Marine sediment remediation under complex contamination: State-of-the-art and perspectives on PAHs, PCBs, and heavy metals

Abstract

Marine sediments contaminated with persistent organic and inorganic pollutants represent a major environmental challenge. Polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and heavy metals frequently coexist, exhibiting high persistence, bioaccumulation potential, and toxicity to benthic ecosystems and human health. Despite the wide range of available remediation technologies, most approaches are designed and evaluated for single contaminant classes, limiting their effectiveness in complex co-contaminated systems. This review critically examines both in-situ and ex-situ remediation strategies for marine sediments, with particular emphasis on their applicability to mixed organic-inorganic contamination. Rather than reiterating individual advantages and drawbacks, the review compares technologies in terms of removal efficiency, operational timescales, costs, environmental impacts, and long-term reliability. The analysis highlights that while in-situ techniques reduce sediment disturbance and ecosystem disruption, and ex-situ methods offer higher control and removal efficiency, neither category alone is sufficient for addressing multi-contaminant scenarios. A central outcome of this review is the identification of integrated and hybrid remediation approaches, combining physical, chemical, and biological processes, as the most promising solutions for complex sediment pollution. Recent developments in reactive materials, environmentally friendly washing agents, and biologically enhanced treatments are discussed. Finally, future perspectives emphasize the integration of sediment remediation with wastewater management and sediment valorization within circular-economy frameworks, providing guidance for research, policy development, and sustainable remediation practice.