It is clear that the sources of lead in the environment have changed over centuries. Mining/smelting were prominent at first, dating back to the Ancient Egyptians—given these operations were local, associated contamination was proximal to the source. Then as civilization entered the Industrial Age in the 19th Century, coal combustion added another source of lead that, given the production of aerosol particulates (flyash), lead contamination could be distributed over larger geographic areas. By the early 20th Century, the 1920s, leaded gasoline combustion entered the mix of lead contaminants, and like coal, lead aerosols emanating from automobile tailpipes became widespread, especially in urban areas.
Lima et al. (2005) published a very prescient article that detailed such temporal changes in the sources of lead contamination as recorded in Pettaquamscutt River Basin sediments (PRBS)—the river is located in the northeastern United States in the State of Rhode Island. The authors apportion temporal variations in lead contamination in the PRBS among mining sources from Mississippi River Valley Type lead production versus coal/leaded gasoline combustion. However, the authors overlooked important details which, given this note is an overview of my response, I will not belabor but will allow you to discover via reading my response. The bottom line is the contribution of leaded gasoline combustion derived lead was underestimated.
Suffice it to say, the article and my response demonstrate the significance of using lead isotopic analyses, incorporated with other information (e,g, age dating, general geochemical analyses of soils) to evaluate the long-term legacy of lead pollution in the environment. The issue of lead pollution, despite governmental regulations, remains given lead’s tenacity and recalcitrance in the environment.