东营市近岸海域营养盐时空分布及富营养化评价

为深入研究现阶段东营市近岸海域的营养盐状况，本文以东营市管理海域为独立单元，根据东营市近岸海域2021年冬季、春季、夏季、秋季4个航次30个站位的海水水质监测数据，分析了东营市近岸海域中营养盐溶解性无机氮（DIN）和活性磷酸盐（DIP）的时空分布特征，分别应用富营养化指数法及潜在性富营养化评价模式对整个海域的水质富营养化程度进行评价。结果表明，东营市近岸海域冬季、春季、夏季3个季节均有80%以上的站位DIN浓度符合二类海水水质标准，且空间分布整体呈现南部高、北部低的趋势；秋季DIN浓度整体较高，符合二类海水水质标准的站位仅占比6.7%；4个季节所有站位DIP浓度均符合一类海水水质标准，季节变化和空间分布未呈现明显差异；富营养化指数法评价结果显示，东营市近岸海域除秋季富营养化程度较高外，其他季节基本未呈现富营养化状态；潜在性富营养化评价模式分析结果表明，东营市近岸海域的氮磷摩尔比均大于Redfield比值（16），总体呈现磷限制状态，秋季尤为凸显，93.3%的站位为磷限制潜在性富营养状态。研究结果可为掌握东营市近岸海域环境质量时空状况和陆海统筹的环境治理提供科学依据，为深入打好渤海污染防治攻坚战，推进黄河流域生态保护和高质量发展提供技术支撑。

Spatial and temporal distribution of nutrients and eutrophication evaluation in Dongying inshore

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.