Modeling the Impact of Heterogeneous Spatial Distribution of Soil Microbes on Pesticide Biodegradation at the Centimeter Scale

Tristan Babey 1 Jean-Raynald de Dreuzy 1 Marc Pinhiero 2 Patricia Garnier 2 Laure Vieublé 2 Alain Rapaport 3, 4
1 GR - Géosciences Rennes
2 AgroParisTech
3 MISTEA - Mathématiques, Informatique et STatistique pour l'Environnement et l'Agronomie
4 MODEMIC - Modelling and Optimisation of the Dynamics of Ecosystems with MICro-organisme
CRISAM - Inria Sophia Antipolis - Méditerranée , MISTEA - Mathématiques, Informatique et STatistique pour l'Environnement et l'Agronomie
Abstract : Micro-organisms and substrates may be heterogeneously distributed in soils. This repartition as well as transport mechanisms bringing them into contact are expected to impact the biodegradation rates. Pinheiro et al [2015] have measured in cm-large reconstructed soil cores the fate of an injection of 2,4-D pesticide for different injection conditions and initial distributions of soil pesticide degraders. Through the calibration of a reactive transport model of these experiments, we show that: i) biodegradation of diffusion-controlled pesticide fluxes is favored by a high Damköhler number (high reaction rate compared to flux rate); ii) abiotic sorption processes are negligible and do not interact strongly with biodegradation; iii) biodegradation is primarily governed by the initial repartition of pesticide and degraders for diffusion-controlled transport, as diffusion greatly limits the flux of pesticide reaching the microbial hotspot due to dilution. These results suggest that for biodegradation to be substantial, a spatial heterogeneity in the repartition of microbes and substrate has to be associated with intermittent and fast transport processes to mix them.
Document type :
Poster communications
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https://hal.inria.fr/hal-01246659
Contributor : Alain Rapaport <>
Submitted on : Friday, December 18, 2015 - 9:24:33 PM
Last modification on : Friday, April 5, 2019 - 8:17:40 PM

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Tristan Babey, Jean-Raynald de Dreuzy, Marc Pinhiero, Patricia Garnier, Laure Vieublé, et al.. Modeling the Impact of Heterogeneous Spatial Distribution of Soil Microbes on Pesticide Biodegradation at the Centimeter Scale . American Geophysical Union Fall Meeting (AGU 2015), Dec 2015, San Fransisco, United States. ⟨https://agu.confex.com/agu/fm15/meetingapp.cgi/Paper/69207⟩. ⟨hal-01246659⟩

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