... Ex. (SILVA, Maria, 2002) ou Silva, Maria (2002) (SILVA, Mauricio, 2002) ou Silva, Maurício (2002) c) quando se tratar de vários trabalhos de um mesmo autor, publicados na mesma data usam-se letras minúsculas acompanhando a data. Ex.:... more
... Ex. (SILVA, Maria, 2002) ou Silva, Maria (2002) (SILVA, Mauricio, 2002) ou Silva, Maurício (2002) c) quando se tratar de vários trabalhos de um mesmo autor, publicados na mesma data usam-se letras minúsculas acompanhando a data. Ex.: SMITH (1978a, 1978b, 1978c) ...
Groundwater is heavily exploited for a variety of uses. Depending on their structure, the wells from which water is extracted can act as an entry point/gateway for a variety of microbiological contaminants, which can cause numerous... more
Groundwater is heavily exploited for a variety of uses. Depending on their structure, the wells from which water is extracted can act as an entry point/gateway for a variety of microbiological contaminants, which can cause numerous adverse health effects. This study aimed to identify the microorganisms present in the groundwater in the Western Amazonian city of Porto Velho, using a methodology that can be deployed in other city centers. We collected 74 water samples from both dug and drilled wells in March, August and November 2018. Total coliforms were detected in 96% of dug wells and 74% of drilled wells. Thermotolerant coliforms were found in 90% of dug wells and 61% of drilled wells. Biochemical identification indicated 15 genera of bacteria. The genera Escherichia, Enterobacter, Cronobacter and Citrobacter had the highest prevalence. The genera Pseudomonas and Enterococcus were also detected. Thermotolerant coliforms showed higher values when the water flow was higher. Our resu...
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Groundwater quality can be affected by many factors. The objective of this study was to assess the quality of groundwater and map the flow direction, to identify possible sources of contamination in the districts of Nova Londrina and Nova... more
Groundwater quality can be affected by many factors. The objective of this study was to assess the quality of groundwater and map the flow direction, to identify possible sources of contamination in the districts of Nova Londrina and Nova Colina (Ji-Paraná, Rondônia). Water samples were collected in September 2015 and February 2016 in 20 wells in Nova Londrina and in December 2016 and April 2017 in 15 wells in Nova Colina. The turbidity, pH and electrical conductivity (EC) were measured in loco. The microbiological parameters were determined by the membrane filtration method in a chromogenic medium, and the total dissolved solids (TDS) were measured by the gravimetric method. The nutrients ammonia, nitrite, nitrate, dissolved phosphorus and total phosphorus were ascertained by the spectrophotometric method and the underground flow was obtained by applying the Surfer 8.0 software. Through principal component analysis (PCA) it was possible to detect that the TDS, total coliforms, pH a...
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This excel file contains the true scores (Fmax) of the EEM-PARAFAC model
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Vários estudos têm sido desenvolvidos nos últimos 20 anos na bacia do Rio Madeira (Amazônia) com o objetivo de diagnosticar a presença de mercúrio em peixes e compreender o ciclo deste elemento no ...
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Información del artículo The presence of mercury in bottom sediments and rocks from Madeira river, Brazil.
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The concentration of chlorine in water declines as it reacts with various substances, causing decay of the residual free chlorine until its total consumption. In light of the typical characteristics of the water from protected dug wells... more
The concentration of chlorine in water declines as it reacts with various substances, causing decay of the residual free chlorine until its total consumption. In light of the typical characteristics of the water from protected dug wells and tube wells, this study aimed to evaluate the decay kinetics of free chlorine in the water of alternative individual supply (AIS) solutions used in the city of Porto Velho in the Brazilian Amazon region. The free chlorine decay constant in the water was evaluated by “bottle tests,” applying a first-order model. According to the results, the type of well and initial chlorine concentration significantly influences the free chlorine decay speed. The water samples from the tubular wells had lower chlorine demand levels, attributed to their better water quality. The simulation of the residual chlorine decay in the different supply sources is an important tool to support safe disinfection processes.
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O Distrito de Jaci-Paraná possui uma população média de 18.000 habitantes e está situado a 87 km do município de Porto Velho, Rondônia, Amazônia Ocidental. Neste distrito o saneamento básico é inexistente. Assim, a captação de água é... more
O Distrito de Jaci-Paraná possui uma população média de 18.000 habitantes e está situado a 87 km do município de Porto Velho, Rondônia, Amazônia Ocidental. Neste distrito o saneamento básico é inexistente. Assim, a captação de água é realizada por meio de poços, principalmente “poços amazonas” e os rejeitos de esgotos são lançados a céu aberto, fossas negras ou pequenos igarapés. O presente trabalho teve como objetivo avaliar a qualidade dos recursos hídricos subterrâneos por meio dos seguintes parâmetros: condutividade elétrica, cor aparente, pH, constituintes iônicos, tais como: fluoreto, cloreto, nitrito, brometo, nitrato, fosfato, sulfato, lítio, sódio, amônio, potássio, cálcio e magnésio, além de análises microbiológicas de coliformes fecais e coliformes totais. A coleta das amostras foi realizada nos meses de dezembro/2011 e maio/2012. Todas as 82 amostras analisadas apresentaram contaminação por coliformes totais e 42,3% das amostras de água apresentaram níveis de nitrato aci...
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Mercury is a major pollutant in the Amazon River system, and its levels in fish and human hair are usually above the limit recommended by health agencies. The objective of this study was to analyze the methylmercury (MeHg) concentration... more
Mercury is a major pollutant in the Amazon River system, and its levels in fish and human hair are usually above the limit recommended by health agencies. The objective of this study was to analyze the methylmercury (MeHg) concentration in fish tissue from the Roosevelt River. The river’s water velocity, depth, pH, temperature, electrical conductivity, dissolved oxygen and substrate type were measured, and fifty specimens distributed in 14 fish species were collected. A total of 64.3% of the sampled species were of the order Characiform and 71.4% of the species were carnivores. Fifty percent of the species had MeHg concentrations above threshold limit (Hg-T 0.5 mg kg-1) established for food by the World Health Organization. Cichla monoculus had the highest value of MeHg (2.45 mg kg-1). The MeHg concentration in fish varied according to dietary habits. The study also found bioaccumulation of MeHg in fish tissue in the following descending order: carnivorous > detritivorous > fr...
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Sex plays an important role in the kinetics and dynamics of methylmercury in some animals. Although fish is the main source of mercury exposure to consumers, the role of sex in fish-Hg bioaccumulation is less known. We studied total Hg... more
Sex plays an important role in the kinetics and dynamics of methylmercury in some animals. Although fish is the main source of mercury exposure to consumers, the role of sex in fish-Hg bioaccumulation is less known. We studied total Hg (THg) concentrations in 2538 samples (males=1052, females=1486) of fish from different trophic levels (herbivorous, planctivorous, detritivorous, omnivorous, carnivorous, piscivorous); for each species we made a post hoc estimation of the minimum number of samples required to detect variance-based differences between sexes. Only five of the 41 studied species showed significant difference between sexes; but, no consistent dominant pattern of THg concentrations favored either sex. When grouped by trophic levels, overall mean difference in THg concentrations between males and females were not statistically significant. Correlation analysis showed sex-dependent THg bio-accumulation as a function of condition factor was statistically significant and negat...
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Significant knowledge gaps exist regarding the fate and transport of persistent organic pollutants like dichlorodiphenyltrichloroethane (DDT) in tropical environments. In Brazil, indoor residual spraying with DDT to combat malaria and... more
Significant knowledge gaps exist regarding the fate and transport of persistent organic pollutants like dichlorodiphenyltrichloroethane (DDT) in tropical environments. In Brazil, indoor residual spraying with DDT to combat malaria and leishmaniasis began in the 1950s and was banned in 1998. Nonetheless, high concentrations of DDT and its metabolites were recently detected in human breast milk in the community of Lake Puruzinho in the Brazilian Amazon. In this work, we couple analysis of soils and sediments from 2005 to 2014 at Puruzinho with a novel dynamic floodplain model to investigate the movement and distribution of DDT and its transformation products (dichlorodiphenyldichloroethylene (DDE) and dichlorodiphenyldichloroethane (DDD)) and implications for human exposure. The model results are in good agreement with the accumulation pattern observed in the measurements, in which DDT, DDE, and DDD (collectively, DDX) accumulate primarily in upland soils and sediments. However, a sig...
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A população de Lábrea – AM está estimada em 46.069 habitantes, dos quais quase 70% vive em área urbana. A migração da população campo-cidade tem propiciado a expansão indiscriminada do espaço urbano de Lábrea. Por isso, é comum encontrar... more
A população de Lábrea – AM está estimada em 46.069 habitantes, dos quais quase 70% vive em área urbana. A migração da população campo-cidade tem propiciado a expansão indiscriminada do espaço urbano de Lábrea. Por isso, é comum encontrar domicílios em áreas impróprias para instalação de moradias, não só do ponto de vista da fragilidade ambiental, mas também do ponto de vista geotécnico. Assim, o estudo teve o objetivo de realizar o diagnóstico da fragilidade ambiental potencial na área urbana do município de Lábrea. Os procedimentos metodológicos foram organizados em etapas: 1) arquitetura organizacional dos dados no SIG; 2) preparação de base cartográfica e processamento digital de imagem e; 3) determinação das classes de fragilidade potencial, a partir do método de individualização de unidades ecodinâmicas instáveis e estáveis. A cidade de Lábrea apresenta áreas com fragilidade ambiental potencial fraca, média e forte, correspondendo a 33,18%, 7,3% e 51,63% respectivamente. As uni...
Este trabalho teve por objetivo avaliar a qualidade da água subterrânea do aquífero livre na microbacia do igarapé Nazaré (Ji-Paraná-RO), por meio de análises físico-químicas e microbiológicas. Foram realizadas 4 coletas de amostras de... more
Este trabalho teve por objetivo avaliar a qualidade da água subterrânea do aquífero livre na microbacia do igarapé Nazaré (Ji-Paraná-RO), por meio de análises físico-químicas e microbiológicas. Foram realizadas 4 coletas de amostras de água em 15 poços rasos nos meses de (março, junho, setembro e dezembro de 2019). Os parâmetros condutividade elétrica, temperatura e o pH foram determinadas in loco por meio de sonda multiparâmetros. A turbidez e os sólidos totais dissolvidos foram determinados no laboratório com sondas especificas. O oxigênio dissolvido foi determinado pelo método titulométrico, a alcalinidade total foi obtida por titulação potenciométrica. As análises dos nutrientes foram realizadas por métodos espectrofotométricos, e as análises microbiológicas realizadas conforme o método de membrana filtrante em meio cromogênico. De acordo com os Valores Máximos Permitidos estabelecidos pela Portaria de Consolidação n° 5/2017 do Ministério da Saúde e com a Resolução do Conselho N...
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The aim of this study was to evaluate the physical, chemical and microbiological groundwater parameters as well as the mapping of groundwater flow in an urban area of Presidente Médici county in Rondônia State, Southern Amazon. The water... more
The aim of this study was to evaluate the physical, chemical and microbiological groundwater parameters as well as the mapping of groundwater flow in an urban area of Presidente Médici county in Rondônia State, Southern Amazon. The water samples were collected in 11 wells in April and June of 2017, which corresponds to the dry season in the studied region. Groundwater was acidic, with a large range of nutrients concentration, low turbidity and presence of fecal coliforms in most sampled wells. The parameters that were in disagreement with Consolidation Ordinance No 05/2017/MS and CONAMA no 396/08 Resolution, were pH, turbidity, total coliforms, Escherichia coli, and nitrate. Regarding the microbiological parameter, most of the sampling sites were in disagreement with the established by the legislation that it recommends to be absent in 100mL, when it is destined for human consumption. Densities found were higher than 112,000UFC/100mL for total coliforms and higher than 56,000UFC/100...
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An agroforestry system (AFS) describes the conjoint use of land for agricultural andforestry purposes. An AFS plays a strategic role in the mitigation of carbon dioxide(CO2) emissions, and stands as an alternative in land use that reduces... more
An agroforestry system (AFS) describes the conjoint use of land for agricultural andforestry purposes. An AFS plays a strategic role in the mitigation of carbon dioxide(CO2) emissions, and stands as an alternative in land use that reduces mercury (Hg)remobilization in cultivated soils. This study evaluated the spatial variability of Hgconcentrations as indicators of environment changes and soil quality in different landcover and use systems in a rural settlement in southern Amazon, Brazil. Themethodological procedures were carried out as steps: the experimental units weredefined, physical and chemical characteristics of soil samples were analyzed, anddata were evaluated using conventional and spatial statistics. The AFS included hadbeen established 10 years before or more, and had high Hg retention capacity ,compared with Hg levels in soils on migratory agriculture or that are not fallowed .Therefore, due to low AFS improve soil quality due to the low intensity of harrowing,increasi...
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Total mercury (THg) concentrations measured in two freshwater shrimp species (Macrobrachium depressimanum and Macrobrachium jelskii) showed a relationship with the location of artisanal and small-scale gold mining (ASGM) from the Madeira... more
Total mercury (THg) concentrations measured in two freshwater shrimp species (Macrobrachium depressimanum and Macrobrachium jelskii) showed a relationship with the location of artisanal and small-scale gold mining (ASGM) from the Madeira River Basin, Western Amazon. Between August 2009 and May 2010, 212 shrimp samples were collected in the confluence of the Madeira River with three of its tributaries (Western Amazon). THg concentration was quantified in the exoskeleton, hepatopancreas and muscle tissue of the shrimps by cold vapor atomic absorption spectrophotometry. There were no significant differences between the two shrimp species when samples came from the Madeira River, but Hg concentrations were significantly lower in a tributary outside the influence of the gold mining area. Average THg concentrations were higher in the hepatopancreas (up to 160.0 ng g) and lower in the exoskeleton and muscle tissue (10.0-35.0 ng gand < 0.9-42.0 ng g, respectively). Freshwater shrimps fro...
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We investigated the impact of the seasonal inundation of wetlands on methylmercury (MeHg) concentration dynamics in the Amazon river system. We sampled 38 sites along the Solimões/Amazon and Negro rivers and their tributaries during... more
We investigated the impact of the seasonal inundation of wetlands on methylmercury (MeHg) concentration dynamics in the Amazon river system. We sampled 38 sites along the Solimões/Amazon and Negro rivers and their tributaries during distinct phases of the annual flood-pulse. MeHg dynamics in both basins was contrasted to provide insight into the factors controlling export of MeHg to the Amazon system. The export of MeHg by rivers was substantially higher during high-water in both basins since elevated MeHg concentrations and discharge occurred during this time. MeHg concentration was positively correlated to %flooded area upstream of the sampling site in the Solimões/Amazon Basin with the best correlation obtained using 100 km buffers instead of whole basin areas. The lower correlations obtained with the whole basin apparently reflected variable losses of MeHg exported from upstream wetlands due to demethylation, absorption, deposition, and degradation before reaching the sampling s...
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Infant exposure to neurotoxic elements is a public health issue that needs monitoring with regard to breast milk composition. We studied six neurotoxic elements in breast milk samples at different stages of lactation in mothers from Porto... more
Infant exposure to neurotoxic elements is a public health issue that needs monitoring with regard to breast milk composition. We studied six neurotoxic elements in breast milk samples at different stages of lactation in mothers from Porto Velho, Brazil. We used a flow-injection mercury system (FIMS) to determine total Hg concentrations and an inductively coupled plasma optical emission spectrometer (ICP-OES) to determine the concentrations of Al, As, Cd, Pb, and Mn in 106 donors of a human milk bank. Association rules analyses were applied to determine the pattern of binary and ternary mixtures of the measured exposants. The metal concentration was mostly below the limit of detection (LOD) for Cd (99%), Pb (84%), and Hg (72%), and it was above the LOD for As (53%), Mn (60%), and Al (82%), respectively. Median concentrations (dry weight) of Al, As, Hg, Mn, and Pb were 1.81 μg/g, 13.8 ng/g, 7.1 ng/g, 51.1 ng/g, and 0.43 μg/g, respectively. Al is singly the most frequent element to whi...
Research Interests: Chemistry, Medicine, Manganese, Aluminum, Heavy metals, and 9 moreHumans, Female, Lead, Mothers, Thimerosal, Cadmium, Breast feeding, Human Milk, and Maternal Exposure
Wetlands are the largest global source of atmospheric methane (CH4), a potent greenhouse gas. However, methane emission inventories from the Amazon floodplain, the largest natural geographic source of CH4 in the tropics, consistently... more
Wetlands are the largest global source of atmospheric methane (CH4), a potent greenhouse gas. However, methane emission inventories from the Amazon floodplain, the largest natural geographic source of CH4 in the tropics, consistently underestimate the atmospheric burden of CH4 determined via remote sensing and inversion modelling, pointing to a major gap in our understanding of the contribution of these ecosystems to CH4 emissions. Here we report CH4 fluxes from the stems of 2,357 individual Amazonian floodplain trees from 13 locations across the central Amazon basin. We find that escape of soil gas through wetland trees is the dominant source of regional CH4 emissions. Methane fluxes from Amazon tree stems were up to 200 times larger than emissions reported for temperate wet forests and tropical peat swamp forests, representing the largest non-ebullitive wetland fluxes observed. Emissions from trees had an average stable carbon isotope value (δ13C) of -66.2 ± 6.4 per mil, consisten...
Research Interests: Wetlands, Brazil, Rivers, Multidisciplinary, Nature, and 5 moreWood, Atmosphere, Methane, Rainforest, and Trees
Pristine forest ecosystems provide a unique perspective for the study of plant-associated microbiota since they host a great microbial diversity. Although the Amazon forest is one of the hotspots of biodiversity around the world, few... more
Pristine forest ecosystems provide a unique perspective for the study of plant-associated microbiota since they host a great microbial diversity. Although the Amazon forest is one of the hotspots of biodiversity around the world, few metagenomic studies described its microbial community diversity thus far. Understanding the environmental factors that can cause shifts in microbial profiles is key to improving soil health and biogeochemical cycles. Here we report a taxonomic and functional characterization of the microbiome from the rhizosphere of Brosimum guianense (Snakewood), a native tree, and bulk soil samples from a pristine Brazilian Amazon forest reserve (Cuniã), for the first time by the shotgun approach. We identified several fungi and bacteria taxon significantly enriched in forest rhizosphere compared to bulk soil samples. For archaea, the trend was the opposite, with many archaeal phylum and families being considerably more enriched in bulk soil compared to forest rhizosp...
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Mercury is a toxic metal, ubiquitous in nature; it is excreted in breast milk from exposed mothers and may affect infant neuro-development. In this study, 224 breast milk samples provided by eight human milk banks in the Federal District... more
Mercury is a toxic metal, ubiquitous in nature; it is excreted in breast milk from exposed mothers and may affect infant neuro-development. In this study, 224 breast milk samples provided by eight human milk banks in the Federal District of Brazil were analyzed for total mercury (THg), of which 183 were also analyzed for methyl mercury (MeHg), the most relevant form of this metal for the breastfed infants. Samples were acid digested in a microwave oven and THg determined by atomic fluorescence spectrometry (LOQ of 0.76μg/L). Samples were lyophilized, ethylated and MeHg determined in a MERX automated system (LOQ of 0.10μg/L). Inorganic mercury (IHg) levels were estimated from the THg and MeHg determined in the samples. Most of the samples were collected 1-2 months postpartum, with 38% during the first month. Over 80% of the samples had THg values above the LOQ, reaching a maximum of 8.40μg/L, with a mean of 2.56μg/L. On average, MeHg accounted for 11.8% of THg, with a maximum of 97.4...
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The present study assesses mercury biomagnification and the trophic structure of the ichthyofauna from the Puruzinho Lake, Brazilian Amazon. In addition to mercury determination, the investigation comprised the calculation of Trophic... more
The present study assesses mercury biomagnification and the trophic structure of the ichthyofauna from the Puruzinho Lake, Brazilian Amazon. In addition to mercury determination, the investigation comprised the calculation of Trophic Magnification Factor (TMF) and Trophic Magnification Slope (TMS), through the measurements of stable isotopes of carbon (δ(13)C) and nitrogen (δ(15)N) in fish samples. These assessments were executed in two different scenarios, i.e., considering (1) all fish species or (2) only the resident fish (excluding the migratory species). Bottom litter, superficial sediment and seston were the sources used for generating the trophic position (TP) data used in the calculation of the TMF. Samples from 84 fish were analysed, comprising 13 species, which were categorized into four trophic guilds: iliophagous, planktivorous, omnivorous and piscivorous fish. The δ(13)C values pointed to the separation of the ichthyofauna into two groups. One group comprised iliophagou...
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This study aims to evaluate the Cr concentrations in surface water, suspended particles, and bottom sediments exposed to tannery effluent releases in the Candeias River. Cr concentrations were compared in relation to environmental... more
This study aims to evaluate the Cr concentrations in surface water, suspended particles, and bottom sediments exposed to tannery effluent releases in the Candeias River. Cr concentrations were compared in relation to environmental thresholds imposed by United States Environmental Protection Agency (USEPA) and the Brazilian Environmental Council (CONAMA), and the geoaccumulation index (Igeo) was calculated in bottom sediment. Samples were collected in flood and dry seasons. Cr extraction was done by an acid extraction and quantified by flame atomic absorption spectrometry. Most samples were found to be below the environmental thresholds imposed by CONAMA and USEPA, except in the one from the discharge zone sampled during the dry season, showing values 1.5 and 6.1 higher than CONAMA in water and bottom sediment, respectively. Cr concentrations were significantly higher (P < 0.001) in suspended particles during dry season than flood season. Surface water and bottom sediment did not ...
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Page 1. Método geoestatístico para modelagem ambiental de poluentes em sistemas lacustres Amazônia Ocidental. Ronaldo de Almeida1 José Vicente Elias Bernardi1 Wanderley Rodrigues Bastos1 Elisabete Lourdes do ...
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In the Pocone district, Brazil, Hg distribution was studied in a small watershed which drains tailings from a 10 yr old gold mining operation. Heavy regional rains are responsible for continuous weathering, thereby making it possible to... more
In the Pocone district, Brazil, Hg distribution was studied in a small watershed which drains tailings from a 10 yr old gold mining operation. Heavy regional rains are responsible for continuous weathering, thereby making it possible to transport Hg into the ecologically important Pantanal area. Mercury concentrations in creek sediments range from < 0.02 to 0.18 mg. kg -1. The highest concentrations occur close to the tailings deposit. Mercury concentrations in the water were always below the detection limit of the analytical method used (<0.04 txg. L-I). Suspended matter samples collected before, during and after a storm, showed a Hg peak value of 0.61 mg kg -~ about 30 min after the event. Dissolved Hg concentration still fell below the detection limit. Among the biota, molluscs accumulated moderately high concentrations of Hg, while macrophytes and fish did not. Mercury concentrations in molluscs were dependent on size, with larger animals presenting higher Hg concentration. We conclude that Hg present in the tailings shows low mobility and that its eventual transport into the drainage system is dependent on the erosion of fine material from the wastes during rains, resulting in a restricted contamination of the area and low Hg concentration in the biota.
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As águas subterrâneas do Aquífero Parecis (AP) representam a única fonte explorada para o abastecimento público de água potável do município de Vilhena - RO. Nesse sentido, a avaliação da qualidade da água determinada por análises... more
As águas subterrâneas do Aquífero Parecis (AP) representam a única fonte explorada para o abastecimento público de água potável do município de Vilhena - RO. Nesse sentido, a avaliação da qualidade da água determinada por análises físicas, químicas e microbiológicas, podem fornecer subsídios para a compreensão das condições da água consumida. No presente estudo, foram realizadas duas coletas de água subterrânea em 12 poços distribuídos na cidade: a primeira no período de estiagem (seca), em agosto de 2013; e a outra no período chuvoso, em dezembro de 2013. Os parâmetros analisados foram os constituintes iônicos (F<sup>-</sup>, Cl<sup>-</sup>,…
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Gold has been exploited intensively in the Brazilian Amazon during the past twenty years, where Hg used in amalgamating the gold has caused abnormal Hg concentrations in waterways. Particular attention to the Madeira River has been given... more
Gold has been exploited intensively in the Brazilian Amazon during the past twenty years, where Hg used in amalgamating the gold has caused abnormal Hg concentrations in waterways. Particular attention to the Madeira River has been given since 1986 because it is the largest tributary of the Amazon River and the gold mining was officially allowed on a 350-km sector
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Mercury is a major pollutant in the Amazon River system, and its levels in fish and human hair are usually above the limit recommended by health agencies. The objective of this study was to analyze the methylmercury (MeHg) concentration... more
Mercury is a major pollutant in the Amazon River system, and its levels in fish and human hair are usually above the limit recommended by health agencies. The objective of this study was to analyze the methylmercury (MeHg) concentration in fish tissue from the Roosevelt River. The river's water velocity, depth, pH, temperature, electrical conductivity, dissolved oxygen and substrate type were measured, and fifty specimens distributed in 14 fish species were collected. A total of 64.3% of the sampled species were of the order Characiform and 71.4% of the species were carnivores. Fifty percent of the species had MeHg concentrations above threshold limit (Hg-T 0.5 mg kg-1) established for food by the World Health Organization. Cichla monoculus had the highest value of MeHg (2.45 mg kg-1). The MeHg concentration in fish varied according to dietary habits. The study also found bioaccumulation of MeHg in fish tissue in the following descending order: carnivorous > detritivorous > frugivore. Low significant correlations were found between fish weight or length and MeHg. Further studies on MeHg contamination are recommended in tissues of fish consumed in human riverine communities in the Roosevelt River Basin. Bioacumulação de metilmercúrio em tecidos de peixes no rio Roosevelt, Sudoeste da Bacia Amazônica RESUMO O mercúrio tem sido um dos principais poluentes no sistema do rio Amazonas, cujos níveis em peixes e cabelo humano são geralmente acima dos limites recomendados pelos órgãos de saúde. O objetivo deste estudo foi analisar a concentração de metilmercúrio (MeHg) em tecidos de peixes do rio Roosevelt. Os atributos medidos do rio foram a velocidade da água, profundidade, pH, temperatura, condutividade elétrica, oxigênio dissolvido, e profundidade. Cinquenta espécimes distribuídas em 14 espécies de peixes foram coletadas. A ordem Characiformes representou 64,3% das espécies amostradas e os carnívoros representaram 71,4%. Cinquenta por cento das espécies apresentaram concentrações de MeHg acima do limite (Hg-T 0,5 mg kg-1) estabelecido para os alimentos pela Organização Mundial de Saúde. Cichla monoculus apresentou o maior valor de MeHg (2,45 mg kg-1). A concentração de MeHg variou por hábitos alimentares. Este estudo demonstrou bioacumulação de MeHg em tecidos de peixes, como segue: carnívoros > detritívoros > frugívoros. Baixas correlações entre peso ou cumprimento de peixe e MeHg foram encontradas. Recomenda-se um estudo mais aprofundado de contaminação do MeHg em tecidos de peixes consumidos nas comunidades ribeirinhas na bacia do rio Roosevelt. Palavras-chave: biomagnificação, contaminação química, poluição aquática.
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Sediment cores from lakes located in the Pantanal Swamp, Central Brazil were analysed for the distribution of mercury released by the local gold mining. Atmospheric transport is the only pathway of mercury contamination of these remote... more
Sediment cores from lakes located in the Pantanal Swamp, Central Brazil were analysed for the distribution of mercury released by the local gold mining. Atmospheric transport is the only pathway of mercury contamination of these remote lakes. Mercury concentrations were higher at the surface of sediments (62 to 80 ug.kg-1) decreasing to values of 20 to 30 ug.kg-1 in deeper