Influences of increased riparian thaw depths on stream temperatures and chemical export in beaded arctic streams

Beaded streams are prominent on the North Slope of Alaska and thus influence the processing and export of constituents. These streams consist of small pools connected by shallow chutes, are typically first order, and exhibit variability in the magnitude of water storage and residence times throughout the open water season. This study examines the changes in pool temperatures in Imnavait Creek for the purpose of understanding heat and mass transport through the system to investigate potential impacts of climate variations. We found that the dominant heat sources and sinks that influence pool thermal stratification, including feedbacks due to absorption of solar radiation by dissolved organic matter (DOM), are key to understanding the evolution of water chemistry and material export. Exchanges between the riparian and hillslope areas with the streams also influenced the timing of solute export and water chemistry through subsurface lateral inputs. Under relatively low flow conditions, we found that pool stratification was persistent, chemical differences between pool surface and bottom waters were strong, and riparian influences on pool bottom water chemistry can be substantial. Temperature modeling indicated that the dominant heat sources vary between stratified layers and that increases in thaw depths surrounding these pools can influence stratification, mixing, residence times, and the fate of stream constituents such as carbon and nutrients.