the source of trace elements in groundwater in sandy aquifers
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The source of trace elements in groundwater in sandy aquifers. Marc J.M. Vissers Faculty of geosciences. Why trace elements in groundwater. Geochemistry Redistribution of trace elements (ore and natural anomalies) Global biogeochemical cycle Environmental science - PowerPoint PPT PresentationTRANSCRIPT
0 1 10
Li
-30
-25
-20
-15
-10
-5
0
5
0 0 0 0 1 10
B e1 10 100 1000
B0 1 10 100100010000100000
Al1000 100001000001000000
C a0 0 1 10
Ti0 0 1 10 1001000
Cr
0 1 10 100 1000
M n
-30
-25
-20
-15
-10
-5
0
5
1 0 1 0 0 1 0 0 01 0 0 0 01 0 0 0 0 0
F e0 0 1 10
C o0 0 1 10 100
Ni0 1 10
C u1 10 100 1000
Z n0 1 10
G a
0 0 1 10 100
A s
-30
-25
-20
-15
-10
-5
0
5
0 0 1 10
S e0 0 1 10
R b1 0 1 0 0 1 0 0 0
Sr0 0 0 1 10 100
Y0 0 0 1 10
Zr0 0 0 0 1
N b
0 0 0 1 10 100
M o
-30
-25
-20
-15
-10
-5
0
5
0 0 0 0 1
A g0 0 0 0 1 10
C d0 0 0 0 1
S n0 0 0 1
S b0 0 0 1 10
Cs1 0 1 0 0 1 0 0 0
B a
0 0 0 0
Hf
-30
-25
-20
-15
-10
-5
0
5
0 0 0 1 10
P b0 0 0 0
Bi0 0 0 0 1
T h0 0 0 1 10
U0 0 0 0 0 0 1 10
E u0 0 0 1 10 1001000
L a
0 1 10
Li
-45-40-35-30-25-20-15-10
-505
0 0 0
B e0 1 10 100
B0 1 10 100
Al10000 100000 1000000
C a0 0 1 10
Ti0 0 1 10
Cr
1 0 1 0 0 1 0 0 0
M n
-45-40-35-30-25-20-15-10
-505
1000 10000
F e0 0 1
C o0 0 1 10
Ni0 0 1 10
C u1 10 100
Z n0 1 10
G a
0 0 0 1 10
A s
-45-40-35-30-25-20-15-10
-505
0 0 1 10
S e0 1 10
R b1 0 1 0 0 1 0 0 0
Sr0 0 1
Y0 0 0 1 10
Zr0 0 0 1
N b
0 0 1 10
M o
-45-40-35-30-25-20-15-10
-505
0 0 0 0 0
A g0 0 0 0 0 1
C d0 0 0 0 1
S n0 0 0
S b0 0 0
Cs1 0 1 0 0 1 0 0 0
B a
0 0 0 0 0
Hf
-45-40-35-30-25-20-15-10
-505
0 0 1
P b0 0 0 0
Bi0 0 0 0 0
T h0 0 0 0
U0 0 0 0
E u0 0 0 1
L a
The source of trace elements in The source of trace elements in groundwater in sandy aquifersgroundwater in sandy aquifers
Marc J.M. Vissers
Faculty of geosciences
Why trace elements in groundwater
• Geochemistry– Redistribution of trace elements (ore and natural
anomalies)– Global biogeochemical cycle
• Environmental science– Atmospheric pollution / acidification– Agricultural pollution / acidification
• Consumption (direct and indirect)
This talk: Environmental geochemistry
- Study area and processes
- Present a 3-step approach for interpretation:- 1: Equilibrium modeling approach- 2: Coprecipitation- codissolution approach- 3: New: Steady-state input approach
Study area and processes Map of the study area
Sandy, unconsolidated aquifer, with ice-pushed ridge in the east Mainly Agricultural land use, eastern part cultivated in the 1920’s 10 Borings, total of 244 mini screens
NZwolleDeventer
210 212 214 216 218 220 222 224
482
484
486
A1A2A3A4A5
A6
A7A8
A10
A11Heeten
Wesepe
HaarleBroekland
Village
R oad
ForestH eathe r
X -coord ina te
Y-co
ordi
nate
G rass / ag ricultu re
O verijsselsch C anal
Study area and processes Cross-section of the study area
Filtrated over 0.45μm, analyzed on ICP-MS Sampled in 1989 (no trace elements), 1996 (½), and 2002 (all) Randomly analyzed on > 70 (mostly inorganic) parameters
kk
-40
-30
-20
-10
0
10
Overijssels canal Holterberg
A1A2A3A4A5A6
A7
A8A10A11
Twello Mb. Hydrological base
Groundwater level
Pine / deciduous forest
Arable land (mostly corn)
Calcite saturatedwaters
Boring with name
NO3/Fe redox boundary
SO4 redox boundary
2 km
Dep
th (m
OD
)
Bx
Z
Bx
Tw
Bx
Ap.
BxBxBxBx
Tw
Bx
Z
Tw
Bx
Tw
Surface level
Mini screen with Cl < 20 mg/l
Mini screen with 20 < Cl < 50 mg/l
Mini screen with Cl > 50 mg/l
Bx = Lower boundary of Boxtel Fm
Pz.
Geological boundary
Z = Zutphen Mb layer
Tw = Upper bd. of Twello Mb.
Ap = Appelscha Fm.
Pz = Peize Fm.
70 elements for 10 wells x 25 screens
1: Equilibrium modeling approach2: Codissolution-coprecipitation approach3: New: Steady-state input approach
1: Equilibrium modeling Theory and Assumptions
• Using CHEAQS and WATEQP– Al3+(aq) + 3OH-(aq) AlOH3(s) Solid phase– Al3+(aq) + F-(aq) AlF2-(aq) Speciation
Equilibrium modeling assumes- chemical equilibrium (also redox and pH)- pure phases- transport in dissolved phase only
1: Equilibrium modeling Results
Pure phase saturation explains:– Sulfate: Barium (barite)– Carbonate: Calcium and apparently iron and manganese in
reduced zone– Hydroxides: Aluminum, manganese in acid zone– Iron / Calcium / pH: Phosphorous (vivianite and apatite)– Phosphates: REY in acid water– Pure phase: Uranium (uraninite) in reduced water
• Depending on local conditions!
1: Equilibrium modeling Summary
Not many elements are controlled by saturation, so one may conclude:
Source-term limitation
Source-term limitation may be sedimentary and / or input-determined.
2: Coprecipitation-codissolution Assumptions and theory
Codissolution:Ca(1-x)SrxCO3 (1-x)Ca2+ + xSr2+ + CO3
2-
- Congruent, and main source- Where x is the fraction of a TRACE ELEMENT in a MAJOR ELEMENT PHASE- Can (and should be) verified using mineral data
Coprecipitation:When saturation of a major element phase is reached through
increasing concentrations or changing redox or pH conditions, the “opposite” reaction may occur
2: Coprecipitation-codissolution Bulk sediment geochemistry
(a) Be (mg/kg) (b) La (mg/kg)
0 1 10 100Ca (g/kg)
0.01
0.1
(c) Sr (g/kg)
Feldspar: 1:14
Clays: 1:60
Calcite: 1:307
Clays: 1:2000
Feldspars: 1:3500
Clays: 1:27000
Feldspars: 1:54000
Heavy minerals
10 100Al (g/kg)
0.1
1
10 100Al (g/kg)
1
10
2: Codissolution Example 1
1000 10000 100000Ca (ppb)
1 0
1 0 0
1 0 0 0S
r (pp
b)
C lay
0.325 w t%
Pollu tedsam ples
Loca l ra in
C a / S r w t ra tioP lag - 14*C lay - 38*Sea - 51Local ra in - 143C alc ite - 307*C alc ite - 320**Po llu tion - 450
Plag.
Significant aluminosilicate weathering
2: Codissolution / Coprecipitation Example 2
• Al-Be and Al-Ga (also Al-REE): is observed codissolution real dissolution?
Dutch soil
water
0.1 1 10 100 1000 10000
Al (ppb)
0.0001
0.001
0.01
0.1
1
10
Be
(ppb
)
0.1 1 10 100 1000 10000
A l (ppb)
0.0001
0.001
0.01
0.1
1
Ga
(ppb
)
2: Coprecipitation Example
1 0 1 0 0 1 0 0 0 1 0 0 0 0
F e
0
1
10
100
1000M
n Different source,but relation
2: Coprecipitation-codissolution Results
Codissolution:- Ca – Sr (carbonates and feldspar, and clay)- K – Rb (from clay mineral as identified from observed ratios)- Fe – As (iron (oxy-) hydroxides)- Mn – Mo (manganese hydroxides?)- Clay (Ca-Mg-Sr) – Cd-Tl (maybe Pb)- Al – Ga / Be / REY- Zr – Hf
Coprecipitation:- Fe – Mn - Al – REY / Be?- Fe/S – As
3: A novel approach
• But what about the ‘normal’ background (e.g. Cu, Pb, Li, etc) and unexplained anomalies (e.g. Zn, Co).
INPUT SOURCE LIMITATION
3: Steady-state input approach Assumptions
- Atmospheric deposition has been relatively constant in the Holocene, and the sediments have become “saturated” with these TE
- Concentrations should be constant with depth- Differences in evaporative concentration ratio TE/CE should
be constant with depth
X-Na+ + Me+(aq) X-Me+ + Na+(aq)seemingly conservative behavior!
- The start of the “Anthropocene” has caused changes!- Geochemical processes cause changes!
3: Steady-state input approach Results: Absolute concentrations match + Evap.
1000 10000 100000N a
0.00
0.01
0.10
1.00
10.00
100.00Copper
Seawater
Rain SallandRain Sweden
Evaporative concentration
Sorption, depending on pH
1000 10000 100000
N a
0.00
0.00
0.00
0.01
0.10
1.00
10.00
1000 10000 100000N a
0
1
10
1000 10000 100000N a
0.1
1.0
10.0
100.0
1000.0
Cadm ium Lith ium
Rubid ium
0.00
0.01
0.10
1.00
10.00
100.00Arsenic
0.00
0.01
0.10
1.00
10.00
100.00
0.00
0.01
0.10
1.00
10.00
100.00
1000.00Cobalt N ickel
3: Steady-state input approach Results: Absolute concentrations match + Evap.
0.1 1 10 100Major Element (mg/l)
0.01
0.1
1
10
100
1000
3-10 * Evaporative concentration
Trace Element (µg/l)
P'
Legend:P = Current rainwater composition and ratioP' = Historic rainwater compositionO = Seawater ratio
zTE:
zME =
2:1 so
rptio
n
zTE:zME = 1:2 sorption
P
Equal valence sorption
O
Boron
3: Steady-state input approach Lithium normalizing on Sodium (Na)
0 1 10
-60
-40
-20
0
101
10 2
10 3
10 4
10 5
106
10 7
108
10 9
110
11 1
112
11 3
114
115
116
117
118
119
120
12 1
122
123124
125126
127128
1 2913 0
13 1132
20 1
202
203
204
205
206
207
208
20 9
210
2 11
212
2 13
214
21 5
216
21 7
21 922 0
221222
2232 24225
22 7
301
30 3
304
305
306
307
308
3 09
31 0
31 1
312
31 3314
315
31 6
317
318
319
320321
32 232 3
32432 5
32 6327
3283 29
33 0
401
40 2
40 3
40 4
40 5
40 6
407
408
409
410
411
41 3
41 4
415
416
417
41 841 9
42042 1
42 2423
42 4425
426
50 1
502
5 03
504
5 05
50 6
50 7
508
509
51 0
511
512
513
514
51 5
516
51 751851 9
52 052 1
52252 3
5245 25
52 6
60 1
602
603
6 04
60 5
60 6
607
608
6 09
610611
612613
614615
61 6617
618619
62 0621
62262 3
70 1
702
703
70 4
705
70 6
70 7
708
709710
71 1712
713714
71571 6
71 7718
719720
80 1
802
803
805
806
80 7
808
80 9
810
81 1
81381 4
815816
81 7818
81 982 0
82 1822
82 3824
1 001
10 02
1003
10 04
1005
1006
10 07
1008
10 09
10 10
10 11
101210 13
10 1410 15
101610 17
10 181019
1020
1 101
11 02
1103
1104
11 05
1106
1107
11 0811 09
111011 11
111211 13
11 1411 15
111811 19
0 0 0
-60
-40
-20
0
101
102
103
10 4
10 5
10 6
10 7
10 8
10 9
11 0
111
112
11 3
114
115
116
117
11 8
11 9
1 20
121
12 2
12 312 4
125126
127128
12 9130
13113 2
20 1
202
203
204
205
2 06
20 7
20 8
209
2 10
211
21 2
21 3
214
215
216
217
21 9220
221222
22322 4
225
227
301
303
30 4
305
30 6
307
3 08
30 9
31 0
31 1
31 2
313
314
3 15
316
317
31 8
31 9
32 032 1
32232 3
32 4325
32 63 27
32832 9
33 0
4 01
40 2
403
404
40 5
40 6
40 7
408
409
4 10
411
41 3
41 4
41 5
416
41 7
41841 9
420421
422423
424425
426
501
502
50 3
504
505
506
50 7
508
509
510
51 1
512
51 3
51 4
51 5
51 6
51 751 8519
52 0521
52 252 3
524525
526
60 1
602
60 3
60 4
605
606
607
6 08
60 9
610611
61261 3
61 461 5616617
618619
62 062 1
622623
70 1
70 2
70 3
704
705
70 6
70 7
70 8
70 9710
71 1712
71 3714
71 5716717
71871 9
72 0
801
802
80 3
80 5
806
807
80 8
809
81 0
811
81 3814
815816
81 7818
81982 082182 2
82 382 4
10 01
100 2
10 03
10 04
10 05
100 6
1007
10 08
10 09
101 0
101 1
1012101 3
101 410 15
101 61017
10 18101 9
10 20
1101
110 2
11 03
110 4
11 05
110 6
1107
11 08
11 0911 10
11 1111 12
111 311 14
11 15
11 18111 9
2 log units 2 log units
Age
3: Steady-state input approach Lithium, Cobalt, Nickel, Rubidium, and Copper
- 5 - 4 - 3log[L i] - log [N a]
-60
-50
-40
-30
-20
-10
0
Dept
h (M
+SL
)
- 6 - 5 - 4 - 3log [C o] - log [N a]
- 5 - 4 - 3 - 2log [N i] - log [N a]
- 5 - 4 - 3 - 2log [R b] - log [N a]
- 5 - 4 - 3log [C u] - log [N a]
Sodium norm alized TE-D epth profiles of L i, C o, N i, R b, and Cu (w tbasis), N um bers indicate boring num ber o f anom aly from base line
A 7
A 6
A 1
A 2
A 1
A 1
A 4
A 2
A 2
A 1
A 2
A 3
A 1
A 8
A 1
A 1
A 2
A 3
A 1
A 1 / A 4
Element EQ CD-CP SEQSSI ratio SEQSSI Other Details
Li CD 15*103 Na X Low-pH weathering, slow ubiquitous IDIS4
Be CD Low-pH weatheringB 2.4*103 NaAl X GibbsiteP X Apatite, VivianiteV 28*104 -Mn X CP EQ: Mn(hydr)oxides/rhodochrosite, CP: sideriteFe X SideriteCo CD 2*104 Ca X Low-pH weathering, mobilization in reduced acid GWNi CD 5*104 Na X Low-pH weathering, mobilization in reduced acid GWCu 5*104 Na/CaZn CD 3*103 Ca X Low-pH weathering, mobilization in reduced acid GWAs CD X CD: Fe oxyhydroxides; Sedimentary control in #A3Rb CD 5*104 Na X Low-pH weathering, slow ubiquitous IDIS4
Sr CD Calcite and Al-silicatesMo X Redox-controlCd CD 12*106 Ca Low-pH weatheringCs CD 5*106 Na X Low-pH weathering, slow ubiquitous IDIS4
Ba X CD EQ: Barite, CD: Calcite and Al-silicatesU X X EQ: Uraninite, S: Mobilisation at Mn redox boundaryREY CD Low-pH weatheringGa* CD Low-pH weatheringSb* Behaviour similar to UTl* CD Low-pH weatheringPb* 1*105 CaZr* Mobilization on organic complexationHf* CD ZirconVissers, M.J.M., 2005, Patterns of groundwater quality, NGS335
Conclusions
• The steady-state input approach significantly increases the understanding of trace element behavior in the subsurface– Anomalies can be identified
• Anomalously high weathering releasing Be, Cd, Tl, Ga, Co, Ni• Kinetic incongruent “dissolution”, releasing Li, Rb, Cs• Mobilization in specific redox environments, Zn, Co, Ni• Diffuse atmospheric / agricultural pollution
• The true baseline concentrations can be predicted!
Conclusions
- For many elements rain is the main source.- Apart from breakthrough of K and Rb, also Cu,
Pb and many other elements are observed to be anthropogenically enriched in groundwater
- “Groundwater enrichment factors” of many trace elements vary from 1 (Lithium) to more than 100 (Co, Ni, Zn)
0 1 10
Li
-45-40-35-30-25-20-15-10
-505
0 0 0
B e0 1 10 100
B0 1 10 100
Al10000 100000 1000000
C a0 0 1 10
Ti0 0 1 10
Cr
1 0 1 0 0 1 0 0 0
M n
-45-40-35-30-25-20-15-10
-505
1000 10000
F e0 0 1
C o0 0 1 10
Ni0 0 1 10
C u1 10 100
Z n0 1 10
G a
0 0 0 1 10
A s
-45-40-35-30-25-20-15-10
-505
0 0 1 10
S e0 1 10
R b1 0 1 0 0 1 0 0 0
Sr0 0 1
Y0 0 0 1 10
Zr0 0 0 1
N b
0 0 1 10
M o
-45-40-35-30-25-20-15-10
-505
0 0 0 0 0
A g0 0 0 0 0 1
C d0 0 0 0 1
S n0 0 0
S b0 0 0
Cs1 0 1 0 0 1 0 0 0
B a
0 0 0 0 0
Hf
-45-40-35-30-25-20-15-10
-505
0 0 1
P b0 0 0 0
Bi0 0 0 0 0
T h0 0 0 0
U0 0 0 0
E u0 0 0 1
L a
0 1 10
Li
-30
-25
-20
-15
-10
-5
0
5
0 0 0 0 1 10
B e1 10 100 1000
B0 1 10 100100010000100000
Al1000 100001000001000000
C a0 0 1 10
Ti0 0 1 10 1001000
Cr
0 1 10 100 1000
M n
-30
-25
-20
-15
-10
-5
0
5
1 0 1 0 0 1 0 0 01 0 0 0 01 0 0 0 0 0
F e0 0 1 10
C o0 0 1 10 100
Ni0 1 10
C u1 10 100 1000
Z n0 1 10
G a
0 0 1 10 100
A s
-30
-25
-20
-15
-10
-5
0
5
0 0 1 10
S e0 0 1 10
R b1 0 1 0 0 1 0 0 0
Sr0 0 0 1 10 100
Y0 0 0 1 10
Zr0 0 0 0 1
N b
0 0 0 1 10 100
M o
-30
-25
-20
-15
-10
-5
0
5
0 0 0 0 1
A g0 0 0 0 1 10
C d0 0 0 0 1
S n0 0 0 1
S b0 0 0 1 10
Cs1 0 1 0 0 1 0 0 0
B a
0 0 0 0
Hf
-30
-25
-20
-15
-10
-5
0
5
0 0 0 1 10
P b0 0 0 0
Bi0 0 0 0 1
T h0 0 0 1 10
U0 0 0 0 0 0 1 10
E u0 0 0 1 10 1001000
L a
?