全球河川大調查：處處化學濃湯 先進國家更待改進

The world's rivers are in a crisis of "ominous" proportions, according to a new global analysis, published today in the journal "Nature." Rivers in the developed world, including those in much of the United States and Western Europe, are under severe threat despite decades of attention to pollution control and investments in environmental protection, the study shows.

Rivers of the world least at risk are those where human populations are smallest. Rivers in arctic regions and inaccessible areas of the tropics appear to be in the best health.

This research is the first to assess both human water security and biodiversity in parallel and is the first to simultaneously account for the effects of pollution, dam building, agricultural runoff, the conversion of wetlands and the introduction of exotic species on the health of the world's rivers.

The report by an international team co-led by Charles Vorosmarty of the City University of New York, an expert on global water resources, and Peter McIntyre, an expert on freshwater biodiversity, presents a grim picture.

"Rivers around the world really are in a crisis state," says Peter McIntyre, a senior author of the new study and a professor of zoology at the University of Wisconsin-Madison's Center for Limnology.

The analysis reveals that nearly 80 percent of the world's human population lives in areas where river waters are highly threatened posing a major threat to human water security and resulting in aquatic environments where thousands of species of plants and animals are at risk of extinction.

"What made our jaws drop is that some of the highest threat levels in the world are in the United States and Europe," says McIntyre, who began work on the project as a Smith Fellow at the University of Michigan. "Americans tend to think water pollution problems are pretty well under control, but we still face enormous challenges."

Huge investments in water technology and treatment reduce threats to humans, but mainly in developed nations, and leave biodiversity in both developed and developing countries under high levels of threat, according to the report.

"We find a real stew of chemicals flowing through our waterways," explains Vorosmarty, noting that the study represents a state-of-the-art summary, yet was unable to account for such things as threats from mining, the growing number of pharmaceuticals found in surface water and the synergistic effects of all the stresses affecting rivers.

What jumps out, say McIntyre and Vorosmarty, is that rivers in different parts of the world are subject to similar types of stresses - agricultural intensification, industrial development, river habitat modification and many other factors.

Compounding the problem is that some of the negative influences on rivers arrive in indirect ways. Mercury pollution, for example, is a byproduct of electricity generation at coal-fired power plants. It is emitted into the atmosphere and then is deposited on river surfaces.