Within-basin profile variability and cross-correlation of lake sediment cores using the spheroidal carbonaceous particle record

Spheroidal carbonaceous particles (SCPs) from the high temperature combusti on of fossil-fuels are stored in lake sediments and provide an unambiguous record of industrially derived atmospheric contamination. It has been assum ed that a single sediment core provides an accurate representation of SCP a ccumulation but to date there have been no studies to determine within-lake variability of the SCP sediment record. This paper describes the SCP profi les of ten sediment cores taken from the deep water area of Loch Coire nan Arr, a remote lake in northwest Scotland, UK. Although each core shows the basic SCP profile used for sediment dating in the UK there is considerable variation between cores. The conversion of SCP concentrations to cumulative percentages resolves a great deal of this variation with the result that m ore accurate cross-correlation and hence date allocation is possible, espec ially in the post-1945 section of the cores. However, significant departure s from the usual SCP profile still reduce the effectiveness of this approac h. It is concluded that: (i) SCP profiles from single cores from the deepes t areas of the lake usually provide an accurate representation of the histo rical record of atmospherically deposited pollutants and that inter-core va riability or noise does not affect the temporal interpretation of that prof ile, and (ii) comparisons of total SCP inventories are a better way of comp aring historical deposition between sites as the impact of temporary variab ility is considerably reduced.