Multiphase flow and transport simulations were conducted to investigate the impact of soil heterogeneity and non-aqueous phase liquid (NAPL) presence on the distribution of stable carbon isotope signatures during contaminant transport with biodegradation. At a later time during the simulation of a homogeneous case with dense NAPL presence, significant carbon isotope signature (δ13C) values could only be observed in a narrow area at the bottom of the aquifer where NAPL accumulated. After this, the δ13C distribution remained relatively stable for a long time until all NAPL was dissolved into the groundwater and removed via biodegradation and groundwater flushing. These characteristics of δ13C distribution may only be captured when considering NAPL migration and dissolution. The simulation results demonstrated that δ13C values and their distribution significantly differed between the heterogeneous case and the homogeneous case, with respect to the maximum δ13C value and the shape of δ13C contours. When reaction rate constant varied for each soil type (each grid block) by relating it to soil permeability, the δ13C distribution demonstrated different patterns. In addition to geological heterogeneity, this indicates that the distribution of δ13C highly depends on the biological heterogeneity in the field. Therefore, this study suggests that, to avoid misinterpretation of isotope signature changes, geological and biological soil heterogeneities should be investigated. If a NAPL is present in the system, the NAPL phase transport and dissolution should be considered in addition to dissolved phase transport.
This is a preview of subscription content, log in to check access.
Buy single article
Instant access to the full article PDF.
Price includes VAT for USA
Subscribe to journal
Immediate online access to all issues from 2019. Subscription will auto renew annually.
This is the net price. Taxes to be calculated in checkout.
Ahad, J. M. E., Sherwood Lollar, B., Edwards, E. A., Slater, G. F., Sleep, B., & E. (2000). Carbon isotope fractionation during anaerobic biodegradation of toluene: implications for intrinsic bioremediation. Environmental Science & Technology, 34(5), 892–896.
Bear, J. (1972). Dynamics of fluids in porous media (environmental science series). New York: American Elsevier Publishing Co..
Beller, H. R., Kane, S. R., Legler, T. C., McKelvie, J. R., Sherwood Lollar, B., Pearson, F., et al. (2008). Comparative assessments of benzene, toluene, and xylene natural attenuation by quantitative polymerase chain reaction analysis of a catabolic gene, signature metabolites, and compound-specific isotope analysis. Environmental Science & Technology, 42(16), 6065–6072.
Bloom, Y., Aravena, R., Hunkeler, D., Edwards, E., & Frape, S. K. (2000). Carbon isotope fractionation during microbial dechlorination of Trichloroethene, cis-1,2-Dichloroethene, and vinyl chloride: implications for assessment of natural attenuation. Environmental Science & Technology, 34(13), 2768–2772.
Bouchard, D., Hunkeler, D., Gaganis, P., Aravena, R., Hohener, P., Broholm, M. M., et al. (2008). Carbon isotope fractionation during diffusion and biodegradation of petroleum hydrocarbons in the unsaturated zone: field experiment at Værløse Airbase, Denmark, and modeling. Environmental Science & Technology, 42, 596–601.
Brooks, R. H., & Corey, A. T. (1964). Hydraulic properties of porous media. In Hydrology papers, 3. Fort Collins: Colorado State University.
Chiogna, G., Cirpka, O. A., Grathwohl, P., & Rolle, M. (2011). Relevance of local compound-specific transverse dispersion for conservative and reactive mixing in heterogeneous porous media. Water Resources Research, 47(7). doi:10.1029/2010wr010270.
Craig, H. (1953). The geochemistry of the stable carbon isotopes. Geochimica et Cosmochimica Acta, 3, 53–92.
Elsner, M., Zwank, L., Hunkeler, D., & Schwarzenbach, R. P. (2005). A new concept linking observable stable isotope fractionation to transformation pathways of organic pollutants. Environmental Science & Technology, 39(18), 6896–6916.
Fischer, A., Gehre, M., Breitfeld, J., Richnow, H. H., & Vogt, C. (2009). Carbon and hydrogen isotope fractionation of benzene during biodegradation under sulfate-reducing conditions: a laboratory to field site approach. [Research support, non-U.S. Gov't]. Rapid Communications in Mass Spectrometry, 23(16), 2439–2447. doi:10.1002/rcm.4049.
Hunkeler, D., Chollet, N., Pittet, X., Aravena, R., Cherry, J. A., & Parker, B. L. (2004). Effect of source variability and transport processes on carbon isotope ratios of TCE and PCE in two sandy aquifers. Journal of Contaminant Hydrology, 74(1–4), 265–282. doi:10.1016/j.jconhyd.2004.03.003.
Hunkeler, D., Meckenstock, R. U., Sherwood Lollar, B., Schmidt, T. C., & Wilson, J. T. (2008). A guide for assessing biodegradation and source identification of organic ground water contaminants using compound specific isotope analysis (CSIA). Office of Research and Development, National Risk Management Research Laboratory, Ada.
Kueper, B. H. (1989). The behaviour of dense, non-aqueous phase liquid contaminants in heterogeneous porous media. Waterloo: University of Waterloo.
Lujan, C. A. (1985). Three-phase flow analysis of oil spills in partially water-saturated soils. Fort Collins: Colorado State University.
Mancini, S. A., Ulrich, A. C., Lacrampe-Couloume, G., Sleep, B., Edwards, E. A., & Sherwood Lollar, B. (2003). Carbon and hydrogen isotopic fractionation during anaerobic biodegradation of benzene. Applied and Environmental Microbiology, 69(1), 191–198. doi:10.1128/aem.69.1.191-198.2003.
McClure, P. D., & Sleep, B. E. (1996). Simulation of bioventing for soil and ground-water remediation. Journal of Environmental Engineering, 122(11), 1003–1012.
Montgomery, J. H. (1995). Groundwater chemicals desk reference (2nd ed.). CRC Press, Inc., Lewis Publishers, US.
Morrill, P. L., Lacrampe-Couloume, G., & Sherwood Lollar, B. (2004). Dynamic headspace: a single-step extraction for isotopic analysis of microg/L concentrations of dissolved chlorinated ethenes. Rapid Communications in Mass Spectrometry, 18(6), 595–600. doi:10.1002/rcm.1372.
Morrill, P. L., Sleep, B. E., Seepersad, D. J., McMaster, M. L., Hood, E. D., LeBron, C., et al. (2009). Variations in expression of carbon isotope fractionation of chlorinated ethenes during biologically enhanced PCE dissolution close to a source zone. Journal of Contaminant Hydrology, 110(1–2), 60–71.
Sherwood Lollar, B., Sleep, B., Witt, M., Klecka, G. M., Harkness, M., & Spivack, J. (2001). Stable carbon isotope evidence for intrinsic bioremediation of tetrachloroethene and trichloroethene at area 6, Dover Air Force Base. Environmental Science & Technology, 35(2), 261–269.
Sleep, B. E., & Sykes, J. F. (1993a). Compositional simulation of groundwater contamination by organic compounds: 1. Model development and verification. Water Resources Research, 29(6), 1697–1708.
Sleep, B. E., & Sykes, J. F. (1993b). Compositional simulation of groundwater contamination by organic compounds: 2. Model applications. Water Resources Research, 29(6), 1709–1718.
Suarez, M. P., & Rifai, H. S. (1999). Biodegradation rates for fuel hydrocarbons and chlorinated solvents in groundwater. Bioremediation Journal, 3(4), 337–362. doi:10.1080/10889869991219433.
van Genuchten, M. T. (1980). A closed-form equation for predicting the hydraulic conductivity of unsaturated soils. Soil Science Society of America Journal, 44(5), 892–898.
Xu, B. S., Sherwood Lollar, B., Passeport, E., & Sleep, B. E. (2016). Diffusion related isotopic fractionation effects with one-dimensional advective-dispersive transport. Science of the Total Environment, 550, 200–208. doi:10.1016/j.scitotenv.2016.01.114.
Yaws, C. L. (1995). Handbook of transport property data: Viscosity, thermal conductivity, and diffusion coefficients of liquids and gases. Houston: Gulf Pub. Co..
Zwank, L., Berg, M., Schmidt, T. C., & Haderlein, S. B. (2003). Compound-specific carbon isotope analysis of volatile organic compounds in the low-microgram per liter range. Analytical Chemistry, 75(20), 5575–5583.
This work was supported by National Natural Science Foundation of China [grant number 41172204]. We would also like to express our gratitude to Professor Brent Sleep at the University of Toronto, for his insights and expertise that greatly assisted this research.
About this article
Cite this article
Zhou, Z., Cui, Z. & Xu, S. Impact of Soil Heterogeneity and NAPL Presence on Stable Carbon Isotope Signature Distribution During Reactive Transport. Water Air Soil Pollut 228, 408 (2017). https://doi.org/10.1007/s11270-017-3528-9
- Stable isotope fractionation
- Isotope signature distribution
- Soil permeability
- Non-aqueous phase liquid