PAHs in Sediments from Amazon Mangrove and Oyster Farming Areas: Sources, Ecological Risks and Potential Toxicity

Abstract Sixteen polycyclic aromatic hydrocarbons (PAHs) were examined in mangrove sediments from three Amazonian municipalities, known for port operation, fish market (Curuçá), oyster production (Augusto Corrêa) and tourism (Salinópolis). ∑PAH concentrations (4.55–1303 ng g −1 dry sediment; mean: 246 ± 644) indicated low to moderate contamination, in the order: Curuçá ≫ Salinópolis > Augusto Corrêa, with the maxima near natural oyster banks (Curuçá) and lowest in the oyster farming area (Augusto Corrêa). Contamination sources and apportionment were investigated using diagnostic ratios and multivariate analysis, estimating 30% from fossil fuel combustion, 59% from biomass/coal burning and 11% from petrogenic and natural sources. Carcinogenic benzo[a]pyrene-equivalent toxicity was below threshold guidelines, but dibenzo[a,h]anthracene exceeded ecological risks and integrative indices in Curuçá and Salinópolis samples. A potential PAH transfer risk from suspended sediments to oyster may occur. Our results contribute to the local socioeconomic basis with environmental quality dataset and baseline PAHs in mangrove areas.