Les rivières les plus polluées d'Europe sont en France
Des chercheurs de l’université de Coblence, en Allemagne, ont analysé la qualité de l’eau dans plus de 4000 points de prélèvements en Europe et mesuré la présence de 223 produits chimiques. Dans 14% des sites, la concentration est potentiellement mortelle et dans 42% des sites ils pourraient causerdes effets à long terme. La France et notamment les rivières qui se jettent dans la mer du Nord est particulièrement concernée.
Comme le rappelait Sud-Ouest récemment, « les zones les plus touchées sont les grandes régions céréalières, maraichères ou viticoles : nord de la France, Bassin parisien, Sud-Ouest, amont du Rhône et Martinique. En 2011, sur les 176 secteurs hydrographiques (découpage géographique par bassins versants des rivières) surveillés en France métropolitaine, 63 présentaient une concentration moyenne annuelle supérieure à 0,5 microgramme par litre, seuil au-delà duquel l’eau est jugée “ impropre à la consommation humaine ”. »
http://rue89.nouvelobs.com/2014/06/22/devinez-sont-les-rivieres-les-plus-polluees-deurope-253118
The most polluted rivers and streams in Europe
Europe's rivers are awash with organic chemicals that can kill or subtly harm aquatic life, according to the most extensive survey yet of pollution in the continent's major river basins.
Toxicologists contacted by New Scientist welcomed the study, but point out that the researchers may have exaggerated the risks by choosing to define relatively low levels of chemicals as harmful. Such small concentrations might well affect animal populations, but by themselves would probably not be enough to cause a population to collapse.
Ralf Schäfer of the University of Koblenz-Landau in Landau, Germany, and colleagues analysed water quality data from over 4000 monitoring sites and measured concentrations of 223 different organic chemicals.
They discovered that at 14 per cent of sites, the concentrations of chemicals could potentially be lethal. The map below illustrates this. The colours indicate the fraction of sites in each river basin that exceed the lethal risk threshold.
What's more, 42 per cent of the sites may have subtler problems. The concentrations of organic chemicals were not immediately lethal, but could cause longer-term damage, such as impacts on breeding or increased vulnerability to disease.
All previous studies had focused on much smaller areas, such as individual streams. "The most important message from our study is that chemical pollution is a large-scale, not just local problem," says Schäfer.
The risk appears to be highest in central European and French rivers, especially those that empty into the North Sea from the Netherlands and Belgium. UK aquatic life also faces chronic risks.
Pesticides pose by far the greatest risk to fish and invertebrates, with weedkillers having the biggest impact on algae.
Journal reference: PNAS, DOI: 10.1073/pnas.1321082111
http://www.newscientist.com/article/dn25737-the-most-polluted-rivers-and-streams-in-europe.html#.U6b7KfRdXX6
Des chercheurs de l’université de Coblence, en Allemagne, ont analysé la qualité de l’eau dans plus de 4000 points de prélèvements en Europe et mesuré la présence de 223 produits chimiques. Dans 14% des sites, la concentration est potentiellement mortelle et dans 42% des sites ils pourraient causerdes effets à long terme. La France et notamment les rivières qui se jettent dans la mer du Nord est particulièrement concernée.
Comme le rappelait Sud-Ouest récemment, « les zones les plus touchées sont les grandes régions céréalières, maraichères ou viticoles : nord de la France, Bassin parisien, Sud-Ouest, amont du Rhône et Martinique. En 2011, sur les 176 secteurs hydrographiques (découpage géographique par bassins versants des rivières) surveillés en France métropolitaine, 63 présentaient une concentration moyenne annuelle supérieure à 0,5 microgramme par litre, seuil au-delà duquel l’eau est jugée “ impropre à la consommation humaine ”. »
http://rue89.nouvelobs.com/2014/06/22/devinez-sont-les-rivieres-les-plus-polluees-deurope-253118
The most polluted rivers and streams in Europe
Europe's rivers are awash with organic chemicals that can kill or subtly harm aquatic life, according to the most extensive survey yet of pollution in the continent's major river basins.
Toxicologists contacted by New Scientist welcomed the study, but point out that the researchers may have exaggerated the risks by choosing to define relatively low levels of chemicals as harmful. Such small concentrations might well affect animal populations, but by themselves would probably not be enough to cause a population to collapse.
Ralf Schäfer of the University of Koblenz-Landau in Landau, Germany, and colleagues analysed water quality data from over 4000 monitoring sites and measured concentrations of 223 different organic chemicals.
They discovered that at 14 per cent of sites, the concentrations of chemicals could potentially be lethal. The map below illustrates this. The colours indicate the fraction of sites in each river basin that exceed the lethal risk threshold.
What's more, 42 per cent of the sites may have subtler problems. The concentrations of organic chemicals were not immediately lethal, but could cause longer-term damage, such as impacts on breeding or increased vulnerability to disease.
All previous studies had focused on much smaller areas, such as individual streams. "The most important message from our study is that chemical pollution is a large-scale, not just local problem," says Schäfer.
The risk appears to be highest in central European and French rivers, especially those that empty into the North Sea from the Netherlands and Belgium. UK aquatic life also faces chronic risks.
Pesticides pose by far the greatest risk to fish and invertebrates, with weedkillers having the biggest impact on algae.
Journal reference: PNAS, DOI: 10.1073/pnas.1321082111
http://www.newscientist.com/article/dn25737-the-most-polluted-rivers-and-streams-in-europe.html#.U6b7KfRdXX6
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