10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
Abstract View
Gaseous Nitrated Phenols as a Potential Source of OH Radicals in Beijing
XI CHENG, Qi Chen, Ying Liu, Tong Zhu, Peking University
Abstract Number: 679 Working Group: Air Quality in Megacities: from Sources to Control
Abstract Nitrated phenols (NPs) are a family of aromatic compounds having both nitro and hydroxyl groups connecting to a benzene ring. These species are important because of their phytotoxicity in agriculture and forestry and their contribution to atmospheric oxidative capacity. Gaseous NPs in the atmosphere had been mainly measured by using off-line methods. In this study, we deployed a chemical ionization time-of-flight mass spectrometer equipped with reagent nitrate ion source in Beijing during 2016 to 2017. The accuracy of mass calibration was within 10 ppm for the measurement periods, and NP species were unambiguously identified in the mass spectra. The concentrations of NPs were calibrated by using standard permeation tubes. Sampling wall losses were also determined. High concentrations of gaseous NPs were observed in Beijing (sometimes hundreds of pptv in total), which came from both primary emissions and secondary production. Nighttime enhancements of the NP concentrations often occurred. Moreover, the occurrence of haze in Beijing correlates well with the strong enhancements of dinitrophenol concentrations. During the haze events, the dinitrophenol concentrations alone may go above 150 pptv, possibly explained by aqueous phase reactions. The results suggest that the photolysis of gaseous NPs can be an important source to form atmospheric oxidant in the heavily-polluted urban environment.