Proceedings of the 4th Mini Conference on Noble Gases in the Hydrosphere and in Natural Gas Reservoirs held
at GFZ Potsdam, GERMANY, 28.02.-02.03.2007
Measurements of helium concentration in groundwater using gas
chromatographic method
J. Pusz, I. Śliwka, J. Lasa
The Henryk Niewodniczański Institute of Nuclear Physics Polish Academy of Science
Radzikowskiego Str. 152, 31-342 Kraków, Poland
DOI: 10.2312/GFZ.mga.020
activated charcoal 50%/50%) to the TCD
detector. The signal from the detector is
registered in a computer equipped with
appropriate software.
K3
R1
R2
R3
TCD
K2
K1
V10
Cap
R3
P
Z1
Vessel with
sample with
Ar “head space
4.0 phase”
Vp- sample loop
Z2
Z5
Z4
Z3
Z6
Ar
6.0
Dewar with
liquid
nitrogen
D
T1
T2
Cylinder with
carrier gas
Syringe
Z1, Z2, Z3, Z4 - Nupro Valves
Fig. 1. Scheme of the chromatographic
system measuring helium concentration in
groundwater.
Examples of the chromatograms of the
helium concentration analysis in air,
surface water and groundwater obtained
through the chromatographic method
described above are shown in Figs 2, 3, 4
and 5, respectively. Figure 6 shows the
results of calibration of the system with the
standard 101±5 ppm helium in argon
(produced by Linde Gas).
2
Signal of TCD [mV]
Gas chromatography (GC) measurements
of helium [1] can be used as an alternative
to mass spectrometry (MS) determinations
of 4He for groundwater dating.
A scheme of the measurement system
developed in the Institute of Nuclear
Physics in Cracow is presented in Figure 1.
The system consists of a gas
chromatograph equipped with a Valco
TCD detector of 2μl volume; 10 port valve
V10; three chromatographic columns K1
(1.5 m), K2 (7 m) and K3 (2 m); sample
loop Vp; system of helium enrichment and
the vacuum pump, P. As a carrier gas
argon 6.0 is used. Water samples are taken
to the stainless steel containers of volume
2900 cm3. Helium is extracted from water
samples by the head-space (HS) method
[2,3]. The HS gas of volume V = 200 cm3
passes through a system of two (vacuumed
earlier) traps, T1 and T2 immersed in
liquid nitrogen, D. In the first trap T1, the
water vapour is stopped. In the second trap
T2 filled with activated charcoal, oxygen
and nitrogen are adsorbed whereas helium
and neon are not adsorbed and fill the
volume of the sample loop Vp, the trap T2
and a pipe connections (also earlier
vacuumed). After changing the position of
V10, helium and neon from sample loop
are dosed to the first column K1 (filled
with molecular sieve 5A) [4]. When helium
and neon gets to the second column K2
(also filled with molecular sieve 5A), the
position of V10 is changed back and the
compounds which remained in the column
K1 are removed from the system. The
columns K1 and K2 are working in the
“back flush” mode. For a better separation,
both gases (i.e. helium and neon) pass
through the third column K3 (filled with
a mixture of molecular sieve 5A and
1,5
1
0,5
He
Ne
0
4
4,5
5
5,5
6
6,5
7
7,5
8
Time [min]
Fig. 2. The chromatogram of helium
concentration analysis in 10 cm3 of air
without the system of enrichment (LOD of
TCD: 2.8 ng He).
Examples of comparisons of He analyses
performed with the aid of GC system with
those performed earlier by MS technique in
water of glacial age in the Cracow area are
shown in Table 1.
10
9
Signal of TCD [mV]
8
7
6
He
5
Ne
4
3
2
1
0
4
4,5
5
5,5
6
6,5
7
7,5
8
Time [min]
Fig. 3. The chromatogram of helium
concentration analysis in 200 cm3 of air
with the system of enrichment.
Signal of TCD [mV]
2
He
Ne
1
0,5
4
4,5
5
5,5
6
6,5
7
7,5
8
Time [min]
Fig. 4. The chromatogram of helium
concentration analysis in surface water
with the system of enrichment.
He
10
Signal of TCD [mV]
Well
11
15
16
4
He (MS)
185
212
225
He (GC)
184±5
225±6
240±7
1,5
0
In the Busko area, southern Poland,
mineral waters of interglacial age occur
with 4Heexc of (12000 to 15400)⋅10-8
cm3STP /g [6]. Similar water was found in
a recently drilled well about 10 km SE of
Busko with He content of (9500)⋅10-8
cm3STP/g as determined with the aid of
GC technique.
In conclusion, the developed system can be
regarded
as
suitable
for
helium
determinations in groundwater for dating
purposes.
8
Acknowledgments
6
This work was partly supported by grants
No. 4T12B 004 28 and 3T09D 038 29 from
the Ministry of Sciences and Education.
4
Ne
2
0
4
4,5
5
5,5
6
6,5
7
7,5
8
Time [min]
Fig. 5. The chromatogram of helium
concentration analysis in groundwater of
glacial age in Cracow with the system of
enrichment.
40
He
35
Peak's area [mVs]
Table 1.
Helium
in
10-8 cm3STP/g
measured by MS in 1992 [5] with
uncertainty lower than 4%, and by GC in
2006.
30
25
20
15
10
S = 0,2 [mVs/ng]
5
0
0
50
100
150
200
Mass [ng]
Fig. 6 The results of the calibration of the
TCD detector, (1 ng = 560·10-8 cm3 STP).
DOI: 10.2312/GFZ.mga.020
References
[1] http://water.usgs.gov/lab/dissolvedgas/lab/helium.html
[2] Śliwka I., Lasa J., 2000, Chem. Anal.
(Warsaw), 45, 59.
[3] Sugisaki R., Taki K., Geochem. J. 21,
pp. 21 to 23-27, 1987.
[4] Sugisaki R., Hiroshi T., Kawabe I., and
Miyazaki H., 1981.
Chemical
Geology, 36, 217-226.
[5] Zuber A., Weise S.M., Motyka J.,
Osenbrück K., and Rozanski K.,
J. Hydrol. 286, 87-112, 2004.
[6] Zuber A., Weise S.M., Osenbrück K.,
and Mateńko T., Appl. Geochem. 12,
643-660. 1997.