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Wednesday, 8 March, 2000, 16:41 GMT

The 'innocent' polluters

Colonies of seabirds are adding to environmental pollution - simply by doing what comes naturally.

The birds are releasing large amounts of ammonia into the atmosphere through their droppings. Researchers say some species, such as gannets and guillemots, are guiltier than others.

Very large emissions of ammonia could have a detrimental impact on the local ecology, and may be just as problematic as intensive farming.

Scientists studying a seabird colony on Bass Rock off the east coast of Scotland have already measured ammonia concentrations 20 times higher than those on chicken farms.

Seabird population

Work has begun on a wider study, focussing on the Isle of May research site in the Firth of Forth, as part of the Ł7.1m Global Atmospheric Nitrogen Enrichment (Gane) programme. Penguin and chick

Researchers are using a range of techniques to record the amount of ammonia produced by different species.

They aim to gauge the effect on the atmosphere of the droppings from the 10 million seabirds that breed around the UK.

Dr Sarah Wanless, from the Centre for Ecology and Hydrology (CEH), said: "Emission rates should be lower from puffins, which nest in burrows, than from other species such as gannets or guillemots, which nest on cliff surfaces."

From there, the next step is to build up a database of global seabird colony distributions and use this to calculate the total ammonia emissions.

Remote areas

The importance of emission "hotspots" such as bird colonies is not wholly clear but Dr Mark Sutton, from the CEH, said: "We might get some clues by looking at the impact of penguin colonies in the Antarctic.

"Seabird emissions will have an impact in remote areas where these are the main source of ammonia in the absence of agricultural sources.

"The extra nitrogen provided from the ammonia deposition is expected to lead to changes in plant species composition, causing a loss of sensitive plant species."

Battery chickens, pig farms and muck-spreading are known to overload the atmosphere with ammonia, which adds to acid rain and global climate change.

Agriculture is believed to account for at least 80% of such acidic emissions.

The Gane programme is largely funded by the UK Natural Environment Research Council, with major contributions from the Ministry of Agriculture, Fisheries and Food and the Scottish Executive.

It is investigating the problems posed by additions to the UK and global nitrogen cycle.

Related to this story:
Ministers consider sandeel fishing ban (14 Dec 99 | Sci/Tech)
Marine life protection plan (24 Feb 00 | Scotland)
Ammonia blamed for fish deaths (29 Mar 99 | UK)
Soil problems prompt farming ban call (10 Jan 00 | Sci/Tech)

Internet links: Global Nitrogen Enrichment - GANE | The Virtual Birder | Natural Environmental Research Council |
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