After completing one of the longest running experiments
ever done on a lake, researchers from the University
of Alberta, University of Minnesota and the Freshwater
Institute, contend that nitrogen control, in which
the European Union and many other jurisdictions around
the world are investing millions of dollars, is not
effective and in fact, may actually increase the problem
of cultural eutrophication.
The dramatic rise in cultural eutrophication-the
addition of nutrients to a body of water due to human
activity that often causes huge algal blooms, fish
kills and other problems in lakes throughout the world-has
resulted from increased deposits of nutrients to lakes,
largely from human sewage and agricultural wastes.
For 37 years researchers looked at Lake 227, a small
lake in the Canadian Shield at the Experimental Lakes
Area (ELA) in Ontario, Canada, and examined the best
ways to control the cultural eutrophication process
of lakes by varying the levels of phosphorous and
nitrogen added to the lake.
"What we found goes against the practices of the
European Union and many scientists around the world,"
said David Schindler, professor of ecology at the
University of Alberta and one of the leading water
researchers in the world. "Controlling nitrogen does
not correct the polluted lakes, and in fact, may actually
aggravate the problem and make it worse."
A previous study, entitled, A Survey of the State
of the World's Lakes, found that the cultural eutrophication
of lakes has had a global effect. The continent percentage
of lakes with cultural eutrophication were shown as:
Asia: 54 per cent
Europe: 53 per cent
North America: 48 per cent
South America: 41 per cent
Africa: 28 per cent
"The damage to these lakes is a major concern for
virtually every continent," said Schindler.
The impact on human society is immense he says, as
cultural eutrophication severely reduces water quality,
which not only kills and contaminates fish, shellfish
and other animals, but also can become a health-related
problem in humans once it begins to interfere with
drinking water treatment.