Agricultural Fires and Their Potential Impacts on Regional Air Quality over China

The potential impacts of agricultural fires (agri-fires) on regional air quality over China were examined using active fire products derived from satellite remote sensing and air mass trajectory modeling from 2009 to 2010. Agri-fires were found in most administrative areas. More than 80% of the agri-fires were in the heartlands of agricultural regions such as Anhui, Jiangsu, Shandong and Henan Provinces. Agri-fires had a seasonal pattern, with two distinct peaks in summer and autumn harvest periods, especially in June (61-86%) and October (5-14%). Agri-fire smoke was transported in the atmosphere on a continental scale in three directions, moving northeasterly, northwesterly and southwesterly away from source areas. Particles from agri-fire smoke contributed more than 35% of aerosol optical depth (AOD) over regions of the Jiaodong Peninsular, the North Plain, East China and other areas, and exceeded 60% in some areas of Shandong, Henan and Jiangsu Provinces. In the boundary layer atmosphere, particles from agri-fire smoke contributed more than 29% of PM10 in parts of Anhui, Jiangsu and Shandong Provinces. Due to agri-fires the amount of PM10 was highly correlated (R-2 = 0.6) with the smoke air masses in the main potential sink regions, and the mean PM10 during the summer harvest of 2010 reached 0.24 mg/m(3), far higher than the adjacent periods without smoke.