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 metalsA urbanização acelerada, sem planejamento, resultou em uma série de problemas à zona costeira do Rio de Janeiro, especialmente em áreas como a Lagoa Rodrigo de Freitas, a qual recebe uma grande descarga de esgoto não tratado todos os dias. No intuito de avaliar a natureza, as fontes potenciais e a extensão da poluição por metais pesados na lagoa, sedimentos das ruas do entorno, das entradas do principal canal de drenagem e de superfície de fundo foram coletados. As análises se deram através de um método modificado de extração sequencial, com o objetivo de estudar o fracionamento geoquímico e a biodisponibilidade de Zn, Cu, Cr, Ni e Pb, nestes três compartimentos. O presente estudo verificou um aumento nas concentrações de Cu, Pb, e Zn no setor norte da Lagoa Rodrigo de Freitas. Apesar dos diferentes níveis de oxidação entre os sedimentos acumulados nas avenidas e no sedimento de fundo da lagoa, o fracionamento geoquímico dos metais pesados não apresentou nenhum padrão de variação, com exceção do Cu. Não foram observadas concentrações na fase solúvel, das amostras coletadas nos sedimentos superficiais na lagoa, sugerindo a não biodisponibilidade dos metais pesado

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

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

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

ABSTRACT 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

The transfer and resulting negative effects of nano- and micro-plastics through the aquatic trophic web—A discreet threat to human health

The ubiquitous occurrence of plastic nano- and micro-particle contamination has raised concerns about its potential risks and impacts on the global environment, especially in aquatic ecosystems. Hundreds of aquatic species, from different trophic levels, have been affected by this “new” contaminant, which has been reported mainly in their digestive tracts. Consequently, current knowledge about plastic nano- and micro-particle spread and the potential impact on aquatic biota is growing rapidly. However, there is a significant lack of understanding of the trophic spread of microplastic contamination and integration of knowledge derived from laboratory assays with that from field research is difficult. Field experiments are unable to deal with differentiating between directly and indirectly ingested plastic microparticles. On the other hand, laboratory assays evaluating the influence of plastic microparticles and of their adhered or constitutive toxins on representative species cannot satisfactorily simulate the real environment. As a result, little is known about the effective transfer of plastic particles through the trophic net and the resulting human health risks. The present review seeks to gather information that can give a more accurate idea of the current situation and future challenges to be faced in mitigating the environmental and human effects of plastic particle pollution in aquatic, particularly estuarine, ecosystems

Negative Impacts of Trace Metal Contamination on the Macrobenthic Communities along the Santos Port Complex—Brazil

Port sites represent one of the most impacted coastal areas; this impact is due to intensive anthropogenic pressures. In addition to the port complex itself, associated activities, such as indiscriminate disposal of pollutants, including trace metals, affect the local ecosystem. Macroinvertebrate benthic communities are one of the most effective bioindicators of environmental health because of their importance as a primary food source for many fish, birds, and mammals, as well as their influence on sediment stability and geochemical composition. This article evaluates the benthic macrofauna in the Santos Estuarine System (SES), the location of the Santos Port Complex (SPC), linking trace metal levels to differences in microbenthic community structure and pollutant bioavailability. The distribution of Cd, Ni, and Pb was directly related to organic matter deposits, while Cu and Zn appeared to result from port activities. The SES contained a poor benthic macroinvertebrate community, resulting from the contaminated muddy sediments. A significant negative correlation was found between the macrobenthic diversity and concentrations of Cu in the soluble phase; this implied the pollution-induced degradation of the macrobenthos in SES