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Healthy rocks and wildlife farming

22 October 2002

The Autumn edition of Planet Earth is now available.

The relationship between rocks and our health, and new methods for farming and countryside management to both encourage wildlife and make a profit, are just two of the exciting research projects highlighted in the latest issue of Planet Earth, the quarterly journal of the Natural Environment Research Council (NERC).

The rock diet

Rocks are a vital source of the essential elements and minerals people need to stay healthy. The British Geological Survey (BGS) together with partners in China, Sri Lanka, Morocco and the UK have investigated the health effects of two of these elements, iodine and selenium.

Weathering breaks down rocks to form the soils in which we grow crops and raise farm animals. Most Westerners no longer grow food in their back yards but people in developing countries rely on their immediate surroundings for food. People suffer serious illness if their local soil provides too much or too little of particular minerals or elements.

Iodine is needed for growth hormones formed in the thyroid gland. Most cases of iodine deficiency cause goitre, a condition where the thyroid becomes enlarged as it attempts to compensate for the lack of iodine. Goitre affects about 190 million people worldwide.

Fiona Fordyce, an Environmental Geochemist with the BGS, said, "In Britain, goitre occurred historically in the Peak District and was known as Derbyshire Neck. People used to think that this was because Derbyshire is a long way from the sea where sources of iodine are abundant. But recent research suggests the chemistry of the limestone environment indirectly prevents the iodine from entering the human food chain."

She added, "In China and Morocco we are examining how iodine moves through the environment or becomes locked in the soils. We want to improve iodine uptake from soils into crops and then into human food. Although medical remedies such as using iodised salt have proved successful in many parts of the world, countries which can't afford these remedies need alternative ways to get this element."

According to the World Health Organisation, iodine deficiency is the major cause of preventable mental retardation in the world today, with 1·6 billion people at risk, 50 million children affected and 100,000 sufferers born every year.

Selenium

In the human body selenium acts as an anti-oxidant, preventing tissue damage. People living in the Enshi District in central China show classic symptoms of the effect of selenium on health. The geology in this remote mountainous region can vary from village to village. Some people live on soils derived from coal, which have very high selenium content, while 20km away people living over selenium-poor sandstone rocks have Keshan disease which damages the heart muscles and eventually causes death.

The BGS team collected samples of soil, food crops, drinking water and human hair from areas with low, moderate and high incidences of Keshan disease. Chris Johnson, a Geochemist at BGS, said, "As expected, both the population and the environment were selenium deficient but there was an interesting twist in the results. The villages with the greatest disease problems had the lowest selenium levels in the hair, water and crop samples. But the soil had the highest selenium content - the very opposite to what we were expecting."

People in the UK are also becoming concerned about the falling levels of selenium in our diet. Bread is one of our main sources of selenium but intakes are going down because Britain no longer imports much wheat from the selenium-rich soils of the North American prairies.

The buzz of biodiversity down on the farm

Satellite technology is helping farmers to make their land environmentally sustainable and profitable.

Dr Richard Pywell and his group from the Centre for Ecology & Hydrology (CEH) teamed up with the Farmed Environment Company to test these new methods. They used satellite Global Positioning System technology to identify areas of a Yorkshire arable farm where extra fertilisers and pesticides had been needed to return a profit. The researchers also conducted a survey of plants, animals and habitats on the 164 hectare Manor Farm. The combined information allowed them to pick out the best areas for environmental enhancement.

Says Dr Pywell, "The farm has created new wildlife habitats, encouraging small animals and insects to take up residence. New hedgerows and a revised crop-harvesting schedule in some fields provides food and havens for birds - there has been a 30% increase in the number of breeding bird territories across the farm over the past two years. And throughout the habitat creation period, the farm has remained profitable!"

Last year the Farmed Environment Company and CEH, together with partners from the farming industry and conservation organisations, launched the Buzz Project. This is a three-year research and technology transfer initiative that aims to test if the findings from the Manor Farm project can be replicated on six other farms. This network of farms will be used as the basis of training packages to help farmers learn some of the environmental skills needed to achieve the Policy Commission's vision of the countryside.

Further information

Iodine and selenium research:
Fiona Fordyce
BGS Edinburgh
Tel: 0131 667 1000
Chris Johnson
BGS Keyworth, Nottingham
Tel: 0115 936 3100

Manor Farm project:
Richard Pywell
CEH Monks Wood, Cambridgeshire
Tel: 01487 772400
Marek Nowakowski
Farmed Environment Company, Chesterton, Oxfordshire
Tel: 01869 253808

NERC Press Office
Natural Environment Research Council
Polaris House, North Star Avenue
Swindon, SN2 1EU
Tel: 01793 411561
Mob: 07917 557215

Notes

1. Copies of Planet Earth can be obtained from the NERC Press officer. Alternatively, you can visit the Planet Earth web page to subscribe to the magazine or download PDF files of the articles.

Press release: 09/02

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