Toxic Effects Of Three Imidazolium-based Ionic Liquids With Different Anions On Vicia Faba Seedlings

ILs usually consist of large asymmetric organic cations and small inorganic or organic anions,Due to the numerous unique physicochemical properties,such as low melting points,good solubility,nonflammability,thermostabilization,ionic liquids have been widely used in the field of electrochemistry,organic synthesis,analytical chemistry,catalysis,and separation processes.However,with the wide application in various fields,ionic liquids may enter the water and soil environment through multiple ways,such as accidental spills or industrial effluents,irrigation or groundwater,bringing potential risks to the environment and the organisms.The previous toxicity studies focus primarily on the toxic effects on plants of ILs in nutrient solutions.In the real environment,plants are mainly grown in soil,so studying the toxicity of ionic liquids to the plant in soil is vitally significant.The study examined the ecological toxicity of three different anions of imidazoles ionic liquids to the Vicia faba seedlings in soil.At day 10 of cultivating,shoot length,root length and dry weight were measured to Vicia faba seedlings at concentrations of 0,500,1000,1500,2000 and 2500mg/kg in soil.The Vicia faba seedlings were cultivated for 10 days at concentrations of 0,1,10,100 and 500mg/kg,the following indicaters were measured: residual concentrations,hill reaction,reaction oxygen apecies?ROS?,antioxidant enzymes?superoxide dismutase?SOD?,catalase?CAT?,ascorbate peroxidase?APX?,glutathione peroxidase?GPX??and oxidative damage?lipid damage,protein damage,DNA damage?.The present study provides a theoretical basis for the comprehensive assessment of the toxicity of ILs.The main conclusions of the present study were as follows:?1?In the present study,the extraction recoveries of [C₆mim]Br,[C₆mim]NO₃,[C₆mim]BF₄ from the soil were 73.3%-88.5%,72.8%-88.3% and 78.0%-88.7%.On the 10 th day,[C₆mim]Br concentrations in different treatments changed 5.6%,4.4%,4.8% and 1.8% compared to that on day 0;[C₆mim]NO₃ concentrations in different treatments changed 4.3%,4.0%,5.7% and 9.8% compared to that on day 0;[C₆mim]BF₄ concentrations in different treatments changed 3.2%,7.4%,2.8% and 3.4% compared to that on day 0.The concentrations of ILs in soil kept stable during the exposure period,and the range of concentrations measured across the different ILs treatments was no more than 10%.?2?From the point of growth index,the growth of Vicia faba seedlings was significantly inhibited after exposure to the three ILs of [C₆mim]Br,[C₆mim]NO₃,[C₆mim]BF₄.Moreover,the inhibitory effect was enhanced with increasing concentrations of the three ILs.For shoot length,root length and dry weight,the EC50 values of [C₆mim]BF₄ were significantly lower than those of [C₆mim]Br and [C₆mim]NO₃.?3?During the exposure period of [C₆mim]Br,[C₆mim]NO₃ and [C₆mim]BF₄,almost no dark blue formazan compound or brown polymerization product was found at low concentrations?1 and 10 mg/kg?.Compared to the control group,a significant amount of dark blue insoluble formazan compound and brown polymerization product were found at 100mg/kg.?4?In the present study,no significant differences in SOD,CAT,APX and GPX activities were observed during the exposure period of [C₆mim]Br,[C₆mim]NO₃ and [C₆mim]BF₄ at low concentrations?1 and 10 mg/kg?.SOD,APX and GPX activity were significantly enhanced at 100mg/kg.In the four antioxidant enzymes,SSOD,APX and GPX were more sensitive than CAT.The ASA and GSH contents were significantly elevated at 500mg/kg and 100mg/kg,respectively.GSH was sensitive than ASA.?5?During the exposure period of [C₆mim]Br,[C₆mim]NO₃ and [C₆mim]BF₄,no significant damage to lipid,protein and DNA were observed at 1 mg/kg.When concentrations were equal to or higher than 10 mg/kg,MDA content was obviously increased when compared to the controls.When [C₆mim]BF₄ was higher than 10 mg/kg,and concentrations of other two ionic liquids were higher than 100 mg/kg,PCO content and OTM values were obviously increased when compared to the controls.