The emission fluxes and the distribution of dissolved methane (CH4) and carbon dioxide (CO2) were... more The emission fluxes and the distribution of dissolved methane (CH4) and carbon dioxide (CO2) were determined for 11 sampling stations in two hydroelectric reservoirs (flooded since 1978 and 1993) located in the James Bay territory of northern Québec. The measured benthic fluxes for the two greenhouse gases were found to be either higher or similar to those determined at the
The geochemical study of surface sediments (vertical profiles of 30–80 cm) from lentic ecosystems... more The geochemical study of surface sediments (vertical profiles of 30–80 cm) from lentic ecosystems of the Tapajós River permit the observation of environmental changes responsible for the mercury contamination of aquatic systems exploited by the human riverine population. The Arapiuns and Amazon rivers are compared. Measurements of mercury, textural indicators (water content and dry density), mineralogic indicators (iron and aluminum
Archives of Environmental & Occupational Health, Sep 1, 2006
The authors present the results of an experiment in which they explored the role of tea in human ... more The authors present the results of an experiment in which they explored the role of tea in human metabolic processing of methylmercury (MeHg) from fish consumption. The experiment involved 50 scientists from the Collaborative Mercury Research Network (COMERN) who agreed to eat fish for 2 daily meals for 3 consecutive days. Half of the participants also drank 6 cups of tea daily, starting a week before and continuing through the experiment. The authors calculated the total amount of MeHg that each participant ingested from (1) the measured mercury (Hg) level in fish and (2) the quantity of fish eaten, and compared it with the total increases of Hg and MeHg levels in participants' blood. Results indicated that the control group metabolized roughly 100% of the available fish MeHg, whereas the tea-exposed group showed blood levels of MeHg at more than 40% than that available in the fish provided, suggesting that an external MeHg pool supplied part of the measured blood MeHg increase. The authors conclude that tea may accelerate the enterohepatic MeHg cycle and contribute to a temporary bioamplification of MeHg in the bloodstream.
The current development model of the agricultural sector in Brazil has considerable potential to ... more The current development model of the agricultural sector in Brazil has considerable potential to cause negative environmental impacts, including the pollution of aquatic ecosystems, as it may contribute to the intensification of erosive processes on deforested soils, to the leaching of eroded materials, and to the consequent siltation of waterbodies with soil particles containing environmental pollutants. We aimed at assessing the occurrence of several pesticide residues in aquatic ecosystems located near large soybean crops of the Santarém region, in the eastern Brazilian Amazon. By adopting a methodological approach combining analytical and environmental chemistry, 10 groundwater samples, 18 surface water, and 15 drainage bottom sediment samples, all collected in streams from the study region, were analyzed. The study included a distributed sampling procedure covering an area of approximately 20 km 2 , and the potential risks of the studied pollutants and their implications for the region were likewise examined and critically discussed. Results indicate that active ingredients such as the herbicides atrazine and metolachlor were detected in the waters, as well as organochlorine insecticides such as DDTs and endosulfan. The spatialization of the resulting pesticide concentrations in water suggests that the contamination would not be punctual but would rather come from various point sources. As for the sediments,
The emission fluxes and the distribution of dissolved methane (CH4) and carbon dioxide (CO2) were... more The emission fluxes and the distribution of dissolved methane (CH4) and carbon dioxide (CO2) were determined for 11 sampling stations in two hydroelectric reservoirs (flooded since 1978 and 1993) located in the James Bay territory of northern Québec. The measured benthic fluxes for the two greenhouse gases were found to be either higher or similar to those determined at the
The geochemical study of surface sediments (vertical profiles of 30–80 cm) from lentic ecosystems... more The geochemical study of surface sediments (vertical profiles of 30–80 cm) from lentic ecosystems of the Tapajós River permit the observation of environmental changes responsible for the mercury contamination of aquatic systems exploited by the human riverine population. The Arapiuns and Amazon rivers are compared. Measurements of mercury, textural indicators (water content and dry density), mineralogic indicators (iron and aluminum
Archives of Environmental & Occupational Health, Sep 1, 2006
The authors present the results of an experiment in which they explored the role of tea in human ... more The authors present the results of an experiment in which they explored the role of tea in human metabolic processing of methylmercury (MeHg) from fish consumption. The experiment involved 50 scientists from the Collaborative Mercury Research Network (COMERN) who agreed to eat fish for 2 daily meals for 3 consecutive days. Half of the participants also drank 6 cups of tea daily, starting a week before and continuing through the experiment. The authors calculated the total amount of MeHg that each participant ingested from (1) the measured mercury (Hg) level in fish and (2) the quantity of fish eaten, and compared it with the total increases of Hg and MeHg levels in participants' blood. Results indicated that the control group metabolized roughly 100% of the available fish MeHg, whereas the tea-exposed group showed blood levels of MeHg at more than 40% than that available in the fish provided, suggesting that an external MeHg pool supplied part of the measured blood MeHg increase. The authors conclude that tea may accelerate the enterohepatic MeHg cycle and contribute to a temporary bioamplification of MeHg in the bloodstream.
The current development model of the agricultural sector in Brazil has considerable potential to ... more The current development model of the agricultural sector in Brazil has considerable potential to cause negative environmental impacts, including the pollution of aquatic ecosystems, as it may contribute to the intensification of erosive processes on deforested soils, to the leaching of eroded materials, and to the consequent siltation of waterbodies with soil particles containing environmental pollutants. We aimed at assessing the occurrence of several pesticide residues in aquatic ecosystems located near large soybean crops of the Santarém region, in the eastern Brazilian Amazon. By adopting a methodological approach combining analytical and environmental chemistry, 10 groundwater samples, 18 surface water, and 15 drainage bottom sediment samples, all collected in streams from the study region, were analyzed. The study included a distributed sampling procedure covering an area of approximately 20 km 2 , and the potential risks of the studied pollutants and their implications for the region were likewise examined and critically discussed. Results indicate that active ingredients such as the herbicides atrazine and metolachlor were detected in the waters, as well as organochlorine insecticides such as DDTs and endosulfan. The spatialization of the resulting pesticide concentrations in water suggests that the contamination would not be punctual but would rather come from various point sources. As for the sediments,
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