Estefan Monteiro da Fonseca

Geochronology and heavy metal flux to Guanabara bay, Rio de Janeiro state: a preliminary study

Guanabara Bay, located in Rio de Janeiro state. It is surrounded by the second most important metropolitan area of the country. Over recent decades, land disturbance and urbanization in the surrounding area has significantly increased sediment input to the bay and had a negative effect on its overall environmental. This is especially related to high volumes of untreated sewage and industrial effluents. This study evaluates the history of this human impact through detailed examination of a sediment core taken from the northern portion of Guanabara Bay. A geochronology is established using ²¹⁰Pb dating and related to organic carbon and heavy metal fluxes to the sediments. This gave a calculated net average sedimentation rate for the core of 0.67 cm.year⁻¹. The organic carbon and heavy metals flux started to increase at the beginning of the last century and the highest values was observed in the top of the cores.

Study of pollutant distribution in the Guaxindiba Estuarine System – SE Brazil

The Guaxindiba Estuarine System is located in the northeast portion of Guanabara Bay. Despite the location inside an environmental protection zone, the main affluent of the river runs through the extremely urbanized area of the cities of Niterói and São Gonçalo. In order to understand the contamination levels of the estuary, 35 surface sediment samples were collected along the river and estuarine area and analyzed for the presence of heavy metals, PAHs, organochlorated pesticides, polychlorinated biphenyl and other contaminants. The analyzed data revealed a greatly affected environment with respect to most of these substances. The results suggested propitious deposits of contaminants, with high concentrations of organic matter and fine sediment. The levels of heavy metal in the entire estuarine system were high compared with the local background. The total mean concentrations of As, Cd, Pb, Cu, Zn, Hg, Cr and Ni in the surface sediments were: 3.74; 0.03; 19.3; 15.0; 99.0; n.d.; 29.0; and 22.0mg/kg, respectively, confirming, in certain cases, the high capacity of the environment to concentrate pollution.

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

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.

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

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.

The Role of the Humic Substances in the Fractioning of Heavy Metals in Rodrigo de Freitas Lagoon, Rio de Janeiro - Brazil

One of the main results of the processes related to urbanization is the contamination of the adjacent water bodies. Inserted in this context, the Rodrigo de Freitas lagoon is situated in the south zone of the city of Rio de Janeiro. This ecosystem receives several inputs containing all sorts of pollutants, including heavy metals. The present work aimed to study the partitioning of heavy metals in the sediments of Rodrigo de Freitas and the influence of organic matter in this fractionation dynamic. The results of these analyses presented the contents of organic matter as an important metal-capturing agent. Fractionation of organic matter resulted in a predominance of humine. Heavy metal partitioning showed that the metals bound by the water-soluble phase have no significant concentrations. Special features such as, reducing sediment, high levels of organic matter and fine grain size have transformed this ecosystem in an effective deposit of pollutants, where heavy metals are not available in easily reactive fractions.

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

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.

Concentrations and physicochemical speciation of heavy metals in urban runoff sediment from São Gonçalo—Rio de Janeiro/Brazil

Urban runoff sediment samples were analyzed for heavy metal concentrations in different neighborhoods in São Gonçalo, Metropolitan region of Rio de Janeiro-Brazil. This study was undertaken to assess the anthropogenic impact of metal concentrations of urban roadside sediments from São Gonçalo and to estimate the potential mobility of selected metals (Zn, Cu, Pb, Cr and Ni) using a sequential partitioning extraction. The concentrations of heavy metals in this work were compared with reported values from other cities and urban areas. This study highlights the urban runoff sediment as a potential source for heavy metals. The physicochemical speciation of heavy metal highlight the potential bioavailability for all metals, but Cr. Three contamination indexes: geoaccumulation index, contamination factor and Pollution Load Index, were used in order to assess the level of metal contamination in the study area, which demonstrated the contamination originating from the urban runoff sediments.

Utilização do Índice de Qualidade da Água como indicador da gestão do impacto do turismo em Paraty, Rio de Janeiro/Brasil

quality. In this context, environmental monitoring is fundamental for the control and support to environmental managecampaigns undertaken at twenty sites were performed to characterize physical-chemical parameters, inorganic nutrient, Electronic Journal of Management & System Volume 11, Number 4, 2016, pp. 466-474 DOI: 10.20985/1980-5160.2016.v11n4.1160 467

Potentially mobile of heavy metals on the surface sediments in tropical hyper-saline and positive estuaries

Estuarine sediments represent important pools of trace metals, released from both anthropogenic and natural sources. Fluctuations in the water column physicochemical conditions, on the other hand, may transfer metals from solid to liquid compartment and resulting in contamination of the surrounding environment. The present research was carried out to evaluate the weakly bounded heavy metal levels in tropical hyper-saline and positive estuaries, in order to quantify its potentially availability. The monitoring includes five metals (Cd, Cr, Cu, Pb, Zn) and cover nine estuaries in Rio Grande do Norte state/Brazil, including four hypersaline and five true estuaries. 50 surface sediment samples were collected in each estuary. At the same time, organic matter concentrations were evaluated in order to help explaining possible local variations in heavy metal levels. Organic matter results (0.7% - 7.3%) suggest the positive Potengi estuary as the most critical environmental quality situation. On the other hand, according to heavy metals levels, both Conchas and Potengi estuaries registered the higher concentrations of Cr. The highest concentrations were observed in the hyper-saline estuaries, with the exception of the Zn. The present study revealed that the watershed occupation has significantly influenced the heavy metal concentrations in the estuaries.

Assessment of human effects through phosphorus partitioning in sediments from two catchment basins around Guanabara Bay, SE Brazil

Abstract Geochemical analyses of sediment samples collected along the fluvial systems of the Guapi-Macacu River and the Mangue Channel hydrographic basins, which flow into a distinct portion of the Guanabara Bay, show the presence of different anthropogenic impacts in the area. The Guanabara Bay is located inside the metropolitan area of Rio de Janeiro, which is one of the most urbanized and industrialized regions in Brazil. Consequently, this estuarine system is subjected to intense degradation processes due to the eutrophication of the hydrographic systems around the bay. This study aims to investigate the influence of the seasonal variations of environmental factors on the fractionation of phosphorus in the hydrographic basins of the Guapi-Macacu River and the Mangue Channel. The geochemical features of the water and sediments were analyzed, and the interactions between these features, the physicochemical parameters, and the sediment properties of the two basins were identified. Phosphorus fractionation revealed that the various forms of phosphorus displayed distinct behaviors. In the Mangue Channel Basin, the main phosphorus fraction detected during the winter and summer was associated with iron, indicating a reductive environment rich in organic matter (i.e., a polluted environment). In the basin of the Guapi-Macacu River during the winter, the residual phase (P-Re) was predominantly detected, whereas the metallic phase (P-Me) prevailed during the summer. The fractions associated with the physicochemical parameters did not vary significantly in this region, which implies oxidized and natural conditions.