topic 2.3

What are biogeochemical cycles?

Natural processes that circulate chemical elements essential for life.

Why are biogeochemical cycles important?

They ensure essential elements remain available to living organisms within an ecosystem.

Name three major biogeochemical cycles.

1. Carbon cycle 2. Nitrogen cycle 3. Hydrological cycle

How can human activities disrupt biogeochemical cycles?

Human activities such as burning fossil fuels, deforestation, urbanisation and agriculture can disrupt biogeochemical cycles. This can lead to environmental imbalances and threaten the sustainability of ecosystems.

What are the three main components of biogeochemical cycles?

Stores, sinks, and sources.

What is a 'store' (or storage) in a biogeochemical cycle?

A reservoir(where elements are held for a long period of time) where an element is held in equilibrium, meaning Inputs = Outputs. Can be natural or artificial

What is a 'sink' in a biogeochemical cycle?

A component where an element accumulates over time because Inputs > Outputs.; results in net accumlation of the element

What is a 'source' in a biogeochemical cycle?

A component that releases an element into the cycle because Outputs > Inputs.results in a led release of the element.

What is residence time?

The average time a carbon atom remains in a specific store (e.g., hundreds of millions of years in fossil fuels).

What are organic carbon stores?

Carbon held in living organisms and fossil fuels, typically as carbohydrates or hydrocarbons.

What are inorganic carbon stores?

Carbon held in the atmosphere, oceans, and soils, typically as CO_{2} or carbonates.

Which process removes CO_{2} from the atmosphere?

Photosynthesis.

Which process releases CO_{2} back into the atmosphere from organisms?

Cellular respiration.

What is fossilisation?

The conversion of organic matter into fossil fuels over millions of years under conditions of low oxygen and high pressure.

What is carbon sequestration?

The process of capturing and storing atmospheric CO_{2} in sinks like trees, soil, or underground.

When does an ecosystem act as a carbon sink?

When carbon uptake (photosynthesis) exceeds carbon release (respiration).

How does ocean acidification occur?

Increased dissolved CO{2} reacts with seawater to lower the pH, reducing calcium carbonate (CaCO{3}) available for shells.

What is BECCS?

Bioenergy with Carbon Capture and Storage; a technology used to reduce atmospheric carbon.

How does regenerative agriculture act as a carbon sink?

By using practices that increase soil organic matter, thereby storing more carbon in the ground.

Why is the total amount of carbon in the biosphere approximately constant?

Because carbon is a finite resource that is continuously recycled through transfers and transformations.