Ecosystem Cycles Review: Carbon, Water, and Nitrogen

Comprehensive flashcards covering the biological and geological processes of the Carbon, Water, and Nitrogen cycles as described in the lecture notes.

Carbon cycle

The movement of carbon between the atmosphere, land, oceans, and living organisms.

Photosynthesis

The process by which plants, algae, and some bacteria use sunlight, water, and $CO_2$ to produce glucose and oxygen.

Cellular respiration

The process by which organisms release energy from organic compounds, releasing carbon back into the atmosphere as $CO_2$.

Decomposition

The process where decomposers like bacteria and fungi break down dead organisms and waste, returning carbon to the soil as nutrients.

Carbon sink

Any reservoir, such as the ocean, that absorbs more carbon dioxide from the atmosphere than it releases.

Oceanic uptake

The process by which dissolved carbon dioxide enters the oceans.

Sedimentation

The deposition of organic and inorganic particles on the ocean floor, where carbon is buried and stored over time.

Lithification

The geological process over millions of years where carbon is stored in sedimentary rocks like limestone.

Combustion

The burning of fossil fuels or organic matter which releases stored carbon into the atmosphere as $CO_2$.

Water cycle (hydrologic cycle)

The continuous and interconnected movement of water molecules throughout the Earth.

Evaporation

The process where heat from the sun turns liquid water into water vapor that rises into the atmosphere.

Condensation

The cooling of water vapor which transforms it back into liquid droplets to form clouds.

Precipitation

Forms of water such as rain, snow, sleet, or hail that fall from clouds due to gravity.

Infiltration

The process where water enters the soil and is absorbed by plant roots or seeps into the Earth's surface.

Percolation

The movement of water through sediments and permeable rock layers toward groundwater reservoirs.

Groundwater

Water that lies beneath the Earth's surface, filling spaces in soil, rocks, and sediment.

Aquifers

Underground reservoirs formed by groundwater flowing through porous materials.

Runoff

Water that flows over the land surface into streams, rivers, and the ocean, often carrying nutrients and minerals.

Transpiration

The process by which plants release water vapor into the atmosphere through their leaves.

Closed system

The nature of the water cycle, meaning the volume of water on Earth remains constant over time.

Nitrogen cycle

The process of movement and transformations of nitrogen in various forms throughout the environment.

Ammonification

The step in the nitrogen cycle where decomposers convert organic nitrogen compounds into ammonium ($NH_4^+$).

Nitrification

The process where specialized bacteria convert ammonium ($NH_4^+$) into nitrite ($NO_2^-$) and then into nitrate ($NO_3^-$).

Assimilation

The process where plants take in nitrogen compounds from the soil through their roots to use for growth and development.

Nitrogen fixation

The conversion of atmospheric nitrogen gas ($N_2$) into a usable form by bacteria in the soil or root nodules of legumes.

Lightning fixation

A process where intense heat breaks nitrogen molecules apart to react with oxygen, forming nitrogen oxides that enter the soil as nitric acid via rain.

Denitrification

The process where specialized bacteria convert nitrate ($NO_3^-$) back into atmospheric nitrogen gas ($N_2$).