Abstract:
To gain deep insight into the existing conditions of nutrients along the coastal sea areas of Dongying, the paper studied specially the sea areas governed by Dongying. Based on the sea water quality monitoring data in spring, summer, autumn and winter from 30 monitoring sites of the coastal sea areas of Dongying, the paper explored the spatial-temporal distribution laws of DIN and DIP in the nutritive salt along the coastal sea areas of Dongying. Eutrophication index method and potential eutrophication evaluation mode were used respectively to evaluate the degree of water quality eutrophication of the entire sea areas. As indicated by the results, the DIN concentration in spring, summer and winter from more than 80% monitoring sites along the coastal sea areas of Dongying was unexceptionally up to Class II sea water quality. Spatially, the DIN concentration in the south was generally higher than that in the north. On the whole, the DIN concentration in autumn tended to be higher and only 6.7% monitoring sites met Class II sea water quality. No significant difference in seasonal changes and spatial distribution was noticed. As suggested by eutrophication index evaluation results, the sea water eutrophication along the coastal areas of Dongying tended to be higher in autumn only. According to potential eutrophication evaluation mode, unexceptionally the nitrogen-phosphorus mole ratio along the coastal sea areas of Dongying was greater than the Redfield ratio (16). On the whole, the coastal sea areas were under phosphorus limitation, especially in autumn. About 93.3% monitoring sites were under phosphorus limitation and potentially eutrophic. Research findings of the paper will lay scientific basis for a good understanding of the temporal-spatial conditions of the offshore sea environment and overall land-sea environmental governance of Dongying. Besides, it will give technological supports to pollution prevention of Bohai Sea as well as ecological protection and high-quality development of the Yellow River.