Geochemical Cycles

These flashcards cover key concepts related to geochemical cycles, including the oxygen, nitrogen, and phosphorus cycles, as well as the impacts of human activity.

Oxygen Cycle

Essential for aerobic organisms, makes up 21% of the air, involves inhalation of oxygen and exhalation of CO₂.

Nitrogen Cycle

Nitrogen makes up 78% of the atmosphere; organisms cannot use nitrogen gas directly; it must be fixed.

Nitrogen Fixation

The process that converts nitrogen gas (N₂) into ammonia (NH₃) and nitrates (NO₂) through lightning and bacteria.

Nitrification

The conversion of ammonia into nitrates by bacteria.

Ammonification

The process where organisms are decomposed by bacteria, returning nitrogen to the ecosystem.

Denitrification

The conversion of nitrates back into nitrogen gas (N₂) by bacteria, returning it to the atmosphere.

Phosphorus Cycle

Involves phosphorus found in rocks; not atmospheric; absorbed by plants and returned to sediment after decomposition.

Impact of Human Activity on Carbon Cycle

Burning fossil fuels and deforestation increase atmospheric CO₂ and lead to ocean acidification.

Synthetic Fertilizers

Human impact that overloads ecosystems with excess nitrogen and phosphorus.