LONDON: A project to assess the world's ecosystems has found that the widespread use of fertilisers and the burning of fossil fuels will severely damage life in lakes and rivers around the globe.

The Millennium Ecosystem Assessment, launched by the World Bank in Washington in 2001, examines how any disruption to the environment, whether by human action or natural events, will harm human health, food production and natural resources.

Scientists have spent the past three years piecing together data from thousands of studies. Their official report will be published early next year, but a first draft shows a number of alarming trends.

A major concern is the increase in nitrogen emissions because of fertiliser use and the burning of fossil fuels.

"In the past 100 years, emissions have risen from around 20m tons a year to more than 150m tons a year," said Robert Watson, the project leader and the World Bank's chief scientist.

"We're emitting more than seven times more nitrogen and that is going to have incredible implications for ecological systems."

As an ingredient in fertiliser, nitrogen helps to feed some two billion people. But when it is washed from soils into water courses it can make rivers and lakes too rich in nutrients.

As a result, algae and other life can grow out of control, eventually stripping oxygen from the water which fish and other aquatic life need.

Dead zones have already begun to appear, notably in the Gulf of Mexico, which is fed by nitrogen-rich water from the Mississippi river. "We are looking at major effects in the US, Europe and south-east Asia," Dr Watson said.

As the world's population is estimated to grow to nine billion in 40 years, food production is expected to become more intensive, requiring ever more nitrogen-rich fertiliser.

Kenneth Cassman, an expert on environmental health at the University of Nebraska, said the efficiency of nitrogen use needed to be "massively improved". "There are a number among us who think this is more important than carbon emissions, in terms of environmental impact," he said.-Dawn/The Guardian News Service.