Biogeochemistry and cycling of lead

Lead has no biological function and is one of the most toxic metals. At the same time, it is one of the most useful, and perhaps no other metal has found such a wide range of industrial applications. It has been used extensively since Antiquity, which is when environmental Pb contamination began. With respect to contamination since industrialization, peat bogs and polar ice show that coal combustion and industrial emissions were as important during the first half of the 20th century as gasoline lead was during the second half. Air Pb concentrations have generally declined since the introduction of pollution control technologies and the gradual elimination of leaded gasoline additives. However, all of the most recent published studies of the isotopic composition of Pb in aerosols and archival samples show that anthropogenic sources continue to dominate the atmospheric Pb flux by a considerable margin. The health effects of childhood Pb exposure is a growing concern, as deleterious effects are seen at BLL well below those currently believed to be safe, and safe levels are one or two orders of magnitude above the estimated natural values. Mobilization of Pb-rich particles from highly contaminated soils in urban areas is an on-going health concern for many large cities. Even in areas far removed from industrial emission sources, Pb concentrations in the surface soil layers are far above their natural concentration range. In acidic forest soils, Pb concentrations are not only elevated in the biologically active zone, but also in their corresponding pore fluids. Accurate and precise measurements of the isotopic composition of Pb employing appropriate clean lab protocols, will continue to advance our understanding of the fate of Pb in the environment and its impact on human and ecosystem health.