Hurricanes and turbulent floods threaten arsenic-contaminated coastal soils and vulnerable communities

Authors: IZADI, LAYLA - The University Of Texas At Dallas; TAMADONI, AMIN - Texas Tech University; SIEBECKER, MATTHEW - Texas Tech University; SRICHAROENVECH, PLYAPAS - University Of Delaware; BARRETO, MATHEUS - University Of Delaware; Fischel, Matthew; TAPPERO, RYAN - Brookhaven National Laboratory; SPARKS, DONALD - University Of Delaware

Submitted to: Environmental International
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/16/2025
Publication Date: 5/8/2025
Citation: Izadi, L.N., Tamadoni, A., Siebecker, M., Sricharoenvech, P., Barreto, M., Fischel, M.H., Tappero, R., Sparks, D. 2025. Hurricanes and turbulent floods threaten arsenic-contaminated coastal soils and vulnerable communities. Environmental International. 200. Article e109479. https://doi.org/10.1016/j.envint.2025.109479.
DOI: https://doi.org/10.1016/j.envint.2025.109479

Interpretive Summary: Rising ocean water levels can expose polluted soils to flooding and move the pollution into areas where it can harm human health. In Delaware, one of these polluted sites has high amounts of toxic arsenic; however, it is unknown how future sea level rise will impact the arsenic, which exists in many forms in the environment, each with different levels of harmfulness. In this study, we simulated sea level rise and flooding events in a special chamber mimicking natural flooding. The experiments showed arsenic was released from the soil and transported into the water, which can lead to greater human exposure and harm. These results will help inform risk management decisions about whether to clean up contaminated sites vulnerable to sea level rise. It will also inform policymakers and human health experts on future risks and steps to reduce possible harm.

Technical Abstract: Coastal environments, particularly those adjacent to Superfund sites, are at increased risk of contaminant release during natural disasters, posing serious threats to nearby communities. To investigate this issue, we employed an advanced laboratory flood simulator to impose arsenic-contaminated sediments to turbulent flooding events. We further monitored changes in arsenic collocation and solid-phase speciation using advanced synchrotron radiation-based techniques to understand the impacts of flooding on arsenic mobility. Our results demonstrate that turbulent conditions significantly enhance the resuspension of arsenic-rich sediments, resulting in increased arsenic release into the water. This mobilization is driven by the erosion of the reduced sediments and the redox-mediated transformation and dissolution of Fe and Mn (oxyhydr) oxides, which promote the release of As(III). We found that arsenic speciation on resuspended particles is closely tied to shear stress, with As(V) prevailing at low stress and the more toxic As(III) dominating at higher stress levels. In the post-erosion phase, solid-phase As(III) decreased while dissolved As(III) increased, indicating ongoing desorption. The persistence of multiple arsenic species on resuspended particles marks them as potential long-range transport vectors. Thus, the environmental impact of flooding and sediment resuspension extends beyond the event itself, raising longer-term concerns for arsenic mobility. Our comprehensive geospatial analysis revealed substantial overlap between arsenic-contaminated soils and regions at high risk of flooding and hurricanes across the conterminous United States. This overlap disproportionately impacts economically disadvantaged and marginalized communities. Approximately 40 million Americans reside within 10 kilometers of these high-risk contaminated zones, with nearly 28 million exposed to hurricane threats and around 18 million vulnerable to flooding risks. Alarmingly, over 40% of those affected by hurricanes and 33% of those impacted by flooding belong to underrepresented minority and low-income populations. These findings highlight the urgent need for targeted mitigation strategies to protect public health and address environmental justice concerns.