Brad Lee
Ph.D. 1999
Dissertation Title:
- Pedogenesis and mineral weathering in serpentinitic landslide terrain, Klamath Mountains, California.
Currently:
- Assistant Professor of Soils and Land Use, Purdue University, West Lafayette, IN.
- http://www.agry.purdue.edu/staffbio/blee/index.html
Publications from Dissertation Research:
- Lee, B.D., R.C. Graham, T.E. Laurent, C. Amrhein, and R.M. Creasy. 2001. Spatial distributions of soil chemical conditions in a serpentinitic wetland and surrounding landscape. Soil Sci. Soc. Am. J. 65:1183-1196.
- Lee, B.D., S.K. Sears, R.C. Graham, C. Amrhein, and H. Vali. 2003. Secondary mineral genesis from chlorite and serpentine in an ultramafic soil toposequence. Soil Sci. Soc. Am. J. 67:1309-1317.
- Lee, B.D., R.C. Graham, T.E. Laurent, and C. Amrhein. 2004. Pedogenesis in a wetland meadow and surrounding serpentinitic landslide terrain, northern California, USA. Geoderma 118:303-320.
Ultramafic terrain (shown in white) is prominent in the Klamath Mountains in northern California and southern Oregon. Ultramafic rocks (peridotite, serpentinite) have high levels of Fe, Mg, Mn, Ni, and Cr, and low levels of Al, K, and Ca. Distinctive plant communities result from this extreme geochemical environment.
Serpentinitic terrain is unstable and landslide features are common. Brad studied the soil-geomorphic relations on a stabilized landslide bench and the surrounding landscape. Tom Laurent, soil scientist on the Klamath National Forest, collaborated with us throughout the project.
Soil on the surrounding slopes are well drained (Haploxeralfs), while those in the wet meadow on the landslide bench are poorly drained (Endoaquolls).
Brad spent considerable time in the field conducting a topographic survey, describing and sampling soils, and collecting soil solution samples.
In response to the diverse pedogenic environments, redox sensitive elements, such as Mn, were dissolved, transported, and concentrated as oxides in soils of certain landscape positions. This figure depicts the spatial distribution of dithionite-extractable Mn in surface soil samples. Sample locations are indicated by dots and the soil-geomorphic map units are numbered 1-6.
High resolution transmission electron microscopy and x-ray diffraction revealed that primary chlorite transformed to vermiculite as its hydroxide interlayer sheet was removed by weathering. Brad traveled to McGill University to work in the laboratory of Professor H. Vali for the HRTEM research.