Biogeochemical cycles

Chapter 4Chapter 4

Biogeochemical CyclesBiogeochemical Cycles

Objectives:Objectives:

Identify and describe the flow of nutrients in Identify and describe the flow of nutrients in each biogeochemical cycle. each biogeochemical cycle.

Explain the impact that humans have on the Explain the impact that humans have on the biogeochemical cycles.biogeochemical cycles.

Chapter Overview QuestionsChapter Overview Questions

What happens to energy in an ecosystem?What happens to energy in an ecosystem? What happens to matter in an ecosystem?What happens to matter in an ecosystem?

What Sustains Life on Earth?What Sustains Life on Earth?

Solar energy, Solar energy, the cycling of the cycling of matter, and matter, and gravity sustain gravity sustain the earth’s life.the earth’s life.

Figure 3-7Figure 3-7

Two Secrets of Survival: Energy Flow Two Secrets of Survival: Energy Flow and Matter Recycleand Matter Recycle

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


MATTER CYCLING IN MATTER CYCLING IN ECOSYSTEMSECOSYSTEMS

Nutrient Cycles: Global RecyclingNutrient Cycles: Global Recycling Global Cycles recycle nutrients through the Global Cycles recycle nutrients through the

earth’s air, land, water, and living organisms.earth’s air, land, water, and living organisms. Nutrients are the elements and compounds that Nutrients are the elements and compounds that

organisms need to live, grow, and reproduce.organisms need to live, grow, and reproduce. Biogeochemical cycles move these substances Biogeochemical cycles move these substances

through air, water, soil, rock and living organisms.through air, water, soil, rock and living organisms.

Water’ Unique PropertiesWater’ Unique Properties There are strong forces of attraction between There are strong forces of attraction between

molecules of water.molecules of water. Water exists as a liquid over a wide Water exists as a liquid over a wide

temperature range. temperature range. Liquid water changes temperature slowly.Liquid water changes temperature slowly. It takes a large amount of energy for water to It takes a large amount of energy for water to

evaporate.evaporate. Liquid water can dissolve a variety of Liquid water can dissolve a variety of

compounds.compounds. Water expands when it freezes.Water expands when it freezes.

Fig. 3-26, p. 72

PrecipitationPrecipitation

Transpiration

Condensation

Evaporation

Ocean storage

Transpiration from plants

Precipitation to land

Groundwater movement (slow)

Evaporation from land Evaporation

from ocean Precipitation to ocean

Infiltration and Percolation

Rain clouds

RunoffSurface runoff

(rapid)

Surface runoff (rapid)

Effects of Human Activities Effects of Human Activities on Water Cycleon Water Cycle

We alter the water cycle by:We alter the water cycle by: Withdrawing large amounts of freshwater.Withdrawing large amounts of freshwater. Clearing vegetation and eroding soils.Clearing vegetation and eroding soils. Polluting surface and underground water.Polluting surface and underground water. Contributing to climate change.Contributing to climate change.

Fig. 3-27, pp. 72-73

Effects of Human Activities Effects of Human Activities on Carbon Cycleon Carbon Cycle

We alter the We alter the carbon cycle by carbon cycle by adding excess COadding excess CO22 to the atmosphere to the atmosphere through:through: Burning fossil fuels.Burning fossil fuels. Clearing vegetation Clearing vegetation

faster than it is faster than it is replaced.replaced.


What Sustains Life on Earth?

• Solar energy, the cycling of matter, and gravity sustain the earth’s life.


Effects of Human Activities Effects of Human Activities on the Nitrogen Cycleon the Nitrogen Cycle

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

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

Contaminating ground water from nitrate ions in Contaminating ground water from nitrate ions in inorganic fertilizers.inorganic fertilizers.

Releasing nitrogen into the troposphere through Releasing nitrogen into the troposphere through deforestation.deforestation.

Effects of Human Activities Effects of Human Activities on the Nitrogen Cycleon the Nitrogen Cycle

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


What Sustains Life on Earth?

• Solar energy, the cycling of matter, and gravity sustain the earth’s life.


Fig. 3-31, p. 77

Dissolvedin Ocean

Water

Marine Sediments Rocks

uplifting overgeologic time

settling out weatheringsedimentation

LandFoodWebs

Dissolvedin Soil Water,Lakes, Rivers

death,decomposition

uptake byautotrophs

agriculture

leaching, runoff

uptake byautotrophs

excretion

death,decomposition

mining Fertilizer

weathering

Guano

MarineFoodWebs

Effects of Human Activities Effects of Human Activities on the Phosphorous Cycleon the Phosphorous Cycle

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

We reduce phosphorous in tropical soils by We reduce phosphorous in tropical soils by clearing forests.clearing forests.

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

Fig. 3-32, p. 78

Hydrogen sulfide

Sulfur

Sulfate salts

Decaying matter

Animals

Plants

Ocean

IndustriesVolcano

Hydrogen sulfideOxygen

Dimethyl sulfide

Ammoniumsulfate

Ammonia

Acidic fog and precipitationSulfuric acid

WaterSulfurtrioxide

Sulfur dioxide

Metallicsulfidedeposits

Effects of Human Activities Effects of Human Activities on the Sulfur Cycleon the Sulfur Cycle

We add sulfur dioxide to the atmosphere by:We add sulfur dioxide to the atmosphere by: Burning coal and oilBurning coal and oil Refining sulfur containing petroleum.Refining sulfur containing petroleum. Convert sulfur-containing metallic ores into free Convert sulfur-containing metallic ores into free

metals such as copper, lead, and zinc releasing metals such as copper, lead, and zinc releasing sulfur dioxide into the environment.sulfur dioxide into the environment.

The Gaia Hypothesis:The Gaia Hypothesis: Is the Earth Alive? Is the Earth Alive?

Some have proposed that the earth’s various Some have proposed that the earth’s various forms of life control or at least influence its forms of life control or at least influence its chemical cycles and other earth-sustaining chemical cycles and other earth-sustaining processes.processes. The strong Gaia hypothesis: life The strong Gaia hypothesis: life controlscontrols the the

earth’s life-sustaining processes.earth’s life-sustaining processes. The weak Gaia hypothesis: life The weak Gaia hypothesis: life influencesinfluences the the

earth’s life-sustaining processes.earth’s life-sustaining processes.

What do you think?What do you think?

Does life on earth control earth’s life-Does life on earth control earth’s life-sustaining processes or does life merely sustaining processes or does life merely influence these life-sustaining process? influence these life-sustaining process? FRQ Format.FRQ Format.

Biogeochemical cycles

Technology

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