Möller Julia N, Heisel Ingrid, Satzger Anna, Vizsolyi Eva C, Oster S D Jakob, Agarwal Seema, Laforsch Christian, Löder Martin G J
Department of Animal Ecology I and BayCEER, University of Bayreuth, Bayreuth, Germany.
Department of Macromolecular Chemistry II, University of Bayreuth, Bayreuth, Germany.
Environ Toxicol Chem. 2022 Apr;41(4):844-857. doi: 10.1002/etc.5024. Epub 2021 May 6.
Microplastic pollution in soils is an emerging topic in the scientific community, with researchers striving to determine the occurrence and the impact of microplastics on soil health, ecology, and functionality. However, information on the microplastic contamination of soils is limited because of a lack of suitable analytical methods. Because micro-Fourier-transform infrared spectroscopy (µ-FTIR), next to Raman spectroscopy, is one of the few methods that allows the determination of the number, polymer type, shape, and size of microplastic particles, the present study addresses the challenge of purifying soil samples sufficiently to allow a subsequent µ-FTIR analysis. A combination of freeze-drying, sieving, density separation, and a sequential enzymatic-oxidative digestion protocol enables removal of the mineral mass (>99.9% dry wt) and an average reduction of 77% dry weight of the remaining organic fraction. In addition to visual integrity, attenuated total reflectance FTIR, gel permeation chromatography, and differential scanning calorimetry showed that polyamide, polyethylene, polyethylene terephthalate, and polyvinyl chloride in the size range of 100 to 400 µm were not affected by the approach. However, biodegradable polylactic acid showed visible signs of degradation and reduced molecular weight distribution after protease treatment. Nevertheless, the presented purification protocol is a reliable and robust method to purify relatively large soil samples of approximately 250 g dry weight for spectroscopic analysis in microplastic research and has been shown to recover various microplastic fibers and fragments down to a size of 10 µm from natural soil samples. Environ Toxicol Chem 2022;41:844-857. © 2021 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.
土壤中的微塑料污染是科学界一个新兴的课题，研究人员致力于确定微塑料的存在情况及其对土壤健康、生态和功能的影响。然而，由于缺乏合适的分析方法，关于土壤微塑料污染的信息有限。由于显微傅里叶变换红外光谱（µ-FTIR）与拉曼光谱一样，是少数能够确定微塑料颗粒数量、聚合物类型、形状和尺寸的方法之一，本研究应对了充分净化土壤样品以进行后续µ-FTIR分析这一挑战。冷冻干燥、筛分、密度分离和连续酶氧化消化方案相结合，能够去除矿物质（干重>99.9%），并使剩余有机部分的干重平均减少77%。除了视觉完整性外，衰减全反射傅里叶变换红外光谱、凝胶渗透色谱和差示扫描量热法表明，尺寸在100至400 µm范围内的聚酰胺、聚乙烯、聚对苯二甲酸乙二酯和聚氯乙烯不受该方法影响。然而，可生物降解的聚乳酸在蛋白酶处理后出现了明显的降解迹象，分子量分布降低。尽管如此，所提出的净化方案是一种可靠且稳健的方法，可用于净化约250 g干重的相对较大土壤样品，用于微塑料研究中的光谱分析，并且已证明能够从天然土壤样品中回收各种低至10 µm大小的微塑料纤维和碎片。《环境毒理学与化学》2022年；41:844 - 857。© 2021作者。《环境毒理学与化学》由Wiley Periodicals LLC代表SETAC出版。
