The Effect Of Antimony On The Toxicity Of Rice Roots

Antimony was a non-essential element in human body and plant.It was a potential global pollutant with potential toxicity,carcinogenicity and long-distance transportation.Antimony industry has developed rapidly in recent years,and pollution was more and more serious.However,compared with other heavy metals,there is short of research of the ecological toxicity of Sb,and our country promulgated The Soil Environmental Quality Standards,without the specific threshold of Sb.The purpose of the study was to study how rice ingest antimony from the environment,the phenomena were produced in the process of ingestion and the reasons for the differences in uptake.In the present study,the toxicity of antimonite and antimonate on the selected 44 varieties of rice was studied by their relative root elongations,and two varieties of rice sensitive and tolerant to antimonite and antimonate were selected to explore the mechanism of Sb toxicity.Two forms the toxicity mechanism of the effect of potassium,sodium,calcium,magnesium and pH on toxicity of Sb.The mechanism of the effect of adsorption and transformation of Sb in rice.Results were as follows:（1）The results showed that the toxicity of Sb（III）to rice root elongation was significantly greater than that of Sb（V）.In the 44 kinds of rice,the value of EC₅₀,Sb（III）was in the range of 0.82 to 100.24 mg·L^-1,while,the value of EC₅₀,Sb（V）was in the range of 13.34 to 766.78 mg·L^-1.Yangjing 687 was more sensitive to Sb（III）with an EC₅₀ of 0.82 mg·L^-1,and Xuhan 1 was more obtuse to Sb（III）and the EC₅₀value was 100.27 mg·L^-1,the difference between the tolerant and sensitive rice being122 folds.Shenliangyou 5183 was more sensitive to Sb（V）and the EC₅₀ value was13.34 mg·L^-1,and Zixiangmi was more obtuse to Sb（V）and the EC₅₀ value was776.78 mg·L^-1,the difference between the tolerant and sensitive rice being 58 folds.The SOD and MDA contents of the 4 kinds of rice were measured,and it was found that the SOD enzyme activity and MDA contents were higher in the roots of rice plants exposed to Sb,which indicated that the roots were poisoned by Sb,and the mechanism of toxicity might be oxidative stress.The results suggested that the rice plant might be subdued by Sb（III）and Sb（V）,and that the inhibitory effect of Sb（III）was greater than that of Sb（V）.（2）Based on the hydroponic experiment,combined with the traditional chemical digestion and atomic fluorescence spectrophotometry,investigated the reaction of rice roots under the stress of Ca²⁺,Mg²⁺,Na⁺,K⁺ions and pH under Sb treatment,the absorption of rice to Sb and the mechanism of the effect of cation on the toxicity of Sb.The effect of K⁺,Na⁺,Ca²⁺,Mg²⁺and pH on Sb（V）toxicity was greater than that on Sb（III）,but this effect was not related to the tolerance of Sb on rice.The toxicity of Sb（V）on Shenliangyou 5183 and Zixiangmi reduced with the decrease of the concentration of K⁺.The toxicity of Sb（III）the Yangjing 687,Xuhan 1 increased with raise of the concentration of K⁺.The absorption of rice for Sb trends and relative root elongation were different.The toxicity of Sb（III）decreased with the increase of Na⁺concentration,while the absorption of Sb（III）increased.The toxic effects of Na⁺on Sb（V）and Sb（III）were independent of rice varieties,which were to alleviate the toxicity of Sb（V）at a certain concentration.Ca²⁺promotes Sb（III）toxicity and inhibits Sb（V）toxicity.The toxicity of Mg²⁺on Sb（V）was greater than that on Sb（III）,and the influence trend of Mg²⁺on different rice was the same,but there were still differences among different varieties of rice.The absorptive Sb（III）of the sensitive variety Yangjing 687 was greater than Xuhan1.PH influence on Sb（V）toxicity than Sb（III）,to the influence of different rice variety trend was the same but different size,that was to say.The influence of pH on Sb toxicity was related with tolerance of rice and the morphology of Sb,sensitive rice was more obvious.（3）Based on hydroponic experiment,combined with traditional digestion method,atomic fluorescence spectrophotometry and atomic absorption spectrophotometry.Analysed the adsorption change of antimony and arsenic on rice to research the mechanism of rice adsorbed Sb and As under the treatment of antimony and arsenic.The amount of ferromanganese film formed on the surface of Zixiangmi was more than that on Yangjing 687,and the amount of Sb absorbed by Zixiangmi was also more than that on Yangjing 687.Iron and manganese on Sb（V）and Sb（III）the absorption rules were same on Yangjing 687.While the ratio of iron and manganese was 1:0 and 1:1 trained Yangjing 687,the former rice took in more Sb（III）and adsorbed more.Under different treatments,the adsorption of Yangjing 687 and Zixiangmi adsorbed more As（V）than As（III）,but the assimilation was similar.Yangjing 687 was filtered Sb as sensitive varieties,while Sb and As belonging to the cognate elements.There were too many difference,but from the results,it seems that the response of As toxicity on Yangjing 687 was faster than that on Zixiangmi.Overall,Sb processing rice root elongation was significantly suppressed,under different varieties of rice to Sb significant differences toxicity response and uptake also have very lagger difference,Ca²⁺,Mg ²⁺,Na⁺,K⁺and pH on Sb toxicity,and the absorption of rice for Sb has a great influence by iron and manganese membrane which can inhibit the absorption of Sb on rice.