Modeling of gaseous methylamines in the global atmosphere: impacts of oxidation and aerosol uptake

Abstract

Abstract. Gaseous amines have attracted increasing attention due to their potential role in enhancing particle nucleation and growth and affecting secondary organic aerosol formation. Here we study with a chemistry transport model the global distributions of the most common and abundant amines in the air: monomethylamine (MMA), dimethylamine (DMA), and trimethylamine (TMA). We show that gas phase oxidation and aerosol uptakes are dominant sinks for these methylamines. The oxidation alone (i.e., no aerosol uptake) leads to methylamine lifetimes of 5-10 h in most parts of low and middle latitude regions. The uptake by secondary species with uptake coefficient (γ ) of 0.03 (corresponding to the uptake by sulfuric acid particles) reduces the lifetime by ∼30 % over oceans and much more over the major continents, resulting in a methylamine lifetime of less than 1-2 h over central Europe, eastern Asia, and eastern US. With the estimated global emission flux, from the literature, our simulations indicate that [DMA] in the model surface layer over major continents is generally in the range of 0.1-2 ppt (parts per trillion) when γ = 0.03 and 0.2-10 ppt when γ = 0, and decreases quickly with altitude.[DMA] over oceans is below 0.05 ppt and over polar regions it is below 0.01 ppt. The simulated [MMA] is about a factor of ∼2.5 higher while [TMA] is a factor of ∼8 higher than [DMA]. The modeled concentrations of methylamines are substantially lower than the limited observed values available, with normalized mean bias ranging from −57 (γ = 0) to −88 % (γ = 0.03) for MMA and TMA, and from −78 (γ = 0) to −93 % (γ = 0.03) for DMA.

Seasonal variation of fine- and coarse-mode nitrates and related aerosols over East Asia: synergetic observations and chemical transport model analysis

“…A CTM incorporating advanced particle microphysics is one potential option (Yu and Luo, 2014). Such a modeling approach, incorporating interactions with mineral dust and sea salt, has not yet been fully explored in East Asia and is a future research direction.…”

Adsorption of Methylamine at the Surface of Ice. A Grand Canonical Monte Carlo Simulation Study

“…14 More generally, amines have attracted increasing attention due to their potential role in enhancing aerosol nucleation rates in the lower troposphere. 15 Because low-molecular weight amines are highly water-soluble, a few studies have been devoted to their interaction with liquid water in order to better characterize their likely dissolution in aqueous aerosols at high temperature, and thus their gas/particle partitionning. [14][15][16] By contrast, very little is known about their interaction with ice surfaces as encountered in high-altitude cirrus clouds or snow flakes.…”

“…15 Because low-molecular weight amines are highly water-soluble, a few studies have been devoted to their interaction with liquid water in order to better characterize their likely dissolution in aqueous aerosols at high temperature, and thus their gas/particle partitionning. [14][15][16] By contrast, very little is known about their interaction with ice surfaces as encountered in high-altitude cirrus clouds or snow flakes. As a consequence, the thermodynamic and kinetic properties of amines in the atmosphere are not well quantified and only few atmospheric models incorporate them although they are ubiquitous.…”

High resolution modeling of gaseous methylamines over a polluted region in China: Source-dependent emissions and implications to spatial variations

“…In this regard, numerical models can be useful in simulating the distributions of amines on regional or global scales. To our knowledge, only three modeling studies of amines have been reported in the literature, all on a global scale (Myriokefalitakis et al, 2010;Yu and Luo, 2014;Bergman et al, 2015). Myriokefalitakis et al (2010) investigated the potential contribution of amines 20 emitted from oceans to secondary organic formation (SOA) formation, assuming total amine emissions to be one-tenth of the oceanic ammonia emissions.…”