Enantioselective behavior of malathion enantiomers in toxicity to beneficial organisms and their dissipation in vegetables and crops

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• 作者：Mingjing Sun ; Donghui Liu ; Ziheng Dang ; Ranhong Li ; Zhiqiang Zhou ; Peng Wang
• 关键词：Acute toxicity ; Beneficial organisms ; Enantioselective degradation ; Malathion enantiomers
• 刊名：Journal of Hazardous Materials
• 出版年：2012
• 出版时间：30 October, 2012
• 年：2012
• 卷：237-238
• 期：Complete
• 页码：140-146
• 全文大小：618 K

文摘

The dissipation behavior of the two enantiomers of malathion was elucidated in five plant species using enantioselective high performance liquid chromatography (HPLC), and the acute toxicity of the individual enantiomers toward earthworms and honeybees was studied. The calculated LC₅₀ values of the R-, S- and rac-malathion to earthworms were 0.3869, 25.17, and 19.19 ¦Ìg/cm², respectively, while the calculated LC₅₀ values of R-, S- and rac-malathion to bees were 2.15, 36.67, and 7.11 ¦Ìg/mL, respectively. This indicated that the R-enantiomer was more toxic than S-enantiomer. The results of the degradation of racemate in Chinese cabbage and rape showed that the inactive S-(?)-enantiomer degraded faster than the active R-(+)-enantiomer. Inversely, we found a preferential degradation of the R-(+)-enantiomer in sugar beet. However, the degradation of malathion in paddy rice and wheat were nonenantioselectivity. In all plants, malathion was degraded to levels <10 % after 5 days, and the calculated t_? values of the enantiomers ranged from 0.83 to 1.43 days in these five plants. In conclusion, our findings of enantioselectivity in the environmental fate and acute toxicity of the malathion enantiomers may have implications for better environmental and ecological risk assessment for chiral pesticides in general.