Weathering Sources in the Kaoping River Catchment,
Southwestern Taiwan: Insights From Major and
Trace Elements, Sr Isotopes and
Rare Earth Elements
C.-F. You, K.-F. Huang, C.-H. Chung and R.-M. Wang
Department of Earth Sciences
Also at Earth Dynamic System Research Center
National Cheng Kung University
Ching et al., 2007
Liu et al., 2007
Outlines
• Sr isotopes
Non-conventional high precision
Sr isotopic measurement
• Major and trace elements
• REEs
Strontium Isotopes:
84Sr
(0.56 %)
87Sr (6.99 %)
87Rb
86Sr
(9.86 %)
88Sr (82.54 %)
 87Sr＋β -＋anti-neutrino＋energy
(t1/2＝4.88× 1010years)
Geological Applications:
1. Geo-chronometer:
Rb-Sr dating
Seawater curve
2. 87Sr/86Sr Tracer:
a. River water --- weathering process
b. Sediments--- provenance and transportation
c. Biogenic carbonate---seawater evolution
3. Environmental proxy
SST or SSS
Sr Isotopic Composition of Earth Systems
Dissloved loa d in rivers
87
86
Sr/ Sr= 0.7119
Detrital loa d in rivers
87
Sr/ 86Sr= 0.7178
Mid -oc ean rid ge
Hydroherm al c irc ula tion
87
86
Sr/ Sr= 0.7035
oc ea n
sed im ent 87Sr/ 86Sr= 0.708
87
Sr/ 86Sr= 0.724
Dissolved load in river
0.7119
Detrital load in river
0.7178
Sediment
0.724
Seawater
0.708
Hydrothermal vent
0.7035
Oceanic crust
0.702
Geochemical Behaviors of Sr in the “Water World”
1. River water:
(a) Reflect the Rb/Sr ratio and “age” of the source rocks;
(b) Sources derived from silicate and carbonate weathering
2. Seawater:
(a) Chemically and isotopically “uniform” because of its
long residence time (~2 Ma);
(b) Small but considerable regional difference in flux
and ICs occurred on time-scales shorter than the
residence time;
(c) Non-conservative mixing in estuaries due to dynamic
exchanges
Oceanic Sr Budget
1, Steady or not?
2, How Sr ICs change with time?
Total mass of Sr in seawater= 1.25×1017 mol
(Assuming an average seawater concentration of 91.3 mM)
After Basu et al., 2001
Sampling Sites
Reference sites- ST-1 (NEC) and St-C (SCS)
Sample Locality
121.0
26.0
121.5
122.0
122.5
123.0
26.0
April
119
122
121
120
123
26
26
Latitude (N)
25.5
25
25.5
25.0
25
SOT
25.0
1
2
7
3
4
5
6
24.5
24.5
TAIWAN
24.0
121.0
24
Lattitude (N)
24
121.5
122.0
24.0
123.0
122.5
Longitude (E)
TAIWAN
119.5
120.0
120.5
121.0
23.0
23.0
TAIWAN
23
23
KPC
22
22
South
China
Sea
China
South
22.5
22.5
22.0
22.0
Lattitude (N)
Aug.
715-2
Sea
South China Sea
21.5
119
120
121
Longitude (E)
122
123
21.5
119.5
120.0
120.5
Longitude (E)
121.0
Modern Hydrography
Typhoon Toraji
WRA., 2003
Liang et al., 2003
Kao-Ping Canyon Sea Water Masses
35
Water mass Depth
RW
Kuroshio
Temperature (oC)
30
0
NPTW
25
RW
SCS
NPTW
SCS
100 m
20
100
200
SCS
400
15
200-300 m
Kuroshio
SCS
Summer
Winter
10
5
NPIW
32
600
1300
400-600 m
NPDW
PDW
>1300 m
0
31
SCS
NPIW
33
Salinity (psu)
34
bottom
35
Wang et al., 2002
High-Precision Sr Isotopic Measurement
P- TIMS
TRITON TI
ORI 679_S6-10 m
4.50E+08
Sr- Elution Curve
Colum n-1
4.00E+08
1. 0.709196±03
2. 0.709197±02
ORI 679_S3-10 m
Colum n-2
Seawater
3.50E+08
Colum n-3
Intensity
(cps)
3.00E+08
2.50E+08
Recovery> 99.5%
2.00E+08
1.
2.
1.50E+08
0.709195±03
0.709195±02
SB_09-12 (10.5 m)
1.00E+08
1.
2.
5.00E+07
0.00E+00
0.0
3N HNO3
5.0
8N HNO3
10.0
3N HNO3
15.0
0.05N HNO3
Eluted volum e (m L)
20.0
25.0
0.709195±03
0.709193±02
The surface distributions of Sr ICs in the KPE
119.5
120.0
120.5
121.0
23.0
23.0
Δ87Sr (ppm)
TAIWAN
64
60
56
22.5
22.5
52
Lattitude (N)
48
44
40
36
32
22.0
22.0
28
24
20
16
South China Sea
12
21.5
21.5
119.5
120.0
120.5
Longitude (E)
121.0
After Typhoon Toraji
Other Hydrographic Evidences
23
Ka
op
Ka
opi
ng
ing
Ch
i
Ch
i
23
0.3
34.5
34.3
0.2
O-18
S
22
34.1
33.9
0.1
22
0.0
Aug. 2001
120
121
Aug. 2001
120
-0.1
121
-0.2
33.7
-0.3
33.5
-0.4
-0.5
33.3
23
32.5
31.5
22
(Lin et al., 2003)
-0.7
-0.8
O-18
S
22
Aug. 2002
Aug. 2002
120
-0.6
Ka
opi
ng
Ch
i
Ka
opi
ng
Ch
i
33.1
23
121
120
121
Surface Seawater Sr ICs vs. Salinity
70.0
EM-1
60.0
Δ87Sr= -39.11*S+1338.7
r2=0.80
Δ87Sr (ppm)
50.0
40.0
EM-2
30.0
20.0
9.3 ppm
(33.99‰)
Δ87Sr= -10.82*S+377.08
r2=0.70
10.0
2σ
0.0
31.00
Freshening
31.50
32.00
32.50
EM-3
33.00
33.50
34.00
Salinity (psu)
EM-1: Most radiogenic Sr IC--- (1) intense water-sediment interaction caused by flood plume
(2) release radiogenic Sr from silicates due to stronger erosion
EM-2: Normal discharge of the Kao-ping river after heavy rainfalls
Sr Isotopic Characteristics of the Taiwan River
121.0
26.0
121.5
122.0
122.5
123.0
26.0
Δ87Sr (ppm)
26
25.5
0.7170
25.5
48
0.7160
0.7140
Latitude (N)
0.7150
44
25.0
1
Tro
40
25.0
36
2
32
7
3
0.7130
24
O
a
aw
kin
h
ug
4
5
6
28
0.7120
24.5
24.5
24
0.7110
20
0.7090
0.7080
0.7070
22
0.7060
119
120
121
122
123
TAIWAN
24.0
121.0
121.5
122.0
Longitude (E)
122.5
24.0
123.0
Mixing processes of the Water masses
--- Evidence from the vertical profiles of the Sr ICs at the SOT
87
ST-1
Sr/86Sr
S3
Sr/86Sr
0.70915
0.70915 0.70918 0.70920 0.70923 0.70925
0.70915 0.70918 0.70920 0.70923 0.70925
0
100
100
100
200
200
200
300
300
300
400
400
400
Depth (m)
500
600
700
NEC
Depth (m)
0
0
Depth (m)
87
St-C
500
600
0.70920
0.70923
0.70925
SW
NPTW
S6
NPIW
700
700
800
900
900
900
1000
1000
1000
1100
Sr/86Sr
600
800
0.709176
0.70918
500
800
1100
87
SCS
0.709182
1100
Seawater Sr ICs is “not” isotopic uniform in the open ocean and marginal sea,
but it seems to have a similar pattern in the same region.
S1
SOT
0.709176
60
10
50
8
6
Ca (mM)
Mg (mM)
40
30
4
st 1-Mg
20
st 1-Ca
st 2-Mg
st 2-Ca
st 3-Mg
10
st 3-Ca
2
st 4-Mg
st 4-Ca
st 5-Mg
st 5-Ca
0
0
0
50
100
150
200
250
Na (mM)
300
350
400
450
0
50
100
150
200
250
Na (mM)
300
350
400
450
100
600
12
6
st 1-B
st 2-B
st 3-B
st 4-B
st 5-B
st 1-Ba
st 2-Ba
st 3-Ba
st 4-Ba
st 5-Ba
90
80
70
10
500
8
400
40
30
20
10
0
0
50
100
150
200
250
Na (mM)
300
350
400
450
B (μM)
6
300
4
3
4
200
2
2
100
1
0
0
0
0
50
100
150
200
250
Na (mM)
300
350
400
450
Ba (μM)
st 1-Sr
st 2-Sr
st 3-Sr
st 4-Sr
st 5-Sr
st 1-U
st 2-U
st 3-U
st 4-U
st 5-U
50
U (nM)
Sr (μM)
60
5
0.7135
0.7135
Surface
0.7130
0.7120
0.7120
0.7115
0.7115
Sr/ 86Sr
0.7125
0.7125
0.7110
87
0.7105
0.7110
0.7105
0.7100
0.7100
0.7095
0.7095
0.7090
0.7090
0.7085
0.00
Bottom
Bottom
87
Sr/ 86Sr
0.7130
Surface
0.7085
0.05
0.10
0.15
1/Sr (μM-1)
0.20
0.25
0.30
0
100
200
300
Cl (mM)
400
500
(b)
(a)
(c)
Summary
• High precision Sr isotopic measurement can be applied as a
new sensitive tracer for studying water mass mixing near
estuary
• Rather large variation in D87Sr, >60 ppm, was detected in the
Kao-ping estuary and possibly were affected by flood plume,
river discharge and surface seawater mass
• Vertical seawater Sr ICs is “not” isotopic uniform in the open
ocean and marginal sea
• Dynamic exchange among freshwater, groundwater and
seawater are occurring in the Kaoping River estuary and
canyon
Summary (continue)
• High dissolved B and Sr in the Kaoping River emphasize
the potential impact of mountainous island to the global
oceanic chemical budget
• The dissolved REE patterns of the Kaoping River at
different tributaries show similar negative Ce anomaly
and HREE enrichment
• Strong positive Gd anomaly supports an anthropogenic
pollution in the river.
• The Sr isotopic variations are rather large, 0.712649~
0.713592, and show systematically decreasing ratios with
distance from the coastal region
THANKS FOR YOUR ATTENTION
EDSRC-NCKU, Taiwan