Abstract

A 60 cm long sediment core from Deer Lake, Burnaby, British Columbia was analyzed palynologically and geochemically in order to trace the effects of human disturbances since settlement. A settlement horizon was identified at 42.5 cm (ca. 1892) by pollen analysis. Declines in the percentages of coniferous tree species are mirrored by rapid increases in red alder and fern spores, and also by the presence of indicators of human influence, including introduced weeds, ornamental trees and herbs, and corn pollen.Geochemical analyses revealed marked increases in sedimentary aluminum, iron, potassium, titanium, and strontium soon after settlement, coinciding with declines in carbon, nitrogen, and sulfur. A corresponding shift from a highly organic gyttja to a silt- and clay-rich sediment also confirms the increased input up to the present day of inorganic sediment derived from soil erosion in the Deer Lake catchment.A peak in copper at 19 cm was attributed to the deliberate introduction of copper sulfate around 1957, and increasing lead concentrations are correlated with post-1947 traffic increases. Peak radioactivity of the fission product cesium-137 is recorded at 17 cm, probably corresponding to the maximum in above-ground bomb testing of 1963. Sediment accumulation rates were relatively constant from settlement until 1963 (0.3–0.4 cm year−1), increasing to 1.06 cm year−1 since then. An increased pollen influx since 1963 suggests a recent increase in runoff and soil erosion.

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