment. The experiment soils were prepared by mixing dredged sewage fiver sediments with clean soil in different ratios. Some mechanisms of heavy metal absorbed by hyperaccumulting plants were studied. Results showed that seeds germinating ratio decreased with the increase of contaminated dredged sediment; On the other hand, for the plants that acclimatized to the high concentration of heavy metal-organic contamination, the sediment promoted plant growth and increased chlorophyll concentration in the plants. Indian mustard in contaminated soil with the mixing ratio of sediment to soil as 2：1 had the highest accumulation of Zn, Pb, Cd, of which the accumulation was 1 521 mg/kg, 453 mg/kg, and 11.7 mg/kg, respectively. The highest accumulation of Cu and Ni was in maize with the mixing ratio of sediment to soil as 3： 0, and the corresponding accumulation amounts were 128 mg/kg and 89.1 mg/kg, respectively. In this experiment, after planting, the removal efficiency of organic was 76.89 % in the mixture of sediment to soil as 3： 0. Through environmental scanning electron microscope （ESEM） and its energetic chart analysis apparatus, muhinuclear heavy metals clusters were found. The results of X-ray fluorescence spectrometer （XFR） and X-ray Diffraction （XRD） showed that the heavy metal accumulation in plant existed in the metal-organic clusters through the bridging of ligand and heavy metals. Organic copper chloride was found in plant roots. The XRD resuits showed clearly that the heavy metals＇ crystal lattice conformation and configuration were changed after planting.