Combined heat and ozone stress impacts on SOA formation and OH reactivity from oak emissions

Secondary organic aerosol (SOA) impacts climate by interactions with radiation and clouds. A globally important source of SOA is the oxidation of biogenic volatile organic compounds (BVOCs) emitted from terrestrial plants. Climate change is intensifying the frequency and severity of heat waves, subjecting plants to unprecedented stress from elevated temperatures and atmospheric pollutants, particularly ozone. However, the consequences of such abiotic stress on forest-derived SOA formation remain poorly understood, as stress conditions can significantly alter BVOC emission composition.

Current research gaps include limited studies examining SOA formation from authentic, complex plant emissions under realistic multi-stressor conditions that reflect actual environmental scenarios. To address this, we conducted controlled experiments using the atmospheric simulation chamber SAPHIR coupled with a plant chamber system (PLUS). Six European oak trees (Quercus robur) were exposed to: (1) no stressor, (2) ozone stress alone, and (3) combined heat and ozone stress conditions. The oak emissions were transferred into SAPHIR for oxidation. Here, we present how environmental stress altered emitted BVOC mixtures, their atmospheric reactivity, and resulting SOA yields.