Intercomparison of nitrous acid (HONO) measurement techniques in a megacity (Beijing)

Abstract

Nitrous acid (HONO) is a key determinant of the daytime radical budget in the daytime boundary layer, with quantitative measurement required to understand OH radical abundance. Accurate and precise measurements of HONO are therefore needed; however HONO is a challenging compound to measure in the field, in particular in a chemically complex and highly polluted environment. Here we report an intercomparison exercise between HONO measurements performed by two wet chemical techniques (the commercially available a long-path absorption photometer (LOPAP) and a custom-built instrument) and two broadband cavity-enhanced absorption spectrophotometer (BBCEAS) instruments at an urban location in Beijing. In addition, we report a comparison of HONO measurements performed by a time-of-flight chemical ionization mass spectrometer (ToF-CIMS) and a selected ion flow tube mass spectrometer (SIFT-MS) to the more established techniques (wet chemical and BBCEAS). The key finding from the current work was that all instruments agree on the temporal trends and variability in HONO (r2 > 0.97), yet they displayed some divergence in absolute concentrations, with the wet chemical methods consistently higher overall than the BBCEAS systems by between 12 % and 39 %. We found no evidence for any systematic bias in any of the instruments, with the exception of measurements near instrument detection limits. The causes of the divergence in absolute HONO concentrations were unclear, and may in part have been due to spatial variability, i.e. differences in instrument location and/or inlet position, but this observation may have been more associative than casual.

Publication DOI: https://doi.org/10.5194/amt-12-6449-2019
Divisions: Engineering & Applied Sciences > Chemical Engineering & Applied Chemistry
Additional Information: © Author(s) 2019. This work is distributed under the Creative Commons Attribution 4.0 License.
Uncontrolled Keywords: Atmospheric Science
Full Text Link:
Related URLs: http://www.scop ... tnerID=8YFLogxK (Scopus URL)
https://www.atm ... t/12/6449/2019/ (Publisher URL)
PURE Output Type: Article
Published Date: 2019-12-09
Accepted Date: 2019-10-29
Authors: Crilley, Leigh R.
Kramer, Louisa J.
Ouyang, Bin
Duan, Jun
Zhang, Wenqian
Tong, Shengrui
Ge, Maofa
Tang, Ke
Qin, Min
Xie, Pinhua
Shaw, Marvin D.
Lewis, Alastair C.
Mehra, Archit
Bannan, Thomas J.
Worrall, Stephen D. ( 0000-0003-1969-3671)
Priestley, Michael
Bacak, Asan
Coe, Hugh
Allan, James
Percival, Carl J.
Popoola, Olalekan A.M.
Jones, Roderic L.
Bloss, William J.

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