Faculty of Engineering and Physical Sciences, University of Southampton, Highfield Campus, University Road, Southampton SO17 1BJ, UK.
Anal Methods. 2021 Apr 14;13(14):1695-1705. doi: 10.1039/d0ay02086a. Epub 2021 Mar 22.
Microplastics are an environmental issue of global concern. Although they have been found in a range of environments worldwide, their contamination in the terrestrial environment is poorly understood. The lack of standardised methods for their detection and quantification is a major obstacle for determining the risk they pose to soil environments. Here we present a systematic comparison of microplastic extraction methods from soils, taking into account the characteristics of the soil medium to determine the best methods for quantification. The efficiency of organic matter removal using hydrogen peroxide, potassium hydroxide and Fenton's reagent was measured. Soils with a range of particle size distribution and organic matter content were spiked with a variety of microplastic types. Density separation methods using sodium chloride, zinc chloride and canola oil were tested. Recovery efficiencies were calculated and the impact of the reagents on the microplastics was quantified using Attenuated Total Reflectance (ATR) Fourier Transform-Infrared (FTIR) spectroscopy. The optimal organic removal method was found to be hydrogen peroxide. The recovery efficiency of microplastics was variable across polymer types. Overall, canola oil was shown to be the optimal method for density separation, however, efficiency was dependent on the amount of organic matter in the soil. This outcome highlights the importance of including matrix-specific calibration in future studies considering a wide range of microplastic types, to avoid underestimation of microplastic contamination. We show here that methods for extracting microplastics from soils can be simple, cost-effective and widely applicable, which will enable the advancement of microplastic research in terrestrial environments.
微塑料是一个全球性的环境问题。尽管它们已在全球范围内的各种环境中被发现，但对其在陆地环境中的污染情况仍了解甚少。缺乏标准化的检测和定量方法是确定其对土壤环境构成风险的主要障碍。在这里，我们系统比较了从土壤中提取微塑料的方法，同时考虑了土壤介质的特性，以确定最适合定量的方法。我们测量了使用过氧化氢、氢氧化钾和芬顿试剂去除有机质的效率。用各种微塑料类型对具有不同粒径分布和有机质含量的土壤进行了添加。测试了使用氯化钠、氯化锌和菜籽油的密度分离方法。计算了回收率，并使用衰减全反射（ATR）傅里叶变换红外（FTIR）光谱量化了试剂对微塑料的影响。发现过氧化氢是去除有机质的最佳方法。不同聚合物类型的微塑料回收率不同。总体而言，菜籽油是密度分离的最佳方法，但效率取决于土壤中的有机质含量。这一结果强调了在未来研究中考虑广泛的微塑料类型时，包括基质特异性校准的重要性，以避免低估微塑料污染。我们在这里表明，从土壤中提取微塑料的方法可以简单、经济高效且广泛适用，这将有助于推进陆地环境中微塑料的研究。
