Permafrost Intro

Question 1

T/F
there is a positive relationship between pfrost (especially continuous) and amount of organic C in the soil

Answer 1

true

Question 2

How much organic C is in pfrost?

Answer 2

~1670Pg/Gt

2x amount that’s in the atmosphere! More will end up in the atmosphere as it warms

Question 3

T/F
permafrost doesn’t preserve things very well because of the moisture

Answer 3

FALSE
things preserve very well in permafrost
eg. mummified baby mammoth found in a gold mine in Dawson City!

Question 4

permafrost is a reservoir for heavy metals –> what happens when it melts?

Answer 4

mercury (& other metals) can come out of pfrost when it melts and cause water quality issues

Question 5

permafrost=

Answer 5

ground below 0 degrees C for 2 or more years

Question 6

permafrost ___ and ice ____
= you can have permafrost without the presence of ice!

Answer 6

thaws
melts

Question 7

proglacial=

Answer 7

processes/ landforms in front of a glacier

Question 8

paraglacial=

Answer 8

temporal term for period following glaciation, characterized by enhanced sedimentation

ie after glaciation= more sediment

Question 9

periglacial=

Answer 9

areas/ landforms/ processes affected by freeze-thaw (not necessarily in permafrost)

Question 10

What are some factors influencing ground temp?

Answer 10

• seasonal changes in insolation (longer winter= cools more effectively)
• insulation by surface (snow, veg)
• geothermal heat flux (eg volcanically active areas)

Question 11

Freeze-thaw:
- facilitates ___ weathering because water ___ when frozen
- particles/ gasses get captured and ____

Answer 11

physical
expands

released

Question 12

below the depth of zero amplitude:

Answer 12

no seasonal change in ground temp

Question 13

active layer=

Answer 13

layer adjacent to the surface that seasonally warms above 0C

Question 14

Why is the presence of unfrozen water in permafrost important?

Answer 14

• latent heat effects are powerful: unfrozen water distributes latent heat effects
• thermal conductivity depends on frozen vs unfrozen sediment

Question 15

___ grain sizes lead to higher unfrozen water content

Answer 15

finer

Question 16

organics tend to have ___ unfrozen water content

Answer 16

low

(around the sand line in a grain size/ freezing chart)

Question 17

high solutes in groundwater= ____ (higher/lower) unfrozen water content

Answer 17

higher

Question 18

Describe the thermal conductivity of wet vs dry peat

Answer 18

dry peat: low thermal conductivity

wet or frozen peat: high thermal conductivity

peat is good at keeping the ground cold in the summer & extracting heat from the ground in the winter

Question 19

Thaw settling=

Answer 19

the creation of space upon thawing

Question 20

T/F
latent heat is always being released or absorbed, and it actually cools the ground as ice is melting

Answer 20

true!
counterintuitive