Terrestrial Oil Spills in Alaska: Environmental Effects and Recovery

Abstract

ABSTRACT Damage and natural recovery of terrestrial ecosystems affected by refined petroleum spills along the Haines to Fairbanks military pipeline in Alaska have been investigated. Since the 20-cm-diameter, 1007-km-long pipeline was opened in 1956, there have been 40 reported ruptures along it. Mosses and trees were completely killed, and vegetation is now sparse in the drier portions of the spill areas. Some new vegetation is growing in drainage pathways. The dead organic mat has provided adequate insulation, and only a few instances of slope instability, where slopes exceed 20 percent, have occurred. Through laboratory studies on the rates of microbial respiration in Fairbanks silt containing 15 percent Prudhoe crude, it has been determined that microbial activity is increased by inoculation with mixed-culture oil-degrading microorganisms, increased pH, and phosphorus additions. Microbial activity also responds positively to nitrogen addition after an initial negative response. The negative response varied with treatments, and was not caused by either ammonia or nitrite toxicity. These observations were tested in the field along the pipeline where nitrogen and phosphorus fertilizers were applied in several rate combinations to small plots in a selected automotive gasoline spill area. In addition the plots were seeded with a commercial grass mixture. The objective of this experiment was to determine if microbial degradation of the fuel and revegetation could be enhanced by the addition of fertilizer. There was a positive response in terms of microbial activity and plant growth in the treated plots. It has not been determined at this point if the increase in vegetation response was solely a fertilizer response or related to the increased rate of petroleum degradation.