Nutrient Variation Characteristics of Luanhekou - Beidaihe Ecological Monitoring Marine Area in summer

Based on the observation data and materials of Luanhekou - Beidaihe ecological monitoring marine area obtained during 1999 and 2014 in summer, the nutrient and its structure change were studied. The results showed that: with social and economic development in the coastal regional, compounds with three nitrogen atoms increased, but phosphate and silicate decreased in the past 16 years. Average N: P ratio increased from 4.951 in 1999 to 47.188 in 2014, while Si: N ratio decreased. Nutrient structure changed obviously. Phosphate was relative surplus but inorganic nitrogen was relative lack before 2004. However, the water quality characteristics turn into high nitrogen and low phosphorus after 2004. (paper)