NWT RESEARCH DATABASE

Regions: Inuvialuit Settlement Region, Gwich'in Settlement Area

Tags: Mackenzie River, biogeochemistry

Objective(s): To directly observe seasonally strongly variable organic carbon concentrations and chemistry of the Mackenzie River and thus its fluxes to Arctic coastal waters.

Project Description: This licence has been issued for the scientific research application No. 5751. The project aims to directly observe seasonally strongly variable organic carbon concentrations and chemistry of the Mackenzie River and thus its fluxes to Arctic coastal waters. We aim for weekly observations of Mackenzie River biogeochemistry resolving the major phases of the hydrological year (winter under-ice flow, spring break-up and freshet, summer flow, and freeze back in fall) over several years with a focus on the loads and quality of dissolved organic carbon. These intra- and interseasonal observations will help to identify potentially changing environmental processes within the catchment, such as permafrost thaw, that are linked to climate change. The research method applied is regular sampling of river water from the Mackenzie River East Channel close to WARC at Carn Road in Inuvik. The sampling location was chosen jointly with WARC personnel and community members at the beginning of the project in May 2023 during a research visit of the applicants. Requirements include safe and easy access to the shoreline or ice throughout the project period and a location upstream of potential sources of contamination, such as boat landing stages. During periods of sufficient ice cover, samples will be taken from below the ice through a hole drilled in the ice. During ice break-up, freeze-up and the ice-free period, samples will be taken from the river bank. On each sampling day, two one-liter plastic bottles and a simple-to-use device to measure water electrical conductivity, temperature and depth (CTD) are taken to the river. The bottles are rinsed with river water and filled, and the conductivity and temperature of the river water are measured with the CTD at the sampling location. Back at WARC, the first sample bottle is split into subsamples for subsequent analyses: Dissolved Organic Carbon (DOC), Colored Dissolved Organic Matter (CDOM), stable water isotopes, total and dissolved nutrients, and a backup sample for other analyses. The DOC, CDOM, and dissolved nutrients subsamples are filtered through a syringe filter into their bottles. The DOC subsample is acidified with HCl. The second sample bottle is filtered through a filter system to derive Particulate Organic Carbon (POC) concentrations. These subsamples are then stored in a cooler/freezer at WARC until shipment to Germany for analyses at AWI’s hydrochemistry lab. In collaboration with the WARC manager, a simple sampling instruction plan has been agreed on. For each sampling, <3 hours will be needed for the preparation, sampling and processing. During yearly visits of the applicants, additional samples will be taken and processed at higher frequency together with the ArcticGRO sampling at that site for comparison. The visits will also be used to check data quality and to collect control samples. For that, we collect multiple samples, use different filter types and investigate the influence of sample storage time on results. All sampling material, consumables and the CTD device will be provided and shipped to WARC by AWI. The sampling material will be prepared as pre-packaged sets of color-coded bottles, syringes and filters. In addition, the plan is to deploy a sensor measuring temperature, electrical conductivity, turbidity, and nutrients in very high frequency (i.e. hourly), if possible, near the sampling location. The sensor is powered by solar panels and a battery on a buoy. The feasibility and potential site of a deployment of this sensor would first be discussed within the community and the ARI/WARC. Reports and copies of all scientific contributions (scientific papers, maps, and databases) were provided to the communities in the ISR through (see attached email and letter). In combination with other projects, we plan to report on the project at all suitable occasions such as workshops and other meetings in Inuvik and Aklavik and Tuktoyaktuk, which gives us a chance to listen to other scientists, community members and WARC staff for ways to improve the observations. For public access, data is being made available via an interactive webpage at https://mackenzie-monitoring.awi.de/. Whenever possible, we will arrange to make presentation at the WARC in order to communicate our activities and results. The project is designed and planned in collaboration with the WARC. The research team collaborates closely with Dustin Whalen (from Natural resource Canada) to build a communication plan for the local community such as visiting school during subsequent sampling campaign. The fieldwork for this study will be conducted from: January 01 - December 31, 2024