Metals in the sediments of the Huron-Erie Corridor in North America: Factors regulating metal distribution and mobilization
Sediment samples from the Huron-Erie Corridor (Great Lakes, North America) were collected to quantify the relative importance of natural and anthropogenic sources of contamination, and to study the spatial metal distribution patterns of metals as a function of the characteristics of the Corridor sediments. A stratified random sampling design was used to measure the spatial patterns of metal inputs, settling and sorting along the length of the Corridor. Factors regulating metal mobilization were assessed by determining metal affinities with the total organic fraction (TOM), the mineral fraction (represented as Al), and the granulometric characteristic (represented as <0.063 mm fraction). The study revealed that anthropogenic factors primarily regulated metal distributions and mobilization throughout the Huron-Erie Corridor. In the St. Clair and Detroit Rivers, the spatial pattern of metal distributions strongly reflected local industrial sources. In the Walpole Delta and Lake St. Clair, however, inorganic (clays) and organic (TOM) particles dominated the contaminant distribution. Sediment contamination issues throughout the Huron-Erie Corridor were dominated by mercury, released from sources along the St. Clair and Detroit Rivers. The mean enrichment factor EFAl for mercury in these sediments has reached 68.3. Other metal pollutants were confined to the sediments in the lower depositional reach of the Corridor.