The Screening Of Phytoremediation In The Polluted Water By Nuclides And The Influence Of Fertilizers For Repairing

Nuclear pollution is one of the important environmental pollution, cesium, uranium is the main species of contamination. The paper has carried on the simulation studies of cesium, uranium biological effects of aquatic plants, screening aquatic plants that has strong cesium accumulation ability, and N, K fertilizations' consequences for plants absorb and accumulate 133Cs?238U. It can provide methods for the repairing the water contaminated by cesium or uranium.In the experiment of screening hyperaccumulation plants, it was divided into 0, 0.5, 2.5 and 10 mg.L-1 for the design of cesium contamination concentration, and included 9 kinds of aquatic plants, three duplications in order to study on the biological effects of different aquatic plants and they absorbed and accumulated of cesium. When the concentration of cesium was 0.5 mg.L-1, increased fresh weight of Polygonum hydropiper was significantly higher than other cesium concentration; when it's 2.5 mg.L-1, the biggest increased fresh weight was Alternanthera philoxeroides, it's more than 30.3% of CK. When it's 10 mg.L-1, Myriactis wallichii Less. had the biggest increased fresh weight, it's more than 63% of CK. On average, in all cesium concentrations Alternanthera philoxeroides' resistance was stronger, Potamogeton pectinatus L. and Eichhornia crassipes' was weak. Different plants had different Cesium contents and abilities on removing cesium contamination of water bodies. The average cesium content was successively Alternanthera philoxeroides > Polygonum hydropiper > Oryza.sativa L. > Eichhornia crassipes > Scirpus tabernaemontani > Potamogeton pectinatus L. > Myriactis wallichii Less. > Azolla imbricata(Roxb.)Nakai. The water cesium concentration at the harvest time reduced up to a minimum was sequentially Polygonum hydropiper, Alternanthera philoxeroides, Eichhornia crassipes, Oryza.sativa L., Myriactis wallichii Less., Scirpus tabernaemontani, Azolla imbricata(Roxb.)Nakai, Potamogeton pectinatus L. According to the biological effects, cesium content and accumulation in plants and the reduction of cesium in the water, Eichhornia crassipes, Oryza.sativa L. and Polygonum hydropiper were suitable for repairing low concentration of cesium contamination of aquatic plants; it was suitable for repairing high concentrations of cesium contamination of aquatic plants for Alternanthera philoxeroides, Polygonum hydropiper and Oryza.sativa L..In the experiment of N, K fertilizers for Eichhornia crassipes and Ipomoea aquatica Forssk absorbed and accumulated 133 Cs of water, it was divided into 0.5, 5 and 50 mg.L-1 for the design of cesium contamination concentrations, the use of N, K fertilizations was respectively 0?0.5 and 5 mg.L-1 in the each caesium concentration, three duplications in order to study N, K fertilizers on the biological effects of these two kinds of plants and they absorbed and transfered cesium in the various cesium polluted water. Amounts of N, K fertilizations applied had different effects on the biological effects and cesium content of Eichhornia crassipes in the various cesium polluted water. In terms of average cesium content, applying N fertilizer improved cesium content was 6.53% of Eichhornia crassipes, applying K fertilizer increased by 14.46%, N and K fertilizations combining application improved plants cesium content was 33.96% of Eichhornia crassipes. Applying N or K fertilization could strengthen and repair cesium's ability of Eichhornia crassipes,the effect was better of applying K alone than N. It was better for N and K fertilizations combining application on the ability of strengthening Eichhornia crassipes repaired cesium.In the experiment of N, K fertilizations for Oryza.sativa L. absorbed and accumulated water 133 Cs and 238 U, it was divided into 0.5, 5 and 50 mg.L-1 for the design of cesium or uranium contamination concentrations, the use of N, K fertilizations was respectively 0?5 and 50 mg.L-1 in the each caesium or uranium concentration, three duplications in order to study N, K fertilizations on the biological effects of Oryza.sativa L. and it absorbed and transfered cesium and uranium in the various cesium and uranium polluted water. Firstly, application of N and K fertilizations made cesium or uranium in plants accumulation increase before earing under the stress of cesium and uranium, the biggest role of strengthening and repairing cesium about the dosage of N and K was 50 mg N·kg-1 and 5 mg K·kg-1, and it was 50 mg N·kg-1 and 50 mg K·kg-1 about uranium. Secondly, the dosage of N and K of lower content about mature rice grains was 5 mg N·kg-1 and 50 mg K·kg-1, it was conducive to reduce cesium or uranium consumption of threat for the human body. N, K fertilizations had different effects on absorbing cesium or uranium for the rice before earing. The suitable combination of N and K fertilizations could strengthen repairing ability. N, K fertilizations had different effects on cesium or uranium content of rice grains. The suitable combination of N and K fertilizations could reduce cesium or uranium content of the rice grains.This study shows that when cesium contaminated water, we can use Eichhornia crassipes and Oryza.sativa L. as repaired plants. Reasonable application of N and K fertilizations can strengthen plants' repairing ability. The scientific method of N and K fertilizations' application can decrease rice consumption risk of growing in the farmland by cesium and uranium contamination. This study has guiding significance for phytoremediation and agricultural production in the polluted farmland by nuclides.