Reading Water Quality Record in West Kitikmeot/Slave Sediment

Organization / Researcher: DIAND, Brian Latham / Glen Stephens

Length of Project: 5 years - Approved for one year only (with costs split over two years) (1996-1998)

Personnel involved: Only two as work was highly specialized

Total Project Cost: $29,900

Sediment in lake bottoms can provide a record of the condition of surrounding areas over time. As land is worn away by water and wind, eroded particles wash into lakes forming layers with older materials lower down and recent accumulations nearer the top. Materials in the sediment layers include metals and chemicals from the water, skeletons of tiny diatoms (algae), remains of other plants and animals living in the water, pollen from plants growing near the lake, as well as bits of soil and rock. Long term data show the natural variability, so that interpretation of any change in the future can be placed in an historical context.

In this project, sediment from two lakes north of Lac de Gras, near the Ekati Diamond Mine, was removed and examined to provide an understanding of conditions in the area over the last hundred years. Researchers lowered a sampling device containing a hollow tube into the lake bottoms and brought up sediment cores of up to two metres long.

Sediment cores from Slipper Lake show pristine, clean conditions with increasing acidity beginning around the year 1820. The cores also indicated a period of less ice cover (longer open water conditions), and/or more active mixing of the water from the early 1820s to the present. The algae, in particular, provided a useful measure of changes over time, and may indicate long-term climatic warming. Analysis of metals in the cores showed no significant change over time. The sediment cores taken from the second lake, Lac du Sauvage, were not usable.

Results from Sediment Cores Collected from an Arctic Tundra Lake, NT (1999)