Black sands of Iwo Jima: How the past can improve the future of warfare

Within the iconic black sands of Iwo Jima (Figure 1) lies an environmental story that has remained untold—until now. New research reveals that the soil of this Pacific Island still harbors toxic remnants of wartime activities, posing ongoing risks to the environment and public health. The research focused on heavy metal contamination in Iwo Jima’s soil, identifying elevated levels of lead (Pb), mercury (Hg), chromium (Cr), copper (Cu), and zinc (Zn)(Figure 2).

These findings underscore the long-lasting environmental impacts of one of the most intense battles of WWII, where U.S. Marines and Japanese forces clashed in February 1945. Using X-ray fluorescence (XRF) analysis, soil samples (Figure 3) from Iwo Jima’s Invasion Beach were examined and compared with control samples from non-affected regions in Malaysia and La Réunion. In addition, this study also examined how these metals interact dynamically with their environment; for instance, changes in soil pH or weathering can re-mobilize contaminants, extending their reach and impact.

The analysis revealed significantly elevated concentrations of heavy metals in Iwo Jima’s soil compared to the background samples, frequently surpassing health risk thresholds (Table 1). The island, heavily impacted by bombings, also known as bombturbation, vehicular activity, and construction during wartime, became a repository for pollutants from military equipment and explosives (Figure 4).

Further complicating the situation, Iwo Jima’s volcanic geology, naturally rich in metals, has likely intensified the contamination, creating a unique and challenging environmental scenario.

Statistical insights

The analysis of heavy metal concentrations in Iwo Jima’s soils reveals concerning levels, particularly when compared to established human health hazard thresholds (Figure 2, Table 1). For instance, mercury concentrations were far above the World Health Organization’s safety guideline of 0.004 mg/kg, raising red flags about potential environmental and health risks stemming from wartime activities. Mercury concentrations in Iwo Jima’s samples significantly exceeded safe limits for human health, over 1000 times higher at 23 mg/kg^-1.

Similarly, lead concentrations in some samples approached or exceeded the U.S. Environmental Protection Agency’s threshold of 50-200 mg/kg for residential soils, highlighting a potential risk for long-term exposure for adults and children. When analysing all the elements collectively, a statistical test designed to evaluate multiple variables simultaneously found significant differences, indicating that Iwo Jima’s soil’s overall heavy metal profile is distinctly higher than the background locations (Figure 2).

The historical connection & global implications

Iwo Jima, now restricted to civilian access and used solely by Japanese and U.S. military forces, highlights the ongoing risks associated with contaminated soils in war-affected regions. Soil samples are often collected by visiting military personnel, raising concerns about inadequate education and safety protocols to mitigate contamination risks.

This issue is not unique to Iwo Jima. Conflict zones worldwide, from Europe’s WWI battlefields to modern war-torn areas like Ukraine and Gaza, face similar challenges, with residues from armaments affecting urban and agricultural lands.

The absence of universal global standards for heavy metal contamination in soil further complicates remediation efforts. Standards are typically set locally based on factors such as industrial history, land use, and regional environmental conditions, leading to significant variability. Health-based thresholds for heavy metal concentrations provide a practical framework for addressing contamination, enabling policymakers to prioritise remediation, develop regulations, and educate communities on exposure risks. Such approaches bridge scientific research and public health, facilitating actionable strategies to protect both the environment and human well-being.

Shaping a sustainable future amid the legacy of war

While the past cannot be undone, steps can be taken to mitigate future environmental impacts of conflict. This study highlights the urgency of adopting environmentally conscious military technologies to reduce ecological harm. Precision-guided munitions can limit damage to specific targets, while biodegradable materials in ammunition may prevent long-term soil contamination. Embracing renewable energy sources and energy-efficient weapon systems further aligns military practices with sustainability goals. Incorporating sustainable manufacturing on the frontlines from 3D printing can enhance resource efficiency and reduce waste in frontline operations.

Addressing the environmental consequences of WWII provides valuable lessons for tackling similar challenges worldwide. Policymakers are encouraged to enforce stricter regulations on contaminant-producing materials, establish protocols for remediating war-affected sites, and update hazard thresholds based on contemporary health research. Public education remains vital for raising awareness among civilians and military personnel about the environmental toll of warfare and the necessity of sustainable practices.

Remediating historically or culturally significant sites like Iwo Jima presents unique challenges. Large-scale cleanup operations risk disrupting the integrity of these areas, while resource-limited regions face significant barriers to implementing effective remediation strategies. Against this backdrop, prioritising the development of environmentally sustainable weapons and military technologies offers a practical path forward.

If complete disarmament is unattainable, minimising the ecological footprint of military activities becomes crucial. By balancing environmental responsibility with the preservation of cultural heritage and resource limitations, global efforts can help address the enduring environmental costs of conflict while fostering a more sustainable future.

Recommendations

1. Standardise and enforce environmental guidelines for conflict zones
   Governments and international organizations should establish standards for heavy metal contamination and remediation in war-affected soils. These guidelines should include baseline health thresholds, monitoring protocols, and mandatory reporting requirements to ensure national uniformity and fairness. Collaborative frameworks like a global treaty on post-conflict environmental cleanup could be developed to hold parties accountable.
2. Invest in research and development of sustainable military technologies
   Military and defense industries should prioritize funding and adoption of environmentally friendly technologies. This includes developing biodegradable munitions, precision-targeted weapon systems to minimize area damage and 3D printing for sustainable front-line manufacturing. Incentives such as tax benefits or grants could be introduced for defense contractors investing in eco-friendly innovations.
3. Enhance international collaboration for site remediation and capacity building
   Governments should lead initiatives for shared knowledge and resources in remediating contaminated areas. International bodies could provide technical expertise, funding, and training programs for local communities to tackle pollution effectively. Establishing a global fund dedicated to cleaning war-impacted regions could support resource-limited nations in addressing environmental justice.

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Journal reference

Shuster, C. A. (2024). Black Sands of Iwo Jima: How the Past Can Improve the Future of Warfare. Environmental Forensics, 1–19. https://doi.org/10.1080/15275922.2024.2431317