Emission inventory of carbonaceous pollutants from biomass burning in the Pearl River Delta Region, China

Emissions from burning major agricultural residue were measured through laboratory simulations using a self-designed dilution chamber system. Emission factors of CO2, CO, non-methane hydrocarbons (NMHCs), oxygenated volatile organic compounds (OVOCs), PM10, PM2.5, OC and EC in PM2.5 were measured for burning rice straw in flaming and smoldering combustion, and for burning of sugarcane leaves. NMHCs emitted from crop straw open burning were dominated by C2 hydrocarbons (ethene, ethane, ethyne), contributing (53.4 ± 4.6)% in volume in rice straw burning emissions and 41.8% in sugarcane burning emissions, respectively. Acetone and aldehyde were major OVOCs species in open straw burning emissions. A survey was conducted to determine the fraction of field crop biomass burned during harvesting season and the amounts of household firewood and crop residue consumption in 2008. Information obtained from the survey, together with measured EFs for field burning of rice straw and sugarcane, and EFs from literatures for field burning of other agricultural residues, biofuel combustion and forest fires, were used in developing the source inventories of carbonaceous pollutants in the PRD region. The annual emissions of CO, VOCs (including NMHCs and OVOCs), NOx, PM2.5, OC and EC from burning biomass were estimated to be 186.38, 15.94, 4.93, 15.56, 7.10, 2.25 kt in the year 2008, respectively. These estimates are lower than previously published estimates by 23–63%. Open burning patterns (flaming and smoldering) and rural biofuel use contribute to the differences. Field burning of straw contributed mainly to VOCs, PM2.5 and OC emissions while the residential sector was the dominant source of EC, CO and NOx. The contributions of biomass burning to entire PRD emissions are estimated as 3.37–6.53%, respectively, for PM, and 1.82–3.17%, respectively, for VOCs, and 0.52–2.77%, respectively, for NOx.