环境相关浓度下的药物对大型蚤的多代慢性毒性

选择无脊椎动物大型蚤(Daphnia Magna)为供试水生生物,以磺胺甲恶唑、氧氟沙星和布洛芬作为目标污染物,在环境相关浓度下,对大型蚤进行6代慢性毒性研究.磺胺甲恶唑在0.8,8.0,80.0μg/L下,对大型蚤生殖和生长指标均没有发现明显的影响.200.0μg/L的氧氟沙星显著降低了F3(孤雌生殖第三代)和F4代的产卵数.900.0μg/L布洛芬明显延长了F3和F4代第一次产卵时间,并显著降低了F3、F4和F5代第一胎产卵数.在6代培养中,复合暴露M1处理(最低浓度药物混合物)没有表现明显效应,M2和M3处理在后面世代中明显延长产卵时间,降低产卵数量.相对于3种药物的单一暴露,复合暴露M2和M3处理增强了对大型蚤产卵时间和产卵数量的影响,提前表现出世代差异.2.0μg/L及20.0μg/L的氧氟沙星和9.0μg/L及90.0μg/L的布洛芬在连续6代的孤雌繁殖中没有发现明显的影响,200.0μg/L的氧氟沙星和900.0μg/L的布洛芬在前几代对大型蚤表现出一定的适应性或耐受性,而在后几代中,大型蚤出现产卵时间延后或产卵数量减少的现象,对大型蚤繁殖的影响表现出浓度依赖性和世代差异性.在目前检测环境浓度(MEC)下,3种药物单一污染和复合污染对大型蚤生态风险较低.

Multigenerational chronic effects of pharmaceuticals on Daphnia magna at environmentally relevant concentrations

Chronic toxicity over six consecutive generations of sulfamethoxazole, ofloxacin and ibuprofen were bioassayed on the cladoceran D. magna at environment related concentrations. Sulfamethoxazole did not exhibit obvious effects on endpoints of reproduction and growth at 0.8,8.0 and 80.0μg/L. Ofloxacin at 200μg/L could cause a significant decrease at the number of first reproduction in F3 (third generation of clone) and F4. For ibuprofen, the age of first reproduction delayed significantly in F3 and F4 and the offspring number decreased obviously in F3, F4 and F5 at 900.0μg/L. Pharmaceutical mixtures did not show obvious effects in M1 treatment (minimum concentration of pharmaceutical mixture), while delayed the age of first reproduction and decreased the number of offspring significantly in subsequent generations in M2 and M3 treatment, respectively. In comparison with single exposure, pharmaceutical mixtures intensified negative effects on the first reproduction time and the first offspring number, and showed generational difference earlier. Ofloxacin at 2.0μg/L and 20.0μg/L level and ibuprofen at 9.0μg/L and 90.0μg/L level did not change life-history of six successive clone generations. Ofloxacin at 200.0μg/L and ibuprofen at 900.0μg/L developed the tolerance or adaption of drug pollution stress at the first several generations in D. magna, while the negative effects occurred with the reproduction time delayed and the offspring number declined in the subsequent generations, which presented concentration dependency and generational difference on D. magna. The results showed that sulfamethoxazole, ibuprofen and ofloxacin (both single and in combination) were at low ecological risk on D. magna at measured environmental concentrations (MEC).