Biogeochemical Cycles Practice Flashcards

This set of vocabulary flashcards covers the key processes, stores, and human impacts associated with biogeochemical cycles, specifically focusing on the carbon and nitrogen cycles as described in the lecture notes.

Biogeochemical Cycle

A process that ensures chemical elements continue to be available to living organisms by cycling them through the environment.

Stores

Components of a biogeochemical cycle where elements are kept or held for varying lengths of time.

Sinks

Parts of a biogeochemical cycle where there is a net accumulation of elements, such as when ecosystems absorb more carbon than they release.

Sources

Parts of a biogeochemical cycle where there is a net release of elements into the environment.

Carbon Sequestration

The process of capturing gaseous and atmospheric carbon dioxide ($CO_2$) and storing it in a solid or liquid form.

Fossil Fuels

Stores of carbon with unlimited residence times, formed when past ecosystems acted as carbon sinks; they become carbon sources when burned.

Ocean Acidification

A change in ocean chemistry caused by increases in concentrations of dissolved $CO_2$, which harms marine animals by decreasing pH levels.

Organic Carbon Stores

Reservoirs of carbon found in living organisms, dead organic matter, soil, crude oil, and natural gas.

Inorganic Carbon Stores

Reservoirs of carbon found in the atmosphere, soils, oceans (as dissolved gas), and sediments/sedimentary rocks like limestone.

Photosynthesis

The process by which plants absorb $CO_2$ and store it as biomass, acting as a flow from the atmosphere to organic stores.

Cellular Respiration

A process in which organisms release $CO_2$ back into the atmosphere or water from organic carbon stores.

Residence Time

The duration for which an element, such as carbon, remains within a specific store or reservoir.

Biomass

The total mass of living organisms in a given area or volume, which serves as a form of organic carbon storage.

Deforestation

The clearing of forests which reduces carbon storage and increases atmospheric carbon levels, turning a carbon sink into a source.

Sedimentation

The process by which carbon-containing materials settle and accumulate in layers, eventually forming sedimentary rock.

Fossilization

The slow geological process of turning organic matter into fossil fuels or rock-based carbon stores like limestone.

Nitrogen Cycle (HL)

The biogeochemical cycle by which nitrogen is converted into various chemical forms as it circulates between the atmosphere, terrestrial, and marine ecosystems.

Methanogenesis (HL)

The production of methane ($CH_4$) by microorganisms under anaerobic conditions.

Nitrates (HL)

A form of nitrogen ($NO_3^-$) that is easily absorbed by plants and is a key component of the nitrogen cycle.

Nitrites (HL)

An intermediate form of nitrogen ($NO_2^-$) produced during the process of nitrification.

Denitrification (HL)

The chemical reduction of nitrates back into nitrogen gas ($N_2$), typically performed by bacteria in anaerobic conditions.

Eutrophication (HL)

The process where excess nutrients, such as nitrogen or phosphorus, enter water bodies, leading to overgrowth of algae and depletion of oxygen.

Nitrogen Fixation (HL)

The conversion of atmospheric nitrogen ($N_2$) into nitrogen-containing compounds like ammonia, often by specialized bacteria or legumes.

Ammonification (HL)

The process by which decomposers convert organic nitrogen from dead organisms and waste back into ammonium ($NH_4^+$).

Leaching (HL)

The loss of water-soluble plant nutrients, such as nitrates, from the soil due to rain or irrigation.

Lithosphere (HL)

The rigid outer part of the earth, consisting of the crust and upper mantle, which acts as a major store for inorganic carbon and minerals.

Planetary Boundaries (HL)

Limits within which humanity can safely operate relative to Earth's systems, including the management of biogeochemical flows like nitrogen.