二类生物可降解塑料对铜绿微囊藻的毒性效应

Toxic effects of class II biodegradable plastics on Microcystis aeruginosa

本研究选用生物可降解塑料(BMPs)中的聚乳酸(PLA)、聚己二酸对苯二甲酸丁二醇酯(PBAT)和传统微塑料(CMPs)中的聚乙烯(PE)作为供试化学品,以铜绿微囊藻(Microcystis aeruginosa)为供试生物.通过藻细胞密度、叶绿素a(Chl-a)、超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、丙二醛(MDA)、胞内总溶解性蛋白质(TP)、活性氧(ROS)等指标的测试,探明不同投加量(50,100,150,200mg/L)和粒径(150,250,500μm)的PLA、PBAT以及PE对铜绿微囊藻的生长、氧化应激以及细胞损伤的影响作用.结果表明,在PLA/PBAT/PE单一作用下,藻细胞的生长和氧化应激指标随暴露时间均发生了明显变化.在暴露96h后,相较于其他处理组,PLA投加量为100mg/L对铜绿微囊藻的抑制率最大(16.31%),而在粒径方面PE150μm的抑制率最大(15.97%).PLA和PE的暴露使铜绿微囊藻的ROS、SOD、CAT和MDA含量显著提高,其急性毒性差异可能与微塑料表面的粗糙程度有关;而作为脂肪族聚酯的PLA在水环境中较PBAT更易发生水解,二次微塑料碎片的释放潜能使其对藻类产生更为严重的急性毒性.

In this study,polylactic acid(PLA),polybutylene glycol terephthalate(PBAT)in biodegradable plastics(BMPs)and polyethylene(PE)in conventional microplastics(CMPs)were selected as test chemicals,and Microcystis aeruginosa was used as the test organism.By testing indicators such as algal cell density,chlorophyll a(Chl-a),superoxide dismutase(SOD),catalase(CAT),malondialdehyde(MDA),total intracellular soluble protein(TP)and reactive oxygen species(ROS),the effects of different dosages(50,100,150 and 200mg/L)and particle size(150,250 and 500μm)of PLA,PBAT and PE on the growth,oxidative stress and cell damage of Microcystis aeruginosa were investigated.The results showed that the growth and oxidative stress indexes of algal cells exhibited significant changes with exposure time under the single action of PLA/PBAT/PE.After 96h of exposure,compared with other treatment groups,the inhibition rate of PLA at a dosage of 100mg/L on Microcystis aeruginosa was the highest(16.31%),while the inhibition rate of PE at a particle size of 150μm was the highest(15.97%).The exposure of PLA and PE significantly increased the contents of ROS,SOD,CAT and MDA in Microcystis aeruginosa,and their acute toxicity differences may be related to the roughness of the microplastic surfaces.PLA,as an aliphatic polyester,was more prone to hydrolysis in aquatic environments than PBAT,and the release potential of secondary microplastic fragments made it more severely acute toxic to algae.