Knoppers¹, Bastiaan, Weber F.L. Souza¹, Tim Jennerjahn² and Eduardo Marone³

¹Departamento de Geoquímica, Universidade Federal Fluminense, 24020-007 Niterói, Brazil, Tel./Fax: +55-21-27174189, E-mail: geoknop@qeoq.uff.br, ²Zentrum für Marine Tropenökologie, Universität Bremen, 28359 Bremen, Germany and ³Centro de Estudos do Mar, Universidade Federal do Paraná, Pontal do Sul, PR, Brazil.

The ocean margin of Brazil, Southwest Atlantic: origin, transport and fate of biogenic matter

This study compiles information on the origin, transport mechanisms and fate of biogenic matter along the East, Southeast and South domains of the tropical/subtropical Brazilian ocean margin, set between the São Francisco River delta (Lat. 10^o30´S, Long. 32^oW) to Chuy (Lat. 34^o S, Long. 58^oW ), and attempts to evaluate the recycling and export potential of materials for this sector of the Southwest Atlantic. The ocean margin is governed by the southward meandering Brazil Current (BC), a passive continental shelf and low to moderate continental run-off. The mechanisms which control material transport across the land-ocean continuum harbor distinct regional differences. The East Brazil Shelf is characterized by efficient dilution of land materials by BC, low productivity, eddy formations induced by variations of shelf topography and by relict terrigenous and carbonate sediments. In contrast, the Southeast-South Brazil Shelf is characterized by BC which meanders further offshore and higher productivity, due to the influence of coastal and shelf edge upwelling. The inner shelf harbors a larger fraction of terrigenous sediments. It is hypothesised, that eddy like circulation and Brazil Current meanders are important mechanisms promoting material transport at the inner and outer shelf. Also, rotatory currents, due to the action of tides, could also be important for across shelf flux estimates.