Seasonal Variation Characteristics Of Water Quality And Improvement Of Water Quality By Water-lifting Aerator In Heihe Jinpen Reservoir

In order to understand the thermal stratification, the characteristics of the water quality and the application of water-lifting aerator system in the deep reservoir. Temperature, dissolved oxygen, p H, chlorophyll a, specific conductivity, ORP, nutrient and DOC, Fe, Mn, CODMn were monitored in a whole year. It mainly focuses on: ①the characteristics of water quality to the seasonal thermal stratification in Heihe Jinpen reservoir; ②Analysis on influence of rainstorm in Heihe Jinpen reservoir; ③Study on application of water-lifting aeration. The main conclusions are as follows:(1)The results showed that Heihe Jinpen reservoir belonged single hybrid mode, the natural thermal stratification period was from March to October. The thermal stratification led physical and chemical stratification. In the end of natural thermal stratification period, the application of water-lifting aerator technology, made the water mixed in advance, achieved compulsory mixed and natural mixed process of organic link, prolonged the continuous improvement of water quality aging. The chlorophyll a, total phosphorus, total nitrogen, ammonia nitrogen and DOC average concentration was 2.21 μg/L, 0.022 mg/L, 1.32 mg/L, 0.20 mg/L and 2.93 mg/L, In the thermal stratification period, the underlying water dissolved oxygen ranged from 0.0 mg/L to 7.9 mg/L, with an average of 2.9 mg/L, the ratio of N/P was between 41 and 100, which showed that Heihe Jinpen reservoir had a seasonal hypoxia, with high nutrient concentration.(2) Rainstorm runoff mainly affects upper-middle-class water quality, runoff into the reservoir, dissolved oxygen content reached more than 8 mg/L, at the same time a dramatic rise in the water turbidity, total nitrogen, total phosphorus, organic matter content increased significantly. The total nitrogen average concentration of 1.48 mg/L, total phosphorus average concentration of 0.04 mg/L, CODMn average concentration reach 5.0 mg/L, organic matter content than sunny runoff around 2 mg/L. Continuous rain, make the upstream water carried by the large amount of nutrient, caused the accumulation of pollutants in the reservoir, and is subject to the influence of rainstorm runoff and the raw water turbidity, potassium permanganate index rise to brought great influence to the safe operation of waterworks.(3)The application of the improved water-lifting aerator obviously to effective to improve the Heihe Jinpen reservoir water quality. Mixed oxygen filling, the thermal stratification structure damage to reservoir, vertical temperature difference narrowed, surface temperature drop about 6℃, thermocline position move down, temperature difference shrink; Narrowing the scope of isothermal layer, layer temperature scope expands unceasingly, and the upper and lower water gradually become homeothermy, seasonal anaerobic environment improved, the sediment surface dissolved oxygen concentrations remain above 9mg/L; Stagnant water dissolved oxygen average concentration increased before running about 1.5 times, TP concentration of 0.042 mg/L fell to 0.013 mg/L;TN concentration of 1.44 mg/L fell to 1.19 mg/L; Ammonia nitrogen concentration of 0.45 mg/L fell to 0.23 mg/L; Iron content by 0.42 mg/L fell to 0.15 mg/L; Manganese content is less than the minimum detection limit(0.05 mg/L); CODMn content by 5.39 mg/L fell to 4.04 mg/L, content of chlorophyll a fell from 5.92μg/L to 1.66μg/L.