Pollution source evaluation using petroleum and aliphatic hydrocarbons in surface sediments from two Brazilian estuarine systems

The levels of aliphatic hydrocarbons, including petroleum biomarkers (hopanes and steranes) were measured in surface sediments from two Brazilian estuarine systems affected by sugar cane monoculture and urbanization in order to identify their sources. The total aliphatic hydrocarbon fraction (TAH) concentration in the sediments ranged from 0.39 to 43.83 μg g−1 in the Mundaú–Manguaba estuarine-lagoon system and from 6.40 to 94.27 μg g−1 in the Paraiba do Sul River estuary. The levels of TAH in both study areas are relatively low. The carbon preference index (CPI) calculated for the C23–C34 range indicates that n-alkanes are mainly inherited from cuticular waxes of higher plants. However, the presence of hopanes and steranes indicates petrogenic input. The low values for the hopanes/n-alkanes (Hop/n-alk) and unresolved complex mixture (UCM)/n-alk ratios indicate that the pollution is diluted with natural input.