Stanford University

*** Ph.D. Thesis/ Oral Defense ***

Rooted in Community: Unearthing the Impacts of Soil Heavy Metal Contamination in Urban Gardens and Implications for Environmental Justice

Alexis Wilson

Friday, May 17th, 1:00pm PST

Mitchell Building Hartley Conference Center

Department of Earth System Science

Advisors:  Scott Fendorf and Chris Field

Urban gardens are crucial for promoting community resilience, increasing access to natural spaces, and combating food insecurity. However, urban gardens can potentially expose people to toxic heavy metals, like lead, cadmium, chromium, and arsenic through interactions with contaminated soil, which can have significant health impacts. This dissertation uses an interdisciplinary approach that integrates soil biogeochemical analyses, qualitative data collection, Environmental Justice principles, and Community Based Participatory Research (CBPR), to address this public health concern. In Chapter 2, we employ a mixed-methods approach in Palo Alto and East Palo Alto, CA which demonstrates the significant impact access to soil testing and information has on urban gardeners’ behavior, knowledge, and level of concern of soil contamination. In Chapter 3, in partnership with the Oakland Unified School District, we detected and remediated soil lead contamination in school gardens in East Oakland, CA. In Chapter 4, we measure heavy metal concentrations in consumer soil products, industrially produced compost, and free soil advertised online to identify sources of lead contaminated material imported to urban gardens. Finally, Chapter 5 presents a novel framework, C.I.R.C.L.E, and eight strategic approaches for implementing CBPR in the Earth and Environmental Sciences. The impact of environmental pollution is not felt equally; communities of color and low-income communities are disproportionately burdened, so throughout this dissertation we assess the environmental justice implications of our findings.