Hydrocarbons in sediments along a tropical estuary-shelf transition area: Sources and spatial distribution

Estuaries generally act as sediment traps and may retain a range of contaminants associated to this matrix. Aliphatic hydrocarbons (AHs) were investigated in Capibaribe Estuarine System and adjacent shelf, Northeast of Brazil, to evaluate the contamination and to better understand its functionality related to the coast. Fourteen sediment samples were analyzed, using gas chromatography with flame ionization detection. Total AHs concentrations ranged from 7.5 to 190.3 μg g− 1 and n-alkanes ranged from below detection limit (< DL) to 9.47 μg g− 1. The highest concentrations were in the upper portion of the estuary, which receives domestic and industrial effluents. The observed UCM and other geochemical markers, indicated contamination by petroleum hydrocarbons. The concentration decrease (about 90%) towards the adjacent shelf suggested an estuarine high retention capacity but dilution and degradation processes cannot be neglected. Similar AHs characteristics reported in sediments from the adjacent shelf suggested that this system may also export contaminants.