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Environmental Science > Research methods > Flashcards

Research methods Flashcards

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1
Q
A
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2
Q

What methods can we use to research past conditions on Earth?

A

Boreholes
Ice cores
Pollen
Insects
Paleo modelling
Paleo oceans
Caves
Lakes
Coral
Fauna
Historical
Plant Macros

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3
Q

What data can we use to research the past conditions on Earth?

A

Proxy data
Direct data

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4
Q

What is Proxy data?

A

Preserved physical characteristics of the environment that can stand in for direct evidence of past climates
- stuff that is inferred from evidence

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5
Q

What is direct data?

A

Data that is gathered from an original first hand source
- stuff that is recorded

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6
Q

Give examples of proxy data

A

Animal and plant fossils
C12-C14 isotope ratio
O16-O18 isotope ratio
Mg-Ca in calcite deposits
Rock deposits
Air bubbles in ice cores

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7
Q

Give examples of direct data

A

Written accounts
Historical record (meteorological)

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8
Q

What does the strength of a record depend on?

A

The timescale (Length of time and resolution)
The geographical area
The ability to accurately record an event

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9
Q

What happens to raw proxy data?

A

Gets calibrated against modern record climate data. If there isn’t any, it gets more qualitative than quantative

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10
Q

What are ice cores? What can they show us?

A

A cylinder of glacial ice made up of layers that preserve climate evidence from the past.

  • Accumulation rate
  • air temperature
  • summer temperatures
  • atmospheric gas concentration
  • volcanic activity
  • sea ice concentration
  • atmospheric circulation
  • solar activity
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11
Q

How do ice cores show accumulation rate?

A

thickness of layer = rate of precipitation
more thick = more snow
more snow = warmer temp

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12
Q

How do ice cores show summer temperatures?

Give example

A

melt layers = layers without gas in

more melt layers = warmer summer because the water melts, dispelling gas

e.g. trends in melt layers of ice in NE Antarctic Peninsula

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13
Q

How do ice cores show us atmospheric gas concentrations?

A

bubbles in ice can be shaved, melted or crushed to release gas. Gas can then be tested

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14
Q

How can ice cores show us air temperatures?

A

Analyse the gas concentrations. More greenhouse gases = warmer because they would have insulated more.

Analyse the water isotope ratio. More O-18 than O-16 means warmer because it requires more energy to evaporate O-18 = heavier.

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15
Q

How can ice cores show us volcanic activity?

A

Layers of ash in the ice = volcanic activity

Tephra can spread a long way. If geochemically identical ice is found in two separate places, we can find the extent of the eruption

Test for acidity - more acid, more volcanic. Run electric current because acid is conductive

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16
Q

How can ice cores show us sea ice concentration?

A

Test salinity. More salinity = more sea ice because sea ice is made from frozen sea water (-1.8) rather than freshwater.

Can be used to predict extent by comparing different places.

17
Q

How can ice cores show us atmospheric circulation?

A

Aerosols carried in air currents get deposited on glaciers e.g. dust from storms.
- the more aerosols found mean better circulation because dust storms do not start in icy places

Can also be used to predict climate changes in other parts of globe - conditions such as drought needed to start the storm

18
Q

How do ice cores show us solar activity?

A

Beryllium-10 is made by Beryllium reacting with cosmic rays near surface of earth. More Beryllium-10 means more cosmic rays, means anomalies in solar radiation e.g. solar wind or Milankovitch theories of orbit. (eccentricity)

INDIRECT

19
Q

Pros of ice cores

A
  • will reliably give evidence
  • gives huge range of proxy data in a small sample
  • hundreds/thousand of years
  • relatively easy to collect/access
20
Q

Cons of ice cores

A
  • EXPENSIVE
  • demanding (-36)
  • permanent/semi permanent camps
  • drills can malfunction
  • kerosene
  • gas can diffuse
21
Q

What is radioisotope analysis?

A

Using radiation given off by C-14 to determine the movement of elements through natural systems

22
Q

How does radio isotope analysis work?

A
  • Living organisms absorb C-14 into their tissue
  • when they die, C-14 decays into other atoms
  • when they decay they release gamma rays
  • these strike RIIDs and convert it to an electrical signal
23
Q

What is radioisotope analysis used for?

A
  • what plants and animals lived where and how long ago
  • how much carbon in atmosphere when animal was alive
  • temperature ranges can be found by comparing it to the dead animals temperature preferences
  • trophic levels and food chains/webs
  • how plants and animals spread after glacial retreat
24
Q

Pros of radioisotope analysis

A
  • samples can be moved to examination site
  • gains info that cannot be gained any way else
  • dates ancient materials
  • pretty accurate
  • small samples
  • 63,000YA is a while ago
25
Q

Cons of radioisotope analysis

A
  • radioactive samples need to be shielded
  • radiation damage to humans
  • sample has to contain C-14 to be studied
  • half life = 5000 years. Some stuff e.g. rocks just too old
  • expensive
  • sample is destroyed
  • sample can be contaminated
26
Q

What is oxygen isotope analysis?

A

Method using the ratio of oxygen isotopes in a sample to gather information about past environmental conditions such as past temperatures, rainfall, and water quantity in ice sheets

O-16 and O-18 are analysed

27
Q

How does oxygen isotope analysis work?

A

The mass of O-16 and O-18 in a sample are taken and then the ratio of these masses are calculated

More O-16 means temps were cooler - it is lighter and therefore condenses last

More O-18 means temps were warmer - it is heavier and therefore evaporates last.

28
Q

Pros of oxygen isotope analysis

A
  • available anywhere that water chemistry has been preserved
  • not limited by age
  • good understanding of natural climate cycles changing over time and the human impact
  • accurate
29
Q

Cons of oxygen isotope analysis

A
  • expensive
  • complicated
  • ratios can be influenced by other factors
  • marginal seas may not represent the big picture
  • cannot be applied below CCD
30
Q

What are magnesium/calcium ratios?

A

Using the magnesium/calcium ratio in samples such as foraminifera, water and soil to determine past conditions

31
Q

How does the Mg/Ca ratio in foraminifera show past conditions?

A

Mg/Ca ratio in shells tells us about temperature.
- Warm temperatures = more Mg. Expends energy to use Mg but it’ll be okay in warm temps

32
Q

How does the Mg/Ca ratio in water show past conditions?

A

Shows alteration in water chemistry and trends can be used to predict past and future data
- ratio increased over past 10s of millions of years. Triggered changes in organisms that build massive CaCO3 reefs
- ratio identifies processes that alter the oceans physiochemical properties

33
Q

What physiochemical properties can Mg/Ca ratios influence?

Why are they important?

A
  • physical properties e.g. freezing/boiling point
  • solvation properties
  • molecular properties e.g. size/shape/volume
  • amino acid properties e.g. acidity

Allows scientists to understand a substance’s behaviour and predict hazards. How to help environment.

34
Q

How can the Mg/Ca ratios in soil show past conditions?

A
  • good soil structure has Mg/Ca ratio of 1:2
  • any less is instable, and more than 10:1 is a deficiency.

Bad because:
- poor aeration (bad gas exchange and harmful pathogens)
- bad plant growth (bad roots and mineral uptake)
- bad plant health (bacteria/viruses)
- bad crop yields

Identifying these in a sample can point to bad soil quality in the past, so we can predict condition that could have lead to it.

35
Q

How has life on earth influenced transpiration?

A
  • plants evolve and colonise land
  • transpiration returns water vapour to the atmosphere which increases rainfall in other areas and can make new plants grow, which build up the stream

Environmental Science (3 decks)

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