APES-Area2e-Natural_Biogeochemical_Cycles

8/4/2019 APES-Area2e-Natural_Biogeochemical_Cycles

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Area IIE: The Living World

Natural Biogeochemical Cycles


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Biogeochemical Cycles

Biogeochemical cycles: how

nutrients cycle through biotic andabiotic components of ecosystems involve soil, atmosphere, and organisms

examples: C and N cycles


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Fig. 4-28 Hydrologic cycle

Precipitation toland

Transpirationfrom plants

RunoffSurface runoff(rapid)

Evaporationfrom land Evaporation

from ocean Precipitation toocean

Ocean storage

Surfacerunoff(rapid)

Groundwater movement (slow)

Rain cloudsCondensation

Transpiration

Evaporation

Precipitation

Precipitation

Infiltration andPercolation


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4-7 Matter Cycling in Ecosystems

Water cycles chemically unchanged natural renewal of water quality human interference

1. we use of large amounts of fresh water 2. we increase runoff 3. we modify water quality 4. we are speeding the water cycle (?) by

increasing global temperatures (?)


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Water cycle


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Diffusion between

atmosphere and ocean

Carbondioxide

dissolved inocean water

Marine food websProducers, consumers,

decomposers, detritivores

Marine sediments, including

formations with fossil fuels

Combustion of fossil fuels

incorporation into

sediments

death,sedimentation

uplifting overgeologic time

sedimentation

photosynthesis

aerobicrespiration

Fig. 4-29a Carbon cycle


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Figure 4-29b Carbon cycle

photosynthesis aerobicrespirationTerrestrialrocks

Soil water(dissolvedcarbon)

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, compactionover geologic timeleaching

runoff

weathering

Combustionof fossil

fuels


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The carbon cycle is based on CO2 in

the atmosphere CO2 in atmosphere plants make organic matter through

photosynthesis autotrophs and heterotrophs use organic

matter through respiration and release CO2

if respiration exceeds photosynthesis, CO2increases: greenhouse effect human interference

1. we clear trees and plants 2. we add large amounts of CO2 to atmosphere


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Carbon cycle


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Carbon cycle


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Fig. 4-30 Human interference in C cycle

Year1850 1900 1950 2000 2030023456789

1011121314

CO

2emissionsfrom

fossilfuel

(billionmetrictons

ofcarbon

equivalent)

1

Highprojection

Low

projection


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Fig. 4-31 Nitrogen cycle

NO3

in soil

NitrogenFixation

by industry foragriculture

Fertilizers

Food WebsOn Land

NH3,NH4+in soil

1. Nitrificationbacteria convert NH4

+

tonitrate (NO2

)loss by

leaching

uptake byautotrophs

excretion,death,

decomposition

uptake byautotrophs

Nitrogen Fixationbacteria convert N2 toammonia (NH3) ; this

dissolves to form ammonium(NH4

+)

loss byleaching

Ammonificationbacteria, fungi convert the

residues to NH3, this

dissolves to form NH4+

2. Nitrification

bacteria convert NO2-to

nitrate (NO3-)

Denitrificationby bacteria

Nitrogenous Wastes,Remains In Soil

Gaseous Nitrogen (N2)

in Atmosphere

NO2

in soil

2004 Brooks/Cole Thomson Learning


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The nitrogen cycle depends largely

on bacteria N2 NH3 NO2

- and NO3-

ammonia nitrite nitrate

human interference 1. we add NO to the air when we burn fuel

it can become NO2 and then HNO3, causingacid rain

2. we add N2O to the atmosphere indirectlythrough the action of bacteria on livestockwaste and fertilizers


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human interference, cont.

3. we release nitrogen stored in soils andplants into atmosphere by removing trees

4. we upset aquatic ecosystems by addingexcess nitrates in agricultural runoff and

sewage systems 5. remove nitrogen from topsoil when

harvesting, irrigating, or burn or cleargrasslands or crops

6. we are affecting biodiversity


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Fig. 4-32 Human interference in N cycle

1920 1940 1960 1980 2000

Globalnitrogen(N)fixation

(trilliongra

ms)

0

50

100

150

200

Year

Nitrogen fixation by natural processes


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Nitrogen cycle


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Fig. 4-33 Phosphorus cycle

GUANO

FERTILIZER

ROCKS

LANDFOODWEBS

DISSOLVEDIN OCEAN

WATER

MARINEFOODWEBS

MARINE SEDIMENTS

weathering

agriculture

uptake byautotrophs

death,decomposition

sedimentation settling out weathering

leaching, runoff DISSOLVED INSOIL WATER,

LAKES, RIVERS

uptake byautotrophs

death,decomposition

miningmining

excretionexcretion

uplifting overgeologic time


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The phosphorus cycle does not move

through the atmosphere human interference

1. we mine phosphate rock to make fertilizer

2. we reduce phosphate availability in tropicsby cutting tropical forests 3. we add phosphates to runoff and disrupt

aquatic systems


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Phosphorus cycle


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Fig. 4-34 Sulfur cycle

SulfurHydrogen

sulfide

Sulfate salts

Plants

Acidic fog and

precipitationAmmonium

sulfate

Animals

DecayingmatterMetallic

sulfidedeposits

Ocean

Dimethylsulfide

Sulfur dioxide Hydrogensulfide

Sulfur trioxide Sulfuric acidWater

AmmoniaOxygen

VolcanoIndustries

Bi h i l C l


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The sulfur cycle human interference

we add sulfur dioxide (SO2) to the atmosphereby:

1. burning coal and oil to generate electricity 2. refining oil to make gasoline and other

petroleum products 3. converting sulfur-containing ores into free

metals

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