环境浓度微/纳米塑料对铜绿微囊藻的毒性效应

Toxic effects of micro/nanoplastics with environmental concentration on Microcystis aeruginosa

湖泊富营养化导致蓝藻水华频发,微塑料这一新出现的环境污染物也广泛存在于富营养化水体中,已有研究认为微塑料可能对蓝藻的环境行为产生进一步的影响.然而,目前微塑料对蓝藻影响的研究主要集中于高浓度、单一粒径微塑料的暴露实验,尚缺乏蓝藻对环境浓度、混合粒径微塑料的抗逆性响应研究.本文探究了不同环境浓度(1、6、12 mg·L^(-1))、不同粒径(0.05、0.5、5μm)及混合粒径的聚苯乙烯微塑料(Polystyrene microplastics,PS-MPs)对铜绿微囊藻的毒性效应.结果表明:环境浓度(6 mg·L^(-1))下,微塑料(0.5、5μm)对铜绿微囊藻生长无显著影响,而纳米塑料(0.05μm)短期暴露即可对铜绿微囊藻产生明显的毒性作用,包括铜绿微囊藻种群密度下降、藻细胞内抗氧化酶活性和脂质过氧化物丙二醛含量上升、藻毒素合成与释放量增大、细胞结构受损,且毒性作用随纳米塑料浓度的增加而增大.6 mg·L^(-1)混合粒径PS-MPs短期暴露对铜绿微囊藻的毒性作用大于所有单一粒径PS-MPs,可以提高微囊藻毒素的释放率,从而增加蓝藻水华对水生态系统和人类健康的威胁.本研究有助于深入了解水体中的微塑料污染对蓝藻水华的影响,合理评估和管理水华爆发的生态风险.

Lake eutrophication leads to harmful cyanobacterial blooms.Emerging environmental pollutants microplastics are also widely present in eutrophication system.Previous studies have demonstrated that microplastics may further impact on the environmental behavior of cyanobacteria.However,the current research on the impact of microplastics on cyanobacteria mainly focuses on the exposure experiments with high-concentration and single-size microplastics.There still needs to be more research on the stress response of cyanobacteria to environmental concentrations and mixed particle size microplastics.The toxic effects of different environmental concentrations(1,6,12 mg·L^(-1)),different particle sizes(0.05,0.5,5μm),and mixed particle size polystyrene microplastics(PS-MPs)on Microcystis aeruginosa were explored.The results showed that experimental research was carried out under environmental concentration of 6 mg·L^(-1).There was no significant effect on Microcystis aeruginosa when the microplastics size was 0.5~5μm.In contrast,short-term exposure to 0.05μm nanoplastics system has a significant toxic effect on Microcystis aeruginosa.These toxic effects included decreased population density,increased intracellular antioxidant enzyme activity and lipid peroxide malondialdehyde content,increased microcystin synthesis and release,and impaired cellular structure.Short-term exposure to mixed particle size PS-MPs had a more significant toxic effect on Microcystis aeruginosa than all single particle size PS-MPs.Microplastics can increase the release rate of microcystins,thereby increasing the threat of cyanobacterial blooms to aquatic ecosystems and human health.The results will be helpful for understanding microplastic pollution on cyanobacterial blooms,and reasonably assessing and managing the involved eco-risks.