排序方式： 共有5条查询结果，搜索用时 234 毫秒
1
1.
Roulet M. Lucotte M. Farella N. Serique G. Coelho H. Sousa Passos C. J. de Jesus da Silva E. Scavone de Andrade P. Mergler D. Guimarães J.-R. D. Amorim M. 《Water, air, and soil pollution》1999,112(3-4):297-313
Three Hg sources were characterised and mass balance calculations were used to determine their relative contributions to the contamination of the Amazonian environment. About an order of magnitude more Hg is emitted to the atmosphere by goldmining activity than by the burning of forest biomass. However, anthropogenic atmospheric Hg cannot account for the high Hg burdens found in terrestrial ecosystems: deposition of Hg from goldmining sources is estimated to account for less than 3% of the Hg present in the surface horizons of soils. We propose that erosion of deforested soils following human colonization constitutes a major disturbance of the natural Hg cycle. Deforestation thus increases soil Hg mobilisation by runoff, which may explain the increase of Hg burdens in Amazonian aquatic ecosystems in newly colonized watersheds. 相似文献
2.
Alexandre Joly Jean Lambert Claude Gagnon Greg Kennedy Donna Mergler Ariane Adam-Poupart Joseph Zayed 《Water, air, and soil pollution》2011,219(1-4):263-270
Methylcyclopentadienyl manganese tricarbonyl (MMT) was used between 1990 and 2003 as an antiknock agent and as an octane booster in Canadian unleaded gasoline. Its combustion leads to Mn emissions. The objective of this research was to examine the variations in atmospheric Mn in Montreal (Canada) from 2001 to 2007, covering the period prior (2001?C2003) to and following (2005?C2007) MMT use. Three sampling stations were selected because of their proximity to roads with widely differing and well-known traffic patterns. Filters from 2001 to 2007 were obtained from the Montreal Urban Community. The first sample of each month was selected, and Mn analysis was performed by neutron activation analysis. Total suspended particulates (TSP) was calculated by weighing the filters before and after dust collection. Results show a significant decrease of Mn over time at each station, whereas TSP decreased significantly in two stations. Comparing atmospheric Mn during and after the period of use of MMT 2001?C2003 vs 2005?C2007 showed a significant decrease at all stations. For TSP, only one station showed borderline significant decline between these two periods. Overall, between the two periods, Mn and TSP decreased by 39% and 17%, respectively. These data suggest that the combustion of MMT led to an increase of airborne Mn of approximately 22%. These findings should help in decision-making processes concerning the use of MMT in gasoline in other countries. 相似文献
3.
Trophic Structure and Bioaccumulation of Mercury in Fish of Three Natural Lakes of the Brazilian Amazon 总被引：2，自引：0，他引：2
D. Sampaio Da Silva M. Lucotte M. Roulet H. Poirier D. Mergler E. Oliveira Santos M. Crossa 《Water, air, and soil pollution》2005,165(1-4):77-94
The bioaccumulation of mercury by fish was studied in three natural lakes lining the Tapajós River, Brazilian Amazon. The Hg content variations are also reported between the rainy and the rising water seasons. Position of fish in the food chain and the source of carbon at the base of the food chain were determined using nitrogen and carbon stable isotopes ratios respectively. During the two seasons, the effect of the Hg biomagnification between the non-piscivorous and piscivorous fish of the three lakes is observed. The correlation between the mercury concentrations and the nitrogen isotopic ratios suggests that the fish mercury content variability is connected with the trophic position and size. Aside from classic observations on mercury biomagnification by certain species of fish (i.e. contents increase with size or trophic status), novel results were revealed as well, such as some species decrease of mercury contents with size of fish. Aquatic organisms in the Amazon are adapted to the complexity of trophic webs coupled with changes in environmental variables, depending on the location and/or the season, which results in a wide range of mercurial contamination among the Tapajós ichthyofauna. 相似文献
4.
5.
Lebel J. Roulet M. Mergler D. Lucotte M. Larribe F. 《Water, air, and soil pollution》1997,97(1-2):31-44
The incorporation of mercury into the food chain and its assimilation by humans is a universally recognized potential health hazard. Studies carried out in the Amazon Basin have shown that mercury (Hg) is present in fish and in humans, however, the relation between fish diet and human exposure has received limited attention in this region. The present study focused on a small village, Brasília Legal (3°59′00″S, 55°30′00″W), situated on the banks of the Rio Tapajós. A total of 181 fish (40 species) were captured in March, 1995 and analysed for Hg concentration. Of these, 132 fish were among species consumed by the population during the rainy season (mid-November to mid-May) and the dry season (mid-May to mid-November). Wide intra- and inter-species variations in Hg concentrations were observed. Thirty four fish (25.8% of the consumed species) had levels above 0.5 μg/g Hg fresh weight; all were among the piscivorous and omnivorous species. Hair Hg concentrations (HHg), showed that villagers with a high fish diet (n=31; median HHg=16.1 μg/g) and mixed fish diet (n=36; median HHg=14.8 μg/g) had significantly higher HHg concentrations compared to the low fish diet group (n=29; mean HHg=7.8 μg/g). Time series function of HHg measurements, made for 26 persons with over 24 cm of hair, revealed sinusoidal variations, with peaks during the rainy season and troughs during the low water period, paralleling the seasonal shift in dietary habits. Piscivorous and omnivorous fish species, with higher mercury levels, are the main component of the fish diet during the rainy season, while herbivorous fish species predominate during the dry season. Preventive actions should take into account the risk to human health, particularly for fetal and neonatal development, the importance of fish in the riparian diet, the wide intra- and inter-species variations in mercury content and seasonal fluctuations in diet. 相似文献
1