氯霉素对大型溞的急性和慢性毒性效应研究

氯霉素是一种具有广谱杀菌作用的抗生素,曾在水产养殖中广泛使用,虽然目前已被列入我国渔药禁用清单,但在水环境中仍被大量检出。为探究氯霉素对水生生物的毒性作用,选择大型溞(Daphnia magna)作为受试生物,研究氯霉素对其急性毒性和慢性毒性效应,同时建立了氯霉素的高效液相色谱(HPLC)分析方法,通过实测浓度分析确保实验过程中氯霉素浓度保持在可接受范围内。结果表明:氯霉素对大型溞的48 h半数抑制浓度(EC50)为129.5 mg·L~(-1),95%置信区间为124.4!150.9mg·L~(-1),对溞类的急性毒性为低毒;长期暴露能抑制大型溞的产溞数量,以繁殖量为毒性指标,21 d无可观察效应浓度(NOEC)为1.25 mg·L~(-1),最低可观测效应浓度(LOEC)为2.50 mg·L~(-1);各暴露组实测浓度范围在配制浓度的80%～110%,保证了实验的有效性。同时,利用实验获得的急慢性毒性数据,计算氯霉素对大型溞的急慢性毒性比(ACR),发现利用慢性毒性求得的ACR值比利用急性毒性EC10求得的ACR值更接近推荐值。研究表明氯霉素对大型溞的急性毒性低,但具有慢性毒性效应,其环境风险不容忽视。

Acute and Chronic Toxicity of Chloramphenicol to Daphnia magna

Chloramphenicol is a broad-spectrum antibiotic, which has been widely used in aquacultures. Although it has been excluded from the list of fish drugs in China, it is still detected frequently and largely in water bodies. In order to explore its toxic effect on aquatic environment, Daphnia magna was selected as a model test organism. At the same time, a high performance liquid chromatography (HPLC) method for the determination of chloramphenicol was established to ensure that its actual concentration in the experimental system was within the acceptable range. The results showed that chloramphenicol had low acute toxicity against Daphnia magna, and the 48 h-EC₅₀ was 129.5 mg?L^-1 (124.4-150.9 mg?L^-1); the long-term exposure to chloramphenicol could affect the number of total offspring per female; the 21 d no observed effect concentration (NOEC) was 1.25 mg?L^-1, and the lowest observed effect concentration (LOEC) was 2.50 mg?L^-1 on the basis of breeding amounts; the measured concentrations of each test group ranged from 80% to 110% of the nominal values, which ensured the validity of the data. The acute and chronic ratio (ACR) of chloramphenicol to Daphnia magna was calculated by using the acute and chronic toxicity data obtained from the tests, and the data showed that the value of ACR obtained from the chronic toxicity test was closer to the recommended value than those from the acute toxicity test. The study demonstrated that although chloramphenicol had low acute toxicity to Daphnia magna, it could exert chronic toxicity effects and potential environmental risk.