Abstract View
Chemical and Microphysical Properties of Windblown Dust near an Actively Retreating Glacier in Yukon, Canada
PATRICK HAYES, James King, Colm Wickham, Marie-Pierre Bastien-Thibault, Malo Bernhard, Jill Bachelder, Kevin Wilkinson, Madjid Hadioui, Universite de Montreal
Abstract Number: 439
Working Group: Aerosol Chemistry
Abstract
Airborne mineral dust emitted in high-latitude regions can impact radiative forcing, biogeochemical cycling of metals, and local air quality. The impact of dust emissions in these regions may change rapidly, as warming temperatures can increase mineral dust production and source regions. As there exists little research on mineral dust emissions in high-latitude regions, we are performing a series of studies on the physico-chemical properties and emissions of mineral dust from a sub-Arctic proglacial dust source. Soil and aerosol samples (PM10, PM2.5, TSP and deposited mineral dust) were collected in May 2018 and May 2019 near the A'Ay Chu (Slims River), a site exhibiting strong dust emissions. WHO air quality thresholds were exceeded at several receptor sites near the dust source, indicating a negative impact on local air quality. Notably, temporally averaged particle size distributions of PM10 were very fine as compared to those measured at more well-characterized, low-latitude dust sources. In addition, mineralogy and elemental composition of ambient PM10 were characterized; PM10 elemental composition was enriched in trace elements as compared to dust deposition, bulk soil samples, and the fine soil fractions (d<53 μm). This enrichment is even more pronounced in PM2.5 samples. Finally, through a comparison of the elemental composition of PM10, dust deposition, and both fine and bulk soil fractions, as well as of meteorological factors measured during our campaign, we propose that the primary mechanisms for dust emissions from the A’ay Chu Valley are the rupture of clay coatings on particles or the release of resident fine particulate matter. This field study highlights the need to include high-latitude mineral dust sources in climate and chemical transport models in order to correctly predict future climate feedbacks, for example, increases in atmospheric ice nuclei concentrations or the deposition of light absorbing mineral dust on snow and ice.