Stable lead isotope data can yield information on
the geochemical origins of lead and on its relative
contributions from sources such as coal burning, mining,
smelting, and car-exhaust emissions. This extremely
detailed 206Pb/207Pb profile for
dated bottom
sediments in Loch Lomond, Scotland, shows the trends
clearly related to the varying nature and extent of
anthropogenic lead inputs after 1630. In particular,
a
significant decline in the
206Pb/207Pb ratio of
excess
lead during 1929−1991 is attributable to the
introduction and use of (206Pb-depleted) leaded
petrol
since the 1920s. This accounts, however, for just
24−53% of the excess lead deposited since 1929 and
≤19% of the total excess lead inventory. Deposition
of lead from industrial (and domestic) activities has
predominated overall and, on an annual basis, until at
least the mid-1950s.