Study On Resistance Physiology Of Phragmites Australis Seedlings To The Livestock Wastewater Containing Copper

Environment pollution of poultry and livestock breeding had become increasingly serious in china.With using all of feed additives,Copper had become another major source of pollution about poultry and livestock breeding.Solving the heavy metals pollution problem in livestock and poultry breeding had been imperative.However,using artificial wetland system of phragmites australis to clear the livestock wastewater had a wider application.The different growing of phragmites australis had different tolerance for different pollutants.The purification effect of phragmites australis wetland was relative with its direct impact on the resistance for pollutants.Therefore,the study on endurance degree and resistance physiology of phragmites australis seedlings in artificial wetland system had important theoretical and practical significance.In this test,we analyzed the quality of livestock wastewater,simulated the pollution of Cu²⁺ and eutrophication in livestock wastewater and studied resistance physiology of phragmites australis seedlings.Then,we could understand the activity mechanism of phragmites australis seedlings under stress of Cu²⁺ and eutrophication in livestock wastewater.The results were as follows:(1) COD^Cr,NH₃-N,TP were major pollutants in livestock wastewater.Because of using various feed additives,Mn,Cu,Cr,Fe,Ni,Zn,and other heavy metals had emerged in livestock wastewater,and Cu was the main heavy metal pollutants.(2) Phragmites australis seedlings had a stronger tolerance for Cu.With the time and intensity of stress increasing,phragmites australis seedlings started their own defense system to resist Cu injuries.Such as SOD,CAT,POD activity enhanced,proline,MDA accumulated and so on.Low concentration of Cu²⁺(＜2.5mg·L^-1) would not cause stress for phragmites australis seedlings.High concentration of Cu²⁺(2.5～25mg·L^-1) would produce a certain damage to phragmites australis seedlings.When the concentration of Cu²⁺ was between 25 and 200mg·L^-1,the normal defense system of phragmites australis seedlings was destroyed.The lethal concentration of phragmites australis seedlings for Cu²⁺ stress was 300 mg·L^-1,when the lethal time was two days.(3) Phragmites australis seedlings showed strong resistance for eutrophication pollution of livestock wastewater without Cu²⁺.Phragmites australis seedlings grown normally by increasing the content of MDA and proline,intensifying the leakage of cell membrane lipid,and enhancing the POD,SOD,CAT activity.Then,chlorophyll content of phragmites australis seedlings decreased gradually. (4) Phragmites australis seedlings could grow normally under the stress of low concentration livestock wastewater which the Cu²⁺ content was 2.5mg·L^-1.But when the content increased 25mg·L^-1 even 100mg·L^-1,phragmites australis seedlings would be damaged a certain.They withstood the injuries which livestock wastewater caused by accumulating proline and MDA,enhancing SOD,POD activity.(5) The livestock wastewater without pre-treatment had many eutrophication pollutants.It would cause greater harm for phragmites australis seedlings.Phragmites australis seedlings would become yellow and wilt after three days.Then,they died after 16 days.(6) Phragmites australis wetland system could be applied to treatment wastewater which the content of Cu²⁺ was less than 25mg·L^-1.It also could be applied to treatment livestock wastewater containing low content of Cu²⁺.But,it could not be directly applied to treatment livestock wastewater without any pre-treatment.