Hyperpycnal flows control the persistence and flushing of hypoxic high conductivity bottom water in a High Arctic lake

• Main Authors: Lewis, Ted, Lamoureux, Scott F., Normandeau, Alexandre, Dugan, Hilary A
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: NRC Research Press (a division of Canadian Science Publishing) 2017
• Subjects: Arctic; Arctic Lake
• Online Access: http://hdl.handle.net/1807/81139; http://www.nrcresearchpress.com/doi/abs/10.1139/AS-2017-0022

In the deepest portions of many lakes, zones of high conductivity bottom water (HCBW) depleted in dissolved oxygen (DO) are present. HCBW and DO are important for determining benthic diversity and abundance, nutrients and contaminant cycling, and understanding the long-term evolution of lakes. We investigate the persistence and removal of HCBW and DO replenishment in a High Arctic lake using physical properties and flow velocity data, along with hydrometric and suspended sediment inflow data over a four-year monitoring period (2007-2010). HCBW was removed in 2007 and 2008, but largely remained in 2009 and 2010. Catchment disturbances in 2007 increased suspended sediment concentrations (SSC) in the inflowing river in 2007 and 2008. In the later two years of monitoring (2009-2010), fluvial sediment availability relaxed to pre-disturbance levels. High SSC in 2007 and 2008 caused by landscape disturbances formed sustained river-generated hyperpycnal flows during the snowmelt period that are linked to HCBW removal. In 2009 and 2010, inflowing river water was periodically denser than lake water; however, HCBW were not removed in these years. Hyperpycnal flows were likely either of insufficient strength or duration, deposited on the delta front, or followed paths that led away from the deepest portion of the lake. (WORD COUNT EXCEEDED) The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author.