中文摘要：

通过野外采样、室内分析和水培实验,研究了某废弃铀矿坑水中的土著水生植物大薸（Pistia stratiotes L.）和凤眼莲（Eichhornia crassipes）对铀矿坑水的原位修复能力。野外采样分析结果表明,大薸和凤眼莲对废弃铀矿坑水中的铀有极强的富集能力。废弃铀矿坑水中铀浓度在0.4~0.6mg/L之间,高出国家排放标准（GB 23727—2009）规定值（0.05mg/L）的10倍左右。废弃铀矿坑水中土著水生植物大薸和凤眼莲根系平均铀含量分别为1 015.40mg/kg（干重）和504.87mg/kg（干重）;富集系数分别为2 071和1 001。水培实验结果表明,大薸对铀矿坑水中铀的去除能力与植物生长期、生物量和覆盖水体面积呈正相关。生长后期（单株生物量鲜重≥100g）的大薸、凤眼莲,投加量为100g/L时,10d可将铀矿坑水中铀浓度由1.93mg/L降至0.03mg/L以下,去除率达到98%以上。SEM-EDS结果表明,大薸和凤眼莲在酸性条件下与水体中的铀结晶矿化,生成纳米片状晶体堆簇在根系表面;在碱性条件下（接近废弃铀矿坑水的pH值时）,未出现类似矿化结晶体。表明大薸和凤眼莲对于不同酸度的铀废水体系有不同的修复机理。

英文摘要：

The field sampling,laboratory analysis and hydroponic solution culture experiments were conducted on the native aquatic plants,Pistia stratiotes L.and Eichhornia crassipes in-situ repair ability of uranium mine pit water.The results of field sampling analysis show the strong enrichment of uranium from abandoned uranium mine pit water by Pistia stratiotes L.and Eichhornia crassipes.The uranium concentration range of abandoned uranium mine pit water is between 0.4mg/L to 0.6mg/L,which is about 10 times higher than the national emission standards of China.The mean uranium concentrations（dry weight）in roots of Pistia stratiotes L.and Eichhornia crassipes are1 015.40mg/kg and 504.87 mg/kg,and the enrichment coefficients are 2 071and1 001,respectively.The results of hydroponic solution culture experiments show that the uranium removal ability is closely relative to the growing period and fresh weight of per plant and the area of the plant covering water.100 g of Pistia stratiotes L.or Eichhornia crassipes at the mature stage（fresh weight more than 100 g per plant）are grown in 1 L of uranium mine pit water with the initial concentration of uranium was1.93mg/L,after 10 days,the uranium concentration reduces to below the national emission standards of China,and the uranium removal rates are higher than 98%.SEMEDS results show that a mass of uranium precipitates with nanometer sized schistose structures on the root surface of Pistia stratiotes L.and Eichhornia crassipes are formed at acidic conditions.But there are no similar crystals observed on the surface of PistiastratiotesL.and Eichhornia crassipes at alkaline conditions.The present work suggests the different repair mechanisms of uranium-contaminated waste water by the Pistia stratiotes L.and Eichhornia crassipes between acidic and alkaline conditions.