Study Notes on the Hydrologic Cycle

Hydrologic Cycle

The topic is focused on the Hydrologic Cycle, also known as the Water Cycle, as part of AP Environmental Science.

ERT-1: Ecosystems are the result of biotic (living organisms) and abiotic (non-living elements) interactions.

ERT-1.0: Students should be able to explain the steps and reservoir interactions in the hydrologic cycle.

ERT-1.0.1: The hydrologic cycle is powered by the sun and involves the movement of water in its various solid, liquid, and gaseous phases between sources (where water originates) and sinks (where water is stored).
ERT-1.0.2: Oceans serve as the primary reservoir of water at the Earth's surface, while ice caps and groundwater function as much smaller reservoirs.

Biogeochemical Cycle: A cycle that involves chemical substances moving through both biotic (living) and abiotic (non-living) parts of the ecosystem.
Hydrologic Cycle: Also known as the water cycle, describes the continuous movement of water on, above, and below the surface of the Earth.
Source: A process that releases substances into the atmosphere.
Sink: A process that removes substances from the atmosphere.
Reservoir: A location where water or other substances accumulate.
Store: Often used interchangeably with reservoir, referring to places where water is held.
Flow: Refers to the movement of water from one store to another.
Runoff: Water that flows over the surface of the ground after precipitation.
Other terms include evaporation, transpiration, evapotranspiration, condensation, sublimation, desublimation, precipitation, infiltration, groundwater, groundwater flow, and aquifer.

Bio = life
Geo = Earth
Chemical = chemicals involved in these processes
Cycle = a repeated process where materials circulate and return to their starting points, leading to changes in the ecosystem.

Chemicals cycle through biotic components (biosphere) and abiotic components (lithosphere, atmosphere, hydrosphere, and cryosphere).
Biogeochemical cycles have a global impact; activities in one area can affect ecosystems elsewhere on the planet.

The most abundant and essential elements found in living organisms are:
- C: Carbon
- H: Hydrogen
- O: Oxygen
- N: Nitrogen
- P: Phosphorus
- S: Sulfur
Additional essential elements include calcium, sodium, iron, etc., each with unique cycling processes.

Understanding these cycles is critical for:
- Environmental health and stability
- Climate change
- Weather modeling
- Human health
The health of the natural world is crucial; human survival depends on it.
Notable Quote: "It is not possible to add pesticides to water anywhere without threatening the purity of water everywhere." - Rachel Carson, Silent Spring.

Source: Processes that release substances to the atmosphere (e.g., H2O, CO2, N2).
Sink: Processes that remove substances from the atmosphere.
Reservoir: A storage area (e.g., water in oceans, carbon in calcium carbonate rock).

Hydrologic cycle: Also known as the water cycle.
Store: Areas where water accumulates (reservoir).
Flow: Movement of water from one store to another.
Evaporation: The vaporization of water, not necessarily at boiling point.
Transpiration: Loss of water from plant leaves to the atmosphere; plants continuously lose water.
Evapotranspiration: The sum of evaporation and transpiration from the Earth's surface.
Condensation: Conversion of water vapor back to liquid water.
Sublimation: Transition from solid (ice) directly to vapor without passing through the liquid phase.
Desublimation: Conversion of vapor back to solid form.
Precipitation: The process through which water falls from the atmosphere (includes snow, rain, sleet, and hail).
Infiltration: Water movement from the surface into groundwater reservoirs.
Groundwater: Water located beneath the Earth's surface, often in aquifers.

Creating dams: Alters river flow; affects aquatic life and ecosystems.
Groundwater mining: Over-extraction of water contributes to sea-level rise and unstable ground, which may lead to earthquakes.
Irrigation: Disrupts natural river flow, affects habitats, and can lead to desertification.
Urbanization: Increases runoff while decreasing infiltration, affecting local water cycles.
Deforestation: Increases runoff, causes erosion, and can contribute to desertification.
Melting Ice: Influences sea levels and interacts with climate change.
Pollution: Affects water quality, with negative repercussions for both ecosystems and human health (includes phenomena like acid rain).

Video recommended: "How the Water Cycle Works" by the National Science Foundation (link included).

Reiterates the importance of understanding ecosystems through biotic and abiotic interactions and emphasizes that understanding the hydrologic cycle is crucial for environmental science studies.
Essential Knowledge points restated for emphasis:
- The hydrologic cycle's power derives from the sun.
- Oceans are the largest reservoirs, with smaller ones being ice caps and groundwater.