A 500 year palaeo record of sulphate and mineral dust from an Alpine ice core (Colle Gnifetti, Swiss

Alps)

M. Schwikowski 1, H.W. Gäggeler 1,2, U. Schotterer2

1 Paul Scherrer Institute, Switzerland

2 Department of Chemistry and Biochemistry, University of Berne, Switzerland

Motivation

Reconstruction of local and regional climate and atmospheric parameters

Documentation of the effects of anthropogenic emissions

The ice core

Drilling site: Colle Gnifetti glacier saddle at 4450 m asl in the Monte Rosa area

Length: 124 m (bedrock) Accumulation rate: 0.3 m water equiv. y-1

Cold glacier: firn temperatures << 0°C

Location

Time period accessible by this ice core

-120

-110

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

0D

ep

t h (

m)

1 10 100 1000 10000Age (years before 1982)

3D-Model (Wagner, 1996)Methane (Daellenbach, 2000)Saharan dustNuclear weapon testingVolcanoesAnnual layer counting

1977

1963

1936/371912

1901/02 1883

1815

1783

Dating error: ± 2 years

Dating error: ± 20 years

Mineral dust tracer Ca2+

1977 Saharan dust event

0

200

400C

a2 + [

eq

u L

-1]

0 10 20 30 40 50Ice core length [cm]

Mineral dust recordExtrem events: Saharan dust

0

100

200

300

400C

a2+

[e

qu L

-1]

1500 1600 1700 1800 1900 2000Year [A.D.]

2529 samples (5 per year)

1977

1937

1901

0

10

20

30

40

Ca

2+ [

equ

L-1]

1500 1600 1700 1800 1900 2000Year [A.D.]

Mineral dust record: long term trendIncreased Ca2+ from 1450 to 1620 (LIA?)

5-year averages

Little Ice Age in NH: cold, dry, increased atmospheric circulation

0

2

4

6

8

Na

+ [

equ

L-1]

1500 1600 1700 1800 1900 2000Year [A.D.]

10-1

100

101

102

Cl-

[ eq

u L

- 1]

10-1 100 101 102

Na+ [equ L-1]

sea salt

5-year averages

Sea salt record (Strength of Westerlies) No trend

nssSulphate recordAnthropogenic emissions, Saharan dust

0

20

40

60

80

100

120

nssS

O4

2 - [e

qu L

-1]

1500 1600 1700 1800 1900 2000Year [A.D.]

nssSulphate trendincreased concentrations from 1870-1970

0

5

10

15

20

nssS

O42+

[ eq

u L

-1]

1500 1600 1700 1800 1900 2000Year [A.D.]

5-year averages

Trend in nssSO42-/Ca2+ ratio

Change in mineral dust source or SO2 emissions?

0

1

2

3

nssS

O42 -

/ Ca2 +

ra t

i o

1500 1600 1700 1800 1900 2000Year [A.D.]

10-1

100

101

102

nss S

O4

2-

[ eq

u L

-1]

10-1 100 101 102 103

Ca2+ [equ L-1]

1640-1870 (R2=0.70)

1470-1620 (R2=0.46)

Source contribution to SO42- (eq L-1)

Period Total Sea salt

Mineral dust

exSO42-

Natural Anthrop.

Industrial1963-1981

14.7 0.23(2%)

1.92(13%)

0.98(6%)

11.6(79%)

Pre-industrial1750-1870

2.71 0.19(7%)

1.54(57%)

0.98(36%)

-

Oldest ice

0

100

200

300

nss S

O4

2 -

[ eq

u L

-1]

1500 1600 1700 1800 1900 2000Year [A.D.]

119124Depth [m]

10-1

100

101

102

103

nssS

O4

2-

[ eq

u L

- 1]

10-1 100 101 102 103

Ca2+ [equ L-1]

1640-1870 (R2=0.70)

1470-1620 (R2=0.46)

Lowest 5 m (R2=0.94)

Conclusion

No change in frequency of major Saharan dust transports

From 1450 to 1620 A.D. increased input of mineral dust and lower nssSO4

2-/Ca2+ ratios (probably related to LIA)

No change in strength of Westerlies Change in area of mineral dust source

(and probably in pre-industrial SO2 emissions)