published_or_final_version / Civil Engineering / Master / Master of Philosophy

published_or_final_version / Civil Engineering / Master / Master of Philosophy

Laboratory soil columns, 0.3 m diameter $ times$ 0.7 m long, and two computer simulation models, LEACHM-N and NTRM, were used to investigate nitrate-nitrogen ($ rm NO sb{3 sp{-}}$-N) leaching in a sandy loam soil. The following treatments were studied: no-till (NT), reduced tillage (RT), and conventional tillage (CT) practices, with residue (R) and without residue (NR). Nitrogen fertilizer was applied at a rate of 180 kg/ha in granular form (experiment I), and in solution form a year later (experiment II). In both experiments, water was applied 5 times over 3 to 4 weeks duration, with each application lasting for 30 minutes. Each column received an average of 24 mm water in experiment I and 32 mm in experiment II. Soil moisture contents were measured and water for $ rm NO sb{3 sp{-}}$-N concentration determination sampled at 0.1, 0.2, 0.4, and 0.6 m depths, following each water application. / In each experiment I, higher nitrate-nitrogen concentrations ($ lbrack rm NO sb{3 sp{-}}$-N)), occurred at the 0.1 and 0.2 m soil layers in RT and CT treatments initially, but less leached to lower layers, while more $ rm NO sb{3 sp{-}}$-N leached to lower depths (below 0.4 m) in the NT treatment. In experiment II, more $ rm NO sb{3 sp{-}}$-N leached below 0.4 m in RT and CT than in NT treatments. Conventional tillage exhibited the lowest drainage rates. Tillage and residue effects were significant only at early stages (4 hours or before) at some depths of experiment I ($P<0.05$). Maximum $ lbrack rm NO sb{3 sp{-}}$-N) occurred at 0.4 m depth in all treatments. / LEACHM-N estimated more $ rm NO sb{3 sp{-}}$-N leaching below 0.4 m in RT and CT treatments than in NT treatment. The model performed poorly only immediately after fertilizer application, showing up to 50% deviation from observed data. Although LEACHM-N overpredicted $ lbrack rm NO sb{3 sp{-}}$-N) in the 0.2 m soil layers in all treatments, estimations remained within standard deviations of observed data. NTRM performed well below 0.4 m depths, but often underpredicted $ rm NO sb{3 sp{-}}$-N leaching at shallower depths. / From both the laboratory experiments and mathematical simulations it was concluded that when fertilizer is applied in granular form, no till practice is undesirable because deeper $ rm NO sb{3 sp{-}}$-N leaching (below 0.4 m) occurs. Reduced tillage may be the preferred choice in such a situation. When fertilizer is applied in solution, reduced and conventional tillage practices are undesirable because deeper $ rm NO sb{3 sp{-}}$-N leaching occurred. No till practice may be a better choice in such a case.

No description available.

Land application of domestic wastewater effluent by rapid rate infiltration (i.e., percolation ponds) is a very successful and cost-effective method for wastewater management. Municipal percolation pond systems have been successfully operated in the United States for about 100 years. The disposal concept depends on a relatively high rate of secondary wastewater effluent infiltration into the soil by rapid percolation, either vertically or horizontally, away from the application surface area. This study was accomplished to determine infiltration rates at two working percolation pond systems and the variability of these rates, to compare the operating results with the initial design, and to create a stochastic computer based simulation program for design and operation. The initial study site was located west of Orlando, Florida, and consisted of a system of two percolation ponds. Daily readings were obtained on evaporation, rainfall, flow to the ponds, pond depth and groundwater table elevations. A mass balance inventory equation was formulated and the infiltration parameter was determined. A frequency distribution was created for the rainfall, evaporation and calculated infiltration from the initial site, and then a stochastic computer based simulation program was written with this data. The program calculated results which compared favorably with the design for this initial percolation pond site. A second site was chosen, also located in the Orlando area, to confirm the usefulness of the program and its operational capabilities.

No description available.

Graduation date: 1997

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.

Orientador: Alcides Lopes Leão / Coorientador: Ivana Cesarino / Banca: Renata Cristina Batista Fonseca / Banca: Vera Lucia Mores Rall / Resumo: A expansão urbana acarreta a necessidade de mitigações ambientais, em que um planejamento do uso do solo bem como seu processo de ocupação traz a necessidade também de estudos para viabilizar tais ações. Nesse processo de expansão, os cemitérios necessitam de maior atenção, visto que estudos dessas áreas já evidenciaram indícios de contaminações no solo. Atualmente, é consenso que atividades de sepultamento são responsáveis pela contaminação do solo e aquíferos subterrâneos através da percolação do necrochorume. O presente trabalho teve como objetivo analisar as concentrações dos metais pesados cobre, cromo, zinco e chumbo no solo de três tipos de áreas presentes no cemitério: zona com sepultamento, área sem atividades cemiteriais e fragmento florestal. Para o objetivo, foram efetuadas coletas de solo através de tradagens em nove pontos e seis profundidades. Para determinação da concentração dos metais, foi utilizado espectrofotometria de absorção atômica, no Centro de Assistência Toxicológica (CEATOX), do IB/UNESP. Os valores obtidos foram comparados aos valores de referência propostos pela CONAMA nº420/2009. Com os resultados obtidos, constatou-se que nenhum dos pontos amostrados apresentou concentração acima dos valores estipulados, porém foi possível visualizar acúmulo dos metais na área onde existe atividade cemiterial e estabelecer sua relação com o fluxo superficial e sub-superficial da água. O fato de o local de estudo possuir uma área com fragmento florestal a jusant... / Abstract: Urban expansion engenders the need for environmental mitigation, in which planning the processes of land use and cover generates the need of studies to enable such actions. In that expansion process, it is imperative that more attention is paid to cemeteries, since studies in the area have already evidenced soil contamination. There is currently a consensus that burial activity is responsible for soil and aquifer contamination through cemetery leachate percolation. The purpose of the present study was to examine the concentration of four heavy metals (copper, chromium, zinc, and lead) in three different types of area found in the cemetery: the burial grounds, an area with no cemeterial activity, and a forest fragment. To achieve that objective, soil samples were collected through boreholes in nine areas and six depths. The metal concentrations were determined through atomic absorption spectroscopy (AAS) at the Toxicology Assistance Center (Centro de Assistência Toxicológica, or CEATOX) in the IB/UNESP campus. The values obtained were then compared to the reference values used by the National Environment Council (CONAMA) nº420/2009. The final results showed that none of the samples had concentrations higher than the established values; however, it was possible to identify a higher concentration of the metals in the burial grounds and to determine its connection to the surface and subsurface water flow. As the study environment has a forest fragment downstream, it was posible ... / Mestre