The long-term status of petroleum hydrocarbons in both seawater and sediment contaminated by the Dalian New Port oil spill has been investigated since 2010. Seawater recovery is relatively swift and is complete within two years, while oil contamination persists in the coastal sediments for several years. Because of the slow degradation and low mobility in sediments, they serve as long-term reservoirs for residual oils. The erosion of sediments into the water column leads to an abrupt increase in hydrocarbons during storms. The cumulative results of hydrodynamic transport and ongoing industrial emissions lead to a spatial shift of hot spots with high petroleum hydrocarbon concentrations from the spill site to the inner corner of the bay. In addition to continuous petroleum hydrocarbon emissions from contiguous coastal outfalls, the regional oil contamination will persist indefinitely. The research provides comprehensive information for years to come to evaluate the long-term damage and multiphase medium impacts of a large oil spill.

Spatial–seasonal variations in dissolved heavy metals in surface seawater were analyzed based on surveys at 87 sampling sites and water samples from six rivers across Liaodong Bay. The concentrations of copper (Cu), lead (Pb), cadmium (Cd), and zinc (Zn) had ranges of 0.20–40.00 (5.45 ± 5.67), 0.51–33.64 (4.68 ± 3.93), 0.03–13.47 (2.22 ± 2.01), and 0.50–80.09 μg/L (14.22 ± 16.32), respectively, throughout the four seasons of 2020. The trace metal concentration showed a spatial gradient of high to low from river to estuary and from inshore to offshore areas. A combination of pollution levels and marine sensitivity was employed to assess the pollution degree of the heavy metals. As a whole, the single pollution factors of trace metals in Liaodong Bay were ranged in the order Pb > Zn > Cu > Cd. The total pollution degree was relatively high in autumn and summer due to increased riverine inputs after the rainy season, while relatively low in spring and winter. These findings provide baseline data for future targeting policies to protect marine environments in Liaodong Bay.

This study investigates the effect of nonlinear strengths of sloshing on damping performance of side-mounted perforated baffles and discusses the influence of perforated baffles on resonance characteristics of sloshing flow. The model performance score is adopted to evaluate the nonlinear strength of water sloshing. A microscopic model and a volume-averaged macroscopic model are established to simulate the sloshing flow in a two-dimensional (2D) water tank with perforated baffles. In addition, a series of experimental tests are conducted to validate the numerical model. By analyzing the effects of nonlinear strength on damping performance of perforated baffles, a critical nonlinear strength of Reynolds number (Re) equal to 56 000 is obtained: For nonlinear strength smaller than critical nonlinear strength, the damping effect due to perforated baffles is mainly achieved by shifting the energy density to the excitation frequency; for nonlinear strength enhanced to the critical value, further increasing nonlinear strength shows slight influence on damping performance, and an additional increase in sloshing response occurred due to violent interaction between baffles and fluid flow. Importantly, the Reynolds number corresponding to the critical nonlinear strength is independent of the properties of perforated baffles, such as porosity and mounted form. Furthermore, the resonance effect of sloshing flow can be significantly weakened with an increasing blockage of perforated baffles, accompanying negative growth of maximum force amplitude on bulkhead.

A numerical model of mussel farm in current was developed to analyse its hydrodynamic performance, in which the mussel dropper was simulated as a porous media. The Reynolds-Average Naiver–Stokes (RANS) equation was applied to simulate the flow around the mussel farm, and the Darcy–Forchheimer equation was adopted to consider the effect of the porous media. A slew of physical model tests were used to validate the numerical model. The results indicate that our numerical model is appropriate to investigate the hydrodynamic behaviour of the mussel droppers in current. The hydrodynamic performance of mussel farms in different water depths was numerically investigated. In addition, the influence of the mussel dropper density and the oblique current was analysed comprehensively. The results indicate that the shielding effect of mussel droppers is increased with the increasing water depth.