Hemispheric atmospheric lead pollution has been
documented in many different geochemical archives
in Europe and North America. It started 6000 years
ago due to agricultural activities and soil tillage and
showed the most prominent peaks around the turn
of the century and between 1960 and 1980, reflecting
industrial emissions during the Industrial Revolution
and leaded gasoline combustion of traffic, respectively.
Significant concentrations of anthropogenic
lead obviously still exist in many archives such
as soil and aquatic sediments, and it is thought that
it will take many years to reduce these concentrations
to prepollution values, even if no new sources
of lead pollution emerge (Callender and van Meter
1997; Shotyk et al. 1998).