Topic: Biogeochemical CyclesEssential Question: How do carbon,

water, nitrogen, and phosphorus cycle through the biosphere?

BIO = Life GEO = EarthChemical CYCLES

ATMOSPHERE

LITHOSPHEREHYDROSPHERE

BIOSPHERE

The biogeochemical cycles show the flow of nutrients through

the biosphere.

Cycles we are going to learn about:1. Water 2. Carbon

3. Nitrogen4. Phosphorus

H

O

HC

O

O N

N

P

Why is water important?

• Water is necessary for all life on Earth.

• Makes up 60-70% of our body.

• Water is found in all the molecules in our cells (proteins, carbohydrates, etc.)

How does water move through the cycle?• Water cycles due to heat from the sun. Without the sun causing

evaporation, the cycle would not happen.• As water molecules in the atmosphere collide and get larger,

they grow too heavy and fall as precipitation.• Since most water is found in the ocean, 85% of evaporation

occurs between the ocean and atmosphere.

Human impact on the water cycleIf the total amount of water on earth does not change, why are there concerns about global freshwater shortages?• Over-pumping of aquifers• Groundwater contamination• Great pacific garbage patch

Lake Mead (AZ / NV border)water depletion

Deposition

Why is carbon important?

• All living things on our planet are full of carbon- it is a building block of life molecules

• Carbon dioxide is required for plants to do photosynthesis

How does carbon move through the cycle?

• Carbon is found in 4 main places:1. In the atmosphere as CO2

2. In the ocean as dissolved CO2 gas

3. On land in organisms, rocks, and soil

4. Underground as fossil fuels

• Plants take in CO2 during photosynthesis and both plants and animals release CO2 during respiration

• Carbon sinks are where large amounts of carbon are stored for long periods of time (old tree growth and the ocean)

Human impact on the carbon cycle• As humans burn fossil fuels we release carbon

dioxide into the atmosphere, which is contributing to climate change.

• Methane (CH4) is a greenhouse gas released from landfills and livestock.

• Too much carbon dioxide absorbed by the ocean is killing coral reefs.

Coral bleaching

Why is nitrogen important?

• Nitrogen is the most common gas in the atmosphere- 78%!

• Nitrogen is found in DNA molecules and proteins

• Humans can't use the nitrogen gas we breathe. As we eat food, we get nitrogen into our bodies

How does nitrogen move through the cycle?

• Nitrogen in the atmosphere (N2) is very stable and nonreactive. This form of nitrogen is unusable to plants and animals.

• Bacteria in the soil take nitrogen from the atmosphere and turn it into ammonia (NH3), a form which is usable by plants.

• Animals receive nitrogen by eating plant matter.

• Lightning can break bonds between N2, and it recombines with oxygen in the air to form nitrogen oxide.

Human impact on the nitrogen cycle

• Farming can cause depletion of soil nutrients so farmers add fertilizer. This can runoff into water supplies.

• Runoff can cause algae blooms, releasing toxins and killing fish.

• Pollution (car emissions, factories) releases nitric oxide into the atmosphere which causes respiratory issues.

Why is phosphorus important?

• Phosphorus is important to human bone health.

• Phosphorus is an important component of nucleic acid molecules.

• It is found in soil as a major plant nutrient.

How does phosphorus move through the cycle?

• The phosphorus cycle is the only nutrient cycle that only occurs on land (it does not enter the atmosphere).

• Phosphorus is found in rocks, and is released through weathering and leaching.

• Producers pick up phosphorus from the soil which are then eaten by consumers.

• As plants and animals die, decomposers return phosphorus to the soil. Weathering and erosion

Human impact on the phosphorus cycle:

• Farmers add phosphorus rich fertilizer to soils, which can runoff into water supplies and cause algae blooms.

• Animal waste (especially pig waste) is high in phosphorus, which can also contaminate water supplies.

https://www.youtube.com/watch?v=2D7hZpIYlCA

https://www.youtube.com/watch?v=leHy-Y_8nRs

Crash Course VideoWater and carbon cycles

Crash Course VideoNitrogen and Phosphorus cycles

Can you make a poster/diagram that shows how all the nutrients cycle through an ecosystem?