Baia de Guanabara, Rio de Janeiro, Brazil
llS
The mean dissolved oxygen concentration in Baia de Guanabara
measures 8.4 mg 1- 1 ( 124% saturation) at the surface and 5.1 mg 1- 1 (73%
saturation) in the bottom layer. It is only at locations in the inner bay, near
sources of significant runoff, that the dissolved oxygen concentration in
the bottom layer averages 3-4 mg 1- 1 • Surface waters, in contrast, are frequently supersaturated with respect to dissolved oxygen, even in highly
polluted areas. This reflects a high rate of phytoplankton primary production (Rebello et al. 1988) as indicated by chlorophyll-a values in the central
channel of less than 25 flg 1- 1 , but mean values in the inner bay exceed
130 flg 1- 1 • Although the main part of the bay has relatively low levels of
fecal coliform counts, on average 0.2-10 counts ml- 1 , there is a serious
problem at the sampling sites in the inner parts of the bay where counts on
average exceed 1,000 counts ml- 1 (Kjerfve et al. 1997).
Extensive contamination of fisheries resources by heavy metals, in
particular mercury, cadmium, copper, and lead, is another problem. For
example, heavy metal concentrations reach two to four times the maximum allowed concentration levels for mussels (Rezende and Lacerda
1986). However, bioconcentration of heavy metals in fish is still noncritical because of the low solubility of most heavy metals in the low-oxygen region of the inner bay as a result of sulfide precipitation (Carvalho
et al. 1993). Although many studies of Baia de Guanabara have involved
extensive data collection (e.g., Paranhos and Mayr 1993; Paranhos et al.
1993 ), there remains a great need for continued monitoring of hydrological, oceanographic, and water quality parameters for analysis, synthesis, modeling, and management of the natural resources of Baia de
Guanabara.
References
Alcantara F, Washington DC (1989) An analytical synoptic-dynamic study about the
severe weather event over the city of Rio de Janeiro on Jan 2, 1987. In: Magoon 0,
Neves C (eds) Coastlines of Brazil. American Society of Civil Engineers, New York,
pp 195-204
Almeida MCM (1993) Estudo sobre a pesca do camarao realizada pelas colonias de pesca
da Ilha do governador na Baia de Guanabara, Rio de Janeiro. Universidade do Estado
do Rio de Janeiro, Rio de Janeiro
Amador ES ( 197 4) Praias f6sseis de reconcavo da Baia de Guanabara. An aisAcad Brasil
Cienc 46:253-262
Amador ES (1980a) Assoreamento da Baia de Guanabara- taxas de sedimenta<;:ao. Anais
Acad Brasil Cienc 52(4):723-742
Amador ES (1980b) Unidades sedimentares cen6zoicas do reconcavo da Baia de Guanabara (folhas Petr6polis e Itaborai). Anais Acad Brasil Cienc 52( 4):743-761
llS
The mean dissolved oxygen concentration in Baia de Guanabara
measures 8.4 mg 1- 1 ( 124% saturation) at the surface and 5.1 mg 1- 1 (73%
saturation) in the bottom layer. It is only at locations in the inner bay, near
sources of significant runoff, that the dissolved oxygen concentration in
the bottom layer averages 3-4 mg 1- 1 • Surface waters, in contrast, are frequently supersaturated with respect to dissolved oxygen, even in highly
polluted areas. This reflects a high rate of phytoplankton primary production (Rebello et al. 1988) as indicated by chlorophyll-a values in the central
channel of less than 25 flg 1- 1 , but mean values in the inner bay exceed
130 flg 1- 1 • Although the main part of the bay has relatively low levels of
fecal coliform counts, on average 0.2-10 counts ml- 1 , there is a serious
problem at the sampling sites in the inner parts of the bay where counts on
average exceed 1,000 counts ml- 1 (Kjerfve et al. 1997).
Extensive contamination of fisheries resources by heavy metals, in
particular mercury, cadmium, copper, and lead, is another problem. For
example, heavy metal concentrations reach two to four times the maximum allowed concentration levels for mussels (Rezende and Lacerda
1986). However, bioconcentration of heavy metals in fish is still noncritical because of the low solubility of most heavy metals in the low-oxygen region of the inner bay as a result of sulfide precipitation (Carvalho
et al. 1993). Although many studies of Baia de Guanabara have involved
extensive data collection (e.g., Paranhos and Mayr 1993; Paranhos et al.
1993 ), there remains a great need for continued monitoring of hydrological, oceanographic, and water quality parameters for analysis, synthesis, modeling, and management of the natural resources of Baia de
Guanabara.
References
Alcantara F, Washington DC (1989) An analytical synoptic-dynamic study about the
severe weather event over the city of Rio de Janeiro on Jan 2, 1987. In: Magoon 0,
Neves C (eds) Coastlines of Brazil. American Society of Civil Engineers, New York,
pp 195-204
Almeida MCM (1993) Estudo sobre a pesca do camarao realizada pelas colonias de pesca
da Ilha do governador na Baia de Guanabara, Rio de Janeiro. Universidade do Estado
do Rio de Janeiro, Rio de Janeiro
Amador ES ( 197 4) Praias f6sseis de reconcavo da Baia de Guanabara. An aisAcad Brasil
Cienc 46:253-262
Amador ES (1980a) Assoreamento da Baia de Guanabara- taxas de sedimenta<;:ao. Anais
Acad Brasil Cienc 52(4):723-742
Amador ES (1980b) Unidades sedimentares cen6zoicas do reconcavo da Baia de Guanabara (folhas Petr6polis e Itaborai). Anais Acad Brasil Cienc 52( 4):743-761