本研究主要目的是為了瞭解常見地表水放流水、灌溉水、自來水、馴養水之氨氮濃度對水生生物急毒性的影響，期望找出氨氮對地表水棲息之水生生物造成的毒性關聯性。各水樣於氨氮濃度於25 mg/L時，其生物急毒性統計略同於氨氮濃度為3 mg/L、10 mg/L所呈現之生物急毒性反應，生物毒性反應較為明顯則是落在氨氮濃度為75 mg/L時，均有明顯魚體死亡情形。而試驗水樣自來水，其氨氮與自由餘氯形成氯胺，可能為影響自來水生物急毒性之原因而導致於氨氮濃度於75 mg/L 時TUa>1.43。放流水與自來水進行比較時，氨氮濃度於25 mg/L時兩者生物急毒性反應略同（TUa<1.43），而於氨氮濃度75 mg/L時，放流水急毒性反應TUa<1.43而自來水TUa則>1.43，經比較其兩者水樣來源時，初步判斷最大之差異應為放流水已經過廢水生物處理系統之氨化、同化、硝化及脫硝去除原廢水中高濃度的氨氮使其符合法定放流水標準，應與生物處理系統含有硝化菌有關。生物毒性會因生物體大小與本身之特性及對污染物之耐受性而有所改變，受測生物的選擇應需要審慎評估，環境因子與環境壓力似乎會提高魚體死亡機率，進而影響TUa的反應。The main purpose of the study was to understand the effects of ammonia in surface water on the acute toxicity of fish. River, discharged, feeding, potable water were used. When the concentration of ammonia was 25 mg/L ,the acute toxicity of ammonia is similar to that when the concentration of ammonia were 3 and 10 mg/L. The significant toxicity was observed when the concentration of ammonia was 75 mg/L, at which many fishes were dead. Ammonia and residual chlorine may form chloroamine; thus, even at low concentration, acute toxicity of ammonia may be enhanced and as ammonia reached 75 mg/L, TUa > 1.43. Biological treatment is commonly used to remove ammonia, which may transform ammonia into less toxic compounds. Therefore, it was found that the toxicity of ammonia may be limited in discharged wastewater due to the presence of nitrobacter. Because of the size, viability, and toxic pathway, organisms have different resistivity to toxic compounds. Therefore, selection of test organism should be assessed carefully. Also, environmental factors seemed to increase the death rate, and thus, affecting TUa
