• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 57
  • 21
  • 5
  • 3
  • 2
  • 2
  • 1
  • 1
  • 1
  • Tagged with
  • 107
  • 107
  • 107
  • 19
  • 15
  • 15
  • 15
  • 14
  • 13
  • 13
  • 13
  • 12
  • 12
  • 11
  • 9
  • 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.
101

Avaliação do risco ambiental de sedimentos contaminados com triclosan, ibuprofeno e 17α-etinilestradiol empregando invertebrados marinhos bentônicos / Environmental risk assessment of sediments contaminated with triclosan, ibuprofeno and 17α-ethynylestradiol employing benthic marine invertebrates

Fabio Hermes Pusceddu 16 August 2016 (has links)
Os protocolos de Avaliação de Risco Ambiental (ERA) de Fármacos e Produtos de Cuidados Pessoais (FPCP) recomendam o uso de ensaios ecotoxicológicos tradicionais (por exemplo algas, bactérias, invertebrados, peixes) e a avaliação de efeitos em um único nível de organização biológica para a determinação dos efeitos potenciais dos FPCP à biota. Considerando que efeitos em nível de sub-indivíduo pode afetar igualmente a aptidão ecológica de organismos marinhos, e que os mesmos estão cronicamente expostos aos FPCP, o objetivo do presente estudo foi avaliar o risco ambiental de triclosan (TCS), ibuprofeno (IBU) e 17&alpha;-etinilestradiol (EE2) em sedimentos marinhos utilizando respostas de efeitos sub-individuais e populacionais. Por meio do HPLC-ESI-MS/MS, as concentrações ambientais de TCS e IBU foram quantificadas em sedimentos marinhos coletados no entorno do emissário submarino de esgoto de Santos (Baía de Santos, São Paulo - Brasil) com 15,14 e 49,0 ng.g-1, respectivamente, enquanto o EE2 não foi detectado (<33 ng.g-1). Uma bateria de ensaios de toxicidade crônica (desenvolvimento embriolarval) com ouriços-do-mar (Lytechinus variegatus) e bivalves (Perna perna) foi realizada (efeito a nível de indivíduo) após exposição a sedimentos contaminados com os FPCP. Além disso, foram analisados alguns biomarcadores de Fase I (etoxiresorufina O-deetilase EROD e dibenzilfluoresceína DBF), de Fase II (glutationa S-transferase GST) do metabolismo, do sistema antioxidante (glutationa peroxidase GPx), de neurotoxicidade (colinesterase ChE), de estresse oxidativo (peroxidação lipídica LPO e danos em DNA) e de citotoxicidade que foram selecionados para avaliação das respostas a nível de sub-indivíduo em mexilhões Mytella charruana. Todos os compostos analisados apresentaram efeitos sobre o desenvolvimento embriolarval de L. variegatus e P. perna em concentrações ambientalmente relevantes. Em nível de sub-indivíuo foi possível observar que o TCS causou efeitos cito-genotóxicos (diminuição da estabilidade da membrana lisossomal, peroxidação lipídica e danos em DNA) e neurotóxicos. O IBU causou efeitos citotóxicos e neurotóxicos, enquanto o EE2 apresentou efeitos citotóxicos e danos em DNA. Nesse sentido, mesmo em baixas concentrações os FPCP são potencialmente capazes de alterar os mecanismos de manutenção da homeostase. Os dados químicos e ecotoxicológicos foram integrados e os quocientes de risco estimados para TCS, IBU e EE2 apresentaram valores superiores a 1,0, indicando alto risco ambiental destes compostos em sedimentos marinhos. Estes são os primeiros dados de avaliação de risco ambiental de FPCP em sedimentos de uma zona costeira brasileira. Os resultados sugerem que a ERA de fármacos e produtos de cuidados pessoais deve contemplar, além dos ensaios de toxicidade tradicionais o uso de biomarcadores como indicadores dos primeiros sinais de efeitos e, assim, estabelecer uma avaliação de risco mais efetiva que assegure a proteção e funcionamento dos ecossistemas aquáticos. / The guidelines for the Environmental Risk Assessment (ERA) of pharmaceuticals and personal care products (PPCPs) usually recommend the use of standard ecotoxicity assays (e.g. algae, bacteria, invertebrate, fish) and the assessment of endpoints at individual level for the evaluation of potential effects of PPCPs on biota. Considering that effects at sub-individual level can also affect the ecological fitness of marine organisms, and that marine organisms are chronically exposed to PPCPs, the aim of the current study was to evaluate the environmental risk of triclosan (TCS), ibuprofen (IBU) and 17&alpha;-ethynylestradiol (EE2) in marine sediments using sub-individual and population endpoints. Using LC-ESI-MS/MS, the environmental levels of TCS and IBU were quantified in marine sediments from the vicinities of the Santos submarine sewage outfall (Bay of Santos, São Paulo, Brazil) at 15.14 and 49.0 ng g-1, respectively, while EE2 was not detected (<33ng g-1). A battery (n=3) of chronic bioassays (embryo-larval development) with a sea urchin (Lytechinus variegatus) and a bivalve (Perna perna) were performed at populational level after exposure to spiked sediment. Phases I (ethoxyresorufin O-deethylase EROD and dibenzylfluorescein dealkylase DBF) and II (glutathione S-transferase GST) of the metabolism, antioxidant system (glutathione peroxidase GPX), neurotoxicity (cholinesterase ChE), oxidative effects (lipid peroxidation LPO and DNA damage strand breaks) and cytotoxicity were selected to evaluate the sublethal responses in the bivalve Mytella charruana. These compounds showed developmental effects on L. variegatus and P. perna at environmentally relevant concentrations. At sub-individual level TCS induced cyto-genotoxic (reduction on stability of lysosome membrane, lipid peroxidation and DNA damage) and neurotoxic effects. IBU caused cyto and neurotoxic effect, while EE2 caused cytotoxic and DNA damage. Chemical and ecotoxicological data were integrated and the quotient risk estimated for TCS, IBU and EE2 showed values higher than 1.0, indicating high environmental risks of these compounds in sediments. These are the first data of risk assessment of pharmaceuticals and personal care products in sediments of a Brazilian coastal zone. The results suggests that the ERA of pharmaceuticals and personal care products must include, in addition to the standard toxicity tests, the use of biomarkers as indicators of the early warning signs and thus provide a more effective risk assessment to security the protection and functioning of aquatic ecosystems.
102

Decision-making for acceptable risk in contaminated site problems in British Columbia

Thomas, Deanna 11 1900 (has links)
Contaminated sites are a common problem across municipalities in the Greater Vancouver Regional District. These problems are complicated and multi-dimensional, and raise fundamental concerns about the risks to human and environmental health. This thesis shows however, that there are no easy answers to how much risk is "acceptable", and no one right way to decide. How the acceptable risk problem is structured is important, because fact and value issues, a source of controversy and dispute, are variously interpreted depending on how the problem is cast. The literature generically categorizes acceptable risk as either a technical, social or decision problem, and each of these have implications for the types of decision-making approaches and solutions that are considered appropriate in resolving acceptable risk. This thesis investigated how acceptable risk in contaminated site problems is handled in British Columbia by reviewing the provincial decision-making framework, and by surveying municipalities in the Greater Vancouver Regional District for their views on contaminated site problems and acceptable risk decision-making. The underlying goal of the thesis is to question the use of the current approach, the Pacific Place site criteria, as a model for acceptable risk decision-making in the province, and to explore the implications for urban communities. The Ministry of Environment is the central authority for contaminated sites in British Columbia and has generally taken a scientific and technical approach to the problem. Although the municipal survey suggests that the Pacific Place site criteria has a broad base of support in the GVRD, the technical emphasis has implications for urban communities. The approach is expert-oriented and largely excludes local and public involvement in the acceptable risk debate. The major concern is that important social value issues have been neglected, relative to the engineering and technical aspects of the problem. The research also finds however, that the majority of individuals in the municipal survey are willing to explore other methods of determining acceptable risk, and support in principle, local government and public involvement in deciding what these methods should be. This thesis suggests that British Columbia can benefit from a more comprehensive view of acceptable risk in contaminated site problems. Resource limitations at the provincial and local level, and the high stakes in contaminated site problems for urban communities point to the growing importance of incorporating a broad range of value issues and understanding the trade-offs in acceptable risk decisions. The Ministry of Environment can improve the current decision-making approach by: incorporating structured value assessments that elicit stakeholder values and address trade-offs; involving a wider range of stakeholders in standard setting and risk assessment, including the forthcoming review of the Pacific Place site criteria; creating forums to explore other decision-making approaches; and by encouraging private sector involvement in risk assessment and risk management. The province can also encourage and support community-based institutional networks, both at the municipal and regional level. / Applied Science, Faculty of / Community and Regional Planning (SCARP), School of / Graduate
103

Health and safety risks among the Thulamela Municipality waste handlers in the Limpopo Province, South Africa

Ngobeni, Takalani 18 May 2019 (has links)
MPH / Department of Public Health / Health and safety issues pertaining to workers are global concerns and a major priority to the employers and government respectively. Employees in general across industries are faced with various health and safety risks. Epidemiological research has shown consistently that waste handlers are mostly exposed to various risks and hazards during their work as compared to other professions globally. This study focused on waste handlers employed by the Thulamela Municipality in the Limpopo Province, South Africa. The study employed qualitative explorative design and targeted all municipal waste handlers. Municipal waste handlers were sampled using non probability purposive sampling. In-depth interviews, using an interview guide, were conducted by the researcher and a voice recorder was used to record data from the participants after obtaining permission from them. The sample size comprised of 18 participants and was determined by data saturation. A thematically analysis technique was used to analyse data. Data from the participants were clustered into main theme, categories and sub-categories. The following themes emerged from data analysis: physical hazards, psychological hazard, biological hazards and chemical hazard. The study revealed that the municipal waste handlers are exposed to various occupational risks and are experiencing shortage of personal protective equipment, ranging from hand gloves, safety helmets, rain coats, overall uniforms, safety jackets and boots, to keep themselves safe from health problems and occupational injury when collecting waste. It is recommended that the Thulamela municipality should prioritise the working conditions for municipal waste handlers, by distributing suitable personal protective equipment such as hands gloves, safety helmet, rain coats, safety jackets and boots) and overalls / NRF
104

An ecological assessment of the Holsloot River, Western Cape, South Africa

Le Roux, Anso 02 1900 (has links)
Human related activities have influenced the rivers of the southern Western Cape since as early as the 1700’s. As there is no detailed information available on ecological status of the Holsloot River, a tributary of the Breede River, this study aimed to gain insight into the effect of impacts associated with human activities on the habitat integrity of this river. The study intended to understand how seasonal changes, catchment characteristics and events are reflected in the ecological status of habitats along the river by applying bio-monitoring and river health measurements at selected sites in the upper, middle and lower reaches of the Holsloot River and compare the results to that of an undisturbed reference site. Results obtained in this study are compared with data gathered in 2008/2009 to determine if the ecological status of the river had changed in the period between the two sampling times. The study included assessment of the ecological status of the river based on standard bio-monitoring protocol (SASS5, IHI, IHAS and VEGRAI) as well as in situ water quality analysis (pH, dissolved oxygen, electrical conductivity and total dissolved solids). The construction of the instream Stettynskloof Dam changed the configuration of the riparian zone and river channel in the upper catchment area. Agricultural- and other human related activities, with consequent water abstraction, non-point-source pollution, loss of riparian vegetation, as well as dense stands of alien invader plants influence flow patterns and affects river ecology, especially in the dry summer months. Providing sufficient stream flow and adequate water levels, human related activities can create a larger variety of habitat types available that can support larger biodiversity and higher productivity. The level of inundation and stream flow, influenced by water abstraction as well as irrigation return-flow from extensive drainage systems especially in the dry months, contribute to the loss of biodiversity in the middle and lower reaches of the river. Where the upper reaches of the river are largely natural with few modifications, the habitat integrity deteriorates in the middle reaches so much so that ecosystem functioning are collectively impaired in lower reaches due to human related impacts. Sensitive macro-invertebrates found at lower seriously impacted parts of the river however, were in all probability washed down from lower impacted upstream habitats and may expectedly be able to again occupy habitats downstream if water quality and habitat availability improves. / Environmental Sciences / M. Sc. (Environmental Science)
105

Prediction of Spatial-Temporal Distribution of Algal Metabolites in Eagle Creek Reservoir, Indianapolis, IN

Bruder, Slawa Romana 29 October 2012 (has links)
Indiana University-Purdue University Indianapolis (IUPUI) / In this research, Environmental Fluid Dynamic Code (EFDC) and Adaptive- Networkbased Fuzzy Inference System Models (ANFIS) were developed and implemented to determine the spatial-temporal distribution of cyanobacterial metabolites: 2-MIB and geosmin, in Eagle Creek Reservoir, IN. The research is based on the current need for understanding algae dynamics and developing prediction methods for algal taste and odor release events. In this research the methodology for prediction of 2-MIB and geosmin production was explored. The approach incorporated a combination of numerical and heuristic modeling to show its capabilities in prediction of cyanobacteria metabolites. The reservoir’s variable data measured at monitoring stations and consisting of chemical/physical and biological parameters with the addition of calculated mixing conditions within the reservoir were used to train and validate the models. The Adaptive – Network based Fuzzy Inference System performed satisfactorily in predicting the metabolites, in spite of multiple model constraints. The predictions followed the generally observed trends of algal metabolites during the three seasons over three years (2008-2010). The randomly selected data pairs for geosmin for validation achieved coefficient of determination of 0.78, while 2-MIB validation was not accepted due to large differences between two observations and their model prediction. Although, these ANFIS results were accepted, the further application of the ANFIS model coupled with the numerical models to predict spatio-temporal distribution of metabolites showed serious limitations, due to numerical model calibration errors. The EFDC-ANFIS model over-predicted Pseudanabaena spp. biovolumes for selected stations. The predicted value was 18,386,540 mm3/m3, while observed values were 942,478 mm3/m3. The model simulating Planktothrix agardhii gave negative biovolumes, which were assumed to represent zero values observed at the station. The taste and odor metabolite, geosmin, was under-predicted as the predicted v concentration was 3.43 ng/L in comparison to observed value of 11.35 ng/l. The 2-MIB model did not validate during EFDC to ANFIS model evaluation. The proposed approach and developed methodology could be used for future applications if the limitations are appropriately addressed.
106

An analysis of security measures implemented on commercial private game reserves in Limpopo

Herman, Dewald Gustav 29 November 2020 (has links)
South Africa presently experiences high levels of crime daily. Although crime is accepted as an everyday occurrence for its citizens, it affects the economy of the country. This study analysed security measures implemented on Commercial Private Game Reserves (CPGRs) in Limpopo and the impact of crime thereof. CPGRs are enclosed areas containing various species of fauna and flora. Visitors from domestic and foreign origins visit these reserves to enjoy nature and its tranquillity. This study analysed the security measures to determine their effectiveness for CPGRs. The study further explored the use of security risk management strategies and risk assessments as crime reduction tools. The study was carried out using a case study research design. Data were collected by the researcher using three methods: observation, onsite checklists and semi-structured one-on-one interviews which were conducted on site. Validity and reliability indicate the trustworthiness of the study. The researcher reduced the data gathered through the use of thematic data analysis. Interviews were transcribed and themes were created and identified by the researcher. The comprehensive data indicated the importance of a security risk manager on a CPGR. The research found that very few security risk managers are employed and that managers of security risks employed on CPGRs have various titles. However, while the CPGRs have similar risks, their risk reduction strategies vary. The most commonly used measures are people, physical and technological measures with each having various subdivisions. The security measures implemented by CPGRs in the Limpopo province which were analysed are not formulated using a scientific approach as most properties do not make use of a formal security risk assessment. The study is deemed valuable as a model was developed from the findings that could be used by game reserves to guide them to apply relevant security measures. A formal security programme is often limited due to financial constraints of the reserve or the reserve owners, however, not all strategies should be considered as a financial expense as much can be done without exhausting financial reserves. The findings contributed to making recommendations to improve the overall security of CPGRs. This study encourages more research into the subject to improve the security industry and to stimulate the tourism industry. / Security Risk Management / M. Tech. (Security Management)
107

Predicting locations for urban tree planting

King, Steven M. January 2014 (has links)
Indiana University-Purdue University Indianapolis (IUPUI) / The purpose of this study was to locate the most suitable blocks to plant trees within Indianapolis, Indiana’s Near Eastside Community (NESCO). LiDAR data were utilized, with 1.0 meter average post spacing, captured by the Indiana Statewide Imagery and LiDAR Program from March 13, 2011 to April 30, 2012, to conduct a covertype classification and identify blocks that have low canopies, high impervious surfaces and high surface temperatures. Tree plantings in these blocks can help mitigate the effects of the urban heat island effect. Using 2010 U.S. Census demographic data and the principal component analysis, block groups with high social vulnerability were determined, and tree plantings in these locations could help reduce mortality from extreme heat events. This study also determined high and low priority plantable space in order to emphasize plantable spaces with the potential to shade buildings; this can reduce cooling costs and the urban heat island, and it can maximize the potential of each planted tree.

Page generated in 0.1177 seconds