Metals in seston from Cabo Frio Bay, a region under the influence of upwelling in SE-Brazil

Abstract

This study, performed during 2003-2005 and 2008-2009, investigated metals (Al, Fe, Ba, Zn, Mn, Cr, Cu, Ni, Cd) content in seston at Cabo Frio Bay, SE-Brazil. This study may serve as a baseline of seston metal distribution to guide biogeochemical and ecological models. The seston fractions (> 20 µm, > 64 µm, > 100 µm, and > 150 µm) were sampled in sub-surface horizontal hauls. Metals were determined by ICP-MS. The metals range: Al (62.5-56,867.6 µg g^-1), Fe (23.5-25,384.0 µg g^-1), Mn (2.7-336.8 µg g^-1), Ba (< 0.005-356.3 µg g^-1), Zn (0.5-94.2 µg g^-1), Cr (0.7-35.5 µg g^-1), Cu (4.3-41.7 µg g^-1), Ni (< 0.005-19.1 µg g^-1) and Cd (< 0.0004-2.4 µg g^-1). Aluminium, Fe, Mn, Ba, and Zn showed significant differences (p < 0.05) between the seston fraction. The results obtained in this study suggest that the elements (Fe, Mn, Ba) in the seston were strongly influenced by the abiogenic source. In contrast, Zn, Cd, Cu, Cr, and Ni can be biogenic/anthropogenic sources. The significant positive linear correlation of Zn:P, Cd:P, and Cu:P can indicate an intracellular concentration higher than the external adsorption in the plankton community.

Keywords: Arraial do Cabo; Coastal water; Plankton; South Atlantic Central Water (SACW).