Chapter 20 



The Distribution of the H2S in the Lake 



of Faro (Messina) with Particular Regard 



to the Presence of "Red Water" 



Sebastiano Genovese 



I 



n the course of my previous observations ( 1 ) on the physical 

 and chemical conditions of the brackish lakes of Ganzirri and 

 Faro (Messina) performed in 1950 and 1951, I had noted in 

 the latter environment, the presence of increasing amounts of 

 hydrogen sulphide from 12 meters tow^ards the bottom. 



Later on I had isolated a strain of Desulfovibrio desulfuricans 

 from the mud taken from the bottom of that lake and studied, in 

 collaboration with Pichinoty and Senez (7), its biochemical 

 characteristics, by Warburg's manometric method. At the same 

 time, counts of sulphate-reducing bacteria on mud samples and 

 waters collected at different depths were carried out. 



In the course of these previous investigations, by means of 

 laboratory cultures, I could also ascertain the presence of purple 

 and green sulphur bacteria in the lake of Faro (6). 



The morphological characteristics of above environment in- 

 clude a constant presence of a more or less compact layer of 

 hydrogen sulphide from a certain depth down to the bottom; 

 thus it seemed advisable to follow, during a full year, the changes 

 in the quantitative distribution and stratification of the above 

 gas, in relation to the changes in the quantity of dissolved oxygen 

 in the superficial layer of the water. 



MATERIALS AND METHODS 



The brackish lake of Faro ( Fig. 1 ) , is situated in Sicily, 

 North of Messina, near Capo Peloro. Its shape is almost circular 

 witli its main diameter towards NW-SE of 661 m; its surface is 

 263,600m". In the center, the lake has a depth of 28 m, a rather 

 exceptional value for litoraneous brackish lakes. Such a depth 



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