SECTION 8 



THE ROLE OF ALGAE IN THE POLLUTION OF RESERVOIRS 

 AND PROBLEMS OF CONTROLLING THEIR NUMBERS 



V.G. Khobot'ev 1 



Water pollution, both marine and freshwater, from industrial wastes 

 changes the living conditions for all living organisms and disturbs the es- 

 tablished communities. In some polluted waters, with nutrient enrichment 

 and slightly increased temperature, favorable conditions are created for 

 massive development of algae. Algal cell counts reach millions or even 

 billions in a single liter. 



The massive development of phytoplankton creates a considerable nui- 

 sance in water supplies, since it often disturbs treatment processes and im- 

 pairs the quality of water produced. Algal blooms in water bodies of this 

 type promote the intensified growth in underground mains and equipment, com- 

 plicating treatment and sometimes causing equipment failure. 



In cooling ponds blooms facilitate the formation of thick, compact sur- 

 face films that hinder evaporation and heat loss from the surface, thereby 

 reducing normal cooling of waste water. The growth of algae also reduced 

 C0 2 through intense photosynthesis and produces scum on the inner surfaces 

 of heat-exchange equipment. Removal of this scum frequently requires a con- 

 siderable expenditure of labor, time, and resources. Blooms caused by blue- 

 green algae also considerably degrade drinking water quality, giving the 

 water an unpleasant taste and odor. The taste is caused by the emission of 

 sulphur-containing compounds produced by the blue-green algae. Methymercap- 

 tan, dimethylmercaptan, isopropylmercaptan, dimethylsulphide, and others 

 have been identified in decaying cultures of these algae. The odor of dime- 

 thylsulphide, brought about by the presence of such amines as methylamine 

 and ethylamine, strongly resembles the smell of fish. A similar smell in 

 natural water associated with the development of certain species of algae 

 is caused by dimethylsulphide. 



The massive development of algae creates difficulties in the operation 

 of other water plants as well as in canals and irrigation systems. For con- 

 trol of phytoplankton, different means have been widely and effectively 

 used in many cases. Biological, physical, mechanical and chemical methods 

 of controlling "blooms" in reservoirs are well-known. 



'Moscow State University 



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