Aliphatic and polycyclic aromatic hydrocarbons and trace elements as indicators of contamination status near oil and gas platforms in the Sergipe–Alagoas Basin (Southwest Atlantic Ocean)

•Studies of sediment contamination status within 100 m distance of oil and gas platforms.•Anthropogenic impacts due to PAHs are restricted to biomass combustion.•PAH recorded in the sediments near the platforms probably come from the burning of the sugarcane fields.•Trace metal and organic markers indicate that the platforms are not affecting the sediment quality.

Oil and gas platforms from Sergipe–Alagoas Basin located in the northeastern region of Brazil do not discharge produced water. However, those platforms can be a potential source of contaminants to the marine environment due to their producing activities. In this study, sediment samples were collected in the vicinity of two offshore oil and gas platforms located in Sergipe–Alagoas Basin (PCM-9 and PGA-1) to evaluate the source and levels of hydrocarbons and trace elements (As, Fe, Al, Ti, Cu, Cd, Zn, Pb, Ni, Mn, Ba, V, Cr and Hg). Also, the potential impact of those platforms on the sediment quality was investigated. Polycyclic aromatic hydrocarbons diagnostic ratios observed in the sediment samples indicated hydrocarbons from pyrogenic source, specifically from biomass combustion. Trace elements As, Cd and Ba recorded concentrations higher than Threshold Effect Levels (TEL) in the sediment nearby the platforms. Also, there was evidence of some samples enriched by barium. Although As, Cd and Ba concentrations were higher than TEL, they most likely corresponded to background levels. The obtained results indicated that activities of the PCM-9 and PGA-1 platforms may not be affecting the quality of nearby sediment.