10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
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Toxicological and Chemical Characteristics of Fine Particles from Burning of Crop Residues in China
KIN‐FAI HO, Jian Sun, Haiyan Ni, Jie Tian, Yongming Han, Junji Cao, Hsiao-Chi Chuang, The Chinese University of Hong Kong
Abstract Number: 243 Working Group: Combustion
Abstract Crop residue burning is a major source of fine particulate matter and arouses significant concern in China and worldwide due to its adverse impacts on environment and human health. Five types of crop residue (rice straw, wheat straw, corn straw, sugarcane straw and sorghum straw) were selected and burned in a laboratory combustion chamber to mimic the combustion process. Total 28 sets of PM2.5 samples were collected to determine their chemical and toxicological characteristics. Human lung alveolar epithelial A549 cells were exposed to PM2.5 at concentrations of 0, 20, and 150 µg/ml for 24 hours. The cell viability and toxicity were measured by the trypan blue dye exclusion assay and lactate dehydrogenase (LDH) / interleukin 6 (IL- 6) release, respectively. Burning of wheat straw emitted the highest level of PM2.5 while sugarcane and sorghum straw emitted the lowest. Carbonaceous species, organic carbon (OC) and elemental carbon (EC), were the dominant components in all samples which contributed ~50% of PM2.5 in total. The ratios of OC/EC from crop residue burning ranged from 8.8 to 31.0 which were significantly higher than those emitted from wood and fossil fuel burning. Potassium (K+) and chloride (Cl-) are dominant water-soluble ions from crop residues burning, with an average abundance of 6.4 ± 4.4% and 14.5 ± 8.2% in PM2.5, respectively. Exposure to PM2.5 at the concentration of 20 μg/ml to 150 μg/ml decreased cell viability and increased LDH / IL-6 release. Strong negative correlations were found between cell viability and OC (R = -0.66) and some heavy metals such as Cr, Mn, Fe, and Ba (R < 0.65). Moreover, OC, Cr, Mn, Fe and Ba also showed strong positive correlations with LDH and IL-6 responses. However, PM2.5 samples emitted from burning of sorghum straw showed the lowest levels of LDH and IL-6 (150 µg/ml exposure) which may be due to the lower abundance of OC and heavy metals in PM2.5. In conclusion, our data indicate that PM2.5 emitted from biomass burning contained high concentrations of OC and toxic metals which were strongly correlated to cell viability and inflammatory responses. The findings suggest a need to control the burning of crop residues which can induce significant health impact on human being.