Characterization of atmospheric microplastics: A case study in Shenzhen City, a southern coastal area of China

The sources of atmospheric microplastics (AMPs) are complex and widely distributed. Microplastic pollution is particularly severe in urban areas. In this study, the abundance of AMPs was investigated at ten representative sampling points, with three points at an experimental building, and seven sample points at a residential district, an industrial area, a park, a farmland, a roadside, a river, and a seaside, respectively. The results show that the average abundance of AMPs is 2.22 n/m³, with a range from 1.31 to 4.5 n/m³. Human activities significantly contribute to the release of MPs. Furthermore, the abundance of AMPs decreases with increasing altitude. The predominant colors of AMPs are black and transparent, and particle sizes predominantly range from 50 to 200 µm. The micro-Fourier transform infrared spectrometer (µ-FTIR) analysis indicates that AMPs are primarily composed of polyethylene (PE), polypropylene (PP), and polyethylene terephthalate (PET), with fibrous shapes being predominant. In the principal component analysis (PCA), it was observed that AMPs exhibit a positive correlation with temperature and a negative correlation with humidity. This research may shed new light on future policy-making in microplastic control.