摘要:
为评价两种常用除草剂草甘膦和精喹禾灵对土壤动物的影响,以赤子爱胜蚓(Eisenia fetida)为受试生物,采用滤纸接触法和人工土壤法测定了两种除草剂的急性毒性效应。并通过人工土壤染毒法研究了两种除草剂对蚯蚓体内超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、过氧化物酶(POD)活性和丙二醛(MDA)含量的影响。结果表明,滤纸法染毒48 h,草甘膦和精喹禾灵对蚯蚓为低毒级,其LC50值分别为546.4和638.7 μg·cm-2;人工土壤法染毒14 d,草甘膦和精喹禾灵对蚯蚓的LC50值分别为321.4和392.3 mg·kg-1,属低毒级。氧化胁迫试验结果表明,较低浓度草甘膦(≤ 4 mg·kg-1)和精喹禾灵(≤ 10 mg·kg-1)对蚯蚓体内抗氧化酶活性影响不显著,而40和80 mg·kg-1草甘膦在暴露7 d内对SOD、CAT和POD活性影响显著,表现为SOD活性显著提高,CAT和POD活性分别呈现降低-提高和提高-降低的变化趋势。暴露7 d内,100 mg·kg-1精喹禾灵对蚯蚓SOD活性表现为先刺激后抑制的变化趋势,CAT和POD活性显著提高。和对照相比,草甘膦污染土壤中蚯蚓体内MDA含量变化不显著,而高浓度精喹禾灵(100 mg·kg-1)污染土壤中,第7和14天时蚯蚓体内MDA含量显著提高。暴露14 d后,草甘膦和精喹禾灵对蚯蚓的氧化胁迫基本消失,说明供试浓度范围内草甘膦和精喹禾灵不会对蚯蚓造成严重的氧化损伤。与急性毒性结果相比,氧化胁迫效应更为敏感,可作为该两种除草剂对土壤生态影响早期预警中的生物标志物。
Abstract:
To evaluate the effects of two kinds of common herbicides, glyphosate and quizalofop-p-ethyl,on soil invertebrates, their acute toxic effects to earthworms (Eisenia fetida) were determined by using filter paper contact test and artificial soil test. The effects of these two herbicides on superoxidedismutase (SOD), catalase (CAT), peroxidase (POD), and malondialdehyde(MDA) in earthworms were also studied by artificial soil method. The acute test results showed that glyphosate and quizalofop-p-ethyl were low toxic to the earthworms, with the LC50 values of 546.4 and 638.7 μg·cm-2(48 h) for filter paper contact test and 321.4 and 392.3 mg·kg-1(14 d) for artificial soil test, respectively. The results of oxidative stress indicated that low doses of glyphosate(≤ 4 mg·kg-1) and quizalofop-p-ethyl (≤ 10 mg·kg-1) could not induce significant changes of antioxidant enzymes activities in the earthworms. Under the stress of 40 and 80 mg·kg-1 glyphosate, the activities of SOD were significantly increased, and the changes of decrease-increase and increase-decrease were observed in CAT and POD activities during seven days exposure. The activity of SOD was promoted and then inhibited significantly at 100 mg·kg-1 of quizalofop-pethyl, meanwhile the CAT and POD activities were promoted significantly in seven days exposure. The MDA content did not change obviously in the earthworms exposed to glyphosate and quizalofop-p-ethyl at different doses except that it increased significantly at the highest dose of 100 mg·kg-1 for quizalofop-p-ethyl on day of 7 and 14. After 14 days exposure, the oxidative stress of these two herbicides on the earthworms was almost disappeared, which indicated glyphosate and quizalofop-p-ethyl could not induce serious oxidative damage to the earthworms within the tested concentrations. Compared with the results of acute toxicity, the oxidative stress is more sensitive to investigate the effects of the two herbcides on soil ecology, and can be used as biomarkersfor soil ecological early warning.
点击查看大图
下载:
