Rheological aspects of the fuel oil spill in the Kerch Strait

This study investigates the physicochemical and rheological properties of fuel oil released during the December 2024 spill in the Kerch Strait, aiming to elucidate its behavior under varying environmental conditions and the mechanisms of its transformation in marine sediments. Comprehensive rheological measurements were performed on samples collected from the damaged tanker and from the seafloor, within a temperature range of 0-50 °C. All tested oils exhibited a pronounced transition from Newtonian to yield-stress flow behavior as the temperature dropped below 20 °C, indicating the formation of a structured dispersion phase. The rheological response of coastal sediments contaminated with fuel oil was also examined; these systems behaved as viscoplastic media capable of sustaining significant irreversible deformation under low shear stress. Furthermore, the addition of the nonionic surfactant Tween 80 was found to induce the formation of a time-dependent oil-in-water emulsion with a viscosity reduced by more than an order of magnitude compared to the original fuel oil, thereby enhancing its potential for dispersal and biodegradation. The mechanical strength and cohesion of the surface fuel layer were quantified, revealing temperature-dependent consolidation processes. Overall, the results provide a quantitative framework for understanding the temperature- and composition-controlled rheology of marine fuel oil residues, offering insights for the optimization of remediation strategies in cold marine environments.