Europe still being showered by acid rain
5 September 2005, PRAGUE - Climate change news grabs headlines, but the decades-old issue of acid rain is still high on the danger agenda for Europe's environmental scientists.
5 September 2005
PRAGUE - Climate change news grabs headlines, but the decades-old issue of acid rain is still high on the danger agenda for Europe's environmental scientists.
From Sweden's lakes to the Swiss Alps, scientists say precipitation tainted by atmospheric pollution continues to shower the continent with harmful acidic compounds linked to the burning of fossil fuels and modern agriculture.
Threats to forests, fish and human health persist despite Europe's significant success in cutting harmful emissions from coal-fired power plants and smokestack industries over the past 30 years, according to scientists at an acid rain conference held recently in Prague.
Several studies at the conference raised red flags about rising levels of nitrogen oxides or NOx, in some parts of Europe. Spewed by motor vehicles, NOx rises into the atmosphere and falls with rainwater, fog, mist and snow.
Levels of the two, main components of acid rain - NOx and sulfur dioxide SO2 - have been declining overall in Europe since the mid- 1980s. But scientists have found NOx hotspots, and warn that government objectives for acid-rain reduction in some countries are not being met.
For example, an eight-year study by scientist Oyvind Kaste and colleagues at the Norwegian Institute for Water Research found seasonally dangerous levels of NOx-linked nitrates in southern Norway's streams before and during spring snowmelts.
The Norwegian study suggested the chemical imbalance in streams and rivers may be hurting fish including the economically important salmon.
"Acid 'pulses' that occur in streams during spring are likely to affect the smolt stage of Atlantic salmon," the study said, noting that nitrate levels in the targeted streams are "steadily increasing".
A separate study of acid rain in the central Alps found high levels of NOx polluting areas of Switzerland and the Alpine foothills of northwest Italy.
The study, conducted by 10 scientists from Italy, Switzerland and France, said forests are threatened by polluted precipitation "transported with air masses from industrialized and urbanized regions, and intensive agriculture on the plains bordering the Alpine rim".
The scientists doubt that an international goal to cut NOx in the Alps by 2010 can be reached.
"The deposition of nitrogen is still well above the estimated critical loads," the study said. "Important terrestrial ecosystems in these regions of the Alps are in a critical situation regarding nitrogen inputs."
Similarly, Swedish scientists said their government's "national objective" to reduce NOx emissions "will most probably not be achieved" without a major effort to lower emissions from motor vehicles, mobile machinery and ships.
Stockholm had hoped to lower annual NOx emissions to 150,000 tons a year by 2010 from the current level of 205,000 tons.
Despite the often bleak forecast, however, the scientists cited some victories in Europe's long battle against acid rain.
For example, in Sweden a huge project that uses aircraft to spread acid-fighting lime has improved conditions on about 8,000 lakes. As a result, only 8 per cent of the country's lakes are listed as "acidified", down from 17 per cent in 1990.
Lower levels of SO2, aluminium and other acid rain components have reduced the stone-scouring damage to many of Europe's historic buildings.
And Czech Republic scientists said cleaner air has helped forest health "improve dramatically" since 1991 in the Krusne Hory Mountains, near the Czech-German border.
However, many forests in the so-called Black Triangle region of Czech Republic, Germany and Poland have only started to recover from the acid rain that polluted soil when the region was heavily industrialized during the Soviet era.
"Long-term acidification" from the 1960s still causes root deformities in beech and larch trees in the Black Triangle's Jizerske Hory Mountains, and the "forest health is still not satisfactory", said Marian Slodicak of the Czech Forestry and Game Management Research Institute.
The persistence of acid rain despite decades of pollution-fighting initiatives was a theme also reflected in a study by German scientists in the East German city of Leipizig.
The study said NOx emissions dropped drastically when East Germany's old, communist-era factories and farms were closed 15 years ago. But it cited a "drastic increase" in Leipzig's motor vehicle traffic since the fall of communism that has "compensated" and reversed the previous decline in emissions that cause acid rain.
Subject: German news