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CVC109 Water > Nutrient Cycling > Flashcards

Nutrient Cycling Flashcards

1
Q

Define ecosystem

A

A biological community of interacting organisms and their physical environment

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2
Q

In cycles what is a source and sink

A

Source= flows out of a large store
Sink= Flows into a large store

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3
Q

What is the movement between stores called, and give examples in the water cycle

A

Flux
Rainfall, Precipitation, Atmospheric Mositure

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4
Q

What is the residence time (turnover time)

A

The total pool divided by the sum of all the inputs and outputs from the reservoir

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5
Q

Difference between 1-way and 2-way flux and what are they used to calculate

A

One Way Flux= One direction. Used to calculate the time that is needed to exhaust a pool

Two-Way= Reversible. Used to calculate half-life

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6
Q

In the carbon cycle give examples of pools

A

Atmosphere, soils, vegetation, oceans, marine biota and sediment

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7
Q

In the carbon cycle give examples of fluxes

A

Photosynthesis, plant respiration, microbial decomposition. As well as anthopogenic fossil fuel input and changing land use

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8
Q

What is carbon sequestration

A

storage of carbon in plants, soils, geologic formations, and the ocean.

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9
Q

What is the only 1-way flux in the carbon cycle

A

The anthropogenic carbon caused by fossil fuels and cement production
This is creating imbalances- the ecosystem can only deal with imbalances to a certain extent

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10
Q

What does the solubility of a gas depend on

A

Temperature
Pressure
Chemical nature of gas and liquid

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11
Q

Why does the solubility of gas depend on temperature

A
  • As temperature increases, the solubility of gases decreases.
    o This is because as temperature increases the gas molecules have more energy, so move around more and are more likely to break free
    o A significant impact of global warming, as the decreasing solubility of oxygen in water is affecting aquatic life forms
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12
Q

Why does the solubility of gas depend on pressure

A
  • Solubility is directly proportional to the pressure, at a given temperature= Henry’s Law
    Henrys Law Constant= Partial Pressure of Gas/Solubility of Gas
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13
Q

Why does the solubility of gas depend on the chemical nature of the gas and liquid

A

In a mixture of gases, each gas behaves as it the other gases are not there- each gas dissolves according to its own (partial) pressure (concentration)

Generally, gases are not very soluble in liquids, unless there is a specific chemical reaction

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14
Q

What ions do acids have

A

Acids have more H+ ions than OH- ions, but it’s a negative logarithmic relationship. So as H+ increases pH decreases

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15
Q

What should the number of H+ ions and OH- Ions add up to

A

14

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16
Q

Describe the carbonate cycle

A
  • Concentrations of gases in the atmosphere are in equilibrium with that in the seawater
  • Carbon dioxide dissolved in water undergoes a chemical reaction with water to produce carbonic acid (these an in equilibrium)
  • By acid definition carbonic acid releases H+ ions into the solution. It does this by dissociating negative bicarbonate ions with positive hydrogen ions- these hydrogen ions decrease the oceans pH
  • Bicarbonate further dissociates to form carbonate ions and hydrogen ions
  • Carbonate then interacts with calcium and magnesium, to form calcium and magnesium carbonate
  • Carbonate buffering system
17
Q

What are the implications of the changing carbonate cycle

A

Ocean Acidification

18
Q

What is causing ocean acidification and what are the issues

A

-The ocean has a pH of 8 (alkaline)
-But because there is more CO2 in the atmosphere the ocean is absorbing more
-Causing the pH to reduce- fallen by 0.1 units since industrial revolution

-Carbonate ions are an important building block of structures such as seashells- calcifying organisms
-Shellfish are dissolving in the sea water
-Effects non-calcifying organisms as well, for example a fish’s ability to detect predators

-But also as it becomes more acidic its capacity to absorb Co2 decreases
-Decreasing the oceans role in moderating climate change

19
Q

Importance of Nitrogen

A
  • Essential for proteins and nucleic acids
  • Limits ecosystem productivity (eutrophication) or agricultural productivity (fertiliser use)
  • Part of an enzyme system that regulates oxidation-reduction of organic C in tissues and of Ribulose enzyme that fix CO2 during photosynthesis
  • Involved in a lot of biochemical transformations
  • Some forms of N are toxic to ecosystems and human health
20
Q

What anthropogenic activities add nitrogen to the atmosphere

A

-Crop Production
-Dairy/Meat Production
-Fossil Fuel Use

21
Q

Key Pools in the nitrogen cycle

A
  • Atmosphere
  • Terrestrial biomass
  • Soil Organic Matter
  • Mineral N pools are small. Plant and microbial uptake are so rapid that little is even available
22
Q

N2 is present in the atmosphere but this isn’t available to plants- what needs to happen so it is

A

-N2 is not bioavailable, despite making up 78% of air
-Plants need nitrogen to be fixated in soil

-Nitrogen is converted to ammonium ions in the soil by nitrifying bacteria
-Ammonium ions are then converted to nitrate and nitrite- which is available to plants. This is done within root nodules or nitrogen fixing bacteria in the soil

23
Q

What is ammonification

A

When death and decay occurs, the dead items are converted back into ammonium ions

24
Q

What is denitrification

A

-Nitrate converted back into nitrogen in the air through nitrifying bacteria

-Natural denitrification occurs during flooding or where there is lack of aeration in the soil- soil environment anaerobic, removing nitrate from the soil

25
Q

Impacts of too much nitrogen on the environment

A
  • Freshwater resources- acidification, eutrophication
  • Coastal water resources- eutrophication
  • Atmosphere- NOx, NH3, N20 as air pollutants (global warming, ozone depletion, smog creation, acid rain)
  • Terrestrial ecosystems- Cation loss, community shifts in primary productivity and decomposition, and biodiversity losses
26
Q

What are the issues of changing forested areas to intensive crop production

A
  • Removes biomass, and uses it for human consumption
  • This prevents death and decay and prevents ammonification
  • Therefore, there is no creation of ammonium ions
  • Therefore, no generation of nitrate, which supports life
  • And therefore, artificial fertilisers are required- fertiliser cycle
27
Q

What is the pH of unpolluted rain

A

5.6

28
Q

Anthropogenic sources of acidifying pollutants- leading to acid rain

A
  • Sources of nitrogen to the atmosphere
    o Ammonia released from fertiliser and manure
    o N2O, NO, NO2 from industry, transport and agriculture
  • Sulphuric Acids
    o Fossil fuel burning- particularly industrial flue gases
29
Q

Effects of acid rain

A
  • Suggested relationship with forest decline as prevents photosynthesis and kills leaves
  • Direct acid deposition of leaves leads to lesions
  • Leeches Ca, Mg, K from leaves and needles
  • Depletion of Ca in needles affects susceptibility to freezing
30
Q

Why is the occurrence of acid rain increasing

A

-Increase in emissions of nitrogen and sulphides

-Oxidation of nitrogen and sulphides leading to the formation of nitric and sulphuric acid

-Sulphuric acid more of a problem as dissociation into more H+ ions

31
Q

Why is phosphorous important

A
  • Part of DNA and RNA structure of cellular membranes
  • Living cells also use phosphate to transport energy
  • Calcium phosphate salt assist in stiffening bones
  • Plant nutrient
  • “Non-renewable” Nutrient
32
Q

Where is phosphorous stored

A

Rocks, soil, biota, dissolved in ocean sediments

33
Q

Anthropogenic sources of phosphorous

A

Detergents, fertilisers and sewage effluent

34
Q

Issues with phosphorous

A
  • Eutrophication- simulation of algal growth
  • Both N and P required, but growth is P limited
  • Reduced water clarity, release of toxic metabolites and organic carbon
  • Disturbed oxygen balance, supersaturation vs very low levels
  • Water treatment difficulties: short filter life
  • Generation of organic C
  • Blue-green algae
35
Q

Describe the phosphorous cycle

A

-Weathering- most phosphorus found in rocks, which is extracted through weathering- eventually washed into soil

-Absorption- once in soil organisms absorb

-Decomposition- when organisms die decomposition occurs and phosphorous is returned to soil

CVC109 Water (13 decks)

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