Masters Theses

Date of Award

6-1988

Degree Type

Thesis

Degree Name

Master of Science

Major

Plant, Soil and Environmental Sciences

Major Professor

John T. Ammons

Committee Members

D. A. Lietzke, John E. Foss, S. Y. Lee, Richard W. Arnseth

Abstract

The nature and properties of soils overlying the Maryville and Nolichucky geologic formations at the Oak Ridge National Laboratory Rese~vation-Solid Waste Storage Area 6 (SWSA-6) were investigated to determine 1) their pedogenesis from physical, chemical, mineralogical, morphological and micromorphological properties, 2) the relationship between geological formations and soils and 3) soil genesis relationships. Physical, chemical, mineralogical, morphological and micromorphological analyses were conducted on soils from the study area. The following physical and chemical analyses were conducted: particle size, water and KCl pH, total carbon, calcium carbonate equivalence (CCE), effective cation exchange capacity (ECEC) using sum of exchangeable bases plus KCl total acidity, exchangeable aluminum, exchangeable acidity, hydroxylamine reducible manganese and sodium dithionite (CBD) extractable manganese and iron. The mineralogy of the clay fraction was determined and micromorphological characteristics were observed. Two Ultisols and two Alfisols were investigated and classified in the study area. Major parent materials present in the study site were ancient alluvium, Maryville Limestone and Nolichucky Shale. Some colluvial soils were present on sideslopes. Areas of ancient alluvium were found in the southwestern portion of the Maryville Limestone area. High silt contents were predominant in the surface horizons and some Bt horizons of all soil profiles due to the deposition of fine alluvium and weathering of silty parent material. Higher sand percentages were found in the Cr horizons due to weathering of sandstone bedrock. Some fragmentation of partially weathered bedrock occurred from the sieving process during sample preparation. This may have resulted in higher sand percentages than what is present in the field. Clay content generally increased with depth and decreased after contact with partially weathered bedrock. With the exception of some surface horizons, low organic carbon values were found throughout the soil profiles and generally decreased with depth. The pH values of the soil and partially weathered bedrock ranged from 4.5 to 7.3. The pH of the carbonate bedrock of the HHMS-4B and HHMS-5A core drillings ranged from 7.5 to 8.4. The values for extractable aluminum and total acidity generally increased with depth in all soil profiles. Effective cation exchange capacity values varied from 2.38 to 52.67 cmol(+) kg-1 and exchangeable bases values varied from 0.01 to 44.06 cmol(+) kg-1 throughout all soils investigated. Ammonium acetate extractable calcium values of samples from the 4Cr and 5Cr horizons of profile four ranged from 44.06 to 30.80 cmol(+) kg-1 and high values were contributed from carbonates. Ammonium acetate extractable magnesium values varied from 0.07 to 7.87 cmol(+) kg -1throughout all soil profiles. Magnesium values were high (6.25, 7.87 and 6.26 mg kg-1 respectfully) in the 3Cr, 4Cr and SCr horizons of profile four, which suggests the presence of dolomite in the bedrock. Weathering sequences and soil forming processes of the soils were evaluated using x-ray diffraction (XRD) and differential scanning calorimetry (DSC). Minerals present in the clay size fraction included kaolinite, hydroxy interlayered vermiculite, vermiculite, illite, and gibbsite. Other constituents of the clay size fraction were organics and manganese and iron oxides. High values of CBD extractable manganese and iron were found throughout most soil profiles. Microscopically, manganese and iron oxides were observed as 1) nodules, 2) granular segregated bodies, 3) crystalline forms, 4) neomangans, 5) infillings, and 6) impregnations. They were also present along with highly oriented clay coatings on pores, and faces of peds and partially weathered bedrock. The development of soil on the interbedded Nolichucky Shale and Maryville Limestone formations exemplified how slope effects soil formation. Soil and partially weathered bedrock were deeper on the upland position than on side slopes and footslope positions. This was due to greater stability and water infiltration which resulted in greater weathering on the upland position. The soil on the footslope was shallow due to removal of material by overland flow of water.

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