With the change of environmental conditions and the influence of human factors, a variety of dead fish accidents are increasing. Due to the large number of oxygen-consuming organics discharged into the fishery waters, the performance characteristics of dead fish are strikingly similar to the performance characteristics of dead fish, which brings certain difficulties to the investigation and handling of accidents. Therefore, how to correctly distinguish the differences between the two? ? I do engage in inland waters fishery pollution accident investigation and handling of many years that should be carried out to identify the following aspects: 1. Dead fish time Hypoxia dead fish is prone to occur in the late spring, early autumn and summer high temperature seasons, especially in the case of abrupt climate change, thunderstorm weather and low atmospheric pressure, usually after midnight to dawn. Oxygen-depleting organic matter polluted dead fish had no obvious selection characteristics for season and time, but the pollutant discharge unit consciously chose a large amount of sewage in the middle of the summer to cause pollution of dead fish, which coincided with the lack of oxygen and dead fish. The distinction has increased the difficulty, and it is necessary to further synthesize the information of all parties and conduct a comprehensive analysis. 2. The oxygen content of dead fish in the dead fish environment is lower than that of the fishery water quality standard. The water color is gray or black and there is a musty smell. The species and quantity of plankton are basically normal or reduced, and the aquatic animals and plants have no obvious abnormalities. Oxygen-depleting organic matter contaminates dead fish. The dissolved oxygen content of dead fish is extremely low in dead fish. The color of water changes due to pollutants. It is mostly yellow-brown, earthy yellow and smelly. Plankton are dead, and aquatic plants become wilting. Yellow, snakes, frogs, snails and other aquatic animals escape or die. 3. Dead fish Symptoms Hypoxia Dead fish does not occur in isolation. Water bodies with similar conditions around the accident site generally occur at the same time, and there is a noticeable taro phenomenon before the large number of fish deaths. Individual large fish bodies die first and die. The proportion is higher than the individual's smaller fish. There was no obvious abnormality on the body surface of the dead fish. The pectoral fins were stretched forward and the fins were white and opened. Oxygen-depleting organic matter pollutes dead fish within its range of influence. Due to the different sensitivity to pollutants, individual small fishes die first, and they crash and swim around the pond, and the water is dissolved due to large amounts of oxygen consumption. The rapid decline in oxygen causes a large number of deaths of fish in a short period of time. There are attachments on the surface of the fish body and the ankle, and there is usually a special smell of pollutants. 4. The investigation of pollution sources through the diagnosis of the above three biological and environmental characteristics can be preliminary inferred whether it belongs to oxygen-consuming organic pollution of dead fish. If it is, then the investigation of the pollution source is of utmost importance. It is necessary to investigate the sources of all possible oxygen-emission organic pollutants in the vicinity of the accident site, mainly to grasp the types of pollutants discharged, the amount of pollutants discharged, the time of pollutant discharge, and the method of pollutant discharge, in order to determine the pollution caused by the pollution. The inner connection of the fish. 5. The laboratory analysis of water samples, sediment samples, and fish samples was promptly sent to the scene of the accident. The first time, effective water samples, sediment samples, and fish samples were taken and laboratory analysis was performed. Scientific data were used to synthesize relevant information. Investigate information and make comprehensive and correct conclusions.
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