Connecting arsenic rhizosphere geochemistry to system-scale fluxes
In my soil biogeochemistry PhD research, I worked with community urban agriculture groups and over 60 undergraduate interns to investigate an enticing proposed “green” remediation alternative to soil excavation, phytoextraction of arsenic-contaminated soils using the fern Pteris vittata. P. vittata absorbs arsenic from soil and stores it in its fronds. Harvesting arsenic-rich fronds removes arsenic from soil. In a field-scale mass balance I revealed for the first time substantial arsenic loss from the soil-plant system, likely due to leaching of arsenic from soil. In a novel meso- to micro-scale approach, I quantified arsenic leaching during P. vittata growth to show that the eco-physiological effects of arsenic tolerance and rhizosphere nutrient scavenging in P. vittata have ecosystem costs. I showed that as interest in P. vittata continues to grow, research and practice must shift from an extractive focus on arsenic uptake, to an ecological analysis of arsenic cycling in the soil-water-plant ecosystem.
Using knowledge of lead contaminant behavior to decrease risk during urban agriculture
Community organizers recognize that urban farming is a double-edged sword, potentially increasing food security but also exposure to lead, a ubiquitous urban soil contaminant and neurotoxin. I worked with urban agriculture organizations, California Department of Toxic Substances Control, and University of California Cooperative Extension specialists to developed and test a novel risk-based curriculum and extension factsheet to teach urban food producers to self-assess and decrease their risk from lead exposure. Reversing common paradigms of experts disseminating knowledge, the curriculum centers the philosophy that practitioners themselves can best assess their risk given the appropriate science. Current and future work will investigate methods to further lower barriers to soil sampling in marginalized communities. With collaborator Dr. Nic Jelinski (University of Minnesota), I am piloting use of a portable X-ray fluorescence instrument for rapid on-site soil analyses and pair spatial modeling and field surveys to optimize community-based soil sampling.
Characterizing nanoparticles that export iron from ocean seafloor to surface
I expand my research breadth with my current postdoctoral research. I work on iron geochemistry in marine environments, developing skills directly transferrable to metal reactivity in soils. With Brandy Toner (University of Minnesota) and collaborators at Woods Hole Oceanographic Institution, Brookhaven National Lab, and Lawrence Berkeley National Lab, I develop analytical approaches to characterize environmental nanoparticles and track iron export from hydrothermal plumes to open ocean waters and, eventually, surface phytoplankton communities.