Page 103 - Soil and water contamination, 2nd edition

90 Soil and Water Contamination

7. Explain why clay particles tend to flocculate as the salinity of the water increases.
8. What is the difference between decomposition and mineralisation of organic matter?

9. The decomposition of organic matter in lake bed sediments leads to stratified layers that
are characterised by the dominant redox reaction. The thickness of these layers is in the
order of a few centimetres in organic-rich bed sediments.
a. Explain why organic matter decomposition leads to the formation of such layers.
b. Which substances act as oxidants in the successive layers?
c. How can these layers be recognised in terms of the presence or oxidants of reductants
or reaction products?
10. Describe the role of the C:N ratio for the decomposition of organic matter.

11. Describe how the base saturation changes as the pH of a soil decreases.

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Soil and Water.indd 102
Soil and Water.indd 102 10/1/2013 6:44:24 PM