The Research on Ocean Risk Assessment

隨著人類活動的增加，陸上污染源所產生的污染物透過管線或河川被過量排放到海洋環境，尤其高生物累積特性之污染物會蓄積在我們所食用的海鮮中，造成嚴重的健康危害，因此海洋污染問題應被高度重視及採取預防管理措施。我國對於預防海洋污染之規範，針對放流水排放無法實質防治對於人體健康的危害，應透過海洋健康風險評估方法之建立，量化人體健康衝擊並採取預防管理措施，以達到污染防治的目的。 本研究所建構的海洋健康風險評估方法包含八個階段，分別為污染源特徵描述、設定海域暴露情境、海洋模式模擬、估算海洋環境介質濃度、暴露量化、海洋風險值估算、不確定性分析、海洋風險管理，細分成12個步驟，並於每個步驟設計評估表單。架構中整合評估範疇內所有的海洋環境介質及受體之風險，並著重污染物之生物累積特性，量化不同暴露受體的健康衝擊影響。 本案例挑選為開發中之場址進行分析，其場址位於高雄港，放流水中共計13項，主要為重金屬類污染物，其排放濃度介於5至400 ng/L；經評估後所量化的風險值為致癌風險10-13至10-8範圍及非致癌風險10-9至10-3範圍，皆低於可接受的風險值。進行海洋健康風險評估過程中，比較稀釋因子及MIKE 21模式(水理及水質)模擬兩種方法，稀釋因子低於模式模擬約10倍，其估算風險亦會較低。估算污染物於環境介質中的濃度為蝦貝及魚體中的濃度較高，可反應污染物具有生物累積特性；而蝦貝類體內濃度比魚類中高，原因與蝦貝類較易蓄積重金屬類污染物有關。暴露受體則以職業漁夫和水產養殖用戶的風險比一般民眾高，與較高的暴露頻率及時間有關。 經由不確定性分析，95%風險值亦低於可接受的風險值，而不確定性因子中，水體濃度、一般民眾之食用量(IU)、職業漁夫及養殖用戶之食用量(IU)及皮膚接觸頻率(EF)皆為主要的影響因子。The ocean pollution is getting serious with the increase of discharges from drains and rivers, especially high bio-accumulations of pollutants lead to high concentration and accumulated in seafood. Moreover precaution and management of ocean should be concerned by the public and government. However in Marine Pollution Prevention Law in Taiwan, there are not enough rules and limitation for protecting human health from discharging. Hence in order to reduce the pollution in the marine environment, ocean health risk assessment should be established for precaution and assessment. The eight stages for ocean health risk assessment methodology was established in this study, including Sources Characterization, Ocean Exposure Scenario, Ocean Model Simulation, Exposure Quantification, Ocean Risk Characterization, Uncertainty Analysis, Ocean Risk Management. The eight stages were classified into 12 steps with 11 forms in detail. Ocean health risk assessment methodology was constructed by form design, which was organized completely and procedurally for explaining the critical scenarios, exposures, receptors, and exporting outcomes. In order to quantify systematically the health risk exposed to marine pollution, sketching the overall picture from the pollution sources to the health of receptors is required, especially effect of bio-accumulative factor in marine ecosystem. A plant is a developing plan in Kaohsiung port is chosen a case in this study, 13 heavy metals discharge into ocean in 5~400 ng/L; consequently the risks of cancer are from 10-13 to 10-8, hazard quotients are from 10-9 to 10-3, which are less than acceptable risk. Further the distribution of metal concentrations in ocean, bio-accumulative concentration, exposure pathway, and uncertainty of risk can be discussed in detail by the form design of ocean health risk assessment. Compared with the metal concentrations simulated by dilution factor and MIKE21, which is a hydrodynamic Model and dispersion Model. The concentrations simulated by dilution factors are 10 times lower than MIKE 21, hence the lower risks are estimated by dilution factors. Based on bio-accumulation of metals, which in shellfishes are higher than in fishes, the metal concentrations are easily accumulated in shellfishes and fishes. The risks of fishers and aquacultures are higher than general receptor, because of high frequency of exposure. Through uncertainty analysis, 95% cumulative risks are also less than acceptable risk, and the sensitive parameters are metal concentrations in ocean, ingestion rate of general receptor and duration of dermal contact