Sterols and linear alkylbenzenes in marine sediments from Admiralty Bay, King George Island, South Shetland Islands

Abstract

Selected sterols (coprostanol, epicoprostanol, cholesterol, cholestanol), stanone (5ßcoprostanone) 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 5ßcoprostanone. Relatively low levels of coprostanol and high levels of cholesterol observed in distant sites could be attributed to natural sources such as marine mammals.