With continued development of Arctic petroleum reserves there has been growing interest in the fate and effects of petroleum hydrocarbons that may be spilled in northern environments. ... There have been a number of studies made during the past decade on the ecological effects of hydrocarbon spillage in the Arctic areas .... [This article offers an overview of some of the research undertaken on this subject since 1970.]
The degradation of Prudhoe crude oil was studied in arctic tundra ponds. Contained subponds were treated with oil and/or oleophilic phosphate or inorganic phosphate fertilizers in an attempt to enhance the degradation of the oil by the indigenous microflora. Enumeration studies of water and sediment samples indicated that oil treatment alone did not increase numbers of total heterotrophic or oil-degrading bacteria over a short period (28 days). It was also shown that oil spilled years previously on 2 whole ponds at a high (10 l/m²) and a low dose (0.24 l/m²) did not alter the microflora quantitatively, except in a small core spilled with oil. Although oil alone seemed to exhibit neither stimulatory nor toxic effects, oleophilic phosphate, added weekly at a concentration of 0.1 mM, significantly stimulated the microflora in the presence or absence of oil. Since equal concentrations of inorganic phosphate failed to induce this effect, the stimulation was attributed to the hydrocarbon portion of the organic phosphate molecule. 14C-hydrocarbon mineralization studies demonstrated that the microflora would mineralize the saturate fraction of the oil before the polyaromatic fraction. It was concluded that oleophilic fertilizers may provide a useful tool to enhance the biodegradation of crude oil spilled on oligotrophic waters.
A sea-curtain enclosed section of a lake 240 km south of Prudhoe Bay, Alaska was exposed to Prudhoe crude oil in July 1976. One year following exposure to the oil, no significant differences were detected between the waters or sediments of the oiled versus control area in rates of turnover of glucose. Total numbers of bacteria were slightly higher in oiled than in control waters. There were no differences in numbers of sediment bacteria. Rates of uptake of hexadecane and napthalene by sediment microbes were not linear with time. Hexadecane was taken up sooner and faster than was napthalene. In 0 some incubations, significantly (88 - 95% probability level) greater rates of hydrocarbon uptake were measured for oiled than for control sediments. Only incorporated, not mineralized, hydrocarbons were measured due to methodological problems. Several methods of using 14C-labelled hydrocarbons in a field situation are presented.
Hydrocarbons and microbial activities in sediment of an Arctic lake one year after contamination with leaded gasoline
Arctic, v. 31, no. 3, Sept. 1978, p. 180-191, 1 ill., 1 map
ASTIS record 1529
Hydrocarbons were found to persist in the sediment of an Arctic lake one year after the lake was accidentally contaminated with leaded gasoline. The contaminating gasoline was continuing to spread from the original site of contamination. High numbers of hydrocarbon utilizing microorganisms were found in the contaminated sediment. Rates of nitrogen fixation did not appear to be affected by hydrocarbon contamination, but potential denitrification activities appeared to be altered by the gasoline. Fertilizer application resulted in a moderate decrease of hydrocarbon concentrations in the sediment.
The effect of oil spilled on Alaskan freshwater phytoplankton populations was studied in waters affected by natural oil seeps, by controlled crude oil spills in tundra thaw ponds and in a morainal lake, by subpond manipulations and bioassay experiments. The studies were carried out over a period of seven years. Regardless of dose the effects of oil were predictable in the small ponds. The zooplankton populations were virtually eliminated, and after an initial depression of primary productivity the photosynthetic rates returned to approximately prespill levels with a small increase in algal biomass. A markedly altered algal composition was an invariable effect of the response, with the elimination of a dominant flagellated form, Rhodomonas spp., in the case of the ponds. From the results of subpond manipulation experiments, evidence supports the hypothesis that elimination of grazers is the principal cause of altered species composition and increased biomass in these ponds. In our lake system there was a severe reduction in primary production during the season of the experimental spill. During the second year only the spring boom was suppressed by the added oil. Bioassay experiments supported the hypothesis that in such lakes, direct inhibition of algal photosynthesis may be important, although zooplankton were greatly reduced.
Bioassay experiments were conducted to determine the relative susceptibilities of three arctic zooplankton species to oil pollution, and the results were compared with the effects of an actual oil spill on a pond near Barrow. In both the bioassays and the pond, the addition of Prudhoe Bay crude oil was toxic to fairy shrimp (Branchionecta paladosa O. F. Müller), which seemed most sensitive, Daphnia middendorffiana Fischer, which was next most susceptible and Heterocope septentrionalis Juday and Muttkowski, which appeared somewhat resistant to the effects of oil. Cyclopoid copepods were the only common zooplankters able to survive the pond oil spill, and these were still present two and one half weeks after the spill. The rapid deaths of the other species, especially the branchiopods, suggest that zooplankton may be the most susceptible of all arctic freshwater organisms to oil pollution.
Aquatic insects are numerous and important in the ecology of tundra thaw ponds, comprising most of the biomass and production. The most common types are the caddisflies Asynarchus and Micrasema, the stonefly Nemoura, the beetle Agabus and especially larvae of the fly family Chironomidae. Studies in vitro showed no detectable mortality of these insects at doses of oil up to 1.5 l/m² Prudhoe Bay crude oil. However, field experiments on two ponds with application rates of about 10 l/m² (Pond E, 1970) and 0.24 l/m² (Pond Omega, 1975) both indicated that selective elimination of Asynarchus and Nemoura had occurred. Chironomidae in Pond Omega displayed much lower rates of adult emergence in 1976 and 1977 than in 1975, immediately before and after oil treatment, with several species in the tribe Tanytarsini most reduced. Pond E did not show low emergence rates, but the proportion of Orthocladiinae was much higher than in reference ponds. Trichotanypus was severely reduced in Pond Omega but unusually abundant in Pond E in 1976 and 1977. Effects of oil seem to be different for different species, and occur at some point during the late larval stages of insects or at metamorphosis, but toxicity experiments did not confirm this. Oil may also interfere with reproduction in insect species which remain mainly on or near the pond surface as adults. Apparent effects in field experiments are not entirely consistent with observations of Canadian researchers. Nevertheless there were several similarities and both followed patterns like those observed in marine benthic communities, such as greater effects on shore fauna, greater effects of low-molecular-weight hydrocarbons, and species-specificity of effects. There is no indication of recovery of Nemoura, Asynarchus or Tanytarsini in Pond E seven years after the spill, but biomass and abundance of the other aquatic insects remains high. We recommend that clean-up measures avoid introducing solvents or dispersants, which might be toxic to insects in the ponds
Effects of crude and diesel oil spills on plant communities at Prudhoe Bay, Alaska, and the derivation of oil spill sensitivity maps
Arctic, v. 31, no. 3, Sept. 1978, p. 242-259, ill., maps
Contribution - Ohio State University. Institute of Polar Studies, no. 355
ASTIS record 1533
Crude oil was spilled on six of the major Prudhoe Bay plant communities at an intensity of 12 l/m². The communities occurred along a topographic-moisture gradient. The reaction of the major species of the various communities was recorded one year following the spills. Sedges and willows showed substantial recovery from crude oil spills. Mosses, lichens, and most dicotyledons showed little or no recovery. On a very wet plot with standing water, the vegetation showed total recovery one year following the spill. Dry plots, on the other hand, showed very poor recovery. Dryas integrifolia M. Vahl, the most important vascular species on dry sites, was killed. Identical experiments using diesel oil rather than crude oil showed all species except an aquatic moss to be killed. A sensitivity index for the communities was calculated on the basis of the percentage cover of the resistant species divided by the original total plant cover of the community. With this information an oil spill sensitivity map for an area of Prudhoe Bay was constructed using a vegetation map as a base. Using the crude oil data from Prudhoe Bay together with some from the literature, a predictive sensitivity map was also constructed for an accidental crude oil spill at nearby Franklin Bluffs. In this example all the community types are considered to have moderate to excellent recovery potential. Implications of the experiments and the mapping exercises for oil spill contingency planning are discussed.
Some effects of oil on the physical and chemical characteristics of wet tundra soils
Arctic, v. 31, no. 3, Sept. 1978, p. 260-276, ill.
Contribution - Ohio State University. Institute of Polar Studies, no. 367
ASTIS record 1534
Crude hydrocarbons were added to the surface of wet tundra soils at Barrow, Alaska at volumes of 5 and 12 l/square metre. Physical and chemical effects in the soil were followed for three years. Soils treated with 5 l/square metre had their chemical and physical properties little altered. Those treated with 12 l/square metre recorded an increase in seasonal thaw, an increase in organic carbon and an increase in available phosphorus. Soil pH shifted toward neutrality. Decreases occurred in water infiltration rate and in plant available cations (Ca, Mg, K). Soil moisture, bulk density, shrinkage percent and total sulphur content appeared unaffected.
The effects on vegetational recovery of removing spilled Prudhoe Bay crude oil from terrestrial sites by burning were observed at three Alaskan locations; Palmer, Fairbanks, and Prudhoe Bay. Five habitat types were studied: 1) abandoned agricultural grass field, 2) the high-brush stage in the secondary succession of interior Alaskan spruce forests, 3) sedge meadow, 4) spruce forest, and 5) wet and mesic arctic tundra. Oil burning was carried out on snow during winter, during the summer growing season and in autumn as soils were freezing. Burning in summer during the growing season was much more detrimental to plant survival than winter burning. Significant amounts of dormant or near dormant vegetation survived hot burns in September where the soil was frozen to a depth of at least four centimeters. Burning spilled oils on frozen soil surfaces at all three locations affected subsequent plant survival less than when soil surfaces were thawed. Plant dormancy, reduced soil permeability, high soil moisture levels and low soil temperatures were the most probable factors contributing to plants surviving oil spills and burns. Heating during the burn failed to raise soil temperatures to levels in the upper soil zone lethal to the perennating buds of grasses and forbs. Spilled oil, permitted to stand (aged), ignited with difficulty or not at all, suggesting the effects of volatilization on combustion potential. Oil that soaked into surface mats of organic matter was also impossible to burn. Attempts to ignite oil spilled on snow during winter at Prudhoe Bay were unsuccessful, possibly because strong winds were rapidly removing volatile fractions. Certain herbaceous plants were relatively unharmed, either by the oil or burning when dormant. Limited damage occurred in winter if the oil was burned immediately after spilling. Delaying burning of oil either 48 hrs or one month after spilling significantly decreased plant survival. In woody vegetation types, plant survival improved slightly where oil was removed by burning. Woody species apparently survived burning and oiling and regrew from stump sprouts. There were two extremes and no intermediate burning situations. Fires either burned rapidly and hot or were impossible to ignite. Heavy black smoke produced during the rapid burns was soon dissipated by light breezes.
Fertilizing and seeding oil-damaged Arctic tundra to effect vegetation recovery Prudhoe Bay, Alaska
Arctic, v. 31, no. 3, Sept. 1978, p. 296-304, ill.
ASTIS record 1633
Vegetational recovery from an accidental oil spill on a wet tundra site at Prudhoe Bay, Alaska, was studied during six growing seasons. The spilled oil consisted of 22° API gravity, Prudhoe Bay crude from which diesel and heating oil fractions had been removed by a topping process. Damages from the winter spill ranged from killing the moss layer and above-grounds parts of vascular plants to killing all the macroflora. Damage to the oil sensitive mosses persisted throughout the study even in lightly oiled areas. Test plots where commercial phosphorus fertilizers had been applied were an exception to this. Moss cover began re-establishing during the first growing season with phosphorus fertilization and continued to improve thereafter. Growth of sedges and grasses, not killed by the oil, was significantly enhanced by phosphorus fertilizations, even though oil persisted in the soil. Revegetation attempts in a barren area during the fourth growing season after the spill resulted in establishing Puccinellia borealis (alkaligrass) seedlings and mosses in phosphorus-fertilized plots. Neither nitrogen nor potassium fertilizers alone and combined with each other improved growth of either resident or seeded plant species on the spill area. The more significant response was to phosphorus.
The physical, chemical and biological effects of crude oil spills on black spruce forest, interior Alaska
Arctic, v. 31, no. 3, Sept. 1978, p. 305-323, ill., maps
ASTIS record 1787
... The overall objectives of the study were threefold: 1) To detail the physical effects of crude oil spills in black spruce forests of interior Alaska emphasizing the mode of transport, area of impact vs. time and effects on the active layer and underlying permafrost; 2) To determine the fate of petroleum contaminants once spilled in subarctic terrestrial environments; 3) To evaluate the effects of crude oil spills on vegetation. ...
This study was conducted on the short-term effects of seasonal spills of hot Prudhoe Bay crude oil on microorganisms in a taiga soil in interior Alaska. Following a winter spill, the filamentous fungal populations were inhibited whereas the heterotrophic bacterial populations were stimulated. After a summer spill there was an initial depression of both the filamentous fungal and bacterial populations followed by a general enhancement. In both oil spill plots, yeasts; along with the denitrifying, proteolytic, oil-utilizing, and cellulose-utilizing microorganisms; were favorably affected by the oil. Soil respiration was also enhanced in the oiled plots. An extended period of study is required to fully evaluate the impact of oil on the soil microflora and the role of these microorganisms in recovery of oil-inundated areas in subarctic ecosystems.
Prudhoe Bay crude oil and refined diesel fuel were applied to five topographically distinct tundra soils at Prudhoe Bay, Alaska. The penetration of hydrocarbons into the soil column depended on soil moisture and drainage characteristics. Biodegradation, shown by changes in the pristane to heptadecane and resolvable to total gas chromatographic area ratios, appeared to be greatly restricted in drier tundra soils during one year exposure. Some light hydrocarbons, C9-C10, were recovered from soils one year after spillages. Hydrocarbons were still present in soils at Fish Creek, Alaska, contaminated by refined oil spillages 28 years earlier, attesting to the persistence of hydrocarbons in North Slope soils.
Long term interactions of microorganisms and Prudhoe Bay crude oil in tundra soils at Barrow, Alaska
Arctic, v. 31, no. 3, Sept. 1978, p. 348-354
ASTIS record 1789
Oil was recovered from tundra soils two and seven years after spillage. Oil persisted in the upper soil layer. The depth of penetration appears to depend on soil moisture and drainage characteristics. Maximal penetration seems to occur within one year of spillage. Biodegradation of the oil was indicated by changes in the ratio of gas chromatographically resolved to unresolved components. Individual components appear to be preferentially degraded, but no evidence was found for significant preferential degradation of structural classes of hydrocarbons. Numbers of microorganisms were different in oil contaminated and reference soils generally showing continued enrichment, but in some soils showing inhibition of microbial populations.
Effect of surface applied crude oil on soil and vascular plant root respiration, soil cellulase, and hydroxylase at Barrow, Alaska
Arctic, v. 31, no. 3, Sept. 1978, p. 355-365
ASTIS record 1790
Surface application of crude oil at 5 or 12 l/m² to polygonal coastal Arctic tundra altered microbial activity in all soil types during three summers after application. Respiration in 5 l/m² oil treated soils increased with decreases in cellulase activity (as endo- and exo-glucanase) and increases in aryl hydrocarbon hydroxylase indicating a shift in the catabolic base of soil microbiota. These trends were paralleled in the 12 l/m² soil, but usually after a lag period of one year, perhaps due to some toxic effect of the oil at high concentrations. These data suggest that tundra soil microbiota can actively modify oil and can utilize it to support metabolism. Higher respiration rates in oiled soils than in control soils suggest that soil microbiota degrade and utilize oil faster than the normal residual plant material
Ectomycorrhizal fungi of Salix rotundifolia Trautv. I. Impact of surface applied Prudhoe Bay crude oil on mycorrhizal structure and composition
Arctic, v. 31, no. 3, Sept. 1978, p. 366-380, ill.
ASTIS record 1791
The effects of exposure to crude oil on the structure and quantity of viable mycorrhizae of the dwarf deciduous shrub, Salix rotundifolia Trautv., have been investigated at Barrow and Cape Simpson, Alaska over a three year period on experimental plots treated with 5 and 12 l/m² of Prudhoe Bay crude oil. Salix rotundifolia populations growing adjacent to the Cape Simpson natural oil seep were examined for possible changes which may have occurred as the result of long term exposure to oil. Structural examination of mycorrhizae was accomplished by light and scanning electron microscopy. Structural difference in viable mycorrhizae were observed between control and oil treated plots one year after the application of oil. Ectomoycorrhizae with smooth mantle surfaces were found to predominate on the Barrow control plot. The predominant viable mycorrhizae on the oil treated plots demonstrated a marked proliferation of mantle hyphae, presumably a result of the altered soil environment. Prudhoe Bay crude oil applied at 12 l/m² caused a large reduction in the number of viable willow mycorrhizae within one week at Barrow. After this rapid initial response, the rate of destruction of mycorrhizae appeared to proceed at a slower rate throughout the remainder of the growing season. The effect of oil in depressing the number of viable mycorrhizae was still apparent three growing seasons after the application of oil. Salix rotundifolia growing adjacent to the Cape Simpson oil seep demonstrated greater numbers of viable mycorrhizae and a higher percentage of Cenococcum graniforme (Sow.) Ferd and Winge. mycorrhizae than did plants at Barrow.
Ectomycorrhizal fungi of Salix rotundifolia Trautv. II. Impact of surface applied Prudhoe Bay crude oil on mycorrhizal root respiration and cold acclimation
Arctic, v. 31, no. 3, Sept. 1978, p. 381-393, ill.
ASTIS record 1792
Ectomycorrhizal root tips of Salix rotundifolia Trautv. removed from Barrow, Alaska tundra treated with 5 or 12 l/m² Prudhoe Bay crude oil on 1 July 1975 showed decreased respiration rates within 48 hr after surface application of oil. Oil treated roots continued to have depressed respiration rates throughout the summer. The following summer, respiration rates of the 5 l/m² oil treated roots were higher than controls. With respiration of the 12 l/m² treated roots only 20% below controls. However, during the summer, respiration rates declined very rapidly, probably due to water stress caused by drought conditions. The third summer, respiration rates of all root samples were quite similar, with all rates low, probably due to continued water stress. Viable root biomass declined from year to year in the oiled soils. Analysis of cold acclimation by Arrhenius plots of respiration rates shows losses in cold acclimation after oil treatment. Ectomycorrhizal roots of S. rotundifolia from the oil impregnated soils of a natural oil seep at Cape Simpson, Alaska showed a minimum loss in respiration rates and cold acclimation after exposure to fresh crude oil.
The effects of two Prudhoe Bay crude oil treatments of 5 and 12 l/square m on fungal hyphae/gm dry wt of soil and on the grams of mycelium/square m were followed in polygonal tundra for three seasons. A significant depressing effect of oil on fungal hyphae was evident over three seasons. However, no significant difference between oil treatments was recorded. The moisture content of the soil appeared to influence the mobility of the oil. Shifts occur in fungal populations in the presence of oil and the presence of oil biodegradation by filamentous fungi was detected. The influence of bulk density on fungal populations and the penetration of oil into tundra soil is discussed.
Summary of the Workshop on Ecological Effects of Hydrocarbon Spills in Alaska
Arctic, v. 31, no. 3, Sept. 1978, p. 408-411
ASTIS record 50243
In any study of the effects of the introduction of an organic compound, such as oil, into a particular environment, such as the Arctic we should, at the outset separate two basic responses: the responses of those organisms (largely bacteria and fungi) to whom the oil is a nutrient to be attacked and eventually decomposed, from the responses of those organisms (largely plants and animals) to whom the oil is a physical and chemical agent of potential toxicity to be tolerated with varying degrees of success. ... both groups really function as mixed populations that exhibit dynamic responses to environmental changes, such as oil spills, but our perception of the effects of these changes is largely population-oriented in the decomposers and species-oriented among higher organisms. ... The actual removal of oil from the Arctic environment depends on a combination of physical weathering and microbial decomposition .... Thus a general principle of microbial ecology is sustained here in that the addition of an organic material to a system stimulates the development of a specific microbial population capable of using that material as a nutrient. The rate of this decomposition process is of maximum importance and it obviously depends on the robustness of the initial microbial population and on nutrient limitation. ... One of the special problems of the Arctic is the very slow rate at which these decomposer populations develop significant activities ... and accessory nutrient supplementations may be required to achieve acceptable rates of hydrocarbon decomposition. A very important facet of oil degradation is the relative rates at which the different components of oil are broken down by bacteria and fungi. ... There are many reasons why oil may be toxic to animals .... Oil appears to constitute a fairly general "contact herbicide" whose direct application is most often toxic to plants. ... plants vary in their sensitivity to this "contact herbicide" and sensitivity mapping ... and bioassays of the sensitivity of specific plants under field conditions are very valuable. ... oil exerts direct and immediate toxic effects on certain plants and animals, in both aquatic and terrestrial systems, and ... more subtle toxic effects are often detected only with the passage of time. Whole populations react in the expected manner in that oil-resistant forms proliferate and then lead the recolonization of the system as the toxic hydrocarbons are removed by weathering or by microbial decomposition. The extent of severe ecological damage from oil spills is, therefore, a function both of the oil-sensitivity of the plant and animal populations and of the rates at which oil is removed by human intervention, weathering or microbial decomposition. ... In the decomposition studies perhaps the most promising development is the advent of rate studies which should be extended to cover the major classes of oil constituents and a very wide variety of ecological systems. ... In many cases it is clear that microbial decomposition, aided by fertilizer application ... will reduce the level of hydrocarbons below the toxic level for the indigenous plants and animals at a satisfactory rate. ... This entire program, with its emphasis on rates of microbial decomposition and on differential sensitivity of both species and populations of higher organisms, is basically well designed and offers a scientific basis for the development ... [of] rational oil spill clean-up policies in the sensitive Alaskan ecosystem.