Chapter 19 



Redox-Conditions and Precipitation of 

 Iron and Copper in Sulphureta 



R. SucKovv and W. Schw.\rtz 



J. he development of a sulphuretiim in nature is connected witli 

 changes of redox-conditions in tlie mud and the supernatant 

 water. The term "Sulphuretum ' was introduced by Bass-Becking 

 ( 1 ) . First of all, the ecological conditions are characterized by the 

 presence of H^S, originating from desulfurication, putrefaction, 

 or vulcanism. The biotope is modified by temperature, pH, 

 salinity, light, nuti^itional materials, etc. Sulphureta occur in deep 

 water or low water, or even within the tidal range; at different 

 temperatures, even under themiophilic conditions; at pH up 

 to 9-10 or more; in fresh water, brackisli water, seawater and 

 concentrated brines. In general, conditions are anaerobic but 

 without sharp limits and there are in a sulphuretum also habitats 

 with a higher partial pressure of oxygen or temporary variations 

 from anaerobic to more or less aerobic conditions. 



The primary type of microbes of the biocenosis are sulfur- 

 microbes with a relatively high number of HlS tolerant bacteria, 

 Cyanophyceae, Protococcales, diatoms, flagellates, rhizopods, and 

 ciliates. The interest of microbiologists has been concentrated 

 upon the microbes of the sulfur cycle so that our knowledge about 

 the accompanying microbes is low; their metabolism and life 

 conditions have not yet been thoroughly explored. 



We have studied the changes of Eh, pH, rH.. and HuS-pres- 

 sure in sulphureta which developed under marine and brackish 

 (nearly limnic) conditions in aquaria with mud/water layers 

 of about 75 cm height. We used a H-S producing blackish mud 

 its natural biocenosis of microbes and small metazoa. To the 

 from the Baltic Sea with high content of organic matter and with 



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