聚乳酸微塑料对大型溞的毒性效应

Toxic effects of polylactic acid microplastics to Daphnia magna

为了进一步揭示生物可降解微塑料对水生生物的影响,以大型溞为模式生物,研究了聚乳酸(PLA)微塑料对其急慢性毒性效应.结果表明,PLA对大型溞的半数效应浓度(48h-EC50)为59.43mg/L,95%置信区间为53.55~65.97mg/L.经紫外照射处理的PLA毒性降低.PLA对大型溞的游泳活力和摄食行为有浓度依赖性的抑制作用.与对照组相比,100mg/L的PLA显著抑制了大型溞的心率和胸肢活动率,最大抑制率分别为31.4%和17.7%.经21d长期暴露后,10和40mg/L的PLA均一定程度上抑制了大型溞的生殖及内禀增长率(rm),但其影响并不显著.40mg/L的PLA显著降低了大型溞的存活率(仅为20%).PLA的暴露显著诱导了超氧化歧化酶(SOD)的活性和丙二醛(MDA)的含量,表明大型溞受到氧化胁迫并引起脂质过氧化损伤.PLA在浓度40mg/L时显著抑制了乙酰胆碱酯酶(AChE)的活性,从而引起大型溞神经毒性和运动失调.

In order to further reveal the effects of biodegradable microplastics on aquatic organisms,the acute and chronic toxic effects of polylactic acid(PLA)microplastics on Daphnia magna were studied using Daphnia magna as the model organism.The results showed that the half effect concentration(48h-EC50)of PLA on Daphnia Magna was 59.43mg/L,with a 95%confidence interval of 53.55~65.97mg/L.Additionally,the toxicity of PLA was reduced by ultraviolet irradiation treatment.PLA inhibited the swimming activity and feeding behavior of Daphnia magna in a concentration-dependent manner.Compared with the control group,PLA at 100mg/L significantly inhibited the heart rate and thoracic limb activity of Daphnia magna,with maximum inhibition rates of 31.4%and 17.7%,respectively.After long-term exposure for 21days,both 10 and 40mg/L PLA inhibited the reproduction and intrinsic rate of population growth(rm)of Daphnia magna to some extent,but the effects were not significant.Exposure to PLA at 40mg/L significantly reduced the survival rate of Daphnia magna(only 20%).PLA exposure significantly induced superoxide dismutase(SOD)activity and malondialdehyde(MDA)content,indicating that Daphnia magna was subjected to oxidative stress and caused lipid peroxidation damage.At the concentration of 40mg/L,PLA significantly inhibited the acetylcholinesterase(AChE)activity,resulting in neurotoxicity and motor disorders of Daphnia magna.