Details of Award
NERC Reference : NE/C004531/1
Charcoal degradation in natural environments: implications for radiocarbon dating and the carbon cycle
Grant Award
- Principal Investigator:
- Professor M Bird, University of St Andrews, School of Geography and Geosciences
- Co-Investigator:
- Professor C Baddeley, University of St Andrews, Chemistry
- Co-Investigator:
- Dr GL Cowie, University of Edinburgh, Sch of Geosciences
- Co-Investigator:
- Professor CB Ramsey, University of Oxford, School of Archaeology
- Co-Investigator:
- Dr P Wormald, University of St Andrews, Chemistry
- Co-Investigator:
- Professor D Philp, University of St Andrews, Chemistry
- Co-Investigator:
- Professor CE Snape, University of Nottingham, Faculty of Engineering
- Co-Investigator:
- Professor T Higham, University of Vienna, UNLISTED
- Grant held at:
- University of St Andrews, School of Geography and Geosciences
- Science Area:
- Terrestrial
- Marine
- Overall Classification:
- Terrestrial
- ENRIs:
- Global Change
- Science Topics:
- Science-Based Archaeology
- Biogeochemical Cycles
- Soil science
- Climate & Climate Change
- Abstract:
- Combustion is an important process by which carbon is returned to the atmosphere and fire is a basic tool that humans have used for many thousands of years for cooking, warmth, hunting and protection. One of the products of burning is charcoal, which is formed when wood is not completely combusted. Charcoal has a different chemistry from wood, and while it is more resistant to decay than wood, it is not yet clear what happens to charcoal after it is formed. Some charcoal is clearly very resistant to decay and can survive for many thousands of years, while other charcoal can apparently decay by mechanisms that are not yet well understood. How charcoal decays may be determined by what material was burnt and the conditions under which it was burnt, but it may also depend on the local environmental conditions where the charcoal was buried. Understanding what happens to charcoal after formation is important for several reasons: (i) if charcoal is resistant to decay, then the formation of charcoal may take carbon from the atmosphere and 'lock' it up, out of the active carbon cycle for thousands of years. Even if some of the charcoal does decay, a portion of it, possibly very small areas within the charcoal, may be resistant to decay and as the surrounding charcoal decays fine particles of 'black carbon' or dissolved molecules that are very resistant to decay may be liberated into the environment. (ii) Ancient humans often used fire for cooking and warmth so archaeological sites usually contain a lot of charcoal. Because charcoal is mostly carbon, it can be carbon dated, and one of the ways that archaeologists determine when people were present at an archaeological site is by carbon dating the charcoal that the people produced in their fires. The problem is that in some environments charcoal is poorly preserved and may be heavily contaminated by younger carbon that does not date from the time of charcoal formation, while in others in others it is well preserved. A new way of dating charcoal has been developed, which progressively 'peels away' the outer layers of the charcoal and gets rid of any contamination, so that a reliable date can be obtained. When this new technique was applied to samples that have been dated previously, about a third of the previous dates were found to be too young, because the old dating techniques did not consistently remove all contamination. This is a big problem, because it means that maybe a third of all charcoal dates ever produced could also be too young / even for important samples the were used to date things like the time at which humans arrived in different parts of the world, or the time at which Neanderthals died out in Europe. This project aims to better understand how charcoal decays in the natural environment, by determining how much charcoal is actually resistant to decay (and is therefore locked away from the active carbon cycle). It also aims to improve carbon dating of charcoal and develop ways to identify previously dated samples where the dates may not be reliable. We will do this by bringing together researchers from geochemistry, archaeology and pure chemistry to investigate the chemistry of charcoal samples we produce under controlled conditions and natural samples taken from sites with different environmental conditions. We will use specialized techniques that can identify the types of chemical bonds inside the samples and at the very surface of the sample, the source of the carbon in the samples, and the types of molecules in the samples. By analysing charcoal formed and/or buried under different conditions, and by separating out different components of the charcoal, we will be able to understand the chemical changes that happen to charcoal over time, and the significance of these changes for the global carbon cycle and for the dating of charcoal, which in turn underpins a wide range of studies in both archaeology and the reconstruction of ancient environments.
- NERC Reference:
- NE/C004531/1
- Grant Stage:
- Completed
- Scheme:
- Standard Grants Pre FEC
- Grant Status:
- Closed
- Programme:
- Standard Grant
This grant award has a total value of £253,954
FDAB - Financial Details (Award breakdown by headings)
| Total - Staff | Total - T&S | Total - Other Costs | Total - Indirect Costs | Total - Equipment |
|---|---|---|---|---|
| £104,565 | £5,049 | £58,674 | £48,100 | £37,566 |
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