Sivaraman Mythreyi, Fan Lingfei, Yan Weile
Department of Civil and Environmental Engineering, University of Massachusetts Lowell, MA, United States.
Department of Civil and Environmental Engineering, University of Massachusetts Lowell, MA, United States.
Sci Total Environ. 2024 Nov 25;953:176009. doi: 10.1016/j.scitotenv.2024.176009. Epub 2024 Sep 2.
Quantifying trace levels of microplastics in complex environmental media remains a challenge. In this study, an approach combining field collection of samples from different depths, sample size fractionation, and plastic quantification via pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) was employed to identify and quantify microplastics at two public beaches along the northeast coast of the U.S. (Salisbury beach, MA and Hampton beach, NH). A simple sampling tool was used to collect beach sand from depth intervals of 0-5 cm and 5-10 cm, respectively. The samples were sieved to give three size fractions: coarse (>1.2 mm), intermediate (100 μm-1.2 mm), and fine (1.2 μm-100 μm) particles. Following density separation and wet peroxide oxidation, a low-temperature solvent extraction protocol involving 2-chlorophenol was used to extract polyester (PET), polystyrene (PS), polyamide (PA), and polyvinyl chloride (PVC). The extract was analyzed using Py-GC-MS for the respective polymers, while the solid residue was pyrolyzed separately for polyethylene (PE) and polypropylene (PP). The one-step solvent extraction method significantly simplified the sample matrix and improved the sensitivity of analysis. Among the samples, PET was detected in greater quantities in the fine fraction than in the intermediate size fraction, and PET fine particles were located predominantly in the surface sand. Similar to PET, PS was detected at higher mass concentrations in the fine particles in most samples. These results underscore the importance of beach environment for plastic fragmentation, where a combination of factors including UV irradiation, mechanical abrasion, and water exposure promote plastic breakdown. Surface accumulation of fine plastic particles may also be attributed to transport of microplastics through wind and tides. The proposed sample treatment and analysis methods may allow sensitive and quantitative measurements of size or depth-related distribution patterns of microplastics in complex environmental media.
对复杂环境介质中的微量微塑料进行定量分析仍然是一项挑战。在本研究中，采用了一种结合从不同深度现场采集样品、样品大小分级以及通过热解气相色谱 - 质谱联用仪（Py - GC - MS）进行塑料定量分析的方法，来识别和定量美国东北海岸两个公共海滩（马萨诸塞州索尔兹伯里海滩和新罕布什尔州汉普顿海滩）的微塑料。使用一种简单的采样工具分别从0 - 5厘米和5 - 10厘米深度区间采集海滩沙子。将样品过筛，得到三个大小分级：粗颗粒（>1.2毫米）、中等颗粒（100微米 - 1.2毫米）和细颗粒（1.2微米 - 100微米）。经过密度分离和湿式过氧化物氧化后，采用一种涉及2 - 氯苯酚的低温溶剂萃取方案来萃取聚酯（PET）、聚苯乙烯（PS）、聚酰胺（PA）和聚氯乙烯（PVC）。萃取物通过Py - GC - MS分析各聚合物，而固体残渣则分别对聚乙烯（PE）和聚丙烯（PP）进行热解。一步溶剂萃取法显著简化了样品基质并提高了分析灵敏度。在样品中，细颗粒级分中检测到的PET数量多于中等大小级分，并且PET细颗粒主要位于表层沙子中。与PET类似，大多数样品中细颗粒中的PS质量浓度更高。这些结果强调了海滩环境对塑料破碎的重要性，其中包括紫外线照射、机械磨损和水暴露等多种因素共同促进了塑料的分解。细塑料颗粒在表面的积累也可能归因于微塑料通过风和潮汐的运输。所提出的样品处理和分析方法可能允许对复杂环境介质中微塑料的大小或深度相关分布模式进行灵敏且定量的测量。
