Study On The Root Environment Effect Of Pb And Cd Stress Of Suaeda Heteroptera

With the development of China's coastal economy,the environmental quality of coastal waters has declined sharply,and the pollution of heavy metals in coastal wetlands has become increasingly serious.Heavy metals are accumulative pollutants,which bring ecological threats.It has become an urgent environmental problem in human society.Suaeda heteroptera as the research object under Pb and Cd stress through a hierarchical pot experiment,the physical and chemical properties such as the total nitrogen,total phosphorus and pH in different soil layers and different time,was determined.And soil dehydrogenase,catalase,urease and alkaline phosphatase activities were analyzed,The contents,migration and transformation of total metal,exchangeable state,carbonate bound state,Fe-Mn oxides state,organic content sulfide bound state and residual state in different time and root layers were discussed.The main conclusions were as follows:1.In the microenvironment of Suaeda heteroptera,the total nitrogen content increased,the total phosphorus content decreased,the acid environment of the soil was improved,and the difference between the upper and bottom layers of the soil root environment was not significant.2.The activity of dehydrogenase in lower Pb-contaminated soil was higher in the middle layer of root,the activity of catalase was higher in the bottom layer,and the activity of urease and alkaline phosphatase were higher in the upper and middle layers.The soil dehydrogenase activity in the low concentration Cd contaminated soil was higher than that in the bottom layer.Catalase activity was higher in the root layer,urease activity was higher in the root layer,and alkaline phosphatase activity was higher in the root layer.3.The growth of Suaeda heteroptera reduced the content of Pb and Cd soil,and in the root the organic and sulfide-bound Pb in the bottom layer was transformed into exchangeable state,carbonate-bound state and Fe-Mn oxide bound Pb,the residual state Pb in the bottom layer was reduced to maintain relative stability.In each root layer,the organic and sulfide-bound state and residual state Cd were transformed to exchangeable state and carbonate bound state Cd.The research in this paper provides new ideas and approaches for the remediation and treatment of heavy metal pollution in tidal flat wetlands in China.