Water Uptake by Fresh Indonesian Peat Burning Particles is Limited by Water Soluble Organic Matter
Jing Chen1, Sri Hapsari Budisulistiorini1, Masayuki Itoh2, Wen-Chien Lee1,3, Takuma Miyakawa4, Yuichi Komzaki4, LiuDongQing Yang1, and Mikinori Kuwata1,21Earth Observatory of Singapore, Nanyang Technological University, Singapore 2Center for Southeast Asian Studies, Kyoto University, Japan 3Division of Chemistry and Biological Chemistry, Nanyang Technological University, Singapore 4Japan Agency for Marine Science and Technology, Japan
Received: 13 Feb 2017 – Accepted for review: 24 Mar 2017 – Discussion started: 27 Mar 2017
Abstract. The relationship between hygroscopic properties and chemical characteristics of Indonesian biomass burning (BB) particles, which are dominantly generated from peatland fires, was investigated using the humidified tandem differential mobility analyzer. In addition to peat, acacia (a popular species at plantation) and fern (a pioneering species after disturbance by fire) were used for experiments. Fresh Indonesian peat burning particles are almost non-hygroscopic (mean hygroscopicity parameter, κ < 0.06) due to predominant contribution of water-insoluble organics. The range of κ spans from κ = 0.02–0.04 (dry diameter = 100 nm, hereinafter) for Riau peat burning particles, while that for Central Kalimantan ranges from κ = 0.05–0.06. Fern combustion particles are more hygroscopic (κ = 0.08), whereas the acacia burning particles have a mediate κ value (0.04). These results suggest that κ is significantly dependent on biomass types. This variance in κ is partially determined by fractions of water soluble organic carbon (WSOC), as demonstrated by a correlation analysis (R = 0.65). κ of water soluble organic matter is also quantified, incorporating the 1-octanol-water partitioning method. κ values for the water extracts are high, especially for peat burning particles (A0 (a whole part of water-soluble fraction): κ = 0.18, A1 (highly water-soluble fraction): κ = 0.30). This result stresses the importance of both WSOC fraction and κ of water soluble fraction in determining hygroscopicity of organic aerosol particles. Values of κ correlate positively (R = 0.89) with fraction of m / z 44 ion signal quantified using a mass spectrometric technique, demonstrating the importance of highly oxygenated organic compounds in controlling hygroscopicity of Indonesian BB particles. These results can be further utilized for investigating environmental and climatic impacts of Indonesian BB particles in both regional and global scales.
Chen, J., Budisulistiorini, S. H., Itoh, M., Lee, W.-C., Miyakawa, T., Komzaki, Y., Yang, L., and Kuwata, M.: Water Uptake by Fresh Indonesian Peat Burning Particles is Limited by Water Soluble Organic Matter, Atmos. Chem. Phys. Discuss., doi:10.5194/acp-2017-136, in review, 2017.