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## Dynamic mathematical model of oxygen and carbon dioxide exchange between soil and atmosphere

Gaseous transport through soil in the presence of soil

microorganisms has been investigated. More recently, modeling of

gaseous transport in the unsaturated zone has been investigated.

However, the problem of mathematical model of oxygen and carbon

dioxide transport through soil, as affected by the climatic

conditions, the transport of soil water, and the biological

activities, has not been studied.

The problem of time-dependent diffusion of oxygen and carbon

dioxide through plant canopy and soil system, as affected by the

infiltration and evaporation of soil water and the rate of

consumption of oxygen and production of carbon dioxide by plant

leaves and roots and soil microorganisms was studied, using a

one-dimensional mathematical model. This model consists of four sets

of non-linear partial differential field equations, which describe

the time-dependent simultaneous transport of water, heat, oxygen, and

carbon dioxide through the soils.

Finite difference methods were used to find the approximate

solutions for the four sets of non-linear partial differential field

equations. The field equations for the transport of water and heat

were approximated by using the implicit scheme. The field equations

for the transport of oxygen and carbon dioxide were approximated by

using the explicit scheme. A computer program was written in Fortran

code to conduct the simulations of the mathematical model.

Simultaneous transport of water, heat, oxygen, and carbon dioxide

through the unsaturated Indio loam soil, through the compacted and

the non-compacted soil during infiltration, redistribution, and

evaporation of soil water was evaluated. Diffusion of oxygen and

carbon dioxide within the canopy and soil system was examined.

Several different functions for the root elongation and the root

oxygen consumption rates were used. Root elongation rate was chosen

to depend on oxygen or carbon dioxide concentrations, in addition to

being a function of time. Root oxygen consumption rate was assumed

to be a function of root age, in addition to being a function of

oxygen or carbon dioxide concentrations. Results illustrate that the

behaviors of the simultaneous transport of water, heat, oxygen, and

carbon dioxide were well predicted by the model. / Graduation date: 1991

Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/37466 |

Date | 27 September 1990 |

Creators | Ou-yang, Ying |

Contributors | Boersma, Larry |

Source Sets | Oregon State University |

Language | en_US |

Detected Language | English |

Type | Thesis/Dissertation |

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