Coupling Measurements of Biogenic Volatile Organic Compounds and Ozone Reactivity in the Field

The concentration and fate of ozone in the troposphere is dependent on the ratio of volatile organic compounds (VOCs) and NOx gases emitted from both anthropogenic and biogenic sources. The biosphere emits over 1,000 Tg of VOCs annually, over half of which come from vegetation. The ‘fingerprint’ of chemical compounds emitted varies greatly both between and within vegetative species. This fingerprint is greatly influenced by the environmental conditions an individual plant is exposed to.  In a changing climate, rising atmospheric CO₂ concentration is expected to significantly change the quantity and variation of BVOC emissions from vegetation; and thus, the fate of tropospheric O₃ concentrations.

This study uses a coupled deployment of a Total Ozone Reactivity System (TORS) and Proton-Transfer-Reaction Mass-Spectrometer (PTR-MS)

At BIFoR FACE (Birmingham Institute for Forest Research Free Air Carbon Dioxide Enrichment) under both ambient and elevated CO₂ to assess the impact of rising CO₂ on both BVOC emissions and ozone chemistry. Our results show a clear diurnal trend with key ozone reactive BVOCs and ozone reactivity. Interestingly, our study showed a variation in morning and afternoon activity, with isoprene and monoterpene emissions predominantly in the afternoon, with a variation of both BVOC emission and ozone reactivity profile seen in the mornings.