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Since 1936 National Park Service has been charged with preserving Civil War Earthworks while allowing public access. Soil erosion, both natural and human-induced, is a major concern facing the preservation of the earthworks. Currently, the National Park Service is committed to preserving these earthworks for future generations by determining which maintenance activities cause the least soil erosion. This study was undertaken to determine which management practice; burned, mowed, park-forest, forested, or trimmed, best minimized soil erosion. A secondary objective was to determine how several empirical formulas (e.g. Universal Soil Loss Equation) and one field estimate (e.g. erosion pins) compared soil erosion trends for the 5 treatments. A third objective of this study was to gather information regarding the soil development which has occurred during the 135 + years since the earthworks were constructed. Earthworks managed by prescribed burning suffered the greatest erosion rates while the forested earthworks eroded the least. The trimmed and mowed management regimes were not significantly different and would provide adequate erosion protection while the forested treatment had significantly less erosion. Based on the empirical models, erosion was primarily a function of ground cover; on the other hand, rain intensity was highly influential for erosion as measured by the erosion pins. All of the erosion estimation methods concurred that the burned treatment should be avoided due to the high erosion rates while the erosion pins indicated that the park-forest treatment could potentially have erosion problems as well. Soil profile descriptions from the earthworks revealed that A horizon depths on the earthworks were not significantly different then the A horizons found on the relatively undisturbed adjacent forest floor and that subsurface soil structure has begun to develop on earthwork soils. / Master of Science

Effect of cementitious stabilization on the stress-compressibility characteristics of three different South Florida organic soils were evaluated in this study. The objectives of the research were to (l) determine if the secondary compression characteristics of organic soils and peats can be stabilized with (a) cement only, (b) binary blends of cement/slag (C-S), cement/gypsum (C-G), and cement/cement-kiln-dust (C-CKD) and (c) ternary blend of cement-slag-gypsum in equal proportions; (ll) quantify the effectiveness of cementitious stabilization by evaluating the time-stress-compressibility (t-log σ'v - e) relationship in terms of the Cα / Cc ratio; and (lll) provide some guidelines for selecting optimum dosage of cementitious materials in deep mixing methods when organic soils and peats are encountered. It was concluded that cementitious mixes containing various waste materials is effective in controlling the secondary compression behavior of organic soils, and therefore should be considered in deep mixing methods as a sustainable practice. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2014. / FAU Electronic Theses and Dissertations Collection

The understanding of the spatial distribution of lead (Pb) in soil is important in the assessment of potential risks and development of remediation strategies for Pb contaminated land. In situ heterogeneity of Pb was measured at two heavily contaminated sites in the United Kingdom using the Portable X-ray Fluorescence Spectrometer (P-XRF) over a range of spatial scales (0.02 to 50 m). The pattern of the distribution of Pb was very variable, and when expressed as heterogeneity factor (HF), it ranged from 1.2 to 3.2 (highly heterogeneous). The effect of such Pb heterogeneity on plant uptake was investigated in greenhouse pot trials. Two earlier pot trials, which assessed the effect of Pb in a fixed concentration (1000 mg/kg) and in a range of concentration (100 to 10000 mg/kg) found a significant effect of the Pb added treatments, when compared to a control treatment (0 mg/kg Pb added). Biomass and uptake varied by 20 to 100% within and between 16 species/varieties. Results enhanced the selection of two species (Brassica napus and Brassica juncea) for further pot trials. A third pot experiment with Brassica napus and Brassica juncea in simplistic binary model of heterogeneity found 20 to 60% lower uptake in the binary treatment, than homogeneous the treatment. Biomass was higher by 10 to 50% in Brassica juncea and 20 to 40% lower for B. napus in the bianary treatment, when compared to the homogeneous and control treatments. The effect of a more realistic in situ heterogeneity on plant uptake was investigated in a further pot trial, which simulated low (LH), medium) (MH) and high (HH) heterogeneity treatments, compared to a homogeneous (HO) treatment. It detected a significant (P < 0.05) impact of heterogeneity on biomass and uptake between treatments and species. Four to five fold lower biomass were recorded in HH treatment, when compared to the HO treatment. Shoot and root uptake in (mg/kg) concentration increased with increasing heterogeneity with peak uptake (twice as high as HO treatment) in LH for B. napus and in HH and MH treatments for B. juncea respectively. Shoot and root Pb masses in (μg) were maximum in HO and MH treatments respectively with 50 to 70% lower Pb mass in the HH treatment. Results showed that response to heterogeneity is species specific. A sub-experiment explored the behaviour of plant roots in HH treatment and found 20 to 80% variation in root biomass between concentric patches with same nominal soil Pb concentrations. This provided insights into varied responses of these species to realistic Pb heterogeneity. The research demonstrated that the presence and extent of in situ heterogeneity of Pb in soil plays an important role in Pb uptake by plants. It also showed that the homogeneous and simplistic binary model of heterogeneity do not give reliable estimates of plant growth and Pb uptake in realistic field conditions. This work has implications for improving the efficiency of phytoremediation of Pb contaminated land, phytomining, reliability of risk assessment and models of human exposure to Pb.

Heterogeneity of contaminants in soils can vary spatially over a range of scales, causing uncertainty in environmental measurements of contaminant concentrations. Sampling designs may aim to reduce the impact of on-site heterogeneity, by using composite sampling, increased sample mass and off-site homogenisation, yet they could overlook the small scale heterogeneity that can have significant implications for plant uptake of contaminants. Moreover, composite sampling and homogenisation may not be relevant to target receptor behaviour, e.g. plants, and studies, using simplistic models of heterogeneity have shown that it can significantly impact plant uptake of contaminants. The alternative approach, to accept and quantify heterogeneity, requires further exploration as contaminant heterogeneity is inevitable within soils and its quantification should enable improved reliability in risk assessment and understanding variability in plant contaminant uptake. This thesis reports the development of a new sampling design, to characterise and quantify contaminant heterogeneity at scales, from 0.02m to 20m, using in situ measurement techniques, and 0.005m to 0.0005m, using ex situ techniques. The design was implemented at two contaminated land sites, with contrasting heterogeneity based upon historic anthropogenic activity and showed heterogeneity varying between contaminants and at different spatial scales, for Pb, Cu and Zn. Secondly, this research demonstrates how contaminant heterogeneity measured in situ can be recreated in a pot experiment, at a scale specific to the plant under study. Results, from 4 different plant species, demonstrated that existing simplistic models of heterogeneity are an inadequate proxy for plant performance and contaminant uptake under field conditions, and significant differences were found in plant contaminant concentrations between simplistic models and those based upon actual site measurements of heterogeneity. Implications of heterogeneity on plant roots were explored in the final experiment showing significant differences in root biomass between patches of differing contaminant concentrations.

Thesis (Ph. D.)--University of Missouri-Columbia, 2003. / Typescript. Vita. Includes bibliographical references. Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 2003. / Typescript. Vita. Includes bibliographical references. Also available on the Internet.

Most natural products and xenobiotic molecules, irrespective of their molecular or structural complexity, are degradable by some microbial species/associations within particular environments. Atrazine- and selected petroleum hydrocarbon (benzene, toluen~ and 0-, m- and p-xylene (BTX))-degrading associations were enriched and isolated"trom atrazine- and petroleum hydrocarbon (PHC)-contaminated KwaZuluNatal loamy and sandy soils, respectively. In total, eight pesticide- and forty BTXcatabolizing associations were isolated. Electron microscopy revealed that, numerically, rods constituted the majority of the populations responsible for both atrazine and PHC catabolism. Cocci and, possibly, spores or fungal reproductive bodies were observed also. For the BTX-catabolizing associations, the population profiles appeared to be dependent on the enrichment pH and the molecule concentration. After combining selected associations, to ensure that all the isolated species were present, batch cultures were made to determine the optimum pH and temperature for growth; With an atrazine concentration of 30 mgr1, the highest specific growth rates, as determined by biomass (OD) changes, were recorded at 30DC and pH 4 although the rate§ at 25DC and pH 5 were comparable. For the BTX (50 mgr1)-catabolizing associations, the highest growth rates were recorded at pH 4 for the four temperatures (15, 20, 25 and 30DC) examined. The sole exception was p-xylene with the highest specific growth rate recorded at pH 5 and 30De. Batch and continuous (retentostat) cultivations in the presence/absence of methanol and under C- and N-limited conditions were used to investigate the impacts of the solvent and the catabolic potentials of a combined atrazine-catabolizing culture (KRA30). In general, different degradation rates were recorded for the culture in response to element limitation. Addition of citrate as the primary carbon source / effected atrazine (100 mg!"l) degradation rates comparable to that of Pseudomonas sp. strain ADP while succinate addition effected herbicide co-metabolism. Carbon supplementation may, therefore, be considered for site amelioration practices. To complement conventional culture-based microbiological procedures, molecular techniques were employed to explore the diversities and analyze the structures of the microbial communities. In parallel, anaerobic microbial associations which targeted atrazine were also characterized. The soil DNA isolation/characterization protocol adopted consisted of a clean-up step followed by the polymerase chain reaction (peR) and 16S rDNA fingerprinting by denaturing-gradient gel electrophoresis (DGGE). The preliminary results suggested that despite different, but chemically similar, petroleum hydrocarbon molecules, the common selection pressures of the primary enrichments effected the isolation of similar and complex aerobic microbial associations. Some similar numerically-dominant bands characterized the aerobic and anaerobic atrazine-catabolizing associations although distinct differences were also recorded on the basis of the enrichment/isolation pH value and the concentration of the herbicide. Cloning and sequencing were then used to identify some of the numerically-dominant and non-dominant association members. Community-level physiological profiling (CLPP) for physiological fingerprinting was made with Biolog EcoPlates and highlighted the differences in the isolated aerobic atrazine-catabolizing associations depending on the enrichment pH and molecule concentration. Logarithmic-phase cultures of the combined atrazine- and BTX-catabolizing associations were used to explore the association profiles following pH and temperaiure optImIzation. Although some common numerically-dominant components were maintained, differences in numerical and, possibly, activity dominance were observed in the 16S rDNA profiles in response to changes in pH and temperature. This indicated that environmental parameter optimization and characterization of catabolic association structure must precede bioaugmentation so that control of key variables will facilitate maintenance of the dominant site-specific species. Following KRA30 cultivation in the presence/absence of methanol and under carbon and nitrogen-limited conditions, the population fingerprints showed that the presence of methanol effected shifts in species numerical dominance and, possibly, changes in atrazine catabolic capacity. Also, Coulter counter results, optical density readings and 16S rDNA characterization by DGGE indicated that degradation rate changes were accompanied by shifts in species numerical/activity dominance within the association. Although N-limitation effected the highest rates of herbicide catabolism, a potential versatility of the combined association for bioaugmented and/or biosupplemented remediation with acceptable rates regardless of any elemental limitation was recorded. To determine if the contaminated and pristine source soils contained comparable catabolic populations and, thus, offered potential for intrinsic bioremediation, PCRDGGE was used to characterize the populations in comparison with the enriched/isolated associations. Some similar dominant bands characterized the contaminated soils and the enriched/isolated associations. The significance of this, in relation to a possible correlation between numerical and activity dominance in the component species, is discussed with respect to the use of PCR-DGGE to identify natural attenuation potential and monitor sustained intrinsic and enhanced (bioaugmented and biosupplemented) bioremediation. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 2001.