Changes in PM2.5 peat combustion source profiles with atmospheric aging in an oxidation flow reactor

• Published in: Atmospheric Measurement Techniques
• Main Authors: Chow, Judith C., Cao, Junji, Chen, L. -W. Antony, Wang, Xiaoliang, Wang, Qiyuan, Tian, Jie, Sai, Steven, Ho, Hang, Watts, Adam C., Carlson, Tessa B., Kohl, Steven D., Watson, John G.
• Format: Report
• Language: English
• Published: COPERNICUS GESELLSCHAFT MBH 2019
• Subjects: FINE PARTICULATE MATTER; HETEROGENEOUS OXIDATION; ORGANIC AEROSOL; SOURCE APPORTIONMENT; CHAMBER EXPERIMENTS; CENTRAL KALIMANTAN; RADICAL CHEMISTRY; EMISSION FACTORS; CARBON; MASS; Meteorology & Atmospheric Sciences; Alaska; Siberia
• Online Access: http://ir.ieecas.cn/handle/361006/13292; http://ir.ieecas.cn/handle/361006/13293; https://doi.org/10.5194/amt-12-5475-2019

Smoke from laboratory chamber burning of peat fuels from Russia, Siberia, the USA (Alaska and Florida), and Malaysia representing boreal, temperate, subtropical, and tropical regions was sampled before and after passing through a potential-aerosol-mass oxidation flow reactor (PAM-OFR) to simulate intermediately aged (similar to 2 d) and well-aged (similar to 7 d) source profiles. Species abundances in PM2.5 between aged and fresh profiles varied by several orders of magnitude with two distinguishable clusters, centered around 0.1% for reactive and ionic species and centered around 10% for carbon. Organic carbon (OC) accounted for 58%-85% of PM2.5 mass in fresh profiles with low elemental carbon (EC) abundances (0.67%-4.4%). OC abundances decreased by 20%-33% for well-aged profiles, with reductions of 3%-14% for the volatile OC fractions (e.g., OC1 and OC2, thermally evolved at 140 and 280 degrees C). Ratios of organic matter (OM) to OC abundances increased by 12%-19% from intermediately aged to well-aged smoke. Ratios of ammonia (NH3) to PM2.5 decreased after intermediate aging. Well-aged NH4+ and NO3 abundances increased to 7%-8% of PM2.5 mass, associated with decreases in NH3, low-temperature OC, and levoglucosan abundances for Siberia, Alaska, and Everglades (Florida) peats. Elevated levoglucosan was found for Russian peats, accounting for 35%-39% and 20%-25% of PM2.5 mass for fresh and aged profiles, respectively. The water-soluble organic carbon (WSOC) fractions of PM2.5 were over 2-fold higher in fresh Russian peat (37.0 +/- 2.7%) than in Malaysian (14.6 +/- 0.9%) peat. While Russian peat OC emissions were largely water-soluble, Malaysian peat emissions were mostly water-insoluble, with WSOC / OC ratios of 0.59-0.71 and 0.18-0.40, respectively. This study shows significant differences between fresh and aged peat combustion profiles among the four biomes that can be used to establish speciated emission inventories for atmospheric modeling and receptor model source apportionment. A sufficient aging time ...