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Bioindication of atmospheric heavy metals in the lower Fraser Valley, B.C., Canada

University of British Columbia

The atmospheric heavy metal content of the Fraser Valley, B.C., Canada was assessed for 1993 by analyzing lead, cadmium, chromium, nickel, zinc, and manganese content in 62 samples of the common woodland moss Isothecium stoloniferum Brid. Lead, cadmium, nickel and zinc showed a correlated regional distribution with high values in the western more urbanized areas and lower values in the rural eastern areas. Chromium and manganese exhibited a less distinct distribution pattern. Highest values were recorded for the North Shore Mountains relating to increased precipitation and pollutant transport by the local wind pattern from industrial areas in the Port Moody, Burnaby area, where metal readings reached another maximum. Relationships of these findings to population density, land use, traffic and industrial activity were investigated. Historical changes of metal levels in the ambient air of the study area since the early 1960s were examined through analysis of moss specimens from the U.B.C. herbarium. Metal pollution patterns were established for the periods 1960 - 1966 and 1975 - 1980. In addition, changes in metal levels in moss samples from three sites with a continuous collection record since the 1960's are described. A general decline in atmospheric levels for lead, cadmium, chromium, nickel, and zinc was found. The observed decrease reflected the reduction of heavy industries in the area, abandonment of leaded gasoline and the change from oil to gas and elecuicity for space heating. Reduction in atmospheric metals, as determined by the moss method, reflected the general decline in particulate .emission, as determined by the GVRD direct air sampling program. Manganese levels, in contrast, have increased since the 1960s, which might be attributed to the addition of Methylcyclopentadienyl manganese tricarbonyl (MMT) to gasoline, replacing the leaded antiknock additives. Comparisons were made to recent metal levels and historical changes reported from European 'moss method' studies. The potential of the 'moss method' to be used for general air quality assessments was investigated, by comparison to direct air quality measurements of various pollutants and a general air quality index.

Thesis/Dissertation

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2009-01-15

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http://hdl.handle.net/2429/3675

Botany

University of British Columbia

UBCV

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