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

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 in...

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Main Authors: Ted Lewis, Scott F. Lamoureux, Alexandre Normandeau, Hilary A. Dugan
Format: Article
Language:English
Published: Canadian Science Publishing 2018-12-01
Series:Arctic Science
Subjects:
Online Access:https://doi.org/10.1139/as-2017-0022
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spelling doaj-61315374aba64c36862e65bce241c8662021-10-02T17:35:32ZengCanadian Science PublishingArctic Science2368-74602018-12-0141254110.1139/as-2017-0022Hyperpycnal flows control the persistence and flushing of hypoxic high-conductivity bottom water in a High Arctic lakeTed Lewis0Scott F. Lamoureux1Alexandre Normandeau2Hilary A. Dugan3Department of Geography and Planning, Queen’s University, Kingston, ON K7L 3N6, Canada.Department of Geography and Planning, Queen’s University, Kingston, ON K7L 3N6, Canada.Natural Resources Canada, Geological Survey of Canada Atlantic, Dartmouth, NS B2Y 4A2, Canada.University of Wisconsin-Madison, Center for Limnology, Madison, WI 53706, USA.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 4 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 and 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 was 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. Results suggest that hyperpycnal flow frequency will increase and HCBW persistence will decrease with projected climate change due to an increase in fluvial SSC inflow. Water density changes resulting from increased electrical conductivity and water temperature are not likely to have a similarly large effect on hyperpycnal flow frequency and HCBW.https://doi.org/10.1139/as-2017-0022hyperpycnal flowshypoxic high-conductivity bottom waterpermafrost degradationclimate changepolar limnology
collection DOAJ
language English
format Article
sources DOAJ
author Ted Lewis
Scott F. Lamoureux
Alexandre Normandeau
Hilary A. Dugan
spellingShingle Ted Lewis
Scott F. Lamoureux
Alexandre Normandeau
Hilary A. Dugan
Hyperpycnal flows control the persistence and flushing of hypoxic high-conductivity bottom water in a High Arctic lake
Arctic Science
hyperpycnal flows
hypoxic high-conductivity bottom water
permafrost degradation
climate change
polar limnology
author_facet Ted Lewis
Scott F. Lamoureux
Alexandre Normandeau
Hilary A. Dugan
author_sort Ted Lewis
title Hyperpycnal flows control the persistence and flushing of hypoxic high-conductivity bottom water in a High Arctic lake
title_short Hyperpycnal flows control the persistence and flushing of hypoxic high-conductivity bottom water in a High Arctic lake
title_full Hyperpycnal flows control the persistence and flushing of hypoxic high-conductivity bottom water in a High Arctic lake
title_fullStr Hyperpycnal flows control the persistence and flushing of hypoxic high-conductivity bottom water in a High Arctic lake
title_full_unstemmed Hyperpycnal flows control the persistence and flushing of hypoxic high-conductivity bottom water in a High Arctic lake
title_sort hyperpycnal flows control the persistence and flushing of hypoxic high-conductivity bottom water in a high arctic lake
publisher Canadian Science Publishing
series Arctic Science
issn 2368-7460
publishDate 2018-12-01
description 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 4 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 and 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 was 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. Results suggest that hyperpycnal flow frequency will increase and HCBW persistence will decrease with projected climate change due to an increase in fluvial SSC inflow. Water density changes resulting from increased electrical conductivity and water temperature are not likely to have a similarly large effect on hyperpycnal flow frequency and HCBW.
topic hyperpycnal flows
hypoxic high-conductivity bottom water
permafrost degradation
climate change
polar limnology
url https://doi.org/10.1139/as-2017-0022
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