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| Titel |
Self-organizing biochemical cycle in dynamic feedback with soil structure |
| VerfasserIn |
Nadezda Vasilyeva, Artem Vladimirov, Alexander Smirnov, Sergey Matveev, Evgeniy Tyrtyshnikov, Anna Yudina, Evgeniy Milanovskiy, Evgeniy Shein |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250129915
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| Publikation (Nr.) |
 EGU/EGU2016-10089.pdf |
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| Zusammenfassung |
| In the present study we perform bifurcation analysis of a physically-based mathematical
model of self-organized structures in soil (Vasilyeva et al., 2015). The state variables in this
model included microbial biomass, two organic matter types, oxygen, carbon dioxide, water
content and capillary pore size. According to our previous experimental studies, organic
matter affinity to water is an important property affecting soil structure. Therefore, organic
matter wettability was taken as principle distinction between organic matter types in this
model. It considers general known biological feedbacks with soil physical properties
formulated as a system of parabolic type non-linear partial differential equations with
elements of discrete modeling for water and pore formation. The model shows complex
behavior, involving emergence of temporal and spatial irregular auto-oscillations from
initially homogeneous distributions. The energy of external impact on a system was defined
by a constant oxygen level on the boundary. Non-linear as opposed to linear oxygen diffusion
gives possibility of modeling anaerobic micro-zones formation (organic matter
conservation mechanism). For the current study we also introduced population
competition of three different types of microorganisms according to their mobility/feeding
(diffusive, moving and fungal growth). The strongly non-linear system was solved
and parameterized by time-optimized algorithm combining explicit and implicit
(matrix form of Thomas algorithm) methods considering the time for execution of the
evaluated time-step according to accuracy control. The integral flux of the CO2 state
variable was used as a macroscopic parameter to describe system as a whole and
validation was carried out on temperature series of moisture dependence for soil
heterotrophic respiration data. Thus, soil heterotrophic respiration can be naturally
modeled as an integral result of complex dynamics on microscale, arising from
biological processes formulated as a sum of state variables products, with no need to
introduce any saturation functions, such as Mikhaelis-Menten type kinetics, inside the
model.
Analyzed dynamic soil model is being further developed to describe soil structure
formation and its effect on organic matter decomposition at macro-scale, to predict changes
with external perturbations. To link micro- and macro-scales we additionally model
soil particles aggregation process. The results from local biochemical soil organic
matter cycle serve as inputs to aggregation process, while the output aggregate size
distributions define physical properties in the soil profile, these in turn serve as dynamic
parameters in local biochemical cycles. The additional formulation is a system of
non-linear ordinary differential equations, including Smoluchowski-type equations for
aggregation and reaction kinetics equations for coagulation/adsorption/adhesion
processes.
Vasilyeva N.A., Ingtem J.G., Silaev D.A. Nonlinear dynamical model of microbial growth
in soil medium. Computational Mathematics and Modeling, vol. 49, p.31-44, 2015
(in Russian). English version is expected in corresponding vol.27, issue 2, 2016. |
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