Distribution and sources of phytosterols in coastal and river sediments of south-central Chile

Phytosterols are potential endocrine-disrupting compounds. Quantification of phytosterols was carried out in sediments from four coastal zones and two rivers in south-central Chile. Sterol concentrations were determined by capillary gas chromatography-mass spectrometry and the sources of sedimentary organic matter were determined using sterol ratios and lipid biomarkers. Total sterol concentrations (0.03 to 10.4 mu g g(-1)) were within the range reported for other marine ecosystems and the beta-sitosterol concentration (0.01 to 2.01 mu g g(-1)) was lower than previously reported for the upwelling system off Peru. Some coastal stations adjacent to the rivers had beta-sitosterol of terrestrial origin. High concentrations of beta-sitosterol were also found in sediments from more oceanic stations, supporting the notion that this sterol can also be produced by phytoplankton. No differences in the sterol concentration between the coastal zones were found. However, significant differences were found between almost all coastal zones and both rivers, and between rivers. At the station level and using different biomarkers of the source of organic matter, some areas were found to have a clear terrestrial influence; whereby it is assumed that the source of the phytosterols (especially beta-sitosterol) would be vascular plants. The BioBio River and its mouth have a wide variety of sterols and lipids and high levels of cholesterol and epicholestanol, which is possibly related to the presence of domestic effluents derived from large cities. No clear spatial pattern emerge between the location of pulp mill industries and beta-sitosterol sediment concentration, with the exception of one station located in the Gulf of Arauco.