Hazards and determination methods of oil in water

The oil in the water body comes from the discharge of industrial wastewater, domestic sewage, and animal decomposition. It is estimated that 500×104-1000×104 tons of oil and its products may be discharged into water bodies every year, resulting in various degrees of pollution, caused by oil leakage and war factors. Hazards and determination methods of oil in water 1. Main hazards of oil ①Consumes DO in water and deteriorates water quality. The oil dispersed in water is partially adsorbed on suspended particles, or exists in the water body in the state of milk, and partly dissolves in water. The oil in water consumes DO during the process of decomposition and oxidation by microorganisms, which deteriorates the water quality; at the same time, it floats on the surface of the water body The oil in the air affects the gas exchange on the air-water interface and forms an oil film. As a result, the water body cannot replenish O2 from the air in time, which further promotes the deterioration of water quality. ②Poison fish and bring damage to fishery production. Oil pollution can directly poison fish, especially oil films and oil clusters can stick a large number of eggs and juvenile fish, causing harm to fish reproduction. Even if the oil concentration is as low as 10-4 to 10-5mg/L, the survival rate of fish eggs is only 55% to 89%, and the deformed larvae account for 23% to 40%. Report: Due to oil pollution in the Caspian Sea of ​​the former Soviet Union, the plankton on which marine fish depended for survival has dropped significantly, the total output of sturgeon has dropped by 2/3, and carp and scorpion fish have almost disappeared. Therefore, oil has become one of the routine monitoring items of water. 2. Oil determination method ①Gravimetric method: complex operation, low sensitivity, but not limited by oil products ②Ultraviolet spectrophotometry: easy to popularize, high sensitivity, based on the characteristic absorption of aromatic hydrocarbons at a certain wavelength, for aromatic hydrocarbons Higher sensitivity ③Fluorescence method: higher sensitivity ④Infrared method: higher sensitivity Oil, while the fluorescence method can only measure crude oil. Therefore, the infrared method has wider applicability and higher accuracy than the fluorescence method.