沉水植物对受重金属镉、锌污染的水体底泥的修复效果

为了探究常见沉水植物对水体底泥中重金属污染的富集效果，选取浙江水域较为常见的3种沉水植物苦草（Vallisneria natans （Lour.） Hara）、黑藻（Hydrilla verticillata（Linn.f.） Royle）、金鱼藻（Ceratophyllum demersum L.），在模拟天然水体环境中，将3种沉水植物培养在含有重金属Cd、Zn的底泥中生长一个生活周期.依据沉水植物对重金属Cd、Zn的富集量和生物-沉积物生物富集因子（biota-sediment accumulation factor，BSAF）等指标，筛选出对2种重金属元素富集效果较好的沉水植物，为受重金属污染底泥生态修复的植物选择提供一定的参考.结果表明：3种沉水植物对重金属Cd、Zn的耐受性均较强，同时对重金属Cd、Zn都有较高的富集能力，生物富集因子大于1，对底泥中的Cd、Zn均具有较好的祛除效果；由相关分析可知，3种沉水植物体中的Cd、Zn的质量分数与其根部底泥中Cd、Zn的质量分数呈极显著的负相关（p<0.01），因此这3种植物均可作为重金属Cd、Zn污染的修复物种.苦草对重金属Cd、Zn的富集量及BSAF均大于黑藻和金鱼藻，对重金属Cd的富集量分别达到了黑藻和金鱼藻的1.90和3.02倍.因此可考虑苦草作为水体底泥Cd、Zn复合污染生态修复的先锋物种.

A study on the absorption of cadmium and zinc in the water sediments with submerged plants

Three common submerged plants in Zhejiang province, namely Vallisneria natans (Lour.) Hara, Hydrilla verticillata(Linn.f.) Royle and Ceratophyllum demersum L., are investigated to explore their enrichment effects of heavy metals in the sediments of water. During the study, a simulated outdoor natural water environment was setup, three different submerged plants were cultivated for 105 d in the sediments of water which containing high concentration of cadmium (Cd) and zinc (Zn), the accumulation amount and biota-sediment accumulation factor (BSAF) of two heavy metals were measured to identify the species with best enrichment effect, providing a theoretical reference for selecting suitable plants that could restore ecologically contaminated sediments. The results show that BSAF for Cd and Zn are both greater than 1 for all species after for 105 d, suggesting that these submerged plants had powerful absorption ability, good removal effect on Cd and Zn in sediments, and a strong tolerance for the combined pollution of Cd and Zn. Meanwhile, there was a significant negative correlation between the content of Cd and Zn in sediment and that in these three plants (all with p<0.01), Therefore, Vallisneria natans (Lour.) Hara, Hydrilla verticillata(Linn.f.) Royle and Ceratophyllum demersum L. could be considered as common species to lieve the sediment pollution caused by Cd and Zn. In particular, Vallisneria natans (Lour.) Hara can be selected as a pioneer plant for ecological restoration of Cd and Zn jointly polluted sediments in water.