NWT RESEARCH DATABASE

Regions: North Slave Region, South Slave Region

Tags: physical sciences, mining, limnology, land use planning, environmental baseline, aquatic environment

Objective(s): The objectives of this project are to characterize the baseline water and sediment quality within the Thor Lake area, and to characterize the baseline aquatic community through the collection of phytoplankton, zooplankton and benthic invertebrates.

Project Description: The objectives of this project are to characterize the baseline water and sediment quality within the Thor Lake area, and to characterize the baseline aquatic community through the collection of phytoplankton, zooplankton and benthic invertebrates. Water, sediment and aquatic organisms will be collected from 20 stations within the Thor Lake area. Most stations will be accessed by ATV and/or boat in summer and fall, and snowmobile in winter. Several stations will require the use of a helicopter for access. A multi-parameter meter will be used to obtain depth profiles of temperature, oxygen, pH and conductivity in the field. Water samples will be collected at two to three depths at each sampling station, depending on lake characteristics. Water samples will be analysed for routine parameters (e.g. turbidity, total suspended and total dissolved solids, alkalinity, major ions), nutrients, total and dissolved metals, dissolved organic carbon and radionuclides (lead-210, radium-226, radium-228, thorium-228, thorium-230 & thorium-232). Sediment samples will be collected from the lake bottom at three locations around each lake station. Sediment samples will be analysed for total metals, total organic carbon, total phosphorus, total kjeldahl nitrogen, organochlorines, radionuclides, PCB congeners, and particle size distribution. Phytoplankton samples will be collected during spring and summer; species composition, abundance, chlorophyll a and phaeopigment levels will be assessed. Zooplankton samples will be collected with a standard zooplankton net in a vertical tow; samples will be examined for species composition and abundance. Benthic invertebrate samples will be collected with an Ekman grab. Grabs will be sieved in the field and specimens will be collected and preserved; samples will be examined for species composition and abundance. As much as possible, locals will be employed during the baseline study. Information including data and analysis on surface water hydrology and aquatics in and around Thor Lake will be available to locals and communities for review. The information may provide locals with a more thorough scientific overview of the local surface water hydrology and quality which can be used for various purposes (e.g. land use planning, economic development). The fieldwork for this study will be conducted from April 30 to October 1, 2010, within and adjacent to the Thor Lake Property, approximately 100 km southeast of Yellowknife (62 06’ 27” N; 112 36’ 25”W).