Fractional Vegetation Cover and Spatiotemporal Variations of PM2.5 Concentrations in the Beijing-Tianjin-Hebei Region of China

Abstract

The Beijing-Tianjin-Hebei region (BTH) of China maintains high-pollution levels of particulate matter ≥2.5 μm (PM2.5). Accordingly, understanding the spatiotemporal distributions of PM2.5 and their relationship with fractional vegetation cover in this region is of great significance for effective air pollution treatment. In the present study, ground-based PM2.5 monitoring, MODIS-NDVI satellite data, spatial interpolation, dimidiate pixel model, and Spearman’s rank correlation analyses were used to explore this relationship in the years 2018 and 2019. The results indicated the following: (1) In the BTH, the average annual PM2.5 mass concentration was 50 μg·m−3 in 2019, a 9.2% decrease from 2018, but still in excess of China’s second-level environmental air quality standards (35 µg·m−3). (2) PM2.5 concentrations in the BTH were temporally distributed, exhibiting a roughly U-shaped pattern within a year, peaking in the winter, followed by the spring and autumn, and reaching its minimum in the summer. (3) Spatially, distributions of PM2.5 mass concentrations in the BTH were significantly lower in the north and higher in the south. PM2.5 in the central and southern areas displayed concentrated and continuous distribution trends. (4) PM2.5 concentrations were negatively correlated with fractional vegetation cover in the BTH, and the effect of fractional vegetation cover on PM2.5 mass concentration was more significant in the winter than in other seasons. According to the results of this study, improving vegetation cover and increasing vegetation area have a positive effect on PM2.5 deposition in the Beijing-Tianjin-Hebei region. Therefore, the author suggests that the ability of urban green spaces to mitigate PM2.5 pollution in the Beijing-Tianjin-Hebei region can be improved in the future by controlling the vegetation coverage of urban green spaces to a suitable extent, especially in winter. This study provides an important scientific basis for the quantitative analysis of the effect of vegetation cover on PM2.5 concentration distribution and air pollution control and environmental protection in the Beijing-Tianjin-Hebei region.