Project Summary (2022-2027)

Abandoned uranium mines (AUM) situated on the tribal lands of the Navajo Nation and Laguna Pueblo represent a major source of environmental contamination that threatens public health as a result of mobilization of toxic metals mixtures bearing uranium (U), vanadium (V), copper (Cu), and arsenic (As). The transport of toxic metals mixtures into the air in nanoparticulate form, and the subsequent potential for inhalational and ingestion exposures, has never been investigated in a rigorous manner. Researchers with this project are investigating the potential exposure hazards to toxic metals mixtures in nanoparticulates resulting from inhalation and ingestion via contaminated agricultural crops from AUM sites located on Navajo Nation and Laguna Pueblo tribal lands in Arizona and New Mexico.

The project addresses the following specific aims:

• Understanding the physicochemical characteristics and distribution of metals mixtures in a range of environmental samples, including mine wastes, soils (agricultural and background) and airborne particulates around AUM and modeling their transport and deposition by wind into neighboring communities
• Assessing the uptake of metals into plants on agricultural soils adjacent to abandoned mine sites to understand if airborne metals-bearing particulates present a potential exposure risk
• Understanding the mechanisms of particulate assimilation into agricultural crops through their root and folial system by developing a process model for the resuspension and transport of metal-bearing PM from AUM sites to estimate exposure risks for nearby vulnerable communities. The process model includes a) ascertaining the particle size distributions and mineralogic characteristics of metal-bearing PM originating from AUM sites and the exposure potential to vulnerable populations living in the regional airshed under varied meteorological conditions; and b) conducting source-receptor modeling for the region, integrating information from three performance sites and deriving long-term estimates for Navajo community members.

The research is using state-of-the-art monitoring, chemical, imaging, and atmospheric modeling techniques to provide a comprehensive dataset on the concentrations, speciation, valence, solubility, etc., of ultrafine-grained PM nanoparticle scale that are essential to evaluate the potential toxicity and inhalation exposure risk for PM. The results will reduce uncertainty regarding the metal content, exposure concentrations, and sources of AUM-related PM exposures in risk reduction strategies.