Sodium sulphate

Endpoint summary

Additional information

Microbes play pivotal roles in the Sulfur cycle. In the case of sulfate:

 

Sulfate provides microorganisms with the possibility of carrying out sulfate reduction to derive their energy. Sulfate is used as an electron acceptor to form sulfide (H2S) this is a process known as dissimilatory reduction and this occurs anaerobically. Alternatively reduction of sulphate for use in amino acid syntheses for example can also occur and is known as assimilatory reduction forming organic sulfur. Other microorganisms reduce the elemental sulphur further still. Sulphite is also a critical intermediate that can be reduced to sulfide as well as oxidized back to sulphate completing the cycle.

 

Some Species commonly associated with these steps are:

 

Aerobic sulfur oxidation - occurs in Thiobacillus Beggiatoa and Thiothrix sp

Anaerobic sulfur oxidation - occurs in Chlorobium and Chromatum and Desulfovibria sp

Sulfur reduction - occurs in Alteromonas,Clostridium sp

 

Summary written using data obtained from (The sulphur Cycle Microbiology Prescott Harley and Klein 1996)

A schematic representation of the sulfur cycle can be found on (http://www.lenntech.com/sulfur-cycle.htm).

 

 

From Source: SODIUM SULPHATE CAS N°: 7757-82-6 OECD SIDS April 2005

Sodium sulfate may be used as an electron acceptor in anaerobic sulfate reduction by sulfate reducing bacteria. Sulfate is converted to (hydrogen)sulfide (Greben,et al.,2000 and Henryet al.,2000).

In the presence of organic substances sodium sulfate is reduced as described in the following reactions:

Sugar:                         C₁₂H₂₂O₁₁+ 5 H₂O + 4 SO₄^{2 -} >>> 4CO₂+ 8 H₂+ 4 HS^-+ 8 HCO₃^-+ 4 H⁺

                                   8 H₂+ 2 SO₄^2-+ 2 H⁺>>>>2 HS^-+ 8 H₂O

                                   C₁₂H₂₂O₁₁+ 8 H₂SO₄ >>>8S + 12 H₂CO₃+ 7 H₂O

Ethanol:                      2 C₂H₅OH + 3 SO₄^2- >>>3HS^-+ 3 HCO₃^-+ 3 H₂O + CO₂

                                   C₂H₅OH + H₂SO₄ >>> 2S + 2 H₂CO₃+ 3 H₂O

 

The sulfur cycle (College of Biological sciences, 2003):

• Assimilative sulfate reduction: sulfate (SO₄^2-) is reduced to organic sulfhydryl groups (R-SH) by plants, fungi and various prokaryotes.


• Desulfuration: organic molecules containing sulfur can be desulfurated, producing hydrogen sulfide gas (H₂S).


• Oxidation of hydrogen sulfide produces elemental sulfur (S^o). This reaction is done by the photosynthetic green and purple sulfur bacteria and some chemolithotrophs.


• Further oxidation of elemental sulfur by sulfur oxidizers produces sulfate.


• Dissimilative sulfur reduction: elemental sulfur can be reduced to hydrogen sulfide.


• Dissimilative sulfate reduction: sulfate reducers generate hydrogen sulfide from sulfate.