Physiological Mechanism And Endurance For Cadmium And Uranium Toxicity Tolerance In Phragmites Communis

With the rapid development of industry and agriculture,chemical pollutants release into the ecosystem constantly,Industrial and agricultural production and human health face serious challenges called "combined pollution".According to the types of pollutants,compound pollution can be divided into organic compound pollution,inorganic compound pollution and organic-inorganic compound pollution.The compound pollution between heavy metals is the focus of the current research on inorganic compound pollution.Among them,the situation of radioactive heavy metal uranium pollution is very serious,uranium is easily absorbed and accumulated by plants and accumulates in the topsoil,and irarely migrates,thus posing a threat to human health and safety.The experiment was conducted through hydroponics,This experiment adopts a two-factor and five-level orthogonal design scheme(The cadmium concentration level is(0?1?3?5mg/L),The uranium concentration level is(0?0.1?1?5?10mg/L)),the no uranium-cadmium elements as blank control.Determination of physiological Indices,and bioaccumulation of Uranium elements in roots,stems and leaves of Phragmites australis.The results showed that under U10+Cd5 stress,Phragmites australis plant height and root length are lower than the blank control,and have a significant inhibitory effect on growth.The photosynthetic pigment content of Phragmites australis leaves indicates a tendency of rise first and then decrease with the increase of single uranium concentration,and peak at U0.1;as the concentration of cadmium increasing,it shows a gradual decline tendency.The results showed a largest decrease in chlorophyll b,it become most sensitive to changes in uranium-cadmium stress.The MDA content gradually increased with uranium concentrations increasing under the uranium-cadmium combined pollution.Proline content and soluble protein content increase first and then decrease with the increase of uranium concentration under uranium-cadmium combined pollution.Under the uranium-cadmium combined pollution,With the uranium increasing concentrations,the activity of POD and GR in the Phragmites australis increase first and then decrease.The activity of SOD and CAT enzymes in Phragmites australis showe a trend of increasing with increasing concentrations.The bioaccumulation of uranium in Phragmites australis shows that the underground is above the ground.Phragmites australis can studied as a potential uranium enriche plant because it have a good enrichment effect on uranium under single uranium stress and uranium-cadmium combined pollution.Under single uranium stress,the maximum enrichment of uranium by Phragmites australis reached 768.77mg/kg peak at U10(17#);Under the uranium-cadmium combined pollution,The maximum absorption of uranium by Phragmites australis reached 772.48mg/kg peak at U10+Cd5(20#),The adsorption effect indicate that the concentration of cadmium in this experiment can promote the enrichment of uranium in Phragmites australis.Under the combined stress of uranium and cadmium,Phragmites australis BCF reach 308.7 peak at U0.1+Cd5.The transfer factor(TF)is less than 1,reach 0.54 peak at U0.1+Cd5.It is known that the transfer coefficient of uranium in Phragmites australis under uranium-cadmium combined pollution.When the uranium concentration is stable,with the increase of single cadmium concentration,Phragmites australis enrichment coefficient shows a small upward trend.By SEM-EDS spectroscopy,the relative content of uranium in Phragmites communis leaves is 2.18%,the relative content of cadmium is 1.04%.