and methanolic (f~) fractions by silica gel chromatography as described 

 for oil samples Below. Each solvent fraction was concentrated by ro- 

 tary evaporation to 4 ml and radioactivity of a portion of the extract 

 was., .determined in AquasoL.as described above. Using these methods 

 [1- C] -hexadecane and [1- C] -heptaderene standards were recovered in 

 the f 1 fraction, whereas [1(4, 5, 8)- C] -naphthalene was recovered in 

 the fl fraction. CO was transferred from the extracted sediment 

 after acidification ana distillation to a C0„ absorbant trap (Carbo- 

 sorb, Packard). This trap was combined with Aquasol and radioactivity 

 determined as described above. 



Gas Measurements 



Gas subsamples (0.2 to 1.0 ml) were removed from the headspace of 

 incubation vials using a helium flushed 1 ml glass syringe (Glaspak) 

 fitted with a Mininert pressure-lock syringe valve (Supelco) . CH, 

 and C0„ were measured by gas chromatography- gas proportional count- 

 ing using the method of Nelson and Zeikus (1974) as modified by Ward 

 and Olson (1980). This method ensured the specific detection of these 

 gaseous metabolites. All numerical results were based on amounts 

 clearly above detection limits, and quantifiable by integration using a 

 Spectra-Physics Minigrator. C0„ values were corrected for CO^ solu- 

 bility and bicarbonate equilibrium as described by Stainton "t 1973) . 

 Methane concentrations were quantified on a Varian 3700 flame ioniza- 

 tion gas chromotograph as described by Ward and Olson (1980). All 

 values for gas analyses are reported on a per vial basis. 



Chemical Analysis of Oils 



Similar methods were used for the analysis of sediment hydrocar- 

 bons (ERCO) or oils (MSU) although the specific details differed. 

 Sediment hydrocarbon samples were solvent extracted and fractionated 

 according to an analytical scheme patterned after that of Brown et al 

 (1980). Hydrocarbons were separated from methanol-dried samples by 

 high-energy shaking with methylene chloride:methanol (9:1), fraction- 

 ated into saturate, aromatic/unsaturate and methanolic fractions by 

 alumina/silica gel column chromatography, and analysed by gas chroma- 

 tography, mass spectrometry and/or mass f ragmentography as described by 

 Boehm, et al (1981). 



AMOCO CADIZ mousse, fresh or evaporated crude oil, and extracts 

 from ll+ C-hydrocarbon experiments (see above) were analyzed as follows. 

 Each sample (a 25 (Jl aliquot of each oil sample diluted in 0.5 ml of 

 hexane, or extracts described above) was loaded onto a glass column (1 

 cm ID x 20 cm long) packed with 40-140 mesh silica gel (Baker Chemical 

 Co.). Saturate components (f,) were removed from the column by eluting 

 with 200 ml of hexane. The aromatic fraction (f ) was then eluted with 

 200 ml of a solution of hexane and methylene chloride (70/30 V/V) . The 

 methanolic fraction (f ) was then eluted with 150 ml of methanol. Each 

 fraction was concentrated to 3-4 ml by flash evaporation and further 



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