URBAN GEOCHEMISTRY OF VICTORIA, BRITISH COLUMBIA, CANADA

An urban geochemical study was undertaken for the city of Victoria, in southwestern British Columbia, Canada.Since its incorporation in 1862 the city has never been industrially based, and today is primarily a government and tourist center. The municipality covers an area of 18 square kilometers and supports a population of 75,000 individuals. For this study, a total of 304 (245 surface, 59 deep) soil and sediment samples were arbitrarily collected from city boulevards, parks and school yards according to a census tract stratified sampling strategy. Geochemical analysis (ICP-MS) of the samples indicates that high levels of heavy metals are present in select locations. The region is underlain predominantly with volcanic rocks that have a low concentration of Pb (mean = 4.7 ppm), Zn (mean = 40.6 ppm) and Hg (mean = 11.3 ppb). In contrast, surface soils have median levels of 89.8 ppm, 106 ppm and 99 ppb, respectively. Concentrations of certain metals show a classic 'decay curve' and are generally low directly adjacent to roads, increase significantly within the first few meters and then show a progressive reduction with increasing distance from the road. These findings along with a strong significant Pearson's correlation (0.63) between Pb and Zn give a strong indication that elevated levels of certain heavy metals are the result of anthropogenic input rather than natural sources. Although elevated levels of certain heavy metals do not pose a direct risk to most of the population, young children can ingest a significant amount (20-50 mg/day) of soil directly through their hand to mouth activity and may therefore be potentially at risk.