Clay mineralogy and surface charge characteristics of basaltic soils from Western Samoa

University of South Pacific, School of Pure and Applied Sciences, Suva, Fiji
University of Wollongong, Australia
CSIRO, Australia
Queensland Department of Primary Industries, Australia

The clay mineralogy and surface charge characteristics of four basaltic soils from Western Samoa have been studied. The soils contained subordinate to dominant amounts of poorly ordered allophanic material in addition to varying amounts of crystalline free iron oxide minerals. Infrared studies revealed the presence of trace to subordinate amounts of kaolin minerals in all the soils. The surface charge-pH curves followed a constant potential model indicating the presence of substantial amounts of pH-dependent charge. Some negative charge was present, however, at pH Values as low as 3.0 and small quantities of positive charge were detected at pH values as high as 9. Values for PZC ranged from 2.2 to 3.9 and these were generally higher than the pHo determined by the Delta pH method.

This record provided courtesy of AGI/GeoRef.