Des scientifiques ont analysés la chair de poissons pêchés dans une des rivières les plus sauvages du Canada, et ont été surpris de se rendre compte que même dans des régions aussi éloignées, la pollution de la civilisation humaine contamine la faune aquatique.
De plus, on suspecte que les changements climatiques sont la raison pour laquelle la concentration de mercure, des BPC et du DDT va en augmentant. Depuis une vingtaine d'années, les BPC ont augmenté par 6 fois, le DDT 3 fois, et le mercure 1,6 fois dans la chair de la lote.
La hausse de température dans les régions nordiques augmentent les activités biologiques, ce qui expliquerait que ces substances pourtant moins présentes dans les régions plus tempérées se retrouvent davantage incorporées dans la chaîne alimentaire dans les régions les plus froides.
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"Mackenzie River's fish contaminated with dangerous toxins: scientists
Scientists studying burbot in the Mackenzie River, one of the country's most pristine rivers, have been surprised to discover that mercury, PCBs and DDT in the fish are rising rapidly, a finding they say is linked to climate change.
The increase in the amount of harmful chemicals has been huge. In the period from the mid-1990s to 2008, PCBs have risen up to six times, DDT by three times, and mercury by 1.6 times in the burbot, a delicacy in the north described as tasting like a freshwater lobster.
The discovery of the rising tally of harmful pollutants in fish in such a remote area of the Northwest Territories was doubly unusual for researchers because contaminant levels should have been going down, based on the declining amount of the chemicals in the general environment. Both PCBs and DDT have been banned for at least the past quarter-century, while mercury concentrations have generally been stable or falling slightly.
Dr. Stern said researchers do not know whether contaminants are increasing in fish elsewhere. The burbot were caught near Fort Good Hope, where temperatures have risen an average of 1.9 degrees since the early 1970s. But he has been part of a wider research effort that has found strong hints that warming is driving a rapid increase in biological activity in the north, with the potential to increase harmful chemical residues in animals."
Excerpts from article written by Martin Mittelstaedt published in The Globe and Mail here: http://www.theglobeandmail.com/news/national/mackenzie-rivers-fish-contaminated-with-dangerous-toxins-scientists/article1462248/
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