Potential Application of Melanins for Restoring War-affected Soils in Ukraine

Abstract

The extensive environmental degradation of terrestrial ecosystems, particularly agricultural soils, in Ukraine following the Russian full-scale invasion necessitates the rapid development of innovative and scalable remediation strategies. Conventional soil restoration methodologies are frequently constrained by factors such as cost, labor intensity, and limited applicability across the vast and complex areas afflicted by military activities. This manuscript presents a comprehensive synthesis of current knowledge regarding melanin, a ubiquitous biopolymer, positing its substantial potential as a sustainable and efficacious soil amendment for the rehabilitation of war-affected landscapes. Melanin‘s diverse biogenic origins in soil, predominantly from microbial biosynthesis pathways, alongside its accumulation from decomposed organic matter, underscore its widespread natural availability. We elucidate its critical properties and ecological functions, including its exceptional capacity for heavy metal and radionuclide sequestration through complexation with its abundant phenolic and carboxylic groups. Furthermore, melanin‘s contribution to long-term soil organic matter stabilization, its potent antioxidant and UV-shielding capabilities, and its role in modulating beneficial microorganism-plant interactions are critically discussed, highlighting its multifaceted contribution to soil health and resilience. The inherent attributes of melanin inform its potential applications in soil remediation, ranging from the direct application of melanogenic microorganisms for contaminant immobilization and enhanced revegetation to the development of engineered melanin-based materials for targeted pollutant removal. While acknowledging the significant promise, challenges such as optimizing its in-situ mobility, ensuring scalable and cost-effective production, and comprehensively assessing long-term ecological impacts remain pertinent research avenues. Future research should focus on the synergistic integration of melanin with complementary soil amendments, particularly silicon-based compounds, which can provide additional benefits in terms of structural stability and plant stress tolerance, thereby fostering a holistic approach to post-conflict ecological restoration.