地表水中抗生素复合残留对水生生物的毒性及其生态风险评价

针对上海地区地表水中混合并持久残留的抗生素对水生态的危害,测试了3种主要被使用的抗生素(磺胺甲恶唑,SMZ;土霉素,OTC;氟苯尼考,FF)对4个不同营养级的水生生物代表种(蛋白核小球藻、费氏弧菌、大型蚤和斑马鱼胚胎)的单一毒性和联合毒性,并进一步对生态风险进行评估来探究抗生素对水生态系统的综合作用。研究表明:水生生物对单一抗生素暴露的毒性敏感顺序为:蛋白核小球藻斑马鱼胚胎费氏弧菌大型蚤。用联合指数(CI)来评价抗生素二元混合物之间的相互作用时发现对于不同水生模式生物,抗生素之间的相互作用方式以拮抗作用(CI1)为主。通过与浓度加和(CA)和独立作用(IA)2个传统模型的预测效果比较,发现CI模型能准确预测到抗生素联合毒性偏离相加作用。由于养殖废水中这3种抗生素的含量均远高于其他水体(如黄浦江、长江口、工厂废水),其对不同营养级的水生生物均表现出较高的风险性,需要对养殖废水采取相应的风险削减措施;相比之下,其他水体中抗生素对费氏弧菌、斑马鱼胚胎、大型蚤均表现出低风险,但是对蛋白核小球藻仍具有一定的风险性,需要警惕抗生素对水体初级生产者的风险性。

Toxicity to Aquatic Organisms and Ecological Risk Assessment of Antibiotic Compound Residues in the Surface Water

Three major antibiotics (sulfamethoxazole SMZ, oxytetracycline OTC and florfenicol FF) were used to explore the effects of mixed and persistent antibiotics on aquatic ecology in the Shanghai surface water. The individual and combined toxicities of these antibiotics have been examined in four target organisms (Chlorella pyrenoidosa, Vibrio fischeri, Daphnia magna and zebrafish embryo), which were representative aquatic species at four different trophic levels respectively. Moreover, further ecological risk assessment based on toxicity tests was conducted to explore the comprehensive effect of antibiotics on aquatic ecosystems. The results showed that the order of sensitivity of aquatic organisms to three major antibiotics was as follows: Chlorella pyrenoidosa > zebrafish embryo > Vibrio fischeri >Daphnia magna. The combination index (CI) was used to evaluate interactions between the antibiotic binary mixtures, and it was found that interactions between two antibiotics were mostly antagonistic (CI>1). In addition, compared with classical models of concentration addition and independent action, CI method could accurately predict the non-additive effect of joint toxicity from antibiotics. As the content of three kinds of antibiotics in aquaculture wastewater is much higher than that of other water bodies (Huangpu River, Yangtze River estuary and factory wastewater), it shows high risk for aquatic organisms at different trophic levels, so corresponding risk reduction measures are needed. In contrast, antibiotics in other water bodies show low risk for Vibrio fischeri, Daphnia magna and zebrafish embryo, but still pose a certain risk to Chlorella pyrenoidosa. Therefore, vigilance is needed against antibiotic risk to aquatic primary producers.