Abstract
Abstract. While ground-based works suggest the significance of in-cloud production (or aqueous formation) to oxalate, direct evidence is rare. With the in situ measurements performed at a remote mountain site (1690 m above sea level) in southern China, we first reported the size-resolved mixing state of oxalate in the cloud droplet residual (cloud RES), the cloud interstitial (cloud INT), and ambient (cloud-free) particles by single particle mass spectrometry. The results support the growing evidence that in-cloud aqueous reactions promote the formation of oxalate, with ∼ 15 % of the cloud RES and cloud INT particles containing oxalate in contrast to only ∼ 5 % of the cloud-free particles. Furthermore, individual particle analysis provides unique insight into the formation of oxalate during in-cloud processing. Oxalate was predominantly (> 70 % in number) internally mixed with the aged biomass-burning particles, highlighting the impact of biomass burning on the formation of oxalate. In contrast, oxalate was underrepresented in aged elemental carbon particles, although they represented the largest fraction of the detected particles. It can be interpreted by the individual particle mixing state that the aged biomass-burning particles contained an abundance of organic components serving as precursors for oxalate. Through the analysis of the relationship between oxalate and organic acids (−45[HCO2]−, −59[CH3CO2]−, −71[C2H3CO2]−, −73[C2HO3]−), the results show that in-cloud aqueous reactions dramatically improved the conversion of organic acids to oxalate. The abundance of glyoxylate associated with the aged biomass-burning particles is a controlling factor for the in-cloud production of oxalate. Since only limited information on oxalate is available in the free troposphere, the results also provide an important reference for future understanding of the abundance, evolution, and climate impacts of oxalate.
Highlights
In-cloud processing represents a large uncertainty in understanding the evolution and impact of secondary organic aerosols (SOA) on both environment and climate (Ervens et al, 2011; Ervens, 2015; Herrmann et al, 2015)
The average relative peak area (RPA) of oxalate in the cloud RES and cloud INT particles suppressed by a factor www.atmos-chem-phys.net/17/13891/2017/
Individual particle mixing state of oxalate in the cloud-free, cloud RES, and cloud INT particles obtained at a remote mountain site allows for the investigation of formation and evolution of oxalate
Summary
In-cloud processing represents a large uncertainty in understanding the evolution and impact of secondary organic aerosols (SOA) on both environment and climate (Ervens et al, 2011; Ervens, 2015; Herrmann et al, 2015). Dicarboxylic acids significantly contribute to SOA, aerosol acidity, and hygroscopicity and play an important role in atmospheric chemistry and cloud condensation nuclei (CCN; Ervens et al, 2011; Furukawa and Takahashi, 2011; Sorooshian et al, 2013). G. Zhang et al.: Insight into the in-cloud formation of oxalate water-soluble organic compounds downwind of the mainland China (Feng et al, 2012; Kawamura and Bikkina, 2016). Oxalate has great impact on the solubility, photochemistry and bioavailability of transition metals in aerosols (Johnson and Meskhidze, 2013; Ito and Shi, 2016)
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call