深層海水模廠排放水對於海域生態影響及海域沃化可行性之評估硏究
- 標題
- 深層海水模廠排放水對於海域生態影響及海域沃化可行性之評估硏究
- 作者
- 環境與發展基金會
- 文件屬性
- 圖書出版
- 知識分類
- 基礎研究
- 出版年
- 2011
- 出版社
- 經濟部水利署
- 點閱數
- 2678
摘要
深層海水低溫利用及多目標研發模廠預計99年年中完工及運轉，抽取之深層海水經過廠區運用後，餘水以預設之排水管，排放回海中50公尺水深處。本計畫目的為評估模廠排放水可能對當地環境之影響，以作為模廠管理及未來深層海水園區開發之參考。因深層海水富含營養鹽類，排放深層海水，是否具有促進浮游生物增值，進而促進海洋生物聚集，達到海域沃化的效果。本計畫初步以數值模擬排放水之擴散，配合模廠運轉前後當地之水質及海域生態基本資料，進行台東深層海水模廠排水對於海域沃化的可行性研究，爰擬委託辦理本計畫。The purpose of this research is to evaluate the possible influence on marine fertilization and ecological system after discharging the effluent coming out of the pilot plants of DOW utilization to the neighboring sea. The nutrient-rich DOW will be discharged after its cold energy and nutrient being used up. The effluent may increase the growth of phytoplankton and then gathers the marine organism to build up a zone of marine fertilization. The numerical model simulations on the flow field of Tai-dong area and the advection-dispersion of conservative substances are conducted. The works on in-situ ecological samplings are also conducted to further estimate the feasibility of marine fertilization. The result of numerical model simulation shows that the current in Tai-dong area is mainly influenced by Kuroshio other than tidal constituents. The dominant current in Ji-Ben area will be northbound when Kuroshio flow through the waterway between the southern tip of Taiwan and the Orchid Island. The dominant current of Ji-Ben area will be southbound if the main stream of the Kuroshio is closer to Orchid Island. The current speed is around 0.05m/s (0.1 knot) at the discharge outlet of 50m deep and the current direction is mainly along the coastline. The simulation shows that the plume concentration will not accumulate because of the strong ambient current. The 10 times dilution rate will be reached at 700m away from the discharge outlet in the depth of 50m. The 33 times dilution rate will be reached in the depth of 25m above the discharge outlet. The area of the plume is bigger when neap tide and smaller when spring tide. Two in-situ marine ecological samplings in the summer (July 2010) and winter seasons (Nov. 2010~January 2011) with 25 sampling stations each are conducted. The result of ecological investigation shows that the primary production is higher in the summer than in the winter. In the summer season, the primary production is 14.6~438.4 (mg/m3/hr) on the surface water and 14.6~1812.1 (mg/m3/hr) down in the depth of 50m. In the winter season, the primary production is 14.0~886.6 (mg/m3/hr) on the surface water and 29.3~385.6 (mg/m3/hr) down in the depth of 50m. The difference between two seasons is small because of the influence of Kuroshio. The primary production in the coastal zone is higher because of the influence of Ji-Ben Creek in the summer time. The number of fish egg and fry is bigger in the summer than in the winter. The benthonic organism in the tidal zone of the coastline is scarce because of the rocky beach. The distribution of the benthonic organism along the coastline is influenced by the ocean current but not the fresh water comes out from the Ji-Ben Creek. The research results on the relationships between nutrients and primary production of KEEP project of East China Sea and the Ji-Ben area are introduced to evaluate the causes of marine fertilization. The sea surface temperature in Ji-Ben area is influenced by Kuroshio which is the same as the southeastern area of KEEP project. The sea water temperature plays most important role on promoting primary production. The primary production is proportional to phosphate and silicate concentration in the region of 50m deep in Ji-Ben area. The zooplankton is proportional to phytoplankton in Ji-Ben area which indicates the feasibility of fertilization if the primary production can be raised. The effluent of DOW pilot plant may cause fertilization in 50m deep in the summer according to the simulation result of advection and diffusion. The fertilization may be reached in the winter if the effluent temperature and phosphate concentration can be raised. The in-situ ecological and water quality samplings after the completion of DOW pilot plant and effluent discharged are proposed. The result of in-situ water quality investigation will be used by the water quality model to simulate the possible area and concentration of the effluent plume. The feasibility of marine fertilization will then be evaluated in further details.