水生植物大薸和凤眼莲对水中铀的去除

通过室内水培和静态吸附实验,研究了铀矿区土著水生植物大薸(Pistia stratiotes L.)和凤眼莲(Eichhornia crassipes)对真实铀矿坑水和不同铀浓度水中铀的去除能力。结果表明:干体大薸和凤眼莲根系以1g/L(干重)的比例投加至铀矿坑水(ρ0(U)=1.93mg/L,pH0=7.83)中,1h后,矿坑水中铀去除率分别达58%和48%,5d后铀质量浓度降至0.3mg/L以下;活体大薸和凤眼莲对水体中铀的去除作用主要集中在第1d内,单株鲜重约为400g左右的活体大薸在10min内可以将1Lρ0(U)=0.045~4.5mg/L的水体中铀质量浓度降至30μg/L以下,符合世界卫生组织建议的饮用水标准;单株鲜重约为400g左右的活体凤眼莲在1d内可以将1Lρ0(U)=0.5~4.5mg/L的水体中铀质量浓度降至国家标准(GB 23727—2009)规定值(0.05mg/L)以下。

Uranium Removal From Water by Pistia Stratiotes L.and Eichhornia Crassipes

Laboratory hydroponic and static adsorption experiments were conducted on the uranium removal by Pistia stratiotes L. and Eichhornia crassipes from the real uranium mine pit water and the solution which contained different initial uranium concentration. The removal rate of uranium could reach 58% and 48% by 1 g/L of the dried root biomass of Pistia stratiotes L. and Eichhornia crassipes from the real uranium mine pit water (the initial uranium mass concentration was 1.93 mg/L and the initial pH value was 7.83） in 1 h, respectively. After 5 d, the uranium mass concentration could reduce to below 0.3 mg/L. The uranium removal was rapid by the living Pistia stratiotes L. and Eichhornia crassipes which could remove more than 95% of total removal rate taking place in 1 d. Only 10 min was required for the Pistia stratiotes L. which has 400 g fresh weight per individual plant with the initial uranium mass concentration in water of 0.045-4.5 mg/L to reduce to below the standards of the world health organization (30 μg/L). Then 1 d was required for the Eichhornia crassipes which has 400 g fresh weight per individual plant with the initial uranium mass concentration in water of 0.5-4.5 mg/L to reduce to below the national emission standards of China (0.05 mg/L).