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NEWSLETTER |
Le Fleuve is
published jointly by St. Lawrence Vision 2000 partners. Text This Newsletter is also available
in PDF
Version.
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Several federal and Quebec departments have joined with the private sector in establishing environmental emergency response teams to deal with oil spills in the St. Lawrence. Furthermore, to improve the efficiency of clean-up operations in oil-contaminated beds of aquatic vegetation, Fisheries and Oceans Canada, the U. S. Environmental Protection Agency, France’s Centre de documentation, de recherche et d'expérimentations sur les pollutions accidentelles des eaux (documentation, research and experimentation centre on accidental spills in aquatic environments) and Environment Canada have joined forces to create a new tool for cleaning up oil spills, based on the use of soil bacteria. The project is part of the Navigation component of St Lawrence Vision 2000, one of the objectives of which is to improve management of the environmental risks and dangers associated with navigation in keeping with the goal of sustainable development.
Every year, there are roughly 140 accidental oil spills in the St. Lawrence. Notwithstanding the best efforts of emergency response teams deployed to the scene of a spill, sometimes some of the oil reaches the shore. At this point, specialists can use a number of different techniques to recover the oil. For example, if the spill affects a sandy beach, contaminated sediments can be collected mechanically and then treated to eliminate the contaminants. If the spill occurs on a rocky coast, the oil can be scraped off and the rocks cleaned with high-pressure sprays of hot water. In some cases, however, these methods may be more damaging to the environment than the oil spill itself.
Spills may also affect beds of aquatic vegetation, which are abundant along the St. Lawrence and are highly productive habitats for a number of wildlife species, which use them for breeding, feeding and resting. The previously described techniques are not suitable for these beds and emergency response teams can only seek to recover the oil floating on the surface of the water or take the more radical step of cutting the contaminated plants and burning the oil.
Soil bacteria, valuable helpers The best solution for restoring oil-contaminated aquatic beds may lie in the use of naturally occurring micro-organisms in the soil. In fact, the sediments in which aquatic vegetation grows are already inhabited by oil-eating bacteria able to feed on hydrocarbons. Under natural conditions, however, the development of these bacteria is often limited by environmental factors. Insufficient nutrients or oxygen, for example, may hinder these bacteria’s natural ability to break down hydrocarbons, thus reducing their efficiency.
Experiments on freshwater bioremediation Since these bioremediation techniques have already been proven effective in saltwater environments, researchers at Fisheries and Oceans Canada and Environment Canada have begun a project to test this technique in fresh water. The U.S. Environmental Protection Agency and France’s Centre de documentation, de recherche et d'expérimentations sur les pollutions accidentelles des eaux are also participating in the project.
In some of the study plots, the aquatic plants were cut back regularly to determine the effect of the presence of plants on oil decomposition rates. In other plots, fertilizer was applied beforehand to provide added nitrogen and phosphorous, nutrients that promote bacterial growth and accelerate the rate of decomposition. Nutrients not only have a direct effect on bacterial growth but also promote the growth of aquatic plants. Aquatic plants promote bacterial growth by releasing added oxygen into the soil, by excreting organic compounds into sediments and by providing micro-organisms with a support on which they can multiply.
Promising preliminary results Immediately after the spill, researchers began to collect sediment samples from the plots to measure hydrocarbon content and quantify the presence of oil-degrading bacteria. Analyses were also carried out in Canadian and U. S. laboratories to assess residual toxicity levels in sediments, which are indicative of the effectiveness of bacteria in decomposing the many toxic chemicals found in hydrocarbons.
In addition, tests were carried out on animals placed in contact with contaminated sediments to determine if exposure hindered their development. More samples will be collected in the spring of 2000. A number of additional analyses will also be required before the final results are available. In the meantime, preliminary results suggest that the American bulrush (Scirpus americanus), the most widespread aquatic plant at the study site, tolerates oil spills fairly well. The results also suggest that growth rates in this species, which are indicative of the level of habitat restoration, can be increased simply by adding fertilizers similar to those used in agricultural environments. If the results from the study at Sainte-Croix-de-Lotbinière prove conclusive, the method developed could be used for spills in beds of freshwater aquatic vegetation in the St. Lawrence between Cornwall and the île d'Orléans. This will give emergency response teams a new tool to use in restoring these productive but vulnerable habitats. For more information: Kenneth
Lee, Section Head Gilles-H.
Tremblay, chemical oceanographer
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Consequently,
bioremediation techniques aim to provide optimal conditions
for bacteria after a spill, so that the bacteria can work as
efficiently as possible to eliminate the oil. Researchers working
to perfect these promising techniques are therefore focussing
on determining limiting factors on the optimal growth of bacteria
and establishing methods to accelerate the natural restoration
process by promoting bacterial growth.
The
tests, which began in June 1999, are being conducted in a bulrush
marsh on the eastern end of the village of Sainte-Croix-de-Lotbinière,
which is located on the south shore of the St. Lawrence. Researchers
created a controlled oil spill in a limited area of the aquatic
bed, making up 5% of the total area of the intertidal zone at
Sainte-Croix. A total of 192 L of crude oil was deliberately
spilt at low tide in 16 well-isolated study plots. An emergency
response team was on hand to assist the scientists in the event
that the oil spread beyond the study plots during high tide.
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 The purpose of this newsletter is to provide recent information on projects and activities surrounding the implementation of the St. Lawrence Vision 2000 Action Plan.
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Les
Publications du Québec announces the sixth title in its
popular series, Aux limites de la mémoire, entitled
"Naviguer sur le fleuve au temps passé, 1860 –
1960." It was written by Alain Frank, a ethnologist
specializing in maritime history.
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