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根据2004年4个航次的调查资料,研究了长江口及其邻近水域溶解无机氮的分布变化特征。结果表明,高浓度溶解无机氮集中分布在河口附近。一般来讲,近岸硝酸盐浓度上层高于下层,远岸与之相反。由于生物和化学作用的影响,亚硝酸盐和铵盐垂直断面分布较为复杂。随着长江径流量的增加与减小、冲淡水势力范围的扩大与缩小,硝酸盐季节分布随之变化,然而,亚硝酸盐春季浓度较高,铵盐冬季浓度远大于其它季节。各月DIN/PO4-P比值远高于Redfield比值。与1985~1986年相比,20余年溶解无机氮增加了2.2倍,DIN/PO4-P比值升高了1.4倍,这主要取决于溶解无机氮浓度的增加。溶解无机氮在河口的转移除了生物活动的影响外,主要受海水稀释作用的控制。
According to the survey data of 4 voyages in 2004, the distribution characteristics of dissolved inorganic nitrogen in the Yangtze Estuary and its adjacent waters were studied. The results showed that high concentrations of dissolved inorganic nitrogen concentrated near the estuary. In general, near-shore nitrate concentrations are higher at the upper level than at the lower level, whereas far-shore is at the opposite. Due to the biological and chemical effects of nitrite and ammonium vertical distribution of the cross section is more complicated. With the increase and decrease of runoff in the Yangtze River and the broadening and shrinking of the scope of diluvial water, the seasonal distribution of nitrate changed. However, the concentration of nitrite in spring was higher and the concentration of ammonium in winter was much greater than in other seasons. The monthly DIN / PO4-P ratio is much higher than the Redfield ratio. Compared with 1985 ~ 1986, dissolved inorganic nitrogen increased by 2.2 times and DIN / PO4-P ratio increased by 1.4 times over 20 years, which mainly depended on the increase of dissolved inorganic nitrogen concentration. Dissolved inorganic nitrogen in estuarine transfer in addition to the impact of biological activity, mainly by seawater dilution control.