The Cycling of Materials

Recycling Matters

Unlike the one way flow of energy in an ecosystem (remember food chains, food webs), matter is recycled within and between ecosystems.

Biogeochemical cycles – cycling of matter between the biological, geological and chemical parts of the biosphere.

Recycling matters

Matter is transformed into living tissue or passed out of the body as waste.

Brainstorm: What happens when you breathe?

Brainstorm

Breathe out CO2 Plant takes in CO2 during photosynthesis, making

carbohydrates (ex. Fruit) Fruit (containing carbon) is eaten by a deer Deer passes the processes food (carbon) out Dung beetle eats the waste Shrew eats the beetle Owl eats the shrew

The carbon that you originally breathed out is not part of the owl.

Natures Cycles

Carbon Nitrogen Phosphorus Water

Carbon Cycle

Carbon is an essential component of proteins, fats, carbohydrates – the basic ingredients of life.

Key component in carbonates that make bones and shells.

Carbon Cycle

All living things are made of carbon. Carbon is also a part of the ocean, air, and even rocks. Because the Earth is a dynamic place, carbon does not stay still. It is on the move!

Carbon Cycle

Carbon cycle - the recycling of carbon between the atmosphere, land, water, and organisms.

There are 4 main ways that carbon is cycled in the environment:– Biological– Geochemical– Decomposition– Human activities

Carbon Cycle

Biological Process:– Respiration – CO2 is released when organisms

breathe and is used by plants to produce more plant material

– Photosynthesis - Plants take in CO2 and use during photosynthesis to produce sugars and more living tissue

Carbon Cycle

Geochemical– Erosion of soil moves carbon into the

waters– Weathering of rocks releases bound

carbon.– Volcanic activity releases carbon to the

atmosphere, water and land Decomposition

– Dead matter breaks down and releases stored carbon

– Fossilized dead plants gives us fuel (coal, petroleum)

Carbon Cycle

Human Activities:– What human activities do you think influence the

carbon cycle? Burning of fossil fuels (coal, gas) Mining of fossil fuels Removal and burning of trees

Carbon dioxide is a greenhouse gas and traps heat in the atmosphere. Without it and other greenhouse gases, Earth would be a frozen world.

Carbon Cycle

Carbon Cycle - Summary

In the short-term carbon cycle, plants convert carbon

dioxide, CO2, from the atmosphere into carbohydrates.

When organisms’ bodies break down the carbohydrates

and release some of the carbon back into the air as CO2

or through their organic wastes as CO2 or methane, CH4.

In the long-term carbon cycle, carbon is stored in the

geosphere in a type of rock called a carbonate.

Nitrogen Cycle

Nitrogen cycle represents one of the most important nutrient cycles found in terrestrial ecosystems.

Nitrogen is used by living organisms to produce a number of complex organic molecules like amino acids, proteins, and nucleic acids.

April 7, 2008

Nitrogen Cycle

Nitrogen plays an important role in the cycle of life.

The atmosphere is 78% Nitrogen. It exists in the air mainly as a gas (mainly N2). The gaseous form is mainly unusable by most lifeforms.

Other major stores of nitrogen include organic matter in soil and the oceans.

N2N2 N2N2N2

Nitrogen Cycle

Nitrogen Cycle

Sources:

– Atmosphere

– Dead and decaying Organic Matter

– Human Activities

Nitrogen Cycle

Atmosphere:– Nitrogen makes up 78% of the earth’s

atmosphere, but is unusable to most organisms.

– Bacteria that live in the soil and roots of legumes (soybeans), can convert the Nitrogen gas to ammonia. This is called Nitrogen Fixation.

– Almost all of the nitrogen found in any terrestrial ecosystem originally came from the atmosphere.

N2

Nitrogen Cycle

Organic Matter:

– Organic nitrogen is converted into inorganic forms when it re-enters the biogeochemical cycle via decomposition (atmosphere).

– Decomposers found in the upper soil layer, chemically modify the nitrogen found in organic matter from ammonia (NH3 ) to ammonium (NH4+ ). This process is known as mineralization.

Nitrogen Cycle

Organic Matter:– In most ecosystems nitrogen is primarily

stored in living and dead organims = organic matter.

– Animals receive the required nitrogen they need for metabolism, growth, and reproduction by eating.

Nitrogen Cycle

Despite its abundance in the atmosphere, nitrogen is often the most limiting nutrient for plant growth. This problem occurs because most plants can only take up nitrogen in two solid forms: – Ammonium (NH4

+ )

– nitrate (NO3- )

Most plants obtain the nitrogen they

need as inorganic nitrate from the soil solution.

N2

Members of the bean family (legumes) and some other kinds of plants form mutualistic symbiotic relationships with nitrogen fixing bacteria.

In exchange for some nitrogen, the bacteria receive from

the plants carbohydrates and special structures (nodules) in roots where they can exist in a moist environment.

Scientists estimate that biological fixation globally adds approximately 140 million metric tons of nitrogen to ecosystems every year.

Nitrogen Cycle

Human impacts on the nitrogen cycle:

– Over application of Nitrogen fertilizers Enter groundwater, rivers, streams

Eutrophication – caused by excess N entering waters

– Livestock ranching. Wastes from animals can runoff into waters or leach into

groundwater

– Sewage waste and septic tank leaching.

Nitrogen Cycle

Nitrogen Cycle - Summary

In the nitrogen cycle, nitrogen moves from the air to soil, soil to plants and animals, and back to air again.

Nitrogen is removed from air mainly by the action of nitrogen-fixing bacteria in the soil.

The nitrogen enters plants, which are eaten by animals.

The nitrogen is returned to the soil by decay and by animal wastes.

Chemical processes that occur in the soil then release the nitrogen back into the air.

Human activities influence the release of Nitrogen into the air or water.

Phosphorus Cycle

The phosphorus cycle is the movement of phosphorus from the environment to organisms and back to environment.

This is a slow cycle because it does not occur in the atmosphere.

Phosphorus Cycle

• Phosphorus (P) is essential for plant growth (DNA/RNA). It stimulates growth of young plants, giving them a good and vigorous start.

Phosphorus Cycle

Remains mostly on land as rock, soil minerals and ocean sediment (inorganic phosphate).– Re-enters when rock breaks down/soil erodes

Plants take phosphate from soil or water, plants bind phosphate into organic compounds.– Re-enters from dead and decaying matter

Phosphorus Cycle

Moves through food web from producers to consumers.– Re-enters cycle from waste products

Phosphorus Impacts:– Phosphorus can build up in soils causes high P-

levels in soil. – Runoff in sediment as soil erodes can cause an

excess in water (algal blooms).

Phosphorus Cycle

Phosphorus Cycle - Summary

During the phosphorus cycle, phosphorus moves through every sphere except the atmosphere.

Phosphorus enters soil and water when rock breaks down, when phosphorus in rock dissolves in water, or when organisms excrete phosphorus in their waste.

Plants absorb phosphorus through their roots and incorporate the phosphorus into their tissues.

Animals absorb the phosphorus when they eat the plants. When the animals die, the phosphorus returns to the environment through decomposition.

Water Cycle

Water Cycle - Summary

The movement of water from the atmosphere to Earth’s surface and back to the atmosphere is called the water cycle.

In the water cycle, water changes from liquid water to water vapor through the energy transfers involved in evaporation and transpiration.

During these processes, water absorbs heat and changes into a gaseous state.

When the water loses energy, it condenses to form water droplets, such as those that form clouds and fall to Earth’s surface as precipitation.

Nutrient Limitations

Primary productivity – rate at which organic matter is created by producers.– Controlled by amount of available nutrients

Limiting Nutrient – when a single nutrient is scarce or cycles very slowly in an ecosytem.

Nutrient Limitations

Three important nutrients – N, P, K– Nitrogen, phosphorus, potassium

Farmers/home owners add to ensure crop productivity.

Aquatic system impacts – algal blooms, eutrophication.