Giraffes eat the grassLions eat the giraffesAnd when they die, they become part of the soil and feed the grass

Wait…seriously…this is mind blowing stuff!

Everything here has always been here I know. Wait? What?

Biogeochemical Cycles

Water Carbon Nitrogen Phosphorus Sulfur

Does any of this look familiar?

The Water Cycle Water comes down as

precipitation, goes into the earth (groundwater) or the oceans, and is taken up by plants. It returns to the air by evaporation and transpiration.

Earth to plants (geo and bio)

transpiration

The water that

comes out of

plants!

Water gets cleaned through this cycle

Evaporation leaves the other stuff behind Flowing water naturally filtered - mostly by

decomposers

Human Impact

1. We take too much fresh water - faster than it can be replenished naturally

2. We clear plants and replace with concrete - this increases soil erosion and landslide risk, increases flooding risk, reduces groundwater replenishment, decreases transpiration

Carbon, Carbon, everywhere

The carbon cycle is a series of processes through which all carbon atoms in existence rotate

All the carbon on earth and in living things gets recycled over and over again.

Where is the Carbon? Carbon is found in the environment as:

– CO² gas in the atmosphere (air)

– dissolved CO2 in the oceans (water)

– Carbon in organic molecules in every living thing

– Carbon is in fossil fuels and sedimentary rocks

Carbon moves from the air into plants

Carbon moves from the atmosphere into plants through a process called photosynthesis

Review - Photosynthesis

Plants take CO2 + water + energy from the sun

And make

Glucose (sugar) and oxygen

CO2 + H2O C6H12O6 + O2

Carbon is in animals

Animals get their carbon when they eat

How does carbon get back into the air?

Carbon is returned to the atmosphere when an organism does cellular respiration

All living things give off CO2

DecomposersWhen decomposers

break down dead things, they return the carbon in those dead organisms to the air

Summing it up

What is the GEO part of this cycle (where is the carbon on earth?)

What is the BIO part of this cycle?

In other words, what are the reservoirs of carbon?

If an organism dies and is buried very quickly, before decomposers can get to it, the carbon in the organism may turn into coal, gas, or oil.

We call this fossil fuel.

Human Impact

When fossil fuels are burned, the carbon in them is released into the atmosphere

When we burn trees, we release the carbon in them.

The carbon gets put into the air.

Carbon diffuses into water Carbon in the atmosphere diffuses into the

oceans Forms carbonic acid

– CO2 + H20 H2CO3

Too much CO2 in oceans leads to ocean acidification

Human Impact Removal of trees and other plants reduces

the amount of CO2 that can be removed from the atmosphere through photosynthesis

Alaska Brazil

Let’s Review How does Carbon get into the atmosphere?

– every living thing gives off CO2

– burning of organic matter like wood

– burning of fossil fuels like coal and oil

– through the decomposition of dead plants and animals How does carbon get out of the atmosphere?

– By plants through photosynthesis

Diagram the Carbon Cycle

Work in pairs to diagram the carbon cycle Include: Respiration Burning/Combustion Fossil fuels Decomposition Photosynthesis Exchange with oceans/ocean acidification Digestion LABEL all processes with arrow that show the direction

carbon is moving

Do nowDo now1. Get out the Carbon

Cycle Game

2. Fill in as much as you can about the water water and carboncarbon cycles on your graphic organizer.

Cycle Name

Reservoirs Major Processes

How it moves from the earth

into living things

How it is returned to the earth

Human Impact on the cycle/Environmental Concerns

Water Cycle

                

Carbon Cycle

                

Nitrogen Cycle

                

Phosphorus Cycle

                

Sulfur Cycle

                

The Nitrogen Cycle

Where is the nitrogen? Most of the

nitrogen (the main reservoir) is in the air.– 78% of our air is

nitrogen gas The nitrogen is the

air cannot be used as it is by most organisms– It has to be “fixed”

first.

How does the nitrogen get fixed?

There are 2 ways:– Lightning can fix the

nitrogen in the air – Lightning causes

nitrogen and oxygen in the air to combine into nitric oxide (NO) and nitrogen dioxide (NO2). This will fall with the rain to the soil.

Fixing Nitrogen

Most of the nitrogen that is fixed is done by special bacteria

These bacteria live in the roots of legumes– Legumes are plants like

alfalfa, clover, and soybeans

The bacteria live in root nodules of these plants.

There, they fix nitrogen into a usable form for the plant

Nitrogen Fixation Nitrogen Fixation: Lighting = 10% Bacteria = 90%

– N2 is combined with H to make ammonia

– Bacteria use some, put the rest in the soil for plants

– Plants can convert ammonia (NH3) to ammonium (NH4

+)

– Remaining ammonia goes through nitrification

Nitrification Ammonia in soil (NH3) &ammonium

(NH4+) converted by bacteria to nitrate ions

(NO3-), which plants happily take up

Because crop plants generally require large amounts of nitrogen for growth, nitrogen frequently becomes the limiting soil nutrient for plant growth.

Nitrogen needs

Farmers and gardeners add nitrogen back into the soil by commercial fertilizers and, more naturally, by crop rotation.

Plants take up nitrates and convert it to amino acids, nucleic acids, vitamins. Animals acquire all of their nitrogen when they eat plants (and other animals).

All living things need nitrogen.

Plants use nitrogen to make important molecules such as proteins, nucleic acids (DNA) and other major cellular components

Returning Nitrogen to the Earth

When animals and plants die nitrogen is released back to the soil by decomposers.

This process is known as ammonification

Ammonification

Animal waste products (urine and manure) also return nitrogen to the soil.

Urine from animals contains excess nitrogen which is returned to the soil. When an organism dies, the nitrogen molecules return to the soil. Plants reuse these nitrates and ammonia molecules

Denitrification The usual form of nitrogen

returned to the soil in animal waste or by decomposers is ammonia. The ammonia is somewhat toxic, but is converted into nitrates by nitrate bacteria. The nitrate can be then be used by plants and the cycle continues.

What returns nitrogen to the air?

Bacteria that are called denitrifying bacteria act on nitrate molecules and put nitrogen back into the air as N2.

Atmospheric Nitrogen

N2

NO3-

Human Impact

Algae bloom resulting from excess nitrates from farm runoff (manures).

Burning fossil fuels puts NO2 & HNO3 into the air = acid deposition

Just as nitrogen acts as an excellent fertilizer for agricultural crops, it also acts as a fertilizer in aquatic ecosystems. When too much nitrogen is washed into a waterway, it promotes an explosion of plant and algae growth, knocking the system out of balance. The plants and algae grow very fast and deplete the available oxygen supply.

The worst-case scenario is the creation of so-called dead zones, where nothing can live. The Gulf of Mexico, Chesapeake Bay, and Black Sea all have dead zones, with devastating consequences to marine life and the livelihoods of those who depend on the fisheries.

Human Impact Put N2O into the atmosphere

when anaerobic bacteria feed on animal waste and fertilizer

This is a greenhouse gas This breaks down the ozone

layer

Take a few minutes

To fill in as much as you can about the nitrogen cycle on your table.

The Phosphorus Cycle

Where is the phosphorus? A major difference with this cycle is that there is no there is no

atmospheric component. atmospheric component.

This process tends to be slow and local in nature.

Where is the phosphorus? Most of our phosphorus

is stored in rocks and stored in rocks and sedimentsediment.

It is released through weathering and erosion. Plants can then take it Plants can then take it up through the soilup through the soil and water.

What about us?

All consumers get their All consumers get their phosphorus through their foodphosphorus through their food.

Phosphorus is used to build bones used to build bones and teeth in animals, and DNAand teeth in animals, and DNA in all living things

Decomposers

Decomposers also help put phosphorus in Decomposers also help put phosphorus in the soilthe soil and water by breaking down dead organisms and their waste.

Phosphatizing bacteria are important in converting this phosphorus into a more usable form for plants.

Waste Waste productsWaste products,,

especially fish eating bird guano, is high high in phosphorusin phosphorus and contributes a little bit to the overall cycle.

Trapped phosphorus

Weathering and Weathering and erosion wash erosion wash phosphorus phosphorus from rocks into from rocks into the oceanthe ocean.

There it can sink to the bottom, become part of the sediment, and be trapped out of circulation for some time.

Problems associated with the phosphorus cycle

Since phosphorus phosphorus is needed for plant growth, it is often added inin the form of fertilizersfertilizers.

Just like nitrogen, too much phosphorus can pollute waterwayspollute waterways and lead to euthrophication (dead zones).

Take a few minutes

To fill in as much as you can about the phosphorus cycle on your table.

The Sulfur Cycle

Most of the sulfur is stored underground in rocks and minerals (sulfate ions - SO4

2-)

Sulfur to the air From volcanoes

and anaerobic decomposers in wet ecosystems (swamps, etc)

As H2S - hydrogen sulfide - rotten egg

As SO2 - suffocating

Sulfur and clouds

Some plankton make dimethyl sulfide (DMS or CH3SCH3)

– These serve as nuclei for condensation of water into droplets in clouds

– So changes in DMS = changes in clouds!

Completing the cycle Bacteria in low oxygen environments

convert sulfate ions to sulfide ions (S2-) Sulfide reacts with metals to make metallic

sulfides which form rocks

Human Impacts

Burning coal and oil puts sulfur into the atmosphere

We refine sulfur containing petroleum which puts sulfur into the air

We convert sulfur containing mineral ores into metals like copper, zinc, lead and out sulfur into the air

All this = acid deposition

Take a few minutes

To fill in as much as you can about the sulfur cycle on your table.

Human Impact on Ecosystems1. Nutrient enrichment – adding

excess nutrients to aquatic ecosystems

2. Acid precipitation – pH less than 5.6, harms trees, aquatic ecosystems,

3. Biological magnification – toxins accumulate in the tissues of organisms, PCBs and DDT

4. Rising atmospheric CO2 – global warming

5. Depletion of the ozone layer – CFCs, burns leaves and skin