ZANARDI-LAMARDO, Eliete; BICEGO, Marcia Caruso and WEBER, Rolf Roland. The fate of an oil spill in São Sebastião channel: a case study. Braz. j. oceanogr. [online]. 2013, vol.61, n.2, pp. 93-104. ISSN 1982-436X. http://dx.doi.org/10.1590/S1679-87592013000200002.
Hydrocarbons as marine environmental assessment tool
Researchers at the Federal University of Pernambuco and São Paulo University investigated the levels of oil contamination in sediments of the São Sebastião Channel, São Paulo, and verified that the North is the first area to be affected by oil spills.
The oil is usually pointed out as the main contaminant of coastal areas, especially because its introduction may be either chronic or accidental. However, hydrocarbons are also important tool to trace the path and identify the final destination of oil after a spill, as has been reported in the scientific literature. The novelty of the present work lies in the fact that it was possible now to relate this knowledge to the hydrodynamics of the São Sebastião Channel and determine which area is most affected and what region is the first to recover from contamination present in the sediments.
The discovery was motivated by an accident occurred in the local oil pipeline. The rupture of the pipeline in May 1994, introduced 2,700 tons of crude oil in the São Sebastião Channel, contaminating the area. On that occasion was being carried out there a monitoring program for determination of the hydrocarbon level present in sediments, and the data obtained were compared with those resulting from samples collected soon after the accident. This procedure was fortuitous, because it allowed detecting not only the extent of oil contamination and the worst-hit places, but also elapsed time for the reduction of pollutants in sediments. Soon after the accident the most contaminated by n-alkanes were the stations situated north, the higher hydrodynamic area, and seven months later they showed signs of recovery. On the other hand, southern stations located in depositional sites remained contaminated after this period.
The work was published in the Journal of Oceanography, volume 61 (2), in June 2013, and according to one of the authors "it is the only existing study conducted with aliphatic hydrocarbons to the area of the São Sebastião Channel and shows the fate of an oil spill and defines the areas most affected within the channel, based on the variation of the petroleum hydrocarbon concentrations in sediments before, right after and some months after the spillage".