Numerical modelling of temporal and spatial patterns of petroleum hydrocarbons concentration in the Bohai Sea

Highlights: • PHs loadings and measured concentration in the Bohai Sea are presented. • A coupled hydrodynamic/transport model is developed to simulate the PHs level evolution. • The genetic algorithm is employed to optimize model parameters. • Simulated and measured results show good agreement. • Several factors impacting PHs level distribution are analyzed. - Abstract: The discharge of petroleum hydrocarbons (PHs; ~ 10,000 tons annually) into the Bohai Sea, a shallow inland sea in China, presents a serious threat to the marine environment. To evaluate the effects of PHs pollution and estimate the corresponding environmental capacity, we have developed a genetic algorithm-based coupled hydrodynamic/transport for simulating PHs concentration evolution and distribution from July 2006 to October 2007, with the predicted values being in good agreement with monitoring results. Importantly, the mean PHs concentrations and seasonal concentration variations were primarily determined by external loading, i.e., currents were shown to drive PHs transport, reconfigure local PHs patterns, and increase PHs concentration in water masses, even at large distances from discharge sources. The developed model could realistically simulate PHs distribution and evolution, thus being a useful tool for estimating the seasonal environmental capacity of PHs.