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Environmental CSI:Chl i t d S l t R lChlorinated Solvent Releases
Alan Jeffrey, Ph.D.DPRA/Zymax Forensics600 S. Andreasen DriveEscondido, CA 92029
Chlorinated SolventsChlorinated Solvents
PCEPCE dr cleaningdr cleaningPCE PCE –– dry cleaning dry cleaning solventsolventTCETCETCE TCE –– vapor vapor degreasing solventdegreasing solventTCA TCA –– degreasing degreasing solventsolventDissolve in Dissolve in groundwater; migrate easilygroundwater; migrate easilyVapors intrude into overlying buildingsVapors intrude into overlying buildings
Chlorinated SolventChlorinated SolventChlorinated Solvent Chlorinated Solvent IssuesIssues
Is the chlorinated solvent in a plume from Is the chlorinated solvent in a plume from
one or more sources?one or more sources?
Is the chlorinated solvent in separate plumesIs the chlorinated solvent in separate plumesIs the chlorinated solvent in separate plumes Is the chlorinated solvent in separate plumes
from the same source or different sources?from the same source or different sources?
Is TCE in a PCE plume from degradation of Is TCE in a PCE plume from degradation of
the PCE or from a separate TCE source?the PCE or from a separate TCE source?the PCE or from a separate TCE source?the PCE or from a separate TCE source?
Chlorinated SolventChlorinated SolventChlorinated Solvent Chlorinated Solvent CharacterizationCharacterization
PCE, TCE etc are single compoundsPCE, TCE etc are single compounds
Different sources are chemically identicalDifferent sources are chemically identical
May be stable isotopic differencesMay be stable isotopic differences
1313C/C/ 1212CC 3737Cl/Cl/ 3535Cl D/H ratios differ dependingCl D/H ratios differ depending1313C/C/ 1212C, C, 3737Cl/Cl/ 3535Cl, D/H ratios differ depending Cl, D/H ratios differ depending
on feedstock and manufacturing process on feedstock and manufacturing process
Carbon IsotopesCarbon IsotopesCarbon IsotopesCarbon Isotopes
6P6N
6P7N
6P8N
Mass 12(stable)
Mass 13(stable)
Mass 14(radioactive)(stable)
12C(stable)
13C(radioactive)
14C
I t i t ti fI t i t ti fIn nature approximate ratios for:In nature approximate ratios for:D/H:D/H: 1/65001/6500 1313C/C/1212C:C: 1/991/99
3737Cl/Cl/3535Cl: 1/3Cl: 1/3Cl/Cl/ Cl: 1/3Cl: 1/3
Compound Specific Isotope AnalysisCompound Specific Isotope Analysis
Volatiles isolated from groundwater and soil Volatiles isolated from groundwater and soil ggon a Solid Phase Micro Extraction (SPME) on a Solid Phase Micro Extraction (SPME) fibrefibre
Volatiles desorbed in inlet of GC/Isotope Volatiles desorbed in inlet of GC/Isotope Ratio Mass SpectrometerRatio Mass SpectrometerRatio Mass SpectrometerRatio Mass Spectrometer
Carbon isotope ratios measured asCarbon isotope ratios measured as δδ1313C inC inCarbon isotope ratios measured as Carbon isotope ratios measured as δδ C in C in parts per mil (parts per mil (oo//oooo) referenced to PDB ) referenced to PDB standard (0 standard (0 oo//oooo))
GC/IRMS InstrumentGC/IRMS InstrumentGC/IRMS InstrumentGC/IRMS InstrumentSchematicSchematic
CASE STUDIESCASE STUDIES
Progression from simple to more complexProgression from simple to more complexg p pg p p
Carbon isotope ratios, little biodegradationCarbon isotope ratios, little biodegradationp , gp , g
Carbon isotope ratios, biodegradationCarbon isotope ratios, biodegradation
Carbon and Chlorine isotope ratios, multiple Carbon and Chlorine isotope ratios, multiple ififaquifersaquifers
C b Chl i d H d i tC b Chl i d H d i tCarbon, Chlorine, and Hydrogen isotope Carbon, Chlorine, and Hydrogen isotope ratiosratios
Case 1: Offsite PCE Source?Case 1: Offsite PCE Source?Case 1: Offsite PCE Source?Case 1: Offsite PCE Source?
Retail StoreRetail StoreRetail StoreRetail Store
Possible offsite dry cleaning sourcePossible offsite dry cleaning sourcey gy g
Possible onsite/offsite solvent cleaning sourcePossible onsite/offsite solvent cleaning sourcegg
Single or Multiple Sources?Single or Multiple Sources?
Time(s) of releaseTime(s) of release
GROUNDWATERGROUNDWATER
SAMPLE PCE TCE
δ13C of Chlorinated Hydrocarbons
SAMPLEIDENTIFICATION ‰ ug/L ‰ ug/L
MW 108 -26.4 2580 -30.8 71
PCE TCE
6 580 30 8MW-109 -25.8 1960 -30.0 63MW 102 -30.4 109 0.9MW 117 -30.4 100 -32.0 4MW 1 28 1 372 31 5 21MW 1 -28.1 372 -31.5 21
PCE PCE δδ1313C C
-28.1-30.4
-25.8-26.4
-30.4
ConclusionsConclusions
At least two PCE sourcesAt least two PCE sourcesAt least two PCE sourcesAt least two PCE sources
Lik l ff it k d d tLik l ff it k d d tLikely offsite, more work needed to Likely offsite, more work needed to establish thisestablish this
Plumes possibly mixing Plumes possibly mixing downgradientdowngradientp y gp y g ggin the sitein the site
Time of releaseTime of release
Case 2: Multiple PCE Releases?Case 2: Multiple PCE Releases?pp
Dry Cleaning OperationDry Cleaning Operationy g py g p
Two Operators 1968Two Operators 1968--19781978pp
Current Operator 1978Current Operator 1978--PresentPresent
PCE in soil and groundwaterPCE in soil and groundwater
Single or Multiple Sources?Single or Multiple Sources?
ConclusionsConclusions
Fairly uniform PCEFairly uniform PCE δδ1313C ratiosC ratiosFairly uniform PCE Fairly uniform PCE δδ C ratiosC ratios
N id f lti lN id f lti lNo evidence for multiple sourcesNo evidence for multiple sources
Possible that different operators used Possible that different operators used PCE from the same distributorPCE from the same distributor
3737Cl/Cl/ 3535Cl can now provide additionalCl can now provide additional3737Cl/Cl/ 3535Cl can now provide additional Cl can now provide additional way to distinguish plumesway to distinguish plumes
Case 3: Offsite TCE Source?Case 3: Offsite TCE Source?
Manufacturing operationManufacturing operation
Degreasers used onsiteDegreasers used onsite
TCE, some PCE in groundwaterTCE, some PCE in groundwater
Offsite, onsite sources?Offsite, onsite sources?
GW Flow Direction
GROUNDWATERGROUNDWATER
PCE PCE δδ1313C C
-19.2
-25.4 -23.6
-24.8
-24.5
-28.6
-23.7
28.6
-31.8
ConclusionsConclusions
Two TCE plumesTwo TCE plumesTwo TCE plumesTwo TCE plumes
Off it TCE i ti itOff it TCE i ti itOffsite TCE source, migrating onsiteOffsite TCE source, migrating onsite
Onsite PCE/TCE source ?Onsite PCE/TCE source ?
3737Cl/Cl/ 3535Cl can now provide additional Cl can now provide additional way to distinguish plumesway to distinguish plumesway to distinguish plumesway to distinguish plumes
Case 4: PCE Degradation?Case 4: PCE Degradation?Case 4: PCE Degradation?Case 4: PCE Degradation?
PCE releasesPCE releasesPCE releasesPCE releases
Two potential sourcesTwo potential sources
Mixing of plumes?Mixing of plumes?
Delineate sourcesDelineate sourcesDelineate sourcesDelineate sources
PCE DegradationPCE Degradationgg
As PCE degradesAs PCE degradesAs PCE degrades, As PCE degrades, isotopic ratio isotopic ratio hh
TCE
changeschanges
PCE DegradationPCE Degradation12C – X Bonds are weaker than 13C – X Bonds
In a chemical reaction, 12C – X Bonds break fasterthan 13C – X Bonds
If reaction proceeds to completion – all PCE goes to TCE -isotope ratio in product is the same as in starting material
If reaction is partially completed, 12C is concentrated in product, and 13C is concentrated pin starting material
Product (TCE) becomes more negative; starting materialProduct (TCE) becomes more negative; starting material (PCE) becomes less negative
PCE SourcesPCE Sources
PCE PCE δδ1313C C
δ 13C
GROUNDWATERGROUNDWATER
δ13C of Chlorinated Hydrocarbonsδ13C of Chlorinated Hydrocarbons
SAMPLE PCE TCE cis-DCE
IDENTIFICATION ‰ /L ‰ /L ‰ /LIDENTIFICATION ‰ ug/L ‰ ug/L ‰ ug/L
MW 1A -11.6 20 -36.4 7 n/a n/aMW-4A -17.4 33 -31.1 46 -39.9 2MW-5A -27.0 28 -32.1 11 -29.1 <1MW-7A -23.4 73 -36.2 54 n/a <1
MW-10A -28.7 2800 -42.2 82 -24.9 <1MW-15D -24.4 35 -38.9 16 n/a n/aMW-16D -28.4 76 -35.7 22 -32.5 2MW-18D -29.1 8 -28.9 76 -46.5 6.6MW-20D -29 6 4 -32 1 38 -35 8 1-29.6 4 -32.1 38 -35.8 1MW-21D n/a 3. -27.6 110 n/a 8
PCE DegradationPCE Degradation
If isotope ratios and concentrations of daughter products are known isotope ratio of initial PCE can beproducts are known, isotope ratio of initial PCE can be calculated
Initial PCE δ 13C =
PCE δ 13C x conc + TCE δ 13C x conc + DCE δ 13C x concPCE δ 13C x conc + TCE δ 13C x conc + DCE δ 13C x concPCE + TCE + DCE conc
Assuming no loss of PCE, TCE, DCE or other daughter products from the systemproducts from the system
Calculated Initial PCE Calculated Initial PCE δδ1313C C
ConclusionsConclusions
PotentialPotential upgradientupgradient undegradedundegraded PCEPCEPotential Potential upgradientupgradient undegradedundegraded PCE PCE sourcesourcePCE degraded in somePCE degraded in some downgradientdowngradientPCE degraded in some PCE degraded in some downgradientdowngradientwellswellsI iti l PCE b i t ti fI iti l PCE b i t ti fInitial PCE carbon isotope ratios for Initial PCE carbon isotope ratios for degraded PCE consistent with the degraded PCE consistent with the
d d dd d dundegradedundegraded sourcesourceMust be consistent with hydrogeologyMust be consistent with hydrogeology
Case 5: Contamination in Multiple Aquifers
• Upper and lower aquifers have PCE
contamination
O l t f TCE d DCE littl t• Only traces of TCE and DCE - little apparent
degradation
• Isotope ratios not altered by degradation
• Multiple sources in upper aquifer?
• Different sources in upper and lower aquifer?• Different sources in upper and lower aquifer?
PCE Concentrations in Upper AquiferPCE Concentrations in Upper Aquiferug/L
260260
1,100 ,
210
180180
PCE Concentrations in Lower AquiferPCE Concentrations in Lower Aquiferug/L
140140
PCE Isotope Ratios in Upper AquiferPCE Isotope Ratios in Upper Aquiferδ13C δ37Cl
-28 9 -2 028.9 2.0
-29.9 -1.6
-29.3 -0.5
29 6 0 8-29.6 -0.8
PCE Isotope Ratios in Lower AquiferPCE Isotope Ratios in Lower Aquiferδ13C δ37Cl
27 0 0 2-27.0 -0.2
PCE in Multiple AquifersPCE in Multiple Aquifers
δ13C δ37Cl
-29.6 -0.8
-27.0 -0.2. .
PCE in Multiple AquifersPCE in Multiple Aquifers
LowerUpper
Conclusions
• Some differences in carbon and chlorine
isotopes in upper aquifer
P ibl diff t• Possibly different sources
• Significant differences between upper and g pp
lower aquifers in the same well
• Definitely different sources
Case 6: Multiple PCE, TCE SourcesCase 6: Multiple PCE, TCE SourcesCase 6: Multiple PCE, TCE SourcesCase 6: Multiple PCE, TCE Sources
PCE and TCE releasesPCE and TCE releasesPCE and TCE releasesPCE and TCE releases
Multiple PCE sources?Multiple PCE sources?
TCE from degradation of PCE TCE from degradation of PCE l f TCE l ?l f TCE l ?release or from TCE release?release or from TCE release?
1 9001,200
3,300 1,900370
,
<10
<10
44050
7,100
110
3,300 PCE concentration ug/L
7,100 TCE concentration ug/L
27 7-25.4
-25.8 -27.75.8
-27.5
-27.2
-27.7 PCE Carbon Isotope Ratio o/oo
1 7-0.2
-0.2 -1.7.
-0.2 PCE Chlorine Isotope Ratio o/oo
-36.1
-28.9
-29.0
-28.5
-29 0 TCE Carbon Isotope Ratio o/29.0 TCE Carbon Isotope Ratio /oo
D/H Ratio and TCED/H Ratio and TCED/H Ratio and TCE D/H Ratio and TCE SourceSource
TCE
Is TCE in a PCE plume from degradation ofIs TCE in a PCE plume from degradation ofIs TCE in a PCE plume from degradation of Is TCE in a PCE plume from degradation of
the PCE or from a separate TCE source?the PCE or from a separate TCE source?D/H ratio of H in TCE can discriminateD/H ratio of H in TCE can discriminateH in degraded TCE comes from HH in degraded TCE comes from H22O in O in gg 22groundwatergroundwaterH in manufactured TCE has very different H in manufactured TCE has very different D/H ratioD/H ratio
+68
+55
+400
+400 TCE Hydrogen Isotope Ratio o/+400 TCE Hydrogen Isotope Ratio /oo
Conclusions
• Two PCE sources – confirmed by Carbon and
Chlorine isotope ratios
P ibl i ti th• Possible migration pathway
• TCE source – limited migrationg
• Other TCE from PCE degradation – confirmed
by hydrogen isotope ratios
Monitoring Degradation Monitoring Degradation
1 As PCE degrades1 As PCE degrades1. As PCE degrades, 1. As PCE degrades, isotopic ratio isotopic ratio hh
TCE
changeschanges
Monitoring DegradationMonitoring Degradation
PCE MTBE BTEX compounds nitratePCE MTBE BTEX compounds nitratePCE, MTBE, BTEX compounds, nitratePCE, MTBE, BTEX compounds, nitrate
MM δδ1313CC δδ1515N ti lN ti lMeasure Measure δδ1313C or C or δδ1515N over time or along N over time or along plumeplume
If ratios change and become less If ratios change and become less ggnegative, degradation is occurringnegative, degradation is occurring
Useful to confirm natural attenuationUseful to confirm natural attenuation
CONCLUSIONSCONCLUSIONSCONCLUSIONSCONCLUSIONS
Measure Carbon and Chlorine ratios for more Measure Carbon and Chlorine ratios for more definitive evidencedefinitive evidenceHydrogen ratios if source of TCE is an issueHydrogen ratios if source of TCE is an issueSelect samples to adequately characterize theSelect samples to adequately characterize theSelect samples to adequately characterize the Select samples to adequately characterize the plumeplumeIf the budget is limited, use a 2 phase approach:If the budget is limited, use a 2 phase approach:Li it d t d t t i t i diffLi it d t d t t i t i diffLimited survey to detect any isotopic differences Limited survey to detect any isotopic differences within plume pointing to multiple sourceswithin plume pointing to multiple sourcesMore detailed survey to delineate components of More detailed survey to delineate components of a mixed plumea mixed plumeDon’t assume that all that PCE on your site is Don’t assume that all that PCE on your site is your client’syour client’syy
