氧化石墨烯存在下铜离子对大型溞的毒性研究

Toxicity of Copper Ions on Daphnia magna in the Presence of Graphene Oxide

氧化石墨烯(graphene oxide,GO)作为一种具有独特物理化学性质的新型纳米材料被广泛应用,其进入环境后可能对传统污染物的毒性造成影响。选取大型溞为受试生物,研究了GO的存在对Cu在大型溞体内的富集、毒性和抗氧化系统的影响。结果表明,GO对Cu^(2+)具有良好的吸附效果,大幅降低了试验液中Cu^(2+)浓度。1 mg·L^(-1)和2 mg·L^(-1)GO存在下,大型溞暴露于19.2μg·L^(-1)Cu^(2+)溶液72 h后,体内的金属Cu富集量由360μg·g-1干重分别降低为308μg·g-1和215μg·g-1干重。GO的存在降低了Cu^(2+)对大型溞的毒性,Cu^(2+)对大型溞的72 h-LC50值由19.2μg·L^(-1)升高至56μg·L^(-1)。Cu^(2+)单独作用时,大型溞体内SOD活性和GSH含量表现为先诱导后抑制,而MDA含量逐渐升高;当GO存在时,大型溞体内酶活性的变化趋势与上述现象类似,但含量总体低于Cu^(2+)单独暴露时的活性和含量。研究表明GO的加入减少了大型溞体内Cu的富集量,降低了Cu^(2+)对大型溞的氧化损害,对Cu^(2+)的毒性存在一定的减轻效果。

Graphene oxide（ GO） has been extensively applied as a novel nanomaterial because of its unique physicochemical properties. It may affect the toxicity of traditional pollutants after entering the environment. In this research,Daphnia magna（ D. magna） was selected as a test organism to assay how accumulation of Cu,toxicity and internal antioxidant system in D. magna were affected in the presence of GO. The results show that the adsorption effect of Cu^2＋ on GO was excellent so that Cu^2＋ concentration in test solution was largely reduced. With 1 mg·L^-1and 2 mg·L^-1GO,the accumulation of copper in D. magna decreased from 360 μg·g^-1dry weight to 308 μg·g^-1and 215 μg·g^-1dry weight,respectively,after exposed to 19. 2 μg·L^-1Cu^2＋ solutions for 72 h. The presence of GO reduced the toxicity of Cu^2＋ to D. magna and the 72 h-LC50 value of Cu^2＋ was increased from 19. 2 μg·L^-1to 56 μg·L^-1. When D. magna was exposedto Cu^2＋ alone,the SOD activity and GSH content were first induced and then inhibited,and MDA content increased gradually. Variation trend of antioxidant compounds and enzymes activities in D. magna in the presence of GO was similar to that in the absence of GO with single Cu^2＋ exposure,but the activity / content was lower than that after single Cu^2＋ exposure. It is indicated that addition of GO decreased the accumulation of Cu in D. magna,reduced the oxidative damage of Cu^2＋ to D. magna and showed certain alleviative effect to the toxicity of Cu^2＋ .