Distribution of sterols in sediment cores from martel inlet, Admiralty Bay, King George Island, Antarctica

Abstract

In the present study, sterols organic markers were applied to identify the sources of organic matter in Admiralty Bay. For this purpose, sediment samples were extracted using a Soxhlet system, clean up with column chromatography and injected into a gas chromatograph. Measurable levels of all sterols analyzed confirm the multiplicity of sources of sedimentary organic matter. In BTN and STH,the most abundant sterol was the colest-5-en-3β-ol (cholesterol) with 2.24 μg.g–1 and 4.12 μg.g–1, respectively, while in FER, itwas the 24-metil-colest-5-en-3β-ol (campesterol) with 1.83 μg.g–1. The saturated sterols have smaller concentrations in relation to parental unsaturated, which may indicate a low rate of bacterial and hydrogenation processes. A generic profile of the vertical distribution representing all 15 sterols studied was obtained by Principal Component Analysis (PCA). In three cores, the vertical distribution pattern of organic material presented the smallest values in the bottomdepth layers, reflecting the organic matter already immobilized while in the upper layers values showed a gradual increase towards the top, representing the recentdeposition of organic matter.