An in situ flow tube system for direct measurement of N 2 O 5 heterogeneous uptake coefficients in polluted environments
Atmospheric Measurement Techniques(2018)
Abstract
Abstract. The heterogeneous reactivity of dinitrogen pentoxide
( N2O5 ) on ambient aerosols plays a key role in the atmospheric fate of NOx and formation of secondary pollutants. To better understand the
reactive uptake of N2O5 on complex ambient aerosols, an in situ
experimental approach to direct measurement of N2O5 uptake
coefficient ( γ N2O5 ) was developed for application in
environments with high, variable ambient precursors. The method utilizes an
aerosol flow tube reactor coupled with an iterative chemical box model to
derive γ N2O5 from the depletion of synthetically
generated N2O5 when mixed with ambient aerosols. Laboratory
tests and model simulations were performed to characterize the system and the
factors affecting γ N2O5 , including mean residence time,
wall loss variability with relative humidity (RH), and N2O5 formation and titration
with high levels of NO, NOx , and O3 . The overall uncertainty was
estimated to be 37 %–40 % at γ N2O5 of 0.03 for RH
varying from 20 % to 70 %. The results indicate that this flow tube
coupled with the iterative model method could be buffered to NO
concentrations below 8 ppbv and against air mass fluctuations switching
between aerosol and non-aerosol modes. The system was then deployed in the
field to test its applicability under conditions of high ambient NO2 and O3 and fresh NO emission. The results demonstrate that the
iterative model improved the accuracy of γ N2O5 calculations in polluted environments and thus support the further field
deployment of the system to study the impacts of heterogeneous N2O5 reactivity on photochemistry and aerosol formation.
MoreTranslated text
Key words
heterogeneous uptake coefficients,situ flow tube system,polluted environments
AI Read Science
Must-Reading Tree
Example
![](https://originalfileserver.aminer.cn/sys/aminer/pubs/mrt_preview.jpeg)
Generate MRT to find the research sequence of this paper
Chat Paper
Summary is being generated by the instructions you defined