Deep-Sea Mining Plume Mitigation: A Geotechnical Perspective on Sediment Behavior

Deep-sea mining is increasingly viewed as a potential source of critical metals needed for the global energy transition, including those used in batteries, electric mobility, renewable power systems, and grid infrastructure. The deep-sea mining faces a critical environmental challenge: sediment plumes generated by collector vehicles disturbing the seabed. These plumes, composed of fine-grained deep-sea clays, can persist for extended periods and disperse across vast oceanic areas, posing a threat to benthic ecosystems. Current plume management predominantly adopts a reactive approach, focusing on monitoring and containment rather than addressing the root cause. This paper argues that effective plume control necessitates an understanding and active management of the geotechnical properties of deep-sea sediments. We find that the unique characteristics of deep-sea sediments, including high water content, fine particle size, flocculated microstructure, high surface activity, and the interactions between particles and hydrodynamics, are not only the origin of the plume issue but also the key to its resolution. Targeting three fundamental pathways, namely reducing particle entrainment, limiting transport range, and shortening suspension duration, we propose a comprehensive mitigation framework grounded in geotechnical principles. We conclude that a transition from passive monitoring to proactive particle-level intervention is essential for reducing plume-related environmental risks and for enabling the environmentally and commercially sustainable extraction of energy-critical metals from the deep sea.