A carregar...
Publicação
Aplicação de modelação oceânica ao estudo de dispersão de plásticos na zona da Margem Ibérica Ocidental
| Nome: | Descrição: | Tamanho: | Formato: | |
|---|---|---|---|---|
| 4.43 MB | Adobe PDF |
Autores
Orientador(es)
Resumo(s)
A poluição associada a plásticos marinhos é considerada um dos problemas ambientais mais graves à escala global, sendo hoje um tema de maior relevância na agenda internacional. A caracterização dos plásticos tem sido objeto de diversos estudos, mas a componente de monitorização dos padrões de dispersão é praticamente inexistente na região da Península Ibérica. O objetivo deste estudo foi conjugar técnicas de modelação para um primeiro estudo da concentração/dispersão de plásticos à escala da zona da Margem Continental Portuguesa. Neste contexto, foi utilizado um modelo lagrangiano (LTRANS) sobre resultados de um modelo oceânico (ROMS) para demonstrar quais os locais de acumulação/dispersão das partículas no final dos seus percursos, e se estes são influenciados pelos períodos em análise. Foram simuladas trajetórias de partículas lançadas inicialmente nas zonas do Tejo e do Sado, isto é, os percursos de cada partícula durante seis períodos bimensais ao longo de um ano (1991). Em cada zona foram lançados dois conjuntos de 400 partículas em dois pontos distintos, com intervalos de 30 a 30 minutos. As zonas escolhidas para este estudo tiveram por base zonas de rotas de navios e pontos prováveis de descarga. As trajetórias obtidas foram analisadas com vista a avaliar o seu comportamento, nomeadamente a sua dispersão e pontos de acumulação, bem como a evidência de algum sinal sazonal. As conclusões sugerem que existe algum sinal sazonal, ou seja, no final da primavera e no verão as partículas tendem a ficar mais longe da costa, enquanto que no final do outono e no inverno as partículas tendem a ficar acumuladas perto do ponto de origem. Os resultados apresentados mostram que muitas partículas que partem da zona do Sado podem chegar à costa Vicentina, e possivelmente podem contribuir para as concentrações de microplásticos encontradas nessa região. Por outro lado, estes resultados confirmam que geralmente no inverno/outono existe uma maior concentração de MP e que as partículas ficam acumuladas perto da costa, principalmente no inverno.
Marine pollution related with plastics is considered one of the most serious environmental problems on a global scale, being a topic of greater relevance on the international agenda. The characterization of plastics has been the subject of several studies, but the component of monitoring of dispersion patterns is practically non-existent in the Iberian Peninsula region. The objective of this study was to combine modelling techniques for a first study of the concentration/dispersion of plastics at the scale of the Portuguese Continental Margin area. In this way, a Lagrangian model (LTRANS) was used with oceanic model (ROMS) results to show the locations where particle accumulation/dispersion occurs at the end of their paths, and whether they are influenced by the periods under analysis. Trajectories of particles initially released in the Tejo and Sado zones were simulated, i.e., the path of each particle during six bimonthly periods over a year (1991). In each zone, two sets of 400 particles were released at two different points, with intervals of 30 to 30 minutes. The areas chosen for this study were based on vessels route zones and likely discharge points. The trajectories obtained were analyzed to evaluate their behavior, namely their dispersion and accumulation points, as well as the evidence of some seasonal sign. The conclusions suggest a seasonal sign, i.e. in late spring and summer particles tend to stay further away from the coast, while in late autumn and winter particles tend to accumulate near the source point or origin. Results show that many particles that released from the Sado area can reach the Costa Vicentina, and possibly may contribute to the concentrations of microplastics found in this region. On the other hand, these results confirm that usually in winter/autumn there is a higher concentration of microplastics and that particles accumulate near the coast, especially in winter.
Marine pollution related with plastics is considered one of the most serious environmental problems on a global scale, being a topic of greater relevance on the international agenda. The characterization of plastics has been the subject of several studies, but the component of monitoring of dispersion patterns is practically non-existent in the Iberian Peninsula region. The objective of this study was to combine modelling techniques for a first study of the concentration/dispersion of plastics at the scale of the Portuguese Continental Margin area. In this way, a Lagrangian model (LTRANS) was used with oceanic model (ROMS) results to show the locations where particle accumulation/dispersion occurs at the end of their paths, and whether they are influenced by the periods under analysis. Trajectories of particles initially released in the Tejo and Sado zones were simulated, i.e., the path of each particle during six bimonthly periods over a year (1991). In each zone, two sets of 400 particles were released at two different points, with intervals of 30 to 30 minutes. The areas chosen for this study were based on vessels route zones and likely discharge points. The trajectories obtained were analyzed to evaluate their behavior, namely their dispersion and accumulation points, as well as the evidence of some seasonal sign. The conclusions suggest a seasonal sign, i.e. in late spring and summer particles tend to stay further away from the coast, while in late autumn and winter particles tend to accumulate near the source point or origin. Results show that many particles that released from the Sado area can reach the Costa Vicentina, and possibly may contribute to the concentrations of microplastics found in this region. On the other hand, these results confirm that usually in winter/autumn there is a higher concentration of microplastics and that particles accumulate near the coast, especially in winter.
Descrição
Tese de mestrado em Ciências Geofísicas (Meteorologia e Oceanografia), Universidade de Lisboa, Faculdade de Ciências, 2020
Palavras-chave
Poluição Lixo marinho Microplásticos Costa ibérica Modelo oceânico Modelo Lagrangiano Trajetórias de partículas Correntes marinhas Teses de mestrado - 2020