Changes in fine particulate matter concentration of near-ground air and its influence on environmental factors at farmlands in Sishui during Spring

The present study observed changes in fine particulate matter (PM_2.5) concentration and environmental factors of air 80 cm above the ground surface of cultivated farmlands in Sishui County, Shandong Province, China, during spring (March 1st – May 31st, 2019). PM_2.5 samplers and automatic weather stations were installed. Soil temperature and moisture data were monitored, and the associations between changes in PM_2.5 concentration and environmental factors were assessed using regression analysis. From March to May, the average PM_2.5 concentration was 160.98 µg·m⁻³, ranging between 16.67 and 333.33 µg·m⁻³. In addition, changes in PM_2.5 concentration were exponentially and positively correlated with wind speed (P < 0.05),and exponentially but negatively correlated soil moisture in the 0 – 5 cm layer (P < 0.05). Moreover, changes in PM_2.5 concentration were significantly and inversely correlated with ambient temperature (P < 0.01). Furthermore, multiple regression analysis revealed a significant effect of wind speed and soil moisture in the 5 cm layer on PM_2.5 concentration (P < 0.01). These results suggest that in spring, PM_2.5 pollution of near-ground air at farmlands in Sishui is significantly affected by wind speed and soil moisture in the 0 – 5 cm layer, in addition to other factors that have a non-negligible impact on the atmospheric environment.