Refractory black carbon (rBC) concentrations in an ice core from Devon ice cap, Devon Island, Nunavut

• Main Authors: Zdanowicz, Christian, Edwards, Ross, Feiteng, Wang, Fisher, David, Hogan, Chad, Kinnard, Christophe, Proemse, Bernadette
• Format: Dataset
• Language: unknown
• Published: Canadian Cryospheric Information Network 2018
• Subjects: Arctic; Arctic Ocean; Canada; Devon Ice Cap; Devon Island; Greenland; Nunavut; albedo; black carbon; Greenland ice cores; Ice cap; ice core
• Online Access: https://dx.doi.org/10.21963/12952; https://www.polardata.ca/pdcsearch/PDCSearchDOI.jsp?doi_id=12952

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. Modelling 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 modelling efforts. Here we present a >250-year ice-core record of refractory BC (rBC) deposition on Devon ice cap, Canada, spanning the years 1735-1992, the first such record ever developed from the Canadian Arctic. Mass concentrations of rBC in the ice core were measured at annual to sub-annual resolution by the single-particle intracavity laser-induced incandescence photometer (sp2) method. The estimated mean deposition flux of rBC on Devon ice cap for 1963-1990 is 0.2 mg m^-2 a^-1, which is at the low end of estimates from Greenland ice cores obtained by the same analytical method (~0.1-4 mg m^-2 a^-1). The Devon ice cap rBC record also differs from Greenland records in that it shows only a modest increase in rBC deposition during the 20th century, unlike in Greenland where a pronounced rise in rBC occurred from the 1880s to the 1910s, largely attributed to mid-latitude coal burning emissions. The deposition of contaminants such as sulfate and lead increased on Devon ice cap in the 20th century but no concomitant rise in rBC is recorded in the ice. Part of the difference with Greenland could be due to local factors such as melt-freeze cycles on Devon ice cap that may limit the detection sensitivity of rBC analyses in melt-impacted core samples, and wind scouring of winter snow at the coring site. 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 suggest that there could be a large variability in BC aerosol deposition across the Arctic region arising from different transport patterns. This variability needs to be accounted for when estimating the large-scale albedo lowering effect of BC deposition on Arctic snow/ice.