Manchester Metropolitan University

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Metal-eating bacteria threat

AREAS of the Peak District are being damaged by acid excreted by metal-eating bacteria, a legacy of the industrial revolution.

Acid build-up in streams now threatens to poison reservoirs and blanket bogs which are home to rare plants, such as wild orchids, golden plovers and mountain hares.

The MMU research is presented today at the Society for General Microbiology's annual meeting in Edinburgh.

Dr Patricia Linton, of the Department of Environmental and Geographical Sciences, who with co-workers carried out the study, said the discovery was a cause for concern.

Getting worse

"This is a legacy of the pollution that has poured from factories and mines in the area. Much of that pollution stopped 50 years ago, with the introduction of clean air legislation. However, there has been no improvement to the Peak District's ecology. The damage is still getting worse."

A particular danger involves heavy metals, in particular lead and zinc. These particles have been swept into the air caught up in clouds, and carried over the area. Then as clouds have released rain, this lead and zinc has fallen over hillsides. In this way, the area has become polluted with heavy metals.

"Lead and zinc are no longer spewed out as they were in the past, but we can still detect high levels in the Peaks," Dr Linton added.

For example, in one sample from Bleaklow - one of most beautiful parts of the Peak District - she found lead levels of 1,066 parts per million, 10 times the expected value.

Metal-eating

At the same time, the scientists found levels of zinc of 66ppm, several times higher than expected.

However, the real surprise for the research team was their discovery that metal-eating bacteria, which are usually only found in mine spoil heaps and other industrial waste tips, can now be found in many parts of the Peaks.

"Metal-eating bacteria seem to be thriving there despite high levels of potentially toxic lead and zinc and are excreting acid as they grow.

"We found high levels of these bacteria in the areas with some of the worst damage. We also found that many samples of soil were more acidic that other bog sites in the UK."

Storm erosion

The scientists suggest acid water could dissolve more metals, and these could leach into the groundwater and streams could carry the acid water down to reservoirs.

"Some areas of the Peak District are already being badly affected by storm erosion and if acid kills off plants that bind and hold soil in place, that problem is only going to get worse," said Linton.

"We badly need to carry out more research to find out the extent of the damage that has been done and to find out how the area is threatened by future changes."

For more about research in the Environmental and Geographical Sciences, go to www.dri.mmu.ac.uk/research_areas/environmental_science/default.asp

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