摘要
海水中NO3—N的含量，在浮游植物大量繁殖时，可以使之消耗殆尽．但有机质的分解，可以使之获得再生．海水垂直对流作用，可以将底部再生的N03-N带到上层．大陆水也会带来大量的NO3-N．
Marine geochemistry of nitrogen near estuary of Yangtze River was investigated during five cruises between August and December 1963.NO3-N, NO2-N, NH4-N and organic-N were measured. High concentrations of NO3-N, 150-220 mg/m3, are in cstuarine and coastal waters, and low concentrations, 0-5mg/m3, are in offshore waters. It clearly shows that the high concentration cf NO3-N is from Yangtze River water which takes NO3-N etc. from nitrogen cycle along the river and partly from chemical fertilizer. The vertical profile distribution of NO3-N shows that coincides with the σt, In summer, the low concentration of NO3-N in upper layer is due to consumption by photoplankton,and the high concentration below the thermocline is from regeneration from dead organisms. The monthly variation of NO3-N shows that most of them in middle and upper layers are low in summer-autumn due to consumption and high in autumn-winter supplied by water vertical mixing. The high atomic ratio of NO3-N/PO4-P in estuary and low ratio in offshore water show the Urge influence of river water. High concentration of NH4-N shows that the NH4+ = NO2- = NO3- system is in thermodynamic nonequilibrium state. However, the total inorganic nitrogen in estuarine area is high, and this is the chemical nutrient base of the famous fishing ground. In June 1980, very high concentration of NO3-N, 910mg/m3, was found in estuarine water( J. Edmond ) , which is 4 times higher than in 1963. This increased NO3-N is mainly from chemical fertilizer, which coincides with increase of fertilizer factory along the river, and with dead and decrease of green frog, field snail and snake etc. in rice water field.
