植物プランクトン量と過マンガン酸カリ消費量

Abstract

The permanganate consumption of the culture medium containing a marine plankton diatom Skeletonema costatum was determined by using cultured samples and was proved that the value to be proportionate to the amount of the cells in the solution. When the plankton quantity expressed in W. B. U. (Warm Brown Units)* the following equation can be obtained (Fig. 1); W. B. U.=1.3×O2Cons. mg/1 This result shows that the oxidisability of the phytoplankton in minute size such, as Skeletonema costatum could be available as one of its quantitative indicators. But, we must know that there are few cases in which the above mentioned relations do not stand true. For instance, when a nutrient salt such as nitrate or phosphate has been completely exhausted in the medium, Skelctonema growth stops distinctly in W. B. U. and also in cell numbers, but its carbon assimilation alone is still continued for a while, and as the result of it the oxidisability of the diatom reaches to an abnormally high value (Fig. 2). From this fact a problem concerning the selection of the adequate unit for the quantitative determinations on the phytoplankton was discussed. (*In the culture experiments on Skeletonema costatum Warm Brown Units has been used exclusively by the author for the quantitative expression of the diatom. It is determined throu ?? h both the colour and the turbidity of the ditom-growing culture in its living state, and it has the following relations against to some other units; W. B. U.= 1.6×10-8×Number of Cells/1 W. B. U.= 4.7×Units of Pigment/cc)