UNIT 3 - Cycles of Matter

4 Spheres of Earth

Atmosphere, Hydrosphere, Geosphere, and Biosphere.

Atmosphere

Layer of gases surrounding Earth, contains oxygen, nitrogen, and carbon dioxide.

Examples of Atmosphere

Air, clouds, weather, and water vapor.

Hydrosphere

All water on Earth, in liquid, solid, or gas form.

Examples of Hydrosphere

Oceans, lakes, rivers, glaciers, water vapor.

Geosphere

All solid land on Earth, including the crust and the interior layers.

Examples of Geosphere

Rocks, soil, mountains, Earth's core.

Biosphere

The zone of life on Earth, where living organisms exist.

Examples of Biosphere

Animals, plants, microbes, ecosystems.

Can Matter Cycle Between Spheres?

Yes, matter can cycle between different spheres (e.g., water moves between hydrosphere, atmosphere, and geosphere).

Water in Earth's Spheres

Water exists in the atmosphere (vapor), hydrosphere (oceans, lakes), and geosphere (glaciers, groundwater).

Ocean

97.96% saltwater in oceans, seas, and salt lakes.

Glacier (Ice River)

2.16% of water is frozen in glaciers, icebergs, and polar ice caps.

Accumulation

Water gathers in large bodies like oceans, lakes, and seas.

Condensation

Water vapor cools and condenses into liquid water, forming clouds.

Evaporation

Water turns from liquid to vapor when heated by the sun.

Precipitation

Water falls as rain, snow, sleet, or hail from clouds to the ground.

Infiltration

Water soaks into the ground to become groundwater.

Surface Runoff

Water flows down in streams and rivers, usually from rain or melted snow.

Transpiration

Water absorbed by plants is released as vapor through leaves.

Evaporation

Liquid → Gas (water vapor)

Condensation

Gas → Liquid (cloud formation)

Freezing

Liquid → Solid (ice formation)

Melting

Solid → Liquid (melting ice)

Carbon Cycle

Movement of carbon through Earth's systems, including the atmosphere, oceans, and living organisms.

Photosynthesis

Producers (plants and algae) absorb carbon dioxide (CO2) from the air and water to create food and release oxygen.

Cellular Respiration

Plants and animals take in food with carbon and oxygen, release CO2 as a waste product.

Consuming

Organisms eat others, obtaining their carbon and energy.

Death and Decomposition

Dead organisms break down, returning nutrients like carbon to the soil.

Deposition

Decomposing organisms become fossil fuels or are absorbed by the ocean.

Combustion

Fossil fuels or plants (including trash) are burned, releasing stored carbon as CO2.

Pre-Industrial Revolution

Before the Industrial Revolution, carbon was mainly stored in marine plants/animals, soil/detritus, and the deep ocean.

Present Day

After the Industrial Revolution, carbon is more abundant in the atmosphere, surface ocean, and ocean sediment.

Atmosphere

Pre-Industrial Rev: 0, Present Day: 3

Marine Plants/Animals

Pre-Industrial Rev: 0, Present Day: 1

Carbon Sinks

Carbon sinks are places where carbon is stored for long periods of time.

Why More Carbon in Atmosphere Now?

After the Industrial Revolution, fossil fuels were extracted and burned, releasing CO2 into the atmosphere.

Why Carbon in Ocean Sediment?

Marine organisms die and sink into the ocean, where their carbon is absorbed by the ocean sediment.

Nitrogen Cycle

The process by which nitrogen moves between the atmosphere, living organisms, and the soil, involving several stages of nitrogen transformation.

Nitrogen Fixation

The process of converting atmospheric nitrogen (N2) into a form usable by living organisms (e.g., ammonium (NH4+), nitrates).

Fixed Nitrogen

Forms of nitrogen that are combined with other elements and usable by organisms, such as ammonium (NH4+), nitrites (NO2-), and nitrates (NO3-).

Mutualism (Nitrogen-Fixing Bacteria and Legumes)

The nitrogen-fixing bacteria in the soil benefit from the plant's nutrients, while the plant receives nitrogen from the bacteria to support growth.

Nitrogen-Fixing Bacteria

Bacteria that convert nitrogen in the atmosphere into forms usable by plants, such as cyanobacteria in soil and lightning in the atmosphere.

Nitrifying Bacteria

Bacteria that convert ammonium (NH4+) into nitrites (NO2-) and then into nitrates (NO3-), which plants can use to build amino acids, proteins, and DNA.

Decomposers

Fungi, aerobic bacteria, and anaerobic bacteria break down dead plants, animals, and animal waste into simpler compounds like ammonia (NH3).

Denitrifying Bacteria

Bacteria that convert nitrates in the soil back into nitrogen gas (N2), releasing it into the atmosphere and completing the nitrogen cycle.

Human Interference

In agricultural practices, humans remove nitrogen from the soil when crops are harvested and replenish it using nitrogen-rich fertilizers.

Nitrogen in Fertilizers

Fertilizers are used to replace nitrogen in the soil, which is depleted after crops are harvested.

Carbon Sinks

Carbon sinks are locations where carbon is stored for long periods of time.

Water Cycle

The process by which water circulates between the Earth’s oceans, atmosphere, and land through processes like evaporation, condensation, and precipitation.

Transpiration

The process where liquid water is absorbed by plants and then released as water vapor through leaves.

Clouds

Liquid droplets of water suspended in the atmosphere.

Condensation

The process in which water vapor cools, condenses, and forms liquid droplets, leading to the formation of clouds.

Infiltration

The process by which water sinks into the ground to replenish groundwater.

Runoff

The process where water flows over the surface of the Earth, eventually accumulating in lakes, rivers, or oceans.

Carbon Sink

A location where carbon is stored for long periods, such as forests and fossil fuels.

Fossil Fuels

Carbon-rich substances like coal, oil, and natural gas formed from the remains of ancient organisms.

Forests

Large areas of trees and plants that absorb and store carbon dioxide from the atmosphere.

Decomposing Leaves

Releases carbon into the atmosphere as CO2 when leaves decay.

Burning Fossil Fuels

Releases carbon into the atmosphere as CO2 when fossil fuels are burned.

Photosynthesis

Plants use sunlight to convert carbon dioxide (CO2) and water into glucose, storing carbon in plant tissues.

Cellular Respiration

Exercising and other metabolic processes release carbon dioxide (CO2) as a waste product, using stored carbon from food.

Eutrophication

A process where excessive nutrients like nitrogen cause overgrowth of algae, depleting oxygen in water and creating dead zones.

Free Nitrogen

Unreacted nitrogen in the atmosphere, comprising about 78% of Earth’s atmosphere.

Legumes

Plants that have a mutualistic relationship with nitrogen-fixing bacteria in their roots, aiding in nitrogen fixation.

Harvesting Crops

Removes nitrogen from the soil as crops absorb nitrogen to grow.

Adding Fertilizer to Farmland

Adds nitrogen to the soil because fertilizers often contain nitrogen compounds.