Magnetic susceptibility in environmental applications: comparison of fieldprobes

Magnetic susceptibility is a convenient measure of determining the concentr ation of (ferri)magnetic minerals by rapid and non-destructive means. The p resent paper aims at defining the characteristics of three field probes, co mmonly used to measure magnetic susceptibility: the Bartington MS2D and MS2 F probes, and the Geofyzika KT-5 Kappameter. Two other instruments, the Bar tington MS2B probe and Geofyzika KLY-2 Kappabridge are used for calibration . The results show that "true" magnetic values are either over- (196%) or u nderestimated (42%) in comparison with MS2D probe when the MS2F probe is bu ried in or placed on the surface of cement samples. The KT-5 Kappameter giv es true values of susceptibility (102%) as referred to the KLY-2 Kappabridg e, and the MS2D probe reads 90% of true values based on the MS2B probe. Dep th penetration of each sensor is only a few centimeters. At a depth of 6 cm , the MS2D probe integrates 90% of the susceptibility signal. The KT-5 Kapp ameter records about 90% in the first 2 cm. For the MS2F probe, almost all of the signal is located within 1 cm around the sensor. (C) 1999 Elsevier S cience B.V. All rights reserved.