Microplastic Extraction from Agricultural Soils Using Canola Oil and Unsaturated Sodium Chloride Solution and Evaluation by Incineration Method
Microplastic Extraction from Agricultural Soils Using Canola Oil and Unsaturated Sodium Chloride Solution and Evaluation by Incineration Method
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DOI：
10.3390/soilsystems6020054
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发表时间：
2022-06
期刊：
影响因子：
3.5
通讯作者：
A. Kononov;Motoya Hishida;Kazuki Suzuki;N. Harada
中科院分区：
文献类型：
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作者：
A. Kononov;Motoya Hishida;Kazuki Suzuki;N. Harada
微塑料对环境的污染已成为一个全球性的问题，但人们对土壤中的微塑料知之甚少。这是因为从土壤中提取MP的方法尚未标准化。本研究利用芥花油的浮力和氯化钠的密度分离过程，尝试建立一种简单、经济的土壤多金属蛋白提取方法。此外，采用焚烧法对提取方法的有效性进行了准确评价。首先，研究了七种不同的油从土壤中提取MP的能力和适用性，并选择了菜籽油。然后，使用芥花油和NaCl溶液对低密度聚乙烯（LDPE）、聚丙烯（PP）和聚氯乙烯（PVC）进行加标和回收试验，如下所示：（1）制备土壤和MP混合物，（2）加入5 g L-1 NaCl和芥花油并充分摇动，（3）沉淀后分离含有MP的油相，（4）用99.5%乙醇冲洗提取的MP，和（5）用过氧化氢消化提取的MP的有机粘附物。经过干燥和焚烧后，计算了实质性的回收率。在日本5种典型农业土壤中MP颗粒（<1 mm）的加标回收试验中，LDPE、PP和PVC的回收率分别为95.2- 98.3%、95.2- 98.7%和76.0- 80.5%，比用饱和NaCl溶液密度分离法所得的结果高。总之，该方法是有效的提取MPs，特别是低密度聚乙烯和聚丙烯，从土壤中，是不敏感的土壤类型，质地和理化性质。
Environmental pollution by microplastics (MPs) has become a global problem, but little is known about MPs in soils. This is because MP extraction methods from soils have not yet been standardized. In this study, we tried to establish a simple and economical method to extract soil MPs using the buoyancy of canola oil and the density separation process using sodium chloride (NaCl). In addition, the incineration method was adapted to evaluate the effectiveness of extraction methods precisely. First, the ability and suitability of seven different oils to extract MP from soil were investigated and canola oil was selected. Then, the spiking and recovery test was performed with canola oil and NaCl solution for low-density polyethylene (LDPE), polypropylene (PP), and polyvinylchloride (PVC) as follows: (1) soil and MP mixtures were prepared, (2) 5 g L−1 NaCl and canola oil were added and shaken thoroughly, (3) the oil phase containing MPs were separated after sedimentation, (4) the extracted MPs were rinsed with 99.5% ethanol, and (5) the organic adherents to the extracted MPs were digested with hydrogen peroxide. After drying and incineration, the substantial recovery rates were calculated. In the spiking and recovery test for MP particles (<1 mm) from five typical Japanese agricultural soils, the recoveries of LDPE, PP, and PVC were 95.2–98.3%, 95.2–98.7%, and 76.0–80.5%, respectively, higher than those obtained by the density separation using saturated NaCl solution. In conclusion, the method is effective for extracting MPs, especially LDPE and PP, from soils and is less sensitive to soil type, texture, and physicochemical properties.