Impact of esturine cation exchange reactions on the true carbon export budget of the Mackenzie river.

Regions: Inuvialuit Settlement Region, Gwich'in Settlement Area

Tags: surface water, carbon fluxes, sediment transport, climate, minerals

Principal Investigator: Tipper, Edward (1)
Licence Number: 17112
Organization: University of Cambridge
Licensed Year(s): 2022
Issued: Aug 17, 2022
Project Team: Luke Bridgestock, Emily Stevenson, Alisdair Knight, Edward Tipper

Objective(s): To determine the impact of cation exchange between minerals and surface waters and quantify the release from the exchange pool as fresh water enters the oceans.

Project Description: This licence has been issued for the scientific research application No.5269.

This project will determine the impact of cation exchange between minerals and surface waters and quantify the release from the exchange pool as fresh water enters the oceans. This will be achieved through careful sampling of suspended sediment and water from regions of fresh to saline waters of the Mackenzie River.

Salinity can vary both horizontally and vertically from the mixing of fresh water with seawater through the Mackenzie estuary, and such mixing zones also vary as a function of seasonality and daily tidal incursions. The team need to collect samples from freshwater through to saline water, therefore the team have chosen sample sites based on previous measurements of salinity in the region to guide sampling locations.

To collect a suite of Suspended Particulate Matter (SPM) from Kugmallit Bay (Mackenzie estuary) the team will choose a variety of salinities based on real-time salinity measurements from a salinity-depth gauge which can hook up to the sampling rig on the back of a local boat. Depending on the time, tide and boat position within the estuary the team can either take surface or depth measurements along a salinity transect within the delta. Sediment concentration and salinity with depth, will be determined using a salinity probe and acoustic probe (LISST) prior to sampling. To complement samples the team will collect cross sectional and longitudinal ADCP transects to map the flow of water and sediment mixing at a given sample site. The team will also collect a freshwater sample, using the same technique, from the Mackenzie River.

After fieldwork, the SPM samples across the salinity gradient will be analysed for their mineralogy (XRD) major element exchangeable compositions (ammonium chloride extracts) and calcium, magnesium, strontium, and lithium isotopes to quantify the amount and processes associated with exchange during the mixing of saline waters on the release of ions from the exchange pool to the water.

In the first instance the team will be collaborating with the local community through the Tuktoyaktuk Hunters and Trappers Committee and the Tuktoyaktuk Community Corporation. The team will also be informing the local community of planned activities at least one month in advance so that any questions from the local community can be addressed and answered. This can be achieved through contacts on the Hamlet of Tuktoyaktuk website where local administrators and community members can be reached. Once in Tuktoyaktuk the team intend to use local facilities such as shops, restaurants and bed and breakfasts, investing financially in the local community. The team will give the community regular updates on the progress of the research and data the team have produced. Any outreach products and publications will be shared with the community, in both original form and plain language versions/summaries.

The fieldwork for this study will be conducted from August 20, 2022 to September 30, 2022