Full text
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| Author(s): |
Andreia Cristiane Teodoro
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | São Paulo. |
| Institution: | Universidade de São Paulo (USP). Instituto de Geociências (IG/BT) |
| Defense date: | 2006-03-30 |
| Examining board members: |
Wania Duleba;
Setembrino Petri;
Silvia Helena de Mello e Sousa
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| Advisor: | Wania Duleba |
| Abstract | |
The present study analyzed the influence of submarine sewage outfall upon foraminifera assemblages on a regional (macro scale) and local (micro scale), in Guarujá and Santos Bay. Fifty samples were analyzed at the macro scale, twenty six from Guarujá and twenty four from Santos Bay. The samples were collected in winter 1997 and summer 1998. At the micro scale, ten samples were collected close to sewage outfall diffusers in Santos Bay in April 2004. At each station hydrographic and sedimentological data were obtained. Spatial and seasonal variations in the composition of foraminifera assemblages were related to environmental variables. Analysis of the influence of oceanic sewage disposal at the macro scale was inconclusive due to the low density of live foraminifera. Thanatocenosis (taphonomic and morphometric analyses) and sedimentological analyses revealed two morphosedimentary sectors in Guarujá and Santos Bay, one in the western portion of the study area with sandy sediments, low C and N, low density and low richness of foraminifera, and the other, in the east-central portion, with predominance of mud, higher C and N, higher density and richness of foraminifera. C/S ratios permitted detection of anoxic sediments near sewage outfall in Guarujá in the winter, and in Santos Bay in both the winter and summer. At the micro scale, hydrogeochemical and sedimentological data indicated that area close to the diffusers is highly eutrofized, with high contents of C, N, P and S in both the water and the sediment. The low C/S ratios of the sediment indicated highly reducing conditions. At the micro scale the biocenosis composition and distribution indicated that environmental characteristics of Santos Bay directly influence the foraminifera assemblages. The results also suggest that the (pre) treatment of Santos sewage is inefficient, transforming the area of the diffusers into one more major focus of pollution in the bay. (AU) | |