using stable isotope ratio analysis to distinguish ... · name of responsible person a. report...
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Using Stable Isotope Ratio Analysis to Distinguish
Perchlorate Sources
Paul B. Hatzinger, Ph.D. Shaw Environmental, Inc.
03/30/2011
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Report Documentation Page Form ApprovedOMB No. 0704-0188
Public reporting burden for the collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering andmaintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information,including suggestions for reducing this burden, to Washington Headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, ArlingtonVA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to a penalty for failing to comply with a collection of information if itdoes not display a currently valid OMB control number.
1. REPORT DATE 30 MAR 2011 2. REPORT TYPE
3. DATES COVERED 00-00-2011 to 00-00-2011
4. TITLE AND SUBTITLE Using Stable Isotope Ratio Analysis to Distinguish Perchlorate Sources
5a. CONTRACT NUMBER
5b. GRANT NUMBER
5c. PROGRAM ELEMENT NUMBER
6. AUTHOR(S) 5d. PROJECT NUMBER
5e. TASK NUMBER
5f. WORK UNIT NUMBER
7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) Shaw Environmental, Inc,4171 Essen Lane,Baton Rouge,LA,70809
8. PERFORMING ORGANIZATIONREPORT NUMBER
9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSOR/MONITOR’S ACRONYM(S)
11. SPONSOR/MONITOR’S REPORT NUMBER(S)
12. DISTRIBUTION/AVAILABILITY STATEMENT Approved for public release; distribution unlimited
13. SUPPLEMENTARY NOTES Presented at the 2011 DoD Environmental Monitoring & Data Quality Workshop (EMDQ 2011), 28 Mar ?1 Apr, Arlington, VA.
14. ABSTRACT
15. SUBJECT TERMS
16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT Same as
Report (SAR)
18. NUMBEROF PAGES
27
19a. NAME OFRESPONSIBLE PERSON
a. REPORT unclassified
b. ABSTRACT unclassified
c. THIS PAGE unclassified
Standard Form 298 (Rev. 8-98) Prescribed by ANSI Std Z39-18
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2
Perchlorate Contamination in the United States:
Historical
Military and Aerospace Issue
• Rocket Testing• Hog-Out• Manufacturing• Training Areas• OB/OD Areas• Few Commercial Sites
Limited Sources
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3
Perchlorate Detections in the United States (2005)
Map source: US EPA
One siteMultiple sites
DODDOE, NASA, DOIPrivately-owedUCMR detectionsUniversity study detections
Legend
Puerto Rico
* Lower Detection Limits - 1998
* UCMR Testing - 2001
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4
A. Natural Perchlorate1. Chilean Caliche – Atacama Desert
- natural nitrogen fertilizer2. Mineral deposits – Death Valley, CA3. Southwest soils and groundwater
B. Other Anthropogenic1. Fireworks2. Road Flares3. Perchloric Acid and Reagents4. Chlorate (herbicide) 5. Chlorine Bleach
Sylvinite (NM)
Other (Non-Military)Sources??
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Chilean Nitrate
Uses Critical N fertilizer during 19th & early
20th C (cotton, tobacco and citrus) Explosives manufacture
Perchlorate Source 1910-1960
US imported 109kg fertilizer /year 0.2% ClO4
- (highly variable) 106kg ClO4
- /year
Historical Impact Citrus or cotton ~50 mg/m2-year Possible large local Impacts
* Dasgupta, PK, et al. 2006. Perchlorate in the United States. Analysis of Relative source contributions to the Food Chain. Environ. Sci. Technol. 40;6608-6614
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6
Perchlorate Sources
Indigenous Perchlorate* Natural nitrate deposits* Perchlorate in soils* Perchlorate in groundwater & rainwater
• Atmospheric formation with O3• Other mechanisms – UV, TiO2
Natural Perchlorate in the USA
Death Valley Nitrate Deposits
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< 0.
1
0.1
- 1.0
1.0
-10.
0
10.0
- 10
0.0
> 10
0
% D
ata
Poin
ts
0
2 0
4 0
6 0
8 0
Concentrations in in Western USGroundwater
Perchlorate ug/l
Courtesy of Dr. W. Andrew Jackson,Texas Tech
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• Study area >59,000 mi2• 89% > 0.1 ppb• Estimated Mass of ClO4
-
– Saturated >2 X 106 Kg
West Texas –Southern High Plains
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(ClO)x+O2→ClO4-
µV
(ClO)x+O3 → ClO4-
DepositionDry &WetEvapotranspiration
ClO4- AccumulationPlant uptake
ClO4-
ClO4- Flushing
Evapotranspiration
Re-concentration
Land Use Change
ClO4-
Dep
th (M
)
0
5
10
15
20
0 50 100 150 200
PerchlorateChloride Nitrate D
epth
(M)
0
5
10
15
20
0 50 100 150 200
PerchlorateChloride Nitrate
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10
Can You Distinguish Natural from Synthetic Perchlorate?
Stable Isotope Ratio Analysis of Chlorine and Oxygen in Perchlorate
•Other Lines of Evidence- 36Cl Analysis- Groundwater Dating - Co-Contaminants- Other Geochemical Data
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Methods developed for analysis of both chlorine and oxygen isotopes in perchlorate. Dual isotope comparisons possible.
Analyzed by IRMS with a precision of about ± 0.1 to 0.4‰
Sample preparation is critical. Methods have been developed to collect, recover, and purify perchlorate.
Stable Isotope Ratio Analysis: Perchlorate
ClO4-
3516
16
1616 16 16
6
Hydrogen 1H, 2HOxygen 16O, 17O, 18OCarbon 12C, 13CChlorine 35Cl, 37Cl Nitrogen 14N, 15NSulfur 32S, 34S
Elements in a compound can have widely different isotopic ratios based on mode of formation (e.g.,18O in NO3 from nitrification vs. atmospheric). Stable isotope ratios can provide a unique “fingerprint”
Cl O
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Stable Isotope Analysis: Perchlorate
Sample Collection (5-10 mg)
ClO4- on IX
resin (NO3-,
SO42-, ReO4)
Preserved with HCland 4oC
Leach with 1M FeCl3 + 4MHCl (FeCl4) -collect fractions
Sample Extraction & Purification
0 1 2 3 4 50
5000
10000
15000
20000
25000
Sulfate
SO42-
des
orbe
d (m
g/L
)
Bed Volume
0
200
400
600
800
1000
Perchlorate Nitrate
NO
3- or
ClO
4- (mg/
L)
Leach with 4M HCl to remove NO3
- & SO42-,
CO3- & some humics
0 1 2 3 40
250
500
750
1,000
Perchlorate
Flow = 0.5 gal/min
ClO
4- des
orbe
d (m
M)
Bed Volume
0
100
200
300
400
500 Nitrate Sulfate
NO
3- or
SO42-
(mM
)
* Neutralize -Remove FeO3* Concentrate ClO4 supernatant* Filter unwanted precipitates * Crystallize ClO4 as CsClO4 or KCO4* Wash crystals with MeOH
Verification of Purity
40060080010001200
1085
1110
627
460
332
937 Sample-1
Sample-2 Sample-3
Inte
nsity
(a.u
.)
Raman shift (cm-1)
970
a
Crystal morphologyIon chromatography(lg sample)Micro-Raman spectroscopy
Impurity detected
IRMS – 18O/17O
Weigh crystal18O: Combust to CO(18O & 17O): decompose to O2IRMS (CO & O2)Measure yieldsDetermine O isotope ratios
IRMS – 37Cl
Weigh crystalCombust to Cl saltConvert to CH3ClPurify via GCIRMSDetermine Cl isotope ratio
Cl-
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13
Terminology:*Isotopic compositions of light elements are generally reported as “delta” ()
values in parts-per-thousand (denoted “‰” = per mil) deviations (enrichments or depletions) relative to a known standard
Equation 1. (in ‰) = (Rx/Rs-1) * 1000R = ratio heavy/light isotope (e.g., 37Cl/35Cl)Rx = sample (e.g., 37Cl/35Cl in environmental sample)Rs = standard (e.g., 37Cl/35Cl in chlorine standard “SMOC”)
* Example: 37Cl = + 30 ‰30 parts-per-thousand (3 %) more 37Cl in sample relative to a known
standard (Standard Mean Ocean Chloride; SMOC). (18O = SMOW)
Terminology:Stable Isotope Ratio Analysis
7
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-20
-15
-10
-5.0
0.0
5.0
-30 -25 -20 -15 -10 -5 0 5 10
Laboratory SaltsMilitaryHerbicidesGunpowderFireworksRoad FlaresTaiwaneseNatural (Chile)
37C
l (p
er m
il)
18O (per mil)
Forensic Isotopic Analysis: Chilean vs. Synthetic37Cl and 18O
Chlorine markedly “heavier” in syntheticperchlorate (n = 43).
Oxygen consistently“heavier” in natural (Chilean) perchlorate (n = 13).
37Cl: 0.5 + 1.0
37Cl: -12.6 + 1.5
18O: -17.5 + 2.7
18O: -6.7 + 2.2
9
Synthetic
Natural-Chilean(Mineral & fertilizer)
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-4.0
-2.0
0.0
2.0
4.0
6.0
8.0
10
12
-30 -25 -20 -15 -10 -5 0 5
1
7O
(pe
r m
il)
18O (per mil)
mass-dependentfractionation
Forensic Isotopic Analysis: Chilean vs. Synthetic17O and 18O
Chilean perchlorateExcess 17O (n = 13)
Synthetic perchlorate “mass dependent”fractionation (n = 43)
17O: + 9.3 + 0.7Range: 7.9 to 10.5
17O: 0.01 + 0.06Range: - 0.24 to 0.11
Synthetic
Natural-Chilean
17O = ~ 0.52 x 18O
17O = 17O -0.52 x 18O (= O)
Bohlke, J.K., N.C. Sturchio, B. Gu, G.M. Brown, J. Horita, W. A. Jackson, J. Batista, and P. B. Hatzinger. 2005. Perchlorate isotope forensics. Analytical Chemistry, 77; 7838-7842.
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-10
-5.0
0.0
5.0
10
-26 -24 -22 -20 -18 -16 -14 -12 -10
37C
l
18O
Can You Differentiate Synthetic Sources?
1. There are some isotopic differences between manufacturers – but only in 18O.
2. H2O is the source of oxygen in synthetic perchlorate and 18O in H2O varies globally.
3. Small dataset - batch to batch variation?- variation with time?- different “sources” in products
(e.g., flares)?
Utah Nevada China
Oregon
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17
Groundwater: Long Island Case Study
Perchlorate isotopesNitrate isotopes
Major ions, trace elementsDissolved gases
Groundwater dating
North Fork(Depot Lane)
Westhampton(BOMARC)
Northport(SCWA)
Preliminary data (2007) **not for distribution**
Analytical: 7 Wells
SCWA
Preliminary data (2007) **not for distribution**
Depot Lane
BOMARC
SCWA
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-20
-16
-12
-8.0
-4.0
0.0
4.0
8.0
-30 -25 -20 -15 -10 -5 0 5 10
37C
l (p
er m
il)
-4.0
-2.0
0.0
2.0
4.0
6.0
8.0
10
12
-30 -25 -20 -15 -10 -5 0 5 10
1
7O
(pe
r m
il)
18O (per mil)
mass-dependentfractionation
North Fork(Depot Lane)
Westhampton(BOMARC)
Northport(SCWA)
SyntheticBomarc
ChileanSCWA/DL
ChileanSCWA/DL
SyntheticBomarc
20Case Study: Long Island, NY
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Long Island, NYDepot Lane Transect
0 500 1000 1500
Distance from DL6 (m)
-40
-30
-20
-10
0
10
20
Ele
vatio
n (m
) 13.6
8.6
8.9
1.0
1.1
6.3
9.1
8.0
8.0
0.9
1.0
4.5
0.10.3
9.9
0.8
0.6
4.6
DL1 DL4DL6
Pleistocene clay confining layer
Northwest Southeast
Upper glacial aquifer
Water table
Nearrecharge
basin
NO3--N ClO4-(mg/L) (µg/L)GW flow
1
40
Age(yrs)
18
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AnthropogenicLong Island, NYAmherst, MAEdwards AFB, CAHenderson, NVSouthern California (2)Elkton, MDDahlgren, VAIsrael
Chilean FertilizerLong IslandSouthern California (3 )New Jersey
Mixtures:Southern California (2)
Comparison of 37Cl and 18O of perchlorate in groundwater from to synthetic solids and natural Chilean sources
Comparison of 18O and 17O of perchlorate in groundwater to various synthetic solids and natural Chilean sources
-20
-16
-12
-8.0
-4.0
0.0
4.0
8.0
-30 -25 -20 -15 -10 -5 0 5 10
37C
l (p
er m
il)
18O (per mil)
Isotope Results: Groundwater Data from Various Sites Compared to Chilean and
Synthetic Sources
-5.0
0.0
5.0
10
15
-30 -25 -20 -15 -10 -5 0 5 10
17O
(pe
r m
il)18O (per mil)
synthetic
Chilean
synthetic
Chilean
Mixtures Mixtures
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Death Valley Caliche
Rio Grande Basin Groundwater (Ancient)
SHP Groundwater and Vadose Soil
Indigenous NaturalPerchlorate
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-20
-16
-12
-8.0
-4.0
0.0
4.0
8.0
-30 -20 -10 0 10 20 30
37C
l (p
er m
il)
18O (per mil)
Synthetic
Chilean
Southern High PlainsTexas GWTexas Soil
Rio Grande, NM GW
Death Valley caliche
Comparison of 37Cl and 18O in perchlorate from indigenous US sources with Chilean and synthetic perchlorate.
Indigenous Perchlorate: 37Cl and 18O
1. There are multiple signatures for natural perchlorate but all are readily distinguished from synthetic sources via 37Cl and 18O.
2. West Texas vadose (soil) perchlorate has a similar isotope signature to that inWest Texas & NM groundwater.
Chilean caliche & fertilizer, and GW
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-5.0
0.0
5.0
10
15
20
-20 -10 0 10 20 30
1
7O
(pe
r m
il)
18O (per mil)
Synthetic
Chilean Death Valleycaliche
Southern High PlainsWT GW
West Texas SoilRio Grande, NM GW
Comparison of 17O and 18O in perchlorate from indigenous US sources with Chilean and synthetic perchlorate.
Indigenous Perchlorate: 17O and 18O
17O: + 0.4 + 0.2
18O: 2.6 + 1.5
17O: 12.7 + 4.2
1. Like Chilean samples, Death Valley deposits have significant excess 17Oin perchlorate.
2. SHP soil and groundwater has only slight 17O excess –no difference between saturated and unsaturated zone??
3. Understanding the origin of natural perchlorate (and the resulting isotope values) is currently the subject of significant research.
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Perchlorate Origin - Why different signatures?
Understanding of Natural Perchlorate Origin: Why is 17O so low in SHP Perchlorate ?
(1) Different reaction mechanism and/or location. - Ozone vs. UV reaction? - Atmosphere vs. surface catalyzed? - What does 36Cl tell us?
(2) Post-depositional modification. - Does oxygen in perchlorate exchange
with water?- Role of plants or microorganisms?
(ClO)x+O2→ClO4-
µV
(ClO)x+O3 → ClO4-
ClO4
ClO4
ClO4
ClO4
H2O
17O18O
Perchlorate generated with O3
-5.0
0.0
5.0
10
15
20
-30 -20 -10 0 10 20 30
17
O (
per
mil)
18O (per mil)
Synthetic solids
Atacama caliche/fertilizer
Death Valley caliche
West Texas
OCl- + O3
ClO2 + O
3
-5.0
0.0
5.0
10
15
20
-30 -20 -10 0 10 20 30 40 50
1
7O
(pe
r m
il)
18O (per mil)
Synthetic solids
Atacama caliche/fertilizer
Death Valley caliche
West Texas
OCl- + UVClO
2 + UV
Perchlorate generated with UV
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36Cl Analysis
Long-lived radioisotopeproduced in the stratosphere from 40Ar(T1/2 = ~ 301,000 yrs)
36Cl/Cl = ~ 700 x 10-15
Analyzed by AcceleratorMass Spectrometry (AMS)
Analyzed purified perchlorate samples- Southwest US- Atacama- Synthetic
1. Southwest perchlorate (SHP and DV) significantly enriched in 36Cl –Irrespective of 17O.
2. Suggests significant component of “young” atmospheric perchlorate.
3. Atacama most likely “old” atmosphericperchlorate
Sturchio N.C., Caffee M.R., Beloso A. D., Heraty L.J., Böhlke J.K., Gu B., Jackson W.A., Hatzinger P.B., Heikoop J.R., and Dale M., 2009. Chlorine-36 as a tracer of perchlorate origin. Environmental Science & Technology 43, 6934–6938.
Atacama
Southwest US
Synthetic
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Perchlorate Forensic Analysis: Summary25
When perchlorate is detected at low concentrations (< 10 g/L) in groundwater, natural sources should be considered.
Isotope analyses (37Cl, 18O, 17O and 36Cl/Cl) can be used to distinguish between synthetic and natural sources – Four independent measurements.
Natural perchlorate (from Chilean fertilizer and from “indigenous” sources) has been detected in numerous wells in the US via isotope analysis.
A “Guidance Manual” for perchlorate isotope sampling is presently under development by SERDP/ESTCP.
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Contact Information
Paul Hatzinger, Ph.D.Shaw Environmental [email protected]
Neil C. Sturchio, Ph.D.University of Illinois at ChicagoChicago, ILTel. (312) [email protected]
ER-0509 Project Team
John Karl Bohlke, Ph.D.US Geological SurveyReston, VA(703) [email protected]
Baohua Gu, Ph.D.Oak Ridge National Lab Oak Ridge, TN(865)[email protected]
We gratefully acknowledge SERDP and ESTCP for supporting this work