Study On Black Carbon Aerosol Emissions From Crop Straw Open Burning And Its Environmental Impact On The Yangtze River Delta Region

The Yangtze River Delta region is composed by25cities located in Shanghai, Jiangsu and Zhejiang,which is an important agricultural commodity base, farming dominated. Large amounts of crop strawsare annually produced, with a lot of crop straws being open burned, causing serious air pollution，which has become a regional problem.Based on literature research, the research on black carbon emissions of crop straw burning is rarenow. In the study, we used crop yield data of25cities to estimate the open burning amount of cropstraw in the region, using Straw to Grain Ratio(S/G), the proportion of crop straw burning of differentcounties，emission factor(EF) of BC. Spatial and temporal distribution of straw burning amounts andBC emissions are analyzed. Based on this, we evaluated the impact of straw burning on regionalenvironmental quality after the analysis of the temporal and spatial distribution of the MODIS fire spotsand Air Pollution Index (API).Firstly, the yields of the three major crops of rice, wheat, corn are gathered in consideration of thespecial planting structure in the region. The crop straw resources in different counties are obtained byusing S/G of three major crops. Straw burning proportion is calculated in accordance with the level oflocal economy and farmers’ income situation, so BC emissions are derived using EF of BC and strawburning amounts in different counties.The crop straw resources of the YRD region in2010are52.78million tons, with the burningamount of9.61million tons, accounting for19%of the total amount. The result obtained is lowcompared with similar literature. There are obvious regional character of straw burning with the mainburning area in Jiangsu Province, especially its northern part.Then we carried out the analysis of temporal and spatial evolution of the fire spots, with the use ofMODIS fire data during wheat harvest season on June of2010in the YRD region. The result shows thatthere are682fire spots during the harvest season.53counties in Jiangsu and15counties of Zhejiang arecovered, with a very large burning area, and the distribution concentrated, mainly in the north of JiangsuProvince. The distribution of fire spot is highly related with the division of administrative boundariesand supervision of local government. The evolution of fire spot distribution is fully consistent with thewheat harvest season of the Jiangsu Province. Finally, the relevance of the fire spots with API distribution is analyzed, combined with the APIdata from28routine air monitoring stations during the wheat harvest of2010in Jiangsu province.Result shows that the fire intensive areas are in good agreement with the move of API high-value areas.The straw burning contributed a lot in the changing of API, and it leads to the accumulation ofpollutants with the calm weather near the surface.