1

Nutrient Cycles

• The magic of water• What is a Nutrient?• The Carbon cycle• The Nitrogen cycle• The Phosphorus cycle• The Sulfur cycle

2

The Magic of Water

• Life is watery!– 60-70% by weight of living organisms

• Makes possible chemical reactions necessary for life

• Promotes neutrality

33

Polar

44CS Fig. 3.4

Extra H+

Extra OH-

H+ + OH- = H2O

55

Mostdense

Leastdense

6

The Magic of Water

• Life is watery!• Makes possible chemical reactions

necessary for life• Promotes neutrality • Sticks together• Holds heat• Large liquid temperature range• Ice Floats!• Evaporation provides cooling mechanism for organisms –

Did you remember your deodorant today?

Polarity

7

What are Nutrients?

• Elements used as building blocks in organic compounds needed to build living cells

• C. HOPKINS

More basic than vitamins!These are the things vitaminsare made of

88

C

H

O

99

Similar toCS Fig. 3.12

1010

CS Fig. 3.13

11

Energy transfer in sample ecosystem

Fig. 3.16

12

Biomass (with nutrients) transfer

Fig. 3.17

13

Fig. 6.2

Biogeochemical Cycles = Natural + Anthropogenic

ANTHROPOGENIC = HUMAN ORIGIN

1414

ATMO-SPHERE

BIOTA

SHORT TERM

1515

CS Fig. 3.15

Crust

Atmos-phere

Biota

Years to Millenia

Millions to100’s ofMillions

CS Fig. 3.20

LONG-TERM

Ocean

16

Carbon Cycle (petagrams = 1015 grams)

Anthropogenic sources = 6.4 – 7.4 Natural sources = 207 Natural removals = 210

Similar to CS Fig. 3.20

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Nitrogen

• Main reservoir is N2 in atmosphere– Cannot be used directly by

plants• Necessary to build amino acids,

peptides, proteins• DNA!

1818

ATMOSPHERE

BIOTA

!

19

Nitrogen made available for Life

• N2 -> NO2- -> NO3

- -> NH4+ -> Peptides and

Proteins

Or in words:

• Gas – Nitrite – Nitrate – ammonium – organic molecules

20

Case Study: Why trees need salmon; pg 52

• Bears feasting on salmon leave about half of carcass in woods– Scavengers and bears deposit up to 120 kg of N/hectare

• Similar to fertilizer quantities added to forest plantations

• Nitrogen important nutrient for trees– In good salmon years, rainforest trees grow up to three

times as fast• Forest ecosystem needs stream ecosystem and stream

ecosystem needs forest ecosystems– Implications for salmon management? Most stocks

down 90% and some gone

21

Nitrogen Cycle (teragrams = 1012 grams)

Eutrophication =The addition ofexcess nutrientsto natural waters

Natural = 196 - 733Anthropogenic = 170 - 445

Similar to CS Fig. 3.21

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Phosphorus

• P necessary for – Nucleic acids– Cell membranes– Energy-transfer reactions– Bones– Teeth

• Source: Minerals (soil)

2323

CRUST

BIOTA

24

CRUST

BIOTA

OCEAN

NATURAL CYCLE

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CS Fig. 3.23

Phosphorus laid downas fertilizer more thanwhat is delivered throughErosion!!

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Island of Nauru after mining for phosphorus

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Sulfur

• S important for proteins

• Source: Minerals (soil)

28

Sulfur Cycle in 1012 moles

Anthropogenic = Significant!Causes Acid Rain

Similar to CS Fig. 3.24

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The End.

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