BIOGEOCHEMICAL CYCLES

ATMOSPHERE

LITHOSPHERE

HYDROSPHERE

ECOSPHERE

HYDROLOGIC CYCLE

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Figure 4-28Page 76

Precipitation toland

Transpirationfrom plants

Runoff Surface runoff(rapid)

Evaporationfrom land Evaporation

from ocean Precipitation toocean

Ocean storage

Surfacerunoff(rapid)

Groundwater movement (slow)

Rain cloudsCondensation

Transpiration

Evaporation

PrecipitationPrecipitation

Infiltration andPercolation

HYDROLOGIC CYCLE

CONNECTS ALL OF THE

CYCLES AND

SPHERES TOGETHER

HUMAN IMPACTS TO WATER CYCLE

1. Water withdrawal from streams, lakes and groundwater. (salt water intrusion and groundwater depletion)

2. Clear vegetation from land for agriculture, mining, road and building construction. (nonpoint source runoff carrying pollutants and reduced recharge of groundwater)

3. Degrade water quality by adding nutrients(NO2, NO3, PO4) and destroying wetlands (natural filters).

4. Degrade water clarity by clearing vegetation and increasing soil erosion.

Water Quality Degradation

MARINE CARBON CYCLE

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Diffusion between atmosphere and ocean

Carbon dioxidedissolved in ocean water

Marine food websProducers, consumers,

decomposers, detritivores

Marine sediments, includingformations with fossil fuels

Combustion of fossil fuels

incorporation into sediments

death, sedimentation

uplifting over geologic time

sedimentation

photosynthesis aerobic respiration

Figure 4-29aPage 78

TERRESTRIAL CARBON CYCLE

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photosynthesis aerobic respirationTerrestrial

rocks

Soil water(dissolved

carbon)

Land food websproducers, consumers,

decomposers, detritivores

Atmosphere(most carbon is in carbon dioxide)

Peat,fossil fuels

combustion of wood (for clearing land; or for fuel

sedimentation

volcanic action

death, burial, compaction over geologic timeleaching

runoff

weathering

Figure 4-29b Page 79

Combustion of fossil

fuels

Primary Productivity Connection

• Gross Primary Productivity (GPP) – the rate at which an ecosystem’s producers capture and store a given amount of chemical energy as biomass in a given period of time.

• Net Primary Productivity (NPP) – the rate at which all the plants in an ecosystem produce net useful energy; equal to the difference between energy produced through photosynthesis and energy used for cellular respiration.

PHOTOSYNTHESIS

Photosynthesis: occurs within the chloroplasts of green plants. The photosynthetic membranes are arranged in flattened sacs called the thylakoids.

6CO2 + 12H2O C6H12O6 + 6O2 + 6H2O light

(reactants) (products)

Function: Chemical energy

Storage for cell use

CELLULAR RESPIRATIONCellular Respiration occurs in light simultaneously with photosynthesis. It occurs in the cytoplasm and mitochondria.

It is the reverse reaction of photosynthesis.

Function = chemical energy release

C6H12O6 + 6O2 + 6H2O 6CO2 + 12H2O+

chemical energy

(reactants) (products)

HUMAN IMPACTS TO CARBON CYCLE

• 1. Forest and brush removal has left less vegetation to absorb CO2 through photosynthesis.

• 2. Burning fossil fuels and wood produces CO2 (greenhouse gas) that flows into the troposphere. Trapping of CO2 in atmosphere enhances natural greenhouse effect and may contribute to climate changes that would disrupt global food production, wildlife habitats and raise sea level by melting ice caps.

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Figure 4-30Page 79

Year

1850 1900 1950 2000 20300

2

3

4

5

6

7

8

9

10

11

12

13

14

CO

2e

mis

sio

ns

fro

m f

os

sil

fu

el

(bil

lio

n m

etr

ic t

on

s o

f c

arb

on

eq

uiv

ale

nt)

1

Highprojection

Lowprojection

IMPORTANCE OF CARBON CYCLE

CARBON IS THE BACKBONE OF LIFE!

NITROGEN CYCLE

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NO3 –

in soil

Nitrogen Fixation

by industry for agriculture

Fertilizers

Food Webs On Land

NH3, NH4+

in soil

1. Nitrificationbacteria convert NH4

+

to nitrate (NO2–)

loss by leaching

uptake by autotrophs

excretion, death,

decomposition

uptake by autotrophs

Nitrogen Fixationbacteria convert N2 to ammonia (NH3) ; this

dissolves to form ammonium (NH4

+)

loss by leaching

Ammonificationbacteria, fungi convert the

residues to NH3 , this

dissolves to form NH4+

2. Nitrificationbacteria convert NO2

- to

nitrate (NO3-)

Denitrificationby bacteria

Nitrogenous Wastes, Remains In Soil

Gaseous Nitrogen (N2)

in Atmosphere

NO2–

in soil

Figure 4-31Page 80

© 2004 Brooks/Cole – Thomson Learning

NITROGEN CYCLEMAJOR STEPS IN NITROGEN CYCLE

• 1. Nitrogen fixation by cyanobacteria or Rhizobium bacter.

• 2. Ammonification by decomposers and/or nitrogen fixing bacteria.\

• 3. Nitrification by bacteria (NO2 [toxic to plants]to NO3

[useable by plants]).4. Assimilation (used by plants) OR Denitrification by

anaerobic bacteria in waterlogged soils or bottom of lakes convert NH3 and NH4 back to NO2 and NO3 ions and then into N2 and NO2 gas to atmosphere.

HUMAN IMPACTS ON NITROGEN CYCLE

1. WORLD War II, German chemist Fritz Haber developed the Haber Process and won the Nobel Prize. He developed Commercial inorganic fertilizer in the laboratory. This was to solve global famine problems!

N2 + 3H2 2NH3

2. Emit large quantities of NOx into the atmosphere when we burn any fuel. (NO + O2 2NO). The nitric oxide then reacts in the atmosphere with oxygen and water vapor to form nitric acid (HNO3) = acid deposition. This damages and weakens trees and interferes with aquatic ecosystems. It also creates photochemical smog known as ozone near the ground.

ACID DEPOSITION

PHOTOCHEMICAL SMOG“BAD OZONE DOWN LOW”

“GOOD OZONE UP HIGH”

HUMAN IMPACTS ON NITROGEN CYCLE CONT.

• N2O gas is released into the atmosphere by anaerobic bacteria on livestock wastes and commercial fertilizers applied to the soil. These act as greenhouse gases and when N2O reaches the stratosphere it contributes to ozone (O3) depletion.

OZONE DEPLETION

HUMAN IMPACTS ON NITROGEN CYCLE

• Remove nitrogen from Earth’s crust when we mine for nitrogen-containing minerals for fertilizers (ammonium nitrate (NH4NO3).

• Deplete nitrogen from topsoil by harvesting nitrogen-rich crops (soybeans, alfalfa).

• Leach water-soluble NO3 ions from soil through irrigation.

• Remove nitrogen from topsoil when we burn grasslands and clear forests before planting crops while releasing NOx into atmosphere.

SLASH AND BURN

“SEDIMENT KILLS REEFS”

HUMAN IMPACTS ON NITROGEN CYCLE CONT.

• Cultural Eutrophication – adding of excess nutrients of NO2, NO3, and PO4, from agricultural runoff (fertilizer and animal waste), discharge of municpal sewage, and deposition of nitrogen compounds from the atmosphere.

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Figure 4-32Page 811920 1940 1960 1980 2000

Glo

bal

nit

rog

en (

N)

fixa

tio

n(t

rilli

on

gra

ms)

0

50

100

150

200

Year

Nitrogen fixation by natural processes

IMPORTANCE OF NITROGEN CYCLE

Organisms use nitrogen to make vital organic compounds such as amino acids, proteins, DNA, and RNA.

In both terrestrial and aquatic ecosystems, nitrogen is typically in short supply and limits the rate of primary production = LIMITING FACTOR!

PHOSPHOROUS CYCLE

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GUANO

FERTILIZER

ROCKS

LAND FOOD WEBS

DISSOLVED IN OCEAN

WATER

MARINE FOOD WEBS

MARINE SEDIMENTS

weathering

agriculture

uptake by autotrophs

death, decomposition

sedimentation settling out weathering

leaching, runoff DISSOLVED IN SOIL WATER,

LAKES, RIVERS

uptake by autotrophs

death, decomposition

miningmining

excretionexcretion

Figure 4-33Page 82

uplifting over geologic time

HUMAN IMPACTS TO PHOSPHOROUS CYCLE

1. Humans mine LARGE quantities of phosphate rock to use in commercial fertilizers and detergents. Phosphorous is NOT found as a gas, only as a solid in the earth’s crust. It takes millions to hundreds of millions of years to replenish.

2. Phosphorous is held in the tissue of the trees and vegetation, not in the soil and as we deforest the land, we remove the ability for phosphorous to replenish globally in ecosystems.

3. Cultural eutrophication – ad excess phosphate to aquatic ecosystems in runoff of animal wastes from livestock feedlots, runoff of commercial phosphate fertilizers fro cropland, and discharge of municipal sewage.

CULTURAL EUTROPHICATION

IMPORTANCE OF PHOSPHOROUS CYCLE

• 1.Phosphorous is an essential nutrient of both plants and animals.

• 2. It is part of DNA molecules which carry genetic information.

• 3. It is part of ATP and ADP) that store chemical energy for use by organisms in cellular respiration.

• 4. Forms phospholipids in cell membranes of plants and animal cells.

• 5. Forms bones, teeth, and shells of animals as calcium phosphate compounds.

SULFUR CYCLE

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Figure 4-34Page 83

Sulfur

Hydrogen sulfide

Sulfate salts

Plants

Acidic fog and precipitation

Ammonium sulfate

Animals

Decaying matterMetallic

sulfide deposits

Ocean

Dimethyl sulfide

Sulfur dioxide Hydrogen sulfide

Sulfur trioxide Sulfuric acidWater

Ammonia

Oxygen

Volcano

Industries

HUMAN IMPACTS TO SULFUR CYCLE

Approximately 1/3 of all sulfur emitted into atmosphere comes from human activities.

• 1. Burning sulfur containing coal and oil to produce electric power (SOx = acid deposition).

• 2. Refining petroleum – (SOx emissions)• 3. Smelting to convert sulfur compounds of

metallic minerals into free metals (Cu, Pb, Zn)• 4. Industrial processing.

IMPORTANCE OF SULFUR CYCLE

1. Sulfur is a component of most proteins and some vitamins.

2. Sulfate ions (SO4 2- ) dissolved in water are common in plant tissue. They are part of sulfur-containing amino acids that are the building blocks for proteins.

3. Sulfur bonds give the three dimensional structure of amino acids.

4. Many animals, including humans, depend on plants for sulfur-containing amino acids.

ROCK CYCLE

HUMAN IMPACTS ON THE ROCK CYCLE

• 1. Humans are excavating minerals and removing rock material. It takes millions of years for rock to form.

• 2. Humans remove sediments for building materials. This removes sediments that may form sedimentary rocks in the future.

• 3. Humans are filling in wetlands (peatlands), area that will form future coal beds.

HOW MANY MORE COWS CAN THE EARTH SUPPORT?