Temporal Changes in Toxic Contamination at the Carillon Sampling Station Deforestation, urban development, industrial activity and farming have generated heavy loads of toxic substances that have found their way into rivers and lakes over the last century. These inputs have contributed to degrading the water quality in the Ottawa River basin and have attendant impacts on the quality of the water and ecosystem of the St. Lawrence River.
Phosphorus at the Mouths of Lake Saint-Pierre Tributaries Between 2005 and 2010, the average concentrations of phosphorus measured at the mouths of the Saint-François and Nicolet rivers oscillated around values corresponding to a eutrophic environment. However, it was at the mouth of the Yamaska River that the highest concentrations were observed and where conditions were hypereutrophic.
Sediment Quality of the St. Lawrence River According to studies by Environment Canada, surface sediments in the St. Lawrence River are generally less contaminated than they were 20 years ago as a result of effluent treatment measures. Yet, concentrations of some substances have remained unchanged or are even increasing.
Benthic Invertebrates: New Indicators for Monitoring the State of Lake Saint-Pierre Benthic invertebrate communities occurring in riverine zones are exposed directly to the stress of pollution and the prevailing conditions of the aquatic environment. Because their distribution and composition are influenced by the characteristics of the aquatic ecosystem in which they live, benthic communities may prove to be useful indicators for assessing the state of Lake Saint-Pierre
Effect of Water Level on Contaminant Transport Contaminant concentrations in the St. Lawrence River near Quebec City are influenced by both the quantities released to the aquatic ecosystem and by the origin of the water masses that carry them, including the Great Lakes water mass.
Monitoring the Water Quality of the St-Lawrence Ten water quality sampling stations being operated in Quebec by Environment Canada serve to assess the level of water contamination by registering seasonal and interannual fluctuations as well as long-term trends in contaminant concentrations.
Sediment Dynamics in the St. Lawrence River Based on the characteristics of the hydrodynamic regime, it is possible to define zones of potential erosion, transport of solid matter and sedimentation. These zones change according to seasons, flows, tides, winds and ice. Facts and figures on sediment inputs in the St. Lawrence are shown.
The St. Lawrence River and Climate Warming In the opinion of some experts, a temperature increase of 2 to 4°C could lower the average flow from Lake Ontario by 24%. Lake Ontario is the major source for the St. Lawrence River, and a decrease in flow of this magnitude could result in a 1-metre drop in water levels in some areas of the St. Lawrence.
The Use of Algae for Assessment of Sediment Quality Research scientists at Environment Canada have developed the algal solid-phase assay for diagnosing toxicity in sediment contaminated by various classes of chemicals, including hydrocarbons. ASPA has certain advantages over conventional bioassays.
Wastewater as a Food Source in the Ecosystem When we think of urban wastewater, its negative environmental impacts generally spring to mind. For example, the enrichment of the aquatic environment by certain nutrients contained in wastewater can lead to a proliferation of algae and, ultimately, the eutrophication of the site. Yet, according to the results of a study conducted by Environment Canada in collaboration with research scientists at McGill University, urban wastewater can also be a food source for aquatic organisms.