Ecological characteristics of 35-year-old crude-oil spills in tundra plant communities of the Mackenzie Mountains, N.W.T.

Abstract

In June 1945 the CANOL Crude Oil Pipeline No. 1 from Norman Wells, Northwest Territories, to Whitehorse, Yukon Territory, was abandoned. During its short history, approximately 17 838 500 L of oil was lost through spills and 9 864 400 L was left in the line and storage tanks. Although some burning was done during salvage operations, most residual oil was drained onto the soil surface. Studies in alpine tundra indicate that this oil penetrated up to 60 cm in dry, coarse-textured soils and 8 cm in wet, clay-rich soils. Oil decomposition ranged from complete utilization of n-alkanes to selective metabolism of n-alkanes C12 to C19. Contaminated soils were drier than control soils. This, plus surface blackening and thinning or organic surface layers, resulted in subsurface warming. Floristic similarity coefficients comparing control sites and 27 crude-oil spills varied from 19 to 52. Plant cover was substantially lower on oil spills and in only one community was floristic diversity greater on oil spills than on associated control sites. Dominant colonizers included Cladonia pocillum, Cladonia pyxidata, Rinodina roscida, Carex aquatilis, Carex membranacea, Carex scirpoidea, Epilobium angustifolium, Eriophorum angustifolium, Festuca altaica, Juncus albescens, Poa alpina, Salix planifolia, Solidago multiradiata, and Trisetum spicatum.