Sources and Distribution of Metal Contamination in Surficial Sediments of Sydney Harbour, Nova Scotia

Abstract

Geochemical studies in Sydney Harbour indicate that its sediments are contaminated to varying degrees with ’pollution’ metals such as As, Cd, Hg and Pb. Results based on the analyses of 119 surface sediment samples show that above background concentrations of Ag, As, Bi, Cd, Cu, Hg, Mo, P, Pb, Sb, and Zn occur in the sandy muds and muds adjacent to the urban and industrial development on the east side of the South Arm and the Sydney River estuary. The distributions of these metals are more strongly controlled by the individual anthropogenic sources of the metals than by the natural depositional patterns. Flocculation and deposition of anthropogenic material in the immediate vicinity of the sources is of greater importance than the more general dispersal, flocculation and settling of fine grained material in the harbour. Organic matter, which is a significant component of many of these inputs, plays an important role in the sequestering and settling of the metals close to the sources. The distributions of Al, Ba, Co, Cr, Fe, Li, Ni, Sr, Ti and V, on the other hand, are controlled by the dispersal, flocculation, settling and resuspension of fine grained aluminosilicate-bearing sediments in response to natural depositional conditions.