Development Toxicity Of Ion Liquids On Physa Acuta

Ionic liquids(ILs)are room-temperature molten salts which chemically consist only of ions. They possess a series of preponderant properties, such as almost no vapour pressure and nonvolatility, high thermal and non-flammability, and high solvent capacity and chemical stability, which promote them to be used in organic synthesis, catalysis, chemical separation, and electrochemistry in the future. Especially in the recent years, ILs have been promised to be used in environmental protection and the utilization of biotic resources, for example, absorption of harmful gas CO2, and degradation of cellulose from the crop stalks. Furthermore, ILs may reduce the risk of air pollution due to their negligible vapor pressure. Therefore ILs have been claimed to be environmentally benign "green solvent" strongly recommended to be the substitutes for conventional organic solvents by chemists. However, most ILs are hydrosoluble and they may be released to water and cause damage to aquatic organisms during the generation and application. Therefore, ILs may pose environmental risks to aquatic ecosystems, and thus IL-toxicity on aquatic organisms is much concerned in the near years.The imidazolium-based ILs have been not only widely applied in the chemical industry, they also possess the excellent and advantageous properties over the conventional organic solvents. Moreover, they usually have moderate or relatively lower toxicity on organisms. The most important is that the toxic response of organisms to the exposure of imidazolium-ILs is in a remarkable dose-dependent manner according to our previous studies and the result of toxicity-testing can be the representation for the common ILs. Therefore the imidazolium-based IL was adopted in the present study to evaluate their embryonic and post-embryonic developmental toxicities on the snail Physa acuta and to elucidate the biochemical mechanism of IL-toxicity by determining the responses of the antioxidant system and the level of lipid peroxidation in the viscera of Physa acuta exposed to1-octyl-3-methylimidazolium bromide([C8mim] Br)in the present study.The results of embryonic toxicity tests showed that[Csmim]Br inhibited the hatching rate of snail embryos while promote the embryonic death rate. Meanwhile, the results reveal that the stage veliger is more sensitive to[Csmim]Br than the stages of blastula and gastrula, indicating that[Csmim]Br-toxicity is stage-sensitive. Moreover, we also find that the juvenile or adult snail is more resistant to the ionic liquids than snail embryo. In addition, this study also indicates that longer alkyl chains can increase the toxicity of the imidazolium ionic liquids on snails.We also find that[Csmim]Br inhibits the activities of superoxide dismutase and glutathione S-transferase while promotes the activity of catalase and increases glutathione content after96h of exposure. Malondialdehyde levels increase in all treatment groups compared to the control, indicating that[C8mim]Br induce lipid peroxidation. These results suggest that reactive oxygen species and lipid peroxidation may involved in the toxicity mechanism of[Csmim]Br for the snail.Finally, we suggest that P. acuta may be a good model of toxicity tests and a valuable indicator of water pollution according to the results of the present study.