Polycyclic aromatic hydrocarbons in sediments of the Amazon River Estuary (Amapa, Northern Brazil): Distribution, sources and potential ecological risk

The distribution, sources and potential ecological risk of priority polycyclic aromatic hydrocarbons (PAHs) in sediment from the Amazon River Estuary (Macapa and Santana, Amapa, Northern Brazil) were investigated. The total PAHs concentration (Sigma PAH) ranged from 22.2 to 158.9 ng g(-1) dw (mean value 49.4 ng g(-1) dw). PAHs levels in the study area were relatively low than those in nearby areas and other coastal zones worldwide, and could be considered as baseline for PAHs in Amazonic sediments. PAHs ratios and the statistical analysis showed that fossil fuel and biomass combustions, primarily from local sources, were the dominant PAHs origins. The potential ecological risk was assessed on the basis of the sediment quality guidelines, and it was found that PAHs in the sediments of the Amazon River Estuary do not cause adverse effects on living organisms; however, the abundance of naphthalene and the presence of dibenzo[a,h]anthracene and benzo[a]pyrene deserve more attention.