Chapter 23: Biogeochemical Cycles Flashcards
1
Q
Biogeochemical cycles?
A
this is how nutrients flow back and forth from living to nonliving components of the ecosystem
- bio = living
- geo= rocks and soil
- chemicals = reactions involved
2
Q
What are important components of biogeochemical cycles?
A
- green plants, decomposers, air and water
3
Q
What are the two source types of biogeochemical cycles?
A
- Gaseous - reservoir atmosphere and oceans
- Sedimentary cycles - reservoir soil, rocks and minerals
* *both are tied to the water cycle medium which moves elements and other materials
4
Q
What are the nutrient inputs?
A
- from atmosphere for gaseous cycle or by weathering of rocks and minerals for sedimentary cycles
5
Q
What are the atmospheric inputs?
A
- wetfall nutrients brought by precipitation (like rain, fog and precipitation etc)
- dryfall nutrients brought by airborne particles and aerosols
6
Q
What are the gaseous outputs aka loss of nutrients?
A
- in gaseous form (CO2 from respiration)
- As organic matter e.g. carried by surface flow into streams, transferred by herbivores
- leaching of nutrients from soils
- harvesting and fire
7
Q
What are the three components of biogeochemical cycles?
A
- inputs, internal cycling and outputs
8
Q
Describe a generalized biogeochemical cycle of an ecosystem!
A
- NPP
- internal cycling:
- litter fall –> dead organic matter(output) –> decomposition/mineralization –> soil nutrients (output) -(input from the weathering of rocks and minerals) –> plant uptake —> incorporation into plan tissues —> atmospheric input —> NPP
- *loses: rain, run off, erosion
9
Q
Carbon Cycle:
-is carbon and energy flow separable?
A
- nope they are inseparable
10
Q
Carbon Cycle:
- source of all carbon is???
A
- CO2
11
Q
Carbon Cycle:
- PS draws CO2 from???
A
- air and water and converts it into organic material
12
Q
Carbon Cycle:
- where does carbon from PS pass on to from plants?
A
- passed to herbivores and carnivores and then is released as CO2 by respiration
13
Q
Carbon Cycle:
- dead organic material?
A
- it is decomposed
- decomposers release CO2 to atmosphere through respiration
14
Q
Carbon Cycle:
- carbon sinks?
A
- peat, coal, oil, gas
15
Q
Carbon Cycle:
- carbon sources?
A
- respiration and photosynthesis
- diffusion from aquatic environments!
16
Q
Variation in Carbon cycling:
- Net ecosystem productivity?
A
- difference between carbon uptake in PS and carbon loss due to autotrophic and heterotrophic respiration
17
Q
Variation in Carbon cycling:
- rate of carbon cycling depends on?
A
- rates of primary productivity and decomposition. These are dependent on temperature and precipitation
18
Q
Variation in Carbon cycling:
- Daily cycles?
A
- no PS at night, therefore higher CO2
19
Q
Variation in Carbon cycling:
- Seasonal fluctuation?
A
- more PS and lower CO2 during growing season
20
Q
Variations in atmospheric CO2 during a typical year in Barrow, Alaska?
A
- lower in the summer time, higher in winter bc PS
- it builds up in the atmosphere bc there is no PS to bring it down cause it is too dark (winter)
- seasonally Co2 builds up
21
Q
Global Carbon Cycle:
- most carbon on earth is where?
A
- buried in sedimentary rocks and not involved in cycle (sink)
22
Q
Global Carbon Cycle:
- global carbon cycle involves?
A
- atmosphere, ocean and land
23
Q
Global Carbon Cycle:
- ocean?
A
- contains a majority of active carbon pool (bicarbonate and carbonate ions )
24
Q
Global Carbon Cycle:
- how is carbon cycled around the globe?
A
- atmosphere and in ocean currents
25
Global Carbon Cycle:
| - sources and sinks of carbon?
- sources: CO2
| - sinks: sediments, rocks, fossil fuels, coral reefs
26
Order in order of greatest sink of carbon to least:
| Atmosphere, vegetation, recoverable fossil fuels, ocean, soils and dead organic matter
- Ocean > Recoverable fossil fuels > Soils and dead organic matter > Atmosphere > vegetation
27
Carbon cycling exchanges:
| - main site in ocean?
- surface water is the main site of exchange of CO2 via diffusion between the atmosphere and the water ...undersaturated it will absorb it..saturated it will release it. The ocean regulates our climate
28
Carbon cycling exchanges:
| - Ability of surface waters to take up CO2 is determined by?
- action with hydrogen ions to form carbonic acid, bicarbonate and carbonate ions
29
Carbon cycling exchanges:
| - uptake of CO2 from the atmosphere by terrestrial systems is determined by?
PS
30
Carbon cycling exchanges:
| - losses are associated with?
- respiration of autotrophs and heterotrophs, primarily microbial decomposers
31
Human Intrusions in Carbon Cycle:
| - Altered by what?
- increased CO2 from burning fossil fuels and clearing forests
32
Human Intrusions in Carbon Cycle:
| - Other gases such as methane (CH4)?
-they are increasing. Sources are ruminant animals, industrial gases, and microbial decomposition. They have doubled over last 200 years
33
Human Intrusions in Carbon Cycle:
| - these intrusions have the potential to alter what?
- global energy balance and global climate
34
Nitrogen Cycle:
| - essential constituent of?
- amino acids, nucleic acids, chlorophyll and hemoglobin
35
Nitrogen Cycle:
| - can plants take up N2 gas?
- hmmm better not
- they can take up ammonium NH4 + and nitrate NO3 - but not N2 gas (which makes up 80% of the atmosphere)
aka nitrogen is not readily useable! even though it is readily available
36
Nitrogen Cycle:
| - what are the two ways nitrogen enters ecosystems?
1. Atmospheric deposition
2. Nitrogen fixation by high energy ex lightning
ALSO biological fixation (90%) by symbiotic bacteria living in association with plants, free living bacteria and cyanobacteria.
37
Nitrogen Cycle:
| - overview?
- N2 ---> atmospheric deposition, ligtning fixation(breaks the bonds in N2 due to high energy blow) , free living N-fixing bacteria and symbiotic N-fixing bacteria--> inorganic nitrogen (NH4+ and NO3-)
- dead organic matter --> decomposition mineralization --> inorganic nitrogen (NH4 and NO3)
- inorganic nitrogen is uptake by plants
- Aquatic: dead organic material --> decomp mineralization --> inorganic nitrogen which can pool there OR go back up to atmosphere
38
Nitrogen Cycle:
| Bacterial processes ?(3)
- Ammonificaiton
- Nitrificaiton
- Denitrificaiton
39
Nitrogen Cycle:
Bacterial processes:
- Ammonification ?
- decomposers break down amino acids in dead material to release energy to form ammonia (useable N)
40
Nitrogen Cycle:
Bacterial processes
- Nitrification?
- ammonia is oxidized to nitrite (NO2-) and then to nitrate (NO3) by two groups of aerobic bacteria
41
Nitrogen Cycle:
Bacterial processes
-Denitrificaiton?
- under anaerobic ocnditions, bacteria turn nitrate into gaseous nitrogen. Common in wetlands and sediments in aquatic systems
42
Global nitrogen cycle:
| - where is a lot of nitrogen kept?
- ocean > land plants
43
Human emissions of nitrogen:
| -have humans altered global nitrogen cycle?
- yep
44
Human emissions of nitrogen:
| - human sources of nitrogen?
- agriculture (fertilizers), industry and automobiles (adding nitrous oxide to atmosphere)
45
Human emissions of nitrogen:
| - issues?
- increased deposition of nitrogen benefits nitrogen-limited ecosystems but can cause problems if too much is added
- say a river passes through that once nitrogen lacking environment and it passes through a city it will et N from this BU Usually it is too much which can be bad and cause blooms etc ..need a happy middle
46
Human effects on nitrogen:
| -Agricultural activities and human pop growth?
- fertilizer use and human population growth in costal areas has increased N inputs to rivers and estuaries
- scientists have tried to document the effects of humans on N cycling
47
Human effects on nitrogen:
| - Nitrogen loading ?
- this is a problem in rivers and coastal waters. Results in eutrophication which can lead to massive algal growth, oxygen depletion and fish kills
48
Human effects on nitrogen:
| - relationship between human pop and nitrogen concentration?
- positive correlation
| - export of nitrate fro river systems worldwide as a function of human population in watershed.
49
Phosphorus Cycle:
| - phosphorus forms part of?
- ATP, RNA, DNA and phospholipid molecules
50
Phosphorus Cycle:
| - is there a significant atmospheric reservoir?
- nope
| - phosphorus is transported form land to sea and does not return to land
51
Phosphorus Cycle:
| - main reservoirs?
- rock and natural phosphate deposits
52
Phosphorus Cycle:
| - is it naturally abundant?
- nope it is scarce under natural conditions
| * *limiting factor
53
Phosphorus Cycle:
| - Terrestrial systems ?
- it passes through plants and the grazing food chain and is cycled back to soil and water by excretion and decomposition
54
What are the three states of phosphorus in aquatic systems?
1. Particulate organic phosphorus: used by bacteria. They may be consumed by microbial consumers. Deposited in sediments
2. Dissolved organic phosphates taken up quickly by phytoplankton and passed to zooplankton and detritus feeders. Returned t cycle by excretion
3. Inorganic phosphates: secreted by zooplankton and taken up by phytoplankton
55
The phosphorus cycle in aquatic and terrestrial ecosystems:
| - sinks?
- sediments in ocean > Soils >oceans >minable rock > land plants
* * no sig atmospheric component. Some phosphates are deposited in sediments and can be locked up for long periods.
56
Oxygen Cycle:
| -major source?
- O2 in atmosphere
57
Oxygen Cycle:
| - oxygen comes form break up of?
- water vapour into hydrogen and oxygen in presence of sunlight (hydrogen escapes into space)
58
Oxygen Cycle:
| - oxygen is also produced by?
- PS by green plants and consumed by plants and animals
59
Oxygen Cycle:
| - when is oxygen limiting?
- in anaerobic areas!
| - in most terrestrial systems it is NOT limiting
60
Oxygen Cycle:
| - oxygen is very/not very reactive
- very reactive - largely biological
61
Oxygen Cycle:
| - constituent of __ and __
- CO2 and water
62
Oxygen Cycle:
| - reacts with what to form oxides?
- nitrogen, iron and other minerals
63
Oxygen Cycle:
| - involved the oxidation of?
- carbohydrates in the process of respiration
64
Oxygen Cycle:
| - atmospheric pool of oxygen?
- balance between production in PS and consumption in R
65
Oxygen Cycle:
| -sink?Source?
- crust of the earth
| - atmosphere, weathering of sediments , NPP
66
Ozone:
| - part of the atmospheric oxygen is reduced to ?
- ozone(O3) by high energy UV radiation
67
Ozone:
| - in the stratosphere?
- shields planet from UV radiation. It is diminished by its reaction with human caused pollutants (CFCs, CH4, ClO)
68
Ozone:
| - it is close to the ground and it is a damaging?
- pollutant that cuts visibility, irritates eyes and respiratory systems and injures or kills plants
69
Ozone:
| - ground level ozone is caused by?
- union of nitrogen oxides with oxygen in the presence of sunlight resulting in smog
70
Linkage of biogeochemical cycles??
- cycled nutrients travel together since they are components of living organisms and organic matter
- stoichiometric relationship among elements involved in carbon uptake and plant growth have important influence on cycling of nutrients
- limitation of one nutrient can affect the cycling of others
