Urban soil microplastic characterization across diverse land use types along the Anyangcheon stream in Seoul, Korea

Microplastics (MPs) are becoming more prevalent in soils. MPs can alter soil pH and soil pore structure. A lot of studies lately have identified and quantified MP occurrence in areas of variable community settlement, such as rural areas with excessive farming and fewer human populations. However, there are limited studies on the spatial distribution of MPs in urban areas along a stream. So, this study aimed to investigate the occurrence, characteristics, and distribution of MPs in soils across 3 different land-use types (high schools, park playgrounds, and residential areas) along the Anyangcheon stream in Seoul, the biggest city in Korea. Overall, 12 samples (4 per land-use type) were collected, pretreated, and analysed using Fourier Transform Infrared (FTIR) spectroscopy. Results revealed that the average concentration of MPs in soil samples in high schools was 62-824 items/kg, 129-5083 items/kg in parks, and 179-2006 items/kg in residential areas. The predominant shape of MPs were fragments, and with variable colours such as: black, white, beige, and grey, and natural being the most prominent colour. The patterns of size distribution varied significantly across the land-use types, and different MP polymers showed varied occurrences, with polypropylene (PP) being the predominant polymer. From the result it was inferred that land-use type significantly affecting MP particle size distribution in soils (p = 0.009). Common sources of MP, such as synthetic textile, plastic waste, synthetic turfs and degradation from playground equipment's, contributes to their presence in these environments.