ASBOG ASBOG - Association of State Boards of Geology Geochemistry and Soil Science Questions and Answers 1 — Questions and Answers
Question 1: Which element is the most abundant by weight in the Earth's crust?
- Silicon
- Iron
- Oxygen (Correct answer)
- Aluminum
Correct answer: Oxygen
Oxygen is the most abundant element in Earth's crust, comprising approximately 46% by weight.
Question 2: Eh-pH (Pourbaix) diagrams are used in geochemistry to display the stability fields of what?
- Rock types and textures
- Minerals and aqueous species (Correct answer)
- Soil grain sizes
- Seismic wave velocities
Correct answer: Minerals and aqueous species
Eh-pH diagrams display the thermodynamic stability fields of minerals and dissolved species as a function of redox potential and acidity.
Question 3: Which soil horizon is characterized by the accumulation of illuviated clay, iron oxides, and aluminum?
- A horizon
- O horizon
- B horizon (Correct answer)
- C horizon
Correct answer: B horizon
The B horizon is the zone of illuviation where materials leached from overlying horizons accumulate, including clay, iron oxides, and aluminum compounds.
Question 4: What does CEC stand for in soil science?
- Calcium Exchange Capacity
- Cation Exchange Capacity (Correct answer)
- Carbon Equivalent Concentration
- Chemical Element Content
Correct answer: Cation Exchange Capacity
Cation Exchange Capacity (CEC) measures the total capacity of a soil to hold exchangeable cations and is a key indicator of soil fertility and contaminant retention.
Question 5: Acid mine drainage (AMD) is primarily generated by the oxidation of which mineral?
- Calcite
- Feldspar
- Quartz
- Pyrite (Correct answer)
Correct answer: Pyrite
Pyrite (FeS₂) oxidizes when exposed to water and oxygen, generating sulfuric acid that dramatically lowers pH and mobilizes heavy metals into drainage water.
Question 6: In the USDA soil texture triangle, a soil with roughly equal parts sand, silt, and clay is classified as:
- Sandy loam
- Silty clay
- Clay loam
- Loam (Correct answer)
Correct answer: Loam
Loam contains approximately balanced proportions of sand, silt, and clay (roughly 40:40:20), giving it intermediate texture properties favorable for many engineering and agricultural uses.
ASBOG ASBOG - Association of State Boards of Geology Geochemistry and Soil Science Questions and Answers 1
Which element is the most abundant by weight in the Earth's crust?