Liu Jinbo, Qin Jianjun, Zhu Lang, Zhu Kecheng, Liu Ze, Jia Hanzhong, Lichtfouse Eric
Key Laboratory of Plant Nutrition and the Agri-environment in Northwest China, Ministry of Agriculture, College of Natural Resources and Environment, Northwest A & F University, Yangling 712100, China.
Key Laboratory of Plant Nutrition and the Agri-environment in Northwest China, Ministry of Agriculture, College of Natural Resources and Environment, Northwest A & F University, Yangling 712100, China.
Environ Int. 2022 Apr;162:107158. doi: 10.1016/j.envint.2022.107158. Epub 2022 Feb 25.
The recent discovery of microplastics contaminants in most ecosystems has raised major health issues, yet knowledge on their impact on soil organisms is limited, especially their toxicity evolution with aging. Herein, the toxicity of polystyrene microplastic (PS-MP) to earthworm (Eisenia fetida) along with aging was investigated. Results showed that the 28 d-LC (50% lethal concentration) of PS-MP was 25.67 g kg, whereas that increased to 96.47 g kg after PS-MP initially aged in soil for 28 days, indicating the toxicity of PS-MP decreased with aging. Laser scanning confocal microscope and scanning electron microscope (SEM) found that the toxicity of PS-MP to earthworm may be due to the ingestion of PS-MP by earthworms and the physical damage (e.g., epidermis abrasion and setae loss) of PS-MP to earthworms. Similarly, the levels of reactive oxygen species, antioxidant enzyme activities and malondialdehyde content increased with PS-MP concentrations from 0.1 to 1.5 g kg, but decreased with aging from 7 to 28 days. The integrated biomarker response index also confirmed that the toxicity of PS-MP decreased with aging. SEM found that PS-MP were progressively covered by soil particles during soil aging, inducing the formation of protective layer and increasing the particle size of PS-MP, which prevented direct contact with earthworms and decreased the ingestion of PS-MP, in turn decreased PS-MP toxicity. Overall, our study provides valuable insights for elucidating the effect of aging on the toxicity of microplastics.
最近在大多数生态系统中发现的微塑料污染物引发了重大健康问题，但关于它们对土壤生物影响的了解有限，尤其是其毒性随老化的演变。在此，研究了聚苯乙烯微塑料（PS-MP）对蚯蚓（赤子爱胜蚓）的毒性及其随老化的变化。结果表明，PS-MP的28天半数致死浓度（LC）为25.67克/千克，而在土壤中初步老化28天后，该浓度增加到96.47克/千克，表明PS-MP的毒性随老化而降低。激光扫描共聚焦显微镜和扫描电子显微镜（SEM）发现，PS-MP对蚯蚓的毒性可能是由于蚯蚓摄入PS-MP以及PS-MP对蚯蚓造成的物理损伤（如表皮磨损和刚毛脱落）。同样，活性氧水平、抗氧化酶活性和丙二醛含量随着PS-MP浓度从0.1克/千克增加到1.5克/千克而升高，但随着老化从7天到28天而降低。综合生物标志物反应指数也证实PS-MP的毒性随老化而降低。SEM发现，在土壤老化过程中，PS-MP逐渐被土壤颗粒覆盖，诱导形成保护层并增加PS-MP的粒径，这阻止了与蚯蚓的直接接触并减少了PS-MP的摄入，进而降低了PS-MP的毒性。总体而言，我们的研究为阐明老化对微塑料毒性的影响提供了有价值的见解。
