【摘要】 <正> 海水中的NO₂—N,是NH₄⁺氧化成为NO₃^-的中间形态,是氧化还原态的指标。而NH₄—N则是有机N分解的第一个无机产物。NO₂^-及NH₄⁺如同NO₃^-一样,可直接被浮游植物同化。大陆迳流及大气降水常带来大量的NH₄⁺。当浮游植物茂盛时,浮游植物与NH₄⁺构成了直接循环,从而更显示了它在氮循环及营养基础中的重要意义。 本文研究了长江口附近渔场区海水中的NO₂—N及NH₄—N的地球化学特征。更多还原

【Abstract】 The horizontal distribution of NO2-N near estuary of the Changjiang River during five cruises between August and December 1963 shows that there is a gradient in summer-autumn with a tendency of high contents in estuary and low in offshore water, such as 10→0.8 mg/m3 in August. In autumn-winter, it tends to homogeneous distribution. Obviously, the high concentration is from the river water. The NH4-N contents are high in the estuarine water in all seasons, 60-140→20 mg/m3. The NO; maximum layer is a characteristic of vertical profile distribution of NO2-N. The mechanism of NO2- maximum is due to consumption of NO2- by phytoplankton in upper water layer and regeneration of NO; from dead organisms below the thermocline. It coincides with the high phytoplankton mass, high O2% high total organic-N and low-nutrients in the water layer above the thermocline. The NH4-N contents in the upper layer and especially in bottom are higher than in the middle layer. In monthly variation, high NO2-N is in summer-autumn in estuarine and coastal waters and NO2- maximum layer, and in autumn-winter in other offshore area.However, the content of total inorganic nitrogen near the estuary of the Changjiang River is high which keeps high primary productivity, and it is not a limiting factor of phytoplankton.In the nitrogen cycle in the sea, the different thermodynamic free energy ΔG0 in NH4+=NO2-and NO2- = NO3-, which shows the spontaneous degree of reaction, coincides with the reaction rate of kinetics dc/dt, it shows that there may be Various catalysts, especially enzymes, in sea water owing to the activity of organisms, so there may be a relationship between ΔG0 and dc/dt in the sea. After catalyst removes the potential barrier of kinetics of a spontaneous reaction, the reaction will take place automatically and directly from initial state to final state, and the reaction rate of kinetics, dc/dt, may relate to the thermodynamic free energy, ΔG0, which shows the spontaneous degree of reaction.更多还原