NOTE EVALUATION OF SELECT IVE D ISSOLUTION EXTRACTANTS IN SOIL CHEMISTRY AND MINERALOGY BY D IFFERENTIAL

• Main Author: X -ray D Iffraction
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Greenland
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.610.3394; http://www.minersoc.org/pages/Archive-CM/Volume_20/20-4-515.pdf

Selective dissolution analysis is widely used to separate various soil minerals (e.g. oxides and oxyhydroxides of A1 and Fe, allophanes, phyllosilicates) from each other. Although a wide variety of reagents has been used for some of these determinations, few rigorous comparative studies have been attempted. Too often, reagents used to extract particular soil components are evaluated using geological or other specimens that may bear little resemblance to soil minerals formed by pedogenic processes; the investigations of Borggaard (1982) and Chao & Zhou (1983) are two recent examples of such an approach. Insufficient use has been made of difference infrared spectra (Wada & Greenland, 1970) obtained from soil samples. Ideally, soil extractants should be tested on phases actually present in a wide range of soils. In soils, crystals of minerals may differ considerably in size, order and degree of isomorphous substitution. Consequently any empirical selective dissolution technique that involves exposing soils to a fixed concentration of a particular eagent, under defined conditions of time and temperature, is unlikely consistently to completely extract only the component i was intended to remove yet never attack other phases. Even poorly-ordered