Characteristics of atmospheric PM2.5 in stands and non-forest cover sites across urban-rural areas in Beijing, China

Abstract

Monitoring air pollution at a city scale is essential for controlling urban air pollution in cities, especially megacities, in China. In this paper, data for 1 city center site and 5 paired (stands and non-forested) PM2.5 monitoring sites across urban-rural areas in Beijing were collected, and air PM2.5 and influential factors were analyzed. The results showed that the mean value of PM2.5 (February to December 2013) was lower in the stands (67.00 μ gm �3 ) than in the non-forested sites (78.02 μ gm �3 ). The diurnal variation was a bimodal double-dip type, and the average daily PM2.5 was lower in the vegetation areas than in the non-vegetation areas in both Changping Dingling (vegetation) and Changping town (non-vegetation) and showed day > night. In the typical pollution process, accompanied by an increase or decrease in PM2.5 and air quality index values, the higher the PM2.5, the lower the wind speed. PM2.5 in the vegetation areas lagged behind PM2.5 in the non-vegetation areas on typical sunny days but not on typical rainy and windy days. On typical sunny days, the variation of PM2.5 in the vegetation areas was less than that in the non-vegetation areas. PM2.5 did not change significantly under rainy conditions and before a rain, but the variation was smaller after a