Heavy Metal Contamination in the Laurel Creek Watershed, Waterloo (Ontario), Canada

Metal pollution in our watersheds can have numerous and sometimes severe impacts on the health of organisms which interact with the affected water sources. Some metals are required for cellular growth and maintenance as micronutrients, but are toxic at larger doses, while others are not required and are toxic at even low concentrations. Anthropogenic activities provide pathways for these metals to enter waterways, including industrial activities, mining, and transportation. There is currently a limited amount of literature addressing metal budgets and pathways within individual drainage basins, leading to some limitations of the understanding of heavy metal sources and interactions within these basins. Here, we study Waterloo region, and specifically the Laurel Creek drainage basin (80 km2 basin area, population 123,500, precipitation 907 mm/year). The Laurel creek watershed has a myriad of land uses that makes it a perfect local setting for our metal budget approach. This tributary to the Grand River is divided in agricultural land (37% basin area), and a mosaic of residential (32% of basin), commercial (4.5% of basin), and industrial land (7% of basin), with some brownfields constituted of previously active tanneries. Extensive datasets, mostly at very high resolution, are available, both historical and current, including climate, GIS data on land use, drinking water, storm water management and sewage system, particulate levels, and measurements of various other factors influencing contaminant pathways, with ongoing sampling for many of these. Using the data available, along with an available water model and GIS processing, the aim is to create a water and metal budget, following the methodology first presented by Meybeck et al. 2007 (Science of the Total Environment, 375, 204-231). The budget will focus on specific target heavy metals, such as copper, nickel, and cadmium. We anticipate that this work will introduce a more detailed conceptual model for heavy metals in urban settings, with a better description of some overlooked sources. This study will serve as a stepping stone for larger watershed studies.

*Gheith abstract at the conclusion of this publication*