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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

An evaluation of electrochemically activated solutions as pre-oxidants in water treatment

Abeywickrama, Lloyd Samitha January 2000 (has links)
No description available.
2

The electrochemistry of silver co-ordination complexes

Bolger, Paul Thomas January 1999 (has links)
No description available.
3

Chlorination of Organic Material in Agricultural Soil

Vali nia, Salar January 2009 (has links)
<p>Chlorine is an essential building block in the environment and can be found in most places. Chlorine participates in a complex biogeochemical cycle and has been discussed for many years and it is well documented that natural chlorination of organic compound takes place in many parts of the ecosystem. Chlorine can be inorganic (Clin) and organically bound (Clorg). Previous studies have shown that the transformation of Clin to Clorg is connected with the amount of organic matter and the microbial activity in the soil. So far, studies have been focused on forest soil and there is a need for analysing the natural chlorination in other soil types. The aim of this study was to provide chlorination rates in agricultural soil which does not weem to have been done previously. Three common agricultural soils experiencing different agricultural practice and different cropping systems were incubated with Na36Cl at 20o C in a 56 days radiotracer experiment. The results show that a chlorination of 36Clin to 36Clorg in agricultural soil occurred and the Clorg levels increased over time. The chlorination rates ranged from 0,040 to 0,063 μg Cl g dry weight soil-1 d1. This was 10-fold lower than rates previously measured in coniferous forest soil. However, when expressed as μg Cl g dry weight organic carbon-1 d-1, rates in the agricultural soil was only slightly (at the most 2-fold) lower than in coniferous forest. This study contributes with new knowledge of natural chlorination rates in agricultural soil and gives further evidence that the natural chlorination can be connected to the amount of organic matter in the soil.</p>
4

The Role of Leaf Litter and Small Wood in the Retention of Fine Particles During Storms in an Appalachian Headwater Stream

Adams, Janey Christine 18 December 1998 (has links)
Streams are constantly subject to downstream movement of materials. The role of fallen leaves in resisting downstream transport of particulates is largely unquantified. The litter exclusion study at Coweeta presented the opportunity to study a stream without litter input. I expected removal of leaf litter to reduce the capacity of the stream to retain fine particulate organic matter, FPOM. However, leaves are also a major source of FPOM. I studied the effect of leaf exclusion on FPOM transport by field sampling and by generating computer simulations of particle transport in the stream. Sampling of suspended particles during storms showed that although litter inputs and subsequent particle generation were greatly decreased (Wallace et al. 1997), storm exports did not differ significantly from those of the reference stream. This suggested that the effect of litter exclusion was to reduce FPOM retention. Although there was no new organic matter entering the stream during the exclusion period, entrainment of stored material compensated for it. The computer simulations predicted higher concentrations of FPOM for storms after litter exclusion than I actually measured except during heavy rains that greatly increased discharge. These results suggested that after litter exclusion, low-intensity storms exported lower concentrations than before exclusion. However, after exclusion, intense storms that greatly increased discharge entrained higher concentrations of FPOM. Both field studies and computer models indicated that stability of the litter-excluded streambed was lower compared to the reference and pre-treatment streams, and stability was further reduced with increased discharge. / Master of Science
5

Chlorination of Organic Material in Agricultural Soil

Vali nia, Salar January 2009 (has links)
Chlorine is an essential building block in the environment and can be found in most places. Chlorine participates in a complex biogeochemical cycle and has been discussed for many years and it is well documented that natural chlorination of organic compound takes place in many parts of the ecosystem. Chlorine can be inorganic (Clin) and organically bound (Clorg). Previous studies have shown that the transformation of Clin to Clorg is connected with the amount of organic matter and the microbial activity in the soil. So far, studies have been focused on forest soil and there is a need for analysing the natural chlorination in other soil types. The aim of this study was to provide chlorination rates in agricultural soil which does not weem to have been done previously. Three common agricultural soils experiencing different agricultural practice and different cropping systems were incubated with Na36Cl at 20o C in a 56 days radiotracer experiment. The results show that a chlorination of 36Clin to 36Clorg in agricultural soil occurred and the Clorg levels increased over time. The chlorination rates ranged from 0,040 to 0,063 μg Cl g dry weight soil-1 d1. This was 10-fold lower than rates previously measured in coniferous forest soil. However, when expressed as μg Cl g dry weight organic carbon-1 d-1, rates in the agricultural soil was only slightly (at the most 2-fold) lower than in coniferous forest. This study contributes with new knowledge of natural chlorination rates in agricultural soil and gives further evidence that the natural chlorination can be connected to the amount of organic matter in the soil.
6

Effect of resuspension on mineralisation of organic material : Laboratory studies of water movement intensity and concentration of suspended sediment

Stenborg Larsson, Charlotte January 2005 (has links)
<p>The Earth’s surface contains of 71% oceans and a large part of the global carbon cycle takes place in the oceans. In the aquatic environment, the sediment-water interface plays an important role for the mineralisation of organic material. One factor that can affect the mineralisation is resuspension. Resuspension cause mixing of surface sediments and bottom water and result in a redistribution of the sediment when it settles again. Resuspension also increases the transport of oxygen into the sediment, reduces the diffusive boundary layer surrounding particles, and enhance the nutrient uptake. Resuspension can be induced by both wave action and bottom currents and is a common physical process in both shallow coastal areas and in the deep ocean. Human impacts, such as dredging and trawling, can also cause resuspension.</p><p>The effect of resuspension on mineralisation of organic material was studied in two experiments ex situ during December to April 2004/2005. The aim for Experiment 1 was to investigate how the intensity of the resuspension event affects the degradation rate. The aim for Experiment 2 was to investigate how different concentrations of resuspended sediment affect the degradation rate of organic matter. Sediment samples were collected in December and late March at a marine field station, Askö, Sweden. Sediment and bottom water were transferred to and incubated in sealed bottles. For Experiment 1, resuspension was created in bottles with a specially designed rotary table, creating different intensity of water movements. In Experiment 2, bottles with different concentrations of sediment were put on an ordinary rotary table. The mineralisation rates were in both experiments monitored by daily sampling of sediment-water slurry, and analysed for total inorganic carbon by a gas chromatography with a thermal detector, GC-TCD.</p><p>Results from Experiment 1 did not show any clear patterns regarding inorganic carbon formation. Experiment 2 did show clear patterns for two of six replicates of mineralisation of organic material. For these replicates the mineralisation rate were low according to previous studies. However, the sediment concentration seems to not affect the mineralisation rate. For both experiments, valuable information on how to better design experiments to investigate the importance of resuspension and the effect of mineralisation of organic material was yielded. Hence, further studies are needed to continue the investigation of the importance of resuspension for the mineralisation rate of organic material, and its impacts on the nutrient fluxes in the oceans.</p>
7

Temperature sensitivity of decomposition in a boreal mixed mire in northern Sweden

Johansson, Linda January 2010 (has links)
Carbon accumulation in soils constitutes a significant sink for carbon. How the climate change with increasing temperatures will affect the soil carbon storage represents uncertainty of the predictions in the climate change ecosystem feedback mechanisms. In this study the temperature impact on the decomposition of the large carbon pools in peatlands was investigated. Peat cores from different microtopographic units in a boreal oligotrophic minerogenic mire in northern Sweden were collected from in three depths (5-10, 10-15 and 15-20 centimeters below the surface). The samples were incubated at four temperatures: 4, 9, 14 and 19°C and the heterotrophic respiration (CO2- production) was measured hourly or 37 days. Unexpectedly, basal respiration did not show any correlation with temperature. However, the exponential increase in respiration (µ) was correlated with temperature: i.e.  giving Q10 values between 2 (SE +/- 0.36) and 5 (SE +/-1.05). Soil depth or vegetation covers did not affect temperature response (Q10) of µ. The substrate induced respiration (SIR) did not occour but for a few of the samples. The conclusion from this study is that degradation of peat seams not be affected by a temperature increase. The addition of glucose, nitrogen and phosphorus increased with increasing temperature with a Q10 value as expected.
8

Effect of resuspension on mineralisation of organic material : Laboratory studies of water movement intensity and concentration of suspended sediment

Stenborg Larsson, Charlotte January 2005 (has links)
The Earth’s surface contains of 71% oceans and a large part of the global carbon cycle takes place in the oceans. In the aquatic environment, the sediment-water interface plays an important role for the mineralisation of organic material. One factor that can affect the mineralisation is resuspension. Resuspension cause mixing of surface sediments and bottom water and result in a redistribution of the sediment when it settles again. Resuspension also increases the transport of oxygen into the sediment, reduces the diffusive boundary layer surrounding particles, and enhance the nutrient uptake. Resuspension can be induced by both wave action and bottom currents and is a common physical process in both shallow coastal areas and in the deep ocean. Human impacts, such as dredging and trawling, can also cause resuspension. The effect of resuspension on mineralisation of organic material was studied in two experiments ex situ during December to April 2004/2005. The aim for Experiment 1 was to investigate how the intensity of the resuspension event affects the degradation rate. The aim for Experiment 2 was to investigate how different concentrations of resuspended sediment affect the degradation rate of organic matter. Sediment samples were collected in December and late March at a marine field station, Askö, Sweden. Sediment and bottom water were transferred to and incubated in sealed bottles. For Experiment 1, resuspension was created in bottles with a specially designed rotary table, creating different intensity of water movements. In Experiment 2, bottles with different concentrations of sediment were put on an ordinary rotary table. The mineralisation rates were in both experiments monitored by daily sampling of sediment-water slurry, and analysed for total inorganic carbon by a gas chromatography with a thermal detector, GC-TCD. Results from Experiment 1 did not show any clear patterns regarding inorganic carbon formation. Experiment 2 did show clear patterns for two of six replicates of mineralisation of organic material. For these replicates the mineralisation rate were low according to previous studies. However, the sediment concentration seems to not affect the mineralisation rate. For both experiments, valuable information on how to better design experiments to investigate the importance of resuspension and the effect of mineralisation of organic material was yielded. Hence, further studies are needed to continue the investigation of the importance of resuspension for the mineralisation rate of organic material, and its impacts on the nutrient fluxes in the oceans.
9

Caracterização da fração orgânica dos resíduos sólidos urbanos do Aterro municipal de Santo André visando seu aproveitamento energético via biodigestão anaeróbia

Silva, Caroline Aparecida da January 2016 (has links)
Orientadora: Prof. Dra. Juliana Tófano de Campos Leite Toneli / Dissertação (mestrado) - Universidade Federal do ABC. Programa de Pós-Graduação em Energia, 2016. / A geração de resíduos sólidos é um problema que vem se agravando com o passar dos anos. A proteção ao ambiente, o combate à poluição e a oferta de saneamento básico são direitos do cidadão, segundo a Constituição Federal, portanto, o governo deve se responsabilizar pelas práticas de controle ambiental. O Plano Nacional de Resíduos Sólidos é um documento elaborado a partir da Política Nacional de Resíduos Sólidos que fortalece os princípios da gestão integrada e sustentável de resíduos, propõe medidas de incentivo nos sistemas de coleta, tratamento e destinação de resíduos sólidos. Esse trabalho apresenta um panorama geral dos Resíduos Sólidos Urbanos do município de Santo André, com o objetivo de caracterizar a fração orgânica para avaliar a possibilidade de tratamento com aproveitamento energético via processo bioquímico de biodigestão anaeróbia. Para tal, foram determinadas as características químicas da fração orgânica dos RSU dispostos no Aterro Municipal de Santo André, tais como teor de umidade, sólidos fixos e voláteis, relação carbono/nitrogênio (C/N) e composição centesimal. Foram estudados resíduos de origens domiciliar e comercial, da CRAISA (Companhia Regional de Abastecimento Integrado de Santo André) e de feiras livres. Os resultados obtidos foram comparados e relacionados. Os valores médios obtidos foram: Sólidos totais de (65,75 ± 8,9)% para as rotas dos resíduos úmidos, (81,61 ± 2,18)% para a CRAISA e (71,8% ± 14,7)% para as feiras livres; Sólidos Voláteis de (72,23% ± 12,28)% para as rotas dos resíduos úmidos, (85,35% ± 1,21)% para a CRAISA e (84,33% ± 9,36)% para as feiras livres; o teor de lipídios foi de (5,43% ± 0,51)% para as rotas dos resíduos úmidos, (2,31% ± 0,44)% para a CRAISA e (3,24% ± 0,23)% para as feiras livres; o teor de proteína foi de (12,23% ± 2,10)% para as rotas dos resíduos úmidos, (8,75% ± 0,44)% para a CRAISA e (9,69% ± 1,17)% para as feiras livres; a razão C/N de 21,63 para as rotas dos resíduos úmidos, 27,97 para a CRAISA e 28,59 para as feiras livres, situando-se, portanto, dentro dos resultados ótimos para que o processo de biodigestão anaeróbia ocorra. / Solid Waste production is a problem it has intensified over the years. The environment protection, that pollution and sanitation availablity is a civil right, according to Federal Constitution, so the government must be responsable for environmetal control practices. The Solid Waste National Plan is a document drawn up from the Solid Waste National Policy that strengthens the principles of integrated and sustainable waste management, it proposes measures to promote the collection, treatment and disposal of solid waste. This study presents an overview of Municipal Solid Waste of Santo André in Brazil, in order to characterize the organic fraction to evaluate the possibility of energy recovery treatment by biochemical process of anaerobic digestion. To this end, it was determined the chemical characteristics of the organic fraction of MSW disposed in the Municipal Landfill of Santo André, such as moisture content, fixed and volatile solids, carbon / nitrogen ratio (C/N) and chemical composition. It were studied the household and commercial waste sources, the CRAISA (Regional Integrated Supply Company of St. Andrew) and fairs. Some results were compared and interrelated. Average values form: Total Solids 65.75 ± 8.9% for the routes of solid waste, 81.61 ± 2.18% for CRAISA and 71.8% ± 14.7% for open-market; Volatile Solids of 72.23% ± 12.28% for the routes of wet waste, 85.35% ± 1.21% for CRAISA and 84.33% ± 9.36% for for open-market; the 5.43% lipid content ± 0.51% for the routes of wet waste, 2.31% ± 0.44% for CRAISA and 3.24% ± 0.23% for for open-market; the protein content was 12.23% ± 2.10% for the routes of wet waste, 8.75% ± 0.44% for CRAISA and 9.69% ± 1.17% for for open-market; the C / N ratio of 21.63 for the routes of wet waste, 27.97 to 28.59 and CRAISA for for open-market, standing therefore in the excellent results for the process of anaerobic digestion occurs.
10

Efeito da compostagem sobre a solubilização e a eficiência agronômica de diferentes fontes de fósforo

Cézar, Vicente Rodolfo Santos [UNESP] 21 March 2005 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:31:34Z (GMT). No. of bitstreams: 0 Previous issue date: 2005-03-21Bitstream added on 2014-06-13T21:02:50Z : No. of bitstreams: 1 cezar_vrs_dr_botfca.pdf: 165898 bytes, checksum: 5fb20932737337f84056a83d049a9b62 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Universidade Estadual Paulista (UNESP) / Com o intuito de avaliar o efeito do processo de compostagem sobre a solubilização e a eficiência agronômica de diferentes fontes de fertilizantes fosfatados, foram desenvolvidos dois experimentos. O primeiro constou da produção de compostos orgânicos enriquecidos ou não com superfosfato triplo (ST) ou fosfato natural de Arad (FN). Foi realizado o acompanhamento da temperatura da pilha e do pH do material orgânico durante o processo, além de uma análise química do composto ao final do processo de compostagem. No experimento II, conduzido em vasos com plantas de alface, em casa de vegetação, os compostos orgânicos gerados foram aplicados ao solo para avaliar, através da planta, a Eficiência Agronômica (IEA) do fósforo. Para ambas as fontes, as quantidades de P adicionadas nos vasos foram de 200 mg de P L-1 de terra. Os tratamentos foram: testemunha, fosfato natural de Arad (FN), superfosfato triplo (ST), composto orgânico + ST (COST) com 1,5; 3,0; 4,5 e 6,0% de P, composto orgânico com FN (COFN) com 1,5; 3,0; 4,5 e 6,0% de P adicionada antes da compostagem, COSTF e COFNF com adição das mesmas quantidades de P (ST ou FN) no composto orgânico após o processo de compostagem. Utilizou-se o delineamento estatístico inteiramente casualizado para os dois experimentos. Não se observou no experimento I, efeito favorável do enriquecimento com diferentes porcentagens de superfosfato triplo na compostagem sobre os parâmetros avaliados. Já para adição de diferentes porcentagens de fosfato natural de Arad, observou-se aumento sobre os valores de temperatura, pH, redução da massa da pilha e diminuiu à solubilidade do P solúvel em água, o que sugere que o processo biológico não promoveu a solubilização do fósforo. Para o experimento II os resultados do IEA, baseado na matéria seca e na quantidade de fósforo extraído pela parte aérea... / To evaluate the composting process on the solubility and agronomic efficiency of different phosphate sources, two experiments were developed. The first consisted of producing organic composts enriched with different levels of triple superphosphate (TS) or natural Arad phosphate (NP). Compost heap temperature and organic material pH were monitored throughout the process; compost chemical analysis was performed at the end of the composting process. In the second experiment, the organic composts were applied to the soil in potted lettuce plants under greenhouse conditions and agronomic phosphate efficiency (APE) was evaluated analysing the plants. For both compost sources, the quantity of additional phosphate was 200mg/L soil. Treatments were: control, NP, TS, organic compost + TS (OCTS) with 1.5, 3.0, 4.5, and 6.0% P, organic compost + NP (OCNP) with 1.5, 3.0, 4.5, and 6.0% P added before composting, OCTSP and OCNPP adding the same quantities of P (NP or TS) after the composting process. A completely randomized experimental design was used for both experiments. No favourable enrichment effects were seen in Experiment I from the different TS levels. However, increase in NP increased temperature and pH, and reduced heap mass and soluble P solubility; this suggests that the biological process did not promote phosphate solubility. APE results from Experiment II, based on dry material and quantity of phosphorous extracted from the above soil part of the lettuce plants, showed that the pre-enrichment composts were inferior to the post-enrichment composts in both crops, indicating that there was no favourable effect in adding TS and NP to the composting process in the evaluated period.

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