|aSource: Dissertations Abstracts International, Volume: 84-06, Section: A.
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|aAdvisor: Garcia, Patricia Ventura;Rodrigues, Armindo dos Santos;Fernandes, Cristina Maria Branquinho.
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|aThesis (Ph.D.)--Universidade dos Acores (Portugal), 2021.
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|aThis item must not be sold to any third party vendors.
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|aThe legal regime concerning air quality and protection of the atmosphere in the Azores upholds the necessity of striving towards harmonizing human socioeconomic development with the preservation of excellent standards of air quality. Though historically a relatively incipient issue, contemporary challenges posed by intensifying anthropogenic activities or climate change require further efforts to address and prevent the decline of air quality, through increasing emissions of atmospheric pollutants, entailing the degradation of the natural patrimony of the Azores and adverse effects upon public health. Furthermore, owing to archipelago’s volcanic background, volcanogenic emissions continually occur during periods of quiescent activity, particularly affecting the populations chronically exposed in the proximity of active volcanoes. Hence, using lichens as biomonitors, the general aim of this thesis was to refine a set of tools to biomonitor air pollution in selected environmental scenarios of Sao Miguel island (SMG), addressing both anthropogenic and volcanogenic airborne emissions originating, respectively, from the unprecedented intensification of human activities as well as ongoing manifestations of active volcanism.The broad-spectrum elemental profile of naturally occurring (native) foliose Parmotrema lichens, sampled across the land use gradient of SMG, revealed a transversal pattern of significant elemental enrichment at agricultural and even more at artificial areas compared with the more pristine-like background of forest areas, thus tracing environmental contamination, through airborne emissions, displaying the impact of intensifying agricultural and urban activities, particularly in the context of the greater environmental vulnerability inherent to small oceanic island ecosystems. Some potentially toxic heavy metals (Pb, Mo, Mn, V, Zn, Th, Sb, Sn, Co, Ni, Cu, Cr, Ti, Fe) reached high bioaccumulation levels in lichens from artificial land use, while nitrogen bioaccumulation was highest in those from agricultural land use, reflecting the ongoing N pollution that has caused eutrophication issues in recent decades at SMG. The N isotopic signature (δ 15N) was a suitable tracer to distinguish the nitrogenous contribution between agricultural and artificial sources, with applicability to discern its respective origin in more complex scenarios of spatial overlapping of these sources. Meanwhile, an alternative approach was followed to biomonitor volcanic air pollution by transplanting fruticose Usnea rubicunda lichens from a reference site into several sites at Furnas village, inside the caldera of the actively degassing Furnas volcano. After a prolonged exposure period of 6 months, it was verified that the δ 34S isotopic ratio, retained in the transplanted lichens, is a specific tracer of airborne hydrothermal emissions in outdoor conditions, strongly relating with the distance to fumarolic fields on a logarithmic regression. δ 34S data was subsequently combined with spatial data on habitational areas to develop a method for spatially modelling, with high spatial resolution and time integration, the risk areas of chronic exposure to air pollution in volcanic environments. Moreover, as revealed through an histomorphometric methodology, the thalli of these same transplanted lichens displayed significant structural alterations suggesting a positive and time-integrated response of greater efficiency, by the algal partner, in sustaining the production of additional fungal biomass. These structural alterations in the heteromerous thalli of U. rubicunda are sensitive responses reflecting the extended exposure under greater availability of CO2 in ambient conditions, with potential to indicate a global rise of CO2 levels.
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|aO regime juridico da qualidade do ar e protecao da atmosfera dos Acores preve a necessidade de encontrar solucoes no sentido de harmonizar o desenvolvimento socioeconomico humano com a preservacao dos padroes de excelencia da qualidade do ar. Embora historicamente tenha sido um problema incipiente, os desafios contemporaneos colocados pela intensificacao das atividades antropogenicas ou alteracoes climaticas requerem esforcos adicionais dedicados a prevencao da declinio da qualidade do ar, por via do aumento das emissoes de poluentes atmosfericos, conduzindo a degradacao do patrimonio natural dos Acores e efeitos adversos sobre a saude publica. Alem disso, devido a origem vulcanica do arquipelago, emissoes vulcanogenicas decorrem continuamente durante periodos de atividade quiescente, afetando particularmente as populacoes cronicamente expostas na proximidade de vulcoes ativos. Assim, atraves do uso de liquenes como biomonitores, o objetivo geral desta tese foi afinar um conjunto de ferramentas para biomonitorizar a poluicao do ar em cenarios ambientais caracteristicos da ilha de Sao Miguel (SMG), abrangendo tanto as emissoes atmosfericas antropogenicas como vulcanogenicas originadas, respetivamente, pela intensificacao sem precedentes das atividades humanas e pelas incessantes manifestacoes de vulcanismo ativo. O perfil elemental de largo espectro de liquenes foliosos nativos (de ocorrencia natural) do genero Parmotrema, amostrados ao longo do gradiente de uso do solo de SMG, revelou um padrao transversal de enriquecimento elemental em areas agricolas e sobretudo areas artificiais em comparacao com o fundo pristino de areas florestais, refletindo a contaminacao ambiental causada por emissoes atmosfericas e exibindo o impacto da intensificacao das atividades agricolas e urbanas, particularmente no contexto da acrescida vulnerabilidade ambiental inerente aos ecossistemas de pequenas ilhas oceanicas. Alguns metais pesados potencialmente toxicos (Pb, Mo, Mn, V, Zn, Th, Sb, Sn, Co, Ni, Cu, Cr, Ti, Fe) atingiram niveis de bioacumulacao elevados nos liquenes do uso do solo artificial, enquanto a bioacumulacao de azoto foi mais elevada nos liquenes do uso do solo agricola, indicando a poluicao azotada que tem causado problemas de eutrofizacao nas ultimas decadas em SMG. A assinatura isotopica δ 15N revelou-se um indicador adequado para distinguir a contribuicao azotada entre fontes agricolas e artificiais, com aplicabilidade para o rastreamento da respetiva origem em cenarios mais complexos de sobreposicao espacial destas fontes. Entretanto, foi escolhida uma abordagem alternativa para biomonitorizar a poluicao vulcanica do ar atraves do transplante de liquenes fruticulosos, da especie Usnea rubicunda, recolhidos a partir de um local de referencia e transplantados para varios locais na vila das Furnas, localizada dentro da caldeira do vulcao que se encontra em desgaseificacao ativa. Depois de um periodo de exposicao prolongado de 6 meses, verificou-se que a razao isotopica de enxofre (δ 34S), retida nos liquenes transplantados, e um indicador especifico de emissoes hidrotermais em condicoes ao ar livre, relacionando-se fortemente com a distancia aos campos fumarolicos numa regressao logaritmica. Os dados de δ 34S foram posteriormente combinados com dados espaciais das areas habitacionais para desenvolver um metodo de modelacao espacial das areas de risco de exposicao cronica a poluicao do ar em ambientes vulcanicos, com elevada resolucao espacial e integracao temporal.