The Effects Of Root Iron Plaque On The Absorption Of Roxarsone During Rice Seedling

Arsenic is a highly toxic and carcinogenic non-metallic substance.Since more than half of the world’s population uses rice as main food,the accumulation of arsenic in rice and its health risks to rice consumer have caused worldwide concern.The Roxarsone in the feed additive is discharged into the environment with animal manure,which causes the risk of arsenic exceeding the standard in rice.Therefore,it is necessary to study the absorption of Roxarsone and the toxic effects and pathways of Roxarsone on rice.Then further explore the effect of rice rhizosphere behavior on the control of Roxarsone.Based on these,this study established on a detection method of Roxarsone in rice.Then this report discussed the toxicity and entry channel of Roxarsone to rice.It also discussed the adsorption and control of the iron film on the root surface of Roxarsone.Concluded as follow:（1）In view of the current gap in the detection method of Roxarsone in rice.this study established a method for the determination of Roxarsone in rice roots,stems and leaves by high performance liquid chromatography using solid phase extraction cartridge purification.The method has the advantages of short retention time,good peak shape,no impurity peak interference nearby,high precision,good reproducibility,wide linear range and low detection limit.It provides a reliable basis for the subsequent research on the detection of Roxarsone in rice.（2）This study demonstrates that the EC50 value of Roxarsone in rice is 7.74 mg/L,which is lower than the EC50 value in wheat.It is possible that rice is more sensitive to Roxarsone than wheat.The inhibition of rice seedling growth,chlorophyll and root activity gradually increased as the increase of the concentration of Roxarsone.Rice’s antioxidant system will resist when forced by Roxarsone.However,as the concentration of Roxarsone increases,the rice enzyme activity system gradually loses its resistance.The glycerol-related vector is not the main carrier of Roxarsone into rice root cells.Si（Ⅳ）,P（Ⅴ）and DNP vectors can be the main carriers for Roxarsone entering into rice root cells.（3）The adsorption performance of iron plaque on the root surface of Roxarsone was determined.The adsorption rate was estimated and the adsorption equilibrium time was determined to explore its possible adsorption characteristics and potential adsorption mechanism.The adsorption of Roxarsone on the iron surface of rice roots accords with Pseudo-second-orderkinetic model.The adsorption rate of Roxarsone by iron plaque on the root surface of rice is affected by the chemical interaction between Roxarsone and the functional groups in the iron plaque of rice root surface.The adsorption behavior of Roxarsone on the iron plaque of rice roots is mainly chemical adsorption,and the exchange,transfer or sharing of electrons between the iron plaque of the root surface of the rice and Roxarsone forms a chemical bond.In the process of adsorption of Roxarsone on the iron plaque of rice root surface,the surface of Fe in the iron plaque of Roxarsone was complexed with the surface of the iron plaque on the root surface of the rice.The Roxarsone was adsorbed and stabilized on the iron plaque of the rice root surface.（4）There was a positive correlation between the content of Roxarsone in rice and the concentration of exogenously added Roxarsone.With the increase of Roxarsone in the nutrient solution,the iron plaque on the root surface of rice could adsorb more Roxarsone,Effectively control the migration of Roxarsone into rice,and can significantly enhance the absorption of nutrients in roots,stems and leaves of rice.After entering the rice seedlings,Roxarsone detected the suspected metabolites phenylarsenic（C₆H₅AsO）and dimethylarsenate（C₂H₇ASO）in the roots and stems in addition to the body material of Roxarsone in various parts of rice,due to various parts.Metabolites are low in content and cannot be further qualitatively analyzed by secondary mass spectrometry.