EGU2020-11754
https://doi.org/10.5194/egusphere-egu2020-11754
EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

From Chemostat/Retentostat to Soil: Modeling bioavailability limitations on atrazine degradation

Luciana Chavez Rodriguez1, Holger Pagel1, Thilo Streck1, and Brian Ingalls2
Luciana Chavez Rodriguez et al.
  • 1Institut für Bodenkunde und Standortslehre, Biogeophysik, University of Hohenheim, Stuttgart, Germany (l.chavezrodriguez@uni-hohenheim.de)
  • 2Department of Applied Mathematics, University of Waterloo, Waterloo, Canada (bingalls@uwaterloo.ca)

Atrazine has been banned in Europe since 2003, but is still a widely used herbicide in the rest of the world. It presents an environmental threat due to its environmental persistence and ecotoxicity. Although soil bacteria have evolved effective biodegradation pathways, atrazine persists in soils at low concentrations making soils to potential continuous sources of groundwater pollution. Experiments using isotopologues of atrazine in simplified systems (chemostat and retentostat) indicate, that limited mass transfer across the cell membrane controls atrazine degradation at low concentrations. We extended and parameterized an existing mathematical model of atrazine degradation in the chemostat/retentostat system using laboratory data. By integrating this modeling approach into a more complex soil model, the role of mass transfer across bacterial cell membranes can be assessed against other rate limiting processes of atrazine biodegradation in soil at low concentrations.

How to cite: Chavez Rodriguez, L., Pagel, H., Streck, T., and Ingalls, B.: From Chemostat/Retentostat to Soil: Modeling bioavailability limitations on atrazine degradation, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11754, https://doi.org/10.5194/egusphere-egu2020-11754, 2020

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Presentation version 1 – uploaded on 30 Apr 2020
  • CC1: Comment on EGU2020-11754, Stefan Reichenberger, 08 May 2020

    I though the principal metabolites of atrazine in temperate climates were DIA and DEA, and that hydroxyatrazine mainly occurs in tropical climates. Have you analyzed DEA and DIA as well?

    • AC2: Reply to CC1, Luciana Chavez Rodriguez, 08 May 2020

      Yes, the degradation of atrazine, at least from my knowledge, follows different degradation pathways leading to the formation of different metabolites, and it depends on which bacteria or bacteria consortia is found. For this experiment, Arthrobacter aurescens was used, and this bacterium follows the degradation pathway: atrazine-hydroxyatrazine-cyanuric acid (this can be further used in the absence of alternative sources of nitrogen). I have, therefore, only included hydroxyatrazine in this model, but I have some other models that include DIA and DEA. 

  • CC2: Comment on EGU2020-11754, Stefan Reichenberger, 08 May 2020

    What bacteria did you use in your experiments?

    • AC1: Reply to CC2, Luciana Chavez Rodriguez, 08 May 2020

      The experiments were done with Arthrobacter aurescens. I did not do the experiments myself, but it is a collaboration with other groups and there are papers on that (, , ).

  • CC3: Comment on EGU2020-11754, Stefan Reichenberger, 08 May 2020

    What types of equations did you use in your compartment model? First order, Michaelis-Menten, other?
    (Sorry, I probably have missed this in the chat.)

    • AC3: Reply to CC3, Luciana Chavez Rodriguez, 08 May 2020

      For the degradation fluxes, I used mainly Michaelis-Menten kinetics. This is basically the core of the model. However, other fluxes such as the mass-transfer across the membrane are only simple diffusion (Fick's law), and the maintenance flux follows a Compromise maintenance model (). I hope it helps. 

  • CC4: Comment on EGU2020-11754, Stefan Reichenberger, 08 May 2020

    Muchas gracias por las explicaciones!

    • AC4: Reply to CC4, Luciana Chavez Rodriguez, 08 May 2020

      Muchas gracias por el interés en mi trabajo.