Some Chemical Investigation with a Special Reference of SiO2, and P2O5 Contents of the Water of the Rivers Huzigawa and Kanogawa in the Sizuoka Prefecture

[摘要] We measured water temperature, hydrogen ion concentration, SiO2, P2O5, and Cl Contents of the water of the rivers Huzigawa and Kanogawa over the period from Sep. 1935 to Sep. 1936. As the water of the Huzigawa was found to be turbid for the most part of the year, Denigeés' method for P2O5, as it is, could not yield but very rough value, whose average came out to be 0.060mg/L. We tried a new method to make the turbid water transparent, adding a drop of 50% H2SO4 and 10mg of alum for 100cc of the test water and filtering after a day or two. Then we applied Denigeés' method and obtained 0.218mg/L as the average value. The discrepancy of the above two values, which is too serious to be attributed to the difficulty in colorimetry for turbid test water, may in all probability be due to the dissolution of P2O5 contained in the suspension during the process of making transparent. We now come by a question as to the meaning of P2O5 content of turbid water whose suspension contains itself P2O5. Apart from this question, it is a matter of interest that Mr. K. Kimura, measuring P2O5, SiO2, etc. on board a ship at several points in north Suruga Bay in 1931, found that P2O5 content of the surface sea-water at the point 1400m SW from the mouth of the river Huzigawa amounts to 0.250mg/L-the value markedly large in comparison with those at other points, while Mr. E. Kurasige in 1933 reported 0.0321mg/L as the average value of P2O5 content of the water of the Huzigawa-the value not reconcilable with the former. In the light of our present investigation, it may be possible that P2O5 contained in the suspension in the river water dissolves under suitable condition in the sea, and if this is the case, the above mentioned relation can be explained at once. It is also a matter of interest that, “Sakura-ebi” (Sergestes prehensilis) which had been found only near the mouth of the Huzigawa was found last year in the offing of Okitu and Miho where P2O5 content is large next to the mouth of the Huzigawa according to Mr. K. Kimura. It seems that abundance in P2O5 has some connection with the yield of Sakura-ebi, but it is not exactly known.Jan. 15, 1937, At Misima.

[学科分类] 大气科学