Production of Volatile Organic Compounds by Ozone Oxidation Chemistry at the South China Sea Surface Microlayer

Ozone (O-3) oxidation chemistry on proxy compoundsofthe sea surface microlayer (SML) generates volatile organic compounds(VOCs) in the atmosphere. To shed light on the proposed significanceof this chemistry, we investigated the formation of VOCs through heterogeneouschemistry of O-3 (100 ppb) with authentic SML collectedfrom 10 sites in the South China Sea using a reactor coupled to protontransfer reaction-time of flight-mass spectrometry (PTR-TOF-MS)and subsequently identified by off-line techniques. On the basis ofthe semi-quantitative data of the identified compounds, we estimatedthe production rates of acetone, acetaldehyde, propanal, hexanal,heptanal, octanal, and nonanal, which correspond to the experimentalconditions applied in this study. These results provide a significantupdate to our understanding of abiotic formation of VOCs in the marineatmosphere, which should be considered in future model studies toproperly evaluate the VOC contribution of ozone heterogeneous chemistrywith the SML.