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Tuesday, 22 April 2008

The excellent blue mussels that so many restaurants serve with a steamed lemon allow scientists at Environment Canada's Atlantic region to measure toxic chemical contaminants in the brackish waters of the Gulf of Maine.    Mussels are indicators ideals not only because they are numerous and easy to pick up, but also because they are nourished by pumping large volumes of water through their system, thus exposing their tissue contaminants. As the mussels remain at roughly the same place all their lives, scientists can determine the quality of water in a specific area simply by analyzing the concentration of contaminants in the tissues of indigenous mussels.    The Gulf of Maine is one of the most productive ecosystems in the world. Stretching from Cape Sable, Nova Scotia, to Cape Cod, in Massachusetts, including the Bay of Fundy and the Georges Bank, it sustains a broad range of algae, herbs of salt marshes, phytoplankton and marine mammals, including several species of commercial importance. Unfortunately, over the past 50 years, the increase in human population and land development have seriously increased air pollution and effluent into the environment estuarine and coastal Gulf. In particular, persistent toxic substances are causing great concern, such as polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), pesticides, dioxins, furans and trace metals, because they are in bioaccumulent tissue and can grow up biologically dangerous levels in the food chain. To protect the health of the ecosystem species, including humans who consume its seafood, the Gulf of Maine Council on the Marine Environment has set up monitoring program transborder Gulfwatch. Since 1991, scientists from Environment Canada and other members of the Supervisory Committee of Gulfwatch go on the shores of the Gulf in the autumn to pick by hand about 200 molds each sampling site - mostly located in the 'mouth of river basins and the coastal drainage systems. Samples are indigenous mussels, but some foreign own molds are also collected to evaluate the effects of short-term exposure to the waters of the Gulf. It collects samples annually in five sites stallions in Nova Scotia, New Brunswick, Maine, New Hampshire and Massachusetts, while 56 other sites are audited every three years in rotation.    The results showed that the concentrations of toxic organic contaminants and money increase from north to south. The concentrations of lead and chromium amounted to sites in Massachusetts, New Hampshire and Maine. Others trace metals are relatively evenly distributed in the Gulf. In general, the concentrations of contaminants correspond to the population density, flexibility and distance of sources of contamination known.    In very few sites concentrations of contaminants in the tissue of mussels they exceed the threshold Canadian or American tolerance for human health. By contrast, some of the levels required to assess more fully the risks to human health and several exceeded concentrations considered dangerous for birds and other animals. An examination of changes in data over time shows that the levels of contamination at most sites falling standards or have no detectable change.    The institutes Canadian and American government use this information for a variety of purposes: to develop plans and policies for environmental management, criteria for industrial discharge permits, and measures for pollution control; to assess the safety of seafood and the effects of spills and other events on the water quality. On the other hand, aquaculture shellfish and fish consult data Gulfwatch to find clean zones to establish facilities for harvesting and culture.

Last Updated ( Monday, 30 June 2008 )

 

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