Boreal blazes: biomass burning and vegetation types archived in the Juneau Icefield

The past decade includes some of the most extensive boreal forest fires in the historical record. Warming temperatures, changing precipitation patterns, the desiccation of thick organic soil layers, and increased ignition from lightning all contribute to a combustive combination. Smoke aerosols trav...

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Bibliographic Details
Published in:Environmental research letters 2020-08, Vol.15 (8), p.85005
Main Authors: Kehrwald, Natalie M, Jasmann, Jeramy R, Dunham, Melissa E, Ferris, David G, Osterberg, Erich C, Kennedy, Joshua, Havens, Jeremy, Barber, Larry B, Fortner, Sarah K
Format: Article
Language:English
Subjects:
Aerosols
alaska
Biomass
Biomass burning
Black carbon
Blanketing
Boreal forests
Burning
Combustion
Desiccation
fire
Forest fires
Fossil fuels
Grasslands
Hardwoods
ice core
Ice fields
Indicators
Levoglucosan
Monosaccharides
Organic soils
Plumes
Satellite observation
siberia
Smoke
Snowpack
Softwoods
Soil layers
vegetation
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Summary:The past decade includes some of the most extensive boreal forest fires in the historical record. Warming temperatures, changing precipitation patterns, the desiccation of thick organic soil layers, and increased ignition from lightning all contribute to a combustive combination. Smoke aerosols travel thousands of kilometers, before blanketing the surfaces on which they fall, such as the Juneau Icefield. However, many aerosols found in smoke plumes are also produced by other processes and therefore can be ambiguous indicators of fire activity. Here, we use the monosaccharide anhydrides levoglucosan, mannosan, and galactosan as specific indicators of biomass burning to unambiguously demonstrate that fire aerosols reach the Juneau Icefield and are integrated into the snowpack. Back trajectories and satellite observations demonstrate that smoke plumes originating in central Alaska and eastern Siberia affect the Juneau Icefield. These regional sources of fire differ from other combustion aerosols deposited on the Juneau Icefield, such as black carbon, that originate from local fossil fuel burning. Ratios of levoglucosan/mannosan (L/M) and levoglucosan/(mannosan + galactosan) (L/(M + G)) demonstrate that while the majority of fire aerosols reaching the Juneau Icefield originate from softwood burning, grasslands and hardwood forests are also sources. The presence of these hardwoods suggests that fire aerosols may reach the Juneau Icefield from locations as far away as East Asia.
ISSN:1748-9326
1748-9326
DOI:10.1088/1748-9326/ab8fd2