浓盐水排海对渤海湾盐度分布的影响预测

利用MIKE21模型进行浓海水排放对渤海湾海水盐度分布影响的研究,分别以天津大港和河北黄骅两地建设海水淡化工程所排放的浓海水量为输入条件,模拟预测了渤海湾不同潮期和工程规模浓海水排放的扩散状况。结果显示,浓海水的稀释扩散受潮流的影响较大,总体来讲小潮低潮时排海的浓海水稀释扩散效果最差,大潮低潮和小潮高潮时次之,大潮高潮时扩散效果最好;建设10×104 t/d以下的海水淡化工程浓海水排海对周围海区的盐度影响不显著,建设50×104 t/d以上的大型海水淡化工程时,小潮低潮时盐度升高波及面积最大,高于背景值1.5 PSU的面积为31 km2,最远离岸距离为6.74 km,所以大规模海水淡化工程的选址、浓海水排海方式均要进行合理规划、选择,尽可能降低其对海洋环境的不利影响。

Impact prediction of the concentrated saltwater discharged from desalination plant on the distribution of the salinity in Bohai bay

The effects of the discharge of the concentrated seawater on the distribution of seawater salinity were investigated using MIKE21 model.With the discharge amounts of the concentrated seawater from Tianjin Dagang and Hebei Huanghua desalination projects as the input conditions, the diffusion of the discharged concentrated seawater in Bohai bay from the desalination projects with different scales during different tide periods was simulated and predicted.The results demonstrated that the dilution of the concentrated seawater was mainly influenced by the ocean currents during different tide periods.Overall, the high water spring tide showed the best dilution and diffusion effects, followed by high water neap tide, the low water neap tide was the worst.The concentrated seawater from the seawater desalination project with the output scale no greater than 10×104 t/d had no significant effect on the sea salinity of the surrounding sea areas.However, the concentrated seawater from the desalination projects with the scales greater than 50×104 t/d could lead to the largest sea area with the increased salinity during low water neat tides.In addition, the sea area with the salinity 1.5 PSU higher than background value and the maximum offshore distance were 31 km2 and 6.48 km, respectively.Therefore, the site selection of large-scale desalination project and the discharge of the concentrated seawater should be properly planed to minimize their detrimental effects on the marine environment.