21 natural abundance variation

Question 1

Describe radiogenic isotope variations

Answer 1

concentrations of radiogenic nuclides are determined by concentration of mother nuclide and closure age of the mineral. This means that different rocks from different places have different ages.

isotopic abundances and isotope ratios of radiogenic nuclides differ between geographical locations

isotope signatures are taken up from soil and food into organisms. We can trace somebody’s geographical origin by analysing their teeth. In their teeth, the enamel contains fluoro apatite and Ca/Sr uptake stops in childhood. On the other hand, dentin Ca/Sr is constantly exchanged. This difference in Sr composition can be used to determine whether the person just migrated to the place where the isotopic signature corresponds to.

Question 2

What have u learnt about authentication of artwork/

Answer 2

U cannot simply say that this artwork is from this country or that country. U can only claim whether it has been forged or not. For example, when a tea company says that its from Sri lanka, u cannot prove that it is from sri lanka, u can only prove that it couldnt have come from Sri lanka. This is because your data shows that the isotopic signature found in ur sample correspond to a a certain country that is not from Sri Lanka.

Question 3

Describe the natural fractionation effect.

Answer 3

Read NB

Question 4

What are the pre conditions necessary for natural fractionation effect?

Answer 4

transfer of matter must be incomplete

element transfer is mass sensitive

Question 5

Describe Equilibrium isotope effect and kinetic isotope effect.

Answer 5

eqm constant in transfer processes differ in isotopologues (same structure but different isotopic composition)
lighter isotopes are bonded less strongly than heavier isotopes
isotope signature carries information on equilibrium state

Kinetic:
rate constant in transfer processes is different for each isotopologue
isotope signature carries information on mass transfer efficiency

Question 6

Describe IRMS.

Answer 6

Read NB

Question 7

What happens during cold climate and warm climate?

Answer 7

water vapour is more enriched in 16O cuz it is lighter than 18O. More 16O will then be trapped in ice in the mountains and less 16O will be found in the oceans

water vapour is less enriched in 16O. Less 16O will then be trapped in ice and more 16O will be found in the oceans.

Question 8

What type of information can u get from arctic glaciers?

Answer 8

Build up of layers over time.
Volcanic history
Entrapped organisms

Question 9

What are the uses of carbon isotope ratios?

Answer 9

Differ in different places.
Carbon in air is indeed coming from fossil fuels
Carbon from fossil fuels has a different isotopic signature from carbon from plant sources and ocean degrassing

Food authentication
13C / 12C is specific and defined by place and condition by which plant or animal it came from or the diet of a person. Hence u can see the isotopic ratio of 13C / 12C and compare with literature values to see if it agrees with it.