Distribution characteristics of nutrients and relationships with the environmental parameters in seawater of Dalian Bay

In this paper,according to the survey data on nutrients of Dalian Bay in August and November 2012,the distribution characteristics and the structure characteristics of silicate(SiO3-Si),reactive phosphate(PO4-P) and dissolved inorganic nitrogen(DIN) were analyzed and discussed,and the correlation relationships between the temperature,pH,chemical oxygen demand(COD),salinity(S),apparent oxygen utilization(AOU) and the nutrients were studied. Comparison with the historical data on nutrients,the results showed that the DIN concentration increased,and PO4-P and SiO3-Si concentration decreased,significantly. The SiO3-Si and PO4-P concentration is lower in August than those in November,but DIN concentration was higher in August than that in November. The DIN, PO4-P and SiO3-Si concentration reduced from the top to mouth of Dalian Bay,gradually. A significant correlation existed between PO4-P,NH4-N and the temperature,pH,COD,S,AOU. The AOU is significantly positively-correlated with the NO2-N and SiO3-Si. Phosphorus was the main limit element in Dalian Bay.