Movement of elements

Question 1

Nutrients

Answer 1

elements required by organisms for metabolism and growth

Question 2

Biogeochemistry

Answer 2

physical, chemical, biological factors that influence the movements and transformation of elements

Question 3

Assimilation

Answer 3

inorganic → organic

Question 4

Dissimilation

Answer 4

organic → inorganic

Question 5

Two abiotic sources of nutrients

Answer 5

• Minerals in rocks
  – Potassium, calcium, magnesium, phosphorus
  – Weathering
• Gases in the atmosphere
  – 78% N2, 21% O2, 0.9% argon, 0.039% CO2
  – Atmospheric deposition
  – Chemical fixation

Question 6

Mechanical weathering

Answer 6

physical alteration of rocks; freezing, wetting/rewetting, otherwise “broken apart”

Question 7

Chemical weathering

Answer 7

minerals subjected to chemical processes (e.g. oxidation)

Question 8

Atmospheric deposition

Answer 8

precipitation, particles, aerosols, and gases move from the atmosphere to the earth’s surface

Question 9

Hydrologic cycle

Answer 9

The movement of water through ecosystems and atmosphere;
driven by evaporation, transpiration, and precipitation

Question 10

Detritivores

Answer 10

physically break organic matter into smaller pieces

Question 11

Decomposers

Answer 11

break dead organic matter into inorganic elements – process called mineralization (a form of dissimilation)

Question 12

Dry environments→

Answer 12

slow decomposition rates

Question 13

Moist forests→

Answer 13

relatively high decomposition rates

Question 14

Water-logged environments
(bogs, swamps, etc.) →

Answer 14

slow

Question 15

more nitrogen →

Answer 15

faster decomposition

Question 16

Nitrogen fixation

Answer 16

Converts atmospheric nitrogen into forms
producers can use, N2 → NH3→ NH4 + or NO3-, requires energy

Question 17

Biotic fixation

Answer 17

free-living and mutualistic bacteria (e.g. rhizobia, frankia)

Question 18

Abiotic fixation

Answer 18

lightning, wildfires, fossil fuel combustion, fertilizer production
– Fertilizer production: Haber-Bosch process, energy from fossil fuels

Question 19

Nitrification

Answer 19

conversion of ammonium to nitrate by bacteria
– Nitrates more easily used by plants

Question 20

Assimilation of nitrogen

Answer 20

incorporation of NH4+ or NO3– into organism tissues

Question 21

Ammonification

Answer 21

nitrogen in organic matter (feces, dead organisms) converted to ammonia or ammonium
– fungal and bacterial decomposers
– can then be converted back into nitrates (nitrification)

Question 22

Denitrification

Answer 22

Nitrates are water-soluble and are leached from surface
* nitrates converted into nitrogen gas (N2) by bacteria under anaerobic conditions
1. NO3- to NO
2. NO to N2
* Returns nitrogen to atmosphere

Question 23

Phosphorus (P) is an essential element
because…

Answer 23

• Needed for bones, scales, teeth, DNA, RNA, ATP, phospholipids in the cell membrane
• Moves as phosphate: PO4 3-
• Often limits productivity
• Excessive phosphorus can cause toxic plant/algae growth

Question 24

Phosphorous plays a role in —– and —– systems

Answer 24

Terrestrial and Aquatic systems

Question 25

Atmospheric deposition

Answer 25

Phosphorous moves through the atmosphere as dust
- Sahara provides phosphorous to the Amazon

Question 26

How do humans alter the hydrologic cycle?

Answer 26

Increase run-off and decrease water in soil:
* Creation of impervious surfaces
* Removal of plant biomass
* Heavy use of ground water
* Climate change → increase evaporation, intense storms → Increased soil erosion and flooding

– Human erosion: 10-15 times faster than
nature

Question 27

Human and increased N-fixation
3 Processes?

Answer 27

– Haber Bosch process
– Crops- soybeans, alfalfa, peas
– Higher atmospheric N from gaseous emissions: fossil fuel combustion, biomass burning, sewage treatment, livestock, etc.

Question 28

Human Impacts on N Cycle

Answer 28

Export of nitrate from river systems worldwide as a function of human population in the watershed

Question 29

Human Impacts on P Cycle

Answer 29

• Use of fertilizers and detergents
• Discharge of sewage and industrial waste
• Increase in terrestrial surface erosion

Question 30

Increased run-off increases…

Answer 30

nutrient transfer to aquatic systems

Question 31

Oligotrophic

Answer 31

– Low nutrient levels (nitrogen & phosphorus)
– Low NPP
– Healthy, diverse fish & invertebrate communities

Question 32

Eutrophic

Answer 32

− Nutrient rich (nitrogen & phosphorus)
− High phytoplankton, algae abundance and turnover
− Oxygen depleted → anaerobic organisms
− Accumulation of detritus, turbid water
− Loss of diversity

Question 33

Consequences of too much Phosphorous

Answer 33

• Eutrophication
• Hypoxia creates “dead zones”
  Example: Grand Lake St. Marys