关键词: 渔业污染事故, 非离子氨, 溶解氧, 氨氮, 鱼类死亡, fishery pollution accident, ammonia nitrogen, dissolved oxygen, ammonia, death of fish

Abstract: Two fishery death accidents happened in Fujian province Minhou county and Fuqing city freshwater fish farms were concluded caused by poultry manure contamination. Through the investigation we found the ammonia, ammonia nitrogen and total coli group were beyond the standard level in the contaminated water. The oxygen consumption substances increased by poultry manure contamination in Minhou county fishery farm. The consumption of oxygen in water caused the fish died for hypoxia. The dissolved oxygen in dead zone is 0.55mg/L to 0.92mg/L. Caused by poultry manure contamination in Fuqing city fishery farm, the amount of phytoplankton rapidly increased from 9.58×107 to 1.05×108cell/L after consuming ammonia nitrogen nutrients. Photosynthesis also produced lager amounts of oxygen in daylight which resulted in super saturation dissolved oxygen （180%~183%）. At the same time released of carbon dioxide also led to pH increase （9.59~9.79）. Furthermore, a large amount of NH4+ in water were transformed into NH3, consequently fish died for the increase of ammonia content. After investigation of these two typical poultry manure contamination in aquaculture water cases, we analyzed the variation of index factors and concluded that the poultry manure contamination could lead to increase of ammonia, ammonia nitrogen and total coli group. The factors causing fish death were lack of oxygen and ammonia poisoning. Recommended strategies for pollution prevention suggested in the paper as well.