Nature the winner as pit closures help to reduce acid rain: Power generators' switch to gas cuts sulphur dioxide emissions. Nicholas Schoon reports

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THE CLOSURE of Britain's coal mines will save huge swaths of the countryside from acid rain damage, government maps published yesterday show.

While communities have been devastated by the pit closures, wildlife and habitats should reap great benefits. The area being acidified by the fall-out from sulphur dioxide pollution will be cut roughly tenfold, from 121,000 square kilometres (46,700 square miles) to about 11,000 over the next two decades.

The burning of high-sulphur British coal in power stations has been the main contributor to the nation's emissions of sulphur dioxide. This is the air pollutant which has been responsible for the bulk of acid rain, mist and snow descending on Britain. Large quantities blown across the North Sea have also helped acidify much of southern Norway and Sweden.

But with electricity generating companies switching from coal to cleaner and cheaper gas, and mines closing rapidly in consequence, the British Government has been able to promise sharp reductions in UK sulphur dioxide emissions over the next 16 years.

At United Nations negotiations on cross-border air pollution in Geneva last week, Britain agreed to cut these emissions to 70 per cent of their 1980 level by 2005, and to 80 per cent by 2010. A new treaty will be signed in June.

In 1991, coal-burning power stations were responsible for 71 per cent of UK sulphur dioxide emissions, producing 2.5 million tonnes of the gas. But as the coal industry declines, so will this pollution.

British coal could be burnt without causing acid rain, but the power stations would have to be fitted with gas desulphurisation equipment which extracts most of the pollution from their flues.

Only two coal-fired stations have been fitted with this equipment - National Power's Drax plant in North Yorkshire, and PowerGen's Ratcliffe on Soar plant in Nottinghamshire.

The total cost was almost pounds 1bn and neither generator plans to install the equipment anywhere else because they believe the expense would make them uncompetitive with the growing number of gas- fired power stations. They also have the option of importing low-sulphur foreign coal.

The maps prepared for the Department of the Environment by government and university scientists show that in the early 1990s almost half of Britain's land was receiving more acid fall-out than it could cope with; the soil is chemically altered in consequence. But by 2010 only 5 per cent of the land should be acidified.

The damage is mostly in the uplands. This is because the high rainfall there washes down the acid fall- out and the thin soils on hard, granitic rocks have little ability to neutralise the acidity.

Trout and salmon have vanished from the streams and lakes of the worst-affected areas. In the south Pennines and the Derbyshire Peak District the upland vegetation has been transformed. But mostly the effects are insidious.

Acidification has been implicated in the decline of the natterjack toad in its native heathlands and the failure of otters to return to some parts of Wales.

(Graphic omitted)