BIOGEOQUÍMICA DE METAIS NA CADEIA TRÓFICA PELÁGICA DA ÁREA DE RESSURGÊNCIA DE CABO FRIO SUDESTE DO BRASIL

Abstract

The coastal regions of the world are subject to the phenomenon of upwelling constituting areas of high biological productivity. Even though upwelling areas represent a small percentage of the total surface of the oceans, they are the main fishing grounds in the world. Along the Brazilian coast the area that is the principal site subject to this phenomenon is the coastal region of Cabo Frio-RJ. In order to investigate the biogeochemistry of metals in this unique environment on the Brazilian coast, plankton samples were collected (fractions: 20, 64, 100 and 150μm), fish (Sargocentron bullisi, Holocentrus adscensionis, Trichiurus lepturus and Merluccius hubbsi) and squid (Loligo plei). These samples, after dry and digested in acidic mixtures were analyzed with an ICP-MS for metals content (Aluminium, Iron, Zinc, Barium, Manganese, Copper, Chromium, Nickel, Vanadium and Cadmium). Vanadium speciation in biomolecules in plankton was used multidimensional techniques coupling HPLC-ICP-MS, UV-VIS detector, the identification of the molecular weight of biomolecules associated with the vanadium MALDI-TOF. The results of four years of plankton sampling totalized 25 samples showed predominance of higher average values of Al, Fe, Cr, Ni and V in winter, and Ba in summer, while the elements Zn, Mn and Cu did not exhibit seasonal distribution pattern defined. Metals: Al, Fe, Mn, Ni and Cr concentrations were distributed in decreasing mesh plankton net (64> 20> 150 mM), whereas for Zn and Cd (150> 64> 20 mM), Ba and V ( 64> 150> 20 ìm). The elemental ratios C: N ranged from 4.3 to 13.8, whereas the period with higher values where in the spring and summer, since the N: P ratio ranged from 13.2 to 54.1 with higher values in autumn and winter. The concentrations of Zn, Cu and Cd in the mantle of the squid Loligo plei were higher than found in any published work for cephalopods, while the values of Fe and Ni are the lowest ever recorded for cephalopods. In the muscle of fish species (Holocentrus adscensionis, Sargocentron bullisi, Merluccius hubbsi, and Trichiurus lepturus) concentrations Mn, Zn, Fe, Cd and Cu are among the largest given for marine fish, while the elements Cr and Ni were found in the same concentration range of other species. Al was found at intermediate concentrations compared to those found in species of the Pacific Ocean and the Mediterranean Sea. The results of the speciation of vanadium 8 associated with biomolecules in plankton indicate a protein with isoelectric point above 8, very similar to that found in vanabinas. Moreover, there was a sort of preliminary analysis in approximately 8KDa in MALDI-TOF, indicating that the biomolecule associated with Vanadium can be a kind of vanabina.