EGU21-11439, updated on 04 Mar 2021
https://doi.org/10.5194/egusphere-egu21-11439
EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Hygroscopicity of HULIS in urban aerosol and its relationship with sources

Ruichen Zhou1, Yange Deng1, Bhagawati Kunwar2, Qingcai Chen3, Jing Chen4, Lujie Ren5, Petr Vodicka2, Dhananjay Deshmukh2, Pingqing Fu5, Kimitaka Kawamura2, and Michihiro Mochida1,6
Ruichen Zhou et al.
  • 1Graduate School of Environmental Studies, Nagoya University, Nagoya, Japan
  • 2Chubu Institute for Advanced Studies, Chubu University, Kasugai, Japan
  • 3School of Environmental Science and Engineering, Shaanxi University of Science and Technology, Xi’an, China
  • 4School of Environmental Science and Engineering, Tianjin University, Tianjin, China
  • 5Institute of Surface-Earth System Science, School of Earth System Science, Tianjin University, Tianjin, China
  • 6Institute for Space-Earth Environmental Research, Nagoya University, Nagoya, Japan

Atmospheric aerosol affects the Earth’s radiation budget by directly scattering and absorbing solar radiation and indirectly acting as cloud condensation nuclei. Both of the effects are responsible for the uncertainties in the prediction of global climate change. A better understanding of the hygroscopicity of the organic aerosol is important because it is poorly characterized to date. In this study, the hygroscopicity of humic-like substances (HULIS), a ubiquitous mixture of water-soluble organic matter, isolated from aerosol samples collected in Beijing in different seasons, was measured using a hygroscopicity tandem differential mobility analyzer (HTDMA). The hygroscopicity parameter of the isolated HULIS fraction (κHULIS) was in the range of 0.03–0.13 (mean: 0.06). Considering the possible influence from small amounts of inorganic salts, the hygroscopicity parameter of pure organic HULIS (κ*HULIS) was found to be slightly lower (0–0.11, mean: 0.04). The κHULIS showed a seasonal variation; the values were highest in summer (0.08), followed by spring (0.06), autumn (0.06), and winter (0.04). The κ*HULIS showed a similar seasonal variation, with the highest and lowest values in summer (0.07) and autumn (0.01), respectively. Both κHULIS and κ*HULIS were correlated positively with the O/C ratio of the HULIS. Comparison of the hygroscopicity parameter values with factors from positive matrix factorization (PMF) analysis of the mass spectra of the HULIS fractions showed that κHULIS correlated positively with more-oxidized oxygenated organic aerosol (MO-OOA) and less-oxidized OOA (LO-OOA), and correlated negatively with cooking-like OA (COA) and biomass burning OA (BBOA). The relationship between the hygroscopicity parameter and sources was further explored based on a multi-liner regression analysis. The variation in the hygroscopicity of HULIS and its connection to sources provide an insight into the contribution of organics to aerosol hygroscopicity, toward a better understanding of its link to climate.

How to cite: Zhou, R., Deng, Y., Kunwar, B., Chen, Q., Chen, J., Ren, L., Vodicka, P., Deshmukh, D., Fu, P., Kawamura, K., and Mochida, M.: Hygroscopicity of HULIS in urban aerosol and its relationship with sources, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-11439, https://doi.org/10.5194/egusphere-egu21-11439, 2021.

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