ISOTOPIC-RATIOS OF LEAD IN CONTEMPORARY ENVIRONMENTAL MATERIAL FROM SCOTLAND

Lead emitted into the environment, primarily from the combustion of le aded petrol and industrial activities, retains the isotopic signature of the ore(s) from which it is derived. Leaded petrol, atmospheric par ticulates and street dust sampled in central Edinburgh between Februar y 1989 and December 1991 had mean Pb-206/Pb-207 ratios of 1.082 +/- 0. 024, 1.092 +/- 0.011 and 1.109 +/- 0.016 respectively. These isotope r atios were found to be depleted in Pb-206 compared with a mean of 1.16 0 +/- 0.012 for tap water in contact with lead pipes and typical ratio s of 1.17-1.19 for British lead ore deposits and coal. Paint, with an observed wide range of Pb-206/Pb-207 ratios (1.083-1.183), appears to have significantly influenced house dust and some street dust Pb-206/P b-207 values. Such overlaps and influences may hinder the quantitative apportionment, via isotope data, of source and route in general popul ation surveys of human exposure to lead.