Biogeochemistry of Lakes in the Mackenzie Delta

Regions: Inuvialuit Settlement Region, Gwich'in Settlement Area

Tags: physical sciences, water quality, hydrology, carbon dioxide, carbon, methane, nutrient levels

Principal Investigator: Lesack, Lance (23)
Licence Number: 15683
Organization: Department of Geography, Simon Fraser University
Licenced Year(s): 2017 2016 2015 2014 2010 2009 2007 2006 2005 2004 2003 2002 2001 2000 1999 1998 1997 1996 1995 1994 1993
Issued: Jun 05, 2015

Objective(s): To improve our understanding of microbial carbon-processing in Mackenzie Delta lakes and how it is affected by the changing water levels; and to decipher the impact of water level changes on the ability of the Mackenzie Delta to affect riverine nutrient flow to the ocean.

Project Description: The Objectives of this research are to: 1) Improve our understanding of microbial carbon-processing in Mackenzie Delta lakes and how it is affected by the changing water levels; and 2) Decipher the impact of water level changes on the ability of the Mackenzie Delta to affect riverine nutrient flow to the ocean.

Specific activities for the coming field season include the following:

(Goal 1) Improve understanding of microbial carbon processing in Arctic delta lakes - This work will help resolve what drives microbial communities in Mackenzie Delta lakes to release the carbon in these waters to the atmosphere or to convert the carbon to a form consumed by fish and other organisms. Field work over the next 5 years will be based on four areas within the delta, plus delta channels by the water gauging stations of Water Survey Canada, where the research team have worked extensively in the past.

Objective (a): Assess patterns of methane production among Delta lakes – the research team expect that macrophyte-rich lakes are stronger methane producers than thermokarst lakes because C-quality for methane-producing bacteria is higher in macrophyte-rich lakes.

This will be assessed by tracking water column levels of dissolved methane and CO2 during years 1-3 in our long-term lake-study network. All fieldwork will be based from the Aurora Research Institute in Inuvik. Detailed weakly measurements of methane/CO2 behavior during open-water (from June through August) will be compared in 2 thermokarst lakes versus 2 macrophyte-rich lakes versus 2 high flood-frequency lakes within Delta Lakes - Area 1. These lakes will be accessed from Inuvik by boat.

Lake-water samples for dissolved gases and dissolved organic-carbon content, and underwater light transparency also need to be collected in a larger set of lakes (from within Delta Lakes - Areas 1-4) at 3 differing times from just after ice-out (early June) until late summer (latter August) conditions. Based on past experience, these samples can be collected from the helicopter floats and the flying can be completed in one day.

Objective (b): Assess extent of under-ice methane accumulation among delta lakes – The research team expect that lakes with highest levels of open-water methane production will yield the highest levels of under-ice accumulation. The research team also expect that under-ice accumulations will now be higher than observed in years prior because of enhanced thermokarst effects associated with the warming climate.

This will be assessed by measuring water methane and CO2 levels in the unfrozen lake waters of late-winter in a set of 40 study lakes within Delta Lakes - Area 1 prior to ice out. All fieldwork will be based from the Aurora Research Institute in Inuvik. Lake-water samples for dissolved gases and dissolved organic-carbon content, and sediment samples for organic-carbon content will be collected in the set of 40 lakes. This requires landing on the lakes and auguring through the ice for sample collection. Based on past experience with ice auguring, this work can be done in a relatively short period by accessing these lakes by helicopter.

The research team makes an effort to publish the results of the work in top-ranked scholarly journals that are subscribed to by the library at the Aurora Research Institute. To make results more accessible to communities in the NWT, I have created and maintain websites on our long-term Mackenzie Delta research http://www.sfu.ca/limnology and our past International Polar Year research (IPY-SCARF) http://www.sfu.ca/ipy. This promotes this research and highlights student opportunities for training in Arctic-based research. The research team have given presentations at ARI Research Forums. The Principal Investigator has given interviews via newspaper (Globe and Mail, Associated Press, Vancouver Sun, Edmonton Journal, News/North), radio (CBC North, Ends of the Earth), TV (CBC Northbeat), and Web-video (Rosenberg International Forum on Water Management in the Mackenzie River Basin). The research team are also happy to give a presentation or meet with anyone that might be interested in hearing about this work.

The fieldwork for this study will be conducted from June 5, 2015 to August 17, 2015.