NSF Award
2422824
High abundance of metals in the natural environment is a bit of a double-edged sword – metals are in greater demand now more than ever as we transition to renewable energy sources, so locating resources for extraction is economically important, yet at certain levels many of these metals may be damaging to the environment or toxic to plants, animals, and humans. Many metals can easily move from soil into plant material, where they can accumulate to a much greater extent, sometimes resulting in incredibly high quantities in plants. Here, plants may act as an entry point for metals to enter the food chain, posing serious environmental and human health risks, or they may allow for cost-effective extraction, helping clean up areas that have been contaminated while providing some information about what may be happening geologically, below the surface. This research focuses on one very toxic element, thallium (Tl), that is often associated with much more valuable metals, such as gold, and that can be taken up by plants quite efficiently. The project aims to use greenhouse experiments with plants grown in Tl-spiked soils to understand how underlying geology may affect plant metal signatures and how that information can be used for both metal exploration and environmental remediation. Throughout the study, a podcast will be published to highlight the societal implications of this research, and to introduce the public to “the person behind the science.”<br/><br/>Thallium can accumulate, and in some cases hyperaccumulate, in a wide variety of plants with measurable biologically-induced isotopic fractionation during bioaccumulation, which may be at least partially controlled by underlying geology. This work will use two greenhouse trials of Brassica juncea (B. juncea), or brown mustard, grown in substrates with differing Tl redox conditions and distinctive starting Tl geochemical compositions to evaluate how accurately biogeochemical signatures reflect below-ground geogenic sources. After growth, each B. juncea plant will be split into specific plant parts (roots, stem, leaves, flowers, seed pods), processed, and analyzed for both trace metal concentrations and Tl isotopic compositions. These data will allow for calculation of the contribution of Tl from underlying geologic sources to the above-ground plant parts and quantification of how well various plant parts reflect original metal sources. This research will contribute to environmental and health-related planning and serve as a new tool for understanding heavy metal (re)distribution during anthropogenic and natural processes while establishing applications and potential limitations of utilizing biogeochemical signatures for metal exploration and environmental remediation.<br/><br/>This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
