南黄海与长江口海域夏秋季营养盐分布特征及影响因素

Distribution and Influence Factors of Dissolved Inorganic Nutrients in the Southern Yellow Sea and Yangtze Estuary in Summer and Autumn

根据2013年6月与11月的夏、秋两季南黄海与长江口北部海水中DIN、PO^(3-)_4-P、SiO^(2-)_3-Si的调查结果,分析了该海域营养盐的浓度状况、季节变化和分布特征,初步探讨了影响该海域营养盐时空变化的主要因素。结果表明,DIN、PO^(3-)_4-P浓度总体符合国家第一类海水标准,其中夏季DIN浓度(5.56±3.43)μmol·L^(-1),PO^(3-)_4-P浓度(0.27±0.27)μmol·L^(-1),SiO^(2-)_3-Si浓度(8.40±6.24)μmol·L^(-1),秋季DIN浓度(7.28±4.09)μmol·L^(-1),PO^(3-)_4-P浓度(0.44±0.32)μmol·L^(-1),SiO^(2-)_3-Si浓度(17.60±9.36)μmol·L^(-1)。调查海域各营养盐的含量均呈明显的季节性变化和垂向变化,表现为秋季普遍高于夏季,底层普遍高于表层。该海域营养盐平面分布的取决于陆源径流与季节性外海海流的强弱竞争,当长江冲淡水的外扩较强时,南黄海营养盐平面分布整体呈现由沿海岸向外海逐渐降低的趋势;当黄海冷水团与外海海流较强时,其分布呈现由外海向沿海岸逐渐降低的相反趋势。

Based on two cruises in the southern Yellow Sea and northern Yangtze estuary during June and November 2013,respectively,concentrations seasonal variations and distributions of dissolved inorganic nutrients（DIN,PO（3-）4-P and SiO（2-）3-Si）were analyzed,and their influenced factors were also discussed.The results showed that the values of DIN and PO（3-）4 generally conformed to the first categorie of seawater quality standard in the study area.The DIN concentrations were（5.56±3.43）and（7.28±4.09）μmol·L（-1） in summer and autumn,respectively.The PO（3-）4-P values were（0.27±0.27）and（0.44±0.32）μmol·L（-1） during the two seasons,respectively.And the SiO（2-）3-Si values were（8.40±6.24）and（17.60±9.36）μmol·L（-1） during the two seasons,respectively.The nutrient concentrations commonly presented the seasonal and stratification variations,and their levels in autumn were usually higher than those in summer,those in bottom higher than surface.The horizontal distributions of nutrients generally depend on the competition between terrestrial input and ocean currents in the study area.When the expansion of the Yangtze Diluted Water exhibited stronger,the horizontal distribution of DIN,phosphate and silicate usually decreased from the nearshore to offshore waters.And when the Yellow Sea Cold Water Mass and ocean currents presented stronger,the nutrient distributions showed the opposite trend,decreasing from offshore to inshore.