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Aliphatic (AHs) and polycyclic aromatic hydrocarbons (PAHs) concentrations were measured in marine surface sediments around the Brazilian station in Admiralty Bay, during the summers of 1997/98 and 1999/2000 using GC-FID and GC-MS. Total aliphatic hydrocarbons ranged from 0.15 to 13.28 µg.g -1 (dry weight) while n-alkanes varied between 0.10 and 9.63 µg.g -1. The highest concentrations were obtained at the sewage outfall, with decreasing levels away from the outfall. The distribution of n-alkanes showed significant quantities of long chain n-alkanes (n-C 22 to n-C 34 ) at sites near the Brazilian station that may be attributed to the station activities. A short chain n-alkanes sequence (n-C 12 to n-C 21 ) associated with diesel fuel arctic (DFA) was present in all the samples. Total PAHs varied from 9.45 to 270.5 ng.g -1. The higher PAHs level and the presence of an unresolved complex mixture only in sediment from the sewage outfall is an indication of oil contamination at this location. A slight increase in PAHs near the Brazilian station since 1993 may be attributed to an increase in the number of staff over recent years. In general, the concentration of AHs and PAHs was similar to that found in other Antarctic areas.

Admiralty Bay on the King George Island hosts the Brazilian, Polish and Peruvian research stations as well as the American and Ecuadorian field stations. Human activities in this region require the use of fossil fuels as an energy source, thereby placing the region at risk of hydrocarbon contamination. Hydrocarbon monitoring was conducted on water and sediment samples from the bay over 15 years. Fluorescence spectroscopy was used for the analysis of total polycyclic aromatic hydrocarbons (PAHs) in seawater samples and gas chromatography with flame ionization and/or mass spectrometric detection was used to analyse individual n-alkanes and PAHs in sediment samples. The results revealed that most sites contaminated by these compounds are around the Brazilian and Polish research stations due to the intense human activities, mainly during the summer. Moreover, the sediments revealed the presence of hydrocarbons from different sources, suggesting a mixture of the direct input of oil or derivatives and derived from hydrocarbon combustion. A decrease in PAH concentrations occurred following improvement of the sewage treatment facilities at the Brazilian research station, indicating that the contribution from human waste may be significant.

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Selected sterols (coprostanol, epicoprostanol, cholesterol, cholestanol), stanone (5ß-coprostanone) and linear alkylbenzenes (LABs) were measured in the surface sediments near Ferraz station sewage outfalls, in Admiralty Bay, King George Island, South Shetland Islands. during the summer of 1997/98 using GC-FID and GC-MS. Total sterol concentrations varied between 0.21 and 10.4 µg g -1 dry sediment. Cholesterol was the major sterol at all sites, except at the sewage outfall, where coprostanol predominated. The concentration of coprostanol varied between 0.03 and 6.14 µg g -1 dry sediment, but the majority of the samples contained levels below 0.13 µg g -1 dry sediment. The parameters coprostanol+epicoprostanol in total sterols, coprostanol/epicoprostanol ratio versus % of cholesterol in total sterols and versus 5ß-coprostanone concentration were used to identify the sewage impacted locations in the study area. Only sites extending to 50m from the sewage outfall exhibited a sterol signal indicating sewage input. Total LABs varied from < 0.60 to 11.8 ng.g -1 dry sediment with the maximum level at the sewage outfall. Faeces from different species of seals all contained large amounts of cholesterol and some 5ß-coprostanone. Relatively low levels of coprostanol and high levels of cholesterol observed in distant sites could be attributed to natural sources such as marine mammals.