1. Radiocarbon Dating of Groundwater
Elisabetta Boaretto
Radiocarbon Dating and Cosmogenic Isotopes Laboratory
Kimmel Center for Archaeological Sciences,
Weizmann Institute of Science
and
Dept of Land of Israel Studies and Archaeology
Bar Ilan University

2. low isotopic concentration 10-12-10-16
Isotope Main Target half-life
3He N,O stable
10Be N,O Ma
26Al Ar Ma
36Cl Ar Ma
14C N y
32Si Ar y
3H N,O y
Mineral
3He O, Mg, Si, Ca…Ol, Pyx,
10Be O, Si, Qtz, Ol,…
26Al Si, Qtz
36Cl Ca, K,… K-spar,
calcite
14C O, Si… Qtz
Cosmogenic Isotopes
Isotope Main Target half-life
3He N,O stable
10Be N,O Ma
26Al Ar Ma
36Cl Ar Ma
14C N y
32Si Ar y
3H N,O y
Mineral
3He O, Mg, Si, Ca…Ol, Pyx,
10Be O, Si, Qtz, Ol,…
26Al Si, Qtz
36Cl Ca, K,… K-spar,
calcite
14C O, Si… Qtz
Cosmogenic Isotopes
Isotope Main Target half-life
3He N,O stable
10Be N,O Ma
26Al Ar Ma
36Cl Ar Ma
14C N y
32Si Ar y
3H N,O y
Mineral
3He O, Mg, Si, Ca…Ol, Pyx,
10Be O, Si, Qtz, Ol,…
26Al Si, Qtz
36Cl Ca, K,… K-spar,
calcite
14C O, Si… Qtz
Cosmogenic Isotopes
low isotopic concentration
long half-life

3. Our Idea Surface collected raw material high 10Be low 10Be
Blade from Qesem Cave
low 10Be
Deep quarried raw material

4. n CO2 HCO3-- ~2 atoms/cm2/sec EQUILIBRIUM HOMOGENEOUSLY DISTRIBUTED
COMMON ELEMENT
CLOSED SYSTEM
T1/ y

5. EQUILIBRIUM
HOMOGENEOUSLY DISTRIBUTED
COMMON ELEMENT
T1/ y
CLOSED SYSTEM
GEOMAGNETIC FIELD
SOLAR ACTIVITY
CLIMATE
NATURAL CHANGES OF 14C
ANTHROPOGENIC CHANGES OF 14C
FOSSIL FUEL CONSUMPTION--- DILUTION OF 14C
NUCLEAR TESTS --- INCREASE OF 14C

6. Dendrochronology Bristlecone pine Building a tree-ring chronology
Sample from
a living tree
Building a
tree-ring
chronology
Dead tree
on ground
Standing
dead tree

7. 12.4 – 26 kyr BP marine data: corals, foraminifera
kyr BP Tree-Ring data set

9. Radiocarbon Activity is expressed in Pmc: percent modern carbon
Age is calculated with the Decay Law
Precision of % = years
Range 50,000 year (LSC 60,000 year)
Isotopic fractionation between 12C, 13C and 14C: δ13C
(13C/12C)sample-(13C/12C)standard
δ13C = x1000
(13C/12C)standard

10. How does carbon and radiocarbon get in the groundwater?
CO2(aq) pmc δ13C -25‰
CaCO pmc δ13C 0 ‰
2HCO3 50 pmc δ13C ‰
How does carbon and radiocarbon get in the groundwater?
CO2(gas)root aq
100 pmc δ13C -25‰
CaCO3
0 pmc δ13C 0‰
CO2(aq)+H2O+CaCO HCO3- + Ca++

11. Different water environments
Kinneret with Ohalo II
Mediterranean Coast
Dead sea and Lisan lake
stalg
Lisan
Med Coast
14C and U-Th

12. Lake Kinneret
Using modern (alive) and fossil material, water

13. Several alive specimen were measured with the water were they lived
Melanopsis Buccinoidea (buc) – lives in streams and springs (white)
Melanopsis costata – costata
(cc) – lives in the Jordan River (black)
Melanopsis costata – jordanica (cj) -lives in the Sea of Galilee (black)
Melanopsis
Saulcyi (sa) –
lives in springs
and streams,
south of the
Sea of Galilee
Several alive specimen were measured with the water were they lived

14. “Water’ plant -32.5

15. How does carbon and radiocarbon get in the groundwater?
CO2(aq) pmc δ13C -25‰
CaCO pmc δ13C 0 ‰
2HCO3 50 pmc δ13C ‰
How does carbon and radiocarbon get in the groundwater?
CO2(gas)root aq
100 pmc δ13C -25‰
14C in groundwater
- Relative ages between aquifers
- Aquifer-flow velocities
- Study of mixed system
- Establishment of flow modes which are related to environmental problems connected with recent pollution
CaCO3
0 pmc δ13C 0‰
CO2(aq)+H2O+CaCO HCO3- + Ca++

16. Hvinningdal Aquifer
- Raised plain 80 m asl
- 800 mm/y precipitation
- >200 mm/y ca. recharge
- Matrix: Tertiary quartz sand covered with quaternary meltwater sand/gravel
- Low carbonate, some tertiary lignite and reworked black org material
- pH ca. 6
- T 8-10 ºC
- O2 12 mg/l saturation value
- Some wells have nitrate
-Tritium (15-62 TU) is present in almost all the wells indicating post-bomb groundwater origin.

17. 18 wells analyzed.
Tritium TU post-bomb

18. Boaretto et al., Radiocarbon 1998
18 wells analyzed.
Tritium TU post-bomb
Matrix carbonate is negligible
Strong disagreement with the T data
<1 TU
n. 3.1 ?
Boaretto et al., Radiocarbon 1998

19. Oxygen as possible candidate for organic material oxidation
T ºC O2 mg/l
O2 + (CH2O)n CO2 + H2O

20. n. 3.1, DOC ca. 3 mg/l
DOC ca. 0.3 mg/l

21. high O2 high 14C
Low O low 14C

22. Acorr diss = Am(-25)/δ13Cm

23. Acorr diss+Ox = Am(-25)/(δ13Cm+25 F)
O2 + (CH2O)n CO2 + H2O
F =(44/32) (12-[O2])/[ΣCO2]
Acorr diss+Ox = Am(-25)/(δ13Cm+25 F)
Fluctuation in gw table

24. CONCLUSION
Most of the sample Acorr is above or close to 100 pmc ---- agreement with Tritium
Extremely low value 32 pmc is due probably to fresh exposure of organic material to atmosphere
Nitrate contribution to oxidation of organic matter
Age: not more than few hundreds year
nitrate
0 TU

25. Radiocarbon Dating in Water Environments
Very important for:
-control and use of hydrological resources
-chronologies
Variables are several
modeling is necessary