氰氟草酯对泽蛙蝌蚪毒性及风险

研究了氰氟草酯(cyhalofop-butyl)对泽蛙(Rana limnocharis)蝌蚪毒性,室内毒性与田间风险的关系。通过监测氰氟草酯在田间的降解规律,解释其对泽蛙蝌蚪的室内外毒性差异。室内急性毒性试验结果表明,氰氟草酯对泽蛙蝌蚪的24h-LC50和48h-LC50分别为0.718 和0.677 mg·L-1,属于高毒级。田间模拟试验结果表明,100 g·L-1氰氟草酯乳油施药剂量为300 g·hm2以下对泽蛙蝌蚪无影响；100 g·L-1氰氟草酯EC施药剂量在1 500 g·hm-2,蝌蚪死亡率为86.7%。降解动态测定结果表明,氰氟草酯在田间条件下降解极快,1 500 g·hm-2处理,田水中氰氟草酯2 h含量为0.112 mg·L-1,远低于理论初始浓度42.9 mg·L-1。因此,虽然氰氟草酯对泽蛙蝌蚪高毒,但在田间对泽蛙急性毒性风险较低。

Toxicity and risk of herbicide cyhalofop-butyl on Rana limnocharis

The relationship between lab acute toxicity and field toxicity of herbicide cyhalofop-butyl on Rana limnocharis tadpole have been studied. The difference between lab toxicity and field toxicity was explained by monitoring the degradation dynamics of cyhalofop\|butyl in field. The acute toxicity test showed that the 24 h-LC50 and 48 h-LC50 of cyhalofop-butyl on Rana limnocharis were 0.718 and 0.677 mg·L-1, respectively, and the toxicity level could be categorized as high toxic. The simulative field trail showed that the death rate of Rana limnocharis tadpole is 86.7% with the dose 1 500 g·hm-2 of cyhalofop-butyl 100EC. The cyhalofop-butyl degraded rapidly in field water .With the dose 1 500 g·hm-2,the water concentration of cyhalofop-butyl was 0.112 mg·L-1, much lower than the concentration of 42.9 mg·L-1 in theory two hours after administration. The results showed that cyhalofop-butyl had low risk to Rana limnocharis though it showed high acute toxicity to Rana limnocharis in lab．