Studies on the biological production of fire pools in Tokyo:XI. The seasonal changes in the amounts of dissolved inorganic salts, organic substances and the number of bacteria, and the interrelation among them

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(1) The seasonal changes in the contents of dissolved inorganic salts, organic substances and the number of bacteria were measured in three pools of Tokyo in 1952 and 1953. The interrelation between these three were also investigated. (2) The amounts of NH4-N of the surface layer was 0.010.042 mg/l in pool A, 0.030.83 mg/l in pool B, and 0.010.64 mg/l in pool C. In all the pools the maximum concentrations were seen in spring and autumn, and the minimum onesin winter and summer. The amount was always larger at the bottom layer than at the surface layer. The difference of the amounts of NO2-N and NO3-N between the surface and the bottom layers was very small, the former being 00.007 mg/l and the latter 00.08 mg/l, both of which decreased to zero in spring and autumn. The concentration in pool A was lower than in any other pools in general. (3) The content of organic-N showed two maxima every year. It was high in spring and in autumn, and low in winter and in summer in all the pools. At the surface layer it was about 0.530.76 mg/l, being lower than in the bottom layer. The content in pool A was lower than those in any other pools. (4) Among the phosphorus compounds, the amount of PO4-P was 00.008 mg/l in pool A and B, 00.003 mg/l in pool C. It became zero in the surface layer in spring and summer, and in every layer in autumn. The content of total P was 0.010.19 mg/l, which was 24 times as much in pool C as in the other pools. (5) The concentrations of the above minerals in each pool was nearly agreeable with those which were seen in neutral dystrophic lakes. (6) The reciprocal relations were seen among the amount of dissolved salts and the amount of albuminoid-N, organic-N or chlophyll content. The relationship was especially marked in the case of chlorophyll content. (7) The measurement of bacterial number was made monthly by the method of plate culture. The bacterial numbers were between ×102-103 per cc water of the pools and were fewer than those of eutrophic lakes. Two maxima and two minima occurred during 1952. The maxima were seen in spring and autumn, and the minima in winter and summer. In 1953 no tremendous abundance occurred, and a minimum was seen during the summer stagnation. (8) It was recognized that bacteria increased in general during the time of optimum temperature (1025°C). However, even in that time they decreased in accordance with the increase of Protozoa and Protophyta or with the shortage of dissolved oxygen. (9) The maximum size of bacterial population appeared at the same time with the maximum of chlorophyll content ; or, the latter followed immediately the former. The increase in the dissolved salts was seen at the same time with or immediately after the increase in bacterial population. The increase of chlorophyll followed the increase of salts. (10) The amount of inorganic salts was 40400 times as much in the living body as in the pool water. (11) According to physiological analyses, the minimum element in the water of pools for biological production seemed to be P rather than N. This shortage of phosphorus was considered to be caused by the abundance of humic substances.
日本陸水学会の論文

Studies on the biological production of fire pools in Tokyo:XI. The seasonal changes in the amounts of dissolved inorganic salts, organic substances and the number of bacteria, and the interrelation among them

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