2.4. (9/2) Clay minerals, saprolite, and soils (Origin of sediments) Flashcards
What are the chemical ways to erode a rock?
- rainwater dissolves
List a sand factory
Biota
Soil
Saprolite
Core stones
Weathering front
Solid rock
Which acid does water and carbon dioxide make?
carbonic acid H2CO3
What kind of acid is H2CO3?
a simple, weak one
Is rainwater pH neutral?
no, it is weakly acidic (pH 5)
What is pH?
- A measure of how basic or acidic a solution is
- it is taking the negative log of the concentration of hydrogen ions -log(H+)
How do we know something is acidic? basic? neutral?
acidic: low pH
basic: high pH
neutral: 7
Which pH has more hydrogen ions?
acidic
what kind of relationship does pH have with hydrogen ions?
inverse
what kind of scale does pH have?
log scale at a factor of 10
What is the pH of carbonic acid?
A little under 5
Why is rainwater acidic?
Because it interacts with carbon dioxide
What are organisms doing to the organic material in the soil?
roots, fungi, and microbial communities are decomposing organic material in the soil
Which gas is released as a function of decomposition? how?
carbon dioxide through respiration
What are soils high in?
pCO2 environment
what does the p stand for in pCO2?
partial pressure of carbon dioxide gas
What is the parts per million of CO2 in the atmosphere?
about 420 ppm (partial pressure)
What is the partial pressure of CO2 in the soil?
10^4 - 10^5 ppm
What happens in the soil when it rains?
- when rainwater soaks into the soil, it picks up many more hydrogen ions
- soil water is more acidic than rainwater