Lipídios em sedimentos superficiais da plataforma continental do Espírito Santo, Brasil

Abstract

Biomarkers of lipid, fatty acids and sterols groups, C13 isotopes and C/N molar ratio were analyzed in 48 sample points of superficial sediments (0 - 2 cm) on the continental shelf adjacent to the Doce River (Linhares-ES, summer 2010 and winter 2011), and the Espírito Santo Basin and the north of the Campos Basin (winter of 2012 and summer of 2013), belonging to the Brazilian Southeast Continental Margin, where there is riverine and anthropic influence, and different oceanographic characteristics. The main objective of this work was to avaliate the sources of organic matter (MO) in this marine environment where there is a transition from the coastal zone to the offshore zone. Saturated fatty acids (SFA), such as C16:0, and monounsaturated fatty acids (MUFA), such as C16:1 and C18:1, and, sterols (from 27 to 29C) such as cholesterol (27? 5 ) and stigmastanol (29? 22) were identified as the most abundant. The results of carbon isotopes varied from -22.1‰ to -25.4‰ for MRD (Doce River mouth) and, from -20.3‰ to -23.6‰ for MPL (Continental Shelf). The C/N molar ratio had a maximum value of 10.86. Fatty acids, 27C sterols, isotopic ratio and C/N molar ratio indicated autochthonous origin, from the primary productivity due to the availability of nutrients in the photic zone. Sterols of terrigenous origin were present in low concentrations, showing little contribution from this source in the analyzed area. There is an influence of the Doce River in the platform mainly in the points closer to the river mouth and to the south. The quality of autochthonous MO seems to be influenced by the phytoplankton community that responds to the availability of nutrients in the region.