Plant Science & Landscape Architecture Theses and Dissertations
Permanent URI for this collectionhttp://hdl.handle.net/1903/2797
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Item Multi-Scale Pedologic Investigation of Manganiferous Soils in the Maryland Piedmont(2008) Bourgault, Rebecca; Rabenhorst, Martin; Plant Science and Landscape Architecture (PSLA); Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Manganese oxides are usually found in trace quantities in soils, but they are important due to their effects on soil chemistry and morphology. There are rare soils in the Maryland Piedmont that have extremely high amounts of manganese oxides that have not been previously studied. These manganiferous soils were examined at multiple scales in order to determine their spatial extent, to characterize their fundamental morphology, mineralogy, and chemical and physical properties, and to better understand their pedogenesis. The soils occupy areas of 1-2 ha in size, within 200 km2 in eastern Frederick County and western Carroll County. The soils can have as much as 140 g kg-1 Mn as oxides, which pigments the entire soil matrix black in subsoil horizons. It appears that the black, porous, Mn-rich material is derived directly from the dissolution of marble bedrock and accumulation of silicate residues plus Mn and Fe from within the rock.Item Quantifying Fine Sediment Sources in the Northeast Branch of the Anacostia River, Maryland, Using Trace Elements and Radionuclides(2006-12-11) Devereux, Olivia Harcourt; Needelman, Brian A; Prestegaard, Karen L; Plant Science and Landscape Architecture (PSLA); Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Fine sediment sources were characterized in an urban watershed, the Northeast Branch of the Anacostia River, which drains to the Chesapeake Bay. Concentrations of 63 elements and two radionuclides were measured in possible sediment sources and suspended sediment collected at the watershed outlet during storm events. Methodology for selecting tracers was developed so the sediment fingerprinting method could effectively determine the relative quantity of sediment contributed by each source to the suspended fraction. The amount of enrichment of trace elements in sediment sources and suspended sediment was determined by calculating enrichment ratios, which are ratios of the normalized concentration of elements in the sample relative to their average normalized concentration in the Earth's upper continental crust. Streambanks contributed the highest relative quantity of sediment in the fall and spring while upland areas contributed mostly during winter. Street residue contributed 12% on average and was the source most concentrated in anthropogenically enriched elements.Item Mapping and Characterization of the Marlboro Clay Formation(2005-12-13) Scott, Mitchell Louis; Needelman, Brian A; Plant Science and Landscape Architecture (PSLA); Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The Marlboro Clay formation is a geologic formation that outcrops in Prince George's County, Maryland, and is of great significance due to its instability. Water well logs are collected to determine ground water quantity. Marlboro Clay can be easily recognized in the water well log's lithology descriptions due to its pink color. The objectives of this study were to provide data on the morphology and problematic characteristics of soils formed from Marlboro Clay to and use water well log data to create an interpolated Marlboro Clay map. Marlboro Clay samples were smectite and kaolinite dominated and had moderate potential volume change ratings. The particle size varied due to infilling of sediments from the overlying Nanjemoy and underlying Aquia formations. An accurate bottom elevation Marlboro Clay map was created which we strongly anticipate will contribute to improved natural resource and urban planning activities where the Marlboro formation is found.Item The Origin and Pedogenic History of Quaternary Silts on the Delmarva Peninsula in Maryland(2003-11-18) Wah, John Stuart; Rabenhorst, Martin C; Plant Science and Landscape Architecture (PSLA)Soils formed in Quaternary age silts are widespread on the Delmarva Peninsula in Maryland. The origin, mode of transportation and deposition, and age of the sediments in which these soils formed have long been debated and are important to understanding climate change and to investigations of the prehistory of the Delmarva. This study was undertaken in an effort to resolve the issue of the origin of parent sediments, to examine the pedogenic history of the soils, and to gain insight into the paleoclimate of the region. Thirty nine profiles were described and sampled in two north-south transects on the upland and the broad terrace along the Chesapeake Bay on Maryland's Eastern Shore. Laboratory analyses included determination of particle size distribution, determination of Zr, Ti, Ca, and K contents of coarse silts, mineralogical analysis, and the examination of biogenic opal. The silty mantle overlying sands ranged in thickness from 150 cm to less than 50 cm, with considerable variation across the study area. Textures of this mantle were silt loam and silty clay loam with 53 to 94 percent clay-free silt and a mean clay-free particle size of 41 mm. The Zr content of the silts was uniform within profiles and across the study area while that of Ti, Ca, and K varied. Mineralogy of the silts was homogeneous across the study area. There were no features diagnostic of either fluvial/estuarine or eolian processes in the silt deposit. Minimal coarse fragments and no stratification were observed. Low chroma matrix colors of soils reflected modern drainage conditions rather than a reducing depositional environment. Pedological development argued for relatively young soils (< 30,000 years) and archaeological materials from surface horizons buried by the silts dated the onset of deposition to the end of the Pleistocene (approximately 10,500 14C years BP). The youthfulness of the silts precluded them from having been deposited during the Sangamon transgression, which occurred no more recently than 82,000 years BP, and proved unequivocally that the silts are loess. Buried paleosols were indicative of the landscape stability prior to loess deposition while phytoliths reflected a climate shift.