Arctic springtime observations of volatile organic compounds during the OASIS‐2009 campaign

Abstract

Gas-phase volatile organic compounds (VOCs) were measured at three vertical levels between 0.6 m and 5.4 m in the Arctic boundary layer in Barrow, Alaska, for the Ocean-Atmosphere-Sea Ice-Snowpack (OASIS)-2009 field campaign during March-April 2009. C 4 -C 8 nonmethane hydrocarbons (NMHCs) and oxygenated VOCs (OVOCs), including alcohols, aldehydes, and ketones, were quantified multiple times per hour, day and night, during the campaign using in situ fast gas chromatography-mass spectrometry. Three canister samples were also collected daily and subsequently analyzed for C 2 -C 5 NMHCs. The NMHCs and aldehydes demonstrated an overall decrease in mixing ratios during the experiment, whereas acetone and 2-butanone showed increases. Calculations of time-integrated concentrations of Br atoms, ∫[Br]dt, yielded values as high as (1.34 ± 0.27) × 10 14 cm À3 s during the longest observed ozone depletion event (ODE) of the campaign and were correlated with the steady state Br calculated at the site during this time. Both chlorine and bromine chemistry contributed to the large perturbations on the production and losses of VOCs. Notably, acetaldehyde, propanal, and butanal mixing ratios dropped below the detection limit of the instrument (3 parts per trillion by volume (pptv) for acetaldehyde and propanal, 2 pptv for butanal) during several ODEs due to Br chemistry. Chemical flux calculations of OVOC production and loss are consistent with localized high Cl-atom concentrations either regionally or within a very shallow surface layer, while the deeper Arctic boundary layer provides a continuous source of precursor alkanes to maintain the OVOC mixing ratios.

Direct detection of atmospheric atomic bromine leading to mercury and ozone depletion

“…Here, the model was constrained to measured Br 2 , BrO, Cl 2 , ClO, O 3 , CH 4 , C 2 H 6 , and C 3 H 8 , as well as photolysis frequencies calculated using the National Center for Atmospheric Research Tropospheric UV and Visible Radiation Model (https://www2.acom.ucar.edu/modeling/ tropospheric-ultraviolet-and-visible-tuv-radiation-model) with a surface snowpack albedo of 0.9 (26). HCHO and CH 3 CHO levels in the model were constrained to previous observations near Utqia _ gvik during spring 2009 (31,60). NO x in the model was varied from 10 to 193 ppt based on measurements near Utqia _ gvik in March 2009 for days with no town influence (33).…”

Atmospheric Acetaldehyde: Importance of Air‐Sea Exchange and a Missing Source in the Remote Troposphere

“…Evidence to support that suspicion in the remote FT is provided by the concomitant PAN measurements, with the observed PAN and CH 3 CHO mutually incompatible based on their known chemistry (Millet et al, ; Staudt et al, ). Progress has been made in recent years to quantify trace levels of CH 3 CHO in pristine environments using the NCAR Trace Organic Gas Analyzer (TOGA; see more details in the supporting information, SI; Apel et al, , ; Hornbrook et al, ).…”

“…It is a major precursor of peroxyacetyl nitrate (PAN; Fischer et al, 2014), which affects the longrange transport of NO x (NO + NO 2 ; Singh et al, 1990). It also affects hydrogen oxide radicals (Moxim et al, 1996;Seinfeld & Pandis, 2012) and reactive halogen chemistry (Hornbrook et al, 2016;Koenig et al, 2017). High levels of CH 3 CHO have been reported in the remote marine boundary layer (MBL; Read et al, 2012;Singh et al, 2003) and the free troposphere (FT; Singh et al, 2001Singh et al, , 2003.…”

Atmospheric VOC measurements at a High Arctic site: characteristics and source apportionment

“…Few studies have reported VOCs in ambient air from Arctic sites with on-line techniques, usually during short-term campaigns. Hornbrook et al (2016) utilized non-methane hydrocarbons measurements to derive time-integrated halogen mixing ratios during the OASIS-2009 campaign at Barrow, AK. Mungall et al (2018) studied the sources of formic and acetic acid at Alert, CA during the summer of 2016.…”