Regresar

Presence and sources of aromatic polycyclic hydrocarbons in superficial sediments at the cariaco gulf sac, Venezuela

Abstract:

The presence, concentration and sources of 14 selected polycyclic aromatic hydrocarbons (PAHs), among those listed as priority pollutants by the US Environmental Protection Agency were investigated in surface sediment samples from the Gulf of Cariaco, Sucre state, Venezuela, in June 2007 and April 2008. The results show the presence of three low molar mass PAHs (LPAHs): naphthalene, phenanthrene and anthracene (2 and 3 rings) and three high molar mass PAHs (HPAHs): fluoranthene, pyrene and benzo(b)fluoranthene (4 and 5 rings). The values of HPAHs/ LPAHs ratios were between 0.07 and 0.50 in both samplings, with predominance of fluoranthene (June 2007: 16.42-76.62ng·g-1; April 2008: 21.49-71.34ng·g-1). The results indicated that total concentrations of PAHs were highest in April 2008 (32.93-104.50ng·g-1) and June 2007 (21.21-78.74ng·g-1). None exceeded the quality criteria established by Washington State Sediment Management Standards and the National Oceanic and Atmospheric Administration. The concentration variances showed no significant differences in both samplings, while the means were statistically different (p<0.05). Their total concentrations were not associated with granulometric size distribution, and there was no significant affinity with organic matter. The values of fluoranthene/pyrene ratios (16-44) show pyrogenic origins of the PAHs. Theses results were corroborated by the values of phenanthrene/anthracene ratios (0.7-28), which indicate, in some cases, mixed origins (pyrogenic+petrogenic). Additionally, the naphthalene/phenanthrene ratios were >1 in certain localities, indicating discharge of waste motor oil and refined oil products.