geo 101 sbu exam 3

What is carbon sequestration?

Capturing and storing atmospheric CO2.

According to "Kiss the Ground," how can soils significantly reduce atmospheric CO2?

By storing carbon long-term. Healthy soils = more effective long-term carbon storage.

What is the chemical equation for photosynthesis?

CO2 + H2O + light → organic carbon (CH2O) + O2

How long can soil ecosystems store carbon

hundreds to thousands of years

What is soil?

A mixture of organic matter, minerals, gases, water, and organisms supporting plant and soil life

What are the three main components of soil?

. Soil matrix (solid minerals + organic matter), 2. Soil atmosphere (gases in pores), 3. Soil solution (water + dissolved substances).

What five factors interact to form soil?

Climate, relief (topography), organisms, parent material, and time.

What is residual soil?

Soil that forms from the weathering of underlying bedrock

What is transported soil?

Soil that is deposited by wind, water, or glaciers

Describe the sequence of mature soil profile development

 Bedrock exposed, 2. Weathering produces C-horizon, 3. Plants establish → A-horizon forms (O-horizon above in vegetated areas), 4. Water percolation → B-horizon develops, 5. Continued leaching removes Fe/Al → E-horizon forms.

Name the five major influences on soil development.

Biology, Climate, Parent Material, Topographic Relief, Time.

What are root exudates?

Sugars and amino acids leaked by plant roots that feed soil microbes.

What do Rhizobium bacteria do?

 Convert atmospheric N2 into NH4+ (ammonium) for plants; plants supply them with sugars.

Describe Ultisols

 Red clay soils; represent "ultimate" weathering in humid temperate climates.

Describe Aridisols.

 Form in arid climates; low organic matter; have mineral accumulations (salts, carbonates, gypsum); defined by water deficiency.

Describe Mollisols.

Deep, nutrient-rich A-horizon; high organic matter; the most agriculturally productive soil order.

Describe Gelisols.

Contain permafrost within 2 meters of the surface; dark organic-rich upper layers; found in very cold climates.

What are three natural resources obtained from soils?

Kaolinite (ceramics, paper), Bauxite (aluminum production), Sand & clay (construction materials).

What is an example of intentional and irreversible soil loss?

Mining (e.g., kaolinite extraction).

What are three unintentional, reversible causes of soil loss from poor agriculture?

Overreliance on chemical inputs, 2. Poor crop rotation, 3. Tillage.

According to the IPCC, how will climate change impact soils globally?

Soils likely to become drier globally due to hotter surfaces and deeper heat penetration causing more evaporation from soil pores. Thick, healthy, vegetated soils help mitigate this.

What are five soil loss mitigation strategies?

1. No-till agriculture, 2. Contour plowing, 3. Terracing, 4. Stream buffers / wetland preservation, 5. Biological soil management.

According to "Kiss the Ground," what can improved soil management do?

Increase soil carbon sequestration, improve soil health & crop support, reduce reliance on pesticides, artificial nutrients, and GM crops.

According to the IEA 2025 Outlook, how much did lithium demand grow in 2024?

~30% (vs. 10% annual growth in the 2010s).

What is the projected growth for lithium demand to 2040?

 Increase 5×

What is the projected growth for graphite and nickel demand to 2040?

Double

What are the main drivers of critical mineral demand?

Electric vehicles (EVs), battery storage, renewable energy systems, power grid electrification, permanent magnets for EVs & wind turbines.

Define mineral resources.

A deposit that is feasible to mine (not necessarily economically feasible).

Define mineral reserve / ore deposit.

A deposit that is economically feasible to mine

What two factors determine the economic feasibility of mining a deposit?

 Enrichment factor (concentration above crustal average) and cost of extraction (technology, depth, grade).

Describe the igneous process of crystal settling.

Dense minerals crystallize early and sink to the bottom of a magma chamber, producing layered intrusive deposits (e.g., Bushveld Complex).

What are pegmatites?

Deposits formed when magma enriched in elements like Li, Be, and rare metals is injected into local bedrock. They are a source of lithium-rich minerals like tourmaline.

 What are some environmental problems associated with mining magmatic nickel sulfide deposits (Minnesota/Wisconsin)?

(Based on Meateater podcast referenced) Acid mine drainage from sulfide minerals exposed to air and water, heavy metal contamination of water resources, and conflict over land use between mining and sensitive aquatic ecosystems (e.g., Boundary Waters)

Why has the Minnesota mining operation (for nickel sulfides) been so controversial?

Due to the risk of sulfuric acid and heavy metals leaching into the pristine Boundary Waters Canoe Area Wilderness, threatening water quality, fisheries, and the regional tourism/recreation economy.

What do hydrothermal processes do in terms of mineral concentration?

Hot, circulating water leaches elements from rocks and deposits them in veins as ore minerals (e.g., copper, lead, zinc, gold, silver).

What are secondary enrichment (supergene) processes?

 Weathering and groundwater leaching concentrate minerals near the surface, often creating high-grade ore deposits from lower-grade primary deposits.

What are placer deposits and give an example?

Mechanical concentration of heavy, durable minerals by flowing water (rivers or waves). Example: Gold in stream sediments.

What is the primary mineral in bauxite ore?

Aluminum hydroxides (gibbsite, boehmite, diaspore).

How does bauxite form?

 Intense chemical weathering of aluminum-rich rocks (like granite or basalt) under tropical to subtropical conditions, removing silica and leaving aluminum behind.

 What are the environmental impacts of bauxite mining and refining?

Deforestation and habitat loss from mining; red mud (highly alkaline, caustic tailings containing heavy metals) from the Bayer refining process, which requires toxic containment.

What is the main environmental concern with lithium brine extraction?

Extremely high water consumption (evaporation of brines in arid regions), which lowers the water table, impacts local ecosystems, and creates conflicts with local farmers and indigenous communities.

What defines a rare earth element (REE)?

The 15 lanthanide elements plus scandium and yttrium. They are not necessarily rare, but are often dispersed and difficult to concentrate into economically mineable deposits.

How are REEs concentrated into mineable deposits?

Magmatic and hydrothermal processes in alkaline igneous rocks and carbonatites (rare, carbonate-rich igneous intrusions), plus weathering that forms ion-adsorption clays (especially in southern China).

Name two major global sources of heavy rare earth elements outside China.

 1. Mount Weld deposit (Australia - weathering of carbonatite), 2. Ion-adsorption clays (historically dominated by China, but exploration underway elsewhere).

What makes REE mining environmentally challenging?

Radioactive byproducts (thorium and uranium often associated with REE ores), acid mine drainage, and heavy metals requiring complex waste management.

What are two primary reasons motivating the transition to alternative energy?

1. Fossil fuel combustion has rapidly increased atmospheric GHGs, altering climate. 2. "Easy to exploit" fossil fuels are dwindling → reliance on harder-to-access resources.

What are the three main non-renewable alternative fossil fuels?

Synthetic gas (syngas), heavy oil, and tar/oil sands.

What is syngas and how is it produced?

Syngas (H2 + CO) is produced by reacting coal with O2 and H2O.

What is the Great Plains Synfuels Plant (ND) doing since 2024?

Using carbon capture & storage (CCS) to manage the significant CO2 produced from syngas generation.

Is syngas considered a "green" energy source?

No, it is still a synthetic fossil fuel.

How is heavy oil extracted?

Requires steam injection to reduce its viscosity so it can be pumped.

What is bitumen?

An extremely viscous hydrocarbon formed by bacterial breakdown of petroleum; found in tar/oil sands.