伊维菌素在环境中的降解及其对七种水生生物的急性毒性研究

伊维菌素作为一种高效的抗寄生虫兽药,在畜禽业有着广泛的应用。但药物随着畜禽动物的代谢产物的排放而进入自然生态系统也成为逐渐显现的环境问题。由于药物具有在自然环境中难以快速降解和对水生枝角类高毒性的特点,因此流入天然水体的伊维菌素存在着影响水生态平衡的风险。为了比较全面评估药物对水生动物潜在的毒害作用,研究模拟天然河道环境,对药物在底质中的降解速率进行了测定,并选取7种占据不同生态位的水生生物作为试验对象,通过关于急性毒性的国家标准试验方法来初步评价药物对水生态系统的风险。结果显示伊维菌素在自然水体中降解缓慢,在泥水混合25℃恒温条件下,70d的降解率仅为28.3%。急性毒性试验结果显示伊维菌素对发光细菌(Photobacterium)并不表现出毒性,对淡水小球藻(Chlorella vulgaris)的96h EC50=19.80 mg/L,属中毒;而对其他实验生物则表现出了较高的毒性,伊维菌素对斑马鱼(Brachydanio rerio)、食蚊鱼(Gambusia affinis)和鲫鱼鱼苗(Carassius carassius)的96h LC50分别为40.48、34.81和13.79μg/L,对罗氏沼虾(Macrobrachium rosenbergii)的96h LC50=7.87μg/L,对大型溞(Daphniamagna)的24h LC50=4.81 ng/L,均属极高毒。因此残留在天然水体的伊维菌素对水生态中的生物有较大影响,对含伊维菌素的废弃物排放进行监控和科学管理非常必要。

RESEARCH ON THE DEGRADATION OF IVERMECTIN AND ITS ACUTE TOXICITY TO SEVEN AQUATIC ORGANISMS

Ivermectin(IVM) is a widely applied veterinary pharmaceutical which is used in large amount to treat livestock.It has been a potential environmental problem,that the drug often appears intact in the metabolite of livestock,and its transport from soil to surface water via runoff.In natural environment,dissipation is relatively slow,and the residues can cause mortality in a diverse range of invertebrates.So ivermectin may destroy the aquatic ecosystems.To evaluate the potential toxicity of ivermectin to aquatic organisms,we simulated a natural riverway environment when monitoring the degradation speed of it,and then chose seven aquatic organisms which take up different ecological riche to test acute toxicity by national standard metords.The results displayed that the degradation of Ivermectin(IVM) in water environment was slow,and the degradation rate of IVM in sediment was only 28.3% of 70 days’ experiment under 25℃.The results showed no obviously toxicity to Photobacterium phosphoreum and the 96h EC50 to Chlorella vulgaris was 19.80 mg/L,it did not exhibit high toxicity.But the toxicity of IVM to Brachydanio rerio,Gambusia affinis,Carassius auratus,Macrobrachium rosenbergii and Daphnia magna were relatively higher,and date was 40.48 μg/L(96h LC50),34.81 μg/L(96h LC50),13.79 μg/L(96h LC50),7.87 μg/L(96h LC50) and 4.81 ng/L(24h LC50) respectively.IVM would influence the aqua-biology obviously when the drug residue appeared in water environment,so it is necessary to learn more on ivermectin.