Evaluation of Marine Eutrophication (COD, DIN and PO4-P) in Yangshan Port Area of Shanghai

According to the monitoring data of COD, NO2-N, NH4-N, NO3-N, DIN and PO4-P of 48 water quality monitoring points in Yangshan Port in spring and autumn of 2020, the pollution degree and eutrophication status of the water body were evaluated by single factor index method, eutrophication status index method and correlation analysis method. The results show that COD, NH4-N, NO3-N, DIN and PO4-P all present obvious stratification characteristics and the concentration in surface water is higher than that in bottom water while the concentration level of NO2-N in bottom water is better. The proportion of NH4-N in inorganic nitrogen in autumn was higher than that in spring, while that of NO3-N in spring was higher than that in autumn. The eutrophication state indexes of surface water and bottom water in spring were 3.51 and 2.94, respectively. The eutrophication state indexes of surface water and bottom water in autumn were 7.90 and 6.35, respectively. The eutrophication degree in autumn was higher than that in spring, and the eutrophication degree in surface water was higher than that in bottom water.