Microplastic Textile Fibers Accumulate in Sand and Are Potential Sources of Micro(nano)plastic Pollution

Agricultural soils have been identified as sinks for microplastic fibers; however, little information is available on their long-term fate in these soils. In this study, polyester and nylon fibers were precisely cut to relevant environmental lengths, using novel methodology, and their behavior in sand columns was studied at environmental concentration. The longer fibers (>50 μm) accumulated in the upper layers of the sand, smaller fibers were slightly more mobile, and nylon showed marginally higher mobility than polyester. Previous studies have overlooked changes in microplastic morphology due to transport in soil. Our study is the first to show that fibers exhibited breakage, peeling, and thinning under flow conditions in soil, releasing smaller, more mobile fragments. Furthermore, the peelings exhibited different adsorption properties compared to the core fiber. This suggests that microplastic fibers can become a source of smaller micro(nano)plastics and potential vectors for certain molecules, risking continuous contamination of nearby soils, surfaces, and groundwater.