249-4 Compounding Hazards: Climate Change, Toxic Layering, and Cross-Border Solutions in Environmental Justice Mining Communities

Session: Emerging Contaminants: Geochemical Insights and Impacts on Human and Environmental Health

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In 2021, wildfires/flash floods heavily impacted several underserved rural communities in AZ near active/legacy mines, which worsened potential contaminant exposures. Mining operations are linked to environmental contamination, with many waste sites left unrehabilitated. Fire can alter the physical/chemical/biogeochemical properties of the soil/surface materials, and potentially lead to the (re)mobilization of contaminants. The extent of post-disaster contamination in AZ’s mining areas remains unassessed and community members have raised concerns. This study analyzed sediments, soil, and dust samples for metal(loid)s, Polynuclear Aromatic Hydrocarbons (PAH), Dioxins, and/or Per- and polyfluoroalkyl substances (PFAS) to assess contaminant release following climate extremes events, with a focus on exposure pathways, cumulative risks, and climate-related geohazards. To dissolve social barriers, a participatory research approach was implemented in partnership with the local/county government to build human capacity through empowerment education and community science and ensure community-centered data report back and intervention/prevention strategies. Representative partners and participants were engaged in study phases, e.g., selection of sampling sites and hypothesis generation. Research was managed in cooperation with the established “Cobre Valley Community Environmental Advisory Board”, members ranging from local/county/state government agencies to residents. Results from this work highlights how wildfires and flash flooding introduced new contaminants and remobilized legacy pollutants. 30% and 25% of outdoor dust and household soil, respectively were aligned with the wildfire Pb isotopic ratio.  Additionally, there were significantly greater concentrations of long-chain PFAS in the residential sites impacted by postfire floods and the co-occurrence of metal(loid)s with PFAS highlights mining’s potential role in PFAS contamination. In general, PFAS and PAHs concentrations were greater in flooded areas and most of the PAHs came from combustion, showing potential, partial wildfire contribution. Probabilistic Bayesian risk assessments estimate unacceptable health risks for residents, especially youth. Action is needed to address the compounded hazards posed by chemical mixtures and climate change and protect vulnerable populations. This cross-boundary and translational approach has led to individual/community intervention/prevention efforts, ongoing/new collaborations, data sharing across agencies, and additional testing/cleanup efforts.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-7474

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