Abstract

Total Zn, Cu, Pb, Co, Ni, Cr, V, Hg, Be, As, Ba, and Se concentrations vary regionally and in response to textural variations of the sediments of the Bay of Fundy. They are, except for local anomalies, at or near natural levels in relation to their source rocks and other unpolluted marine sediments.Chemical partition indicates that small but significant amounts (1–27%) of the total element concentrations are potentially available to the biota. Potential bioavailable metals are derived from natural and industrial sources and are held in the sediments by fine grained organic material (Hg, Pb), hydrous iron oxides (Cr, V, Co, Pb), ion exchange positions (Zn), and calcareous components (Cu, Zn, Ba).Of the total metal content, however, 73–99% is not readily available to the biota but held in various sulphide (Zn, Cu, Pb, As, Se), oxide (Cr, Ni, Co, V), and silicate minerals (Cr, V, Co, Ni). The host minerals have accumulated at the same rates as other detrital material except for particles of zinc oxide that have been derived from industrial sources adjacent to the Bay of Fundy. The accumulations of fine grained host minerals are the main control on the abundance and distribution of Hg, Be, Zn, Pb, and As in the sediments whereas the dispersal of the ferromagnesian silicates and various oxide minerals, rather than the grain size of their hosts, accounts for dispersal of Cr, V, Co, and Ni in the sediments. These factors together with the present depositional pattern of the particles account for the accumulation and relative enrichment of most metals along with other fine grained materials in the "Quoddy region" of the bay. Local anomalies of detrital minerals related to bedrock exposures also account for high concentrations of Cr, V, and Ni in the vicinity of Grand Manan Island and along the Nova Scotian coast. Relatively high metal concentrations also occur near a dredge dispersal site off St. John Harbour and may reflect the initial impact of anthropogenic inputs on the natural levels of metals in the Fundy sediments.

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