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GLGY202 Applications of Geoscience > The Earth System > Flashcards

The Earth System Flashcards

1
Q

The Earth system is made up of four main “spheres”:

A
  1. Geosphere
  2. Hydrosphere
  3. Atmosphere
  4. Biosphere
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2
Q

Biogeochemical Cycles

A
  • Matter is neither created nor destroyed, it is recycled
  • The ingredients for life (CHNOPS) can be stored in one sphere for a period of time, but also naturally move from one sphere to another through chemical reactions or phase changes
  • Movements between spheres = biogeochemical cycles

The water cycle, carbon cycle, and nitrogen cycle allow Earth to sustain life.

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3
Q

The Hydrologic Cycle

A

Transfer of water among the spheres

  • Is not smooth and continuous, but a stop and go process
  • Water is temporarily stored in one of several major reservoirs (atmosphere, vegetation, lakes, river, groundwater, oceans) before it is transferred to another
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4
Q

Water moves from reservoir to reservoir through several different processes:

A
  • Evaporation
  • Precipitation
  • Runoff (surface only)
  • Infiltration (into substrate)
  • Transpiration (evaporation of water from plants at leaves)
  • Groundwater flow
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5
Q

The sizes of reservoirs are variable and the rate of transfer between reservoirs depends on:

A

temperature, wind, relative humidity, etc.

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6
Q

The Carbon Cycle

A

Describes how carbon moves between the biosphere, geosphere, hydrosphere, and atmosphere

  • Carbon we have on Earth has been here since Earth formed
  • It has been recycled from one form to another over time
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7
Q

Carbon (C) is the building block of many molecules (CO2, glucose, ATP, etc.)

A
  • If a decaying organism undergoes burial, it is protected from decomposition. The carbon from it then enters the geosphere instead of the atmosphere or biosphere. May turn into coal in a very long time with compaction.
  • Best way to return carbon from coal = combustion of fossil fuels into atmosphere
  • CO2 is also dissolved in the oceans, which can be used by organisms to construct skeletons/shells. Shells may dissolve and carbon will be returned to ocean or they can pile up on ocean floor and become limestone with burial and compaction which enters the geosphere
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8
Q

Carbon is temporarily stored in different reservoirs within each sphere and transferred to

A

other reservoirs through various processes

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9
Q

Just like water in the hydrologic cycle, the carbon cycle is a

A

stop and go process. Carbon is temporarily stored in several major reservoirs and the reservoirs vary in size.

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10
Q

Carbon reservoirs (from smallest to largest):

A
  • Atmosphere
  • Vegetation
  • Soils
  • Surface of the ocean
  • Deep ocean
  • Rocks and sediments
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11
Q

Which rock type stores most of the world’s carbon?

A

Carbonates (limestones, etc.) have more than coal

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12
Q

Carbon may form organic or inorganic compounds:

A

Organic carbon: hydrocarbons, often in long chains that are mostly made in living things:
- Proteins, carbohydrates, fats, DNA
Inorganic carbon: carbon not bonded to hydrogen; some are made by living things:
- CaCO3 (calcium carbonate)
- CO2

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13
Q

Which rock type is made up of organic carbon? Inorganic?

A
  • Coal = organic carbon

- Carbonate rocks = inorganic

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14
Q

The Carbon Cycle allows organic carbon to become

A

inorganic carbon and vice versa. This allows carbon to be exchanged freely among all reservoirs.

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15
Q

Small surface reservoirs can exchange all of their C with one another in a few years, whereas deep ocean is

A

partially isolated by temperature differences; exchanges with surface ocean/atmosphere in >100 years.
C buried in seds and rock takes >1000 years to fully exchange.

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16
Q

Large fluxes are ~balanced year to year, which means that

A

C into a reservoir = C out of that reservoir

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17
Q

Processes leading to an increase in carbon in atmosphere (positive number):

A

volcanoes, fossil fuel burning, deforestation

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18
Q

Processes leading to a reduction in carbon in atmosphere (neg number):

A

carbonate rock formation, weathering

19
Q

Scientific Models:

A

physical, mathematical, or conceptual representations of a system of ideas, events, or processes
- Are not reality, they are simplified versions of reality

20
Q

Residence time

A

The length of time carbon stays in any given reservoir

21
Q

the surface ocean is in direct contact with the atmosphere and exchanges carbon:

A

easily with the atmosphere. The deep ocean partially isolated by temperature differences; exchanges C with surface ocean/atmosphere in >100 years.

22
Q

Carbon sinks

A

reservoirs that accumulate and store carbon for a long period of time

23
Q

Carbonate rocks and the deep ocean are large reservoirs with long:

A

residence time and low fluxes. This means they are able to store carbon for long periods of time and are excellent carbon sinks.

24
Q

Other Cycles

A

Although the processes, fluxes, and residence times vary, the other ingredients for life (S and P) also cycle through the Earth system

25
Q

Rock Cycle

A

Large scale process that describes how one rock type becomes another when it enters a new tectonic environment

  • Weathering and volcanism are two major processes that allow elements to exchange b/w the geosphere, hydrosphere, and atmosphere
  • The rock cycle encompasses many biogeochemical cycles
26
Q

Volcanism

A

Volcanic eruption allow gases (water carbon dioxide, sulfur dioxide) to move from geosphere to atmosphere

27
Q

What is weathering?

A
  • Breaking down rocks
  • Earth materials are weather through: physical weathering and chemical weathering
  • Earth materials are eroded by: wind, running water, waves, glaciers, groundwater, gravity
28
Q

Physical weathering:

A

Mechanical breakdown of rocks into smaller pieces

  • Frost wedging: water freezes in joints/cracks and expands
  • Root wedging: roots push grains and rock fragments apart
  • Ventifaction: blowing wind can sandblast rocks
  • Thermal expansion: changes in temperature cause rocks to expand and contract
  • Salt crystal growth: crystals grow in cracks and push grains and rock fragments apart
  • Bioturbation: burrowing animals loosen aerate sediments, includes root wedging
29
Q

Rates of physical weathering depend on:

A
  1. Local climatic/environment conditions
  2. Rock type, texture, structures
  3. Biological activity
  4. Time
30
Q

Local climatic/environment conditions

A
  • Seasonal temperature changes
  • Seasonal fires
  • Aridity (salt growth)
  • Strong, persistent winds
  • Water availability
31
Q

Rock type, texture, structures

A

Some rock types are less resistant to weathering than others

32
Q

Biological Activity

A

Burrowing animals and plants break rocks and churn sediments

33
Q

Time

A

The longer a rock is exposed, the more it will be weathered

34
Q

Chemical weathering:

A

alters rocks and minerals at Earth’s surface as they react with water, oxygen, and carbon dioxide. This produces new minerals, dissolved elements, and compounds.

35
Q

4 main chemical processes lead to chemical weathering (not a complete list of course):

A
  1. Dissolution/Solution
  2. Oxidation
  3. Hydration
  4. Hydrolysis
36
Q

Dissolution/Solution

A

Dissolving a mineral in water or a weak acid

  • Acid rain/surface water produced when CO2, SO2, or NOx combine with water = H2O + CO2 -> H2CO3
  • Acid dissolves carbonate rocks, creating solution of calcium and bicarbonate ions HCO3-
  • Results in chemical weathering at surface and underground cave systems called karst
37
Q

Karst Topography

A
  • Remember: karsts extend into the landscape

- Loss of structural integrity and then it will eventually collapse

38
Q

Speleothems

A
  • Travertine: carbonate rock precipitated directly from solution
  • Forms dripstones: Stalactites (from the ceiling down) and stalagmites (from the ground up)
  • Although more resistant to chemical weathering, silicates are also subject to dissolution. Both granite obelisks are believed to have been carved 3.5k years ago.
39
Q

What caused the difference in weathering?

A 
Climate = NYC more moisture vs. Egypt super dry
Pollution = NYC super high pollution means more CO2 and sulfur so it favours production of acid rain which weathers it
40
Q

Oxidation

A

Occurs when minerals react with oxygen

  • Leads to rusting and produces iron-oxide minerals like hematite
  • Pyroxene, amphibole, magnetite, pyrite, and olivine are most susceptible to oxidation because they are high in iron -> mafic rocks are more likely to be weathered bc of high mineral content that’s susceptible
41
Q

Hydration

A

Occurs when minerals combine with water, changing their structures
- Can be undone with heating, but heating can induce chemical and physical weathering

42
Q

Hydrolysis

A

Complex weathering reaction that produces clays, an important mineral in soils
- The main chemical reaction that removes carbon from the atmosphere

43
Q

Hydrolysis Reaction

A
  • Commonly, potassium feldspar reacts with H+ and OH- ions in water to produce clay minerals, potassium and silica in solution
  • When silicate rocks react with carbonic acid, a mixture of clay and dissolved ions are produced. The dissolved ions are carried by rivers to oceans, where they become incorporated into the shells of organisms
  • If the shells accumulate on the sea floor and turn into stone, they enter into long-term carbon storage (VERY SLOW process)
44
Q

Rate of chemical weathering controlled by:

A
  • Surface environment (rocks under water or not)
  • Exposed surface area (more surface area results in more chemical weathering)
  • Grain size (related to surface area)
  • Climate (more weathering in warm, humid climates)
  • Nature of rocks and minerals (some rocks and minerals are more susceptible to weathering than others: granite vs. limestone, quartz vs. feldspar)

GLGY202 Applications of Geoscience (9 decks)

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