有機物汚染海水の溶存酸素の一定量法について
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概要
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A study has been designated to determine a method of estimating the dissolved oxygen in the sea water polluted with organic matter. Interference in the determination of the dissolved oxygen in sea water by Shibata-Miller's method, especially due to metallic ions in it, results in indistinctness of the end point of titration. But it could be avoided by using together dimethylglyoxime and potassium sodium tartarate as chelating agents. Dimethylglyoxime also acts as an indicator. The end point of titration could be made more distinctive by using methylene blue complementally as an indicator. The procedures of the present method are as follows: Place two drops of 0.1per cent methylene blue solution at the bottom of a test tube (5 × 20cm.). Add 5ml. of liquid paraffin in the tube and pour 50ml. of sample by means of an injector under the paraffin layer. Add 7.5ml. of dimethylglyoxime-potassium sodium tartarate reagent (dimethylglyoxime 1.0g., potassium sodium tartarate 35g., and sodium hydroxide 10g. per 100ml.), and 2ml. of concentrated ammonium hydroxide along the wall of the test tube. Stirring the water layer, titrate with ferrous ammonium sulfate solution (ferrous ammonium sulfate 1.08g. and 95 per cent sulfuric acid lml.per lOOml.) until the pink color is held over 10 seconds. The ferrous ammonium sulfate solution is standardized against the distilled water saturated with oxygen. In that case, the dissolved oxygen content of the distilled water is calculated by WHIPPLE and WHIPPLE's table. In order to test the validity of the present method, the oxygen content in sea waters containing several organic matters was estimated by the present and other methods. a) In the sea water to which was added 0.1 per cent of organic matter such as glucose, acetic acid, citric acid, casein hydrolyzate and peptone etc., the organic matter had little or no influence on the determination of dissolved oxygen by the present method or by TOMIYAMA and KOJIMA's method. But in each case of the method of ALSTERBERG, RUCHHOFT, MOORE, and BEADLE, the value of estimation, when organic matter was added, was less than that when organic matter was not added (Table 2). b) In the sea water polluted by the Sasebo river, the river water polluted by sewage, and the water of fish-culture pond, the values obtained by the methods of the author, and of TOMIYAMA and KOJIMA were close to that of the carbone dioxide method by WINKLER and SUGAWARA. But there was a considerable difference between the values obtained by ALSTERBERG's method and that of the carbone dioxide method. There was no appreciable difference among the four methods employed in the sea water to which were added the wastes of the starch factories (Table 3). From the results of these experiments, it may be concluded that the present method was relatively free from interference by the presence of organic matter and gives reliable results.
- 社団法人 日本水産学会の論文