Rodrigo De Freitas Lagoon Research Articles

Polycyclic aromatic hydrocarbons in sediments from Rodrigo de Freitas Lagoon in the urban area of Rio de Janeiro, Brasil

Regular (non-alkylated) polycyclic aromatic hydrocarbons (PAHs) and their alkylated homologues were determined in sediments from Rodrigo de Freitas Lagoon using gas chromatography with mass selective detector (GC-MSD). Concentrations varying from 405 to 11734 ng·g−1 were found for total PAHs (regular and alkylated homologues). The study showed a pyrogenic and petrogenic contribution, probably due to the incomplete burning of fossil fuels as a result of the intense traffic of boats and motor vehicles added to the anthropogenic activity of several gas stations present in the region of Rodrigo de Freitas Lagoon. According to the National Oceanic and Atmospheric Administration (NOAA) Sediment Quality Guide, PAHs concentration should not exceed 4000 ng·g−1 (Long et al., 1995) The obtained data present values above the NOAA limit for some sampling points indicating chronic contamination of those sites probably due to anthropogenic activities related to petroleum and its derivatives.

Heterotrophic bacteria abundances in Rodrigo de Freitas Lagoon (Rio de Janeiro, Brazil)

The Rodrigo de Freitas Lagoon (RJ, Brazil) is an important coastal ecosystem that has been submitted to an accelerated degradation process. The aim of this work was to determine the abundance and the spatial distribution of total heterotrophic (by flow cytometry) and cultivated bacteria ("pour plate" method on R2A agar). Another objective was to evaluate the lagoon's influence on water quality of Ipanema and Leblon beaches. Physical and chemical data were acquired too. Sub-superficial water samples were taken monthly, from December 1999 to October 2000. On lagoon, the cultivated bacteria abundance varied from 6.9x10(5) to 5.0x10(7) CFU.100 mL-1. On Ipanema and Leblon beaches, this parameter yielded 1.4x10(5) and 2.8x10(6) CFU.100 mL-1, respectively. Total bacterial abundance varied from 2.9x10(7) to 3.2x10(7) cells.mL-1 on lagoon. On Ipanema and Leblon, this parameter yielded 8.7x10(6) and 1.1x10(7) cells.mL-1, respectively. Two sub-groups were determined with dominance of HNA cells. Samples were added latter to better understand the bacteria present on these environments. Bacterial abundance were analyzed only by flow cytometry and the results varied from 8.3x10(6) to 2.5x10(7) cells.mL-1 on lagoon. On the beach, this parameter yielded 6.9x10(6) cells. mL-1. Two bacterial sub-groups were also observed, with dominance of HNA on lagoon and LNA on the beach. The results showed that the Rodrigo de Freitas Lagoon is an eutrophic ecosystem where the bacterial populations and the physical and chemical parameters do not differ spatially. The data also confirmed that the outflow of the lagoon's polluted waters affect the sanitary conditions of Ipanema and Leblon beaches.

Use of molecular approach to verify the influence of a eutrophic lagoon in the nearby ocean's bacterioplankton communities

Rodrigo de Freitas lagoon is an eutrophic aquatic environment. The waters from the lagoon are released to the sea at Ipanema and Leblon beaches, through Jardim de Alah channel. In this work, the influence of these waters on the bacterial communities of these beaches was investigated. Eleven sampling stations were set between the lagoon and the beaches, and the samples were analyzed by molecular and microbiological parameters. PCR-DGGE of the DNA extracted from the samples was performed using rpoB primers. Preliminary results indicate that all used approaches could reveal the influence of the lagoon on the beaches bacterial communities.

Aspectos reprodutivos de Poecilia vivipara (Bloch & Schneider) (Poeciliidae) da Lagoa Rodrigo de Freitas, Rio de Janeiro, Brasil

Poecilia vivipara (Bloch & Schneider. 1801) is a species that lives in the Rodrigo de Freitas lagoon, a coastal lagoon in the city of Rio de Janeiro. The objective of this study was to increase the knowledge about reproductive aspects of P. vivipara population including: the female size when it begins reproduction, the number of offsprings per gestation, embrionary development stages and the number of pregnant females. The results show that P. vivipara reproduces throughout the whole year with its first maturation occurring at 29 mm. The proportion found of females to males was 3:1. Embryos showed four developmental stages until birth with sexual differentiation occurring after 15mm.

Monitoring and spatial distribution of heterotrophic bacteria and fecal coliforms in the Rodrigo de Freitas Lagoon, Rio de Janeiro, Brazil

The distribution of heterothrophic bacteria and fecal coliforms was monitored at four sampling stations located near the shore of the Rodrigo de Freitas Lagoon, in the city of Rio de Janeiro, Brazil. Water samples were collected, monthly from October 1994 through September 1998. The highest heterothrophic count (6.5x10 7 CFU/100mL) was recorded at stations 2 and 4 during August 1998 and the lowest (10 ³ CFU/100 mL) at station 3 during February 1995. With respect to fecal coliforms, the highest and lowest counts were 1.6x10 5 coliforms/100mL at station 3 during March 1997 and <1 coliform/100mL at all the stations during February 1995 and September 1997 as well as station 3 during February 1998. The data indicated a percentage increase of the microorganisms surveyed over time at all the sampling stations studied.

Ten Years of Operation of Rio De Janeiro'S Ipanema Submarine Outfall

Monitoring and surveys of the Ipanema Submarine Outfall of the city of Rio de Janeiro have been practiced during the 10 years of the outfall operation. The outfall is a 2.4m diameter prestressed concrete pipeline, 4.3 km long, extending 3.3 km seaward to a depth of 27m. It discharges presently 6 m3/s average raw sewage flow, through a 450m long diffuser. A planned survey program was established in order to verify pipe conditions through periodical deep sea inspection, monitored by radio and video recording; this paper discusses the preventive and corrective maintenance of the outfall, especially the failures that occurred in 5 accidents. It discusses also the water quality monitoring program established one year before the outfall began its operation in 1975. A program had been prepared which established beneficial water uses, water quality standards required for protection of the uses,and a monitoring system which provides the input data for verifying compliance with the standards. Pre-discharge studies were conducted for one year prior to operation, to provide background data on the various parameters, and over 70 000 analyses were made during the 10 years of the outfall operation. This paper evaluates the results of grease, coliforms, and hydrobiological indicators, as the most representative parameters of water quality in the sea. It shows that a marked improvement has occurred in the water quality. It also shows that the beaches receive a great amount of pollution through the canals of Visconde de Albuquerque Avenue and Jardim de Alá (Rodrigo de Freitas Lagoon), due to sewage overflows from the sewer network and the storm-water networks. The importance of giving special attention to the sewer network in systems involving submarine outfalls is stressed.