Do efflorescent salts from worn lead-acid automotive batteries represent potential non-exhaust emissions to urban pollution? A Pb isotope perspective

Automotive lead-acid batteries have been used for decades, and despite the development of alternative battery technologies, they are still widely used around the world, especially in developing countries. Several studies on the production, recycling, and environmental impact of the lead-acid battery industry have been carried out; however, the contribution of batteries used in operating vehicles to urban pollution (i.e., non-exhaust emission) remains unexplored. Worn lead-acid batteries trigger the formation of efflorescent salts containing potentially toxic elements that precipitate on battery terminals, which could be dispersed during vehicle transport. This research focused on determining the nature of Pb associated with this type of efflorescent salts to identify the sources that influence Pb in the urban dust of Hermosillo city, northwestern Mexico. Pb isotope systematics was used to determine the anthropogenic end-member contributing to the composition of urban dust. Pb isotope data of efflorescent salts revealed less-radiogenic compositions. The findings of this research highlight that efflorescent salts related to acid-lead batteries may represent an anthropogenic source of contaminants associated with non-exhaust emissions. The contribution of efflorescent salts potentially influences the Pb isotope compositions of urban dust and may help to understand Pb inputs from non-exhaust emissions to urban dust.