ABSTRACT. Detailed observations, mapping and sampling were conducted following an experimental spill of 15 m3 of crude oil adjacent to the coast at Cape Hatt, Baffi Island, N.W.T. The beach could not retain all of the oil that reached the shoreline, and as a result, one-third of the spilled oil was recovered in cleanup activities on the water, approximately one-third was lost to the atmosphere and to the Ocean and one-thrd remained stranded on the intertidal zone. The stranded oil was subject to natural cleaning processes during approximately 6 months of open-water periods from 1981 to 1983. Over this period the surface area of oil cover was reduced by approximately half, whereas estimates indicate that 80% of the oil initially stranded (5.3 m3) was removed. This natural removal of stranded oil occurred in a very sheltered environment. The reduction of the surface area and of the volume of oil resulted primarily from the physical processes associated with wave activity and ground-water leaching. By 1983 an asphalt pavement had developed in the upper intertidal zone on the beach-face slope. Total hydrocarbon concentrations of samples collected from the asphalt pavement indicated a significant increase in oil-in-sediment values in this zone to concentrations in the order of 2-5%. Oil removed from the beach was transported into the adjacent nearshore bottom sediments, where oil concentrations increased sixfold between 1981 and 1983. Physio-chemical weathering rates were relatively rapid immediately following the release of the oil, as the lower molecular weight (Cl to CIO) hydrocarbons evaporated. Subsequent physio-chemical changes were heterogeneous: weathering and biodegradation progressing slowly where oil-in-sediment concentrations exceeded 1%. The primary conclusion from the investigations undertaken to date is that oil is removed in substantial quantities from the intertidal zone even in such a sheltered, low-energy arctic environment. Similar changes should also be expected from comparable environments in lower latitudes. Key words: oil spill, natural oil weathering, asphalt pavement, beached oil RÉSUMÉ. On aeffectué des observations, des prises d'échantillons et des relevés détaillés à la suite d'un déversement expérimental de 15 m3 de pétrole brut, à proXimit6 de la côte du cap Hatt à l'île Baffin (T. N.-O.). La plage n'a pas pu retenir tout le pétrole qui a atteint le rivage, et il a fallu en enlever un tiers de la surface de l'eau lors d'op6rations de nettoyage. Un autre tiers environ a été éliminé par evaporation et par dissolution dans l'océan, et le dernier tiers est rest6 échoué sur la laisse. Ce p6trole &houé a kt6 soumis à des processus de nettoyage naturels pendant les périodes d'eau libre totalisant environ 6 mois entre 1981 et 1983. Pendant cette. période, la surface couverte de pétrole a diminué environ de moitié, et on estime qu'environ 80% du volume original du pétrole 6choué ( 5 3 m3) a été éliminé. Cette élimination naturelle du pétrole échoué s'est produite dans un environnement trks abrit...

Oil was laid down in a series of experiments at Cape Hatt, Baffin Island, N.W.T., on pairs of control plots in the upper intertidal zone at four beach sites, each with a different wave exposure, and on backshore pairs of control plots at two sites. The control plots were established as a basis for comparison with a series of intertidal shoreline cleanup experiments. Sites with different wave-energy exposures were selected in order to provide a range of energy level environments and also a variety of intertidal sediment characteristics. The experimental design of this phase of the project attempted to reproduce conditions similar to those that would result from a large spill. At each location one plot was oiled with an aged Lagomedio crude oil and the other with an emulsion of water in aged crude oil. Replication of total hydrocarbon (t-h) analytical results within and between plots initially proved difficult due to the variability of grain size and to the presence of pooled oil on the beach surface. Although the subsequent collection of large (2.4 1) composited samples reduced this element of variability in the t-h data sets, changes through time or differences between plots were considered significant only if these were in the range of one order of magnitude or greater. At the gravel beach sites the initial retention of oil on the intertidal emulsion plots was considerably less than on the aged oil plots, probably as a result of the different adhesion properties, viscosity and density of the emulsified oil. Observations and measurements indicate that there was a maximum loading of oil that is believed to be a function of (1) the size of sediments and of the surface interstitial spaces; (2) the surface properties of the sediment particles (including wetness and dryness of the surface); (3) the level of the water table; and (4) the type and volume of the oil. On the most exposed of the four intertidal locations over 99% of the spilled oil was removed from the surface of the plots within 48 h. This removal was due to the mechanical energy of wave action and to sediment redistribution (erosion). At the more sheltered sites, oil was removed by rising tides after application of the oil. Rates of oil removal from the two sheltered beaches varied independently of wave exposure. Observations and analytical results indicate that after seven or eight days dispersion and edge effects became significant on the intertidal plots. Data from the intertidal plots, therefore, were considered to replicate patchy oil contamination and were not representative of large natural spill situations beyond one week after the oil was laid down.

ABSTRACT. A series of experiments was conducted to evaluate selected countermeasures for the cleanup of oil on remote beaches. These experiments formed part of the Baffin Island Oil Spill (BIOS) Project, which was conducted at Cape Hatt, N.W.T., between 1980 and 1983. An isolated lagoon was selected with a series of segregated bays that could be used for discrete experiments with control and countermeasure plots. Intertidal control plots were established in 1980 at an exposed site and at a relatively sheltered location. The oil on the exposed intertidal control plot was removed rapidly by natural processes so that subsequent attention was focused on low wave energy sites. Countermeasure experiments were conducted in 1981 in the intertidal zone at a relatively sheltered site and in 1982 in the intertidal and backshore zones at a very sheltered beach. At each of these two locations, control and countermeasure plots were duplicated using an aged Lagomedio crude oil and a water in aged Lagomedio emulsion. Countermeasures were selected for testing on the basis of existing experimental or practical knowledge and the applicability to remote or arctic beach environments. The selected techniques were incendiary combustion, mechanical mixing, chemical dispersion, solidifying and low-pressure flushing.Samples of surface and subsurface sediments were collected throughout the experiments for total hydrocarbon and GUMS analysis. Two chemical dispersants (BP 1 lOOX and Corexit 7664) were effective on the relatively sheltered beach but neither was effective on the very sheltered beach due to the lack of wave energy to agitate or to redistribute the oiYdispersant mixture. The mechanical mixing of backshore sediments accelerated the removal of surface oil but increased subsurface hydrocarbon concentrations. Low-pressure flushing on the very sheltered fine-grained beach did not reduce surface hydrocarbon concentrations and resulted in higher oil in sediment concentrations when compared to an adjacent control plot. The solidifying agent was an effective method for encapsulating oiled beach sediments. Over a five-to six-week period the control plot data indicates that rates of natural cleaning resulted in similar total hydrocarbon values when compared to the Countermeasure plots. However, these results must be considered in the context of edge effects and dispersion that are a function of using small (10 m X 2 m) intertidal plots. Such plots represent only patchy contamination. AS the experimental concept was aimed primarily at the cleanup of heavily contaminated beaches, the primary evaluation of the countermeasures relates to data obtained only from the first week of each experiment. Neither the incendiary device nor the low-pressure flushing techniques proved to be effective, whereas over this short period mixing and chemical dispersion demonstrated a potential to mitigate the effects of beach contamination or to accelerate the removal of stranded oil. hydrocarbures et pour l'analyse par CG/SM. Deux agents de dispersion chimiques...

Field studies on a remote, sheltered gravel beach have monitored the fate of 15 m3 of aged medium crude oil that was released onto the water surface and allowed to strand. The initial volume of oil (5.3 m3) retained on the shore in August 1981 was reduced to 1.3 m3 by August 1985, but oil that had been contained within an intertidal asphalt pavement remained relatively unweathered. By 1985, the pavement accounted for almost 30% of the oil remaining on the beach, even though it covered only 5% of the contaminated area. Oil-in-sediment concentrations remained high in the pavement samples (19,000 mg/kg); elsewhere on the beach, the concentrations in surface sediment samples ranged between 50 and 4,000 mg/kg, and the oils had undergone considerably greater evaporative weathering and biodegradation.

Field experiments have been conducted on arctic beaches to assess the effectiveness of dispersants for the cleanup of stranded oil. The application of two commercially available chemical dispersants to aged and emulsified oil plots, in the intertidal zone on a semi-sheltered beach, resulted in a significant reduction of oil loadings immediately following the experiment as compared to loadings on adjacent intertidal control plots. The use of dispersants may, therefore, be of some value in mitigation of the potential adverse effects of oil immediately following stranding. In the semi-sheltered arctic environment in which the 1981 experiments were conducted (fetch up to 100 km; two-month open-water season), natural reworking of the oiled intertidal control plots over a 40-day period was effective in removing approximately 85 to 95% of the original oil loading. Further experiments in 1982 replicated the 1981 study in a more sheltered location, with a fetch area of less than 2 km, and indicate that the use of dispersants was not effective in this very low-energy environment. The conclusions drawn from this arctic experiment have a direct relevance to other coastal environments in lower latitudes.