酰胺类除草剂对铜绿微囊藻的生长影响及氧化损伤效应

酰胺类除草剂的广泛使用对水生生态环境构成了潜在风险。为探究其对藻类的毒性作用,以铜绿微囊藻为对象,分别从藻类生长和氧化损伤效应角度探讨了甲草胺、乙草胺和丁草胺对铜绿微囊藻的毒性影响。实验结果显示,酰胺类除草剂对藻类的影响存在明显的滞后效应和剂量–效应关系,低浓度暴露组刺激藻类增长,高浓度表现为抑制作用;3种酰胺类除草剂增加了铜绿微囊藻的氧化压力,并随着暴露时间的延长和浓度的增加而增强。其中,藻体内过氧化脂质降解产物丙二醛(MDA)含量明显增加,同时超氧化物歧化酶(SOD)和过氧化物酶(POD)活性也显著增强。经96 h暴露后,甲草胺(32.0 mg·L~(-1))、乙草胺(32.0 mg·L~(-1))和丁草胺(15.0 mg·L~(-1))暴露溶液中相对MDA含量分别为138%、204%和154%,相对SOD活性分别为116%、87%和115%,相对POD活性分别475%、278%和627%。结合生物量及氧化损伤效应实验结果可知,3种除草剂对铜绿微囊藻的毒性大小顺序为丁草胺乙草胺甲草胺。

Effects of Acetanilide Herbicides on Growth and Oxidative Damage of Microcystis aeruginosa

The widespread use of acetanilide herbicides causes potential risks to aquatic ecological environment. In order to reveal their toxic effect on algae, we used Microcystis aeruginosa as the model organism, the impacts on biomass and oxidative damage of alachlor, acetochlor and butachlor to M. aeruginosa were investigated. The results showed an obvious lag effect and dose-response relationship. Lower concentrations of herbicides stimulated the growth of algae, but higher concentrations inhibited the growth. The oxidative pressure on M. aeruginosa increased with the extension of exposure time and the increasing concentrations of the three acetanilide herbicides. Levels of malondialdehyde (MDA) which is a lipid peroxide degradation product, were markedly increased, meanwhile, the activities of superoxide dismutase (SOD) and peroxidase (POD) were also significantly increased. After 96 h exposure, the relative MDA contents in alachlor (32.0 mg·L-1), acetochlor (32.0 mg·L-1) and butachlor (15.0 mg·L-1) exposure solution were 138%, 204% and 154%, the relative SOD activities were 116%, 87% and 115%, the relative POD activities were 475%, 278% and 627%, respectively. Combined the results of biomass and oxidative damage, the order of toxicity to the M. aeruginosa of the three acetanilide herbicides was butachlor > acetochlor > alachlor.