Composition and Distribution of Microplastics in the Water and Sediments of Urban Rivers in Beijing

Abstract

It has been confirmed that microplastics widely exist in the natural environment, causing potential harm to organisms and humans. An investigation into the occurrence of microplastics is helpful to understand the level of pollution of microplastics in urban rivers and sediments. In this study, eight sampling points of water samples and three of sediments samples were placed along the North Canal and Huaihe River in Beijing, to compare the composition and distribution characteristics of the abundance, particle size, color, shape, and species of microplastics. The results showed that the abundance of microplastics in the water and sediments of the North Canal were(1941±201)-(8155±1781) n·m-3(n refers to the number of microplastics) and (120±11)-(268±31) n·kg-1, respectively. The average abundance of microplastics in the water of the North Canal was 4160 n·m-3. Compared with the North Canal, the pollution degree of microplastics in the Huaihe River was lower with an average abundance of 2357 n·m-3. Furthermore, the abundance of microplastics in the water and sediments in the upper reaches of the North Canal was higher than that in the lower reaches. No significant difference of microplastics distribution was observed in the water of the Huaihe River on the whole; however, there was a marked difference in abundance between the two distant locations. The main particle size range of microplastics at all site points was<300 μm, and mostly white/transparent(50.75%-83.91%); the main shape were fragments(50.00%-95.08%) and fibers(3.86%-30.00%). Polyurethane(PU) and ethylene vinyl acetate(EVA) were two main plastic species found at all sites. Microplastics in the water and sediments of the North Canal might have originated from urban construction and development, while the surrounding villages might have only affected the abundance of microplastics in the Huaihe River.