Effect of seasonal population fluctuation in the temporal and spatial distribution of polycyclic aromatic hydrocarbons in a subtropical estuary

• PAH concentrations on surficial suspended particulate matter were determined.
• PAH temporal distribution appears to be affected by population fluctuations.
• The PAH spatial distribution and the water physical parameters were related.
• PAHs were primarily related to petrogenic sources, with some pyrolytic contribution.
• The distribution of alkyl PAHs with different molar weights was discussed.

Guaratuba Bay is a subtropical estuary located in an Environmental Protection Area and between two touristic cities, which are strongly influenced by seasonal increased population during austral summer. To evaluate the recent introduction of polycyclic aromatic hydrocarbons (PAHs) in Guaratuba Bay, samples of surficial suspended particulate matter (SPM) were collected at 22 sites and at three different times. PAHs were determined by gas chromatography coupled to a mass spectrometer (GC/MS). The studied area was sectored according to hydrological parameters. The highest PAH concentrations were observed during the Carnival period due to the tourism and population increase. Spatially, the highest concentrations were verified in the mesohaline and euhaline estuarine regions and were related to the environmental characteristics that facilitate material accumulation and the proximity to ship docks, respectively. The diagnostic ratios and the principal component analysis suggest that the main sources of PAHs are petrogenic inputs related to the boat traffic.