Emissions of polychlorinated-p-dibenzo dioxin, dibenzofurans (PCDD/Fs) and polybrominated diphenyl ethers (PBDEs) from rice straw biomass burning

Biomass burning in Asia has been widely studied owing to its adverse effects on visibility, human health, and global climate. However the impact of rice straw burning on polychlorinated dibenzo-p-dioxin and dibenzofurans (PCDD/Fs) and polybrominated diphenyl ethers (PBDEs) concentrations is not known. In this study concentrations of these pollutants were measured at a farm site and two nearby sites during rice straw (open) burning and non-burning periods. During non-burning periods atmospheric PCDD/F and PBDE concentrations ranged from 0.0263 to 0.0329 pg I-TEQ/Nm3 and 43.5 to 58.3 pg/Nm3 respectively, and were similar at all of the sites. During rice straw burning periods PCDD/F and PBDE concentrations measured near the combustion (farm) site increased dramatically by six to twenty times. The strong correlation between the natural logarithm of PBDE and PCDD/F concentrations (r = 0.949, p < 0.01) at each site indicates that the elevated PCDD/Fs and PBDEs were due to emissions from the rice straw burning. The calculated emission factors, determined using the burned carbon method and the Industrial Source Complex Short-Term Dispersion Model (ISCST3), ranged from 12.6 to 14.5 ng TEQ/kg Cburned and 11.7 to 14.5 μg/kg Cburned, for PCDD/Fs and PBDEs respectively. The PBDE emission factors were at least 38 times higher than those of PCDD/Fs, revealing that rice straw burning is an important PBDE emission source.