Organosulfates and organic acids in Arctic aerosols: speciation, annual variation and concentration levels

Abstract

Abstract. Sources, composition and occurrence of secondary organic aerosols in the Arctic were investigated at Zeppelin Mountain, Svalbard, and Station Nord, northeastern Greenland, during the full annual cycle of 2008 and 2010, respectively. Speciation of organic acids, organosulfates and nitrooxy organosulfates – from both anthropogenic and biogenic precursors were in focus. A total of 11 organic acids (terpenylic acid, benzoic acid, phthalic acid, pinic acid, suberic acid, azelaic acid, adipic acid, pimelic acid, pinonic acid, diaterpenylic acid acetate and 3-methyl-1,2,3-butanetricarboxylic acid), 12 organosulfates and 1 nitrooxy organosulfate were identified in aerosol samples from the two sites using a high-performance liquid chromatograph (HPLC) coupled to a quadrupole Time-of-Flight mass spectrometer. At Station Nord, compound concentrations followed a distinct annual pattern, where high mean concentrations of organosulfates (47 ± 14 ng m−3) and organic acids (11.5 ± 4 ng m−3) were observed in January, February and March, contrary to considerably lower mean concentrations of organosulfates (2 ± 3 ng m−3) and organic acids (2.2 ± 1 ng m−3) observed during the rest of the year. At Zeppelin Mountain, organosulfate and organic acid concentrations remained relatively constant during most of the year at a mean concentration of 15 ± 4 ng m−3 and 3.9 ± 1 ng m−3, respectively. However during four weeks of spring, remarkably higher concentrations of total organosulfates (23–36 ng m−3) and total organic acids (7–10 ng m−3) were observed. Elevated organosulfate and organic acid concentrations coincided with the Arctic haze period at both stations, where northern Eurasia was identified as the main source region. Air mass transport from northern Eurasia to Zeppelin Mountain was associated with a 100% increase in the number of detected organosulfate species compared with periods of air mass transport from the Arctic Ocean, Scandinavia and Greenland. The results from this study suggested that the presence of organic acids and organosulfates at Station Nord was mainly due to long-range transport, whereas indications of local sources were found for some compounds at Zeppelin Mountain. Furthermore, organosulfates contributed significantly to organic matter throughout the year at Zeppelin Mountain (annual mean of 13 ± 8%) and during Arctic haze at Station Nord (7 ± 2%), suggesting organosulfates to be important compounds in Arctic aerosols.

Atmospheric black carbon and sulfate concentrations in Northeast Greenland

“…as (NH 4 ) 2 SO 4 or NH 4 HSO 4 (Seinfeld and Pandis, 2006). Furthermore, inorganic sulfate can react with organic aerosol species to form organosulfates (Liggio and Li, 2006;Surratt et al, 2007), which have also been observed in the Arctic (Hansen et al, 2014). The presence of sulfate also enhances the CCN activity in atmospheric aerosol samples (Quinn and Bates, 2011).…”

Organic functional groups in the submicron aerosol at 82.5° N, 62.5° W from 2012 to 2014

“…During winter and early spring, much of the OM may come from Eurasian fossil fuel sources (e.g., Behrenfeldt et al, 2008;Nguyen et al, 2013;Barrett et al, 2015), and it is mixed with sulfates and nitrates (Weinbruch et al, 2012). Organic acids and organosulfates measured in samples from Station Nord suggest that OM during October to April is from distant anthropogenic sources, whereas the year-round presence of organic sulfates in samples collected at Mount Zeppelin indicates contributions from local sources as well as long-range transport (Hansen et al, 2014). Tracers of secondary organic aerosol (SOA) production from BVOC oxidation have been found in the late spring and summer at Alert (Fu et al, 2009a, b) and in the Arctic marine boundary layer (Hu et al, 2013).…”

“…Tracers of secondary organic aerosol (SOA) production from BVOC oxidation have been found in the late spring and summer at Alert (Fu et al, 2009a, b) and in the Arctic marine boundary layer (Hu et al, 2013). During May-September, organic acids at Station Nord suggest evidence of a relatively high biogenic influence (Hansen et al, 2014). Summer observations from ships in the central Arctic Ocean (Chang et al, 2011) and the southeast Beaufort Sea (Kawamura et al, 2012), as well as spring samples from Alert (Fu et al, 2015), indicate OM from both marine and continental sources.…”

Evidence for marine biogenic influence on summertime Arctic aerosol

“…Detection of molecular tracers for secondary organic aerosol (SOA) has indicated a contribution from secondary processes. In particular, tracers of isoprene, terpene, and fatty acid oxidation have been detected in summer aerosol at several Arctic sites, including Alert, Nunavut; Station Nord, Greenland; and Zeppelin, Svalbard [Fu et al, 2009;Kawamura et al, 2012;Fu et al, 2013;Hansen et al, 2014]. Sources of gas phase precursors to SOA are poorly characterized in Arctic summer but could include Arctic terrestrial [Schollert et al, 2014;Kramshoj et al, 2016] and marine emissions [Willis et al, 2016;Kim et al, 2017;Mungall et al, 2017].…”