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)