Abstract: Waters and sediments in coastal waters are important sites for nutrient translocation. By sampling the Bohai Sea waters and sediments in August 2016, the spatial distribution characteristics of different forms of nutrients in the waters and sediments of the Bohai Bay were analyzed. In addition, the migration and transformation of nutrients in waters and sediments were studied. The results show that nutrients in Bohai Bay waters are higher in the nearshore area of the west coast and lower in the open sea areas far from the coastline, showing a clear concentration gradient. It shows that the contribution of man-made activities to the nutrient content in the water body in coastal waters is obvious. Nutrients in waters are mainly in inorganic forms, and inorganic nitrogen and inorganic phosphorus account for 76.65% and 76.46% of the total. Nitrogen and phosphorus in sediments show similar spatial distribution of nutrients in waters. However, the main form of nitrogen is organic nitrogen, while the content of inorganic phosphorus also drops to 30.42%. This shows that the nitrogen and phosphorus in Bohai Bay waters mainly enter the sediments through the assimilation of organic compounds in waters by the organism. Part of inorganic phosphorus enter the sediments through the adsorption form, but the effect of nitrogen entering the sediments from the water body through adsorption is not obvious.

Key words: nitrogen, phosphorus, spatial distribution, migration and transformation, Bohai Bay