The historical record of PAH, PCB, trace metal and fly-ash particle deposition at a remote lake in north-west Scotland

Sediment cores taken from the deep basin of Loch Coire nan Arr in north-west Scotland were dated using 210Pb calibrated spheroidal carbonaceous particle (SCP) profiles and analysed for trace metals, polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs). These data show that the site is one of the least contaminated by atmospheric pollution in the UK. Peak concentrations of PAHs were found to be equivalent to background values at sites in the English Lake District. The date of concentration maxima for SCP, PCB and some metals were in agreement with previously published polychlorinated dibenzo-p-dioxin/polychlorinated dibenzofuran (PCDD/F) data suggesting long-range industrial sources. The date of individual PAH concentration maxima were earlier, but concomitant with each other, possibly suggesting the influence of a local source. Comparison with remote European mountain lakes shows Loch Coire nan Arr to be one of the least contaminated sites in Europe with respect to PCBs, but more contaminated with respect to PAHs.