AAAR 36th Annual Conference October 16 - October 20, 2017 Raleigh Convention Center Raleigh, North Carolina, USA
Abstract View
Minimal Water Uptake by Fresh Indonesian Peat Burning Particles is Governed by Limited Availability of Water Soluble Organic Matter
JING CHEN, Sri Hapsari Budisulistiorini, Masayuki Itoh, Wen-Chien Lee, Takuma Miyakawa, Yuichi Komzaki, LiuDongQing Yang, Mikinori Kuwata, Nanyang Technological University
Abstract Number: 724 Working Group: Aerosols, Clouds, and Climate
Abstract During last few decades, Indonesian peatland fires which include combustions of peat and vegetation (e.g., fern, acacia) have been recurrently happening. Particles emitted from peatland burning have significantly affected regional and global climate by complexly coupled aerosol-cloud-precipitation interactions. Accurate evaluations of these peat-burning-particle-driven effects require well characterized water uptake properties, yet they have been rarely explored. Here, we quantified water uptake by various types of fresh Indonesian peatland burning particles using the humidified tandem differential mobility analyzer (HTDMA). To link water uptake property with chemical composition, both the Aerodyne Time of Flight-Aerosol Chemical Speciation Monitor (ToF-ACSM) measurements and offline carbon analysis were conducted. The concurrent HTDMA and ToF-ACSM measurements were also performed for bulk water-soluble organic matter (WSOM) and its highly hydrophilic fraction classified with the 1-octanol-water partitioning method. We show that fresh peat burning particles are almost non-hygroscopic (mean hygroscopicity parameter, κ < 0.06) due to predominant contribution of water-insoluble organics. κ is greatly dependent on biomass types (e.g., mean κ = 0.08 (fern) and 0.04 (acacia)), likely determined by the variance in the water-soluble organic fraction. κ values for water extracts are high, especially for peat burning particles (bulk WSOM: κWSOM = 0.18, highly hydrophilic fraction: κH-HPHIL= 0.30). These results stress the importance of characterizing the bulk and highly hydrophilic water-soluble organic fractions in determining hygroscopicity of fresh peat burning particles. κ correlates positively (R = 0.89) with fraction of m/z 44 ion signal (f44), demonstrating the importance of highly oxygenated organic species to water uptake by peatland burning particles. Further, our study provides an experimentally validated reference for organics-dominated particle hygroscopicity, thus contributing to more accurate estimation of climate impacts caused by Indonesian peatland burning particles.