SULFUR

1
GES175, Science of Soils
Lecture 9 SULFUR
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Relevance of Soil Sulfur
Slide 9.2

• Used in amino acids, vitamins
• Plant Deficiency
• u small and spindly plants
• u yellowish leaves (new tissue)
• Environmental Problems
• u acidification
• - acid rain
• - sulfide oxidation

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Sulfur Cycle
Slide 9.3
plants animals
SO4-2
2. Immobilization
organic-S
3
4. reduction
(So)
S-2
1. mineralization
3. Oxidation
4
Slide 9.4
S oxidation and reduction?
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Acid Mine Drainage
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Result of Acid Mine Drainage
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S oxidation and Reduction
Slide 9.7

• Oxidation
• S-2 ¾(O2) SO4-2
• Autotrophic microorganisms
• u energy obtained from S oxidation
• Acid producing process
• u S or S-2 ¾ H2SO4

8
Reduction
Slide 9.8
e- e-
SO4-2 ¾¾ So ¾¾ S-2

• Anaerobic process
• u organisms use S in place of O2
• as a terminal e- acceptor
• u sulfate reducing bacteria
• (obligate anaerobes)

9
Reduction (contd)
Slide 9.9

• S-2 can be toxic
• u forms H2S gas
• u reacts with Pb, Cd, Zn Þ
• insoluble compounds
• mostly, heterotrophic organisms
• u require OM for energy source