CHLORINE-36 AS A TRACER FOR
SUBSURFACE FLOW PATHS AND
RESIDENCE TIMES
Fred M. Phillips
New Mexico Tech
Socorro, NM USA
IAEA (A. Suckow, P.K. Aggarwal
and L. Araguas-Araguas; Eds.)
(2013) Isotope Methods for
Dating Old Groundwater,
IAEA (International
Atomic Energy Agency),
STI/PUB/1587, Vienna, 357 p.
(Chapter 6 – Chlorine-36
Dating of Old Groundwater)
cosmic-ray
neutron
40
R36 = 100
36
R36 = 500
R36 = 50
R36 = 40
CCl = 400
Ar
Cl
Cl
R36<1
Phillips F. M. (2013) Chlorine-36 dating of old groundwater, In Isotope Methods for Dating Old
Groundwater, IAEA (International Atomic Energy Agency), STI/PUB/1587, Vienna, pp. 125-152.
Use of 36Cl Decay to Date Old Groundwater
Tom Torgersen and Harold Bentley at Milo Holding 3 bore, 26 May 1982
Patterns produced by decay, evapotranspiration,
and chloride addition
(Phillips, 2013)
Three actual aquifers as examples
(Phillips, 2013)
Milk River aquifer on an expanded scale
(Phillips, 2013)
The Nubian aquifer: a case of simple decay
180
160
140
initial value
100 ka
100 ka
100
200 ka
200 ka
80
36
15
Cl/10 Cl
120
400 ka
60
40
400 ka
600 ka
600 ka
900 ka
20
900 ka
secular equilibrium
0
0
100
200
36
300
400
6
500
600
700
-1
Cl Concentration (10 atoms L )
Data from:
Patterson L. J., Sturchio N. C., Kennedy B. M., van Soest M. C., Sultan M., Lu Z. T., Lehmann B., Purtschert R.,
El Alfy Z., El Kaliouby B., Dawood Y., and Abdallah A. (2005) Cosmogenic, radiogenic, and stable isotopic
constraints on groundwater residence time in the Nubian Aquifer, Western Desert of Egypt: Geochemistry
Geophysics Geosystems 6.
(Phillips, 2013)
A comparison of 36Cl with 81Kr (Nubian aquifer)
Sturchio N. C., Du X., Purtschert, R. et al. (2004) One million year old groundwater in the Sahara revealed by
krypton-81 and chlorine-36: Geophysical Research Letters 31(5) L05503, doi:10.1029/2003GL019234.
Dating without a flow path: Comparison of 36Cl and 3He
60
40
36
Cl/Cl (x 10
-15
)
50
30
20
10
0
0
1
2
4
He (10
3
-6
3
4
5
-3
cm STP cm )
Phillips (2013); data from Mahara Y., Habermehl M. A., Miyakawa K., Shimada J., and Mizuochi Y. (2007) Can the
4He clock be calibrated by 36Cl for groundwater dating?: Nuclear Instruments and Methods in Physics
Research Section B: 259(1) 536-546.
Comparison of 3He and 36Cl along a flow
path: upper Patapsco aquifer, Maryland
USA
Plummer L. N. et al. (2012) Old groundwater in parts of the upper
Patapsco aquifer, Atlantic Coastal Plain, Maryland, USA: evidence
from radiocarbon, chlorine-36 and helium-4: Hydrogeology Journal
10.1007/s10040-012-0871-1, 26 p.
Use of 36Cl to calibrate climate-dependent recharge to
a semiarid aquifer: Continental intercalaire, North Africa
Petersen J. O. et al. (2014) Quantifying paleorecharge in the Continental Intercalaire (CI) aquifer by a Monte-Carlo
inversion approach of data: Applied Geochemistry 50(0) 209-221.
Use of 36Cl to calibrate climate-dependent recharge to
a semiarid aquifer: Continental intercalaire, North Africa
Petersen J. O. et al. (2014) Quantifying paleorecharge in the Continental Intercalaire (CI) aquifer by a Monte-Carlo
inversion approach of data: Applied Geochemistry 50(0) 209-221.
Use of Secular Variation in 36Cl Production
over the Millennial Scale
Records of 36Cl secular
variation in ice
cores and fossil
packrat urine
Wagner G., Laj C., Beer J., Kissel C., Muscheler R., Masarik J., and Synal H.-A. (2001) Reconstruction of the paleoaccumulation rate of
central Greenland during the last 75 kyr using the cosmogenic radionuclides 36Cl and 10Be and geomagnetic field intensity data:
Earth and Planetary Science Letters 193 515-521. Plummer M. A., Phillips F. M., Fabryka-Martin J., Turin H. J., Wigand P. E., and Sharma P.
(1997) Chlorine-36 in fossil rat urine: An archive of cosmogenic nuclide deposition over the past 40,000 years: Science 277 538-541.
Application of 36Cl secular variation to the problem of
whether 14C is conservative in carbonate aquifers
14C
Reduced Concentration
3H
Pore Volumes
Garnier J.-M. (1985) Retardation of dissolved radiocarbon through a carbonated matrix:
Geochimica et Cosmochimica Acta 49 683-694.
Silicate aquifer
Carbonate aquifer
Packrat Urine
Kwicklis E. and Farnham I. (2014) Testing the 14C ages and conservative behavior of dissolved 14C in a carbonate
aquifer in Yucca Flat, Nevada (USA), using 36Cl from groundwater and packrat middens: Hydrogeology
Journal 22(6) 1359-1381.
The Bomb-36Cl Pulse as a Tracer
Bomb-36Cl Pulse
36Cl
fallout
Modeled and Dye-3
3H
and 3He
Sturgeon Falls
3H
3He
(Phillips, 2000)
D.K. Solomon et al. (1993) A validation of
the 3H/3He method for determining
groundwater recharge: Wat. Resour. Res.
29 2951-2963.
Bomb-36Cl Pulse
Sturgeon Falls 1991
Sturgeon Falls 2015 (calculated)
3H
3He
The bomb-tritium pulse is fading rapidly
The bomb-36Cl pulse is easy to measure
3H
3He
Latitudinal distribution of bomb-36Cl fallout
F.M. Phillips (2000) Chlorine-36 in Environmental Tracers in Subsurface Hydrology
(Cook, P.G. and Herczeg, A.L., eds.) Boston, Kluwer Academic, p. 299-348.
Recent measurements on bomb36Cl
deposition in glaciers
Heikkilä U., Beer J., Feichter J., Alfimov V.,
Synal H. A., Schotterer U., Eichler A.,
Schwikowski M., and Thompson L. (2009)
36Cl bomb peak: comparison of modeled
and measured data: Atmos. Chem.
Phys. 9(12) 4145-4156.
GCM Simulation of 36Cl deposition on glaciers
Heikkilä et al. (2009)
Latitudinal simulation of bomb-36Cl deposition
Heikkilä U., Beer J., Feichter
J., Alfimov V., Synal H. A.,
Schotterer U., Eichler A.,
Schwikowski M., and
Thompson L. (2009)
36Cl bomb peak: comparison
of modeled and measured
data: Atmos. Chem.
Phys. 9(12) 4145-4156.
Comparison of glacier and soil/aquifer data
Glacier data
36Cl
enrichment of drip waters in Bunker Cave, Germany
Münsterer C., Fohlmeister J., Christl M., Schröder-Ritzrau A., Alfimov V., Ivy-Ochs S., Wackerbarth A., and
Mangini A. (2012) Cosmogenic 36Cl in karst waters from Bunker Cave North Western Germany – A tool to derive
local evapotranspiration?: Geochimica et Cosmochimica Acta 86 138-149.
Bomb-36Cl in groundwater, Odense, Denmark
What is the cause
of the sustained
bomb-36Cl input?
Alvarado J. A. C., Purtschert R., Hinsby K., Troldborg L., Hofer M., Kipfer R., Aeschbach-Hertig W.,
and Arno-Synal H. (2005) Cl-36 in modern groundwater dated by a multi-tracer approach (H-3/He-3,
SF6, CFC-12 and Kr-85): a case study in quaternary sand aquifers in the Odense Pilot River Basin,
Denmark: Applied Geochemistry 20(3) 599-609.
Hypotheses for ‘tailing’ of bomb-36Cl peak
• Adsorption or matrix diffusion in vadose zone
• Uptake of bomb-36Cl in halogenated organic
compounds and volatilization from plants, followed
by atmospheric transport
• Halogenated uptake by plants and slow release due to
organic decomposition
Bomb-36Cl pulse in Dye 3 ice core
Synal H.-A., Beer J., Bonani G., Suter M., and Wölfli W. (1990) Atmospheric transport
of bomb-produced 36Cl: Nuclear Instruments and Methods in Physics Research B52 483-488.
Bomb-36Cl pulse in vadose zone, Texas, USA
Scanlon B. R. (1992) Evaluation of liquid and vapor water flow in desert soils based
on chlorine-36 and tritium tracers and nonisothermal flow simulations: Water
Resources Research 28 285-298.
Bomb-36Cl pulse in glacier ice, Wyoming, USA
Cecil L. D., Green J. R., Vogt S., Frape S., Davis S. N., Cottrell G. L., and Sharma P. (1999)
Chlorine-36 in water, snow, and mid-latitude glacial ice of North America: Meteoric and
weapons-tests production in the vicinity of the Idaho National Engineering and
Environmental Laboratory, Idaho: U.S. Geological Survey Water-Resources Investigations
Report 99-4037, 27 pp.
Bomb-36Cl pulse in vadose zone, Washington, USA
Prych E. A. (1995) Using chloride and chlorine-36 as soil-water tracers to estimate deep
percolation at selected locations on the U.S. Department of Energy Hanford Site,
Washington: U.S. Geological Survey, Open-File Report 94-514.
Inferences
• Bomb-36Cl is increasingly attractive as a hydrologic
tracer for the mid-20th century as the tritium
pulse decays away
• Global deposition is fairly well understood
• The bomb-36Cl pulse in groundwater and the vadose
zone often shows very significant tailing
Inferences
• Most likely this is due to incorporation in plant
halogenated organics and subsequent release
by decomposition
• If so, release should be ecosystem-dependent and
predictable. Could provide important information
on organic Cl cycle.