摘要:
地表水中抗生素与农药的混合暴露及其潜在生态与健康风险受到广泛关注。然而,目前关于抗生素与农药混合毒性研究大多仅考虑急性毒性,缺乏其长期毒性相互作用的研究。以较为广泛使用的2种抗生素土霉素(OXY)、环丙沙星(CIP)和1种三唑类杀菌剂农药戊唑醇(TCZ)及其二元混合物为研究对象,以生态系统中初级生产者绿藻(羊角月牙藻)为受试生物,研究目标混合物在暴露时间为96、120、144和168 h的长期毒性相互作用。结果表明,单一物质及其混合物随暴露时间延长而毒性增大;同一暴露时间点的单一污染物毒性大小顺序为OXY > TCZ > CIP;混合物毒性相互作用与浓度、混合物组分和暴露时间三者密切相关;混合体系的拮抗作用均出现在高浓度区域,而中、低浓度区域呈协同作用或加和作用;OXY-CIP与CIP-TCZ混合体系的协同作用随着暴露时间延长而协同作用逐渐增大。研究结果对水环境中抗生素与农药复合污染生态风险评估具有重要的现实意义。
Abstract:
Co-exposure of antibiotics and pesticides in surface water and their potential ecological and human health risks have attracted wide attention. Currently, most studies focus on the combined toxicity of antibiotics and pesticides at short-term exposure, however, the toxic interactions of long-term effects are still lack. In this study, the toxicities of two antibiotics (oxytetracycline (OXY) and ciprofloxacin (CIP)) and one triazole fungicide pesticide (tebuconazole (TCZ)) as well as their binary mixtures were studied. The green algae (Selenastrum capricornutum), one of the primary producers in the aquatic ecosystem, was used as the test organism. The long-term toxicities of the mixtures were determined at the exposure time of 96, 120, 144, and 168 h. The results showed that the toxicities of the single pollutants and their mixtures increased with the prolongation of exposure time. The order of toxicity was OXY > TCZ > CIP. The toxic interactions of the mixture depended on the concentrations of components and exposure times. The antagonistic effects of the mixture toxicities occurred at high concentrations, while the synergistic or additive effects presented at medium or low concentrations. The strength of synergy in the mixture systems of OXY-CIP and CIP-TCZ increased with the prolongation of exposure time. This study has a great realistic significance to the ecological risk assessment of mixtures of antibiotics and pesticides in water environment.
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