Power stations cleared of acid lake effect
Published in the journal BioScience, new research from Sweden suggests that emissions from power plants have played less of a role in the acidification of lakes than previously thought.
Power stations used to pump out unregulated sulphur dioxide and nitrogen oxides until controls were brought in in the 1970s and 1980s.
As Sweden has thousands of lakes the Swedish government was particularly active, instigating a programme of liming acidified lakes.
However, some scientists believed that organic carbon from living organisms played a greater role in lake acidification.
Martin Erlandsson of the University of Reading, United Kingdom, tried to go back in time to see if they could find which was the greater culprit.
Since 1990, the acidifying emissions from power stations have been stable because of legislation. Yet, the acidity in Swedish lakes has continued to rise.
Erlandsson and his team decided to test the hypothesis that power station emissions kept the emissions of carbon from organic sources down and, in fact, the lakes might have been 'naturally' more acidic than the 1990 base level.
The scientists made estimates of the pre-industrial acid levels in 66 lakes, and looked at sediment from some of the lakes and found that levels from organic carbon deposits were often higher than they were when anti-acid measures were first taken in 1990.
Erlandsson says they do not doubt the general good of reducing power station emissions but knowing the true effect of the emissions on acidification is an important area of study.
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