Sulfate Formation in Incense Burning Particles: A Single-Particle Mass Spectrometric Study
ZHANCONG LIANG, Liyuan Zhou, Rosemarie Ann Infante Cuevas, Xinyue Li, Chunlei Cheng, Mei Li, Rongzhi Tang, Ruifeng Zhang, Patrick Kwan Ho Lee, Alvin Chi Keung Lai, Chak K. Chan, King Abdullah University of Science and Technology
Abstract Number: 273
Working Group: Aerosol Chemistry
Abstract
Incense burning, a common form of the residential biomass burnings, emits substantial amounts of particles. These particles are subject to atmospheric aging upon exposure to sunlight and other pollutants. In this work, we observed sulfate formation in fresh incense particles upon exposure to SO2, using a single-particle aerosol mass spectrometer (SPAMS). The analysis of the positive mass spectra classified the particles as K-type and OC-type. In both dark and light experiments, SO2 uptake and oxidation were found preferentially in OC-type particles over K-type particles. Sulfate formation, as represented by the number fraction of sulfate-containing particles (FS), was likely due to gaseous oxidants under dark. FS increased with UV, mainly attributable to photosensitization reactions. While more sulfate formed at higher relative humidities (RH) under dark, sulfate formation under light was independent of RH. The increase in FS due to photochemistry was more effective under lower RH, where the photoactive compounds were more concentrated and likely generated more photo-oxidants. This effect outweighed that due to reduced SO2 dissolution. Our findings shed light on the potential of biomass burning particles to trigger sulfate formation, at a single-particle level.