Theoretical analysis of coupled effects of microbe and root architecture on methane oxidation in vegetated landfill covers

S. Feng, A. K. Leung, C. W. W. Ng, H. W. Liu (Lead / Corresponding author)

Research output: Contribution to journalArticle

16 Citations (Scopus)
202 Downloads (Pure)

Abstract

Reduction of soil moisture by plant root-water uptake could improve soil aeration for microbial aerobic methane oxidation (MAMO) in a landfill cover, but excessive soil moisture removal could suppress microbial activity due to water shortage. Existing models ignore the coupled microbe-vegetation interaction. It is thus not known whether the presence of plants is beneficial or adverse to MAMO. This study proposes a newly-improved theoretical model that couples the effects of root-water uptake and microbial activity for capturing water-gas flow and MAMO in unsaturated soils. Parametric studies are conducted to investigate the effects of root characteristics and transpiration rate on MAMO efficiency. Uniform, parabolic, exponential and triangular root architectures are considered. Ignoring the effects of water shortage on microbe over-predicts the MAMO efficiency significantly, especially for plants with traits that give high root-water uptake ability (i.e., uniformly-rooted and long root length). The effects of plants on MAMO efficiency depends on the initial soil moisture strongly. If the soil is too dry (i.e., close to the permanent wilting point), plant-water uptake, with any root architecture considered, would reduce MAMO efficiency as further soil water removal by plants suppresses microbial activity. Plants with exponential or triangular root architectures could preserve 10% higher MAMO than the other two cases. These two architectures are more capable of minimizing the adverse effects of root-water uptake due to microbial water shortage. This implies that high-water-demand plants such as those with long root length and with uniform or parabolic root architectures require more frequent irrigation to prevent from excessive reduction of MAMO efficiency.
Original languageEnglish
Article number2393
Pages (from-to)1954-1964
Number of pages11
JournalScience of the Total Environment
Volume599-600
Early online date23 May 2017
DOIs
Publication statusPublished - 1 Dec 2017

Keywords

  • Plant root-water uptake
  • Microbial aerobic methane oxidation
  • Coupled water-gas flow
  • Numerical simulation

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