Historical black carbon deposition in the Canadian High Arctic: A 190-year long ice-core record from Devon Island

Abstract

Abstract. Black carbon aerosol (BC) emitted from natural and anthropogenic sources (e.g., wildfires, coal burning) can contribute to magnify climate warming at high latitudes by darkening snow-and ice-covered surfaces, thus lowering their albedo. Modeling the atmospheric transport and deposition of BC to the Arctic is therefore important, and historical archives of BC accumulation in polar ice can help to validate such modeling efforts. Here we present a 190-year ice-core record of refractory BC (rBC) deposition on Devon ice cap, Canada, spanning calendar years 1810-1990, the first such record ever 15 developed from the Canadian Arctic. The estimated mean deposition flux of rBC on Devon ice cap for 1963-1990 is 0.2 mg m -2 a -1 , which is low compared to most Greenland ice-core sites over the same period. The Devon ice cap rBC record also differs from existing Greenland records in that it shows no evidence of a substantial increase in rBC deposition during the early-mid 20th century, which, for Greenland, has been attributed to mid-latitude coal burning emissions. The deposition of other contaminants such as sulfate and Pb increased on Devon ice cap in the 20th century but without a concomitant rise in 20 rBC. Part of the difference with Greenland may be due to local factors such as wind scouring of winter snow at the coring site on Devon ice cap. Air back-trajectory analyses also suggest that Devon ice cap receives BC from more distant North American and Eurasian sources than Greenland, and aerosol mixing and removal during long-range transport over the Arctic Ocean likely masks some of the specific BC source-receptor relationships. Findings from this study underscore the large variability in BC aerosol deposition across the Arctic region that may arise from different transport patterns. This variability 25 needs to be accounted for when estimating the large-scale albedo lowering effect of BC deposition on Arctic snow/ice.

An 800-year high-resolution black carbon ice core record from Lomonosovfonna, Svalbard

“…The very low rBC concentrations in the LF-11 core compared to the EC concentrations around local sources of contamination in Svalbard such as settlements and mining activities with values higher than 1000 ng g −1 for some samples (Aamaas et al, 2011) underlines that rBC contribution from local anthropogenic sources to the LF drill site appears to be minimal, at least for the most recent years. LF rBC concentrations are very similar to those observed in Greenland and Canadian Arctic ice cores obtained by SP2 analyses (Keegan et al, 2014;McConnell et al, 2007;Sigl et al, 2013;Zdanowicz et al, 2017) (Table 1). However, EC concentrations in Svalbard snow (Aamaas et al, 2011;Doherty et al, 2010;Forsström et al, 2009Forsström et al, , 2013 as well as in the HDF and Fiescherhorn ice cores (Jenk et al, 2006;Ruppel et al, 2014Ruppel et al, , 2017 are 1 order of magnitude higher than rBC concentrations in the topmost part of the LF core.…”

“…The case of the 1797 peak in the rBC and VA records is also remarkable as outstanding values in various biomass burning proxies were detected in several ice cores from Greenland during the last decade of the 18th century. In the NEEM ice core, rBC and levoglucosan were greatly enhanced between 1787 and 1791 (Sigl et al, 2013;Zennaro et al, 2014), while a very strong peak was visible in 1794 in the D4 ice core (McConnell et al, 2007) and in 1799 in the Summit 2010 ice core (Keegan et al, 2014). Ammonium records from the ice cores mentioned above all showed peak values in the same decade (Legrand et al, 2016), supporting the fact that this period of enhanced biomass burning could originate from the same decadal-scale climatic event.…”

“…A few years displayed rBC peaks (see Sect. 3.4) probably originating from atmospheric deposition from biomass burning plumes reaching the Arctic, as McConnell et al (2007) and Zennaro et al (2014) described for Greenland, but annual rBC values did not exceed 4.7 ng g −1 (maximum in 1797). A clear minimum occurred between 1520 and 1540 with annual values lower than 0.2 ng g −1 .…”

“…Formate (HCOO − ) is another appropriate proxy, despite postdepositional effects (Legrand et al, 2016). Specific organic tracers of biomass burning such as vanillic acid (VA), levoglucosan, or p-hydroxybenzoic acid (p-HBA) have also been recently introduced (Grieman et al, 2015(Grieman et al, , 2017(Grieman et al, , 2018Kawamura et al, 2012;Kehrwald et al, 2012;McConnell et al, 2007;Zennaro et al, 2014). In Arctic ice cores, while VA is rather associated with conifer and deciduous boreal tree burning, p-HBA is thought to be predominantly emitted by tundra grass and peat burning (Grieman et al, 2018).…”

Twentieth Century Black Carbon and Dust Deposition on South Cascade Glacier, Washington State, USA, as Reconstructed From a 158‐m‐Long Ice Core

“…The rBC time series from the SCG ice core differs from the other existing Northern Hemisphere rBC ice core records (Figure ; the different dating scenarios minimally affect the presented results), with the timing of peak rBC concentrations at SCG later than in Greenland (McConnell et al, ; Sigl et al, ; Zdanowicz et al, ) and the European Alps (Sigl et al, ) and earlier than in the Caucasus (Lim et al, ), Himalayas (Kaspari et al, ), and Pamirs (M. Wang et al, ) (Figure ). Greenland ice core records generally show BC concentrations increasing after 1880, peaking around 1910, followed by a decreasing trend during the latter 20th century, with North America interpreted as the dominant source of BC emissions deposited in Greenland.…”