APES 2.1-2.5 Notes

Biogeochemical cycle

A process that moves elements and nutrients between living organisms and nonliving parts of Earth.

Nitrogen fixation → nitrification → assimilation

The main sequence of nitrogen use: bacteria convert N2 into usable nitrogen, other bacteria form nitrates, and plants absorb the nitrogen into their tissues.

Ammonification

The conversion of nitrogen in dead organisms and waste into ammonia/ammonium.

Cultural eutrophication

Human-caused excess nutrients in water, often from fertilizer, that cause algal blooms and can reduce dissolved oxygen.

Carbon cycle

Carbon moves through the atmosphere, organisms, soil, oceans, and fossil fuels; photosynthesis removes CO2 while respiration, decomposition, and combustion return it.

Ocean acidification

Extra CO2 dissolves in seawater, forms carbonic acid, increases H+, and lowers pH, making it harder for organisms to build calcium carbonate structures.

Water cycle vs. other biogeochemical cycles

The hydrologic cycle is unique because water changes physical state and location while remaining H2O.

Infiltration, percolation, and leaching

Infiltration is water entering soil; percolation is water moving downward through soil; leaching is dissolved substances being carried downward by water.

Phosphorus cycle

Phosphorus moves mainly through rocks, soil, water, and organisms and has no major atmospheric stage.

Sulfur and acid rain

Sulfur in fossil fuels can be released as SO2 when burned; SO2 can react with water and contribute to acid rain.

Radiometric vs. relative dating

Radiometric dating gives an approximate numerical age using radioactive decay; relative dating determines whether something is older or younger than something else.

Stratigraphy

The study of rock layers; generally, lower undisturbed layers are older than layers above them.

Lithosphere vs. asthenosphere

The lithosphere is the rigid crust and upper mantle divided into plates; the asthenosphere is the softer layer beneath it that allows plates to move.

Mantle convection

Hot material rises and cooler material sinks in the mantle, helping drive movement of tectonic plates.

Oceanic vs. continental crust

Oceanic crust is thinner and denser, while continental crust is thicker and less dense.

Convergent, divergent, and transform boundaries

Convergent plates move together; divergent plates move apart and create new crust; transform plates slide past each other.

Convergent boundary effects

Convergence can cause subduction, trenches, volcanoes, or mountain ranges depending on which types of plates collide.

Divergent boundary effects

Divergence causes magma to rise and create new crust, producing features such as mid-ocean ridges and rift zones.

Transform boundary effects

Transform plates slide sideways past each other, commonly causing earthquakes.

Rock cycle

Weathering and erosion create sediment; deposition and compaction form sedimentary rock; heat and pressure form metamorphic rock; melting and cooling form igneous rock.

Hotspot

A place where unusually hot magma rises through the crust and can form volcanoes or volcanic island chains as a plate moves over it.

Earthquake focus vs. epicenter

The focus is the underground point where an earthquake begins; the epicenter is the point on the surface directly above it.

P waves vs. S waves

P waves arrive first and travel through solids and liquids; S waves arrive later and travel through solids but not liquids.

Richter scale

A logarithmic earthquake scale based on wave amplitude; each whole-number increase represents 10 times greater wave amplitude.

Tsunami

A series of large ocean waves usually caused by sudden displacement of seawater, such as from an underwater earthquake.

Atmospheric composition

Earth's atmosphere is about 78% nitrogen, 21% oxygen, and 1% other gases.

Atmospheric layers

Troposphere: weather; stratosphere: ozone; mesosphere: meteors; thermosphere: auroras/ions; exosphere: outermost layer.

Atmospheric temperature pattern

Temperature generally decreases in the troposphere, increases in the stratosphere, decreases in the mesosphere, and increases in the thermosphere.

Albedo

A measure of how much radiation a surface reflects; ice, snow, and clouds have high albedo, while darker surfaces generally have lower albedo.

Natural vs. enhanced greenhouse effect

The natural greenhouse effect keeps Earth warm enough for life; human activities increase greenhouse gases and strengthen heat trapping.

Ozone layer and CFCs

The ozone layer absorbs harmful UV radiation; CFCs can release chlorine that destroys ozone, which led to the Montreal Protocol.

Hadley, Ferrel, and Polar cells

Hadley cells occur around 0–30°, Ferrel cells around 30–60°, and Polar cells around 60–90° latitude.

Coriolis effect

Earth's rotation causes moving air to curve right in the Northern Hemisphere and left in the Southern Hemisphere.

Climate vs. weather

Climate is the long-term pattern of atmospheric conditions, while weather is the short-term condition of the atmosphere.

ENSO

El Niño-Southern Oscillation is a Pacific Ocean-atmosphere pattern involving changes in surface temperature, trade winds, upwelling, and the thermocline.

El Niño vs. La Niña

El Niño has weaker trade winds, warmer surface water, a flatter thermocline, and less upwelling; La Niña has stronger trade winds, cooler surface water, a steeper thermocline, and more upwelling.

Saltwater, brackish water, and freshwater

Saltwater has high salinity; brackish water is a mixture of fresh and salt water; freshwater has very low salinity.

Estuary

An area where freshwater and saltwater mix, usually where a river meets the ocean; estuaries are highly productive and biodiverse.

Aquifer and recharge

An aquifer stores and transmits groundwater; recharge occurs when water enters an aquifer, mainly through precipitation and infiltration.

Watershed

A land area in which water drains toward a common body of water; activities within the watershed can affect its water quality.

River features

Headwaters begin a river; tributaries flow into larger rivers; a confluence is where rivers meet; floodplains surround rivers and can flood; the mouth is where a river enters another body of water.

Delta vs. estuary

A delta forms when a river deposits sediment; an estuary forms where freshwater and saltwater mix.

Soil-forming factors

The five factors are parent material, climate, topography, organisms, and time; together they determine how soil develops.

Mechanical, chemical, and biological weathering

Mechanical weathering physically breaks rock apart; chemical weathering changes its chemical composition; biological weathering is caused by living organisms.

Primary vs. secondary succession

Primary succession begins without soil, such as on bare rock; secondary succession begins after a disturbance when soil remains, so it usually occurs faster.

Soil texture and CEC

Soil texture depends on sand, silt, and clay; CEC measures how well soil holds positively charged nutrients, with higher CEC generally meaning greater nutrient-holding ability.

Soil horizons

O is organic material; A is topsoil; E is the eluviation layer; B is subsoil; C is partly weathered parent material; R is bedrock.

Soil degradation

Waterlogging fills soil pores with water; erosion removes soil; desertification decreases land productivity; salinization causes salts to accumulate, often from irrigation.

Human activities that degrade soil

Agriculture can cause nutrient loss and compaction; overgrazing removes vegetation and compacts soil; deforestation increases erosion; urbanization and industry can also disturb and compact soil.