Experiments Regarding the Sulfide Formation in Sediments ^11 



2.0 g MgSOi 



0.1 g ascorbic acid 



0.05g asparagine 

 trace Mohr's salt 

 750 ml aged sea water 

 250 ml aqua dest. 



3. For the enumeration of the bacteria producing hydrogen sul- 

 fide from organic sources: 



1.0 g yeast extract 



5.0 g neopeptone 



0.1 g cystine 



0.5 g K.HPO4 



1.0 g NH.Cl 

 trace FeCL 

 750 ml S04-free artificial sea water 

 250 ml aqua dest. 



4. For the enumeration of the anaerobes we used a modified Zo- 

 Bell's 2216 medium: 



5.0 g Bacto-peptone 



Bacto-yeast extract 



glucose 



ascorbic acid 



FeP04 



aged sea water 



aqua dest. 



The last three media were used in completely filled prescrip- 

 tion bottles. They were incubated in Texas at 28 C and in Helgo- 

 land at 18 C. The pH was in all cases 7.6. 



RESULTS 



Figure 2 shows the results of the first series of experiments 

 in the natural environment. The sulfides increased within eleven 

 weeks, 0.284 mg/g wet sediment, while the sulfates decreased, 

 0.577 mg/g wet sediment. A part of the sulfate must have been 

 transformed into something else than sulfide. It would be conceiv- 

 able that a certain amount of hydrogen sulfide formed from 

 organic sources during the decomposition was transformed into 

 such another form. The Eh became unexpectedly less reducing 



