Comparative Heavy Metal Transport along Streams Draining Headwater Urban and Urbanizing Watersheds

Session: Poster session

Tim Duval, University of Toronto Mississauga, [email protected]

Abstract

While it is well known that urban streams are subject to impaired water quality, far less research has been directed at the acute modification of stream water quality during the urbanization process. This study determines the role of residential development construction activities on the transport of dissolved and particulate heavy metals along a headwater tributary of the Credit River in Brampton, Canada. Stream sites were sampled daily over a six-month period at locations representing varying stages of subdivision completion (upper site - active construction; middle site - finished construction and natural vegetation; lower site - finished construction and active construction). An adjacent stream draining an urban watershed served as a reference. Heavy metal loads in the urban stream were generally greater than the urbanizing stream, with the exception of a few winter storm events. Along the suburbanizing gradient, the upper stream site dominated by active construction had elevated levels of metals, partiularly aluminum, copper, and zinc. The hydrological connection to a mid-reach zone of no-construction activity / fallow field and native forest resulted in lower metal flux. This suggests that the timing of construction activities and the hydrological connection between the stream and construction activities affect downstream export of metals.

1. Keyword
urban watersheds

2. Keyword
metals

3. Keyword
sediment transport

4. Additional Keyword
urbanization

5. Additional Keyword
headwater