Bagaiev A. Three-dimensional model of transport and transformation of the anthropogenic persistent organochlorine contamination on the Black Sea shelf

The thesis is devoted to the three-dimensional mathematical modeling transport and transformation of an anthropogenic persistent organochlorine contamination, such as polychlorinated biphenyls (PCBs). Numerical three-block model is implemented due to one-way coupling of the full physics hydrodynamic block with the modules of transport and transformation of detritus and PCBs. Gravitational settling of detritus, first-order decomposition rate and sign-changing fluxes in the water–sediment interface are taken into account to describe concentration of detritus. The third block includes three state variables: PCB concentration in solution, PCB concentration on the particles of detritus and PCB concentration in the upper layer of sediment. Adsorption and desorption as well as the reversible PCB fluxes on the bottom are taken into consideration. The 20-day simulation is spun up to reconstruct an accident spill of 4 kg of PCBs in the Danube Mouth zone in spring. A comparative assessment of pollution flows in the system is provided and its mass budget is analyzed. The model developed is modified to evaluate efficiency of introducing an artificial active sorbent as a countermeasure to fight the accident-related dispersion of PCBs. The governing system of equations is supplemented with the equations for active sorbent concentration and PCB concentration on the active sorbent. Natural adsorption on detritus passes ahead adsorption on the artificial sorbent due to the abundance of detritus.