RESUMO
Wood and economic crops are still widely used in rural areas of China. Although their combustion is an important source of volatile organic compounds (VOCs), study on their emission characteristics is relatively weak. In this study, three kinds of wood (poplar, cedarwood, and citrus branches) and six economic crop straws (soybean stalk, sesame stalk, corn cob, cotton stalk, peanut stalk, and corn stalk) were selected and their burning was simulated in the laboratory. A dilution tunnel system was used to dilute the smoke, and then Tedlar bags were used to collect the smoke. The compositions of 102 VOCs were analyzed by Agilent 7820A/5977E gas chromatography/mass spectrometry. The ozone formation potential (OFP) of VOCs for different types of biomass burning was analyzed. The results indicated that there are differences in the VOC compositions of different types of biomass burning emissions. Ethane (11.1%), trans-2-pentene (15.4%), ethylene (8.3%), and dichloromethane (11.9%) are the main VOCs emitted from poplar and cedarwood burning. Toluene (49.8%) is the most abundant species of VOC emitted from burning of citrus branches. Ethylene (11.8%-17.5%) and acetone (9.2%-14.7%) are the main VOCs components of straw burning. Corn stalks, peanut stalks, and citrus branches have similar VOC source profiles, with the coefficient of divergence less than 0.1. The benzene/toluene ratio for biomass burning emissions obtained in this study and in the literature is in the range of 0.030-6.48. It is arguable that a value higher than 1 indicated the impact of biomass burning. The contributions of alkenens, oxygenated VOCs, and aromatic hydrocarbons to the OFP of biomass burning were 30.6%-80.3%, 6.5%-21.0%, and 3.8%-56.5%, respectively. The components contributing more than 10.0% to the OFP are ethylene, propylene, trans-2-pentene, cis-2-pentene, toluene, and propionaldehyde.
RESUMO
Inhalatory and dermal exposures of on-duty vehicle inspection workers to polycyclic aromatic hydrocarbons (PAHs) in Beijing were investigated from April 18 to May 17, 2011. Exposure levels to particulate PAHs for the vehicle inspection workers at gasoline, bus and diesel lines were found to be 56.07 ng m(-3), 111.72 ng m(-3) and 199.80 ng m(-3), respectively. A probabilistic risk assessment framework was integrated with the toxic equivalence factors (TEFs) and the incremental lifetime cancer risk (ILCR) approaches to quantitatively estimate the exposure risk for vehicle inspection workers of the three work lines. The median values of inhalation risk were estimated to be 3.7 × 10(-7), 5.0 × 10(-7) and 1.37 × 10(-6), respectively, while the median dermal ILCR values were 7.05 × 10(-6), 6.98 × 10(-6) and 1.28 × 10(-5), respectively for gasoline, bus, and diesel inspection workers. Total ILCR was higher than the acceptable risk level of 10(-6), indicating unacceptable potential cancer risk.