--> Abstract: The Distribution of Hydrocarbons and other Components in Waters and Sediments from the Guanabara Bay, Rio de Janeiro, by G. K. Carvalhaes and P. W. Brooks; #90933 (1998).

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Abstract: The Distribution of Hydrocarbons and other Components in Waters and Sediments from the Guanabara Bay, Rio de Janeiro

Carvalhaes, Gabriela Kernick and Paul William Brooks - Petrobras/Cenpes

The Guanabara Bay, Rio de Janeiro, has over 50 miles of shoreline and at least 12 major surface water inlets that introduce industrial and/or domestic waste. As part of a larger study to characterise the environmental condition of the waters and sediments within the Bay it is thought that a comprehensive evaluation of the condition of waters and sediments in the Cunha Channel and its many inputs would provide several benefits. As can be seen in figure 1, the Cunha Channel is an important part of the whole Bay area. Situated close to Ilha do Governador, it is a focal point, where different inputs like two research centers, a harbour, a hospital and the whole university center contribute to the environmental condition of Guanabara Bay.

The Guanabara Bay is known to receive inputs of contamination from a large number of sources, including industrial and domestic wastes, runoff from storm drains, drainage channels from within the city of Rio de Janeiro and from the constant movement of shipping. Little is known concerning the distribution of hydrocarbons and other components in the waters and sediments within the Bay.

This paper describes preliminary studies on the distribution of these components in this channel (Canal do Cunha) and has served to initiate a much larger study program aimed at the description of contamination levels within the whole Bay area together with possible remediation strategies. Thus, water and sediment samples from this Channel were analysed by High-Resolution GC/MS for different classes of contaminants.

Hydrocarbons in both samples can be divided into two sources, anthropogenic and autogenic. The types of natural hydrocarbons found (at parts per million levels ) include phytadiene isomers, from the natural degradation of phytol (side chain alcohol of chlorophyll) and heptadecene, a dominant hydrocarbon constituent of certain species of algae and higher molecular weight n-alkanes (C25-C35). The presence of fossil fuel hydrocarbons is indicated by the presence of a broad unresolved "hump" of branched and cyclic alkanes containing components whose structures are not known in present day natural sources but can only have been derived from crude oils or refined products.

The samples were also analysed for the presence of other components, including Polynuclear Aromatic hydrocarbons, organochlorine pesticides, polychlorinated biphenyls (PCB's) and Polychlorinated Dibenzodioxins and dibenzofurans (PCDD's and PCDF's).

Components were found from these groups of compounds at parts per billion and parts per trillion levels. The distribution of these components in the channel and their significance will also be discussed.

AAPG Search and Discovery Article #90933©1998 ABGP/AAPG International Conference and Exhibition, Rio de Janeiro, Brazil