Magnetic materials are found naturally in certain terrestrial and extra-terrestrial geological settings and can influence subsurface mapping and fluid transport and content estimations. With the advent of magnetic nanoparticle research there is also the possibility that these will be inputted in the environment on purpose, as research and industrial applications, or inadvertently as contaminants. The presence of magnetic materials is usually not considered in electromagnetic response modeling of saturated or partially saturated porous materials. This is because relative magnetic permeability of most natural materials is close to one, and thus should not affect propagation velocity calculations. The objective of this study was to investigate the effect of magnetic mineral inclusions on the velocity of propagation of an electromagnetic signal on porous materials saturated with water and its influence on volumetric water content estimation. The effective relative dielectric permittivity and magnetic permeability terms were modeled using Maxwell-Garnett, Polder-van Santen, Lichtenecker and Looyenga effective medium approximation equations. Data from three nonmagnetic soils saturated with water to varying degrees was used for preliminary model evaluations. The effect of magnetic minerals was tested by mixing magnetic sand with quartz sand at different proportions and measuring propagation velocity under fully water saturated conditions using Time Domain Reflectometry (TDR). Propagation velocity decreased with increasing magnetic volume fraction, while the effect of increasing magnetic fraction on attenuation factor was not markedly distinct. Water content estimations using models not accounting for magnetic inclusion substantially overestimated volumetric water content in saturated porous media.
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