Evaluation of the Clay Fraction in some Danish Soils, Making Use of High-Gradrent Magnetic Separation (HGMS)

Abstract

After removal of the ‘free Fe-oxyhydroxides’, a high-gradient magnetic separation (HGMS) procedure was used to separate the minerals of the clay fraction in soil samples from different horizons of two Alfisols, a Mollisol, an Ultisol and a Spodosol into a magnetic and a non-magnetic fraction. The magnetic fraction constituted 12–19% of the total clay fraction in the Alfisols, 28–35% in the Mollisol, 9–10% in the Ultisol and 11–16% in the Spodosol. X-Ray diffraction (XRD), Mossbauer spectroscopy and total elemental analysis (TEA) were used for the characterization of the different fractions. The CBD-treated magnetic clay contained mainly paramagnetic 2:1 layer silicate clay minerals, including hydroxy-interlayered clay minerals (HICM) high in Fe. The nonmagnetic clay was composed of diamagnetic minerals such as quartz, feldspars, gibbsite, kaolinite and the diamagnetic 2:1 layer silicate clay minerals.

Key Words:

• HGMS
• soil clay
• Danish soils