1Institute of Energy and Climate Research, IEK-8:
Troposphere, Forschungszentrum Jülich GmbH, Jülich, Germany
2College of Environmental Sciences and Engineering,
Peking University, Beijing, China
3Chemical Sciences Division, Earth System Research
Laboratory, National Oceanic and Atmospheric Administration,
Boulder, CO, USA
4Key Laboratory for Urban Habitat Environmental Science
and Technology, School of Environment and Energy, Peking
University Shenzhen Graduate School, Shenzhen, China
5Cooperative Institute for Research in Environmental
Sciences, University of Colorado, Boulder, CO, USA
6School of Environmental Sciences and Engineering,
Nanjing University of Information Science and Technology, Nanjing,
China
7CAS Center for Excellence in Regional Atmospheric
Environment, Chinese Academy of Science, Xiamen, China
bnow at: College of Environmental Sciences and
Engineering, Peking University, Beijing, China
cnow at: School of Environmental Science and Engineering,
Gwangju Institute of Science and Technology, Gwangju, Korea
1Institute of Energy and Climate Research, IEK-8:
Troposphere, Forschungszentrum Jülich GmbH, Jülich, Germany
2College of Environmental Sciences and Engineering,
Peking University, Beijing, China
3Chemical Sciences Division, Earth System Research
Laboratory, National Oceanic and Atmospheric Administration,
Boulder, CO, USA
4Key Laboratory for Urban Habitat Environmental Science
and Technology, School of Environment and Energy, Peking
University Shenzhen Graduate School, Shenzhen, China
5Cooperative Institute for Research in Environmental
Sciences, University of Colorado, Boulder, CO, USA
6School of Environmental Sciences and Engineering,
Nanjing University of Information Science and Technology, Nanjing,
China
7CAS Center for Excellence in Regional Atmospheric
Environment, Chinese Academy of Science, Xiamen, China
Received: 09 Aug 2016 – Discussion started: 10 Aug 2016 – Revised: 24 Nov 2016 – Accepted: 06 Dec 2016 – Published: 13 Jan 2017
Abstract. In 2014, a large, comprehensive field campaign was conducted in the densely populated North China Plain. The measurement site was located in a botanic garden close to the small town Wangdu, without major industry but influenced by regional transportation of air pollution. The loss rate coefficient of atmospheric hydroxyl radicals (OH) was quantified by direct measurements of the OH reactivity. Values ranged between 10 and 20 s−1 for most of the daytime. Highest values were reached in the late night with maximum values of around 40 s−1. OH reactants mainly originated from anthropogenic activities as indicated (1) by a good correlation between measured OH reactivity and carbon monoxide (linear correlation coefficient R2 = 0.33) and (2) by a high contribution of nitrogen oxide species to the OH reactivity (up to 30 % in the morning). Total OH reactivity was measured by a laser flash photolysis–laser-induced fluorescence instrument (LP-LIF). Measured values can be explained well by measured trace gas concentrations including organic compounds, oxygenated organic compounds, CO and nitrogen oxides. Significant, unexplained OH reactivity was only observed during nights, when biomass burning of agricultural waste occurred on surrounding fields. OH reactivity measurements also allow investigating the chemical OH budget. During this campaign, the OH destruction rate calculated from measured OH reactivity and measured OH concentration was balanced by the sum of OH production from ozone and nitrous acid photolysis and OH regeneration from hydroperoxy radicals within the uncertainty of measurements. However, a tendency for higher OH destruction compared to OH production at lower concentrations of nitric oxide is also observed, consistent with previous findings in field campaigns in China.
OH reactivity was measured during a 1-month long campaign at a rural site in the North China Plain in 2014. OH reactivity measurements are compared to calculations using OH reactant measurements. Good agreement is found indicating that all important OH reactants were measured. In addition, the chemical OH budget is analyzed. In contrast to previous campaigns in China in 2006, no significant imbalance between OH production and destruction is found.
OH reactivity was measured during a 1-month long campaign at a rural site in the North China...
