The soil temperatures from plot 113 and the adjacent untreated area were measured but not 

 reported here. No appreciable differences were observed between treated and non-treated. The 

 method of application of the crude oil achieved one of its objectives - enough of the oil was kept 

 off the vegetation and the soil surfaces so that no increase in temperature was recorded because 

 of greater absorption of solar energy. Therefore, any damage observed should be caused by the 

 oil itself and not as the indirect result of increased temperatures. 



In order to determine the depth of penetration of the oil, soil cores were taken, sampled, aiid 

 analyzed for the presence of hydrocarbons. Several conclusions can be drawn from these pre- 

 liminary data: 



1. The oil penetrated in some cases to the permafrost on the drier soils of site 1, but did not 

 penetrate much below the organic layer on the wetter site 3, even with the heavy application. 

 Possibly the standing water at the time of application prevented the downward movement of the 

 oil. Even though the surface water had drained by July, the oil no longer penetrated the soiL 



2. The organic matter, although quite wet at the time of application, was capable of absorbing 

 large quantities of oil. This was particularly noticeable on the wet site with its thicker organic 

 layer. When a buried soil organic layer was encountered, it absorbed much more oil than the ad- 

 jacent soil. 



3. There appear to be no natural constituents of the soil or of the living or dead biota that 

 interfere with the soil-hydrocarbon test. This makes the extremely simple test widely applicable. 



The failure to detect downward movement of the oil in the wet site after the standing water 

 had drained indicates that most of the volatile fraction of the oil had evaporated before recession 

 of the water, thus increasing the viscosity of the oil and making it relatively immobile in the sur- 

 face organic matter at the prevailing temperatures. This seems reasonable, since it is known that 

 from 30 to 50% of an oil spill will evaporate in 50 hours under temperate region conditions. Al- 

 though the temperatures were lower at Barrow than they would be in temperate regions, the oil had 

 a longer period to evaporate (the surface waters took at least a week to drain). More important is 

 the fact that many important phytotoxic components of the crude oil are lost with the volatile 

 fraction. 



Data from temperate regions indicate that damage to plants can be expected at soil hydrocar- 

 bon levels above 20 mg/g dry soil. Lethal levels of oil occur around 40 mg oil/g dry soil. Ob- 

 served levels of hydrocarbons in the present study were at least double these values. Such levels 

 would probably result in severe injury and death in temperate climates, but the full effects in the 

 arctic climate and soil conditions are not known at this time. 



Comparison of soil respiration between control and oil-treated areas generally showed that 

 the most active soil layers were at the surface and at the bottom of the core. The layer just below 

 the top 3 cm of soil was usually the least active. The soils from site 3 had a respiration rate 

 more than five times that at site 1. The difference was maintained throughout the soil profile. 



Based on limited data, the heaviest oil treatment (12 liters/m') produced, on the average, a 

 two-fold increase in respiration over the untreated control. In no instance was oil observed to 

 inhibit soil respiration. Although penetration of oil into the profile on the wet site was not detect- 

 able by the fluorescent comparator technique, respiration was stimulated throughout the profile. 

 This suggests some component of crude oil was in fact percolating below the surface even though 

 petroleum components are extremely insoluble in water. 



Data from the fertilizer treatments were very limited. At this time, no conclusions can be 

 made. Based on the literature and pilot studies, an increase in respiration rate would be expected 

 when fertilizer is applied to an oil spill. Added mineral nutrients probably allow a more rapid 

 microbial population response and hence an increase in measurable oxygen consumption. 



77 



