A comprehensive review of the circulation of microplastics in aquatic ecosystem using scientometric method

Establishing freshwater sediment sample pretreatment methods for monitoring microplastics and its challenges

Microplastics (MPs) have been detected in various environmental matrices, drinking water, and food, and their presence is an ecological and human health concern. Most research on MPs has focused solely on their detection and analysis. However, sample pretreatment methods are critical for accurate MP analysis and must be properly established. In particular, freshwater sediment contains more impurities than other environment samples, thus requiring more elaborate sample pretreatment. Therefore, research on this media and corresponding pretreatment needs to be performed. Herein, we present a sample pretreatment method for analyzing MPs in freshwater sediments. Detailed factors in arriving at this pretreatment process were evaluated and discussed. Using this established pretreatment method, a total average recovery of six types of standard MPs (HDPE, LDPE, PS, PP, PET, and PVC) for sizes of ≥ 100 μm, 20-100 μm, and 1-20 μm was 94.0%, 90.2%, and 82.5%, respectively. After recovery validation, a modular pretreatment device was developed and combined with the established pretreatment method. The developed device performs density separation and organic matter removal, resulting in about 80% recovery of standard MPs. In addition, natural freshwater sediment samples were prepared using an established pretreatment method, and MPs in streams were analyzed using FTIR, TED-GC-MS, and Pyr-GC-MS. The device affords a low-cost, simple, efficient tool for sample pretreatment steps and easy MP recovery. Thus, it has great potential to simplify sample pretreatment steps for easy MP monitoring, especially for freshwater sediment samples.

Occurrence and sources of micro-plastics in various water bodies, sediments, and fishes in Ansan, South Korea

In this study, the Pearson correlation coefficients were determined to derive correlations between micro-plastics (MPs) in carp and river crabs. MPs were detected for various water sources, including four rivers and four main waterways, sediments, and fish, using Fourier transform infrared spectrometry (FTIR), microscopic analysis, and image mapping. Carp and river crabs had coefficients of 0.888 and 0.724, respectively, which showed a high positive correlation. In water samples, the MPs detected in rivers were higher than those in the main waterway. However, in sediment samples, the MPs detected in the main waterway were higher than those in the rivers. It is believed that MPs are carried toward shore by ocean tide. The size of most of the sediment MPs was 20-49 µm, representing 64.1% of the entire population. The plastics detected in this study were polyethylene terephthalate (PET), polypropylene (PP), and polyethylene (PE), which originate from synthetic fibers, scrubs, and packing material. MP pollution by non-point pollution sources was investigated, with the abundance of MPs increasing by 2 to 3 times between the dry and wet seasons in water and sediment, respectively. It was determined that the inflow of MPs into rivers could have been due to non-point source pollutants from household items, roads, plants, and soil around the water sources.