Science Inventory

Complexities in attributing lead contamination to specific sources in an industrial area of Philadelphia, PA

Citation:

Tuccillo, M., J. Blue, J. Koplos, J. Kelly, AND R. Wilkin. Complexities in attributing lead contamination to specific sources in an industrial area of Philadelphia, PA. Heliyon. Elsevier B.V., Amsterdam, Netherlands, 9(5):e15666, (2023). https://doi.org/10.1016/j.heliyon.2023.e15666

Impact/Purpose:

Requests for analytical support to measure Pb isotope ratios from site soils and groundwater are becoming frequent from our Regional partners. Lead isotope ratios can be used as a geochemical tool for constraining source apportionment. Lead isotopes are useful for solving a range of problems in environmental geochemistry due to the highly varied natural abundance of Pb and the half-lives of the radionuclides, like U and Th, that decay to different Pb isotopes. Lead isotopes are particularly useful for determining the source of Pb-containing materials in the environment. This research is needed to support current and future requests for support and analytical data, and to develop and test this approach for use in source apportionment studies conducted by the agency.

Description:

Globally, lead (Pb) contamination is one of the top ten chemical exposure issues affecting public health. Children’s neurological system development can be impaired by even low levels of Pb exposure. Detailed site histories and the identification of specific sources of Pb (e.g., using stable isotopes) may provide valuable information to determine assignment of liability for site cleanup and to improve sampling plans and remedial strategies. This paper examines Pb concentrations and Pb isotopic data from samples collected at and near the site of a Pb paint production facility with a long operating history. Although extremely high soil Pb concentrations are found at the site, Pb concentrations in surrounding neighborhoods do not simply decline with distance from the site. We evaluated soil samples and assessed spatial distribution and isotopic mixing lines to explore potential sources of Pb pollution. Three-isotope plots show overlap of site samples and those from the surrounding neighborhood, consistent with pollution from the facility affecting offsite soils. A major challenge in separation of potential sources is that the isotopic signatures of other potential Pb sources fall within the range of the soils data. The long operational site history, soil disturbances from construction and excavation, the presence of nearby smelters, and other local and remote sources affect identification of lead sources in the soil samples. This analysis demonstrates that although the likely signature of a significant polluter may be discernable, a simple source attribution for a given sample can be confounded by incomplete site and material sourcing information and area histories. An integrated approach that includes in-depth site characterization and exploration of site and neighborhood history (e.g., Pb ores used over time, amounts of Pb emitted by other area smelters, land use changes, and soil disturbances) would be useful for source attribution. Careful planning of soil sampling efforts to capture more site history would also be valuable. This analysis may provide insights into future site investigations where soil lead contamination has resulted from a long industrial history in an urban setting.