High Arctic Dust Storms and Their Potential Impacts on Freshwater Ecosystems

The impacts of regional dust storms on the functioning of High Arctic ecosystems is an emerging area of research interest. There, little vegetation on expansive Arctic desert landscapes expose mineral and thin organic soils to deflation processes. We were afforded the opportunity to begin examining the impacts of dust storms on freshwater ecosystems within the 7500 km² Lake Hazen watershed on northern Ellesmere Island, Nunavut, Canada, following particularly low snowpack water loadings in winter 2013/14 compared to normal loadings of ~130±90 kg/m² for the region. Low snowpack loads allowed for aeolian redistribution of exposed surface soils within and outside the watershed during wind storms throughout that winter and spring. When the dust was deposited onto the ice-covered surface of Lake Hazen (540 km²), these light absorbing impurities (LAIs) impacted patterns of snow drifting and albedo, which in turn impacted spatial distribution of nutrients and contaminant loadings. In fact, in mid-May 2014, half of the lake surface had dark, dust laden snowpacks with low water loadings (14±19 kg/m²) whereas the other half had white, low dust snowpacks with higher water loadings (49±10 kg/m²). Furthermore, a major 3-day dust storm in late May 2014 resulted in the entire surface of Lake Hazen being covered in a new layer of dust just prior to snowmelt. This caused major increases in concentrations of particulate nitrogen and carbon, mercury and turbidity in Lake Hazen surface waters under the ice when snowmelt drained into the lake via drain holes, open-water leads, and ice candle channels that formed prematurely due to the widespread abundance of LAIs on the ice surface. Interestingly, concentrations of most other chemical parameters decreased in surface waters via dilution following snowmelt. These snowmelt chemical dynamics are important to the spring pulse of primary productivity in upper surface waters under the ice. The premature candling and degradation of the lake ice also caused an early ice out on Lake Hazen in 2014 despite summer temperatures being cooler than in other years. As ice-free seasons grow longer in the Arctic due to human-induced climate warming, direct aeolian inputs of nutrients and contaminants to freshwaters could increase during summer dust storms, further affecting basic freshwater functioning.