Solução da equação de advecção-difusão estocástica para simular a concentração e deposição de amônia em confinamento bovino

Abstract

There is concern about environmental damage due to the considerable increase in air pollution, largely caused by intensive agriculture and livestock. In particular, large properties dedicated to intensive animal husbandry release considerable amounts of ammonia, NH3, both into the atmosphere, which acts as a precursor of greenhouse gases, and into the soil, whose effect over prolonged periods of time is the rise in acidity. The present work aims to quantify the concentration in the air, together with the flux of deposition in the soil, of the ammonia emitted by a bovine feedlot. To this end, we present the development and application of a mathematical model, using the three-dimensional advection-diffusion equation, in a transient regime, adopting a wind profile with a stochastic component and height-dependent turbulent diffusion coefficients, which simulates the dispersion. of the pollutant in the atmosphere. It is also considered unstable and stable atmospheric conditions. The model developed uses the combination of the GILTT method (Generalized Integral Laplace Transform Technique) with the method of separation of variables in the solution of the advection-diffusion equation. This joint use of methods has advantages over other methods that use only the GILTT technique, as it does not require numerical inversion of the Laplace transform, requiring less computational effort. Simulations were performed and compared with the experiment carried out in Victoria, Australia, indicating a good agreement between the simulated and experimental data.