centers of the organism, not react with chemical compounds contained in the 

 water and be available for use. In addition, the algicides should be safe 

 for man, harmless to fish and non-corrosive to metallic parts of equipment. 

 Chemicals such as 2,3-dichloronaphthoquinone (also called figone, frigone, 

 2,3DNA, 2,3SNA) and hexachlorobutadiene are suggested as algicides, as well 

 as rosein-amide-D-acetate, monuron, simazine and many other algicides. 



The physiological effect of some algicides, monuron and diuron on blue- 

 green algae in particular, amounts to an acute inhibition of photosynthesis. 

 Diuron, the molecules of which contain two chlorine atoms and methyl groups 

 in addition to the phenol ring, possess the most clearly-pronounced effect 

 on blue-green algae. However, the introduction of these algicides into a 

 reservoir impairs the organoleptic properties of the water, and the pro- 

 cesses of nitri- and nitrof ication are disturbed. Through toxicity tests 

 on other aquatic organisms 2 and 10 mg/ liter were shown to have a substan- 

 tial effect on blood morphology, phagocytic activity of leucocytes and 

 other changes in test animals. 



Many algicides are volatile or readily hydrolyzed, thereby requiring re- 

 peated application, sometimes 3-4 times in a summer. 



Searchers for new compounds to effectively protect the water from blooms 

 led us to study the effect of complex ores and products of their processing 

 on various species of algae. Together with A. P. Terent'ev and N.S. 

 Stroganov, we established that complex ores containing zinc, copper, cad- 

 mium, nickel, lead, silver, and other chemical elements act effectively on 

 the algae which produce blooms in water bodies. In tests 2 mg/liter reduced 

 the number of algae cells in 30 days and eliminated them in 45 days. Under 

 the effect of complex ores, the filamentous alga, Cladophora , decreased 

 sharply in biomass and the colony darkened and decomposed into separate 

 cells. Green algae proved more resistant to the effect of ores, but was 

 severely depressed. First the chlorophyll disappears, then the cells lose 

 pigment and in 30 days they are almost entirely dead. 



The effect of complex ores is a complex process, but the investigations 

 conducted show that the slow change of complex metals into a soluble state 

 and their low initial concentration evidently favor their inclusion into 

 the algae's biochemical reactions and lead to inhibition of various vital 

 functions. The slow and weak dissolution of the ores is easily overcome if 

 the ores are introduced into the water body 10-15 days prior to the begin- 

 ning of phytoplankton development. In some cases, it is convenient to 

 introduce the algicide into the ice in the spring so that water contains a 

 solution of substances f"*om the complex ore in the required concentration 

 prior to the spring outbreak of algae development. Thus, one can prevent 

 an increase in the number of algae by controlling their numbers, and not 

 just decreasing them. Complex ores, usable as algicides, are resistant to 

 hydrolysis and not susceptible to destruction by bacteria. Their slow dis- 

 solution in water makes it possible to maintain a concentration in the re- 

 servoir which is toxic for algae for a long period of time. 



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