长江口理化因子影响初级生产力的探索Ⅰ.营养盐限制的判断方法和法则在长江口水域应用

营养盐限制浮游植物的生长是近年来国际研究的热点。探讨了目前营养盐限制的判断方法，认为仅靠氮和磷比值来得到磷限制或氮限制的结论是不完善的。根据营养盐限制的判断方法和法则，对长江口水域进行综合分析，认为在长江口及其附近海域，磷不是浮游植物生长的限制因子，而且氮、磷的浓度值都高于限制浮游植物生长的阈值，满足浮游植物的生长。通过1985年8月至1986年8月的长江口调查数据分析，发现从长江河口到远海水域的有些断面上，磷酸盐浓度并不一定离岸越远越低，且也没有周期性的季节变化。因此，尚须对河口区磷酸盐来源作进一步研究。

An Approach to the Effect of Physicochemical Factors on Primary Productivity in the Changjiang EstuaryⅠ.Application of Judging Methods and Rules of Nutrient Limitation to the Changjiang Estuary Water Area

In recent years, the limitation of nutrients on phytoplankton growth has become a focus of international research. In this paper, the methods for judging nutrient limitation are discussed, and a conclusion on N limitation or P limitation drawn only from the radio of N to P is not thought perfect. The judging methods and rules of nutrient limitation are used to make a comprehensive analysis of the Changjiang estuary water area, and it is shown from the analysis results that in the Changjiang estuary and its adjacent sea area, P is not a limiting factor for phytoplankton growth, and the N and P concnetrations are all higher than their critical values of limiting phytoplankton growth, so the N and P concentrations in the sea area can satisfy the phytoplankton growth. It is shown from the analysis results of data surveyed in the Changjiang estuary water area from August 1985 to August 1986 that the phosphate concentration along some sections in the sea area did not decrease with increasing offshore distance, and there was no periodic seasonal variation in phosphate concentration. Therefore, the phosphate sources in the Changjiang estuary water area remain to be further studied.