NUTRIENT CYCLES

What are nutrients?

•Nutrients are chemicals that are essential to the survival of living things

•Nutrients are CYCLED through ecosystems and the Earth’s spheres.

•We can’t create new nutrients or destroy them – they just move around.

All living things needs nutrients•Where do you get your nutrients

from?

•Food!

•All food comes from plants. If you eat meat, the animals you eat get their food from plants (or other animals who ate plants).

•So how do plants get their nutrients?

Nutrient Cycles

• Nutrients are made up of elements, which are pure substances that can’t be broken down further. You’d find them in the periodic table

•Water (hydrogen and oxygen) Cycle

• Carbon Cycle

• Nitrogen Cycle

• Phosphorous Cycle (we won’t cover this cycle)

These 4 nutrients are essential to ecosystems. Without them, plants cannot survive. Without plants, ecosystems cannot exist.

Nutrients move through spheres. Do you remember

the Earth’s 4 spheres? Identify

them

Earth’s 4 spheres1.Atmosphere – The air surrounding

the Earth’s surface

2.Lithosphere – The soil, rock, and magma beneath the Earth’s surface

3.Hydrosphere – All water on Earth

4.Biosphere – All living things on Earth (all which live on or near Earth’s surface).

Are humans creating more

carbon?• True or false? Humans are creating more carbon.

• False. You may have heard that humans are responsible for adding more carbon dioxide to the atmosphere. This is true! But they didn’t “create” it.

•Humans burn carbon-rich fossil fuels from the lithosphere. When they are burned, the carbon is release into the atmosphere.

• Therefore, humans aren’t creating more carbon. They are just moving it from one sphere to another. This is the primary cause of global warming.

Why a cycle?•The Earth, nor humans, cannot create more

water, carbon, nitrogen, and phosphorus.

•Therefore, these nutrients are moved around different spheres: atmosphere, lithosphere, hydrosphere, and biosphere

•As stated earlier, carbon is found in fossil fuels. When fossil fuels are burned, the carbon is released in the atmosphere. No new carbon was made, it was just cycled.

THE WATER CYCLE•Water continually cycles through the earth’s

spheres. Identify the spheres in this diagram.

1. The sun’s rays evaporate water from oceans and other bodies of water (hydrosphere).

2. As the water vapour rises in the atmosphere, it cools and condenses to form clouds

3. The water falls from the clouds as precipitation

4. As the water falls onto land (lithosphere), into lakes etc., it eventually makes its way back into the oceans/lakes, etc. (runoff, ground water, etc.)

5. Plants and animals intake water and then release it through cellular respiration (biosphere).

This is how water cycles through the 4 spheres

NITROGEN CYCLE

THE NITROGEN CYCLE IN TERRESTRIAL ECOSYSTEMS

•Soil bacteria convert nitrogen in the atmosphere into ammonium.

•Other bacteria convert ammonia into nitrite and then nitrate.

•Plants can absorb these forms of nitrogen through their roots.

• As organisms eat plants, this nitrogen enters the food chain

•When organisms die, decomposers convert nitrate back into nitrogen gas, returning it to the atmosphere, or back into the ammonia in the soil.

•Nitrogen is also returned to the atmosphere as ammonia during volcanic eruptions. Therefore, the lithosphere is also a source of nitrogen.

•In a sustainable ecosystem, the amount of nitrogen that is converted to other forms (ammonia, ammonium, nitrate) is EQUAL to the amount that is returned to the atmosphere.

Eutrophication

•Nitrogen can also enter ecosystems when humans use fertilizers.

•This causes too much nitrogen in an ecosystem!

•Too much nitrogen in water bodies causes eutrophication: excessive algae and plant growth in the water. As they decay, this depletes oxygen and the native species cannot survive.

•Many native species, like bass and trout, cannot survive in lakes with low oxygen levels.

•However, invasive species like carp can, but only to an extent.

THE CARBON CYCLE•Carbon is another essential nutrient that

cycles through the earth’s spheres. The same carbon atoms in your body today have been used in

countless other molecules since time began. The wood burned just a

few decades ago could have produced carbon dioxide which through photosynthesis became

part of a plant. When you eat that plant, the same carbon from the

wood which was burnt can become part of you.

1) Air in the atmosphere has carbon in the form of carbon dioxide gas. Plants use this carbon dioxide for photosynthesis. They make sugars, which are energy-rich, carbon-containing compounds.

2)Organisms break down these sugar molecules through cellular respiration and release carbon dioxide as waste.

PHOTOSYNTHESIS AND CELLULAR RESPIRATION

• Photosynthesis: Plants use the sun’s energy, carbon dioxide, and water to make sugars.

• Cellular respiration: In the presence of oxygen, these sugars are then broken down and released as energy, carbon dioxide, and water.

3)Burning fossil fuels and wood releases CO2 into the atmosphere

4)When organisms die, their carbon-containing molecules become part of the soil. These molecules are broken down by fungi and other decomposers. During this decay, CO2 is released into the air.

5)Under certain conditions, the remains of some dead organisms may be changed into fossil fuels (coal, gas ,oil)

Homework

•p. 27 #1-4

•p. 35 #4, 6

•Also, study the diagram of each nutrient cycle and briefly explain how each nutrient travels through the 4 spheres: biosphere, atmosphere, hydrosphere, and lithosphere.