Characterization of Granulometric and Chemical Composition of Sediments of Barigui River Samples and their Capacity to Retain Polycyclic Aromatic Hydrocarbons

Abstract

The presence of polylcyclic aromatic hydrocarbons (PAHs) in surface sediments of Barigui River was investigated. PAHs are considered highly toxic and persistent compounds because of their structure. They originate from incomplete combustion of fossil fuels or biomass. The Barigui River crosses the metropolitan region of Curitiba, and some regions are highly polluted and located near the possible sources of pollution. The results showed that concentrations of total PAHs ranged from 44.6 to 880.2 ng g−1, and the highest values were found at the sites previously investigated and identified as critically polluted. At sites located away from the traffic and possible pollution sources, the total PAHs was lower, 44.6 ng g−1. Due to their hydrophobic character, sediments with high silt and clay content retain greater amounts of PAHs. The granulometric composition of the sediments revealed that most of them are composed basically by silt and clay, and those samples showed high concentration of PAHs. The organic carbon content also confirms this observation. The other sites investigated showed a high capacity to adsorb hydrophobic compounds mainly due to the granulometric composition and organic matter that adsorb poorly water soluble compounds. Finally, we found that the main sources of PAHs are petrogenic; however, at some sites, it is hard to confirm this pattern, and possibly, a mixture of the source would be more appropriate.