渤海湾天津近岸海域化学需氧量的分布特征、影响因素及与富营养化的关系

本文根据2014年春季（5月）、夏季（8月）、秋季（10月）天津近岸海域18个站位的海水质量监测数据，分析了海水中化学需氧量（Chemical Oxygen Demand，COD）的时空分布特征和海域富营养化状况，研究了COD与营养状态质量指数（NQI）的关系，浅析了赤潮生消过程中COD浓度的变化。结果表明，夏季COD高于春季和秋季，季节性差异显著；COD基本呈现近岸高外海低、南部高北部低的趋势；NQI指数的变化范围为1.68~12.50，平均值为4.46，富营养化严重；COD与NQI指数具有显著正相关性，一定程度上可以反映海域富营养化状况；COD与赤潮生物密度、Chl a呈极显著正相关关系，在反映赤潮生消过程中有重要作用。

Distribution and influencing factors of COD,along with the relationship with eutrophication in Tianjin coastal area

The spatiotemporal variation of chemical oxygen demand (COD) and the eutrophication status were determined in spring(May), summer(August)and autumn(October) 2014, in Tianjin coastal area, Bohai Bay. Based on the seawater quality monitoring database at 18 stations in this area, the relationship between COD and nutrient quality index (NQI) were investigated, as well as the variations of COD during the occurrence of a red tide. Significant seasonal variation of COD was found, with that higher in summer and lower in spring and autumn. COD decreased from nearshore to offshore and from south to north. NQI index ranged from 1.68 to 12.50, with the average of 4.46, reflecting serious eutrophication. To some extent, the significant positive correlation between COD and NQI index could reflect the eutrophication status in seawater. Significantly and positively, COD was correlated with red tide biological density and Chl a, which plays an important role in reflecting the red tide generating and vanishing process.