養鰻池水炭酸量の日中変化

Abstract

1. The diurnal fluctuation of carbon dioxide content of water in eel-culture-ponds was studied by means of the diffusion analysis method. 2. Total CO2, HCO3- as well as H2CO3 (dissolved gas of carbon dioxide plus free car-bonic acid) were found to decrease in the daytime and to increase in the nighttime. Their minimum figure was observed in the afternoon at the time when O2 was at its maximum, and the maximum one was observed early in the morning at the time when O2 was at its minimum. The fluctuation of CO3- content was contrary to that of other forms. (Fig. 1-3.) 3.The range of the diurnal fluctuation of carbon dioxide content was proportional to the density of phytoplankton, the density of fish, the total amount of solar radiation, and the tem-perature of water. (Table 1.) 4. H2CO3 content of the water ranged from 0.003 to 0.821 mEq./l early in the morning at its maximum. These values were considered not to cause the surfacing of eels which is a sign of dyspnoea. (Table 2.) 5. Total CO2 content of the water ranged from 0.11 to 3.58mEq./l in the afternoon at its minimum. (Table 2.)