Caracterização da matéria orgânica sedimentar na Baía de Guanabara através de marcadores moleculares

Abstract

The present work aimed at investigating the effects of growing eutrophic conditions and soil occupation on the carbon storage in Guanabara Bay. Sterols in dated sediment cores were used to characterize the sources of organic matter to the bay. Dinosterol was the most abundant amongst the measured sterols reaching 64.7 % of the total. Coprostanol, a fecal sterol, was present in concentrations as high as 40 µg g-1 in areas of intensive sewage discharge. These results are in agreement with the known elevated primary production in the bay and with the severe eutrophic conditions. The calculated carbon fluxes using the organic carbon content and the sedimention rates range between 50 g C m-2 year-1 and 500g C m-2 year-1 during the last 100 years.