CARBYDAT

What are SCPs?

Fossil-fuels, such as coal and oil, are burned at high temperatures to produce heat and power for electricity generation and other industries. At temperatures of up to 1750°C and at a rate of heating of approaching 104°C-1 the droplets, or pulverised grains of fuel, are efficiently burned even though they only remain in the furnace for a matter of seconds.

spheroidal carbonaceous particleThe products of this combustion are porous spheroids of mainly elemental carbon and fused inorganic spheres formed from the mineral component of the original fuel.

These spheroidal carbonaceous particles (SCPs) and inorganic ash spheres (IASs) are collectively known as fly-ash, the term used to describe the particulate matter within emitted flue-gases.

This page provides information on the use of Spheroidal Carbonaceous Particles (SCPs) as a means by which to date lake sediment cores, and in particular, the NERC funded project 'Using spheroidal carbonaceous particles to establish a reliable, recent lake sediment chronology for the future' (2000 - 2002) Project No. (GR9/04557) undertaken with the Environmental Radioactivity Research Centre (ERRC) at the University of Liverpool.

Introduction

Many environmental change studies deal with human impacts in the modern industrial age and thus focus on the period since the mid-19th century. Fortuitously, sediment dating for this period has, until now, been reliably covered using a chronology based on the isotope 210Pb, which has a half-life of 22.26 years. However, the time is now approaching when this half-life will preclude this isotope from providing a chronology for the full post-industrial period. Even now, confidence limits for dates in the mid- late19th century are in the region of ±20 - 25 years. This situation will only deteriorate until this period is out of reach of the technique entirely as, progressively, will each successive year. While 210Pb can still date this period with some degree of reliability it is essential that an alternative, independent technique be calibrated, in order to provide a reliable sediment chronology for future researchers. The aim of this project is to produce such a chronology using spheroidal carbonaceous particle stratigraphy.

Spheroidal carbonaceous particles (SCPs)

SCPs are produced from the high temperature combustion of fossil-fuels and emitted to the atmosphere with flue-gases (see boxed info). There are no natural sources and they therefore provide an unambiguous indicator of atmospheric deposition and contamination. There is no evidence for any particle decay in lake sediments and they are not subject to remobilisation once stored except by physical disturbance. They are therefore reliable sediment markers from the start of their record in the mid-19th century and their consistent stratigraphy has led to their being used for dating purposes.

Three features of SCP profiles have been used for sediment dating although specific dates are subject to regional variation. These are:

  • the start of the record (c.1850)
  • the start of the rapid increase in concentration following the Second World War (1950s)
  • the peak in SCP concentration (mid - late 1970s). 

More information on this approach can be found in Rose et al. (1995).

CARBYDAT Database

This project has used archived and new sediment cores, and existing data from the ECRC (University College London), to produce dated SCP profiles for 80 lakes across the UK and north of Ireland. The temporal profiles of these lakes shows some regional coherence and the SCP sediment record, in particular the cumulative percentage profiles, can thus be used to date lake sediment cores from sites within these regions.

There are two ways to use these data. First, use the regional approach to provide dates (with errors) for each 10-percentile of the SCP cumulative inventory. To do this, click on the 'CARBYDAT - REGIONS' link below. Second, use the dated SCP profiles to provide dating information for sediment cores from specific sites. To do this, click on the 'CARBYDAT - SITES' link below.

Use of these data are restricted. To obtain data please e-mail Neil Rose stating how you intend to use these data.

Please note that any use of these data should acknowledge 'CarbyDat' and the ECRC. In the future it is hoped to expand this work to other regions of the world as more data become available.

>>CARBYDAT - SITES<<

>>CARBYDAT - REGIONS<<

Please reference this work as:

Rose, N.L. and Appleby, P.G. (2005) Regional applications of lake sediment dating by spheroidal carbonaceous particle analysis I: United Kingdom. Journal of Paleolimnology 34:349-361.

Additional References

Rose, N.L., Harlock, S., Appleby, P.G. and Battarbee, R.W. (1995) The dating of recent lake sediments in the United Kingdom and Ireland using spheroidal carbonaceous particle concentration profiles. Holocene 5:328-335.