Topic 2 - Environmental Cycles Flashcards
The Water, Carbon-Oxygen and Nitrogen Cycles
The Water Cycle
The cycling of water through the lithosphere, biosphere, hydrosphere, and atmosphere. It’s driven by solar energy.
Transpiration
- Water is absorbed by plants from the soil though their roots.
- The water travels up the stem of the plant to the leaves.
- The water is releases into the atmosphere through stomata.
Condensation
- Cooling of water vapour (gas) in atmosphere.
- Water vapour condenses into water droplets (liquid) – forming clouds
Precipitation
- Water drops formed by condensation fall to earth.
- Can fall as rain, snow, or hail (depends on how cold it is).
Surface Run Off
- Refers to the movement of water over the land surface.
- Runoff ends in streams, rivers, lakes, and oceans.
- Can transport sediment, nutrients, and pollutants to other areas.
Infiltration
- Precipitation that falls onto land can soak into the soil, refilling groundwater sources.
Ground Water Flow
- Water that infiltrates into the soil becomes groundwater, which slowly moves through underground aquifers.
Aquifer
A layer of rock or soil that can hold and transmit groundwater, serving as an important source of fresh water for drinking, irrigation, and other uses.
Evaporation
- The sun heats bodies of water such as oceans, lakes and rivers.
- Causes water to change from liquid water to water vapour (gas) and rise into the atmosphere.
Freezing
- Freezing converts water from the liquid state to the solid state.
- Acts as water storage.
- Removed from the water cycle until it is melted again.
Melting
- Converts ice and snow back into liquid water.
- After melting, snow and ice refills rivers, lakes, and oceans.
Sublimation
- Transforms a solid straight into a gas (skips liquid phase).
- Ice ➡️ water vapour
Deposition
- Transforms a gas straight into a solid (skips liquid phase).
- Forms ice, snow, and glaciers.
Percolation
- The movement of water through soil and rock.
The Carbon-Oxygen Cycle
The cycle that transfers carbon through the atmosphere, lithosphere, biosphere, and hydrosphere.
Volcanic Eruptions
(in the carbon-oygen cycle)
Release large amounts of carbon dioxide into the atmosphere.
Carbon Sequestration
- On land, plants take in carbon dioxide to use in photosynthesis and store within their tissues (cells)
- In the ocean, phytoplankton and other marine organisms take in carbon through photosynthesis.
- Oceans also dissolve carbon dioxide.
- CO2 combines with the water and forms calcium formation of calcium carbonate shells.
Cellular Respiration
- Animals eat the plants and take in O2 to power cellular respiration, and then release CO2 into the atmosphere.
- Works with photosynthesis to act as carbon transfer between organisms.
Photosynthesis
- Plant cells absorb solar energy, carbon dioxide and water and convert them into oxygen, water and glucose (energy).
- Works with cellular respiration to act as carbon transfer between organisms.
Decomposition
- When organisms die, their organic matter becomes available for decomposition by decomposers.
- Decomposers break down complex organic molecules (like glucose) into simpler compounds (such as CO2)
Fossilisation and Unavailable Carbon
- Involves the burial and transformation of organic matter into fossil fuels such as coal, oil, and natural gas.
- Removes carbon from the cycle as it is transformed into fossil fuels.
- Once fossil fuels are formed, they remain underground until extracted.
Combustion of Fossil Fuels
- When burned, fossil fuels release large amounts of carbon dioxide into the atmosphere.
- Fossil fuels are burned for energy production, transportation, industrial processes, and heating.
- Not part of natural carbon cycle (human impact).
Limestone and Weathering
- Limestone is primarily composed of calcium carbonate (CaCO3)
- Calcium carbonate reacts with acids found in rainwater and soil.
- Produces CO2 which is released into the atmosphere.
Deforestation and Fires
- When trees and vegetation are cut down, burned, or left to decay, the carbon stored in their tissues and cells is released into the atmosphere as CO2.
- Also results in the loss of carbon sinks.
The Nitrogen Cycle
The nitrogen cycle transforms and circulates nitrogen in various forms through Earth’s spheres.
Atmospheric Nitrogen Fixation
- Lightning strikes generate enough energy to separate nitrogen gas (N2) into nitric oxide (NO) and nitrogen dioxide (NO2)
- These smaller molecules dissolve in water droplets in clouds - forming nitric acid.
- Nitric acid is transported to the Earth’s surface through precipitation.
Assimilation of Nitrites, Nitrates and Ammonia by Plants
Plants and some microorganisms take up ammonium (NH4+) and nitrate ions from the soil to use in cell processes.
Consumption
Animals acquire organic nitrogen by consuming plants or other animals.
Ammonification
- Decomposers (bacteria and fungi) break down nitrogen compounds found in dead organisms and other organic matter.
- Converts them to ammonia or ammonium ions.
- These simpler forms of nitrogen are released back into the soil.
Volcanic Eruptions
- Volcanic eruptions release nitrogen gas straight into the atmosphere.
- Heat and pressure created by eruptions leads to transformation of atmospheric nitrogen into nitrogen oxides.
- Reacts with water vapour to form precipitation.
Denitrification by Bacteria
- Denitrifying bacteria convert nitrate (NO3-) and nitrite (NO2-) ions into nitrogen gas.
- Nitrogen gas is returned to the atmosphere, where it can be accessed again by nitrogen-fixing bacteria.
Nitrogen Fixation by Bacteria
- Atmospheric N2 is converted into ammonia or ammonium ions by nitrogen-fixing bacteria found in the soil.
Nitrification
- Ammonia (from nitrogen fixation) is converted to nitrite ions by nitrifying bacteria.
- Nitrite ions are then oxidized into nitrate ions by other nitrifying bacteria (Nitrobacter).
