Atmospheric Fate of Carbonyl Oxidation Products Originating from α-Pinene and Δ³-Carene:  Determination of Rate of Reaction with OH and NO₃ Radicals, UV Absorption Cross Sections, and Vapor Pressures

Abstract

Large yields of dicarbonyl compounds have been found in the atmospheric oxidation of R-pinene and ∆ 3 -carene. These terpenes are emitted in large quantities by biogenic sources, and it is important to know the fate of their reaction products. In this investigation, ultraviolet and infrared absorption cross sections, vapor pressures, and rate coefficients for hydroxyl and nitrate radical reactions have been determined for the main product in each case, i.e., 3-acetyl-2,2-dimethylcyclobutaneacetaldehyde (pinonaldehyde) and 2,2-dimethyl-3-(2-oxopropyl)cyclopropaneacetaldehyde (caronaldehyde). Photolysis lifetimes at noon on July 1 at 50°N using a photolysis quantum yield of 1 are 3.3 h for pinonaldehyde and 5.8 h for caronaldehyde. The infrared absorption cross sections obtained (base e) were (8.08 ( 0.32) × 10 -19 and (1.04 ( 0.05) × 10 -18 cm 2 molecule -1 for pinonaldehyde and caronaldehyde at 1725.4 and 1741.5 cm -1 , respectively. Vapour pressures determined by Knudsen effusion measurements are 5.1 and 3.0 Pa at 298 K. The rate coefficients obtained using the relative rate technique for reaction with OH radicals were (8.72 ( 1.14) × 10 -11 and (1.21 ( 0.36) × 10 -10 molecules cm -3 s -1 for pinonaldehyde and caronaldehyde and for the corresponding NO 3 reactions were (2.35 ( 0.37) × 10 -14 and (2.71 ( 0.15) × 10 -14 molecules cm -3 s -1 . The vapor pressures are too high for homogenous nucleation or direct condensation to take place in the atmosphere. The dominant gas-phase removal processes will be reaction with OH radicals and possibly also photodissociation.

Temperature dependence of yields of secondary organic aerosols from the ozonolysis of <i>α</i>-pinene and limonene

“…While closer to the expected range this value is still low. On the other hand, applying the vapour pressure recently estimated by Tillmann et al (2009), which is about two to three orders of magnitude smaller than the value reported by Hallquist et al (1997), the results are almost consistent with the two product approach. However, since the vapour pressure of pinonaldehyde still seems to have substantial uncertainty this compound was not included explicitly into the model analysis presented in this paper.…”

“…Using the PTR-MS measurements we could indeed observe an increasing partitioning of pinonaldehyde into the condensed phase with decreasing temperature and hence a larger contribution to the semivolatile SOA fraction (Tillmann et al, 2009). Including pinonaldehyde in our model analysis with the molar yields determined by Tillmann et al (2009) but relying on the vapour pressure parameterisation derived by Hallquist et al (1997) leads to a stronger temperature dependence of the vapour pressure of the remaining effective semivolatile SOA component as reflected by an increase of the evaporation enthalpy to about 34 kJ mol −1 . While closer to the expected range this value is still low.…”

“…At 303 K the vapour pressures of the less and more volatile SOA forming compounds are within the same order of magnitude and comparable to vapour pressures at 296 K of pinic acid (3.2×10 −10 bar), cis-pinonic acid (7×10 −10 bar) and trans-norpinic acid (1.3×10 −9 bar) (Bilde and Pandis, 2001), but well below the vapour pressures of the semivolatile compound pinonaldehyde. The vapour pressure of pinonaldehyde was measured to be 5.1×10 −5 bar at 298 K and 7×10 −6 bar at 243 K (Hallquist et al, 1997) but a recent analysis resulted in lower values of 10 −7 to 10 −9 bar at 303 K (Tillmann et al, 2009). Consequently, either of the two effective SOA forming products may represent the product class of acid or diacid products while it is unrealistic to compare with the much more volatile compounds with only carbonyl functional groups (Capouet and Müller, 2006).…”

“…pinonaldehyde (75.5±5.6) kJ mol −1 (Hallquist et al, 1997), pinic acid (109±21) kJ mol −1 (Bilde and Pandis, 2001), transnorpinic acid, (42±51) kJ mol −1 (Bilde and Pandis, 2001), and straight chain C3-C9 diacids 91-184 kJ mol −1 (Bilde et al, 2003;Chattopadhyay and Ziemann, 2005). The value is also lower than effective evaporation enthalpies of about 33-43 kJ mol −1 determined for SOA from the photooxidation of α-pinene (Offenberg et al, 2006), values of 42-104 kJ mol −1 as estimated by Sheehan and Bowman (2001), and a value of 38 kJ mol −1 obtained by analysis of datasets from 7 different groups (Svendby et al, 2008).…”

A group contribution method for estimating the vapour pressures of α-pinene oxidation products

“…The vapour pressures of its oxidation products range from 10 −2 torr to 10 −7 torr (Hallquist et al, 1997;Hoffmann et al, 1997;Bilde and Pandis, 2001). The least volatile of these products can enter the aerosol phase and form secondary organic aerosol (SOA) (Kanakidou et al, 2005).…”