Stable carbon isotope analysis of dissolved inorganic carbon (DIC) and dissolved organic carbon (DOC) in natural waters – Results from a worldwide pro!ciency test

RATIONALE: Stable carbon isotope ratios of dissolved inorganic (DIC) and organic carbon (DOC) are of particular
interest in aquatic geochemistry. The precision for this type of analysis is typically reported in the range of 0.1‰ to
0.5‰. However, there is no published attempt that compares !13C measurements of DIC and DOC among different
laboratories for natural water samples.
METHODS: Five natural water samples (lake water, seawater, two geothermal waters, and petroleum well water) were
analyzed for !13CDIC and !13CDOC values by !ve laboratories with isotope ratio mass spectrometry (IRMS) in an
international pro!ciency test.
RESULTS: The reported !13CDIC values for lake water and seawater showed fairly good agreement within a range of about
1‰, whereas geothermal and petroleum waters were characterized by much larger differences (up to 6.6‰ between
laboratories). !13CDOC values were only comparable for seawater and showed differences of 10 to 21‰for other samples.
CONCLUSIONS: This study indicates that scatter in !13CDIC isotope data can be in the range of several per mil for
samples from extreme environments (geothermal waters) and may not yield reliable information with respect to
dissolved carbon (petroleum wells). The analyses of lake water and seawater also revealed a larger than expected
difference and researchers from various disciplines should be aware of this. Evaluation of analytical procedures of the
participating laboratories indicated that the differences cannot be explained by analytical errors or different data
normalization procedures and must be related to speci!c sample characteristics or secondary effects during sample
storage and handling. Our results reveal the need for further research on sources of error and on method standardization.

[1] S. A. Rounds. Alkalinity and acid neutralizing capacity,
(version 4.0), U.S. Geological Survey Techniques of
Water-Resources Investigations (TRWI), Book 9, Chap.
A6., sec. 6.6, September, 2012. Available: http://water.
usgs.gov/owq/FieldManual/Chapter6/section6.6/ (accessed
10 March 2012).
[2] W. Stumm, J. J. Morgan. Aquatic Chemistry: Chemical
Equilibria and Rates in Natural Waters, (3rd edn.). John Wiley,
New York, 1996.
[3] J. A. C. Barth, J. Veizer, B. Mayer. Origin of particulate
organic carbon in the upper St. Lawrence: Isotopic
constraints. Earth Planet. Sci. Lett. 1998, 162, 111.
[4] D. T. Monteith, J. L. Stoddard, C. D. Evans, H. A. de Wit,
M. Forsius, T. Hogasen, A. Wilander, B. L. Skjelkvale,
D. S. Jeffries, J. Vuorenmaa, B. Keller, J. Kopacek, J. Vesely.
Dissolved organic carbon trends resulting from changes in
atmospheric deposition chemistry. Nature 2007, 450, 537.
[5] P. A. Raymond, N.-H. Oh, R. E. Turner, W. Broussard.
Anthropogenically enhanced "uxes of water and carbon
from the Mississippi River. Nature 2008, 451, 449.
[6] P. Schulte, R. van Geldern, H. Freitag, A. Karim, P. Négrel,
E. Petelet-Giraud, A. Probst, J. L. Probst, K. Telmer, J. Veizer,
J. A. C. Barth. Applications of stable water and carbon
isotopes in watershed research: Weathering, carbon cycling,
and water balances. Earth-Sci. Rev. 2011, 109, 20.
[7] D. H. Doctor, C. Kendall, S. D. Sebestyen, J. B. Shanley,
N.Ohte, E.W. Boyer.Carbon isotope fractionation of dissolved
inorganic carbon (DIC) due to outgassing of carbon dioxide
from a headwater stream. Hydrol. Processes 2008, 22, 2410.
[8] R. van Geldern, T. Hayashi, M. E. Böttcher, M. J. Mottl, J. A.
C. Barth, S. Stadler. Stable isotope geochemistry of pore
waters and marine sediments from the New Jersey shelf:
Methane formation and "uid origin. Geosphere 2013, 9, 96.
[9] A. Myrttinen, V. Becker, R. van Geldern, H. Würdemann, D.
Morozova, M. Zimmer, H. Taubald, P. Blum, J. A. C. Barth.
Carbon and oxygen isotope indications for CO2 behaviour
after injection: First results from the Ketzin site (Germany).
Int. J. Greenhouse Gas Control 2010, 4, 1000.
[10] J.-F. Hélie, C. Hillaire-Marcel. Sources of particulate and
dissolved organic carbon in the St Lawrence River: isotopic
approach. Hydrol. Processes 2006, 20, 1945.
[11] A. Stögbauer, H. Strauss, J. Arndt, V. Marek, F. Einsiedl,
R. van Geldern. Rivers of North-Rhine Westphalia revisited:
Tracing changes in river chemistry. Appl. Geochem.
2008, 23, 3290.
[12] J. Barth, J. Veizer. Three-component water balance to enable
protection of ecologically important ecosystems: an example
from the St. Lawrence River. Appl. Geochem. 2004, 19, 1637.
[13] Final Report on Fourth Interlaboratory Comparison
Exercise for !2H and !18O Analysis of Water Samples
(WICO2011), (Eds: M. Ahmad, P. Aggarwal, M. van Duren,
L. Poltenstein, L. Araguas, T. Kurttas, L. I. Wassenaar).
International Atomic Energy Agency, Vienna, Austria,
2012, p. 67.
[14] Available: http://isogeochem.wikispaces.com/.
[15] N. Assayag, K. Rivé, M. Ader, D. Jézéquel, P. Agrinier.
Improved method for isotopic and quantitative analysis of
dissolved inorganic carbon in natural water samples. Rapid
Commun. Mass Spectrom. 2006, 20, 2243.
[16] G. St-Jean. Automated quantitative and isotopic (13C)
analysis of dissolved inorganic carbon and dissolved organic
carbon in continuous-"ow using a total organic carbon
analyser. Rapid Commun. Mass Spectrom. 2003, 17, 419.
[17] C. Spötl. A robust and fast method of sampling and analysis
of !13 C of dissolved inorganic carbon in ground waters. Isot.
Environ. Health Stud. 2005, 41, 217.
[18] Available: http://nucleus.iaea.org/rpst/.
[19] Available: http://www.nist.gov/srm/.
[20] G. Capasso, R. Favara, F. Grassa, S. Inguaggiato, M. Longo.
On-line technique for preparing and measuring stable
carbon isotope of total dissolved inorganic carbon in water
samples (!13CTDIC). Ann. Geophys. 2005, 48, 159.
[21] G. G. Salata, L. A. Roelke, L. A. Cifuentes. A rapid and
precise method for measuring stable carbon isotope ratios
of dissolved inorganic carbon. Mar. Chem. 2000, 69, 153.
[22] D. Paul, G. Skrzypek, I. Fórizs. Normalization of measured
stable isotopic compositions to isotope reference scales – A
review. Rapid Commun. Mass Spectrom. 2007, 21, 3006.
[23] S. Emerson, J. Hedges. Chemical Oceanography and the Marine
Carbon Cycle. Cambridge University Press, Cambridge, 2008.
[24] M. P. Verma. A revised analytical method for HCO3 and
CO32– determinations in geothermal waters: An assessment
of IAGC and IAEA interlaboratory comparisons.
Geostandards Geoanal. Res. 2004, 28, 391.
[25] M. P. Verma. Determination of carbonic species in ground,
surface, geothermal, ocean and petroleum waters:
Theoretical aspects of CO2 chemistry in acid-base titration.
J. Anal. Chem. 2013, submitted.
[26] M. P. Verma, P. Brikle, D. Sánchez, in Proceedings World
Geothermal Congress 2010, Bali, Indonesia, 25–29 April, 2010.
[27] I. Clark, P. Fritz. Environmental Isotopes in Hydrology. Lewis,
Boca Raton, 1997.
[28] J. E. Spangenberg. Caution on the storage of waters and
aqueous solutions in plastic containers for hydrogen and
oxygen stable isotope analysis. Rapid Commun. Mass
Spectrom. 2012, 26, 2627.
[29] J. E. Spangenberg, T. W. Vennemann. The stable hydrogen
and oxygen isotope variation of water stored in
polyethylene terephthalate (PET) bottles. Rapid Commun.
Mass Spectrom. 2008, 22, 672.
[30] S. J. Taipale, E. Sonninen. The in"uence of preservationmethod
and time on the !13C value of dissolved inorganic carbon in
water samples. Rapid Commun. Mass Spectrom. 2009, 23, 2507.
[31] B. M. Van Breukelen,W. F. M. Röling, J. Groen, J. Grif!oen, H.
W. Van Verseveld. Biogeochemistry and isotope geochemistry
of a land!ll leachate plume. J. Contam. Hydrol. 2003, 65, 245.
[32] P. P. Videla, A. J. Farwell, B. J. Butler, D. G. Dixon.
Examining the microbial degradation of naphthenic acids
using stable isotope analysis of carbon and nitrogen. Water
Air Soil Pollut. 2009, 197, 107.
[33] W. A. Brand, in Handbook of Stable Isotope Analytical Techniques,
vol. I, (Ed: P. A. De Groot), Elsevier, Amsterdam, 2004.