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Poster De Conférence Année : 2015

Modeling the impact of heterogeneous spatial distribution of soil microbes on pesticide biodegradation at the centimeter scale

Résumé

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.
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Dates et versions

hal-02796852 , version 1 (05-06-2020)

Identifiants

  • HAL Id : hal-02796852 , version 1
  • PRODINRA : 340326

Citer

Tristan Babey, Jean-Raynald de Dreuzy, Marc Pinhiero, Patricia P. Garnier, Laure L. 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 Francisco, United States. , 2015. ⟨hal-02796852⟩
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