Gaseous hydrocarbons - volatile organic compounds (VOCs) - are key atmospheric components. They may be air pollutants, harmful to human health in their own right, and some are greenhouse gases. Atmospheric chemical processing of VOCs leads to the formation of secondary pollutants such as ozone and secondary organic aerosol - which adversely affect health, damage vegetation (reducing crop yields by 5 - 15% globally) and affect climate. A quantitative understanding the atmospheric VOC budget underpins many aspects of atmospheric science.

This project developed a prototype ozone reactivity instrument, building upon a feasibility study carried out in our laboratory and has been tested with a system performance with individual VOC standards. The project then took complex VOC mixtures from plant specimens in laboratory enclosures, and demonstrated its applicability to assess the change in BVOC emissions from whole trees in response to environmental stress.

This latter objective was achieved through measurements at the internationally unique whole tree chambers at the Hawkesbury Forest Experiment (HFE) site in Richmond, NSW, where measured changes in total ozone reactivity from eucalyptus trees as a function of changing RH, temperature and CO2 abundance (400 ppm [i.e. present day] vs 640 ppm). Within the duration of the project, only limited experiments were undertaken - but provided a unique insight into the response of total BVOC emissions from vegetation to environmental change, underpinning future exploitation of the approach.

The project achieved technology readiness level (TRL) 4 - basic validation in a controlled environment. Following this proof-of-concept work (i.e. outside this proposal), we have identified an opportunity for initial field deployment of the technique, to perform the first measurements of total BVOC ozone reactivity in ambient air, from a mature Oak woodland under conditions of present day and anticipated future CO2 levels. VOC.