Diel peroxy radicals in a semi-industrial coastal area: nighttime formation of free radicals 1Institute of Environmental Physics, University of Bremen, Bremen, Germany
14 Jun 2013
2Max Planck Institute for Chemistry, Mainz, Germany
3Indian Institute of Science Education and Research Mohali, Department of Chemical Sciences, Sector 81, S.A.S. Nagar, Manauli PO, Punjab 140306, India
*now at: Institute for Atmospheric Physics, University of Mainz, Mainz, Germany
Received: 25 June 2012 – Published in Atmos. Chem. Phys. Discuss.: 07 August 2012 Abstract. Peroxy radicals were measured by a PeRCA (Peroxy Radical Chemical Amplifier)
instrument in the boundary layer during the DOMINO (Diel Oxidant Mechanisms
In relation to Nitrogen Oxides) campaign at a coastal, forested site
influenced by urban-industrial emissions in southern Spain in late autumn.
Total peroxy radicals (RO2* = HO2 + ΣRO2)
generally showed a daylight maximum between 10 and 50 pptv at 13:00 UTC,
with an average of 18 pptv over the 15 days of measurements. Emissions from
the industrial area of Huelva often impacted the measurement site at night
during the campaign. The processing of significant levels of anthropogenic
organics leads to an intense nocturnal radical chemistry accompanied by
formation of organic peroxy radicals at comparable levels to those of summer
photochemical conditions with peak events up to 60–80 pptv. The RO2
production initiated by reactions of NO3 with organic trace gases was
estimated to be significant, but not sufficient to account for the
concentrations of RO2* observed in air masses carrying high
pollutant loading. The nocturnal production of peroxy radicals in those
periods seems therefore to be dominated by ozonolysis of volatile organic
compounds, in particular alkenes of industrial petrochemical origin.
Revised: 26 March 2013 – Accepted: 06 May 2013 – Published: 14 June 2013
RO2* diurnal variations were consistent with HO2
measurements available at the site. HO2/RO2* ratios
generally varied between 0.3 and 0.6, though on some occasions this ratio
was likely to have been affected by instrumental artifacts (overestimated
HO2) associated with high RO2 loads.
Citation: Andrés-Hernández, M. D., Kartal, D., Crowley, J. N., Sinha, V., Regelin, E., Martínez-Harder, M., Nenakhov, V., Williams, J., Harder, H., Bozem, H., Song, W., Thieser, J., Tang, M. J., Hosaynali Beigi, Z., and Burrows, J. P.: Diel peroxy radicals in a semi-industrial coastal area: nighttime formation of free radicals, Atmos. Chem. Phys., 13, 5731-5749, doi:10.5194/acp-13-5731-2013, 2013.