Applications of 81Kr and 85Kr in Groundwater Hydrology

Neil C. Sturchio1, Reika Yokochi2, Roland Purtschert3, J.K. Bӧhlke4, Pradeep Aggarwal5,

Wei Jiang6, Peter Mueller6, Zheng-Tian Lu6,7

1) Earth & Environmental Sci., University of Illinois at Chicago, Chicago, IL 60607, USA

2) Geophysical Sciences, The University of Chicago, Chicago, IL 60637, USA

3) Physics Institute, University of Bern, Bern CH-3012, Switzerland

4) Water Resources Division, U.S. Geological Survey, Reston, VA 20192, USA

5) Water Resources Programme, International Atomic Energy Agency, Vienna, Austria

6) Physics Division, Argonne National Laboratory, Argonne, IL 60439, USA

7) Department of Physics, The University of Chicago, Chicago, IL 60637, USA

Supported by NSF/EAR and DOE/Nuclear Physics

Noble gas radionuclides

85Kr

81Kr, 39Ar

Half life Abundance 81Kr 229,000 10-12 85Kr 10.8 10-11 39Ar 296 10-15

Well-mixed

0 10 20 30 40 50

0.0

0.2

0.4

0.6

0.8

1.0

Iso

top

ic A

bu

nd

an

ce

Time (Years)

Solubility equilibrium

Applicable Systems in Nature

10 -3

10 0

10 3

10 6

10 9

Time scale (years)

Air

Ocean (Surface)

(Deep)

Fresh Groundwater

Saline Groundwater

Ice Sheets

Plate Tectonics

85Kr 81Kr 39Ar 14C

81Kr: Old groundwater, glacial ice, brines 85Kr: Young groundwater, atmosphere

Competing Tracers and Advantages of Kr

Well-mixed?

Solubility equilibrium

-> (P, T, S) required

+ + +

+ +

+

+

+ 39Ar &36Cl, subsurface

production

C from carbonate

Cl from salt deposits and pore fluids Not much Kr in rocks

Degassing

CFCs, 3He loss

Biodegradation

Half Life (yr)81Kr 22900036Cl 301000

14C 5730

39Ar 269

85Kr 10.8

T-3He 12.32

CFCs Stable

How I got started on the path of the holy grail in 1999…..

First application of ATTA in hydrology:

Nubian Aquifer, Egypt

0

50

100

150

0 500 1000 1500 2000 81

Kr age (kyr)

36 C

l/C

l (x

10 -1

5 )

Bauti 1

Sherka 36

Baris(Aden)

El Zayat 12

Farafra 6

Gum Horia

36Cl-81Kr correlation

(Sturchio et al., GRL, 2004; Patterson et al., G3, 2005)

10-8 10-7 10-6 10-5 10-4 10-3 10-2 10-1 1Efficiency

107 106 105 104 103 102 10 1

Water or Ice

Sample Size (L)

Groundwater

Polar Ice

LLC

1969

AMS

1997

ATTA-1

1999

ATTA-2

2003

ATTA-3

2008 (projected)

10-8 10-7 10-6 10-5 10-4 10-3 10-2 10-1 1Efficiency

107 106 105 104 103 102 10 1

Water or Ice

Sample Size (L)

10-8 10-7 10-6 10-5 10-4 10-3 10-2 10-1 1Efficiency

107 106 105 104 103 102 10 1

Water or Ice

Sample Size (L)

Groundwater

Polar Ice

LLC

1969

AMS

1997

ATTA-1

1999

ATTA-2

2003

ATTA-3

2008 (projected)

Getting ready for ATTA-3!

Extraction of Dissolved Gas for Analysis of Radiokrypton (EDGAR)

•Up to ~30 liter/min sampling rate

•Up to ~90% extraction of dissolved gases

Improvements in on-site dissolved gas extraction

Pete Probst, MS thesis 2007, UIC Bern apparatus

Portability: EDGAR II

ATA300 case

400 lbs.

100 lbs.

Steel frame

2

Adjusted for checked luggage size in

closed ATA-certified boxes, suitable for

international travel

Improved Kr purification system (Yokochi et al., 2008)

3 ft 3 in

5-125 LSTP

bulk gas

5-250 L STP

pure Kr

- Kr extraction from 5-125 liter STP of bulk gas

in 4-6 hours with > 90% Yield

EDGAR Field Test #1: Locust Grove, Maryland

Pete Ed JK Neil

Roman Reika

Shallow unconfined aquifer

Creek

Aquitard

400 m

Water table - Agricultural area

- Denitrification studied by

Böhlke and Denver (1995)

- Comparative study of residence-time tracers 3H/3He, CFCs, SF6,

85Kr by Ekwurzel et al. (1994)

Wells

0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

0

500

1000

1500

2000

2500

3000

3500

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5

Pre

ssu

re (

To

rr)

Wa

ter

Pro

ce

sse

d (

L)

Time Elapsed (hr)

Well KeBe 61

Water Processed

Membrane Vacuum

Tank Pressure

Example of typical sampling parameters using EDGAR-1

0.01

0.1

1

10

1975 1985 1995 2005 2015

85K

r, B

q/m

3

Year

atmospheric 85Kr (Momoshima et al., 2010)

Locust Grove

samples, 2006

Comparison of SF6 and 85Kr in 2006

52

61

162

163

64

63

Creek

211

Confined unit

400 m

Water table

1984/1975*

1991/1997

1970/1970

1991/2000

1985/1987

1989/1997

1981/1982

SF6 /85Kr dates (cy)

7 samples, >150 l Kr separated

Field Test #3: WIPP (Waste Isolation Pilot Plant) storage site for TRU waste in a salt excavation near Carlsbad, NM

- What is the travel time of radionuclides from the

repository to the accessible environment?

Location of WIPP site in

southeastern New Mexico

Culebra Dolomite

Sampled wells:

SNL-8 (low trans.) and

SNL-14 (high-trans.)

Relatively low 14C found

in some brine samples

from the Culebra dolomite

aquifer

Conclusions from 14C and 36Cl measurements:

ATTA-3 results for WIPP brine samples:

Apparent Mean Residence Times (corrected assuming 85Kr/Kr in air at time of well completion):

SNL-8

SNL-14

TDS,mg/L

140,000

87,000

Problems found from CFCs, SF6, 14C measurements:

air jetting and water injection during well completion

Low-Trans.

High-Trans.

Other Work in Progress: N.A. Midcontinent

Transcontinental travel time

- Great Plains and Interior Plains

aquifers, USA

- Saline groundwaters, ~1000 km

distance from Colorado Front

Range recharge area to central

Missouri discharge area

- Anticipated travel time

~106 yrs (1 m/yr)

(Musgrove & Banner, 1993)

1000 km

Other Work in Progress : Atacama Desert, Chile

• Atacama Desert = Hyperarid region

- Rainfall <10mm/yr

- Water resource

= Vital for life and Cu industry

Beyond groundwater, oceans, and ice:

Noble gas radionuclides in different reservoirs

> 2Myr

Modern air

Local

groundwater

Crust

Planned sampling sites

Subduction Mantle gases?

Volcan Poas, Costa Rica Rio Grande Rift, New Mexico

+ Yellowstone

(Roland’s talk)

Applications in CO2 sequestration studies?