Rosivaldo de Alcântara Mendes

Ocorrência de uma floração de cianobactérias tóxicas na margem direita do Rio Tapajós, no Município de Santarém (Pará, Brasil)

The presence of cyanobacterial blooms and their subproducts interferes directly in water quality and may cause negative effects, both aesthetically and to public health, due to the production of potentially toxic and carcinogenic compounds. The most common type of intoxication involving cyanobacteria is caused by microcystin-LR (hepatotoxin), which can cause severe damage to the liver. The objective of this study was to identify the genera that caused cyanobacterial blooms in the Tapajos river (Santarem, Para, Brazil) in March 2007, as well as to execute acute toxicity bioassays in Swiss-webster mice. Sample collection was performed at five sampling points throughout the left margin of the Tapajos river, by horizontal dragging with the aid of a 20 μm plankton net. Samples of raw water (5,000 ml) were also collected in amber propylene bottles. Optical microscopy was applied to identify the organisms, and the determination of microcystin-LR was executed through ELISA and HPLC. The analyses showed that, at P01 and P02, there was an ecological imbalance in the phytoplanktonic community, characterized by an intense proliferation of the genera Anabaena and Microcystis. The concentrations of microcystin-LR reported in the raw water samples were below the maximum values permitted by Brazils legislation for drinking water. However, it is important to note that the blooming observed in loco occupied around 10 cm of the water column surface and therefore presented cyanobacterial cells enough to cause rashes in people who swam or bathed in the rivers during this period.

Occurrence of toxic cyanobacterial bloom in the left margin of the Tapajós river, in the Municipality of Santarém (Pará State, Brazil)

The presence of cyanobacterial blooms and their subproducts interferes directly in water quality and may cause negative effects, both aesthetically and to public health, due to the production of potentially toxic and carcinogenic compounds. The most common type of intoxication involving cyanobacteria is caused by microcystin-LR (hepatotoxin), which can cause severe damage to the liver. The objective of this study was to identify the genera that caused cyanobacterial blooms in the Tapajos river (Santarem, Para, Brazil) in March 2007, as well as to execute acute toxicity bioassays in Swiss-webster mice. Sample collection was performed at five sampling points throughout the left margin of the Tapajos river, by horizontal dragging with the aid of a 20 μm plankton net. Samples of raw water (5,000 ml) were also collected in amber propylene bottles. Optical microscopy was applied to identify the organisms, and the determination of microcystin-LR was executed through ELISA and HPLC. The analyses showed that, at P01 and P02, there was an ecological imbalance in the phytoplanktonic community, characterized by an intense proliferation of the genera Anabaena and Microcystis. The concentrations of microcystin-LR reported in the raw water samples were below the maximum values permitted by Brazils legislation for drinking water. However, it is important to note that the blooming observed in loco occupied around 10 cm of the water column surface and therefore presented cyanobacterial cells enough to cause rashes in people who swam or bathed in the rivers during this period.

Levels of organochlorine pesticides in Amazon turtle (Podocnemis unifilis) in the Xingu River, Brazil

Abstract Due to the toxicity and high environmental persistence of organochlorine pesticides in aquatic organisms, turtles have been studied as environment biomonitors. These animals are important sources of protein for the riverside and indigenous peoples of the Brazilian amazon. In the present study, organochlorine pesticide contamination was investigated in Podocnemis unifilis. Liver, muscle and fatty tissue samples were removed from 50 specimens collected from five sampling points located in the Xingu River basin. Fourteen organochlorine pesticides were analysed via gas chromatography with an electron capture detector (CG-ECD). Eight organochlorine pesticides were detected with average concentrations of ∑DDT, ∑Endossulfan and ∑HCH which were 26.17 ± 26.35, 14.38 ± 23.77 and 1.39 ± 8.46 ng g−1 in moisture content, respectively. DDT compounds were the most predominant, with a greater concentration of pp′-DDT in the liver and pp′-DDD in the muscle. Significant differences were noted between the types of tissues studied, and the concentration of OCPs varied between sampling sites.AbstractDue to the toxicity and high environmental persistence of organochlorine pesticides in aquatic organisms, turtles have been studied as environment biomonitors. These animals are important s...

Assessment of Mercury Concentration in Turtles (Podocnemis unifilis) in the Xingu River Basin, Brazil

Many studies on mercury contamination in aquatic biota deal with the effect of consuming metal-contaminated organisms on human health. In this study, we examined the factors that cause mercury contamination in Podocnemis unifilis in the Xingu River Basin of Mato Grosso and Pará States, Brazil. We quantified by atomic absorption spectroscopy with cold vapor the total mercury (THg) content in the liver and muscle samples of 50 Podocnemis unifilis specimens collected from the basin. The liver and muscle samples contained 134.20 ± 119.30 ng g−1 THg and 24.86 ± 26.36 ng g−1 THg, respectively. Each chelonian or meal has, on average, 5.34× more Hg than the highest level established as acceptable. From the results it can be inferred that, given the weekly consumption of chelonians, the riverine and indigenous communities in the Xingu River Basin are at risk of chronic consumption of Hg in amounts beyond the acceptable limit. The potential high risk to the health of this population is evident; however, the risk classification needs to be further studied.

Floración de cianobacterias tóxicas en la orilla derecha del río Tapajós, en el Municipio de Santarém (Pará, Brasil)

The presence of cyanobacterial blooms and their subproducts interferes directly in water quality and may cause negative effects, both aesthetically and to public health, due to the production of potentially toxic and carcinogenic compounds. The most common type of intoxication involving cyanobacteria is caused by microcystin-LR (hepatotoxin), which can cause severe damage to the liver. The objective of this study was to identify the genera that caused cyanobacterial blooms in the Tapajos river (Santarem, Para, Brazil) in March 2007, as well as to execute acute toxicity bioassays in Swiss-webster mice. Sample collection was performed at five sampling points throughout the left margin of the Tapajos river, by horizontal dragging with the aid of a 20 μm plankton net. Samples of raw water (5,000 ml) were also collected in amber propylene bottles. Optical microscopy was applied to identify the organisms, and the determination of microcystin-LR was executed through ELISA and HPLC. The analyses showed that, at P01 and P02, there was an ecological imbalance in the phytoplanktonic community, characterized by an intense proliferation of the genera Anabaena and Microcystis. The concentrations of microcystin-LR reported in the raw water samples were below the maximum values permitted by Brazils legislation for drinking water. However, it is important to note that the blooming observed in loco occupied around 10 cm of the water column surface and therefore presented cyanobacterial cells enough to cause rashes in people who swam or bathed in the rivers during this period.