Using wildland fire tracer molecules to investigate fire frequency and vegetative combustion sources archived in the Juneau Icefield of Alaska

Publication Date

2020-03-16

Time Period

2016

Time Period

2017

Jasmann, J.R., Kehrwald, N.M., Dunham, M.E., Ferris, D.G., Osterburg, E.C., Kennedy, J., and Barber, L.B., 2020, Using wildland fire tracer molecules to investigate fire frequency and vegetative combustion sources archived in the Juneau Icefield of Alaska: U.S. Geological Survey data release, https://doi.org/10.5066/P9DNAN1M.

The deposition of black carbon onto glaciers is known to increase the melting rate which has severe implications on sustainability of fresh water availability and water quality to downstream communities in certain regions. The source of black carbon and other co-transported smoke aerosols and particulates can not be distinguished to have come from wildland fires or industrial fossil fuel burning without the use of other chemical tracer molecules. This study uses the monosaccharide anhydride stereoisomers (also called anhydrosugars) combustion products levoglucosan, mannosan, and galactosan as specific indicators of biomass burning to unambiguously demonstrate that wildland 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. Our smoke aerosol tracer method informs water and land resource managers on source locations of recent and historic fire aerosol and particulate deposits archived in the ice, along with revealing historical trends and links between climate, shifts in local vegetation type, and wildland fire activity frequency and intensity.

• USGS Data Release Products