Abstract View
PM2.5 Characteristics in the Ammonia-Rich Agricultural Environment
JOONWOO KIM, Haebum Lee, Taewoong Gong, Jiho Jang, Dahye Oh, Kihong Park, Gwangju Institute of Science and Technology
Abstract Number: 345
Working Group: Remote and Regional Atmospheric Aerosol
Abstract
Gas-phase NH3, which is emitted from agricultural areas, plays a key role in atmospheric chemistry as the major basic gas. The NH3 neutralizes acidic gases, promotes secondary aerosol formation, and is converted to particulate NH4+ which contributes to the increases of PM2.5 mass and nanoparticle number concentrations. To characterize PM2.5 in the NH3-rich agricultural environment, we performed field measurements (point and mobile measurements) of aerosols and gases downwind of an intensive animal farming area in the summer of 2020. The average NH3 concentration was 81.7±84.3 ppb. The NH4+ completely neutralized anions in aerosols, indicating that the atmosphere was NHX-rich (NHX = NH3 + NH4+). The mass fraction of particulate NO3- in PM2.5 was as high as 21.9%, which is contrary to the sulfate-dominant PM2.5 in summer at urban sites. During the PM2.5 events, the nitrate oxidation ratio (NOR = [NO3-]/([NO2] + [NO3-])) doubled to ~0.5 and the ratio of water-soluble organic carbon to organic carbon increased. Excess NHX was likely to promote the formation of secondary aerosols, especially NO3-, and contributed to the increase of PM2.5 mass concentration. Further analyses on NH3 emissions from the source area, spatial distribution of fine particles, and their physical and chemical properties are in progress and will be presented.