Sediment Diagenesis

Question 1

What is Sediment Diagenesis and its Key processes?

Answer 1

Diagenesis – is the sum of all processes that changes a sediment
- Physical effects e.g compaction
- Biological/physical/chemical influence of burrowing organisms: bioturbation and bio irrigation
- Formation of new minerals and modification of pre-existing minerals
- Complete or partial dissolution of minerals
- Post-depositional mobilization and migration of elements: elements migrate in and out of the sediment by diffusion, driven by concentration gradients
- Bacterial degradation of organic matter

Question 2

What is redox potential?

Answer 2

Expresses the tendency of an environment to receive or supply electrons (pE), measurement of a systems’ capacity to oxidize or reduce
- An oxic environment has a high redox potential because O2 is available as an electron acceptor
- An anoxic environment has low redox potential because of the absence of O2
- measure voltage then use Nernst equation to convert to redox potential (pE)

Question 3

What is the importance of Redox reactions?

Answer 3

redox reactions control organic matter oxidation and element cycling in aquatic ecosystems

Question 4

What can Eh-pH diagrams be used for?

Answer 4

Eh-pH diagrams describe the thermodynamic stability of chemical species under different biogeochemical conditions