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???Scientists can use the isotopes in fossils to investigate the climate millions of years ago.
Scientists can use the isotopes in fossils to investigate the climate millions of years ago.

Press Release - 24 June 2005

Nature’s atomic reporters: Isotopes tell their stories

The chemical ‘signatures’ that have helped scientists gain amazing insights into the history of the universe and could help develop new generations of drugs will be the subject of a unique conference at the University of Bath next week. (27 June - 1 July)

Seventy scientists from around the world will be coming to Bath to discuss new research into isotopes; different versions of the same element caused by variations in their atomic structure.

Isotopes were discovered early last century when scientists found that the atomic nucleus of many elements, including oxygen, carbon and hydrogen, can have different numbers of neutrons and thus different weights.

Some isotopes are unstable and change into other elements by radioactive decay, a process that is the source of nuclear power but also has other uses.

Archaeologists use the radioactive isotope of carbon, known as carbon-14, to work out how old an object is. Radioactivity breaks carbon-14 down in a very predictable way, so scientists can work out how old the object is by looking at how far the process of breakdown has gone. As carbon is one of the key elements in all living things, carbon dating provides archaeologists with a very useful too for assessing the age of historical artefacts.

The Bath conference, hosted by the University’s Department of Chemistry, will focus upon stable (non-radioactive) isotopes. Once it was thought that the proportion of the isotopes of a particular element - for example, oxygen-16, oxygen-17 and oxygen-18 – was a fixed ratio everywhere and at all times. However, at different times through history, environmental conditions on Earth have favoured slightly different ratios of these isotopes.

These isotopes can then become ‘frozen’ into an object - for example when a fossil is formed – and scientists can work out the conditions in which it was formed by studying the isotopes.

For example, sea creatures that died and fell to the bottom of the sea many millions of years ago contain a proportion of oxygen - 18 determined by the average temperature at that time.

So by measuring the relative amounts of the oxygen isotopes in the calcium carbonate stored in fossil sea-shells, scientists can find out about ancient climatic conditions when the sea creatures were still alive.

A baffling recent discovery is that the isotopic ratios found in meteorites are like nothing on Earth. For example, the relative amounts of the oxygen isotopes cannot be explained by the conventional theories. Some of the world’s leading experts will be discussing their ideas about the problem at next week’s conference.

“Isotopes are like atomic reporters, each telling their story to provide detailed information about the chemical processes that operate at different times or under different conditions,” said Professor Ian Williams who has organised the conference.

“Chemists can deliberately introduce a heavier isotope into a substance in place of the regular one – for example hydrogen is replaced by its isotope deuterium which is twice its weight - and then measure how chemical reactions are slightly speeded up or slowed down by the change.

“This approach is giving us a new understanding of how these reactions are controlled by enzymes in living organisms. That knowledge can be applied in the design of novel and effective drugs.

“Isotopes are the subtlest of variations within an element, but even these tiny changes can change the way that element behaves within a chemical reaction.

“An exciting new development is to use different isotopes to produce different chemical products than would normally be obtained in a reaction. This way it may be possible to make new materials that we can put to use in a variety of practical ways.

“The conference will bring together scientists from all over Europe and the rest of the world to talk about some of the latest research findings and discuss ideas and opportunities for future collaborations,.

“Isotopes are much more than just curiosities but provide useful tools for exploring a vast range of science from cosmology to biology.”

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