Journal cover Journal topic
Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
Atmos. Chem. Phys., 16, 4101-4118, 2016
https://doi.org/10.5194/acp-16-4101-2016
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
30 Mar 2016
Hygroscopic behavior of multicomponent organic aerosols and their internal mixtures with ammonium sulfate
Bo Jing1,2,*, Shengrui Tong1,*, Qifan Liu1, Kun Li1, Weigang Wang1, Yunhong Zhang2, and Maofa Ge1 1Beijing National Laboratory for Molecular Sciences (BNLMS), State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
2The Institute of Chemical Physics, School of Chemistry, Beijing Institute of Technology, Beijing 100081, China
*These authors contributed equally to this work.
Abstract. Water-soluble organic compounds (WSOCs) are important components of organics in the atmospheric fine particulate matter. Although WSOCs play an important role in the hygroscopicity of aerosols, knowledge on the water uptake behavior of internally mixed WSOC aerosols remains limited. Here, the hygroscopic properties of single components such as levoglucosan, oxalic acid, malonic acid, succinic acid, phthalic acid, and multicomponent WSOC aerosols mainly involving oxalic acid are investigated with the hygroscopicity tandem differential mobility analyzer (HTDMA). The coexisting hygroscopic species including levoglucosan, malonic acid, and phthalic acid have a strong influence on the hygroscopic growth and phase behavior of oxalic acid, even suppressing its crystallization completely during the drying process. The phase behaviors of oxalic acid/levoglucosan mixed particles are confirmed by infrared spectra. The discrepancies between measured growth factors and predictions from Extended Aerosol Inorganics Model (E-AIM) with the Universal Quasi-Chemical Functional Group Activity Coefficient (UNIFAC) method and Zdanovskii–Stokes–Robinson (ZSR) approach increase at medium and high relative humidity (RH) assuming oxalic acid in a crystalline solid state. For the internal mixture of oxalic acid with levoglucosan or succinic acid, there is enhanced water uptake at high RH compared to the model predictions based on reasonable oxalic acid phase assumption. Organic mixture has more complex effects on the hygroscopicity of ammonium sulfate than single species. Although hygroscopic species such as levoglucosan account for a small fraction in the multicomponent aerosols, they may still strongly influence the hygroscopic behavior of ammonium sulfate by changing the phase state of oxalic acid which plays the role of "intermediate" species. Considering the abundance of oxalic acid in the atmospheric aerosols, its mixtures with hygroscopic species may significantly promote water uptake under high RH conditions and thus affect the cloud condensation nuclei (CCN) activity, optical properties, and chemical reactivity of atmospheric particles.

Citation: Jing, B., Tong, S., Liu, Q., Li, K., Wang, W., Zhang, Y., and Ge, M.: Hygroscopic behavior of multicomponent organic aerosols and their internal mixtures with ammonium sulfate, Atmos. Chem. Phys., 16, 4101-4118, https://doi.org/10.5194/acp-16-4101-2016, 2016.
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Water-soluble organic compounds (WSOCs) play an important role in the hygroscopicity of aerosols. The coexisting hygroscopic species such as levoglucosan, malonic acid, and phthalic acid have a strong influence on hygroscopic growth and phase behavior of oxalic acid, even suppressing its crystallization completely. The hygroscopic species such as levoglucosan in the mixed particles may significantly influence the hygroscopic behavior of ammonium sulfate by changing phase state of oxalic acid.
Water-soluble organic compounds (WSOCs) play an important role in the hygroscopicity of...
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