Biogeochemical Cycles

Represent the movement of a particular form of matter through the
living and nonliving parts of an ecosystem.

BIOGEOCHEMICAL

CYCLES

The 3 main cycles are:
1)

Water Cycle

2)

Carbon Cycle

3)

Nitrogen Cycle

The Water Cycle

Water = H2O and is necessary for the life processes of ALL living things

Water is found in

1.Earth’s surface

2.

Under earth’s surface

3.

In the atmosphere

4.

In living organisms

The water cycle is driven by the SUN which causes evaporation from
reservoirs and organisms.

Multiple Choice

What is the water cycle driven by?

• the sun

• water

• the earth

• temperature

The 6 Big
Steps

Precipitation

Water falls to the earth as liquid (rain, sleet, snow, etc)

Infiltration

Some water seeps
underground from the
surface of earth.

-Aquifer = an
underground layer
Of permeable rock
that can
hold water.

Infiltration

Runoff

Liquid water that is NOT
infiltrated runs along the
surface and collects in bodies
of water.

Infiltration

Evaporation

Sun heats liquid water to vapor and it rises into the atmosphere

Infiltration

Transpiration

Water rises back into the atmosphere as water vapor from plants

Infiltration

Open Ended

What is transpiration?

Condensation

Water vapor condenses to form clouds before precipitating again.

Infiltration

Multiple Choice

What step in the water cycle involves water turning to a gas from a liquid?

• precipitation

• evaporation

• transpiration

• condensation

Multiple Choice

What step in the water cycle involve water moving from a gas to a liquid.

• transpiration

• evaporation

• precipitation

• condensation

HOW DO HUMANS IMPACT

THE WATER CYCLE?

1. Pollution

2. Deforestation = decreased transpiration

3. Paving/building = more runoff, less
infiltration

Open Ended

How do paved roads affect the water cycle?

Multiple Choice

How can we reduce pollution and protect earth's freshwater?

• reduce, reuse, recycle

• minimize the use of pesticides and fertilizers

• support laws that reduce industrial waste

• all of the above

Carbon is found in…

Large molecules
necessary for life

MACROMOLECULES

PROTEINS (muscles, skin, etc)

CARBOHYDRATES (starches,
sugars)

LIPIDS (fats)

NUCLEIC ACIDS (DNA & RNA)

Carbon is found in…

In soil or aquatic sediments

FOSSIL FUELS & MINERALS

ROCKS

Coal, oil, natural gas

Organic (living)

materials

As CO2

Our ATMOSPHERE

Photosynthesis

Plants capture CO2 from the
atmosphere and use it to
make sugar

MAIN STAGES of the CARBON CYCLE

CELLULAR
RESPIRATION

CO2 is released into
atmosphere as waste from
metabolism.

MAIN STAGES of the CARBON CYCLE

CONSUMPTION

One organism eats another for
carbon

MAIN STAGES of the CARBON CYCLE

DECOMPOSITION


Decomposers break down
carbon from dead organisms,
recycling it in the soil

MAIN STAGES of the CARBON CYCLE

Open Ended

What part do decomposers play in the carbon cycle?

FOSSILIZATION

Converts carbon from
once-living organisms into
fossil fuels through intense
heat and compression

MAIN STAGES of the CARBON CYCLE

COMBUSTION

CO2 is released into the
atmosphere from burning
things (anything)

MAIN STAGES of the CARBON CYCLE

HOW DO HUMANS IMPACT

THE CARBON CYCLE?

COMBUSTION: when we burn things, we
cause a major increase in CO2 in the
atmosphere

Open Ended

What are the consequences of having too much carbon in the atmosphere?

Multiple Choice

How can we reduce the amount of carbon humans release into the atmosphere?

• drive more cars

• support laws that restrict use of fossil fuels

• burn your garbage at home

• cut down trees to use as fuel

Refresher: what is a
biogeochemical
cycle?

movement of a particular form of matter
through the living and nonliving parts of an
ecosystem.

Think about this question throughout the rest
of class.

How does the
nitrogen cycle
maintain balance in
our ecosystem?

THE MAIN
STAGES

Nitrogen Fixation

Bacteria or lightning
convert nitrogen into
forms that plants can
use.

THE MAIN
STAGES

Consumption

One organisms eats
another and obtains
nitrogen through it.

THE MAIN
STAGES

Decomposition:
Decomposers like
bacteria break down
dead matter,
returning nitrogen to
soil.

Ammonification:
Bacteria convert the
nitrogen from waste
into ammonia.

THE MAIN
STAGES

Nitrification:
Bacteria convert the
ammonia into
nitrates & nitrites to
be absorbed by
plants in their roots

* this is how nitrogen
enters the food chain
and reaches us

THE MAIN
STAGES

Denitrification:

Bacteria convert the
ammonia into N2
(gas) so it can return
to the atmosphere.

The nitrogen cycle is different from other biogeochemical
cycles in that no step is completed without help of
living organisms!

The Nitrogen Cycle and
Living Organisms

Multiple Choice

What does the nitrogen cycle need in order to continue?

• clouds

• rocks

• living organisms

• sand

HOW DO HUMANS IMPACT

THE NITROGEN CYCLE?

FERTILIZERS add way too much nitrogen to the
soil
COMBUSTION - burning fossil fuels releases
excess nitrogen into the atmosphere

Open Ended

How does using lots of fertilizer cause imbalance in the nitrogen cycle?

Multiple Choice

In summary, what do all biogeochemical cycles have in common?

• They all involve the circulation of an element through biotic and abiotic components of Earth

• They all need living organisms to power every step of the cycle

• They all use up a resource until it cannot be used anymore

• They all require pollution by human beings in order to continue throughout time

Draw

Draw one of the cycles (water, carbon, nitrogen). Be sure to include at least 3 places on earth that it can cycle through.