LEAD FRACTIONATION AFTER UPTAKE BY BRASSICA JUNCEA (BROWN MUSTARD)

Despite efforts to limit its introduction into the environment, lead (Pb) remains a concerning pollutant for many communities. The utilization of plants as phytostabilizers has drawn interest to control the spread of Pb contamination as an alternative to other more costly and invasive remediation techniques. Additionally, Pb within these plants may be analyzed to detect unique isotopic signatures related to certain contamination sources, providing a way to trace Pb within the soil back to its origin. However, the behavior of Pb during plant uptake is still poorly understood, particularly as it pertains to plant isotopic fractionation patterns and whether they can accurately reflect unique sources of contamination. This project aims to characterize these changes in plant Pb ratios during uptake and to determine the feasibility of biological isotopic fingerprinting for Pb sourcing.

For this project, Brassica juncea, a known accumulator of Pb, was grown in a controlled greenhouse environment. Twenty individuals were cultivated, with three trials grown in substrates amended with Pb from different sources (natural ore, anthropogenic, and mixed) as well as a control with no Pb amendment. After maturing, plants were harvested, split into individual parts, and analyzed for both Pb concentrations and isotopic composition. These ongoing analyses aim to determine patterns of both relative Pb content and fractionation between different parts of the plant. If the original isotopic signals seen in the substrate can be ascertained after accounting for biological fractionation, and there are noticeable differences in isotope ratios between plants of different trials, then using B. juncea as an extractor for Pb source fingerprinting could be feasible.