Effects of Elevated CO2 and O3 Concentrations on Isoprenoid Emissions from Pinus tabulaeformis
Isoprene and monoterpenes have indirect effects on ozone concentration, methane lifetime and aerosol formation. At the same time, the atmospheric composition change (reflected in elevated CO2 and O3 concentrations) can affect the speciation of monoterpenes / isoprenoids and magnitude of isoprene and monoterpenes fluxes. Ambient concentrations of CO2 and O3 were 342 μmolmol-1 and 40 nmolmol-1, respectively. The effects of elevated CO2 (700 μmolmol-1) and O3 (80 nmolmol-1) concentrations on isoprenoid emission rates and patterns from Pinus tabulaeformis were studied in open top chambers (OTCs). The released volatiles were quantified by thermal desorption and gas chromatography with flame ionization detector (GC-FID). The study showed that α-pinene was the main compound emitted from P tabulaeformis, accounting for more 51.5 - 72.6% of the detected volatile compounds. The emissions of isoprene and monoterpenes were reduced in response to elevated CO2 concentrations. Exposure to elevated O3 for 3 years significantly promoted the isoprene and monoterpenes emissions (p<0.05). Compared with ambient, elevated O3 concentration increased isoprene emission from P tabulaeformis by about 270.5 ± 13.5%. The response of monoterpene emission to elevated O3 may vary during the course of exposure to the pollutant. The patterns of monoterpene and isoprene emissions under combined elevated CO2 and O3 concentrations were similar to those under elevated CO2 concentration alone.
Fauziah Shahul Hamid, Seung-Bok Choi and Liyuan Han
D. W. Li et al., "Effects of Elevated CO2 and O3 Concentrations on Isoprenoid Emissions from Pinus tabulaeformis", Applied Mechanics and Materials, Vols. 522-524, pp. 264-271, 2014