Determination of carbon balances for smog chamber terpene oxidation experiments using a 14C tracer technique

Abstract

In the last decade, numerous studies of monoterpene hydrocarbons in the presence of ozone and oxides of nitrogen have been completed. Although insights about the reactivity of terpenes have been gained, and several products have been identified in the gas and aerosol phases, carbon balances have been generally poor. This paper describes a radiotracer technique which accounts for carbon-containing compounds in a smog chamber at the conclusion of a photooxidation or ozonolysis reaction. Instead of attempting to identify individual products, gas-phase compounds were separated from aerosols, and each phase was analyzed by a liquid scintillation counter. A carbon balance of 79 to 97% was obtained with 14C-~-pinene and ozone using this technique. The significance of the results are discussed in terms of the l*C-a-pinene concentrations used in this study, which were lower than concentrations used previously by one to four orders of magnitude. In spite of the lower concentrations, the gaseous and aerosol fractions observed in the present investigation are comparable to those observed by others. Possible reaction products are discussed with respect to likely mechanisms for a-pinene oxidation.

Mass balance of gaseous and particulate products analysis from α‐pinene/NOx/air in the presence of natural sunlight

“…A new pathway is proposed to explain their formation. According to Hooker et al [1985], the abstraction of a tertiary hydrogen atom of carbonyl products leads to peroxy radicals formation (ROO) as shown in Figure 11 (pathway P1, PAHD panel)…”

Formation and chemical composition of atmospheric aerosols in an equatorial forest area

“…NH~ NO 3 K* Na* Na" Na" Na ÷ ' Na* from Dehnas and Servant (19821 hypothesized that some of them may rapidly undergo oxidation close to the source (Hooker et al, 1985); this is suggested by the physical data presented above. Important CO mixing ratios obtained in these regions indicate also a fast decomposition of numerous organic species (Zimmerman et al, 1978;Logan et al, 1981;Crutzen et al, 1985).…”

Conifer monoterpenes emitted to air by logging operations

“…In the monoterpene plume from conifer processing, nitrogen oxides required for efficient ozone formation are provided by the diesel engine. The ozonolysis of the monoterpenes also gives rise to immediate formation of radicals, aldehydes, peroxides and other potentially harmful photo-oxidants (Hooker et al, 1985;Gäbetal., 1985).…”