抗生素与杀菌剂顺序暴露对绿藻的联合毒性

本文选取常见的3种抗生素盐酸强力霉素(DOX)、红霉素(ERY)、土霉素(OXY)和3种三唑类杀菌剂腈菌唑(MYC)、丙环唑(PRO)、戊唑醇(TCZ)混合体系为研究对象,以生态系统中初级生产者绿藻(蛋白核小球藻)为受试生物,研究目标污染物顺序暴露的联合毒性.结果表明,6种单一目标污染物对蛋白核小球藻抑制毒性大小为:PRO>DOX>TCZ>ERY>MYC>OXY.抗生素-三唑类杀菌剂混合体系在50%效应浓度(EC₅₀)下同时暴露和顺序暴露的抑制率差异为0.38%~36.76%.DOX与PRO、TCZ、MYC任何一种三唑类杀菌剂顺序暴露于蛋白核小球藻,顺序相反后,对蛋白核小球藻的毒性作用均增强,最大可增强36.82%.在不同浓度与时间的影响下,PRO-DOX和TCZ-DOX顺序暴露毒性高于调整暴露顺序后的DOX-PRO和DOX-TCZ顺序暴露毒性,且浓度越高,抑制率差异越大.在96h~144h暴露时间下,暴露浓度EC₅₀/20的顺序暴露抑制率差异为0.65%~11.57%;暴露浓度EC₅₀的顺序暴露抑制率差异为0.15%~36.93%,顺序暴露的抑制率差异范围随浓度增加变大.在EC₅₀/20~EC₅₀暴露浓度下,暴露时间96h的顺序暴露抑制率差异为0.29%~36.93%,暴露时间144h的顺序暴露抑制率差异为0.215%~30.09%,顺序暴露的抑制率差异范围随时间增加变小.因此,顺序暴露会改变抗生素与三唑类杀菌剂对蛋白核小球藻联合毒性大小,且顺序暴露、暴露时间和暴露浓度是影响毒性作用大小的关键因素.

Combined toxicity of sequential exposure of antibiotics and fungicides on green algae

The mixture systems of three antibiotics (doxycycline hydrochloride (DOX), erythromycin (ERY), oxytetracycline (OXY)) and three triazole fungicides (myclobutanil(MYC), propiconazole (PRO) and tebuconazole (TCZ)) were selected as target pollutants. The primary producer green algae (Chlorella pyrenoidosa) in the ecosystem was used as the test organism to study the combined toxicity of sequential exposure to target contaminants. The results showed that the inhibitory toxicities of six single target pollutants to Chlorella pyrenoidosa were: PRO>DOX>TCZ>ERY>MYC>OXY. The difference of inhibition rates between simultaneous exposure and sequential exposure of antibiotic triazole bactericide mixture system mixed at 50% effect concentration was 0.38%~36.76%. The toxicity to Chlorella pyrenoidosa increased up to 36.82% when DOX, PRO, TCZ, and MYC were exposed to Chlorella pyrenoidosa in the reverse order. Under the influence of different concentrations and time, the sequential exposure toxicities of PRO-DOX and TCZ-DOX were higher than that of DOX-PRO and DOX-TCZ after adjusting the exposure sequence. The higher concentrations the greater difference of inhibition rates. At the exposure time of 96h~144h, the difference of sequential exposure inhibition rates of exposure concentration EC₅₀/20 was 0.65%~11.57%. The difference of sequential exposure inhibition rates of exposure concentration EC₅₀ was 0.15%~36.93%. The range of sequential exposure inhibition rate increased with the increase of concentration. At the exposure concentration EC₅₀/20 to EC₅₀, the difference of sequential exposure inhibition rates of exposure time 96h was 0.29%~36.93%. The difference of sequential exposure inhibition rates of exposure time 144h was 0.215%~30.09%. The range of sequential exposure inhibition rate decreased with the increase of time. Therefore, sequential exposure changed the combined toxicity of antibiotics and triazole fungicides to Chlorella pyrenoidosa. The sequential exposure, exposure time, and exposure concentration were the key factors affecting the toxicity.