Lead in the western North Atlantic Ocean: Completed response to leaded gasoline phaseout

A 16-year time series of lead concentrations in the western North Atlantic Ocean shows that lead concentrations decreased markedly during the 1980s but that the decline slowed in the 1990s. The decrease during the 1980s can be attributed to the phasing out of leaded gasoline in the United States. Lead concentration levels of the 1990s may be supported by emissions from high temperature industrial activities in the USA rather than by residual leaded gasoline emissions. Lead concentrations in the thermocline above ∼700 m depth have continued to decrease over this time period. Further decreases in surface water Pb concentrations may be minimal in coming decades, but continued propagation and evolution of the lead distribution in deeper waters should be expected.