Sewage contamination following an accidental spillage in the Ria Formosa, Portugal

Following an accidental spillage of sewage to the Ria Formosa in September, 1994, sediment samples were collected and analysed for sterols and fatty alcohols. Coprostanol concentrations ranged from 0.1 μg g−1 at sites remote from the spill, to 41.8 μg g−1 adjacent to the source. Use of the coprostanol/cholesterol ratio indicates the localized nature of the dispersion, only 2 km from the source. The distribution of fucosterol, ergosterol and fatty alcohols in the sediments are discussed. Principal Component Analysis using selected sterol and fatty alcohol ratios identified two major components describing the extent of sewage contamination and the marine-terrestrial nature of the organic matter.