Simulação do comportamento de íons em solos altamente intemperizados utilizando o modelo de capacitância constante
Abstract
Agriculture is a very important economic activity in Brazil, and almost all cultures are
grown directly on the soil. Thus, improve the knowledge of soil behavior is fundamental
for the improvement of agricultural practices potentially harmful to the environment.
The acric Oxisols are highly weathered soils, present in large and important productive
productive regions of Brazil, and there are few studies using surface complexation models
for description of ion adsorption processes in these soils. This work aimed at verifying
the adequacy of the constant capacitance model in describing the adsorption of copper,
cadmium, nickel and zinc in Latosols acric. This verification was done by analysing simulation
residues and comparing surface potencial simuations with the values of PESN. All
cations used are plant nutrients or important trace elements with respect to environmental
contamination. In this work three soils were considered,Oxisol acric (LVwf), Oxisoil
acric (LAw) and Eutric Kandiudalf (NVef). Measurements of their chemical (CEC, pH,
Organic carbon, etc,), mineralogical (kaolinite and gibbsite) and physical (distribution of
particle size and specific surface area) properties as well as adsorption, were obtained from
literature. The adsorption envelope measurements collected in the literature were generally
very consistent, and the cadmium and zinc measures are more behaved distribution
in relation to other cations. Capacitance constant model were performed by a iterative
computer program named FITQL. The constant capacitance model proved reasonably
adequate to simulate the behavior of all the cations of the study. Simulations for nickel
were relatively inconsistent regarding the experimental measurements. In most cases it
was not possible to make appropriate distinctions between measurements and simulations
for surface and depth, between the three concentrations of supporting electrolyte. All simulations
of waste presented well-defined structure, unlike that normally expected. This
may occur mainly due to methodological errors or errors inherent to the model, however,
examples were not found in the literature regarding the waste generated by the simulation
model for a proper comparison.