Supporting Data for Fristensky & Carey, “Drivers of Dissolved Organic Matter Quality and Concentration in a Mountainous Subarctic Watershed, Yukon, Canada”

Northern permafrost regions contain vast stores of organic carbon and rapidly rising temperatures make these frozen soil stores increasingly vulnerable to thaw and mobilization. While considerable attention has been given to carbon export from large Arctic river systems, gaps remain in characterizing carbon export and dissolved organic matter (DOM) quality in permafrost influenced headwater catchments that contain a complex mosaic of landscape types including lakes and wetlands. This study examines the spatial and temporal factors influencing DOM quality and concentration over a four-year period across the Wolf Creek Research Basin, Yukon. Repeat sampling at six sites were combined with optical indices to assess changes in DOM quality as related to landscape type from permafrost dominated headwaters to forested lowlands and included lake and wetland sampling. Results indicate DOM export was transport-limited with greater exports in years with record high snowpacks and flows. Seasonality was responsible for the greatest variability in DOM quality, yet landscape type was and important factor during the open water season. High SUVA254/HIX in headwater streams indicated primarily humic, terrestrially derived DOM while high BIX and comparatively lower SUVA254 /HIX in a mid-catchment lake indicated autotrophic production of new DOM. DOM quality at the catchment outlet reflected a mixture of upstream sources and increased influence of groundwater. During high snow and streamflow years, DOM was humic and aromatic compared to low flow years which had a greater portion of fresh DOM. Results highlight the importance of evaluating DOM quality across all seasons and the relative influence of different landscape types and potential response to rapid environmental change.

This data collection contains air temperature, Wind Speed (m/s), precipitation (mm), Snow Water Equivalence, and DOC data from all study years and sites referenced in the accompanying publication.