Lead (Pb) is the most widespread contaminant resulting from human land use, and mounting evidence shows there is no safe blood lead level resulting from exposure. In comparison to urban areas, rural areas have been far less researched with regard to Pb contamination despite documented potential for long-range transport. In this study, we employ a 60-year long-term soil experiment in rural South Carolina to capture decadal changes in Pb deposition during the phase-out of leaded gasoline, and to observe migration in soil-bound Pb over time. We used Pb stable isotopes alongside sequential extractions to identify the Pb source as well as the mechanisms behind its persistence. Our findings show minimal deposition of atmospheric Pb, ranging from 3 to 30 ppm. Pb levels were stationary over time, maintaining highest concentrations in the organic horizon and decreasing with depth. The surficial distribution of Pb coupled with isotopic signatures suggest atmospheric-derived Pb deposition occurred in the rural Southern Piedmont, and that these trace amounts are immobile over decadal scales.
Wade, Anna, Daniel Richter, and Paul Heine (2019): Atmospheric Vs Geogenic: Using Long-Term Soil Experiments to Delineate between Lead (Pb) Sources in the Southern Piedmont. ASA-CSSA-SSSA International Annual Meeting, 10-13 Nov. 2019, San Antonio, Texas.
This Paper/Book acknowledges NSF CZO grant support.