Persistent toxic substances in surface water of Todos Os Santos Bay, Brazil

Abstract

Persistent toxic substances (PTSs) such as polycyclic aromatic hydrocarbons (PAHs) are of great concern due to their persistence, bioaccumulation and toxic effects. In this work, 14 PAHs included in the US Environmental Protection Agency’s (EPA) priority pollutant list were analysed using gas chromatography–mass spectrometry (GC–MS). Surface water sampling was undertaken in Todos os Santos Bay, northern Brazil. Total PAH concentrations varied from 0.0029 to 0.1079 ng/L in surface waters (main rivers, tributaries, etc.) with mean value of 0.0344 ng/L. Such concentrations can be taken as background values for the studied region and show that PAHs are within or lower than levels reported in certain other areas. The PAH profiles were dominated by high molecular weight PAHs (four- and five-ring components) in surface water samples. It indicated that PAHs in surface water have its origin from oil or sewage contamination (petrogenic input). The collected data, based on indices among phenanthrene versus anthracene, showed that petrogenic input was predominant at almost all the stations investigated. Principal component analysis (PCA), using a correlation matrix, revealed the latent relationships among all the surface water stations investigated and confirmed our analytical results.