Influence Of Temperature, Salinity On Toxicity Of Two Chiral Pyrethroids In Zebrafish Embryo

Climate change has already impacted on every aspect of human’s production and life, however, it also plays important roles in the environmental fate and toxicity of contaminants. Climate change will influence the environmental distribution and toxicity of chemical contaminants by altering environmental factors, such as temperature, salinity, ions concentration and so on. Pesticide is a kind of chemical pollutants widely distributed in water and sediment, moreover, about 40% of pesticides used in China have chiral structure. Their aquatic toxicity depends on the absorption, accumulation, metabolism and enantioselectivity in these processes. However, up to now, most of the aquatic toxicity assessments of pesticides had been conducted under the best conditions, and no systematic or in-depth studies under environmental stress conditions has been applied, especially the effects of variation of environmental factors in the enantioselective toxicity.Here, we focused on the two key factors of aquatic environment under the background of climate change: temperature and salinity. Two types of pyrethroids: type I pyrethroid-bifenthrin and type II pyrethroid-lambda cyhalothrin were used as target compounds, zebrafish embryo was used as a model organism, the chacisteristics of enantioselectivity in bioaccumulation and aquatic toxicity of chiral pesticides and the further mechanism were studied.The results indicated that the developmental toxicity and acute toxicity of cis-BF and(±)-LCT both enhanced with increasing temperature(20°C,25°C and 30°C) of exposure solution. The analysis of the enantioselective toxicities showed that the toxic effects were mainly from the enantiomers of 1R-cis-BF and(+)-LCT. The developmental toxicity and acute toxicity of cis-BF were also enhanced significantly with increasing salinity(0‰,5‰,10‰ and 15‰) of exposure solution. By analysing the related gene expressions of metabolism and thyroid, we found that the increasing of temperature or salinity could enhance the effect of BF or LCT on related gene expressions, then disturbed the normal physiological function of metabolism and thyroid, and increased the toxicity of BF or LCT in zebrafish embryos. Base on these results, we speculated that the influence of the temperature had a significant effect on the toxicity of BF, but lower effect on the toxicity of LCT. High salinity increased the toxicity of BF, and a synergistic effect was found. Additionally, temperature showed no significant effects on accumulation of BF and LCT in zebrafish embryos, however, higher salinity increased the accumulation of BF in zebrafish embryos.