EVALUATION AND APPLICATION OF A FUGACITY MODEL TO EXPLAIN THE PARTITIONING OF CONTAMINANTS IN THE ST. LAWRENCE RIVER VALLEY     

Koprivnjak  Jean-François  Poissant  Laurier 《Water, air, and soil pollution》1997,97(3-4):379-395

A fugacity-based model to explain the partitioning of contaminants in the environment is evaluated. Using emission inventories, air and water concentrations predicted by the model for the southwestern Québec region generally agree with field data for phenanthrene,α-HCH, lindane, and DDT. For pyrene, air concentrations are in agreement but water concentrations were in error by a factor of nearly 20. There is also a possibility for using the model to predict emissions from known air and water concentrations. The model was run over 120 times each for phenanthrene, HCB, and lindane while randomly varying the input parameters each time. A Principal Components Analysis and a partial correlation analysis indicate that certain input parameters are more important for some compounds than for others and that log K _ow is the physical-chemical property of greatest importance.  相似文献   

Ecotoxicity of Snowpack Collected from Selected Sites in Québec, Canada     

François Gagné  Laurier Poissant  Christian Blaise 《Water, air, and soil pollution》2009,201(1-4):121-133

Sampling was conducted at seven sites on, and at varying distances adjacent to, the Island of Montréal (Québec, Canada), and as far as 1,100 km away in Northern Québec, to explore the hazard potential of snowpacks in remote, rural, and urban environments. Ecotoxic effects of melted snow were ascertained with a suite of small-scale bioassays representing several aquatic taxonomic groups (bacteria, micro-algae, micro-invertebrates, fish liver cells) as well as with biomarker measurements determined with a rainbow trout primary hepatocyte (RTPH) assay. Bioassays undertaken with the cnidarian Hydra attenuata and RTPH cell assays, and to a lesser extent with the micro-alga Pseudokirchneriella subcapitata, proved particularly sensitive to infer the presence of bio-available pollutants in snow samples collected from all sites, thereby suggesting their contamination (at least) via atmospheric sources. Furthermore, biomarker responses indicated that snow samples presumably included metals (free Zn biomarker), organics (CYP 1A1 biomarker), estrogens (alkali-labile phosphate biomarker) as well as chemicals capable of causing oxidative stress (LPO biomarker), depending on the site being considered. Overall, effects data acquired during this preliminary investigation on the ecotoxicity of snowpacks submit that adverse impact toward aquatic biota is conceivable at some sites during spring meltdown. Because snow has a recognized affinity for sequestering solids and contaminants of atmospheric origin, future studies aimed at identifying sources and chemicals implicated in observed effects are legitimate endeavors.  相似文献   

Analysis of rainwater quality variability on mesoscale: Case of the montreal island     

Laurier Poissant  Pierre Pagé  Patrick Béron 《Water, air, and soil pollution》1994,73(1):363-373

During summer of 1989, a network for the analysis of spatial variability of rainwater quality was operated on Montréal Island. Six bulk samplers distributed on the territory were used for this purpose. A total of 97 storm-station events have been analyzed for pH, conductivity, Total Organic Carbon, nitrate, sulphate, calcium and magnesium. A canonical discriminant analysis shows that as a whole, there is no statistically significant discrimination between stations. However, Tukey's test for means shows that mean pH is significantly different between downtown and peripheric stations. The pH is higher in downtown. Finally, a variance analysis shows that variations with respect to time are greater than those on a spatial basis. Thus, the Montréal Island can be considered as spatially homogeneous for most rainwater quality parameters.  相似文献   

Mercury Partitioning in Surface Sediments of the Upper St. Lawrence River (Canada): Evidence of the Importance of the Sulphur Chemistry   总被引：1，自引：0，他引：1  

João Canário  Laurier Poissant  Nelson O`Driscoll  Jeff Ridal  Tania Delongchamp  Martin Pilote  Philipe Constant  Jules Blais  David Lean 《Water, air, and soil pollution》2008,187(1-4):219-231

An intensive survey of mercury speciation was performed at a site on the Upper St. Lawrence River near Cornwall, Ontario, Canada with a history mercury contamination in sediments. Surface sediments were collected every 1.50 h. Total mercury (Hg_total), methylmercury (MeHg), organic carbon, inorganic and organic sulphur were determined in the solid fraction. Dissolved Hg_total, MeHg and dissolved organic carbon (DOC) were measured in pore waters. Concentrations of Hg_total in the upper layers (first 5 cm) were high, ranging from 1.42 to 25.8 nmol g^?1 in solids and from 125 to 449 pM in pore waters. MeHg levels were also high, ranging from 4.34 to 34.1 pmol g^?1 in solids and from 40 to 96 pM in pore waters. This amounts to up to 1.4% of Hg_total present as MeHg in solids and 64% in pore waters. A daily pattern for Hg_total was observed in the solid fraction. The MeHg distribution in solids and pore waters was not correlated with Hg_total or DOC_, suggesting that the concentrations of MeHg are probably more influenced by the relative rates of methylation/demethylation reactions in the sediment–water interface. Acid volatile sulphide levels and DOC were inversely correlated with organic sulphur (S_org) levels suggesting that both parameters are involved in the rapid production of S_org. A positive correlation was also observed between Hg_total and S_org in solids (R?=?0.87, p?<?0.01) illustrating the importance of organic sulphur in the retention and distribution of Hg in the solid fraction of the sediments. The results suggest that variations of Hg_total concentrations in Upper St. Lawrence River surface sediments were strongly influenced by the formation/deposition/retention of organic sulphur compounds in the sediment–water interface.  相似文献   

Disentangling the effect of size and competition: a growth model for Aucoumea klaineana     

Nestor Laurier Engone Obiang  Alfred Ngomanda  Lee J. T. White  Kathryn J. Jeffery  Éric Chézeaux  Nicolas Picard 《Annals of Forest Science》2013,70(3):241-249

• Context Okoume (Aucoumea klaineana) is the most important timber species in Gabon, while being classified as vulnerable in the IUCN red list. Thousands of growth measurements for this species have been performed since the 1950s but, because of a lack of integrated analysis, did not bring a consistent view on its growth pattern.
• Aims This study aims at disentangling the effects of tree size and local competition on tree growth.
• Methods A growth model was fitted for okoume, using data from seven sites in Gabon and Congo. The growth model was designed to be useful for forest management, which means that it relied on variables that could be computed using forest inventory data.
• Results A lognormal growth model with a negative response to stand basal area was selected. A significant residual site effect on growth was found, with a slower growth in the sites near the border of the natural range of okoume than in the sites far from it.
• Conclusion Growth strongly responded to local stand attributes such as tree density and basal area. Growth decrease with stand age in monodominant okoume stands was correctly predicted, although tree age was not incorporated into the model.

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Toxicity survey of Canadian Arctic marine sediments     

João Canário  Laurier Poissant  Martin Pilote  Christian Blaise  Philippe Constant  Jean-François Férard  François Gagné 《Journal of Soils and Sediments》2014,14(1):196-203

Purpose

This paper reports a toxicity survey of Canadian Arctic marine sediments. During the Amundsen scientific cruise, eight sites distributed across the Canadian Arctic and sub-Arctic regions were selected to highlight sensitive areas affected by either atmospheric deposition, ocean current, river drainage, or anthropogenic activities. As part of the Canadian-led ArcticNet research program, this study aims to monitor and to better understand potential changes likely to impact the Arctic.

Materials and methods

Surface sediments were investigated with bioanalytical tests to assess sediment toxicity. Testing of sediment elutriates was undertaken with the ARTOXKIT M, Microtox liquid phase (MLPA), and ROTOXKIT M toxicity assays, while whole sediment testing was carried out with the Microtox solid phase assay (MSPA) toxicity test procedure. Sediment mercury (Hg) content was also determined in each sample since Hg transport and toxicity is specifically an important issue in the Arctic and is generally a key indicator of the pollution status in many aquatic ecosystems.

Results and discussion

Based on bioassay results and sediment granulometric criteria, these Arctic sediments must be considered nontoxic. However, based on MSPA half maximal inhibitory concentrations (IC50s) and/or MLPA threshold effect concentration (TEC) values, some degree of toxicity may be measureable particularly in the sediments located in southern and northeast Hudson Bay. The Hudson Bay watershed drains 30% of Canadian rivers and extends to northern USA. Despite the large Hg concern in the Arctic, the input of local or long-range Hg sources does not appear to be a contributing factor to sediment toxicity.

Conclusions

These initial results are valuable in that they set baseline quality levels for these sediments as of 2005. As such, future comparisons can be made to assess temporal and spatial trends. Human activity and climate change is expected to impact these regions in the future, resulting in further reduction of sea ice extent, access to new Arctic seaways, and drilling associated with the exploitation of natural resources.  相似文献