Experiments Regarding the Sulfide Formation in Sediments 675 



closed with neopiene-stoppers, nearly no water above tlie sedi- 

 ment layer. The sediment consisted of a sandy clay and had a high 

 content of organic substances. Only a very thin top-most layer 

 was aerobic; all the other sediment was anaerobic and black, due 

 to metallic sulfides. It was very homogeneous and gases were 

 fomied. Sample tubes were removed at intervals (for 11 weeks) 

 from the sediment for analysis. 



Laboratory Studies 



The superficial layer of the bottom of a very productive 

 shallow water pool near Port Aransas was collected, homogenized 

 by a mixer and filled into a number of glass containers as shown 

 in Figure 1. The sandy-clay sediments contained a large hetero- 

 geneous living population of blue green algae, flagellates, proto- 

 zoans, diatoms, bacteria and nematodes. In the experiments con- 

 ducted at the German coast, sediments consisted mainly of sandy 

 clay and decomposing benthic algae like Laminaria, Fucus and 

 red algae. The containers were stored in Texas at 30 C and in 

 Germany at 18 C. The containers were closed by neoprene- 



Fig. 1. Container used for the storage of homogenized sediments. Ex- 

 planation see text. 



