PLSC204 Lecture 18: The Colloidal Fraction - Seat of Soil Chemical and Physical Activity
28 Jan 2019
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Document Summary
Chapter 8 the colloidal fraction - seat of soil chemical and physical activity. May be inherited from parent material or formed via the weathering of original (i. e. , primary) minerals or decomposition of organic residues. Small size, colloidal clays are <1 mm diameter . External, some have extensive internal sa as well. Surface charges, usually a net negative charge. Adsorb ions, cations (positive) more so than anions (negative) Adsorb - hold molecules of a gas or liquid as a film on the outside surface or on internal surfaces within the material. Fact that soil particles have water films on them. Types of soil colloids (differ greatly in properties) 1:1, 2:1, 2:1:1 (relative proportions of different types of layers making up each of the pages of the clay. Remember that sand and (mostly) silt are direct products of chemical and physical weathering processes (big small)
