| Along with the accelerating process of economy,hazardous chemical productions and consumptions increase rapidly,and the varieties update constantly.Hazardous chemical enterprises are located in the coastal area mostly, coupling with lack of government regulation,poor corporate governance,lack of sound laws and regulations that will posing a great threat to offshore waters.As a typical semi-closed bay in north China,Dalian Bay scattered many hazardous chemical enterprises around the coast.It is require to know the trend and diffusion of hazardous chemicals when leakage accident happens in time,and that can be used to providing technical support for the prevention of leakage accident and emergency disposal.Specific tasks and conclusions of this paper are as follows:(1)Based on seabed based platform,we continuously observed ocean currents and bottom temperature in Dalian Bay,and then analyzed hydrodynamic characteristics by means of spectral and harmonic analysis.The results show that the tide is regular and tidal current is an irregular semidiurnal one.On the whole,the residual currents are strong in the surface layer, with the velocities of 5 cm/s, and the direction are southwestward.While the residual currents are weaker under the surface layer at station outside and inside station of Dalian Bay,and the direction are southwestward.(2) In this paper,coastline and topography were depicted more detail than before,and then ROMS model was used to simulate tidal current field and water exchange capacity.The simulation results show that the flow in the mouth of Dalian Bay can be characterized by obvious traveling wave that its maximum velocity occurred in the moment of high tide and low tide.(3)Investigation and evaluation have been done that including about chemicals using situation,the main potential risks and potential pollution sources.According to this,the area where leakage may occur surrounding Dalian Bay are Oil Wharf area,the western of Heshang Island,the Development Zone,and Dagushan Petrochemical Park.Thus,pollution sources will be incorporated into the following six:D29 and D42 at Oil Wharf area,D53 and D60 at the western of Heshang Island,K01 at the Development Zone and G01 at Dagushan petrochemical park.(4) Numerical simulation was used to study the transport and diffusion process of hazardous chemicals leaking in Dalian Bay and Dagushan respectively.The simulation results showed that when leakage accident happens,the hazardous chemicals will be taken role of tidal currents,and will assume reciprocating diffusion in the area.The influence of pollution source surrounding source itself, and with the increasing of distance,it will decrease gradually.Under the circumstance of leaking at the same time,the leakage intensity of hazardous chemicals play a significant influence on the diffusion range and area.The detailed analysis of seasonal indicates that pollutant will be diffused to north when the source is located in the south of Dalian Bay in summer,while will be diffused to south in winter.(5)According to the results of this research, this paper proposed to relocate petrochemical enterprises from Oil Wharf area,the western of Heshang Island and the Development Zone to Dagushan Petrochemical Park.It’s advantageous to strengthen the supervision of government regulators through the centralized management, and is beneficial for providing safety guidance to the same type enterprises uniformly which can avoid the leakage accident effectively.In addition,when the accident happened,it need to cut off the leak source in time,and to strengthen monitor according to the diffusion of seasonal condition,and to set up barriers to reduce the pollution degree and range. |
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