硝酸盐为本次调查的计划外选测项目,仅做了两航次的大面观测(1981年9月及10月)和一站次的周日连续观测(128站,1981年10月22日),因此只能对其时空分布作一粗略描述。硝酸盐含量测值的变化范围是0.37—18.3μmol NO_3-N/L(以下用μmol/L表示),比长江口同季节硝酸盐的测值低得多,均值3.74μmol/L。其在平面上的分布随海区和时间而有甚大的变化,但Ⅲ区的规律性较好,呈由湾内向外逐渐减小的趋势。其断面分布大致为:01,02和04断面的等值线较少,分布较为均匀;03和05断面等值线密集,并向海底倾斜。其垂直分布以上高下低的递减型分布为主,但Ⅰ,Ⅱ区的垂直梯度较小,Ⅲ区的则较大,并呈现由湾内向外垂直梯度逐渐减小的规律性变化。128站硝酸盐浓度的周日变化甚大,日较差达5.95μmol/L,并有明显的潮汐效应,与盐度有相当好 Nitrate was the unplanned option for this survey. Only two major voyages of observations (September and October 1981) and one continuous observation of Sunday (128 stations, 22 October 1981 ), So only a rough description of its space-time distribution. The range of nitrate content was 0.37-18.3μmol NO_3-N / L (hereinafter expressed as μmol / L), which was much lower than that of the same season in the Yangtze Estuary with an average of 3.74μmol / L. Its distribution in the plane has a great change with the sea area and time, but the regularity of Ⅲ area is better, showing a downward trend outward from the bay. The distribution of the cross sections is roughly as follows: the contour lines of 01, 02 and 04 are less and the distribution is more uniform; the contour lines of 03 and 05 are dense and inclined to the seafloor. However, the vertical gradients of regions I and II are smaller while those of regions III are larger, and the regularity of the vertical gradient gradually decreases from the inside of the bay. The nitrate concentration in station 128 changed greatly on Sundays, with a daily difference of 5.95 μmol / L and a significant tidal effect, which was quite good with salinity