Permafrost thaw and surface water chemistry

Question 1

active layer

Answer 1

Portion of permafrost soil that thaws seasonally
- active layer thickens as permafrost thaws

Question 2

Talik

Answer 2

soil that is unfrozen all year but surrounded by permafrost

Question 3

permafrost thaw- disturbances

Answer 3

retrogressive thaw slump: saturated soil slumps along curved surface

active layer detachment slide:slides down permafrost layer

Question 4

Thermokarst

Answer 4

occurs when ice-rich permafrost thaws
- land subsides below water table-> thermokarst lake with talik below where soil is unfrozen year round but surrounded by permafrost

Question 5

Phosphorus

Answer 5

weathering of minerals containing PO4 causes inputs of P–> eutrophication

Question 6

Mercury

Answer 6

Permafrost stores a significant portion of global mercury
- fluvial concentrations of total Hg and MeHg greatly increased downstream of retrogressive thaw slumps
- microbial methylation (Inorganic mercury–> methyl-mercury) occurs in water bodies