Lec 26 (Nutrient cycle part 1)

Question 1

Nutrient Cycling?

Answer 1

Whereas energy flows through ecosystems, nutrients cycle.

Flow = One-way trip (energy)
Cycle = Continuously recycled (nutrients)

Question 2

Reservoirs?

Nutrients?

Answer 2

-Stores of water or nutrients in a cycle.

-Elements that are required for the
development, maintenance, and reproduction of
organisms.

Question 3

Macro vs. Micro Nutrients

Answer 3

Macronutrients: essential elements required in
large concentrations in an organism.

Examples: carbon, hydrogen, oxygen, nitrogen,
phosphorus

Micronutrients: essential elements required
only in small concentrations in an organism

Examples: iron, magnesium, iodine, selenium, zinc

Question 4

Facts About Phosphorus

Answer 4

• Essential to energetics, genetics and structure
of living systems.
– Is the main component of ATP, RNA, DNA, and
phospholipid molecules. Kinda important
• Not very abundant in the biosphere

• Does not have an atmosphere reservoir

• Can be a limiting factor for aquatic primary
production, not usually for terrestrial primary
production

Question 5

Cycle units for phosphorus?

Answer 5

Reservoir/Pool = 1012 g of nutrient

Fluxes = 1012 g of nutrient per year

Question 6

The Phosphorus Cycle?

Answer 6

• Plants take up phosphate ions from soil or water and
incorporate them directly into tissue

• Animals gain phosphate by eating these tissues, or
from the tissues of other organisms

• Animals eliminate excess phosphorus through urine

Question 7

The largest pool of phosphorus is?

Answer 7

In marine sediment

Question 8

Facts About Nitrogen?

Answer 8

• Important to structure and functioning of
organisms.

• May limit rates of primary production in
terrestrial and marine systems.

• One of the biggest reservoirs is the

atmosphere (Earth’s atmosphere = 78% N)
• Microbes play a BIG role in the nitrogen cycle

• Its cycle is way more complicated than
phosphorus’

Question 9

Forms of N….?

Answer 9

• Ammonia: NH3
• Ammonium: NH4+
• Nitrite: NO2-
• Nitrate: NO3-
• Nitrogen gas: N2
• Nitric oxide: NO

Question 10

The important forms of nitrogen are?

Answer 10

Nitrate NO3 and Ammonia are the forms organisms take in nitrogen

Nitrogen gas N2 is the most common form nitrogen is in

Question 11

-What are the Five Transformations of N?

Answer 11

1. Nitrogen fixation:
2. Immobilization
3. Mineralization (ammonification)
4. Nitrification
5. denitrification

Question 12

-What is Nitrogen fixation?

Answer 12

-the process of converting
atmospheric nitrogen into forms primary producers
can use

Question 13

Immobilization?

Answer 13

the conversion of mineral forms of
nitrogen (ex. ammonia and nitrate) into organic
forms (ex. proteins).

Question 14

Mineralization (ammonification)?

Answer 14

the conversion of
organic forms of nitrogen (ex. proteins) into mineral
forms (ex. ammonia and nitrate).

Question 15

Nitrification?

Answer 15

the conversion of ammonium(NH4+) to nitrite (NO2), and then nitrite (NO2) to nitrate (NO3-)

Question 16

Denitrification?

Answer 16

the process of converting nitrate (NO3-) into nitrogen gas (N2)

Question 17

The biggest reservoir of N is the?

Answer 17

atmosphere (as N2 gas). over land and ocean

Question 18

Explain the nitrogen cycle. (Fixation)

Answer 18

Nitrogen can be fixed, through nitrogen fixation, by certain prokaryotes. It also can be fixed by lightning!

During nitrogen fixation, N2 gas is reduced to ammonia, NH3… N2 + 8 H+ → 2 NH3 + H2

Question 19

Explain the nitrogen cycle. (Immobilization)

Answer 19

• After fixation, nitrogen it is available to primary producers and can be immobilized (assimilated into
their tissue).

• Consumers can gain nitrogen by eating
these primary producers or other organisms.

• Once an organism dies, nitrogen is released from its
tissues by fungi and bacteria during decomposition.

Question 20

Explain the nitrogen cycle. (mineralization)

Answer 20

Nitrogen released through mineralization, also called
ammonification. During this process the organic nitrogen is converted into ammonium NH4+

This ammonium can then be converted into
nitrate through nitrification (a two-step process)

Question 21

Explain the nitrogen cycle. (denitrification)

Answer 21

Nitrogen re-enters the atmosphere
reservoir through denitrification, when denitrifying
bacteria convert nitrate into N2 gas

Question 22

Facts About Carbon

Answer 22

It makes organic molecules organic

We humans are messing up the balances in the
carbon cycles, thus are creating global climate
change

Question 23

Explain the Carbon cycle.

Answer 23

• Some of the big carbon reservoirs are the atmosphere, terrestrial soils, all organisms, and the oceans.

• Carbon moves between organisms and the
atmosphere through respiration and photosynthesis.

• Respiration moves carbon to the atmosphere
Photosynthesis removes carbon from the atmosphere

Question 24

We humans are messing up the balances in the carbon

cycles, thus are creating global climate change… How?

Answer 24

Burning:

• Fossil fuels
• Vegetation
• Peat

Question 25

The largest actively cycled nitrogen occurs?

-Human activity is a substantial source of nitrogen in the atmosphere. True or False

Answer 25

In the ocean

True

Question 26

-What contains the largest amount of carbon?

Answer 26

Carbonate rocks

Question 27

In_____ ecosystems CO2 has to be dissolved into
the water before it is available to primary
producers.

Answer 27

aquatic

Question 28

When dissolved in water, CO2 turns into?

Answer 28

two compounds (in equilibrium):

• Bicarbonate HCO 3-
• Carbonate CO3 2-

CO3 2- can combine with dissolved calcium and
precipitate out as calcium carbonate CaCO3

Question 29

Decomposition?

Answer 29

the breakdown of organic matter accompanied by the release of CO2

Question 30

Factors that influence decomposition?

Answer 30

– Temperature
– Moisture
– Chemical composition of decaying matter
– Chemical composition of the environment

Question 31

Comparing Decomposition Rates:

Precipitation…

Answer 31

The more precipitation you have the more decomposition you will have.

Question 32

Comparing Decomposition Rate:

Leaf Characteristics

Answer 32

-Decomposition rates dependent on %lignin: %N ratio

Higher the ratio of lignin to N, the longer it took to decompose

Also, the more N in the soil (North Carolina), the
higher the decomposition rate

Question 33

Comparing Decomposition Rates:

Temperature and Moisture (AET)

Answer 33

-In warmer and moisture climates we see more decomposition

Question 34

Decomposition in Aquatic Ecosystems?

Answer 34

Influenced by the same three factors:
– Temperature
– Nutrient content of
the decaying matter
– Nutrient content of
the water