Wheat straw burning and its associated impacts on Beijing air quality

Based on MODIS images, large-scale flow field charts and environmental monitoring data, we thor- oughly analyzed the spatial distribution of wheat straw burning in North China, with focus on its envi- ronmental impacts on the air quality of Beijing and pollution transport paths. And we anatomized changes of air quality in Beijing under the impacts of pollution generated by wheat straw burning around. The results indicate that: (1) The North China Plain, a winter-wheat growing area, is the main source of pollutants induced by wheat straw burning in Beijing. The direction of south-west is the dominant heavy pollution transport path. (2) Impacts of wheat straw burning on air quality are mainly manifested by significantly increasing CO concentration. (3) Precursors of O3 generated by wheat straw burning, combining with favorable meteorological conditions, can induce increasing O3 concentration greatly. NO concentration will be greatly increased due to decreasing O3 concentration at night. (4) Atmospheric particles, especially the fine ones, from wheat straw burning exert considerable influ- ence on Beijing air quality. (5) Different contributions of wheat straw burning to pollutants are identified. Ratios of PM10/SO2, CO/SO2, etc., can be applied to indicate pollution extent of wheat straw burning. High ratios of PM10/SO2 and CO/SO2 show that the air quality was heavily impacted by wheat straw burning and these ratios can be employed as indicators of contribution of wheat straw burning to the degradation of Beijing air quality. (6) Randomness of wheat straw burning activities renders random outbreak of air pollution of this type. Regional and extensive wheat straw burning activities can cause serious air pollution event.