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Authors
Abstract(s)
As alterações climáticas tornaram-se um dos assuntos ambientais mais preocupantes da atualidade, pois os seus efeitos transpõem todas as fronteiras, sejam elas naturais ou antrópicas. Atualmente a grande generalidade da comunidade científica justifica a agudização das alterações climáticas às elevadas emissões dos Gases do Efeito Estufa, como o dióxido de carbono. Muitas formas de mitigar este efeito estão sendo estudadas, e entre elas tem surgido o fomento de espaços verdes urbanos enquanto potenciais sumidouros de CO2. Neste estudo procurou-se avaliar o potencial de um espaço verde relvado localizado na cidade de Bragança, região de Trás-os-Montes no norte de Portugal, como sumidouro de carbono, recorrendo à medição da transferência de dióxido de carbono através da interface atmosfera/superfície num espaço relvado, submetido a cortes regulares, durante o período compreendido entre fevereiro e junho de 2021. Os fluxos de CO2 foram medidos em contínuo com recurso ao sistema LI-8100A da LI-COR Biosciences ®, equipado com câmara transparente. O estudo envolveu também a monitorização de parâmetros edáficos, meteorológicos e, ainda, de parâmetros vegetativos como a percentagem de coberto vegetal e a biomassa produzida. Os resultados obtidos mostram a existência de um padrão intradiário expectável em que a superfície relvada se comporta como sumidouro durante uma parte considerável das horas solares e como emissor no período complementar. Este padrão foi visível ao longo do período de observação, mas marcado por uma diminuição das capacidades absorção de CO2 pela superfície e, simultaneamente, pelo aumento das emissões deste constituinte, ao longo do período de observação. Em termos médios, a superfície comportou-se como fonte de CO2 durante o período de avaliação, com um fluxo líquido de emissão de aproximadamente 0,7 g C m-2 d-1. Os resultados demonstraram igualmente uma forte relação entre os parâmetros do solo, vegetação e meteorológicos na magnitude e variabilidade dos fluxos de CO2, sendo os fatores que mais favoreceram a absorção a radiação solar, temperatura do solo, temperatura do ar ambiente e fitovolume e os que mais promoveram as emissões a precipitação, a humidade relativa do ar e o teor de humidade do solo. Com os modelos matemáticos multiregressivos desenvolvidos foi também possível demonstrar a capacidade preditiva de fluxos de CO2 a partir da utilização exclusiva de parâmetros apenas metereológicos ou de parâmetros edafoclimáticos e vegetativos.
The climate changes became one of the most worrying environmental issues today, as their effects cross all borders, whether natural or anthropogenic. Currently, the great generality of the scientific community justifies the aggravation of climate changes to the high categories of greenhouse gases, such as carbon dioxide. Many ways to mitigate this effect are being studied, and among them has emerged the promotion of urban green spaces as potential CO2 sinks. In this study we plan to evaluate the potential of a green grassy space located in the city of Bragança, Trás-os-Montes region in northern Portugal, as a carbon sink, using the reference of carbon dioxide transfer through the atmosphere / surface in a lawn area, submitted to regular cuts, during the period between February and June 2021. CO2 fluxes were measured continuously using the LI-COR Biosciences ® LI- 8100A system, equipped with a transparent chamber. The study also involved the analysis of edaphic and meteorological parameters and also of vegetative parameters such as the percentage of vegetation cover and the biomass covered. The results found show the existence of an expected intraday pattern in which the grassed surface behaves as a sink during a substantial part of the solar hours and as an emitter in the complementary period. This pattern was visible throughout the observation period, but marked by a reduction in the capacity of CO2 absorption by the surface and, at the same time, by the increase emission of this constituent, throughout the observation period. In average terms, the surface behaved as a source of CO2 during the evaluation period, with a net emission flux of approximately 0.7 g C m-2 d-1. The results also showed a strong relationship between soil, vegetation and meteorological parameters in the magnitude and variability of CO2 fluxes, being the factors that most favored the absorption solar radiation, soil temperature, ambient air temperature and phytovolume and those that most promoted emission precipitacion, the relative humidity of the air and the moisture content of the soil. With the developed multiregressive mathematical models, it was also possible to demonstrate the predictive capacity of CO2 fluxes from the exclusive use of meteorological parameters only or edaphoclimatic and vegetative parameters.
The climate changes became one of the most worrying environmental issues today, as their effects cross all borders, whether natural or anthropogenic. Currently, the great generality of the scientific community justifies the aggravation of climate changes to the high categories of greenhouse gases, such as carbon dioxide. Many ways to mitigate this effect are being studied, and among them has emerged the promotion of urban green spaces as potential CO2 sinks. In this study we plan to evaluate the potential of a green grassy space located in the city of Bragança, Trás-os-Montes region in northern Portugal, as a carbon sink, using the reference of carbon dioxide transfer through the atmosphere / surface in a lawn area, submitted to regular cuts, during the period between February and June 2021. CO2 fluxes were measured continuously using the LI-COR Biosciences ® LI- 8100A system, equipped with a transparent chamber. The study also involved the analysis of edaphic and meteorological parameters and also of vegetative parameters such as the percentage of vegetation cover and the biomass covered. The results found show the existence of an expected intraday pattern in which the grassed surface behaves as a sink during a substantial part of the solar hours and as an emitter in the complementary period. This pattern was visible throughout the observation period, but marked by a reduction in the capacity of CO2 absorption by the surface and, at the same time, by the increase emission of this constituent, throughout the observation period. In average terms, the surface behaved as a source of CO2 during the evaluation period, with a net emission flux of approximately 0.7 g C m-2 d-1. The results also showed a strong relationship between soil, vegetation and meteorological parameters in the magnitude and variability of CO2 fluxes, being the factors that most favored the absorption solar radiation, soil temperature, ambient air temperature and phytovolume and those that most promoted emission precipitacion, the relative humidity of the air and the moisture content of the soil. With the developed multiregressive mathematical models, it was also possible to demonstrate the predictive capacity of CO2 fluxes from the exclusive use of meteorological parameters only or edaphoclimatic and vegetative parameters.
Description
Mestrado de dupla diplomação com a UTFPR, Universidade Tecnológica Federal do Paraná
Keywords
Fluxos de CO2 Alterações ambientais Norte interior de Portugal