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UBC Theses and Dissertations

Chemistry of tropospheric fallout and streamflow in a small mountainous water-shed near Vancouver, British Columbia Zeman, Lubomir John


This thesis describes the balance between ionic input in precipitation and output in streamflow from a small mountainous watershed, and deals with a detailed examination of ionic concentrations in bulk and wet fallout on a coastal site in the vicinity of Vancouver, British Columbia. The Jamieson Creek experimental watershed in the Greater Vancouver Water District was chosen as an example of a topographically well-defined watershed with relatively watertight bedrock and an undisturbed coniferous forest ecosystem. During the period of November 1970 to October 1971, weekly samples of precipitation and discharge water were analyzed for eleven ionic constituents. The ionic input-output budgets show that there were net losses of sodium, potassium, calcium, magnesium, bicarbonate, sulfate, chloride, silica and phosphate from the watershed in stream-flow. The exceptions were the nitrate and ammonium loads which showed net gains in the watershed. The tropospheric fallout provides most of the ionic loads of the following constituents of discharge water: nitrate, ammonium, sulfate and chloride. The terrestrial sources, however, are the major suppliers of silica, calcium, bicarbonate, magnesium and potassium. Phosphate and sodium are derived equally from tropospheric and terrestrial sources. Continuous daily sampling of bulk fallout and wet fallout was carried out on Point Grey, Vancouver, during the period of December 1971 to April 1972. Although the ionic concentrations in bulk fallout were consistently somewhat higher, the differences between ionic concentrations in bulk and wet fallout were not statistically significant. The relationships between concentrations and rainfall were significant for sodium, potassium, calcium, magnesium, sulfate, chloride, nitrate, silica and ammonium but there were no significant relationships between snowfall and the concentrations of any chemical constituent. Bicarbonate and phosphate do not show any significant relationship with either rain or snow. The bulk fallout on Point Grey was characterized by higher ratios of calcium and potassium to sodium and chloride, and by a lower ratio of chloride to sodium than is found in sea water. These deviations from sea water ratios are ascribed to the contribution of soil dust to the content of calcium, potassium and sodium in bulk fallout. Higher ratios of sulfate to sodium and chloride were observed in the Point Grey results and are ascribed to the influence of anthropogenic sources on the composition of bulk fallout. On the other hand, in bulk fallout on the Jamieson Creek watershed there was a lower deviation of ratios of sulfate to sodium or chloride from the sea water values, suggesting that anthropogenic sources are less influential in the watershed area. However, much higher ratios of calcium, magnesium and chloride to sodium were observed. These indicate that dry fallout contributes substantially to the composition of bulk fallout on the watershed.

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