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Preliminary study on Source Apportionment and Photolysis Process Identification of Selected POPs by CSIA. Z.L. Zhang, G. Yu, J. Cheng, X. Wang, J.L. Zhou Center for Environmental Research, University of Sussex, UK POPs Research Center, Tsinghua University, China. Outline. POPs and CSIA

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Preliminary study on Source Apportionment and Photolysis Process Identification of Selected POPs by CSIA

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Preliminary study on source apportionment and photolysis process identification of selected pops by csia

Preliminary study on Source Apportionment and Photolysis Process Identification of Selected POPs by CSIA

Z.L. Zhang, G. Yu, J. Cheng, X. Wang, J.L. Zhou

Center for Environmental Research, University of Sussex, UK

POPs Research Center, Tsinghua University, China


Outline

Outline

  • POPs and CSIA

  • Study Approach

  • Source Identification for POPs in the Environment

  • Isotopic Fractionation during Photolysis Process of POPs

  • Conclusion


Preliminary study on source apportionment and photolysis process identification of selected pops by csia

POPs

Persistent Organic Pollutants (POPs) are defined as ‘a set of organic compounds that:

(i) posses toxic characteristics;

(ii) are persistent;

(iii) are liable to bioaccumulate;

(iv) are prone to long-range atmospheric transport and deposition;

(v) can result in adverse environmental and human health effects at locations near and far from their sources’

Dirty Dozen: Aldrin, Endrin, Dieldrin, DDT, Chlordane, Hexachlorobenzene, Heptachlor, Mirex, Toxaphene, PCBs, PCDDs and PCDFs

Relative Candidates: PAHs, Hexchlorohexane(HCH), PBDEs...

Source: Convention on Long-Range Transboundary Air Pollution (CLRTAP), a protocol on persistent organic pollutants (POPs) under the auspices of the United Nations Economic Commission for Europe (UN-ECE)


Preliminary study on source apportionment and photolysis process identification of selected pops by csia

(‰)

Compound Specific Stable Isotope Analysis(CSIA)

  • Compound Specific Stable Isotope Analysis(CSIA) is an analytical Method which using Gas Chromatography-Isotope Ratio Mass Spectrometry (GC/IRMS) was developed in many application areas over the last decades.

  • Carbon: Radioactive Isotope-14C; Stable Isotope-12C(99.89%),13C(0.11%). Stable Isotopic composition expressed as δvalues in per mil (‰)

    Eq(1), Definition :

    where RA and Rst are the ratios of heavy isotope to the light isotope(R=13C/12C) in compound X and international standard(usually Vienna Peedee Belemnite, VPDB).


Preliminary study on source apportionment and photolysis process identification of selected pops by csia

EA

CO2

BSIA

Sample

µmol

d13C Bulk Sample

IRMS

950°C

V.S.

GC Separation

of all individual

compounds

GC/CIII

CO2 CO2

CO2

Sample

nmol

IRMS

CSIA

GC

950°C

d13C of all Individual

Compounds

Compound Specific Isotope Analysis(CSIA)


Preliminary study on source apportionment and photolysis process identification of selected pops by csia

Application of CSIA in Environmental Science

  • Allocate and distinguish sources of organic compounds on a local, regional, and global scale. e.g.PAHs, PCBs source apportionment…

  • Identify and quantify transformation process, characterize of elementary reaction mechanisms that govern product formation. e.g. microbial degradation process identification…


Preliminary study on source apportionment and photolysis process identification of selected pops by csia

Aim of this study

  • To develop sample pretreatment method for CSIA analysis organic pollutants in environmental matrices.

  • Apply the developed method for CSIA to identify the selected POPs sources

  • Investigate isotope fractionation by CSIA during the photolysis of selected POPs, to explore it as a potential tool for monitoring the photodegradation process.


Outline1

Outline

  • POPs and CSIA

  • Study Approach

  • Source Identification for POPs in the Environment

  • Isotopic Fractionation during Photolysis Process of POPs

  • Conclusion


Preliminary study on source apportionment and photolysis process identification of selected pops by csia

GC-C-IRMS FOR PAHs, OCPs, and PCBs standard


Preliminary study on source apportionment and photolysis process identification of selected pops by csia

Low Signal and UCM Encountered in CSIA Application

Signal is too low (<Detection limit)

Unresolved Complex Mixture (UCM)


Clean up by dmf pentane biphasic system lle

Clean up by DMF-Pentane biphasic system (LLE)

95%DMF

H2O

HEX

DMF

HEX

PET

Cu、N2

PET

HEX+

DCM

Hex/DCM

PSE

Principle:DMF (Dimethylformamide) –Pentane(PET) biphasic system,PAHs、PCBs etc. are easy to stay in DMF phase,the UCM will be removed from the system by affinity to pentane.


Preliminary study on source apportionment and photolysis process identification of selected pops by csia

The result of LLE Clean up for Sediment Sample


Preliminary study on source apportionment and photolysis process identification of selected pops by csia

LOD, Recovery, RSD of POPs for CSIA

a

LOD1、LOD2 are calculated for LOD of POPs- POPs-δ13C by equation C = M /(LNc)、C =(S-b)/ k =(100-b)/ k respectively .


Outline2

Outline

  • POPs and CSIA

  • Study Approach

  • Source Identification for POPs in the Environment

  • Isotopic Fractionation during Photolysis Process of POPs

  • Conclusion


Preliminary study on source apportionment and photolysis process identification of selected pops by csia

UCM Removed by DMF-Pentane biphasic system


Preliminary study on source apportionment and photolysis process identification of selected pops by csia

-26.2~-23.7‰

Source Identified by Compound Specific Isotope Analysis(CSIA)


Outline3

Outline

  • POPs and CSIA

  • Study Approach

  • Source Identification for POPs in the Environment

  • Isotopic Fractionation during Photolysis Process of POPs

  • Conclusion


Preliminary study on source apportionment and photolysis process identification of selected pops by csia

Isotope Fractionation for Compound during Reaction Process

Rayleigh equation : Rt/Ro = f (α-1) …… (2)

α: isotope fractionation factor ; Rt and Ro are the isotope compositions, f is the fraction of substrate remaining (f) which equals to Ct/Co, and Ct and Co are the concentrations of the compound at times t and zero, respectively.

ε=(α-1)×1000 ……(3)

ε: enrichment factor

ln((10-3×δ13Ct+1)/(10-3×δ13 Co))=(α-1)×lnf ……(4)


Preliminary study on source apportionment and photolysis process identification of selected pops by csia

Primarily Observed Carbon Isotope Effect Occurred in the photolysis Process of PCBs


Preliminary study on source apportionment and photolysis process identification of selected pops by csia

Photochemical degradation of HCB in hexane

t1/2 = 387min, r = 0.997

t1/2 = 387min, r = 0.997

t1/2 = 394min, r = 0.997


Preliminary study on source apportionment and photolysis process identification of selected pops by csia

Relative conversion and Mass balance over time for photochemical process


Preliminary study on source apportionment and photolysis process identification of selected pops by csia

HCB photochemical process at different time

t=600min

t=0min

t=1200min


Preliminary study on source apportionment and photolysis process identification of selected pops by csia

δ13C values for HCB in different concentration


Preliminary study on source apportionment and photolysis process identification of selected pops by csia

The δ13C value of HCB and PCB versus percent conversion


Preliminary study on source apportionment and photolysis process identification of selected pops by csia

δ13C value of the residual HCB versus fraction remaining

ε= -14.8

n=28, r=0.96


Preliminary study on source apportionment and photolysis process identification of selected pops by csia

δ13C value of the product PCB versus fraction producing

ε = 22.7

n=14, r=0.84


Preliminary study on source apportionment and photolysis process identification of selected pops by csia

Isotope Fractionation for Compound during Reaction Process

Rt/Ro = f (α-1) …… (2)

α: isotope fractionation factor ; Rt and Ro are the isotope compositions, f is the fraction of substrate remaining (f) which equals to Ct/Co, and Ct and Co are the concentrations of the compound at times t and zero, respectively.

ε=(α-1)×1000 ……(3)

ε: enrichment factor

ln((10-3×δ13Ct+1)/(10-3×δ13 Co))=(α-1)×lnf ……(4)


Outline4

Outline

  • POPs and CSIA

  • Study Approach

  • Source Identification for POPs in the Environment

  • Isotopic Fractionation during Photolysis Process of POPs

  • Conclusion


Conclusion

Conclusion

  • The method of CSIA applied in POPs study is primarily established, include sample pretreatment and the related analytical properties.

  • In identifying the source of POPs, CSIA is primarily applied in PAHs source apportionment.

  • Isotopic Fractionation during Photolysis Process of HCB indicated that CSIA might serve as a potential tool to monitor the photo-chemical process for POPs in environment.


Preliminary study on source apportionment and photolysis process identification of selected pops by csia

Thank You!


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