Seasonality of Solute Flux and Water Source Chemistry in a Coastal Glacierized Watershed Undergoing Rapid Change: Wolverine Glacier Watershed, Alaska

As glaciers around the world rapidly lose mass, the tight coupling between glaciers and downstream ecosystems is resulting in widespread impacts on global hydrologic and biogeochemical cycling. However, a range of challenges make it difficult to conduct research in glacierized systems, and our knowl...

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Bibliographic Details
Published in:Water resources research 2021-11, Vol.57 (11), p.n/a
Main Authors: Bergstrom, Anna, Koch, Joshua C., O'Neel, Shad, Baker, Emily
Format: Article
Language:English
Subjects:
Biogeochemical cycles
Calcium
Calcium ions
Coastal waters
concentration‐discharge relationships
Downstream effects
Drainage network
Drainage patterns
Electrical conductivity
Electrical resistivity
Flow paths
Fluxes
Glacier research
glacierized watersheds
Glaciers
Glaciohydrology
Groundwater
Groundwater flow
Hydrologic processes
Hydrology
mixing model
Partitioning
Seasonal variations
Seasonality
Seasons
Snowmelt
solute flux
Solutes
Stream discharge
Stream flow
Subsurface flow
Water analysis
Water sampling
Water sources
Watersheds
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Summary:As glaciers around the world rapidly lose mass, the tight coupling between glaciers and downstream ecosystems is resulting in widespread impacts on global hydrologic and biogeochemical cycling. However, a range of challenges make it difficult to conduct research in glacierized systems, and our knowledge of seasonally changing hydrologic processes and solute sources and signatures is limited. This in turn hampers our ability to make predictions on solute composition and flux. We conducted a broad water sampling campaign in order to understand the present‐day partitioning of water sources and associated solutes in Alaska's Wolverine Glacier watershed. We established a relationship between electrical conductivity and streamflow at the watershed outlet to divide the melt season into four hydroclimatic periods. Across hydroclimatic periods, we observed a shift in nonglacial source waters from snowmelt‐dominated overland and shallow subsurface flow paths to deeper groundwater flow paths. We also observed the shift from a low‐ to high‐efficiency subglacial drainage network and the associated flushing of water stored subglacially with higher solute loads. We used calcium, the dominant dissolved ion, from watershed outlet samples to estimate solute fluxes for each hydroclimatic period across two melt seasons. We found between 40% and 55% of Ca2+ export occurred during the late season rainy period. This partitioning of the melt season coupled with a characterization of the chemical makeup and magnitude of solute export provides new insight into a rapidly changing watershed and creates a framework to quantify and predict changes to solute fluxes across a melt season. Key Points Electrical conductivity‐discharge relationships indicate four hydroclimatic periods in a glacierized watershed Dominant source waters shift between hydroclimatic periods, particularly from snowmelt to groundwater Highest solute flux occurs during the late‐season rainy period, which is projected to lengthen with changing climate
ISSN:0043-1397
1944-7973
DOI:10.1029/2020WR028725