Study On Determination Of Living Algae In Fresh Water By Dehydrogenase Activity (DHA)

Algal bloom causes a good many damages to drinking water. However, there are few research papers to focus on determination of algae, and currently there is not a widely accepted method for algae determination.Dehydrogenase is a kind of key enzymes in organism, whose activity is an indicator reflecting activity of microbe. Therefore, the detection of dehydrogenase activity (DHA) is widely used in many fields. However, it has not been reported that the detection of dehydrogenase activity is introduced in determining algae quantitatively. This study is to find a quick, stable and practicable determining method to measure living algae concentration in fresh water.Firstly, this dissertation states the significance and feasibility to establish this new method, reviews the research progress and application in environmental monitoring field.Secondly, this dissertation researched in determining algae by TTC-DHA, including the experimental conditions such as wave length for colorimetry, extractants, extracting duration, pH, reducing agent and its concentration, reaction time for making standard curve and activity determination, temperature of water bath, terminators, TTC concentration and so on. According to these research results, the determining method of algal concentration was optimized, using TTC as an artificial hydrogen acceptor. The suitable measuring range of this method is 0.025～6μg TF/mL water sample· h, in which the correlation coefficient of standard curve is 0.9973, the sensitivity is 0.00032μg TF/mL water sample · h, and the detection limit is 0. 001μg TF/mL water sample· h.Thirdly, this dissertation researched in determining algae by methylene blue-DHA, including the experimental conditions such chlorophyll and oxygen, pH, terminators, reaction time of activity determination, temperature of water bath, methylene blue concentration and so on. According to these research results, the determining method of algal concentration was optimized, using methylene blue as an artificial hydrogen acceptor. The suitable measuring range of this method is 0. 12~24μ g methylene blue /mL water sample·h, in which the correlation coefficient of standard curve is 0.9988, the sensitivity is 0.006μg methylene blue /mL water sample·h, and the detection limit is 0. 06μg methylene blue /mL water sample · h.