Clumped Isotope Geochemistry: Possibilities and Complications
Isotope geochemistry of islamabad groundwater
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Transcript of Isotope geochemistry of islamabad groundwater
Isotopic and Geochemical
Characteristics of Groundwater
in Islamabadin Islamabad
By
Sajjad Munir
Introduction
�Groundwater contamination is reported in;
� Mexico, Chile, Argentina, Mangolia, Ghana, Taiwan, Canada, China, America, India, Nepal, Bangladesh, Botswana, Nigeria.Bangladesh, Botswana, Nigeria.
� Isotopic and geochemical techniques are employed greatly to study surface and groundwater contaminant transport.
Water Quality in Pakistan� Deteriorating water quality is reported in;
� Major industrial cities including;
� Sialkot, Gujrat, Faisalabad, Karachi, Qasur, Peshawar, Lahore, Rawalpindi and Sheikhupura.
� Reasons;� Reasons;
� Unchecked disposal of untreated municipal and industrial wastewater,
� Excessive use of fertilizers and insecticides.
� Effects;
� Serious water borne diseases;
� Severe illness, hepatitis, gastro-intestinal problems, chronic diarrhea, abnormalities, skin problems etc.
Problem to be addressed
�Lei Nala provides main drainage for industrial and domestic wastewater.
�Many tube wells have been installed alongside the stream bank (within a reach of 15-50 the stream bank (within a reach of 15-50 meters) are;� Most susceptible to infiltration of polluted water
through Lei Conglomerate into shallow groundwater reservoir.
� K-values ranges between 1.2 x 10-4 to 9.8 x 10-4
cm/sec.
� Groundwater recharge –5.4 liters/cm.km2.
Objectives
�Study of contaminant transport in potable groundwater systems in Islamabad city using;
� Environmental stable and radio-isotope trace � Environmental stable and radio-isotope trace techniques,
� Conventional (hydro-geochemical and physiochemical) techniques.
�To help management of potable groundwater.
The Study Area� Islamabad – National capital
� Latitude – 33º 29’ and 33º 49’ N
� Longitude – 72º 50’ and 72º 24’ E
N
Hydrogeology� Area lies in Soan River catchment basin
� Formed as part of Indo-Gangetic synclinorium of Tertiary and Pre-Tertiary sediments.
� Sedimentary deposits belong to Eocene to Recent in age.in age.
� Consolidated deposits are;
� Limestone, sandstone, clay, shale and conglomerates,
� Do not serve as aquifer.
� Unconsolidated deposits are found as;
� Terrace gravel and alluvial fill.
� Serving as groundwater aquifers.
General Geology�Area exhibits intensive tectonic activities;
� Folding and faulting forms current landform.
�Precambrian to Tertiary consolidated sedimentary rocks are exposed in the areasedimentary rocks are exposed in the area
�These are covered by Miocene to Pleistocene deposits composed of;
� Limestone, sandstone, shale with clay.
�Recent age unconsolidated deposits are clay, silt and medium to fine sand.
Generalized composite stratigraphic section of consolidated rocks in the consolidated rocks in the Islamabad- Rawalpindi area.
Field Sampling�Samples collected are as under;
� 4 surface water samples from Lei Nala,
� 10 shallow groundwater samples not deeper than 60 meters,than 60 meters,
� 12 deep groundwater samples from tube wells installed at depths greater than 100 meters.
S.#. Sample Code Type LocationCoordinates
Elevation (m)Latitude Longitude
1 IBD-01 Nala I-9 33°39'58.06"N 73°3'14.755"E 507
2 IBD-02 Nala H-9/2 33°40'17.6" N 73°02'40.6" E 511
3 IBD-03 Tube well H-9/2 near Christian Graveyard 33°40'19.9" N 73°02'41.7" E 512
4 IBD-04 Nala G-9 33°40'39.7" N 73°02'08.7" E 526
5 IBD-05 Tube well H-8/1, infront of Polytechnic Istiture for Women 33°40'32.5" N 73°03'16.6" E 520
6 IBD-06 Tube well I-8 33°39'38.6" N 73°03'57.5" E 512
7 IBD-07 Nala I-8 33°40'15.4" N 73°03'39.9" E 509
8 IBD-08 Tube well I-8/2 33°40'17.4" N 73°03'51.1" E 513
9 IBD-09 Boring G-9/4, Al-Furqan Mosque 33°40'56.7" N 73°02'22" E 531
10 IBD-10 Boring G-9/4 , Block 78, I & T Centre, Abdullah Catering 33°40'57.3" N 73°02'20.7" E 530
11 IBD-11 Boring G-9/1 33°41'00.7" N 73°01'53.2" E 535
12 IBD-12 Boring Fatima Jinnah Park, F-9 33°42'58.0" N 73°01'44.1" E 557
13 IBD-13 Boring Bahria University, Shangrilla Road, Naval Complex E-8 33°42'58.0" N 73°01'44.1" E 563
14 IBD-14 Boring Madni Mosque, Infront of Khaldunia High School F-8/2 33°42'50.9" N 73°02'03.3" E 567
15 IBD-15 Tube well G-9/2, near Haydri Market 33°41'20.2" N 73°01'37.1" E 541
16 IBD-16 Boring G-7/2-4 33°42'10.5" N 73°03'59.8" E 544
17 IBD-17 Boring Alipur, infront of Mosque 33°38'40.9" N 73°10'47.6" E 529
18 IBD-18 Boring Village Majuhan, Chak Shehzad 33°40'19.09" N 73°09'56.34" E 502
19 IBD-19 Tube well G-10/4 33°40'29.614" N 73°01'34.271" E 525
20 IBD-20 Tube well G-10/3 33°41'4.727" N 73°0'46.465" E 540
21 IBD-21 Tube well G-10/2 33°40'29.17" N 73°00'32.19" E 545
22 IBD-22 Tube well I-10/2 33°38'51.434" N 73°02'21.123" E 514
23 IBD-23 Tube well I-10/4 33°38'53.737" N 73°02'53.794" E 499
24 IBD-24 Tube well F-10/1 33°41'03.1" N 72°59'57.4" E 549
25 IBD-25 Boring H-10/1 33°39'21.4" N 73°00'49.2" E 541
26 IBD-26 Tube well G-9/4 33°40'47" N 73°02'18.6" E 528
Sample Preservation
Sampling Type Type of Bottle Method Used Preservation
δ13C 250 ml plastic bottles Filled with beakerAdd few grains of
Mercuric ChlorideMercuric Chloride
δ�3H 1L Plastic Bottles Completely filled No Preservation
Trace Metals 500 ml plastic bottles Filled with beakerAdd HNO3 to lower
pH to 2.
Major Ions 500 ml plastic bottles Filled with beaker No preservation
Physiochemical Analysis
� Electrical Conductivity and Total Dissolved Solids are measured with;
� Portable conductivity meter (Model HI 8633, M/S HANNA Instruments).
pH and temperature are measured with;� pH and temperature are measured with;
� Portable pH meter ( Model PS-19, M/S Corning, Canada).
� Dissolved Oxygen was measure with;
� Portable DO meter ( Model Sension 6, M/S HACH)
Isotopic Analysis� δ13C is analysed using isotope ratio mass spectrometer
after CO2
extraction using vacuum system.
Vacuum lines for extraction of CO
2
from inorganic matter
Isotopic Analysis� Tritium Isotope was analysed using a
scintillation counter after tritium enrichment is being done.
Liquid Scintillation counter for counting tritium units in water samples
Metal Analysis�Major cations namely Sodium, Potassium,
Calcium and Magnesium were analysed by ICP-OES.
�Major Anions were analysed by;�Major Anions were analysed by;
� Nitrates by HPLC,
� Sulphates by Spectrophotmeter,
� Carbonate, Bicarbonate and Chloride were anlysed by titration method.
Metal Analysis�Toxic metals were
analysed by;� Chromium and Total
Iron by SpectrophotometerSpectrophotometer
� Zinc, Cadmium, Lead, Copper, Nickel, Cobalt and Arsenic were analysed by 797 VA Computrace Polarograph.
Groundwater CharacterizationParameter
WHO Standard Values (1993)
Pak-EPA Standard Values(2008)
EU Standard Values (1998)
TDS <1000 mg/L <1000 mg/L Not mentioned
pH 6.5-8.5 6.5-8.5 6.5-8.5
Conductivity Not mentioned Not mentioned 2500 μS/cm
Cadmium 0.003 mg/L 0.003 mg/L 0.005 mg/L
Chloride 250 mg/L 250 mg/L 250 mg/L
Copper 2 mg/L 2 mg/L 2 mg/LCopper 2 mg/L 2 mg/L 2 mg/L
Lead 0.01 mg/L 0.01 mg/L 0.01 mg/L
Nickel 0.02 mg/L 0.02 mg/L 0.02 mg/L
Arsenic ≤0.05 mg/L ≤0.01 mg/L 0.01 mg/L
Chromium ≤0.05 mg/L 0.05 mg/L 0.05 mg/L
Nitrate 50 mg/L 50 mg/L 50 mg/L
Zinc 3.0 mg/L 3.0 mg/L Not mentioned
Sodium 200 mg/L Not mentioned 200 mg/L
Sulphate 500 mg/L Not mentioned 250 mg/L
Hardness No guideline <500 mg/L 150-500 mg/L
Chemical Analysis�Major cations and anions are analysed
namely;
� Sodium, Potassium, Calcium, Magnesium, Nitrate, Sulphate, Chloride, Carbonate and Bicarbonate.Bicarbonate.
�Trace metals analysed are;
� Zinc, Cadmium, Lead, Copper, Nickel, Cobalt, Arsenic, Chromium, Total Iron.
Nitrates
100.00
150.00
200.00
250.00
Nit
rate
co
ncen
trati
on
(p
pm
)
No
t A
naly
sed
� Permissible limit ≤ 50 ppm
� Anthropogenic source
0.00
50.00
IBD-01
IBD-02
IBD-04
IBD-07
IBD-25
IBD-16
IBD-17
IBD-18
IBD-09
IBD-10
IBD-11
IBD-12
IBD-13
IBD-14
IBD-03
IBD-05
IBD-06
IBD-08
IBD-15
IBD-19
IBD-20
IBD-21
IBD-22
IBD-23
IBD-24
IBD-26
Sample Code
Nit
rate
co
ncen
trati
on
(p
pm
)
No
t A
naly
sed
Sulphates
60.00
80.00
100.00
120.00
140.00
160.00
180.00
Su
lph
ate
Co
ncen
trati
on
(p
pm
)
� Permissible limit –500 ppm
0.00
20.00
40.00
60.00
IBD-01
IBD-02
IBD-04
IBD-07
IBD-25
IBD-16
IBD-17
IBD-18
IBD-09
IBD-10
IBD-11
IBD-12
IBD-13
IBD-14
IBD-03
IBD-05
IBD-06
IBD-08
IBD-15
IBD-19
IBD-20
IBD-21
IBD-22
IBD-23
IBD-24
IBD-26
Sample Code
Su
lph
ate
Co
ncen
trati
on
(p
pm
)
Carbonates and Bicarbonates
150.0
200.0
250.0
300.0
350.0
400.0
450.0
500.0
Bic
arb
on
ate
Co
ncen
trati
o (
pp
m)
� Carbonates are absent
� Margalla Hill Limestone is contributing to Bicarbonates.
0.0
50.0
100.0
150.0
IBD-01
IBD-02
IBD-04
IBD-07
IBD-25
IBD-16
IBD-17
IBD-18
IBD-09
IBD-10
IBD-11
IBD-12
IBD-13
IBD-14
IBD-03
IBD-05
IBD-06
IBD-08
IBD-15
IBD-19
IBD-20
IBD-21
IBD-22
IBD-23
IBD-24
IBD-26
Sample Code
Bic
arb
on
ate
Co
ncen
trati
o (
pp
m)
Chlorides
40.00
50.00
60.00
70.00
80.00
90.00
100.00
Ch
lori
de
Co
nc
en
tra
tio
n (
pp
m)
� Permissible limit – <250 ppm
0.00
10.00
20.00
30.00
IBD-01
IBD-02
IBD-04
IBD-07
IBD-25
IBD-16
IBD-17
IBD-18
IBD-09
IBD-10
IBD-11
IBD-12
IBD-13
IBD-14
IBD-03
IBD-05
IBD-06
IBD-08
IBD-15
IBD-19
IBD-20
IBD-21
IBD-22
IBD-23
IBD-24
IBD-26
Sample Code
Ch
lori
de
Co
nc
en
tra
tio
n (
pp
m)
Sodium
60
80
100
120
140
160S
od
ium
Co
ncen
trati
on
(p
pm
)
No
t A
naly
sed
� Permissible limit –200 ppm
0
20
40
IBD-01
IBD-02
IBD-04
IBD-07
IBD-25
IBD-16
IBD-17
IBD-18
IBD-09
IBD-10
IBD-11
IBD-12
IBD-13
IBD-14
IBD-03
IBD-05
IBD-06
IBD-08
IBD-15
IBD-19
IBD-20
IBD-21
IBD-22
IBD-23
IBD-24
IBD-26
Sample Code
So
diu
m C
on
cen
trati
on
(p
pm
)
No
t A
naly
sed
Potassium
30
40
50
60
70
80
Po
tassiu
m C
on
cen
trati
on
(p
pm
)
No
t A
naly
sed
� Permissible limit – 200 ppm
0
10
20
30
IBD-01
IBD-02
IBD-04
IBD-07
IBD-25
IBD-16
IBD-17
IBD-18
IBD-09
IBD-10
IBD-11
IBD-12
IBD-13
IBD-14
IBD-03
IBD-05
IBD-06
IBD-08
IBD-15
IBD-19
IBD-20
IBD-21
IBD-22
IBD-23
IBD-24
IBD-26
Sample Code
Po
tassiu
m C
on
cen
trati
on
(p
pm
)
No
t A
naly
sed
Calcium
60
80
100
120
140
160
Co
ncen
trati
on
of
Calc
ium
(p
pm
)
No
t A
naly
sed
� Permissible limit –200 ppm
� Margalla Hill Limestone is the main source of calcium in water
0
20
40
IBD-01
IBD-02
IBD-04
IBD-07
IBD-25
IBD-16
IBD-17
IBD-18
IBD-09
IBD-10
IBD-11
IBD-12
IBD-13
IBD-14
IBD-03
IBD-05
IBD-06
IBD-08
IBD-15
IBD-19
IBD-20
IBD-21
IBD-22
IBD-23
IBD-24
IBD-26
Sample Code
Co
ncen
trati
on
of
Calc
ium
(p
pm
)
No
t A
naly
sed
Magnesium
30
40
50
60
70
80
Mag
nesiu
m C
on
cen
trati
on
(p
pm
)
No
t A
naly
sed
� Permissible limit –150 ppm
� Increasing trend is evident in shallow groundwater
0
10
20
IBD-01
IBD-02
IBD-04
IBD-07
IBD-25
IBD-16
IBD-17
IBD-18
IBD-09
IBD-10
IBD-11
IBD-12
IBD-13
IBD-14
IBD-03
IBD-05
IBD-06
IBD-08
IBD-15
IBD-19
IBD-20
IBD-21
IBD-22
IBD-23
IBD-24
IBD-26
Sample Code
Mag
nesiu
m C
on
cen
trati
on
(p
pm
)
No
t A
naly
sed
Groundwater Facies Characterization
Groundwater Facies Characterization
Subdivision of diamond
Characteristics of Corresponding subdivisions of diamond-shaped fields
Percentage of samples in this
category
1 Alkaline earth (Ca+Mg) Exceed alkalies (Na+K) 53.86
2 Alaklies exceeds alkaline earths 46.15
3 Weak acids (C03+HCO
3) exceed Strong acids (SO
4+Cl) 96.15
4 Strong acids exceeds weak acids 3.84
5 Magnesium bicarbonate type 0
6 Calcium-chloride type 0
7 Sodium-chloride type 0
8 Calcium-Bicarbonate type 96.15
9 Mixed type (No cation-anion exceed 50%) 3.85
Groundwater Facies Characterization
100
80
60
Calc
iu
40
20
0
esiu
m %
Legend
Lei Nala
Deep Groundwater
Shallow Groundwater
0 20 40 60 80 100
Sodium %
40
20
0
ciu
m %
100
80
60
Magnes
Groundwater Facies Characterization
100
80
60SO
4 -2
40
20
0
ori
de %
Legend
Lei Nala
Deep Groundwater
Shallow Groundwater
0 20 40 60 80 100
HCO3 %
40
20
0
O4 -2
%
100
80
60
Chlo
ri
Legend
A= Calcium Type
B= No Dominant Type
C= Magnesium Type
D= Sodium and Potassium
Type
E= Bicarbonate Type
F= Sulphate Type
G= Chloride Type
Zinc
2.00
3.00
4.00
5.00
6.00
Zin
c C
on
cen
trati
on
(p
pm
)
� Permissible limit – 3 ppm
� Low quality pipes –anthropogenic source
0.00
1.00
2.00
IBD-01
IBD-02
IBD-04
IBD-07
IBD-25
IBD-16
IBD-17
IBD-18
IBD-09
IBD-10
IBD-11
IBD-12
IBD-13
IBD-14
IBD-03
IBD-05
IBD-06
IBD-08
IBD-15
IBD-19
IBD-20
IBD-21
IBD-22
IBD-23
IBD-24
IBD-26
Sample Code
Zin
c C
on
cen
trati
on
(p
pm
)
Cadmium
0.30
0.40
0.50
0.60
0.70
0.80
Cad
miu
m C
on
cen
trati
on
(p
pb
)
� Permissible limit – 0.003 ppm
� More frequent in deeper horizons
0.00
0.10
0.20
IBD-01
IBD-02
IBD-04
IBD-07
IBD-25
IBD-16
IBD-17
IBD-18
IBD-09
IBD-10
IBD-11
IBD-12
IBD-13
IBD-14
IBD-03
IBD-05
IBD-06
IBD-08
IBD-15
IBD-19
IBD-20
IBD-21
IBD-22
IBD-23
IBD-24
IBD-26
Sample Code
Cad
miu
m C
on
cen
trati
on
(p
pb
)
Lead
10.00
15.00
20.00
25.00
30.00
35.00
40.00
Lead
Co
ncen
trati
on
(p
pb
)
� Permissible limit – 0.01 ppm
� Corrosion from pipes and atmospheric pour down of lead through rain.
0.00
5.00
10.00
IBD-01
IBD-02
IBD-04
IBD-07
IBD-25
IBD-16
IBD-17
IBD-18
IBD-09
IBD-10
IBD-11
IBD-12
IBD-13
IBD-14
IBD-03
IBD-05
IBD-06
IBD-08
IBD-15
IBD-19
IBD-20
IBD-21
IBD-22
IBD-23
IBD-24
IBD-26
Sample Code
Lead
Co
ncen
trati
on
(p
pb
)
Copper
200.00
250.00
300.00
350.00
400.00
450.00
500.00
Co
pp
er
Co
ncen
trati
on
(p
pb
)
� Permissible limit –2 ppm
� Associated with distribution systems
0.00
50.00
100.00
150.00
IBD-01
IBD-02
IBD-04
IBD-07
IBD-25
IBD-16
IBD-17
IBD-18
IBD-09
IBD-10
IBD-11
IBD-12
IBD-13
IBD-14
IBD-03
IBD-05
IBD-06
IBD-08
IBD-15
IBD-19
IBD-20
IBD-21
IBD-22
IBD-23
IBD-24
IBD-26
Sample Code
Co
pp
er
Co
ncen
trati
on
(p
pb
)
Nickel
0.15
0.20
0.25
0.30
0.35
0.40
0.45
Nic
kel
Co
ncen
trati
on
(p
pm
)
� Permissible limit – 0.02 ppm
0.00
0.05
0.10
IBD-01
IBD-02
IBD-04
IBD-07
IBD-25
IBD-16
IBD-17
IBD-18
IBD-09
IBD-10
IBD-11
IBD-12
IBD-13
IBD-14
IBD-03
IBD-05
IBD-06
IBD-08
IBD-15
IBD-19
IBD-20
IBD-21
IBD-22
IBD-23
IBD-24
IBD-26
Sample Code
Nic
kel
Co
ncen
trati
on
(p
pm
)
Cobalt
20
30
40
50
60
70
80
Co
balt
Co
ncen
trati
on
(p
pb
)
� Permissible limit – 0.05 ppm
� Much frequent in shallow groundwater
0
10
20
IBD-01
IBD-02
IBD-04
IBD-07
IBD-25
IBD-16
IBD-17
IBD-18
IBD-09
IBD-10
IBD-11
IBD-12
IBD-13
IBD-14
IBD-03
IBD-05
IBD-06
IBD-08
IBD-15
IBD-19
IBD-20
IBD-21
IBD-22
IBD-23
IBD-24
IBD-26
Sample Code
Co
balt
Co
ncen
trati
on
(p
pb
)
Arsenic
0.06
0.08
0.10
0.12
0.14
0.16
Ars
en
ic C
on
cen
trati
on
(p
pm
)
� Permissible limit – 0.01ppm
� Local source of contamination
0.00
0.02
0.04
IBD-01
IBD-02
IBD-04
IBD-07
IBD-25
IBD-16
IBD-17
IBD-18
IBD-09
IBD-10
IBD-11
IBD-12
IBD-13
IBD-14
IBD-03
IBD-05
IBD-06
IBD-08
IBD-15
IBD-19
IBD-20
IBD-21
IBD-22
IBD-23
IBD-24
IBD-26
Sample Code
Ars
en
ic C
on
cen
trati
on
(p
pm
)
Chromium
3
4
5
6
7
8
Ch
rom
ium
Co
ncen
trati
on
(p
pb
)
� Permissible limit – ≤ 0.05 ppm
0
1
2
IBD-01
IBD-02
IBD-04
IBD-07
IBD-25
IBD-16
IBD-17
IBD-18
IBD-09
IBD-10
IBD-11
IBD-12
IBD-13
IBD-14
IBD-03
IBD-05
IBD-06
IBD-08
IBD-15
IBD-19
IBD-20
IBD-21
IBD-22
IBD-23
IBD-24
IBD-26
Sample Code
Ch
rom
ium
Co
ncen
trati
on
(p
pb
)
Total Iron
8.00
10.00
12.00
14.00
16.00
18.00
20.00
To
tal
Iro
n C
on
cen
trati
on
(p
pm
)
� No guidelines
� No evidence of industrial source of contamination
0.00
2.00
4.00
6.00
IBD-01
IBD-02
IBD-04
IBD-07
IBD-25
IBD-16
IBD-17
IBD-18
IBD-09
IBD-10
IBD-11
IBD-12
IBD-13
IBD-14
IBD-03
IBD-05
IBD-06
IBD-08
IBD-15
IBD-19
IBD-20
IBD-21
IBD-22
IBD-23
IBD-24
IBD-26
Sample Code
To
tal
Iro
n C
on
cen
trati
on
(p
pm
)
Metals Correlation Coefficients
Metals Correlation Coefficients
�Strong Correlation exists between;
� Zn and Cd,
� Cd and Co, K, As,
� Ni and Co,� Ni and Co,
� Co and As,
� Na and K and Mg,
� K and Mg.
�Suggests that these metals have same source of origin.
Metals Correlation Coefficients
�Weak Correlation exists between;
� Zn and As and Cr,
� Cd and Cu, Mg and Cr,
� Cu and Na, K, As and Cr,� Cu and Na, K, As and Cr,
� K and As,
� Mg and As and Cr.
�Suggests that these metals have different source of origin.
Carbon-13 (13δC)
-5.00
-4.00
-3.00
-2.00
-1.00
0.00
IBD-01
IBD-02
IBD-04
IBD-07
IBD-16
IBD-17
IBD-18
IBD-10
IBD-11
IBD-12
IBD-13
IBD-14
IBD-03
IBD-05
IBD-06
IBD-08
IBD-15
IBD-19
IBD-21
IBD-22
IBD-23
C v
alu
e(‰
)
� Bicarbonate is the main source of dissolved inorganic carbon (DIC).
� No evidence of mixing of domestic wastewater.
-10.00
-9.00
-8.00
-7.00
-6.00
Sample Code
13 C
valu
e(‰
)
Tritium (13δH)
4
6
8
10
12
Tri
tiu
m U
nit
s (
TU
)
� IBD-13, IBD-15, IBD-20 show mixing of meteoric/ sewage water
� Depleted contents show older waters.
0
2
4
IBD-07
IBD-16
IBD-17
IBD-09
IBD-13
IBD-14
IBD-03
IBD-06
IBD-15
IBD-20
IBD-22
IBD-23
Sample Code
Tri
tiu
m U
nit
s (
TU
)
Conclusion� Physiochemical parameters are well within the
permissible limits defined by WHO.
� Nitrate concentration is higher in shallow groundwater than the deep groundwater thus showing input from external sources.showing input from external sources.
� Ca-Mg-HCO3 type of water is dominant.
� Margalla Hill Limestone is contributing to Ca-Mg-HCO3 dominance in the area.
� No significant change in hydrochemical facies indicates natural source of origin for most of ions.
Conclusion� δ13CTDIC indicates no domestic input from surface.
� Tritium content shows mixing of surface/rain water in some of the shallow and deep groundwater wells namely;
� IBD-15, IBD-20 and IBD-13.
Recommendations
� The wells should be installed at greater distances from the Lei Nala embankment.
� The depth of tubewells should be increased to avoid infiltration from the surface.avoid infiltration from the surface.
� Peak load of Lei Nala should be monitored and tube wells should not be operated during peak load times of Lei Nala.
� Filtration plants must be installed on the tubewells along the Lei embankment.