Prosenc Franja, Leban Pia, Šunta Urška, Bavcon Kralj Mojca
Research Institute, Faculty of Health Sciences, University of Ljubljana, 1000 Ljubljana, Slovenia.
Department for Sanitary Engineering, Faculty of Health Sciences, University of Ljubljana, 1000 Ljubljana, Slovenia.
Polymers (Basel). 2021 Nov 23;13(23):4069. doi: 10.3390/polym13234069.
Microplastic pollution is globally widespread; however, the presence of microplastics in soil systems is poorly understood, due to the complexity of soils and a lack of standardised extraction methods. Two commonly used extraction methods were optimised and compared for the extraction of low-density (polyethylene (PE)) and high-density microplastics (polyethylene (PET)), olive-oil-based extraction, and density separation with zinc chloride (ZnCl2). Comparable recoveries in a low-organic-matter matrix (soil; most >98%) were observed, but in a high-organic-matter matrix (compost), density separation yielded higher recoveries (98 ± 4% vs. 80 ± 11%). Density separation was further tested for the extraction of five microplastic polymers spiked at different concentrations. Recoveries were >93% for both soil and compost, with no differences between matrices and individual polymers. Reduction in levels of organic matter in compost was tested before and after extraction, as well as combined. Double oxidation (Fenton's reagent and 1 M NaOH) exhibited the highest reduction in organic matter. Extracted microplastic polymers were further identified via headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS). This method has shown the potential for descriptive quantification of microplastic polymers. A linear relationship between the number of particles and the signal response was demonstrated for PET, polystyrene (PS), polyvinyl chloride (PVC), and PE (R > 0.98 in alluvial soil, and R > 0.80 in compost). The extraction and identification methods were demonstrated on an environmental sample of municipal biowaste compost, with the recovery of 36 ± 9 microplastic particles per 10 g of compost, and the detection of PS and PP.
微塑料污染在全球范围内广泛存在；然而，由于土壤的复杂性以及缺乏标准化的提取方法，人们对土壤系统中微塑料的存在情况了解甚少。对两种常用的提取方法进行了优化并比较，用于提取低密度（聚乙烯（PE））和高密度微塑料（聚对苯二甲酸乙二酯（PET）），即基于橄榄油的提取方法以及用氯化锌（ZnCl₂）进行密度分离。在低有机质基质（土壤；大多数回收率>98%）中观察到了相当的回收率，但在高有机质基质（堆肥）中，密度分离产生了更高的回收率（98±4%对80±11%）。对密度分离法进一步测试了添加不同浓度的五种微塑料聚合物的提取情况。土壤和堆肥的回收率均>93%，基质和单个聚合物之间没有差异。对堆肥提取前后以及综合处理后的有机质含量降低情况进行了测试。双重氧化（芬顿试剂和1 M氢氧化钠）显示出最高的有机质降低率。通过顶空固相微萃取-气相色谱-质谱联用仪（HS-SPME-GC-MS）对提取的微塑料聚合物进行了进一步鉴定。该方法已显示出对微塑料聚合物进行描述性定量的潜力。对于PET、聚苯乙烯（PS）、聚氯乙烯（PVC）和PE，证明了颗粒数量与信号响应之间存在线性关系（在冲积土中R > 0.98，在堆肥中R > 0.80）。在城市生物废物堆肥的环境样品上展示了提取和鉴定方法，每10克堆肥回收了36±9个微塑料颗粒，并检测到了PS和PP。
