Tendency and Causes Analysis of Marine Water Quality of Jinzhou Bay

Based on the two monitoring data of Jinzhou Bay in July 2008, September 2013 and September 2016, this article analysis the temporal trends of marine water quality of Jinzhou Bay. The average concentration of COD, inorganic nitrogen and phosphate is between 1.09mg/L~1.45mg/L, 0.42mg/L~0.711mg/L and 0.006mg/L~0.03mg/L, respectively. The concentration of inorganic nitrogen showed a downward trend while the concentration of phosphate showed an increased trend. Meanwhile, the concentration of COD had no significant change. Results showed that the inorganic nitrogen concentration and phosphate concentration have good correlation with eutrophication index and Eutrophication parameters（E）showing a clear upward trend. The emission of active phosphates and inorganic nitrogen from land-based pollutants are the main cause of this phenomenon.