A new source of methylglyoxal in the aqueous phase

Abstract

Abstract. Carbonyl compounds are ubiquitous in atmospheric multiphase system participating in gas, particle, and aqueous-phase chemistry. One important compound is methyl ethyl ketone (MEK), as it is detected in significant amounts in the gas phase as well as in cloud water, ice, and rain. Consequently, it can be expected that MEK influences the liquid-phase chemistry. Therefore, the oxidation of MEK and the formation of corresponding oxidation products were investigated in the aqueous phase. Several oxidation products were identified from the oxidation with OH radicals, including 2,3-butanedione, hydroxyacetone, and methylglyoxal. The molar yields were 29.5 % for 2,3-butanedione, 3.0 % for hydroxyacetone, and 9.5 % for methylglyoxal. Since methylglyoxal is often related to the formation of organics in the aqueous phase, MEK should be considered for the formation of aqueous secondary organic aerosol (aqSOA). Based on the experimentally obtained data, a reaction mechanism for the formation of methylglyoxal has been developed and evaluated with a model study. Besides known rate constants, the model contains measured photolysis rate constants for MEK (kp = 5 × 10−5 s−1), 2,3-butanedione (kp = 9 × 10−6 s−1), methylglyoxal (kp = 3 × 10−5 s−1), and hydroxyacetone (kp = 2 × 10−5 s−1). From the model predictions, a branching ratio of 60 /40 for primary/secondary H-atom abstraction at the MEK skeleton was found. This branching ratio reproduces the experiment results very well, especially the methylglyoxal formation, which showed excellent agreement. Overall, this study demonstrates MEK as a methylglyoxal precursor compound for the first time.

Description and evaluation of a detailed gas-phase chemistry scheme in the TM5-MP global chemistry transport model (r112)

“…All applications of TM5 share the same methods for model discretization and operator splitting (Krol et al, 2005), the treatment of the meteorological fields, and the mass-conserving tracer transport (Bregman et al, 2003). TM5-MP is driven by meteorological fields from the ECMWF ERA-Interim reanalysis (Dee et al, 2011) with an update frequency of 3 h. The advection scheme used is based on the slopes scheme (Russell and Lerner, 1981), and deep and shallow cumulus convection is parameterized according to Tiedtke (1989). The performance of the transport in the model has been evaluated by Peters et al (2004) using sulfur hexafluoride simulations and by analyzing the vertical and horizontal distribution of radon ( 222 Rn) (Koffi et al, 2016;Williams et al, 2017).…”

Toxicological Responses of α-Pinene-Derived Secondary Organic Aerosol and Its Molecular Tracers in Human Lung Cell Lines

“…First-generation oxidation products of α-pinene that have been measured in SOA include pinonaldehyde as well as pinic, pinonic, and 10-hydroxypinonic acids. − Another important molecular marker for α-pinene-derived SOA formation is 3-methyl-1,2,3-butanetricarboxylic acid (MBTCA), which is formed via • OH oxidation of pinonic acid. , In addition to aldehydes and carboxylic acids, α-pinene SOA may contain organic peroxides, dimer esters, , organosulfates, and/or extremely low-volatility organic compounds (ELVOCs) . ELVOCs are believed to form from the autoxidation of first-generation peroxy radicals (RO 2 • ) generated by either α-pinene + O 3 or α-pinene + • OH reactions .…”

Atmospheric mixing ratios of methyl ethyl ketone (2-butanone) in tropical, boreal, temperate and marine environments

“…Due to its high solubility in water and its relatively long lifetime, MEK could potentially influence gas-aqueous reactions on aerosol surfaces (Nozière, 2005). This has been shown indirectly by the production of methyl glyoxal after its oxidation by OH, having implications for the formation of organics in the aerosol aqueous phase (Rodigast et al, 2016).…”