Distributions of Polycyclic Aromatic Hydrocarbons, Aromatic Ketones, Carboxylic Acids, and Trace Metals in Arctic Aerosols: Long-Range Atmospheric Transport, Photochemical Degradation/Production at Polar Sunrise

Abstract

The distributions, correlations, and source apportionment of aromatic acids, aromatic ketones, polycyclic aromatic hydrocarbons (PAHs), and trace metals were studied in Canadian high Arctic aerosols. Nineteen PAHs including minor sulfur-containing heterocyclic PAH (dibenzothiophene) and major 6 carcinogenic PAHs were detected with a high proportion of fluoranthene followed by benzo[k]fluoranthene, pyrene, and chrysene. However, in the sunlit period of spring, their concentrations significantly declined likely due to photochemical decomposition. During the polar sunrise from mid-March to mid-April, benzo[a]pyrene to benzo[e]pyrene ratios significantly dropped, and the ratios diminished further from late April to May onward. These results suggest that PAHs transported over the Arctic are subjected to strong photochemical degradation at polar sunrise. Although aromatic ketones decreased in spring, concentrations of some aromatic acids such as benzoic and phthalic acids increased during the course of polar sunrise, suggesting that aromatic hydrocarbons are oxidized to result in aromatic acids. However, PAHs do not act as the major source for low molecular weight (LMW) diacids such as oxalic acid that are largely formed at polar sunrise in the arctic atmosphere because PAHs are 1 to 2 orders of magnitude less abundant than LMW diacids. Correlations of trace metals with organics, their sources, and the possible role of trace transition metals are explained.

Chemical Composition of Aerosol over the Arctic Ocean from Summer ARctic EXpedition (AREX) 2011–2012 Cruises: Ions, Amines, Elemental Carbon, Organic Matter, Polycyclic Aromatic Hydrocarbons, n-Alkanes, Metals, and Rare Earth Elements

“…Most importantly, they highlighted that the more volatile PAHs are more abundant towards the Arctic (by comparing PAHs at Zeppelin and Andøya stations in Northern Norway). PAHs behavior was investigated by dividing the ship route in two main parts: [71][72][73][74][75][76] • N (between Norway and Svalbard) and 76-80 • N (around and above Svalbard). Semi-volatile PAHs concentrations (from FLN to PYR) were found to be 2.3 ± 0.5 and 1.7 ± 0.4 times higher in particle and gas phases, respectively, in the northern track of the ship, in keeping with the literature data.…”

“…REEs are particularly suitable for this purpose. Given the analytical limitations in their measurements (very low concentrations), trace elements and REEs data available from remote sites are limited to short or low temporal resolution sampling campaigns [75] or to a few continuous campaigns in the High Canadian Arctic [76] or Svalbard Islands [77]. Hence, the data set here presented from the Arctic Ocean offer a chance to enlarge the currently available information of these chemical tracers in polar areas.…”

Response to reviewer comment

“…The observed PAH deposition fluxes in these high mountain European areas, 0.02-0.28 µg m −2 d −1 , range among the lowest values reported in the literature (Table 2). Thus, PAH deposition fluxes of 0.40-0.55 µg m −2 d −1 have been recorded at remote sites from the USA (Su et al, 2007;McVeety and Hites, 1988;Leister and Baker, 1994;Dickhut and Gustafsson, 1995), whereas Foan et al (2012) reported mean deposition fluxes of PAHs of 0.18 µg m −2 d −1 in remote areas of northern Spain. The reported PAH depositions in background areas are again higher than those observed in the high mountain European sites, 0.19-0.82 µg m −2 d −1 (Brorstrom-Lunden et al, 1998;Horstmann and McLachlan, 1998;Garban et al, 2002).…”

Polycyclic aromatic hydrocarbons (PAHs), oxy- and nitro-PAHs in ambient air of Arctic town Longyearbyen, Svalbard

“…BZT, 2-and 4-NBip, and BaFlu, suggesting different sources of origin. Several studies have shown that 9-NAnt, cPPhe-4, 9-Flu, and 2+3-NFlt can be secondarily formed via chemical reactions in the atmosphere (Singh et al, 2017;Lin et al, 2015a;Zhao et al, 2018). The compounds were also associated with the sample U2, collected on the warmest day with high UV https://doi.org/10.5194/acp-2020-142 Preprint.…”