| Liquefied natural gas(LNG)has begun to be used as the main energy source in more and more countries because of its clean and efficient characteristics.At present,the LNG industry has developed into the fastest growing energy industry in the world.China is gradually adjusting the energy structure and increasing the development and utilization of LNG in order to make up for the limited availability of traditional energy resources such as oil and coal,and ensure diversified energy supply.LNG pollution is relatively small,which has a certain role in promoting the improvement of China's environmental quality.In view of the natural geographical advantages of coastal areas,the construction of LNG projects has been selected in such areas.However,the waste generated during the construction and operation of the project will have a certain impact on the nearby sea environment,and further research is needed.In order to ensure the safety of the overall use of gas in Fujian Province and meet the development of gas demand in the medium and long term,the Luzhou LNG project came into being.Based on the background of the project,this article uses a numerical simulation method to analyze the natural conditions of the Zhangzhou waters,and uses five methods:hydrodynamic environment,siltation,seawater quality,marine ecology,and marine environmental sensitivity.The project construction will systematically study the impact on the surrounding sea area environment.The results show:(1)During the tidal period after the project,the flow direction of the ebb and flow fields is basically the same,and the flow velocity is relatively reduced.The flows of the flow field in the mid-tidal period between the high tide and the ebb tide were WS-EN and EN-WS,respectively.The flow rates were 60 cm/s and 55 cm/s,respectively.The maximum flow rate appears on the east side of Liuhui Village;in countercurrent rotation in Xinggu Bay,the flow velocity is relatively small;the near-shore velocity is smaller,generally less than 15cm/s.Compare the tide field during the tide,(2)The effect of scouring and silting before and after the project is basically the same,mainly due to a slight change in the amount of deposition on the southeast side of the project.The amount of erosion increases,and the increase is mainly 0.01m/a.There are siltations in the interior of Xinggu Bay,near the Jiluo Reef and the Outer Sea,and the sedimentation amounts are less than 0.04m/a,0.01m/a,and 0.01m/a,respectively.The southwestern side of Xinggu Bay and the southeast coast of Liuhui Village are in the state of erosion.The erosion amount is about 0.02m/a and 0.02-0.05m/a.(3)Comparing the three construction methods,the suspended sediment concentration increments ranged from 0.1 to 3.9 km~2,and the suspended sludge exceeded the minimum multiple of 0.1,with a maximum of 9 or more.The maximum area affected by the temperature drop of 1°C in the cold drainage of the project is approximately 6.2hm~2,the maximum area affected by the temperature drop at 2°C is approximately 1.9hm~2,the maximum area affected by the temperature drop at 3°C is approximately 0.6hm~2,and the temperature drop at 4°C affects the maximum area About 0.2hm~2,the farthest impact distance is 0.32km.The scope of residual chlorine diffusion in cold water drainage is mainly in the direction of main flow.Because the current water quality standard does not specify the limit value of residual chlorine,this paper based on the existing research results 0.02mg/L is the safety threshold,so take 0.02mg/L To evaluate the limits,the impact of residual chlorine on the environment is within the discharge range of 936m.(4)According to the calculation result of suspended sediment increase caused by riprap,dredging in the harbor,and caisson sand filling,the porphyra cultivation near the project is located in the range of 10-100mg/L of suspended solids.Under the conditions of migration of this part of the seaweed breeding facilities,the increase in suspended solids concentration has a very limited impact on seaweed farming activities.(5)Comprehensive assessment of impacts on marine ecological environment from the aspects of roll loading effect,cold drainage and residual chlorine diffusion,calculation of the impact on the marine ecological and fishery resources during the construction period,and a calculated loss of approximately 1.468.63 million yuan over three years.(6)Select important fish habitats,culture areas,fishing areas,Chinese white dolphins,and nearby waterways as sensitive targets.Analysis shows that cold drainage,warm water drainage,etc.have no significant effect on fish spawning and feeding,and strict measures are adopted.Implementation can effectively reduce the adverse effects of project construction on the navigable safety of the above-mentioned channels. |
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