Biogeochemical Cycles

Mrs. StewartHonors Biology

CLE 3210.3.4 Describe the events which occur during the major biogeochemical cycles.

You will know you have mastered this standard when:

You can predict how changes in a biogeochemical cycle can affect an ecosystem

Objectives:

• Analyze the flow of nutrients in each biogeochemical cycle.

• Evaluate the impact that humans have on the biogeochemical cycles.

Why do we recycle?

• Think – Pair - Share

What sustains life on Earth? • Solar

energy

• The cycling of matter, energy & nutrients

• Gravity

Two Secrets of Survival: Energy Flow and Matter

Recycle• An

ecosystem survives by a combination of energy flow and matter recycling.

MATTER CYCLING IN ECOSYSTEMS

• Nutrient Cycles: Global Recycling– Global Cycles recycle nutrients through

the earth’s air, land, water, and living organisms.

– Nutrients - the elements and compounds that organisms need to live, grow, and reproduce.

Macromolecule Review

• What element does every organic organism contain?

• What are the 5 major elements that create all the macromolecules?

Carbon

CarbonHydrogenOxygenNitrogenPhosphorous

Think – Pair – Share

• What would happen to these elements if they were only capable of being used once? – Think about every time an organism is created

and/or destroyed

They would begin disappearing (dwindling in supply)– like fossil fuels

Biogeochemical Cycles– These are just illustrations or

representations to show how substances move through air, water, soil, rock and living organisms.

Decomposition

•Decomposers:– ultimately responsible for recycling

of chemical nutrients– releasing the nutrients in detritus

•This makes nutrients available again to the autotrophs in the ecosystem

Recycling

• What nutrients get recycled?– Carbon Dioxide– Oxygen– Water– Carbon– Nitrogen– Phosphorous

Water Cycle

Movement of Water

• Three important processes:1. Evaporation – adds water as vapor to

atmosphere (heat) a. Bodies of water, soil, animal bodies, etc.

2. Transpiration – water evaporates from the leaves of plants

3. Precipitation – water released from the atmosphere (temperature, air pressure)

a. Rain, snow, sleet, hail or fog

Water Cycle

Think-pair-share

• What human activities effect the water cycle?– What do we do as humans that could

have positive or negative effects on this cycle

– 2 minutes

Effects of Human Activities on Water Cycle

• We alter the water cycle by:– Withdrawing large amounts of

freshwater.– Clearing vegetation and eroding soils.– Polluting surface and underground

water.– Contributing to climate change.

• How do these changes affect the surrounding ecosystems?

Objectives:

• Analyze the flow of nutrients in each biogeochemical cycle.

• Evaluate the impact that humans have on the biogeochemical cycles.

Carbon Cycle

Photosynthesis vs Cellular Respiration

• Photosynthesis absorbs CO2 from the atmosphere/biosphere and releases O2

• Cellular respiration absorbs O2 from the atmosphere/biosphere and releases CO2

Carbon is found in 5 major places:

1. Living and dead organisms2. Carbon Dioxide (CO2) in atmosphere

3. Organic matter in the soil4. Fossil fuels and rock deposits5. Oceans – dissolved CO2 and shells

Do these plants contain Carbon?

What happens to the carbon now?

Where is the carbon?

Think-pair-share

• What human activities effect the Carbon-Oxygen cycle?– What do we do as humans that could

have positive or negative effects on this cycle

– 2 minutes

Effects of Human Activities on Carbon Cycle

• We alter the carbon cycle by adding excess CO2 to the atmosphere through:– Burning fossil

fuels.– Clearing

vegetation faster than it is replaced.

• How do those changes affect the surrounding ecosystems?

Objectives:

• Analyze the flow of nutrients in each biogeochemical cycle.

• Evaluate the impact that humans have on the biogeochemical cycles.

Nitrogen Cycle

Nitrogen Uses:

• Proteins– Enzymes, skin,

muscles, etc.

• Nucleic Acids– DNA– RNA

Forms of Nitrogen

• Nitrogen is found in many forms in the atmosphere / ecosystem– N2 = nitrogen gas (79% of atmosphere)

– N2O = nitrous oxide

– NH3 = ammonia

– NH4 = ammonium

– NO3 = nitrate

– NO2 = nitrite

Nitrogen Fixation

• Converting N2 gas to nitrate (only usable form of nitrogen for most plants)

• 2 types:– Natural = lightning, fires and bacteria– Human = fossil fuel combustion,

fertilizer manufacturing

Nitrogen-fixing bacteria

• bacteria that transform Nitrogen gas into a usable form (Nitrate)– Live in the soil – May live in the swellings on the roots of

some plants (ex. Beans, peas, clover)• These plants provide sugars for the bacteria,

and the bacteria provide usable nitrogen.

Recycling Nitrogen

• Where is Nitrogen found?– Dead organisms

(as proteins & nucleic acids)

– Urine & dung• Decomposers: break

down and release Nitrogen as NH3 (ammonia)

Nitrogen Processes• Ammonification – converting NH3

(ammonia) to NH4 (ammonium)

• Nitrification – converting NH4 (ammonium) into NO2 (nitrite) or NO3 (nitrates)

• Denitrification – anaerobic bacteria break down NO3 (nitrates) and release N2 (nitrogen gas) into the atmosphere

Nitrogen Sources:

• Plants = Nitrates from the soil– Use to form proteins

• Animals = eating plants/organisms and digesting the proteins and nucleic acids

• Humans = have doubled the amount of fixed N2 in the atmosphere in the last 100 years.– HOW?

Too much of a good thing?

• Too much nitrogen in aquatic ecosystems results in:

•Eutrophication = excess nutrients stimulate plant growth (algal blooms); when these plants die, decomposers use up the available oxygen during decomposition.

Eutrophication

Nitrogen Cycle

Think-pair-share

• What human activities effect the Nitrogen cycle?– What do we do as humans that could

have positive or negative effects on this cycle

– 2 minutes

Effects of Human Activities on the Nitrogen Cycle

• We alter the nitrogen cycle by:– Adding gases that contribute to acid rain.– Adding nitrous oxide to the atmosphere

through farming practices which can warm the atmosphere and deplete ozone.

– Contaminating ground water from nitrate ions in inorganic fertilizers.

– Releasing nitrogen into the troposphere through deforestation.

Effects of Human Activities on the Nitrogen Cycle

• Human activities such as production of fertilizers now fix more nitrogen than all natural sources combined.

How does this affect the surrounding ecosystems?

• Acid rain• creation of ground level

ozone• groundwater contamination• eutrophication.

•Exploring the Nitrogen Cycle Activity

Objectives:

• Analyze the flow of nutrients in each biogeochemical cycle.

• Evaluate the impact that humans have on the biogeochemical cycles.

Phosphorus Cycle

Overview

• Movement of phosphorus from the environment, to organisms, and back to the environment

• Slow process

• Normally does not occur in atmosphere because phosphorus rarely occurs as a gas

Phosphorus Uses:• Essential material for animals

– Form bones, teeth, molecules (DNA/RNA)

Where do organisms get phosphorus?

• Plants = absorb from soil and water• Animals = eating plants & other organisms

Cycle• Rocks erode, and small amounts of

phosphorus dissolve as phosphate PO4 3-, in soil and water

• Excreted in wastes from organisms• Released by decomposers from dead

organisms• Plants absorb from soil and water, through

roots• Animals eat plants/other organisms• Some in fertilizers and applied to fields/crops• Washes off into streams, groundwater and

soil

Phosphorus Cycle

Think-pair-share

• What human activities effect the Phosphorus cycle?– What do we do as humans that could

have positive or negative effects on this cycle

– 3 minutes

Effects of Human Activities on the Phosphorous Cycle

• We remove large amounts of phosphate from the earth to make fertilizer.

• We reduce phosphorous in tropical soils by clearing forests.

• We add excess phosphates to aquatic systems from runoff of animal wastes and fertilizers.

What determines population size?

Environment vs Habitat

• Many species can survive in more than one environment.

• But each species has its “home” or habitat. – Fish may be able to

live in fish tanks, but would rather live in the wild

What do organisms need to survive?

• Basic requirements for survival include:– Food – Water– Shelter

Competition

• An important aspect of the struggle for survival involves competition for limited resources– Food– Water – Shelter– Sunlight

Limiting Factors

• Limiting factors are factors that affect the population size of a species in a specific environment.

• They can be abiotic or biotic.

Predator – Prey relationship

• Predators are a biotic limiting factor.

• They control population size by feeding on prey.

• There is a delicate balance that needs to be maintained.

Carrying Capacity

• When all the limiting factors are considered together we can determine the maximum number of organisms that can survive in an area.

How do we determine the Carrying Capacity of a

Species?• All limiting factors

must be taken into consideration.

• It is very difficult to determine the actual carrying capacity.

The Lesson of the Kaibab Deer

• Purpose: – to graph data on the

Kaibab deer population of Arizona from 1905~1939

– to analyze the methods responsible for the changes in the deer population

– to propose a management plan for the Kaibab deer population

How Many Bears??

Kaibab Forest: North Rim of the Grand Canyon

Key Idea

• All organisms have the ability to produce populations of unlimited size

• But their environment keeps their numbers in check.

• THINK-PAIR-SHARE– How?– List examples of

limiting factors.

– 3 minutes