Monday, November 5, 2007
115-6

Mineralogy and Heavy Metal Distribution in Soils along a Serpentinized/ultramafic Transect of the Great Dyke, Zimbabwe.

Courage Bangira, C. Tom Hallmark, and Richard H. Loeppert. Soil & Crop Sciences, Texas A&M University, 370 Olsen Blvd, College Station, TX 77843-2474

Soils formed on ultramafic/serpentinized areas present some great agronomic, ecological and environmental challenges. The objective of this study was to describe the relationships between parent material, topographical position, soil mineralogy and heavy metal composition across a toposequence of the ultramafic/serpentinized Great Dyke of Zimbabwe. Soil samples were taken across the transect, and their mineralogy and elemental composition (Ca, Mg, K, Cr, Co, Fe, Mn and Ni) determined. Mineralogy of finely ground sand and silt fractions and oriented clay fractions were determined by XRD. Mineralogy was substantiated by FTIR, SEM, and x-ray microprobe of individual particle-size separates. Elemental composition was determined by INAA, ICP and FAAS following digestion with HF/HNO3/H202. The results indicated the predominance of iron oxides (hematite, magnetite, maghemite), enstatite, serpentine and quartz in the sand and silt fractions, and talc, serpentine and smectite in the clay fractions. Talc and kaolinite were associated with both crest and back slope positions, with smectite being an additional mineral on the back slope. The respective occurrence of serpentine and smectite on the foot slope and backslope positions clearly reflected the parent material and topography as important soil forming factors in this area.

Back to Symposium--Distribution of Soil Minerals in Landscapes (includes Graduate Student Competition): II
Back to S09 Soil Mineralogy

Back to The ASA-CSSA-SSSA International Annual Meetings (November 4-8, 2007)