Horizontal distribution features of biogenic elements in Bohai Sea and the Yellow Sea in summer

Based on the survey carried out from 22 June to 9 July 2013 in the Bohai Sea and the Yellow Sea, the concentrations and horizontal distribution features of biogenic elements (including DIN, PO4-P and SiO3-Si) and DO were analyzed, and daily variation patterns and influence factor of parameters of anchor station P2 in Laizhou Bay were preliminary discussed. Results showed that in summer, DIN was higher in the Bohai Sea than in the Yellow Sea, but DO, PO4-P and SiO3-Si were on the contrary. In the Bohai Sea, DIN and SiO3-Si were higher in surface layer than in bottom layer, but they were on the contrary in the Yellow Sea. DO was higher in surface layer than in bottom layer in both the Bohai Sea and the Yellow Sea. Nutrient distributions showed a descending trend from north to south and from coast to offshore. High value area of nutrient mainly appeared in Yangtze River Estuary, Yellow River Estuary, Jiangsu Coast and bottom of central area of the Yellow Sea, their distributions were obviously affected by Yangtze River Diluted Water, Yellow River Diluted Water and Yellow Sea Cold Water Mass. DO distribution showed a descending trend from north to south. DO was relatively low in the south Yellow Sea and high value area of DO appeared in bottom layer in north Yellow Sea. Affected by the Yellow River Diluted Water, nutrients and DO in surface layer of anchor station P2 were higher than in 10m and bottom layer, SiO3-Si and DIN were significantly affected by tide and their variation patterns were similar with that of salinity. DO was affected by the combined action of tide and biological activities, and it reached maximum value at 1600 hour in the afternoon.