Abstract. The first multi-year contributions from organic functional groups to the Arctic submicron aerosol are documented using 126 weekly-integrated samples collected from April 2012 to October 2014 at the Alert Observatory (82.45 • N, 62.51 • W). Results from the particle transport model FLEXPART, linear regressions among the organic and inorganic components and positive matrix factorization (PMF) enable associations of organic aerosol components with source types and regions. Lower organic mass (OM) concentrations but higher ratios of OM to non-sea-salt sulfate mass concentrations (nss-SO = 4 ) accompany smaller particles during the summer (JJA). Conversely, higher OM but lower OM / nss-SO = 4 accompany larger particles during winter-spring. OM ranges from 7 to 460 ng m −3 , and the study average is 129 ng m −3 . The monthly maximum in OM occurs during May, 1 month after the peak in nss-SO = 4 and 2 months after that of elemental carbon (EC). Winter (DJF), spring (MAM), summer and fall (SON) values of OM / nss-SO = 4 are 26, 28, 107 and 39 %, respectively, and overall about 40 % of the weekly variability in the OM is associated with nss-SO = 4 . Respective study-averaged concentrations of alkane, alcohol, acid, amine and carbonyl groups are 57, 24, 23, 15 and 11 ng m −3 , representing 42, 22, 18, 14 and 5 % of the OM, respectively. Carbonyl groups, detected mostly during spring, may have a connection with snow chemistry. The seasonally highest O / C occurs during winter (0.85) and the lowest O / C is during spring (0.51); increases in O / C are largely due to increases in alcohol groups. During winter, more than 50 % of the alcohol groups are associated with primary marine emissions, consistent with Shaw et al. (2010) and Frossard et al. (2011). A secondary marine connection, rather than a primary source, is suggested for the highest and most persistent O / C observed during the coolest and cleanest summer (2013), when alcohol and acid groups made up 63 % of the OM. A secondary marine source may be a general feature of the summer OM, but higher contributions from alkane groups to OM during the warmer summers of 2012 (53 %) and 2014 (50 %) were likely due to increased contributions from combustion sources. Evidence for significant contributions from biomass burning (BB) was present in 4 % of the weeks. During the dark months (NDJF), 29, 28 and 14 % of the nss-SO = 4 , EC and OM were associated with transport times over the gas flaring region of northern Russia and other parts of Eurasia. During spring, those percentages dropped to 11 % for each of nss-SO = 4 and EC values, respectively, and there is no association of OM.

Abstract-The Arctic is generally considered to be a pristine environment and has few direct inputs of organochlorine compounds (OCs), including pesticides, herbicides, polychlorinated biphenyls, or polycyclic aromatic hydrocarbons (PAHs). In spite of this, airborne concentrations of persistent organic pollutants (POPs) are comparable to those in more populated and industrialized regions of North America and Europe. Atmospheric transport and condensation of compounds at low temperature conditions are important factors contributing to the presence of contaminants in the Arctic. A long-term program has been established to measure the airborne concentrations of POPs in the Arctic. The first station at Alert was established in January 1992. The concentrations measured in the first year of monitoring for 18 compounds that are representative of different compound classes are presented. Seasonal variations for PAHs are similar to those for Arctic haze and peak during winter. For example, in the coldest period, October to April, benzo[a]pyrene concentrations were found to average 20 pg/m 3 , whereas, in contrast, during the relatively warm May to September period, average levels were 1.0 pg/m 3 . For OCs, the seasonal cycle was not as pronounced as that for PAH compounds. For example, ␣-hexachlorocyclohexane was found at Alert at average concentrations of 62 and 57 pg/m 3 , respectively, during cold and warm periods. It is postulated that air concentrations are influenced by advection from distant source regions as well as exchange with local (Arctic Ocean) surfaces.

Abstract. Rapidly rising temperatures and loss of snow and ice cover have demonstrated the unique vulnerability of the high Arctic to climate change. There are major uncertainties in modelling the chemical depositional and scavenging processes of Arctic snow. To that end, fresh snow samples collected on average every 4 days at Alert, Nunavut, from September 2014 to June 2015 were analyzed for black carbon, major ions, and metals, and their concentrations and fluxes were reported. Comparison with simultaneous measurements of atmospheric aerosol mass loadings yields effective deposition velocities that encompass all processes by which the atmospheric species are transferred to the snow. It is inferred from these values that dry deposition is the dominant removal mechanism for several compounds over the winter while wet deposition increased in importance in the fall and spring, possibly due to enhanced scavenging by mixed-phase clouds. Black carbon aerosol was the least efficiently deposited species to the snow.

No abstract

During the international Polar Sunrise Experiment 1992 at Alert, Northwest Territories, Canada, in the high Arctic, atmospheric chemistry measurements were conducted from January to April to investigate lower tropospheric ozone depletion chemistry. A series of filter‐based measurements involving a denuder and multistage filter holders were made to characterize the particulate and gaseous fraction of lower tropospheric SOx., Br, Cl, I, and NO3− in relation to O3 depletion events. Bromine compounds were the only ones of all those measured to show correlations with ozone depletion. All three components of total Br (particulate inorganic, gaseous inorganic, and gaseous organic) increased during O3 depletion events. Temporal trends in halogens between the dark of January and the complete light of April were in some cases evident. Largely, as a result of more frequently occurring O3 depletion‐related episodes toward April, average concentrations of Br components tended to increase. The sum of inorganic particulate and gaseous Br increased from about 10 to 20 parts per trillion by volume (pptv) and organic gaseous Br increased from 25 to 40 pptv. Total inorganic I concentrations increased from about 0.3 pptv in early March to 1.0 pptv in late April. There was no systematic trend in total inorganic (gas plus particle) Cl with concentrations averaging approximately 40 pptv, while organic Cl trapped on charcoal was much more abundant. SOx concentrations averaged about 1200 pptv, decreasing from a maximum of 6000 pptv in January to 800 pptv in April and were well correlated with anthropogenic V. The fraction of SOx oxidized to SO4= increased progressively from a low of 20 to 30% in January to greater than 80% in April. SO4= concentrations increased from 500 pptv in January/February to 1000 pptv in March and dropped to 700 pptv in April. Inorganic NO3− showed no systematic variation throughout the period. It averaged 50 pptv, which is much less than peroxyacetyl nitrate (PAN) (150 to 600 pptv), and it was predominantly in particles. Judging from denuder observations, a filter combination of Teflon followed by two KOH filters can provide useful estimates of inorganic particulate Br− and NO3− as well as of inorganic gaseous Br−. Inorganic gaseous NO3− measurements from KOH and nylon filters suffer interferences from collection of PAN.