牟京龙^1,2, 张珊珊¹, 梁翠¹, 线薇微^1,3, 沈志良¹
1.中国科学院 海洋研究所 海洋生态与环境科学重点实验室, 山东 青岛 266071;2.中国科学院大学, 北京 100049;3.青岛海洋科学与技术国家实验室 海洋生态与环境科学功能实验室, 山东 青岛 266071

摘要:
根据2014年长江口水域4个季节航次水体中五项营养盐（硝酸盐NO₃-N、亚硝酸盐NO₂-N、铵盐NH₄-N、磷酸盐PO₄-P和硅酸盐SiO₃-Si）的调查数据，解析长江口水域营养盐的时空分布特征，结合盐度（S）、溶解氧（DO）、温度（T）、悬浮体（SPM）和叶绿素a等环境参数，探究其迁移过程的分布行为。结果表明：NO₃-N、SiO₃-Si和PO₄-P在长江口水域的时空分布主要受长江陆源输入的影响，随长江冲淡水扩展范围的季节变化而变化，除冬季外，在122°20'E以东，主要受到温盐跃层的影响，其在31°N断面出现明显的分层现象，冬季水体垂直混合均匀，其垂直分布较为均匀。春季长江陆源输入较高浓度的NO₃-N，40 μmol/L的NO₃-N随长江冲淡水向东北方向最远扩展到123°E，垂直方向上扩展至水深10 m，而秋季长江陆源输入较高浓度的SiO₃-Si和PO₄-P，其浓度分别为40 μmol/L和0.6 μmol/L的等值线分别向东最远扩展到123°E、123°20'E和水深20 m、50 m。受到生物吸收，硝化作用等因素影响，NO₂-N和NH₄-N的时空分布比较复杂，季节分布规律不明显，而冬季自口门向外海浓度逐渐降低，且垂直分布也相较均匀。通过盐度这一保守性指标引入理论稀释线来研究营养盐的迁移过程，结合叶绿素a和SPM的数据表明：春、夏季营养盐浓度低于理论稀释浓度可能是由于生物吸收所致，而PO₄-P在春、夏和秋季均有散点高于理论稀释浓度可能与悬浮颗粒物释放有关。
关键词:营养盐时空分布季节变化迁移过程
DOI：10.11759/hykx20190716002
分类号:P736.4
基金项目:国家自然科学基金资助项目（31872568）

Temporal and spatial distribution and mixing behavior of nutrients in the Changjiang River Estuary
MU Jing-long^1,2, ZHANG Shan-shan¹, LIANG Cui¹, XIAN Wei-wei^1,3, SHEN Zhi-liang¹
1.The Key Laboratory of Marine Ecology and Environment Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China;2.University of Chinese Academy of Sciences, Beijing 100049, China;3.Laboratory of Marine Ecology and Environmental Science, Qingdao National laboratory for Marine Science and Technology, Qingdao 266071, China
Abstract:
Based on four investigations conducted in February, May, August, and November 2014, we collected the data of five nutrients (nitrate, nitrite, ammonium, phosphate, and silicate) and the related environmental parameters (salinity, dissolved oxygen, temperature, suspended particulate matter, and chlorophyll) a) to analyze temporal and spatial distribution and mixing behavior of nutrients in the Changjiang River Estuary. Results show that NO₃-N, PO₄-P, and SiO₃-Si were mainly affected by the Changjiang terrigenous input, consisting of variation of the Changjiang Diluted Water (CDW). East of 122°20'E, water stratification caused by the thermocline, halocline, and the winter, as well as the vertical distribution of nutrients was obviously stratified. In contrast, the water in the vertical direction mixed well in winter, as well as nutrients. In the spring, the Changjiang terrigenous input supplied a high-concentration of NO₃-N and 40 μmol/L isoline extended northeastward as far as 123°E, reaching a water depth of 10m. In the autumn, the Changjiang terrigenous input supplied high-concentration SiO₃-Si and PO₄-P, and 40 μmol/L and 0.6 μmol/L isolines extended eastward to 123°E and 123°20'E, and reaching a water depth of 20 m and 50 m, respectively. The distribution of NO₂-N and NH₄-N were complicated by many factors such as bioadsorption and nitrification, and the seasonal variations were not obvious. A theoretical dilution line was introduced to study the mixing behaviors of NO₃-N, SiO₃-Si, and PO₄-P in the Changjiang River Estuary. The results show that nutrients consumed in the spring and summer might be related to primary production, and PO₄-P showed a positive deviation as conservative mixing could be connected to the process of SPM release.
Key words:nutrientstemporal and spatial distributionseasonal variationmixing process





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