Chemistry - Ice Coring

Question 1

What is the basis of using 018 for determining past carbon cycles?

Answer 1

CO2 readily dissolves in water for CO2-H20 exhange, measured in foraminifera

Question 2

How do foraminifera measure past temperatures?

Answer 2

O18 and O16 ratio determines temperature of surrounding water at time shell was formed.

Question 3

How can O18 be used to measure evaporation?

Answer 3

O16 is lighter, thus surfaces contain greater proportions of O18 where more evaporation occurs.

Question 4

How does O18 measure precipitation?

Answer 4

O18 condensates quicker than O16

Question 5

How does O18?O16 relate lattiduinally in rain?

Answer 5

It is composed of more O16 due to less O18(precipitating first)

Question 6

How does O18/O16 precipitation ratio relate to ice ages?

Answer 6

Colder temperatures in ice ages extend equatorially more-so, O18 thus rains at even lower latitudes, meaning higher O18 concentration than usual, whilst ice higher O16 concentration than usual.

Question 7

How can past water ocncnetraiton be inferred?

Answer 7

Water trapped in glaciers or marine plants and animals.

Question 8

Why can shells be harder to measure?

Answer 8

Because as they form, they incorporate more O18 than they do O16 regardless of oxygen ratio.

Question 9

What is less O18 proportional to?

Answer 9

Colder temperatures

Question 10

How else can temperature be inferred from shells?

Answer 10

Strontium and calcium balance

Question 11

What is ice coring data based on?

Answer 11

Build up of distinct snow layers on glaciers and ice sheets.

Question 12

What material in glaciers can be used for past climate inferrance?

Answer 12

Trapped bubble gas composition.
Pollen
Ions

Question 13

Why is trapped ice usually younger than it actually should be?

Answer 13

Because snow and firn in the upper 10 meters must be compacted to trap air bubbles, meaning air can still diffuse.

Question 14

What is past temperature determination based on?

Answer 14

O18 concentration.

Question 15

Istotopic Fractionation

Answer 15

The relative partioniing of the heavier and lighter isotopes between two co-existing phases in a natural system

Question 16

What is Oxygewn istootopic fractionation caused by?

Answer 16

Evaportation, condensation, thermal diffusion.

Question 17

What is thermal diffusion caused by?

Answer 17

Temperature gradients, heavier isotopes moving towards colder regions.

Question 18

How can thermal diffusion be used in measuring abrupt climate change?

Answer 18

Gas diffse in firn pores faster than heat does, meaning isotopic signals reach bubble trapping death before heat does, the degree of enrichnment telling you magnitude of climate change.

Question 19

What does pollen tell you?

Answer 19

Terrestial activity nearby.

Question 20

What do ions tell you?

Answer 20

Salinity and biogenic information.

Question 21

How can ice layers be chronologically ordered?

Answer 21

Preserved annual layers dated through seasonal variations displayed isotopic compositions, dust content,.

Question 22

Why cant seasonal variations be applied to antartica?

Answer 22

Earths orbital variations and their insolation.

Question 23

What are ice core climatic records measured by?

Answer 23

Insolation changes that can be accurately calculated in passed millions of years

Question 24

Orbital Turning

Answer 24

The process of adjusting geologic time scales to the corresponding milankovitch cycles in Earths orbital motion.

Question 25

What is orbital turning based on
?

Answer 25

Orbital changes affect insolation and thus climate, sedimentation should reflect this.

Question 26

What is another way of measuring time in ice?

Answer 26

Volcanic eruptions exhibited in the ice cores composition.