RESUMO
Mercury concentrations in oysters from four estuaries in northeastern Brazil varied following source changes during the past 13 years. Concentrations were higher in urban estuaries relative to rural areas, but decreased in the 13-years interval following improvements in solid wastes disposal and sewage treatment. In rural estuaries, the one located in an environmental protection area showed no changes in Hg concentrations in the period. However, in the Jaguaribe estuary, remobilization from soils and sediments due to regional environmental changes, increased Hg concentrations in oysters to values similar to the most contaminated metropolitan sites.
Assuntos
Monitoramento Ambiental/métodos , Mercúrio/análise , Ostreidae/química , Animais , Brasil , Estuários , Rhizophoraceae/química , Frutos do MarRESUMO
This paper estimates annual P emission to the Jaguaribe River estuary, NE Brazil, responsible for approximately 30% of the country's farmed shrimp production. Emissions increased three times between 2001 and 2006 and reached 43.9 t.year-1. These emissions make aquaculture the third main source of P for this estuary and are much smaller than emissions from agricultural sources and slightly lower than emissions from wastewater. Their relative contribution also increased from 10.5% to 20.5%. Temporal variability of P concentrations in estuarine bottom sediments also suggest an increase, but not as evident as the emissions. The spatial distribution and speciation of P (total P and inorganic P) in sampling stations located upstream and downstream from the main aquaculture area confirmed the importance of this source. Inorganic P was the dominant form present in sediments downstream and showed an increase from 67% to 75% of the total P present in the sediment.
Assuntos
Monitoramento Ambiental/métodos , Sedimentos Geológicos/química , Fósforo/análise , Rios/química , Poluentes Químicos da Água/análise , Animais , Aquicultura , BrasilRESUMO
This paper estimates annual P emission to the Jaguaribe River estuary, NE Brazil, responsible for approximately 30 percent of the country's farmed shrimp production. Emissions increased three times between 2001 and 2006 and reached 43.9 t.year-1. These emissions make aquaculture the third main source of P for this estuary and are much smaller than emissions from agricultural sources and slightly lower than emissions from wastewater. Their relative contribution also increased from 10.5 percent to 20.5 percent. Temporal variability of P concentrations in estuarine bottom sediments also suggest an increase, but not as evident as the emissions. The spatial distribution and speciation of P (total P and inorganic P) in sampling stations located upstream and downstream from the main aquaculture area confirmed the importance of this source. Inorganic P was the dominant form present in sediments downstream and showed an increase from 67 percent to 75 percent of the total P present in the sediment.(AU)
É apresentada uma estimativa da emissão anual de P para o estuário do rio Jaguaribe, Ceará, Nordeste do Brasil, área responsável por cerca de 30 por cento da produção total de camarão cultivado no país. As emissões aumentaram por um fator de três entre 2001 e 2006, atingindo 43,9 t.year-1. Essa emissão coloca a aquacultura como a terceira fonte principal de P para esse estuário, sendo bem menor que a emissão de fontes agrícolas e um pouco menor que as emissões por águas servidas. A contribuição relativa da aquacultura também aumentou de 10,5 por cento a 20,5 por cento, no mesmo período. A variação temporal das concentrações de P em sedimentos estuarinos sugere um aumento no período, porém não tão evidente quanto das emissões. A distribuição espacial e a especiação do P (P total e P inorgânico) em estações de coleta localizadas à montante e à jusante da principal área de aquacultura confirmaram a importância desta fonte. O P inorgânico foi a forma dominante presente em sedimentos à jusante e mostrou um aumento de 67 por cento a 75 por cento do total de P presente no sedimento.(AU)
Assuntos
Animais , Monitoramento Ambiental/métodos , Sedimentos Geológicos/química , Fósforo/análise , Rios/química , Poluentes Químicos da Água/análise , Aquicultura , BrasilRESUMO
We present here the first results of Hg concentrations in three small shark species (Rhizoprionodon lalandei, R. porosus and Mustelus higmani) from the SE Brazilian coast. Mercury concentrations in R. lalandei ranged from 21.5 to 280.0 ng.g-1 dry weight (d.w.) (average 74.6 ng.g-1 d.w.; 17.9 ng.g-1 wet weight). In R. porosus, concentrations ranged from 7.6 to 90.5 ng.g-1 d.w. (average 42.2 ng.g-1 d.w., 9.4 ng.g-1 wet weight), whereas in M. higmani, concentrations ranged from 13.0 to 162.8 ng.g-1 d.w. (average 54.9 ng.g-1 d.w., 13.4 ng.g-1 wet weight). These concentration ranges are very low compared with values reported for other large shark species of the Southwestern Atlantic Ocean. There was a significant positive correlation between Hg concentrations and individual size, suggesting that biomagnification is occurring in these animals
Assuntos
Animais , Mercúrio , Tubarões , BrasilRESUMO
We present here the first results of Hg concentrations in three small shark species (Rhizoprionodon lalandei, R. porosus and Mustelus higmani) from the SE Brazilian coast. Mercury concentrations in R. lalandei ranged from 21.5 to 280.0 ng.g-1 dry weight (d.w.) (average 74.6 ng.g-1 d.w.; 17.9 ng.g-1 wet weight). In R. porosus, concentrations ranged from 7.6 to 90.5 ng.g-1 d.w. (average 42.2 ng.g-1 d.w., 9.4 ng.g-1 wet weight), whereas in M. higmani, concentrations ranged from 13.0 to 162.8 ng.g-1 d.w. (average 54.9 ng.g-1 d.w., 13.4 ng.g-1 wet weight). These concentration ranges are very low compared with values reported for other large shark species of the Southwestern Atlantic Ocean. There was a significant positive correlation between Hg concentrations and individual size, suggesting that biomagnification is occurring in these animals.
Assuntos
Mercúrio/análise , Tubarões , Animais , BrasilRESUMO
A system, based on annular gold-coated denuders, was optimized and used in the atmospheric sampling of mercury in urban and rural sites of the Alta Floresta, a region in the Brazilian Amazon. Results showed that vapour phase mercury (Hgv) is dominant in samples collected in both sites. However, particulate mercury (Hg) may sometimes be significant at the urban site, with values representing up to 77% of the total Hg collected during sampling, but may also be insignificant at the same site, depending on the gold commercialization activity and, probably, on the meteorological conditions during the sampling period. The presence of mercury in both the vapour and particulate phases in the atmosphere of the urban site can explain the high mercury concentrations found in urban dust reported for some cities in the Amazon, and also the relatively high Hg concentrations found in soils adjacent to the urban centre of Alta Floresta. It appears that the urban dust of "garimpo" areas in the Amazon can act as an efficient adsorber of Hgv emitted by gold dealer operations during the purification process. Mercury emissions from gold dealer shops in the Amazon have been considered as a human health risk through the inhalation of Hg vapour. However, although true for indoor sites, the significant contribution of particulate phase Hg shown in this study in outdoor urban sites calls for a re-evaluation of the risk assessment estimates performed up to now in urban centres in the Amazon.