8. Biogeochemical Cycling -> Iron And Sulfar Cycles

Question 1

Name the reservoirs where Iron and Sulfur are found

Answer 1

Sulfur reservoirs
- oceans contain the most sulfur
- sulfur can also be found in sediments and rocks

Iron reservoirs
- iron ores and minerals such as magnetite, hematite, goethite etc
- metallic iron on the other hand is virtually non existent
eg. meteorites and xenoliths

Question 2

Detail the different Iron cycle

Question 3

Detail the Sulfur cycle

Question 4

What microbes oxidise Iron at a low pH

Answer 4

• acidophilic bacteria and archaea that have been reported to catalyse the dissimilatory oxidation of ferrous iron or reduction of ferric iron
• where ph < 4 (acidic)
  Eg. Acidithiobacillus ferrooxidans, Leptospirillum, Ferroplasma, Sulfolobus
• bioleaching microbes

Question 5

What is bioleaching and why is it advantageous?

Answer 5

Bioleaching is when bacteria is added to the acid leaching of sulfide minerals to increase amounts of ferric iron (an oxidant) and produce acid

Bioleaching is advantageous as it can stabilise sulphate toxins from the mine without causing harm to the environment. It is also more cost effective than smelting processes.
- bioprocessing is the way of the future

Question 6

How do microbes bioleach?

Answer 6

Bioleaching is the conversion of insoluble metal self-identify (or oxides) to water soluble metal sulfates using microbes

Direct bioleaching uses minerals that are easily receptive to oxidation to create direct enzymatic strike using the microorganisms to separate the metal and the ore

In indirect bioleaching microorganisms are not in direct contact with minerals during the process

Question 7

Detail copper leaching with microbial action