Chemical Properties

The pH of Arctic soils varies greatly (Table 1.4), and depends on the chemistry of the parent materials. The similarity of the pH to that of the parent material results, in part, because of cryoturbation, which not only mixes and translocates fresh parent material to the near surface, but also mixes soil material among the soil horizons.

The nitrogen, potassium and phosphorus contents of Arctic soils are generally low (Table 1.4), since most of these nutrients are locked into the surface organic matter (Broll et al. 1999). The movement of moisture along the thermal gradient from warm to cold results in the transfer of nutrients carried by solutes, enriching the perennially frozen layer of the soils. The movement of nutrients by this process occurs in both organic and mineral soils (Tarnocai 1972; Kokelj and Burn 2005).

Table 1.4 Selected chemical and physical characteristics of selected pedons

CaCO,

Total

Table 1.4 Selected chemical and physical characteristics of selected pedons

CaCO,

Total

Pedon

equiv.

CEC

sand

Silt

Clay

no.

Horizons

pH

(%)

C (%)

N (%)

(meq)

(%)

(%)

(%)

1

Ck

7.3

10.2

2.3

0.10

-

61.0

36.8

2.2

Cky

7.4

13.3

3.1

0.24

-

18.7

58.7

2.6

Ckyz

7.1

7.4

2.8

0.20

-

40.2

54.7

5.1

2

Ajjl

5.0

-

3.2

0.2

21.4

18.0

36.8

45.2

Ajj2

4.9

-

2.7

0.3

21.3

16.0

36.8

47.2

Bw

5.0

-

2.7

0.2

20.0

14.0

38.8

47.2

Wf/Bgf

4.9

-

2.7

0.2

26.4

16.0

38.8

45.2

Wf/Cf

4.9

-

2.8

0.2

23.3

20.0

36.8

43.2

3

Ah

6.2

-

10.3

0.9

37.0

-

-

-

Bmyl

7.2

1.85

1.4

0.1

11.3

62.8

23.3

13.8

Bmy2

7.3

1.76

1.1

0.1

10.3

63.2

23.3

14.5

Cy

7.0

1.10

2.2

0.2

16.0

64.4

23.9

11.8

Ahyz

6.6

-

13.4

0.8

51.8

-

-

-

Cyz

6.9

-

2.4

0.2

19.8

59.0

29.3

11.7

4

Bmky

7.4

7.5

1.7

0.1

-

72.3

16.0

11.7

BCky

7.2

4.6

0.2

0.1

-

75.3

14.0

10.7

Ahky

7.4

<1

5.5

0.3

-

76.9

14.2

8.9

Ckz

7.5

13.8

0.4

<1

-

82.5

11.7

5.8

5

Al

7.9

27

2.2

0.2

11.9

54.9

38.5

6.6

A2

7.9

25

2.4

0.2

9.7

49.2

42.2

8.6

Ajj

8.0

-

4.2

0.2

16.0

-

-

-

Cl

8.6

22

1.5

0.1

7.9

33.2

43.4

23.4

C2

8.3

22

0.8

0.1

7.5

36.2

42.9

20.5

Bwjj1

8.1

23

0.8

0.1

7.2

38.1

43.3

18.6

Bwjj2

8.0

23

4.4

0.1

7.2

38.9

44.9

16.2

Bwjj3

8.0

33

1.8

0.1

9.1

31.3

59.4

9.3

Wfm/Cf

7.9

22

2.8

0.1

8.5

41.0

43.6

15.5

Cf

7.4

36

2.8

0.1

6.4

54.2

35.6

10.2

6

Oi

4.1

-

17.2

0.6

2.2

20

60

20

A

4.1

-

2.4

0.2

0.9

20

62

18

Bw

4.6

-

1.4

0.1

0.7

18

62

20

Bwj

4.7

-

1.1

0.1

0.7

19

62

20

Bgfm

4.7

-

1.6

0.1

0.7

15

66

19

Ajfm

5.2

-

3.0

0.2

0.9

18

63

20

Oajfm

5.3

-

14.1

0.8

1.5

14

48

38

BCgfm

6.3

-

3.3

0.2

1.2

19

64

18

7

Oh

3.4

-

36.9

1.4

-

-

-

-

Ohz

3.5

-

47.3

1.5

-

-

-

-

Omzl

3.9

-

37.8

1.7

-

-

-

-

Omz2

4.0

-

45.1

1.8

-

-

-

-

Wz

7.0

-

-

-

-

-

-

-

8

L,H

4.2

-

43.3

1.1

70.7

-

-

-

Bmgyl

3.9

-

1.7

0.1

11.8

22.3

54.7

23.0

BCgyzl

3.9

-

1.5

0.1

11.5

22.8

56.0

21.2

Czl

4.0

-

2.3

0.1

11.7

20.4

56.2

23.4

Cz2

4.3

-

17.0

22.3

52.6

25.1

Bmgy2

4.1

-

3.8

0.1

15.3

18.3

52.3

29.4

BCgyz2

4.0

-

4.3

0.2

14.0

19.9

53.2

26.9

The electrical conductivity of arctic soils is generally low, except for those soils developed on marine clays or marine shale. For example, soils developed on marine clay in the Tanquary Fiord area of Ellesmere Island have an electrical conductivity of 1.64-2.73 mmhos cm-1, while soils developed on marine shale on Ellef Ringnes Island have a conductivity of 0.350-0.500 mmhos cm-1. Salt crusts usually develop on the surfaces of both of these types of soils during dry periods in the summer.

One of the most striking features of Arctic soils is the large amount of organic carbon in both the active layer and the perennially frozen portion of the soils (Table 1.4). Although permafrost-affected ecosystems produce much less biomass than do temperate ecosystems, permafrost-affected soils that are subject to cryoturbation have the unique ability to sequester a portion of this organic matter and store it for thousands of years.

Organic, or peatland, soils, which occur mainly in southern areas of the Arctic, contain large amounts of organic carbon that have accumulated as a result of the gradual build-up process. Although this process may be interrupted periodically by wildfires or other environmental changes, the build-up process has continued for thousands of years. The organic carbon content of these organic soils ranges from 43 to 144 kg m-2 (Tarnocai et al. 2007). The organic carbon content of cryoturbated, permafrost-affected, mineral soils, which occur throughout the Arctic, is also large, ranging from 49 to 61 kg m-2 (Tarnocai et al. 2007).

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