UBC Theses and Dissertations
Hydrocarbon pollution from urban runoff in the Brunette watershed Larkin, Gillian Alexandra.
During the first half of the twentieth century, the Brunette watershed underwent rapid urbanization with water resources largely forsaken in the name of development. Urban runoff has been recognized as the major continuing source of contaminants to the urban streams. This study examines hydrocarbon pollution in the Brunette watershed. Total petroleum hydrocarbon (TPH) concentrations were determined in lake core sediments, streambed sediments, stormwater and street surface sediments from throughout the watershed. The lake core sediments provided a record for change ; TPH concentrations increased tenfold over the last 200 years, due to regional development and anthropogenic inputs. TPH concentrations found in streambed sediments were generally higher than those cited in the literature (up to 4800 ug/g), indicating some highly contaminated areas. Streambed sediments from industrialized regions had the highest TPH concentrations, implicating highly developed areas as sources. Hydrocarbons found in stormwater were predominantly aliphatic (66.8 - 92.1%) and particulate associated (75.3 - 96.7%) ; mean concentrations (0.96 - 5.79 mg/L) were similar to those reported in the literature. Suspended solids and hydrocarbon loadings were greatest during the first flush ; TPH concentrations were measured as high as 8.6 mg/L. The influence of catchment land use, dilution of street runoff by the stream volume, and traffic intensity on mean hydrocarbon concentration in stormwater runoff is evident. Relationships between hydrocarbon concentration and Microtox® EC50 values suggest that hydrocarbon content is a consequential contributor to stormwater toxicity. TPH concentrations were remarkably uniform in street sediments from throughout the watershed (average 5812 ug/g). The exception was parking lots where concentrations were considerably higher (6629 - 12111 ug/g). Suspended solids in stormwater are considerably enriched in hydrocarbons compared to their source street surface sediments. Oil stains in traffic lanes and parking stalls implicate road washoff as the source. This study found that hydrocarbon pollution is prevalent in the Brunette watershed. The watershed lacks responsible, sustainable resource management. Actions such as restructuring institutions to form an effective framework, creation of economic incentives, installation of management technologies, use of source control measures, reclamation projects and expansion of public education programs are needed to generate results.
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