Showing papers by "José Antônio Baptista Neto published in 2011"

Geochemical behavior of heavy metals in differents environments in Rodrigo de Freitas lagoon - RJ/Brazil

Abstract: The accelerated urbanisation without a planning, brought several environmental problems to Rio de Janeiro coastal zone, especially in areas such as Rodrigo de Freitas lagoon, which receives a great amount of untreated sewage every day. To assess the nature, potentially sources and extent of heavy metal pollution in the lagoon, sediments from the surrounding streets, from the entrance of the main canal that drains to the lagoon and from the bottom of the lagoon were collected and analysed by a modified selective extraction procedure in order to study the geochemical partitioning and bioavailability of Zn, Cu, Cr, Ni and Pb in these three compartments. The present study verified an increase in the Cu, Pb and Zn concentrations in the north of the Rodrigo de Freitas lagoon. Despite the different levels of oxidation between the sediments accumulated in the streets and in the bottom of the lagoon, the geochemical partitioning of the heavy metals did not show any pattern of variation for the metals, except for the element Cu. No concentrations were found in the soluble phase of samples collected in the surfacial sediments of the lagoon, suggesting no bioavailability of heavy metals.

Study of heavy metal concentration and partitioning in the Estrela River: implications for the pollution in Guanabara Bay - SE Brazil

Abstract: In this study, the geochemical analysis of ten sediment samples collected along the fluvial system of the Estrela River, which flows into the northern portion of Guanabara Bay, shows the presence of anthropogenic impacts in this area. Concentrations of Fe, Mn, Zn, Cu, Pb, Cr and Ni obtained were slightly higher, when compared with values found in natural environments. The particle size and organic matter content in most of the analyzed stations showed features not conducive to the accumulation of pollutants due to the low organic matter content and the strong presence of sand fraction. There was also the fractionation of heavy metals in sediments and it was found the prominence of residual and reducible phase, besides the significant occurrence of organic fractions in some analyzed stations. These factors, thus, highlight the potential risks of contamination, where the metals associated with the organic phase can become bioavailable in processes of dissolution, provided by physico-chemical changes that can occur in this aquatic environment.

Variação sazonal, espacial e composicional de lixo ao longo das praias da margem oriental da Baía de Guanabara (Rio de Janeiro) no período de 1999-2008

Abstract: Guanabara Bay is one of the largest bays on the Brazilian coastline and has an area of approximately 384 km2 , including it islands, however, has been identi...

Distribuição sedimentar da Lagoa Rodrigo de Freitas através de sísmica de alta resolução

Abstract: The Rodrigo de Freitas Lagoon (Rio de Janeiro State) sediments and bottom characteristics were analyzed using high-resolution (10 kHz) sub-bottom profiles associated with particle size analyses of 44 bottom sediment samples. Four types of echo-characters were identified revealing the strong relation with the particle size distribution and bottom morphology. In areas of acoustic penetration, the basement delineates buried sugar-loaf hills and infilled-valley features. The total sediment thickness can reach as much as 16 meters along the paleovalleys, which are aligned in a NE-SW direction, parallel to the regional basement orientation observed on the coastal massifs. There is a predominance of organic rich muddy sediments, infilling the paleovalleys which are the main sites of shallow gas occurrences within the lagoonal sediments.

Variação sazonal, espacial e composicional de lixo ao longo das praias da margem oriental da Baía de Guanabara (Rio de Janeiro) no

Abstract: Guanabara Bay is one of the largest bays on the Brazilian coastline and has an area of approximately 384 km 2 , including it islands, however, has been identified as one of the main polluted coastal environments on the Brazilian coastline. In the last 100 years the catchment area around Guanabara Bay has been strongly modified by human activities, in particular deforestation and uncontrolled settlement, which increased the amounts of contaminants introduced from sewage effluents, industrial discharge, urban and agricultural runoff, atmospheric fallout, and the combined inputs from the rivers. This study quantifies the distribution and composition of beach debris during surveys of beaches in the eastern margin of Guanabara Bay during the years of 1999-2008, field surveys was carried out using transects, all of the transects with the same measurement (10 X 1 meters), and it were set parallel to the water line and located on top of the high tide mark, in three stations of each beach, the extremities of the beach arc and in the central part of the beach, the surveys was carried out in two distinct seasons of the year, one representing the rainy period (summer) and one in the dry period (winter). Debris was categorized into 13 predetermined types of anthropogenic debris: plastic bag, plastic bottles, glass bottles, metal, paper, fishing material, modified wood, fabrics, footwear, construction material, light bulbs, cans and expanded polystyrene. A total of 21841 items were quantified on the Guanabara Bay beaches during the ten years of surveying, with an annual average of more then 2000 item. Temporal differences in the accumulation of debris were also assessed, a total of 14505 items were quantified in the summer and 7336 items in the winter, reflecting the increase capacity of the rivers in the debris transport during the rainy season (summer). Plastic comprised 70.6% of debris deposited in the Guanabara bay beaches, significantly higher than construction material, which was the second most abundant debris type at 10%, followed by glass (8.1%), expanded polystyrene (7.0%), paper (6.7%), cans (4.8%), modified wood (4.6%), fabrics (3.6%), diverse metals (3.2%), footwear (1.6%), remaining fishing material (1.3%) and light bulbs (1.1%). Comparisons, based on debris counts average across transects and areas, indicated that the Brandoas beach was the most contaminated site, followed by Pedrinhas, Boas Viagem, Luz, Charitas and Sao Francisco. However, 77% of all the catalogued items were counted in the Sao Goncalo Municipality, and the Brandoas beach the most contaminated site, representing 52% of counted items, indicating that this beach was the main site for debris deposition, and it can also be source of debris for the other sites. Differently from others areas of the world where the debris has its origin in activities based in the ocean, such as ships, recreation and fishing. The abundance and distribution of debris through the Guanabara Bay beaches appears to be from local land-based or near shore sources, where the rivers represent the main source of debris, due to the use of the rivers by the municipally inhabitant to discard their garbage. The results gotten in these surveys in relation to the amount and composition of the debris deposited on beaches also reflect the cleanness practice by the municipality. One another factor that has great influence in the composition of the debris, found in beaches, is the buoyancy capacity of the materials, since the heaviest material tends to concentrate and remain closer to the source areas. Anthropogenic debris constitutes a significant threat to the marine environment, represent a hazard not only for the marine animals, but also for human activities, health and tourism.