Distribution Characteristics of Nutrients and Eutrophication and Organic Pollution Evaluation in the Coastal Area of Shandong

According to the survey data of three voyages in the coastal area of Shandong in May, August and October of 2019, the distribution characteristics and water qualities of DIN, PO₄-P and COD in different seasons were analyzed, and the eutrophication status and organic pollution of the waters was assessed by single factor index, eutrophication index and organic pollution comprehensive index. The results showed that the concentration of DIN showed a tendency of gradually decreasing from west to east, high value areas appeared in Laizhou Bay.The overall trend was that their concentrations of the northern waters of Shandong were higher than those of the southern areas. The concentration of PO₄-P and COD was balanced, and the distribution law was not obvious.Seasonal variation of nutrients concentration was the lowest in summer and the highest in autumn, followed by spring. The eutrophication stations in the study area accounted for 19.1%, the light organic pollution and above stations accounted for 21.3%, it is mainly distributed in Laizhou Bay, Jiaozhou Bay and Dingzi Bay.