Winter Dust Storms Impact the Physical and Biogeochemical Functioning of a Large High Arctic Lake.

ABSTRACT

We found that a winter of abnormally low snowfall and numerous dust storms from eolian processes acting on exposed landscapes (including a major 4-day dust storm while onsite in May 2014) caused a cascade of impacts on the physical, chemical, and ecological functioning of the largest lake by volume in the High Arctic (Lake Hazen; Nunavut, Canada). MODIS imagery revealed that dust deposited in snowpacks on the lake's ice acted as light-absorbing impurities (LAIs), reducing surface reflectance and increasing surface temperatures relative to normal snowpack years, causing early snowmelt and drainage of meltwaters into the lake. LAIs remaining on the ice surface melted into the ice, causing premature candling and one of the earliest ice-offs and longest ice-free seasons on record for Lake Hazen. Meltwater inputs from snowpacks resulted in dilution of dissolved, and increased concentration of particulate bound, chemical species in Lake Hazen's upper water column. Spring inputs of nutrients increased both heterotrophy and algal productivity under the surface ice following snowmelt, with a net consumption of dissolved oxygen. As climate change continues to alter High Arctic temperatures and precipitation patterns, we can expect further changes in dust storm frequency and severity with corresponding impacts for freshwater ecosystems.