Influence of water movements and other factors on distribution and transport of heavy metals in a shallow bay (Canada)

Abstract

Concentrations of heavy metals and cyanide in water and sediments were determined from December 1974 to February 1976 in Yellowknife Bay situated in northern Canada. The bay receives a continuous discharge of liquid waste effluents from an operating gold mine. Arsenic reached a maximum concentration of 3100 mg kg(-1) in sediments near the waste source and decreased to minimum of less than 12 mg kg(-1) moving away from this area; corresponding ranges for Pb, Cu, Zn, Hg, and Fe were 13-800 mg kg(-1), 45-785 mg kg(-1), 23-935 mg kg(-1) 35-505 mg kg(-1) and 1.9-6.3% respectively. Although most pollutants were recorded at low levels in the water, arsenic and copper rose to 0.75 and 0.29 mg L(-1) coincident with maximum discharge from the waste source. Overall, water movement (generated by inflowing rivers and wind) was the most important factor governing the distribution of metals in the bay. Although surrounding islands also restricted the movement of pollutants through the bay, water depth, slope of the bottom and organic content of the substrate did not have a measurable impact on concentrations in sediments.