Oil Spills and Contaminants

From 1974 to 1977, when the trans-Alaska pipeline was first built and operated, more than 16,000 hydrocarbon spills, totaling more than 265,000 l, occurred along the pipeline route. During 1985-1986, 952 spills were reported on the North Slope, totaling 731,8001. Most of these spills consisted of refined petroleum products and occurred on water or in gravel pads, although some occurred on terrestrial vegetation. Oil does not penetrate deeply into saturated soils, but spills on dry sites are absorbed by mosses and the underlying organic material and mineral soils. Sedges and willows are the first vascular plants to reappear following a terrestrial oil spill. Recovery from diesel spills is extremely slow, whereas spills of crankcase and crude oil are generally able to recover more quickly (in less than 30 years).

Local and migrant populations of marine and littoral wildlife faced many problems as a result of the large amount of oil spilled by the Exxon Valdez into Alaska's Prince William Sound. While some effects still persist, many damages were relatively short-lived because the region is essentially free of ice year-round and thus water temperatures are much warmer than in the true Arctic. Were such a spill to occur in the Beaufort Sea, or another similarly northern area along the Arctic Ocean's coast, the initial cleanup effort could be seriously hindered by the presence of sea ice. Furthermore, the breakdown of contaminants within the marine environment would be extremely slow. Therefore, the negative effects may persist indefinitely, disrupting potentially all segments of the affected ecosystem, from the lowest phytoplankton up to the top carnivore, the polar bear.

Besides localized spills of hydrocarbons, many other more diffuse contaminants are transported to the Arctic via ocean currents, winds, and rivers. These include radionuclides, heavy metals, and persistent organic pollutants (POPs). Some of these, such as radionuclides, tend not to be taken up in the marine food web. Others, such as some heavy metals and most organic pollutants, concentrate in living things, especially in the fatty tissues that are common in Arctic animals, posing danger not only for the animals but also for humans who subsist on them.

0 0

Post a comment