The lead content and isotopic composition of British coals and their implications for past and present releases of lead to the UK environment

More than 60 coal samples, predominantly from the principal coalfields of E ngland and Wales (25) and Scotland (30), were analysed for lead by AAS and for stable lead isotopes by ICP-MS. While the average lead content of Scott ish coal, 23.9 mg kg(-)1, was more than double that of coal from England an d Wales, 11.0 mg kg(-)1, the corresponding mean Pb-206/Pb-207 ratios (+/- 1 s.d.) were nearly identical, at 1.181 +/- 0.011 and 1.184 +/- 0.006, respe ctively. In the light of the lead isotopic signatures of British coals and of both indigenous (Pb-206/Pb-207 similar to 1.17) and imported Australian (Pb-206/Pb-207 similar to 1.04) lead ores, an approach based on estimated l ead emissions from these sources and the deconvolution of the historical le ad and Pb-206/Pb-207 records preserved in lake sediments, peat bogs and arc hival herbage material indicates that coal combustion became an increasingl y significant contributor to atmospheric lead deposition in the UK during t he period 1830-1930, especially after the onset of England's decline as a m ajor location of lead mining and smelting in the late-19th Century. Since 1 930 and the introduction of leaded petrol, the atmospheric Pb-206/Pb-207 ra tio in the UK has been strongly influenced by car-exhaust emissions of comp aratively Pb-206-depleted lead of predominantly Australian origin, counter- balanced to some extent by coal-combustion emissions of lead, although thes e have fallen dramatically since the mid-1950s. Nevertheless, with the intr oduction and substantial uptake of unleaded petrol in the UK during the las t decade, even the declining releases from coal, along with contributions f rom other sources, are continuing to affect the atmospheric lead content an d Pb-206/Pb-207 ratio.