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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

Quantification of PAHs and PCBs in eThekwini aquatic systems, using chemical and biological analysis / Natasha Lee Vogt

Vogt, Natasha Lee January 2014 (has links)
Polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) are common contaminants of sediment, soils and biological tissues. These compounds pose a significant risk to biological and ecosystem health and functioning due to these compounds being mutagenic, carcinogenic and are known to disrupt the endocrine system. The bioaccumulation and biomagnification potential that these compounds possess mean that they are capable of affecting the entire food chain and are not limited to the organisms that are directly in contact with the compounds Even though there has been an increase in the attention on identifying the presence and impacts that these compounds may have in South Africa, the level of attention is lower than what it is in other countries around the world. Although South Africa has guidelines in place for other pollutants, such as metals, there are no such guidelines in place to monitor PAHs and PCBs.. Industries are known to release both PAHs and PCBs, mainly from incomplete burning processes and the release of oils and fuels in the case of PAHs, and from heat transfer fluids in the case of PCBs. Durban Bay and surrounding areas of eThekwini, KwaZulu-Natal are highly industrialised with many aquatic systems, in which these contaminants are likely to deposit. The aim of this research was to determine the concentrations of these compounds by means of chemical analysis and additionally biological analysis, using the H4IIE-luc bioassay and compare these levels to international guideline levels. It was found that the concentrations of the 23 analysed PAHs were 6.5–3 235.6 ng.g-1 and the concentration of the PCBs analysed were 0–113.83 ng.g-1. Many sites were found to be in exceedance of the guideline limits, particularly in the harbour. Toxic equivalency factors (TEF) were used to gauge the toxic equivalency (TEQ) of the PAHs and PCBs that were found. The TEQs were generally low, and were below any guideline levels. The assay revealed the extract containing the PCBs had a bioassay equivalence (BEQ) of 0–93.54 pgTCDDeq. g-1 and the extract containing the PAHs of 0–776.08 pgTCDD-eq.g-1. With a proportion of the sites exceeding guideline limits. The BEQ results were two to three orders of magnitude greater than the TEQs calculated from the concentrations determined by the instrumental analysis, however, followed a similar trend. Additionally chemical analysis was not performed on a full suite of compounds that are able to elicit a response from the cells, which could be a reason why the BEQ and TEQ did not follow a similar trend among some of the samples. It would have been more beneficial to have performed chemical analysis on the 16 priority PAHs (as determined by the United States Environmental Protection Agency), the dioxin-like PCBs and polychlorinated dibenzo-p-dioxins (PCDD) and polychlorinated dibenzofurans (PCDFs) which are all capable of eliciting a response from the cells and have TEF values. The areas that were most affected by contamination of these compounds was the harbour and surrounding canals, and there was point source contamination along the Umhlatuzana, Umbilo, and Amanzimnyana Rivers. All dl-PCBs should be chemically analysed at all the sample areas, as these cause adverse effects to biota. In addition to this, biota should be sampled to determine concentrations of the compounds to determine bioavailability and the degree of bioaccumulation in the food chain. Utilising biomarkers it would be possible to determine stresses of fish. / MSc (Environmental Sciences), North-West University, Potchefstroom Campus, 2014
2

Quantification of PAHs and PCBs in eThekwini aquatic systems, using chemical and biological analysis / Natasha Lee Vogt

Vogt, Natasha Lee January 2014 (has links)
Polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) are common contaminants of sediment, soils and biological tissues. These compounds pose a significant risk to biological and ecosystem health and functioning due to these compounds being mutagenic, carcinogenic and are known to disrupt the endocrine system. The bioaccumulation and biomagnification potential that these compounds possess mean that they are capable of affecting the entire food chain and are not limited to the organisms that are directly in contact with the compounds Even though there has been an increase in the attention on identifying the presence and impacts that these compounds may have in South Africa, the level of attention is lower than what it is in other countries around the world. Although South Africa has guidelines in place for other pollutants, such as metals, there are no such guidelines in place to monitor PAHs and PCBs.. Industries are known to release both PAHs and PCBs, mainly from incomplete burning processes and the release of oils and fuels in the case of PAHs, and from heat transfer fluids in the case of PCBs. Durban Bay and surrounding areas of eThekwini, KwaZulu-Natal are highly industrialised with many aquatic systems, in which these contaminants are likely to deposit. The aim of this research was to determine the concentrations of these compounds by means of chemical analysis and additionally biological analysis, using the H4IIE-luc bioassay and compare these levels to international guideline levels. It was found that the concentrations of the 23 analysed PAHs were 6.5–3 235.6 ng.g-1 and the concentration of the PCBs analysed were 0–113.83 ng.g-1. Many sites were found to be in exceedance of the guideline limits, particularly in the harbour. Toxic equivalency factors (TEF) were used to gauge the toxic equivalency (TEQ) of the PAHs and PCBs that were found. The TEQs were generally low, and were below any guideline levels. The assay revealed the extract containing the PCBs had a bioassay equivalence (BEQ) of 0–93.54 pgTCDDeq. g-1 and the extract containing the PAHs of 0–776.08 pgTCDD-eq.g-1. With a proportion of the sites exceeding guideline limits. The BEQ results were two to three orders of magnitude greater than the TEQs calculated from the concentrations determined by the instrumental analysis, however, followed a similar trend. Additionally chemical analysis was not performed on a full suite of compounds that are able to elicit a response from the cells, which could be a reason why the BEQ and TEQ did not follow a similar trend among some of the samples. It would have been more beneficial to have performed chemical analysis on the 16 priority PAHs (as determined by the United States Environmental Protection Agency), the dioxin-like PCBs and polychlorinated dibenzo-p-dioxins (PCDD) and polychlorinated dibenzofurans (PCDFs) which are all capable of eliciting a response from the cells and have TEF values. The areas that were most affected by contamination of these compounds was the harbour and surrounding canals, and there was point source contamination along the Umhlatuzana, Umbilo, and Amanzimnyana Rivers. All dl-PCBs should be chemically analysed at all the sample areas, as these cause adverse effects to biota. In addition to this, biota should be sampled to determine concentrations of the compounds to determine bioavailability and the degree of bioaccumulation in the food chain. Utilising biomarkers it would be possible to determine stresses of fish. / MSc (Environmental Sciences), North-West University, Potchefstroom Campus, 2014
3

Poluentes Orgânicos Persistentes em sangue de aves marinhas no Arquipélago de São Pedro e São Paulo e na Ilha da Trindade / Persistent Organic Pollutants in blood of seabirds in the São Pedro and São Paulo Archipelago and Trindade Island

Silva, Daniela Alves Maia da 08 March 2019 (has links)
As aves marinhas são sensíveis às alterações em todos os níveis tróficos, decorrentes de variações na disponibilidade de presas e contaminação por alguns compostos, capazes de se acumular nos tecidos dos organismos e magnificar-se através da cadeia trófica. As ilhas oceânicas brasileiras abrigam importantes colônias reprodutivas de aves marinhas e, apesar de serem consideradas locais remotos, estão sujeitas à contaminação decorrente de atividades humanas. Este trabalho avaliou a presença de poluentes orgânicos persistentes (POPs) em sangue, uma matriz não-destrutiva, de seis espécies de aves marinhas no Arquipélago de São Pedro e São Paulo e na Ilha da Trindade, que possibilita o monitoramento destes indivíduos ao longo dos anos. Os resultados indicaram que os principais POPs detectados no sangue (em ng g-1 de massa úmida) foram PCBs (0,05 a 55,09), DDTs (0,01 a 17,36) e Mirex (0,01 a 5,53). A migração influenciou nos altos níveis de POPs encontrados em Pterodroma arminjoniana e a massa (g) média dos indivíduos apresentou uma forte correlação negativa com as concentrações dos compostos predominantes no sangue. O sexo das aves não contribuiu significativamente nas concentrações de POPs em espécies monotípicas, exceto para a espécie Sula leucogaster que apresenta dimorfismo sexual acentuado. O comportamento alimentar, avaliado através da análise de isótopos estáveis de carbono e de nitrogênio (δ13C e δ15N), bem como as condições biológicas de cada animal contribuíram para explicar as variações nos perfis de contaminação entre as diferentes espécies. No geral, observou-se que as concentrações de POPS nos dois locais apresentaram valores baixos e similares sugerindo a via atmosférica como principal mecanismo de entrada desses contaminantes para estas regiões. Os resultados inéditos de POPs em sangue das aves marinhas nas duas mais recentes unidades de conservação marinhas criadas no Brasil, podem contribuir como referência para o monitoramento desses compostos em longo-prazo nessas regiões. / Seabirds are sensitive to changes at all trophic levels, due to variations in prey availability and contamination by some compounds, which can be accumulated in the tissues of organisms and to be magnified through the trophic chain. The Brazilian oceanic islands harbor important seabird breeding colonies and, although they are considered remote sites, they are subject to contamination from human activities. This work evaluated the presence of Persistent Organic Pollutants (POPs) in blood, a non-destructive matrix, of six species of seabirds in the São Pedro and São Paulo Archipelago (SPSPA) and Trindade Island (TI), that allows the monitoring of these individuals over the years. The results indicated that the major POPs detected in blood (ng g-1 in wet weight) were PCBs (0.05 to 55.09), DDTs (0.01 to 17.36) and Mirex (0.01 to 5,53). Migration influenced the high levels of POPs found in Pterodroma arminjoniana and the mean mass (g) of the individuals drove a strong negative correlation with the concentrations of the predominant compounds in the blood. The gender of the individuals did not contribute significantly to the concentrations of POPs in monotypic species, except for the species Sula leucogaster that presents marked sexual dimorphism. The feeding behavior was evaluated through the analysis of stable isotopes of carbon and nitrogen (δ13C and δ15N) as well as the biological conditions of each animal contributed to explain the variations in the contamination profiles between the different species. In general, we observed that POPS concentrations at both sites presented low and similar values suggesting the atmospheric transport as the main input mechanism of these compounds for these regions. The unpublished results of POPs, in blood of seabirds from the two most recent marine conservation units created in Brazil, can contribute as reference values for their long-term monitoring in those regions.

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