Through the collection and analysis of COD, dissolved inorganic nitrogen (DIN) and active phosphate monitoring data in Tianjin Hangu Agricultural and fishery area from 2010 to 2019, this paper analyzed and studied the structure of nutrients and the state of eutrophication. The results show that in recent ten years, the water quality of Tianjin Hangu Agricultural and Fishery Area has basically met the water quality requirements of functional area, the regional nitrogen pollution has been

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... ed, and the eutrophication index of sea area has shown a decreasing trend year by year, but the nitrogen and phosphorus nutrient structure is still in the state of "phosphorus restriction". Pollution control of sea areas and conservation of aquatic germplasm resources are still urgent.