Organic Nitrate Contribution to New Particle Formation and Growth in Secondary Organic Aerosols from α-Pinene Ozonolysis

The results indicate a way with which nitrogen oxides deriving from human activities may boost secondary organic aerosol production from biogenic volatile organic compounds.

SVOC and LVOC: volatile organic compounds.

LVOC and ELVOC: extremely low volatility compounds

ROI: reactive oxygen intermediates

The chemical kinetics of organic nitrate production during new particle formation and growth of secondary organic aerosols (SOA) were investigated using the short-lived radioactive tracer 13N in flow-reactor studies of α-pinene oxidation with ozone. Direct and quantitative measurements of the nitrogen content indicate that organic nitrates accounted for ∼40% of SOA mass during initial particle formation, decreasing to ∼15% upon particle growth to the accumulation-mode size range (>100 nm). Experiments with OH scavengers and kinetic model results suggest that organic peroxy radicals formed by α-pinene reacting with secondary OH from ozonolysis are key intermediates in the organic nitrate formation process. The direct reaction of α-pinene with NO3was found to be less important for particle-phase organic nitrate formation. The nitrogen content of SOA particles decreased slightly upon increase of relative humidity up to 80%. The experiments show a tight correlation between organic nitrate content and SOA particle-number concentrations, implying that the condensing organic nitrates are among the extremely low volatility organic compounds (ELVOC) that may play an important role in the nucleation and growth of atmospheric nanoparticles.

Citation: Berkemeier, T., Ammann, M., Mentel, T. F., Pöschl, U., and Shiraiwa, M.: Organic Nitrate Contribution to New Particle Formation and Growth in Secondary Organic Aerosols from α-Pinene Ozonolysis, Environmental Science & Technology, doi: 10.1021/acs.est.6b00961, 2016. 2016.

Publication:DOI

Further publications:Laboratory of Environmental Chemistry (LUC) Publications