Experiments Regarding the Sulfide Formation in Sediments 679 



log N / g wet sediment 

 7 r 



r 

 / 



. *- - - 



r" 



■^-.i — 



■♦. \ 



_ — a 



■, ^3 a 



> b 



time in weeks 



Fig. 3. Bacterial numbers corresponding to the chemical data of Figure 2. 

 Aerobic- (a), anaerobic- (b), HjS from organic sources producing- (c) sul- 

 fate reducing bacteria ( d ) . 



inoculation. After different times the sulfide and sulfate of the 

 containers were determined. It is evident that in this series of 

 experiments the increase of sulfide was less than the decrease of 

 sulfate and a part of the sulfur must have been transformed into 

 another form than sulfide. 



Figure 5a shows the results of experiments in which the 

 superficial layers of sediments were collected, filled into glass 

 containers and stored for different lengths of time. In addition 

 to sulfate and sulfide, we determined that part of iron which 

 was not soluble in liot diluted hydrochloric acid but onlv in hot 

 nitric acid. Based on the investigations of Sugawara, Koyama and 

 Kozawa (9) we assumed that this iron is bound in the form of 

 pyrite. In both experiments a considerable increase of sulfate- 

 sulfur, sulfide-sulfur and pyrite-sulfur took place. The increase 



