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ABSTRACT/Gold mining activities generated wastes with high concentrations of arsenic and zinc in the vicinity of YelIowknife, Northwest Territories, Canada. Some of the waste material has been discharged into Yellowknife Bay of Great Slave Lake. Concentrations of arsenic and zinc were determined in sediment cores collected at the depositional areas of Yellowknife Bay. Sedimentation rates were estimated using two different radiometric approaches: the depth profiles of Cs-137 and Pb-210. Geochemical composition of the sediment cores indicated input of similar material into sampling areas over the past 50 years. Age profiles of the sediment constructed from the radionuclides measurements were used to determine historical trends of arsenic and zinc inputs into Yellowknife Bay. The historical record was in good agreement with implemented remedial actions and usage patterns of both elements.

Nonapatite phosphorus concentrations in sediment cores from five mainstem lakes and two sloughs indicate that most Prairie water bodies were eutrophic prior to European settlement and agricultural development of the region. Nonapatite phosphorus increases towards the sediment surface are attributed to urban and/or agricultural effluents. Organic phosphorus increases towards the sediment surface are considered as evidence of post‐settlement increases in lake productivity. Surface sediment increases in nonapatite inorganic phosphorus are the result of urban and/or agricultural effluents modified by upward migration and pooling. Declines in surface sediment nonapatite inorganic phosphorus are evidence of internal loading.

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