Background values and assessment of fecal steroids discharged into two inlets (mackelar and ezcurra) in Admiralty Bay, King George ­Island, Antarctica

Abstract

Steroids are efficient geochemical markers of natural and anthropogenic environmental events, because they present stability and resistance to the degradation process, keeping a record of their signature origin, allowing interpretations about the organic matter sources. The Antarctic region is considered one of the best preserved environments in the world; however human activities have resulted in changes in this pristine location. Sampling was collected during the 2006/07 austral summer at three points: Refuge II (REF) (Mackelar Inlet), Thomas Point (PTH) and Barrel Point (BAR) (Ezcurra Inlet). After Soxhlet extraction, clean up using adsorption column and derivatization, steroids concentrations were determined by gas chromatography with flame ionization detector (GC-FID). Concentrations of fecal sterols (coprostanol and epicoprostanol) in all locations studied were <0.10 μg.g–1, suggesting natural contributions of these compounds. This statement is corroborated by values found for the coprostanol/epicoprostanol ratio for all cores (<2.50). Based on these results, background values were established for the analyzed compounds in the two studied inlets. The values for REF, PTH and BAR were, respectively, (0.06 ± 0.02), (0.04 ± 0.03) and (0.03 ± 0.01) for coprostanol + epicoprostanol.