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7 Factors in the Determination of Dissolved Oxygen in Surface Water


Dissolved oxygen content determination, is a major aspect of water pollution detection and assessment. To this end, this article analyzes the influencing factors of dissolved oxygen determination in surface water in conjunction with the definition of dissolved oxygen, focusing on the selection of the determination method and the assessment of the solution concentration, to achieve a multi-level analysis of the conditions of dissolved oxygen determination and to provide reference and guidance for the promotion of the sustainability of social resources.


Dissolved oxygen determination, an important branch of surface water survey and analysis, can survey and examine the vitality of surface water and the oxygen-rich content of water in all aspects. To further clarify the distribution of surface water and oxygen content, the analysis of the conditions affecting the determination can reduce the negative interference in the determination and improve the accuracy of product determination.

Overview of dissolved oxygen

Dissolved oxygen, the number of oxygen molecules dissolved in water, is measured in mg/L. Dissolved oxygen, as an important indicator of surface water testing, can accurately determine the current water quality, and water ecological conditions, and is also a major factor in the analysis of nutrient composition in water. Generally speaking, when the proportion of oxygen content in the water body does not exceed 5 mg/L, the water environment will be damaged, the water body circulation structure will appear anorexic state, the water body becomes black, odor and other phenomena, which the current surface water dissolved oxygen content is not enough to produce the negative hidden danger.

7 Factors in the Determination of Dissolved Oxygen in Surface Water

Factors affecting the determination of dissolved oxygen

The influence of measurement method selection

Dissolved oxygen content in surface water measurement and analysis process, due to the different measurement methods, the results will also exist corresponding differences. For this reason, the inspector needs to do a good job in the measurement environment before carrying out the work, and scientific selection of measurement methods. If the determination personnel can determine the determination means scientifically according to the local environment, the possibility of deviations in the results will be greatly reduced; on the contrary, the results of the determination of dissolved oxygen content in surface water will be more disturbed.

In the specific implementation of the determination of dissolved oxygen in surface water in a certain area, the staff in the determination of method selection points to determine: ① determine the location of surface water oxygen dissolution, do a good job in the determination of dissolved oxygen in surface water after circling the range, by the standard requirements to do a good job of measuring the location of the selection; ② for better water quality samples using the iodine method for determination; ③ for the determination of high nitrite content in water quality, should be sodium peroxide correction method for testing; ④ if the water contains suspended particulate matter, alum can be used to purify the test.

During the determination and analysis of oxygen content in surface water, combined with different water samples taken, choose the appropriate method for testing, not only to protect the accuracy of the measurement results but also the most important manipulation in the analysis of surface water survey.

The influence of the determination of the dissolved concentration

During the analysis of water dissolution determination, most of them directly use iodine for dissolution determination and determine the concentration of dissolved oxygen in the water according to the measurement results. However, in actual operation, residual air bubbles and water sample aeration often occur during water sample collection. Most of the problems in this part are caused by the improper adjustment of the dissolved concentration.

To avoid the problem of ineffective water dissolution measurement and analysis caused by improper control of dissolved concentration, the main points of staff in solubility measurement can be summarized as follows: ①Before the measurement of dissolved concentration, first use water samples to clean the dissolution bottle to ensure the dissolution The concentration in the bottle is kept similar to the concentration of the water sample; ② Use a straw to inject water into the bottle, and stop pouring when the water sample reaches 1/3 of the dissolved bottle; ③ After the water sample is taken out by the instrument, use a rubber Fix the tube, and put the cannula above the bottle mouth into the top of the bottle; ④ Keep the water sample in the bottle in normal contact with the outside through the pipe, and then measure the content in the water sample after everything is ready.

The interference analysis of water sample collection on the measurement of dissolved oxygen concentration is mainly affected by the interference of the measurement environment, and then the effectiveness of water sample measurement is not good, and the determination of influencing factors varies greatly.

Effect of dissolved oxygen concentration

The level of dissolved oxygen concentration will also have a corresponding interference with the overall test concentration. Especially when the concentration and specific gravity of the oxygen component in the air changes, the bubble content in the dissolved oxygen will also change accordingly. If the experimenter cannot adjust the dissolved oxygen in time at this time, there will be a problem that the dissolved oxygen concentration cannot be adjusted. . For example, during the measurement and analysis of dissolved oxygen concentration in water samples, manganese sulfate, and potassium iodide solutions are used for corresponding adjustments; at the same time, during the reagent analysis process of dissolved oxygen, if the sample liquid level in the reagent bottle is too much or exceeds the dissolved The basic standard of oxygen control is prone to the phenomenon of increased dissolved sediment inside, which in turn hurts the determination of dissolved oxygen content in water samples. On the contrary, if the dissolved oxygen adjustment period can be properly adjusted according to the differences in the social environment, it can not only meet the specific needs of the implementation of the current activities but also ensure the flexible adjustment and change of the relevant materials in terms of water sample solubility. And one of the distracting factors of scientific analysis.

Influence of dissolved oxygen water reagent

During the fixed dissolved oxygen inspection and measurement, to avoid the problem of changing the measurement results due to improper addition of reagents in the dissolved oxygen water, the measurement personnel also need to pay attention to the influence conditions of the overall oxygen content of the added solvent. For example, when manganese sulfate or potassium iodide solution in the reagent is added to the test, the tester is required to conduct a blank test on the water sample first, then analyze the manganese hydroxide precipitate, and finally use dissolved oxygen, manganese hydroxide, etc. To carry out redox. The basic situation of dissolved oxygen water samples should be properly dealt with by the reagent adjustment method in the water.

At the same time, to prevent the change of the reagent solution in the dissolved oxygen water sample, the experimenter can also directly add potassium hydroxide to the water body to reduce the water sample and then analyze the brown sodium hydroxide manganese precipitate to analyze the overall concentration of dissolved oxygen. Comprehensive evaluation and analysis of reagent volume. During the comprehensive investigation and exploration of water sample dissolution work, to ensure the accuracy of the measurement results, technicians also need to make appropriate standardized adjustments and analysis of solution reagents in the water body in combination with the basic situation of water sample development.

Effect of dissolved oxygen mixture

The interactive management of fixed dissolved substances in water samples lies in the adjustment and control of the dissolved oxygen mixture, to reduce the correlation interference at the level of the dissolved oxygen mixture. Combined with domestic water sample dissolved oxygen determination and analysis period, technicians analyzed the impact of mixture determination and the analysis points of the dissolved oxygen mixture management link as follows: ① Place the water sample in a narrow-mouth bottle and shake it sufficiently to fully dissolve the materials and water in the bottle Combined, after 1-2 hours of precipitation, observe and record the sediment situation; ②Combined with the current basic situation of water-oxygen interaction communication, do a good job in the all-round investigation of the chemical and physical properties of the water samples. The sediment will appear in the fastest form; ③ After the water body sample is fully shaken and shaken, if there is no more or larger-scale change in the dissolved oxygen mixture, it means that the accuracy of the test result of the water body sample is relatively high; on the contrary, it means There are some errors in the test results of water samples, and the experimenters need to re-test.

During the full implementation and investigation of fixed dissolved oxygen measurement and analysis, technicians not only need to coordinate the analysis and evaluation of various investigation factors in combination with the specific conditions of project implementation, but also need to combine the specific conditions of project implementation. Integration and multi-level evaluation of sample determination conditions.

Effect of dissolved oxygen acidification concentration

When exploring the acidification concentration of dissolved oxygen, if the acidification concentration integrated into the dissolved oxygen has reached the optimal standard, the color of the solution will generate a change in the comprehensive sediment. Therefore, in the process of evaluating and analyzing dissolved oxygen conditions, it is also necessary to combine the specific conditions of dissolved oxygen acidification measurement, analyze the basic conditions of dissolved oxygen acidification treatment, and properly evaluate and explore dissolved oxygen acidification conditions.

Combined with the specific situation of the current determination of dissolved oxygen acidification concentration, the analysis points of technicians in the aspect of acidification concentration adjustment can be summarized as follows: ① According to the law of acidification change of water samples, first add the appropriate sulfuric acid reagent to the water sample, stir well, and then use Potassium permanganate is used for reduction; 2. Using the low stability of the iodide ions in potassium iodate, sodium sulfate is used to comprehensively measure the content of the iodide ions. To avoid an excessive increase in the content of potassium iodate solution, it is advisable to control its specific gravity at about 1.5mL at this time; ③ If there are special water samples in the measurement process, the specific gravity of potassium iodate solution can be increased to 1.8mL; ④ During the process of adding concentrated sulfuric acid to the water sample, pay attention to observe the overall color change of the solution. When the color changes from colorless to slightly yellow, the amount of potassium iodate solution should be appropriately reduced.

When measuring dissolved oxygen in surface water, pay attention to the analysis and evaluation of the oxygen content in it, and reasonably grasp the influencing conditions, especially the acidic factors, which are also the main influencing factors.

Influence of starch indicator in dissolved oxygen

The determination and analysis of the indicator concentration of starch in the water sample refer to the analysis and evaluation of the influencing factors in the inspection process of the water body sample by the staff after the solution is acidified and left to stand for 10 minutes. Generally speaking, the color of the water sample changes because the content and ratio of ions in the water sample show a continuous change after the acid-base solution collides with each other. When the starch precipitant interferes with the internal factors, the ions in the solution and the starch content will also change accordingly. At the same time, the starch indicator in the water sample will also display the changes in the water sample the first time when the result deviates. Therefore, the analysis of the changes in starch indicators during water sample collection can be used as the main standard for water sample detection and research, and then detailed investigation and research are carried out. This is also one of the main contents of the determination of dissolved oxygen in surface water.


To sum up, exploring the influencing factors of dissolved oxygen measurement in the surface water is a theoretical summary of water environment detection and investigation. On this basis, this article analyzes the influence of the determination method selection, the determination of dissolved concentration, the dissolved oxygen concentration, the dissolved oxygen water reagent, the dissolved oxygen mixture, the dissolved oxygen acidification concentration, and the starch in dissolved oxygen. The influence factors of the determination of dissolved oxygen in surface water are sorted out. Therefore, the research results of this article provide a new perspective for the detection and exploration of the surface environment.

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