A review of heavy metals contamination within the laurentian great lakes

Abstract

Heavy metals are ubiquitous in the Great Lakes basin at a wide range of concentrations. Their historical sources are associated with geological settings of the area, while contemporary ones are attributed to anthropogenic activities of the watershed’s inhabitants. Four heavy metals in particular can be credited with the development of this area: copper, iron, lead, and mercury. Copper has been mined and processed in the Lake Superior basin for almost 10,000 years, while the iron industry history impacts are relatively new, dating back to the nineteenth century. It was iron however, which first prompted widespread development of the region, due to its high demand and extensive use. Also, lead and mercury can be credited as elements marking critical moments in local economic progress: lead, as an exponent of the auto-moto industry, and mercury as a side pollutant of coal burning and as a determinant of the chlor-alkali industry. The following description of the Great Lakes status in relation to metals has been drawn based mostly on sediment contamination, since this compartment of the environment is considered an “archive” for most of the aquatic pollutants. A review of metal loadings in the Great Lakes shows a fascinating history of the civilizational progress and efforts and also scientific accomplishments in metal research. Temporal patterns of metal concentrations showed the highest values around the 1950s, followed by a generally decreasing trend attributed to notable achievements in emission reduction and remediation efforts. Although such a trend is a most desirable attainment and conclusion, still much remains to be considered in this field, especially in light of potential future climatic changes.