Ajuste de parâmetros de transporte de solutos no solo utilizando Matlab 6.5

Abstract

RESUMO:O sucesso na utilização de modelos matemáticos no estudo do transporte de íons no solo está intimamente ligado à precisão com que os parâmetros de transporte envolvidos neste processo são estabelecidos. De maneira geral, tais parâmetros são determinados mediante a resolução de um problema de otimização não linear em que os dados experimentais, obtidos em ensaios de deslocamento miscível, são ajustados a um modelo teórico. Neste sentido, a utilização de softwares de alta performance no ajuste destes parâmetros mostra-se vantajosa, uma vez que, além da consistência e da disponibilidade de ferramentas numéricas preexistentes, possibilita a incorporação de novas rotinas de acordo com o fenômeno que se queira simular. Sendo assim, este trabalho teve como objetivo desenvolver, em ambiente MATLAB 6.5, uma rotina computacional para a otimização dos seguintes parâmetros de transporte: fator de retardamento (R) e coeficiente de dispersão (D). A rotina desenvolvida foi aplicada a dados experimentais de três ensaios de deslocamento miscível do íon potássio em colunas preenchidas com um Latossolo Vermelho--Amarelo, fase arenosa. A qualidade dos ajustes obtidos foi avaliada utilizando-se do coeficiente de exatidão. Concluiu-se que a rotina proposta apresentou ótimo desempenho, o que, além de reforçar a consistência do método numérico utilizado, indica que a rotina proposta neste trabalho pode contribuir com o avanço dos estudos teóricos da dinâmica da água e de solutos em meios porosos não saturados. PALAVRAS-CHAVE: curva de distribuição de efluentes, rotina computacional, dinâmica de solutos. ADJUSTMENT OF SOIL SOLUTE TRANSPORT PARAMETERS WITH MATLAB 6.5 ABSTRACT:The successful use of mathematical models in studies of solute transport in soil is dependent on the accuracy to which the transport parameters involved in this process can be specified. In general, these parameters are determined by using nonlinear optimization techniques to fit theoretical models to experimental data obtained in miscible displacement experiments. The use, therefore, of high-performance software to evaluate these parameters appears to be advantageous since, in addition to consistency and the availability of pre-existing numerical routines, such software allows for the incorporation of new routines that are specifically tailored for the phenomena being simulated. The main objective of this study was to develop a MATLAB 6.5 computational routine to optimize the evaluation of retardation factor (R) and dispersion coefficient (D) from miscible displacement data. This routine was applied to experimental data from three miscible displacement studies of potassium transport in columns filled with an Oxisol of sandy phase, with the setting quality being assessed by the coefficient of accuracy. The proposal routine gave excellent results, reinforcing the consistency of the numerical method used, and indicating that this routine can contribute to the advancement of theoretical studies of the solute-water dynamics in unsaturated porous media.

Transport Parameters of Potassium From Different Sources in Soil Columns

“…Water dislocation breadth and further groundwater contamination by ions and other dissolved elements can be characterized by studies on miscible displacement, which enable us to comprehend the characteristics of certain elements, along with their mobility, persistence, and interaction with the soil (Souza et al, 2011). However, it is important to highlight that the presence of inorganic and organic constituents (competitors for sorption sites) in the soil solution favors the leaching of those not retained, which should alert us to the danger of groundwater pollution (Martinez et al, 2001;Shaheen et al, 2013).…”

Method to evaluate the efficiency of manual overhead irrigation in citrus rootstock liner production

“…However, manual overhead irrigation has no water flow or uniformity control, resulting in uneven irrigation. Water and nutrient solution excess is directly disposed into the soil and may cause salinization, in addition to serious environmental impacts and increase of production costs (GIRARDI et al, 2010;SOUZA et al, 2011b;FERRAREZI et al, 2012). Adequate irrigation management and mitigation of any environmental impacts are necessary for sustainable plant production, especially because the current regulations do not specify recommendations for water and nutrient management.…”

Effect of companion ion on nitrate displacement through transport parameters analysis

“…Through miscible displacement studies, it is possible to know the characteristic of certain chemicals, such as its interaction with environment, mobility and persistence in soil (SOUZA et al, 2011). Knowing such characteristics and soil hydrodynamics and hidrodispersive, which associated with simulation models, provides a better understanding of solute displacement processes in soil.…”

“…Knowing such characteristics and soil hydrodynamics and hidrodispersive, which associated with simulation models, provides a better understanding of solute displacement processes in soil. Therefore, these concepts are characterized as important tools for contamination risk assessment to the environment and its further impacts, besides preventing future damages (CARMO et al, 2010;SOUZA et al, 2011).…”

“…On the other hand, these models would succeed if transport parameter, which are input values, could be quantified (SOUZA et al, 2011).…”