ENV100Y5 Lecture Notes - Lecture 22: Soil Ph, Ion Exchange, Cation-Exchange Capacity
Module 3: June 4-June 15
Date: Monday, June 4
SESSION 24: SOIL RESOURCES (I)
Readings: Chapter 7
Central Case: Mer Bleue bog
● A 35 km2 protected wetland
● Peat soils formed over 8000 years; up to 6m thick → soil has a dynamic component
● Carbon balance in peat - reservoir in constant flux:
○ Primary production stores carbon
○ Decomposition releases carbon
● Interdisciplinary research project studying the influence of climate on carbon balance
(and vice versa)
Soil is a complex material
● Mineral matter, organic matter, water, gases
● Dead/living microorganism; decaying material
● Bacteria, algae, earthworms, insects, mammals, amphibians, reptiles
● Supports plant growth
Soil formation starts with bedrock
● Parent material = base geologic material of soil
● Bedrock = continuous mass of solid rock (the Earth’s crust)
● Regolith (sediment) = broken-up rock → base material that produces soil
Lunar regolith
● The surface of the moon is not a soil.
● You can only have soil where there is dead/living microorganisms
Weathering = processes that break down rocks
● Physical (mechanical) = no chemical changes in parent material
○ E.g. wind, rain, thermal expansion and contraction, water freezing
● Chemical = substances chemically interact with parent material
○ E.g. water (physical -wave/freezing; chemical - dissolve) and gases
● Biological = organisms break down parent material
○ E.g. tree roots and lichens
Pressure Release
● After glacier retreats, causes damage to rock, different rocks bounce from pressure at
different rates, so rocks lift up
Karst: dissolution of layers of bedrock
● If bedrock is largely limestone, it dissolves quite easily under acidic conditions which
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Document Summary
Peat soils formed over 8000 years; up to 6m thick soil has a dynamic component. Carbon balance in peat - reservoir in constant flux: Interdisciplinary research project studying the influence of climate on carbon balance (and vice versa) Bacteria, algae, earthworms, insects, mammals, amphibians, reptiles. Parent material = base geologic material of soil. Bedrock = continuous mass of solid rock (the earth"s crust) Regolith (sediment) = broken-up rock base material that produces soil. The surface of the moon is not a soil. You can only have soil where there is dead/living microorganisms. Physical (mechanical) = no chemical changes in parent material. E. g. wind, rain, thermal expansion and contraction, water freezing. Chemical = substances chemically interact with parent material. E. g. water (physical -wave/freezing; chemical - dissolve) and gases. Biological = organisms break down parent material. After glacier retreats, causes damage to rock, different rocks bounce from pressure at different rates, so rocks lift up.
