HO<sub>2</sub>NO<sub>2</sub> and HNO<sub>3</sub> in the coastal Antarctic winter night: a "lab-in-the-field" experiment

Abstract

Abstract.Observations of peroxynitric acid (HO 2 NO 2 ) and nitric acid (HNO 3 ) were made during a 4 month period of Antarctic winter darkness at the coastal Antarctic research station, Halley. Mixing ratios of HNO 3 ranged from instrumental detection limits to ∼ 8 parts per trillion by volume (pptv), and of HO 2 NO 2 from detection limits to ∼ 5 pptv; the average ratio of HNO 3 : HO 2 NO 2 was 2.0(± 0.6) : 1, with HNO 3 always present at greater mixing ratios than HO 2 NO 2 during the winter darkness. An extremely strong association existed for the entire measurement period between mixing ratios of the respective trace gases and temperature: for HO 2 NO 2 , R 2 = 0.72, and for HNO 3 , R 2 = 0.70. We focus on three cases with considerable variation in temperature, where wind speeds were low and constant, such that, with the lack of photochemistry, changes in mixing ratio were likely to be driven by physical mechanisms alone. We derived enthalpies of adsorption ( H ads ) for these three cases. The average H ads for HNO 3 was −42 ± 2 kJ mol −1 and for HO 2 NO 2 was −56 ± 1 kJ mol −1 ; these values are extremely close to those derived in laboratory studies. This exercise demonstrates (i) that adsorption to/desorption from the snow pack should be taken into account when addressing budgets of boundary layer HO 2 NO 2 and HNO 3 at any snow-covered site, and (ii) that Antarctic winter can be used as a natural "laboratory in the field" for testing data on physical exchange mechanisms.

Deposition, recycling, and archival of nitrate stable isotopes between the air–snow interface: comparison between Dronning Maud Land and Dome C, Antarctica

“…During other periods, the δ 15 N-NO − 3 in the snow and atmosphere switch to being out of phase, emphasizing NO − 3 isotopic fractionation during those periods. Both HNO 3 and peroxynitric acid (HNO 4 ) can be adsorbed to the snow surface in tandem (Jones et al, 2014), and although we have no direct measurements of these during the campaign, based on previous studies we suggest that HNO 3 is dominantly adsorbed to the skin layer (Jones et al, 2007;Chan et al, 2018).…”

“…Chem. Phys., 20, 5861-5885, 2020 https://doi.org/10.5194/acp-20-5861-2020 are the measured concentrations in snow pit samples, and 0.252 is the SO 2− 4 /Na + ratio in bulk seawater (Keene et al, 1986).…”

Seasonal variability of atmospheric nitrogen oxides and non-methane hydrocarbons at the GEOSummit station, Greenland

“…For the BC anthropogenic tracer the Emissions Database for Global Atmospheric Research (EDGAR) UNEP BC report 2005 data (UNEP, 2011;Shindell et al, 2012) were used. To estimate the BC fire emissions, MODIS hot spot data (Justice et al, 2002;Giglio et al, 2003) were used to estimate the area burned (180 hPa per MODIS hot spot) and combined with a combustion efficiency, emission factor, and fuel load, which were all based on land use type . The land surface types are taken from the NOAH Land Surface Model version 2.7.1.…”

Quantification of peroxynitric acid and peroxyacyl nitrates using an ethane-based thermal dissociation peroxy radical chemical amplification cavity ring-down spectrometer

“…Even though only a small fraction of O 3 dissociates to O 2 + O at ∼ 150 • C in the TD inlet (∼ 0.1 %; Fig. 5; Jones and Davidson, 1962;Heimerl and Coffee, 1979), a comparatively large signal is generated because the O atom reacts with C 2 H 6 to form two radicals, OH and C 2 H 5 (Baulch et al, 1994). This reaction is competitive in the PERCA inlet (compared to reaction of O with O 2 ) because of the high C 2 H 6 concentration (1.7 %): the lifetime of O with respect to reaction with C 2 H 6 is ∼ 0.34 ms, which is of similar magnitude as the expected lifetime of O with respect to reaction with O 2 of ∼ 0.15 ms (Hippler et al, 1990).…”