Impact of the Prestige oil spill on marsh soils: Relationship between heavy metal, sulfide and total petroleum hydrocarbon contents at the Villarrube and Lires marshes (Galicia, Spain)

Abstract

 The objectives of this study were to determine the effect of the Prestige oil spill on the total petroleum hydrocarbons and heavy metal contents of soils in two marshes (Lires and Villarrube, Galicia, Spain) and the relationship between their oxidationreduction potential and the solubility of heavy metals with sulfide and sulfate contents. Soil samples were taken from polluted and unpolluted areas and their petroleum hydrocarbon contents, heavy metal contents and other chemical characteristics were measured. The soils affected by the oil spill show remarkable contents of Cr, Cu, Ni, Pb and V. The Lires marsh soils are more affected by fuel oil than Villarrube marsh. The effects of the contaminating agents on the soils reach distances of up to 500 m from the coastline. In the first 400 m, there are important spatial variations because the fuel oil penetrated into the soils through tidal action and not directly. The Cr, Cu, Ni, Pb and V contents of polluted soils were between 50 and 200 times higher than those of their unpolluted counterparts and the background concentrations in Galician coastal sediments. In the case of Cr, Cu, Ni, Pb and V, their originthrough the fuel oil was corroborated by the high correlation (r > 0.90) between the concentrations of these metals and the total petroleum hydrocarbon content of the polluted soils, which shows the combined addition of these metals through the fuel oil.